Prism, a polyhedron made of transparent material is an important optical component. The plane where light enters and exits is called the side plane, and the plane perpendicular to the side plane is called the principal section plane. According to the shape of the principal section plane, it can be divided into prisms, right-angle prisms, pentagonal prisms, etc. The principal section plane of a prism is a triangle, and there are two refractive surfaces. The angle between them is called the apex angle, and the plane opposite to the apex angle is the base plane. According to the refraction law, light passing through a prism will be deflected twice towards the base plane, and the angle 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 incident angle i. When i is fixed, different wavelengths of light have different deflection angles. Among visible light, the deflection angle is the largest for violet light and the smallest for red light. In modern life, prisms are widely used in digital devices, science and technology, medical instruments, etc. Common digital devices: cameras, closed-circuit television, projectors, digital cameras, digital video recorders, CCD lenses, and various optical devices; science and technology: telescopes, microscopes, level meters, fingerprint scanners, gun sights, solar converters, and various measuring instruments; medical instruments: cystoscopes, gastroscopes, and various laser treatment equipment.