It's not really a "ray" because the reflective panels don't direct all the light to one location. It just directs most of the light to a smaller location. To qualify as a "death ray" it would need to be shaped more like a giant magnifying glass.
If they wanted a death ray they could have put all the reflective slabs on remote controlled servos to change the pitch and angle. Then you could do as they did in this link, and melt steel in seconds.
http://www.youtube.com/watch?v=AJot9WKybQE
