Archimedes' Death Ray done right

The general idea is lots of mirrors each on a two-axis steerable mount, so it can be pointed in any direction, within limits.

Using cameras and sensors, all mirrors automatically track the sun and the target.

The exciting part is trying to make the design as simple, elegant, and inexpensive as possible (as inexpensive as a design with thousands of individually controlled mirrors can be).

One idea is a single central sun and target tracker which wirelessly (to avoid having to string a cable to every mirror) tells each mirror how to point itself. The orientation computation is done centrally. (Another possibility is distributed computation, but I don't think it is worth it.)

The second challenge is calibrating every mirror so that the central computer knows its position and orientation. This can be done automatically beforehand with some fixed targets. A mirror is directed to do a boustrophedonic raster scan (or an irrational Lissajous scan) until it hits a target, detected by the central camera. Repeat for several targets and sun positions, and the central camera and computer gathers enough information to solve for the position and orientation of the moving mirror. Repeat for each mirror: the calibration process may take a long time, but it's fully automated.

Each mirror can be solar powered, for its steering motor and radio. Then we don't have to string thousands of power cables.