The doctoral degree held by Angelo M. Codevilla, a member of the Senate Intelligence Committee staff, is in government, not in physics, as suggested by a story in yesterday's editions about funding for space-based laser weapons.

A classified government study completed last year criticized the pace at which the United States was funding the development of high-energy laser weapons for use in outer space and concluded that such a weapon could be ready for flight testing in 1993 with a total system price tag of $30 billion.

The Pentagon, through its Defense Advanced Research Projects Agency, now has contracts out for all of the major components of a space-based laser system in a consortium that includes Lockheed Corp., TRW Inc. and Eastman Kodak Co.

Many components of the project are highly classified and carry exotic code names such as Lockheed's "Talon Gold" system for optical pointing and tracking gear that enables the laser to spot and fire on pinpoint targets thousands of miles away. But many details of the laser weapon's three major components are known and have advanced to the engineering stage.

A low-powered version of the laser similar to the one under development by these companies destroyed an unarmed and stationary Thor nuclear missile in a still-secret Pentagon test last fall, according to knowledgeable aerospace industry and congressional sources.

The test demonstrated that the radiant light energy from current laser systems is adequate to destroy missiles whose thin outer skin is vulnerable to laser heat, especially when the missile is ascending under the stress of its booster engines.

Though the aged Thor was among the first U.S. nuclear missiles, later generations of missiles, including the current fleet of Soviet liquid-fuel missiles, do not have outer skins hardened against laser attack.

In a 1978 test, a similar laser design using sophisticated tracking technology fired upon and destroyed three TOW antitank missiles traveling at 500 miles per hour, according to public Pentagon reports.

The classified study and these tests show that President Reagan's vision of an ultimate anti-ballistic missile system may not be as far away as some critics have claimed. But even aerospace industry enthusiasts acknowledge that there are formidable technical problems to be overcome if such a system is to be deployed before the next century.

And, if developed, such weapons still face the strategic and political problems posed by U.S.-Soviet treaties. They also may provoke preemptive Soviet strikes to block their deployment or countermeasures to render them ineffective, officials said.

"I think this . . . leads to war in space, not as an alternative to war on earth, but as a prelude to war on earth," said Richard L. Garwin, a physicist and longtime Pentagon weapons consultant who helped develop the hydrogen bomb.

"If I were a Russian planner," said Hans A. Bethe, one of the Manhatten Project physicists who was invited by Reagan to last week's White House announcement, "once I saw these . . . lasers appear in space, I would challenge the United States and say, 'Stop doing that,' and if it didn't stop, I would shoot down all those satellites. I don't see anything else that the Russians can do in that case."

Reagan and his main defense and science advisers have avoided specific references to various laser weapon designs or concepts under study or development since Reagan announced Wednesday night that he would seek "the means of rendering . . . nuclear weapons impotent and obsolete."

In a Washington Post interview published yesterday, George A. Keyworth, the president's chief science adviser said one "very promising" laser concept for defending against Soviet missile attack involved using a giant ground laser in tandem with large orbiting mirrors to knock down enemy missiles.

Keyworth emphasized that the concept was one of many laser ideas and that it faces many technical obstacles which, if overcome, still would make development unlikely in this century. He added that the field of laser technology, however, was the most advanced for producing high-energy space-based weapons to protect the United States from Soviet missile attack.

In response to Keyworth's remarks, a leading congressional expert on laser weapons, Angelo M. Codevilla, a physicist on the staff of the Senate Intelligence Committee, expressed doubt that the concept Keyworth mentioned would be the most desirable, or attainable, goal for Reagan's pursuit of a workable anti-ballistic missile system technology.

"There are other missile-killing lasers than the concept mentioned by Keyworth which are already well into the engineering phase and which everyone knows can be built," Codevilla said.

The classified study was conducted by a General Accounting Office scientist as a review of the Defense Department's 1981 assessment of laser weapon projects. The GAO report is classified secret because the Pentagon data it analyzed was classified.

The Pentagon study concluded that the deployment of "moderate numbers" of chemical laser satellites with beam energies of five megawatts "would place at risk large numbers of ballistic missiles and aircraft in the current Soviet strategic inventory due to their . . . vulnerability."

But the GAO report pointed out that the technology is available now to scale up plans for the satellite to 10 megawatts of beam power using a 40-foot optical mirror. Such a system, generating light energy equal to about 1 percent of a large nuclear power plant's output on earth, could be effective against several Soviet strategic weapons, including the high-altitude Soviet Backfire bomber, the SS20 intermediate-range ballistic missile, low-altitude Soviet satellites and limited numbers of Soviet ballistic missiles, the report said.

An aerospace consultant who has worked on the sophisticated laser and tracking systems, Gerald Oeullette, agreed with the study. "A reasonably good-sized space laser could inflict considerable damage . . . against Soviet strategic weapons ," said Oeullette, who was one of four scientists who first briefed the Senate Armed Services Committee on the feasibility of space lasers in 1979.

Details of the study first appeared last year in Aviation Week & Space Technology magazine and were confirmed last week by congressional and aerospace industry sources. Since the GAO study, the Pentagon has further delayed the development schedule for the laser satellite, postponing indefinitely the 1991 test flight date set by President Carter. Defense planners say they will not make a decision on a test flight date until 1988.

"Realistically, early generations of space-based laser weapons will not provide the important military capability to achieve defensive dominance, but would represent steps toward developing such a system," the GAO study concluded.

The study said a tripling of the current funding for the space laser program could produce flight tests for a scaled-up satellite system by 1993. The cost of the first satellite was estimated at $5 billion and for each additional satellite, $1 billion. At current levels of funding, the Pentagon's program will not produce an operational system before the year 2000. The report noted that the current developmental pace is limited not by research obstacles, but by funding.

The goal of the chemical laser system that is closest to demonstration is to shoot down 1,000 Soviet ballistic missiles in the first 250 seconds of a surprise nuclear attack, according to the Pentagon study.

The chemical laser system, which has yet to be given a name, includes:

* An Alpha laser powered by a chemical reaction of liquid hydrogen and flourine, under development by TRW Inc.

* A 40-foot-wide optical mirror that focuses the laser beam on its target, under development by Eastman Kodak, Corning Glass and Lockheed.

* The "Talon Gold" tracking and pointing system, under development by Lockheed.

When integrated for test flight, this is how the system would work, according to congressional and industry sources:

A laser satellite system capable of seriously blunting a Soviet first strike of 1,000 missiles would require at least 24 orbiting laser platforms arranged in three pole-to-pole orbits. Such an arrangement would ensure that at least eight of the platforms were in range of the primary Soviet missile fields at all times.

Infrared telescopes aboard each satellite could "see" enemy missiles seconds after they were launched and identify them by their "signatures" obtained by earlier satellites and stored in the data base of the on-board computer. The "Talon Gold" tracking gun would use a low-powered laser to point to the target, still 3,000 miles away. The reflection from this tracking laser would direct the large laser mirror to rotate into aiming position on the target.

The satellite then would fire the invisible infrared laser beam across the vacuum of space and bathe the thin skin of the Soviet missile with intense thermal energy.

The missile skin would expand from the added heat, buckle and tear apart. Fuel tanks would explode and the missile's deadly nuclear warheads, still unarmed during the booster stage of flight, would fall to earth.

The missile kill, from the moment the satellite identified its target seconds after launch, to destruction, could take as few as four seconds.

A second laser system under study by the Pentagon would be powered by a nuclear bomb in a still-theoretical design to focus the X-ray radiation from its detonation at dozens of rising Soviet missiles. The X-ray laser, as it is called, would be far more powerful than normal laser light and its ultra-high frequency energy waves would penetrate any missile skin and shatter the structure of the missile like glass.

Another laser under study, the Excimer laser design, needs a large electrical power source and achieves a tighter light wave that could penetrate "hardened" missile skins of the future. A third system, called a particle beam weapon, would fire what amounts to lightning bolts at its targets. It would consist of a stream of atomic particles.

While some technologies look more promising than others now, all present formidable technical problems that could delay development at least into the next century.

Even then, such weapons face what would be a historic debate on the wisdom of abandoning the 20-year-old strategic doctrine that offensive nuclear arsenals are sufficient to deter aggression by both sides.

Said Kurt Gottfried, a Cornell physicist and defense consultant: "If such a system can be constructed, it is the equivalent of putting all of the other side's ICBMs in the garbage can; therefore they are made naked; therefore they won't allow it to happen."