Thermoelectric cooler aids astro imaging

The new Artemis ART11002 charge coupled device camera uses a Kryotherm thermoelectric cooling device from Steadlands International.

Despite the speed at which light travels, taking photographs of stars and nebulas in deep space is a lengthy process which requires a very low dark current to enable exposures of many hours to be performed.

To achieve this requirement, the new Artemis ART11002 CCD (charge coupled device) camera uses a Kryotherm thermoelectric cooling device from Steadlands International.

The CCD is sealed in a cold chamber which is Peltier cooled to 25C below ambient in order to create a very low dark current of 0.03 electron/s.

The 11Mpixel camera has a slightly larger than 35mm format and each pixel measures 9.0um.

The ART11002 uses a standard Artemis operating system on a PIC microcontroller running at 32MHz which looks after most of the house keeping functions of the camera including temperature control of the sensor.

An analogue to digital convertor can convert 2Msample/s at 16bit resolution and a reprogrammable logic device handles the high speed signal generation as well as data processing.

Chosen for their cost, reliability and the ease with which they can drive high voltage, lower current devices the Kryotherm parts offers number of advantages over traditional refrigeration methods, such as no moving parts and do not require the use of liquids, gases or refrigerants, compact size, precise temperature control and their ability to operate quietly in any orientation.

The Peltier effect occurs whenever current passes through the circuit of two dissimilar semiconductors.

Depending on the current direction, the junction of the two conductors will either absorb or release heat, in direct proportion to the current supplied.

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