What is the wavelength of the interference filter?

Understanding the Wavelength of an Interference Filter

What is an Interference Filter?

An interference filter is a device that selectively transmits light of a narrow range of wavelengths, effectively filtering out light of other wavelengths. This is achieved through the constructive and destructive interference of light waves, a principle that allows these filters to precisely control which wavelengths pass through.

How is the Wavelength Determined?

The wavelength of light that an interference filter transmits is primarily determined by the physical structure of the filter itself. This includes:

  • The thickness of the dielectric layers.
  • The refractive index of the materials used.
  • The angle of incidence of the light.

By adjusting these parameters, manufacturers can design interference filters to target specific wavelengths.

Typical Wavelength Range

Interference filters can be designed to target a wide range of wavelengths, from the ultraviolet (UV) through the visible spectrum and into the infrared (IR). The specific wavelength or wavelengths a filter is designed to transmit are often specified by the manufacturer and can vary widely depending on the application.

Measuring the Wavelength

To determine the exact wavelength of an interference filter, one would typically refer to the filter's specification sheet provided by the manufacturer. This document will detail the peak transmission wavelength(s) and the bandwidth (the range of wavelengths over which the filter is effective).


Interference filters find applications in various fields, including:

  • Photography and cinematography, for color correction and effects.
  • Astronomy, for isolating the light of specific stars or galaxies.
  • Biomedical imaging, for enhancing contrast in microscopic images.
  • Laser systems, for selecting specific laser lines.

In summary, the wavelength of an interference filter is a critical parameter that defines its function and suitability for specific applications. It is determined by the filter's design and can be found in the product's technical specifications.

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