A narrowband beamsplitter cube is an optical device used to split a beam of light into two or more separate beams based on the wavelength or frequency of the light. It is designed to work within a specific, narrow range of wavelengths, typically in the visible or near-infrared spectrum. Beamsplitter cubes are commonly used in various optical instruments and applications, including microscopy, spectroscopy, and laser systems.

Here’s how a narrowband beamsplitter cube typically works:

  1. Cube Design: The beamsplitter cube is usually made of a high-quality optical glass or crystal material, such as BK7, fused silica, or other specialized materials with specific optical properties.
  2. Dielectric Coating: The cube’s surfaces are coated with a dielectric coating, which is designed to have a high reflectance for a certain range of wavelengths and high transmittance for another range of wavelengths. The specific design of the coating determines the narrowband spectral characteristics of the cube.
  3. Incoming Light: When a beam of light enters the beamsplitter cube, a portion of the light is transmitted through the cube, and the rest is reflected at a right angle. The division of light between transmission and reflection depends on the cube’s coating and is typically specified as a percentage, such as 50/50 (equal division) or other ratios.
  4. Wavelength Dependence: The beamsplitter cube is designed to be wavelength-dependent, meaning it works optimally within a certain range of wavelengths. Light within this range will be split into transmitted and reflected beams according to the cube’s specifications, while light outside this range may behave differently.
  5. Applications: Narrowband beamsplitter cubes are used in various optical setups where it’s necessary to separate or combine light of specific wavelengths. For example, in fluorescence microscopy, a beamsplitter cube may be used to separate excitation and emission wavelengths, allowing researchers to observe specific fluorescence signals.
  6. Polarization Considerations: Some beamsplitter cubes are designed to be polarization-dependent, which means they may behave differently for different polarization states of light. This can be advantageous in applications where polarization control is important.

Narrowband beamsplitter cubes are precision optical components, and their design and manufacturing require careful consideration of the desired wavelength range, the angle of incidence, and other factors. Choosing the right beamsplitter cube for a particular application is crucial to ensure optimal performance and accurate results.

Factory Standard


Schott, Ohara, CDGM Optical Glass, Corning fused silica, JGS1, JGS2


+/- 0.2mm


l/4 @ 632.8 nm

Surface Quality

60/40 scratch and dig

T/R, T=(Ts+Tp)/2, R=(Rs+Rp)/2

50/50+/- 5% for natural light

Beam Deviation

<3 arc minutes


Single wavelength partial reflectance on hypotenuse face “V” AR-coatings: on all input and output face

Avantier’s narrowband beamsplitter cube is a precision optical device designed to split light based on wavelength, functioning within a specific range. Made from high-quality materials like Schott and fused silica, it offers precise dimension tolerance, flatness, and surface quality. With a 50/50+/- 5% T/R ratio for natural light, minimal beam deviation, and specialized coatings, it suits applications like microscopy and spectroscopy. Our cube enables accurate wavelength-dependent light manipulation, essential for optical research and analysis. Please contact us if you’d like to schedule a consultation or submit a request for quote on your next project.


Contact us NOW for sales & expert advice.