Solar Death Ray

This is pretty neat. Didn't the Mythbusters guys try something like this? Check out the target gallery. Take that Hootie!

I see nothing wrong there. Power estimate is in the ballpark, termal equilibrium discussion a bit simplistic, but basically right...

They did try something like this. They didn't get it to work, though.

Yeah, but they were attempting to focus the light at a much greater distance. We know that it's possible in general, because of the existing Solar Power Towers, but they were testing to see if the Greek army could have done it to destroy attacking triremes.

True, but I thought they started with a scale model and tested how well that worked. I guess I'm not remembering the episode very well

Me either.

That mythbusters episode did indeed do a small mockup and it seemed to work. They also tried various materials but I forget which worked best..
Then they tried it the way the ancient greeks were supposed to do it and it failed. They couldn't get everone to focus in exactly the same spot.
Lastly the tried the large scale mounted version and it did start to heat up the boat, but it look so long and did get hot enough to cause any problems.

You can always use a fresnel lens. It's not been updated in ages though.

Gareth