Abstract: An optical system for 360.degree. image transfer in which spaced primary secondary hyperbolically surfaced mirrors are combined with a refractive lens system and are held in spaced relation by a transparent envelope having inner and outer surfaces generated from the near focal point of the primary mirror to avoid image impairing aberrations, and in which the mirrors are so spaced and concentrically arranged that the entrance pupil of the lens system coincides with the near focal point of the primary mirror, which is centrally apertured to form an aperture diaphragm, and the near focal point of the secondary mirror approximates the apex of the primary mirror, the far focal points of the mirrors coinciding to form a confocal set of mirrors.

Abstract: A filter replaces the oxygen canister of an oxygen breathing apparatus and the air flow path is modified to provide a realistic simulation for training personnel in the use of closed circuit breathing units.

Abstract: A system is disclosed for displaying a life or other size replica of a moboard or other scene in a non-programmed and real or other time manner, whereby said displayed replica constitutes a realistic ambient environmental simulation which may be used to facilitate the training of people in various and sundry situations, such as, for example, in piloting aircraft, tanks, automobiles, and other automotive devices, and the like. As disclosed, a modelboard scene is optically observed by a unique annular probe which forms an annular optical image thereof, rotates said annular optical image, and then timely converts it to a plurality of electrical signals proportional thereto.

Abstract: An optical system for 360.degree. image transfer in which spaced primary secondary hyperbolically surfaced mirrors are combined with a refractive lens system and are held in spaced relation by a transparent envelope having inner and outer surfaces generated from the near focal point of the primary mirror to avoid ray pass through distortion, and in which the mirrors are so spaced and concentrically arranged that the entrance pupil of the lens system coincides with the near focal point of the primary mirror, which is centrally apertured to form an aperture stop (diaphragm), and the near focal point of the secondary mirror approximates the apex of the primary mirror, the far focal points of the mirrors coinciding to form a confocal set of mirrors.

Abstract: The invention utilizes a vertically positioned arc lamp and associated lamp ollector-reflector in conjunction with depending associated secondary and projection mirrors, the projection mirror being convex and centrally apertured to form an exit pupil closely adjacent and above the head of an observer and in the center of a curved projection screen to minimize perspective distortion of image as seen by the viewer. The invention further provides an elimination of shadow effect by the depending relationship of the apparatus and by the recessing of arc lamp electrode through an aperture in the lamp reflector. An adaption of image spacing by recessed fitting of image on film to adapt the film to intended projector image width is also an aspect of the invention.

Abstract: A fresnel lens employs a design that reduces the transmission of stray light to a viewer located at its entrance pupil, said design requiring directional undercutting of selected facets of the lens so as to align the directionally undercut nonimaging surface parallel to the viewer's line of sight. The facets of the lens are arcuately shaped to yield a closer approximation to a glass lens. The lens is of particular use in a visual image display system.