Flat stationary field light beam scanning device

A light beam scanning device (100) and method comprises a first light source (102) for providing a scanning light beam (104) and a flat stationary scanning surface (134) to be scanned by the beam. An f sine theta slens system (136) focuses the light beam onto the flat stationary scanning surface. A galvanometer mirror (138) provides for repetitively scanning the light beam across the flat stationary scanning surface in a first fast scan direction while a pivoting mirror (140,142) provides for receiving the light beam (104) and scanning it onto the galvanometer mirror (138) in a second slow scan direction perpendicular to the first direction. The cooperative operation of the galvanometer mirror (138) and the pivoting mirror (140,142) raster scan the light beam (104) onto the flat stationary scanning surface (134). A second light source (150) generates a reference light beam (152) which is directed onto a rear mirror surface (138B) of the galvanometer mirror (138) from which it is directed to a nonlinear grating (154) having line spacing proportional to 1/(sine theta) for defining the position of the scanning beam in the first direction. The grating (154) is scanned by the reference beam (152) as it is reflected from the galvanometer mirror (138) and passes from the grating to a detector (156) for generating a control signal representative of the position of the scanning light beam (104) in the first direction. The grating (154) may be reciprocally moved relative to the galvanometer mirror to compensate for distortion of the image scanned in the flat stationary scanning surface (134).