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| Programmable optical interconnect system |
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Segmented hologram for multi-image display
| Details |
Inventors: Andrews, John R.; Rainsdon, Michael D.; Haas, Werner E.;
Assignee: Xerox Corporation (Stamford, CT)
Primary Examiner: Arnold; Bruce Y.
Assistant Examiner: Lerner; Martin
Attorney, Agent or Firm: Finnegan, Henderson, Farabow, Garrett & Dunner
A holographic display includes "segmented" images configured as if positioned in separate viewing "cells" corresponding spatially to preselected subareas of a desired display area with invisible segmenting cell sides. In one embodiment, a polarized conjugate reference light source projects the segmented hologram images form a light-transmissive recording medium into the display area, a multi-element nematic 90.degree. twisted shutter assembly changes the polarization of light emanating from subareas corresponding to the images to be blocked while keeping unchanged the polarization of the segmented images to be displayed, and a sheet polarizer positioned between the multi-element shutter and the viewer blocks from view images from those subareas which the polarization direction has been changed by the multi-element shutter. In other embodiments, light-reflective recording mediums and multi-element nematic shutters having an appropriate guest-host dyes are used. Constantly viewable unsegmented holographic images recorded in the same recording medium as the segmented images or on a separate recording medium can be multiplexed into the display area using a conjugate light source of a different frequency or having a different polarization condition (e.g., unpolarized) from the conjugate light source used to project the segmented images to be selectively displayed/blocked. |
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DETAILED DESCRIPTION As a consequence of the above, it is an object of the present invention to provide a holographic image display wherein one or more of a plurality of holographic images can be selectively displayed or blocked from view, while preventing "look around".
It is a further object of the present invention to provide a holographic display which can discriminate between holographic images to be selectively displayed or blocked from view and contiguous holographic images to be continuously displayed in the display apparatus.
Additional objects and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments thereof, which proceed with reference to the accompanying drawings.
In view of the aforesaid objects, and in accordance with the invention as embodied and broadly described herein, the apparatus for selectively displaying discrete holographic images in respective subareas of a display area comprises a holographic recording medium having a plurality of segmented holographic images stereographically recorded therein.
The images are spatially separated in the medium to correspond to the subareas and each is configured as if bounded by imaginary segmenting planes extending to the rear of the display area with respect to the viewer.
The apparatus further includes a reference light means including a first reference light for illuminating the holographic recording medium to project the plurality of segmented holographic images into the display area.
The apparatus also includes masking means including shutter means positioned between the display area and the viewer and having shutter elements commensurate in extent with the subareas for selectively blocking from view, including "look around" view, one or more of the plurality of projected segmented images.
Preferably, the masking means includes first polarizing means for causing the light from the reference light means that illuminates the holographic medium to be polarized in one direction; the shutter means includes second polarizing means for changing the direction of the polarization of the light emanating from the subareas corresponding to the segmented images to be blocked; and the masking means further includes third polarizing means positioned between the shutter means and the viewer, for transmitting only light polarized in the one direction
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Optical Systems 
