The function and principle of optical filters

The functions and principles of optical filters are as follows:

1. Function of optical filters

Optical filters play a great role and are widely used in the photography industry . For example, if you want to use your camera to take a picture of a yellow flower with a blue sky and green leaves in the background, if you take the picture as usual, you cannot highlight the theme of "yellow flower" because the image of the yellow flower is not prominent enough.

However, if you put a yellow filter in front of the lens to block part of the green light emitted by the green leaves and the blue light emitted by the blue sky, and allow a large amount of yellow light emitted by the yellow flowers to pass through, then the yellow flowers will appear very obvious. , highlighting the theme of "yellow flowers".

2. The 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, and so on. . The refractive index of the glass sheet is originally about the same as that of air, and all colored light can pass through it, so it is transparent. However, after being dyed with dye, the molecular structure changes, the refractive index also changes, and the passage of certain colored light changes.

Characteristics of optical filters:

The main feature is that the size can be made quite large. Thin film filters generally transmit longer wavelengths and are often used as infrared filters.

The latter is to alternately form high-refractive-index or low-refractive-index metal-dielectric-metal films, or all-dielectric films, with a certain thickness on a certain base using a vacuum coating method, forming a low-level film. The _multistage series solid Fabry-Perot interferometer. The choice of material, thickness and series connection method of the film layer is determined by the required center wavelength and transmission bandwidth λ.