[Laser] Cloud Bounce, Comm or Distance

[Tom Becker]

  A few years ago I built several time-of-flight rangefinders, one of 
which is breadboarded here 
http://forum.sparkfun.com/viewtopic.php?f=14&t=8781&start=120 (scroll 
down a bit), to demonstrate some concepts to a Sparkfun crowd.  It's 
schematic, a simple optical oscillator, is shown earlier in that thread.

One of the last things I did before being diverted to other work was to 
point a fresnel-in-a-bucket receiver with a 5mW 535nm module on it 
straight up.  I got returns from a few low clouds (~1000 feet) despite 
having essentially no electronic gain.  I intend to someday revisit that 
project with a fast logamp optical receiver I developed for a marine 
scanning laser project, also shown in that thread.

Tom