Filter principle and function

Filter is an optical device that can selectively pass through or block specific wavelengths of light, and is widely used in various fields according to its specific optical characteristics. The following is a detailed introduction to the working principle and application of the filter:

 

How it works:

Absorption: Filters absorb light by absorbing specific wavelengths, such as in dye filters, dye molecules are able to absorb light in a specific wavelength range.

Transmission: The filter allows a specific wavelength of light to pass through, for example in an interference filter, through optical interference to enhance or weaken the transmission of a specific wavelength of light.

Reflection: Some coated filters are able to selectively block or transmit specific wavelengths of light by reflection.

Diffraction: Some special filters use the principle of diffraction to separate or emphasize specific wavelengths of light.

 

Types and Applications:

Select by wavelength:

Long wave pass filter (infrared filter) : Through long wavelength infrared radiation, often used in infrared photography and imaging fields.

Short-wave pass filter (UV filter) : through short-wavelength ultraviolet radiation, often used in ultraviolet lamps, ultraviolet sterilization and scientific research.

Bandpass filters: pass only a certain range of wavelengths, such as for spectral measurement and optical communication.

Band filter (absorption filter) : blocks a certain wavelength range of light, often used to eliminate ambient light interference of a specific wavelength.

 

Other types:

Polarizing filters: Transmit or block light in a specific polarization direction and are widely used in devices such as LCD displays, photographic lenses, and 3D glasses.

Thin film interference filters (optical interference filters) : Selectively enhance or weaken the transmission of light at specific wavelengths through the principle of optical interference.


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Application field:

Photography and video: used to improve the color of the scene, to prevent ultraviolet interference and to achieve special photographic effects.

Optical microscopes and telescopes: Used to improve image quality, reduce ambient light interference, and enhance observation at specific wavelengths.

Laser system: wavelength selection, collimation and focusing for laser output.

Optical communication: Used for wavelength division multiplexing and wavelength division scattering in optical fiber communication systems.

Medical imaging: Used for selective imaging of specific wavelengths in medical examination and imaging equipment.


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Scientific research: Used in spectral measurement, fluorescence microscopy and optical experiments in laboratory research. Filters play an important role in optical systems, selectively passing through or blocking specific wavelengths of light, it plays an indispensable role in color correction, optical imaging and optical measurement.


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