Widely used in human body sensor switch, alarm, infrared thermometer and
infrared imaging and other aspects. It can provide users with different
sensing angles, sensing distances, sizes, and test ratios. Fresnel lens
function: first, focusing effect; The second is to divide the detection
area into several bright and dark areas, so that the moving objects
entering the detection area can produce a change pyroelectric infrared
signal on the PIR (passive infrared detector) in the form of temperature
changes.