| 摘要 |
PURPOSE:To measure an object having a wide temperature measured range with high accuracy by using a diaphragm having 100% surface reflectance and preventing an ineffective infrared ray from being made incident on a detecting element even if the F value of a lens is changed with the aid of the diaphragm. CONSTITUTION:The diaphragm 3 having 100% surface reflectance, where a passage hole whose diameter is variable is provided in the center, is arranged between the lens 1 and an infrared ray detector 2. A black body 4 is disposed around the detecting element 21 of the detector 2 and the diaphragm 3 and the black body 4 are positioned as if the black body 4 can be seen with the surface reflection of the diaphragm 3 by means of the detecting element 21. Then, only the light quantity of the infrared ray of the object which passes through only the passage hole provided on the diaphragm 3 is detected by the detecting element 21 and the ineffective light quantity of the infrared ray of a background is absorbed by the cooled black body 4 and also prevented from being made incident on the detecting element 21 by being reflected on the surface of the diaphragm 3 to 100%. By changing the F value with the aid of the diaphragm 3, the object having the wide temperature measured range can be detected without receiving the effect of the ineffective light quantity of the infrared ray of the background. |
