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 the spectral instrument, the compound light is decomposed into the spectral “dispersion prism”, and the more commonly used is the equilateral prism; In periscope, binocular telescope and other instruments, it is called “total reflection prism” to change the direction of light and adjust its imaging position. Generally, right-angle prism is used.
Relevant definitions of prisms
The side of the prism: the plane of light incident and emitted is called the side.
The main section of the prism: the plane perpendicular to the side is called the main section. According to the shape of the main section, it can be divided into three prisms, right-angle prisms, pentagonal prisms, etc. The main cross section of a prism is a triangle. A prism has two refractive surfaces, and their included angle is called the top angle, and the plane opposite the top angle is the bottom surface.
According to the refraction law, the light passes through the prism and deflects twice to the bottom. The angle q between the outgoing light and the incident light is called the deflection angle. Its size is determined by the refractive index n of the prism medium and the incident angle i. When i is fixed, the light of different wavelengths has different deflection angles. In the visible light, the largest deflection angle is purple light, and the smallest is red light.
