Updated

At least a dozen cases of lasers (search) being beamed into aircraft cockpits since Christmas are being investigated by the FBI.

The lasers can temporarily blind pilots. A cluster of incidents received wide attention between Christmas and New Year's Day, and the FBI says at least four more have occurred in the past week. Authorities have continued to rule out terrorism.

Transportation Secretary Norman Mineta (search) was briefing reporters Wednesday about the issue at the Federal Aviation Administration's (search) aeronautical research center in Oklahoma City.

Mineta was expected to announce new measures for alerting pilots and preparing them to react when lasers are shined at their aircraft. He was also expected to outline ways to notify law enforcement investigators more quickly.

Last week, a pilot told law enforcement officials that a green light appeared on the nose of his aircraft as it was taking off from the Burbank, Calif., airport.

"To our knowledge there was no danger to the aircraft," said Cathy Viray, spokeswoman for the FBI in Los Angeles.

Last weekend, two pilots near Washington Dulles International Airport (search) reported lasers beamed at them, according to FBI spokeswoman Debra Weierman.

The first incident occurred Saturday and involved a helicopter from the Fairfax County (Va.) Police Department; the other happened Sunday to a US Airways Express (search) flight.

Weierman said the bureau was investigating. There have been no arrests and neither pilot was affected by the laser light, she said.

In Boise, Idaho, a pilot told the FBI that someone was possibly using a red laser on a small plane shortly after takeoff Friday evening, according to Dominic Venturi, the FBI supervisor.

"It did not injure the pilot or any of the passengers on board," Venturi said, adding the FBI believes it has identified the person responsible.

"We feel confident it is not related to terrorism," he said.

Beginning Christmas night, there were reports of lasers pointed at aircraft cockpits in Cleveland, Houston, Colorado Springs, Colo., Medford, Ore., and Nashville, Tenn. Many of the reports described a green beam.

A New Jersey man was arrested and charged last week for aiming a green laser at a small jet flying over his home near Teterboro Airport.

The man, David Banach of Parsippany, said he had been using the device to point at the stars from his back yard.

That type laser pointer, which sells for $119, is the most powerful that can be used in a public place without government regulation, according to Bigha, the company that manufactures it. It produces a bright green beam that can be seen up to 25,000 feet away, and is used by bird watchers, astronomers and lecturers to point out faraway objects.

The FBI and Homeland Security Department sent a memo to law enforcement agencies in November saying they had evidence terrorists have explored using lasers as weapons.

An FAA report released in June found that even the lowest-intensity lasers temporarily impaired the vision of most of 34 pilots who were studied in a flight simulator.