Polygonal mirrors for deflecting light? You’re in good business, a lot of these are made for the laser industry and laser printers. You just got to make sure you use the right search engine terminology otherwise no useful results will turn up.
One innovative thing that can be done with polygonal mirrors is to have each face at a slightly different angle so that the polygonal mirror can scan out multiple parallel projected lines (i.e. multiple light planes) from a single laser beam.
20190817/DuckDuckGo triangle prism mirror
20190817/DuckDuckGo polygonal mirror
20190817/https://www.ebay.com/sch/i.html?LH_CAds=&_ex_kw=&_fpos=&_fspt=1&_mPrRngCbx=1&_nkw=polygon+mirror&_sacat=&_sadis=&_sop=12&_udhi=&_udlo=&_fosrp=1
20190817/https://www.ebay.com/itm/Rotating-Polygon-Mirror-Laser-Scanner-Makes-8-Lines-for-Raster-Scanning/113329858581?hash=item1a62fc6815:g:GQcAAOSwfeZc0KF3:sc:USPSPriority!55422!US!-1
20190817/https://precisionlaserscanning.com/polygon-mirrors/