police laser

A couple of friends told me a disturbing story about police using laser.
while they were riding, both experienced a blinding sting. afterwards, they both remembered passing a parked police cruising in a parking lot during the incident. They both concluded that the cop was aiming his laser at their helmets to check their speed.

Can anyone verify if this is the case? I remember reading that police laser requires a flat white surface to work. on cars, they target license plates. But what part of the bike do they target?

-a|ex