Holograms - ghostlike, three-dimensional images created with the use of lasers - have been more of a curiosity than a commercial success since their advent more over two decades ago.
Other than their use in some scientific tools, art displays, and gimmicks - you can still buy glasses with open eyes hologrammed on the lenses (considered handy for napping at technical meetings) - holography has been defined more by its limits than its potential.
Now, however, new tricks and cheaper production are putting more of these light-created pictures to work in science, industry, and even people's billfolds.
''What's significant is not that the applications are new, but that they have become established as something more than just a novelty,'' says Emmett Leith, a University of Michigan electrical engineering professor and holography expert.
Holography will not have the sweeping impact of some other laser-related technologies, such as fiber-optic communications systems. But the ability to emboss 3-D pictures on wafers of plastic or project them into air is leaving an imprint in several areas. Among them:
* Security. MasterCard International Inc. will embed tiny holograms on all 80 million of its cards over the next three years to prevent counterfeiting. By themselves credit cards are easy to reproduce. But putting holograms on cards could in theory thwart forgers. Last year counterfeiting cost the credit-card industry an estimated $40 million. But some see the idea more as a marketing gimmick than an effective security device.
* Industrial inspection tools. Because they provide detailed images of an object, holograms have proved useful in gauging responses to stress and vibrations in industry. Manufacturers have put them to work detecting flaws in aircraft wings, turbine blades, tires, satellite components, and other precision parts.
The testers have been around since the 1960s. But a generation of easier-to-use (if expensive) holographic tools is being developed that may find wider use. Two of the many possible uses: examining circuit boards and detecting microscopic flaws in computer chips.
The big plus of the instruments: their sensitivity. By superimposing one hologram of an object over another taken after stress was applied, surface irregularities have been detected down to a billionth of an inch, says Fredric Unterseuer, educational director of the New York Museum of Holography.
* Aircraft instrument aids. Called ''head-up displays,'' these let pilots read information such as airspeed and altitude, and gaze at an image of the runway without looking down at their instrument panels. The displays are useful for foul-weather flying. They also give military pilots more time to spot enemy fighters.
Conventional head-up displays flash data on aircraft windows, but can partly block a pilot's view. With holographic devices, pilots peer through the data projected in front of them. ''The beauty of the hologram is that it looks like a clear piece of glass,'' says Gaylord Moss, a scientist at Hughes Aircraft, a maker of the displays.
The tailor-made systems are being tested on a number of fighter aircraft. Some commercial airlines are looking at them, too, but growth will likely be slow. ''At this point it's like speed control on a car,'' says a Boeing Company official. ''It makes driving easier, but you don't necessarily need it.''
The head-up displays are part of an emerging family of versatile holograms known as holographic optical elements. The forte of HOEs isn't in capturing images in three dimensions but in focusing or reflecting light similar to mirrors and lenses, which they are slowly replacing. HOEs are popping up in more advanced supermarket checkout scanners, high-speed laser printers, and new chemical analysis measuring tools.
Then, too, advertisers and artists continue to be tantalized by the potential of putting holographic ''light sculptures'' to work. At least two recent books have come out containing 3-D illustrations. Holograms are being experimented with to enhance computer graphics. Some architects use 3-D ''light'' models of buildings.
The past two decades were teething time for the technology. The '80s may be a commercial testing time.