Laser-Optical System of the IBM 3800 Printer

A helium-neon laser, acousto-optical modulator and rotating polygonal mirror are used for the optical design of a computer printout system. This combination of technologies in the printer produces high-quality nonimpact printing at speeds of 23,000 to 52,000 characters per second. A new technique utilizing a cylindrical/toroidal lens pair is described which reduces, by two orders of magnitude, scan line displacement errors produced by the polygonal mirror. The optical design principles and alignment techniques used in the assembly are shown.