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Audine KAF0402-ME with LPT1 interface = noise statistics in the offset and dark frames


30 offset frames are taken with closed shutter and 0 sec exposure.
30 dark frames are taken with closed shutter and 30 sec exposure.
AudeLA v1.5 is used. The CCD camera temperature is stabilised (stabilisation time 1h) at -5.8 °C

Analysis of offset frames
I start by analysing the offset frames. For each pixel, I calculate the mean and standard deviation over the 30 frames. Each pixel is thus characterised by its mean and standard deviation sigma. It can be represented by a point with coordinates (mean, sigma). Here is the obtained map.



The same operation is made, after removing the line and column at the frame edge which have a slightly different offset value.



Analysis of dark frames
The same analysis is repeated with the dark frames. The line and column that have slightly different offset values are again excluded.

The thermal signal is well visible, some hot pixels with a mean value higher than the offset appear on the right of the map. It can be noticed that their standard deviation increases with their amplitude. That is normal since the noise of the thermal signal is a shot noise.



I don't have any clear explanation for the group of hot pixels observed at a value slightly higher than the offset. Thus I have put an interrogation mark on the map. However, a similar effect is visible on the analyses of thermal signal performed by C.Buil for digital cameras Canon EOS 350D and 400D (which have CMOS type sensors).

Comparison offset / dark frames