A friend and I were having a debate about whether this is a legitimate combat tactic that has been used. Is there any historical examples?
I'm not exactly sure this counts, if you're only interested in antiquity - but
Outside of Berlin in April of 1945 the Red Army was preparing to assault the strategic Seelow heights in the suburbs of Berlin in order to surmount an incredibly well fortified defensive position, the last before the city its self, along with gaining an overview with which to engage the beleaguered city with artillery and Katyusha rockets. In preparation for the assault by the 1st Belorussian front an array of searchlights had been assembled behind the infantry and tanks in order to illuminate enemy positions and blind the defending troops attempting to stop the advancing soviet army.
After a heavy artillery barrage to soften up the defenders - the 1st Belorussian front advanced with searchlights illuminating the path infront of them. Unbeknownst to the commanders at the time, the artillery barrage had kicked up large clouds of dust and earth scattering the beams and light, and the ensuing chaotic battles did more to obfuscate the view for the Red Army than to clear it. Along with the searchlights not blinding the German defenders it actually silhouetted the advancing soviets and made them easy targets in the confusion of the battle that was beginning to ensue.
The Soviets had to pull back initially after heavy casualties, but would eventually take the heights after a heavy toll on both sides.
Archimedes was legendarily supposed to have devised a defense of mirror shields which could focus the rays of the sun and set attacking Roman warships aflame during the siege of Syracuse.
This is generally held to be myth rather than fact.