The signal level output by the detector is a function of the target temperature, which is determined by the target radiation characteristics, the spectral transmission characteristics of the infrared imaging system, and the spectral response characteristics of the detector. Obviously, this function is nonlinear. However, in order to display the infrared image and the actual temperature, the temperature signal sent to the display terminal is required to have a linear relationship with the target temperature. Therefore, the signal voltage output by the detector should be linearized and corrected so that it has a linear relationship with the temperature.

 

The compensation of the ambient temperature is measured with a thermal element, and its signal level is approximately linearly related to the temperature. However, when this level signal is sent for temperature compensation, the relationship between the compensated temperature signal and temperature is nonlinear. Therefore, the linear ambient temperature should be nonlinearly processed to make it consistent with the nonlinearity law of the original temperature signal, and then compensated. Linearization circuits can consist of nonlinear potentiometers, diodes, and resistor networks.