Abstract: An apparatus for measuring edge features of a work piece includes an optical sensor assembly and a reference device. The reference device includes a contact surface configured to contact a surface of the work piece adjacent to an edge of the work piece and a marked surface including a plurality of markings indicating positions relative to the contact surface. The reference device is configured to be coupled to a portion of the optical sensor assembly such that the optical sensor assembly is positioned to capture an image representing a portion of the marked surface and an edge feature of the work piece.

Abstract: An apparatus for measuring edge features of a work piece includes an optical sensor assembly and a reference device. The reference device includes a contact surface configured to contact a surface of the work piece adjacent to an edge of the work piece and a marked surface including a plurality of markings indicating positions relative to the contact surface. The reference device is configured to be coupled to a portion of the optical sensor assembly such that the optical sensor assembly is positioned to capture an image representing a portion of the marked surface and an edge feature of the work piece.

Abstract: Substrates suitable for the production of photopolymerizable elements comprise an adhesive layer capable of providing durable adhesion between a photopolymerizable layer and a plastics film or sheet, wherein the adhesive layer comprises an unsaturated resin having the formula: ##STR1## wherein R.sub.1 and R.sub.2 are the same or different and represent lower alkyl groups having up to 6 carbon atoms, x and y are the same or different and are an integer from 1 to 4 inclusive and n is an integer from 4 to 30 inclusive. The preferred resin is a propoxylated bisphenol A-fumarate condensate. Suitable for the production of photorelief printing plates.

Abstract: A photopolymerizable element suitable for use in the production of photorelief printing plates comprises a film or sheet, an adhesive layer and a photopolymerizable layer wherein the adhesive layer comprises a non-photopolymerizable plastics binder and a photopolymerization initiator comprising an admixture of a compound of the formula: ##STR1## preferably 4,4'-bis(dimethylamino)-benzophenone in an amount 0.01 to 2.0% by weight based upon the weight of the binder and another photopolymerization initiator in an amount 0.1 to 7% by weight based upon the weight of the binder.