ON Oct. 18, 1975, a United States reconnaissance satellite orbiting 22,300 miles above the Indian Ocean detected a sudden flash of energy 1,000 times brighter than that of the launch of a Soviet long-range nuclear-armed missile.
Then, just as suddenly, the satellite's delicate infrared sensors blacked out. The satellite was designed to give the US an early warning of a Soviet nuclear attack.
Some US intelligence and technical experts thought at the time that the satellite might have been deliberately blinded by a beam fired from a Soviet ground-based laser system. There was speculation at the Pentagon that perhaps the Soviets had developed a working laser weapon, not unlike the heat ray of the turn-of-the-century science-fiction writer H.G. Wells.
But the incident, as pieced together from trade journal reports and official sources, is now widely believed to have been caused by an unusually large gas pipeline fire in the Soviet Union.
Similar satellite blindings have occurred since, including one reported in late 1982, but none are officially suspected to have been caused by Soviet laser weapons, officials say. They are thought to have been caused by the sun's reflection.
Nonetheless, the incidents have heightened the American defense community's concern about a potential Soviet laser weapon - a weapon that might be capable of zapping US satellites or other targets with a destructive flash traveling at the speed of light - 186,000 miles per second.
In its 1984 report entitled ''Soviet Military Power,'' the US Defense Department says, ''The Soviets could deploy antisatellite lasers to several ground sites in the next 10 years and they could deploy laser-equipped satellites either available for launch on command or maintained in orbit.'' The 1983 Pentagon assessment was more explicit: ''An operational system capable of attacking other satellites within a few kilometers range could be established in the early 1990s.''
Since the early 1960s, the US has invested close to $2 billion in research aimed at developing a laser weapon before the Soviets do. The Soviet effort has been estimated to be three to five times larger than that of the US.
It is no wonder then that the Pentagon and the Commerce Department place such a high priority on restricting shipments of all but the most basic laser systems from the US. But that has not prevented American laser equipment from finding its way to the Soviet Union, both legally and illegally.
The most widely publicized example of US laser equipment going to the Soviets was the transshipment in 1976 and '77 of laser mirrors built by Spawr Optical Research Inc. of Corona, Calif., to a university in Moscow.
In 1980, the president of Spawr Optical, Walter Spawr, and his wife, Frances, were convicted of conspiring to circumvent US export laws in transshipping 19 water-cooled, pure copper laser mirrors to the Soviet Union via Switzerland. They had been charged with transshipping some 40 laser mirrors ranging in diameter from 1.25 inches to 12 inches.
The Spawrs say they are innocent.
Though the mirrors were said to have been designed for use in laboratory research and laser welding applications, the case attracted international attention because of the potential national-security implications of lasers.
To an uninformed public the words ''laser mirrors'' conjure images of death rays. To the press it was a spicy story.
In March 1980, the trade journal Industrial Research and Development featured a report on the loss of strategic high technology to the Soviets. In it the writer mentioned Walter Spawr, saying, ''Commerce Department officials told him his precision laser mirrors might have application in Soviet 'killer-satellites, ' and therefore couldn't be exported.'' The story also said, ''laser technology exported for manufacturing purposes can be modified for exotic satellite-killing weapons.'' This last statement was not attributed.
ACCORDING to Mr. Spawr, the ''killer-satellite'' statement was made to him by Commerce investigator Robert Rice, who had no technical background in laser optics. Spawr said he laughed when he first heard the statement. He said he told the investigator as well as the Industrial Research and Development writer that such a statement was ridiculous. Nonetheless, ''killer-satellite'' was included in the story. After that, no one in the press checked it out. It was simply repeated.
Spawr says that the prosecuting attorney in his case, Theodore W. Wu, mentioned the ''killer-satellite'' article to the grand jury that eventually indicted him and his wife. But ''killer-satellites'' was not an issue in the subsequent courtroom trial of the Spawrs, according to Spawr and the trial transcript.
Nonetheless, the Washington Post and the Wall Street Journal both printed stories in 1981 suggesting that Spawr's laser mirrors might have already been used in tests of Soviet ''killer-satellites.''
In July 1981, a then-assistant secretary at the Commerce Department, Lawrence Brady, was quoted on the British Broadcasting Corporation as saying: ''I would refer to the public record in the case. . . . I believe there is a Department of Defense film, or a US government film which indicates - and classified film - which shows how these very mirrors are used in a device to blow up aircraft in space. . . .''
But according to the major participants in the 1980 Spawr trial and a review of court records, national security was not an issue debated in the case.
According to Spawr's attorneys, Spawr was convicted in a broad interpretation of national security as it applies to the Export Administration Act. He was found guilty of selling laser mirrors that ''would be used for the benefit of a communist-dominated country.''
According to the Export Adminstration Act, the intent of Congress in passing the law was ''to restrict the export of goods and technology which would make a significant contribution to the military potential of any other nation or nations which would prove detrimental to the national security of the United States.''
But all that was shown to send Spawr to prison was that he knew that his mirrors would offer a ''benefit'' to the Soviets. The jury that convicted Spawr was told nothing about ''national security,'' ''significant contribution to military potential,'' or even ''technological benefit.''
The government's position was that the Soviets could gain a ''benefit'' from the laser mirrors by disassembling them and copying the technology in order to design and build their own laser mirrors.
According to the trial transcript, the court never determined - indeed no one ever asked - if the shipment of the mirrors to the Soviets could constitute a threat to US national security.
''The chances of a Spawr mirror being incorporated in a satellite weapon are to my way of thinking zero. I'm not even going to say there's a small chance. It's zero,'' says Dr. Peter Franken, a former acting director of the Defense Advanced Projects Agency (DARPA), which oversees US laser-weapons development. He has also served as a director of the Optical Sciences Center at the University of Arizona, as a member of the Defense Science Board's task force on particle-beam technology, as a consultant to Los Alamos Scientific Laboratory, and as a consultant to the Defense Department. Dr. Franken, who testified at the Spawr trial, says the case has resulted in ''an obfuscation of basic national-security concerns.''
''I have been in many of the laboratories in the Soviet Union where much of the Soviet high-energy laser research is being conducted. I have seen it and talked to the Soviets about it. I have seen the (Spawr) mirrors - or if not those then some like them - at Moscow State University, where I lectured several years ago. They were in a laboratory of the physics department,'' he says.
''In no way, shape, or form has this compromised the security of the United States - in no way, shape, or form,'' he adds.
Kosta Tsipis, a Massachusetts Institute of Technology physics professor and co-director of the program in Science and Technology for International Security at MIT, says it would be ''absurd'' to suggest that the export of water-cooled, pure copper laser mirrors to the Soviet Union would comprise a strategic loss to the US.
''These are research tools, they are not military weapons'' he says. ''They help with their research, but you cannot apply that as a weapon - it is out of the question.''
Franken adds, ''There was no transshipment of technology at all - mirrors were shipped, but technology was not.''
''I told this to (then prosecuting attorney Theodore W.) Wu before the trial, but Wu didn't like the news he was getting from Franken. He had a real motivation, he wanted to win the case,'' Franken says today.
Mr. Wu declines to answer questions about his possible pretrial discussions with Franken.
The Spawr case was prosecuted at a time after the Soviet invasion of Afghanistan when American trade policy was beginning a dramatic shift away from detente and toward tighter controls on trade with the Soviets.
''The pressure was to nail somebody,'' says Jerry Trippe, a former acting director of the State Department's Office of Atomic Energy and Aerospace. Mr. Trippe, who has studied the Spawr case, is currently a Washington lawyer specializing in export regulations.
''They (Commerce Department officials) had pressure on them to perform - to show that the government was not going to let technology diversion go on,'' he says. ''They went into (the Spawr case) as something politics demanded that they do.''
Mr. Wu became nationally known in the early 1980s as a specialist in high-technology export cases, not only for his work on the Spawr case, but also for the successful prosecutions of Edler Industries in 1979 and the 1981 CTC-Maluta case, which has been called the largest, most complex high-technology export case yet uncovered. A 1981 Fortune magazine profile of Wu said he had more experience in export control cases ''than any other US prosecutor.''
Since June 1982, Wu has been deputy assistant secretary for export enforcement at the Commerce Department. In a telephone interview he said of the Spawr case: ''During trial there was substantial testimony by the government that these mirrors had military applications and that they were built the same or were similar to those used at (the Air Force Weapons Laboratory,) Kirtland Air Force Base.''
According to the trial transcript, an Air Force laser expert testified in 1980 that Spawr's pure copper mirrors were specially designed for ''high-power laser weapons demonstrations.'' Today, that witness, Dr. Rayond Wick of the Air Force Weapons Laboratory, declines to specify exactly how Spawr mirrors similar to those that were exported were used at the weapons laboratory. He says such information is classified.
The focal point of the laser research at the weapons laboratory in the mid- 1970s was the Airborne Laser Laboratory (ALL). It was a modified Boeing 707 carrying a 400-kilowatt laser that in June 1983 shot down five Sidewinder air-to-air missiles in test flights. The ALL was phased out as an active research project last September.
According to Wu: ''The Airborne Laser Laboratory used similar mirrors as those exported (by Spawr).''
An Air Force spokesman in Washington says that none of the mirrors in the ALL were made of copper. Dr. Wick confirmed this. All of Spawr's mirrors were copper.
In addition the water-cooling system in Spawr's mirrors was a ''single-pass'' system designed to operate at 60 pounds per square inch (psi) pressure, says Spawr. The mirrors used in the ALL were designed with a more sophisticated ''double-pass'' water-cooling system designed to operate at between 200 and 300 psi, according to laser optics experts.
What then were the nine water-cooled copper mirrors that the Air Force purchased from Spawr Optical in 1975 specifically used for? The answer, according to Dr. Wick, is classified.
Did those mirrors play a central role in military vs. essentially civilian research applications in Air Force laser laboratories? The answer is classified.
ACCORDING to court documents and the West German distributor who sold Spawr's products in Europe, Spawr's competitors - both American and European - were selling similar laboratory-grade laser mirrors to the Soviet Union in the mid- 1970s.
Spawr's attorney, William Dougherty, says the government made Spawr's mirrors appear more strategically valuable than they were.
''(Prosecuting attorney) Wu created an aura of national security even though it wasn't there,'' he says.
Wu disputes the contention. He says the Spawr case ''was significant because of the strategic value related to the technology compromised by the illegal transfer to the Soviet bloc.''
In a telephone interview, Wu added: ''There was no known commercial use for those mirrors at the time of trial.''
But according to public documents filed in federal court in Los Angeles in connection with the Spawr case, there was an established commercial use for Spawr's laser mirrors at the time of trial.
According to a legal brief written by Wu, the then-assistant US attorney had been in telephone contact in late 1980 with a California-based manufacturer of industrial laser systems used for precision welding in the auto industry. The firm was Spectra Physics, located in Mountain View. Wu had been told, according to his own legal brief, ''the model 971I lasers made by Spectra Physics probably used Spawr 4-inch water-cooled mirrors.''
The legal brief was written in reply to allegations by Spawr's attornies that Wu had attempted to mislead the federal jury in the Spawr case during his closing argument. Wu views the Spawr case as fitting into a larger context, along with the two other major high-technology cases he prosecuted as an assistant US attorney in Los Angeles.
''The prosecution of Spawr was a turning point from the heretofore lax attitude and detente environment that did not place strategic export enforcement on top of our national concerns,'' Wu says today.
The prosecution was a turning point for the Spawrs, too:
* Since the 1980 publicity about case, the Spawrs have received several death threats.
* The Spawr Optical plant has been vandalized, including having the letters KKK painted in blood across the front of the plant.
* The Commerce Department on Feb. 24, 1981, issued a temporary suspension of the firm's export privileges, citing ''the protection of the national security.'' To date there has been no notification of when the suspension might be lifted or how much longer it will apply.
* The day after the Spawrs were sentenced the Internal Revenue Service put a lien on the company's bank account and then audited Spawr Optical's tax records for the previous three years. When nothing improper was discovered, the IRS turned its attention to the personal income tax returns of each of the Spawrs. Nothing improper was found. The lien was subsequently lifted.
* Spawr Optical's liability insurance coverage was canceled. According to Mrs. Spawr, who handles the company's paper work: ''The carrier's feeling was that they were not sure how safe our business would be with the government being unhappy with us. We have had over 50 false (burglar) alarms since the trial.''
* In court, Walter Spawr was sentenced to six months in prison. Both he and his wife were placed on five years' probation. The firm was fined $100,000.
The Spawrs appealed their convictions on Nov. 3, 1981. They lost. After the US Supreme Court declined in early 1983 to hear the case, Spawr served his sentence from June to November 1983 at Boron Federal Prison in California.
Next: efforts to halt the flow of US technology to the Soviet Union.