Pentagon officials confirmed yesterday that Waltham-based Raytheon Co., the famous developer of microwave technology, has delivered its first Active Denial System unit that shoots microwavelike heat beams at people - stinging targets with an intense burning sensation comparable to having a hot iron pressed against flesh.

Touted as a "nonlethal'' weapon that could change warfare, the futuristic device resembles a satellite dish mounted on a Humvee.

Some backers are already saying the system could be deployed to Iraq within a year, though military officials declined to say when and where the ADS might be first used.

The weapon, which fires concentrated ``millimeter-wave energy'' waves, is undergoing final tests, said a spokesman for the Pentagon's Joint Non-Lethal Weapons Directorate.

"It gives the military an option between shout and shoot,'' said Mike Booen, vice president of directed energy weapons at Raytheon, which has a $40 million contract with the Pentagon to develop the Buck Rogers-style weapons.

The heat beam is more accurate and shoots farther than a standard M-16 rifle, said Charles "Sid'' Heal, a former Marine who has assisted on the still largely classified ADS project.

One day the heat-beam weapon will be small enough to be mounted on helicopters or tripods stored in car trunks, he predicted. Police departments may also end up buying the devices for crowd control, said Heal, now a commander with the Los Angeles Sheriff's Department.

The weapon, which fires invisible beams at a frequency of 95Ghz, only penetrates skin to less than 1/64 of an inch, making it remarkably safe but highly effective in terms of forcing adversaries to flee, disperse or surrender, Heal said.

Many GIs in Iraq are vulnerable to roadside car-bomb and small-arms attacks because they're hesitant about shooting bullets at suspects, Heal said.

The ADS will give troops an added option to defend themselves, he said.

But critics say the Pentagon, while it should proceed with development of less deadly weapons, is overhyping the ``nonlethal'' nature of the ADS.

Joshua Rubenstein, Northeast regional director of Amnesty International, said Bostonians need look no further than the October tragedy in which an Emerson College student was killed when she was hit in the eye by a pepper-spray pellet fired by Boston police during chaos outside Fenway Park.

He also noted that other alleged ``nonlethal'' weapons, such as Tasar eletro-shock guns, inflict horrible wounds.

"It may well be this heat beam is a worthwhile alternative to just shooting someone,'' said Rubenstein. "But the question is: Are they being used responsibly?''