激光是六十年代迅速发展起来的一门新技术。普通光源如电灯、日光灯、高压水银灯都是自发辐射发光,原子的自发辐射发光是彼此无关进行的。激光是受激辐射发光,激光器发出的光子具有频率、相位、传播方向、偏振态四同性。因而在宏观上与普通光源相比较,激光具有单色性好、方向性好、相干性好、亮度高等宝贵特点。为此,激光刚一问世,就引起了各国普遍重视,发展十分迅速。目前,从真空紫外到远红外波段, Laser was developed rapidly in the sixties a new technology. Ordinary light sources such as electric lamps, fluorescent lamps, high-pressure mercury lamps are spontaneous emission of light, spontaneous emission of atoms is independent of each other. Laser is stimulated by the radiation of light, the laser emits photons with frequency, phase, propagation direction, polarization state of the same sex. Thus compared with the general light source in the macro, the laser has a monochromatic, good direction, good coherence, high brightness and other valuable features. Therefore, just after the advent of the laser, it has aroused the universal attention of all countries and the development is very rapid. At present, from the vacuum ultraviolet to far infrared band,