PURPOSE: To obtain method and apparatus for measuring the degree of vacuum in a vacuum case for infrared detector in which variation in the degree of vacuum can be measured accurately and the duration of vacuum can be measured and evaluated accurately in a short term.
CONSTITUTION: The apparatus for measuring the degree of vacuum in a vacuum case 3 comprises an infrared detector 1, and a temperature measuring diode 2 outputting an electric signal corresponding to the detected temperature. The apparatus for measuring the degree of vacuum in a vacuum case 3 further comprises a cooler 10 for cooling the detector 1 with a constant power, a voltmeter 20 for detecting the voltage value of an electric signal outputted from the diode 2, a memory section 21 for storing a data indicative of the relationship between the degree of vacuum measured before sealing the vacuum case 3 and the temperature corresponding to a voltage detected by the voltmeter 20, and an arithmetic section 22 for operating the degree of vacuum based on a data stored in the memory section 21 and a temperature corresponding to a voltage detected by the voltmeter 20 after sealing the vacuum case 3.
FUJII HIDEKI
KIYOTA TAIJIRO
