Line Screen Focus Wedge
Original Publication Date: 1980-Feb-01
Included in the Prior Art Database: 2005-Feb-13
This article teaches that a line screen mask in which two micron wide chrome lines spaced two microns apart and arranged at a 5-1/2(de- gree) angle with respect to a workpiece, so as to achieve +/- 20 micron depth of focus, produces parallel, sharp infringement bands across the center of the workpiece when the focal plane of the projection printer is in focus with the plane of the product on which the image is being impinged. Off-center bands show out of focus and converging bands show non-parallelism of the focal plane and the workpiece.