PACS 301 Special Topics: Fair Trade Fall 2009

An optical system for scanning a light beam across an object where the light beam is double reflected by the reflection surfaces of a rotating polygonal mirror. Beam expander optics are included in the light path for the light beam following the first reflection by the polygonal mirror to magnify the beam diameter to fill the length of the reflective surface of the polygonal mirror at the second reflection. The beam expander optics further include lenses for demagnifying scan angle in the light beam following the first reflection. The lenses of the beam expander optics are formed with a Petzval curvature (third order Seidel aberration) to correct for the distortion induced in the optics image plane by the longitudinal shift in the entrance pupil position at the first reflection as the polygonal mirror rotates.