More laser stuff

[quk@sievers.com (Phil Payne)]

In message <UPMAIL04.199609180509240706@msn.com> "Mike Miller" writes:

> The doppler efffect has the moving object as the *source* of the measured 
> effect. Most common example is the moving train sounding its whistle/horn. The 
> velocity of the train is added in to the frequency of the oncoming sound waves 
> and subtracted from the receding sound wave. 

The same can be done with a laser.  The speed of light is immaterial - it's the 
frequency that matters.  Although the scattered beam returns to the gun at the 
same speed, its frequency is higher.  If the two are mixed, a delta (see 
Fourier) can be derived.  However - it seems most guns don't work this way - 
they emit a pulse which is timed over the round trip.

--
 Phil Payne
 phil@sievers.com
 Committee Member, UK Audi [ur-]quattro Owners Club