I dont mean to spy on people.. It looks like something of interest. I like to make little projects.. Anyway.. Thank you for the site. It is a bit over my head though. I was looking for something a bit easier.
All you are looking for is a slight modulation in LASER position due to vibeations in a SINGLE pane piece of glass. IIRC basically a small op-amp hooked up to a CdS cell or mabyee a small solar cell catching the light reflected from a reflective surface should work.
Radio shack has a one watt amp runs on a 9 volt
find a small solar cell put a small plug on the cell plug it into the amp,get a small tube glue the cell on the back of the tube it helps block outside noise,,for long distance
binocs work real well to raise the bounce signal