Abstract: The novel transparent sheet contains at least one authenticating image, each image being viewable from the front of the sheet, but only across a cone which preferably is less than 90.degree.. The novel sheet may be adhesively bonded over information areas of a document for authenticating purposes. When such an authenticating image is viewable only from an angle appreciably different from angles at which the document is ordinarily viewed, the image is obscure in that users of the document will notice the authenticating image only when confirming the authenticity of the document. Usually each authenticating image is viewable only across a cone of about 10 to 20 degrees.

Abstract: In known sightline stabilizing apparatus 10 (FIG. 1) a gyro-stabilized reflector 25 maintained in orientation in space about two axes 18 and 26 by gyro means in the mechanism 22. The reflector mechanism is contained in housing 17 and is pivotable about elevation axis 18 in relation thereto. The housing also carries a sensor, e.g. a tv camera providing signals to a remote (non-stabilized) image display device, and is itself rotatable in elevation relative to a platform 16 rotatable in azimuth. The apparatus is normally carried by a vehicle and movements thereof cause servo responses of the mechanism 22 to stabilize the mirror and follow-up movements of the housing and pedestal 16 restore the mirror to the center of its limited motion in the housing. However, changes in elevation angle of the reflector cause rotation of the remote image about the center of its field of view and motion induced changes can rapidly lead to motion sickness in an observer of the image.

Abstract: The invention relates to a stereoscopic viewer for aerial photographs. In this viewer, optical means permit simultaneous examination, through two eyepieces, of corresponding points in two successive panoramic photographs in the film to be examined. The optical means comprise, for each optical path, on the one hand, a set of plane-mirrors and, on the other hand, a rotating system adapted to rotate the images about the corresponding viewing axis, the unit thus assuring an even number of reflections; the adjusting means comprise elements permitting at least one of the rotating systems to pivot about a fixed axis and/or the displacement of at least one of the plane-mirrors.

Abstract: Apparatus is provided for guiding a pellicle-covered photomask or other flat object into viewing position for inspection upon a flat top plate of a stage below the objective of a microscope. The apparatus includes a pair of spaced parallel rails having inwardly extending upper and lower flanges that define opposed keyways in which keybars at the edges of a photomask-carrying paddle slide. To protect the pellicle membrane and to space the latter above the top stage top plate, at entrance ends of the rails, segments of the upper flanges are recessed greater than the width of the paddle to permit a vertical dropping movement of the leading end of paddle onto inlet horizontal guide surfaces. These guide surfaces are broad platforms on which may be deposited the leading end of the paddle.

Abstract: A microscope illuminator containing an incandescent point source of illumination, an aspheric lens with heat absorbing characteristics defining an optical path for the illumination, a cut-off filter and a rotatable dichroic interference filter capable of being moved into the optical path of the illumination and capable of polarizing light as its angle of incidence with respect to the optical path is varied, a condensing lens and a rotatable mirror for receiving the polarized illumination from the dichroic filter and altering the optical path to coincide with the optical axis of a microscope. Additional filters are optionally provided.

Abstract: An optical instrument such as a binoculars has an eyepiece lens unit detachably mounted on an eyepiece mount and comprising an eyepiece lens assembly including an eyepiece lens and an image intensifier tube assembly separably coupled to the eyepiece lens assembly. The image intensifier tube assembly includes an image intensifier tube having a light-sensitive surface lying at the focal plane of the objective lens and a phosphor screen lying at the focal point of the eyepiece lens. When the optical instrument is used to enable the user to see a dark object, the eyepiece lens unit with the eyepiece lens assembly and the image intensifier tube assembly coupled together is attached to the eyepiece mount. For the user to see a bright object, the image intensifier tube assembly is detached from the eyepiece lens assembly, and the eyepiece lens assembly is attached directly to the eyepiece mount.

Abstract: A halftone image is recorded on a photosensitive material by exposing the image to secondary exposing beam that is obtained by imparting to a primary beam two types of intensity modulation. The intensity modulation establishes a transmissivity distribution equivalent to that of a contact screen to which the halftone image is exposed.

Abstract: A microscope inspection slide including at least one examination chamber formed by bonding together a base plate and a cover plate. The base plate having a chamber floor surface raised above a deck surface on the base plate, and the cover plate having a roof surface with a depth control ridge positioned about a portion of the edge of the chamber roof surface. Bonding the cover plate to the base plate forms an examination chamber with the distance between the roof surface and floor surface maintained constant, and entrapped gases and excess fluid allowed to drain from the examination chamber through notches in the depth control ridge.

Abstract: A method and apparatus is provided for adjusting the direction of a beam of radiation by a mirror mounted on a shaft so that the normal to the mirror is inclined relative to the longitudinal axis of the shaft. The shaft is mounted in a bearing for rotational adjustment relative to a supporting structure. This technique and structure may be applied to monochromators or interferometers in which radiation beams must be adjusted in direction to very close tolerances, such as seconds of arc, and maintained in direction with a corresponding stability. The shaft is rigidly secured in the bearing after adjustment by an adhesive so that a stress-free structure is realized in which hysteresis effects due to temperature cycling are minimized.

Abstract: An observation apparatus enabling alternative sighting of two objects (11, 21) placed in two intersection planes (1, 2). The apparatus comprises, in front of its objective lens (42), a reflector (6) comprising a single flat reflecting surface capable of pivoting around the optical axis (41) of the objective, this axis being positioned substantially in the bisector plane (5) or a plane parallel to the bisector plane of the dihedron formed by the two object planes (1, 2) while forming a specified angle with a ridge (3) of the dihedron. The apparatus applies particularly to an audiovisual device for sighting, using a camera, a person or a document placed before him or her so as to be readable in a normal fashion.

Abstract: An optical system comprises a number of optical elements arranged in a housing. The housing may be fixed to the underside of an airship. The system corrects for picture tilt. The housing comprises a first fixed portion, a second portion rotatable relative to the first portion around an axis XX', and a third portion rotatable relative to the second portion around an axis YY' orthogonal to XX'. The combination of the rotating motions of the portions B and C of the housing render it possible to rotate the line of sight of the optical system through more than one half-circle.

Abstract: A laser beam scanning device is disclosed and which includes an optical system that is mounted on a carriage which is movable back and forth along a linear path in front of a target area and which is parallel to the optical path of a projected laser beam. The lens system includes a component on the carriage which is arranged in the optical path for the laser beam and serves to project the laser beam along a second optical path toward the target area and which is normal to the first optical path. The optical system also includes a focusing lens on the carriage which is arranged in the second optical path for focusing the laser beam on the target area. A pair of lenses that are mounted on the carriage as part of the optical system are arranged to form a collimating telescope so as to expand and then collimate the laser beam light for delivery to the focusing lens.

Abstract: Sheeting having images that are viewable within limited angles of viewing from the front of the sheeting are prepared from retroreflective sheeting or from sheeting patterned after retroreflective sheeting, i.e., sheeting having a monolayer of microlenses like the monolayer of microspheres in retroreflective sheeting. A layer of transparent material covers the back surface of the microlenses. Axial markings are disposed behind individual microlenses at the back of the layer of transparent material and the markings are viewable from the front of the sheeting as an image.

Abstract: A multiple port electromechanical optical fiber switch provides for the exchange redirection of one common optical path with one of several other optical paths through the switch. It is particularly useful when one standby laser transmitter must be quickly substituted for any single failed transmitter among a group of several actively operating transmitters. A prism for exchanging the optical paths of two initially parallel beams by means of four refractions at their entry and exit points and at least two internal reflections per beam within the prism is set forth in modified rhombic form with two additional parallel facets that transmit undeflected in the deactivated position one of two beams so as to minimize required shift distance to the prism activated position where it exchanges the optical paths of both parallel beams.

Abstract: An eyeguard for a low light level or night vision rifle sight which does not rely on uniform axial pressure for proper opening comprises a moulded rubber body having a front portion which fits on the viewing end of the sight, a back cup portion angled with respect to the front portion, and a middle thin walled deformable portion to which a single flap is secured. The flap is biased towards a closed position by the resilience of the body but is opened by angular pressure applied by an observer's eye socket to the cup portion.

Abstract: An optical spatial address system wherein a collimated light beam which is deflectable in a predetermined manner strikes a backdrop having one or more sets of reflecting facets thereon to direct the beam to a unique point in a three-dimensional space as defined by the predetermined deflection of the light beam for the case of two sets of facets. The facets are designed to preferably direct the beam from the source from the first set of facets along an axis in three-dimensional space to the second set of facets, the latter facets directing the beam along an axis orthogonal to the direction of the beam impinging thereon.

Abstract: A transmission type illuminating device for stereomicroscopes formed by arranging in the order mentioned a light source, a collector lens, a pair of light source image forming lenses located in positions symmetrical with respect to the optical axis of the collector lens and a relay lens for light source images arranged on the same optical axis as of the collector lens in order that a uniform bright illumination may be always made irrespective of the magnification and a wide uniform oblique light illumination may be also easily made.

Abstract: An articulated arm for conducting the beam of a laser to a point of utilization which moves relative to the laser. In the preferred embodiment the articulated arm is supported in a generally vertically depending manner from a stationary laser. The articulated arm terminates in a focusing clamp assembly which is positioned by an industrial robot. The articulated arm following the motions of the robot. The articulated arm comprises joints through which the laser beam is conducted and which contain mirror assemblies for changing the direction of the laser beam as it passes through each joint. A joint may include a rotary coupling member on a main body providing relative rotation of the axis of one of the incident and reflected laser beams about the axis of the other. The mirror assemblies include adjustable shim mechanisms which provide for the precision adjustment of the mirrors to secure alignment of the incident and reflected laser beam along the intersecting path segments through each joint.

Abstract: An optical apparatus for imaging light from a laser device into a spot shape includes an objective lens for converting parallel rays into a spot-like light, the pupil plane of the objective lens being located at a position conjugate with the emitting plane of the laser device so that the amount of light at the spot will less be changed under variations of emitting angle in the laser device.

Abstract: A device for projecting the image of a reticle in an optical system whose line of sight is represented by the reticle. The collimator is situated at the edge of the pupil of an objective of the optical system. The optical axes of the objective coincides with the line of sight. According to the invention, the collimator comprises two subcollimators arranged along respective orthogonal axes perpendicular to the optical axis. Each collimator forms an image of a radial slit in such a way that the intersection of the two slit images is situated on the line of sight. In this way, focussing error does not give rise to an angular displacement of the line of sight.