Fresnel lens has two functions: one is to focus, that is, to refract (reflect) pyroelectric infrared signals onto PIR, and the other is to divide the detection area into several bright areas and dark areas, so that moving objects entering the detection area can generate changing pyroelectric infrared signals in the form of temperature changes on PIR. Fresnel lens is a widely used optical element. Its design and manufacture involve many technical fields, including optical engineering, polymer material engineering, numerical control machining, diamond turning technology and nickel plating technology. Molding, injection molding, casting and other manufacturing processes. You can learn about Nanyang Ba Sen Optoelectronics, which is a company specializing in producing Fresnel lenses.