FLAT-FIELD POSTOBJECTIVE POLYGON SCANNER

摘要

A general two-dimensional ray-trace analysis is presented for the motion of a geometric focal point over a flat surface provided by a postobjective rotating polygon laser beam scanner. The exact defocus equation is derived for any value of the neutral scan position deflection angle and the polygon rotation angle. The scan nonlinearity is derived for the special case of a zero neutral scan deflection angle. Geometric parameters were found that reduce the peak-to-peak defocus by more than an order of magnitude from that found in previous design approaches. Conditions were also found that reduce scan nonlinearity to less than 2 x 10(-4). Practical limitations, such as large polygons and beam obscurations, encountered in the implementation of postobjective scanning are discussed. [References: 3]