Abstract: The present invention is directed to a method of selectively pre-exposing a photosensitive printing element prior to imagewise exposure in order to remove oxygen from the photosensitive layer prior to imagewise exposure. The invention is usable in a computer-to-plate process to produce flexographic relief image printing elements.

Abstract: A process of producing a relief image printing plate, the process comprising the steps of providing a photosensitive printing element, quenching dissolved oxygen in the photosensitive resin layer by pre-exposing the photosensitive layer to one or more sources of actinic radiation, wherein the range of wavelengths spanned by the one or more sources of actinic radiation differs by no more than about 20 nm, and imagewise exposing the photosensitive resin layer to actinic radiation to crosslink and cure the photosensitive resin layer. The photosensitive composition typically comprises at least one photoinitiator that is present in the photosensitive composition in an amount sufficient to provide an optical density in the photosensitive composition of between about 0.05 and 0.43 at a wavelength used to pre-expose the photosensitive composition.

Abstract: In accordance with the present invention, there are provided apparatus and methods useful for efficiently subjecting photosensitive materials to a relatively low energy pre-exposure using the electromagnetic energy during the non-imaging portion of the exposure process (i.e., a backscan beam exposure) prior to subjecting such materials to the main imaging exposure (i.e., an imagewise exposure). In a further aspect of the present invention, there are provided combinations and improvements useful for the enhanced imagewise exposure of photosensitive materials. In additional aspects of the present invention, there are provided methods of enhancing the imagewise exposure of photosensitive materials, imagewise exposed photosensitive material made according to such methods, methods for enhancing sensitivity of a photosensitive material for imagewise exposure, and photosensitive materials having enhanced sensitivity for imagewise exposure made according to these methods.