The thermopile and passive infrared sensor that are using for motion sensor detects the wavelength of 8~13um.
Without Fresnel lens, the sensor only can detect less than 1m distance and narrower space with lens.
To work with Pyroelectronic detector and thermopile ,Fresnel lens that collects infrared rays as a sensor is required.
Fresnel Factory manufactures Fresnel lenses for passive infrared absolute temperature sensors.
Material is important to have a wide FOV and excellent Far infrared transmittance. Therefore, Fresnel Factory is using Poly FIR200 and Poly FIR25,which have a wide FOV and excel FIR transmittance.
