A high quality nonimpact printer at a speed of 10,000 1/min is realized by a new laser scanning system and an electrophotographic process. The laser scanning system uses a parabolic mirror for correcting line scanning distortion. When a polygonal mirror facet is placed on the axis of the parabolic mirror at about two-thirds of the focal length from the mirror surface, and the focus of the parabolic mirror is on a photosensitive drum surface. The scanning velocity distortion is reduced to less than 0.1% over ±30° of the scanning angle. The confusion circle induced by the parabolic mirror is 1 order of magnitude smaller than the spot size determined by diffraction limit. The tolerance of the length from the rotating mirror to the parabolic mirror for 0.1% distortion over ±30° scanning angle is 10% of focal length. This high speed laser printer has demonstrated the high quality printing of 10-dots/mm resolution.
© 1978 Optical Society of America
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