前言激光是六十年代发展起来的一种新光源,是受激发射而产生的能量高度集中的光。激光和普通光有其相同之处,都有一定的能量,都遵守能量守恒和动量守恒,都表现有反射、折射、衍射等现象;但又具有和普通光不同的特点,如方向性 Preface Laser is a new light source developed in the sixties and is a highly concentrated energy light generated by stimulated emission. Laser and ordinary light have the same place, have certain energy, observe energy conservation and conservation of momentum, all show reflection, refraction, diffraction and so on; but they also have different characteristics from ordinary light, such as directivity