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Optical Filters and their Types


An optical filter is a substance that allows a specific wavelength and frequency of light to pass through it. It allows a specific set of the light spectrum to pass and stops the other portion from passing through it. 

Alluxa Optical Filters provides the best quality filters and coated thin films. It was established in 2007 and since then, it has grown up rapidly from a small startup to world-class manufacturer of optical filters.


Ideal optical filters are those that have very sharp cut-off characteristics. Such that they can exactly transmit a certain specified set of frequencies and wavelengths and totally prevent the set of wavelengths and frequencies outside that band. The phase spectrum of an ideal optical filter is linear.


The optical fibers are divided into two categories based on their operations. They both have different kinds of mechanisms.


Absorptive Filters: 


  • They are the simple type of filters that can be coated on both glass and plastic.
  • They have a coating of different organic and inorganic materials that absorbs a certain set of light frequencies.
  • The temperature of the optical filters increases as they absorb light energy.
  • The operation of these filters depends upon the material used in its mechanism.
  • Its operations do not depend on the incident angle of light.


Dichroic Filters:


  • These are more complicated types of filters than absorptive filters.
  • The operation of the dichroic filter is more complex than the absorptive filter.
  • They have a set of coating of different thicknesses that is called the transmission side and reflection side.
  • The wavelengths that are desired to pass strike on the transmission side of the filter.
  • While the wavelengths that are desired to block strike on the reflection side of the filter.



  • Short-Pass Filters: These are the type of edge filters that are designed to block long wavelengths and allow wavelengths that are shorter than the given cut-off wavelengths. The transition point for transmission and prevention is called the cut-off wavelength.



  • Long-Pass Filters: The type of edge filters that are designed to allow the longer wavelengths and block the shorter wavelengths. These filters work completely opposite to short-pass filters. They allow the wavelengths that are longer than the given cut-on wavelengths and block those that are shorter than it. The transition point for transmission and blocking is called cut-on wavelength.



  • Band-Pass Filters: The type of filters that allow the transmission of a specific range of light frequencies varying from narrow band frequencies to wideband frequencies. It can filter out frequencies of visible light, invisible light, infrared wavelengths, and ultraviolet set of light frequencies.



Optical filters play an important role in laser experiments such as laser safety glasses which are used for the protection from laser radiations. They can be used for the enhancement of images.

It can split images into two identical images. You can transmit images by using optical filters. They are used to improve the Reman spectroscopy by using optical filters. The monochrome cameras cannot differentiate between colors, so different optical filters are used to increase the contrast and color quality of an image.

Alex Carey
Alex Carey is working as a Content Marketing Specialist at The Technoverts. He loves to write and share content related to the latest technical research. He is also a soccer lover.


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