Infrared thermal camera receives the infrared radiation from the object through the lens and reflects it on the detector to form an infrared image with temperature. Different colors represent different temperatures. Infrared thermal camera lens can pass through infrared, but ordinary camera can't. Why is the price difference between infrared thermal camera lens and ordinary camera lens so big? Why is this?

1. Ordinary camera lens material

The lens of an ordinary camera is usually made of optical glass, which refracts light to magnify objects. Optical glass is usually synthetic. The main reason why ordinary cameras are not sufficiently exposed to infrared light is probably the sensor, followed by the lens. The attenuation degree of ordinary camera lens to infrared ray mainly depends on the lens material, coating film and infrared wavelength, the infrared ray transmission amount close to visible light is relatively high.

2. Infrared thermal camera lens material

The lens of the infrared thermal camera is made of germanium glass. Germanium glass has good light transmittance in the 2-16 m band, and its chemical properties are relatively stable. It is not easy to react with metal oxides, acid substances, air and water. The working band of infrared thermal camera is 2-13 m, and germanium glass has good transmittance to the middle and far infrared. The transmittance of common optical glass is very low in these bands. Coating germanium glass with optical film can greatly increase the infrared transmittance and reduce the surface reflectance of germanium glass, but germanium glass is impervious to visible light band.

Germanium is a rare metal element, and the high concentration of germanium is very difficult to extract. Therefore, the production cost of germanium glass is relatively high, and its price in the market is higher than that of ordinary optical glass, which leads to the higher price of infrared thermographic lens than that of ordinary cameras.