ABC TV Perth:
Police are investigating three separate incidents when the police helicopter was hit with high-powered lasers.
Lasers can threaten aircraft safety when they flood the aircraft cockpit with intense light, making it difficult for pilots to see.
The number of laser incidents has been on the rise in recent years - and there's been a series of them in the past week.
A pilot was forced to take evasive action after being hit several times by a green laser beam while flying over Joondanna last Thursday night .
The helicopter crew traced the beam to a house in Yokine where detectives arrested a man and seized a laser.
The helicopter was hit again a short time later and another laser was seized from a house in Joondanna.
A third man was arrested after a similar incident on Friday night.
Police expect to lay charges against three men aged 57, 43 and 35.
The Police Commissioner Karl O'Callaghan says someone could die if people persist in shining high powered lasers at the police helicopter and other aircraft.
Mr O'Callaghan says it will soon be illegal to carry the lasers without a legitimate reason.
He says people shining them at pilots need to think of the consequences.
"This is not fun, this is serious," he said.
"People could get seriously injured or many people could potentially die if offenders keep targeting aircraft with these lasers."
