LEO's and Laser

[nr2d]

I was thinking on my way to work this morning, how close to a right angle must the laser hit the reflecting object on a vehicle, such as a license plate, for the LEO to receive a valid speed? How much of the laser will be reflected off into never never land if the LEO is say 30 degrees off of perpendicular? :?

(I drew a simple picture to illistrate what I am asking but I can't paste it for some reason)

Rich Dunklee
NR2D

[ELVATO]

Plates are retroreflective. They will reflect alot of the original light back regardless of the angle it hit. Either way, some light does make it back even if the surface is not reflective.

The more off 90 degrees he hits you, though, the greater the cosine error, which is in the favor of the motorist since it will display a lower speed, though not by much.

[bauzer71487]

Seeing as its impossible for the cop to hit you at exactly 90 degrees, unless he's standing in the road. Definitely the farther off, the more chance of sweeping + cosine error though.