>
>This is what Like Dave VanHorn said:
>
>         "You simply mix the received light with the transmitted light.
>         Dark means out of phase, bright means in-phase."
>
>I must agree with him but I agree with you too. You can easily modulate a
>laser light by controlling the current. This allows you to send pulses by
>connecting the laser to a square wave generator and then it's possible to
>compare the phase between the incoming and transmitted pulse.

You can do both I suppose, modulate the beam with one carrier, and phase
detect that to get distance, then use the interference rate to get speed,
during the interval that the beam is on.


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