They find things in the dark. They check groceries, play concertos and perform eye surgery. They are faster than a speeding bullet and could do serious damage to a locomotive.

Lasers have been the Superman of the electromagnetic spectrum ever since 1960, when 33-year-old Theodore H. Maiman of Hughes Aircraft Co. built the first one from a pink ruby.As they near their 30th anniversary, though, lasers have switched from comic-book novelties to necessities that preoccupy the technology giants of the United States, Europe and Japan.

Lasers are not only in compact disc players and bar-code scanners at checkout counters; they are in the phone system, carrying long-distance calls over hair-thin glass fibers.

Now, lasers are poised to take a quantum leap. Tiny devices called quantum lasers herald an era in which lasers will be more central to the technology underlying daily life.

Experts say quantum lasers and their cousins, quantum transistors, could make possible supercomputers the size of baseballs, and television screens of unparalleled clarity that hang on the wall like a painting.

"Quantum devices are the wave of the future. Almost all of the research that goes on involves quantum effects in some way or another," said David V. Lang, director of the solid state electronics research lab at AT&T Bell Labs.

Lasers are what some scientists call a "killer" technology: Compact discs are killing vinyl records, for example, and nobody uses copper anymore for long-distance phone lines.

To repeat a familiar story, the Japanese are putting the American-invented killer to use more effectively than Americans themselves are.

Japan's dominance of mass-market electronics gives its companies unmatched expertise in making things small, cheap and reliable. For example, Japanese companies dominate the market for CD players, which use more lasers than any other product.

"It's a byproduct of the Japanese decision to invest in consumer electronics. They'll find an application and find the technology to solve it. I wish we did it here," said Henry Kressel, a venture capitalist at E.M. Warburg Pincus & Co. Inc. in New York.

Japan's twin towers of strength in lasers and semiconductors could allow it to build the first computers in which chips are connected by quantum laser beams instead of electricity. That worries companies like International Business Machines Corp., which is intensively studying quantum well lasers and quantum well transistors.

At AT&T Bell Laboratories, one of America's foremost laser research centers, Alan Huang is hoping to leapfrog the Japanese. But he admits the competition is tough: For an early model of his "optical computer" he had to use a diode laser he took from a Japanese-made CD player.

A laser is a directed needle of light purified to one particular color, or wavelength. In contrast, ordinary light is a jumble of many wavelengths flying in all directions.

"Laser" stands for light amplification by stimulated emission of radiation. In a cascading effect, photons of light strike an energized material and stimulate the release of more photons in a synchronized pattern.

The most powerful lasers, big enough for someone to walk inside, are being used to attempt to fuse the nuclei of atoms in flashes of energy a million times more intense than a nuclear blast. Sustained nuclear fusion could be a source of clean, plentiful and cheap electricity.

At the other end of the scale are semiconductor diode lasers, no bigger than a grain of salt - the kind used in compact disc players and the phone system. One exotic subspecies is the quantum laser.

Scientists build quantum lasers by "spray-painting" atoms in a layer cake of incredibly thin layers, some of which have impurities added.

The impure layers act like walls to trap electrons. Confining so many electrons and their receptors ("holes") to a tiny space makes it easier to get a cascade of photons going, creating laser light.

If a laser the size of a salt crystal were blown up to the size of the World Trade Center in New York, a quantum well would be about the thickness of a rug in an office, said Michael Ettenberg, director of the optoelectronics research lab at the David Sarnoff Research Center in Princeton, N.J.

Quantum lasers are more precise and require less current, and their efficiency in converting electricity to light is unmatched.

Spectra Diode Physics of San Jose, Calif., recently produced 76 watts of continuous wave power from a quantum laser, a record in power conversion efficiency, president and chief executive Donald Scifres told The Associated Press this past week.

Optical surgeons have used lasers since 1970 to weld detached retinas. Later came other medical uses like excising tumors and eliminating cataracts. Today, lasers snaked into the body on optical fibers clean arteries and destroy urinary-tract stones.

Lasers are used to make pinholes in the nipples of baby bottles, study components of car exhaust and form the three-dimensional holograms used on credit cards - and maybe someday dollar bills.

The military has "Star Wars" designs for free-electron lasers and powerful X-ray lasers, which physicist Edward Teller has suggested could be triggered by a nuclear blast.

Laser weapons would most likely be mounted in space: "People tried to shoot laser beams through the sky and what they discovered was fog and rain," said William Bridges of California Institute of Technology.

Quantum well lasers fill only one niche, but an important one. Their speed and efficiency makes them ideal for rapid-fire communication, initially for long-distance calls, later for links between neighboring computers and eventually for the links between chips in computers, said Robert Melcher, a laser expert for IBM in Zurich, Switzerland.

"I've been in the laser game for 25 years now," said one researcher, Ross A. McFarlane, of Hughes Research Laboratories in Malibu, Calif. "That (quantum lasers) is where the future lies."