A beam splitter refers to any device that can split light beams in two different directions. Beam splitters are usually made of glass, which is formed into a cube. Half of the beam goes through the glass when light is shone onto the cube, while the other half is reflected.

Beam splitters have been used in physics experiments, such as those that involve measuring the speed of light. One of its real-world applications is in the field of fiber optic telecommunications. Your broadband Internet connection might be problematic without a beam splitter. Beam splitters are also present in optical equipment, such as microscopes, binoculars, cameras, and telescopes.

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Beam splitters commonly come in the form of a cube but can also be made as a plate. We differentiate the two in the illustration below.

beam splitters

Both beam splitters are made of glass, and at first glance, the only difference between them is their shape. However, there are other significant differences between cube and plate beam splitters. These are:

  • Angle: The cube beam splitter has an angle of interference of 0° so it’s easy to integrate into different equipment. Plate beam splitters are, meanwhile, angled at 45° so alignment may be necessary for specific applications.
  • Weight: Plate beam splitters are relatively lightweight as they are, after all, made of only one plate of glass. On the other hand, cube beam splitters comprise two right-angled prisms cemented together. Therefore, it is heavier.
  • Cost: Because of how it is constructed, a cube beam splitter is more difficult and expensive to manufacture than a plate beam splitter.

How Are Beam Splitters Made?

By now, you may think that beam splitters are complicated to make. That may be true for beam splitters that need to be integrated into optical equipment. But at its simplest form, a beam splitter can be formed by gluing two triangular glass plates together.

In the video demonstration below, the person could even make a beam splitter using a plastic container. As he said, you can make a better beam splitter with better glass material.

Types of Beam Splitters

Aside from its form (cube or plate), a beam splitter can also be categorized according to how it splits unpolarized light. Examples of such include LED lights, sunlight, incandescent light bulbs, and other natural light sources. 

Most beam splitters are designed to receive unpolarized light and can be grouped into two—polarizing and non-polarizing beam splitters.

  • Polarizing beam splitters: This type of beam splitter can split unpolarized light into two polarized beams.
  • Non-polarizing beam splitters: These beam splitters do not care about polarization. They only split light beams without changing the light’s polarization state.

What Are Beam Splitters Used For?

As has been said, beam splitters have several real-world applications and are also used in physics experiments. In an experiment in 1851 performed by Hippolyte Fizeau, a beam splitter was used to measure the speed of light in water.

At present, one of the most crucial applications of beam splitters is in fiber optics and broadband connections. They are used to split ultraviolet (UV) light and reduce interference. In particular, beam splitters are integrated into interferometers, which are devices used to measure interference.

Microscopes also benefit from beam splitters that come in the form of multiple camera adapters. This device allows a sample to be captured by two cameras. Half of the light from the microscope is reflected in one camera. In contrast, the other half is transmitted to another camera.

Your color TV even uses beam splitters to distribute light and form green, red, and blue images. 

The concept behind beam splitters may be easy to understand. Simply put, these devices are used to split light into different directions. However, its applications are varied and, at times, complicated.