SELF FOCUSING ROS
Original Publication Date: 1993-Apr-30
Included in the Prior Art Database: 2004-Apr-06
Xerox Disclosure Journal
When exposing a photoreceptor using a laser Raster Output Scanner (ROS), the spot size is usually of the order of several thousandths of an inch. The consequential large depth of focus means that relatively crude means can be applied to focus the beam onto the photoreceptor. However, in the case of high resolution imaging, as on microfilm, where the spot size may be as small as one micron, the depth of focus could be below that possible with normal mechanical tolerancing. One method to alleviate this problem is to use a technique developed for optical disk, a technique employing dynamic focusing. As practiced, this technique cannot be applied to flying spot scanners, but disclosed herein is an extension that can be used.