What are the application scenarios of infrared lenses?

  What are the application scenarios of infrared lenses corrected by special materials? Come and learn about the relevant content with the editor of Fuqing Optical Lens!

1. All-weather surveillance camera

The most minor use of infrared lenses is to complete all-weather surveillance. The optically corrected infrared lens can focus clearly during the day, and usually needs to be refocused in the morning. The infrared lens corrected by a special material can make visible light and infrared focus to the same focus, so after the focus is clear during the day, the infrared lens is turned on at night. The fill light can still image clearly.

Second, through the fog

Fog penetration originates from the monitoring requirements in long-distance and complex environments. Fog is composed of coarse particles floating in the air. The more particles per unit volume, the denser the fog. Visible light has shorter wavelengths and cannot penetrate mist, which is why visibility is very low on foggy mornings. The wavelength of near-infrared light is longer, and this feature enables infrared light to diffract huge particles and complete the purpose of fog penetration.

In the fog-through mode, the filter will filter out the visible light and only save the infrared light. With the coating anti-reflection technology, the fog-through lens can also complete long-distance all-weather monitoring under the condition of low visibility, and in the normal and fog-through modes. Keep the focal plane from shifting.

3. Laser night vision

Laser is a highly concentrated monochromatic light, so long-distance night vision monitoring can be realized by using infrared laser. The laser beam scans the object, the object reflects the beam back, and the image can be imaged after being focused by the lens. Infrared lasers are usually used, and their wavelengths are in the near-infrared wavelength range, so infrared lenses must be used to cooperate with laser equipment. The infrared lens corrected by special material can penetrate 950nm light source, and can realize ultra-long-distance night vision monitoring when used with infrared laser.

Factors to Consider When Choosing an IR Lens

1. The importance of infrared lenses

The lens is an indispensable part of the thermal imaging camera. Its function is to focus the infrared radiation of the target on the infrared detector, and after photoelectric conversion and image processing, a good contrast image is finally formed. The quality of the infrared lens largely determines the performance of the infrared camera.

2. Factors to Consider When Choosing an IR Lens

1. Band

Infrared lenses should be specially designed according to their operating band to optimize their performance. The infrared materials used in infrared lenses of different wavelengths are also different.

2. Vignetting

Generally speaking, IR lenses do not allow vignetting. For the lens used in the infrared cooling detector, if the lens has vignetting, it cannot meet the 100% cold aperture efficiency design principle, and the stray radiation will affect the performance of the infrared thermal imager.

3. Focal length and field of view

Infrared lenses are usually identified by their focal length. As the focal length increases, the field of view of the lens narrows. Conversely, as the focal length decreases, the field of view widens.

Infrared lenses can generally be divided into single-field lenses, multi-field lenses, and continuous zoom lenses. Since the infrared continuous zoom lens can realize target search and continuous tracking of targets at different distances, it has been widely used in many fields.

4. F-number

The F-number of the infrared lens determines how much radiant energy from the target enters the thermal imager. The smaller the F-number, the larger the size of the infrared lens at the same focal length.

5. Transmittance

Most infrared materials have a high refractive index, and the lenses in the infrared lens need to be coated with a high-efficiency anti-reflection coating to increase the transmittance of the infrared lens. As the number of lenses in the lens increases, the light transmittance of the lens gradually decreases.

6. no heating

Since the refractive index of infrared materials varies greatly with temperature, when the ambient temperature changes, the Athermalized Lens will produce corresponding defocusing. The infrared lens also adopts active and passive methods to achieve athermalization to ensure the focal position of the lens when the temperature changes.