OKLAHOMA CITY – Transportation Secretary Norman Mineta announced changes yesterday to the way pilots report lasers being beamed at airplanes – a response to a rash of such incidents in recent weeks.

Mr. Mineta also issued a stern warning that federal officials will aggressively prosecute those caught shining laser beams into cockpits. The bright lasers – usually green – can temporarily blind pilots. “We will not allow careless people making stupid choices to put pilots and their passengers at risk,” Mr. Mineta said.

He said authorities do not believe that people shining lasers at airplanes have terrorist motivations. They suspect that copycats who have heard news reports about the lasers apparently have been involved in some of the more recent incidents.

Mr. Mineta said the Federal Aviation Administration will now require pilots to immediately report laser incidents to air traffic controllers, who would then repeatedly broadcast warnings and quickly notify law officers.

There appears to be no current problem with the way pilots report the lasers to authorities, but the changes will standardize the reporting system and provide police with more timely and detailed information.

A cluster of laser incidents received wide attention between Christmas and New Year’s Day.

Mr. Mineta said in a news conference at the FAA’s aeronautical research center in Oklahoma City that 31 of these incidents have been reported since December 31, including one Tuesday night involving a Southwest Airlines flight in Phoenix.

Nobody was arrested. He said there have been 400 reports of lasers being beamed at airplanes since 1990.

“Shining these lasers at an airplane is not a harmless prank,” Mr. Mineta said. “You are putting other people at risk and law enforcement authorities are going to seek you out and if they catch you, they are going to prosecute you.”

Mr. Mineta said officials are working on possible devices to protect pilots from lasers, including modifications to windshields, but no one solution has emerged.