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Old 04-12-2008, 11:56 AM
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Omaroo (Chris Malikoff)
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Omaroo is offline
Join Date: Aug 2006
Location: Sydney/Cooma
Posts: 7,628
Thanks Bert - much appreciated.

So - from that are you saying, I gather that it may not be the absolute temerature of a CCD or CMOS array that determines the point at which thermal noise will start to become prevalent, but how far from its "equilibrium" it is at any point? I wouldn't have thought that a measured 2-degree rise in temerature of an array sounds like it should be enough to trigger thermal noise (but I'm not knowledgable in this area so might be sprouting rubbish), so is your method of measurement accurate at pixel fence level - or are you looking at the temperature of the sensor and its casing through a glass filter over an average area? I can imagine that the photodiodes might each be a good deal warmer than that average - triggering their noise response.

If you leave the cool-down period between frames very short - without a giving heat a chance to dissipate, does chip heat accumulate to a point that it is indeed very warm? What is, in fact, "very warm"? At what point does noise start to show? Is it the product of a temperature differential between the array and its environment, or is it due to an absolute temperature - above which you get noise and below you dont?

Last edited by Omaroo; 05-12-2008 at 04:24 PM.
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