Prisms on a surface splitting light

Beamsplitter

Beamsplitter

An optical device for dividing a beam into two or more separate beams. A simple beamsplitter may be a very thin sheet of glass inserted in the beam at an angle to divert a portion of the beam in a different direction. A more sophisticated type consists of two right-angle prisms cemented together along their hypotenuse faces, with one face already coated with a metallic or dielectric layer having the desired reflecting properties (e.g. the percentage of reflection and the desired color). An example that uses a three-way beamsplitting prism is color television cameras. Multilayer films are deposited on the interfaces to divert red and green light to two vidicons, leaving the blue image to pass through to the third vidicon tube.