Hi - does anybody here have any experience with building a laser rangefinder? For a very small robotic application I am trying to figure out a good way to do object detection and avoidance. Sonar is a common choice for this application but I'm not too keen on it for various reasons. Is building a laser rangefinder feasible? I am slightly worried, due to the incredible speed of light. Any pointers? Projects? Anything? Thanks!
-Mike Noone
You can evade the problems with the (perfectly credible) speed of light by modulating your laser beam - search on the HP Tellurometer, which used the technique with microwaves, way back when I was at school.
There are also radio rangefinders using this. You can use more than one tone to range different distances. Doppler can even keep track of everything, once basic range is determined.
greg
Building a laser rangefinder is very dificult especially a short range one.
The most straightforeward laser range finder for short distances uses converging beams from two sources. When the beams strike a surface, the distance between the spots is proportional to the distance to the surface. Use IR lasers and appropriate filters on the camera to increase contrast and make it easier to see the spots.
See Circuit Cellar, November 2005 for an article on the Sharp Microelectronics optical distance sensor.
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