50 Fun Facts About Laser

The word 'laser' began as an acronym. What does the 'S' and 'E' part stand for?

The full phrase is 'light amplification by stimulated emission of radiation'; a joker once noted 'LOSER' (light oscillation) would be more accurate.

Who built the first working laser, in 1960?

He did it at Hughes Research Laboratories in Malibu, beating rival teams at Columbia, Bell Labs and TRG.

The first working laser used a synthetic crystal of which gemstone as its lasing medium?

A flashlamp pumped the crystal to produce red light at 694 nanometres, in pulses only.

The maser, the laser's predecessor, amplified what kind of radiation?

Early lasers were briefly called 'optical masers' before 'microwave' was swapped for 'light' in the acronym.

Which physicist laid the theoretical foundations for the laser in a 1917 paper on the quantum theory of radiation?

His coefficients for absorption, spontaneous emission and stimulated emission are still called Einstein coefficients.

Charles Townes shared the 1964 Nobel Prize in Physics with two scientists from which country?

Nikolay Basov and Aleksandr Prokhorov solved the problem of continuous output by using more than two energy levels.

Gordon Gould, who coined the term 'laser' in his 1957 notebook, took the notebook where to have it notarised?

That notebook launched a 28-year patent fight; he did not win a significant infringement claim until 1987.

Gould's 1959 paper intended different acronyms for different parts of the spectrum. What did he propose for X-rays?

'UVASER' was for ultraviolet and 'RASER' for radio waves; instead 'laser' swallowed everything shorter than microwaves.

How long did Gordon Gould's legal fight over laser patent rights last after the patent office turned him down in 1960?

Historians still regard the question of who invented the laser as unresolved, since so many parts were patented by different people.

Maiman's paper announcing the first laser was published in Nature in August 1960 after how many rejections from Physical Review Letters' editor?

Townes later called it 'probably more important per word than any of the papers published by Nature over the past century'.

Later in 1960, Ali Javan and colleagues built the first gas laser using which two gases, and it could run continuously?

Most HeNe lasers are engineered to lase at 633 nm, the familiar red beam of school physics labs.

The first semiconductor laser, demonstrated by Robert N. Hall in 1962, was made of which material?

It emitted near-infrared light at 850 nm and only worked in pulses while cooled with liquid nitrogen.

The carbon-dioxide laser, invented by C. Kumar N. Patel in 1964, emits in which part of the spectrum?

Its 10.6 μm beam and unusually high efficiency of over 30% made it a workhorse for industrial cutting and welding.

The active ingredient in a ruby laser's crystal is ions of which element suspended in synthetic sapphire?

Those chromium ions are also what make natural ruby red.

When it was first invented, the laser was famously described as what?

Gould's notebook had already listed telecommunications, radar, spectrometry and nuclear fusion as possible uses.

What was the first widely noticeable everyday use of lasers, introduced in 1974?

The first item scanned was a pack of Wrigley's chewing gum at a Marsh supermarket in Troy, Ohio.

The first product ever scanned with a UPC barcode, in June 1974, was a pack of what?

It happened at a Marsh supermarket in Troy, Ohio, using a scanner made by Photographic Sciences Corporation.

Which product, introduced in 1978, was the first successful consumer device to include a laser?

The CD player, commercialised in 1982, was the first laser-equipped device to become truly common.

A compact disc is read by a semiconductor laser of what wavelength, in the near infrared?

Early players used a helium-neon laser instead; Blu-ray players use a 405 nm violet laser.

The laser printer was invented in 1969 by Gary Starkweather at which company?

His idea was to use a laser beam to 'draw' the image directly onto a copier drum.

Which type of beam is used in LASIK surgery to reshape the cornea?

These ultraviolet lasers are also used to print microchips by photolithography.

Which type is by far the most commonly manufactured, found in barcode readers, pointers and disc drives?

They also carry the world's fibre-optic internet traffic.

The word 'lidar', first recorded as a stand-alone word in 1963, is thought to have begun as a portmanteau of which two words?

It measures range by timing how long laser light takes to bounce back, and now guides self-driving cars.

Lunar laser ranging bounces beams off a retroreflector array left on the Moon by which mission on 21 July 1969?

Those measurements show the Moon is spiralling away from Earth at 3.8 centimetres a year.

Laser ranging to the Moon shows it is drifting away from Earth at roughly what rate?

The retroreflectors placed by Apollo astronauts and Soviet Lunokhod rovers still return photons today.

The National Ignition Facility at Lawrence Livermore focuses how many laser beamlines onto its fuel target?

They are flashlamp-pumped, neodymium-doped phosphate glass lasers, and the whole system is the most energetic laser in the world.

On 5 December 2022 the National Ignition Facility achieved what long-sought milestone?

The shot yielded 154% of the laser energy that went in, though far less than the electricity used to power the lasers.

LIGO, which uses laser interferometers to detect gravitational waves, has L-shaped vacuum arms of what length?

Its two observatories are in Hanford, Washington, and Livingston, Louisiana; Europe's Virgo detector has 3 km arms.

LIGO's first detection, on 14 September 2015, came from the merger of two of what?

Each was about 30 solar masses; the discovery was announced in February 2016 and won the 2017 Nobel Prize in Physics.

The 1997 Nobel Prize in Physics went to Steven Chu, Claude Cohen-Tannoudji and William Phillips for using lasers to do what?

Laser cooling slows atoms to a crawl by hitting them with photons tuned just below their absorption frequency.

In the James Bond film Goldfinger, the villain menaces Bond with an industrial laser. What weapon did he use in Ian Fleming's novel?

Lasers did not exist in 1959 when the book was written; the filmmakers swapped it in to feel fresher.

The first laser-tag style toy, sold in 1979, was a set of electronic phaser guns tied to which film franchise?

They used infrared light and a sensor, and accompanied the release of Star Trek: The Motion Picture.

Green laser pointers usually get their colour by frequency-doubling a diode-pumped solid-state laser to which wavelength?

Cheap pointers can leak the invisible infrared they start from, which is a hidden eye hazard.

Laser pointers are banned in many places from being aimed at what, because they can dazzle pilots?

Even a few milliwatts becomes dangerous when a cockpit is dark and the beam is spread by a windscreen.

Lasers in which safety category, 500 milliwatts and up, can burn skin and cause eye damage even from scattered light?

Class 1 devices are safe under all normal use, and CD players are Class 1 because the beam is enclosed.

The first chemical laser, demonstrated at Berkeley in 1965, used which gas?

Chemical lasers release huge energy from a reaction and have long interested the military.

Charles Townes built the first maser in 1953 at Columbia University using which gas?

Several eminent physicists, including Niels Bohr and John von Neumann, told him the device would violate the uncertainty principle.

Townes recalled that several eminent physicists insisted the maser could not work because it violated what?

Isidor Rabi and Polykarp Kusch merely thought it impractical and not worth the effort.

The property that lets a laser beam stay narrow over great distances is called what?

It comes from spatial coherence, and it is why a pointer's dot barely grows across a lecture hall.

For a laser to work, its medium must be kept in a state where more atoms are excited than not. What is this called?

Materials with metastable states, which stay excited unusually long, are chosen so the chain reaction of stimulated emission can build.

The builder of the first laser received which prestigious 1987 award for 'realization of the world's first laser', though never a Nobel?

The Nobel committee honoured Townes, Basov and Prokhorov for the theory, but the man who built the thing was passed over.

A device that produces light by itself, as a laser does, is technically what rather than the amplifier its acronym suggests?

Hence the joke that LOSER, for light oscillation by stimulated emission of radiation, would be the correct name.

By the 2020s, the shortest laser pulses were measured in what unit of time?

An attosecond is a billionth of a billionth of a second, short enough to catch electrons moving inside atoms; the 2023 Nobel honoured the field.

Devices working at frequencies above roughly 300 GHz are called lasers; what are the equivalent devices at microwave or radio frequencies called?

Nature makes them too: astrophysical masers occur in interstellar gas clouds.

At which company's research laboratories in Malibu was the first working laser operated in 1960?

Theodore Maiman beat rival teams at Columbia, Bell Labs and the TRG company to the milestone.

What wavelength of red light did Maiman's flashlamp-pumped ruby laser produce?

The device could only run in pulses because of its three-level pumping scheme.

Which Japanese engineer proposed a 'semiconductor optical maser' in an April 1957 patent application?

That same year Townes and Schawlow at Bell Labs began their serious study of infrared 'optical masers'.

Neodymium-doped crystals such as Nd:YAG produce high infrared power at which wavelength?

Frequency-doubling that output gives the familiar 532 nm green of many laser pointers.

Which highly tunable class of laser uses an organic gain medium dissolved in liquid?

The broad gain spectrum also lets them produce pulses only a few femtoseconds long.

Hobbyists salvage violet laser diodes from which kind of broken player?

DVD players yield red diodes, while CD and DVD burners give higher-power ones.