Hello,
I've been playing with PCX lenses to make a beam expander to reduce the divergence of a laser beam, but why not use a doublet or convex-convex lens and adjust the distance from a laser diode so the light is focused upon a point which is in the far, far distance, for example, 20 miles away? That way you would have no divergence at all for the distance, only a converging beam. Perhaps a lens only a few inches across can't focus a beam to a spot that far away?
OK, after you stop laughing at my stupid question, can someone please make something which is probably painfully obvious to you known to me? I'm bringing this question to the only place I think I can get an answer on this, so many people are clueless with simple optic theory on the other forums I frequent, and I count myself as one of them! Maybe there is a hobby optics forum somewhere?