Abstract: An optical imaging system includes an array of optical imaging devices each comprising a device for providing charge amplification in a gaseous medium. A preferred embodiment of such a charge amplification device includes a substrate having a cavity defined therein, an anode surface positioned in the bottom of the cavity and a cathode positioned adjacent the cavity opening. A drift electrode is juxtaposed over the substrate opposite the cavity and defines a region containing a gaseous medium. As ionized charge pairs are established in the gaseous medium due to radiation provided by an external radiation source, electrons are attracted toward the anode where they undergo avalanche multiplication with the gaseous medium under the influence of an intense electric field established between the anode and cathode.

Abstract: A self-propelled portable watercraft, including a deck and hull, an engine, and a waterjet propulsion system, capable of operating while a supply of air is unavailable. The air substitute, consisting of a mixture of oxidizing gas and recycled exhaust gas, is delivered to the engine through a self-actuated control valve. In addition, the waterjet propulsion system is equipped with an intake port at the terminus of a narrow, elongated, hollow downward extension of the hull. The purpose of the extension being to minimize the occurrence of a loss of thrust which can result when the craft is vertically displaced above the surface of the surrounding water.