From afa at star.le.ac.uk Thu Dec 19 17:17:05 1996 From: afa at star.le.ac.uk (Tony Abbey) Date: Thu Jul 29 11:54:15 2004 Subject: MHz pixel rate deep depletion CCD In-Reply-To: <199612161501.JAA15729@phoebus> Message-ID: Our group here at Leicester has been developing high resistivity CCDs with EEV for many years. These are for direct detection of X-rays, and we have been able to procure up to 8000 ohm-cm EPI, and also very high res bulk silicon. The latest CCDs for the XMM EPIC Xray astronomy satellite with 600 X 600 frame transfer 40 micron pixels and open-electrode structure for good low energy QE at 100eV and high res for good QE up to around 15keV are being tested now. Expected depletion depths are around 50 microns. We are not using EEV's latest fast low noise o/p node configuration, since we run at 5 microsec/pixel, but I believe the above CCDs can have the o/p node reconfigured to use the new structure, giving under 5 electrons at 1MHz. _________________________________________________________________________________ Tony Abbey E-mail: afa@star.le.ac.uk CCD Group Dept. of Physics and Astronomy Phone: +44 116 252 3490 University of Leicester Fax: +44 116 252 3311 University Road LEICESTER LE1 7RH United Kingdom _________________________________________________________________________________ From hoffberg at aps.anl.gov Mon Dec 16 10:01:36 1996 From: hoffberg at aps.anl.gov (Mike Hoffberg) Date: Thu Jul 29 11:54:15 2004 Subject: MHz pixel rate deep depletion CCD Message-ID: <199612161501.JAA15729@phoebus> I am looking for a high-speed CCD that can be used for direct X-ray exposure. At the moment we are using CCDs such as the TH7895 and the TC215 with phospher to image X-rays. We are trying to improve the characteristics of our camera system, so we would like to try to build a camera around a deep depletion CCD. Currently we are able to clock out our CCDs at a pixel rate of over 15 MHz and digitize the data with a 12-bit ADC. (With 2 outputs, the TH7895 camera system can have a frame rate of 100 fps). If anyone has any suggestions for a deep depletion CCD I would appreciate hearing from you. MIKE -- Michael Hoffberg Advanced __/- hoffberg@aps.anl.gov Photon __/==== Argonne National Laboratory Source __/******* http://www.aps.anl.gov/xfd/WWW/xfd/Detectors ________/########## From prj at ast.cam.ac.uk Mon Dec 16 09:16:26 1996 From: prj at ast.cam.ac.uk (Paul Jorden) Date: Thu Jul 29 11:54:15 2004 Subject: X-ray source (repeat) Message-ID: Greetings Barry & ccd-world, > > You might be interested to learn of a variable x-ray source produced by > Amersham International which can be used outside a dewar window. > [cut...] > We purchased this item in 1991, and its product code then was AMC2084, but > can't recall the price. I have a British phone number where you might > reach them: (0494) 544000. All UK area dialling codes now have an extra '1' digit. ie Amersham should be +44 (0)1494-544000 The extra energy of the source increases the safety hazard. We decided to only invest in the standard Fe55 source for two main reasons: 1. Safety. 2. We are interested in checking the CTE at low charge levels; the more energetic source cannot do this so well. Of course, the higher energy presumably gives an even better determination of the 'e/ADU' conversion 'gain'. I'd be interested in hearing if anyone has found such higher energy sources to be useful. (I know Andrew Holland & colleagues at Leicester use them- but they need to quantify CCDs as detectors for x-ray astronomy anyway). Cheers, Paul ------------------------------------------------------------------- E-mail: prj@ast.cam.ac.uk Web: http://www.ast.cam.ac.uk/RGO Royal Greenwich Observatory, Madingley Road, Cambridge, CB3 0EZ, UK. Phone: +44 (0) 1223- 374000 \direct phone- 374811 \RGO Fax- 374700 ------------------------------------------------------------------- E-mail: prj@ast.cam.ac.uk Web: http://www.ast.cam.ac.uk/RGO Royal Greenwich Observatory, Madingley Road, Cambridge, CB3 0EZ, UK. Phone: +44 (0) 1223- 374000 \direct phone- 374811 \RGO Fax- 374700 From prj at ast.cam.ac.uk Mon Dec 16 09:15:15 1996 From: prj at ast.cam.ac.uk (Paul Jorden) Date: Thu Jul 29 11:54:15 2004 Subject: camera calibration (repeat) Message-ID: Nick, > Can anyone tell me the technique used to measure the calibration > between the number of electrons on the gate of the output FET and ADC > counts for a typical CCD Camera? > Gerry Luppino has already told you the best way to do it. The alternative is the 'photon-transer curve' technique; this was basically described in: Mortara & Fowler, 1981, Proc SPIE 290, 28. We use both techniques, and they agree with each other. The x-ray technique works best if you have an x-ray source; the disadvantage is that you need the x-ray source inside the CCD camera head, or the other side of a thin Beryllium window. If you want to know more give me a call. Regards, Paul J ------------------------------------------------------------------- E-mail: prj@ast.cam.ac.uk Web: http://www.ast.cam.ac.uk/RGO Royal Greenwich Observatory, Madingley Road, Cambridge, CB3 0EZ, UK. Phone: +44 (0) 1223- 374000 \direct phone- 374811 \RGO Fax- 374700 From ger at hokupa.IFA.Hawaii.Edu Thu Dec 12 07:52:48 1996 From: ger at hokupa.IFA.Hawaii.Edu (Gerard Luppino) Date: Thu Jul 29 11:54:15 2004 Subject: camera calibration Message-ID: <9612121652.AA00598@hokupa.ifa.hawaii.edu> Hi Paul, Just to clarify your message, if you are using Fe55 x-rays, you don't need a "thin" Be window. I've used windows with thicknesses from 0.1mm up to 0.5mm! The 0.5mm is a pretty strong hunk of metal and can span a rather large (10mm or more) hole and not have any problems withstanding vacuum. You can get Be pretty cheaply in the thicker sizes and can make a mesh frame that allows you to make a Be window large enough for a big focal plane. Also, The thicker Be is totally opaque to optical light (well, so is 0.1mm Be). Users should beware of the hazards of workking with Be, however. Be dust is pretty nasty stuff. The material should not be cut or machined without the proper precautions and equipment. Aloha, Gerry From prj at ast.cam.ac.uk Thu Dec 12 17:48:11 1996 From: prj at ast.cam.ac.uk (Paul Jorden) Date: Thu Jul 29 11:54:15 2004 Subject: X-ray source Message-ID: Greetings Barry & ccd-world, > > You might be interested to learn of a variable x-ray source produced by > Amersham International which can be used outside a dewar window. > [cut...] > We purchased this item in 1991, and its product code then was AMC2084, but > can't recall the price. I have a British phone number where you might > reach them: (0494) 544000. All UK area dialling codes now have an extra '1' digit. ie Amersham should be +44 (0)1494-544000 The extra energy of the source increases the safety hazard. We decided to only invest in the standard Fe55 source for two main reasons: 1. Safety. 2. We are interested in checking the CTE at low charge levels; the more energetic source cannot do this so well. Of course, the higher energy presumably gives an even better determination of the 'e/ADU' conversion 'gain'. I'd be interested in hearing if anyone has found such higher energy sources to be useful. (I know Andrew Holland & colleagues at Leicester use them- but they need to quantify CCDs as detectors for x-ray astronomy anyway). Cheers, Paul ------------------------------------------------------------------- E-mail: prj@ast.cam.ac.uk Web: http://www.ast.cam.ac.uk/RGO Royal Greenwich Observatory, Madingley Road, Cambridge, CB3 0EZ, UK. Phone: +44 (0) 1223- 374000 \direct phone- 374811 \RGO Fax- 374700 From jb at galileo.apo.nmsu.edu Thu Dec 12 12:15:42 1996 From: jb at galileo.apo.nmsu.edu (Jon Brinkmann) Date: Thu Jul 29 11:54:15 2004 Subject: Amersham International (Was: Re: X-ray source) Message-ID: <199612121815.LAA24983@galileo.apo.nmsu.edu> > We purchased this item in 1991, and its product code then was AMC2084, but > can't recall the price. I have a British phone number where you might > reach them: (0494) 544000. There is an American office in Arlington > Heights, Illinois. See http://www.amersham.com/ or http://www.amersham.co.uk/. Jon --- Dr. Jon Brinkmann Apache Point Observatory Instrument Scientist 2001 Apache Point Road Internet: brinkmann@nmsu.edu P.O. Box 59 URL: http://www.apo.nmsu.edu/brinkmann/ Sunspot, NM 88349-0059 From bburke at ll.mit.edu Thu Dec 12 10:36:13 1996 From: bburke at ll.mit.edu (Barry E. Burke) Date: Thu Jul 29 11:54:15 2004 Subject: X-ray source Message-ID: <9612120936.AA14497@LL.MIT.EDU> Dear Nick (and all other CCD folks out there), You might be interested to learn of a variable x-ray source produced by Amersham International which can be used outside a dewar window. It consists of an Am-241 source which can be aimed at any of six targets. The emissions from the Am-241 cause x-ray fluorescence from the targets and are a convenient source of variable x-ray energies. The source is compact (37 mm diameter by 23 mm high), and the target wheel can be rotated to present each target to the primary source. The targets, their K-alpha energies, and photoelectron count in silicon are: 1.Cu 8.04 keV 2203 e- 2.Rb 13.4 3663 3.Mo 17.4 4778 4.Ag 22.1 6055 5.Ba 32.1 8784 6.Tb 44.2 12,118 Of course, the higher energies interact less with the silicon, and so one needs much longer integration times to collect enough events. On the other hand, the flux from this source increases as the energy goes up (30X more at Tb than Cu). Am-241 has a half-life of 433 years, so its output will be quite stable in contrast to Cd-109. I believe someone here at Lincoln successfully used even the Cu line through the window of his dewar. We purchased this item in 1991, and its product code then was AMC2084, but can't recall the price. I have a British phone number where you might reach them: (0494) 544000. There is an American office in Arlington Heights, Illinois. Barry Burke Barry E. Burke M.I.T Lincoln Laboratory, M.S. LI-127 244 Wood Street Lexington, MA 02173-9108 bburke@ll.mit.edu Phone: (617) 981-0680; FAX: (617) 981-5957 From bogus@does.not.exist.com Wed Dec 11 23:30:29 1996 From: bogus@does.not.exist.com () Date: Thu Jul 29 11:54:15 2004 Subject: Help Message-ID: <9612111430.AA04932@sun10.bao.ac.cn> mail ccd-world@cfht.hawaii.edu Looking for long rectangular CCD array (thousands by 256 pixels) for solar spectroscopy, could anyone tell us where is the longest area array avariable at this moment? Thank you in advance Binxun Ye _________________________________________________________________ Binxun Ye E_Mail: bxye@bao01.bao.ac.cn Research Labs For Astronomy ybx@sun10.bao.ac.cn Beijing Observatory Telephone: +86-10-62569840 ZhongGuanCun Telefax: +86-10-62561085 BEIJING, 100080 China ________ From tmca Wed Dec 11 15:33:28 1996 From: tmca (Tim Abbott) Date: Thu Jul 29 11:54:15 2004 Subject: Forwarded from Binxun Ye Message-ID: <199612120033.OAA28022@kuanalu.cfht.hawaii.edu> Binxun Ye had trouble getting this through: Looking for long rectangular CCD array (thousands by 256 pixels) for solar spectroscopy, could anyone tell us where is the longest area array avariable at this moment? Thank you in advance Binxun Ye _________________________________________________________________ Binxun Ye E_Mail: bxye@bao01.bao.ac.cn Research Labs For Astronomy ybx@sun10.bao.ac.cn Beijing Observatory Telephone: +86-10-62569840 ZhongGuanCun Telefax: +86-10-62561085 BEIJING, 100080 China __________________________________________________________________ From ger at hokupa.IFA.Hawaii.Edu Wed Dec 11 07:56:52 1996 From: ger at hokupa.IFA.Hawaii.Edu (Gerard Luppino) Date: Thu Jul 29 11:54:15 2004 Subject: Gain by Photon Transfer method Message-ID: <9612111656.AA02762@hokupa.ifa.hawaii.edu> Hi Roger and all, You are absolutely right abou the window. To use Fe55 x-rays you need to swap the optical window for an x-ray transmitting window (Be, say) or mount the source inside the dewar. Either way, its a pain for a camera in regular use in an observatory setting. However, Jim Janesick showed us an alternative a few years back. Instead of using a 5.89 keV Fe55 source, you can use a ~22keV Cd source. A lot of these x-rays will get through most dewar windows. They'll also zip right through the CCD, but I understand that enough will have interactions that you can use the same technique. This time, of course, you'll generate ahcrge packets of 22 keV/3.65 eV/e-h pair. I've been wanting to get such a source for years, but have never gotten around to it. Indeed, the photon transfer curve method is straightforward enough that it can be used fairly reliably for getting the "gain". Aloha, Gerry From prj at ast.cam.ac.uk Wed Dec 11 09:47:07 1996 From: prj at ast.cam.ac.uk (Paul Jorden) Date: Thu Jul 29 11:54:15 2004 Subject: camera calibration Message-ID: Nick, > Can anyone tell me the technique used to measure the calibration > between the number of electrons on the gate of the output FET and ADC > counts for a typical CCD Camera? > Gerry Luppino has already told you the best way to do it. The alternative is the 'photon-transer curve' technique; this was basically described in: Mortara & Fowler, 1981, Proc SPIE 290, 28. We use both techniques, and they agree with each other. The x-ray technique works best if you have an x-ray source; the disadvantage is that you need the x-ray source inside the CCD camera head, or the other side of a thin Beryllium window. If you want to know more give me a call. Regards, Paul J ------------------------------------------------------------------- E-mail: prj@ast.cam.ac.uk Web: http://www.ast.cam.ac.uk/RGO Royal Greenwich Observatory, Madingley Road, Cambridge, CB3 0EZ, UK. Phone: +44 (0) 1223- 374000 \direct phone- 374811 \RGO Fax- 374700 From roger at ctios1.ctio.noao.edu Wed Dec 11 11:50:43 1996 From: roger at ctios1.ctio.noao.edu (roger smith x294) Date: Thu Jul 29 11:54:15 2004 Subject: erratum Message-ID: <9612111350.AA06703@ctios1> Should read: "Gerry is right about the peak in the Fe55 histogram being a quick, easy, and precise method to determine gain but he forgot to mention that...." Sorry, ...a copy paste error. Roger From roger at ctios1.ctio.noao.edu Wed Dec 11 11:08:52 1996 From: roger at ctios1.ctio.noao.edu (roger smith x294) Date: Thu Jul 29 11:54:15 2004 Subject: Gain by Photon Transfer method Message-ID: <9612111308.AA06224@ctios1> Nick, Gerry is right about the peak in the Fe55 histogram being a quick, easy, and precise method to determine but to mention that 5.89 keV X-rays don't pass through a fused silica ("quartz") dewar window. To do the Fe55 test you have to replace the optical window temporarily with a Beryllium, or build the Fe55 source into your dewar along with a method for retracting it into an X-ray-tight shield. This is great in a lab dewar but in real applications one often has to locate the CCD too close to the window to fit the Fe55 retractor because of back focal distance requirements of the optics. The "Photon Transfer" method is the standard way to measure gain. In practice this means taking pairs of identical flat field exposures at various illuminations and plotting the variance of the difference within each pair against the sum of the means, for a region selected to be free of cosmetic defects. The slope is then the gain, in units of ADU/e-. The differencing removes pixel to pixel sensitivity variations, leaving only noise. The point at which the curve deviates from linear is the full well capacity or saturation level and the Y-intercept is the square of the read noise. Read noise is more accurately obtained from a zero length dark frame than extrapolating the variance curve. You can get the gain from just two illumination levels (4 frames), but it is safer to plot a curve to ensure that the system is behaving itself. The math is trivial. For poission statistics.... variance = mean (e-) ........(1) Define gain, A = number of ADU per electron then (A**2)variance = VARIANCE (ADU) ........(2) and A*mean = MEAN (ADU) ........(3) Substituting (2) and (3) into (1): VARIANCE = A*MEAN (ADU**2) ........(4) The variance of the difference is twice the variance of the shot noise component of a single frame, so by plotting against the sum of the means, the factors of 2 cancel. Astronomers express "gain" in units of e-/ADU (the inverse of gain) just to keep out the riff raff. Roger Smith, CTIO From ger at hokupa.IFA.Hawaii.Edu Tue Dec 10 09:41:18 1996 From: ger at hokupa.IFA.Hawaii.Edu (Gerard Luppino) Date: Thu Jul 29 11:54:15 2004 Subject: camera calibration Message-ID: <9612101841.AA00432@hokupa.ifa.hawaii.edu> Hi Nick, BY far the easiest and most error-free way to do this is to use the Fe55 x-ray calibration. The drawback is you need to buy or have access to a radioactive Fe55 source (they are cheap and not dangerous, but it isn't the easiest thing to find). The technique works as follows: The K-kapture decay of Fe55 produces a Manganese K-alpha x-ray of 5.89 keV. This x-ray is absorbed in the silicon, producing a charge cloud with size proportional to the energy of the x-ray. The conversion factor is 3.65 eV/e-h pair. Therefore the absorbed 5.9keV x-ray produces a cloud of size 1616 electrons. The variance in the number of electrons produced does not obey Poisson statistics, but rather is weighted by bthe "Fano" factor, which is 0.1 for silicon. Therefore the variance in the number of electrons is F*N = 160 and the rms is the sqrt of 160 -- not a large number. To calibrate a CD gain, one illuminates a CCD with x-rays (10 microcurie to 1 mcurie source is plenty bright enough). You want to have a reasonable number of x-ray events but want to remain in the regime where it is unlikely that many pixels have two events. One then reads out the CCD and looks at the histogram of pixels. You should see a large spike at the bias level value with a small peak at some ADU value that corresponds to 1616e-. Reading off that number on the ADU axis agives you the conversion of e-/ADU. There are nuances to this method, and it is EXTREMELY useful for diagnosing low level charge transfer problems, but the above is the quick and dirty discription. Aloha, Gerry Luppino From nick at msi.campus-ventures.co.uk Tue Dec 10 18:52:57 1996 From: nick at msi.campus-ventures.co.uk (Nick Heyes) Date: Thu Jul 29 11:54:15 2004 Subject: camera calibration Message-ID: <199612101903.TAA25680@msi.campus-ventures.co.uk> Hi, Can anyone tell me the technique used to measure the calibration between the number of electrons on the gate of the output FET and ADC counts for a typical CCD Camera? Regards, Nick --------------------------------------- Dr. Nick A.E. Heyes, Manchester Scientific Instruments Ltd., Campus Ventures Centre, Manchester University, Dover Street, Manchester M13 9PL, U.K. Tel: 0161 934 0004 FAX: 0161 273 5111 E-Mail: nick@msi.campus-ventures.co.uk Web Site: http://msi.campus-ventures.co.uk/naeh.htm --------------------------------------- From tmca Thu Dec 5 18:52:50 1996 From: tmca (Tim Abbott) Date: Thu Jul 29 11:54:15 2004 Subject: Problems with CCD-world Message-ID: <199612060352.RAA07373@kuanalu.cfht.hawaii.edu> The recent problems with CCD world have probably resulted from the Hawaii<->Mainland upgrades that UH has been working on. We have seen badly reduced bandwidth from time to time. Once this upgrade is complete, I hope that the problems will go away (if they have not already). In the meantime, if your messages do bounce, or fail to appear, please send them on to me, and I will remail them. Otherwise, please use CCD-world as normal. I know it is tempting, but I would appreciate it if subscribers would not send test messages to CCD-world themselves -- the remailer is really quite dumb (deliberately so) and such test messages do not acheive much. Alternatively, the challenge is to say something erudite about CCDs in such a message! Speaking of which: Keck observatory were recently kind enough to arrange a two-day seminar on vacuum technology and were kind enough to invite CFHT personel. One recommendation which I thought I would pass on to those who are interested is that we do not grease O-rings, or at least, use the smallest amount on those surfaces which are under mechanical pressure. Another interesting tidbit: the manufacturer's definition of Viton, a common O-ring material, requires that it contain only 25% actual Viton. The rest can be anything - old tires, shoe soles, whatever. The recommendation, therefore, for reliable O-rings is that the buyer explicitly ask what fraction of Viton is in his O-rings. And another: turbopumps should be allowed to slow to half speed after use and then vented with dry nitrogen to avoid contamination with lubricants from a roughing pump. Cheers, Tim -- Timothy M. C. Abbott http://www.cfht.hawaii.edu/~tmca/tmca.html From apo at ast.cam.ac.uk Mon Dec 2 10:56:00 1996 From: apo at ast.cam.ac.uk (Paddy Oates) Date: Thu Jul 29 11:54:16 2004 Subject: Fast CCD clearing Message-ID: Tim and Tim and others, We have used a fast clear option on our Teks foe a few years. We have also now implemented a FLASH clear on the EEV42 device as they come with a dump drain along the serial register. We gained a factor of about 80 on the Teks going from Std clear (1 row at a time with a register scan, done twice) to Quick clear which implements a 50 rows bin into the S.register, with the register clock highs, and at the end does a 50x1 row shift into the SR with a SReg scan(twice). I think the latter is important to ensure the register is clear and no charge flows back into the image area. The flash clear on the EEV gets down to 0.4s to clear the whole array twice using the dump drain BUT we still scan the SR at the end. If we dont I saw charge flow back to the image area. Peter Poole told me a time delay after the last row was dumped into the SR would also have achieved the same effect - allowing the charge to fully drain down the plug-hole.... Hope this helps Paddy -- Contact - work :: Tele +44 (0)1223 374836 Fax +44 (0)1223 374700 E-Mail apo@ast.cam.ac.uk apo@apoates.demon.co.uk WWW Page http://www.ast.cam.ac.uk/~apo/ CCD Page http://www.ast.cam.ac.uk/~apo/docs/ccds.html Personal Web Pages http://www.apoates.demon.co.uk -------------------------------------------------------------- -- Contact - work :: Tele +44 (0)1223 374836 Fax +44 (0)1223 374700 E-Mail apo@ast.cam.ac.uk apo@apoates.demon.co.uk WWW Page http://www.ast.cam.ac.uk/~apo/ CCD Page http://www.ast.cam.ac.uk/~apo/docs/ccds.html Personal Web Pages http://www.apoates.demon.co.uk -------------------------------------------------------------- From rsmith at ctiot0.ctio.noao.edu Wed Dec 4 12:41:56 1996 From: rsmith at ctiot0.ctio.noao.edu (Roger M. Smith) Date: Thu Jul 29 11:54:16 2004 Subject: Reset feedthrough & linearity References: <199612040047.AAA23551@sys4.cambridge.uk.psi.net> Message-ID: <32A5D404.2AB0@ctio.noao.edu> huw.prytherch@unicam.co.uk wrote: > > Hi Roger, > I saw your message about reset feedthrough. I have done some work on > linearity of the KODAK 1300-L CCD, and played with most of the voltages > around the output stage. These are some of my findings/ conclusions: > > As you said, when Reset ck goes high, the output node capacitance is > connected via the reset FET to Vrd, and the node capacitance should be > charged up to Vrd. However, when Reset ck goes low, the falling edge is > capacitively coupled via the FET gate-source capacitance onto the output > node capacitance giving rise to the -ve going edge of the reset > feedthrough. > > The FET needs a sufficiently large Vgs (gate-source voltage) in order to > turn it off properly. If there are not enough volts, then when the output > node fills with charge (and node voltage drops - reducing the voltage > diference between gate and source) the FET will try and turn on again and > the node capacitance will start charging from Vrd. In equilibrium, this > will cause the voltage at the output to saturate at some signal level. > This level may be less than the saturation level for the imaging area > i.e. the apparent full well level is reduced. I found that this also > happened when the reset drain voltage (Vrd) was reduced - for the same > reasons (not enough Vgs when charge transferred to the output node) - > this can be overcome by also reducing Reset ck (low). > > The output stage amplifier of the 1300-L appears to show increased > non-linearity as the output node voltage approaches the supply rail Vdd > (not uncommon for amps I suppose). The operating point of the output > stage will be dependant on the output node voltage after reset. By > reducing the reset feedthrough, the output will be operating at a > slightly higher voltage and this may affect linearity. > > I hope that some of this is of use / interest to you. I would be > interested in any comments you have, > > Regards, > Huw Prytherch. Huw, Whatever is causing non-linearity would have to be happening on the output node itself (the gate of the output FET) rather than being a reduction of drain-source voltage (VDS) of the output FET, since reset feedthrough is small (0.25 V) compared to VDS. Linearity doesn't depend on such small changes, at least in my experience. How far did you find you had to place RG_low below the threshold of the Reset FET to turnnit off fully? 2V below threshold (3 V above substrate) looked safe for the TEK2048EB I was testing. Roger From preben at astro.ku.dk Mon Dec 2 08:39:17 1996 From: preben at astro.ku.dk (Preben Noerregaard) Date: Thu Jul 29 11:54:16 2004 Subject: From Tim Hardy In-Reply-To: <199611291838.AA23450@uwila.cfht.hawaii.edu> Message-ID: Hi Tim This is the flushing mode we are using as standard on our Loral 2k3eb's. All serials, SW, OG and RG are held high during the parallel clocking. It is true that, especially at high flat levels, there may be remaining charge is the image. For this reason we run the parallels typically 10-20% more than the length of the parallel (2200 cycles for a 2kx2k) and complete the procedure with a similar sweep of the serial reg. The potential barrier between the serial and up to the parallel may be too weak on your TK512, so it simply doesn't work on your CCD. 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 -------------------------------------------- From roger at ctiol3.ctio.noao.edu Sat Nov 30 17:24:40 1996 From: roger at ctiol3.ctio.noao.edu (roger smith x294) Date: Thu Jul 29 11:54:16 2004 Subject: CCD Reset Feedthrough Message-ID: <9611301924.AA23044@ctiol3> _________________________________________________________ A METHOD TO REDUCE RG FEEDTHROUGH ! ......Increase RG low. _________________________________________________________ Most subscribers to ccd-world are familiar with the pesky feed-through of the CCD Reset pulse, but for those who aren't... It is a +200 mV to +300 mV transient on VOS during CCD Reset, similar in amplitude and opposite in sign to the signal. It can cause signal chain saturation and at the very least carries a settling time penalty which becomes increasingly relevant as we read faster. We have seen all sorts of circuit designs to accommodate it: diodes across gain setting resistors (a linearity hazard), clamping switches, and increased supply rails plus faster settling op amps. Some fast op amps, notably the Burr Brown OPA627, can take microseconds or even tens of microseconds to recover from saturation (depending on which rail), so it is especially important to deal with reset feedthrough. Having never heard of a way to reduce it, I assumed that it was an inescapable feature of CCDs. I had been thinking of it as a narrow positive going pulse - the way it looks on the oscilloscope. This led me to adjust the high level of Reset Gate. This has no effect since the output node is connected to Reset Drain while RG is high. With copious hindsight it is obvious that the same doesn't apply to the low level of RG. When the Reset Gate falls below the threshold of the reset FET, the reset switch opens and its gate-source capacitance (2-3 femtofarads) can no longer be charged from Reset Drain. Charge is shared between it and the CCD output node. The voltage change on the output node is proportional to the difference between the Reset FET's turn-off threshold and the **low** level of RG. The feedthrough pulse is really a high duty cycle low going pulse! If you set RG_low too high then the reset switch doesn't turn off fully. I found that the reset FET's threshold is about 5V for SITe CCDs (with VRD=14V) and that increasing RG-low from 0 to 3V, reduced feedthrough to 40% or about 90 mV. I haven't yet measured linearity but noise, cosmetics and full-well are not adversely affected. I am interested in hearing if anyone else has tried increasing RG_low, or if you foresee any problems. Roger Smith, CTIO (rsmith@noao.edu) From roger at ctiol3.ctio.noao.edu Sat Nov 30 14:05:16 1996 From: roger at ctiol3.ctio.noao.edu (roger smith x294) Date: Thu Jul 29 11:54:16 2004 Subject: Fast erase & line skips. Message-ID: <9611301605.AA22473@ctiol3> Tim Hardy wrote to ccd-world........ Has anyone successfully operated a CCD in a parallel flushing mode where the serial gates are all held high while the parallel clocks are runnning instead of periodically flushing out the serial register? The theory is that the charge should all drain out to the output node, but I have been trying it with a Tektronix TK512 and have had no luck - I always get overflow from the serial register into the imaging area. Are there any tricks to it? ________________________________________________________________________ Tim Hardy Dominion Astrophysical Observatory E-mail: hardy@dao.nrc.ca National Research Council Canada Phone: (250) 363-0015 5071 W. Saanich Road FAX: (250) 363-0045 Victoria, B.C. V8X 4M6 ________________________________________________________________________ Tim, This is my standard method for erasing the CCD and for skipping lines between Regions of Interest. I take all the serials and Summing Well high (5V), and Reset Gate high so that the the charge will drain out the Reset Drain, while clocking the parallels. Before using the serial register again, which is to say between line skips/erase and start of region/readout, I clock all the pixels plus overscan out of the serial register, which fills up to the level of the barrier formed by the Last Gate. ie: you need to use negative clocks to lift the charge over the Last Gate onto the output node. With some CCDs I get one bright line at the start of the image or region of interest. I hypothesize that this is due to clock in charge into the serial register faster than it drains out through the serial register. It is no longer being pushed along by the clock potentials but by self-repulsion of the charge. Anyway, whatever the mechanism, I consider it a good trade. You must discard one line at most in exchange for much faster erasing and regions of interest. It does work, so what could be going wrong? I suggest that you check that Last Gate is not too negative. A minimum requirement is that LG be more positive than the low level of the last parallel clock (usually Tranfer Gate), but maybe to "ease the flow" you need it even more positive. (I'm guessing here, since I've never had cause to worry about it.) The other thing to watch out for is that your positive parallel clock levels are not too high. You don't want charge to get stuck in the surface traps when the charge backs up since this can take many line times to be relased and will be deposited in the first lines of your Region of Interest. It is less of a problem for readout which usually occurs well after the erase. Anyway, surface full well is bad because saturated stars bleed this way too. You want the charge to bloom before reaching the surface. Check you parallel clock voltages. This mode runs your clocks faster than you have been doing and the increased current drawn by the CCD plus slope control filter capacitances could be overloading your clock drivers. Please let us know how it goes, even if it was a simple error since it's always useful to know what to avoid doing. Roger Smith, CTIO rsmith@noao.edu ....Use this address only since I'm changing computers. From preben at astro.ku.dk Mon Dec 2 08:39:17 1996 From: preben at astro.ku.dk (Preben Noerregaard) Date: Thu Jul 29 11:54:16 2004 Subject: From Tim Hardy In-Reply-To: <199611291838.AA23450@uwila.cfht.hawaii.edu> Message-ID: Hi Tim This is the flushing mode we are using as standard on our Loral 2k3eb's. All serials, SW, OG and RG are held high during the parallel clocking. It is true that, especially at high flat levels, there may be remaining charge is the image. For this reason we run the parallels typically 10-20% more than the length of the parallel (2200 cycles for a 2kx2k) and complete the procedure with a similar sweep of the serial reg. The potential barrier between the serial and up to the parallel may be too weak on your TK512, so it simply doesn't work on your CCD. 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 -------------------------------------------- From tmca Fri Nov 29 12:28:33 1996 From: tmca (Tim Abbott) Date: Thu Jul 29 11:54:16 2004 Subject: Problems with CCD-world Message-ID: <199611292128.AA25764@uwila.cfht.hawaii.edu> Dear CCD-world subscribers, CCD-world appears to be suffering some problems. We are not sure what is going on, but some subscribers have complained that their submissions are not getting through. At this end, we see no evidence of such submissions, which is confusing us. For the time being, please continue to send emails to CCD-world as usual. If these messages bounce, please send the entire text and header of the bounced email directly to me (tmca@cfht.hawaii.edu) before trying again. I apologise for the inconvenience and normal service will be resumed as soon as possible. Cheers, Tim Abbott From tmca Fri Nov 29 09:38:37 1996 From: tmca (Tim Abbott) Date: Thu Jul 29 11:54:16 2004 Subject: From Tim Hardy Message-ID: <199611291838.AA23450@uwila.cfht.hawaii.edu> Forwarded from Tim Hardy: Has anyone successfully operated a CCD in a parallel flushing mode where the serial gates are all held high while the parallel clocks are runnning instead of periodically flushing out the serial register? The theory is that the charge should all drain out to the output node, but I have been trying it with a Tektronix TK512 and have had no luck - I always get overflow from the serial register into the imaging area. Are there any tricks to it? ________________________________________________________________________ Tim Hardy Dominion Astrophysical Observatory E-mail: hardy@dao.nrc.ca National Research Council Canada Phone: (250) 363-0015 5071 W. Saanich Road FAX: (250) 363-0045 Victoria, B.C. V8X 4M6 ________________________________________________________________________ From tmca Fri Nov 29 09:46:48 1996 From: tmca (Tim Abbott) Date: Thu Jul 29 11:54:16 2004 Subject: Soft x-ray ccd camera Message-ID: <199611291846.AA23543@uwila.cfht.hawaii.edu> Forwarded from Carlo Sozzi (not a CCD-world subscriber): We are looking for a scientific grade CCD camera matching most or all following specifications: -Spectral sensitivity from visible to X-rays (up to 10 keV) (no fiberoptics coupler) -back-illuminated thinned device (eventually with antireflective coating for UV) -readout rate 200 frames/sec or better -selectable integration time -number of pixels: at least 512 x 128 (possibly option of a larger matrix in a reduced readout rate) -object to detect characteristics: 8x20cm at 150 cm -operation in evacuated environment -CCD sensor and amplification stage wired to control unit for remote operation (10 meters away or more) -rugged for operation in environment with relevant electromagnetic noise (30 Khz) and quasi static magnetic field (0.1 T/sec, max 0.1 T), exposed to ionising radiation. Such a beautiful device is intended to be used in monitoring plasma behavior in a tokamak device. If you have any useful information or suggestion please contact me. Thank you for help Best regards, C. Sozzi Carlo Sozzi Istituto di Fisica del Plasma Consiglio Nazionale delle Ricerche Via Bassini, 15 - 20133 Milano, ITALY Tel. + 39-2-2363492 + 39-2-70638646 Fax + 39-2-2663212 From tmca Fri Nov 15 14:27:00 1996 From: tmca (Tim Abbott) Date: Thu Jul 29 11:54:16 2004 Subject: Forwarded message Message-ID: <199611152327.AA22507@uwila.cfht.hawaii.edu> The enclosed email from CCD-world subscriber Tim Puckett raises an interesting point - how do we feel about "advertising" on CCD world? In this particular case, Tim has a (single) CCD to sell and CCD-world seems an obvious market, but he has been very courteous and checked first. Personally, I am quite happy to see such messages on CCD-world, since the aim is to spread as much information as possible around our small but disparate community. Moreover, I know that many of us are very interested keeping up with any and all sources of science grade devices. Consequently, I would even encourage the several vendors who subscribe to announce new products or services via CCD-world. On the other hand, I am quite sensitive to "spam" and junk email and would do my best to discourage it. However, I do not think that I would put the occasional "classified ad" or announcement of a new product into this category. If anyone objects to this policy, please let me know. Cheers, Tim ------ >From tpuckett@mindspring.com Thu Nov 14 16:46:23 1996 Received: from itchy.mindspring.com by uwila.cfht.hawaii.edu with SMTP id AA26893 (5.65c/IDA-1.4.4 for ); Thu, 14 Nov 1996 16:46:21 -1000 Received: from tpuckett.mindspring.com (borg.mindspring.com [204.180.128.14]) by itchy.mindspring.com (8.7.5/8.7.3) with SMTP id VAA25297 for ; Thu, 14 Nov 1996 21:45:58 -0500 (EST) Message-Id: <2.2.32.19961115024554.0073e6b4@mindspring.com> X-Sender: tpuckett@mindspring.com (Unverified) X-Mailer: Windows Eudora Pro Version 2.2 (32) Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Thu, 14 Nov 1996 21:45:54 -0500 To: tmca@cfht.hawaii.edu From: tpuckett Subject: Site Chip Status: RO Dear Dr. Abbott, I wondered if you know of a medium by where I might be able to sell a grade 1 Site chip I have on hand. I have a camera that uses the Site SIA502A with the on board TEC and am satisfied with it's performance. I also purchased a grade one SI-502AB sensor and would like to sell it for a reduced price. At this time I can not accommodate a chip without an on board cooler. The chip is still in it's container and has never been opened, The factory seal is still in place. I am on your CCD world list and would not dare post such a thing. I thought you might know how I could sell the chip I have on hand in a more private manner. If your time allows and you have any suggestions please advise... Best regards Tim Puckett The Puckett Observatory P.O. Box 818 Ellijay, Ga. 30540 USA 706-636-1166 770-459-6491 Web Site http://www.mindspring.com/~tpuckett From tmca Tue Nov 12 10:00:13 1996 From: tmca (Tim Abbott) Date: Thu Jul 29 11:54:16 2004 Subject: Forwarded query Message-ID: <199611121900.AA24388@uwila.cfht.hawaii.edu> Very sad news about Walter Kosonocky. I enjoyed his retrospective at Garching and I feel honoured to have met one of the originators of our field before this tragic loss. If I may echo John Geary's sentiments, Walter's talk was the capstone on a very successful workshop - many thanks to Jim, Paola et al. for organising it all. Also, many thanks to Fred Harris for broadcasting his most extensive notes, these are now available on the CCD-world web page (new URL: http://www.cfht.hawaii.edu/~tmca/CCD-world.html). In the meantime, I pass on the following interesting query about a possible alternative application for CCDs. Perhaps it will provide a diverting idea for some of us. Best regards, Tim Georgios Skillas writes: >From skillas@solid.phys.ethz.ch Wed Oct 30 05:18:13 1996 Message-Id: <199610301514.QAA28484@solid.phys.ethz.ch> X-Sender: skillas@129.132.149.11 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Wed, 30 Oct 1996 16:16:52 +0100 To: ccd-world-request@cfht.hawaii.edu From: skillas@solid.phys.ethz.ch (Georgios Skillas) Subject: Info about the CCD mailing list. Cc: skillas@solid.phys.ethz.ch Dear Sir, although I am not a astronomer or IC technology expert ( I am working on my PhD. on aerosol characterisation ) I would like to obtain some information about CCD technology which will enable me to judge if a CCD-like device would be a solution to the following problem : To get information on the particle mass of charged aerosol par- ticles (typical radii : 2 - 150 nm, typical charge : 1 - 2 electrons ty- pical densities : 1000-2000 kg/m^3 ) are accelerated to near-sonic ( but always subsonic ) velocities and then led against a metal plate with a radius of 1 cm. This metal plate is connected to an electrometer, so one can count how many particles are impa- cted. The noise level is between 3 - 10 fA while the signal is typicaly between 30 - 600 fA. The electrometer time constant is 4 s. As it is this device can only be used to characterise aero- sols with high particle concentrations, and a lot of time is nee- ded for each measurement ( ca. 30 min ) in order to obtain a good statistic I am looking for ways to improve the device. On the plus side, the plate is easy to clean, as it can be cleaned by CH3COCH3 ( acetone ) or CCl4 ( carbon tetra cloride ) and even ultrasound. My question is : Could I use a CCD camera to obtain a better temporal resolution as well as a lower noise level ? I could live with a smaller plate radius, and what I need in principle is a very accurate way of counting charges. It should be possible to clean it by one of the aforementioned methods though. If a CCD does not work as is, could a partially completed CCD chip ( without the photon to electron conversion layer(s) ) be used ? I would be glad if I could post this question to the ccd-list. Yours sincerely, George Skillas -- Timothy M. C. Abbott http://www.cfht.hawaii.edu/~tmca/tmca.html From jsoldan at asu.cas.cz Sat Nov 9 09:26:51 1996 From: jsoldan at asu.cas.cz (SOLDAN Jan) Date: Thu Jul 29 11:54:16 2004 Subject: CCD Camera Message-ID: <9611090726.AA00292@asu.cas.cz> We would like to buy commercialy available CCD camera with chip size about 30-40mm. It could be 1k x 1k or 2k x 2k with appropriate pixel size. It could be thermoelectrically cooled. We would like to use such CCD camera with 1 meter telescope in primary focus. The total price is up to 100.000 USD for whole CCD camera (i.e. hardware & software for PC either DOS or Windows (3.1, 95, NT)). Could anybody help? Best Regards, Jan ------------------------------------------------------------ Jan Soldan, Software Development Engineer Astronomical Institute Ondrejov Observatory 251 65 Ondrejov Czech Republic E-mail: jsoldan@asu.cas.cz Fax : +42-2-881611 Voice : +42-204-857142 ------------------------------------------------------------ From Dirk.Viehmann at space.otn.dasa.de Fri Nov 8 18:17:19 1996 From: Dirk.Viehmann at space.otn.dasa.de (Dirk.Viehmann@space.otn.dasa.de) Date: Thu Jul 29 11:54:16 2004 Subject: CCD Stammtisch MUNICH 13.Nov.96 Message-ID: <32835D0F.55C@space.otn.dasa.de> In Munich we are having a CCD Stammtisch at the Augustiner Braeu in the Kaufinger Str.(near Stachus) every 2nd Wednesday of the month (only the first second wednesday). next:13.Nov.1996 / 11.Dec.1996 Time 7.00 p.m. ask a waitor for CCD Stammtisch Best regards ---------------------------------------------------- Dirk Viehmann / RST15,Dornier Satellitensysteme GmbH PB 81663 D-81663 Muenchen mailto:dirk.viehmann@space.otn.dasa.de Tel: +49-89-607-23755 Fax: +49-89-607-35180 ---------------------------------------------------- From jbeletic at eso.org Fri Nov 8 10:08:50 1996 From: jbeletic at eso.org (James Beletic) Date: Thu Jul 29 11:54:16 2004 Subject: Walter Kosonocky Message-ID: 8 November 1996 Dear colleagues, It is my sad duty to report that Walter Kosonocky passed away last Saturday, 2 November of a heart attack. Many of us have met Walter at the Cayman CCD meetings and we were honored to have Walter give a retrospective talk on CCD technology at the ESO workshop dinner in early October. As those of you who were at Cayman last November or at ESO a few weeks ago will remember, Walter was vibrant and full of energy, which makes this news all the more shocking. I don't think Jim Janesick will mind if I include part of the message that he sent out earlier this week. Jim wrote: Shocking... a tremendous loss to CCD technology. Took Walts UCLA course in CCDs 20 years ago (a real pioneer). And he was actively writing e-mails a few weeks ago. Seemed in good health at Cayman. Sorry to hear this news. In the proceedings of the ESO workshop, we are planning to put in something special about Walter. If you have any contribution to make, or any ideas (whether or not you attended the workshop), please let us know. Best regards, Jim ========================================================================= James W. Beletic E-mail: jbeletic@eso.org European Southern Observatory Phone: +49-89-320-06520 Karl-Sch-Str 2, D-85748 Garching, GER FAX: +49-89-320-2362 ========================================================================= From geary at cfa.harvard.edu Fri Nov 1 15:14:13 1996 From: geary at cfa.harvard.edu (John Geary) Date: Thu Jul 29 11:54:16 2004 Subject: CMOS vs JFET switches Message-ID: <9611011914.AA01254@jupiter.harvard.edu> Here is a question I forgot to bring up at the ESO workshop. Maybe some of you would like to comment. I note that some folks use fast CMOS switches (e.g. 201HS and DG271) for signal processing duties, while others stick to the slower JFET switches for such things as the CDS reset and integrator reset & sample. Any particular reasons to go with the slower JFETs, anyone? Are there noise or charge injection or other issues here that cannot be seen in the data sheets? BTW, for some reason, I thought this last ESO fest was one of the most productive meetings on CCDs in recent memory. Don't know what the cause was, but congrats to all involved, and keep up the good work. --JG From conroy at mso.anu.edu.au Thu Oct 31 10:05:45 1996 From: conroy at mso.anu.edu.au (Peter Conroy) Date: Thu Jul 29 11:54:16 2004 Subject: Newsgroup. Message-ID: <199610302205.JAA01669@merlin> Hi. My name is Peter Conroy. I work with CCD detectors at Mt Stromlo Observatory in Australia. I heard about your newsgroup when I was at ESO in Garching. May we join your newsgroup or have access to your web site. Regards ----------------------------------------- Mr Peter Conroy Mt Stromlo Observatory The Australian National University Private Bag Weston Creek PO ACT 2611 AUSTRALIA Phone (W)61 6 279 8022 Fax 61 6 249 0233 Email conroy@mso.anu.edu.au ----------------------------------------- From fhh at nofs.navy.mil Wed Oct 16 15:39:50 1996 From: fhh at nofs.navy.mil (fhh@nofs.navy.mil) Date: Thu Jul 29 11:54:17 2004 Subject: notes from ESO detector workshop 96 Message-ID: <9610162139.AA21793@ccder.nofs.navy.mil> Disclaimer: many notes here will be repetitive with respect to the published contents of the proceedings; all have been filtered by my personal view points. Apologies for missed and/or misspelled names; comments and corrections to Fred Harris at fhh@nofs.navy.mil ESO DETECTOR CONFERENCE, FIRST DAY: 1. Guy Monet: Introduction to the conference Opening Session: 2. Albert Theuwissen of Philips Imaging Technology: - ref to Janesick's sandbox paper from SPIE - not part of Philips Research, but shares same facilities at Eindhoven - processing capability beyond 0.5um with 6-in wafers, going to 8-in in 1998 - most devices are 4-phase, with two poly-Si layers - n-type substrates, one flat gate oxide - gradients vs depth flatten out by 7um depth - +10v gate potential; +2V barrier-gate potential will still collect light; at 0V gate potential then drains vertically to substrate => collect electrons only in first 2.5um depth, deeper drain to substrate; also implies an electronic-shutter capability - unit fab block for image area is 1Kx1K; can repeat as needed to fab larger array sizes, up to 7K (H) x 9K (V) to fill 6-in wafer; block layout (modular) - full frame or frame transfer - single output up to quad output - image array split vertically, serial regs split horiz - triple poly (2 used in image area, 3 used in horiz reg) plus 1 metal - amps are 3-stage, first 2 stages have on-chip loads, 3re stage load off chip - >200K e- for 12um pixel - <0.5 nA/cm^2 dark current at +60C, non-MPP - QE of 13% at 420 nm; 27% at 530 nm, 7% at 800 nm (losses due to vertical antiblooming) - 6 uV/e-, 30 e- rms at 5 MHz; 110MHz bandwidth; summing gate and floating diffusion capacities >600K e-; random pixel non-uniformity <1.0%; fixed pattern noise <50 e- (at 60C, 20ms integration time) - Lesser's tests: cooled to -150C with no problems; >10 e- at 33Kpxl/sec (results on web page) - typical anticipated wafer delivery time is 2 months - would eliminate vertical antiblooming if thinned for backside operation - noted by Mackay that amp very similar to Kodak amp - estimated cost $150K (for lot run?) - guess that dark current would increase x2-x3 in p-type substrate (IR sensitive without antiblooming) 3. Morley Blouke: SITe 3-side buttable arrays - primarily speaking to 2Kx4K CCD (SI002A) - 15um pixels, frame-transfer image area organization - 2 amps - 25 extended pixels - no transfer gate - serial pixel well x2 that of image area, summing well same as serial pixel - three phase, triple poly (3 level) buried channel - 63.43 mm x 31.464 mm - 37.5 mm chip center-to-center butted spacing - phase 3 is mpp gate in image area - can do frame transfer in MPP only - can do clocked antiblooming alternating phases 1 and 2 - 2 devices per 4-inch wafer - non-, visible- and UV-AR coatings available; peak QE 60% for UV coating; 85% peak for visible coating; QEs drop with increasing cold temperatures - packaging effort to provide means for flattening the die - 32 pads total for pinout including temperature sensor (AD590) - ribbon cable to external connector - edge of die recessed 25 um from edge of package for protection in H-dir - chip carrier is Invar 36 with 4 blind holes on back for mounting - CTE 0.999995 H and 0.999999 V; Fe55 testing done by Elliott at JPL - SITe test system limited to 1Kx2K image storage for testing - 2.9 e-noise at 50Kpxl/sec - <30 pA/cm^2 dark current in MPP - SI008A: 4K H x 2K V, buttable on one edge to make 4Kx4K arrays, for the HST ACS (Advanced Camera System); H reg longer for improved radiation tolerance - Al gnd barrier around periphery and over amp to make amp light-tight - Invar package is tied to package substrate (= GND) - bow of parts has not been measured as a function of temperature - Rich Reed has measured increased bows in 2Kx2K parts versus increasing cold temperature 4. Barry Burke: MIT-Lincoln Labs - U of HI consortium: 2Kx4K buttable imager: - architecture similar to SITe 2Kx4K - output amp <2 e- rms for same-style amp as AXAF - back illuminated - flat to <15 um (+/- 5 um) - enhanced near-IR QE with 7000 ohm-cm bulk wafers - Aluminum Nitride package substrate of 3 layered pieces - 2 JFET source followers off-chip on-package to improve drive capability - full well >125K e- (not yet optimized) - 10-15 uV/e- output - packaging of devices to start Nov 96 - blooming control experimental chips: - 512x512 frame-transfer CCDs, 15 um pixels - blooming drains hidden in center of channel stops: - take away conventional LOCOS channel stops - place n+ blooming drain surrounded by p+ barrier underneath with n- blooming barrier on each side - blooming can be electrically turned off - optical overloads tested at x1000 and x1000000 - QE tests still im progress - this structure is wider than standard channel stop, full well should be diminished - Tonry's chips: - should be 4 poly levels; 1 is Al to allow no changes on rest of wafer - structure with 1 metal layer has excess of pockets - 4-inch wafer capability to date - 1960x2560 CCD frame-transfer CCD fills wafer: - package is Molybdenum with die attached; pc board attached to metal plate; bond wires direct from Si to pc board (10-layer) - 5 back-illuminated devices delivered to Air Force (GEODSS program) - no bright columns, just a few pockets - AR-coating is UV opaque - going to 6-inch wafers, fab line conversion this month (Oct 96); driven by lack of good 4-inch wafers - may not make chips commercially available; do take on research programs instead (no fixed-price contracts for deliverables, best-effort only): - possible to perform technology transfers to other manufacturers 5. Peter Pool of EEV: - CCD42-80 is 13.5 um pixels 2Kx4K - 210 um butting loss on sides, 100 um on top - 3 devices max per wafer - could do 2 of 2Kx5K plus 1 of 2Kx7K on wafer max - CCD44-82 is 15.0 um pixels 2Kx4K - 500 um butting loss on sides, 150 um on top - 2 devices max per wafer - backsides are implanted, with laser anneals - in-lab QEs can peak over 90% - high-resistivity substrates show red enhanced QE, peak 88% at 800 nm at room temp - output amps are two-stage, internal load on first stage, external load on second stage: - 400 ohms output impedance - electrically equiv to single stage - DC restoration available on-chip via extra drive-input connection - 3 e- at 100Kpsl/sec; 6 e- at 1Mpxl/sec - with 10pf load capacitance, 35ns settling time - should operate well at 1 Mpxl/sec - two output gates: - stagger 1st to second output gate by 1 volt, good low-noise performance - bias second output gate to 10V, triples output node capacitance so larger dynamic range at output amp is realized - CCD bonded directly to Invar; Invar bonded only near center to Al substrate to avoid thermal mismatch and maintain planarity over temperature - CCD before packaging has 4 um peak-to-valley flatness; maintained after packaging at room temp - at -100 C, actually gets flatter if starting shape is domed - peak deflection at -75C where Si and Invar characteristics cross over - picking the CCD doming vs Invar thickness can flatten combined system over wide temperature ranges - future: package concept the pin grid UNDER part of Invar to minimize hit in image plane for 4-side butting; places for off-chip JFETs for buffering; either 13.5 um or 15 um CCDs will be so available - 128x128 frame-store chip for AO with 1K frames/sec (for Beletic) - 15 um 2Kx4K chips available end of 97 6. Dick Bredthauer of Lockheed Martin (/Loral/Ford): - 5-in line now - 6-inch line in Shanghai China to come on line next year - 4Kx4K 15 um CCD for Dicomed / Hasselblad Camera ("BigShot") - almost 1K fabbed so far - Milpitas also fabs the whole back end to bolt directly to back of camera - outputs are NOT designed for low-noise applications - flat to about 25 um - "those who pay the most complain the least"... - Helin using on GEODSS scope at -5C with 10 e- noise @ 50Kpxl/sec - Table Mountain running colder - for astronomy, need to remove wire bonds and protective epoxy and rebond; this process not yet firmed - 4Kx4K 19.5 um CCD on 5-inch wafer (79.9 mm x 79.9 mm) - thousands of CCDs already fabbed for dental X-ray work - China and India SPOT satellites use Loral CCDs - Mars Global Surveyor mission uses backup CCDs from Mars Observer - 1.5 um design rules, 3-phase 3-level poly process - $2500 - $3500 for grade 1 2Kx2K CCDs - 9216x9216 8.75 um CCD: - 50 Ke- charge capacity - 4 of 20 MHz outputs - 80.6x80.6 mm - Navy recon instrument (on F18?) (NRL program to demonstrate system) - 3 or 4 working arrays from R&D program; lot to be fabbed later this year for Navy program; first devices not cosmetically good enough for astronomy 7. Richard Stover of Lick: - thick CCD back illuminated: Lawrence Berkeley Lab: - high-resistivity Si - 300 um thick, completely depleted Si wafer - good QE response at 350 nm; about 85% QE out to the near-IR - spreading of e- in substrate, must apply backside bias (best for 18-24 V) to minimize spreading - very thin ITO on backside for bias application - can't use in fast beam due to thickness of CCD; f10 is probably slow enough - 200x200 pxl size for these first test devices 8. Christoph von Zanthier of MPI: Fully depleted CCDs for X-ray, UV and IR detection: - for XMM-Satellite mission - if have pn junctions on both sides of the wafer, and apply voltages to gates on both sides to fully deplete the thickness of the wafer - clock lines on the front side are pn junctions - epi layer 40 ohm-cm, 12 um deep - n Si 2.5K ohms-cm, 270 um thick - 2x6 array of CCDs on a 4-inch wafer - pixel size 150x150 um; image area size 10 mm x 30 mm => longest dimension is 200 pixels - QE better than 65% from 200 to 800 nm; wavelengths outside this range now under test - each column has on-chip amplifying JFET (? 5 e- noise ?) - present technology could go down to 50 um pixels - full not measured because amplifier saturates first; >500K e- known, about 1M e- estimated 9. Paddy Oates of RGO: EEV CCD42 test and evaluation - camera rear defines CCD in dewar - serial reg has U-turn at end to minimize butting-area losses - expect <2 e- noise at 50KHz and 5 e- at 1MHz sampling, BUT noise spectrum is flatter than expected => lower noise at the higher frequencies (read rates); determined with photon transfer - output gate 2 run either at +3V or +13V, producing about x3 gain change - 128K e- < full well < 190K e- - Vcte 0.999997; Hcte very good - clocking Verts 35 usec/line without noticeable spurious charge - 3000 sec exposure, cosmic rays very point-like - RGO QE measures: in good agreement with EEV now; QE uniformity within 10% at 350 nm - flatness: one corner is low, middle flat to <10 um, periphery <15 um; measured with technique similar to Hartmann testing - Dump drain along serial reg: V shift each row, activate dump drain, read out serial reg twice => 0.4 sec to clear chip - if V binned x50 and H reg read out plus read serial reg twice at end => 2.0 sec and results comparable to using dump drain 10. Gerry Luppino's open session: - Jim Beletic: wants high QE in UV - question for Morley Blouke: can SITe UV and visible QEs be both realized: answer is maybe? - H2 poisoning of Lesser-thinned surface by ion pump dropped QE from 90+% to 4% (Geary) - note that Loral devices seem not to perform at better than 7 e- noise; basically confirmed by Bredthauer - comments by users of Lesser CCDs: they can hold up in an observing environment, although their QEs change as a function of handling procedures - comments on Loral CCDs: blurring of PSF: thickness of epi changed from 15 um to 20 um for Lesser's convenience, 20 um epi kept since and this increased thickness results in the PSF spreading; Rich Reed reports one 800x1200 at KPNO was overly thinned to maybe 13 um thickness, reduced PSF spreading from 2.6 pixels to 2.1 pixels - one Si supplier has a stiffened lattice because the molten Si is in a quartz beaker which dissolves some of the beaker, loading the Si with oxygen to concentrations of 10^17 per cubic cm; on this epi is grown - comment that wafers thinner than 150 um won't withstand processing - Loral once made p-channel CCDs for radiation hardness, but lost out on CTE - fringing issue: for some spectrographs fringing is THE limiting problem; can this be addressed by the vendors? Is the CCD a 10 micron-thick etalon with an index of 4 or 5 or 6? Spectroscopists want it all (except perhaps readout speed) i.e. a very small part of the astronomy market which is already small compared to the (paying) commercial market... 11. Kirk Gilmore of Lick: Noise tests: - Loral: about 10 nV/root Hz at 100 KHz - Orbit: still in progress? - Lincoln Labs: about 15 nV/root Hz at 100 KHz; knee at about 1MHz - Lawrence Berkeley Labs: about 10 nV/root Hz at 100 KHz 12. Roger Smith of CTIO: How linear are CCDs? - his DC-coupled preamp has clamp diodes which changed from forward to reversed bias when VOS offset was improperly subtracted; some turn-down of linearity is still found with the diodes removed - Burr-Brown OPT211 integrated photodiode& as LED intensity reference to guarantee constant flux rather than sending through a constant current - Mackay says using switching FETs work best because they have a lower impedance; two resistors are still needed to bias the FET?; only a single resistor from source to gnd with gate to gnd seems to be enough - Chris Stubbs wrote up a paper while at LBL on making such active loads 13. Richard Stover: CCD flatness measuring system - fixed laser - video camera on pen-plotter x-y stage - CCD on milling-machine x-y stage - laser up to mirror, down to CCD, up to larger mirror, down to video camera - changing tilt on CCD translates the laser spot on video camera 14. ?: - grounding SITe amp gnds at the chip gives lower noise than if that gnd is returned to the preamp 15: general discussion: - more observers should have means (and intent) to monitor CCD/camera performance characteristics - more instruments should have diagnostic stimuli built in - cryogenic warmup alarms to prevent the warmup and outgassing of the getter followed by the detector cryopumping the outgassed species (i.e., operator error in cold vacuum maintenance) - urge for trend of adding telemetry of in-camera CCD excitations to new camera designs - detector systems with critical alignments cannot be easily removed from the telescope environment, so desire testing capabilities internal to the instrument ESO DETECTOR CONFERENCE, SECOND DAY: 1. Satoshi Miyazaki of National Obs of Japan: - Large format and high QW CCDs for Subaru Telescope - need 14 of 2Kx4K devices for instruments - prime focus camera expects f1.9 beam - needs less than +/-30 um flatness for 15 um pixels - EEV 2Kx4K anticipated - measured EEV flatness +/-2 um - readout 10 usec/pxl, really need 1 Mpxl/sec rate - high resolution spectrograph has f3.5 camera - in-vacuum clock driver and preamp board per CCD - single board from CCD via FPC, and FPC out to 41-pin hermetic conn in dewar wall - board folds in half to make preamp compact with clock drivers - preamp heat removed via copper gnd plane - bias generators and signal-chain+ADCs outside of vacuum - tests of Hamamatsu CCDs, backside - 2Kx4K 15 um pxl intended, frontside - peak QEs near 90% measured 2. Johannes Andersen of U of Copenhagen: - CCD detector program for NOT and 1.5-m Danish on La Silla - circa 1991: Loral wafer run, thinning by Lesser; camera to be built in-house - 7 e- read noise for Loral, 4 e- for SITe - runs on PC with Linux - fiber optic connection between instrument and data system - coming soon: 2Kx2K CCDs, single chips for most instruments, 2x2 mosaic at cass - Preben Noerregaard is contact for controller hardware development - circa 1994: Loral run with 88 chips, 66 alive; 2nd run had >40 alive - SITe chip is still working great 3. Jim Beletic of ESO: ESO's plans for optical detectors - VLT and support for telescopes on La Silla - optical imagers, and wavefront sensors for AO - one Lesser CCD operating for 1.5 years with no problems - 3.6 e- noise at 1 Mpxl/sec from Lincoln Labs CCD; this speed needed for direct cameras - faint spectrographs can run at 100Kpxl/sec - Toshiba paper describes <1 e- noise at 1 Mpxl/sec, hopes this can be realized - FIERA CCD controller: in development/test - will get 2 of 7Kx9K Philips CCDs; 2Kx2K 24 um with 4 tracker CCDs on sides; UH/MITLL chips, want 3; EEV 2Kx4K 15 um want 10, also EEV wavefront CCD 128x128 24-um; need CCDs for 8Kx8K mosaic - note that no mfr can test CCDs at high speed, will loan FIERO controller for speed tests - ACE controller going to NTT next month 4. Russel Cannon of AAO: AAO detectors, present and future - Tek 1Kx1K used almost exclusively - f3.3 prime focus needs more area coverage - 90% of scope time used for spectroscopy - Schmidt FLAIR system is fiber coupled - want to do: - 8Kx8K for prime, 2Kx4K elsewhere; UH/MITLL and EEV usage expected - circa 1983 controller: 2.3 e- noise at scope, 1.7 e- in lab; does charge-shuffle readout (CSR): - CSR: image in middle 1/3 of CCD, mask each end for storage areas - Leach controllers as interim solution, in-house next generation continues - first prototype on new sys 1 yr, in use 2 years 5. Gerry Luppino of IfA: U of HI plans for CCDs - existing 2Kx2K TEK camera, Loral/Lesser 2Kx1K camera, mosaic 8Kx8K of Loral thick CCDs, travels around - UH/MITLL thinned to replace thick CCDs in 8Kx8K camera - will build 8Kx12K camera for CFHT (2x6 array) - 3.6-m AF scope on Haleakala to get high-res spectrograph needing 8Kx8K cam 6. Rick Murowinski of DAO (for Todd Boroson): Gemini CCDs - wants high-speed mode and slow-speed mode, hopes calib shots in high speed can be matched to data taken in low speed - GMOS wants: <3 e-/hr dark current, flat <25 um over WHOLE focal plane, temperature stability <0.18C/hr to maintain velocity resolution - vendors for 2Kx4K buttable parts to be contacted - controllers: Int'l bid for integrated controllers - Shack-Hartmann sensors are EEV39, 3-5 e- noise, 200 frames/sec, CCD integrated with CCD package 7. Richard Stover of Lick Obs: development of CCDs for Keck - DEIMOS will use 8Kx8K of 2Kx4K 15 um CCDs for Keck II - ESI spectrograph with one of 2Kx4K um CCD (echelle) - 4Kx4K upgrade of HIRES via 2 of 2Kx4K 15 um - will use SDSU-II controller - for Lick, need 2Kx2K CCDs (1 of SITe and rest of 15 um pxls) - hoping for SITe CCDs flatter; don't think EEV will be ready for Keck timeline 8. Paul Jorden of RGO: RGO and INT CCD developments - at present mostly using Tek 1K and 2K CCDs - working on Loral/Lesser 2Kx2K 3-side buttable, EEV 2Kx4K CCD42 - INT to get 4Kx4K camera: - Loral non-buttable CCDs as close as possible plus autoguider CCD - no circuitry in vacuum - one controller for science CCDs, separate controller for autoguider - rotating sector shutter, 6-position filter wheel coaxial 9. Rich Reed of NOAO: CCD plans - 20 of 2Kx4K CCDs ordered from SITe (? thinned grade 2 ?) 10. Craig Mackay of U of Cambridge: High speed wide dynamic range controllers - no trimpots on boards, DACs instead - for interferometer, 10Hz response in telescope autoguiding CCD controller; readout rate up to 150 frames/sec of guiding subarray (interferometer detectors are APDs) - 64x64 15 um pixel frame-transfer CCD by Loral, 8M pxl/sec (12-bit) (100 e-), 5M pxl/sec (14-bit), up to 865 frames/sec - using this controller for 2x2 mosaic of HgCdTe 1Kx1K IR arrays 11. Claudio Cumani of ESO: ACE and FIERO - ACE is transputer based; libraries used for hardware dependent features, rest of code (80%) in common - 100K pxl/sec per port - FIERA: - analog bias board, video board, clock driver board, common board per CCD detector head - 880 Kpxl/sec/port, 1.3 e- noise at 1 Mpxl/sec, "negligible" crosstalk - circa 1997: 2 Mpxl/sec/port limited by 16-bit ADC (could change to 10 Mpxl/sec with 12-bit ADC board), 16 Mpxl/sec total 12. John Geary of SAO: preamp designs - likes to put preamp in vacuum near CCD => should be small and clean - JPL/Jamesick preamp deemed complex, V noise less than AD745 - AD745: low V noise, low I noise (less important), slew rate & settling time modest; 2 in parallel slightly lower V noise than JPL - OPA627 (or OPA637): V noise x2 of AD745, faster slew rate - Fred Harris' tests: AD745 too slow at 100 Kpxl/sec; OPA637 slews fast enough to pass too much feedthru - Philip MacQueen's use of OPA637: works well with gain foldback to knock down reset feedthru, must heatsink parts - 5-volt-rail opamps will probably have dynamic range problems 13. Philip MacQueen of McDonald Obs: 18-bit analog signal processing - full well < full ADC scale - read noise > 3 ADUs - analog signal processor linearity >> CCD linearity - Analogic 18-bit ADC - integrator is major weakness in system: - multiple integrator reset pulses for best linearity (even if total reset on-time is comparable?) - ? charge stored in reset switch, leaking back into integrator capacitor ? - jitter noise in integrator switch windows major noise contributor - make zero signal level to be 0 volts, then gain changes from jitter have minimal effect on small-level signals - speed changes via multiple selectable integrators 14. Roger Smith of CTIO: readout speed optimization - doesn't yet run I+ directly after I-; waits for video to settle between I- time and I+ time - OPA627 saturation recovery takes 10-15 usec - analog switch to switch preamp gain to unity seems not to add noise 15. Maki Sekiguchi of NAOJ: Messia CCD controller - no CPUs => no code maintenance; waveforms stored in SRAM, loaded with DSP (DSP is Motorola 16-bit fixed-point) - fast data transfer to host workstation: fiber-channel hardware between front end and workstation 16. CCD controller round table: - Rolf Gerdes: FIERA has 2 of 320C40 DSPs for camera head control; no software in the camera head, just in VME crate, to insure synchronization in multiple detector systems; in detector head small PLDs provide local sequencing (Lattice 1040C-70 ?) - Gerry Luppino representing Bob Leach from SDSU: - timing board is 56002 - clock driver board has 24 clock output via analog switches with DAC-set rails; no slope/slewrate control - Dual ADC board: 500 Kpxls/sec at 16-bits; dc-coupled preamp; 12-bit bias DACs - uses separate timing generation board - uses utility board - ESO is using DAC per clock-driver output with ability to write to multiple DACs simultaneously so waveform synthesis is possible, viewed as desirable for edge control for tri-level clocks for clocked antiblooming; 80MHz DACs from Analog Devices - Craig Mackay's clocks: 16 MHz in serials, perhaps a Teledyne part? - Chris Stubbs: U of Washington CCD MACHO controller: - OPA627 with LM6321 in feedback loop for the preamp output to drive cables some distance from the dewar heads - read out everything in lock-step - opto-isolate everything - only use single amp per CCD - NOT one-size-fits-all controller - FORTH-interpreting micro as front end to DSP which generates timing - trimpots generate voltage levels - transversal filter DCS at 250 Kpxl/sec - the 2 output drains tied together with single-wire in => big mistake with the Loral 2-side-buttable 2Kx2K thick CCDs - Craig Mackay: SITe devices with 4 outputs being used: drive the reset drains independently; output drains and reset gate drives entirely separate - Richard Stover: reset connections seem to matter most in inter-amp crosstalk - Mingzhi Wei: using an optical pattern to stimulate a multi-amp CCD makes it easier to look for crosstalk problems - Jim Beletic asks: can the community build electronics lacking crosstalk? - Gerry Luppino says yes, already done in 8Kx8K camera; controllers must be entirely synchronous - Craig Mackay: must meet EM compatibility reqs as a mfr; asynchronous controllers are deadly - Luppino asks: why don't people use transversal-filter signal chain? Maybe because the totally-reflective implementation has not been published? - Beletic asks: why not take multiple fast ADC conversions to digitally synthesize the dual-slope integrator digitally? - noise goes down at root-N conversions, but: - do you lose that by the greater noise bandwidth needed by the faster electronics to run the multiple conversions? - advantage might be increasing the summed dynamic range beyond that of the single ADC conversion (i.e., slowing down a dual-slope integrator increases the gain which reduces dynamic range; summing multiple ADC conversions can increase the resultant dynamic range beyond that of the ADC digitization limit) - could use the multiple samples to calculate the asymptotic result of where the system SHOULD reach given enough time - Craig Mackay uses dual-slope integration at 5.5 MHz: use RF components and RF circuit techniques; keep amplifier gains to x2-x3 only; use discrete FETs meant to be switches instead of integrated analog switches (? ref to SD5000 by Geary ?); separate +1 and -1 feeder amps, use the FETs to GND the output of the path not being used => organize the circuit topology so that all switches tie a node to GND so that the drive to the switch is TTL-like; may want to have a switch from integrator input node directly to GND; - Philip says: SD214DE FET switch for integrator input, but HI-201HS for conventional integrator reset; a single switch to the integrator input node, and a second switch on the input side of the integrator input switch which clamps the input source signal to GND - Roger Smith uses a pulsed summing well drive, 2 usec long at present, to minimize the offset from a single summing well transition into the integrator path 17. Claude Trottier of EG&G Canada Ltd: Silicon Avalanche Photodiodes - active quench circuit, separate from reset circuit - quench ckt drops the voltage on the APD below the breakdown threshold when an output pulse is detected, waits briefly, then re-establishes the normal breakdown voltage with a rising exponential waveshape - reset is when you recharge the APD - correction factor applied to transfer curve (of input rate versus output when output turns over because input comes faster than APD can recharge to breakdown potential) which is a rising curve, curve rises slower for smaller area devices - electrons get trapped in the avalanche process, must be allowed to relax before recharging the APD or would cause a prompt (next) avalanche - when an APD fires it emits light, must be properly shielded in 4-quadrant APDs; another solution is when one APD quadrant fires, reset all quadrants - quadrant module not convenient for assembly for mass production; crosstalk between cells still needs to be studied - threshold, voltages, cooler, etc all preset for the user 18. Anthony Peacock of ESTED: Superconductivity Tunnel Junction (STJ) detectors - program started in 1986 to evaluate these for X-ray spectrometry - temp below critical temperature (operating temp 1.2 K) - electrons in Cooper pairs; Cooper pair is broken by a phonon from photon - when a Cooper pair is broken, generate 2 charge carriers (quasiparticles) - two thin films 100 nm thick, separated by an insulator 1-2 um thick - time from photon absorption to carrier production is a few nsec - critical temp is 9.25 K for a Niobium device - mechanical coolers operating at 1.4-1.5 K are available - charge carriers are blocked from entering the leads by having niobium nitride at the leads - apply a magnetic field parallel to the barrier of the device - started working with niobium due to higher critical temp and mature technology; evolving to Hafnium via Tantalum - by choice of materials can effect the temporal characteristics of the device - each device has to have its own preamp, etc. - in addition to Fano noise, have noise factor due to internal tunneling - for niobium at 500 nm, resolve 14 nm spectrally - devices 20 um on a side are realized now - photo-absorption in the poly-crystalline niobium layer - electronics are room-temp charge amplifier + shaping stage - charge output per photon: = ? 1.74 x 10^4 e- per blue photon ? - output linear with photon energy to better than a percent - at 200 nm incident wavelength, see 60 nm spectral resolution; resolution drops with increasing wavelength; with backside illumination, get 15 nm resolution at 200 nm - newer device has an epitaxial tantalum structure, but leads are still niobium, top is poly-aluminum followed by poly-tantalum; run at T = 0.3 K; at 200 nm, resolution 9 nm direct, 8 nm with noise correction; small nonlinearity better than 0.6%; reflectivity around 20% at 500 nm, going up to 80% at 1000 nm; IR response: ? - to go into UV, change substrate from sapphire to magnesium fluoride - 3x3 array of 25 um devices have been fabbed and tested, with 1.5 um gaps; test array of 4x4 coming out of fab; masks made up for 6x6 array; - first large format device will be 18x50 of 25 um elements - 3x3 devices have not experienced crosstalk problems - count rates of 10KHz limit, may be limited by electronics - going to the William Herschel telescope with 6x6 array at end of 1997 ESO DETECTOR CONFERENCE, THIRD DAY: 1. Tim Hardy of DAO: Charge transfer efficiency in proton damaged CCDs - radiation damage via displacement: collisions with Si atoms in lattice - affects bulk Si and buried channel - most important is phosphorus-vacancy complex at 0.4 eV - damage increases dark current, decreases CTE - equations of model tested with TK512 damaged by 3 MeV protons, pure beam claimed, fit to equations good - traps at 0.42 eV (phosphorus complex) and 0.223 eV (oxygen complex) 2. Alain Maury of OCA: converting a Schmidt scope to CCD operation - more than 1/3 of discovered asteroids have been discovered with Spacewatch - some films can be 3-4% QE, up to 8%; no commercial market for these products - camera should be no larger than prior plate holder - readout time SHOULD be short, even if noise is increased - photon noise limited, so lowest readout noise not critical - cosmetic quality not as important as some other astronomical applications - current CCD controller at 500 Kpxl/sec, 15-bit data, PC-based acquisition, data reduction on Unix machine; current CCD is Loral 2Kx2K 15 um pxl thick; TEC cooled with glycol loop to remove excess heat - limiting mag of 20th in 2-minute exposure - next generation is Loral 4K CCD, 2.5 Mpxl/sec, 12-bits, controller from DLR 3. John Tonry of IfA: Orthogonal transfer CCD - a number of science-grade devices already made - pocket pumping does happen as charge is shifted around, may be a fundamental concern - 512x512 orthogonal field next to standard 512x512 3-phase field next to amp - pumped pockets often dig down right to the bias level - pocket pumping in lab shows whole spectrum - pockets are very sensitive to clock voltages - kT about 50 e-; pockets shallower empty fast, deeper they do not drain - 3-phase region shows fewer deep pockets, may be function of Al (fourth) gate - most of power spectrum in atmosphere found to be at 1-sec timescale rather than 10-sec or 0.1-sec timescale; slower than Kolmogorov - incredibly low degradation of PSF far from the guide star, suspects that a 10 arc-min could be corrected (iso-kinetic patch) - good cheap way to implement tip-tilt, with NO vibrations - for (KPNO) 2.4-m aperture, see 0.2 arc-sec improvement (0.7 -> 0.5); pixel there is 1/6th arc-sec 4. Walter Kosonocky of New Jersey Inst of Tech: very high frame rate burst- imager sensor - captures frames at rates up to 10^6/sec by storing up to 30 images in frame store section - 2x2 cm chip, 4x180x180 pixels, 50 um pixels, fill factor 13.5%, 30 memory stages per pixel, 3-phase BCCD, 4-level poly, 2-level Al - each pixel contains detector, serial reg, parallel reg; single readout/quad - 1st level poly forms channel stop for serial regs; 3 levels for 3-phase CCD - blooming barrier gate per detector area into dump/overflow drain - detector is pinned buried photodiode; N regions are graded (stepped implant potentials) to move charge toward readout structure - each pixel has at least 10 contacts to aluminum busses - for readout, pixel memory regs are configured into a large (standard) parallel-serial CCD - image-area serial clocks separate from readout reg serial clocks - TEC cooled to -30 C, 8 seconds to readout full image - saturation signal 11 Ke-/pxl, readout noise 9 e- rms (dual slope CDS at 120 Kpxl/sec), dark current 100-200 e-/pxl for 8 seconds of readout time; 2.3 uV/e- - used for studies of cavitation of propellers (such as for ships and subs) 5. Gerry Luppino of IfA: science with large CCD mosaics - present: 8Kx8K, cost of $300K for initial effort (1 lot plus 1 backup lot), thick Loral 2Kx4K 15 um CCDs - future 8Kx12K (2x6 array), thinned CCDs - pincushion distortion at CFHT prime focus => no scan-mode operation - 3 saddlebag system; 2 boxes of Leach I, each box read sequentially (don't know how to synchronize more than one such box); readout time 7 minutes => twilight flats impractical - flat fielding via superflats, precision 0.1%; minimum 60 exposures to generate the flats and biases; everyone's frames go into creating the superflats - running at -70C to avoid serial CTE problems at colder temperatures, so dark current is non-negligible 6. Simon Tulloch of RGO: technique for determining coplanarity in mosaic CCDs - going into f3.3 beam - CCDs scanned cold within cryostat - commercial scanners confused by reflections from surfaces of cryostat window - Hartmann-like test with beam angles of 28.5 degrees - centroids measured to about 1/50th of a pixel - the CCD being scanned is the detector for the test; requires cosmetically good CCDs - taking two exposures, one with one aperture and the other with the second (opposing) aperture, play Hartmann connect-the-dots and simple geometric optics to determine the depth (flatness) dimension; these are 1-dimensional scans - flatness of individual CCDs and flatness inter-CCD in mosaics determined - green LED for illumination 7. Florian Bauer of CEA Saclay: the two EROS 4Kx8K CCD mosaic cameras - detection of massive compact objects, 10^-4 to a few solar masses - 1 m RC scope; 450-650 nm blue passband, 650 nm onwards red - Loral 2Kx2K 15 um 3-side-buttable CCDs - coplanarity 10 um, alignment to 2 pixels - variable thermal resistance between cold mass and detector head, varied with stepper motor, 900 copper contact points; one day to cool (15 Kg) thermal mass, 1 hour to cool CCDs - CCDs have individual driver boards - 12 usec/pxl (ADC limited), 50 secs to read both mosaics, one amp/CCD, 6-7 e- readout noise - typical exposure 3-4 min (galactic bulge), will go to 80 fields/night 8. Rich Reed of NOAO: 8Kx8K mosaic at NOAO - small gaps <1 mm between CCDs acceptable - yield of 9 CCDs out 80 from wafer fab - dewar base has dry N2 gas to keep dewar window dry - radiative coupling of dewar cold source to CCD Invar mounting plate via nested concentric rings - bimetallic strips (12 around periphery) connect dewar to CCD mounting plate, when the strips go cold enough the strips deflect and disconnect - pneumatic-driven shutter (air cylinders) adds no heat load, 2 blades with bidirectional cylinder on each blade, can get photometric operation with either direction of shutter-blade throw - filter motion via air cylinder "one-step stepper motor", one stroke advances filters by one position, bidirectional 9. Roger Smith of CTIO: experiences with Arcon - multiple CCD controllers rather than a single large controller - 3 transputers per controller - the 4 controllers can be individually or individually addressed - each controller can process 4 analog channels - common microprocessor clock is distributed - CCDs float with respect to their dewars and are referenced to their particular Arcon; grounds return to each Arcon; Arcons each have a star ground point on the backplane, this is connected to the shield; Arcon shields are connected by the dewar; - clock distributed by coax between Arcons; 40 nsec change in delay between one Arcon to the next; changes in delay may produce small changes in overscan level - test alignment of CCD pixel descrambling done with on-window copied transparency with LED illumination 1 meter away - data on disk goes on as an IRAF file per amplifier - only one amp per CCD used; electronics can support 2 amps/CCD 10. John Geary of SAO: MMT MEGACAM project - 16Kx16K pixels - 32 of 2Kx4K 15 um or 13.5 um CCDs; half are butted on 4 sides; purchase of CCDs not yet made; controllers not made yet; timetable of 3 years - optical distortions will not allow TDI over the whole array - Spectrograph: 300 fibers positioned via two identical robots, 150 seconds to completely reposition (hoped); CCDs at focus of Schmidt camera with cooling brought in from exterior tot he beam 11. Maki Sekiguchi of NAOJ: Survey camera for Sloan Digital Sky Survey - 54 CCDs in focal plane; 30 of SITe 2Kx2K, 24 of SITe 2Kx400 - TDI mode, all CCDs have image areas clocked in unison - all CCDs require individual rotational and tilt alignment - preamp ICs are OPA627, not AD745 as stated in talk 12. Olivier Boulade of CEA Saclay: MEGACAM project - want readout time <20 seconds for entire array, read noise < 5 e- - want spectral response down to 350 nm - driver board to drive 8 CCDs; readout board to read 8 CCDs - budget for CCDs $2M for grade 1 devices (don't need grade 0); 40 of 2Kx4K CCDs to be purchased - total budget $3.5M - first light in 2000-2001? 13. Discussion session: - organization of multi-chip data is not handled via a single organizational approach across the different conference participants - appears that there is no standard for a compressed FITS format; proposed format from 2 years ago perhaps but not confirmed - MACHO project stores each CCD image as a separate FITS file; will have 500GB of disk in the dome - U of HI 8Kx8K, never look at full image at the telescope; suggest that you have enough disk space for any one night of observing - experience to date that CCDs should be removable from a focal plane - expensive accurate alignment of CCDs within a mosaic required ONLY for cameras running TDI modes - discussion about fringing: - broad band (>100 nm bandpass): not too bad - narrow band: not uniform across field, gets you on faint extensions to galaxies, planetary nebulas, HII regions; hard on spectra - to fix, go to flat fielding: again, direct imaging not too bad; for spectroscopy, okay if fixed instrument format (i.e. no grating-angle changes) - question: do we ALWAYS want coated and/or thinned CCDs? (some groups are gong back to frontside devices?) - note that no fringing was found in the LBL thick back-illuminated high-resistivity CCD; but Fe55 testing difficult - can manufacturers and users of CCDs agree on a simple set of tests for characterizing devices? - DACs: bias voltages and clock voltages usually generated separated in different DACs; DACs can show 1/f noise so expect to heavily filter the DAC outputs; restrict rails, particularly for amplifier biases; provide reverse- protection diodes for amplifier volts with breakdown lower than the CCD; possibly gate the DAC outputs with analog switch per output and have the software verify legal voltages before connecting the DACs to the CCD - setting of parallel clocks and full-well questions: some SITe CCDs seem to have a different full well in one direction than the other, is this effect sensitive/insensitive to clock overlap times? From gpe at saao.ac.za Mon Sep 23 15:19:59 1996 From: gpe at saao.ac.za (Geoff Evans) Date: Thu Jul 29 11:54:17 2004 Subject: neck tube temperature sensor In-Reply-To: <9609222102.AA16785@ctiol3> Message-ID: On Sun, 22 Sep 1996, roger smith x294 wrote: > The epoxy was thermally conductive, electrically insulative and vacuum > safe. > > Sorry - I am in Tucson at present and don't have the epoxy > at hand to check what it is. It's blue!! We were informed of this thermal-conductive-electrical-insulating epoxy by Alistair Walker and Bill Ditsler. It is TRA-BOND 2151 and is obtainable from :- TRA-CON INC. 55 North Street Medford Massachusetts 02155 Phone No. (617) 391-5550 FAX Number (617) 391-7380 We use a similar temperature sensing system with 1N4148 diodes calibrated the same way. We glue the diodes into copper blocks using TRA-BOND 2151 These blocks are then screwed to the surfaces whose temperature we want to measure. Willie Koorts( wpk@saao.ac.za ) Geoff Evans ( gpe@saao.ac.za ) South African Astronomical Observatory P.O. Box 9 , Observatory , 7935 , South Africa From roger at ctiol3.ctio.noao.edu Sun Sep 22 17:02:08 1996 From: roger at ctiol3.ctio.noao.edu (roger smith x294) Date: Thu Jul 29 11:54:17 2004 Subject: neck tube temperature sensor Message-ID: <9609222102.AA16785@ctiol3> Roland Reiss asked.... >Which type of sensor do you use and how exactly do you glue it > to the tube? It;s nothing fancy. I use a simple 1N914 forward biased at 10 uA. We calibrated a bunch of them from a single batch at the boiling point of Nitrogen and at the melting point of water and found that they varied by only about a degree or two from the mean. The variation is primarily "gain" rather than "offset" giving greater errors at room temperature. We verified a few to be quite linear, and don't bother checking that any more. These are cheap and simple. The cost is in the calibration but we did a whole lot all at once to be more efficient. If you try this be sure to put the sensor in a plastic bag to keep it dry when "immersing" it in water since the conductivity of tap water is not negligible. The epoxy was thermally conductive, electrically insulative and vacuum safe. A tiny drop is applied to the neck tube on the vacuum side just above the N2 flask and just below the point it exits the dewar so that it is about 3cm from the warm end. A twisted pair runs down to the detector mount where we have made a simple keyed socket from stackanle SIP sockets. Sorry - I am in Tucson at present and don't have the epoxy at hand to check what it is. It's blue!! The sensor is glued *directly* to the neck for simplicity and good contact. It has never separated due to the thermal shock from nitrogen hitting the other side of the wall, which I think is remarkable. See you in Garching in a few weeks. Roger From rreiss at eso.org Thu Sep 19 08:56:22 1996 From: rreiss at eso.org (Roland Reiss) Date: Thu Jul 29 11:54:17 2004 Subject: Cryogen expiry alarms References: <9609181907.AA28251@ctiol3> Message-ID: <3240EE96.2781E494@eso.org> roger smith x294 wrote: > > ccd-world, > > (In response to Paul Jorden) > > At CTIO we have had similar experiences and I was going to write an > almost identical reply to that of Carter/Koorts/Evans at SAAO. > > We use a neck tube which goes to the center of the flask so that hold > time is more or less independent of orientation. With about 18-20 > hour hold time, we fill twice a day. > > There are occasional human errors or vacuum problems, so we too find > an alarm useful. When I have the opportunity, I glue a sensor to the > neck tube (on the vacuum side) to sense the presence of gas flow from > the boiloff. Placing the sensor near the warm end provides very good Which type of sensor do you use and how exactly do you glue it to the tube? -- * Roland Reiss European Southern Observatory * Optical Detector Team Karl-Schwarzschild-Str. 2 * D-85748 Garching, Germany * rreiss@eso.org +49-89-32006-390 (phone) * +49-89-320 23 62 (fax) From maki at indy.mtk.nao.ac.jp Thu Sep 19 09:50:05 1996 From: maki at indy.mtk.nao.ac.jp (Maki Sekiguchi) Date: Thu Jul 29 11:54:17 2004 Subject: output of CCD to preamp References: <199609182250.RAA22263@phoebus> Message-ID: <9609190057.AA03053@messia.mtk.nao.ac.jp> Mike, >> Once I am writing this message: >> Has anyone come up with a high bandwidth serial link (100+ MB/s)? >> >> Gazell HotRod - no longer in production (1 Gb/s) >> AMD TAXI - no longer in production for high data rates (150 Mb/s) >> Cypress HotLink - too slow (330 Mb/s) >> IEEE1394/Fire Wire - way too slow, for now (100-200 Mb/s) >> IBM SSA - only 20 MB/s?? >> >> FiberChannel - Fastest out there? (1 Gb/s) All necessary parts to make 1 Gbps link is commercially available. In fact we have developed a new DAQ system for Japanese 8.2m telescope (Subaru) using the hardware for FiberChannel. (It is FibreChannel not Fib"er"....) Although it is written in Japanese, you could visit http://www.messia.nao.ac.jp. I will give a table-talk on this system in coming ESO CCD conf. I may not be 100% upto date, but hardwares available for 1 Gbps FibreChannel link are: Gigabit link module : HP (Optial) and Vitesse (electrical) EO module: Finisar, Methode, etc... Tranceiver: Vitesse, TriQuit (former Gazell), HP EnDec: Vitesse, TriQuit, HP? (I thought there are also PCI cards that has 1 Gbps I/O.) If you include 622 and 256 Bps, there are more companies who makes parts for. I would rather recommend to do Web survey for upto-date products. (We have used a conbination of Vitesse Trans/Recevi/EnDec and Finisar EO module.) regards, Maki Sekiguchi maki@indy.mtk.nao.ac.jp National Astronomical Observatory Dep. of Optial & IR From hoffberg at aps.anl.gov Wed Sep 18 17:50:07 1996 From: hoffberg at aps.anl.gov (Mike Hoffberg) Date: Thu Jul 29 11:54:17 2004 Subject: output of CCD to preamp Message-ID: <199609182250.RAA22263@phoebus> The output of the CCD usually resides at a DC offset from the ground. (In particular, the Thomson TH7895 seems to have an offset of about 11 volts). The ADC used to digitize the output is expecting a signal with zero offset. The question I have is what is the best way to remove the offset: AC coupling? This might be the "safest" because it would eliminate the fear of grounding the output of the CCD. If so, where do you put the cutoff frequency of this high pass filter? Should a higher order filter be used to make the cutoff frequency higher? (Can a transformer be used to AC couple the signal?) DC restoring circuit? Used in conventional video circuits, but the commercially available ICs, do not provide the capability to remove 11 volts of off set at high bandwidths. Biasing the ADC to 11 volts? This would make the analog ground at 11 volts, the +Vcc @ 16V, the -Vcc @ 6V. This would allow the output of the CCD to be directly coupled to a preamp (buffer) which would then go to the input of the ADC. The digital outputs of the ADC could be optically isolated from the digitizer. I am not sure as to how one goes about biasing the AGND. Is it attached to a potential that is at that bias level (from the ground of the CCD and drivers?), making sure that the +Vcc and -Vcc are from supplies that have floating grounds? Once I am writing this message: Has anyone come up with a high bandwidth serial link (100+ MB/s)? Gazell HotRod - no longer in production (1 Gb/s) AMD TAXI - no longer in production for high data rates (150 Mb/s) Cypress HotLink - too slow (330 Mb/s) IEEE1394/Fire Wire - way too slow, for now (100-200 Mb/s) IBM SSA - only 20 MB/s?? FiberChannel - Fastest out there? (1 Gb/s) MIKE -- Michael Hoffberg /.\ Argonne hoffberg@aps.anl.gov // \\ National mike@anl.gov //_O_\\ Lab Standard Disclaimer Applies /__| |__\ From roger at ctiol3.ctio.noao.edu Wed Sep 18 15:07:23 1996 From: roger at ctiol3.ctio.noao.edu (roger smith x294) Date: Thu Jul 29 11:54:17 2004 Subject: Cryogen expiry alarms Message-ID: <9609181907.AA28251@ctiol3> ccd-world, (In response to Paul Jorden) At CTIO we have had similar experiences and I was going to write an almost identical reply to that of Carter/Koorts/Evans at SAAO. We use a neck tube which goes to the center of the flask so that hold time is more or less independent of orientation. With about 18-20 hour hold time, we fill twice a day. There are occasional human errors or vacuum problems, so we too find an alarm useful. When I have the opportunity, I glue a sensor to the neck tube (on the vacuum side) to sense the presence of gas flow from the boiloff. Placing the sensor near the warm end provides very good detection of loss of gas flow, within a few minutes of liquid nitrogen expiry, and with no risk of false alarms as dewar orientation, or thermal load on the cryogen flask change. I found that (in our dewars) the N2 flask temperature was too slow moving and varied strongly with orientation. If one set the threshold high enough to avoid false alarms in all orientations, then the response came late enough that the detector temperature was soon to rise. Using the vent gas temperature proved better in our system. The next level of protection we have dreamed up is to log the temperatures to a file so we can plot the thermal history of any/all dewars in real time from anywhere on the network. This will tell us time since last fill and hold time, as well as current status, and the gaps will show when the system /software was down. I would like to stress the importance of the warning from SAAO about not refilling too soon after if the Nitrogen flask and/or moleculear sieve have released water vapour into the vacuum since this will condense on the detector until it catches up thermally. Though this is very rare, this is our most serious human error: it is usually only discovered after cooling and taking flats and requires another thermal cycle to fix. It can cost a full night of observing. Roger Smith, CTIO From oiwert at eso.org Wed Sep 18 18:46:55 1996 From: oiwert at eso.org (Olaf Iwert) Date: Thu Jul 29 11:54:17 2004 Subject: LN2 cryostat warming up Message-ID: <199609181646.SAA13531@mc14.hq.eso.org> Dear Paul, Dear all, We at ESO have taken another approach for the VLT instruments based exactly on the problems you pointed out in your EMail. Our new Gen.3 cryostat features a hold time between 48 and 54 hours depending on the orientation. It is a modular system consisting of a universal cryostat head and different cooling systems which can easily be attached to it (bath cryostat in different configurations and a continuous flow system) =============================================================================== Olaf Iwert E-mail : oiwert@eso.org European Southern Observatory Phone & Voice Mail : +49-89-320-06-353 Optical Detector Lab FAX : +49-89-320-23-62 Karl-Schwarzschild-Str 2 85748 Garching GERMANY =============================================================================== From wpk at saao.ac.za Wed Sep 18 15:54:27 1996 From: wpk at saao.ac.za (Willie Koorts) Date: Thu Jul 29 11:54:17 2004 Subject: LN2 cryostat warming up (fwd) Message-ID: > I guess most of us use Liquid Nitrogen Cryostats for our CCD cameras. At > our La Palma observatory there are irregular, but inconvenient, instances > of the dewar warming up because the LN2 has run out in the night. > > Can anyone say if they never get this sort of problem? > Does anyone have any good practical solutions? > Does anyone implement a reliable LN2-loss indicator? > Any other comments? > > Regards, Paul Jorden Hi Paul, We have the same problem with the same "irregular but inconvenient" frequency of occurrences ( probably the same cryostat design as well. ) We cope it as follows ( "cope" as opposed to "solve") : 1. We have a filling routine with logsheets etc, and standard specific times of day for filling the cryostat. ( Either 3 fills/24hr or 2 fills/24hr depending on the type of cryostat and known LN2 usage pattern). Currently two of the fills are performed by daytime staff, when the telescope is not being swung around and therefore there is less wastage. 2. We tend to "overfill" - eg an old cryostat that has a 12 hour hold time on the bench is filled approxiamtely every 8 eight hours on the telescope. 3. We monitor the temperature of the LN2 container, and trigger an alarm condition on the instrument control computer if the temperature rises above a threshold - currently about 95K. We are happy that this gives an alarm within 15min or so of the LN2 running out, with plenty of time to organise a refill. 4. If an alarm occurs, the observer/night assistant must obviously refill the cryostat. 5. If any temperature in the cryostat has risen above a threshold ( currently 240K ), the warming up process must be completed and the cryostat re-pumped before being cooled again. The somewhat arbitrary threshold of 240K is based on the assumption that no cold part in the cryostat has warmed up through 273K - i.e. that water vapour is still frozen out. 6. Most times when the cryostat does warm up it tends to be the observer/user at fault - often due to bad weather and the fact that the observer doesn't go anywhere near the dome overnight, and thus forgets to do the nightime fill. There seems to be no way of removing the human factor from the equation. regards Dave Carter Willie Koorts Geoff Evans South African Astronomical Observatory From noah at wise1.tau.ac.il Wed Sep 18 10:15:36 1996 From: noah at wise1.tau.ac.il (Dr. Noah Brosch) Date: Thu Jul 29 11:54:17 2004 Subject: lN2 purging Message-ID: <199609180815.AA17891@wise12.tau.ac.il> From prj at ast.cam.ac.uk Wed Sep 18 08:42:53 1996 From: prj at ast.cam.ac.uk (Paul Jorden) Date: Thu Jul 29 11:54:17 2004 Subject: LN2 running out of cryostats Message-ID: Hi everyone- I guess most of us use Liquid Nitrogen Cryostats for our CCD cameras. At our La Palma observatory there are irregular, but inconvenient, instances of the dewar warming up because the LN2 has run out in the night. The cryostats generally have 16-20 hours hold-time when upright. However, some telescope attitudes are particularly unfavourable. The worst case is a cryostat configured for inverted use, with an inserted (offset) siphon tube. If the cryostat is rotated, and then the telescope tipped right over much of the nitrogen can be lost. Our policy of sharing detectors between different instruments, means that they are not always optimally designed for all uses. We can monitor temperature to determine when LN2 has expired, and we have also experimented with a nitrogen gas flow-meter, but have not established a working technique to completely solve the problem yet. Can anyone say if they never get this sort of problem? Does anyone have any good practical solutions? Does anyone implement a reliable LN2-loss indicator? Any other comments? Regards, Paul Jorden ------------------------------------------------------------------- E-mail: prj@ast.cam.ac.uk Machine: Kria.ast.cam.ac.uk Royal Greenwich Observatory, Madingley Road, Cambridge, CB3 0EZ, UK. Phone: +44 (0) 1223- 374000 \direct phone- 374811 \RGO Fax- 374700 From lesser at as.arizona.edu Fri Aug 23 15:20:53 1996 From: lesser at as.arizona.edu (Michael P. Lesser) Date: Thu Jul 29 11:54:17 2004 Subject: Philips 7kx9k CCDs Message-ID: <199608232220.PAA16041@bilbo.as.arizona.edu> The Steward Observatory CCD Laboratory has been collaborating under contract to American Digital Imaging, Inc. to package and characterize the Philips 7kx9k (12 um pixel) CCDs. As we just got first light on the first device I thought a few notes would be of interest on the world's largest integrated circuit (yes, it is 140 mm diagonal!!!). Please note all data is very preliminary at this time, but the device looks very good!!! For current information please check out our Lab's home page on the Web under the Projects section. There are some images there which might be of interest. We are running the CCD with one of Bob Leach's SDSU controllers. We made no modifications to operate this big device. Currently we are just reading out one of the four amplifiers (usually binned 4x4). We designed and manufactured the package here in the Lab (2.2 lbs of Invar!). It is designed to be flat to less than 10 um over the entire surface. We have packaged two devices so far, and have the first one running. These are supposedly the worst of the devices we have (as selected by DC testing by Philips). Here are some first pass results.... - we have imaged the device as low as -150C. - read noise at 33 kHz with no optimization of voltages is under 10 electrons. This is as low as we ever see at this speed in our test system. We used a 12 us parallel clock overlap (4 phase parallel, 3 phase serial). - full well (to the beginning of non-linearity) is at least 60,000 electrons. There is charge handling capacity many time this and we may do much better after optimization. - CTE looks very good in both directions. - A few traps due to interpoly shorts can be seen as short line breaks. This is typical of a device with interpoly shorts. Overall, we are VERY encouraged and impressed with this device, particularly since it was the first one packaged and that it really did not pass initial DC tests. We will have more information on the Web as characterization proceeds. It is clear the folks at Philips have done an impressive job!!!! Michael Lesser Steward Observatory University of Arizona Tucson, AZ 85721 mlesser@as.arizona.edu (520) 621-4236 (520) 626-4330 FAX *** A World Wide Web hyperlinked document can be used to navigate through the Steward Observatory CCD Laboratory information. The URL is http://bilbo.as.arizona.edu/ccdlab.html. From apo at ast.cam.ac.uk Wed Aug 21 08:31:55 1996 From: apo at ast.cam.ac.uk (Paddy Oates) Date: Thu Jul 29 11:54:17 2004 Subject: new QE shuttering technique Message-ID: John and others, The Ion pump idea sounds great...only I think we have been getting this result without trying with our super-clean Oxford Instruments dewars. We are now baking and cleaning everything in sight.... Paricularly like the idea of a data throttle... Any chance of devising a device for speeding it up! Paddy -- Contact - work :: Tele +44 (0)1223 374836 Fax +44 (0)1223 374700 E-Mail apo@ast.cam.ac.uk apo@apoates.demon.co.uk WWW Page http://www.ast.cam.ac.uk/~apo/ CCD Page http://www.ast.cam.ac.uk/~apo/docs/ccds.html ------------------------------------------------------------ -- From geary at cfa0.harvard.edu Tue Aug 20 15:55:54 1996 From: geary at cfa0.harvard.edu (John Geary) Date: Thu Jul 29 11:54:17 2004 Subject: new QE shuttering technique Message-ID: <9608201955.AA06476@cfa0.harvard.edu.HARVARD.EDU> I have discovered a new way of "electronic shuttering" CCD response, using the ION PUMP (of all things!). Those of you with a perverse point of view (most of you, I think) will find all sorts of new uses for this valuable technique. The trick is to take your Pt-flash-gated CCD from M. Lesser, put it in a really clean dewar on a really clean vacuum pump, suck it down, fill the dewar tank with LN2, and then turn the ion pump on before anything gets very cold. Everything looks great, including the vacuum, until your go to take a flat or something. Wow! Here are the results: QE (400 nm) using the above: 1.5 % QE (400 nm) after O2 soak: 97.7 % (ML and I have discussed this a bit. Maybe residual water vapor is initially dissociated by the ion pump, allowing hydrogen poisoning to develop?? Nothing bad happens if you wait for the dewar innards to get very cold before lighting up the ion pump.) So, what uses for the above 40 db attenuator can you think of? How about: (1) Teaching tool for observers too young to remember photographic plates. (Hmmm. This probably includes many on this list !). (2) Data throttle, for observers who were counting on bad weather to get an urgent paper finished. (3) April Fool joke for your favorite dickhead observer (you furnish your own list). Any more? |\ |\ | \ OoOo \ \ \ \ oOOo \ \ / `~~~--__ oOo / \___----~~' `~~-_ o _______ __________ \ /// (O) `\_(__||___)________/____ / /~~~~-, ,__. , /// __,,,,) || o ______/ \ \/ \/ `~~~; ,---~~-_`_= \ \---||--o-' \ / / / / \ |_./ _/_/ /;|\ John Geary PADI DM-52283 geary@cfa.harvard.edu From prj at ast.cam.ac.uk Thu Aug 15 13:03:56 1996 From: prj at ast.cam.ac.uk (Paul Jorden) Date: Thu Jul 29 11:54:17 2004 Subject: CCD Controller Specification Questionnaire (RGO) Message-ID: Greetings everyone. We are doing a survey of current CCD controller requirements, and would appreciate all responses that you have time to deal with. Thanks. Paul Jorden ----------- Please return all completed questionnaires to: John Turner email: jct@ast.cam.ac.uk Royal Greenwich Observatory Madingley Road Cambridge CB3 0EZ Tel: 01223 374000 Fax: 01223 374700 Deadline: 23rd August 1996 As part of a study into the feasibility of designing or procuring a new CCD controller for use by the RGO, its collaborators and its customers, this questionnaire has been produced to collect information relating to the specifications required by its potential users. Any feedback would be greatly appreciated. 1. Number of ports : (1, 2, 4, Other (specify)) 2. Pixel digitisation rate (kpix/s)(/port): (specify) 3. ADC resolution (bits): (specify) 4. Support for... (specify) Variable Speed Readout (Y/N) Binning (Y/N) Windows (Y/N) 5. Number of gains: (specify) 6. Peripheral Support: (specify) Cooling: Peltier (Y/N) LN2 (Y/N) Closed Cycle (Y/N) Other (specify) Shutters (Y/N) Filters (Y/N) Preflash LEDs (Y/N) GPS timestamps (Y/N) Others (specify) 7. Mosaic / Multiple CCD support: (Y/N) Please specify any details 8. Host computer: PC (Y/N) UNIX Workstation (Y/N) VAX (Y/N) Other (specify) 9. Interfaces: S-Bus (Y/N) VME (Y/N) PCI/PMC (Y/N) Other (specify) 10. Application areas envisaged: (e.g. instrument science, adaptive optics, imaging etc.) 11. Areas of risk: (specify any requirements that from experience were found to be necessary or useful and clarify any areas of perceived risk with regard to controller design or procurement). 12. Financial considerations: 13. Notes: Thank you for completing this questionnaire. ------------------------------------------------------------------- E-mail: prj@ast.cam.ac.uk Machine: Kria.ast.cam.ac.uk Royal Greenwich Observatory, Madingley Road, Cambridge, CB3 0EZ, UK. Phone: +44 (0) 1223- 374000 \direct phone- 374811 \RGO Fax- 374700 From preben at astro.ku.dk Tue Aug 6 11:34:34 1996 From: preben at astro.ku.dk (Preben Noerregaard) Date: Thu Jul 29 11:54:17 2004 Subject: Contamination of PPtF CCD's Message-ID: Hi Derek We, - and others, have had some experiences that PPtF chips tends to loose their sensitivity when kept in vacuum at room temperature. It looks like the oxygen disappears from the surface. Keeping the chip in dry air for a few hours and then pump the dewar down again, will recharge the surface and the QE is OK again. Regards, 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 -------------------------------------------- From roger at ctiol3.ctio.noao.edu Sat Aug 3 11:55:59 1996 From: roger at ctiol3.ctio.noao.edu (roger smith x294) Date: Thu Jul 29 11:54:17 2004 Subject: contaimination by superinsulation Message-ID: <9608031555.AA16115@ctiol3> Derek, Once upon a time, we used aluminized mylar film ("superinsulation") as a radiation barrier. We eliminated it from our CCD dewars many years ago after discovering that it adsorbed water vapour and was the primary cause of our early contamination problems. Outgassing from the adhesive tape was also a concern. Our dewars are now built in house from all Aluminium. We get similar radiation performance to superinsulation by highly polishing the inner wall of the dewar and the outer walls of the nitrogen can, mount ad so on. Polishing is also necessary to minimize adsorption onto the Aluminium surfaces. Anodizing is forbidden on all surfaces in the vacuum. We still have some occasional contamination problems. We use small amounts of fiberglass in thin walled tubes and the CCD connector, plus a few nylon bolts, but we feel that stricter handling procedures and baking are probably all that is required. Our colleagues in NOAO/Tucson have their own dewar design which shares most of the same attributes, except that their inner can is copper. I have been using one of their dewars containing a pair of Loral 2x4Ks for the last year (sorry no Pt flash gate), and I am impressed with how rapidly it pumps down and holds vacuum. ...They electro-polish and are very careful with handling, and this appears to pay big dividends. Roger Smith, CTIO  From dji at ast.cam.ac.uk Fri Aug 2 13:00:54 1996 From: dji at ast.cam.ac.uk (Derek Ives) Date: Thu Jul 29 11:54:17 2004 Subject: Contamination ? of PPtF CCDs Message-ID: Hi CCD gurus, I was wondering if anyone else out there was running the Passivated Platinum Film LORAL devices as produced by Mike and his group at Steward. I am having problems with the QE remaining stable with time and/or temperature. This may be due to some form of contamination ( of water vapour ? ) possibly in our dewars. We use standard Oxford Instruments dewars, made from aluminum with mylar film taped to the inner surfaces , some stainless bits and pieces and not much else. We do use a small no. of 'O' rings with Fomblin very high vacuum grease. We can bake the CCDs out in the dewars and this process "reactivates" the QE response of the CCDs. If we then leave the CCDs in the dewars under vacuum but at room temp. for a few days and then repeat the QE measurements (in diode mode - its very quick) we find that it has dropped off significantly, especially in the blue. We also find that the QE in the blue reduces with temperature. Regards, Derek Ives ******************************************************************************** E-mail: dji@ast.cam.ac.uk Machine: Kria.ast.cam.ac.uk Royal Greenwich Observatory, Madingley Road, Cambridge, CB3 0EZ, UK. Phone: +44 (0) 1223- 374000 \direct phone- 374824 \RGO Fax- 3747000 ******************************************************************************** From drm at ing.iac.es Mon Jul 29 15:08:34 1996 From: drm at ing.iac.es (Daniel Matthews) Date: Thu Jul 29 11:54:18 2004 Subject: CCD job in La Palma Message-ID: Position for one, possibly two CCD people in La Palma (Isaac Newton Group of telescopes). HPTO or SPTO - adverts (internal and press) follows. For more info contact: Clive Jackman ------------------------------------------------------------------------------ PPARC Council Vacancy Notice The Observatories, Isaac Newton Group HPTO/SPTO Electronics Engineers or Physicists Operations Division Closing date: 16 August 1996 Vacancies exists within the electronics group of the Isaac Newton Group of Telescopes on La Palma in the Canary Island, for an electronics engineer or physicist specialising in astronomical detectors. The Isaac Newton group comprises three world-class optical telescopes: the 4.2-m William Herschel Telescope, the 2.5-m Isaac Newton Telescope and the 1-m Jacobus Kapteyn Telescope. The telescopes are equipped with a powerful set of instruments and detectors allowing a wide range of astronomical observations. They are situated at the Observatorio del Roque de Los Muchachos at an altitude of 2400m. Light collected by the telescopes may be presented to a variety of astronomical instruments before detection by highly sensitive low noise CCDs, or infra red array detectors. To remain competitive within the astronomical community it is essential that we provide the latest in detector technology and ensure that these devices operate at the peak of their performance. DUTIES A successful applicant could be expected to head the detector section of the electronics group. The group comprises of a multi-national team of 10 engineers who enhance and maintain a wide range of electronic hardware. The equipment includes both analogue and digital systems at all stages of the equipment life cycle. The postholders will have an additional responsibility for astronomical detector systems. This will involve trouble shooting problems reported by users, preparing detectors prior to instrument changes, maintaining quality control standards and planning and implementing enhancements. The telescopes are used every night of the year, so a willingness to work to tight deadline under difficult conditions often at unsociable times is most important. Night-time engineering support is mostly provided by members of the electronics group. Duties of the postholder will include: Specific responsibility for daily maintenance and quality control of all astronomical detector systems. Responsibility for commissioning and characterising new detectors delivered to the observatory. Involvement in defining and planning upgrade programmes General responsibility, shared with the rest of the electronics group, for maintenance of electronics systems. Providing night-time engineering support for the telescopes, as a member of the Duty Engineer roster. QUALIFICATIONS AND EXPERIENCE Successful applicants for the posts will probably have had experience working with low level- imaging systems operating at optical or infra red wavelengths, possibly in an R&D environment. Some knowledge of modern detector systems used in astronomy (CCDs, infra-red arrays, intensified TVs and image photon counting systems) is important. Applicants must have demonstrated a capacity to work at professional engineer level. APPLICATIONS ETC. The successful candidates will be based on La Palma where free accommodation will be provided along with a wide range of other benefits. The salary will be free of UK and local income tax, in the range of œ14122 to œ24888, together with additional allowances depending on personal circumstances. Further progression to the band maximum of œ29986 is applicable through performance pay. A relocation package will also be available. Staff wishing to be considered for the post should complete a PPARC Vacancy Application Form (obtainable from PMG) and forward it via the Head of their Group or Section, to reach the Personnel Section ING La Palma, at the following address: Royal Observatories , Isaac Newton Group, Personnel Section, Apartado de Correos 321, 38780 Santa Cruz de la Palma, Canary Islands by the closing date. Applications from non-permanent employees can only be considered if they were recruited to their present posts through fair and open competition and have the necessary entry qualifications of the grade for which they are applying. For permanent employees, promotion to this fixed-term post will be non-substantive. On completion of their fixed-term appointment, the Council will first seek to re-assign them to their originating establishment; if no opportunities are available it will use its best endeavours to seek opportunities to place them elsewhere in the organisation. Applications for a request interview may be made against this Vacancy Notice by employees of the PPARC who have served in their present grade for at least seven years (at the date of this Notice) and have not been interviewed for promotion within the same Occupational Group for at least four years. CEM 7D, section 8 refers. Applicants applying for a vacancy at an establishment other than their own, should also complete a "Notification of Application" slip and forward it directly to the Personnel Section of the establishment with the vacancy. A non-industrial employee serving on AEA-type conditions would be entitled to retain those conditions on appointment to this post. For applicants from outside PPARC Swindon Office, applications must be with their local Personnel Section not less than three days before the closing date. This post is also being advertised externally. Further information on these posts is available from Clive Jackman on La Palma (telephone 34 22 405555, fax 34 22 405646, Internet e-mail CWMJ@ING.IAC.ES). ----------------------------------------------------------------------------- The Isaac Newton Group of Telescopes (ING) on La Palma in the Canary Islands are looking for astronomical detector specialists. Electronics Engineers or Physicists Isaac Newton Group of Telescopes La Palma, Canary Islands The Isaac Newton group comprises three world-class optical telescopes: the 4.2-m William Herschel Telescope, the 2.5-m Isaac Newton Telescope and the 1-m Jacobus Kapteyn Telescope. The telescopes are equipped with a powerful set of instruments and detectors allowing a wide range of astronomical observations. They are situated at the Observatorio del Roque de Los Muchachos at an altitude of 2400m. Light collected by the telescopes may be presented to a variety of astronomical instruments before detection by highly sensitive CCD, or infra red array detectors. To remain competitive within the astronomical community it is essential that we provide the latest in detector technology and ensure that these devices operate at the peak of their performance. Successful applicants for the posts will probably have had experience working with low level- imaging systems operating at optical or infra red wavelengths, possibly in an R&D environment. Some knowledge of modern detector systems used in astronomy (CCDs, infra-red arrays, intensified TVs and image photon counting systems) is important. Applicants should have demonstrated a capacity to work at chartered engineer level. The successful applicants will be based on La Palma where free accommodation will be provided. The salary will be free of UK and local income tax, in the range of œ14122 to œ24888, together with additional allowances depending on personal circumstances. Further progression to the band maximum of œ29986 is applicable through performance pay. A relocation package will also be available. For further information and an application form please contact Clive Jackman on La Palma (telephone 34 22 405555, fax 34 22 405646, Internet e-mail CWMJ@ING.IAC.ES). From lesser at as.arizona.edu Thu Jul 25 09:12:13 1996 From: lesser at as.arizona.edu (Michael P. Lesser) Date: Thu Jul 29 11:54:18 2004 Subject: Electronic Imaging: Science & Technology SPIE Symposium Message-ID: <199607251612.JAA19577@bilbo.as.arizona.edu> Hi Everyone! We have only received a few astronomy related abstracts for next years SPIE symposium even though it is past the abstract deadline. If any of you would like to present a paper please contact me. Last year we had some excellent papers relating to CCDs, especially for astronomy and digital imaging. If you can present a paper, please let me know right away so we can arrange for a late abstract. The symposium is huge and offers and excellent opportunity to see exhibits and papers in all areas of Electronic Imaging. Thank you! -Michael Lesser ******* Cameras and Systems Part of IS&T/SPIE's 1997 Symposium on Electronic Imaging: Science & Technology 8-14 February 1997 San Jose Convention Center San Jose, California USA Conference Chairs: Michael Lesser, Univ. of Arizona, Steward Observatory; Wesley A. Miller, Eastman Kodak Co. Microelectronic Technology CCD-based cameras and scanners have found wide applicability in consumer, commercial and scientific imaging applications. Advances are continuing in areas such as digital photography, astronomy, spectroscopy, highway safety, industrial inspection, and in many others. In addition, image processing within the cameras or in dedicated computers connected to the cameras comprise systems with analytical capabilities and intelligence that was unimagined only a short time ago. In this conference we solicit papers that describe cameras and camera technologies for: * astronomy * digital photography * computers * spectroscopy, microscopy * slow scan, low noise, high speed, high resolution, low light level, and other applications * remote sensing * new and novel applications. Papers addressing issues such as camera intelligence, interfaces, image storage technologies, signal processing, and A/D conversion are also welcome. This conference is just one of nearly 30 conferences to be held at the EI'97 symposium. And EI'97 is one of 4 collocated symposia (Electronic Imaging, Biomedical Optics, Lasers and Applications, and Optoelectronics). Watch SPIE's web site for the entire Photonics West Call for Papers (mid-May): http://www.spie.org/web/meetings/calls/pw97/pw97call_home.html For a printed call for papers or other information: E-mail: pw97@spie.org Fax: 360/647-1445 Phone: 360/676-3290 DEADLINES Paper Abstracts (for review) Due from Authors: 15 July 1996 Camera-Ready Abstracts (from accepted authors) Due: 18 November 1996 Manuscripts Due from all Authors: 13 January 1997 GUIDELINES FOR SUBMITTING AN ABSTRACT Send a 500 word abstract of your paper, by 15 July, in ONE of the following ways: >>electronic mail in ASCII format (NOT encoded) to abstracts@spie.org The SUBJECT line must include: EI97 (Lesser/Miller) (Send one submission per email message.) Note: There will also be available an interactive abstract submission form on the web site. >>mail (please mail 4 hard copies) to: IS&T/SPIE Electronic Imaging '97 SPIE, P.O. Box 10, Bellingham, WA 98227-0010 Shipping Address: 1000 20th Street, Bellingham, WA 98225 Telephone: 360/676-3290 >>fax to SPIE at 360/647-1445 (Please send one submission per fax.) Be sure each abstract includes the following: 1. CONFERENCE CHAIR and CONFERENCE TITLE (submit to ONLY ONE conference) to which the abstract is submitted 2. AUTHOR LISTING (List principal author first) for each author: full name [first(given) last(family] and affiliation, mailing address, phone/fax numbers, email 3. ABSTRACT/PAPER TITLE 4. ABSTRACT TEXT: 500 words typed on white paper 5. KEYWORDS: maximum of 5 keywords 6. BRIEF BIOGRAPHY of the principal author: 50-100 words Please contact SPIE if you have any questions or require further information. From maury at ocar01.obs-azur.fr Wed Jul 24 03:17:55 1996 From: maury at ocar01.obs-azur.fr (ALAIN MAURY) Date: Thu Jul 29 11:54:18 2004 Subject: CDS ICs from Datel Message-ID: <009A5C97.2B945700.533@ocar01.obs-azur.fr> Hello world, We are currently operating a 5 microseconds 16 bits acquisition chain for our 2K CCD. The next generation CCD will be larger and will require a faster acquisition system. We are aiming at something in the 14 bits 1 MHz range/4 parallel channels. We have found no satisfying analog switches, except the DG612, which we are welcome to buy here in France, but only in very large quantities. If one of you had some of them available for resale, I would be glad to exchange a couple of them against a n dollar bill sent in an envelope so as to test them in real life. The other solution is to use double conversion systems with faster converters or two converters and a Lattice style chip to perform a digital substraction so as to send both conversion in a single optical fiber to the control room. We have also seen some Datel CDS chips ( CDS 1401