填空题

The word laser stands for "light amplification by stimulated emission of radiation". To many people lasers are very (36) , but a laser is simply a (37) that produces a very strong light. The light from a laser is called (38) light because it is light that moves in only one direction. In contrast, incoherent light, like the light form the sun or a light (39) , moves away from its (40) in all directions and (41) in a narrow beam. As soon as the laser was developed, scientists began thinking of practical (42) for it. One of the earliest uses was to make extremely (43) measurements of distance and speed. As time passed, many more applications for the laser were developed. (44) .From laser printers to technology by which whole encyclopedias of information can be stored on a laser disk (called a CD-ROM) and read by a computer, lasers are revolutionizing computers. Lasers have also made a big difference in the way telephones work. Instead of changing sound waves to electricity that travels through copper wire, (45) One such fiber can carry more than a million conversations at the same time! (46) .