| 摘要 |
PURPOSE:To suppress the generation of noise even when a Dewar window vibrates, by mounting a projected part, which is formed so as to project to the outside from the side cylindrical part of a cold shield, to the end surface opposed to the Dewar window of the cold shield. CONSTITUTION:A projected part 4d projecting to the outside from the side cylindrical part 4a of a cold shield 4 is formed to the end surface 4b opposed to a Dewar window 2 of the cold shield 4. Therefore, since infrared rays 6, 7 emitted from the outer cylinder 1a of a Dewar 1 are blocked by the projected part 4d, said infrared rays are not incident on a quantum type infrared detection element 3. In place of said infrared rays 6, 7, the infrared rays 8, 9 emitted from the projected part 4d are reflected from the inner and outer surfaces of the window 2 to be incident on the element 3 but, since the shield 4 is cooled, the radiation quantity of the infrared rays 8, 9 is so little as to be make negligible and, therefore, the quantity of the infrared rays incident on the element 3 does not almost change even when the window 3 is vibrated and the generation of noise can be suppressed. Further, the same effect is obtained even when the window 2 and the projected part 4d etc. are composed of a flat plate or a curved plate. |
