Abstract: A device for mounting a transparency. The device includes back and front sheets of transparent plastic. The outer edges of the sheets are continuously bonded together. In a preferred embodiment, an opaque coating on the front sheet defines one or more generally rectangular windows. Each window is variously sized to permit the transparency to be viewed therethrough but to prevent light from leaking around the transparency. The sheets are continuously bonded together along three sides of the window to form a pocket between the sheets for mounting the transparency. A slit is formed along a fourth side of the window for inserting the transparency into the pocket.

Abstract: An X-ray tubehead counterbalancing mechanism devoid of springs, cams and chains is disclosed. The mechanism requires only a single adjustment to precisely counterbalance objects, such as tubeheads and the like. The mechanism includes a commercially available gas spring which is used in conjunction with parallel motion linkage assembly which carries the tubehead. The piston rod end of the gas spring is adjustable upwardly or downwardly in a direction substantially normal to the axis of the piston rod by means of a single adjustment screw cooperating with a clevis which pivotally mounts the piston rod. With such adjustment capability, the present mechanism will support and counterbalance tubeheads having wide variations in weight and inertia.