The radiant energy of the human eardrum mainly comes from the 6~15μm area.

Ear thermometers usually use a thermopile sensor, which contains the above-mentioned optical system, photodetector-thermopile, thermistor.

The thermopile sensor detects the far-infrared radiation intensity of the human eardrum from 6 to 15 μm. This measurement result is a relative quantity, that is, the obtained result is related to the radiation intensity of the measured object and the temperature of the thermopile itself.

The thermistor is used to measure the temperature of the thermopile itself.

By calculating the radiation intensity and the temperature of the thermopile itself, the temperature of the measured object can be obtained.