Abstract: A method for cleaning an optical surface such as an eyeglass lens involves the use of a cleaning head having a contact seal for engaging around the perimeter of the surface to be cleaned. The cleaning head defines a shallow cleaning cavity which includes the optical surface and the surface is cleaned by generating in the cavity a high velocity air flow across the surface, introducing a cleaning fluid into the air flow so as to scrub the surface, and terminating the introduction of cleaning fluid while maintaining the air flow to remove any residual cleaning fluid. A particular application of the method to simultaneously clean all four surfaces of the eyeglass lenses of a pair of 3-D glasses is also disclosed.

Abstract: A dome-shaped motion picture projection screen is constructed from an external supporting frame and a plurality of panels that are clipped to the frame by a series of individual fasteners that are hooked into the perforations in the panel and clamped to the frame. Each fastener has a L-shaped fastener body with a pair of hook-shaped pins that project from one end of one limb so that they can be hooked into the perforations in the panel. A screw extends through the other limb parallel to the first limb and can be tightened against a supporting frame member to secure the panel to the frame. By carefully controlling tightening of the screw, localized flattening of the panel at the positions of the hooks can be avoided. The ends of the hooks are so small as to be virtually invisible to the audience.