Why can CCD see infrared light?

In fact, in the CCD, it is sensitive to infrared light and can see infrared light, for example: using a black and white camera, when the bright electric light is turned off, turn on the infrared light, you can immediately see the image. This is because black and white cameras are inherently colorless, but most color CCDs used in reality do not see infrared light. In fact, the color CCD can also recognize and sense infrared, but it will interfere with the operation of the DSP (image processing main chip) to cause "color cast". Therefore, in order to make it not "color cast" in the color CCD, the color CCD The filter sticking on top prevents it from receiving infrared rays.

Figure:

This is the transmittance of the filter for each wavelength of light.The horizontal axis is the wavelength, expressed in nanometers (nm), and the vertical axis is the transmittance. It is just the range of visible light (purple-indigo-blue-green-yellow-orange-red), which is the color of the rainbow! More than 600 nm is red light, and it is called "infrared" when it is "outside" to the right. "Light other than red" is not red light, because the eyes can no longer see it. Then, what our eyes see is purple around 380nm. At 380nm, the left is "outside", which is called "ultraviolet".

From the picture above, we can see that the filter has blocked the infrared and ultraviolet light, and only the visible light comes in. Therefore, the infrared light cannot be seen by the color CCD.