Natural light and polarized light concept

Natural light: Vibration in any direction in the plane of vertical light wave propagation, and the amplitude of each vibration direction is equal, as shown in Figure 2-8 - 1a. That is to say, its vibration direction is on the one hand perpendicular to the direction of propagation of the light wave, and on the other hand it rapidly and irregularly changes its direction. The light emitted directly from the light source is generally natural light, such as sunlight, light, and the like.

Polarized light: A light wave that vibrates only in a certain fixed direction of the vertical direction of propagation, called plane polarized light, referred to as polarized light or polarized light, as shown in Figure 2-8-1b. The plane formed by the direction of polarization of the polarized light and the direction of propagation is called the vibration plane.

Natural light can be converted into polarized light by reflection, refraction, birefringence and selective absorption. The effect of converting natural light into polarized light is called polarization. Polarization is mainly used in crystal optics research. The main tool of the study is a polarizing microscope, in which there is a polarizer that causes natural light to become polarized. The polarizer is usually made by the principle of birefringence (Nicol prism or the like) or selective absorption (polarizer) to generate polarized light. After the natural light passes through the polarizer (polarizer), it is converted into a polarized light with a fixed vibration direction. .