The personnel halting and stimulation response rifle (PHASR) is a prototype non-lethal laser dazzler developed by the US Department of Defense.
Its purpose is to temporarily disorient and blind a target.
Blinding laser weapons have been tested in the past, but were banned under the 1995 UN Protocol on Blinding Laser Weapons, which the United States acceded to on 21 January 2009. The PHASR rifle, a low-intensity laser, is not prohibited under this regulation, as the blinding effect is intended to be temporary. It also uses a two-wavelength laser
This was/is a thing, but it isn’t made to blind you permanently. It wouldn’t take too much power, really. 8 18650 batteries would probably let you just hold down the trigger for 4 hours non stop.