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US 7,742,378 B2Granted
Method and apparatus for azimuthal holographic multiplexing using elliptical reflector
AssigneeSTX Aprilis, Inc.
InventorsDavid A. Waldman, Christopher J. Butler, Daniel H. Raguin
Life of this patent
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Abstract
A method and an apparatus for recording at least two multiplexed holograms. Either an object beam or a reference beam is reflected from an aspherical reflecting surface. Either the reference beam impinging on a recording media at the selected storage location or the object beam impinging on the recording media at the selected storage location is rotated through a selected azimuthal angle about an axis that passes through a plane defined by the intersection of the object beam and the reference beam in the recording media, wherein an angle between the object beam and the reference beam impinging on the recording media is preserved.
Claims84
A method of recording at least two multiplexed holograms comprising the steps of
- reflecting either an object beam or a reference beam from at least one aspherical reflecting surface having two focal points, said at least one aspherical reflecting surface having portions that correspond to azimuthal angles spanning an azimuthal arc of 360°, the object beam and the reference beam generated by a coherent light source, thereby causing the object beam and the reference beam to intersect and form an interference pattern at a selected storage location in a recording media at or near one of the two focal points, thereby recording a first hologram at said selected storage location;
- and
- rotating at least one of a portion of the reference beam impinging on a recording media at the selected storage location and a portion of the object beam impinging on the recording media at said selected storage location through a selected azimuthal angle about an axis that lies in the plane formed by optical axes of said portions of the object beam and the reference beam impinging on the recording media,
- wherein said axis passes through the selected storage location, and
- wherein an angle between optical paths of said portions of the object beam and the reference beam impinging on the recording media is preserved, thereby recording at least two azimuthally multiplexed holograms.
2 more elements
A method of recording azimuthally multiplexed holograms in an optical recording media, comprising the steps of:
- (a) predetermining a series of azimuthal multiplexing angles {φj}, wherein j is an integer;
- (b) selecting an angle φa wherein a is an integer and φa is selected from the series {φj};
- (c) directing an object beam and a reference beam that are mutually coherent at a selected data storage location situated along a selected track on the optical recording media,
- wherein the reference beam is reflected from at least one aspherical reflecting surface having two focal points, said at least one aspherical reflecting surface having portions that correspond to azimuthal angles spanning an azimuthal arc of 360°, and
- wherein a portion of the reference beam impinging onto the recording media has an azimuthal angle φa about an axis that lies in the plane formed by optical axes of portions of the object beam and the reference beam impinging on the recording media at or near one of the two focal points;
- (d) repeating step (c) for a plurality of selected data storage locations, thereby recording a plurality of holograms, each at a selected storage location along the selected track on the optical recording media;
- and
- (e) repeating steps (c) through (d) for a different integer a, wherein the subsequent holograms are recorded in the selected track using the storage locations utilized by the previously recorded plurality of holograms.
5 more elements
A method of recording azimuthally and angularly multiplexed holograms on an optical recording media, comprising the steps of:
- (a) predetermining a series of planar-angle multiplexing angles {θi}, wherein i is an integer;
- (b) predetermining a series of azimuthal multiplexing angles {φj}, wherein j is an integer;
- (c) selecting a pair of angles (θa,φb) wherein a and b are integers and θa and φb are independently selected from the series {θi} and {φj}, respectively;
- (d) directing an object beam and a reference beam that are mutually coherent at a data storage location situated along a selected track on the optical recording media,
- wherein the reference beam is reflected from at least one aspherical reflecting surface having two focal points, said at least one aspherical reflecting surface having portions that correspond to azimuthal angles spanning an azimuthal arc of 360°, and
- wherein an angle between portions of the object beam and the reference beam impinging onto a recording media is θa, and
- wherein the portion of the reference beam impinging onto the recording media has an azimuthal angle φb about an axis that lies in the plane formed by optical axes of portions of the object beam and the reference beam impinging on the recording media at or near one of the two focal points.
4 more elements
A method of reading azimuthally and angularly multiplexed holograms recorded in an optical recording media, comprising the steps of:
- (a) predetermining at least one selected multiplexed hologram of a selected storage location along a selected track of recorded storage locations in an optical recording media;
- (b) predetermining at least one of a plurality of azimuthal multiplexing angles {φj}, wherein j is an integer, used to record said selected multiplexed hologram;
- (c) selecting a φa wherein a is an integer φa is selected from the series {φj};
- (d) directing a reference beam at the selected data storage location,
- wherein the reference beam is reflected from at least one aspherical reflecting surface having two focal points, said at least one aspherical reflecting surface having portions that correspond to azimuthal angles spanning an azimuthal arc of 360°, and
- wherein the portion of the reference beam impinges onto the recording media at or near one of the two focal points and has an azimuthal angle φa about an axis that lies in the plane formed by optical axes of portions of the object beam and the reference beam impinging on the recording media and used to record said selected multiplexed hologram, and
- wherein reconstructing the selected multiplexed hologram includes relaying a diffraction pattern from the multiplexed hologram with reconstruction optics to a detector;
- and
- (e) repeating step (d) for a plurality of selected multiplexed holograms previously recorded in data storage locations along at least one selected track for different integer a as may be necessary to read other selected multiplexed holograms, thereby reading a plurality of selected multiplexed holograms, each at a selected storage location along at least one track on the optical recording media.
6 more elements
A method of reading azimuthally and angularly multiplexed holograms recorded in an optical recording media, comprising the steps of:
- (a) predetermining at least one selected multiplexed hologram of a selected storage location along a selected track of recorded storage locations in an optical recording media;
- (b) predetermining at least one of a plurality of planar-angle multiplexing angles {θi}, wherein i is an integer, used to record said selected multiplexed hologram;
- (c) predetermining at least one of a plurality of azimuthal multiplexing angles {φj}, wherein j is an integer, used to record said selected multiplexed hologram;
- (d) selecting a pair of angles (θa,θb) wherein a and b are integers and θa and φb are selected from the series {θi}and {φj}, respectively;
- (e) directing a reference beam at the selected data storage location,
- wherein the reference beam is reflected from at least one aspherical reflecting surface having two focal points, said at least one aspherical reflecting surface having portions that correspond to azimuthal angles spanning an azimuthal arc of 360°, and
- wherein a portion of the reference beam impinges on the selected storage location at or near one of the two focal points;
- wherein the angle between the portion of the reference beam that impinges on a recording media at the selected storage location and a portion of an object beam used to record said selected multiplexed hologram that impinged on the recording media at said selected storage location is θa, and
- wherein the portion of the reference beam impinging onto the recording media has an azimuthal angle φb about an axis that lies in the plane formed by optical axes of portions of the object beam and the reference beam impinging on the recording media and used to record said selected multiplexed hologram, and
- wherein reconstructing of the selected multiplexed hologram includes relaying a diffraction pattern from the multiplexed hologram with reconstruction optics to a detector;
- and
- (f) repeating step (e) for a plurality of selected multiplexed holograms previously recorded in data storage locations along at least one selected track for different integers a and/or b as may be necessary to read other selected multiplexed holograms, thereby reading a plurality of selected multiplexed holograms, each at a selected storage location along at least one track on the optical recording media.
9 more elements
An apparatus for recording holographically stored information comprising:
- at least one aspherical reflecting surface having two focal points, said at least one aspherical reflecting surface having portions that correspond to azimuthal angles spanning an azimuthal arc of 360°;
- at least one additional reflecting surface;
- a motive device for rotating at least one of either the at least one aspherical reflecting surface or the at least one additional reflecting surface about a first axis and, independently, a second axis, perpendicular to the first axis;
- and
- means for directing an object beam and a reference beam that are mutually coherent along their respective optical paths,
- wherein either the object beam or the reference beam is reflected from the aspherical reflecting surface to intersect and form an interference pattern with the reference beam or the object beam at a storage location in a recording media at or near one of the two focal points.
3 more elements
An apparatus for reading and/or recording of holographically stored information comprising:
- at least one aspherical reflecting surface having two focal points, said at least one aspherical reflecting surface having portions that correspond to azimuthal angles spanning an azimuthal arc of 360°;
- at least one additional reflecting surface;
- reconstruction optics for reconstructing at least one selected hologram;
- a detector for detecting the selected reconstructed hologram;
- a motive device for rotating at least one of either the at least one
- aspherical reflecting surface or the at least one additional reflecting surface about a first axis and, independently, a second axis, perpendicular to the first axis;
- and
- a means for directing a reference beam along its optical path,
- wherein a reference beam is reflected from the at least one aspherical reflecting surface to impinge on at least one selected storage location in a recording media at or near one of the two focal points.
6 more elements
Dependencies are inferred from the claim text.