Abstract: An autostereoscopic imaging system is disclosed that provides for a three dimensional display of an image to multiple observers simultaneously from a single pair of stereoscopic projectors. The system provides for high quality immersive imagery using a holographic diffractive optical element that is made and configured to contain multiple holograms of optical diffusers, each of the holograms having a common reference beam and being made with each diffuser in a different location. A pair of projectors placed astride the reference beam virtual focus projects a stereoscopic image onto the diffractive optical element, such that the plurality of holograms reconstructs multiple stereoscopic images at multiple locations corresponding to the location where the diffusers were previously located during the recording of each respective hologram. Methods of making the diffractive optical element with a plurality of holograms are also disclosed.

Abstract: A holographic center high mounted stoplight system that includes a light source for providing a nearly collimated beam, an expanding lens responsive to the nearly collimated beam for providing a diverging or converging reconstruction beam, and a stoplight hologram responsive to the expanding beam for producing stoplight illumination. Also disclosed is a holographic center high mounted stoplight system that includes a light source for providing a nearly collimated beam, a light bending hologram for providing a diffracted near collimated beam, and an expanding stoplight lens array responsive to the diffracted near collimated beam for providing non-collimated stoplight illumination.

Abstract: A holographic recording medium is treated to reduce or eliminate unwanted extraneous diffraction in a volume transmission hologram. Surface regions of the medium are desensitized either before or after a holographic recording to reduce the contrast of the holographic fringe pattern along the surfaces, and thereby to eliminate planar phase grating effects. Treatments include applying a burst of gas or vapor to the surface, irradiating the surfaces with highly absorbed incoherent light, thermally treating the recording medium.

Abstract: A method for precisely controlling the overall average diffraction efficiency of a hologram including the steps of (a) providing a hologram layer that includes a hologram formed pursuant to hologram forming exposure and development, (b) coating the hologram layer with a photoresist layer, (c) masking the photoresist layer with a mask having opaque and transparent areas wherein the proportion of the opaque areas relative to the transparent areas is selected pursuant to the desired diffraction efficiency, the opaque and transparent areas being sufficiently small so as to have little noticeable effect when the resulting hologram is played back, (d) exposing the photoresist layer to actinic illumination through the mask transparent areas, (e) developing the photoresist layer to remove the photoresist in the areas illuminated by the actinic illumination to uncover the areas of the recording material corresponding to the transparent areas of the mask, (f) etching the recording material to remove the areas thereof t

Abstract: A hologram efficiency adjusting process that includes scanning the brightness effect of a hologram, which is either the hologram to be adjusted or a hologram representative of the hologram to be adjusted, to provide brightness vs. position information. The brightness information is utilized to produce a variable duty cycle half-tone mask that contains a pattern defining the areas of the hologram which are to be removed, with the pattern being unresolvable by the viewer of the hologram from which holograms have been removed pursuant to the mask pattern. The hologram to be adjusted is then photoresist coated and etched in accordance with the mask. Alternatively, the brightness information can be utilized to directly expose, for example by a laser scanner, photoresist disposed on the hologram to be adjusted.

Abstract: A method is disclosed for forming a multi-layer holographic device 22. A first hologram is formed on a major surface of a substrate 14. The first hologram is desensitized to prevent interaction with a second subsequently formed hologram. The second hologram is formed conterminous with said first hologram.

Abstract: A head-up display for a vehicle, including a primary image reflection hologram supported by a transparent substrate located in the vehicle operator's field of view for the ambient scene in front of the vehicle, a light source for providing playback illumination to the primary image hologram, and a guard hologram in front of the primary image hologram for substantially reflecting ambient illumination that otherwise could spuriously turn on the first reflection hologram, the guard hologram having an angular bandwidth and a spectral bandwidth that are greater than the angular bandwidth and the spectral bandwidth of the primary image hologram, and having an optical density of 2.0 or greater. The guard hologram can be parallel fringe reflection hologram or a slant fringe reflection hologram.

Abstract: A pulsed laser provided a pulsed incident beam which impinges a recording assembly which includes a glass substrate and a recording film adhered thereto. The pulse can be singular or multiple. In either event, the duration of each pulse of light is controlled in such a fashion so that the pulse is long enough to enable it to reflect off of a reflecting element to thereby produce a primary reflected beam. In the recording film, the primary reflected beam can interfere with the incident beam to produce the interference pattern in the film. However, the pulse is not of such a duration to allow a noise reflected beam, such as one from a glass-air interface, to pass through the recording film and interfere with the incident beam or primary reflected beam while those beams are still present. Thereby, noise holograms which might otherwise be recorded in the film are precluded while allowing the primary hologram to be recorded.

Abstract: A helmet mounted display uses a see-through visor holographic combiner to provide, in the normal field of view of a helicopter pilot, a pair of images derived from an image source such as a miniature cathode ray tube. A source of the video display may be an infrared sensor mounted on an external turret underneath the helicopter. The turret rotates in response to helmet movements so that the pilot is continually provided with a dual image from the CRT display which corresponds with the external scene as visible through the visor.

Abstract: Noise is reduced in computer generated holograms (CGH's) by a method of overexposure. The CGH is used to make a master hologram. The master hologram is then used to make a copy from which a succession of other copy holograms is made. Each successive copy hologram is exposed less than the prior ones while increasing brightness uniformity. Consequently, a decreasing amount of change in exposure is required to reach 100% efficiency. The number and orientation of the copy holograms is incorporated into the design of the final optical element. The final hologram is not overexposed, since the amount of exposure has been reduced from the earlier holograms, and can be used in complex optical power systems.

Abstract: A focusing, collimating, and beamsplitting test system for testing laser rangefinders for their beam quality, ranging accuracy, and sight unit alignment. The system includes holographic optical elements in place of conventional mirrors, lenses and beamsplitters. The advantages of this system are that it not only reduces the size and weight of optical elements, but also reduces the number of required elements. Consequently, the resulting test equipment requires less labor to assemble and is more compact and much lighter than conventional test systems.

Abstract: A method of making edge-faded holograms. A holographic recording medium is masked to provide a medium having photo-sensitive and photo-desensitized pixel areas. The photosensitive areas of the masked recording medium are exposed with a holographic image, producing an edge-faded hologram. Both positive and negative image masks may be employed to implement the invention. In a specific embodiment of the invention, the number and/or density of the photo-desensitized pixel areas are arranged in a pattern with the number of desensitized pixel areas increasing with proximity to the edge of the medium. The method may be performed in a single frame procedure or may be performed as a continuous process utilizing a continuous strip of holographic recording medium.

Abstract: A method and apparatus of exposing a hologram to reduce spurious noise holograms. The exposure light source is moved relative to a recording module within predetermined distances that will ensure a blurring of the fringes of a noise hologram that is formed at a distance from a primary hologram while substantially not affecting the primary hologram. The controlled relative movement of the exposure source and the recording module within predetermined limits provide a considerable improvement in reducing the efficiency of spurious noise holograms.

Abstract: A rear window mounted stoplight assembly for a vehicle including stoplight illuminating apparatus for producing stoplight illumination, and a scatter blocking hologram adjacent the stoplight illuminating apparatus for preventing scattered stoplight illumination from being viewable by the vehicle operator. In a particular embodiment, the stoplight illumination apparatus includes an image volume hologram and a source of playback illumination.

Abstract: A computer generated diffraction grating which exhibits multiple order scattering noise is illuminated by a point source to generate a first wavefront which is intersected with a second wavefront to form a desired interference pattern in a recording medium. The point source is moved relative to the recording medium during exposure in order to reduce multiple order scattering noise.

Abstract: A holographic stoplight assembly including a volume hologram having a recorded stoplight image secured adjacent to the inside surface of an automobile window. The volume hologram is selectively illuminated by an illumination source located out of the driver's rearward field of vision and forward of the hologram. Also disclosed is a method for recording a hologram for use in a holographic automobile stoplight system which includes the steps of recording the image of a stoplight in a first hologram, and then recording in a second hologram the playback image of the first hologram.

Abstract: An improved holographic rear window stoplight is provided and includes a hologram member laminated to the rear window surface. Single or multiple hologram layers may be provided. The hologram layers can have a diffraction grating developed in a position relative to the other diffraction grating to provide a folded reflection of light from a source of light of an appropriate wavelength band to indicate a stoplight from a predetermined angle. Alternatively predetermined indicia can be selectively displayed in either a single or multiple layer configuration. The reflection hologram member is transparent when not in use to all observers and remains transparent to the driver even when in use, and thereby prevents any blocking of his field of view.

Abstract: Aberration in an image reflected from a warped surface such as an automobile windshield is corrected by providing an image to the windshield which is predistorted to compensate for the aberration. The predistorted image is created and stored in a hologram by a recording technique wherein a first transmission hologram which records the virtual image of an object is illuminated with a conjugate beam. The beam which is transmitted by the first transmission hologram is reflected off the windshield onto a second hologram recording plate, which is also illuminated by a reference beam passed through the windshield. The desired predistorted image is thereby stored in the second hologram recording plate.

Abstract: A converter hologram providing radially symmetric exposure of coaxially located holograms from an off-axis source and displays utilizing the same.

Abstract: A head-up holographic display for providing a display on a vehicle windshield of a control panel and indications of the vehicle operator's manual movements and manual selection operations on the control panel. The display includes a number of edge-illuminatable hologram layers providing a background display and touch and activation indications. Signals from the control panel selectively illuminate respective layers and portions thereof in response to operations on the control panel to create a windshield display thereof. In a second embodiment, a head-up virtual image background display is provided by a first hologram and dots indicative of the driver's finger position on the control panel are positioned on the background display by selective illumination of a second hologram.