Environmental Research Institute of Michigan

US Government As Represented by the Secretary of the Army

University of Michigan

Juris Upatnieks

Anthony M Tai

Eric J Sieczka

Stephen Barrett Segall

Charles R Christensen

Bobby D Guenther

A reconfigurable optical method and system for rapidly measuring relative angular alignment of flat surfaces are provided. The method and system can be used to rapidly and simultaneously measure the relative angular alignment of machined flat surfaces of a manufactured part. The system can measure parallelism, perpendicularity or angular alignment of multiple flat surfaces. The system can also be used to set up a range of reference angles to which machined surfaces can be compared.

Optical method and system for rapidly measuring relative angular alignment of flat surfaces

A holographic sight which includes a base having at least one connector for mounting the base on a small arm, and a hologram of a reticle pattern, a compact laser light source for illuminating the hologram, and a power source for the laser diode, each mounted on the base. The sight also includes an achromatizer supported in the path of the light beam for reducing shifts in the position of the reticle pattern due to variations in the wavelength of the light beam emitted from the laser diode. The sight may further include means for circularizing the generally elliptical beam emitted by the laser diode to provide a uniform illumination pattern for the hologram. A brightness adjuster and position adjuster, for varying the brightness and relative position of the reticle, respectively, may also be provided.

Compact holographic sight

A compact, self-contained monolith hologram display apparatus includes a laser diode mounted on an edge of a solid glass plate having a front surface with a hologram mounted thereon. The beam is expanded within the glass plate and is reflected off an opposing mirrored contoured edge surface that collimates the beam and directs it onto an angled reflection grating. The reflection grating is mounted onto an edge which is canted with respect to the front surface. The reflected beam diffracts from the grating and impinges upon the hologram to provide for reconstructed image that has achromatic properties.

Compact hologram displays & method of making compact hologram

A compact head-up display comprising a combiner which combines light energy from an outside view with light energy transmitted within the combiner and diffracted out by means of an upper diffraction grating. The head-up display disclosed further comprises an image source, a collimating lens, and a lower diffraction grating for diffracting the collimated light energy into the combiner.

Compact head-up display

Methods and apparatus for recording and displaying edge-illuminated holograms. Disclosed is a method for producing holograms whereby the reference beam, when recording, and the illumination beam, when displaying the hologram, impinge on the edge of the cover plate placed over the hologram. Edge-illumination of holograms makes possible holographic displays which fit in a volume having very little depth.

Method and apparatus for recording and displaying edge-illuminated

Reference scenes stored in a filter set containing an array of sets of suimposed, holographic, matched filters are optically correlated with input images displayed on an optically-addressed, liquid crystal, light modulator 34. In operation, a selected laser diode is energized to direct a polarized light beam through the collimating lens L1 to the reflecting surface of a polarizing beam splitter 35. After reflecting off the beamsplitter surface, the beam is expanded by positive lens L2 and passed to the liquid crystal modulator. There it is modulated by the input image and reflected; after which it is recollimated by positive lens L2, transmitted by the beamsplitter, and directed to a particular array location of the filter set dependent upon which particular laser diode is energized. The filter set is positioned to be in the back focal plane of lens L4 so that the Fourier-transform of the input image is incident on the particularly located, superimposed matched filter at 31. If the Fourier transformed input image corresponds to one of the superimposed matched filters the incident light beam is diffracted by that particular hologram matched filter to form a spot of light at a predetermined array location of a detector array. The optical correlator finds use as a terminal guidance system in guiding a missile to its target.

Coherent optical correlator

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. Next the conjugate aberrated image of the reference source used to form that hologram is reconstructed by illuminating the hologram with a beam different from the object beam, and finally, a second hologram is formed of the aberrated reference source thereby reconstructed and this second hologram is illuminated with a light beam conjugate to the reference beam used in its formation to produce either a reference beam for the formation of the light line hologram or a reconstruction beam for a conventional light line hologram.

Aberration correction of magnified holographic images

A projector for casting the image of a section of an object recorded on a hologram includes a laser for illuminating a section of the hologram and a lens for focusing a section of the reconstructed virtual image on a screen. The hologram is formed as a cylindrical section surrounding the object, on film, and is stored on a pair of parallel spools. A coherent light beam illuminates a section of the hologram arrayed between the spools and an adjustment mechanism which moves an optical element in the reconstructing beam path and the projecting lens allows adjustment of the illuminated section along an axis parallel to the spools. The projecting lens assembly has an adjustable focal length allowing it to project images at varying depths of the resultant virtual image. The projected image of a section of the object may be changed by rotating the reels to give the effect of viewing the object from differing angles or changing the height of the illuminated section to give the illusion of viewing the object from different heights.

Hologram projector

A sight for determining the direction and distance from a viewer to a target employs a transparent panel containing a hologram of a line of light on a plain background. The line extends from one side of the field of view, near the viewer, away from the hologram, and terminates at its far end in the central portion of the field of view. A coherent light source illuminates the panel to reconstruct a three-dimensional virtual image of the line superimposed on the scene viewed through the hologram. By moving the panel and source relative to the viewer the line may be moved and by adjusting the angle of incidence of the reconstructing wavefront and the position of their source relative to the panel, the extension of the line from the viewer may be manipulated. In alternative embodiments a reticle or distance and direction indicia are formed along the line; a plurality of different lines are recorded on the hologram using reference beams bearing different angles to the recording plate so as to be selectively reconstructable; and the panel is associated with an artillery piece and the line is curved to approximate the trajectory of a projectile.

Growing community of inventors

Ann Arbor, MI, United States of America

Juris Upatnieks