I own a simple laser rangefinder for home repairs purposes which is pretty great - it can measure the distance to any object with an astounding accuracy (down to 1cm for distances up to 100m). It's fast, works in any light conditions and doesn't require the object measured to have any contrast.
This brings me to my question — why not include a laser rangefinder in DSLRs? This would let the camera focus in the worst possible conditions when the standard methods fail. It also shouldn't be too expensive as cheap laser meters cost as little as $10. Or perhaps I'm missing something and such systems do exist already?
Nikon does produce a series of portable laser rangefinders, but nothing similar for DSLRs. And in case you're wondering - laser rangefinders can use wavelengths invisible to the human eye, so you won't disturb your subject by measuring the distance to them. And you won't be hurting anyone's eyes as most laser rangefinders use Safety Class 1 lasers.