What's the difference between a dichroic filter and a beamsplitter?

Difference Between a Dichroic Filter and a Beamsplitter

Dichroic Filter

  • Function: Designed to selectively pass light of a small range of colors while reflecting other colors.
  • Usage: Commonly used in fluorescence microscopy, projectors, and lighting systems.
  • Construction: Made by depositing many thin layers of dielectric material on a glass substrate. The specific layer structure determines the wavelengths that are reflected and transmitted.
  • Directionality: Has a specific orientation; the coated side must face the source of light for optimal performance.
  • Transmission and Reflection: Transmits light of certain wavelengths while reflecting others, based on the design.


  • Function: Designed to split incoming light into two separate beams, which can be equal or unequal in intensity.
  • Usage: Widely used in optical experiments, laser systems, and imaging applications.
  • Construction: Can be made of glass or other transparent materials, with a coating that partially reflects and transmits light.
  • Directionality: Generally non-directional, meaning it can be used in any orientation.
  • Transmission and Reflection: Splits incoming light into two paths, typically at a specific ratio like 50/50, but other ratios are also possible.

Comparison Table

Feature Dichroic Filter Beamsplitter
Function Selectively passes or reflects wavelengths Splits light into two beams
Usage Fluorescence microscopy, projectors Optical experiments, laser systems
Construction Dielectric layers on glass Coated glass or transparent material
Directionality Directional Non-directional
Transmission/Reflection Wavelength-specific Ratio-specific (e.g., 50/50)
Back to blog