| 摘要 |
PURPOSE:To perform evaluation based upon a photon background over a wide range in a short time without releasing a dewer from a vacuum by switching beams from two blackbody furnaces periodically on an infrared detector by using a mirror chopper. CONSTITUTION:A device consists of the blackbody furnaces 1 and 2 which are variable in temperature, the mirror chopper 3 which switches infrared radiations from the blackbody furnaces 1 and 2 periodically on the infrared detector 6, and the dewer 7 which has the detector 6, a cooling diaphragm 4, and a cooling filter group 5. The detector 6 detects a difference between values obtained by the infrared radiations from the blackbody furnaces 1 and 2 by the reflection factor of the chopper 3. The quantities of the photon background falling on the detector 6 and the infrared radiations made into an AC current are determined by the temperatures of the diaphragm 4, filter group 5, and blackbody furnaces 1 and 2. For the purpose,the temperature of the blackbody furnace 2 is set lower than that of the blackbody furnace 1 and then the quantity of the photon background is set by varying the temperature of the blackbody furnace 2. Consequently, the number of times of the releasing of the dewer 7 from a vacuum for variation of the photon background is decreased. |
