Can a blue transparent substance let blue light pass through? Using blue transparent material can let light except blue pass through, can it block other light, ni?

Blue transparent substance can let blue light pass, but blue transparent substance can't let other light pass, and can block other light.

The mechanism is as follows-

Function and filtering principle of optical filter

Optical filter is an optical device used to select the required radiation band. All filters absorb certain wavelengths.

Objective: To make natural imaging brighter.

Purpose: Used to select the required radiation band.

principle

The filter is made of plastic or glass, and special dyes are added. The red filter only allows red light to pass through, and so on. Glass sheets are almost as transparent as air, so they are transparent. However, after dyeing, the molecular structure changes, the refractive index also changes, and the passage of some colored light also 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.

function

Filters have played a great role. Widely used in photography. Why is the main scene always so prominent in the landscape paintings taken by some photographers? How do you do it? That's what filters are for. For example, if you want to shoot a yellow flower with a camera, the background is blue sky and green leaves. If you shoot according to the routine, you can't highlight the theme of "yellow flower" because the image of yellow flower is not prominent enough. However, if you put a yellow filter in front of the camera to block some green light scattered by green leaves and blue light scattered by blue sky, and a large number of yellow light scattered by yellow flowers pass through, the yellow flowers will be very obvious, highlighting the theme of "yellow flowers".

trait

Its main feature is that its size can be made quite large. Thin film filters that usually transmit longer wavelengths are often used as infrared filters. The latter is a low-order, multi-stage series solid Fabry-Perot interferometer. Metal-dielectric-metal films or all-dielectric films with high refractive index or low refractive index are alternately formed on a certain substrate by vacuum coating. The choice of material, thickness and series connection mode of the film depends on the required central wavelength and transmission bandwidth λ.

wavelength

Various interference filters with λ of 1~500 angstrom can be used at any wavelength from ultraviolet to infrared. The peak transmittance of metal dielectric film filter is not as high as that of all dielectric film, but the secondary peak and sideband problems of the latter are more serious. There is also a circular or strip variable interference filter in the thin film interference filter, which is suitable for space astronomical measurement. In addition, there is a dichroic filter, which is placed at an angle of 45 with the incident light beam, and can decompose the light beam into two different colors, with high and uniform reflection and transmittance, and is suitable for multi-channel multi-color photometry. Interference filter generally requires vertical incidence, and when the incidence angle increases, it moves to the short wave direction.

This characteristic can be used to adjust the central wavelength within a certain range. Because λ and peak transmittance change significantly with temperature and time, we must be very careful when using narrow-band filters. Because it is difficult to obtain a large area of uniform film, the diameter of the interference filter is generally less than 50 mm Someone once obtained a 38 cm square interference filter by splicing and installed it on the Schmidt telescope with British caliber 1.2 m to shoot a monochrome image of a large area nebula.

equipment

synchronizing function

This technology can control the camera, infrared light, filter and color to switch to black synchronously. Stability has the functions of automatic positioning and image stabilizer, and the light will not flicker when it is at the zero boundary. Fast switching in one step will not stop halfway because of resistance jam, which will lead to filter deviation. The filter will not move due to translation/tilt and rotation and stop of vibration. When switching at high speed, it will not rebound due to collision, resulting in inaccurate filter positioning. filter

Image color recovery function

Crystal filter can solve the problems of pseudo color and color cast to the maximum extent. The light transmittance of 98% can be achieved by adding AR-COOTRMG thick film on the crystal. Switching to the crystal filter state during the day can well sense visible light and prevent interference from infrared rays and other light. Bright and vivid colors, switching to the filter coated with transparent film at night can achieve 100% transmittance. The camera senses more infrared rays, most wavelengths of light can pass through, and the camera turns black at the same time, so the infrared distance is farther and clearer.

classify

Filter products are mainly classified according to spectral band, spectral characteristics, thin film materials and application characteristics.

Spectral band: ultraviolet filter, visible light filter, infrared filter;

Spectral characteristics: bandpass filter, cutoff filter, spectral filter, neutral density filter, reflection filter;

Membrane material: soft membrane filter, hard membrane filter;

Hard film filter not only refers to the hardness of thin film, but also refers to its laser damage threshold, so it is widely used in laser system, while surface soft film filter is mainly used in biochemical analyzer.

Bandpass type: the light in the selected band passes through, and the light outside the band is cut off. Its optical indexes are mainly central wavelength (CWL) and half bandwidth (FWHM). Divided into narrowband and broadband. Such as narrowband 808 filter NBF-808.

Short-wave pass type (also called low-wave pass): light shorter than the selected wavelength passes through, and light longer than this wavelength is cut off. Such as infrared cut-off filter, IBG-650.

Long wave pass type (also called high wave pass): light longer than the selected wavelength passes and light shorter than this wavelength is cut off, such as infrared transmission filter, IPG-800.

In the past, monochromatic light in photoelectric colorimetric determination was made of filters with different bands, but now it has been replaced by monochromator in spectrophotometer.