How Laser Works

[John Hobson <johnh@haht.com>]

Check out http://www.motorists.com/laser.htm and
http://www.motorists.com/radar1.htm for the details.

Quick summary:
Laser works by timing how long it takes for the signal to bounce back to
calculate a distance. Another measurement taken a split second later gives
another distance. Subtract the differences and divide by the time between
the two signals and you get a speed.

Radar works differently, on the "Doppler shift" principle.