Abstract: A safety-type viewing window assembly for protective housings and protective doors of material-processing machines, such as grinding or metal-cutting machines. The assembly includes a fixed, transparent glass pane coupled along its periphery to a fixed, transparent, puncture-proof or unbreakable protective pane made, for instance of polycarbonate. The glass pane is on the side of the assembly toward the machine and the protective pane is on the side toward the user. The glass pane has a circular opening which is covered by a circular, transparent, rotatable window made of transparent glass which is coupled, on its side facing toward the protective pane, to a rotary drive mechanism. The diameter of the rotatable window is slightly less than the diameter of the opening in the glass pane. The rotatable window is disposed inside the opening in the glass pane, and the gap between the periphery of the rotatable window and the opening in the glass pane is sealed.

Abstract: Viewing aids useful for doors and windows, especially in aeroplanes, comprising as an essential element a pane made of a transparent material, which pane has at least one optically active surface comprising a plurality, i.e. at least two, of prisms, or a Fresnel lens, or a combination of both.

Abstract: An optical fiber bundle 10 is disclosed including a plurality of polymer optical fibers 12 disposed within a rigid sleeve 14. The fibers have been drawn to a draw ratio of at least 1:1.5 prior to placing them within the sleeve, whereupon the structure 13 is heated to induce elastic relaxation of the fibers which contract in length and expand in girth. The expansion within the rigid sleeve results in a close-packed geometry.