Thanks for all the input! What I am looking at is the ability to recreate the actual light so that it is visible when it passes through fog/mist and invisible in air and can be reflected off a mirrored surface. I have success doing this with tubes but wanted to see if it could be done with a "Real" light. I found a tutorial for max, but I can not get the angle less than one so my "Real" light always expands. I also have been unable to reflect the light off an object- I can see reflections of the light in the target if it is a mirrored surface, but if I bounce the light off a mirror onto a flat object it is not visible. This optics challenge is very thought provoking! Would it be possible to create an extension for a parallel light?