Lasers are found in many products used almost everywhere. Laser printers can print out forms and documents quickly and are relatively low in cost. They are required equipment for offices around the world.
If you have a CD or DVD player, you own a laser. Laser disc players use lasers to accurately read or write marks on a reflective, coated plastic disc. A device turns these optical signals into digital information that becomes music, computer software or a full-length movie.
Over one hundred years ago, writers imagined that beams of light could be powerful weapons. Today, lasers guide missiles and bombs.
For example, pilots can mark a target invisibly with a laser. Bombs or missiles then track the target with deadly results.
And, yes, American defense companies are working on giant laser guns recognizable to science fiction fans everywhere. But there are technological difficulties. Scientific American magazine says huge lasers turn only about twenty to thirty percent of the energy they use into a laser beam. The rest is lost as heat.
That has not stopped scientists from working to perfect powerful lasers that, one day, may be able to shoot missiles out of the sky.
【The history of the laser】相关文章:
★ More than one way to the square
★ Messages of hope for working class
★ The Cobbler and the banker皮匠和银行家
最新
2020-12-21
2020-08-06
2020-07-31
2020-07-30
2020-07-30
2020-07-30