Patent ID: 6104523
Filing Date: 2000-08-15
Classification: G02B

Abstract:
A raster output scanner (ROS) imaging system comprising:a light source for generating two coherent light beams in the infrared wavelength range, said two beams being output along an optical path,a photosensitive image plane,a rotatable multifaceted polygon mirror interposed in the optical path between said light source and said photosensitive image plane for scanning said two light beams directed onto the facets of said polygon mirror in a fast scan and cross scan direction across the photosensitive image plane, said two light beams directed against the rotating polygon mirror overfill illuminating each facet,a post polygon mirror optical system to focus said two light beams reflected from said polygon mirror in said fast scan and cross scan directions onto said photosensitive image plane, said post polygon mirror optical system including a f-theta lens group having two cylindrical lens positioned between said polygon mirror and said photosensitive image plane to control the scan linearity of said two light beams on said photosensitive image plane, and a cylindrical mirror for wobble correction of said two light beams along said scanning of lines on said photosensitive image plane positioned between said f-theta lens group and said photosensitive image plane, anda pre-polygon mirror optical system including an aspherical collimator lens positioned in the optical path between said light source and said polygon mirror, an aperture positioned in the optical path between said collimator lens and said polygon mirror, and a cylindrical lens group having four lens positioned in the optical path between said aperture and said polygon mirror, said cylindrical lens group having power only in the cross scan direction, said collimator lens and said cylindrical lens group focusing said two light beams in the cross scan direction at each facet of said polygon mirror while maintaining the collimation of said two light beams after said cylindrical lens group in the scan direction at each facet of said polygon mirror, wherein said two light beams pass through said f-theta lens group positioned in the optical path between said cylindrical lens group and said facet of said polygon mirror.