Study of Screenless Lithography.

This report describes a study to find out how screenless lithography works. Screenless lithography is quite similar to conventional lithography except that pictures are reproduced without a halftone. A hypothesis for the continuous tone effect is proposed which says that the ability of a plate to produce ink receptive spots varying in area is due to the point by point sensitivity distribution across the surface of the printing plate. This sensitivity distribution is in turn due to the coating thickness distribution formed by the peak and valley topography of the grained plate. This hypotheses was tested and found to be in agreement with the results of the test.