Infrared light in what place to use appropriate, infrared light has what function?

The core component of the infrared sensor light is a pyroelectric infrared sensitive device, which is sensitive to the infrared rays emitted by living beings, and can output a switching signal after receiving it. In order to increase its working distance (improve sensitivity), it is usually equipped with a hemispherical Fresnel lens in front of it.

The pyroelectric infrared sensor switch can be made together with lamps to form a whole infrared sensor light; it can also be put on the lintel of an automatic door to control the opening and closing of the door; the location-specific alarms in the bank also use it to detect intruders - just detect and alarm, different from the surveillance camera.

Blocking the Fresnel lens with a thicker plate makes the light undetectable in infrared, but it's not easy to operate. If you need to change its function, you might as well just replace the regular lamp.