Fresnel lens
For us, Fresnel lens seems a bit unfamiliar, but it is present in our real lives, for this we need to understand it further, so as to make better use of it to create value for our mankind. Therefore, today I'll talk about classification of Fresnel lenses and other related content. Hope to be able to bring more help to your lives, so as to make progress in life. The Fresnel lens also known as thread lenses, are made from optical molding polyolefin material with thin slices, which also made of glass, one side with lens is smooth ,and the other side burn from small to large concentric circles, its texture is designed based on optical interference and disturbance shot angle, and relative sensitivity and receive requirements ;Requirements of Lens is very high. A high quality lens to smooth surface, texture clear, thickness changing with usage, 1mm, characteristic for the area, the thickness of thin and long detection distance. Fresnel lenses in many cases the equivalent of convex lens infrared and visible light, the result is better, but the cost is much lower than the normal convex lens. Used in many occasions for high accuracy requirements , such as projectors, infrared detectors, thin film magnifying glass Fresnel lens can be classified according to optical design or structure ; Fresnel lens has two effects: first is focusing action; the second is to divide the detection into a number of bright area and dark area, which make the moving object making access to the detection areas can be showed thermal infrared signals in the form of temperature change in the PIR (passive infra-red detectors)
