Abstract: The present invention relates to a holographic optical storage device utilizing a material in which the transfer of photo-induced charges is orientated along the cristallographic axis C of the material. On the faces of the material perpendicular to said axis, two transparent electrodes connected together are arranged so that the field developed between said two faces is zero whatever the uniform illumination superimposed upon the modulation. The selective erasing of a first induced spatial variation in refractive index is achieved by recording a second spatial variation which is the complement of the first, the number of successive record-erase cycles being unlimited.

Abstract: A moveable mask with a pin hole therethrough is disposed between a source of an object beam and a holographic recording medium. The pin hole limits the angular range of rays of the object beam transmitted to the medium, thereby preventing intermodulation distortion caused by rays of the object beam that have large angles therebetween. The mask may be moved to cause all of the rays of the object beam to pass through the pin hole, whereby a hologram is recorded.

Abstract: A hologram which is made by use of a collimated light beam incident upon the hologram at an angle with respect to the line orthogonal thereto is used as an optical element to converge a laser beam in a process of making a hologram lens. Since the hologram made by use of the obliquely incident collimated light beam has a large effective area, a hologram lens having a large effective diameter can be produced.

Abstract: Single crystal electro-optic material useful for recording phase holograms comprises lithium niobate or lithium tantalate doped with iron and silicon.

Abstract: An economical optical system without elements of more exotic optical materials for imaging light rays from an ultra-violet or near ultra-violet light source of an optical instrument.

Abstract: An economical optical system for imaging light rays from a near ultra-violet light source of an optical instrument without elements of special optical materials.

Abstract: A hologram is produced by arranging a plurality of two-dimensional pictures in a predetermined pattern, illuminating each of the two-dimensional pictures with a coherent beam, projecting light emerging from each of the two-dimensional pictures to a screen, a dispersing light on the screen in one direction parallel to the screen and redirecting the light along predetermined courses in the direction parallel to the screen but orthogonal to the one direction so as to form overlapping images of the two-dimensional pictures on the screen. The light from each picture is then redirected onto different positions of a holographic recording medium, and a reference beam is directed toward the medium so as to produce interference with the light from the screen. In one embodiment the screen reflectively disperses the light in the vertical direction and redirects it retroreflectively in the horizontal direction.

Abstract: A phase mask comprised of a rectangular array of phase shifting areas arranged in a pseudo-random pattern is illuminated with a beam of electromagnetic radiation. The array of pseudo-randomly phase shifted beams is focused on a Fourier transform plane on which the power spectrum of the beams distributes in two orthogonal directions from its center maxima. The phase shifting areas are arranged in such a manner that there is an approximately equal number of phase shifts for each of the different phase shifting areas with a constant phase relation between orthogonally adjacent phase shifting areas. The center maxima of the spectrum is confined to a rectangular-shaped area and uniformly distributed by suitably selecting the number of different phase shifts. Coherent noise on the reconstructed image is effectively eliminated.

Abstract: A mask is used to sequentially illuminate successive elemental areas of an object (by changing the position of the mask) to obtain from each relatively small elemental area a diverging object-information component of coherent wave energy which is passed through a relatively large cross-sectional aperture of imaging and/or recording means. The fact that this cross-sectional aperture is so much larger in area than the area covered by any dust or optical defects of the imaging and/or recording means markedly reduces spurious coherent-wave patterns normally produced by such dust or optical defects. Further, since the illumination is not diffuse, no speckle pattern problem exists.

Abstract: Improved apodization filter serving as the field stop of a scanning radiometer and attenuating unwanted light modulation signals when scanning edges of any field of view resulting in more accurate radiometric measurements.

Abstract: A color encoding or dichroic filter for video transmission and method of making the same is provided. The color encoding filter can be used with a vidicon tube to provide color signals for video transmission. The filter comprises a substantially transparent substrate, such as glass, having a plurality of grid patterns superimposed thereon with each pattern individually or in conjunction with an overlapping grid pattern capable of transmitting a predetermined bandwidth of energy. A substantially transparent filler material is utilized to complete the filter structure. The filler material is substantially transparent to the desired transmitted bandwidth of energy and is further optically complementary to the filter material of each individual grid pattern to minimize any refractive scattering of transmitted energy. The filler material also provides both a planar exterior surface to the filter and further permits the filter material of the overlapping grid patterns to be maintained with a constant thickness.

Abstract: The present invention relates to optical systems for the storage in the form of elementary holograms, of pages of binary data, said elementary hologram being stored in a two-dimensional or three-dimensional photosensitive medium. The system in accordance with the invention makes use of a photosensitive storage medium lending itself to the selective erasure of binary data, and which contains optical phase-shift devices which enable a phase-shift of 0.degree. or 180.degree. to be produced between the object beam and the reference beam depending upon whether it is desired to record or to erase the data.

Abstract: A method of decoding composite images of three-dimensional objects which are coded by means of a large number of radiation souces of different perspective and which are decoded by means of a point hologram. The point hologram is produced by means of a flat reference beam and by illuminating a shadow mask in the converging beam. The coordinates of the shadow mask correspond to the point image of the source distribution recorded by a hole camera, while the coordinate differences of the holes of the shadow mask have the same value, or a value increased to scale, with respect to the coordinate differences of the point image function of the object plane of the composite image which was nearest to the source distribution during the recording. The decoding of the composite image is effected by shifting between an illumination lens and the point hologram in an incoherent monochromatic converging beam.

Abstract: A hologram apparatus comprises a rotary plane with a plurality of holograms concentrically or spirally arranged thereon, a light emitting source, and at least one photodetector for reading out reconstructed images of the holograms. During rotation of the rotary plane, the optical path of a light beam from the light emitting source is controlled, whereby the reconstructed images from the respective holograms are focused on the photodetector in succession. Some or all of the holograms are substantially oblong, and the long side and the short side of each oblong extend radially about the axis of the rotary plane and substantially orthogonally to the radial direction respectively.

Abstract: This invention is concerned with methods and apparatus for recording multiple exposure holograms on a film record and displaying reconstructed images of the separately recorded subjects. Means are provided, by the use of simultaneous application of multiple different reference beams, to reconstruct a plurality of images, each of which can be separately controlled in intensity or other random parameter. Also, the recording of the separate subjects can be controlled in a predetermined timed sequence, and the corresponding reconstruction of the plurality of images can be controlled in the same or different timing sequence. Means are provided for recording the separate subjects by keeping the subject and reference beam in fixed directions and rotating the plane of the recording film sheet or strip.Encoding of the hologram record is accomplished by means of a beam scrambler which introduces random parameters, e.g.

Abstract: A non-bleachable liquid absorber for high power laser apodizers which utilizes an annular liquid chamber filled with a dye solution composed of copper nitrate in dimethyl sulfoxide and water.

Abstract: A solid cylindrical recording medium is axially rotatable within a cavity in a transparent block, the medium and the cavity being complementary in shape. The medium and the block have substantially equal indexes of refraction whereby the medium does not refract light transmitted thereto through the block. Transmitted to the medium (through the block) is an object beam, representative of an image, and a reference beam, whereby the medium is exposed and a volume hologram of the image is recorded. A multiplicity of volume holograms of images may be recorded by rotating the medium with respect to the reference beam after each of a multiplicity of exposures.

Abstract: A transparency for reproducing preselected area delineations in colors and intensities thereof variable at will is formed by using an interference pattern formed holographically by the interference of a split laser beam. The transparency has a plurality of mutually exclusive areas each individual area representing a variable color wherein the area or areas representing a particular variable color contains spatial frequency carriers which are oriented differently from the spatial frequency carriers of the other areas. The holographic process of preparing the transparency by separately exposing each area in a different orientation to the interference of the two said laser beams is also disclosed. The process and apparatus for utilizing the separation transparency to form predetermined images wherein the color of the individual areas and the intensity thereof forming such image may be varied at will is also disclosed.

Abstract: A falsification-proof identity card comprises a first transparent layer on the underneath side of which conventional data is applied by printing technology. The card contains a holographic safeguard and additional safety measures such as metal structures, fluorescent structures, safety imprints and the like which are only visible in response to holographic reconstruction and/or other light applications, such as ultra-violet light. The holographic safeguard comprises a second transparent or non-transparent layer which carries on the entire surface which faces the first layer a phase hologram or an amplitude hologram which can be read out by light transmission or by light reflection, depending on the transparency of the layer, and which contains at least the visible data printed on the first layer in a direct recording.

Abstract: A phase mask comprised of a square array of phase shifting areas arranged in pseudo-random pattern is illuminated with a beam of electromagnetic radiation, as a result of which an array of pseudo-randomly phase shifted beams emerges from the phase mask and impinges upon an object transparency to be intensity-modulated thereby and come to a focus on a Fourier transform plane. The power spectrum of the beams distributes in orthogonal directions on the Fourier transform plane from its center maxima in a distinct pattern of series of fringes. The technique of apodization is employed to suppress the fringes to thereby reduce the coherent noise of a hologram to a minimum.