Monday, July 02, 2007

Peltier cooling for even longer exposure

These are dark frames basically (with some light leakage), exposure of individual frames are 315s, i.e. more than 5 minutes which are quite typical maximum for Hong Kong darkest sky.

The camera is on for 10 minutes before the test, so t = 0 means the camera has been used for 10 minutes already, and I turned on Peltier cooling at t = 0. So you can see the Peltier will take some time to cool down the camera, and you can see until around the 7th frame, the temperature stabilized and the noise level remained the same afterward.

t = 0

t = 332

t = 996

t = 1328

t = 1660

t = 1992

t = 2324

t = 2656

t = 2988

t = 3320

Amplifier glow can be seen at the upper left, especially when the camera is cooled, but not yet fully cooled. Seems like cooling can keep them to minimum.

I measured the temperature after cooling, and it's around 8-10 degrees below ambient.

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