Why use wavelength of 850nm an infrared led in infrared cameras

There are many different wavelengths of infrared transmitting tubes in led mark, withwavelength of 850nm ir led strip or 940nm ir led strips is main force. So why use 850nm wavelength infrared in  infrared cameras ?

First of all, we come to knowledge about infrared cameras. In simple word, infrared camera is used to sense infrared and Image forming, it can be divided into 2 types: one is the passive infrared cameras, mainly for the military; another is active, mainly civilian. Any objects in absolute zero(-273 ℃) above will emit infrared light, but the infrared intensity, so in here we can only use passive infrared camera to capture images. But passive infrared camera, the price is very expensive, so not suitable for civilian & household use. The active infrared camera is the use of infrared emission emitted infrared, infrared is adopting the infrared principle to capture images, so the price is cheaper. Active infrared camera can receive infrared distribution center wavelength as 830 – 950nm. Within this range, Thus The 850nm or 940nm wavelengths of infrared transmitting led are suitable for, can make an infrared camera with a red explosion and none red explosion. Therefore, Infrared cameras are therefore not only 850nm IR led can be used, and not with the others. The reason to use 850nm infrared led is 850nm wavelength sensitivity thanin the 940nm wavelength sensitivity to 10 times better. as well as transmit power range, distance farther, by contrast, 850nm this slightly red bursts of infrared tube more suitable for application on the infrared camera, , and thus become the mainstream.