Introduction to Beam Splitter and its design

Introduction to Beam Splitter:

Beam Splitter:

A beam splitter can be simply defined as an optical device that splits up or divides a beam of light in two. It is a very important part of many measurement systems and optical experiments, such as interferometers, also finding a wide range of applications in fiber optic telecommunications.


Beam-Splitter designs:

A cube is the most common form, a beam splitter is composed of two triangular glass prisms that are glued together at their bases using polyester, epoxy, or urethane-based adhesives. (Prior to these synthetic resins, natural resins were used, such as Canada Balsam). The width of the resin layer is controlled (for a certain wavelength) in order to make the half of the light incident through one “port” (i.e., the face of the cube) is reflected back and then the transmission of the other half takes place due to FTIR (Frustrated Total Internal Reflection). There are many polarizing beam splitters available in the market, such as Wollaston prisms, which use bifurcating materials to split light into two beams of orthogonal polarization states. There are many beam spliter available in the market which takes the advantage of the industrial optical mirrors advanced process and the light which is circularly polarized light through linear polarizer intensity.

The half-silvered mirror is used to create another design. It basically consists of an optical substrate, in most cases, it is a sheet of plastic or glass, with a partially coated thin material. This thin layer of coating can be of aluminum deposited from aluminum vapor using a physical vapor deposition method. The thickness of the deposit is controlled so that part (usually half) of the light that is incident at a 45° angle is not absorbed by the coating or substrate material and the rest is reflected. In photography, a very thin half-silvered mirror is used which is known as a pellicle mirror. Swiss-Cheese beam-splitter is used in order to reduce the loss of light that happens due to absorption of the reflective coating.

Originally, these were sheets of highly polished metal that were punched with holes to achieve the desired ratio of reflectance. Later, the metal was sprayed onto the glass to form a discontinuous coating, or small areas of a continuous coating were removed by chemical or mechanical action to produce a very «half-silver» surface.

A dichroic optical coating may be used instead of a metallic coating. The ratio between the reflection to transmission changes as the function of the wavelength of the incident light which depends on its characteristics.