Method of using variable depth photopolymerization imaging systems

Claim 1

METHOD OF MAKING A VARIABLE DEPTH POSITIVE, CONTOUR, IMAGE ON A SUBSTRATE WHICH COMPRISES COATING THE SUBSTRATE WITH A PHOTOPOLYMERIZABLE COATING COMPOSITION CONTAINING (1) A NON-GASEOUS ETHYLENICALLY UNSATURATED COMPOUND CAPABLE OF ADDITION POLYMERIZATION BY FREE-RADICAL INITIATED CHAIN PROPAGATION, (2) 0.001 TI 1.0 PART BY WEIGHT PER PART OF POLYMERIZABLE COMPOUND OF AN ORGANIC LIGHT-SENSITIVE FREE-RADICAL GENERATING SYSTEM, AND (3) 0.1 TO 10 PERCENT BY WEIGHT BASED ON THE COATING COMPOSITION OF A PHOTODISSOCIABLE NITROSO DIMER HAVING A DISSOCIATION CONSTANT OF 10**-2 TO 10**10 AND A DISSOCIATION HALF-LIFE OF AT LEAST 30 SECONDS IN SOLUTION AT 25*C EXPOSING THE PHOTO-POLYNERIZABLE COATING TO LIGHT HAVING WAVELENGTHS BOTH ABOVE 3400A WHICH EFFECT POLYMERIZATION AND BELOW 3400A WHICH DIISOCIATE NITROSO DIMER TO NITROSO MONOMER, THROUGH A TRANSPARENT FILM OF VARIABLE OPTICAL DENSITY TO LIGHT HAVING A WAVELENGTH OF LESS THAN 3400A AND TRANSPARENT TO LIGHT HAVING A WAVELENGTH ABOVE 3400A, AND DEVELOPING A VARIABLE DEPTH, POSITIVE, POLYMERIC, CONTOUR IMAGE BY REMOVING THE NONPOLYMERIZED PORTION OF THE POLYMER COATING