Infrared optical lens

Infrared optical lens is a critical configuration of the infrared optical system, which directly affects the performance of infrared camera. Infrared lens collects infrared radiation actively emitted by the target and focuses it on an infrared detector. Then the infrared radiation is converted into electrical signals by the infrared detector. Through video processing and other processes, the thermal image of the object is presented on a display. This article mainly provides you with a detailed understanding of the focal length, types of infrared lens, field of view, relative aperture, F-number, material and other parameters of infrared optical systems.

1.Focal length

Focal length refers to the distance from the optical center of a lens to the focal point of light, which directly determines the detection performance and size of infrared thermal imaging equipment.

2. Types of infrared lens

There are various classifications of optical lenses. According to whether the focal length can be changed, there are fixed focus lenses and zoom lenses. According to different application scenarios, it can be divided into telephoto lens and wide angle lens. For example, in the application of security monitoring, border and coastal defense, the telephoto lens is generally used for long-distance monitoring of large scenes. While the wide angle lens should generally be used in industrial testing, fire rescue, smart home and other fields.

3.Field of view

Field of view refers to the angle of view in the physical space observed by an optical system, which varies with the focal length. As the focal length increases, the field of view narrows. On the contrary, the field of view will become wider.
According to the field of view, it can generally be divided into full field of view, horizontal and vertical field of view.

4.Relative aperture

Relative aperture is an important parameter of the optical system's focusing ability, which is the ratio of the aperture to the focal length. The larger this value, the more thermal radiation the infrared detector receives.

5.F numbers

F-number is the reciprocal of the relative aperture of an optical system. At the same focal length, the smaller the F-number, the more infrared radiation is obtained, and the higher the sensitivity of the thermal imager.

6.Material

Infrared lenses generally use materials such as Ge, Si, ZnS, and ZnSe. In recent years, sulfur based glass has attracted much attention in the application of infrared systems due to its cost and process advantages. The advantages of wafer level WLO technology in mass production, size and cost are increasingly evident.

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