Posted by
Gerhard Holst on
URL: http://confocal-microscopy-list.275.s1.nabble.com/CMOS-inquiry-for-camera-gurus-tp7589055p7589061.html
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Dear Josh,
I try to answer your questions:
You wrote:
1. I remember hearing a little bit about cameras holding vacuum, but not about this backfill problem. Anyway, what is backfill and how does it go wrong? Is it some kind of an inert, dry gas around the sensor that may now have some moist air in it? How is it possible to get a backfill problem without the seal on the vacuum also breaking? Interestingly, I believe I saw online that the (pre-2016) Andor warranty is 5years on the vacuum and 3years on the backfill.
As far as I know (keep in mind that I am from a competitor of Andor) the Zyla is TE cooled but not to an extent that it requires vacuum. Like for the emCCD cameras or the Neo camera. Therefore I guess that one of the seals might have been not as tight as you would prefer it and then it might happen that humidity might enter, which even at an absoluete cooling to 0°C or 5°C can cause condensation. Usually, if you cool but run the camera at normal pressure in the camera head, the head is filled with nitrogen, xenon or argon to keep the humidity out, sometime scavengers are added too.
You wrote:
2. If we have to spend ~$1k to have Andor take a look and then, assuming it is repairable pay more money (not sure how much, but I'd guess at least $1-2k), I wonder whether we might be better off just getting something new. Most recently, we had been using the Zyla on a spinning disc, though it might have been overkill there. Does anybody have suggestions for an alternative, such as a good and affordable CMOS camera? We're looking for something with >1MP, >50Hz, QE>65%, some cooling to help keep the read noise low, a fire signal for synchronization, and compatibility with Micromanager.
Let's say that's the everlasting problem or issue you have to face when you apply cameras in scientific environment. You application or the questions you try to answer define the required performance data, that you need to look for. To a certain extent it can get philosophical. The Zyla, like all the other sCMOS cameras is a good fit for a spinning disk system. If your stains or samples are very bright, you might do with a less sensitive, and less dynamic range camera, which is cheaper. There is a whole bunch of machine vision cameras which use the Sony IMX174 CMOS image sensor (that's the one in the camera which you mentioned), mostly non-cooled which means even cheaper than the ZWO. If this is what you need go ahead.
But don't expect offset stability, don't expect a good linearity and don't expect a high dynamic range, and don't expect a very low readout noise, which can be extremely convenient, if the signals you are looking at are low, and don't expect a high variability of triggering options. I know that the standard CMOS image sensors become better and better, which can mean that more and more the cheaper cameras can repülace the expensive scientific cameras, but there is also a reason, that scientifc cameras are a bit more expensive, beside the fact that the manufacturers live from it :-). There is nothing wrong to buy a cheaper camera, if it does what you need.
About you idea for what cooling is good for, I wanted to say, at first, it serves for stabilization of offset and image sensor, even if you record for longer times this should be stable (and this is independent from the absolute value of the temperature), then, in case of long exposure times, it reduces the amount of dark current and dark current noise contribution to the signal, but it also reduces the sensitivity towards the red part of the visible spectrum. There are plenty machine vision manufacturers, but I guess none of them really cools the image sensor.
You wrote:
Related to 2, here is a little info on the sort of thing we are interested in. We recently purchased a ZWO CMOS camera for ~ $900 and it has been very nice on our benchtop LED/epi scope (ZWO ASI 174 Cooled). It gives surprisingly good performance for the price. The specs state 2.4MP, 5.9um pixels, cooled to 40C below ambient, peak QE of 79%, up to 128FPS, works fine with Micromanager, but *lacks* a fire signal and we think only has a buffer of one frame. So it is very close to what we want, but we need really need a fire signal for synchronization on our spinning disc and we think a bigger buffer would probably also be important.
As said, the camera uses the IMX174 Sony CMOS image sensor which is a little older right now, since Sony has reduced their standard pixel size. For sure it is a good image sensor, it has roughly 13 bit dynamic, but you only get 12 bit out, 3-4 e- readout noise (if I remember correctly). In case all data are transmitted, what is your worry about the buffer size?
mit freundlichen Grüßen,
Gerhard
Dr. Gerhard Holst
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Von: Confocal Microscopy List [mailto:
[hidden email]] Im Auftrag von Joshua Vaughan
Gesendet: Mittwoch, 16. Januar 2019 08:32
An:
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Betreff: CMOS inquiry for camera gurus
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Dear camera gurus,
our Andor Zyla 5.5 sCMOS camera shows condensation on the chip when we cool it. Andor told us this might be caused by a backfill issue and it costs ~$1,000 to take a look, possible 4-6weeks turnaround and probably more money to fix the problem. I have a couple questions and I am also looking for a little advice.
1. I remember hearing a little bit about cameras holding vacuum, but not about this backfill problem. Anyway, what is backfill and how does it go wrong? Is it some kind of an inert, dry gas around the sensor that may now have some moist air in it? How is it possible to get a backfill problem without the seal on the vacuum also breaking? Interestingly, I believe I saw online that the (pre-2016) Andor warranty is 5years on the vacuum and 3years on the backfill.
2. If we have to spend ~$1k to have Andor take a look and then, assuming it is repairable pay more money (not sure how much, but I'd guess at least $1-2k), I wonder whether we might be better off just getting something new. Most recently, we had been using the Zyla on a spinning disc, though it might have been overkill there. Does anybody have suggestions for an alternative, such as a good and affordable CMOS camera? We're looking for something with >1MP, >50Hz, QE>65%, some cooling to help keep the read noise low, a fire signal for synchronization, and compatibility with Micromanager.
Related to 2, here is a little info on the sort of thing we are interested in. We recently purchased a ZWO CMOS camera for ~ $900 and it has been very nice on our benchtop LED/epi scope (ZWO ASI 174 Cooled). It gives surprisingly good performance for the price. The specs state 2.4MP, 5.9um pixels, cooled to 40C below ambient, peak QE of 79%, up to 128FPS, works fine with Micromanager, but *lacks* a fire signal and we think only has a buffer of one frame. So it is very close to what we want, but we need really need a fire signal for synchronization on our spinning disc and we think a bigger buffer would probably also be important.
https://optcorp.com/products/zwo-asi-174-cooled-monochrome-cmos-telescope-cameraThanks!
Best regards,
Josh
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Joshua C. Vaughan
Assistant Professor
Department of Chemistry
Box 351700
University of Washington
Seattle, WA 98195
206-543-4644