The patent mentioned in the article is specifically for continuous SLA printing (no pauses for lifting/peeling between layers), which the photon and other similarly-priced models don't do. I have one of the cheap SLA printers, and the lifting can occupy over half the printing time depending on layer height/resin type. The continuous printing machines seem to start in the several-thousand-dollar range.

the rotating reflective polygon patent is this one https://patentimages.storage.googleapis.com/29/68/46/da50635... I think it is even more relevant but somehow it did not get posted.

You'd think laser printers would be prior art - a rotating mirror (usually a hexagon) was exactly how older laser printers would scan across the drum to form out the print.

You have to specify application in a patent. Riken desribed it for 3D printing in 1997 see https://sffsymposium.engr.utexas.edu/Manuscripts/1997/1997-2.... but did not specify the use of laser diode as it was quite new at the time. It got only invented in 1996 by https://en.wikipedia.org/wiki/Shuji_Nakamura who got a patent for the laserdiode but little rewards and fought with his employer over it.

true it is a nice machine.. but laser bundles have advantages. You can direct other wavelengths, sinter powders and get to much smaller features. All these LCD printer, do show a pixel size but not a real spec or accuracy. If you go really high end even for mask projection with UV led you need expensive lights see https://www.idonus.com/activities/products/mems-products/uv-... ... costs around 20K i believe.