| 摘要 |
PURPOSE:To compact an optical system and to improve an SN ratio by arranging a condenser lens on the infrared window side of a cold shielding room in a vacuum room. CONSTITUTION:Liquid nitrogen is injected into a container 2 formed in the vacuum room 1, the cold shielding room 4 having an infrared ray passing hole is formed on the lower part of an inside wall 1a and a semiconductor infrared ray detecting element 5 is fixed to the inside wall 1a contacted with the liquid nitrogen 3 in the room 4. Thereby, the temperature of the element 5 becomes -196 deg.C and infrared rays are not almost discharged from the element 5 itself and the vicinity of the element 5, so that the SN ratio can be improved. Since the condenser lens 14 is arranged on the infrared ray window 10 side of the cold shielding room 4, the light flux of the infrared rays can be reduced as compared with a measuring article and thereby a compact and inexpensive optical system can be obtained. |
