Abstract: A method of and system for compensating for geometric distortion in a two-dimensional image finds fiducial marks in the image plane corresponding to fiducial marks in the object plane. The invention includes performing a matched filter search to locate corner fiducials from an object plane in the image plane. Locating the corner fiducials permits locating the remaining fiducials in the image plane. A centroid calculation makes the location of the fiducials in the image plane more precise and permits the generation of a solution matrix. The solution matrix and a trajectory engine map the pixels in the image plane to compensate for magnification, tilt, pin cushion, barrel, and other types of geometric distortions.

Abstract: Molded block optics system (10) writes and reads data from an optical storage medium and includes first molded optics block (12) for receiving reference beam (60) and original object beam (46) that contains a predetermined data set. First molded optics block (12) includes reflective surfaces (18, 20, 22, and 24) and spatial light modulator (50). Reflective surfaces (18, 20, and 24) include reference beam surfaces (24) and object beam surfaces (18, 20, and 22). Reference beam surfaces (24) direct reference beam (60) to optical storage medium (16) at predetermined location (54). Spatial light modulator (50) modulates object beam (46) and directs modulated object beam (46) to predetermined location (54). Reference beam (60) and object beam (46) form an interference pattern that writes data on optical storage medium (16). First molded optics block (12) also directs reference beam (60) to optical storage medium (16) for generating reconstructed object beam (64).

Abstract: A spindle for providing precise radial location of a disk includes a spindle having a key that extends from one end thereof. The disk includes a hub having a shape that is similar to that of the spindle with a key notch disposed on the peripheral edge thereof that is shaped similar to that of the key in the spindle. The key has two surfaces that come together at an angle to an apex, which apex extends downward away from the spindle and radially outward. The surfaces of the key notch on the hub are longer than that of the key, such that the surfaces of the key can mate with the surfaces of the key notch and slide therealong, such that the spindle is maintained in the center of the hub.

Abstract: Photosensitive polyimides (Ps-PIM) materials have been synthesized that belong to three families of Ps-PIM materials. Through the use of precursors, various catalytic compositions with differing photosensitivities are provided. The results are Ps-PIM materials having increased photosensitivities at wavelengths longer than approximately 330 to 350 nm and an associated catalytic system that is insensitive to oxygen. A variety of applications, including use in holographic systems, are improved by the present invention.

Abstract: A holographic data storage system includes a laser (12) for generating both data and reference beams. The reference beam is deflected by an optic system such that the reference beam can be directed at the surface of a thin holographic storage media (10) to interfere with a data beam to store data in the form of an interference grating. For each Bragg angle associated with a reference beam and a data beam, multiple pages of information are stored in the storage media (10). Each page of information stored at a given Bragg angle is associated with a different Bragg plane. Upon reconstruction of the data, a given reference beam at a given Bragg angle will reconstruct the data in the associated Bragg plane on a detector (42) and will reconstruct data for the same Bragg angle but a different Bragg plane in an off-image plane (88) or (90). This, therefore, allows multiple pages of information to be stored for the same Bragg angle in the same storage region (54).

Abstract: A method and apparatus for reconstructing holographic images is disclosed. A holographic image is recreated from a holographic storage media (10) by passing a reference beam (38) therethrough, which holographic image comprises a composite data image of discrete binary images arranged in an array. A reconstructed data beam (58) is then directed onto a detector array (42), resulting in a reconstructed composite data image (62) formed on the surface thereof. The detector (42) is comprised of a plurality of detector elements or pixels (92) arranged in an array corresponding to the original array of binary data images that are associated with the reconstructed composite data image (62). The reconstructed composite data image is oversampled such that each discrete binary image in the reconstructed composite data image is associated with, for example, four of the detector elements (92) which define pixels. Each group of pixels that is associated with an image is defined as a bixel. A 2.times.

Abstract: Novel photosensitive polymer films are provided that include (1) a polymer carrier having .dbd.N--C(.dbd.O)-- groups; (2) an initiation system for photo polymerization; (3) polymerizable compounds; and (4) other chemicals as appropriate. The photosensitive polymer films demonstrate short pump times, short DRAW times, short fix times, and reduced noise levels equal to one-third to one-fifth the noise level of prior photosensitive polymer films.

Abstract: A holographic storage system and method are provided in which a light source (12) is used to generate a coherent light beam which is split into a reference beam (18) and an object beam (20). The reference beam (18) is directed to the holographic storage medium (22) through use of a reference beam multiplexer (24). The object beam is encoded with a pattern encoder (34) and directed to the holographic storage medium (26). During read out, the object beam is reconstructed and detected by an optical detector (40).

Abstract: A method and apparatus for holographic storage with combined orthogonal phase codes and random phase codes are provided in which a reference beam (18) is encoded with a combination orthogonal phase code and random phase code by a phase encoder (28). A data pattern is imposed on an object beam (20) by pattern encoder (38). Both the reference beam (18) and the object beam (20) are directed to a particular stack site on a storage medium (32).

Abstract: An apparatus for positioning a data and reference beam onto the surface of a holographic storage media (10) includes a laser (16) for generating the reference beam, and a first reflecting surface (18) for positioning the output of the laser (16) along the y-axis. The beam is split into a data beam and a reference beam by a beam splitter (24) with the data beam directed toward an SLM (36) and the reference beam (26) directed toward an angle multiplexing reflective surface (40). The data beam during a record operation is reflected from the surface of the SLM (36) to a transform lens (34) and then to a column (35) on the surface of a holographic storage media (10). The reference beam is reflected from a reflective surface (40) at a predetermined angle determined by the position of the reflective surface (40) to an HOE (46) for redirection to the surface of the storage media (10) to interfere with the data beam. During a data reconstruction operation, only the reference beam is generated.

Abstract: A disk-based holographic storage media includes a disk fabricated from a holographic storage media. A plurality of holographic storage regions are defined within the storage media such that pages of holographic data can be stored therein in the form of an interference grating. A Read/Write head is provided for containing the optics necessary to read information from the holographic storage region and write information thereto. The Read/Write head moves along the radial direction of the disk with the disk stepped by a motor to discrete angular positions, comprising the address of the storage region along with radial positioning of the Read/Write head. Each of the storage regions is diamond-shaped and oriented such that the apexes thereof are oriented along a common radial column line. Adjacent columns have the storage regions disposed in alternating rows or tracks. This allows for a higher packing density.

Abstract: A holographic storage media (10) is fabricated from a thin layer of photopolymer recording media. The photopolymer recording media is disposed between a substrate (48) and a capping layer (56). The media (10) is divided into a plurality of storage regions (54), which are formed within wells (52) to isolate each of the regions (54). During a record operation, a pumping operation is first performed to remove oxygen molecules from the media by bombarding the select region that is to have an interference pattern recorded therein with photons for a predetermined duration of time. Once the oxygen molecules have been depleted, then a data beam is generated with data superimposed thereon and a reference beam generated for interference with the data beam in the storage region (54). This results in the recording of an interference pattern.

Abstract: A package for a holographic storage media disk (10) is provided that is comprised of a super structure (18) that is operable to hold the disk (10). The disk (10) is comprised of a photopolymer material that is formed in a disk-shaped member having a hub (14) disposed at the center thereof. The disk (10) is disposed in the structure (18) and then a cover (24) disposed thereover, the cover (24) being opaque. An access opening (28) is disposed within the cover (24) to allow access to the surface of the disk (10). A hub opening (26) is provided for allowing access to the hub (14). The hub (14) is disposed such that there is a light tight seal relative to the cover (24). A door (32) is provided for reciprocating over the opening (28) to light seal the package when data is not being recorded to the disk (10) or read therefrom.

Abstract: A holographic storage assembly is provided which utilizes a large holographic storage media (36) disposed between two reflecting surfaces (40) and (42). An optics system (44) is disposed between the two reflecting surfaces (40) and (42) is operable to generate both a reference beam (58) and a data beam (50). The data beam (50) and reference beam (58) are generated on a virtual spot plane (100), which is then imaged from the surface of the reflecting surface (42) onto the much larger surface of the media (36). This is operable to record an interference grating at a storage location (56). During a playback operation, a reconstructed data beam (64) is generated and reflected from the surface of the mirror (40) onto a detector (68) in the deflector system (44).

Abstract: A tape cartridge (12) is provided for storing holographic recordings in a longitudinal holographic storage media tape (14). The tape (14) is comprised of a thin holographic storage media such as a photopolymer. A laser (54) is operable to generate a coherent light beam, which is then positioned on a given row of storage regions (42) on the surface of the tape (14). A positioning/angle multiplexing device (90) is operable to both position a reference beam (60) and a data beam (62) onto a select one of the storage regions in a given row on the surface of the tape (14). The tape (14) is incremented a row at a time for each scan operation wherein both the reference and the data beams during a Write operation, and only the reference beam during the playback operation, are moved along a given row. The spinning polygon mirror (56) is utilized to provide both positioning along a given row and angle multiplexing in a select storage region, with the optic system removing the angular information from the data beam (62).

Abstract: A detected image output by a holographic storage system is comprised of a grid of dark and light spots, representing high and low logic states. The image is superimposed onto a grid of detector elements or pixels in a detector. Each of the data bits is represented by a bit image or bixel, which is oversampled by a factor of two along the x- and y-axis by the pixels. A state machine is utilized to generate expected states for each of the pixels and then an energy shifting operation performed to shift energy from a pixel having a higher than expected output value to a pixel having a lower than expected output value. This operation can result in energy being shifted from the left to the right or the right to the left. Column synchronization is performed by defining a set of pixels in a row for each column as a segment with an associated parity bit and row number. Each segment may be output as validated, or may be retained in a buffer until all previous segments in a row have been accumulated and/or output.

Abstract: A package for a holographic storage media (10) is provided that utilizes a slide tray (43) for containing a plurality of slides (102). Each of the slides (102) is comprised of an opaque casing (110), which is operable to hold a sandwich structure (120). The sandwich structure (120) has a gripping mechanism (122) disposed on the edge thereof for allowing the structure (120) to be reciprocated within the jacket (110) for extraction thereof and reinsertion thereof. A gripping arm (156) is operable to attach to a gripping member (124) on a gripping mechanism (122) attached to the slide (102) to extract the slide (102) and place it into a holder (148). The holder (148) is then operable to receive the slide (102) and dispose it in a holographic storage system. The slide (102) can then be written to by interfering a data beam and a reference beam in a predetermined storage location (54) and then the slide again placed into the jacket (110).

Abstract: A holographic storage system includes a storage media in the form of a disk that is operable to incrementally rotate under a moveable optics system contained in a gantry. The gantry reciprocates along the radial axis of the media in response to a drive mechanism. A laser is operable to direct a beam to a mirror that reflects the light beam along the reciprocating axis of the gantry. The gantry contains a spatial light modulator which is operable to receive the incoming light beam and transform it through a transform lens down to a storage location on the surface of the storage media. A reference beam is reflected from a reflecting surface at a predetermined angle and directed to the storage location by an elliptical mirror to interfere with the data beam and perform a record operation. During data reconstruction, when the reference beam is generated a reconstructed data beam is directed toward the reconstruction optics and a detector array. The detector array is also contained on the gantry.

Abstract: A holographic storage media for storing digital data in the form of an interference grating is provided which includes a substrate (48) over which a perforated opaque structure (50) is disposed. The opaque structure (50) has wells (52) disposed therein. In the wells, a photopolymer material (54) is disposed to form data storage regions (54). This is covered by a capping layer (56). The wells (52) are chemically and/or optically isolated from each other.

Abstract: A holographic storage media for storing digital data in the form of an interference grating is provided which includes a plurality of slabs of photorefractive material (72) arranged in a stack, with one edge thereof comprising an incident face (74). A data beam (39) having data superimposed thereon and a reference beam (38) are input to the face (74) to record a holographic image of the data in one of the slabs (72). Each of the slabs has a plurality of adjacent storage regions formed therein. The data and reference beams are disposed in a plane perpendicular to both the face (74) and the side (75) of the slabs (72), such that the reference beam (38) is confined within the slab (72) for all angles of the reference beam (38).