Summary says it all.-- 21 Quest, May 13 2023 Depends what you mean by "optimal range". "Target too far for effective use" is the only distance that would really be meaningful, shirley? (Disclaimer: not a gun person.)-- neutrinos_shadow, May 14 2023 What I mean is, the range that it is sighted to, at which your shot will most likely hit within an acceptable distance of the dot.-- 21 Quest, May 14 2023 Ah. Shirley, then, if you're going to the trouble of adding a rangefinder, you would simply have it adjust WHERE the dot is, so it's accurate at all ranges? (More pondering...) If you shine the varying-colour light from the laser through a prism on it's way to the sight, you can control the position of the dot, without any moving parts. (Er, might be a blurry dot due to the 3-wavelength nature of a multicolour laser diode set...)-- neutrinos_shadow, May 14 2023 A simple transparent lens with very fine and rapid control would suffice. But there's no way that hasn't already been developed and sold to a military.-- Voice, May 15 2023 //Depends what you mean by "optimal range".//
This is the point. What is the optimal range? Let's assume we're talking about rifle rounds. The bullet has the most amount of energy at the point of leaving the barrel. So in terms of amount of penetration/damage the optimal range is near 0. After that the bullet is bleeding kinetic and gravitational potential energy the whole time until it hits the ground. Usually a rifle round is fired at a relatively flat trajectory and so it will retain sufficient kinetic energy to put a hole in someone right up until it runs out of height.
There are plenty of rifle sights with laser rangefinders built in, then there are many levels of calculation that can be built upon that, usually this is packaged as some form of "ballistic computer". There are difficulties here however, the ballistic computer doesn't know the wind, the altitude, the temperature over the whole distance from rifle to target. Then there's whether you want to be waving a visible or IR laser around on a battlefield, that's going to make you quite obvious nowadays.
How you'd want to do it in the real world is use a standalone range finder to get the range to target in a second or two. After that, careful observations of the conditions by a trained and experienced sniper/spotter is the way to go.-- bs0u0155, May 15 2023 random, halfbakery