We explore one of the most iconic objects in science fiction: the laser. It is a prime example of how technology can evolve from the science of the future to become part of our everyday lives in a relatively short period of time. Faith Lapidus and Steve Ember will tell us about its history and its many uses.
The word ‘laser’ is short for ‘Light Amplification by Stimulated Emission of Radiation’. The concept behind lasers is complex. Just how complex is it? It took the mind of Albert Einstein to discover the physics behind the laser.
Theodore Maiman succeeded in building the first working laser in 1960. Mr Maiman worked at the Hughes Research Laboratories in Malibu, California.
A laser fires a beam of light. Before the laser was invented, scientists developed a similar device called a maser, which stands for ‘microwave amplification by stimulated emission of radiation’. A maser is essentially a microwave version of a laser. Microwaves are a form of electromagnetic radiation that is similar to, but shorter than, radio waves. Masers are best known for their use in highly accurate clocks.
In the 1950s, 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. He and his students developed the first maser.
Meanwhile, Russians Nicolay Basov and Aleksandr Prokhorov conducted their research in Moscow. Their work led to important laser and maser technology. All three men received the Nobel Prize in Physics in 1964.
The concept of a thin beam of light with deadly power emerged much earlier. By the end of the 19th century, the Industrial Revolution had demonstrated that science could create machines with almost magical capabilities. Some writers of the time were the first to imagine something like a laser.
In 1898, H. G. Wells published the science fiction novel The War of the Worlds. In it, he described Martian creatures with technology far beyond anything found on Earth. Among their weapons was a device that Wells called a ‘heat ray’. Listen to actor Orson Welles’s description of the weapon in his famous 1938 radio broadcast of The War of the Worlds.
‘I shall refer to the mysterious weapon as a heat ray… My guess is that they are somehow able to generate intense heat in a chamber of almost absolute non-conductivity. They project this intense heat in a parallel beam against any object they choose by means of a polished parabolic mirror of unknown composition, much as a lighthouse mirror projects a beam of light. That — that is my conjecture as to 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 contain a material that supplies electrons and a power source that increases the energy level of those electrons. As Wells guessed, many lasers also have mirrors that direct light.
Laser light differs from daylight or electric lights. It has one wavelength, or colour. Laser light is also highly organised. Light behaves like a wave, and laser light is launched from its source in one orderly wave at a time.
You are listening to the VOA Special English programme EXPLORATIONS.
The physics of the laser may be complex. Nevertheless, it is simply a story of how electrons interact with light. When a photon hits an electron, the electron jumps to a higher energy state. If another photon then 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 organised, or coherent, photons are produced.
The first laser built by Theodore Maiman used a rod of man-made ruby to supply electrons. A more powerful version of the flash found in a standard camera was used to raise the electrons’ energy level. Mirrors at either end of the ruby rod reflected and amplified the light. An opening at one end of the rod allowed the laser light to shoot out, much like the flash ray of the science fiction hero Buck Rogers.
Industry put lasers to work almost immediately after their invention in 1960. However, weapons were not at the top of the list.
The first medical operation using a laser took place the year after its invention. Doctors Charles Campbell and Charles Koester used a laser to remove a tumour from a patient’s eye at Columbia-Presbyterian Hospital in New York City. Since then, doctors have used lasers to safely cut and remove tissue with little risk of infection.
Other health applications include medical imaging and vision correction surgery. LASIK operations involve eye surgeons using lasers to reshape the cornea, which covers the lens of the eye. This corrects the patient’s vision so that they do not need to wear glasses or other corrective lenses.
Lasers have made measurement an exact science. For example, astronomers have used lasers to measure the distance to the Moon with an accuracy of a few centimetres. Mappers and builders use laser technology every day. For instance, it is easy to draw a perfectly level straight line on a construction site using a laser.
Energy researchers are using lasers in an attempt to develop fusion, the same process that powers the Sun. They hope that fusion will be able to supply almost limitless amounts of clean energy in the future.
Lasers have also transformed communication. It is likely that laser light carried this EXPLORATIONS programme at least part of the way to you via a fibre optic network if you are reading or listening online. Super-fast internet connections allow people to watch films and send large amounts of data at the speed of light.
Manufacturers have been using lasers to cut and join metal parts for years. The jewellery industry also uses lasers to engrave diamonds, which are the hardest substance on Earth.
Since 1974, the public has had direct experience of lasers at the supermarket checkout.
Laser barcode scanners have transformed the way stores record information. They help businesses keep track of products. They facilitate storage and every stage of the supply process.
According to experts, no company has made better use of barcode technology than Wal-Mart, which is based in Bentonville, Arkansas. By 1988, all Walmart stores were using laser barcode scanners. The highly detailed records of its products and sales helped Wal-Mart keep costs down. Today, Walmart is the world’s biggest corporation.
Lasers are found in many products and are used almost everywhere. Laser printers can quickly and cheaply produce forms and documents. They are essential office equipment 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 reflective, coated plastic discs. These optical signals are then converted into digital information that can be used to play music, run computer software or display a full-length movie.
Over one hundred years ago, writers imagined that beams of light could be used as powerful weapons. Today, lasers guide missiles and bombs.
For instance, pilots can invisibly mark a target with a laser. Bombs or missiles can then track the target with deadly accuracy.
American defence companies are even working on giant laser guns that will be recognisable to science fiction fans everywhere. However, there are technological difficulties. According to Scientific American magazine, huge lasers convert only twenty to thirty percent of the energy they use into a laser beam. The rest is lost as heat.
This has not stopped scientists from working to perfect powerful lasers that could one day shoot missiles out of the sky.
