Light wavelengths & camera 
In Nature,There are a variety of light wavelengths, from refraction of human eye can see different colors of light, which is caused by different wavelengths of light.  In fact, there are many rays are invisible to the human eye, the eye detection wavelength of light in the range of 320nm-760nm,
larger than 760nm is light that human eye can not see the light, such as infrared light by ir led stripsWith the progress of science, the invention of the camera, the camera can see most of the light wavelengths in theory,but in the process of using the camera on the emergence of a problem, due to a variety of mixed light,the camera can see objects reflected on the monitor that the human eye is different. Such as the human eye to see the green, through the camera then turns blue, produce color distortion.   In the past, in order to solve the problem of color distortion, in generally the CCD with a filter, the filter hampers infrared light mobility, color distortion during the day, but at night but not the night vision function.IR CUT is a kind of mechanical device, has two windows, one side for the  filter On the other side is a transparent glass,can be adjusted easily as needed. so the color distortion during the day , and the night is still a night vision function.