VOA慢速英语2013 EXPLORATIONS - The History of the Laser

 

EXPLORATIONS - The History of the Laser

Welcome to EXPLORATIONS in VOA Special English. I’m Mario Ritter. This week, we tell about one of the most recognizable objects in science fiction — the laser. It is one of the best examples of how technology can go from the science of the future to everyday use in a short period of time. Faith Lapidus and Steve Ember tell us about the history and many uses for the laser.

Laser is short for Light Amplification¹ by Stimulated² Emission³ of Radiation. The idea behind lasers is complex. Just how complex? Consider that it took the mind of Albert Einstein to discover the physics behind the laser. 

Theodore Maiman succeed in building the first working laser in nineteen sixty. Mr. Maiman worked at Hughes Research Laboratories in Malibu, California.

A laser fires a light beam. Before the laser, scientists developed a similar device: a maser which stands for Microwave Amplification by Stimulated Emission of Radiation. A maser is basically a microwave version of the laser. Microwaves are a form of electromagnetic radiation similar to, but shorter than, radio waves. The best-known use of masers is in highly accurate clocks. 

In the nineteen fifties, researchers in the United States and Russia independently developed the technology that made both masers and lasers possible. Charles Townes was a professor at the Massachusetts Institute of Technology in Cambridge, Massachusetts. He and his students developed the first maser. 

Russians Nicolay Basov and Aleksandr Prokhorov did their research in Moscow. Their work led to technology important to lasers and masers. The three men received the Nobel Prize in Physics in nineteen sixty-four. 

The idea of a thin beam of light with deadly power came much earlier. By the end of the eighteen hundreds, the industrial revolution had shown that science could invent machines with almost magical powers. And some writers of the time were the first to imagine something like a laser.

In eighteen ninety-eighty, H.G. Wells published a science fiction novel called “The War of the Worlds.” In it, he described creatures from the planet Mars that had technology far beyond anything on Earth. Among their weapons was what Wells called a “heat ray.” Listen to actor Orson Welles describe the weapon in a famous radio broadcast of “The War of the Worlds” from nineteen thirty-eight. 

“I shall refer to the mysterious weapon as a heat ray… It's my guess that in some way they are able to generate an intense heat in a chamber⁴ of practically absolute non-conductivity. This intense heat they project in a parallel beam against any object they choose, by means of a polished parabolic mirror of unknown composition, much as the mirror of a lighthouse projects a beam of light. That -- That is my conjecture⁵ of the origin of the heat ray.” 

H.G. Wells’ description is not too far from the truth. All lasers have several things in common. They have a material that supplies electrons and a power source that lifts the energy level of those electrons. And, as Wells guessed, many lasers have mirrors that direct light.

Laser light is different from daylight or electric lights. It has one wavelength⁶ or color. Laser light is also highly organized. Light behaves like a wave and laser light launches in one orderly wave at a time from its source. 

You are listening to the VOA Special English program EXPLORATIONS.

The physics of the laser may be complex. Still, it is just a story of how electrons interact with light. When a light particle, or photon, hits an electron, the electron jumps to a higher energy state. If another photon strikes one of these high-energy electrons, the electron releases two photons that travel together at the same wavelength. When this process is repeated enough, lots of organized, or coherent, photons are produced.

In Theodore Maiman’s first laser, a rod of man-made ruby⁷ supplied the electrons. A more powerful version of the flash on a common camera was used to lift the energy state of the electrons. Mirrors on either end of the ruby rod reflected and increased the light. And an opening at one end of the rod let the laser light shoot out — just like the flash ray of science fiction hero Buck⁸ Rogers.

Industry put lasers to work almost immediately after they were invented in nineteen sixty. But weapons were not first on the list. 

The first medical operation using a laser took place the year following its invention. Doctors Charles Campbell and Charles Koester used a laser to remove a tumor⁹ from a patient’s eye at Columbia-Presbyterian Hospital in New York City. Since then, doctors have used lasers to cut and remove tissue safely with little risk of infections.

Other health uses include medical imaging and vision correction surgery. Eye surgeons use lasers in LASIK operations to reshape the cornea, which covers the lens of the eye. The reshaped cornea corrects the patient’s bad eyesight so he or she does not have to wear glasses or other corrective lenses.

Lasers have made measurement an exact science. Astronomers¹⁰ have used lasers to measure the moon’s distance from Earth to within a few centimeters. Mappers and builders use laser technology every day. For example, drawing a perfectly¹¹ level straight line on a construction site is easy using a laser. 

Energy researchers are using lasers in an attempt to develop fusion¹², the same energy process that powers the sun. Scientists hope fusion can supply almost limitless amounts of clean energy in the future.

Lasers have also changed the way we communicate. It is likely that laser light on a fiber¹³ optic network carried this EXPLORATIONS program at least part of the way to you if you are reading or listening online. Super-fast Internet connections let people watch movies and send huge amounts of information at the speed of light. 

Manufacturers have used lasers for years to cut and join metal parts. And the jewelry¹⁴ industry uses lasers to write on the surface of the world’s hardest substance, diamonds.

Since nineteen seventy-four, the public has had direct experience with lasers — at the grocery store checkout¹⁵ line. 

Laser barcode scanners have changed how stores record almost everything. They help businesses keep track of products. They help in storage and every detail of the supply process. 

Experts say no company has put barcode technology to better use than Wal-Mart, based in Bentonville, Arkansas. By nineteen eighty-eight, all Wal-Mart stores used laser bar code scanners. Highly detailed¹⁶ records on its products, and how they were selling, helped Wal-Mart keep costs down. Today, Wal-Mart is the world’s biggest corporation.

Lasers are found in many products used almost everywhere. Laser printers can print out forms and documents quickly and are relatively¹⁷ 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 accurately¹⁸ 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 defense¹⁹ companies are working on giant laser guns recognizable to science fiction fans everywhere. But there are technological²⁰ 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.

1 amplification   

n.扩大，发挥

参考例句：

• The voice of despair may be weak and need amplification.绝望的呼声可能很微弱，需要扩大。
• Some of them require further amplification.其中有些内容需进一步详细阐明。

2 stimulated   

a.刺激的

参考例句：

• The exhibition has stimulated interest in her work. 展览增进了人们对她作品的兴趣。
• The award has stimulated her into working still harder. 奖金促使她更加努力地工作。

3 emission   

n.发出物，散发物；发出，散发

参考例句：

• Rigorous measures will be taken to reduce the total pollutant emission.采取严格有力措施，降低污染物排放总量。
• Finally,the way to effectively control particulate emission is pointed out.最后，指出有效降低颗粒排放的方向。

4 chamber   

n.房间，寝室；会议厅；议院；会所

参考例句：

• For many,the dentist's surgery remains a torture chamber.对许多人来说，牙医的治疗室一直是间受刑室。
• The chamber was ablaze with light.会议厅里灯火辉煌。

5 conjecture   

n./v.推测，猜测

参考例句：

• She felt it no use to conjecture his motives.她觉得猜想他的动机是没有用的。
• This conjecture is not supported by any real evidence.这种推测未被任何确切的证据所证实。

6 wavelength   

n.波长

参考例句：

• The authorities were unable to jam this wavelength.当局无法干扰这一波长。
• Radio One has broadcast on this wavelength for years.广播1台已经用这个波长广播多年了。

7 ruby   

n.红宝石，红宝石色

参考例句：

• She is wearing a small ruby earring.她戴着一枚红宝石小耳环。
• On the handle of his sword sat the biggest ruby in the world.他的剑柄上镶有一颗世上最大的红宝石。

8 buck   

n.雄鹿，雄兔；v.马离地跳跃

参考例句：

• The boy bent curiously to the skeleton of the buck.这个男孩好奇地弯下身去看鹿的骸骨。
• The female deer attracts the buck with high-pitched sounds.雌鹿以尖声吸引雄鹿。

9 tumor   

n.（肿）瘤，肿块(英)tumour

参考例句：

• He was died of a malignant tumor.他死于恶性肿瘤。
• The surgeons irradiated the tumor.外科医生用X射线照射那个肿瘤。

10 astronomers   

n.天文学者，天文学家( astronomer的名词复数 )

参考例句：

• Astronomers can accurately foretell the date,time,and length of future eclipses. 天文学家能精确地预告未来日食月食的日期、时刻和时长。 来自《简明英汉词典》
• Astronomers used to ask why only Saturn has rings. 天文学家们过去一直感到奇怪，为什么只有土星有光环。 来自《简明英汉词典》

11 perfectly   

adv.完美地，无可非议地，彻底地

参考例句：

• The witnesses were each perfectly certain of what they said.证人们个个对自己所说的话十分肯定。
• Everything that we're doing is all perfectly above board.我们做的每件事情都是光明正大的。

12 fusion   

n.溶化；熔解；熔化状态，熔和；熔接

参考例句：

• Brass is formed by the fusion of copper and zinc. 黄铜是通过铜和锌的熔合而成的。
• This alloy is formed by the fusion of two types of metal.这种合金是用两种金属熔合而成的。

13 fiber   

n.纤维，纤维质

参考例句：

• The basic structural unit of yarn is the fiber.纤维是纱的基本结构单元。
• The material must be free of fiber clumps.这种材料必须无纤维块。

14 jewelry   

n.（jewllery）（总称）珠宝

参考例句：

• The burglars walked off with all my jewelry.夜盗偷走了我的全部珠宝。
• Jewelry and lace are mostly feminine belongings.珠宝和花边多数是女性用品。

15 checkout   

n.（超市等）收银台，付款处

参考例句：

• Could you pay at the checkout.你能在结帐处付款吗。
• A man was wheeling his shopping trolley to the checkout.一个男人正推着购物车向付款台走去。

16 detailed   

adj.详细的，详尽的，极注意细节的，完全的

参考例句：

• He had made a detailed study of the terrain.他对地形作了缜密的研究。
• A detailed list of our publications is available on request.我们的出版物有一份详细的目录备索。

17 relatively   

adv.比较...地，相对地

参考例句：

• The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
• The operation was relatively painless.手术相对来说不痛。

18 accurately   

adv.准确地，精确地

参考例句：

• It is hard to hit the ball accurately.准确地击中球很难。
• Now scientists can forecast the weather accurately.现在科学家们能准确地预报天气。

19 defense   

n.防御，保卫；[pl.]防务工事；辩护，答辩

参考例句：

• The accused has the right to defense.被告人有权获得辩护。
• The war has impacted the area with military and defense workers.战争使那个地区挤满了军队和防御工程人员。

20 technological   

adj.技术的；工艺的

参考例句：

• A successful company must keep up with the pace of technological change.一家成功的公司必须得跟上技术变革的步伐。
• Today,the pace of life is increasing with technological advancements.当今， 随着科技进步，生活节奏不断增快。