From MAILER-DAEMON at ctiosz.ctio.noao.edu Thu Mar 7 22:46:21 2002 From: MAILER-DAEMON at ctiosz.ctio.noao.edu (Mail System Internal Data) Date: Thu Jul 29 11:52:02 2004 Subject: DON'T DELETE THIS MESSAGE -- FOLDER INTERNAL DATA Message-ID: This text is part of the internal format of your mail folder, and is not a real message. It is created automatically by the mail system software. If deleted, important folder data will be lost, and it will be re-created with the data reset to initial values. From vince at ctecphotonics.com Mon Dec 9 11:35:00 2002 From: vince at ctecphotonics.com (kasprzak@sbcglobal.net) Date: Thu Jul 29 11:52:22 2004 Subject: CCD-world: TI Impactron CCDs Message-ID: <200212091858.gB9IwIW21221@astro.ku.dk> The following was posted to CCD-world: Do you have any insight as to the problem of requiring extra low noise clocks for the multiplying register. Since these clock levels determine the gain factor, noisy clocks will equate to noisy video. I believe that this is evident from the different SNR specs for multiplication off versus multiplication on. Does anyone have designs for low noise and zero glitch clocks for this application? Long term clock level stability could also be a problem concerning gain stability. Vince Kasprzak -----Original Message----- From: Craig D Mackay To: CCD-world@astro.ku.dk Date: Monday, December 09, 2002 7:35 AM Subject: Re: CCD-world: TI Impactron CCDs The following was posted to CCD-world: Dear Roland I managed to try one of the cameras that uses the TC253 CCD from Texas Instruments. The system that I tried only had available and video output. It came with a built-in peltier cooler, which I think allowed it to be chilled to approximately 0 centigrade. The camera appeared to work well, better than I feared it might do, with good performance at really quite low signal levels. The data sheet for the device contains some rather curious features. Although Texas normally use single phase image area structures, in this case they have used a two phase structure although still with an additional virtual phase in the pixels. The data sheet, worryingly, says that you have to have different voltages for the high and low levels of each clock electrode. As there are seven of these it needs 14 different clock supply voltages to run the camera! The nominal voltage for the multiplying register is 13.6 volts, with an absolute maximum rating of 15 volts. Although it does not explicitly states this, the typical charge multiplication gained which is given as 30 and which I assume occurs at the nominal multiplication gained voltage. This would imply that the gain could only be set to a bit more than 30. The data sheet says that a gain of 100 is not guaranteed. Nevertheless the experience that I had with their camera suggests that really quite high gains can be had from the chip. Because I could not get inside the camera (I had to be held back) to find out what voltage was used for the multiplying clock electrode, the fact that I was getting a maximum gain of several hundred suggested that perhaps this voltage had been pushed above its official maximum rating. The question about the suitability of these devices for astronomical application will depend on how low the dark current can be with the appropriate cooling. At the temperature of the camera as supplied the dark current was clearly reduced significantly but was quite obviously completely dominated the output noise. It will be very interesting to see what happens to this device if it was cooled to a much lower temperature. The dark current would certainly be reduced but of course the effect of the virtual phase structure on parallel charge transfer efficiency and low temperatures would be a worry. Rumour also has it that Texas have another device using the same technology but 1024 by 1024 pixels in development. The conclusion from the tests that I ran were that this does seem to be a very promising device. At the prices that these are available (USD $ few hundred, even with an integrated peltier chiller) it must be worth a try. For those nervous of the whole business of driving these chips with a much higher clock voltage then if you look towards the end of the data sheet he was the schematic which will work with these devices. Note that if you want to use the same approach for driving the E2V devices then you will have to choose components which have a significantly higher working voltage such as those from Vishay Siliconix. Time for everybody who has been having an easy time working at pixel rates of a few hundred KHz maximum to get used to the fact that we are going to have to face up to the delights of working at pixel rates in the 10 - 30 MHz. It is not as hard as it might seem because there are large number of devices now available that a used for digital still cameras. Although they are single frame devices, if you want to run a 6 megapixel camera at several frames a second then you must read out pretty quickly. Best wishes Craig D. Mackay. Institute of Astronomy, University of Cambridge The following was posted to CCD-world: I wanted to ask if somebody has collected experience with the Texas Instruments TX253 family of low light level CCDs. They are fairly cheap (approx. USD 600) and require a much lower clock voltage (approx 17V) for the gain stage. See http://www.tij.co.jp/jsc/docs/disp/eng/impact/tc253-e.htm for details, datasheets etc. TI offers also a complete video camera with composite and digital output (http://www.tij.co.jp/jsc/docs/disp/eng/lineup-e.htm). Roland Reiss, ESO - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From rnt20 at cam.ac.uk Fri Jan 4 15:30:32 2002 From: rnt20 at cam.ac.uk (Bob Tubbs) Date: Thu Jul 29 11:52:22 2004 Subject: CCD-world: LLLCCD CCD65 results from the NOT Message-ID: <3C35BC88.62579841@cam.ac.uk> The following was posted to CCD-world: Dear All, I thought some people might be interested in some preliminary results using the zero read noise Marconi CCD65 at the NOT: http://www.mrao.cam.ac.uk/~rnt20/lllccd_results/ Hope that's of interest, Bob -- Bob Tubbs, Cavendish Astrophysics Group and Institute of Astronomy http://www.cus.cam.ac.uk/~rnt20 01223 337296(w) 01223 474306(h) - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From Paul.Jorden at marconi.com Mon Jan 7 16:48:07 2002 From: Paul.Jorden at marconi.com (Jorden, Paul) Date: Thu Jul 29 11:52:22 2004 Subject: CCD-world: LLLCCD CCD65 results from the NOT Message-ID: <4F826F960057D4118EC3009027E2453804D14EF6@whl17.eev.uk> The following was posted to CCD-world: Bob- thanks for the publicity! If anyone wants further information about the ccd65 chip (or the smaller WFS version- the ccd60 128*128 format) please contact me directly. Thanks. Best Wishes for 2002 to all ccd-worlders, Paul _________________________________________________________ Dr Paul Jorden, CCD Sensors, Marconi Applied Technologies Waterhouse Lane, Chelmsford, Essex, CM1 2QU, UK Tel: +44 (0)1245 -453458 (direct), -493493 (switchboard) Fax: 44 (0) 1245 453224 http://www.marconitech.com/ccds/ -----Original Message----- From: Bob Tubbs [mailto:rnt20@cam.ac.uk] Sent: 04 January 2002 14:31 To: CCD-world@astro.ku.dk Subject: CCD-world: LLLCCD CCD65 results from the NOT The following was posted to CCD-world: Dear All, I thought some people might be interested in some preliminary results using the zero read noise Marconi CCD65 at the NOT: http://www.mrao.cam.ac.uk/~rnt20/lllccd_results/ Hope that's of interest, Bob -- Bob Tubbs, Cavendish Astrophysics Group and Institute of Astronomy http://www.cus.cam.ac.uk/~rnt20 01223 337296(w) 01223 474306(h) - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From pamico at keck.hawaii.edu Wed Jan 16 18:23:31 2002 From: pamico at keck.hawaii.edu (Paola Amico) Date: Thu Jul 29 11:52:22 2004 Subject: CCD-world: Scientific Detectors for Astronomy Workshop - registration is ope n Message-ID: <8EA8A1A22061D4118AF20090278AE539011D25C1@ntserver.keck.hawaii.edu> The following was posted to CCD-world: Dear infrared and optical detector aficionados, the registration to the Scientific Detectors for Astronomy workshop, June 16-22, 2002 in Waimea, Hawaii, is available at http://www2.keck.hawaii.edu:3636/. Just follow the link at the bottom of the page. Many thanks & see you in Hawai'i! Paola Amico W.M. Keck Observatory Local Organizing Committee - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From dennish at rsinc.net Fri Jan 18 10:23:41 2002 From: dennish at rsinc.net (Dennis Haskvitz) Date: Thu Jul 29 11:52:22 2004 Subject: CCD-world: Job Posting Message-ID: The following was posted to CCD-world: Would you please post the following job opening. Thank you, Dennis CAMERA ENGINEERING DESIGN MANAGER Key Responsibilities: Lead a group of Camera Design Engineers in the development of high-speed CCD & CMOS Camera and Test Systems. Follow Corporate New Product Introduction Process & Design For Six Sigma Methodology to deliver high quality Product in a short Time-To-Market window. ? Product Development, Improvement & Maintenance of all Cameras & Test Systems of Corporate (legacy Reticon) ? System Design of all Electronic development, consisting of: ? Identifying the customer^?s Critical To Quality parameters. ? Specification & Interface Flow Down ? System Architecture ? Schedule, Performance & Cost of Development. ? Product Quality & compliance including Verification, Qualification and Validation ? Product release to Manufacturing and to the Market, according to corporate rules. Manage and actively be involved in Hardware, Software, Firmware and ? Continuously improve Camera department skills and talents, through retaining, training and hiring talented Engineers. ? Manage Outsourcing consultants & companies ? Use off-the-shelf solutions for quick time-to-market and to improve the efficiency of the department ? Capital Budgeting and planning. ? Maintain close communication with Management, Engineers, Customer, Manufacturing and Marketing. ? Manage and actively contribute in all design reviews related to the Camera or Sensor Development & Test. ? Owns the modularization of our designs to increase the efficiency of our Engineering Department. ? Sets an example of high standard of work ethics and performance. Essential Knowledge and Skills: ? BS. EEng or higher, with at least 8 years experience in digital camera designs ? Digital & Analog Hardware design, plus good Firmware & Software experience. ? Good understanding of CCD & CMOS sensors device physics, and digital image analysis and processing. ? Good Computer skills using Excel, Word and Ms Project ? Knowledge in some of the following: Six Sigma, ISO9001, Kaisen, Design For Manufacturing, Design For Six Sigma, Radiometry, Thermal Management, Mechanical issues, Optics, Risk Management, Cost Accounting and Program Management. ? Excellent written and oral communication skills - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From Gene at adept-ic.com Fri Feb 1 17:16:19 2002 From: Gene at adept-ic.com (Gene Atlas) Date: Thu Jul 29 11:52:22 2004 Subject: CCD-world: Surplus CCDs Message-ID: <5.1.0.14.0.20020201140724.00b12a98@mail> The following was posted to CCD-world: An item that might be of interest to the members: We have a small selection of astronomy grade CCD devices of various sizes at reasonable prices. These devices range in size from 256x256 to 4096x4096. For those who might be interested, please contact me directly at Gene@adept-ic.com. Gene Atlas - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From reynolds at as.arizona.edu Mon Feb 4 15:41:29 2002 From: reynolds at as.arizona.edu (robert reynolds) Date: Thu Jul 29 11:52:22 2004 Subject: CCD-world: Metric nuts for mounting Marconi CCD's Message-ID: <3C5F0009.CAD24373@as.arizona.edu> The following was posted to CCD-world: I'm getting ready to mount a Marconi CCD44-82, which has integral studs made of Invar, and want to find out what material others have used for the mating nuts (metric size M3 x 0.5). Some of the issues involved are galling/cold welding of similar materials, outgassing of plating/lubricating materials, etc. Has anybody out there mounted these devices, and if so what kind of nuts did you use ? -- Robert O. Reynolds University Of Arizona (520) 621-1833 phone Steward Observatory (520) 621-9843 fax 933 N. Cherry Ave. Room N430 email: reynolds@as.arizona.edu Tucson, AZ 85721 - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From bmcleod at cfa.harvard.edu Tue Feb 5 10:32:34 2002 From: bmcleod at cfa.harvard.edu (Brian McLeod) Date: Thu Jul 29 11:52:22 2004 Subject: CCD-world: Metric nuts for mounting Marconi CCD's References: <3C5F0009.CAD24373@as.arizona.edu> Message-ID: <3C5FED02.50564E3E@cfa.harvard.edu> The following was posted to CCD-world: Robert, We have been using custom nuts made of Invar to mount CCD42-90s which have the same style package. The nut is a cylinder with a slot cut in the top, tall enough that it is taller than the stud when fully tightened. So far we have encountered no problems with galling. We have occasionally found that the stud itself gets loose in the CCD package when we remove the nut, so it's worth paying attention to that. You might have to retighten it -- carefully! We have made a custom tool for that as well. Brian > > I'm getting ready to mount a Marconi CCD44-82, which has integral studs > made of Invar, and want to find out what material others have used for > the mating nuts (metric size M3 x 0.5). Some of the issues involved are > galling/cold welding of similar materials, outgassing of > plating/lubricating materials, etc. Has anybody out there mounted these > devices, and if so what kind of nuts did you use ? -- Brian McLeod Phone: 1-617-495-7023 Center for Astrophysics, MS20 FAX: 1-617-495-7467 60 Garden Street Email: bmcleod@cfa.harvard.edu Cambridge, MA 02138 USA - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From rmg at astro.caltech.edu Tue Feb 5 09:32:55 2002 From: rmg at astro.caltech.edu (Rich Goeden) Date: Thu Jul 29 11:52:22 2004 Subject: CCD-world: Metric nuts for mounting Marconi CCD's References: <3C5F0009.CAD24373@as.arizona.edu> Message-ID: <3C600937.EB524C17@astro.caltech.edu> The following was posted to CCD-world: We have used stainless steel M3 nuts to mount two of the Marconi CCD44-82 devices with no evidence of galling etc. We have gone through several assembly cycles. The nuts are not plated, and washed with acetone and alcohol before assembly. No lubricant is used. Rich Goeden Caltech Astronomy rmg@astro.caltech.edu robert reynolds wrote: > > The following was posted to CCD-world: > > I'm getting ready to mount a Marconi CCD44-82, which has integral studs > made of Invar, and want to find out what material others have used for > the mating nuts (metric size M3 x 0.5). Some of the issues involved are > galling/cold welding of similar materials, outgassing of > plating/lubricating materials, etc. Has anybody out there mounted these > devices, and if so what kind of nuts did you use ? > -- > Robert O. Reynolds > University Of Arizona (520) 621-1833 phone > Steward Observatory (520) 621-9843 fax > 933 N. Cherry Ave. Room N430 email: reynolds@as.arizona.edu > Tucson, AZ 85721 > > - -- CCD-world -- -- > CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk > Standard replies will go to the list; address personal replies manually. > For more information, please go to: http://www.not.iac.es/CCD-world/ - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From tabbott at not.iac.es Tue Feb 5 17:41:01 2002 From: tabbott at not.iac.es (Tim Abbott) Date: Thu Jul 29 11:52:22 2004 Subject: CCD-world: Appropriate Use of List? Message-ID: The following was posted to CCD-world: Hi All, I have just received the following request: > I recently left my job as the lead designer of CCD cameras for remote > sensing and machine vision applications. I'd like to make my design > services available on a contract basis to the greater imaging community, > is this an appropriate forum to do so? I have to admit that I can see almost equal arguments in either direction. The submitter is not specifically aiming at the astronomy market and he may be one of many; if I let his through, I have to let them all through (well, no I don't, but you see what I mean?). On the other hand, the community can possibly benefit from knowing that such skills exist and are available, some of us might have side projects pending which could be farmed out. So, I shall sit firmly on the fence for a couple of days. If there is no obvious consensus, or no particular objection, I'll let it through. (I won't let people's comments on this topic through, unless specifically requested, since this is administrative clutter.) Cheers, Tim -- Tim Abbott, Astronomer-in-Charge, Nordic Optical Telescope tabbott@not.iac.es, http://www.not.iac.es/~tabbott/, +34 922 425 472 Roque de Los Muchachos & Santa Cruz de La Palma, Canary Islands, Spain - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From PCDH at watson.ibm.com Tue Feb 5 18:18:10 2002 From: PCDH at watson.ibm.com (Phil Hobbs) Date: Thu Jul 29 11:52:23 2004 Subject: CCD-world: Metric nuts for mounting Marconi CCD's Message-ID: <200202052220.g15MKdO38216@sp1n293en1.watson.ibm.com> A non-text attachment was scrubbed... Name: not available Type: text Size: 897 bytes Desc: not available Url : http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20020205/392df924/attachment.bat From reynolds at as.arizona.edu Thu Feb 7 13:56:46 2002 From: reynolds at as.arizona.edu (robert reynolds) Date: Thu Jul 29 11:52:23 2004 Subject: CCD-world: Metric nuts for mounting Marconi CCD's References: <3C5F0009.CAD24373@as.arizona.edu> <3C600937.EB524C17@astro.caltech.edu> Message-ID: <3C62DBFE.D7D1F092@as.arizona.edu> The following was posted to CCD-world: Rich; Thanks for your reply. Are you torquing the nuts per the Marconi mounting notes (I'm assuming they're more likely to gall if tightened than if just loosely threaded on.)? Robert Reynolds Rich Goeden wrote: > The following was posted to CCD-world: > > We have used stainless steel M3 nuts to mount two of the Marconi > CCD44-82 devices with no evidence of galling etc. We have gone > through several assembly cycles. The nuts are not plated, and washed > with acetone and alcohol before assembly. No lubricant is used. > > Rich Goeden > Caltech Astronomy > rmg@astro.caltech.edu > > robert reynolds wrote: > > > > The following was posted to CCD-world: > > > > I'm getting ready to mount a Marconi CCD44-82, which has integral studs > > made of Invar, and want to find out what material others have used for > > the mating nuts (metric size M3 x 0.5). Some of the issues involved are > > galling/cold welding of similar materials, outgassing of > > plating/lubricating materials, etc. Has anybody out there mounted these > > devices, and if so what kind of nuts did you use ? > > -- > > Robert O. Reynolds > > University Of Arizona (520) 621-1833 phone > > Steward Observatory (520) 621-9843 fax > > 933 N. Cherry Ave. Room N430 email: reynolds@as.arizona.edu > > Tucson, AZ 85721 > > > > - -- CCD-world -- -- > > CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk > > Standard replies will go to the list; address personal replies manually. > > For more information, please go to: http://www.not.iac.es/CCD-world/ > - -- CCD-world -- -- > CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk > Standard replies will go to the list; address personal replies manually. > For more information, please go to: http://www.not.iac.es/CCD-world/ -- Robert O. Reynolds University Of Arizona (520) 621-1833 phone Steward Observatory (520) 621-9843 fax 933 N. Cherry Ave. Room N430 email: reynolds@as.arizona.edu Tucson, AZ 85721 - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From tfe at tina.aip.de Fri Feb 8 15:24:32 2002 From: tfe at tina.aip.de (Thomas Fechner) Date: Thu Jul 29 11:52:23 2004 Subject: CCD-world: Jobin Yvon CCD2000 controller Message-ID: The following was posted to CCD-world: Hi all, last month I got an old Yvon CCD2000 controller with a Site 2kx0.8K CCD. It will be usefull for our laboratory work, but a quick look at the software shows me that only DOS functionality is provided. Does anyone use this controller anymore and perhaps has written an unix (linux) driver? All suggestions are welcome Thanks in advance Th. Fechner -------------------------------------------------------------------------- Thomas Fechner tfechner@aip.de Astrophysikalisches Institut Potsdam Tel. ++49+331/7499412 Optische Instrumente Fax. ++49+331/7499436 An der Sternwarte 16 D-14482 Potsdam - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From tabbott at not.iac.es Wed Feb 13 13:00:36 2002 From: tabbott at not.iac.es (Tim Abbott) Date: Thu Jul 29 11:52:23 2004 Subject: CCD-world: Postings from job seekers and services available Message-ID: The following was posted to CCD-world: Dear CCD-world, The responses on the issue of whether or not to allow postings from people seeking employment or offering services of direct relevance to the interests of CCD-world was precisely balanced between the "Yays" and the "Nays". Since I like to say "Yay" myself more than "Nay" I will therefore allow them through at the rate of no more than one per week (one poster points out that we're unlikely to get more than this), first come, first served; and each poster may send out no more than once per year. I will also set up an area in the CCD-world web pages for posting curriculum vitae where the limit will be my time. (Another poster also pointed out that SPIE has an area for posting resumes and that will probably reach a wider audience.) I think that is reasonable and I hope you agree. Cheers, Tim Moderator, CCD-world -- Tim Abbott, Astronomer-in-Charge, Nordic Optical Telescope tabbott@not.iac.es, http://www.not.iac.es/~tabbott/, +34 922 425 472 Roque de Los Muchachos & Santa Cruz de La Palma, Canary Islands, Spain - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From jsg at aaoepp.aao.gov.au Thu Feb 14 09:36:27 2002 From: jsg at aaoepp.aao.gov.au (Jason Griesbach) Date: Thu Jul 29 11:52:23 2004 Subject: CCD-world: Fast clock circuit Message-ID: <3C6ADC5B.111F53CB@aaoepp.aao.gov.au> The following was posted to CCD-world: Dear CCD-World: I am in the process of redesigning a CCD controller for astronomy CCDs, and this controller is intended to drive a variety of CCDs including the Tek TK1024, MIT/LL CCID-20, and Marconi (EEV) CCD42-80. I am trying to decide what kind of fast (serial register) clocks to design into the controller and want to know what others are using. Either I can use an RC-filtered clock, or I can use current sources to charge/discharge a capacitor for a more linear ramp on the clock transitions. Obviously, the latter is more complicated and I want to know if it is necessary. Any suggestions? Best Regards, Jason Griesbach Anglo-Australian Observatory jsg@aaoepp.aao.gov.au -- Jason Griesbach, electronics engineer Anglo-Australian Observatory PO Box 296 Epping, NSW 1710 Australia Phone: +61-2-9372-4886 Fax: +61-2-9372-4880 e-mail: jsg@aaoepp.aao.gov.au - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From preben at ursa.astro.ku.dk Thu Feb 14 09:05:14 2002 From: preben at ursa.astro.ku.dk (Preben Noerregaard) Date: Thu Jul 29 11:52:23 2004 Subject: CCD-world: Fast clock circuit In-Reply-To: <3C6ADC5B.111F53CB@aaoepp.aao.gov.au> Message-ID: The following was posted to CCD-world: Hi Jason We have reasently redesigned the clock-drivers in our controller for the same purpose, - more speed. We take the advantage of new opamps originally intended as xDSL drivers. We use LT parts (the 1795), being able to drive cap. loads at 500mA. It is used in a Sallen-key configuration implementing a 2. order Chebyshev filter. I guess you could regard my solution as something in between your two proposals .. Cheers, Preben -------------------------------------------- Preben Noerregaard Copenhagen University Observatory Juliane Maries Vej 30, DK 2100 Copenhagen O Tel: +45 35 32 59 44, Fax: +45 35 32 59 89 email: preben@astro.ku.dk -------------------------------------------- - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From dfb at mrao.cam.ac.uk Thu Feb 14 13:02:25 2002 From: dfb at mrao.cam.ac.uk (David Buscher) Date: Thu Jul 29 11:52:23 2004 Subject: CCD-world: Fast clock circuit In-Reply-To: Message-ID: The following was posted to CCD-world: I would be interested in understanding the argument for using a Chebyshev filter rather than a Bessel filter in this case: is the ideal response of a clock waveform best considered in terms of the suppression of high frequencies or in the terms of the settling time, or do we perhaps want to encourage some overshoot? David On Thu, 14 Feb 2002, Preben Noerregaard wrote: > The following was posted to CCD-world: > > Hi Jason > We have reasently redesigned the clock-drivers in our > controller for the same purpose, - more speed. > > We take the advantage of new opamps originally > intended as xDSL drivers. We use LT parts (the 1795), > being able to drive cap. loads at 500mA. It is used > in a Sallen-key configuration implementing a 2. order > Chebyshev filter. > > I guess you could regard my solution as something in between > your two proposals .. > > Cheers, Preben > > -------------------------------------------- > Preben Noerregaard > Copenhagen University Observatory > Juliane Maries Vej 30, DK 2100 Copenhagen O > Tel: +45 35 32 59 44, Fax: +45 35 32 59 89 > email: preben@astro.ku.dk > -------------------------------------------- > > - -- CCD-world -- -- > CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk > Standard replies will go to the list; address personal replies manually. > For more information, please go to: http://www.not.iac.es/CCD-world/ > - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From preben at ursa.astro.ku.dk Thu Feb 14 14:42:55 2002 From: preben at ursa.astro.ku.dk (Preben Noerregaard) Date: Thu Jul 29 11:52:23 2004 Subject: CCD-world: Fast clock circuit In-Reply-To: Message-ID: The following was posted to CCD-world: Hi David You are right, - Bessel is best. We want optimum compromise between bandwidth cutoff and settling, and certainly no overshoot! Thanks, Preben -------------------------------------------- Preben Noerregaard Copenhagen University Observatory Juliane Maries Vej 30, DK 2100 Copenhagen O Tel: +45 35 32 59 44, Fax: +45 35 32 59 89 email: preben@astro.ku.dk -------------------------------------------- - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From jsg at aaoepp.aao.gov.au Fri Feb 15 18:06:41 2002 From: jsg at aaoepp.aao.gov.au (Jason Griesbach) Date: Thu Jul 29 11:52:23 2004 Subject: CCD-world: Fast clock circuit References: Message-ID: <3C6CA571.F146E1A1@aaoepp.aao.gov.au> The following was posted to CCD-world: Hi Preben and David, Thanks for your input. A second order Bessel filter is a good clock option that I had overlooked. I have two questions relating to that: 1. Do your clocks have programmable rise/fall times? Our parallel clocks are programmable, but I wasn't sure if the serial clocks should be. Incidentally, another reader strongly recommended programmability. 2. A filter won't normally allow for setting of rise times independently of fall times. Do you find that this limits the CCD performance? (I'm terribly new at this game!) Thanks. Jason Preben Noerregaard wrote: > The following was posted to CCD-world: > > Hi David > You are right, - Bessel is best. We want optimum > compromise between bandwidth cutoff and settling, > and certainly no overshoot! > Thanks, Preben > > -------------------------------------------- > Preben Noerregaard > Copenhagen University Observatory > Juliane Maries Vej 30, DK 2100 Copenhagen O > Tel: +45 35 32 59 44, Fax: +45 35 32 59 89 > email: preben@astro.ku.dk > -------------------------------------------- > > - -- CCD-world -- -- > CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk > Standard replies will go to the list; address personal replies manually. > For more information, please go to: http://www.not.iac.es/CCD-world/ -- Jason Griesbach, electronics engineer Anglo-Australian Observatory PO Box 296 Epping, NSW 1710 Australia Phone: +61-2-9372-4886 Fax: +61-2-9372-4880 e-mail: jsg@aaoepp.aao.gov.au - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From bgoodin at unex.ucla.edu Sun Feb 17 16:45:56 2002 From: bgoodin at unex.ucla.edu (Goodin, Bill) Date: Thu Jul 29 11:52:23 2004 Subject: CCD-world: UCLA spring short courses in Imaging and Electronics Message-ID: <5B229CD021ECD411B17D00010254DBB101B89AAC@www3.unex.ucla.edu> The following was posted to CCD-world: > This spring, UCLA Extension will present the following imaging and > electronics short courses on the UCLA campus in Los Angeles. > > April 2-3, 2002, "Understanding BSIM3 MOSFET Models". The instructor is > William Liu, PhD, Member of Technical Staff, Maxim Integrated Products, > $1195. > http://www.unex.ucla.edu/shortcourses/spring2002/bsim3_mosfet_sp02.htm > > April 4-5, 2002, "Analog Signal Processing". The instructor is Mahmoud > Wagdy, PhD, Professor, Electrical Engineering, California State > University, Long Beach, $1095. > http://www.unex.ucla.edu/shortcourses/spring2002/analog_signal_pro_sp02.ht > m > > April 29-May 3, 2002, "Charge-Coupled Devices/CMOS Imaging Sensors and > Cameras". The instructors are James R. Janesick, MS, Sarnoff Research; > Terrence Lomheim, PhD, The Aerospace Corporation; and > Bedrabata Pain, PhD, Jet Propulsion Laboratory, $1795. > http://www.unex.ucla.edu/shortcourses/spring2002/charge_coupled_sp02.htm > > May 6-7, 2002, "Laser Fundamentals and Applications". The instructor is > Hagop Injeyan, PhD, Technical Fellow, TRW, $995. > http://www.unex.ucla.edu/shortcourses/spring2002/laser_fundamental_app_sp0 > 2.htm > > May 6-7, 2002, "JPEG 2000: Second-Generation Standard for Image > Compression". The instructor is Michael Marcellin, PhD, Professor, John > M. Leonis Litton Industries Distinguished Professor of Engineering, > University of Arizona, Tucson, $995. > http://www.unex.ucla.edu/shortcourses/spring2002/jpeg2000_sec_gen_comp_sp0 > 2.htm > > May 8-10, 2002, "Multimedia/Video Coding, Streaming, and Search Standards: > MPEG-4 and MPEG-7". The instructors are Atul Puri, PhD, Principal > Technical Staff Member, Image Processing Research Department, AT&T > Laboratories, and A. Murat Tekalp, PhD, Professor, Electrical and Computer > Engineering, University of Rochester, $1595. > http://www.unex.ucla.edu/shortcourses/spring2002/multi_video_code_sp02.htm > > May 13-14, 2002, "System Modeling and Diagnostics Using Bayesian > Networks". The instructor is Adnan Darwiche, PhD, Assistant Professor, > Computer Science Department, UCLA, $995. > http://www.unex.ucla.edu/shortcourses/spring2002/system_modeling_diag_sp02 > .htm > > > For additional information and complete descriptions of all short courses, > please visit our website, http://uclaextension.org/shortcourses/, > > or contact Marcus Hennessy at: > (310) 825-1047 > (310) 206-2815 fax > mhenness@unex.ucla.edu > > All of these courses may also be presented on-site at company locations. > - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From Paul.Jorden at marconi.com Mon Feb 18 11:22:06 2002 From: Paul.Jorden at marconi.com (Jorden, Paul) Date: Thu Jul 29 11:52:23 2004 Subject: CCD-world: FW: L3vision astronomy chips Message-ID: <200203060027.g260R6o17235@ursa.astro.ku.dk> The following was posted to CCD-world: As many of you know, we now sell the ccd65 (TV format) and ccd60 (128*128) L3Vision chips, with sub-electron noise. Contact me directly if you need more info. [512*512 and 1024*1024 scientific formats are also in development] This message is to discuss potential interest in other formats, using the same L3vision technology: A. We could make a 2k*4k thinned chip with the same technology. I would be interested in comments on the desirability of this. I assume such a chip would be particularly desirable for high dispersion spectroscopy (ie lowest noise). B. We are also considering making a multi-output L3vision AO chip, for fast frame rates. The ccd60 reads at > 500 frames/sec from one output, but only has a limited format. To achieve the same frame rate for say a 512*512 format would need perhaps 16 outputs (at> 10 MHz). We could make such a chip- but would you want to operate it (& build controllers for it?) Or we could build a simple drive unit that gave a full-frame readout at maximum rate. Any interest? I'll welcome any discussion on the desirablility of such devices, and am happy to discuss the issues directly or via ccd-world, as well as at the Keck ccd mtg in June. Hope to see many of you there. Regards, Paul J _________________________________________________________ Dr Paul Jorden, CCD Sensors, Marconi Applied Technologies Waterhouse Lane, Chelmsford, Essex, CM1 2QU, UK Tel: +44 (0)1245 -453458 (direct), -493493 (switchboard) Fax: 44 (0) 1245 453224 http://www.marconitech.com/ccds/ - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From gleeson at gv.net Mon Feb 18 12:33:16 2002 From: gleeson at gv.net (Greg Leeson) Date: Thu Jul 29 11:52:23 2004 Subject: CCD-world: Design Services Available Message-ID: <3C7156FC.24A001E6@gv.net> The following was posted to CCD-world: I have recently left my job as lead design engineer for a commercial manufacturer of CCD cameras and would like to offer my services on a contract basis. I have experience designing both line and area scan cameras using sensors from Kodak, Sony, T.I. and EG&G. The scope of my work includes analog and digital (FPGA) design, digital image processing, low noise power supplies, embedded microprocessors and embedded firmware in C. My commercial designs are currently being used in aerial remote sensing, precision machine vision and other industrial applications. I am also working with clients on cameras for astronomy, retinal imaging and food inspection applications. My rates are quite reasonable. - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From G.F.W.Woodhouse at rl.ac.uk Wed Feb 20 16:33:23 2002 From: G.F.W.Woodhouse at rl.ac.uk (Woodhouse, GFW (Guy) ) Date: Thu Jul 29 11:52:23 2004 Subject: CCD-world: CCD World - Job notice Message-ID: <49F73BEED865D3119F8700902773C9F901466960@exchange09.rl.ac.uk> The following was posted to CCD-world: > Hi Tim, > > Would you mind putting this on CCD- world : > > Vacancies at Rutherford Appleton Laboratory, UK - VN2219: Detector > Physicists or Engineers > > Description : > > Within the Space Science and Technology Department, the CCD Technology > Group is responsible for the design and development of CCD and IR detector > instrumentation for a variety of space science, Earth observation, > planetary remote sensing, and ground-based astronomy instrumentation. The > Group is seeking two additional physicists or engineers with an interest > in detector systems. > > Duties : > > - Development and engineering of solid-state detector systems for space > science, Earth observation, and ground-based astronomy. > - Responsibility for setting up new detector facilities, and procuring > and/or developing detector readout systems for both specific projects and > R&D work. > - Leadership of instrument conceptual design, preparing project > proposals/reports, and attending/presenting at meetings. > > For further information, including how to apply, please see : > > http://www.clrc.ac.uk/Activity/JS=FALSE;CSS=FALSE;ACTIVITY=VNs;SECTION=151 > 4; > > Regards, Guy Woodhouse > --------------------------------------- > Room G-13 Building R25 tel : +44 1235 445 328 > Space Science & Technology Department fax : +44 1235 445 848 > Rutherford Appleton Laboratory > Chilton Didcot > Oxfordshire > OX11 0QX > UK - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From tylinski at pcez.com Tue Feb 26 11:26:01 2002 From: tylinski at pcez.com (George Tylinski) Date: Thu Jul 29 11:52:23 2004 Subject: CCD-world: Acres of Invar and 9.2 Mpel LCD display In-Reply-To: Message-ID: <200203011719.g21HJox28403@ursa.astro.ku.dk> The following was posted to CCD-world: Hello - I recently returned from a conference/trade show (SolidWorks World Conference, Las Vegas). At the show I learned of two items that may be of interest to this community: 1) A company that can produce very large Invar parts (or other metals) by powder metallurgy, at 100% density, in prototype quantities. Has been used successfully in vacuum applications. Daniel Zick, Chief Applications Engineer, 978-470-1620 (Massachusetts, USA) danzick@bodycote-imt.com. I'm sure it's not inexpensive, but to get a large Invar part with no grain direction and near-net shape (to minimize machining cold-working) is enabling for ultra-large format cameras, or telescope structures. http://www.bodycote-na.com/hip/index.htm 2) An incredible 204 pixel/inch monitor (3840x2400, 22.2 inch diag.) with stated 400:1 contrast, which looked much better than any CRT I've ever seen - like a magazine photo. You need their video board of course (ATI Fire GL4 or equivalent) but WHAT an image, and the uniformity holds up over a very wide angle unlike most flat panels. Sony Titus, 914-642-5017 (New York), sonyt@us.ibm.com. IBM is very interested in leading-edge applications like astronomy, and willing to price aggressively for the prestige. http://www.storage.ibm.com/lcd/products/md2229/md2229index.htm Best Regards, George Tylinski George Tylinski Mechanical Design & Analysis 503-515-3338 voice - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From daikens at suite224.net Thu Feb 28 12:13:09 2002 From: daikens at suite224.net (Dave Aikens) Date: Thu Jul 29 11:52:24 2004 Subject: CCD-world: EG Message-ID: <3C7E5715.2CF37029@suite224.net> The following was posted to CCD-world: I am looking for the technical specifications including pinout for an EG&G Reticon CCD chip #RA100X100A-2 or #RA100AAQ-011 circa 1996. I beleive it was used in a CCD camera. Any help would be greatly appreciated. Thanks in advence, Dave - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From marien at mpia-hd.mpg.de Mon Mar 4 12:48:03 2002 From: marien at mpia-hd.mpg.de (karl-Heinz Marien) Date: Thu Jul 29 11:52:24 2004 Subject: CCD-world: EG In-Reply-To: <3C7E5715.2CF37029@suite224.net> Message-ID: <5.1.0.14.0.20020304114011.00a6a3f8@pops2.mpia-hd.mpg.de> The following was posted to CCD-world: Hi Dave, I've got a Reticon "Image Sensing Products 1992/1993" data book. A device RA0100A however is described as a discrete photodiode array in a 24 pin DIP package. If you want info on it, send an email. Charly At 11:13 28.02.2002 -0500, you wrote: >The following was posted to CCD-world: > >I am looking for the technical specifications including pinout for an >EG&G Reticon CCD chip #RA100X100A-2 or #RA100AAQ-011 circa 1996. I >beleive it was used in a CCD camera. Any help would be greatly >appreciated. > >Thanks in advence, > >Dave > >- -- CCD-world -- -- >CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk >Standard replies will go to the list; address personal replies manually. >For more information, please go to: http://www.not.iac.es/CCD-world/ - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From wpk at saao.ac.za Tue Mar 5 13:06:57 2002 From: wpk at saao.ac.za (Willie Koorts) Date: Thu Jul 29 11:52:24 2004 Subject: CCD-world: Re: Mylar foil insulated CCD-cryostats? In-Reply-To: Message-ID: The following was posted to CCD-world: Hi Anton and others I just stumbled upon the reference I could not find 6 months ago. Anton's original question was about the pro's and con's of using multiple layers of mylar superinsulation and radiation shields. On Fri, 14 Sep 2001, I wrote: > I was trying to find an old mail to quote the exact numbers here, but > could not find it, but talking to Bill Ditsler at NOAO, Tucson years > ago, he mentioned about a case where someone came to him with a dewar > with short hold-time problems. After just stripping out all the > superinsulation and doing a minimal clean-out of the dewar (simply > wiping down the insides with acetone) he managed to improve the hold > time dramatically. (I don't want to quote any numbers here since I > cannot remember exactly but it was close to double the original hold > time, I seem to recall.) He actually wrote: "I've had a dewar that was purchased by someone that came to me with the request to solve their hold time problem. The dewar was stripped and cleaned of all superinsulation and all the glue that holds it, reassembled and pumped. No electropolishing or fine tuning of parts or processing to make them super clean was done. The hold time went from 6 hours to 36 hours." So the hold time was not doubled but increased 6-FOLD! Interestingly, he continues: "Now don't get me wrong. There is a place when a radiation shield, if you will, should be used ... if you have the room (and you can clean parts). A single layer or surface between the LN2 tank and the outside wall of the dewar will help control radiation losses. BUT ... IF you have highly polished surfaces on the inside wall of the outer dewar container and the surface of the LN2 tank, you don't need the shield either! I prove that every day with our dewars ... all twelve of them [back in 1995]. Again I must add that a good vacuum is necessary ... as good as you can get." I would be very interested to hear further opinions/experiences on adding/removing radiations shields. Regards Willie Mr. W.P. Koorts ( wpk@saao.ac.za ) South African Astronomical Observatory PO Box 9 Observatory 7935 South Africa Tel.(27) (21) 447 0025 Fax.(27) (21) 447 3639 World Wide Web ( Work ) http://www.saao.ac.za World Wide Web ( Personal ) http://www.saao.ac.za/~wpk/ - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From norup at astro.ku.dk Tue Mar 5 14:09:58 2002 From: norup at astro.ku.dk (=?iso-8859-1?Q?Anton_Norup_S=F8rensen?=) Date: Thu Jul 29 11:52:24 2004 Subject: CCD-world: Re: Mylar foil insulated CCD-cryostats? In-Reply-To: Message-ID: The following was posted to CCD-world: Hi Willie, and thanks for bringing this topic up again. I guess something must have gone very wrong in the radiation shield installation you describe. Either heavy outgassing or conductive short-cirquiting by the glue or insulation material. All the radiation shield experiments performed here have showed that they improve the insulation of the LN2 tank. Our tank surface is relatively dark, as it consists of unpolished stainless steel and copper welded together. This may account for some of the success using radiation shields. We have just got our first shiny LN2 tank back from electro-polishing, so that should not be a problem anymore. Here is a description of one of our experiments: One of our standard cryostats for 2k^2 detectors, with a LN2 capacity of 1.4l was placed on a weight, and the decrease in weight from evaporation of LN2 translated into heat transfer. No detector was installed, and no wires except for those required for temperature measurement. The cryostat window was replaced by an aluminium dummy. During the experiments, the vacuum was not quite good, about 10^-4 to 10^-5mBar, so gas conduction cannot be entirely eliminated. Wihout any radiation shield installed, the heat transport was 1.79W, a sum of radiation transport and conduction through the filling tube. With our standard 1-layer radiation shield, heat transport decreased to 0.93W. With a 15 layer mylar shield, heat transport further decreased to 0.47W. There are som pictures from this experiment at http://www.astro.ku.dk/~ijaf/optlab/cryo.html Other tests indicate that the heat transport through the filling tube and tank support is 0.3W, so the radiation loss is now quite small. Kind regards, Anton Norup Sorensen -------------------------------------------------------------------- Address : Ground-Based Astronomical Instrument Centre, IJAF Copenhagen University Observatory Niels Bohr Institute for Astronomy, Physics and Geophysics Juliane Maries Vej 30 DK-2100 Copenhagen OE , Denmark Phone : +45 353 25940 Fax : +45 353 25989 E-mail : norup@astro.ku.dk WWW : http://www.astro.ku.dk/~norup - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From Paul.Jorden at marconi.com Tue Mar 5 13:31:34 2002 From: Paul.Jorden at marconi.com (Jorden, Paul) Date: Thu Jul 29 11:52:24 2004 Subject: CCD-world: Re: Mylar foil insulated CCD-cryostats? Message-ID: <4F826F960057D4118EC3009027E2453804D1501A@whl17.eev.uk> The following was posted to CCD-world: my comment on this- if the dewar is 'bare' then you can get good results, especially by making everything shiny... as soon as you add a complex detector plate then the chances of higher radiation exchange can increase a lot. especially if the detector area is large and black pointing through the window. At RGO our dewars when delivered had ~ 40 hrs hold time (ie ~ 1.5W heat to a cold surface which was not as well wrapped up as Anton's. By the time we had added a cold plate, with some circuitry and the detectors it usually reduced to ~ 12 hrs. This was mainly radiation. There is no point in extreme superinsulation on the N2 can, if other parts of the cold assembly dominate. Paul _________________________________________________________ Dr Paul Jorden, CCD Sensors, Marconi Applied Technologies Waterhouse Lane, Chelmsford, Essex, CM1 2QU, UK Tel: +44 (0)1245 -453458 (direct), -493493 (switchboard) Fax: 44 (0) 1245 453224 http://www.marconitech.com/ccds/ -----Original Message----- From: Anton Norup S?rensen [mailto:norup@astro.ku.dk] Sent: 05 March 2002 12:10 To: ccd-world@astro.ku.dk Subject: CCD-world: Re: Mylar foil insulated CCD-cryostats? The following was posted to CCD-world: Hi Willie, and thanks for bringing this topic up again. I guess something must have gone very wrong in the radiation shield installation you describe. Either heavy outgassing or conductive short-cirquiting by the glue or insulation material. All the radiation shield experiments performed here have showed that they improve the insulation of the LN2 tank. Our tank surface is relatively dark, as it consists of unpolished stainless steel and copper welded together. This may account for some of the success using radiation shields. We have just got our first shiny LN2 tank back from electro-polishing, so that should not be a problem anymore. Here is a description of one of our experiments: One of our standard cryostats for 2k^2 detectors, with a LN2 capacity of 1.4l was placed on a weight, and the decrease in weight from evaporation of LN2 translated into heat transfer. No detector was installed, and no wires except for those required for temperature measurement. The cryostat window was replaced by an aluminium dummy. During the experiments, the vacuum was not quite good, about 10^-4 to 10^-5mBar, so gas conduction cannot be entirely eliminated. Wihout any radiation shield installed, the heat transport was 1.79W, a sum of radiation transport and conduction through the filling tube. With our standard 1-layer radiation shield, heat transport decreased to 0.93W. With a 15 layer mylar shield, heat transport further decreased to 0.47W. There are som pictures from this experiment at http://www.astro.ku.dk/~ijaf/optlab/cryo.html Other tests indicate that the heat transport through the filling tube and tank support is 0.3W, so the radiation loss is now quite small. Kind regards, Anton Norup Sorensen -------------------------------------------------------------------- Address : Ground-Based Astronomical Instrument Centre, IJAF Copenhagen University Observatory Niels Bohr Institute for Astronomy, Physics and Geophysics Juliane Maries Vej 30 DK-2100 Copenhagen OE , Denmark Phone : +45 353 25940 Fax : +45 353 25989 E-mail : norup@astro.ku.dk WWW : http://www.astro.ku.dk/~norup - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From atwood at mps.ohio-state.edu Tue Mar 5 09:09:34 2002 From: atwood at mps.ohio-state.edu (Bruce Atwood) Date: Thu Jul 29 11:52:24 2004 Subject: CCD-world: Re: Mylar foil insulated CCD-cryostats? References: Message-ID: <3C84C38E.43C63AE9@ohstpy.mps.ohio-state.edu> The following was posted to CCD-world: Just a quick comment on some aspects of dewars. The heat gain in a vacuum dewar is dominated by radiation at any pressure below 10e-5 Torr. Don't waste your time on techniques appropriate for very or ultra high vacuum. Second, heat loss by "conduction through the filling tube" is almost never a factor since the boil off gas normally passes through the fill tube. It takes 45 W-hr to boil a liter of LN2 and another 45 W-hr to heat the resulting gas from the boiling point to room temperature. The gas has plenty of "cooling power" One of the nice features of IR Labs dewars is the gas cooled radiation shield. It is not necessary to monitor the weight of dewars to measure either the LN2 consumption or power input, a cheap flow meter gives you an instantaneous measurement of consumption or power input. If you get one calibrated in cubic feet per hour that turns out to be almost exactly liters of liquid per day and multiplying by two gives power input in watts. Even with a detector as small as a 2k square the heat gain through the window is non trivial. Room temperature black body radiation is 45 mW/cm^2. Many CCDs are nearly black at 10 microns so they can soak up quite a bit of power coming from or through the window. Better yet, read : http://www.astronomy.ohio-state.edu/~isl/PAPERS/Aadsorb.htm Anton Norup S?rensen wrote: > The following was posted to CCD-world: > > Hi Willie, and thanks for bringing this topic up again. > > I guess something must have gone very wrong in the radiation shield > installation you describe. Either heavy outgassing or conductive > short-cirquiting by the glue or insulation material. > > All the radiation shield experiments performed here have showed that they > improve the insulation of the LN2 tank. Our tank surface is relatively dark, > as it consists of unpolished stainless steel and copper welded together. > This may account for some of the success using radiation shields. We have > just got our first shiny LN2 tank back from electro-polishing, so that should > not be a problem anymore. > > Here is a description of one of our experiments: > One of our standard cryostats for 2k^2 detectors, with a LN2 capacity of 1.4l > was placed on a weight, and the decrease in weight from evaporation of LN2 > translated into heat transfer. No detector was installed, and no wires except > for those required for temperature measurement. The cryostat window was > replaced by an aluminium dummy. During the experiments, the vacuum was not > quite good, about 10^-4 to 10^-5mBar, so gas conduction cannot be entirely > eliminated. > > Wihout any radiation shield installed, the heat transport was 1.79W, a sum > of radiation transport and conduction through the filling tube. > > With our standard 1-layer radiation shield, heat transport decreased to 0.93W. > > With a 15 layer mylar shield, heat transport further decreased to 0.47W. > There are som pictures from this experiment at > http://www.astro.ku.dk/~ijaf/optlab/cryo.html > Other tests indicate that the heat transport through the filling tube > and tank support is 0.3W, so the radiation loss is now quite small. > > Kind regards, > > Anton Norup Sorensen > -------------------------------------------------------------------- > Address : Ground-Based Astronomical Instrument Centre, IJAF > Copenhagen University Observatory > Niels Bohr Institute for Astronomy, Physics and Geophysics > Juliane Maries Vej 30 > DK-2100 Copenhagen OE , Denmark > Phone : +45 353 25940 Fax : +45 353 25989 > E-mail : norup@astro.ku.dk WWW : http://www.astro.ku.dk/~norup > > - -- CCD-world -- -- > CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk > Standard replies will go to the list; address personal replies manually. > For more information, please go to: http://www.not.iac.es/CCD-world/ - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From mckenna at as.arizona.edu Tue Mar 5 12:49:42 2002 From: mckenna at as.arizona.edu (Dan McKenna) Date: Thu Jul 29 11:52:24 2004 Subject: CCD-world: Re: Mylar foil insulated CCD-cryostats? References: Message-ID: <3C851346.92CE2C00@as.arizona.edu> The following was posted to CCD-world: Hi Willie, Yes, I normally would remove the super insulation when working on CCD cameras ( a few years ago) and had similar results. The hold time increased many fold ! In the last two years of my CCD tour of duty we obtained a mass spectrometer that showed why. It seems that once the super insulation was cycled to room air a few times it took weeks to reduce the H20 partial pressure. This would saturate the getter (activated charcoal) and one need to heat the can to make headway. I tried using dry N2 back fills so that the warm can (80C) with dry N2 at atmospheric pressure would "scrub" the water vapor layers faster than in a vacuum. That did speed up the process but not enough to be of practical use. I would gold plate as much as possible for a low emmisivity non oxidizing surface and never use MLI. For big chips most of the heat loss is via front window radiation. Dan Willie Koorts wrote: > "Now don't get me wrong. There is a place when a radiation shield, if you > will, should be used ... if you have the room (and you can clean parts). > A single layer or surface between the LN2 tank and the outside wall of the > dewar will help control radiation losses. BUT ... IF you have highly > polished surfaces on the inside wall of the outer dewar container and the > surface of the LN2 tank, you don't need the shield either! I prove that > every day with our dewars ... all twelve of them [back in 1995]. Again I > must add that a good vacuum is necessary ... as good as you can get." > > I would be very interested to hear further opinions/experiences on > adding/removing radiations shields. > > Regards > Willie > > - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From wpk at saao.ac.za Wed Mar 6 13:43:44 2002 From: wpk at saao.ac.za (Willie Koorts) Date: Thu Jul 29 11:52:24 2004 Subject: CCD-world: Re: Mylar foil insulated CCD-cryostats? In-Reply-To: Message-ID: The following was posted to CCD-world: On Tue, 5 Mar 2002, Anton Norup S?rensen wrote: > I guess something must have gone very wrong in the radiation shield > installation you describe. Either heavy outgassing or conductive > short-cirquiting by the glue or insulation material. The first part of this mail which I never quoted agrees 100% with Dan McKenna's experience and theory - it read as follows: "In my opinion ... and this usually will get me into lots of trouble ... superinsulation is a waste of time for LN2 dewars! You're right, how do you clean the stuff??? Twenty layers of this stuff increase your surface area by a factor of 20 at least. What stick to all surfaces, is hard to pump, and screw up a good AR coating? Answer: WATER!" Bruce, I never managed to read your MATHCAD 6.0 document, even after trying hard. Is it not possible to make this available in a more general format eg PDF or even just some screenshots or scans of the printouts? Regards Willie - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From geary at cfa.harvard.edu Wed Mar 6 08:13:00 2002 From: geary at cfa.harvard.edu (John Geary) Date: Thu Jul 29 11:52:24 2004 Subject: CCD-world: FW: L3vision astronomy chips In-Reply-To: <200203060027.g260R6o17235@ursa.astro.ku.dk> Message-ID: <5.1.0.14.0.20020306070507.021fce20@cfa-pop1.harvard.edu> The following was posted to CCD-world: At 10:22 AM 2/18/2002 +0000, Paul Jorden wrote: >This message is to discuss potential interest in other formats, using the >same L3vision technology: > >A. We could make a 2k*4k thinned chip with the same technology. I would >be interested in comments on the desirability of this. I assume such a >chip would be particularly desirable for high dispersion spectroscopy (ie >lowest noise). ---------------------------------------------- In addition to the large format you mention, many older spectrographs could benefit from a reduced format like 3K X 512. Yield would obviously be better for this reduced format, with hopefully lower prices. You might even fit a couple of these on the chords of wafers being fabbed for the larger devices. --J.Geary - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From atwood at mps.ohio-state.edu Wed Mar 6 09:30:45 2002 From: atwood at mps.ohio-state.edu (Bruce Atwood) Date: Thu Jul 29 11:52:24 2004 Subject: CCD-world: Re: Mylar foil insulated CCD-cryostats? References: <3C851346.92CE2C00@as.arizona.edu> Message-ID: <3C861A05.2A272908@ohstpy.mps.ohio-state.edu> The following was posted to CCD-world: Dan McKenna wrote: > The following was posted to CCD-world: > > Hi Willie, > > Yes, I normally would remove the super insulation when working > on CCD cameras ( a few years ago) and had similar results. > > The hold time increased many fold ! > In the last two years of my CCD tour of duty we obtained a mass > spectrometer that showed why. > > It seems that once the super insulation was cycled to room air a few times it > took weeks to reduce the H20 partial pressure. This would > saturate the getter (activated charcoal) and one need to heat the > can to make headway. > MLI, superinsulation, or aluminized mylar is one of many sources of H2O in vacuum systems. H2O is almost always the hardest component to control especially, as Dan mentions, when it saturates your actvated charcoal or zeolite. That is why I use warm (and easy to change) zeolite to pump water and cold charcoal to pump O2 and N2 (which comes through the ORings). Again, see http://www.astronomy.ohio-state.edu/~isl/PAPERS/Aadsorb.htm > > I tried using dry N2 back fills so that the warm can (80C) > with dry N2 at atmospheric pressure would "scrub" the > water vapor layers faster than in a vacuum. That did speed > up the process but not enough to be of practical use. > > I would gold plate as much as possible for a low emmisivity > non oxidizing surface and never use MLI. For big chips most of > the heat loss is via front window radiation. > > Dan > > Willie Koorts wrote: > > > "Now don't get me wrong. There is a place when a radiation shield, if you > > will, should be used ... if you have the room (and you can clean parts). > > A single layer or surface between the LN2 tank and the outside wall of the > > dewar will help control radiation losses. BUT ... IF you have highly > > polished surfaces on the inside wall of the outer dewar container and the > > surface of the LN2 tank, you don't need the shield either! I prove that > > every day with our dewars ... all twelve of them [back in 1995]. Again I > > must add that a good vacuum is necessary ... as good as you can get." > > > > I would be very interested to hear further opinions/experiences on > > adding/removing radiations shields. > > > > Regards > > Willie > > > > > > - -- CCD-world -- -- > CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk > Standard replies will go to the list; address personal replies manually. > For more information, please go to: http://www.not.iac.es/CCD-world/ - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From dbc at saao.ac.za Wed Mar 6 16:46:41 2002 From: dbc at saao.ac.za (Dave Carter) Date: Thu Jul 29 11:52:24 2004 Subject: CCD-world: CCD temperature stability In-Reply-To: <3C84C38E.43C63AE9@ohstpy.mps.ohio-state.edu> Message-ID: The following was posted to CCD-world: Hi All Has anybody got hard data to define the requirements of detector temperature control? I have checked through the archives and it seems this topic hasn't come up for discussion other than in the context of dark current and temperature-related QE affects which are not significant over small (<1 degree) temperature changes. There was some discussion on output amplifier gain vs temperature, concluding that it was not a significant effect over the temperature range at which we operate the detectors. My questions are: 1. How stable should the temperature be (P-P variation) and what effects do we look for related to short-term temperature variations? (e.g. as may result from high speed image area clocking) 2. How important is it to minimize the temperature profile across a large detector? (In our case 2Kx4K) We are modelling the thermal characteristics of a 2-device mini mosaic, currently predicting a "quiescent state" 0.1 degree max differential across one detector. regards +-----------------------------------------------------+ Dave Carter Electronics Lab, S. A. Astronomical Observatory. e-mail : dbc@saao.ac.za Tel ( Nat. ) : 021-4470025 ( Int. ) : 27-21-4470025 Fax ( Nat. ) : 021-4473639 ( Int. ) : 27-21-4473639 +-----------------------------------------------------+ - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From smt at ing.iac.es Wed Mar 6 16:32:06 2002 From: smt at ing.iac.es (Simon Tulloch) Date: Thu Jul 29 11:52:24 2004 Subject: CCD-world: Pt100 References: <3C851346.92CE2C00@as.arizona.edu> <3C861A05.2A272908@ohstpy.mps.ohio-state.edu> Message-ID: <00d501c1c524$12d184e0$7b1a48a1@ing.iac.es> The following was posted to CCD-world: Hi, I have recently been trying to check the accuracy of our CCD temperature servo hardware/software here at the ING. We use Pt100 sensors in all our CCDs. I have always believed that the temperature coefficient of Pt100 sensors to be 0.38 Ohms per K but recent experiments indicate a higher figure. I calibrated two sensors of differing design by dipping them in melting ice and boiling nitrogen. These indicated a coefficient of 0.41 Ohms per K for both sensors. Would this seem to be a fair calibration or does platinum experience non-linearities at these low temperatures? I would be interested to hear what Tcoeffs are assumed by other observatories using Pt100. Regards Simon Tulloch Isaac Newton Group - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From Tim.Hardy at nrc.ca Wed Mar 6 10:12:28 2002 From: Tim.Hardy at nrc.ca (Hardy, Tim) Date: Thu Jul 29 11:52:25 2004 Subject: CCD-world: Pt100 Message-ID: <0B39C62869FED21181C90004ACE532DD013BBB79@nrcvicex1.hia.nrc.ca> The following was posted to CCD-world: I have a data sheet here for a Pt RTD that includes a temperature vs. resistance table. The coefficient does vary with temperature, from 0.37 ohm/K at +119C to 0.44 ohm/K at -200C. A rough summary of the table (eyeball averaging): Temperatures (C) Resistance (ohms) Coefficient (ohm/K) -200 - -199 18.49 - 18.93 0.44 -198 - -171 19.36 - 30.90 0.43 -170 - -141 31.32 - 43.45 0.42 -140 - -91 43.87 - 63.90 0.41 -90 - -31 64.30 - 87.93 0.40 -30 - +40 88.22 - 115.54 0.39 +41 - +119 115.93 - 145.68 0.38 Tim Hardy Herzberg Institute of Astrophysics National Research Council Canada > -----Original Message----- > From: Simon Tulloch [mailto:smt@ing.iac.es] > Sent: Wednesday, March 06, 2002 7:32 AM > To: CCD-world@astro.ku.dk > Subject: CCD-world: Pt100 > > > The following was posted to CCD-world: > > Hi, > I have recently been trying to check the accuracy of our CCD > temperature > servo hardware/software here at the ING. We use Pt100 sensors > in all our > CCDs. I have always believed that the temperature coefficient of Pt100 > sensors to be 0.38 Ohms per K but recent experiments indicate a higher > figure. I calibrated two sensors of differing design by > dipping them in > melting ice and boiling nitrogen. These indicated a > coefficient of 0.41 Ohms > per K for both sensors. Would this seem to be a fair > calibration or does > platinum experience non-linearities at these low > temperatures? I would be > interested to hear what Tcoeffs are assumed by other > observatories using > Pt100. > Regards > Simon Tulloch > Isaac Newton Group > > - -- CCD-world -- -- > CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk > Standard replies will go to the list; address personal > replies manually. > For more information, please go to: http://www.not.iac.es/CCD-world/ > - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From andy at retrievertech.com Wed Mar 6 11:14:43 2002 From: andy at retrievertech.com (Andy Bartlett) Date: Thu Jul 29 11:52:25 2004 Subject: CCD-world: CCD repeatability Message-ID: <013101c1c53a$ca69f040$0300000a@net> I have a question concerning the repeatability of data from a CCD camera. Assume: A scientific grade cooled CCD detector No temperature variation Imagine that the CCD images a perfectly flat scene. Multiple exposures are taken of the same scene for exactly the same time. The results of these different exposures are compared. I believe that: Any pixel will have a Poisson distribution about a mean, with standard deviation given by the square root of the number of counts The mean value of all the pixels in one exposure will be the same as the mean value of the pixels in the other exposure. OK, that last statement isn't exactly true, which is the crux of my question. No mean value will ever be 'the same,' but how close will they be? I think that the mean values will be distributed over a value much tighter than the shot noise. What kind of distribution will this mean value have? And what effects lead to differences in the mean value? Does variation in CTE significantly change the mean value? Will the amplifier give some scatter? I don't think that linearity is a factor here, since that describes the behavior of any given pixel over a range of exposure times. (And actually what I'm thinking is that non-linearities can be mapped out since the response is repeatable.) Thanks for any ideas on this. Andy ************************************ Andrew H. Bartlett, Ph.D. Retriever Technology 1415 W. Alameda St. Santa Fe, NM 87501 Phone: (505) 986 8196 Fax: (505) 986 9266 email: andy@retrievertech.com ************************************* -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20020306/88210232/attachment.htm From rsmith at astro.caltech.edu Wed Mar 6 11:18:22 2002 From: rsmith at astro.caltech.edu (Roger Smith) Date: Thu Jul 29 11:52:25 2004 Subject: CCD-world: FW: L3vision astronomy chips References: <5.1.0.14.0.20020306070507.021fce20@cfa-pop1.harvard.edu> Message-ID: <3C865D6E.A4CC95D7@astro.caltech.edu> I support John Geary's suggestion that a cheaper intermediate size would be an interesting option. A little bigger than 3Kx512 would be better, especially given the existence of a conventional 2048x512 13.5um CCD from Marconi. Goals: low noise, low dark, negligible spurious charge, and serial register on long dimension. -- Roger John Geary wrote: > The following was posted to CCD-world: > > At 10:22 AM 2/18/2002 +0000, Paul Jorden wrote: > > >This message is to discuss potential interest in other formats, using the > >same L3vision technology: > > > >A. We could make a 2k*4k thinned chip with the same technology. I would > >be interested in comments on the desirability of this. I assume such a > >chip would be particularly desirable for high dispersion spectroscopy (ie > >lowest noise). > ---------------------------------------------- > > In addition to the large format you mention, many older spectrographs could > benefit from a reduced format like 3K X 512. Yield would obviously be > better for this reduced format, with hopefully lower prices. You might > even fit a couple of these on the chords of wafers being fabbed for the > larger devices. > > --J.Geary > > - -- CCD-world -- -- > CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk > Standard replies will go to the list; address personal replies manually. > For more information, please go to: http://www.not.iac.es/CCD-world/ -------------- next part -------------- A non-text attachment was scrubbed... Name: rsmith.vcf Type: text/x-vcard Size: 429 bytes Desc: Card for Roger Smith Url : http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20020306/1efc8a45/rsmith.vcf From rsmith at astro.caltech.edu Wed Mar 6 11:26:47 2002 From: rsmith at astro.caltech.edu (Roger Smith) Date: Thu Jul 29 11:52:25 2004 Subject: CCD-world: CCD temperature stability References: Message-ID: <3C865F67.8D73A67A@astro.caltech.edu> Dave, An additional thermal stability requirement is imposed if you are DC coupling the video, since the ~20V DC level on the video is modulated by the output FET current which is mildly temperature dependent. The specifics depend on the video gain (and thus dwell time), the temperature of the CCD, and so on, but as a rough rule of thumb I found that a 5-10 degree change was the most I as comfortable with before the midpoint of the dual slope integration would start to see significant excursions. In short, the effects that you are concerned about are not a concern in this respect (or any other that I know of). -- Roger Dave Carter wrote: > The following was posted to CCD-world: > > Hi All > > Has anybody got hard data to define the requirements of detector > temperature control? I have checked through the archives and it seems > this topic hasn't come up for discussion other than in the context of dark > current and temperature-related QE affects which are not significant over > small (<1 degree) temperature changes. There was some discussion on > output amplifier gain vs temperature, concluding that it was not a > significant effect over the temperature range at which we operate the > detectors. > > My questions are: > 1. How stable should the temperature be (P-P variation) and what effects > do we look for related to short-term temperature variations? (e.g. > as may result from high speed image area clocking) > 2. How important is it to minimize the temperature profile across a large > detector? (In our case 2Kx4K) > > We are modelling the thermal characteristics of a 2-device mini mosaic, > currently predicting a "quiescent state" 0.1 degree max differential > across one detector. > > regards > > +-----------------------------------------------------+ > Dave Carter > Electronics Lab, S. A. Astronomical Observatory. > e-mail : dbc@saao.ac.za > Tel ( Nat. ) : 021-4470025 ( Int. ) : 27-21-4470025 > Fax ( Nat. ) : 021-4473639 ( Int. ) : 27-21-4473639 > +-----------------------------------------------------+ > > - -- CCD-world -- -- > CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk > Standard replies will go to the list; address personal replies manually. > For more information, please go to: http://www.not.iac.es/CCD-world/ -------------- next part -------------- A non-text attachment was scrubbed... Name: rsmith.vcf Type: text/x-vcard Size: 429 bytes Desc: Card for Roger Smith Url : http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20020306/2270547c/rsmith.vcf From mckenna at as.arizona.edu Wed Mar 6 12:27:08 2002 From: mckenna at as.arizona.edu (Dan McKenna) Date: Thu Jul 29 11:52:25 2004 Subject: CCD-world: Re: Mylar foil insulated CCD-cryostats? References: <3C84C38E.43C63AE9@ohstpy.mps.ohio-state.edu> Message-ID: <3C865F7C.67FBE402@as.arizona.edu> The following was posted to CCD-world: Bruce, Your words some how compel me to stand on on a soap box as in past times, I would rant and rave about the construction and maintenance of CCD dewars. It's like an old war wound and its hard to find a therapist that understands. Bruce Atwood wrote: > The following was posted to CCD-world: > > Just a quick comment on some aspects of dewars. The heat gain in a vacuum dewar > is dominated by radiation at any pressure below 10e-5 Torr. Don't waste your time > on techniques appropriate for very or ultra high vacuum. I would argue that you want to use ultra high vacuum techniques when ever practical. Take a room temp dewar and pump on it for a few hours, shut the valve and watch the pressure rise. It seems that the first step in making a camera would be a dewar that would maintain a vacuum. OK, so when the camera is cold, the getter and cold can should cyro pump the chip environment. The observed pressure rise is do to a mass flux from a leak and or out gassing. A small fraction of gas will stick to the ccd and depending on the type of detector, may produce a change in the Q.E. How important is the long term stability of QE ? A day at the busy observatory will have the crew changing instruments and detectors. How long do we pump the dewar ? How long after the ln2 runs out ( who was going to fill the can ?) can we refill the cold can with out repumping the dewar ? These operational issues are sometimes compromised by unforeseen set up problems and as a result the dewar ends up with a soft vacuum. A well designed and maintained dewar will minimize ccd contamination in a operational system. > monitor the weight of dewars to measure either the LN2 consumption or power input, > a cheap flow meter gives you an instantaneous measurement of consumption or power > input. If you get one calibrated in cubic feet per hour that turns out to be > almost exactly liters of liquid per day and multiplying by two gives power input Yes, flow meters work great and if you log the boil off rate say at 12 bits you can see a small leak long before its reported in reduced hold time. If the telescope operator does a incomplete fill the flow meter can save the night. Dan - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From deg at panisse.lbl.gov Wed Mar 6 12:13:13 2002 From: deg at panisse.lbl.gov (Don Groom) Date: Thu Jul 29 11:52:25 2004 Subject: CCD-world: CCD repeatability In-Reply-To: <013101c1c53a$ca69f040$0300000a@net> Message-ID: The following was posted to CCD-world: As far as I know, the uncertainty in the mean value of N numbers, each chosen from a Gaussian distribution with width sigma, is sigma/sqrt(N). And then there's lamp stability... Don |-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+| Don Groom (Particle Data Group, Supernova Cosmology Project) DEGroom@lbl.gov www-ccd.lbl.gov Voice: 510/486-6788 FAX: 510/486-4799 Analog: 50-308//Berkeley Lab//Berkeley, CA 94720 - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From rsmith at astro.caltech.edu Wed Mar 6 12:19:34 2002 From: rsmith at astro.caltech.edu (Roger Smith) Date: Thu Jul 29 11:52:25 2004 Subject: CCD-world: Pt100 References: <3C851346.92CE2C00@as.arizona.edu> <3C861A05.2A272908@ohstpy.mps.ohio-state.edu> <00d501c1c524$12d184e0$7b1a48a1@ing.iac.es> Message-ID: <3C866BC6.6AF59D2D@astro.caltech.edu> Simon, I have used simple 1N914 diodes as temperature sensors and went through a similar procedure to check their calibration. I found that it was necessary to keep the diode from contacting the water directly since the leakage current through the water would skew the results. I tried distilled water without success perhaps because of surface contamination issues. A plastic bag around the device under test proved to be the simplest solution. -- Roger -------------- next part -------------- A non-text attachment was scrubbed... Name: rsmith.vcf Type: text/x-vcard Size: 429 bytes Desc: Card for Roger Smith Url : http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20020306/f219924c/rsmith.vcf From Farrokh.Vakili at unice.fr Wed Mar 6 21:30:33 2002 From: Farrokh.Vakili at unice.fr (Farrokh VAKILI) Date: Thu Jul 29 11:52:25 2004 Subject: CCD-world: FW: L3vision astronomy chips References: <200203060027.g260R6o17235@ursa.astro.ku.dk> Message-ID: <3C866E59.34F2ABD8@unice.fr> The following was posted to CCD-world: Hi, our applications are A.O. high dynamic imaging using coronagraphic optics for direct EXPN detection. We are extremely interested in a 512x512 version of the ccd60 but donnot possess the infrastructure and manpower for building ourselves the controller. Therefore a simple drive with full-frame at maximum rate is our favorite choice. If the first alternative is prefered by the majority of you and Marconi we would join other partners probably in terms of financial support. friendly Farrokh -- Farrokh VAKILI mailto:Farrokh.Vakili@unice.fr Tel: (33)492076320 Secretariat:(33)492076322 Fax:(33)492076321 Directeur UMR 6525 Astrophysique CNRS Universite de Nice Sophia-Antipolis UFR Faculte des Sciences Parc Valrose 06108 Nice Cedex 02, FRANCE - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From pjm at wairau.as.utexas.edu Wed Mar 6 16:07:54 2002 From: pjm at wairau.as.utexas.edu (Phillip MacQueen) Date: Thu Jul 29 11:52:25 2004 Subject: CCD-world: Pt100 Message-ID: <200203062107.PAA09642@wairau.as.utexas.edu> The following was posted to CCD-world: Hello Simon, To follow up a little more on your RTD question, Omega Engineering (from whom I buy RTDs) give a table of resistance versus temperature for RTDs over the range of -200 degrees Celsius to 850 degrees Celsius. It's for their standard parts which use the European curve with an alpha of 0.00385, and which are exactly 100 ohms at 0 degrees Celsius. The URL is: http://www.omega.com/temperature/Z/pdf/z252-254.pdf (Omega also give limited data for devices with the American curve, which have an alpha of 0.00395). These tables are all very well, but when you make a thermometer with an RTD, generally the RTD is excited with a constant current source (via two wires of a 4-wire measurement), and the voltage across the RTD is measured via the other two wires. The known current and measured voltage allow the resistance of the RTD to be calculated. To find the temperature to which that resistance corresponds, it's best to have a function T=fn(R) rather than a table. I have a (good) fit to the data in the above table over the range of -200 to +100 degrees Celsius. It's what my CCD controller uses in its thermometry. The function is: T = -241.92 + 2.2109*R + 3.0362E-3 * R**2 - 1.2237E-5 * R**3 + 2.7021E-8 * R**4 I have the table as a plain text document and will e-mail it to anyone who would find it useful. It's in the following format: -200 18.52 -199 18.96 0.44 -198 19.39 0.43 -197 19.82 0.43 ...deleted... +98 137.75 0.38 +99 138.13 0.38 +100 138.51 0.38 As some further background, I generally use four 100 ohm RTDs in series as the sensor for my temperature controller servo loops. Using four (versus one) halves the sensor noise and doubles the precision, but it also allows the 4 RTDs to be distributed over the cold block to give an averaged temperature. Generally the precision I see is about 30 (or so) microkelvin, so the temperature of the thermometer (which after all is what is controlled, rather than the CCD temperature) stays within about a 200 microkelvin band. Regards, Phillip CCD group McDonald Observatory > From owner-CCD-world@astro.ku.dk Wed Mar 6 09:55 CST 2002 > From: "Simon Tulloch" > Subject: CCD-world: Pt100 > Hi, > I have recently been trying to check the accuracy of our CCD temperature > servo hardware/software here at the ING. We use Pt100 sensors in all our > CCDs. I have always believed that the temperature coefficient of Pt100 > sensors to be 0.38 Ohms per K but recent experiments indicate a higher > figure. I calibrated two sensors of differing design by dipping them in > melting ice and boiling nitrogen. These indicated a coefficient of 0.41 Ohms > per K for both sensors. Would this seem to be a fair calibration or does > platinum experience non-linearities at these low temperatures? I would be > interested to hear what Tcoeffs are assumed by other observatories using > Pt100. > Regards > Simon Tulloch > Isaac Newton Group - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From atwood at mps.ohio-state.edu Wed Mar 6 18:29:25 2002 From: atwood at mps.ohio-state.edu (Bruce Atwood) Date: Thu Jul 29 11:52:25 2004 Subject: CCD-world: Pt100 References: <3C851346.92CE2C00@as.arizona.edu> <3C861A05.2A272908@ohstpy.mps.ohio-state.edu> <00d501c1c524$12d184e0$7b1a48a1@ing.iac.es> Message-ID: <3C869845.C6DEAC63@ohstpy.mps.ohio-state.edu> The following was posted to CCD-world: There are two main standards, European and American (no this is not another inch/cm joke). They are quite close but you must know what kind of RTD you have. The whole issue is well discussed in the Omega website with a table for R vs T in : http://www.omega.com/temperature/Z/pdf/z252-254.pdf Simon Tulloch wrote: > The following was posted to CCD-world: > > Hi, > I have recently been trying to check the accuracy of our CCD temperature > servo hardware/software here at the ING. We use Pt100 sensors in all our > CCDs. I have always believed that the temperature coefficient of Pt100 > sensors to be 0.38 Ohms per K but recent experiments indicate a higher > figure. I calibrated two sensors of differing design by dipping them in > melting ice and boiling nitrogen. These indicated a coefficient of 0.41 Ohms > per K for both sensors. Would this seem to be a fair calibration or does > platinum experience non-linearities at these low temperatures? I would be > interested to hear what Tcoeffs are assumed by other observatories using > Pt100. > Regards > Simon Tulloch > Isaac Newton Group > > - -- CCD-world -- -- > CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk > Standard replies will go to the list; address personal replies manually. > For more information, please go to: http://www.not.iac.es/CCD-world/ -- Bruce Atwood Research Scientist Imaging Sciences Laboratory Astronomy Department The Ohio State University 140 W. 18th Ave. Columbus, Ohio 43210-1173 (614) 292 6279 (V) (614) 292 2928 (F) - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From r.bredthauer at sta-inc.net Wed Mar 6 16:41:33 2002 From: r.bredthauer at sta-inc.net (Richard) Date: Thu Jul 29 11:52:25 2004 Subject: CCD-world: Astronomer requirements Message-ID: <003001c1c568$733665a0$0f00a8c0@Richard1> I have received requests for availability of the 2k x 2k 15 micron CCDs such as the old Geary 3-side abutable device (aka Edgar Smith CCD). I am considering putting together a mask set of 2kx2k devices and making a run on 6" inch wafers (lower noise, higher charge capacity, better cosmetics). In order to do so I would like to know which astronomers might be interested in acquiring such devices, both front or backside illuminated. If so please email CCD-world or myself with your requirements. We will also be describing a new 4k at the CCD conference in Hawaii. I am looking forward to seeing everyone there. Sincerely Dr. Richard Bredthauer Semiconductor Technology Associates, Inc 27122 Paseo Espada, Suite 1004 San Juan Capistrano, CA 92675 Tel: 949-4811595 Fax: 949-4811597 e-mail: r.bredthauer@sta-inc.net www.sta-inc.net -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20020306/c5db826b/attachment.htm From wpk at saao.ac.za Thu Mar 7 10:39:45 2002 From: wpk at saao.ac.za (Willie Koorts) Date: Thu Jul 29 11:52:26 2004 Subject: CCD-world: Pt100 In-Reply-To: <0B39C62869FED21181C90004ACE532DD013BBB79@nrcvicex1.hia.nrc.ca> Message-ID: Hi Attached is a scan (18 KB) of part of a Foxboro data sheet showing a table of PT100 resistance covering -220C to +220C in 5 degree steps which was what I always used to calibrate industrial systems in a former life. Regards Willie -------------- next part -------------- A non-text attachment was scrubbed... Name: pt100.gif Type: image/gif Size: 18530 bytes Desc: Url : http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20020307/e0322f23/pt100.gif From Paul.Jorden at marconi.com Thu Mar 7 10:16:19 2002 From: Paul.Jorden at marconi.com (Jorden, Paul) Date: Thu Jul 29 11:52:26 2004 Subject: CCD-world: Pt100 Message-ID: <200203071341.g27Dfbh26727@ursa.astro.ku.dk> The following was posted to CCD-world: Tim- for ccd-world please- Simon, et al, the lakeshore web has a full table of values at- http://www.lakeshore.com/temperature/pt_100_curve.html platinum is used for its stability primarily. Tim (Hardy) is right to point out that the coefficient changes, so use the table over a wide range. I used to use a table to select a reference resistor value which defined the temperature set point. [eg 56 ohm = -110C]. then if you want to calculate variations about this point you should strictly use the coefficient of ~ 0.41 ohm/degree (not the room temp value of 0.385 ohm/degree) Cheers, Paul _________________________________________________________ Dr Paul Jorden, CCD Sensors, Marconi Applied Technologies Waterhouse Lane, Chelmsford, Essex, CM1 2QU, UK Tel: +44 (0)1245 -453458 (direct), -493493 (switchboard) Fax: 44 (0) 1245 453224 http://www.marconitech.com/ccds/ -----Original Message----- From: Simon Tulloch [mailto:smt@ing.iac.es] Sent: 06 March 2002 15:32 To: CCD-world@astro.ku.dk Subject: CCD-world: Pt100 The following was posted to CCD-world: Hi, I have recently been trying to check the accuracy of our CCD temperature servo hardware/software here at the ING. We use Pt100 sensors in all our CCDs. I have always believed that the temperature coefficient of Pt100 sensors to be 0.38 Ohms per K but recent experiments indicate a higher figure. I calibrated two sensors of differing design by dipping them in melting ice and boiling nitrogen. These indicated a coefficient of 0.41 Ohms per K for both sensors. Would this seem to be a fair calibration or does platinum experience non-linearities at these low temperatures? I would be interested to hear what Tcoeffs are assumed by other observatories using Pt100. Regards Simon Tulloch Isaac Newton Group - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From Paul.Jorden at marconi.com Thu Mar 7 11:07:09 2002 From: Paul.Jorden at marconi.com (Jorden, Paul) Date: Thu Jul 29 11:52:26 2004 Subject: CCD-world: CCD repeatability Message-ID: <200203071343.g27DhUW26909@ursa.astro.ku.dk> The following was posted to CCD-world: Andy, et al, a few comments- Firstly don't forget that Poisson statistics apply to electrons (or detected particles) not to arbitrary electronic units like ADC counts. Also, it is worth separating discussion of the CCD chip from that of the camera. How stable are your external electronics (gain & offset stability...)? you don't give any figures, but if your mean value differs much I would suspect the following- scene illumination, and camera electronic gain stability in that order. the ccd chip should be more stable. Of course, (Poisson) statistics will allow you to calculate the best that you can achieve, in an ideal world. Regards, Paul J -----Original Message----- From: Andy Bartlett [mailto:andy@retrievertech.com] Sent: 06 March 2002 18:15 To: CCD-world@astro.ku.dk Subject: CCD-world: CCD repeatability I have a question concerning the repeatability of data from a CCD camera. Assume: A scientific grade cooled CCD detector No temperature variation Imagine that the CCD images a perfectly flat scene. Multiple exposures are taken of the same scene for exactly the same time. The results of these different exposures are compared. I believe that: Any pixel will have a Poisson distribution about a mean, with standard deviation given by the square root of the number of counts The mean value of all the pixels in one exposure will be the same as the mean value of the pixels in the other exposure. OK, that last statement isn't exactly true, which is the crux of my question. No mean value will ever be 'the same,' but how close will they be? I think that the mean values will be distributed over a value much tighter than the shot noise. What kind of distribution will this mean value have? And what effects lead to differences in the mean value? Does variation in CTE significantly change the mean value? Will the amplifier give some scatter? I don't think that linearity is a factor here, since that describes the behavior of any given pixel over a range of exposure times. (And actually what I'm thinking is that non-linearities can be mapped out since the response is repeatable.) Thanks for any ideas on this. Andy ************************************ Andrew H. Bartlett, Ph.D. Retriever Technology 1415 W. Alameda St. Santa Fe, NM 87501 Phone: (505) 986 8196 Fax: (505) 986 9266 email: andy@retrievertech.com ************************************* _________________________________________________________ Dr Paul Jorden, CCD Sensors, Marconi Applied Technologies Waterhouse Lane, Chelmsford, Essex, CM1 2QU, UK Tel: +44 (0)1245 -453458 (direct), -493493 (switchboard) Fax: 44 (0) 1245 453224 http://www.marconitech.com/ccds/ - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From paul.clark at durham.ac.uk Thu Mar 7 12:04:03 2002 From: paul.clark at durham.ac.uk (Paul Clark) Date: Thu Jul 29 11:52:26 2004 Subject: CCD-world: FW: L3vision astronomy chips References: <200203060027.g260R6o17235@ursa.astro.ku.dk> Message-ID: <3C874923.6060700@durham.ac.uk> The following was posted to CCD-world: Hi Paul (& Fellow CCDers), Jorden, Paul wrote: > A. We could make a 2k*4k thinned chip with the same technology. I would > be interested in comments on the desirability of this. I assume such a > chip would be particularly desirable for high dispersion spectroscopy (ie > lowest noise). After a straw poll here at Durham, we would like to express our interest in the format A device: to be used in IFU spectroscopy with AO where the spectral dispersion is not huge, but the spatial sampling is fine and so the photon rate is again tiny. Regards, Paul Clark -- ------------------------------------------------------- EurIng Paul Clark |Email: paul.clark@durham.ac.uk AIG Head of Engineering |WWW: http://aig-www.dur.ac.uk University of Durham | Department of Physics | Rochester Building |Office: +44 (0)191 374 2762 South Road |Lab: +44 (0)191 374 2763 Durham |Secretary: +44 (0)191 374 2678 DH1 3LE |Mobile: +44 (0)777 372 2949 UK |Fax: +44 (0)191 374 3709 ------------------------------------------------------- - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From atwood at mps.ohio-state.edu Thu Mar 7 10:45:58 2002 From: atwood at mps.ohio-state.edu (Bruce Atwood) Date: Thu Jul 29 11:52:26 2004 Subject: CCD-world: Pt100 References: <3C851346.92CE2C00@as.arizona.edu> <3C861A05.2A272908@ohstpy.mps.ohio-state.edu> <00d501c1c524$12d184e0$7b1a48a1@ing.iac.es> <3C866BC6.6AF59D2D@astro.caltech.edu> Message-ID: <3C877D26.80B16B6B@ohstpy.mps.ohio-state.edu> The following was posted to CCD-world: Silicon diodes do make good temperature sensors, they are cheap, stable and have a reasonable signal level. They do, however, require individual calibration and, because of their non-linear characteristic, are great detectors. We gave up on them when we saw that noise from detector clocks would affect their reading. I'm sure we could have engineered out the problem but life is to short to be solving that kind of problem instead of buying RTD at U$15 a pop. Roger Smith wrote: > Simon, > > I have used simple 1N914 diodes as temperature sensors and went through > a similar procedure to check their calibration. I found that it was > necessary to keep the diode from contacting the water directly since the > leakage current through the water would skew the results. I tried > distilled water without success perhaps because of surface contamination > issues. A plastic bag around the device under test proved to be the > simplest solution. > > -- Roger - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From gleeson at gv.net Thu Mar 7 09:35:35 2002 From: gleeson at gv.net (Greg Leeson) Date: Thu Jul 29 11:52:26 2004 Subject: CCD-world: CCD repeatability References: <013101c1c53a$ca69f040$0300000a@net> Message-ID: <200203071704.g27H42i14206@ursa.astro.ku.dk> If I understand your question I think the answer is fairly simple. Rather than think about the "mean value of all the pixels in one exposure", think about the total number of counts in each exposure. Clearly, over many exposures these will be Poisson distributed. The mean value of all the pixels in one exposure is simply the total number of counts divided by the number of pixels. Regards, Greg Leeson Andy Bartlett wrote: > I have a question concerning the repeatability of data from a CCD > camera. Assume: A scientific grade cooled CCD detectorNo temperature > variation Imagine that the CCD images a perfectly flat scene. > Multiple exposures are taken of the same scene for exactly the same > time. The results of these different exposures are compared. I > believe that:Any pixel will have a Poisson distribution about a mean, > with standard deviation given by the square root of the number of > countsThe mean value of all the pixels in one exposure will be the > same as the mean value of the pixels in the other exposure. OK, that > last statement isn't exactly true, which is the crux of my > question. No mean value will ever be 'the same,' but how close will > they be? I think that the mean values will be distributed over a > value much tighter than the shot noise. What kind of distribution > will this mean value have? And what effects lead to differences in > the mean value? Does variation in CTE significantly change the mean > value? Will the amplifier give some scatter? I don't think that > linearity is a factor here, since that describes the behavior of any > given pixel over a range of exposure times. (And actually what I'm > thinking is that non-linearities can be mapped out since the response > is repeatable.) Thanks for any ideas on > this. Andy ************************************ > Andrew H. Bartlett, Ph.D. > Retriever Technology > 1415 W. Alameda St. > Santa Fe, NM 87501 > Phone: (505) 986 8196 > Fax: (505) 986 9266 > email: andy@retrievertech.com > ************************************* -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20020307/3c41e300/attachment.htm From rsmith at astro.caltech.edu Thu Mar 7 09:38:59 2002 From: rsmith at astro.caltech.edu (Roger Smith) Date: Thu Jul 29 11:52:26 2004 Subject: CCD-world: More Geary (3 side buttable) CCDs References: <003001c1c568$733665a0$0f00a8c0@Richard1> Message-ID: <200203071705.g27H59714359@ursa.astro.ku.dk> Richard, After 19 years at CTIO, I've moved to a small research university in Southern California. Among many other things I'm looking around for CCDs of about the size you propose for a simultaneous multiband imager (bands defined by dichroic mirrors). So yes I have an application. The number of we require is most likely 3 (G and R bands, plus guider), with the other 2 science devices being deep depletion for the I and Z bands. Though it could be more if the deep depletion devices don't come through or if we decide invest in more pixels for our fixed guider. We will want the high midband QE. What are you going to do for thinning and backside treatment? UV flooding is not an option in this setup since we have fixed filters and this is to be a low maintenance instrument. I'd like to hear an approximate price so we can decide how to trade number pixels in the guider against opto-mechanical complexity. I hope to see you again at the Scientific Detector Workshop, http://www2.keck.hawaii.edu:3636/realpublic/sdw2002/ , or if you are in Pasadena, give me a call. (contact info attached). -- Roger -------------- next part -------------- A non-text attachment was scrubbed... Name: rsmith.vcf Type: text/x-vcard Size: 429 bytes Desc: Card for Roger Smith Url : http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20020307/81de9ab2/rsmith.vcf From rsmith at astro.caltech.edu Thu Mar 7 10:25:28 2002 From: rsmith at astro.caltech.edu (Roger Smith) Date: Thu Jul 29 11:52:26 2004 Subject: CCD-world: temperature stability & accuracy requirments ? Message-ID: <3C87A288.541D56A6@astro.caltech.edu> Hey Bruce, I've never had a problem with the diodes-as-temperature-sensors rectifying crosstalk, except the one time that my heater circuit oscillated at 300 MHz (:-). That's a another story. Neither do I worry about millikelvin temperature stability. Seems to me from this discussion that the advantages of RTD's are not so clear as you state, when considering the 4 wire measurement requirement and non-linearity discussed at length here. All the 1N914's I have tested have deliver 1.5K peak error at 77K and 4K peak error at room temp. Typically they are much better than this. With 10 uA drive current, series resistance has negligible effect and twisting the wires seems to keep the pickup at bay. Diodes do go non-linear below about 45K. So what do we consider the absolute accuracy and stability requirements to be? I believe that the answer lies in sensitivity of dark current and QE to temperature. Dark current variation is well understood but one's requirements vary greatly with application and operating temperature (the less you have, the less you care). QE variation versus temperature is dependent on the specific device or manufacturer and is supposed to be low. Of course some non-flat CCDs change shape with temperature but again this is a slow effect. Why all the fuss? What am I missing? -- Roger Bruce Atwood wrote: > The following was posted to CCD-world: > > Silicon diodes do make good temperature sensors, they are cheap, stable and > have a reasonable signal level. They do, however, require individual > calibration and, because of their non-linear characteristic, are great > detectors. We gave up on them when we saw that noise from detector clocks > would affect their reading. I'm sure we could have engineered out the > problem but life is to short to be solving that kind of problem instead of > buying RTD at U$15 a pop. > > Roger Smith wrote: > > > Simon, > > > > I have used simple 1N914 diodes as temperature sensors and went through > > a similar procedure to check their calibration. I found that it was > > necessary to keep the diode from contacting the water directly since the > > leakage current through the water would skew the results. I tried > > distilled water without success perhaps because of surface contamination > > issues. A plastic bag around the device under test proved to be the > > simplest solution. > > > > -- Roger > > - -- CCD-world -- -- > CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk > Standard replies will go to the list; address personal replies manually. > For more information, please go to: http://www.not.iac.es/CCD-world/ -------------- next part -------------- A non-text attachment was scrubbed... Name: rsmith.vcf Type: text/x-vcard Size: 429 bytes Desc: Card for Roger Smith Url : http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20020307/1b63a6ec/rsmith.vcf From ja at ursa.astro.ku.dk Thu Mar 7 19:34:50 2002 From: ja at ursa.astro.ku.dk (Johannes Andersen) Date: Thu Jul 29 11:52:26 2004 Subject: CCD-world: Astronomer requirements In-Reply-To: <003001c1c568$733665a0$0f00a8c0@Richard1> from "Richard" at Mar 06, 2002 03:41:33 PM Message-ID: <200203071734.g27HYoE16233@ursa.astro.ku.dk> The following was posted to CCD-world: Hi Richard, We'd certainly also be interested in the kind of chip you describe, i.e. the good old Lorals, but with lower noise, no charge diffusion PLEASE (i.e. perfect MTF), QE up to Lesser standards, and preferably a thick version also for use in the red. All at affordable prices and predictable delivery times. If I think of anything else I'll let you know! I'll miss all of you guys in Hawaii, but am taking up a new job at the Nordic Optical Telescope, so I'll have to miss this one, but the rest of the gang from here will keep you company. Best regards, Johannes Andersen ============================================================= Niels Bohr Institute for Astronomy, Physics and Geophysics Astronomical Observatory Tel: +45 353 25934 Juliane Maries Vej 30 Fax: +45 353 25989 DK - 2100 Copenhagen E-mail: ja@astro.ku.dk Denmark WWW: http://www.astro.ku.dk/~ja ============================================================= - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From tylinski at pcez.com Thu Mar 7 10:42:06 2002 From: tylinski at pcez.com (George Tylinski) Date: Thu Jul 29 11:52:26 2004 Subject: CCD-world: Pt100 In-Reply-To: Message-ID: <000101c1c5ff$7b5d9ef0$85cfd2d1@MPRO> The following was posted to CCD-world: Using either Pt or Si diode, it is imperative that the sensing element is structurally isolated. Strains due to differential expansion will throw the calibration curves out the window. The trick is achieving structural isolation AND thermal coupling - not a trivial task. For this reason, prepackaged (structurally isolated) sensors are worth the extra cost. Also, it's important to locate them where they are not exposed to direct thermal radiation from the window, which typically has a high emissivity (antireflection) coating. Best Regards, George Tylinski George Tylinski Mechanical Design & Analysis 503-515-3338 voice - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From Rick.Cross at hs.utc.com Thu Mar 7 11:31:45 2002 From: Rick.Cross at hs.utc.com (Rick.Cross@hs.utc.com) Date: Thu Jul 29 11:52:26 2004 Subject: CCD-world: CCD repeatability Message-ID: The following was posted to CCD-world: > I think that the mean values will be distributed over a value much > tighter than the shot noise. What kind of distribution will this mean > value have? And what effects lead to differences in the mean value? Well, this is an exercise in Poisson statistics. The std. deviation of the mean you calculate will be approximately the root-sum-square of all of the individual pixels' absolute sigmas (i.e., absolute uncertainties, or rms noise) divided by the rss of the individual pixels' *normalized* sigmas (i.e., fractional uncertainties), meaning that the overall distribution will be broader than that of a typical pixel. (Unless, of course, the NEE of your system is < 1!) Now I used the word "approximately" because I left out a step. Once you start averaging pixels across the array, then the statistics of the result will be affected by fixed pattern noise, either from the scene or inherent in the array response. The degree it impacts the result depends on the quality of your array and the flatness of your illumination, and since it is correlated uncertainty, Poisson statistics no longer help you quantify the uncertainty of your result. Fixed pattern noise will serve to further broaden the distribution of means (i.e., more uncertainty). If you need a quantitative uncertainty, then before you analyze your frames you must correct them for fixed pattern noise. This will further spread the uncertainty in your mean by (1/root N+1), N being the number of frames you sample to find the fixed pattern noise, and 1 for correcting the fixed pattern in a newly sampled frame. Janesick gives an excellent description of fixed pattern correction in Scientific Charge-Coupled Devices, SPIE Press 2001. > Does variation in CTE significantly change the mean value? Intuitively: On a flat exposure, CTI would have little effect on the mean, since eventually, you still count almost every electron on the array. However, I would expect to see a slight increase in the sigma of the mean value... > Will the amplifier give some scatter? I don't think that linearity > is a factor here, since that describes the behavior of any given pixel > over a range of exposure times. (And actually what I'm thinking is > that non-linearities can be mapped out since the response is > repeatable.) The amplifiers add to the noise in each pixel, but if you're working in a well-illuminated condition, the photon noise will dominate. Similarly, the differential non-linearity of the amplifier response is typically negligible except at the extreme ends of the response, and in a flat field all the pixel values will fall on the same small area of the linearity curve, so if you're using halfway decent equipment, you shouldn't see any noticeable contributions from nonlinearity. Regards, Rick -- Richard Cross, Sr. Systems Engineer Rick.Cross@hs.utc.com Hamilton Sundstrand Sensor Systems Division (formerly Orbital Sciences SSD) PO Box 2801 Pomona, CA 91769 909-593-3581 x4003 - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From CMOSCCD at aol.com Thu Mar 7 17:19:52 2002 From: CMOSCCD at aol.com (CMOSCCD@aol.com) Date: Thu Jul 29 11:52:26 2004 Subject: CCD-world: CCD repeatability Message-ID: <200203072147.g27LlbI28703@ursa.astro.ku.dk> The following was posted to CCD-world: Andy, Let's say you had a CCD with infinite pixels with an average signal of m and standard deviation of s. Then you start taking sub frames of n pixels with means of m1, m2, m3. . . mn What is standard deviation of the means? The answer is s/(n)^1/2. Lets say the array was finite in size (N pixels). The standard deviation here is . . . s x (N-n)/n(N-1))^1/2 which reduces to the above equation when N>> n. Dark current, pixel nonuniformity, spurious charge, read noise would not change the equations above (all would add in quadrature to give s). CTE would influence. . . because s would vary across the CCD. Does this help ? Are you actually making measurements like this ? Jim *******************************jj In a message dated 3/6/02 11:53:03 AM Pacific Standard Time, andy@retrievertech.com writes: OK, that last statement isn't exactly true, which is the crux of my question. No mean value will ever be 'the same,' but how close will they be? I think that the mean values will be distributed over a value much tighter than the shot noise. What kind of distribution will this mean value have? And what effects lead to differences in the mean value? Does variation in CTE significantly change the mean value? Will the amplifier give some scatter? I don't think that linearity is a factor here, since that describes the behavior of any given pixel over a range of exposure times. (And actually what I'm thinking is that non-linearities can be mapped out since the response is repeatable.) Thanks for any ideas on this. Andy ************************************ Andrew H. Bartlett, Ph.D. Retriever Technology 1415 W. Alameda St. Santa Fe, NM 87501 Phone: (505) 986 8196 Fax: (505) 986 9266 email: andy@retrievertech.com ************************************* >> - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From manderse at sun3.oulu.fi Fri Mar 8 10:44:02 2002 From: manderse at sun3.oulu.fi (Michael Andersen) Date: Thu Jul 29 11:52:27 2004 Subject: CCD-world: temperature stability & accuracy requirments ? In-Reply-To: <3C87A288.541D56A6@astro.caltech.edu> Message-ID: The following was posted to CCD-world: Hi Roger, Bruce Many of the stability of accuracy requirements for a scientific CCD were addressed in: Buffington, Hudson and Booth, 1990: PASP, , Vol 102, p.688. Surely, the requirements are much depending on the application. For high precision spectroscopic work (radial velocities) you would like to reach the impressive level of temperature control quoted by Phillip MacQueen, rather than the behaviour shown in Fig. 7 of Buffington et al. Cheers, Michael On Thu, 7 Mar 2002, Roger Smith wrote: > Hey Bruce, > > I've never had a problem with the diodes-as-temperature-sensors rectifying > crosstalk, except the one time that my heater circuit oscillated at 300 MHz > (:-). That's a another story. > > Neither do I worry about millikelvin temperature stability. Seems to me from > this discussion that the advantages of RTD's are not so clear as you state, > when considering the 4 wire measurement requirement and non-linearity discussed > at length here. All the 1N914's I have tested have deliver 1.5K peak error > at 77K and 4K peak error at room temp. Typically they are much better than > this. With 10 uA drive current, series resistance has negligible effect and > twisting the wires seems to keep the pickup at bay. > > Diodes do go non-linear below about 45K. > > So what do we consider the absolute accuracy and stability requirements to > be? I believe that the answer lies in sensitivity of dark current and QE to > temperature. Dark current variation is well understood but one's requirements > vary greatly with application and operating temperature (the less you have, the > less you care). QE variation versus temperature is dependent on the specific > device or manufacturer and is supposed to be low. Of course some non-flat > CCDs change shape with temperature but again this is a slow effect. > > Why all the fuss? What am I missing? > > -- Roger > > > > Bruce Atwood wrote: > > > The following was posted to CCD-world: > > > > Silicon diodes do make good temperature sensors, they are cheap, stable and > > have a reasonable signal level. They do, however, require individual > > calibration and, because of their non-linear characteristic, are great > > detectors. We gave up on them when we saw that noise from detector clocks > > would affect their reading. I'm sure we could have engineered out the > > problem but life is to short to be solving that kind of problem instead of > > buying RTD at U$15 a pop. > > > > Roger Smith wrote: > > > > > Simon, > > > > > > I have used simple 1N914 diodes as temperature sensors and went through > > > a similar procedure to check their calibration. I found that it was > > > necessary to keep the diode from contacting the water directly since the > > > leakage current through the water would skew the results. I tried > > > distilled water without success perhaps because of surface contamination > > > issues. A plastic bag around the device under test proved to be the > > > simplest solution. > > > > > > -- Roger > > > > - -- CCD-world -- -- > > CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk > > Standard replies will go to the list; address personal replies manually. > > For more information, please go to: http://www.not.iac.es/CCD-world/ > -------------------------------------------------------------------------------- Michael I. Andersen Division of Astronomy, Room T? 320 P.O. BOX 3000 FIN-90014 UNIVERSITY Of OULU, Finland Office phone : +358 8 553 19 37 Fax : +358 8 553 19 34 Mobile : +358 50 34 15 463 -------------------------------------------------------------------------------- - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From cdm at ast.cam.ac.uk Fri Mar 8 16:00:05 2002 From: cdm at ast.cam.ac.uk (Craig D Mackay) Date: Thu Jul 29 11:52:27 2004 Subject: CCD-world: FW: L3vision astronomy chips References: <200203060027.g260R6o17235@ursa.astro.ku.dk> Message-ID: <3C88D1F5.6CD05CAC@ast.cam.ac.uk> The following was posted to CCD-world: Dear Paul I was most interested to see you discussing possible new directions for these LLLCCD technology. As you know we have been enthusiastic users of the CCD 65 and have produced a couple of papers on our results. The most recent paper can be found on: In it we show that it is possible to take diffraction limited images using a ground based telescope without any adaptive optics hardware and achieve surprisingly faint limiting magnitudes. I think it is important to identify that there are two very separating applications for this technology. In the first the emphasis is on high-speed operation and where frame transfer CCD format essential. In astronomical terms this means imaging fast enough so that atmospheric blur is not a problem. In practice this means achieving frame rates in excess of 100 frames per second, and preferably somewhat higher. For applications that are principally adaptive optics types then the size of the CCD is much less important. However there are many applications which are outside astronomy and where high-speed imaging is desirable. There is a lot of interest in neuronal imaging and also in three-dimensional (confocal) fluorescent microscopy where an image as small as 512 by 512 will be much less attractive than one of 1024 by 1024. The device with 1024 by 1024 pixels and 16 outputs running at the same sort of rate that the CCD 60 achieves of 18 MHz would give a frame rate of about 275 frames per second. This would be more than adequate for astronomical imaging as well as for these other applications. I do believe that it would be a mistake to put the development effort into the smaller formats unless there was a very clear indication that this would be attractive for other reasons. The second, and very different application, is where the CCD is still to be used in the way that CCDs are used at present. This is where the shutter is used to give a long exposure and the application of LLLCCD technology is in order to achieve the lowest possible read-out noise. It is very important to appreciate that LLLCCD devices need to be operated in a photon counting mode if they are not to have the effective quantum efficiency reduced by a factor of 2 because of the statistics of the amplification process. In many cases in astronomical spectroscopy this would be an unacceptable feature. To operate the CCD in photon counting mode with an external shutter would be really hard and therefore I think it is extremely important to think quite carefully what is likely to be the mode of operation of a large device and whether it is realistic to think of working with such a device that is not a frame transfer devices and which can be operated at a relatively high frame rate in order to give an unacceptable dynamic range. Although spectroscopy is an extremely low light level application it also has really quite a high dynamic range, contributed at least in part by night sky emission lines even assuming that the object itself is extremely faint. Only in the highest dispersion work is the sky dark enough to make photon counting possible. We have done some simulations here in Cambridge (with Alistair Basden) that suggests one can recover the quantum efficiency that would otherwise be lost by using these devices in the analog mode even at photon levels of a few photons per pixel per frame. Nevertheless I do have some difficulty in understanding exactly how you would actually operate a large area LLLCCD device unless it is a frame transfer device. There have also been comments on CCD world that imply that building controllers for such devices is extremely difficult. Many astronomers and groups have already addressed the business of building controllers that have multiple output channels as well as being able to operate at high pixel rates, and these should be directly usable with a multi output channel LLLCCD. There is a great deal of technology available now associated with driving CCD chips at high speed because that is an essential ability even for still digital cameras. The more interesting challenge is the operation of the high-voltage clock. Marconi have provided quite a lot of information about how to do this and although it is definitely nontrivial, because of the essentially zero noise there is little to the achieved by operating the controller and is more than one pixel rate and therefore the whole business of providing this clocking waveform is much less of a challenge than it might otherwise be. Nevertheless is it is undoubtedly an interesting challenge for the electronic designer (but we all enjoy a challenge). So my vote is definitely for the 1024 by 1024 pixel device with multiple outputs. A large area device is that was frame transfer devices would indeed have very great interest for spectroscopy and I suspect that although the usual response of astronomers (the bigger the better) is what they will instinctively say, it is very important to also think about what are the frame rates that could be achieved are and whether this is going to be satisfactory to achieve photon counting operation at lower signal levels. Best wishes Craig D. Mackay. - -- CCD-world -- -- CCD-world is fully moderated. Send posts to CCD-world@astro.ku.dk Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.not.iac.es/CCD-world/ From cdm at ast.cam.ac.uk Fri Mar 8 16:10:58 2002 From: cdm at ast.cam.ac.uk (Craig D Mackay) Date: Thu Jul 29 11:52:27 2004 Subject: CCD-world: FW: L3vision astronomy chips References: <200203060027.g260R6o17235@ursa.astro.ku.dk> Message-ID: <3C88D482.EDC82540@ast.cam.ac.uk> The following was posted to CCD-world: Dear Paul I missed out the Web reference of our paper in my recent message. It should have started with: "The most recent paper can be found on: http://www.mrao.cam.ac.uk/~rnt20/not2.ps In it we show that it is possible to take diffraction limited images using a ground based telescope without any adaptive optics hardware and achieve surprisingly faint limiting magnitudes." Best Wishes Craig D Mackay. - --