Abstract: A foldable utility cart has a hauling body convertible between erected and folded conditions and tiltable between upright hauling and upturned nonhauling positions. Wheels are connected to the hauling body so as to engage the ground and movably support the body when in its erected condition and upright hauling position, but not support the body when in its folded condition and upturned nonhauling position. An auxiliary support carriage is connected to the hauling body and disposable at transport and stored positions respectively when the hauling body is tilted between its upturned nonhauling and upright hauling positions. When the carriage is disposed at its transport position, it is engaged with the ground so as to support the hauling body freestanding without operator assistance in its upturned nonhauling position out of contact with the ground thereby facilitating conversion of the hauling body between its erected and folded conditions and transport of the body to and from a storage location.

Abstract: An improved foldable utility cart has a hauling body formed by a floor and a pair of opposite wheel-bearing side panels, and a handle assembly mounted to the side panels, adapting the hauling body for manually-powered push or pulling type of locomotion. Pivot plates fixed at opposite ends of the floor mount the side panels for pivotal movement between erected transport positions in which the side panels togehter with the floor form a load supporting cavity in the body and mobilize the body and a folded storage position in which the side panels overlie the floor so as to eliminate teh cavity and immobilize the body for storage. Each side panel has a wall member and a longitudinal tube connected along the exterior of the wall member adjacent to its lower longitudinal edge. The tube has opposite ends at which it and thus the side panel is mounted to the floor pivot plates located outside of the load supporting cavity.

Abstract: An apparatus for varying the vergence of a beam of light from a laser including first and second focusing reflector means; one for receiving the beam of light and another for directing it away from the apparatus in a predetermined direction. Intermediate the two focusing reflecting means, there is provided an arrangement of substantially flat surface reflector means, one of which is moveable for varying the length of the path of the beam of light through the apparatus. In accordance with a preferred embodiment, the two focusing reflecting means comprise parabolic mirrors and the moveable reflector means comprises a piston mirror.

Abstract: A projection screen is formed as at least one reflective holograms each of which, when referenced with a projector, reconstructs a defined observation pupil.

Abstract: Graphic data entry in an interactive graphic display system is achieved by means of an apparatus that provides automatic centering of a pointing laser beam on a hand held cursor. The graphic display system provides a means for displaying and comparing through superposition full size overlaid graphical data and projected graphical data on a common display screen. It includes a steerable pointing laser the beam of which scans the display screen in response to a laser beam deflection circuit. The system also includes laser beam position sensing and indicating circuits which accurately measure the laser beam position. Centering of the laser beam on the cursor at the display screen is accomplished by dithering the beam uniformly about its average position in a discrete dither pattern and utilizing the dither pattern to determine misalignment of the beam's average position with respect to the center of the cursor.

Abstract: A system for sensing the position of a laser writing beam is provided wherein at least two laser beams of unlike frequency are superimposed on the laser writing beam. The combined laser beams are simultaneously deflected in a common optical deflection system. Once deflected, the unlike frequency laser beams are separated from the writing laser beam and focused onto a diffraction grating. The position of the focused beams of unlike frequency on the diffraction grating corresponds to the position of the writing laser beam on the writing media. The focused laser beams of unlike frequency produce a traveling interference pattern on the grating and are diffracted by the grating into a plurality of beams. By sensing the frequency of at least one of the beams diffracted by the grating, the position and movement of the writing laser beam can be determined.

Abstract: A flat PLZT plate is utilized to form erasable images thereon which images may be projected or viewed directly. One embodiment includes electrically conductive islands on one side of the PLZT plate which are surrounded by and electrically isolated from an electrically conductive grid pattern. The portion of the PLZT plate located between an island and the surrounding portion of the grid pattern constitutes a pixel or image forming element. By grounding the grid pattern and applying an electrical charge to selected ones of the islands, an image can be formed on the PLZT plate which can be viewed directly or projected by means of polarized light. In order to form the erasable images on the PLZT plate by optical means, the grid pattern and islands are coated with a layer of photoconductive material upon which a layer of a transparent conductor is coated.

Abstract: A microwave oven has an up-opening oven door which is hinged to be movable in an arcuate path. The door moves between a closed lower position covering an aperture to the cooking cavity in the front surface of the oven cabinet and an open upper position above the aperture. The axis of this arcuate motion is adjacent the upper edge of the oven door and internal to the oven cabinet. Connecting arms extend from pivots within the cabinet through openings in the front surface of the oven cabinet, and connect to the oven door. The front surface of the oven cabinet above the aperture is recessed such that the oven door may be opened substantially beyond a horizontal position to provide access to the oven cooking cavity.

Abstract: Measuring apparatus using the moire fringe concept of measurement to provide a precise digital numeric indication of displacement between two relatively movable members. The apparatus includes an accurately ruled grating or scale, a transducer head in the form of an index grating supported on a movable carriage and a transducer support housing. The scale is secured in a spar which is preferably mounted to the carriage of a machine tool such as a milling machine. The transducer support housing is mounted to the stationery part or bed of the machine tool and is provided with a cantilever spring element which holds the carriage in direct contact with the scale.

Abstract: Measuring apparatus using the moire fringe concept of measurement to provide a precise digital numeric indication of displacement between two relatively movable members. The apparatus includes an accurately ruled grating or scale, a transducer head in the form of an index grating supported on a movable carriage and a transducer support housing. The scale is secured in a spar which is preferably mounted to the carriage of a machine tool such as a milling machine. The transducer support housing is mounted to the stationery part or bed of the machine tool and is provided with a cantilever spring element which holds the carriage in direct contact with the scale.