Hi Steve,

I have made a search and have come accors a number of options.

There is a variety of Polaroid, electrostatic transducers for range finding and distance measuring.

I am not sure which one would suit.

However, there is one 6500 series Polaroid module which is ready made and just to be interfaced with a micro. but the max. distance is only 10 meters far less than what I need. :(

Simon