| 摘要 |
A linear array of injection diode lasers formed on a common substrate is utilized to provide modulated scanning beams for a photosensitive medium. A scanning device, preferably a multifaceted mirror polygon driven at a constant speed, is placed in the optical path between the array and the photosensitive medium, as is a focusing lens. To provide additive exposure intensity the plane of the emitting surface of the array is oriented relative to the scanning device so that all of the beams emitted by the array are caused to illuminate the same scan line of the photosensitive medium whereby each beam scans the same data spots on the same line of the photosensitive medium such that additive exposure of those spots is achieved. Alternatively, each laser of an array of N lasers could be used to expose only 1/N spots across a scan line thereby lowering the duty cycle for each laser whereby the pulse power emission from each laser can be increased so that one diode laser can provide the required exposure intensity at the photosensitive medium. In those instances where a single laser can expose each spot of a scan line of a photosensitive medium with the required exposure intensity for that photosensitive medium, the emitting surface of the array can be oriented relative to the scanning device so that each beam emitted by an array of N lasers illuminates a different scan line position of the photosensitive medium. As the scanning device rotates, this orientation provides for simultaneous scanning of N scan lines. By properly choosing the orientation of the emitting surface of the array relative to the scanning device consecutive horizontal scan lines can be written with a vertical separation smaller than the separation between the lasers of the array. Advantages of these orientations is that the printing speed can be substantially increased up to N times or the rotation speed of the scanning device can be decreased up to a factor of N or any combination thereof while maintaining the same resolvable spots density.
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