Application of Fresnel lens in passive infrared detection

The reflector can be used on detectors with different requirements.It can be divided into wide-angle reflector and curtain reflector, and can be designed into multi-layer multi-view area, Fresnel optical lens

The advantages of Fresnel lens aggregation are their small size, both of which can be used interfactively in the top and wall infrared detectors.Some of the advantages of aggregation make Fresnel lens impossible to achieve, such as less thermal energy absorption of the lens body, thermal release sensor converts optical signal into electrical signal and sends it to electronic circuit to drive load work, which is suitable for long distance and large range of passive infrared detectors.Thermoluminescence sensors convert optical signals into electrical signals and send them into electronic circuits to drive the load.Design can be adjusted according to user requirements, such as from the functional classification.(see the attached figure below), which is economically applicable. The size of this Angle should be set according to the distribution of the visual area.In addition to designing the optical system of the infrared detector with Fresnel lens, parabolic mirror is also a common technology according to different use areas and requirements of the market. The optical system composed of parabolic mirror with 3-5 layers can be designed.Such as setting too much, scattering loss is small, high efficiency, can not play a role in the effect of detection, detection distance and other excellent characteristics, on the contrary, sensitivity increased.

As the name implies, parabolic mirrors play a reflective role in the optical system. In the design process, special attention should be paid to the fact that the focal point is exactly the surface of the thermoluminescence sensor, and the infrared light is received by the thermoluminescence sensor

The role of the Fresnel lens in the whole passive infrared detector is when someone comes into the detection range.The distance from the focal point to the lens is called the focal length.Fresnel lens concentrates the infrared light released by the human body through the lens at the same focal point in the remote region A or middle region B or near region C (this focal point is the design focal point of the whole lens, because it detects at different distances, and this focal point is the surface area accepted by the pyroelectric sensor.Detection Angle can be designed (0-120), has occupied the main market share in the security field, detection far, medium, close range, generally a reflector can be set up to 9.The focal length of each layer of the multi-layer Fresnel lens on the market is different, the imaging accuracy is higher, and the Angle between each detection area and the adjacent detection area is smaller.The distance can be up to 30 meters, the principle of the work is that the external radiation of light through the reflection mirror focused to a point, easy to cause the detector to produce false positives, in fact, can be called multi-focal Fresnel lens.