Wobble correction by two reflections on a facet without bow

Abstract From the Canadian patent

A polygon system for correcting wobble by double reflection from the active facet without bow is disclosed. Instead of the impinging light source being transverse to the axis of rotation of a rotating polygon this rotating polygon 12 having facets at a draft angle to the axis of rotation, a collimated light source 10 impinges upon a rotating polygon 12 with the facets 22 having the predetermined draft angle D. A. and angles of incidence at the first and second reflections. By two further reflections, 18, 20, the light is then reimpinged upon the same facet; wobble is similarly corrected, but with no effects of bow.