Abstract: A photoinitiator composition comprising a compound which absorbs actinic radiation and directly or indirectly generates free radicals, and an O-acylthiohydroxamate compound or an N-alkoxypyridine thione; photohardenable compositions containing that photoinitiator composition; and photosensitive materials employing same.

Abstract: Imaging materials employing photosensitive microcapsules having improved film speed are disclosed wherein the microcapsules contain a photoinitiator system including an absorber, a coinitiator and an autoxidizer; the absorber is a compound such as an aromatic ketone, the coinitiator and the autoxidizer are different but may be compounds such as N,N-dialkylanilines; the coinitiator and autoxidizer are selected such that free radical generation and oxygen consumption occur with optimum efficiency thereby providing an imaging material having high film speed.

Abstract: An imaging material comprising a support and a layer of photosensitive microparticles on one surface of said support, said microparticles including an image-forming agent and a photosensitive composition containing a polymer which is capable of undergoing cationically-initiated depolymerization and a photoinitiator including a silver halide and an organo silver salt, wherein, after exposing said microparticle to radiation, said microparticles, directly or with additional processing, release said image-forming agent or become permeable to a developer which reacts with said image-forming agent to form a visible image.

Abstract: Imaging systems employing photosensitive microcapsules having improved film speed are disclosed wherein the microcapsules contain a photosensitive composition in which the photoinitiator system includes a photobleachable sensitizer such as a 3-substituted coumarin compound; the invention is particularly useful in providing self-contained imaging systems which are sensitive at 390-500 nm but which can be photobleached to reduce background yellow; an imaging process including a photobleaching step following exposure and development is also disclosed.

Abstract: In operations such as seismic exploration seismic waves are generated at a shot point. The amplitudes of successive samples of seismic waves appearing at a plurality of detector stations variously spaced from said shot point in the wake of generation thereof are converted to digital codes. The codes from all the detectors are transmitted in sequence and on a real time basis by spread spectrum radio pulses to a master station.A plurality of data acquisition units each including a radio transponder and a seismic detector are located at each of a plurality of spaced seismic detector stations in a seismic prospect. A master radio station means is located in or adjacent to the prospect.