I recently received a question in my mail on the alignment of the prism. When i made the technical presentation, I did not know how to align the prisms. I have improved the mounting procedure. Basically what i do is, i take the top of with a Dremel ( a drilling machine). I can then remove the reflective polygon. At the center of the reflective polygon there is an axis. With my Dremel I grind this axis away until i have a small hole at the center of the top plateau of the polygon basis. I put a bit of UV glue in the hole i created and place the prism on top. Then by rotating the prism with respect to a reference point I am able to center it. I then use a UV flash light to fix the prism. Afterwards, I measure how planar the prism is with a displacement meter. The current prism is planar within 5 microns.  The prism can rotate with speeds up to 10.000 RPM, beyond it become too noisy as it is unbalanced.