Light is composed of various wavelengths. The wavelength range of light that human eyes can see is between 320nm and 760nm, but CMOS sensor chips can see light of most wavelengths. If CMOS processes all the light signals, the processed image will appear color cast to the human eye, for example, black is grayish, green is purple, etc. In order to correct this problem, it is necessary to wear "glasses" (650nm filter) on the CMOS sensor to filter out the infrared light invisible to the human eye, so the image seen by the human eye and CMOS is the same. When at night, because infrared lights are commonly used for supplementary light, the "glasses" (650nm filter) must be removed at night to allow infrared light to penetrate the CMOS surface, and at the same time filter out light other than infrared (850nm filter). This is to achieve the purpose of supplementary light at night time by infrared light, and at the same time increase the purity of night vision images.
So I call the IR-CUT is a 650nm filter and a 850nm filter switcher