Optical Stun Ray
It’s been patented; no idea if it actually works.
…newly patented device can render an assailant helpless with a brief flash of high-intensity light. It works by overloading the neural networks connected to the retina, saturating the target’s world in a blinding pool of white light. “It’s the inverse of blindness—the technical term is a loss of contrast sensitivity,” says Todd Eisenberg, the engineer who invented the device. “The typical response is for the person to freeze. Law enforcement can easily walk up and apprehend [the suspect].”