An equilateral triangular prism is an optical element characterized by having three equal sides, each of which is a normal plane. This type of prism is primarily used for the reflection and steering of light. All three sides of an equilateral triangular prism are normal to each other, so the reflection of light occurs on each side. When light is incident on one side of the prism, the light undergoes total reflection and then exits the prism on the other side. The outgoing light is rotated 90 degrees relative to the incident light without dispersion. Equilateral triangular prisms are usually made of glass or optical plastic. Applications for such prisms include optical measurements, laser technology, optical instrumentation, and optical biology.