1960年,人类首次在实验室发出激光。它的相干性、方向性和亮度皆远优于普通的光,其中相干性是主要的,故激光又称相干光。和无线电波对比,普通的光(即非相干光)相当于电波的无规则噪声,激光则相当于规则的、能用各种调制方法传送声音、图像等信号的无线电波。激光的出现在光学中是划时代的。 In 1960, the first human being in the laboratory laser. Its coherence, directionality and brightness are far superior to ordinary light, of which the coherence is the main, so the laser is also called coherent light. Compared with radio waves, normal light (ie, incoherent light) is equivalent to random noises of electric waves. The laser is equivalent to a regular one, and can use various modulation methods to transmit radio waves of signals such as sound and images. The emergence of lasers in epochs is epoch-making.