Joule-Thomson Cryostat Cooled Infrared Cell Having a Built-In Thermostat Sensing Element.
DEPARTMENT OF THE NAVY WASHINGTON D C
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A cryogenically cooled infra-red detection cell assembly comprises a Dewar-flask type of thermal insulation casing. The closed end of the Dewar casing is the front end of the assembly and is adapted to have a lead sulfide infra-red transducer mounted on the inside face of the casing inner end wall, and to have the casing outer end wall form a part of a lens system for focusing on the transducer. A Joule-Thomson cryostat projects into the casing so as to maintain liquid nitrogen adjacent the outside face of the inner end wall. The cold end of the cryostat is mounted to a metal mandrel, with the rear end of the mandrel serving as a mount for a small piece of gold-doped germanium. This piece of doped germanium acts as a variable resistance at the critical range of temperature control for the front end of the cryostat, and is operatively connected to a thermostat circuit which actuates the valve controlling the flow of gas into the cryostat.
- Infrared Detection and Detectors