Ever wonder how your phone's portrait mode blurs the background so perfectly, or how autonomous cars avoid bumping into things? A huge part of the magic often comes down to a humble yet powerful piece of tech: the laser rangefinder . Forget clunky tape measures or guessing distances. Laser rangefinders are the unsung heroes that let us precisely measure distances with the speed of light. But what's inside these futuristic tools, and how do they actually work  their magic? Let