| The cryogenic infrared target is the key device used to correct the responselinearity and uniformity of infrared. The infrared detector has to experience the severespace environment in the process of launching and working, so it requires excellentperformance such as high resolution, high linearity, high sensitivity, high spectralresponsibility, prefect uniformity and wide dynamic range and so on. As the keydevice of correct experiment, cryogenic infrared target needs wide temperaturevariation range as well as stable and uniform temperature distribution in a larger area.The cryogenic infrared target also demands other excellent performance such as hightemperature control precision and faster rate of temperature change.The temperature uniformity, temperature stability, emissivity, rate of temperaturecontrol and temperature precision were discussed according to infrared optical, heattransfer theory, principle of low temperature and vacuum in this paper. The keystructure of cryogenic infrared target, design of temperature control and analysis ofstray light were studied in this paper.Starting from the structure of the target, the transmission-type structure and thereflection-type was discussed. The cryogenic target system-temperature controlsystem-vacuum system was determined as the final structure. On this basis fourrefrigeration structures were designed for the cryogenic target system. And thetemperature uniformity of the blackbody and efficiency of refrigeration under therefrigerated condition was analyzed. For the best structure, the power needed forwarming and temperature field was calculated and analyzed. The results showed that,the structure was reasonable, and the indicators met the requirements.The digital PID control technology was analyzed in this paper. The temperaturecontrol system was designed for the cryogenic infrared target form hardware andsoftware. First of all, the temperature control system based on PLC and temperaturecontrol principles were discussed. In addition, the devices needed for temperaturecontrol system were chosen and the ports were assigned. Finally, the electric designwas given for the system. Then the flow chart of main program and subroutine weredesigned for temperature control system.Starting from three source of stray light, the stray light of the cryogenic infraredtarget was analyzed. And the method for analyzing the stray light was discussed inthis paper. The actual radiation and the ideal radiation which infrared can receive werecalculated and comparison with ray tracing. Finally, the radiation temperatures forparts of the temperature points were corrected by the form of radiation correctiontable. |
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