英语_电子信息工程10.pptVIP

Unit 10 Lasers Unit 10 Lasers Passage A What is a Laser? Passage B Introduction: Super-tool Passage C Lasers Passage A What is a Laser? 　　In H. G. Wells’s The War of the Worlds, published in 1898, extraterrestrial aliens wreak destruction on our planet with their “heat ray”, a beam of energy so hot, so powerful, that it destroys anything it touches. “Suddenly there was a flash of light,” wrote Wells. “It was sweeping round swiftly and steadily, this flaming death, this invisible, inevitable sword of heat.” Wells’s heat ray, which inspired generations of science-fiction writers to imagine ray guns and death rays, was a chillingly accurate premonition of plans to use the high-energy infrared laser as a weapon. 　　When real lasers finally arrived—in 1960—writers and moviemakers immediately leaped upon their destructive power and substituted the word “laser” for ray gun. A laser was one of the leading pieces of machinery in the James Bond techno-spy thriller Goldfinger in the early 1960s. As you may recall, Bond (Sean Connery played the role at the time) was tied down to a metal table by the villain Goldfinger, his legs spread apart, while a laser made its way directly toward his genitals. The laser’s bright, red, thick beam easily cut a swath through the table. It obviously had the power to tear him asunder, lengthwise. 　　This is, alas, the most popular image of the laser. A ray gun. A death ray. And indeed, some lasers do cut through metal and some can be used as weapons. But this image of the laser is a reflection more of the need for drama in works of fiction than of the laser’s potential usefulness in our society. Most laser beams can’t cut or burn and are at best faint pencil lines in the air, light scattered by dust. The nice sharp pictures of laser beams in this book are taken by projecting the beams through clouds of smoke, which scatter their light enough to allow them to be seen and photographed. 　　So how should you think of the laser? Think of it