Introduction of prism

2020-06-24

1、 About prism

Prism is a polyhedron made of transparent materials (such as glass, crystal, etc.). It is widely used in optical instruments. Prism can be divided into several kinds according to its nature and application. For example, in the spectral instrument, the composite light is decomposed into "dispersion prism" of spectrum, and the more commonly used one is equilateral prism; in the periscope, binocular telescope and other instruments, the "total reflection prism" is used to change the direction of the light, so as to adjust the imaging position.


2、 Classification of prisms

Polyhedron made of transparent material is an important optical element. The plane of light incident is called the side, and 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 section of a prism is a triangle, which has two refraction surfaces. The angle between them is called the top angle, and the plane opposite the top angle is the bottom. According to the law of refraction, light passes through a prism and deflects twice to the bottom. The angle Q between the outgoing light and the incoming light is called the deflection angle. Its size is determined by the refractive index n and the incident angle I of the prism medium. When I is fixed, different wavelengths of light have different deflection angles. In visible light, the largest deflection angle is violet light, and the smallest deflection angle is red light.


3、 The discovery of prism

Newton discovered the dispersion of light in 1666, and the Chinese were ahead of the foreigners in this respect. In the 10th century A.D., the Chinese called the natural transparent crystal after sunlight "five light stone" or "light stone", and realized that "in the light of sunlight, five colors are like neon". This is the world's first understanding of the dispersion of light. It shows that people have liberated the dispersion of light from the mystery and know that it is a natural phenomenon, which is a great progress in the understanding of light. It's 700 years earlier than Newton's understanding that white light is composed of seven colors of sunlight through prism.


4、 The function of prism

(1). Common digital equipment: camera, CCTV, projector, digital camera, digital camera, CCD lens and various optical equipment

(2). Science and technology: telescope, microscope, level, fingerprint, gun sight, solar energy converter and various measuring instruments

(3). Medical instruments: cystoscope, gastroscope and various laser treatment equipment.