Dichroic Beamsplitters

Dichroic beamsplitters are optical filters with high transmission at specific wavelengths, and high reflection at other wavelengths. They often have a steep cut off point between transmission and reflection bands, enabling them to be used to effectively split a beam of light by wavelength.

Dichroic Beamsplitters
Dichoric Beamsplitter

Types of Dichroic Beamsplitters and Their Applications

Longpass dichroic beamsplitters

Longpass dichroic beamsplitters reflect short wavelengths and transmit longer wavelengths. They can be used for fluorescent microscopy, to reflect excitation light toward a sample while emitted light passes through the filter. They can be used for beam combing in laser launches, or for Raman (Stokes), to reflect laser light toward a sample while transmitting the Raman signal. 

Shortpass dichroic beamsplitters

Shortpass dichroic beamsplitters are designed to transmit short wavelengths while reflecting longer wavelengths. You might want  shortpass dichroic filters if you were doing multi photon laser scanning, and your emission had a much shorter wavelength than the excitation laser.  You would also choose a shortpass dichroic beamsplitter  if you were doing second-harmonic imaging where light is emitted at half the laser wavelength. 

Multiband dichroic beamsplitters

Unlike longpass or shortpass filters, which have one reflection band and one transmission band, multiband dichroic beamsplitters have multiple regions of reflection and regions and transmission, alternating. These beamsplitters can be used for rapid laser switching or LED switching, among other uses.

Specifications of Longpass and Shortpass Dichroic Filters 

Key specifications of longpass and shortpass filters include:

  • Wavelength range of the transmission band, and the average percentage transmission for that band
  • Wavelength range of the reflection band, and the average reflection transmission for that band. This is often described in terms of blocking. 
  • Angle of incidence of the beamsplitter (45 degrees is the usual, but other angle of incidences are possible)
  • Cut on and cut off wavelengths (calculated as the wavelength at 50% of peak transmission)
  • Edge steepness describes the transition from transmission to reflection
Dichroic Beamsplitters
Dichroic Beamsplitters

Dichroic Beamsplitters

Custom Dichroic Beamsplitters at Avantier

At Avantier, we are fully equipped to produce custom dichroic beamsplitters that exactly meet your specifications. Whether you need a short-pass filter for second harmonic imaging or a long pass filter for fluorescent microscopy, we have you covered. We can produce beamsplitters with extremely narrow spectral band edge tolerances for maximum spectral stability. Our beamsplitters have low residual optical absorption losses, and we can produce beamsplitters with extremely high environmental stability. 

At Avantier, we don’t work with in-stock products and encourage you to get an optic that almost fits your application. Instead, we work with you to determine exactly what you need, and then produce that as a custom optic. That’s the Avantier difference— high quality, fully customized optics that precisely meet your specifications. Don’t be satisfied with something that almost works— get a custom made optics today. Contact us to place an order or schedule an initial consult with our experienced and personable optical designers.


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