From apo at mail.ast.cam.ac.uk Thu Dec 22 13:08:22 1994 From: apo at mail.ast.cam.ac.uk (Paddy Oates) Date: Thu Jul 29 11:54:05 2004 Subject: Tek CTE Message-ID: Hi folks, As ststed in my last message about the WWW problem page - I have now included a few more details about the poor CTE we are seeing with our Tek CCDs. We do not get this sort of problem with our EEV devices using the same controllers/pre-amps etc. Would welcome any comments anyone has about CTE measurements they have made on their Tek devices. There's a picture of the effect on the problem page- http://cast0.ast.cam.ac.uk/~apo/docs/probs.html Have a good Christmas.... Paddy -- ___________________ * _-_ \==============_=_/ ____.---'---`---.____ * \_ \ \----._________.----/ * \ \ / / `-_-' * * __,--`.`-'..'-_ /____ || * `--.____,-' ...to boldly go where no one has gone before! REFORM:: 'To train, develop or mould by instruction, discipline or example...' Captain Paddy... -- From lesser at as.arizona.edu Mon Dec 12 15:02:18 1994 From: lesser at as.arizona.edu (Michael P. Lesser) Date: Thu Jul 29 11:54:05 2004 Subject: Steward Observatory CCD Lab home page Message-ID: <9412122102.AA16953@frodo.as.arizona.edu> Greetings, I have recently modified the Steward Observatory CCD Laboratory World Wide Web home page to include information on measured and predicted CCD AR coatings, back illuminated CCD processing information, a UV flooding recipe, and misc. information on the Lab. The URL is ftp://frodo.as.arizona.edu/pub/ccdlab.html. Suggestions are welcome. For more information, please contact Michael Lesser Steward Observatory University of Arizona Tucson, AZ 85721 (602) 621-4236 (602) 621-1532 FAX mlesser@as.arizona.edu From brucet at pcnet.com Tue Dec 6 11:02:16 1994 From: brucet at pcnet.com (Bruce E. Truax) Date: Thu Jul 29 11:54:05 2004 Subject: Spotty CCD's Message-ID: I think that your suspicion regarding the cause of the spots has a high probability of being correct. The spots that you are seeing could come from one of three causes. The first, and most common cause is dust on an optic in close proximity to the focal plane. The same effect can be caused by coating pinholes in an anti-reflection coating on a transparent window or more likely in a reflective coating on a mirror. The third cause is bubbles or inclusions in one of the windows or lenses near the CCD. Glass can be purchased in a number of "bubble" grades and it is critical in applications such as this to use material which is "bubble free". Surface imperfections, bubbles and other inclusions create scattering centers which will create spots of the type you are seeing. The problem with any of these causes is that flat fielding will not always eliminate them. Flat fielding will work if you are observing an extended source such a galaxy, but it may actually introduce inverse spots when looking at individual point objects. The reason for this is that these are scattering centers. Scattering centers do not generate any light distribution in the focal plane if there is no light to scatter. Therefore, if there is no star light striking the defect, there will be no "spot" in the image. If this is the case, subtraction of the flat field image will introduce an inverse spot. Good Luck! Bruce E. Truax Optical Engineering Consultant brucet@pcnet.com From apo at mail.ast.cam.ac.uk Tue Dec 6 12:26:39 1994 From: apo at mail.ast.cam.ac.uk (Paddy Oates) Date: Thu Jul 29 11:54:05 2004 Subject: WWW CCD Page. More additions... Message-ID: ### CCD WWW Page, News item 3 ### ----------------------------------- Hi Folkettes once more, I have included an 'agony aunt' page to my WWW pages. Again its in development so there's only a couple of 'things' in there a ce moment. The CCD page is at - (and accesible via the RGO home page, thanx to Dave Carter), So get pointing your URL at it... http://cast0.ast.cam.ac.uk/~apo/docs/ccds.html the Problem page is- http://cast0.ast.cam.ac.uk/~apo/docs/probs.html Again the whole thing is under development so don't be surprised at finding things er.. not quite finished. Comments/large amounts of money/Isle of Jura Malt/gratuitous se... welcome... Paddy -- Dont be a heel, have a look............... \ |o\/\ \=== |o/\ \ |===== |o\/ \ /===== |o/\ | / |o\/ | / |o/\ | |\_ |o\/ | | \ |o/\ \ | \ |o\/ | | \ |o/\ | | \ |o\/ | | /\ |o/\ | | / \ |o\/ | | | \ |o/\ | | | | |o\/ / | | | |o/\ | | | | |o\/ | | | | |o/\ | | | | |o\/ | | | | |o/\ | | | | |o\/ | | | | |o/\ | | | | |o\/ | | | | |o/\ \ | | | \____\ |_| | ==\_ | | \ | | | \........../ |__| -- -- ___________________ * _-_ \==============_=_/ ____.---'---`---.____ * \_ \ \----._________.----/ * \ \ / / `-_-' * * __,--`.`-'..'-_ /____ || * `--.____,-' ...to boldly go where no one has gone before! REFORM:: 'To train, develop or mould by instruction, discipline or example...' Captain Paddy... -- From prj at mail.ast.cam.ac.uk Thu Dec 1 13:46:43 1994 From: prj at mail.ast.cam.ac.uk (Paul Jorden) Date: Thu Jul 29 11:54:05 2004 Subject: CCD job at RGO Message-ID: Greetings, I draw to your attention a job opportunity at RGO, that has just been advertised. Feel free to ask if you want any further information. ---------------- THE ROYAL OBSERVATORIES THE ROYAL GREENWICH OBSERVATORY, Cambridge INSTRUMENT SCIENTIST 3 year fixed term appointment There is an an opportunity for an Instrument Scientist to work in the Technology Division of the Royal Greenwich Observatory. The successful applicant will work on the development of advanced new imaging systems for existing UK telescopes on La Palma in the Canary Islands, and on Hawaii, and on systems for the next generation of 8m telescopes. The Instrument Scientist will take a leading role in a new project to provide a mosaic of CCD devices for a wide field imaging camera system. The successful candidate will be either a professional Physicist with electronic experience, or an Electronic Engineer with some broad instrumentation skills, and will have at least two years practical experience in some of the following areas- * CCD electronics and operation; * cryogenics; * low-noise analogue electronics; * real time microprocessor electronics. The appointment will be on the "Higher" or "Senior" level of either the Science or Professional and Technology scale depending on the experience and qualifications. A broad outline of salaries based on qualifications and experience is shown below. "H" level, £13k-£19k, relevant degree or equivalent, and minimum of 2 years experience. "S" level £16k-£24k, relevant degree or equivalent, and a minumum of 4 years experience. For further information and an application form please contact, Miss J Adams, The Royal Greenwich Observatory, Madingley Road, Cambridge CB3 0EZ Tel. 0223 374000 ext. 4865 Please quote reference number 23/94. Closing date 30 Dec 1994. The Particle Physics and Astronomy Research Council has an equal opportunities policy. -------------- Best Regards, Paul Jorden ------------------------------------------------------------------- E-mail: prj@mail.ast.cam.ac.uk Machine: Kria.ast.cam.ac.uk Royal Greenwich Observatory, Madingley Road, Cambridge, CB3 0EZ, UK. Phone: +44 (0) 223- 374000 \direct phone- 374812 \RGO Fax- 374700 From apo at mail.ast.cam.ac.uk Thu Nov 17 10:33:42 1994 From: apo at mail.ast.cam.ac.uk (Paddy Oates) Date: Thu Jul 29 11:54:05 2004 Subject: Apologies ... again Message-ID: Grovel, Grovel, Er my understanding of the UNIX ~apo construct was in error... I assumed it was how you got to my public html directory but it doesnt mean that in the MOSAIC http case - THE CORRECT ADDRESS IS - http://cast0.ast.cam.ac.uk/~apo/docs/ccds.html SORRY AGAIN Paddy -- ___________________ * _-_ \==============_=_/ ____.---'---`---.____ * \_ \ \----._________.----/ * \ \ / / `-_-' * * __,--`.`-'..'-_ /____ || * `--.____,-' ...to boldly go where no one has gone before! REFORM:: 'To train, develop or mould by instruction, discipline or example...' Captain Paddy... -- From bogus@does.not.exist.com Mon Sep 26 23:45:41 1994 From: bogus@does.not.exist.com () Date: Thu Jul 29 11:54:05 2004 Subject: CCD mailing list administrivia Message-ID: Dear Colleagues, At the end of this message you will find the current list of subscribers to the CCD e-mailing list as provided by ESO. A number of new additions appear as a result of interest shown at the IAU General Assembly. New users: to send a message to *all* subscribers of the list, send email to ccd@eso.org, queries about the list may be sent to ccd-request@eso.org. Please note that the list has so far needed no editing and the membership has carefully stuck to (usually technical) discussion of astronomical CCDs on subjects which cannot easily be found in published literature. Old hands: My apologies for the recent garbage messages, they seem to be dying away now and hopefully the error will not be repeated. Best regards, Tim Abbott ESO, La Silla tabbott@eso.org ---- start list jwm@saao.ac.za John Menzies SAAO prj@mail.ast.cam.ac.uk Paul Jordan RGO apo@mail.ast.cam.ac.uk Paddy Oates RGO w.tobin@csc.canterbury.ac.nz William Tobin Mt. John tinbergen@ksw.rug.nl Jaap Tinbergen Kapteyn Obs. nz@pyxis.usno.navy.mil Norbert Zacharias USNO omiyaza@c1.mtk.nao.ac.jp Satoshi Miyazaki NAO osekigu@c1.mtk.nao.ac.jp Maki Sekiguchi NAO giovanni@astrct.ct.astro.it Giovanni Bonanno OAC noah@wise.tau.ac.il Noah Brosch Wise Obs. picat@srvdec.obs-mip.fr Pierre Picat Pic du Midi dennefel@iap.fr Michel Dennefeld IAP-Paris ege@iac.es Eduardo Martin pjm@astro.as.utexas.edu Phillip MacQueen Mcdonald Obs. agdp@gar.union.edu A. G. Davis Phillip Union College wmz@ucscloa.ucsc.edu Mingzhi Wei UCSC richard@ucscloa.ucsc.edu Richard Stover UCSC kibrick@lick.ucsc.edu Bob Kibrick UCSC gilmore@lick.ucsc.edu Kirk Gilmore UCSC leach@mintaka.sdsu.edu Bob Leach SDSU clampin@stsci.edu Mark Clampin STScI rsh@ctios1.ctio.noao.edu Ricardo Schmidt CTIO fstauffer@sunspot.noao.edu Fritz Stauffer NSO tyb@noao.edu Todd Boroson NOAO rsmith@noao.edu Roger Smith CTIO rreed@noao.edu Richard Reed NOAO jacoby@noao.edu George Jacoby NOAO awalker@noao.edu Alistair Walker CTIO burke@ccd.ll.mit.edu Barry Burke Lincoln Labs ger@hokupa.ifa.hawaii.edu Gerry Lupino IFA mckenna@cfht.hawaii.edu Dan McKenna CFHT controller@cfht.hawaii.edu Jim Wright CFHT geary@cfa.harvard.edu John Geary SAO beletic@gtri.gatech.edu Jim Beletic Georgia Tech ccdlist@as.arizona.edu Skip Schaller Arizona mlesser@as.arizona.edu Mike Lesser Steward Obs. ralph@bro835.astro.ku.dk Ralph-Florentin Nielsen Copenhagen ja@astro.ku.dk Johannes Anderson Copenhagen bt@obs.aau.dk Bjarne Thomsen IFA reif@astro.uni-bonn.de Klaus Reif Bonn rkohley@astro.uni-bonn.de Ralf Kohley Bonn marien@mpia-hd.mpg.de Karl-Heinz Marien MPIA gary_hughes@maca.sarnoff.com Gary Hughes Sarnoff bradley_art@mnb2.fss-moses.lockheed.com Art Bradley Allied Signal schild@aiub.unibe.ch Thomas Schildknecht Berne labhardt@urz.unibas.ch Lukas Labhardt Basel fgafa23@cc1.kuleuven.ac.be Ivo Verstraelen KULeuven jan@astro.oma.be Jan Cuypers KSO-ORB marijke@astro.oma.be Marijke Burger Belguim dimitris@astro.oma.be Dimitris Sinachopoulos Belgium jrb@aaoepp.oz.au John Barton AAO tabbott@eso.org Tim Abbott ESO, La Silla sdodoric@eso.org Sandro D'Odorico ESO, Garching sdeiries@eso.org Sebastian Deiries ESO, Garching rreiss@eso.org Roland Reiss ESO, Garching psinclai@eso.org Peter Sinclaire ESO, La Silla pmoore@eso.org Peter Moore ESO, La Silla oiwert@eso.org Olaf Iwert ESO, Garching nhaddad@eso.org Nicholas Haddad ESO, La Silla jcuby@eso.org Jean Cuby ESO, Garching hschwarz@eso.org Hugo Schwarz ESO, La Silla ccumani@eso.org Claudio Cumani ESO, Garching alongino@eso.org Antonio Longinotti ESO, Garching ----------- end of list From apo at mail.ast.cam.ac.uk Fri Aug 19 13:23:07 1994 From: apo at mail.ast.cam.ac.uk (Paddy Oates) Date: Thu Jul 29 11:54:05 2004 Subject: CCD Noise Message-ID: John, Jim and others... Our noise figures are determined by the method of a simlified mean versus variance (photon transfer charactersitic) type measurement. We do not (as of yet) have the facility to measure noise by the Fe55 method. I havent seen any dis-agreement in our means of meassuring the noise and other , independant measurements using the same method, eg John Barton at AAO. I would like to try and implement this at RGO, we have just set up a means of measuring QE at room temperature using the CCD in diode mode.. this has meant we can now cross check our measurements gainst other grou;s who do it the same way. Its quite fast, easy to implement, you do need a calibrated diode to measure the absolute photon flux, but this to gether with our standard photometric system has not shown any anomolies in the gain and noise we measure, the former being required in the photometric determination of the QE. Unfortunately ALL our diode measurements to date have shown consistent agreement of QE with the photometric system for all CCDs EXCEPT the new EEV thin, which appears to be showing a dramatic decrease in QE with lower temperature (i.e. 1% at 150k cf 12% at room temp and in dis-agreement with EEV/Hirst measurements when cold) ANY ONE ANY IDEAS WHY THIS SHOULD HAPPEN. EEV say that there is NO physical reason why the QE in the blue should change with Temp. RGO and EEV are trying to determine who 'has egg on their faces' !! Cheers Paddy PS . Sorry I got off the subject a little but I thought it timely to broach the subject as thinned, low noise EEV chips (measured as 2.3e rms at 150k) may be of some interest to the community!!! -- ___________________ * _-_ \==============_=_/ ____.---'---`---.____ * \_ \ \----._________.----/ * \ \ / / `-_-' * * __,--`.`-'..'-_ /____ || * `--.____,-' ...to boldly go where no one has gone before! REFORM:: 'To train, develop or mould by instruction, discipline or example...' Captain Paddy... -- From beletic at gtri.gatech.edu Thu Aug 18 17:05:19 1994 From: beletic at gtri.gatech.edu (beletic@gtri.gatech.edu) Date: Thu Jul 29 11:54:05 2004 Subject: Gain determinations Message-ID: <199408182105.RAA27529@acmez.gatech.edu> 18 August 1994 CCD Aficionados, In response to John Geary's missive about gain determination, I typically get very good agreement between Fe55 and the photon transfer curve; with the system gain from Fe55 sometimes a (very small) bit lower which we usually attribute to charge transfer inefficiency. I eagerly await your responses.....(there is not much to do in August in hot, humid Atlanta). Cheers, Jim Beletic From geary%cfa3.DECNET at cfa.harvard.edu Thu Aug 18 16:28:55 1994 From: geary%cfa3.DECNET at cfa.harvard.edu (geary%cfa3.DECNET@cfa.harvard.edu) Date: Thu Jul 29 11:54:05 2004 Subject: gain calibration Message-ID: <9408182028.AA00776@cfa.harvard.edu> The recently quoted noise figures for various CCDs (R. Smith and P. Oates) are interesting, but are they calibrated via Fe55 x-rays? I tend to distrust all gain determinations that are not subjected to this rigorous test. --John Geary geary@cfa.harvard.edu From roger at ctios1.ctio.noao.edu Wed Aug 3 11:07:36 1994 From: roger at ctios1.ctio.noao.edu (roger smith x294) Date: Thu Jul 29 11:54:05 2004 Subject: Noise...reply to Paddy Oates Message-ID: Paddy, Thanks for your response Paddy. Its great to see that several commercial suppliers are doing so well with these LDD FETs. Looking back through my AAO newsletters, I found a table of noise versus readout time for a Tek1K published by John Barton in the July 92 issue (no. 62). Is this the article you refer to? It lists 2.3 e- at 394 sec readout time. Roger From apo at mail.ast.cam.ac.uk Wed Aug 3 09:06:05 1994 From: apo at mail.ast.cam.ac.uk (Paddy Oates) Date: Thu Jul 29 11:54:05 2004 Subject: CCD read-noise, Roger Smith Enq. Message-ID: Roger, Hi. We measure routinely 3.5e on a Tek1024 CCD. At 173K, by doing stats on two identical images to work out the electronic gain and then converting our sigma sq. to noise rms e. The CDS time is 70us/pixel and 20+20 integrator slopes. This ISNT the lowest noise I have seen quoted. John Barton at AAO has a table of CCD read-speeds versus noise and he can get 2ish at LONG pixel times - 320us/pixel I think. His stuff was published in an AAO newsleter a while ago. Drain current 1.0mA, no CREs, underscan used for bias subtraction, dark current 0 for the ms integration of the 2 exposures- done with some pre-flash LEDs on the chip PCB in the dewar. Gain 1.2e/adu The lowest noise we can get, to convince you that we are (just about at present) detector noise limited is 2.5e with the new EEV 15/11 series chips which I am currently trying to quantify with EEV in terms of its 300-400nm response- these are to be the flag-ship EEV units (27/13.5um, 1024x256/2048x512 pixels) for large area devices. The read-noise of these devices appears to be best at twice our normal read-out rate (35us/pixel, 10+10us integrator slopes) and with a low drain current, 0.3mA, I have measured one chip at around 2e rms. All 'standard' operating conditions, non MPP, T=150K.. Gain 0.3e/adu... Sensitivity of FET 3uV/e. Cheers, Paddy Oates RGO UK -- ___________________ * _-_ \==============_=_/ ____.---'---`---.____ * \_ \ \----._________.----/ * \ \ / / `-_-' * * __,--`.`-'..'-_ /____ || * `--.____,-' ...to boldly go where no one has gone before! REFORM:: 'To train, develop or mould by instruction, discipline or example...' Captain Paddy... -- From roger at ctio.noao.edu Tue Aug 2 12:53:21 1994 From: roger at ctio.noao.edu (roger smith x294) Date: Thu Jul 29 11:54:06 2004 Subject: < 2 e- noise Message-ID: What is the lowest noise achieved with an astronomical CCD camera without using a skipper amplifier ? ------------------------------------------------------------------ I'd like to know what you have achieved, or what you know someone else has achieved for useful astronomical CCDs? By "useful" I mean large area, good QE, low dark current, low spurious charge, low trap count, and *commercially available*. Please specify the conditions: - Where was the noise measured: image area or overscan? - Does it include any spurious charge contribution or dark current? - Is the noise quoted the standard deviation of a region in a single frame (dodging cosmic rays) or is is square root of the stddev in a difference frame. - Has overscan correction been applied; how? - Any other image processing? - What was the readout time? - How many e-/ADU? I have heard that several groups have achieved 2.3 e- with Tek 1K or 2K CCDs. Janesick and Elliott report 1.7 e- and MIT 1.5 e- for the same Lincoln lab CCD (in ASP Conference Series Vol 23, 1992, p47). This is great news provided that the technology is successfully transferred to commercially available Astronomical CCDs, and if our CCD controllers are able to reproduce this performance. How are we doing in practice? I am pleased (this is an understatement) to announce our latest result. Tektronix (SITE) delivered a grade one 2K CCD with 4 excellent amplifiers to CTIO early this year. The CCD is excellent in every respect, and it is by far the best CCD we have ever seen. SITE deserve all the good publicit they can get for this. I have achieved the following noise figures in the most recent Arcon system delivered to Cerro Tololo: Noise +-5% 1/Gain Readout Time (quad, 2K^2) (e-) (e-/ADU) (s) ----- ---- ------------ 4.1 4.0 29 2.6 1.0 51 1.9 0.17 250 The noise quoted is the (average) of 5 standard deviations measured in different regions chosen to avoid cosmic rays, each 100 pixel wide and 50 pixels high. No frame differencing, overscan subtraction or any other processing has been applied. The dark current is currently 4e-/hour and has not been optimized. It has been necessary to reduce the P3_high voltage to reduce spurious charge. This results in a loss of full well capacity which is not seen at the high gain settings employed but does require a special adjustment when changing from imaging mode to ultra low noise mode. The noise quoted above is for the best quadrant. Yhe other amplifiers are not far behind. Noise, at 0.17 e-/ADU, 250 us/pixel (!)... Lower Left 2.1 e- Lower Right 1.9 e- Upper Left 2.1 e- Upper Right 2.4 e- It is interesting to note that the sensitivity of these CCD outputs is only about 1 uV/e-. This is very different to the Lincoln Labs' optimum output FET configuration which yields a sensitivity of about 4 or 5 uV/e-. The size of the Lightly Doped Drain FET has been reduced to the point where output sensitivity no longer increases faster than the noise voltage produced by the output FET. The lower output sensitivity of the Tek CCD would seem to imply that they have optimized their output FETs quite differently. This is good, if I am correct in presuming that Lincoln Labs' higher output sensitivity comes at the cost of proportionately earlier onset of non-linearity (lower in electrons, similar in volts at the CCD output). Are there any readers from Lincoln Labs or SITE who would like to comment? What about skipper amplifiers? ------------------------------ Has anyone other than Janesick made skipper amplifiers work? What performance did you achieve? Roger Smith Senior Electronics Engineer Cerro Tololo Inter-American Observatory (CTIO), La Serena, CHILE. Coordinates: 29.54 South, 71.16 West Internet: rsmith@noao.edu Tel: 56 (51) 225415 (English speaking receptionist 08:30-21:00) Fax: 56 (51) 205342 (direct) Post: Cerro Tololo Inter-American Observatory, Casilla 603, La Serena, CHILE. or National Optical Astronomy Observatories (NOAO) PO Box 26732, Tucson AZ 85726-6732, USA. From JohannesAndersen at bro835.astro.ku.dk Sat Jul 2 23:23:23 1994 From: JohannesAndersen at bro835.astro.ku.dk (JohannesAndersen@bro835.astro.ku.dk) Date: Thu Jul 29 11:54:06 2004 Subject: Dewar window material Message-ID: Dear Olaf, Yes, we have seen something like a 5-fold increase in cosmic ray event rate with BK7 instead of fused silica. But other components in the cameras can be radioactive too. Ralph Florentin can give you more details on his recent experiments when he returns from vacation at the end of the month. There are plans to present them at the CCD symposium in the Hague, too. Best regards, Johannes Andersen From roger at ctios1.ctio.noao.edu Fri Jul 1 09:51:14 1994 From: roger at ctios1.ctio.noao.edu (roger smith x294) Date: Thu Jul 29 11:54:06 2004 Subject: dewar connector light leak Message-ID: Reply to Paul Jorden, RGO Paul, Thanks for pointing out the light leak through the amphenol hermetic connector. We are presently using Bendix PT02H-20-41P 41 pin hermetic connectors. As soon as I read your message a focused a bright light (from a fiber optic illuminator) on the green glassy substrate of the connector and - guess what - it is quite translucent. Though there is an O-ring seal to the mating connector it is very plausible that a leak by this path could invalidate our results when comaparing dark current from various windows. I will measure the ease of ingress of light via this path and take steps to attenuate it. I find this kind of discussion on the net very helpful... Roger Smith, CTIO From prj at mail.ast.cam.ac.uk Fri Jul 1 14:14:55 1994 From: prj at mail.ast.cam.ac.uk (Paul Jorden) Date: Thu Jul 29 11:54:06 2004 Subject: light leaks in cryostats Message-ID: Greetings. Roger Smith's recent message has has reminded me of a recent problem that we discovered. We've been using Amphenol-type hermetic dewar connectors for many years. These are a glass-to-metal pin type plug. We've just seen that although they appear opaque, the do actually transmit a little light. Not normally a problem with a mating connector attached, but worth knowing about. We normally do lab. dark tests with lots of black cloths etc. so that the plug-light-leak is not evident in this case. I'm following the cosmic-ray/radioctive glass messages with interest. We always see cosmic event rates of order 2 cm-2 min-1 in all cases, with no additional events. We use specrosil-B windows. Our lab event rates are similar to those at the telescopes (ING on La Palma, 2.5 km high). regards, Paul Jorden ------------------------------------------------------------------- E-mail: prj@mail.ast.cam.ac.uk Machine: Kria.ast.cam.ac.uk Royal Greenwich Observatory, Madingley Road, Cambridge, CB3 0EZ, UK. Phone: +44 (0) 223- 374000 \direct phone- 374812 \RGO Fax- 374700 From roger at ctios1.ctio.noao.edu Fri Jul 1 09:04:10 1994 From: roger at ctios1.ctio.noao.edu (roger smith x294) Date: Thu Jul 29 11:54:06 2004 Subject: window emissions Message-ID: Variations in radioactivity for window materials have been experienced by many of us, but has anyone seen light emmission ? We were swapping windows recently and measured 1.7 e-/hr with a known good window and 3 e-/hr/pixel with a new window on the same detector. While the conditions appeared to be well controlled for the test, we would want to repeat the experiment before making any wild claims. For example, we are about to replace the window by an Aluminium disk. One could easily explain the measured difference by a light leak, except that the dewar was capped with a metal disk sealed by an O-ring, wrapped in black cloth in a dark room and no response was seen to turning on the room lights. Cosmic rays were removed before measuring image statistics. Spurious charge was measured and subtracted from these numbers. You will need a very low dark current CCD and very good light seals to see the effect, but this is the mail list to find people with such things. Has anyone seen light emission from *fused silica* windows? Roger Smith Arcon Project Senior Electronics Engineer Cerro Tololo Inter-American Observatory (CTIO), La Serena, CHILE. Coordinates: 29.54 South, 71.16 West Internet: rsmith@noao.edu Tel: 56 (51) 225415 (English speaking receptionist 08:30-21:00) Fax: 56 (51) 205342 (direct) Post: Cerro Tololo Inter-American Observatory, Casilla 603, La Serena, CHILE. or National Optical Astronomy Observatories (NOAO) PO Box 26732, Tucson AZ 85726-6732, USA. From oiwert at eso.org Fri Jul 1 12:01:32 1994 From: oiwert at eso.org (Olaf Iwert) Date: Thu Jul 29 11:54:06 2004 Subject: Dewar window material Message-ID: Dear all, in the course of new optical designs, we would like to know whether anyone has experience with the use of dewar windows, made of materials other than fused silica glass (as currently used). We are concerned especially about the potential danger for increases in the count rate of cosmic rays on thinned CCDs and are thinking of materials like BK7 and La K4. Any comments based on your experience are welcome Best regards, Olaf From prj at mail.ast.cam.ac.uk Thu Jun 30 10:35:57 1994 From: prj at mail.ast.cam.ac.uk (Paul Jorden) Date: Thu Jul 29 11:54:06 2004 Subject: Dalsa CCDs?? Message-ID: Greetings. In an idle moment, I was just wondering if anyone has made serious astronomical use, or lab. tests of any of the Dalsa chips. Can anyone give me any references/reports? I've seen their data sheets etc. My understanding is that they make these frontside chips for incorporation into cameras. They obviously work quite fast, and presumably have good quality. Have any been tested cold & slow? Cheers From richard at ucscloa.UCSC.EDU Mon May 2 10:29:18 1994 From: richard at ucscloa.UCSC.EDU (richard stover) Date: Thu Jul 29 11:54:06 2004 Subject: ARCON controller Message-ID: This is a second request for comments by astronomers who have used the NOAO ARCON CCD controller. I have heard from Roger Smith, and his response is appreciated, but I was also hoping to hear from users. I'd be interested in any evaluations. Thanks. Richard Stover Lick Observatory University of California, Santa Cruz richard@ucscloa.ucsc.edu From roger at ctios1.ctio.noao.edu Thu Apr 21 16:52:56 1994 From: roger at ctios1.ctio.noao.edu (roger smith x294) Date: Thu Jul 29 11:54:06 2004 Subject: CTIO's Arcon Message-ID: Reply to Richard Stover, Lick Obs: > > I'd like to receive peoples evaluations of the CTIO ARCON controllers. > We would like to as well! > > What is their current state of development? How easy are they to > use? What are the limitations and strengths? etc. etc. etc. > There is a description of the system available by anonymous ftp to ctio.noao.edu /pub/arcon/data_sheet.postscript.Z. Uncompress it before printing. I updated it today, but maybe you would be better off talking to our numerous users! Roger Smith, CTIO From richard at ucscloa.UCSC.EDU Thu Apr 21 12:03:35 1994 From: richard at ucscloa.UCSC.EDU (richard stover) Date: Thu Jul 29 11:54:06 2004 Subject: CTIO ARCON controllers Message-ID: I'd like to receive peoples evaluations of the CTIO ARCON controllers. What is their current state of development? How easy are they to use? What are the limitations and strengths? etc. etc. etc. Thanks Richard Stover From richard at ucscloa.UCSC.EDU Tue Mar 29 11:58:56 1994 From: richard at ucscloa.UCSC.EDU (richard stover) Date: Thu Jul 29 11:54:06 2004 Subject: SPIE paper Message-ID: At the recent SPIE conference in Hawaii we presented a paper on some of the results we have obtained with CCD devices made for us by Orbit Semiconductor. A postscript copy of the paper as it will appear in the proceedings is available. If you would like a copy please send a request to me at richard@lick.ucsc.edu. Richard Stover From abbott at ctios2.ctio.noao.edu Mon Mar 21 19:14:49 1994 From: abbott at ctios2.ctio.noao.edu (tim abbott ESO) Date: Thu Jul 29 11:54:06 2004 Subject: Hawaii Message-ID: Dear ccd-list subscribers, Speaking as one of those who was not fortunate enough to be able to attend the recent SPIE meeting in Hawaii, I for one, would be most grateful if any of you who did go would be willing to post anything interesting that you learnt (new foundries? controller systems...?), your own contribution to the conference (if the SPIE's copyright setup permits it - if postscript source is too large, perhaps invite requests for copies rather than just sending to all subscribers. Yes, I know there will be a contributions, but the best news is the hottest news) or just any juicy gossip that you might have heard (who was seen dancing in a grass-skirt on the beach and with whom?)... Thanks in advance, Tim Abbott ESO, La Silla. From reif at astro.uni-bonn.de Wed Mar 9 13:00:27 1994 From: reif at astro.uni-bonn.de (Klaus Reif) Date: Thu Jul 29 11:54:06 2004 Subject: SBIG-4 camera Message-ID: Dear Tim, I'm not shure if this message is still of interest for you. I'm back from Calar Alto observations and I have seen that the Schmidt-telescope at Calar Alto is autoguided by two SBIG-4 cameras. You may contact Ulli Thiele thiele@caserv.caha.es Klaus Reif Radioastronomisches Institut der Universitaet Bonn Auf dem Huegel 71 53121 Bonn, FRG Tel.: [49]-228-737834 FAX: [49]-228-733672 email: reif at astro.uni-bonn.de (131.220.96.55) SPAN: 29472::REIF From richard at ucscloa.UCSC.EDU Fri Mar 4 15:40:47 1994 From: richard at ucscloa.UCSC.EDU (richard stover) Date: Thu Jul 29 11:54:06 2004 Subject: CCDs at orbit Semiconductor Message-ID: To CCD Developers: I am about to start three wafer runs at Orbit Semiconductor. The wafer runs will consist of about 20 wafers each, with two CCDs per wafer. The CCDs will be approximately 4K rows by 2K columns, in a 3-side buttable design. Pixels will be 15 microns square. I am willing to consider a small number of partners on these runs. Cost for participation will be about $22,000 US. This amount buys 1/6th of the total output from the three runs (or the equivalent of 1/2 of an average run). Interested parties should contact me directly by email (richard@ucscloa.ucsc.edu) or see me at the SPIE meeting in Kona (where we will be reporting on our first 4Kx2K CCD wafer run results). Richard Stover From apo at Kria Fri Jan 21 12:35:45 1994 From: apo at Kria (Paddy Oates) Date: Thu Jul 29 11:54:06 2004 Subject: Beta Lights Message-ID: Just a comment in response to Ralph Florentins remarks about Beta sources. The blurb quotes 6%/year for the change in output due to the decay of the Tritium and the -0.3%/deg change in output quoted by Ralph, I think, do not impinge severely on our calibrations. We quote our fluxes at 20deg C and point out that measurements should be taken at this temperature. Over the integration times we use, typically 100s, we dont feel that changes in light output are significant and so the Beta sources can be used for 'spot' measuements to ensure our detectors are performing to the 5-10% level compared with our more rigorous measurements undertaken in our photometric laboratory using standard (NPL) calibrated light sources. The question regarding the Tritium has been taken up with Saunders-Roe who are investigating. The have already stated they handle many hundreds of these devices and there hasnt (to their knowledge) been a problem. We assume they are bound by regulations concerning dangers in the workplace issued by the Health and Safety Executive (at least here in the UK!). More later Paddy -- _________________________________________________________________ | .. | | /||\ . 'Step up the red alert!' | | / || \ / \ 'Are you sure?' | | / || \ / \ 'Yeah!' | | /---||___| \ / 'Only it will mean changing the bulb...' | | / || \ / | | ||addy oates | |_________________________________________________________________| From apo at Kria Fri Jan 21 10:15:28 1994 From: apo at Kria (Paddy Oates) Date: Thu Jul 29 11:54:06 2004 Subject: Stable light sources and a warning... Message-ID: I read Tim Abbott's article about Beta sources. It has me worried as the RGO has 3 sets (R, G and B) of these Beta sources, one at the ING and 2 here in Cambridge. We were assured by the company we bought them from that they were classified sufficiently low in terms of emitted particles that we did not have to take specific precautions. There was no mention of any problems should the glass break. Our sources are mounted in a small, hand-sized, cylindrical metal housing containing a filter and shutter. I guess if these were dropped the shock would fracture the glass and we do operate them in rooms, here, of 30m^3... I will discuss this with collegues here and will report on our conlusions... Being an anti-nuclear supporter I dont like the idea that any material should endanger the environment in any situation! Cheers Paddy -- _________________________________________________________________ | .. | | /||\ . 'Step up the red alert!' | | / || \ / \ 'Are you sure?' | | / || \ / \ 'Yeah!' | | /---||___| \ / 'Only it will mean changing the bulb...' | | / || \ / | | ||addy oates | |_________________________________________________________________| From ralph at bro835.astro.ku.dk Fri Jan 21 10:33:32 1994 From: ralph at bro835.astro.ku.dk (Ralph Florentin) Date: Thu Jul 29 11:54:06 2004 Subject: SBIG ST-4 (fwd) Message-ID: > > > Do any of the ccd-list readers have experience with the SBIG ST-4 autoguiding > camera? We are considering purchasing one to experiment with, but would > like to hear any knowledgeable comments first. > > Many thanks, > > Tim Abbott > tabbott@eso.org > ESO, La Silla > > > Dear Tim: We use the SBIG ST-6 at a 25 cm Cassegrain telescope in Copenhagen for teaching purposes. The students are very pleased with it. Jens Viggo Clausen who purchased the camera strongly advises you to use the ST-6 rather than the ST-4 - larger chip and better softeware. Also these cameras are so inexpensive. Kind regards Ralph. From ralph at bro835.astro.ku.dk Fri Jan 21 10:32:56 1994 From: ralph at bro835.astro.ku.dk (Ralph Florentin) Date: Thu Jul 29 11:54:06 2004 Subject: Stable light sources and a warning... (fwd) Message-ID: > > > > Dear Colleagues, > > Recent problems with ESO CCDs have prompted us to instigate a > regular programme of tests (Linearity, CTE, RON etc) of all our CCDs. > Clearly, this requires that we obtain some sort of stable light > source, preferably one dedicated to each of our 15 CCDs. Beta lights > seemed ideal for this purpose - they are cheap, small and very stable. > They fit easily within any instrument's filter wheel and, since the > actual light source consists of a flourescent screen excited by > electrons from the radioactive decay of Tritium, the light varies in a > known manner on the timescale of the half life of Tritium (12.4 yrs). > As such, they can also provide a quick indication of any variations in > QE exhibited by a CCD. > > Unfortunately, however, we have discovered that they are a > significant radiation risk. Calculations show that if the glass bulb > which contains the tritium is broken in a room of 30 cubic metres > volume, then that room must be vacated within 10 seconds to avoid > breathing a dangerous amount of Tritium (Martin Cullum, private > communication). > > We are therefore forced to abandon our plans for tests with Beta lights. > > Does anyone have any ideas for alternative solutions. We are considering > using LEDs, possibly mounting them in a filter-sized bracket with a > stabilized, dry-cell power supply to approximate the convenience of the > beta lights. Does anyone have any knowledge of the stability of LEDs over > long (day, week, month...?) timescales? > > > Many thanks, > > Tim Abbott > tabbott@eso.org > ESO, La Silla. > Hello again, Tim, Beta light sources are not really such ideally suited constant light sources. Although the beta decay of tritium is a very well defined process, the phosphor exhibits a noticeable temperature dependence. In practice this means that the light output has a temperature coefficient of typically -0.3 percent/degree centrigrade (values measured, Saunders Roe Beta lights). In our calibration rig for RQE I use a PIN Si photodiode for reference or electrical feed back. I agree that a simple LED setup would be ideal - if it is stable enough! But that I do not know. I should certainly like to be informed about it if anybody has this knowledge. Best wishes, Ralph. From pmoore at eso.org Mon Jan 17 13:07:02 1994 From: pmoore at eso.org (Peter Moore) Date: Thu Jul 29 11:54:06 2004 Subject: shutters Message-ID: Hi everyone, I originally posted this to Bob directly, however, I now realize that this is a forum and as such .... > > Hi Bob, > Read your enquiry about shutters and since I have a few minutes to spare > I thought I'de contribute my 'Two Bobs Worth'. > > We currently use, as a standard, Prontor shutters available from Prontor > directly in West Germany. These shutters are available with a variety of > aperture sizes and drive mechanisms. The shutters are robust and reliable, > being based on the iris principle and driven by one or two solenoids. > Their model E/64 fits your description. It has a 64mm aperture and > measures 147mm square by 35mm high. The operating time is rather slow at > around 25ms to open and 40ms to close. The open and close delay times > are generally constant although they are affected by temperature. The > models we use have 200 ohm coils and we drive these beasts open with a > 24 volt source, then sense the shutter open with a hall effect switch and > reduce the drive to 8v which holds the shutter open and reduces heat > dissipation by the solenoid. Failures are rare and are generally caused > by contamination of the iris leaves by coffee etc :-). > > In regard to focal plane or blind shutters that elliminate exposure > gradients, we have never experimented with them (comercial ones) although > I know that Hassellblad does make a focul plane shutter for their frame > cameras ($$$) that could be modified. No details on aperture size etc. > > We did build one focal plane shutter for a particular instrument. This > was made as a disk with a slot cut into the circumference wich equalled > the aperture. The disk was rotated by a motor so that when the disk was > in the field the shutter was closed. Then, when the disk was rotated to > the open position, one side of the field was exposed first. When the > shutter was closed (again rotating in the same direction), this same > side was closed first. This of course is this same old device used in > movie cameras. > > Tektronix have a commercial device that consists of 2 lcd panels > together that they use as a light modulator on some of their diplays. > This device then acts as a fast (~2ms) shutter. The problem is that > the glass used in the lcd is probably not optically usefull for > scientific purposes and there would be residual attenuation from the > lcd matrix. > > Have fun, hope this helps out a bit, > regards, > Peter Moore, > Detectors Lab, > La Silla. > > > P.S Great Forum, at last one that is Interesting !! From walker at ctiow3.ctio.noao.edu Mon Jan 17 10:30:22 1994 From: walker at ctiow3.ctio.noao.edu (a.walker x295) Date: Thu Jul 29 11:54:06 2004 Subject: shutters Message-ID: At CTIO we have for several years been using Prontor Magnetic E 100 shutters which have 100mm clear aperture. There are also models with 70, 64 and 40 mm aperture. When used with a Tek 2048 the center-corner exposure time difference is about 50 ms. The shutter timing values are very stable with time and do not seem to vary with temperature. We have found these units to be very reliable. They are made by Prontor-Werk Alfred Gauthier GmbH D-7547 Wildbad-5/Schwarzw, Stadtteil, Calmbach, tel. 07081/781-1. the US agent is Geiss-America, 4821 W. Main Street, Skokie, Illinois 60077, tel (312) 674-5800. Cost about $800 for the E-100, depending on options. We have also used the UNIBLITZ model 262X. This has 63.5mm clear aperture. It is available from Vincent Associates, 1255 University Avenue, Rochester, NY 14607. tel (716) 473-2232, fax (716) 244 6787. Cost was $600 in 1988. We also use smaller UNIBLITZ shutters for various applications, these are very compact and have given little trouble. Alistair Walker From reif at astro.uni-bonn.de Mon Jan 17 10:27:39 1994 From: reif at astro.uni-bonn.de (Klaus Reif) Date: Thu Jul 29 11:54:06 2004 Subject: large aperture shutters Message-ID: Hi Bob and others, we use a Melles Griot iris type shutter (04 IES 005) with our 2kx2k 15micron CCDs. Its aperture is 60mm. We have measured its delay times - relative to the falling/rising edge of the signal - and opening times at temperatures between -13C and +26C. T = 26 C T = 5 C T = -13 C delay (open) 20.8ms 20.2ms 27.3ms duration(open) 14.5ms 12.5ms 18.0ms delay (close) 52.0ms 55.0ms 62.4ms duration(close) 31.3ms 27.3ms 27.2ms Errors are of the order of 2ms. The shutter behavior is almost independent of the ambient temperature. At the centre the exposure times are longer by about 40 to 45ms compared to exposure times at a radial distance of about 30mm. Due to different delay times exposures are about 30ms longer than given by the control signal. It would be very interesting to see how these values compare to those of other large aperture shutters currently in use. Klaus Reif ____________________________________________________________ | Klaus Reif | | | | Radioastronomisches Institut | | der Universitaet Bonn | | | | Auf dem Huegel 71 reif@astro.uni-bonn.de | | 53121 Bonn phone: 49 228 737834 | | Germany FAX: 49 228 733672 | |____________________________________________________________| From jb105 at prism.gatech.edu Fri Jan 14 15:14:50 1994 From: jb105 at prism.gatech.edu (jb105@prism.gatech.edu) Date: Thu Jul 29 11:54:07 2004 Subject: Shutters Message-ID: Bob et al, For relatively long exposures (1 sec or more) we have found the Uniblitz shutters to be good. However, for fast framing (50-100 Hz), the Uniblitz shutters, which can open in a few milliseconds, get very warm and tend to wear out quickly. So for fast framing we use a spinning blade shutter, like those made for chopping laser beams. I am interested in the devices others use. Of course, the best would be to have a good electronic shutter in the CCD chip itself. Are you aware of the electronic shutters used in some of the MIT Lincoln Laboratory CCD chips which can open/close in less than 50 nanoseconds? These can have high extinction but can only be put into backside illuminated chips. It would be wonderful if all backside illuminated chips had this feature. Cheers, Jim Beletic Georgia Tech Research Institute beletic@gtri.gatech.edu From leach at suicide.SDSU.Edu Fri Jan 14 11:25:12 1994 From: leach at suicide.SDSU.Edu (Robert Leach) Date: Thu Jul 29 11:54:07 2004 Subject: shutters Message-ID: I'd like to "contribute" a question. I'm looking to buy shutters to operate 2048 square 15 micron CCDs, so need a 50 mm or so shutter. Does anyone know of a good supplier of iris type diaphragm shutters, or preferably a shutter that gives equal exposure times for all regions on the CCD? Bob Leach San Diego State University leach@mintaka.sdsu.edu From shalonso at ull.es Tue Oct 11 11:57:32 1994 From: shalonso at ull.es (Sergio Hernández Alonso) Date: Thu Jul 29 11:54:36 2004 Subject: large ccd for spectroscopy Message-ID: <2E9A618C.C7C6487D@ull.es> Posted to CCD-world: -+-+-+- Dear CCD Friends At the University of La Laguna we are trying to make a prototype of a cooled CCD camera for spectroscopy. Our main restrictions are: CCD chip area: 20 X 2 mm or higher Exposition time from 10 to 100 micro seconds Low noise High sensitivity Wave-length from 400 to 1100 nm Budget less than 2000 USA dollars If anyone knows a good CCD chips, a place to find electronics diagrams or anything concerning this subject we will appreciate a response. Yours -- SERGIO HERNANDEZ SERVICIO ELECTR?NICO FAC. F?SICAS UNIVERSIDAD DE LA LAGUNA 38071 TENERIFE SPAIN TF: 34(9)22318290 FAX: 34(9)22630040 -+-+-+- For information about CCD-world, send email to owner-CCD-world@cfht.hawaii.edu.