A prism is a polyhedron made of transparent materials (such as glass, crystal, etc.). It is widely used in optical instruments. Prisms can be divided into several types according to their properties and uses. For example, in spectroscopic instruments, an equilateral prism is commonly used to decompose the composite light into a "dispersive prism" of the spectrum; in periscope, binocular telescope and other instruments, a "total reflection prism" is commonly used to change the direction of light so as to adjust its imaging position.
