Showing papers on "Holographic optical element published in 1989"

Wide viewing angle avionics liquid crystal display

Abstract: A wide viewing angle avionics liquid crystal display is disclosed which utilizes a planar holographic optical element collimator disposed between the liquid crystal panel and the back light source. Also disclosed a method and apparatus for manufacturing a planar holographic optical element collimator.

Diffraction optics diffusing screen laminate for full color on-axis viewing

Abstract: An optical screen module for full-color, on axis viewing is described. The module has a transmission holographic optical element, a louver filter, and a diffraction optics diffusion screen. Input light is diffracted off-axis by the transmission holographic element, passed through the louver filter and rediffracted on-axis by the diffusion screen. The module can handle full-color light because the dispersion in the transmission hologram is compensated by that in the diffusion screen. The louver filter blocks the undiffracted zero-order light while allowing the light diffracted by the transmission hologram to pass through.

Optical pickup head having a hologram-associated objective lens and optical information processing apparatus using the same

Abstract: An optical pickup head for performing recording, reproducing and erasing of information on an optical disc in an optical system employs an objective lens, which is integrated or combined with a holographic optical element, so that the focusing of a diffraction beam on a photo-sensor is stabilized irrespective of the movement of the objective lens due to the tracking control operation in the optical system.

Analytic optimization for holographic optical elements

Abstract: A method is presented for designing optimal holographic optical elements. The method is based on an analytic ray-tracing procedure that uses the minimization of the mean-squared difference of the propagation vector components, between the actual output wave fronts and the desired output wave fronts. The minimization yields integral equations for the grating vector components that can be solved analytically, in some cases without any approximation. This leads to a well-behaved grating function that defines a holographic optical element.

Sandwich reflection hologram

Abstract: A transmission holographic element (1) composed of a first reflection holographic optical element (2) and a second reflection holographic optical element (3). Reflection holographic optical elements (2,3) are adhesively mated such that the distance separating the two elements is no more than a few wavelengths of the incident light beam (9). The incident light beam (9) passes through first element (2) and is reflected off of the second element (3) which reflects the light beam back towards first element (2) which again reflects the light beam through the second optical element (3). In this manner, two discrete reflection holographic elements (2,3) behave as a single transmission holographic element.

Contact copying of reflection or volume holograms

Abstract: A method of preparing a reflection hologram which includes mounting a transmission hologram in register with a portion of transparent photosensitive holographic material there being present there between a filter to cut out zero order light transmitted through the transmission hologram, there being present on each side of an assembly which includes the hologram and the holographic material a light reflecting surface then causing a beam of light from a laser source to pass through a holographic optical element (H.O.E.) which splits the beam into two beams and causes both beams to scan in register over both the whole surface of the transmission hologram and the holographic material by directing the beams onto both reflecting surfaces so that one beam is reflected from one said reflecting surface and on passing through the transmission hologram takes-up the image information and passes through the filter to cut out the zero order light to the portion of transparent photosensitive holographic material where it interferes with the other beam which is reflected from the other reflecting surface into the holographic material then processing the holographic material to fix the holographic image therein.

Holographic Optical Element with Analyzer Function for Magneto-Optical Disk Head

Abstract: A new holographic optical element, made of a birefringent LiNbO3 substrate, has been developed for magneto-optical, disk heads. The element includes the analyzer function required for magneto-optical signal detection, in addition to focusing and tracking error signal detection functions. The analyzer function was realized by introducing a birefringent grating structure, using proton exchange method. More than 15dB extinction ratios were obtained for the fabricated element.

Method of optimizing holographic optical elements

Abstract: A method of designing a holographic optical element (diffractive grating) that transforms a set of waves into another set of waves in order to minimize aberrations in the phase of the output wavefront, includes the steps: (a) define continuous input parameters that characterize the propagation vector components of the incoming wavefront and the desired output wavefront; (b) formulate integral equations for the optimal grating vector components; and (c) solve the integral equations for the optimal grating vector components to minimize the difference between the actual and desired output wavefronts.

Computer Generated Holographic Optical Elements For Optical Disk Memory Read Write Heads

Abstract: A new concept optical head, using a holographic optical element has been developed. This holographic element combines three optical functions, beam splitter, focusing error detection and tracking error detection optics functions. A polarizing beam splitter function is also combined for magneto-optical disk head use. These holographic optical elements are computer generated holograms fabricated using electron beam lithography technique. A new optical configuration has been designed for this optical head to remove the influence of wavelength variation in the laser diode used for a light source. The off-set signal in tracking error signal has been reduced by introduction of the holograms which are used only for detecting tacking error. The stable operation and high read out S/N ratio have been obtained by applying this holographic optical element.

Holographic polar formatting and realtime optical processing of synthetic aperture radar data.

Abstract: A two holographic optical element (HOE) system for polar formatting of spotlight mode synthetic aperture radar (SAR) data was designed, fabricated, and successfully tested. With the addition of a spatial light modulator, a third phase-compensating HOE, and a Fourier transform lens, the real-time polar formatting of SAR data and SAR image formation was experimentally demonstrated.

A Holographic Optical Element for Non-symmetric Fourier Transform Systems

Abstract: Up to now, the non-symmetric Fourier transform (NFT) of an object has been made using conventional refractive optics such as cylindrical and/or spherical lenses. In this paper, we propose the use of a holographic optical element in conjunction with refractive lenses to improve the design flexibility of NFT systems working with parallel beam illumination. Experimental results are presented.

Application of Third-Order Non-Linearities of Dyed PVA to Real-Time Holography

Abstract: Actually, many experimental investigations for new optical recording materials seem to be very important to permit applications of holography and four-wave mixing techniques. Construction of holographic optical elements (HOE) and filters, aberration corrections and non-destructive testing as well as optical data storage require recording materials of high optical performance.

Method of producing holograms particularly for holographic helmet displays

Abstract: A method of producing a desired hologram for a holographic optical element for use in imaging a multi-dimensional array of points, in which two coherent recording beams are utilized to produce an interference pattern which is recorded to form the desired hologram, characterized in that one or both of the recording beams have an aspherical wavefront derived from one or more intermediate holograms each reconstructed by the use of a read out beam having a geometry and/or wavelength different from the beams for recording the respective intermediate hologram.

Head-up display device

Abstract: PURPOSE:To suppress glaring, to make a glass substrate not shine brightly, and to make an exterior easy to see by diffracting image light by a holographic optical element and superposing it upon light from an external visual field. CONSTITUTION:A driver fixed his or her eyes on a 2nd holographic optical element HOE substrate 8b, but only wavelength light lambdaG of green from a 1st HOE substrate 8a reaches the 2nd HOE substrate 8b and is all diffracted, so other wavelength light beams lambdaR and lambdaB which cause glaring do not reach the eyes of the driver. Further, no light is confined to the glass substrate 9b forming the 2nd HOE substrate 8b. Consequently, the 2nd HOE substrate 8b never shines brightly, and the exterior outside an vehicle is easy to see even in the night and there is no hindrance to safe driving.

Display of holograms

Abstract: A hologram display apparatus comprises a rectangular light box having a rainbow transmission hologram (16) mounted in an aperture (14) in one side wall. The hologram is illuminated by means of a linear light source (18) mounted within the box on an axis generally perpendicular to that of the hologram. Light from the source (18) passes through a condenser and/or holographic optical element (22), past baffles (24), and is reflected by an angled mirror (26) to the hologram. The mirror may either be planar or curved about an axis parallel to that of the light source.

An Efficient Multiple-Image Holographic Optical Element

Abstract: A new holographic optical element that combines the beam-multiplexing properties of binary-phase computer-generated holograms with the efficiency of volume holograms formed in dichromated gelatin is described. Experimental results for an element that improves both the efficiency and signal-to-noise ratio of a computer-generated hologram are presented. The possibility of using this element as an optical interconnect is discussed.

Compact Magneto-Optical Disk Head Using Reflection Polarizing Holographic Optical Element

Abstract: A compact magneto-optical disk head using a reflection polarizing holographic optical element has been developed, which has polarizing beam splitter function and error detection optics functions. As a result of introducing the element into an magneto-optical disk head, a high carrier to noise ratio has been achieved, while simple optics has been used.

Treading on the Tail of the Tiger: A Collaborative Effort in Large-Format Holography

Abstract: The authors discuss the installation Alignment, whose simple elegance rests on a foundation of technical complexity. One of the fundamental components of this work is a holographic optical element 80 in high by 40 in wide. In holography, an increase in scale coupled with a demand for precise color control can escalate technical difficulties exponentially. To meet the technical, conceptual and aesthetic demands of this work, two hnlnoranhir artists rnllahborated tn Three vertical lines of color develop a holographic design syshang in space. They appear sustem that reduced the time and cost pended approximately 6 to 8 ft of experimentation. Many elements in front of a 7-ft curved acrylic of this design system eventually were incorporated into an interstructure. The simple concave active, matrix-based HOE computersculptural form supports a design program. Using this design single 80-x-40-in holographic system, the authors exploited the optical element (HOE). This technical capacity of holography to curved rectangular form proproduce a work that would have ved rea ur for pro been impossible in ny other been impossible in any other vides a frame for the projected medium. lines, emphasizing the light. The foremost line is blue; behind it is a green line, and behind this is a red one (Color Plate D No. la). The lines bend slightly outward, flaring at the top and bottom, like a doubleended flame. When the viewer stands directly in front of the sculpture, the lines overlap and the colors blend together, slowly slipping into white as the viewer recedes. The single achromatic line has a calm, meditative quality (Color Plate D No. lb). This achromatic line becomes more highly colored as the viewer approaches. Passing through these focused lines of light, the viewer is immersed in expanding fans of color that sweep across the arc of the sculpture (Color Plate D No. Ic). Because of the scale of this work, the forms of light and the viewer coexist in the same space. Seen in the context of its environment, other viewers interacting with the light become part of the work as well.

Method and apparatus for the use of holographic optical elements

Abstract: This invention concerns a method and apparatus of using the relatively thin holographic material (HF) of a transmission holographic optical element in such a manner whereby a narrow spectral bandwidth may be achieved. The interference fringe planes (IF) oriented through the depth of the material are interrogated by way of the edge of the holographic optical element whereby the holographlc optical element is caused to respond, in use, in the manner of a relatively thick reflection holographic optical element of considerable effective thickness. The apparatus takes the form of a narrow bandwidth optical filter which is interrogated by a tightly focussed interrogating beam (JRB).

Polarization Properties of High Numerical Aperture Holographic Objectives

Abstract: The polarization properties of high numerical aperture holographic objectives were experimentally and theoretically investigated. A local planar grating model was combined with one-dimensional coupled wave theory to determine the full aperture s and p diffraction efficiency characteristics of this holographic optical element (HOE). To verify the modelling approach, diffraction efficiencies for s and p reconstruction waves were measured at local regions of the HOE aperture and compared to corresponding planar gratings. Good agreement was obtained between the theoretical model and the measured full aperture diffraction efficiency. Results indicated that the control of polarization sensitivity, along with the high diffraction efficiency obtainable with volume holograms suggests promising applications for holographic components in magneto-optic head designs.

Horographic optical element and its manufacture

Abstract: PURPOSE:To improve diffraction efficiency and to obtain excellent stability by providing a resin layer which has formed a surface relief type hologram, on one face of a substrate CONSTITUTION:As for a substrate 1, for instance, a glass plate, a transparent or translucent plastic sheet, etc are used, and on its arbitrary one face, a resin layer 2 which has formed a surface relief type hologram is provided As for the layer 2, a negative type photoresist layer which has formed a surface relief type hologram by a laser exposure, and a development processing can be utilized as it is, and also, a surface relief type hologram resin layer which is reproduced to a thermoplastic resin, etc as a replica can also be utilized A holographic optical element is prepared by forming the negative type photoresist layer which can be developed by a water alkali developer on the substrate by a spinner, a bar coater, etc, thereafter, allowing two interferable luminous fluxes to interfere with each other, recording a linear hologram grating and processing it by a developer In such a way, said holographic optical element has a high diffraction efficiency, its time aging deterioration is not caused and its stability can be improved

Contact print of reflection or capacity hologram

Abstract: PURPOSE: To make it possible to obtain a high quality reflection hologram by providing both sides of an assembly with light reflection surfaces, splitting the ray thereof to two rays by holographic optical element(H.O.E.), directing these rays toward both reflection surfaces and aligning both rays over the entire surface of a transmission hologram and both reflection surfaces of a holographic material. CONSTITUTION: The ray 4 passes by the rotatable H.O.E 5 for splitting the ray to two pieces of low, first order diffracted rays 6, 7. The ray 6 passes a ray attenuating means 8 and heads toward a silver plated mirror 9. The ray reflected by the mirror passes the transmission hologram 10 then a louver filter 22 and heads toward the sheet of a photosensitive holographic film material of silver halide. The ray 7 passes the ray attenuating means 8 and heads toward the silver plated mirror 14 where the ray reflects. The ray heads toward the holographic film material 12 and interferes with the ray 6. If these rays interfere, the interference fringes are formed and are fixed by processing the holographic film. The image of the unexposed silver halide modulating reconstruction wave is arranged in the fringes. The holographic image by reconstruction is thus formed.