CO2 laser is a molecular laser that can excite laser beams in the far infrared range of 9~11μm. It works in both pulsed and continuous modes. Time constant is an important index to ensure thermoelectric dynamic performance. In order to verify that the dynamic performance of WRe film thermocouple is better than that of ordinary K-type thermocouple, it has a fast response and a short time constant. The tset system consists of CO2 laser, shieldingbox, elliptic mirror, thermocouple, infrared detector and acquisition circuit. A pulsed CO2 laser with a laser wavelength of 10.6 μm is used as the excitation heat source to act on the thermal junction. Time constant dynamic test was carried out on tungsten-rhenium thin film thermocouples WRe3/25 and ordinary K-type thermocouples with a thickness of micron.The time constant testing method of thermocouple can be intuitively obtained by making a tangent line at the highest point of the response curve, and the intersection point of the tangent line and the horizontal axis of the coordinate is the time constant value of the thermocouple. The experimental results show that the WRe film thermocouple has a faster response time and a smaller time constant. Therefore, the conclusion that this thin film thermocouple has better dynamic characteristics than the ordinary K type thermocouple is verified.
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