The working principle of the filter: The filter is made of plastic or glass and added with special dyes. The red filter can only let red light pass through, and so on. The refractive index of the glass sheet is originally similar to that of air, and all colored lights can pass through, so it is transparent, but after dyeing the dye, the molecular structure changes and the refractive index also changes, and the passage of certain colored lights changes. For example, a beam of white light passes through a blue filter and emits a beam of blue light, while green light and red light are very few, and most of them are absorbed by the filter. The filter is used to filter out the light in a certain wavelength range and acts as a monochromator, but it is impossible to obtain monochromatic light.
The function of the filter:
1. Filter out infrared rays.
2. Trim the incoming light
Filter out infrared:
Color CCD can also sense infrared light. Because it can sense infrared light, it will cause the DSP to fail to calculate the correct color. Therefore, a filter must be added to separate the infrared part of the light. Therefore, only the color CCD needs to be equipped with a filter, black and white No need.
Trim into the light:
Because the CCD is composed of photoreceptors (CELL), it is best for the light to come in directly, but in order to fear that it will interfere with the neighboring photoreceptors, the light needs to be trimmed, so the filter is not glass, but quartz The film uses the physical polarization characteristics of quartz to retain the direct part of the incoming light, and reflect off the oblique part to avoid affecting the photosensitive spot next to it.
Post time: Aug-20-2021