Pyrometer An instrument that measures higher temperatures. The two most important are optical pyrometers and radiation pyrometers.
In the optical pyrometer, the filament is heated to the calibrated heat, and compared with the color of the high-heat object, the heat of the filament is adjusted so that the color is consistent with the high-heat object, and the temperature of the filament is the temperature of the high-heat object.
In a radiation pyrometer, the radiation from an object is concentrated on a thermopile, and a corresponding voltage is generated according to the amount of thermal radiation intercepted, and then the voltage is converted to the temperature of the object.

Pyrometers come in two forms:
1) A device for measuring the temperature of a molten pool, comprising: a refractory mounting sleeve and an optical pyrometer;
2) Generally refers to the thermometer used to measure the temperature higher than 500℃. Commonly used pyrometers include optical pyrometers, colorimetric pyrometers, and radiation pyrometers.
In addition, thermocouple thermometers can also be used to measure high temperatures below 3000°C. But because the measuring range of thermocouple thermometer can be as low as -200 ℃, it is generally not classified as a pyrometer.