Abstract: A visual aid for nighttime driving of automobiles having an exterior side mounted rear vision mirror wherein a driver tends to be subjected to headlight glare directly from oncoming automobiles and headlight glare reflected by the mirror from following automobiles, having a frame, and a supporting assembly, including a glare reduction arrangement which includes a direct glare portion and a reflected glare portion for reduction of light transmission therethrough. A lens arrangement including the glare reduction arrangement and a frame mounted blocking portion of the glare reduction arrangement may also be used.

Abstract: An element, such as a lens, is mounted on an element holder, such as a lens holder, so as to be constrained with a clearance-free, exact centering fit. The element has three radial faces spaced 120.degree. apart with respect to the center of the element, and the element holder has three abutments spaced 120.degree. apart with respect to a center point about which the abutments are distributed. Upon seating the element in the element holder with the radial faces and abutments in engagement, the element is constrained with the center points of the element and element holder in alignment. The radial faces and abutments are held in engagement by a retainer which also holds the element on the element holder. In accordance with one embodiment of the invention, the element is a plastic lens, and the element holder is a lens barrel, the lens being retained with clearance within the lens barrel by a retaining ring.

Abstract: An optical recursive filtering system in which a signal beam of optical radiation is passed through the optical filtering means a multiplicity of times. The filtering system has an optical Fourier transform means, a spatial filter, optical inverse Fourier transform means and a pair of reflectors in the Fourier plane of the spatial filter. An input signal beam to be filtered is optically Fourier transformed by the transform means and is passed through the spatial filter where unwanted frequencies of the signal beam are attenuated. The filtered beam is reflected by one of the reflectors back through the filter and the second mirror reflects it back through the filter a third time. Subsequent reflections back through the filter with a consequent further filtering of the signal beam can be accomplished by appropriately positioning the reflectors. After multiple filtering passes, the filtered beam is extracted for utilization.

Abstract: A method and associated system for providing interference patterns generated from light, including visible, ultraviolet and infrared, carrying desired information comprises the steps of and associated apparatus for modulating a light beam emanating from a suitable source, in accordance with the desired data or information or signal, splitting the modulated light beam into a pair of component beams, both thereby derived from the modulated beam, reflecting the resultant split beams towards each other so as to interfere optically. Advantageously, beam splitting and reflection may be effected by an essentially integrated, transparent element. Also advantageously, a recording of such interference is made by a positioning photosensitive medium at the point or in the plane of interference.

Abstract: One or more holographic optical elements are placed within an aerodynamic front enclosure. Each element redirects a transmitted electro-magnetic wave to a radiation detector. The holographic optical elements correct by diffraction the aberration in a wavefront caused by transmission through the aerodynamic frontal enclosure. Each holographic optical element corrects for wavefronts coming from different directions.

Abstract: In an apparatus capable of duplicating jacketed and unjacketed microfiche, a bank of clear cylindrical lenses is provided, each lens being divided into segments by a series of substantially opaque baffles. The lenses are used with a corresponding bank of aperture lamps, and are disposed between the lamps and microfiche to provide relatively uniform, collimated light upon an image plane, the side of the lenses closest to the microfiche being flattened, and the baffles having an index of refraction lower than that of the clear segments of the lens.

Abstract: A transfer lens comprises a first field-flattening component of negative power, a second component of positive power providing overcorrect astigmatism, a third component of positive power consisting of a plurality of positive members providing most of the power of the overall lens and whose undercorrect astigmatism is corrected by the overcorrect astigmatism of the second component, and a fourth component of negative power which increases the field angle. The lens is particularly useful in a head-down display having two primary displays from which light travels to a combiner so that the transfer lens produces a combined image. A Fresnel field lens is preferably located at the image position.

Abstract: A method of constructing cylindrical holograms in which the image space is the entire space within the cylinder, and a method of constructing holograms on surfaces of other shapes, such as flat surfaces, both from original cylindrical hologram masters. The method uses cylindrical and other reflectors to recreate pseudoscopic images within the cylindrical volume of original cylindrical hologram masters and to form construction reference waves which are appropriate for the new holograms created within this image space.

Abstract: In a method and apparatus for recording a holographic image on a photosensitive medium or film which is capable of being viewed from a wide vertical viewing angle when illuminated by incoherent light, a source of coherent light (10) is divided by splitter (14) into a reference beam (16) and an image or object beam (18). The image beam is directed toward the object, either a transparency (20) or a three-dimensional object (20a), and the image thereof is focused in the vertical plane by means of an anamorphic lens (30) onto a vertical dispersion element (35) and the image thereon is gathered and focused in the vertical plane by means of anamorphic lenses (36 and 38) onto the film (40). In the horizontal plane, the image is focused by an anamorphic lens (42) onto a horizontal exit pupil forming means which may include horizontal dispersion element (45) and the light therefrom is directed onto the film (40).

Abstract: A device for spacially separating specific spectral regions, preferably of color components from a wideband spectrum which is actively and/or passively radiated by objects. The spectral regions, or color components, are derived from the diffraction orders of a diffraction grating (phase grating), which is disposed in the pupil of an imaging lens and whose groove profile consists of several steps, which produce path length differences which are integral multiples of a specific wavelength.

Abstract: A rotation sensitive ring laser system comprising an optical loop including a polarizing beam splitter in the loop, the laser gain medium being outside the loop, and a quarter wave plate in the path of light emanating from the loop for converting the light into linearly polarized light, the plane of polarization of which is rotating at an angular rate proportional to the angular rate with which the system is rotating in inertial space.

Abstract: An optical system is disclosed which, when utilized in conjunction with an electrographic printer and a laser light source, provides high quality characters at very high print speeds with a minimum of laser power. Horizontal and vertical light beam deflectors are employed to access a hologram in a two dimensional holographic array. The horizontal deflector is controlled by internally generated timing pulses to sequentially step from one column of the array to another, each column corresponding to a printing position on a line of print, while the vertical deflector is controlled by an external electrical signal to position a spatially unmodulated laser beam to illuminate the desired hologram in the column. The illuminated hologram emits a spatially modulated beam that forms an image along a line of print, at a position on a conductive drum corresponding to the column of the illuminated hologram.

Abstract: In a two or three anti-reflection coating, a .lambda..degree./2 layer is replaced by a composite layer.The composite layer is characterized by a higher equivalent inhomogeneity .phi.' than the inhomogeneity .phi. of the .lambda..degree./2 layer.

Abstract: A hologram-containing storage medium is rapidly scanned or swept by a sinusoidal spatial fringe pattern, the spatial frequency of which varies with time. This may be achieved by the use of a suitable light beam deflection system and frequency shift arrangement disposed up-stream of a focussing lens. The deflection system and frequency shift arrangement may incorporate a pair of light beams, such as those obtained from a laser, a source of coherent monochromatic light. A single deflector-frequency shifter, such as an acousto-optic element and an electro-mechanical deflector may be disposed in the path of one of the beams, with a prescribed carrier modulation frequency applied to shift the frequency of that one beam relative to that of the other beams. The modulated beam is deflected and is then directed along with the unmodulated beam through the focussing lens so that the beams combine with each other to form a read-out interference pattern on the hologram.

Abstract: Apparatus for reading optically detectable indicia on a record carrier, such as video information which is recorded in the form of pits on a record medium, for example, a video disc. A source of coherent light transmits a beam to the record carrier. A hologram is interposed between the coherent light source and the carrier, the hologram serving to focus the beam on the record carrier. The intensity of the focussed beam is modulated by the recorded indicia, and at least one photodetector is disposed in an optical path traversed by the modulated beam so as to detect the intensity thereof. In a preferred embodiment, the hologram focusses the beam onto the surface of the record medium whereat it is modulated and reflected therefrom to the photodetector.

Abstract: An on-axis thick phase holographic optical element for use as a lens is fabricated by incorporating two off-axis holograms of two point sources located on opposite sides of the plate made by use of reference beams having a common angle with respect to the photographic media and complementary curvatures in the two cases. The element may be formed either by forming the two holograms in a single photographic emulsion, incoherently relative to one another, using a double exposure technique, or by forming the holograms on two physically separated media and then joining them to one another with their emulsion sides in contact. The resultant elements enjoy the low dispersion and aberrations like a conventional on-axis thin holographic optical element and the high diffraction efficiency like a thick hologram and additionally provide an extremely high ratio of diffracted to undiffracted light energy in the on-axis image.

Abstract: A light scanning apparatus comprises a disk having a plurality of holograms, and a laser beam source for radiating and directing a laser beam (which functions as a reproduction wave) onto the holograms in a sequential order, wherein each of the holograms converges the laser beam toward a corresponding focal point. While the disk and the laser beam are moved relative to each other, the focal point scans an object to be scanned in a particular scanning direction. The laser beam acting as a reproduction wave is preferably a spherical wave laser beam.

Abstract: Visible transmitting and infrared reflecting filter having a substrate formed of a material capable of transmitting visible light or absorbing visible light and having a surface and a coating carried by the surface of the substrate. The coating comprises at least one period of a multilayer stack which is reflecting in the infrared and transmitting at shorter wavelengths. The period is formed of a plurality of layers of high and low index materials with alternate layers being formed of materials having a high index of refraction and the other layers being formed of materials having a low index of refraction. At least one anti-reflection layer is disposed between adjacent layers of the period for matching the layers of the period to each other in the visible so that the transmission of the filter is relatively high over a relatively wide wavelength band at shorter wavelengths while maintaining high reflection and low absorption at the longer wavelengths.

Abstract: A flow chamber includes a flow passage having a knee with a window through which cells in liquid suspension pass. An optical system establishes an observation plane through the passage at the corner enclosed in the knee and illuminates the two portions separated by the corner with light at different wavelengths. Fluorescence of the cells is detected and measured.

Abstract: In the process of reconstruction of a virtual image of a light line having one end disposed at infinity with respect to the observer from a hologram of a shorter light line by shifting the position of the reconstructing light source relative to the hologram with respect to the position of the reference beam during formation of the hologram, aberrations are introduced which vary the attitude of the line image and the location of its end point as a function of the position of the observer with respect to the hologram. To correct the position of the infinity point in the image, a holographic optical element is formed using a two-step process. First a hologram is formed of a light source at apparent infinity.