Abstract: A solar concentrator having a housing that supports at least one photovoltaic cell therein. A heat sink underlies the photovoltaic cell and a transparent cover, preferably glass, protects the surface of the cell. Positive and negative contacts are operatively connected to the cell to transmit the electrical energy generated thereby. A primary optical concentrator is provided in the form of a Fresnel lens. The Fresnel lens has a central facet and a plurality of adjacent facets of varying widths, the width of each successive adjacent facet decreasing in the direction away from the central facet. The radius of curvature of each successive adjacent facet increases in the direction away from the central facet. All of the facets have a peak of the same height and a valley of the same height. The Fresnel lens has a predetermined focal distance and the photovoltaic cell is supported within the housing within the focal range of the lens and at a distance from the lens that is less than the focal distance.

Abstract: Apparatus for graphic arts plate making suitable for exposing diazo plates and the like. A unit providing an exposure bed with a plurality of lamps close to the negative and plate and operating in the ultraviolet region, and another plurality of lamps in the visible light region with a diffused glass top for a work table and for fixing an exposed plate. Separate control units for each exposure lamp to provide uniform radiation from all lamps to the plate.