Oh. Well, I’d call that death by heat vision if it happened in real life, I just picked a decent range for the purpose of the thread.
Boy, imagine trying to design Superman’s heat vision. You have to be able to direct light out through the same optics that normally bring it it. That would work, I suppose, if you had a hot spot at your retina, since the object and image are conjugate points. But it also means that your retina gets awfully hot. Not a good idea. And imagining vision off while heat vision on won’t save you from that problem. Nor will beamsplitters.
Easier to imagine you’ve got a laser in your head that’s targeted using your eyes. Don’t worry about using the same organs for vision and for shooting. But now your problem is that lasers are horribly inefficient, with most of the energy going into heat. Your head’s going to get awfully hot, and you’ve got to redistribute that heat. And what are you using to pump it? Your best bet is some kind of chemical laser – combine the right chemicals in your chamber, and you get a burst of energy. If your Amplified Spontaneous Emission is high enough (as in some Nitrogen Lasers), you don’t even need a resonant cavity – you get laser-like effcts without really having to build a preecisely-aligned laser.
Considering that you’ve got to create a corrosive, high temperature situation that lasts a short time, I think you ought to take your cue from the Bombadier Beetle. This insect has a tough reaction chamber in its back end where it ciombines chemicals to create a burst of hot, acrid gas that it uses to shoot at attackers. Combine that capability (only with chemical laser gases) with maybe a little optics and put it in a head, targeted with eyes, and you’ve got it. You can easily disspiate the heat from a single blast by waiting between shots.
Gonna take a lot of genetic engineering, though./
As mentioned - genetic engineering.
Need a power surce? Let’s que up some spliced genes from the electric eel. We will scale it up, lots of voltage.
Need chemicals? I’m sure we can produce the need potions with the correct mix of genes, RNA, proteins, and viral bits and pieces.
I don’t see a problem with projecting the beam. We seem to be focusing on our current bodily equipment. Our retinas and corneas may not be transparent at the needed/desired frequency but LASERs and the like project just fine through lenses. No reason why we couldn’t produce something naturally or place as an implant a more perfect lens. Same with reflectors and focusing cells. They abound in nature. We may need some callouses to thicken them up a bit.
Heat disapation? Forget water or air cooling. We’re engineering oil cooling. Cue the sperm whale - we’ll need some DNA and stem cells.
Once assembled - suitable lightning bolt and voila.