A little while back while using my drill in the shed i noticed the sun reflecting off the drill bit curved part while slow drilling making a raster dot between all the curved bits of the dill giving multiple scans straight across each part of the bit.
If you used this for 12.5 hz horizontal and reflected off a 4 or so sided mirror
same size but square....for screen size you'd have something a bit different .
My bit wasn't the largest type but i have kept this in mind and went looking to see what was out there .the size of the line is the size between the curved screw part largest i have seen shiny type for this was about 2 inches 30 dollars .
I suppose you could use 2 and have a drill tv