A prisms is a polyhedron made of transparent materials such as glass, crystal, etc. It is widely used in optical instrument. Prisms can be divided into several types based on their properties and uses. For example, in spectroscopic instruments, a “dispersion prism” is commonly used to decompose composite light into spectra, and an equilateral prism is more commonly used; In periscope, binoculars and other instruments, changing the direction of light to adjust its imaging position is called “total reflection prism”, which generally uses right angle prism.
The side of a prism: The plane where light enters and emits is called the side.
The main cross-section of a prism: The plane perpendicular to the side is called the main cross-section. According to the shape of the main cross-section, it can be divided into three prisms, right angled prisms, pentagonal prisms, etc. The main cross-section of a prism is a triangle. A prism has two refractive surfaces, and their angle is called the top angle. The plane opposite the top angle is the bottom surface.
According to the Snell’s law, light passes through a prism and deflects twice to the bottom. The included angle q between the outgoing light and the incoming light is called the deflection angle. Its size is determined by the refractive index n of the prism medium and the incidence angle i. When i is fixed, light of different wavelengths has different deflection angles. In visible light, the largest deflection angle is purple light and the smallest is red light.
