From cox at not.iac.es Tue Jan 9 08:13:57 2007 From: cox at not.iac.es (Graham C. Cox) Date: Tue, 9 Jan 2007 11:13:57 +0000 (WET) Subject: CCD-world: persistent noise problem Message-ID: Dear All, We have got a persistent noise problem with one of our CCDs, it takes the form along a row, of one or two bright pixels adjacent to one or two dark pixels. The levels in the bright and dark pixels are up to 40 counts off the bias level, (see attached images). The noise has a well defined repetition rate that corresponds for us to approximately every 175 pixels in the serial direction, this is roughly 300Hz. We don't expect anyone to provide a solution to this problem but we would be grateful if possible sources of this form of noise could be suggested? One theory is that the instrument is acting as an aerial and receiving a signal from somewhere. Tests to try and identify the noise have included, exchanging the CCD controller with two others (mounted on and off the instrument, a low resolution spectrograph and imager), replacing all the cabling, switching off everything on the instrument and on the telescope, but the noise remains. We even get the noise when the instrument is off the telescope sitting on its trolley, which has rubber wheels, and only powering the CCD controller. Disconnecting the mains earth has also been tried. Regards, Graham Cox -- Graham C. Cox Nordic Optical Telescope Tel +34 922 425468 Apartado 474 Fax +34 922 425475 E-38700 Santa Cruz de La Palma http://www.not.iac.es Canarias, Spain Email cox at not.iac.es -------------- next part -------------- A non-text attachment was scrubbed... Name: pi270001.fits Type: application/octet-stream Size: 731520 bytes Desc: Url : http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070109/575a0a4c/attachment.obj -------------- next part -------------- A non-text attachment was scrubbed... Name: pi270001.png Type: image/png Size: 18548 bytes Desc: Url : http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070109/575a0a4c/attachment.png From tg.burke at ngc.com Tue Jan 9 12:25:48 2007 From: tg.burke at ngc.com (Burke, Thomas G.) Date: Tue, 9 Jan 2007 10:25:48 -0500 Subject: CCD-world: persistent noise problem In-Reply-To: Message-ID: Any way you can shield it? Put a good ground on the dewar and run it dark (attach a metal plate to the front... It could be that your noise is being induced through your cabling or power lines... For some reason, 300Hz is tickling my memory banks about power lines, but I'm not sure... How well-filtered are your power supplies? -----Original Message----- From: ccd-world-bounces at ctio.noao.edu [mailto:ccd-world-bounces at ctio.noao.edu] On Behalf Of Graham C. Cox Sent: Tuesday, January 09, 2007 6:14 AM To: Optical & SWIR imager development for professional astronomy Subject: CCD-world: persistent noise problem Dear All, We have got a persistent noise problem with one of our CCDs, it takes the form along a row, of one or two bright pixels adjacent to one or two dark pixels. The levels in the bright and dark pixels are up to 40 counts off the bias level, (see attached images). The noise has a well defined repetition rate that corresponds for us to approximately every 175 pixels in the serial direction, this is roughly 300Hz. We don't expect anyone to provide a solution to this problem but we would be grateful if possible sources of this form of noise could be suggested? One theory is that the instrument is acting as an aerial and receiving a signal from somewhere. Tests to try and identify the noise have included, exchanging the CCD controller with two others (mounted on and off the instrument, a low resolution spectrograph and imager), replacing all the cabling, switching off everything on the instrument and on the telescope, but the noise remains. We even get the noise when the instrument is off the telescope sitting on its trolley, which has rubber wheels, and only powering the CCD controller. Disconnecting the mains earth has also been tried. Regards, Graham Cox -- Graham C. Cox Nordic Optical Telescope Tel +34 922 425468 Apartado 474 Fax +34 922 425475 E-38700 Santa Cruz de La Palma http://www.not.iac.es Canarias, Spain Email cox at not.iac.es From rsmith at astro.caltech.edu Tue Jan 9 13:50:40 2007 From: rsmith at astro.caltech.edu (Roger Smith) Date: Tue, 9 Jan 2007 08:50:40 -0800 Subject: CCD-world: persistent noise problem In-Reply-To: References: Message-ID: Graham, Some ideas... Do the spikes occur at fixed locations in every image? (Average a long sequence of short darks.) If so, this could be interference from data packet transmission, though every 175 pixels implies a small data packet. Is your temperature controller digital or analog? Does disabling it get rid of the noise. Is there any low rate monitoring of bias voltages or temperature readout at this cadence? Is your detector ground isolated from the dewar (shield). I believe in joining the various grounds out in the controller to minimize current in the high impedance dewar wiring, particularly shield current. If you are stuck, take the CCD out, and loopback bias voltages into the video chain (at the CCD location). You can compare with a loopback the controller end of the cable. This should give you a lead or rule some things out. -- Roger On Jan 9, 2007, at 3:13 AM, Graham C. Cox wrote: > Dear All, > We have got a persistent noise problem with one of our > CCDs, it > takes the form along a row, of one or two bright pixels adjacent to > one or > two dark pixels. The levels in the bright and dark pixels are up to 40 > counts off the bias level, (see attached images). The noise has a well > defined repetition rate that corresponds for us to approximately > every 175 > pixels in the serial direction, this is roughly 300Hz. > > We don't expect anyone to provide a solution to this problem but > we would > be grateful if possible sources of this form of noise could be > suggested? > One theory is that the instrument is acting as an aerial and > receiving a > signal from somewhere. > > Tests to try and identify the noise have included, exchanging the CCD > controller with two others (mounted on and off the instrument, a low > resolution spectrograph and imager), replacing all the cabling, > switching > off everything on the instrument and on the telescope, but the noise > remains. We even get the noise when the instrument is off the > telescope > sitting on its trolley, which has rubber wheels, and only powering > the CCD > controller. Disconnecting the mains earth has also been tried. > > Regards, > Graham Cox > > -- > Graham C. Cox > Nordic Optical Telescope Tel +34 922 425468 > Apartado 474 Fax +34 922 425475 > E-38700 Santa Cruz de La Palma http:// > www.not.iac.es > Canarias, Spain Email cox at not.iac.es > > > > > -- CCD-world -- > CCD-world is fully moderated. Send posts to CCD-world at ctio.noao.edu > Standard replies will go to the list; address personal replies > manually. > For more information, please go to: http://www.ctio.noao.edu/ > mailman/listinfo/ccd-world From S.Fellowes at sstl.co.uk Tue Jan 9 14:13:38 2007 From: S.Fellowes at sstl.co.uk (Simon Fellowes) Date: Tue, 9 Jan 2007 17:13:38 -0000 Subject: CCD-world: persistent noise problem Message-ID: <94ABC0A314235C4EB382D09EC52D712A0734334B@taurus.sstl.co.uk> Graham, Are the electronics that drive and recieve the data from the CCD "bespoke"? I made a drive circuit and a recieve circuit myself, and found similar noise on the image that I obtained, careful selection of appropriate caps in the right places can help. Good luck -----Original Message----- From: ccd-world-bounces at ctio.noao.edu [mailto:ccd-world-bounces at ctio.noao.edu]On Behalf Of Graham C. Cox Sent: 09 January 2007 11:14 To: Optical & SWIR imager development for professional astronomy Subject: CCD-world: persistent noise problem Dear All, We have got a persistent noise problem with one of our CCDs, it takes the form along a row, of one or two bright pixels adjacent to one or two dark pixels. The levels in the bright and dark pixels are up to 40 counts off the bias level, (see attached images). The noise has a well defined repetition rate that corresponds for us to approximately every 175 pixels in the serial direction, this is roughly 300Hz. We don't expect anyone to provide a solution to this problem but we would be grateful if possible sources of this form of noise could be suggested? One theory is that the instrument is acting as an aerial and receiving a signal from somewhere. Tests to try and identify the noise have included, exchanging the CCD controller with two others (mounted on and off the instrument, a low resolution spectrograph and imager), replacing all the cabling, switching off everything on the instrument and on the telescope, but the noise remains. We even get the noise when the instrument is off the telescope sitting on its trolley, which has rubber wheels, and only powering the CCD controller. Disconnecting the mains earth has also been tried. Regards, Graham Cox -- Graham C. Cox Nordic Optical Telescope Tel +34 922 425468 Apartado 474 Fax +34 922 425475 E-38700 Santa Cruz de La Palma http://www.not.iac.es Canarias, Spain Email cox at not.iac.es From jreyes at eso.org Tue Jan 9 14:20:53 2007 From: jreyes at eso.org (Javier Reyes) Date: Tue, 09 Jan 2007 18:20:53 +0100 Subject: CCD-world: 850nm vs. 1310nm optical transceivers Message-ID: <45A3CEF5.1050008@eso.org> Hi folks, As you might already know, we are at ESO developing a new detector controller called NGC. NGC front-end electronics will communicate to the back-end computer using a 2.5Gbps optical link. For this link we are currently using 1310nm transceivers and single-mode fibers to fulfill a transmission distance of about 500m. For several reasons we want to use 850nm transceivers instead and need to know whether we can reach this distance at this bitrate with single- or multi-mode fibers. Does any of you have ever used 850nm at 2.5Gbps and over 500m fiber? Cheers, Javier -- ----------------------------------------------------------------- Javier Reyes European Southern Observatory ESO Instrumentation Division Karl Schwarzschildstr. 2 Optical Detector Laboratory 85748 Garching bei M?nchen Phone: +49-89-32006-384/520 Germany Fax: +49-89-32006-530 E-mail: jreyes at eso.org From dkf at ll.mit.edu Tue Jan 9 12:40:20 2007 From: dkf at ll.mit.edu (Fischi, David) Date: Tue, 9 Jan 2007 10:40:20 -0500 Subject: CCD-world: persistent noise problem In-Reply-To: Message-ID: <759330D15859D744927C6E2A8CE78D3056862D@llexchange01.mitll.ad.local> Graham, It sure looks like EMI. The variation in bright-to-dark pixels implies a differentiation of a spike which can be capacitive feedthrough or pickup. The sparkles are regular, but walking through the image, which means it is asynchronous with the CCD timing - once again an EMI source. The low rate suggests a power quality issue (really WAGing here). Has the power for the facility and the camera been checked lately (power line spikes)? Has anything changed in the power & ground scheme? If decoupling in the analog section was marginal but working before and something changed for the worse ... It might help to break the CCD connection, terminate the input to the digitizer section and see if the noise is still there with a flat input. This could help localize where possible external interference is being picked up - the sensor or the electronics. Just a reminder of the basics for EMI, remember the trio: source-path-receiver. Good luck. David Fischi Group 99, Advanced Space Systems and Concepts M.I.T. Lincoln Laboratory 244 Wood St., Lexington, MA 02420 Voice: 781-981-5162, Email: dkf at ll.mit.edu -----Original Message----- From: ccd-world-bounces at ctio.noao.edu [mailto:ccd-world-bounces at ctio.noao.edu] On Behalf Of Graham C. Cox Sent: Tuesday, January 09, 2007 6:14 AM To: Optical & SWIR imager development for professional astronomy Subject: CCD-world: persistent noise problem Dear All, We have got a persistent noise problem with one of our CCDs, it takes the form along a row, of one or two bright pixels adjacent to one or two dark pixels. The levels in the bright and dark pixels are up to 40 counts off the bias level, (see attached images). The noise has a well defined repetition rate that corresponds for us to approximately every 175 pixels in the serial direction, this is roughly 300Hz. We don't expect anyone to provide a solution to this problem but we would be grateful if possible sources of this form of noise could be suggested? One theory is that the instrument is acting as an aerial and receiving a signal from somewhere. Tests to try and identify the noise have included, exchanging the CCD controller with two others (mounted on and off the instrument, a low resolution spectrograph and imager), replacing all the cabling, switching off everything on the instrument and on the telescope, but the noise remains. We even get the noise when the instrument is off the telescope sitting on its trolley, which has rubber wheels, and only powering the CCD controller. Disconnecting the mains earth has also been tried. Regards, Graham Cox -- Graham C. Cox Nordic Optical Telescope Tel +34 922 425468 Apartado 474 Fax +34 922 425475 E-38700 Santa Cruz de La Palma http://www.not.iac.es Canarias, Spain Email cox at not.iac.es From cdm at ast.cam.ac.uk Tue Jan 9 12:27:48 2007 From: cdm at ast.cam.ac.uk (Craig Mackay) Date: Tue, 09 Jan 2007 15:27:48 +0000 Subject: CCD-world: persistent noise problem In-Reply-To: References: Message-ID: <45A3B474.4090301@ast.cam.ac.uk> An HTML attachment was scrubbed... URL: http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070109/1cd10028/attachment.html -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: image/png Size: 18548 bytes Desc: not available Url : http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070109/1cd10028/attachment.png From atwood at mps.ohio-state.edu Tue Jan 9 14:39:59 2007 From: atwood at mps.ohio-state.edu (Bruce Atwood) Date: Tue, 09 Jan 2007 12:39:59 -0500 Subject: CCD-world: 850nm vs. 1310nm optical transceivers In-Reply-To: <45A3CEF5.1050008@eso.org> References: <45A3CEF5.1050008@eso.org> Message-ID: <45A3D36F.901@ohstpy.mps.ohio-state.edu> Javier Reyes wrote: >Hi folks, > >As you might already know, we are at ESO developing a new detector >controller called NGC. NGC front-end electronics will communicate to >the back-end computer using a 2.5Gbps optical link. For this link we >are currently using 1310nm transceivers and single-mode fibers to >fulfill a transmission distance of about 500m. > >For several reasons we want to use 850nm transceivers instead and need >to know whether we can reach this distance at this bitrate with >single- or multi-mode fibers. Does any of you have ever used 850nm at >2.5Gbps and over 500m fiber? > >Cheers, > >Javier > > > Hola Javier, We are using 850 nm at 2.0 Gbps with Finasar parts (FTLF 8519 P2BNL). They claim 300 m with 62.5 micron core fibers and 500m with 50 micron cores. We are trying to stick with 62.5 micron cores since it seems to be far and away the most common in astronomy and in networking in general. Don't forget that connectors eat up your optical budget very quickly. cheers -- Bruce Atwood Department of Astronomy The Ohio State University 140 West 18th Ave. Columbus, OH 43210-1173 Phone 614.292.6279 FAX 614.292.2928 From atwood at mps.ohio-state.edu Tue Jan 9 14:42:40 2007 From: atwood at mps.ohio-state.edu (Bruce Atwood) Date: Tue, 09 Jan 2007 12:42:40 -0500 Subject: CCD-world: persistent noise problem In-Reply-To: References: Message-ID: <45A3D410.5070402@ohstpy.mps.ohio-state.edu> Just a thought... 50 Hz three phase equipment will make a lot noise at 300Hz. Graham C. Cox wrote: >Dear All, > We have got a persistent noise problem with one of our CCDs, it >takes the form along a row, of one or two bright pixels adjacent to one or >two dark pixels. The levels in the bright and dark pixels are up to 40 >counts off the bias level, (see attached images). The noise has a well >defined repetition rate that corresponds for us to approximately every 175 >pixels in the serial direction, this is roughly 300Hz. > > We don't expect anyone to provide a solution to this problem but we would >be grateful if possible sources of this form of noise could be suggested? >One theory is that the instrument is acting as an aerial and receiving a >signal from somewhere. > > Tests to try and identify the noise have included, exchanging the CCD >controller with two others (mounted on and off the instrument, a low >resolution spectrograph and imager), replacing all the cabling, switching >off everything on the instrument and on the telescope, but the noise >remains. We even get the noise when the instrument is off the telescope >sitting on its trolley, which has rubber wheels, and only powering the CCD >controller. Disconnecting the mains earth has also been tried. > > Regards, > Graham Cox > > > >------------------------------------------------------------------------ > > >-- CCD-world -- >CCD-world is fully moderated. Send posts to CCD-world at ctio.noao.edu >Standard replies will go to the list; address personal replies manually. >For more information, please go to: http://www.ctio.noao.edu/mailman/listinfo/ccd-world > > -- Bruce Atwood Department of Astronomy The Ohio State University 140 West 18th Ave. Columbus, OH 43210-1173 Phone 614.292.6279 FAX 614.292.2928 -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070109/6dbf21eb/attachment.html From rlobdill at lcogt.net Tue Jan 9 15:22:19 2007 From: rlobdill at lcogt.net (Rich Lobdill) Date: Tue, 9 Jan 2007 10:22:19 -0800 Subject: CCD-world: DC-coupled pre-amp? Message-ID: <0E7451C890AF144997C31B2C771C64A201FE77@MAILSBA.LCO.GTN> Dear All: Here at Las Cumbres Observatory, I've been given the opportunity to approach the front-end camera design with a clean slate. My background is in low-noise analog amplifiers used in electrophysiology. I've not designed a camera so that might be good or bad !?. I've come up with a little circuit to continually subtract the DC level of the CCD output while at the same time leaving the high frequency information unaltered for presenting to the CDS circuit. This adds a few parts but removes the need for a high quality, large footprint blocking cap (and even the high quality caps are not ideal). There are no switches used, the DC subtraction is done with a linear approach. I wouldn't consider this approach novel but I have not seen it implemented in any of the camera schemes I have been able to study. So my question to my esteemed colleagues on this list is: Are there well known downsides to this approach that make it infeasible? I realize noise could be added due to this topology but I think with an eye towards noise, the noise addition could be reduced to being negligible. Thanks in advance for any insight. Rich Lobdill Las Cumbres Observatory Goleta, CA -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070109/d4084a5c/attachment.html From tg.burke at ngc.com Tue Jan 9 16:01:39 2007 From: tg.burke at ngc.com (Burke, Thomas G.) Date: Tue, 9 Jan 2007 14:01:39 -0500 Subject: CCD-world: DC-coupled pre-amp? In-Reply-To: <0E7451C890AF144997C31B2C771C64A201FE77@MAILSBA.LCO.GTN> Message-ID: Why bother? A CDS circuit, properly designed, will remove the DC offset without the extra components. At leastif you do it in the analog domain. ________________________________ From: ccd-world-bounces at ctio.noao.edu [mailto:ccd-world-bounces at ctio.noao.edu] On Behalf Of Rich Lobdill Sent: Tuesday, January 09, 2007 1:22 PM To: CCD-world at ctio.noao.edu Subject: CCD-world: DC-coupled pre-amp? Dear All: Here at Las Cumbres Observatory, I've been given the opportunity to approach the front-end camera design with a clean slate. My background is in low-noise analog amplifiers used in electrophysiology. I've not designed a camera so that might be good or bad !?. I've come up with a little circuit to continually subtract the DC level of the CCD output while at the same time leaving the high frequency information unaltered for presenting to the CDS circuit. This adds a few parts but removes the need for a high quality, large footprint blocking cap (and even the high quality caps are not ideal). There are no switches used, the DC subtraction is done with a linear approach. I wouldn't consider this approach novel but I have not seen it implemented in any of the camera schemes I have been able to study. So my question to my esteemed colleagues on this list is: Are there well known downsides to this approach that make it infeasible? I realize noise could be added due to this topology but I think with an eye towards noise, the noise addition could be reduced to being negligible. Thanks in advance for any insight. Rich Lobdill Las Cumbres Observatory Goleta, CA -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070109/666165e6/attachment.html From nzbackpackers at yahoo.com Tue Jan 9 19:45:19 2007 From: nzbackpackers at yahoo.com (Hugh Molesworth) Date: Tue, 09 Jan 2007 14:45:19 -0800 Subject: CCD-world: persistent noise problem In-Reply-To: References: Message-ID: <7.0.1.0.2.20070109144019.021afe40@yahoo.com> A good start is to identify whether it is mains-bourne or radiated interference. A simple way to do this is to remove all AC voltage power inputs and replace them with a battery, preferably one with a very low impedance. Not always easy to do, of course, but if it is an option then it's worth a try. There are some simple analogue circuits to apply if it turns out to be an RF problem, if so I'll dig out a reference. Hugh At 03:13 AM 1/9/2007, you wrote: >Dear All, > We have got a persistent noise problem with one of our CCDs, it >takes the form along a row, of one or two bright pixels adjacent to one or >two dark pixels. The levels in the bright and dark pixels are up to 40 >counts off the bias level, (see attached images). The noise has a well >defined repetition rate that corresponds for us to approximately every 175 >pixels in the serial direction, this is roughly 300Hz. > > We don't expect anyone to provide a solution to this problem but we would >be grateful if possible sources of this form of noise could be suggested? >One theory is that the instrument is acting as an aerial and receiving a >signal from somewhere. > > Tests to try and identify the noise have included, exchanging the CCD >controller with two others (mounted on and off the instrument, a low >resolution spectrograph and imager), replacing all the cabling, switching >off everything on the instrument and on the telescope, but the noise >remains. We even get the noise when the instrument is off the telescope >sitting on its trolley, which has rubber wheels, and only powering the CCD >controller. Disconnecting the mains earth has also been tried. > > Regards, > Graham Cox > >-- >Graham C. Cox >Nordic Optical Telescope Tel +34 922 425468 >Apartado 474 Fax +34 922 425475 >E-38700 Santa Cruz de La Palma http://www.not.iac.es >Canarias, Spain Email cox at not.iac.es > > > > > >-- CCD-world -- >CCD-world is fully moderated. Send posts to CCD-world at ctio.noao.edu >Standard replies will go to the list; address personal replies manually. >For more information, please go to: >http://www.ctio.noao.edu/mailman/listinfo/ccd-world From jean-luc.gach at oamp.fr Tue Jan 9 17:23:11 2007 From: jean-luc.gach at oamp.fr (GACH jean-luc) Date: Tue, 9 Jan 2007 21:23:11 +0100 Subject: CCD-world: RE : 850nm vs. 1310nm optical transceivers In-Reply-To: <45A3CEF5.1050008@eso.org> Message-ID: <002b01c7342b$fc6a2000$3201a8c0@portablejlg> Hi Javier, First of all, I wish yo a happy new year. We used in marseille 850nm trancievers (Avago HFBR53D5), they worked fine at 1.5 Gb/s over more than 300m. Reaching 500m requires to use 125/50um fibers. This kind of specification is usually in the transceiver's datasheet. Cheers --------------------------- Jean-Luc GACH Instrumentation engineer Universit? de Provence Observatoire de Marseille 2 place Le verrier 13248 Marseille cedex 4 phone : +33 (0) 4 95 04 4119 fax : +33 (0) 4 91 62 1190 http://www-obs.cnrs-mrs.fr/interferometrie/interferometrie.html -----Message d'origine----- De : ccd-world-bounces at ctio.noao.edu [mailto:ccd-world-bounces at ctio.noao.edu] De la part de Javier Reyes Envoy? : mardi 9 janvier 2007 18:21 ? : ccd-world at ctio.noao.edu Objet : CCD-world: 850nm vs. 1310nm optical transceivers Hi folks, As you might already know, we are at ESO developing a new detector controller called NGC. NGC front-end electronics will communicate to the back-end computer using a 2.5Gbps optical link. For this link we are currently using 1310nm transceivers and single-mode fibers to fulfill a transmission distance of about 500m. For several reasons we want to use 850nm transceivers instead and need to know whether we can reach this distance at this bitrate with single- or multi-mode fibers. Does any of you have ever used 850nm at 2.5Gbps and over 500m fiber? Cheers, Javier -- ----------------------------------------------------------------- Javier Reyes European Southern Observatory ESO Instrumentation Division Karl Schwarzschildstr. 2 Optical Detector Laboratory 85748 Garching bei M?nchen Phone: +49-89-32006-384/520 Germany Fax: +49-89-32006-530 E-mail: jreyes at eso.org -- CCD-world -- CCD-world is fully moderated. Send posts to CCD-world at ctio.noao.edu Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.ctio.noao.edu/mailman/listinfo/ccd-world From caa at ifa.hawaii.edu Tue Jan 9 17:00:30 2007 From: caa at ifa.hawaii.edu (Colin Aspin) Date: Tue, 9 Jan 2007 10:00:30 -1000 Subject: CCD-world: persistent noise problem In-Reply-To: References: Message-ID: <9E8FB582-192D-45EC-8E80-BEDB2DC6EC88@ifa.hawaii.edu> Hi Graham, Please let us all know which of the excellent suggestions leads to a solution of your noise problem! Also, I asked the group some time ago if anyone had a Tek 2K 24um pixel array they are not using any more. We have one in a camera that the Faculty really love to use (monolithic, easy to process the data etc) and so I'd like to obtain a 'backup' CCD in case anything ever happened to the current science grade. Anyone got one they could part with? aloha, Colin Aspin -- Colin Aspin UH Telescopes Manager Institute for Astronomy University of Hawaii 640 N Aohoku Place Hilo, HI 96720 (808) 932-2392 (office) (808) 960-5089 (cell) On Jan 9, 2007, at 1:13 AM, Graham C. Cox wrote: > Dear All, > We have got a persistent noise problem with one of our > CCDs, it > takes the form along a row, of one or two bright pixels adjacent to > one or > two dark pixels. The levels in the bright and dark pixels are up to 40 > counts off the bias level, (see attached images). The noise has a well > defined repetition rate that corresponds for us to approximately > every 175 > pixels in the serial direction, this is roughly 300Hz. > > We don't expect anyone to provide a solution to this problem but > we would > be grateful if possible sources of this form of noise could be > suggested? > One theory is that the instrument is acting as an aerial and > receiving a > signal from somewhere. > > Tests to try and identify the noise have included, exchanging the CCD > controller with two others (mounted on and off the instrument, a low > resolution spectrograph and imager), replacing all the cabling, > switching > off everything on the instrument and on the telescope, but the noise > remains. We even get the noise when the instrument is off the > telescope > sitting on its trolley, which has rubber wheels, and only powering > the CCD > controller. Disconnecting the mains earth has also been tried. > > Regards, > Graham Cox > > -- > Graham C. Cox > Nordic Optical Telescope Tel +34 922 425468 > Apartado 474 Fax +34 922 425475 > E-38700 Santa Cruz de La Palma http:// > www.not.iac.es > Canarias, Spain Email cox at not.iac.es > > > > > -- CCD-world -- > CCD-world is fully moderated. Send posts to CCD-world at ctio.noao.edu > Standard replies will go to the list; address personal replies > manually. > For more information, please go to: http://www.ctio.noao.edu/ > mailman/listinfo/ccd-world From davidcorzo at hotmail.com Wed Jan 10 13:07:54 2007 From: davidcorzo at hotmail.com (David) Date: Wed, 10 Jan 2007 10:07:54 -0600 Subject: CCD-world: LED wavelenght temperature variations? Message-ID: Hi I had a discussion about the fact "how the enviroment temperature afect to led light" Is this true????????? Can the heat modified the color temperature on a led radiation? or the wavelenght? in a factor of what? degrees? tenth of degrees? Thanks in advance for the aswer or answers? David Corzo -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070110/514359d4/attachment.html From Paul.Jorden at e2v.com Thu Jan 11 07:53:02 2007 From: Paul.Jorden at e2v.com (Jorden, Paul) Date: Thu, 11 Jan 2007 10:53:02 -0000 Subject: CCD-world: LED wavelenght temperature variations? Message-ID: <90511C6E9D0A89419745854EACE4C7A801A5BDC9@whl46.e2v.com> David, you may find this of interest. the intensity of the LED is quite strongly temperature dependent. the technical note also refers to a spectral change with temperature http://www.ing.iac.es/Astronomy/observing/manuals/ps/tech_notes/tn107.pdf I'm sure google will find references to the spectral shift with temperature Paul -----Original Message----- From: David [mailto:davidcorzo at hotmail.com] Sent: 10 January 2007 16:08 To: ccd-world at ctio.noao.edu Subject: CCD-world: LED wavelenght temperature variations? Hi I had a discussion about the fact "how the enviroment temperature afect to led light" Is this true????????? Can the heat modified the color temperature on a led radiation? or the wavelenght? in a factor of what? degrees? tenth of degrees? Thanks in advance for the aswer or answers? David Corzo -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070111/2d705edc/attachment.html From john.phillips at kodak.com Fri Jan 26 13:16:55 2007 From: john.phillips at kodak.com (john.phillips at kodak.com) Date: Fri, 26 Jan 2007 16:16:55 +0000 Subject: CCD-world: Job Posting - Kodak Image Sensor Solutions: European Field Applications Engineer Message-ID: Hello Tim, I would be grateful if you could post the following - it is especially poignant for me as a similar posting was instrumental in my getting my current job. Best regards, John >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hello CCD-World, We have an opening for another European field applications engineer at Kodak Image Sensor Solutions. (We have had an engineer leave the company recently.) Job Summary: Work as Field Applications Engineer for Image Sensor Solutions, manufacturer of image sensors. A fast growing, worldwide market in digital imaging is targeted, with expectations of significant growth over the coming years. The Field Applications Engineer would support bringing this technology to the customer base, including support of marketing and sales to secure new design wins and assisting in implementation at customer sites as necessary. Target markets include automotive, mobile phones, digital still cameras, industrial, medical, professional photography and scientific. Extensive travel required. Fluent in English - written and oral. Qualifications/Experience: Experience in design of CCD/CMOS sensor camera or test systems including sensor drive electronics, logic and analog, and data acquisition circuits including CDS, ADC, and frame storage interfacing. Also desirable: automotive and or mobile phone system design, working knowledge of solid state image sensors and device physics, working knowledge of eletro-optical systems design and operation, timing and data acquisition and manipulation software including C++, Labview, Altera Max Plus, etc. Willingness to work with design, product engineering, and marketing resources to achieve design wins and resolve customer implementation issues. Ideally 6 years experience & MSEE Degree or equivalent in engineering or related discipline. If this is something that appeals to you then please email your CV to marco.andreghetti at kodak.com On a personal note, I was about to (reluctantly) embark on a company relocation about four years ago when I saw a posting just like this one. I replied, was accepted, and, as they say, the rest is history. I have been very busy and found meeting with and working through problems with design engineers throughout Europe and in many different applications very stimulating and great fun. Please note that, as it says above, there is extensive travel involved which is mostly in Europe. As the post is vacant we are looking for someone as soon as possible. If you would like to contact me to discuss my experience of the job informally my details are below. Best regards, John. +++++++++++++++++++++++++++++ John Phillips European Applications Engineer Image Sensor Solutions Eastman Kodak Company john.phillips at kodak.com Office: +44 1442 8 46557 Mobile: +44 7709 482019 http://www.kodak.com/go/imagers +++++++++++++++++++++++++++++ -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070126/84226069/attachment.html From bobtek at fishcamp.com Fri Feb 2 12:59:42 2007 From: bobtek at fishcamp.com (bob piatek) Date: Fri, 2 Feb 2007 07:59:42 -0800 Subject: CCD-world: Multi-band IR sensors In-Reply-To: References: Message-ID: <2CEA6EF7-24BC-4C65-9B3D-AF378E3881ED@fishcamp.com> Hello, Does anyone have knowledge of IR sensor designs that incorporate pixel level color filters? I'm thinking of an analogous solution comparable to the Bayer Matrix color filters used to create color image sensors in the visible spectrum. I have applications in mind in both the MWIR and LWIR spectrums where I would like to be able to distinguish multiple color bands within the total available band of the sensor. Ideally, I would like to have a sensor with a repeating matrix of four or more filters across the sensor. I know of some efforts done to produce IR image sensors for the MWIR band that included an array of micro-lenses across the sensor. This was done to increase the sensitivity of the sensors. I haven't been able to find any information on IR sensors with integrated filter elements bonded to the pixels. Any info would be appreciated. Bob Piatek fishcamp engineering 105 W. Clark Ave. Orcutt, CA 93455 http://www.fishcamp.com TEL: 805-937-6365 FAX: 805-937-6252 -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070202/43bf06f9/attachment.html From rsmith at astro.caltech.edu Fri Feb 2 18:53:35 2007 From: rsmith at astro.caltech.edu (Roger Smith) Date: Fri, 2 Feb 2007 13:53:35 -0800 Subject: CCD-world: Dark current < 0.1e-/hr ? Message-ID: <7CEA83EA-45B0-4B7A-8218-C7756FDADAE2@astro.caltech.edu> Folks, We have a an application for a UV (370-400nm) sensitive CCD, where we would like to achieve better than 3e- total noise in a one hour exposure. Total noise includes read noise, dark current and spurious charge. Just to make it more interesting we need 60um square pixels. We have been looking at 4096x4096 15um pixel CCDs binned 4x4. We believe we will be able to reduce Spurious Charge by lowering the positive rails and/or taking the CCD out of inversion (slowly) prior to readout. (Our signals are very faint, obviously, so well capacity is not an issue. ) So the total noise calculation might look like this: Xbin factor 4 Ybin Factor 4 exp time 1 hr Total noise 3 e- Read noise 2.5 e- say so? dark charge 2.75 e- =Total_noise^2 - Read_noise^2 dark current 0.17 e-/hr We approached one manufacturer who believed that their customers had measured performance this good, but they were not setup to test to this spec. Rather than ask about just that case, I thought it better to state the question more generally: Can anyone can confirm measuring performance that would meet our specs? ... of course we'd be really interested to know if it was for a 60mm * 60mm CCD with high QE at 400nm. -- Roger Roger M. Smith California Institute of Technology 1200 E. California Blvd, Mail Stop 105-24 Pasadena CA 91125, USA Office: 1-626-395-8780 Fax: 1-626-568-1517 e-mail: rsmith at astro.caltech.edu -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070202/4d1bd564/attachment.html From rsmith at astro.caltech.edu Fri Feb 2 19:09:33 2007 From: rsmith at astro.caltech.edu (Roger Smith) Date: Fri, 2 Feb 2007 14:09:33 -0800 Subject: CCD-world: (no subject) Message-ID: Dear World, Yes, its me again, wearing a different hat. If a have a CCD operating in inversion but not MPP mode, and I reduce the high levels in the parallel clocks, I will see an increase in the Pixel Response Non-Uniformity. When I last looked at this (E2V 2Kx4K, in 2002) I only cared about the overall standard deviation of the pixel scale structure in the flats. I'd now like to know whether the pixel-to-pixel sensitivity variation is simply amplified or if the pattern changes? -- Roger Roger M. Smith California Institute of Technology 1200 E. California Blvd, Mail Stop 105-24 Pasadena CA 91125, USA Office: 1-626-395-8780 Fax: 1-626-568-1517 e-mail: rsmith at astro.caltech.edu -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070202/f02b7289/attachment.html From cyril.cavadore at fr.thalesgroup.com Mon Feb 5 05:52:48 2007 From: cyril.cavadore at fr.thalesgroup.com (cyril cavadore) Date: Mon, 05 Feb 2007 09:52:48 +0100 Subject: CCD-world: Sony CCD, new defective (hot) pixels that appear over time In-Reply-To: <90511C6E9D0A89419745854EACE4C7A801A5BDC9@whl46.e2v.com> References: <90511C6E9D0A89419745854EACE4C7A801A5BDC9@whl46.e2v.com> Message-ID: <45C6F060.60107@fr.thalesgroup.com> Hello all, I'm seeking for user feedback regarding CCD SONY devices. I'm much more used with E2V or Kodak CCDs :-) We are using ICX409AL (Sony EX-View HAD CCDs) that tends to develop additional hot pixels over time. We are wondering where those pixels come from. I know that scientific CCD can get additional hot pixels when exposed to harsh environment (very high elevation or space use) Sony told us that we should use the CCDs as fast as possible, and avoid long storage periods, because cosmic rays can damage them and can cause new hot pixels, they even speak about travel condition (plane and high elevation!) : this seems to me exaggerated especially when devices are stored at see level. Also people from my company said that he could come from ESD discharge (!) This explanation, I don't really believe it too much, because ESD discharge just kills CCD from my experience. I have found this explanation (by Googling this question), that seems to me more relevant (about process stabilization) : ***** "The drawback to EX-View technology is that, due to the difficult nature of the CCD chip manufacturing process and the delicate nature of the chips, there is a limited supply of the sensor elements from SONY. According to SONY, there are more latent imperfections in the photodiodes of the EX-View CCD chip compared to the Super HAD sensors. These few defective CCD elements may break down, thereby causing "dead pixels", which leave white or black spots on the image which cannot be removed. Dead pixels are known to develop whether the CCD chip is in storage or in active use. As an example, an EX-View CCD might ship from SONY's factory with only 3 dead spots but the number might increase to 5 during transportation and then perhaps grow to 7 while sitting in the camera manufacturer's warehouse and grow further to, say, 12 when installed in a CCD camera. The number of dead pixels might later grow to 15 to 30 by the time the camera is received by the end user. This process will continue until the latent defects in the photodiodes stabilize. SONY says that the growing number of dead pixel elements is caused by cosmic rays that bombard the more vulnerable junctions of some of the photodiodes in the CCD array." ***** Full text here : http://www.mintron.com/HTM/Q&A/Htm/EX-View%20CCD%20camera.htm If people here have some feedback about this issue, I will be very grateful. Regards, C.Cavadore -------------- next part -------------- A non-text attachment was scrubbed... Name: cyril.cavadore.vcf Type: text/x-vcard Size: 396 bytes Desc: not available Url : http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070205/2c45807d/attachment.vcf From Albert.Theuwissen at dalsa.com Mon Feb 5 13:15:41 2007 From: Albert.Theuwissen at dalsa.com (Albert.Theuwissen at dalsa.com) Date: Mon, 5 Feb 2007 17:15:41 +0100 Subject: CCD-world: Sony CCD, new defective (hot) pixels that appear over time Message-ID: Hello everyone, I did some interesting experiments about new hot pixels, and reported about that at IEDM 2005. See attachment. Kind regards, Albert. prof. dr. ir. Albert J.P. THEUWISSEN office +31-40-274-2734 fax +31-40-274-4090 mob. +31-65-345-2707 albert.theuwissen at dalsa.com The information contained here is DALSA company confidential and intended only for the individuals to whom it is addressed. This message contains confidential information and shall not be exchanged between the addressed person and any other third party. Any review, transmission, dissemination or other use of this information is prohibited. If you received this in error, please contact the sender and delete the material from any computer. cyril cavadore Sent by: ccd-world-bounces at ctio.noao.edu 05/02/2007 09:52 Please respond to Optical & SWIR imager development for professional astronomy To: Optical & SWIR imager development for professional astronomy cc: Subject: CCD-world: Sony CCD, new defective (hot) pixels that appear over time Hello all, I'm seeking for user feedback regarding CCD SONY devices. I'm much more used with E2V or Kodak CCDs :-) We are using ICX409AL (Sony EX-View HAD CCDs) that tends to develop additional hot pixels over time. We are wondering where those pixels come from. I know that scientific CCD can get additional hot pixels when exposed to harsh environment (very high elevation or space use) Sony told us that we should use the CCDs as fast as possible, and avoid long storage periods, because cosmic rays can damage them and can cause new hot pixels, they even speak about travel condition (plane and high elevation!) : this seems to me exaggerated especially when devices are stored at see level. Also people from my company said that he could come from ESD discharge (!) This explanation, I don't really believe it too much, because ESD discharge just kills CCD from my experience. I have found this explanation (by Googling this question), that seems to me more relevant (about process stabilization) : ***** "The drawback to EX-View technology is that, due to the difficult nature of the CCD chip manufacturing process and the delicate nature of the chips, there is a limited supply of the sensor elements from SONY. According to SONY, there are more latent imperfections in the photodiodes of the EX-View CCD chip compared to the Super HAD sensors. These few defective CCD elements may break down, thereby causing "dead pixels", which leave white or black spots on the image which cannot be removed. Dead pixels are known to develop whether the CCD chip is in storage or in active use. As an example, an EX-View CCD might ship from SONY's factory with only 3 dead spots but the number might increase to 5 during transportation and then perhaps grow to 7 while sitting in the camera manufacturer's warehouse and grow further to, say, 12 when installed in a CCD camera. The number of dead pixels might later grow to 15 to 30 by the time the camera is received by the end user. This process will continue until the latent defects in the photodiodes stabilize. SONY says that the growing number of dead pixel elements is caused by cosmic rays that bombard the more vulnerable junctions of some of the photodiodes in the CCD array." ***** Full text here : http://www.mintron.com/HTM/Q&A/Htm/EX-View%20CCD%20camera.htm If people here have some feedback about this issue, I will be very grateful. Regards, C.Cavadore -- CCD-world -- CCD-world is fully moderated. Send posts to CCD-world at ctio.noao.edu Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.ctio.noao.edu/mailman/listinfo/ccd-world ********************************************************************** To help combat SPAM DALSA will no longer return delivery failure notifications for incorrect or invalid addresses. This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This email message has also been swept for the presence of computer viruses Please note that DALSA employee addresses have been standardized to dalsa.com-- Please update your address book as may be required ********************************************************************** -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070205/12094fef/attachment.html -------------- next part -------------- A non-text attachment was scrubbed... Name: cyril.cavadore.vcf Type: application/octet-stream Size: 411 bytes Desc: not available Url : http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070205/12094fef/attachment.obj -------------- next part -------------- A non-text attachment was scrubbed... Name: s33p6.doc Type: application/octet-stream Size: 115712 bytes Desc: not available Url : http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070205/12094fef/attachment-0001.obj From deg at lbl.gov Mon Feb 5 16:50:03 2007 From: deg at lbl.gov (Don Groom) Date: Mon, 5 Feb 2007 11:50:03 -0800 (PST) Subject: CCD-world: Sony CCD - high-altitude cosmic ray effects In-Reply-To: <45C6F060.60107@fr.thalesgroup.com> References: <90511C6E9D0A89419745854EACE4C7A801A5BDC9@whl46.e2v.com> <45C6F060.60107@fr.thalesgroup.com> Message-ID: Perhaps I can help a little on the high-altitude cosmic ray business, dodging the rest of the problems with the Sony CCD's. Buried in a footnote on p 90 in my SDW2003 (?; anyhow, Hawaii) paper is a rather incomplete reference to our experiments to address the worry that flying the dewar + CCD to Hawaii radioactivated something or another. The materials in the CCD, substrate, etc, as for the table on p 91, got a clean bill of health in assays, and are thought to be unlikely to be cosmogenically activated very much. The stainless was a different matter. Richard Stover looked up the recipe for the stainless in the dewar. We obtained 7kg of the material in the form of 1/2 " plates, stacked in a smallish package. This was characterized at the LBNL low-level facility about 180 m underground, in a "clean" lead cave, by Al Smith. Then, as fast as we could, I sent it via FedEx overnight delivery to a friend at MIT, who sent it back the same day. I received it and sent it back to him on the same day; we were held up by a weekend on his returning it again. It was then immediately characterized in Al Smith's lab. A very small amount of cosmogenic activation was found (seven isotopes) whose total count rate was about .015 decays/m/kg. We don't know if the flights were nonstop, but at minimum the steel was at 35,000 ft or so for more than 20 hours. The conclusion was that there was "no problem." There is certainly a higher neutron + proton flux at these altitudes; see fig 24.3 in the cosmic ray review at http://pdg.lbl.gov/2006/reviews/contents_sports.html#astroetc --but they seem to cause little problem, or so we presently understand. Muons are a different matter; these minimum-ionizing particles go through everything and the flux is definitely greater at mountain observatory altitudes. Don |-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+| Don Groom (Particle Data Group, SNAP CCD Project) DEGroom(at)lbl(dot)gov www-ccd.lbl.gov 510/486-6788 FAX: 510/486-4799 Analog: 50R6008//1 Cyclotron Road//Berkeley Lab//Berkeley, CA 94720-8166 From veillet at cfht.hawaii.edu Mon Feb 5 17:34:00 2007 From: veillet at cfht.hawaii.edu (Christian Veillet) Date: Mon, 05 Feb 2007 10:34:00 -1000 Subject: CCD-world: Last chance to acquire CFH12K! Message-ID: <45C794B8.6030102@cfht.hawaii.edu> Before dismantling it, CFHT is offering for sale CFH12K, its wide-field 12Kx8K mosaic camera, as a complete system (camera, filter wheel, shutter, pc-host, and acquisition software). When replaced with MegaCam in 2003, CFH12K was an excellent camera. It was just not big enough for the CFHT users... You can go to the ADS web site http://adsabs.harvard.edu/abstract_service.html and search all papers with "CFH12K" as an Abstract Word. Already two papers with CFH12K data in 2007! Details on the camera can be found here: http://www.cfht.hawaii.edu/Instruments/Imaging/CFH12K/ If you are interested, let's talk! Aloha, Christian -- Dr Christian Veillet Executive Director Canada-France-Hawaii Telescope http://www.cfht.hawaii.edu/ From cyril.cavadore at fr.thalesgroup.com Tue Feb 6 07:35:29 2007 From: cyril.cavadore at fr.thalesgroup.com (cyril cavadore) Date: Tue, 06 Feb 2007 11:35:29 +0100 Subject: CCD-world: Sony CCD - high-altitude cosmic ray effects In-Reply-To: References: <90511C6E9D0A89419745854EACE4C7A801A5BDC9@whl46.e2v.com> <45C6F060.60107@fr.thalesgroup.com> Message-ID: <45C859F1.6010108@fr.thalesgroup.com> Hello all, Just to be sure that we are all on the same wavelength, my previous message was related to permanent damages that lead to have an increased number of hot pixels. Also, I have no way to cool down the device (this one operates at almost 35?C). The Theuwissen's paper (thanks for sending it!) seems to be inline with Sony's statements. Nevertheless, I'm surprised that little devices such as ICX409AL (640x480pixels) 6mm diagonal have this behavior. Let's say you build a camera in a given place, then you ship it oversea and the "customer" get it with additional hot pixels (!). Of course, if those pixels are software corrected in real time (including real time hot pixel detection), this is not a problem, in the other case, this is a nightmare. From Kodak device, I've never heard about this kind of issues... so I fear that Sony tries to get rid of manufacturing problem by shifting the problem to cosmic rays. A test of devices in Tokyo and afterward shipped by plane, and once delivered in Europe would tell the truth. Cyril Don Groom a ?crit : >Perhaps I can help a little on the high-altitude cosmic ray business, >dodging the rest of the problems with the Sony CCD's. > >Buried in a footnote on p 90 in my SDW2003 (?; anyhow, Hawaii) paper >is a rather incomplete reference to our experiments to address the worry >that flying the dewar + CCD to Hawaii radioactivated something or another. >The materials in the CCD, substrate, etc, as for the table on p 91, got a >clean bill of health in assays, and are thought to be unlikely to be >cosmogenically activated very much. The stainless was a different matter. > >Richard Stover looked up the recipe for the stainless in the dewar. We >obtained 7kg of the material in the form of 1/2 " plates, stacked in a >smallish package. This was characterized at the LBNL low-level facility >about 180 m underground, in a "clean" lead cave, by Al Smith. Then, as >fast as we could, I sent it via FedEx overnight delivery to a friend at >MIT, who sent it back the same day. I received it and sent it back to him >on the same day; we were held up by a weekend on his returning it again. >It was then immediately characterized in Al Smith's lab. A very small >amount of cosmogenic activation was found (seven isotopes) whose total >count rate was about .015 decays/m/kg. We don't know if the flights were >nonstop, but at minimum the steel was at 35,000 ft or so for more than 20 >hours. The conclusion was that there was "no problem." > >There is certainly a higher neutron + proton flux at these altitudes; >see fig 24.3 in the cosmic ray review at >http://pdg.lbl.gov/2006/reviews/contents_sports.html#astroetc >--but they seem to cause little problem, or so we presently understand. >Muons are a different matter; these minimum-ionizing particles go through >everything and the flux is definitely greater at mountain observatory >altitudes. > >Don > >|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+| >Don Groom (Particle Data Group, SNAP CCD Project) >DEGroom(at)lbl(dot)gov www-ccd.lbl.gov 510/486-6788 FAX: 510/486-4799 >Analog: 50R6008//1 Cyclotron Road//Berkeley Lab//Berkeley, CA 94720-8166 > >-- CCD-world -- >CCD-world is fully moderated. Send posts to CCD-world at ctio.noao.edu >Standard replies will go to the list; address personal replies manually. >For more information, please go to: http://www.ctio.noao.edu/mailman/listinfo/ccd-world > > -------------- next part -------------- A non-text attachment was scrubbed... Name: cyril.cavadore.vcf Type: text/x-vcard Size: 396 bytes Desc: not available Url : http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070206/30961164/attachment.vcf From Albert.Theuwissen at dalsa.com Tue Feb 6 09:47:12 2007 From: Albert.Theuwissen at dalsa.com (Albert.Theuwissen at dalsa.com) Date: Tue, 6 Feb 2007 13:47:12 +0100 Subject: CCD-world: Sony CCD - high-altitude cosmic ray effects Message-ID: Hello, Cyril wrote the following : A test of devices in Tokyo and afterward shipped by plane, and once delivered in Europe would tell the truth. My answer : that is exactly what I did in my experiments ! To tell you the truth : this is not something that Sony tries to hide, this is an overall silicon issue ! You see these effects in CMOS imagers (if the overall dark current is low enough), in CCD imagers, in Sony devices, in Philips devices, in Panasonic devices, .... you name them. I do have material available of Sony devices, of Sharp imagers, of Toshiba imagers and of Panasonic imagers. THEY ALL BEHAVE THE SAME !!! So Kodak devices will perform in the same way ! And not only imagers are suffering from these effects, also DRAMs, etc. Boeiing together with IBM did a lot of experiments on these effects, which are published in 1995 (?) in the IBM Disclosure Journals (look after the author Ziegler). Maybe one last suggestion : please visit http://www.l2mp.fr/astep/ here exactly the same experiments are being done as what I did with my imagers. Kind regards, Albert. prof. dr. ir. Albert J.P. THEUWISSEN office +31-40-274-2734 fax +31-40-274-4090 mob. +31-65-345-2707 albert.theuwissen at dalsa.com The information contained here is DALSA company confidential and intended only for the individuals to whom it is addressed. This message contains confidential information and shall not be exchanged between the addressed person and any other third party. Any review, transmission, dissemination or other use of this information is prohibited. If you received this in error, please contact the sender and delete the material from any computer. cyril cavadore Sent by: ccd-world-bounces at ctio.noao.edu 06/02/2007 11:35 Please respond to Optical & SWIR imager development for professional astronomy To: Optical & SWIR imager development for professional astronomy cc: Subject: Re: CCD-world: Sony CCD - high-altitude cosmic ray effects Hello all, Just to be sure that we are all on the same wavelength, my previous message was related to permanent damages that lead to have an increased number of hot pixels. Also, I have no way to cool down the device (this one operates at almost 35?C). The Theuwissen's paper (thanks for sending it!) seems to be inline with Sony's statements. Nevertheless, I'm surprised that little devices such as ICX409AL (640x480pixels) 6mm diagonal have this behavior. Let's say you build a camera in a given place, then you ship it oversea and the "customer" get it with additional hot pixels (!). Of course, if those pixels are software corrected in real time (including real time hot pixel detection), this is not a problem, in the other case, this is a nightmare. From Kodak device, I've never heard about this kind of issues... so I fear that Sony tries to get rid of manufacturing problem by shifting the problem to cosmic rays. A test of devices in Tokyo and afterward shipped by plane, and once delivered in Europe would tell the truth. Cyril Don Groom a ?crit : >Perhaps I can help a little on the high-altitude cosmic ray business, >dodging the rest of the problems with the Sony CCD's. > >Buried in a footnote on p 90 in my SDW2003 (?; anyhow, Hawaii) paper >is a rather incomplete reference to our experiments to address the worry >that flying the dewar + CCD to Hawaii radioactivated something or another. >The materials in the CCD, substrate, etc, as for the table on p 91, got a >clean bill of health in assays, and are thought to be unlikely to be >cosmogenically activated very much. The stainless was a different matter. > >Richard Stover looked up the recipe for the stainless in the dewar. We >obtained 7kg of the material in the form of 1/2 " plates, stacked in a >smallish package. This was characterized at the LBNL low-level facility >about 180 m underground, in a "clean" lead cave, by Al Smith. Then, as >fast as we could, I sent it via FedEx overnight delivery to a friend at >MIT, who sent it back the same day. I received it and sent it back to him >on the same day; we were held up by a weekend on his returning it again. >It was then immediately characterized in Al Smith's lab. A very small >amount of cosmogenic activation was found (seven isotopes) whose total >count rate was about .015 decays/m/kg. We don't know if the flights were >nonstop, but at minimum the steel was at 35,000 ft or so for more than 20 >hours. The conclusion was that there was "no problem." > >There is certainly a higher neutron + proton flux at these altitudes; >see fig 24.3 in the cosmic ray review at >http://pdg.lbl.gov/2006/reviews/contents_sports.html#astroetc >--but they seem to cause little problem, or so we presently understand. >Muons are a different matter; these minimum-ionizing particles go through >everything and the flux is definitely greater at mountain observatory >altitudes. > >Don > >|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+|-+| >Don Groom (Particle Data Group, SNAP CCD Project) >DEGroom(at)lbl(dot)gov www-ccd.lbl.gov 510/486-6788 FAX: 510/486-4799 >Analog: 50R6008//1 Cyclotron Road//Berkeley Lab//Berkeley, CA 94720-8166 > >-- CCD-world -- >CCD-world is fully moderated. Send posts to CCD-world at ctio.noao.edu >Standard replies will go to the list; address personal replies manually. >For more information, please go to: http://www.ctio.noao.edu/mailman/listinfo/ccd-world > > -- CCD-world -- CCD-world is fully moderated. Send posts to CCD-world at ctio.noao.edu Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.ctio.noao.edu/mailman/listinfo/ccd-world ********************************************************************** To help combat SPAM DALSA will no longer return delivery failure notifications for incorrect or invalid addresses. This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This email message has also been swept for the presence of computer viruses Please note that DALSA employee addresses have been standardized to dalsa.com-- Please update your address book as may be required ********************************************************************** -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070206/ebf5b1b6/attachment.html -------------- next part -------------- A non-text attachment was scrubbed... Name: cyril.cavadore.vcf Type: application/octet-stream Size: 411 bytes Desc: not available Url : http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070206/ebf5b1b6/attachment.obj From mark at apo.nmsu.edu Fri Feb 9 19:13:51 2007 From: mark at apo.nmsu.edu (Mark Klaene) Date: Fri, 9 Feb 2007 15:13:51 -0700 Subject: CCD-world: Job Posting Message-ID: Position Announcements: ELECTRONICS ENGINEER Apache Point Observtaory/New Mexico State University is seeking an Electronics Engineer, who will have the on-site responsibility for the performance, maintenance, and upgrading of the existing and future scientific instrumentation associated with the astronomical telescopes at Apache Point Observatory, near Sunspot, New Mexico. Minimum requirements for the position include a BSEE degree or equivalent plus at least five years of applicable professional experience, including substantial involvement in the design and construction of optical and near-IR detector systems. APO is owned and operated by the Astrophysical Research Consortium, of which NMSU is the member institution that oversees observatory operations. The principal APO facilities are the ARC 3.5-meter and 2.5-meter Sloan Digital Sky Survey telescopes. Scientific instrumentation at the site includes visible and near-infrared CCD cameras and grating spectrographs; future instrument development is planned. Applicants should have a history that demonstrates creativity and current hands-on knowledge (including design, implementation, and testing experience) in several technical areas including: * design, construction, and commissioning of visible-light and near-IR CCDs and other electronics associated with astronomical camera and spectrograph systems; * general electronic and opto-mechanical design, fabrication, and troubleshooting; * microprocessor control and data acquisition hardware and software; * cryogenic and vacuum dewar systems; * engineering documentation; * systems-level trouble-shooting and problem analysis. The successful applicant will possess good communication skills, be able to work effectively both independently and with astronomers and other technical support staff, display initiative and reliability with minimal supervisory direction, show responsibility for the safe and proper use of observatory equipment, and prepare and update engineering and user documentation. The ability to plan projects, budgets, evaluate make vs. buy decisions, and occasionally direct the work of other staff and engineering contractors is also desirable. Submit application letter and r?sum? (naming 3 references) to the address below-electronic submissions will not be accepted. The position will remain open until filled. Employment will be contingent upon funding and eligibility for employment in U.S. NMSU is an EEO/AA employer. -- Mark Klaene Deputy Site Manager voice: 505 437 6822 PO Box 59 fax: 505 434 5555 2001 Apache Point Rd Sunspot NM 88349-0059 web: www.apo.nmsu.edu -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070209/10810cfb/attachment.html From Venkatraman.Iyer at kla-tencor.com Mon Feb 12 19:22:21 2007 From: Venkatraman.Iyer at kla-tencor.com (Iyer, Venkatraman) Date: Mon, 12 Feb 2007 14:22:21 -0800 Subject: CCD-world: 13 nm EUV detector technology Message-ID: <321D44776C348447B1440547A77C2F6802DBBBB8@CA1EXCLV03.adcorp.kla-tencor.com> HI all, Can anyone point me to references about 13nm EUV CCD technology? I am interested in * QE, QY of Silicon at 13 nm * interaction details with Si/SiO2 including damage studies * any vendors that actively supply sensors/ cameras and have experience in this area thanks, Venkat -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070212/8fb91d6c/attachment.html From Peter.Pool at e2v.com Wed Feb 21 12:00:49 2007 From: Peter.Pool at e2v.com (Pool, Peter) Date: Wed, 21 Feb 2007 15:00:49 -0000 Subject: CCD-world: 13 nm EUV detector technology Message-ID: <90511C6E9D0A89419745854EACE4C7A801D578B7@whl46.e2v.com> Hi, Here at e2v, we make back-illuminated CCDs which perform at 13nm. May I refer you to Bob Stern at Lockheed Martin ( stern at sag.lmsal.com ) who made measurements in support of the Solar X-ray Imager instrument on the GOES satellite. Bob also confirmed QE stability after extended exposure. Best regards Peter Pool CCD Chief Engineer e2v technologies -----Original Message----- From: Iyer, Venkatraman [mailto:Venkatraman.Iyer at kla-tencor.com] Sent: 12 February 2007 22:22 To: CCD-world at ctio.noao.edu Subject: CCD-world: 13 nm EUV detector technology HI all, Can anyone point me to references about 13nm EUV CCD technology? I am interested in * QE, QY of Silicon at 13 nm * interaction details with Si/SiO2 including damage studies * any vendors that actively supply sensors/ cameras and have experience in this area thanks, Venkat -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070221/7777a229/attachment.html -------------- next part -------------- A non-text attachment was scrubbed... Name: QE - BobStern.ppt Type: application/vnd.ms-powerpoint Size: 194560 bytes Desc: not available Url : http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070221/7777a229/attachment.ppt From stern at lmsal.com Wed Feb 21 14:04:46 2007 From: stern at lmsal.com (Robert Stern) Date: Wed, 21 Feb 2007 09:04:46 -0800 Subject: CCD-world: EUV CCD Message-ID: <45DC7BAE.6020404@lmsal.com> Hi, Re Peter Pool's message: reference is: Stern et al., 2004, SPIE Proc. 5171, p. 77 link to SPIE DIgital Library: http://spiedl.aip.org/vsearch/servlet/VerityServlet?KEY=SPIEDL&smode=strresults&sort=rel&maxdisp=25&threshold=0&pjournals=SPIEDL&possible1=stern&possible1zone=article&SMODE=strsearch&OUTLOG=NO&deliveryType=spiedl&viewabs=PSISDG&key=DISPLAY&docID=6&page=0&chapter=0 SPIE Digital Library Search Results : Abstract View Bob Stern LMSAL P.S. please use stern at lmsal.com (old link to stern at sag.lmsal.com will disappear at some point) > Hi, > > Here at e2v, we make back-illuminated CCDs which perform at 13nm. > > May I refer you to Bob Stern at Lockheed Martin ( > stern at sag.lmsal.com ) who made measurements in > support of the Solar X-ray Imager instrument on the GOES satellite. Bob > also confirmed QE stability after extended exposure. > > Best regards > > Peter Pool > CCD Chief Engineer > e2v technologies > > -----Original Message----- > From: Iyer, Venkatraman [mailto:Venkatraman.Iyer at kla-tencor.com] > Sent: 12 February 2007 22:22 > To: CCD-world at ctio.noao.edu > Subject: CCD-world: 13 nm EUV detector technology > > > > HI all, > > Can anyone point me to references about 13nm EUV CCD technology? > I am interested in > > > * QE, QY of Silicon at 13 nm > > * interaction details with Si/SiO2 including damage studies > > * any vendors that actively supply sensors/ cameras and have > experience in this area > > > thanks, > > Venkat > > > > -- Robert Stern Lockheed Martin ADBS (L9-41) Solar and Astrophysics Lab Bldg. 252 Phone: (650) 424-3272 3251 Hanover Street Fax: (650) 424-3994 Palo Alto CA 94304 From ebakker at mro.nmt.edu Wed Feb 21 17:29:36 2007 From: ebakker at mro.nmt.edu (Eric J. Bakker) Date: Wed, 21 Feb 2007 13:29:36 -0700 Subject: CCD-world: vacancy: postdoctoral instrument specialist (detector specialist) Message-ID: <003a01c755f7$024c33e0$6664a8c0@Viking> See also: http://www.mro.nmt.edu/Employment/instrument_scientist.php (Postdoctoral) Instrument Scientist The Magdalena Ridge Observatory Interferometer near Socorro, NM, USA has an immediate opening for a postdoctoral instrument scientist. MROI is an ambitious project to design, build and operate a 10 element optical interferometer for astronomical research. It is the only interferometer designed for faint source imaging using optical interferometry. Start of operations of the interferometer is expected for 2010. The interferometer is a consortium effort, which includes New Mexico Tech and the University of Cambridge (UK). The observatory is located in the mountains about an hour drive from Socorro. Socorro is a university oriented town close to the metropolitan city of Albuquerque. The observatory has a staff of about 30 and is expected to hire more scientists and engineers in the next years. The instrument scientist has the following responsibilities: :: Participate in the procurement of the infrared arrays and the associated electronics :: Design, develop, and commission the cryogenic housing for the infrared arrays :: Optimize the near-infrared detectors for use in the fringe tracking and science instruments :: Participate in the overall design, development, and commissioning of the MRO interferometer. Minimum qualifications: Ph.D degree in physics, astronomy, engineering, or related field. The candidate must demonstrate a proven ability to develop and operate cryogenic infrared arrays. They should demonstrate the interpersonal skills that are needed for working in a team environment. They must also have excellent presentational and written communications skills. Desired qualifications: The ideal candidate should demonstrate a proven ability to write scientific and/or technical articles in recognized journals. Salary depends on experience and is negotiable. This is a fixed term position, with competitive salary, benefits and relocation allowance. To apply, submit cover letter, resume, statement of research interest, and names of 3 references to Dr. Eric J. Bakker. Review of candidates starts on April 15, 2007 and continues until a suitable candidate has been identified. All applications will be handled confidential. -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070221/bc69c8e0/attachment.html From rsmith at astro.caltech.edu Thu Feb 22 01:01:16 2007 From: rsmith at astro.caltech.edu (Roger Smith) Date: Wed, 21 Feb 2007 20:01:16 -0800 Subject: CCD-world: LED flux non-linearity Message-ID: CCD-world, This is not about detectors but the light sources used to test them. We have several infrared LEDs inside a dark chamber illuminating a 1.7um cutoff HgCdTe detector. The tests in progress require low continuous illumination (no pulsing allowed). We have an ND3 filter between the 1650nm Hamamatsu LED and the detector but still have to operate in the 10-200uA range. The LED current is precision regulated and the LED (case) temperature is servo controlled. The Lakeshore controller reading and RTD shows 1mK rms variation about 120K. So I was expecting flux to depend linearly on current until junction heating set in and caused an efficiency loss. This is what one sees in data sheets but they don't address the range of current and operating temperature involved here. At our low current you don't expect self heating to be significant, so I was expecting a linear relationship. What we see is the opposite: flux scales as current to the to power of 1.5. I am surprised to say the least. Since we are in an odd part of parameter space: low current, 120K, and 1650nm, my initial search has been unproductive, so I wonder if anyone in CCD World can point me to the explanation. -- Roger -------------- next part -------------- A non-text attachment was scrubbed... Name: unknown.png Type: image/png Size: 33414 bytes Desc: not available Url : http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070221/2922cd28/attachment.png -------------- next part -------------- From tg.burke at ngc.com Thu Feb 22 13:13:34 2007 From: tg.burke at ngc.com (Burke, Thomas G.) Date: Thu, 22 Feb 2007 11:13:34 -0500 Subject: CCD-world: LED flux non-linearity Message-ID: I'm not sitting near any references, right now, but it sounds like you're down around the region where the thing is just coming on. IIRC, LED's act similarly in the optical domain as the I/V relationship (eg exponential) - they really aren't linear (again, IIRC)n but the part of the curve that is considered normal operation is awfully close. ----------------------- I am not at my desk, but can be reached at 443-603-7308 -----Original Message----- From: ccd-world-bounces at ctio.noao.edu To: Optical & SWIR imager development for professional astronomy Sent: Wed Feb 21 23:01:16 2007 Subject: CCD-world: LED flux non-linearity CCD-world, This is not about detectors but the light sources used to test them. We have several infrared LEDs inside a dark chamber illuminating a 1.7um cutoff HgCdTe detector. The tests in progress require low continuous illumination (no pulsing allowed). We have an ND3 filter between the 1650nm Hamamatsu LED and the detector but still have to operate in the 10-200uA range. The LED current is precision regulated and the LED (case) temperature is servo controlled. The Lakeshore controller reading and RTD shows 1mK rms variation about 120K. So I was expecting flux to depend linearly on current until junction heating set in and caused an efficiency loss. This is what one sees in data sheets but they don't address the range of current and operating temperature involved here. At our low current you don't expect self heating to be significant, so I was expecting a linear relationship. What we see is the opposite: flux scales as current to the to power of 1.5. I am surprised to say the least. Since we are in an odd part of parameter space: low current, 120K, and 1650nm, my initial search has been unproductive, so I wonder if anyone in CCD World can point me to the explanation. -- Roger From CMOSCCD at aol.com Thu Feb 22 13:13:08 2007 From: CMOSCCD at aol.com (CMOSCCD at aol.com) Date: Thu, 22 Feb 2007 11:13:08 EST Subject: CCD-world: LED flux non-linearity Message-ID: Roger, Does SZE help. . . specifically Fig. 41 in LED chapter.. . where nonlinearity exists for low currents?.. . referred to as threshold current density. Have you tried increasing the current to see if behavior is linear ? Like you say. . 200 uA isn't much. Jim In a message dated 2/22/2007 7:35:57 A.M. Pacific Standard Time, rsmith at astro.caltech.edu writes: CCD-world, This is not about detectors but the light sources used to test them. We have several infrared LEDs inside a dark chamber illuminating a 1.7um cutoff HgCdTe detector. The tests in progress require low continuous illumination (no pulsing allowed). We have an ND3 filter between the 1650nm Hamamatsu LED and the detector but still have to operate in the 10-200uA range. The LED current is precision regulated and the LED (case) temperature is servo controlled. The Lakeshore controller reading and RTD shows 1mK rms variation about 120K. So I was expecting flux to depend linearly on current until junction heating set in and caused an efficiency loss. This is what one sees in data sheets but they don't address the range of current and operating temperature involved here. At our low current you don't expect self heating to be significant, so I was expecting a linear relationship. What we see is the opposite: flux scales as current to the to power of 1.5. I am surprised to say the least. Since we are in an odd part of parameter space: low current, 120K, and 1650nm, my initial search has been unproductive, so I wonder if anyone in CCD World can point me to the explanation. -- Roger


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AOL now offers free email to everyone. Find out more about what's free from AOL at http://www.aol.com. -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070222/1a45da20/attachment.html From dbaade at eso.org Fri Mar 2 11:19:41 2007 From: dbaade at eso.org (Dietrich Baade) Date: Fri, 02 Mar 2007 15:19:41 +0100 Subject: CCD-world: detector workshop in 2009 In-Reply-To: References: <4579CDD4.8050201@charter.net> Message-ID: <45E8327D.5010809@eso.org> Dear Colleagues, One and a half years have already elapsed since the 2005 detector workshop in beautiful Taormina, and its time to think about the next one! Therefore, we are happy to announce that the next detector workshop will be organized by ESO. It will be held at a nice place in the German state of Bavaria in the surroundings of Munich. In order to avoid too much stress on travel budgets and personal schedules, we will stretch the inter-workshop time interval from 3 to 4 years, because in 2008 there will be another SPIE conference. We hope to welcome you in September or October 2009. Further details will be provided in due course, using the same communication channels. In the meantime, suggestions to any of the undersigned will be most welcome. Best wishes, Dietrich Baade Jim Beletic Gert Finger -- Dietrich Baade European Southern Observatory Karl-Schwarzschild-Strasse 2, 85748 Garching bei Muenchen, Germany Email: dbaade at eso.org Tel: +49 89 3200-6388 Fax: +49 89 3202362 From shai at wise.tau.ac.il Thu Mar 29 11:56:59 2007 From: shai at wise.tau.ac.il (Shai Kaspi) Date: Thu, 29 Mar 2007 17:56:59 +0200 (IST) Subject: CCD-world: CCD contamination problem Message-ID: Hello, At the Wise Observatory we have a Tek 1024x1024 CCD with pixel size of 24 micron, coated with METACHROME II. It was purchased from Photometrics at the beginning of 1994. The CCD is used for imaging with our 1m telescope. It worked very well until about two months ago when several black spots appeared on the images. The spots change their place over time so we guess they are some particles moving around close/on the CCD surface. They block the light and produce black spots/regions when taking an image. These black spots/regions cannot be flat-fielded out. The source of these "particles" is not clear. Seems like something is dissolving inside and spreading these particles all around. We spotted some particles stuck to the inner side of the CCD "glass" window, and they move when the CCD is strongly moved, but then other particles appear as well. We opened the CCD window and brushed away these particles from the glass but few days later more particles were back. >From looking at the images, it seems the particles are not only on the CCD window, as then they would form the out-of-focus bagel shadows. Rather, they appear to be ON the chip. Most of them are quite small, obscuring just one pixel, and the counts in those pixels don't go down to the bias level, meaning they're smaller than one pixel, i.e. 24 microns. The biggest one is 10 pixels across, so 0.25 mm. Our guess is that these particles are not black, but shiny (e.g. from some metallic coating that has crumbled off from something). The reason is that each spot is darkest as its center, but more and more light gets through to the CCD as one goes toward the spot's edges. Furthermore, around the biggest black spot there is a "halo" with counts higher than the background, which could be the result of reflection of light from the particle back onto the CCD. But all this is only a guess. We do have a getter inside and it could be that over the years and with enough temperature cycles this had produced some dust. However, we do not have the capability to take the camera apart and look at it. I put some images in: ftp://wise-gate.tau.ac.il/pub/shai/tmp/tek/ and there is a README file there which give some basic information about the images. Any information which will help us to further understand the problem and how it can be remedy will be most appreciated. Thanks, Shai Kaspi Wise Observatory, Israel From b.corrie at verizon.net Thu Mar 29 13:55:29 2007 From: b.corrie at verizon.net (Brian Corrie) Date: Thu, 29 Mar 2007 10:55:29 -0700 Subject: CCD-world: CCD contamination problem In-Reply-To: Message-ID: Beth, I have check into this part it was sold to Photometrics (Tucson) by SITe from the inventory we had at the time of the transition from Tektronix to SITe. Photometrics did the coating and the camera. There is nothing we can do to help this is now a Roper problem. Brian -----Original Message----- From: ccd-world-bounces at ctio.noao.edu [mailto:ccd-world-bounces at ctio.noao.edu]On Behalf Of Shai Kaspi Sent: Thursday, March 29, 2007 8:57 AM To: ccd-world at ctio.noao.edu Cc: Shai Kaspi Subject: CCD-world: CCD contamination problem Hello, At the Wise Observatory we have a Tek 1024x1024 CCD with pixel size of 24 micron, coated with METACHROME II. It was purchased from Photometrics at the beginning of 1994. The CCD is used for imaging with our 1m telescope. It worked very well until about two months ago when several black spots appeared on the images. The spots change their place over time so we guess they are some particles moving around close/on the CCD surface. They block the light and produce black spots/regions when taking an image. These black spots/regions cannot be flat-fielded out. The source of these "particles" is not clear. Seems like something is dissolving inside and spreading these particles all around. We spotted some particles stuck to the inner side of the CCD "glass" window, and they move when the CCD is strongly moved, but then other particles appear as well. We opened the CCD window and brushed away these particles from the glass but few days later more particles were back. >From looking at the images, it seems the particles are not only on the CCD window, as then they would form the out-of-focus bagel shadows. Rather, they appear to be ON the chip. Most of them are quite small, obscuring just one pixel, and the counts in those pixels don't go down to the bias level, meaning they're smaller than one pixel, i.e. 24 microns. The biggest one is 10 pixels across, so 0.25 mm. Our guess is that these particles are not black, but shiny (e.g. from some metallic coating that has crumbled off from something). The reason is that each spot is darkest as its center, but more and more light gets through to the CCD as one goes toward the spot's edges. Furthermore, around the biggest black spot there is a "halo" with counts higher than the background, which could be the result of reflection of light from the particle back onto the CCD. But all this is only a guess. We do have a getter inside and it could be that over the years and with enough temperature cycles this had produced some dust. However, we do not have the capability to take the camera apart and look at it. I put some images in: ftp://wise-gate.tau.ac.il/pub/shai/tmp/tek/ and there is a README file there which give some basic information about the images. Any information which will help us to further understand the problem and how it can be remedy will be most appreciated. Thanks, Shai Kaspi Wise Observatory, Israel -- CCD-world -- CCD-world is fully moderated. Send posts to CCD-world at ctio.noao.edu Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.ctio.noao.edu/mailman/listinfo/ccd-world From djs at aaocbn.aao.gov.au Thu Mar 29 18:27:55 2007 From: djs at aaocbn.aao.gov.au (Darren Stafford) Date: Fri, 30 Mar 2007 08:27:55 +1000 Subject: CCD-world: CCD contamination problem In-Reply-To: References: Message-ID: <460C3D6B.1010600@aaocbn.aao.gov.au> Hi Shai, The contamination may be tin. Sometimes tin is sneaked into a dewar as a replacement for indium (which is used as a conductive gasket). Check the gaskets in the heat path from the liquid nitrogen can to the ccd mounting block. Tin is easy to source and is cheap but it transforms from silvery, ductile, "white tin" to a grey powder "grey tin " at temperatures less then 13.2 degrees celsius. The process is called tin pest. Let me know what you find. Darren Stafford Anglo-Australian Observatory Coonabarabran Australia Shai Kaspi wrote: > Hello, > > At the Wise Observatory we have a Tek 1024x1024 CCD with pixel size > of 24 micron, coated with METACHROME II. It was purchased from > Photometrics at the beginning of 1994. The CCD is used for imaging > with our 1m telescope. It worked very well until about two months ago when > several black spots appeared on the images. The spots change > their place over time so we guess they are some particles moving > around close/on the CCD surface. They block the light and produce > black spots/regions when taking an image. These black spots/regions > cannot be flat-fielded out. > > The source of these "particles" is not clear. Seems like something > is dissolving inside and spreading these particles all around. > We spotted some particles stuck to the inner side of the CCD "glass" > window, and they move when the CCD is strongly moved, but then other > particles appear as well. We opened the CCD window and brushed away these > particles from the glass but few days later more particles were back. > > >From looking at the images, it seems the particles are not only > on the CCD window, as then they would form the out-of-focus bagel > shadows. Rather, they appear to be ON the chip. Most of them are > quite small, obscuring just one pixel, and the counts in those > pixels don't go down to the bias level, meaning they're smaller than > one pixel, i.e. 24 microns. The biggest one is 10 pixels across, > so 0.25 mm. Our guess is that these particles are not black, but > shiny (e.g. from some metallic coating that has crumbled off from > something). The reason is that each spot is darkest as its center, > but more and more light gets through to the CCD as one goes toward > the spot's edges. Furthermore, around the biggest black spot there > is a "halo" with counts higher than the background, which could be > the result of reflection of light from the particle back onto the > CCD. But all this is only a guess. > > We do have a getter inside and it could be that over the years and > with enough temperature cycles this had produced some dust. However, > we do not have the capability to take the camera apart and look at it. > > I put some images in: > ftp://wise-gate.tau.ac.il/pub/shai/tmp/tek/ > and there is a README file there which give some > basic information about the images. > > Any information which will help us to further understand the problem > and how it can be remedy will be most appreciated. > > Thanks, > Shai Kaspi > > Wise Observatory, Israel > > -- CCD-world -- > CCD-world is fully moderated. Send posts to CCD-world at ctio.noao.edu > Standard replies will go to the list; address personal replies manually. > For more information, please go to: http://www.ctio.noao.edu/mailman/listinfo/ccd-world > From ralf.kohley at gtc.iac.es Fri Mar 30 04:36:03 2007 From: ralf.kohley at gtc.iac.es (Ralf Kohley) Date: Fri, 30 Mar 2007 09:36:03 +0100 Subject: CCD-world: CCD contamination problem In-Reply-To: References: Message-ID: <000601c772a6$740068f0$1d1b48a1@grantecan.net> Hi Shai, It looks like a similar contamination problem Gert Raskin had with his E2V CCD42-20 (see his email to CCD-World). We took his cryostat apart here at the IAC cleanroom and had a look at the contamination. I first thought of charcoal particles from the getter, but at certain angles of light incidence the particles on the surface looked shiny, which points more to something metallic. We did not have the time to investigate more into the origin of the contamination and simply rinsed the particles off the surface with IPA. Gert thought of having gotten the contamination by a vacuum pumping accident, and at least so far it did not come back. Best regards, Ralf -----Mensaje original----- De: ccd-world-bounces at ctio.noao.edu [mailto:ccd-world-bounces at ctio.noao.edu] En nombre de Shai Kaspi Enviado el: jueves, 29 de marzo de 2007 16:57 Para: ccd-world at ctio.noao.edu CC: Shai Kaspi Asunto: CCD-world: CCD contamination problem Hello, At the Wise Observatory we have a Tek 1024x1024 CCD with pixel size of 24 micron, coated with METACHROME II. It was purchased from Photometrics at the beginning of 1994. The CCD is used for imaging with our 1m telescope. It worked very well until about two months ago when several black spots appeared on the images. The spots change their place over time so we guess they are some particles moving around close/on the CCD surface. They block the light and produce black spots/regions when taking an image. These black spots/regions cannot be flat-fielded out. The source of these "particles" is not clear. Seems like something is dissolving inside and spreading these particles all around. We spotted some particles stuck to the inner side of the CCD "glass" window, and they move when the CCD is strongly moved, but then other particles appear as well. We opened the CCD window and brushed away these particles from the glass but few days later more particles were back. >From looking at the images, it seems the particles are not only on the CCD window, as then they would form the out-of-focus bagel shadows. Rather, they appear to be ON the chip. Most of them are quite small, obscuring just one pixel, and the counts in those pixels don't go down to the bias level, meaning they're smaller than one pixel, i.e. 24 microns. The biggest one is 10 pixels across, so 0.25 mm. Our guess is that these particles are not black, but shiny (e.g. from some metallic coating that has crumbled off from something). The reason is that each spot is darkest as its center, but more and more light gets through to the CCD as one goes toward the spot's edges. Furthermore, around the biggest black spot there is a "halo" with counts higher than the background, which could be the result of reflection of light from the particle back onto the CCD. But all this is only a guess. We do have a getter inside and it could be that over the years and with enough temperature cycles this had produced some dust. However, we do not have the capability to take the camera apart and look at it. I put some images in: ftp://wise-gate.tau.ac.il/pub/shai/tmp/tek/ and there is a README file there which give some basic information about the images. Any information which will help us to further understand the problem and how it can be remedy will be most appreciated. Thanks, Shai Kaspi Wise Observatory, Israel -- CCD-world -- CCD-world is fully moderated. Send posts to CCD-world at ctio.noao.edu Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.ctio.noao.edu/mailman/listinfo/ccd-world ---------- ADVERTENCIA: La informacion incluida en este e-mail es CONFIDENCIAL, siendo para uso exclusivo del destinatario arriba mencionado. Si Usted lee este mensaje y no es el destinatario indicado, le informamos que esta totalmente prohibida cualquier utilizacion, divulgacion, distribucion y/o reproduccion de esta comunicacion sin autorizacion expresa en virtud de la legislacion vigente. Si ha recibido este mensaje por error, le rogamos nos lo notifique inmediatamente por esta misma via a GRAN TELESCOPIO DE CANARIAS, S.A. (gtc at gtc.iac.es) y proceda a su eliminacion. DISCLAIMER: This message is intended exclusively for its addressee and may contain information that is CONFIDENTIAL and protected by professional privilege. If you are not the intended recipient you are hereby notified that any dissemination, copy or disclosure of this communication is strictly prohibited by law. If this message has been received in error, please immediately notify us via e-mail to GRAN TELESCOPIO DE CANARIAS, S.A. (gtc at gtc.iac.es) and delete it. From wpk at saao.ac.za Sun Apr 1 15:43:16 2007 From: wpk at saao.ac.za (Willie Koorts) Date: Sun, 1 Apr 2007 21:43:16 +0200 (SAST) Subject: CCD-world: CCD contamination problem In-Reply-To: Message-ID: On Thu, 29 Mar 2007, Shai Kaspi wrote: > It worked very well until about two months ago when several black spots > appeared on the images. The spots change their place over time so we > guess they are some particles moving around close/on the CCD surface. > They block the light and produce black spots/regions when taking an > image. These black spots/regions cannot be flat-fielded out. At first it sounded similar to what we had had years ago, which was plasticiser condensing on the CCD and window (see http://www.saao.ac.za/~wpk/ccd/ustrip.html). Contamination from vacuum pump oil back-streaming when not following the correct pumping procedure can cause similar problems. These also don't flat-field out because the contamination is dynamic. > The source of these "particles" is not clear. Seems like something > is dissolving inside and spreading these particles all around. > We spotted some particles stuck to the inner side of the CCD "glass" > window, and they move when the CCD is strongly moved, but then other > particles appear as well. However, the fact that they move and change when shaken seems like particles, hence something "powdered up" inside the dewar. This is very strange - from our experience, getter material (zeolite or charcoal) do not, under normal circumstances, powder up unless the dewar was very badly (mis)handled. I cannot think of any material normally used inside dewars that will suddenly crumble like this. You obviously already investigated anything you did different in the last while since this problem started - different vacuum pump or pumping procedure, the dewar was inverted/dropped/knocked/shaken, etc. > However, we do not have the capability to take the camera apart and look > at it. This is a problem, otherwise you could have tried replacing the getter, but the "dust" must first be cleaned out and the CCD probably cleaned too (not a job for the faint at heart!). Regards Willie Mr. W.P. Koorts ( wpk at saao.ac.za ) South African Astronomical Observatory PO Box 9 Observatory 7935 South Africa Tel.(27) (21) 447 0025 Fax.(27) (21) 447 3639 World Wide Web ( Work ) http://www.saao.ac.za World Wide Web ( Personal ) http://www.saao.ac.za/~wpk/ From CMOSCCD at aol.com Sun Apr 1 11:16:02 2007 From: CMOSCCD at aol.com (CMOSCCD at aol.com) Date: Sun, 1 Apr 2007 11:16:02 EDT Subject: CCD-world: CMOS QE and X_RAY Message-ID: CMOS World. . . :-) Update on CMOS development. . . . Shown below is "first light" QE data for a back illuminated deep depletion, fano noise limited 8 um pixel CMOS array. Also, presented is a corresponding Fe-55 x-ray response. Data is generated from a CMOS test array with 128 pixel experiments. Although QE performance is identical for the pixels, x-ray results dramatically depend on pixel design geometry. The last figure below shows Fe-55 x-ray stacking plots for eight pixels. . . including the "best" pixel that generated QE and x-ray responses. Amazing. . . Credits. . . Backside illuminated devices provided by Mike Lesser. . . . . X-ray and QE measurements by Tom Elliott. . . . Jim ****************************jj ************************************** See what's free at http://www.aol.com. -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070401/b103840c/attachment.html -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: image/jpeg Size: 46382 bytes Desc: not available Url : http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070401/b103840c/attachment.jpe -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: image/jpeg Size: 53218 bytes Desc: not available Url : http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070401/b103840c/attachment-0001.jpe -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: image/jpeg Size: 70689 bytes Desc: not available Url : http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070401/b103840c/attachment-0002.jpe From martin at dvcco.com Fri Apr 27 11:27:12 2007 From: martin at dvcco.com (Martin Parker) Date: Fri, 27 Apr 2007 10:27:12 -0500 Subject: CCD-world: DC-coupled pre-amp? In-Reply-To: <0E7451C890AF144997C31B2C771C64A201FE77@MAILSBA.LCO.GTN> Message-ID: <001c01c788e0$8791a730$b001a8c0@dvcparker> Rich, I came across this today and was wondering how your circuit fared. Regards, Martin Parker Director of Engineering, DVC Company 10200 Hwy 290 West Austin, TX 78736 phone: 512-301-9564 x302 fax: 512-288-2961 martin at dvcco.com www.dvcco.com _____ From: ccd-world-bounces at ctio.noao.edu [mailto:ccd-world-bounces at ctio.noao.edu] On Behalf Of Rich Lobdill Sent: Tuesday, January 09, 2007 12:22 PM To: CCD-world at ctio.noao.edu Subject: CCD-world: DC-coupled pre-amp? Dear All: Here at Las Cumbres Observatory, I've been given the opportunity to approach the front-end camera design with a clean slate. My background is in low-noise analog amplifiers used in electrophysiology. I've not designed a camera so that might be good or bad !?. I've come up with a little circuit to continually subtract the DC level of the CCD output while at the same time leaving the high frequency information unaltered for presenting to the CDS circuit. This adds a few parts but removes the need for a high quality, large footprint blocking cap (and even the high quality caps are not ideal). There are no switches used, the DC subtraction is done with a linear approach. I wouldn't consider this approach novel but I have not seen it implemented in any of the camera schemes I have been able to study. So my question to my esteemed colleagues on this list is: Are there well known downsides to this approach that make it infeasible? I realize noise could be added due to this topology but I think with an eye towards noise, the noise addition could be reduced to being negligible. Thanks in advance for any insight. Rich Lobdill Las Cumbres Observatory Goleta, CA -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070427/cf51ca90/attachment.html From tg.burke at ngc.com Mon Apr 30 12:30:51 2007 From: tg.burke at ngc.com (Burke, Thomas G.) Date: Mon, 30 Apr 2007 12:30:51 -0400 Subject: CCD-world: DC-coupled pre-amp? In-Reply-To: <001c01c788e0$8791a730$b001a8c0@dvcparker> References: <0E7451C890AF144997C31B2C771C64A201FE77@MAILSBA.LCO.GTN> <001c01c788e0$8791a730$b001a8c0@dvcparker> Message-ID: nobody asked for my $0.02, but it seems that the servo loop, however slow it is, might be prone to add some error in there. Of course, I suppose you'd need real data to see how bad it is, but... ________________________________ From: ccd-world-bounces at ctio.noao.edu [mailto:ccd-world-bounces at ctio.noao.edu] On Behalf Of Martin Parker Sent: Friday, April 27, 2007 11:27 AM To: 'Optical & SWIR imager development for professional astronomy' Subject: Re: CCD-world: DC-coupled pre-amp? Rich, I came across this today and was wondering how your circuit fared. Regards, Martin Parker Director of Engineering, DVC Company 10200 Hwy 290 West Austin, TX 78736 phone: 512-301-9564 x302 fax: 512-288-2961 martin at dvcco.com www.dvcco.com ________________________________ From: ccd-world-bounces at ctio.noao.edu [mailto:ccd-world-bounces at ctio.noao.edu] On Behalf Of Rich Lobdill Sent: Tuesday, January 09, 2007 12:22 PM To: CCD-world at ctio.noao.edu Subject: CCD-world: DC-coupled pre-amp? Dear All: Here at Las Cumbres Observatory, I've been given the opportunity to approach the front-end camera design with a clean slate. My background is in low-noise analog amplifiers used in electrophysiology. I've not designed a camera so that might be good or bad !?. I've come up with a little circuit to continually subtract the DC level of the CCD output while at the same time leaving the high frequency information unaltered for presenting to the CDS circuit. This adds a few parts but removes the need for a high quality, large footprint blocking cap (and even the high quality caps are not ideal). There are no switches used, the DC subtraction is done with a linear approach. I wouldn't consider this approach novel but I have not seen it implemented in any of the camera schemes I have been able to study. So my question to my esteemed colleagues on this list is: Are there well known downsides to this approach that make it infeasible? I realize noise could be added due to this topology but I think with an eye towards noise, the noise addition could be reduced to being negligible. Thanks in advance for any insight. Rich Lobdill Las Cumbres Observatory Goleta, CA -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070430/b353b658/attachment.html From pmoore at noao.edu Mon Apr 30 13:12:13 2007 From: pmoore at noao.edu (Peter Moore) Date: Mon, 30 Apr 2007 10:12:13 -0700 Subject: CCD-world: DC-coupled pre-amp? In-Reply-To: References: <0E7451C890AF144997C31B2C771C64A201FE77@MAILSBA.LCO.GTN> <001c01c788e0$8791a730$b001a8c0@dvcparker> Message-ID: Hi Gang, Yup it's high time we sent some traffic through ccd-world and began conversing between ourselves again .. maybe it is because we are all 'under the gun' to produce nowdays and no one has time to dream .. except Rich ! Rich, I assume from your email that you are measuring the DC offset with a long time constant lossy integrator and summing the term back into the inverting node of the preamp (Please shoot me down if I'm wrong :-). This approach, given the correct time constant worked well in early comercial cameras but has limitations concerning the available dynamic range of the rest of the DC coupled stages. This because the reset feedthrough pulse from a typical CCD amplifier output will add an error offset which will eat up some of your dynamic range. In a similar manner, the integrator will have to recover from the increase in the pixel2pixel timing when a new row is shifted into the serial register. Apart from these 'problems' I think that the concept is feasable ... Has anyone actually implemented this ? While on the subject of front ends ... I'd like to take the oportunity to ask if anyone has ever implemented (or thought about implementing) a transformer coupled front end to convert from single ended to differential mode ? I'm considering this as it seems to offer a chance to transform the signal and add moderate gain without incurring noise. Any comments or experiences ? All the best, Peter. Peter Moore - Detector Engineer - ETS. Email: pmoore at noao.edu Smail: National Optical Astronomy Observatory, Casilla 603, La Serena, Chile. Phone: +56 51 205233 or +56 51 205208 Faxes: +1 520 318 8303 Skype: pmoore159 The fact that we live at the bottom of a deep gravity well, on the surface of a gas covered planet going around a nuclear fireball 90 million miles away and think this to be normal is obviously some indication of how skewed our perspective tends to be. - Douglas Adams 1998. From rlobdill at lcogt.net Mon Apr 30 13:27:19 2007 From: rlobdill at lcogt.net (Rich Lobdill) Date: Mon, 30 Apr 2007 10:27:19 -0700 Subject: CCD-world: DC-coupled pre-amp? In-Reply-To: References: <0E7451C890AF144997C31B2C771C64A201FE77@MAILSBA.LCO.GTN><001c01c788e0$8791a730$b001a8c0@dvcparker> Message-ID: <0E7451C890AF144997C31B2C771C64A201FEEB@MAILSBA.LCO.GTN> Martin: I've been through a couple of iterations. I've spent more time optimizing noise than dynamics so still have some ways to go. On the noise side of things, my circuit generates a noise of about 3 uVrms (RTI) for a 1 MHz pixel rate. For the CCD we plan to use the noise equates to about 1e-rms. I put forth previously that I could do the DC coupled circuit with no switches. That turned out to be optimistic. I will need one switch but it will only need to be switched in/out prior to (and just after) a complete CCD readout. Making this topology work and not add significant noise is where a large portion of my time was spent. As I said above, I'm still not happy with the dynamics of the circuit (dealing with the reset feedthrough pulse) so we shall see. If I can solve the dynamics issues then I will have a circuit that will not suffer from 'remnant noise' since there will be no capacitor switching at each pixel read. Rich ________________________________ From: ccd-world-bounces at ctio.noao.edu [mailto:ccd-world-bounces at ctio.noao.edu] On Behalf Of Burke, Thomas G. Sent: Monday, April 30, 2007 9:31 AM To: martin at dvcco.com; Optical & SWIR imager development for professional astronomy Subject: Re: CCD-world: DC-coupled pre-amp? nobody asked for my $0.02, but it seems that the servo loop, however slow it is, might be prone to add some error in there. Of course, I suppose you'd need real data to see how bad it is, but... ________________________________ From: ccd-world-bounces at ctio.noao.edu [mailto:ccd-world-bounces at ctio.noao.edu] On Behalf Of Martin Parker Sent: Friday, April 27, 2007 11:27 AM To: 'Optical & SWIR imager development for professional astronomy' Subject: Re: CCD-world: DC-coupled pre-amp? Rich, I came across this today and was wondering how your circuit fared. Regards, Martin Parker Director of Engineering, DVC Company 10200 Hwy 290 West Austin, TX 78736 phone: 512-301-9564 x302 fax: 512-288-2961 martin at dvcco.com www.dvcco.com ________________________________ From: ccd-world-bounces at ctio.noao.edu [mailto:ccd-world-bounces at ctio.noao.edu] On Behalf Of Rich Lobdill Sent: Tuesday, January 09, 2007 12:22 PM To: CCD-world at ctio.noao.edu Subject: CCD-world: DC-coupled pre-amp? Dear All: Here at Las Cumbres Observatory, I've been given the opportunity to approach the front-end camera design with a clean slate. My background is in low-noise analog amplifiers used in electrophysiology. I've not designed a camera so that might be good or bad !?. I've come up with a little circuit to continually subtract the DC level of the CCD output while at the same time leaving the high frequency information unaltered for presenting to the CDS circuit. This adds a few parts but removes the need for a high quality, large footprint blocking cap (and even the high quality caps are not ideal). There are no switches used, the DC subtraction is done with a linear approach. I wouldn't consider this approach novel but I have not seen it implemented in any of the camera schemes I have been able to study. So my question to my esteemed colleagues on this list is: Are there well known downsides to this approach that make it infeasible? I realize noise could be added due to this topology but I think with an eye towards noise, the noise addition could be reduced to being negligible. Thanks in advance for any insight. Rich Lobdill Las Cumbres Observatory Goleta, CA -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070430/dc366c53/attachment.html From atwood at mps.ohio-state.edu Mon Apr 30 13:45:44 2007 From: atwood at mps.ohio-state.edu (Bruce Atwood) Date: Mon, 30 Apr 2007 13:45:44 -0400 Subject: CCD-world: DC-coupled pre-amp? In-Reply-To: References: <0E7451C890AF144997C31B2C771C64A201FE77@MAILSBA.LCO.GTN> <001c01c788e0$8791a730$b001a8c0@dvcparker> Message-ID: <46362B48.6070204@ohstpy.mps.ohio-state.edu> Burke, Thomas G. wrote: > nobody asked for my $0.02, but it seems that the servo loop, however > slow it is, might be prone to add some error in there. Of course, I > suppose you'd need real data to see how bad it is, but... > > ------------------------------------------------------------------------ > From: ccd-world-bounces at ctio.noao.edu > [mailto:ccd-world-bounces at ctio.noao.edu] On Behalf Of Martin Parker > Sent: Friday, April 27, 2007 11:27 AM > To: 'Optical & SWIR imager development for professional astronomy' > Subject: Re: CCD-world: DC-coupled pre-amp? > > Rich, > > I came across this today and was wondering how your circuit fared. > > Regards, > > > Martin Parker > Director of Engineering, DVC Company > 10200 Hwy 290 West > Austin, TX 78736 > phone: 512-301-9564 x302 > fax: 512-288-2961 > martin at dvcco.com > www.dvcco.com > > > ------------------------------------------------------------------------ > From: ccd-world-bounces at ctio.noao.edu > [mailto:ccd-world-bounces at ctio.noao.edu] On Behalf Of Rich Lobdill > Sent: Tuesday, January 09, 2007 12:22 PM > To: CCD-world at ctio.noao.edu > Subject: CCD-world: DC-coupled pre-amp? > > Dear All: > > Here at Las Cumbres Observatory, I've been given the > opportunity to approach the front-end camera design with a > clean slate. My background is in low-noise analog amplifiers > used in electrophysiology. I've not designed a camera so > that might be good or bad !?. > > I've come up with a little circuit to continually subtract > the DC level of the CCD output while at the same time > leaving the high frequency information unaltered for > presenting to the CDS circuit. This adds a few parts but > removes the need for a high quality, large footprint > blocking cap (and even the high quality caps are not > ideal). There are no switches used, the DC subtraction is > done with a linear approach. > > I wouldn't consider this approach novel but I have not seen > it implemented in any of the camera schemes I have been able > to study. So my question to my esteemed colleagues on this > list is: Are there well known downsides to this approach > that make it infeasible? I realize noise could be added due > to this topology but I think with an eye towards noise, the > noise addition could be reduced to being negligible. > > Thanks in advance for any insight. > > Rich Lobdill > Las Cumbres Observatory > Goleta, CA > >------------------------------------------------------------------------ > > >-- CCD-world -- >CCD-world is fully moderated. Send posts to CCD-world at ctio.noao.edu >Standard replies will go to the list; address personal replies manually. >For more information, please go to: http://www.ctio.noao.edu/mailman/listinfo/ccd-world > > For me the arguments against DC coupling are: 1: Requires analog electronics that operates at >~20 volts above the substrate, while everything else (with the exception of the not very critical DC supply for the output drain) can operate with +/- 15 volt electronics 2. A challenge to implement without adding noise (who needs extra challenges). 3. Requires either a very very stable detector temperature or some closed loop scheme to compensate for changes in Vos with temperature. The disadvantage of AC coupling are some loss of flexibility in readout timing due to the fixed input time constant. The time constant must be chosen so that errors introduced as you go from a long string of bright pixels to a dark pixel, or vice versa, are acceptable. -- Bruce Atwood Department of Astronomy The Ohio State University 140 West 18th Ave. Columbus, OH 43210-1173 Phone 614.292.6279 FAX 614.292.2928 -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070430/9ea9cb98/attachment.html From tg.burke at ngc.com Mon Apr 30 14:08:00 2007 From: tg.burke at ngc.com (Burke, Thomas G.) Date: Mon, 30 Apr 2007 14:08:00 -0400 Subject: CCD-world: DC-coupled pre-amp? In-Reply-To: References: <0E7451C890AF144997C31B2C771C64A201FE77@MAILSBA.LCO.GTN><001c01c788e0$8791a730$b001a8c0@dvcparker> Message-ID: Never done a trasformer coupling, as the trasformer (generally speaking) adds hysteresis ans limits bandwidth. Instead, we've done one of two things: 1) Carry a separate ground wire from the output all the way to the differential input of the Op-Amp/ADC, effectively creating a signal match for the distance. Works pretty well. 2) Use two op-amps to create a push-pull amplifier that sits very near the sensor output, to set up differential signalling. Gotta be careful with this one, though, as the phasing can be out of whack, and create distorted signals. -----Original Message----- From: ccd-world-bounces at ctio.noao.edu [mailto:ccd-world-bounces at ctio.noao.edu] On Behalf Of Peter Moore Sent: Monday, April 30, 2007 1:12 PM To: Optical & SWIR imager development for professional astronomy Subject: Re: CCD-world: DC-coupled pre-amp? Hi Gang, Yup it's high time we sent some traffic through ccd-world and began conversing between ourselves again .. maybe it is because we are all 'under the gun' to produce nowdays and no one has time to dream .. except Rich ! Rich, I assume from your email that you are measuring the DC offset with a long time constant lossy integrator and summing the term back into the inverting node of the preamp (Please shoot me down if I'm wrong :-). This approach, given the correct time constant worked well in early comercial cameras but has limitations concerning the available dynamic range of the rest of the DC coupled stages. This because the reset feedthrough pulse from a typical CCD amplifier output will add an error offset which will eat up some of your dynamic range. In a similar manner, the integrator will have to recover from the increase in the pixel2pixel timing when a new row is shifted into the serial register. Apart from these 'problems' I think that the concept is feasable ... Has anyone actually implemented this ? While on the subject of front ends ... I'd like to take the oportunity to ask if anyone has ever implemented (or thought about implementing) a transformer coupled front end to convert from single ended to differential mode ? I'm considering this as it seems to offer a chance to transform the signal and add moderate gain without incurring noise. Any comments or experiences ? All the best, Peter. Peter Moore - Detector Engineer - ETS. Email: pmoore at noao.edu Smail: National Optical Astronomy Observatory, Casilla 603, La Serena, Chile. Phone: +56 51 205233 or +56 51 205208 Faxes: +1 520 318 8303 Skype: pmoore159 The fact that we live at the bottom of a deep gravity well, on the surface of a gas covered planet going around a nuclear fireball 90 million miles away and think this to be normal is obviously some indication of how skewed our perspective tends to be. - Douglas Adams 1998. -- CCD-world -- CCD-world is fully moderated. Send posts to CCD-world at ctio.noao.edu Standard replies will go to the list; address personal replies manually. For more information, please go to: http://www.ctio.noao.edu/mailman/listinfo/ccd-world From tg.burke at ngc.com Mon Apr 30 14:09:52 2007 From: tg.burke at ngc.com (Burke, Thomas G.) Date: Mon, 30 Apr 2007 14:09:52 -0400 Subject: CCD-world: DC-coupled pre-amp? In-Reply-To: <0E7451C890AF144997C31B2C771C64A201FEEB@MAILSBA.LCO.GTN> References: <0E7451C890AF144997C31B2C771C64A201FE77@MAILSBA.LCO.GTN><001c01c788e0$8791a730$b001a8c0@dvcparker> <0E7451C890AF144997C31B2C771C64A201FEEB@MAILSBA.LCO.GTN> Message-ID: If you connect the switch properly, there should be very little noise induced by that switch. Trick is to ground reference that switch, so any "feed-through" will have a tendency to go straight to ground, rather than into your circuit. ________________________________ From: ccd-world-bounces at ctio.noao.edu [mailto:ccd-world-bounces at ctio.noao.edu] On Behalf Of Rich Lobdill Sent: Monday, April 30, 2007 1:27 PM To: Optical & SWIR imager development for professional astronomy; martin at dvcco.com Subject: Re: CCD-world: DC-coupled pre-amp? Martin: I've been through a couple of iterations. I've spent more time optimizing noise than dynamics so still have some ways to go. On the noise side of things, my circuit generates a noise of about 3 uVrms (RTI) for a 1 MHz pixel rate. For the CCD we plan to use the noise equates to about 1e-rms. I put forth previously that I could do the DC coupled circuit with no switches. That turned out to be optimistic. I will need one switch but it will only need to be switched in/out prior to (and just after) a complete CCD readout. Making this topology work and not add significant noise is where a large portion of my time was spent. As I said above, I'm still not happy with the dynamics of the circuit (dealing with the reset feedthrough pulse) so we shall see. If I can solve the dynamics issues then I will have a circuit that will not suffer from 'remnant noise' since there will be no capacitor switching at each pixel read. Rich ________________________________ From: ccd-world-bounces at ctio.noao.edu [mailto:ccd-world-bounces at ctio.noao.edu] On Behalf Of Burke, Thomas G. Sent: Monday, April 30, 2007 9:31 AM To: martin at dvcco.com; Optical & SWIR imager development for professional astronomy Subject: Re: CCD-world: DC-coupled pre-amp? nobody asked for my $0.02, but it seems that the servo loop, however slow it is, might be prone to add some error in there. Of course, I suppose you'd need real data to see how bad it is, but... ________________________________ From: ccd-world-bounces at ctio.noao.edu [mailto:ccd-world-bounces at ctio.noao.edu] On Behalf Of Martin Parker Sent: Friday, April 27, 2007 11:27 AM To: 'Optical & SWIR imager development for professional astronomy' Subject: Re: CCD-world: DC-coupled pre-amp? Rich, I came across this today and was wondering how your circuit fared. Regards, Martin Parker Director of Engineering, DVC Company 10200 Hwy 290 West Austin, TX 78736 phone: 512-301-9564 x302 fax: 512-288-2961 martin at dvcco.com www.dvcco.com ________________________________ From: ccd-world-bounces at ctio.noao.edu [mailto:ccd-world-bounces at ctio.noao.edu] On Behalf Of Rich Lobdill Sent: Tuesday, January 09, 2007 12:22 PM To: CCD-world at ctio.noao.edu Subject: CCD-world: DC-coupled pre-amp? Dear All: Here at Las Cumbres Observatory, I've been given the opportunity to approach the front-end camera design with a clean slate. My background is in low-noise analog amplifiers used in electrophysiology. I've not designed a camera so that might be good or bad !?. I've come up with a little circuit to continually subtract the DC level of the CCD output while at the same time leaving the high frequency information unaltered for presenting to the CDS circuit. This adds a few parts but removes the need for a high quality, large footprint blocking cap (and even the high quality caps are not ideal). There are no switches used, the DC subtraction is done with a linear approach. I wouldn't consider this approach novel but I have not seen it implemented in any of the camera schemes I have been able to study. So my question to my esteemed colleagues on this list is: Are there well known downsides to this approach that make it infeasible? I realize noise could be added due to this topology but I think with an eye towards noise, the noise addition could be reduced to being negligible. Thanks in advance for any insight. Rich Lobdill Las Cumbres Observatory Goleta, CA -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.ctio.noao.edu/pipermail/ccd-world/attachments/20070430/818c7cf0/attachment.html From mpeck at ucolick.org Mon Apr 30 14:18:37 2007 From: mpeck at ucolick.org (Michael Peck) Date: Mon, 30 Apr 2007 11:18:37 -0700 Subject: CCD-world: DC-coupled pre-amp? In-Reply-To: References: <0E7451C890AF144997C31B2C771C64A201FE77@MAILSBA.LCO.GTN> <001c01c788e0$8791a730$b001a8c0@dvcparker> Message-ID: <463632FD.1050207@ucolick.org> ... and my 2 cents - (pretty soon we'll have enough for a cup of coffee) I did a digital servo for an IR system with first order DC drift - I put a DAC in the feed back loop and only updated the DC level during specific times that did not impact the integration. This allowed the DC front end to stay within range even with high gains. There was a DSP (any micro controller will work) in the loop so there was real-time update for the offset. Another benefit is that the DC offset was reported in the header so that the absolute DC input could be recovered. DAC systems can be made highly stable (use a high quality (re $$) voltage reference) and low noise (low noise DAC and filtering). The DSP kept track of video histogram information to calculate the best DC offset to keep all the video in the ADC range. This allowed for some saturation or clipping without pushing the zero level off of the other end of the ADC - something not easily duplicated in an analog approach. The next thing to consider is eliminating the analog CDS circuit and replacing it with digital over sampling and digital CDS. There are multi-megahertz 16-bit ADCs that run on 1/4 watt that make a great alternative to analog CDS for pixel rates up to about 1MHz. At fractional MHz pixel rates, multiple samples are taken on both the signal and reset levels reducing noise in the CDS result. For 200 kHz pixel rates we got 18-20 bit CDS performance with a 5 MHz ADC. Michael Peck UCO/Lick Observatory Technical Facilities University of California, Santa Cruz 1156 High Street Santa Cruz, California 95064 Burke, Thomas G. wrote: > nobody asked for my $0.02, but it seems that the servo loop, however > slow it is, might be prone to add some error in there. Of course, I > suppose you'd need real data to see how bad it is, but... > > ------------------------------------------------------------------------ > *From:* ccd-world-bounces at ctio.noao.edu > [mailto:ccd-world-bounces at ctio.noao.edu] *On Behalf Of *Martin Parker > *Sent:* Friday, April 27, 2007 11:27 AM > *To:* 'Optical & SWIR imager development for professional astronomy' > *Subject:* Re: CCD-world: DC-coupled pre-amp? > > Rich, > > I came across this today and was wondering how your circuit fared. > > Regards, > > > Martin Parker > Director of Engineering, DVC Company > 10200 Hwy 290 West > Austin, TX 78736 > phone: 512-301-9564 x302 > fax: 512-288-2961 > martin at dvcco.com > www.dvcco.com > > > ------------------------------------------------------------------------ > *From:* ccd-world-bounces at ctio.noao.edu > [mailto:ccd-world-bounces at ctio.noao.edu] *On Behalf Of *Rich Lobdill > *Sent:* Tuesday, January 09, 2007 12:22 PM > *To:* CCD-world at ctio.noao.edu > *Subject:* CCD-world: DC-coupled pre-amp? > > Dear All: > > Here at Las Cumbres Ob