Advances in development of thermoelectric modules for cooling electro-optic components

V. A. Semenyuk

Thermion Company, Odessa State Academy of Refrigeration, 65009 Odessa, Ukraine

The cooling of electro-optic components is one of the most important applications of thermoelectric technology. As heat sources, these components can be divided into two groups. The first one combines localized elements (semiconductor diodes and lasers, power amplifiers and other intensive optoelectronics). These elements are characterized with moderate operating temperatures and high density heat release. To ensure their safe operation, miniature thermoelectric coolers (TECs) with compatible cooling power density have to be created. The second group are multi-element IR detectors, CCDs and other planar large-geometry optoelectronics. In contrast to the elements of the first group, they constitute a family of low intensive deconcentrated power sources which need however relatively low operating temperatures (140-220 K). To provide their high efficiency, multistage thermoelectric coolers (TECs) have to be created, in which enlarged cold side dimensions are coupled with low required temperature, minimal power consumption and acceptable mechanical strength, the demands being contradictory in their nature.

This talk is based on the results of researches performed at the Thermion Company during last decade in both aforesaid directions. The typical temperature dependence of characteristics for different electro-optic elements are reviewed and their peculiarities as heat sources are analyzed. The progress in the development of extremely short-legged single-stage and cascade TECs having not only enhanced cooling power density but also possessing increased attainable temperature differences is presented. The peculiarities of a TEC operation as a part of electro-optic device are considered and the system analysis of a TEC coupled with a cooled object inside a sealed housing is given.

Numerous novel configurations of "cubic-type" multi-stage TECs with identical cascade dimensions for cooling planar electro-optic elements are presented. The concept of mixed series-parallel TE pellets connection is used which allowed to implement designs having equal number of TE legs in all cascades together with identical their topology what gives an advantage of unified technology and increased mechanical strength. The temperature differences which are achieved experimentally proved to be higher than those for traditional "pyramidal-type" TECs. Particularly, the low temperature 3-stage TECs with the top and the bottom of 12x12 mm destined for cooling multi element IR detector in a Mars-type mission are designed and manufactured. Their tests results are given and discussed.