Main Parameters of Beam Splitters and Their Detailed Explanations

Main Parameters of Beam Splitters

Reflectivity ® and Transmittance (T) 

Reflectivity: It refers to the proportion of light reflected by the beam splitter.

Transmittance: It represents the proportion of light transmitted through the beam splitter.

Common splitting ratios include 10T:90R, 20T:80R, 30T:70R, 40T:60R, 50T:50R, etc. The splitting ratio can be customized according to specific requirements.

Substrate Material: The substrate material of beam splitters is usually optical glass, such as UV - grade fused silica optical glass, B270, and float glass.

One side of the beam splitter is usually coated with an anti - reflection (AR) coating to improve the light transmittance, while the other side is coated with a beam - splitting coating to achieve partial reflection and partial transmission of light.

Coating technology is crucial for the performance of beam splitters. High - quality coatings can improve the reflectivity and transmittance of the beam splitter, while reducing stray light and ghosting. 

Other Relevant Parameters of Beam Splitters

Focal Length: It is a measure of the convergence or divergence of light in an optical system. However, the beam splitter itself does not have the property of focal length. Focal length is typically used to describe the performance of optical elements such as lenses or convex lenses. 

Length: Beam splitters usually have a certain thickness and size, but the term “length” is not an accurate description. The size of a beam splitter can be represented by its diameter (for circular ones) or side length (for square or rectangular ones), and the thickness is an important physical parameter. 

Diameter Tolerance: The diameter tolerance of a beam splitter refers to the deviation range between its actual diameter and the nominal diameter. Diameter tolerance is of great significance for ensuring the mechanical accuracy and optical performance of the beam splitter.

High - quality beam splitters usually have a smaller diameter tolerance range. 

Surface Finish: The surface finish of a beam splitter refers to the smoothness and flatness of its surface. Surface finish is important for reducing the scattering and loss of light on the surface of the beam splitter.

A beam splitter with high surface finish can improve the light transmittance and reflectance, while reducing stray light and ghost images. 

It should be noted that the specific parameter values may vary depending on the type, application, and manufacturer of the beam splitter. Therefore, when selecting a beam splitter, it is necessary to determine the appropriate parameter values according to the specific application scenario and requirements.