Fresnel lens can focus light passing through a narrowband interference filter on the photoactive surface of a silicon photodiode detector

You will find a plastic hat on each PIR. This is the Fresnel lens, which refractions (reflects) the heat-release IR signal on the PIR Fresnel optical lens. The second role is to divide the exploration area into several bright and dark areas. The outside of the small hat is engraved with teeth.

Fresnel lens. It is easy to say that there is an equal distance tooth pattern on one side of the lens. This Fresnel lens can limit the frequency of the incident light to the Fresnel optical lens inside and outside 10 meters (the peak of the human body's red inner radiation). Ability to reach the light wave pass (reflective or refraction) for the designated spectrum category. Traditional band-pass optical filters for polishing optical devices are expensive. The Fresnel lens can greatly reduce the old Fresnel optical lens. A typical example is PIR (active red line detector). The old is equally low. If you take a look. The Fresnel lens has two functions: one is a focusing Fresnel optical lens.

The Fresnel lens can focus the light passing through the narrowband interference filter on the photosensitive surface of the silicon photodiode detector. The Fresnel optical lens passes through the tooth pattern.

The Fresnel lens is made of organic glass and formed by the Fresnel optical lens. This allows the moving animals entering the detection sea area to undergo changes in PIR on the way of measurement. Thermo-response infrared signal Fresnel optical lens can be used in the dusting with alcoholized water. Or general water rinse. Do not use any organic filtrate (such as ethanol, etc.) to wipe, PIR is widely used on the radar, and then wipe the cotton.