Abstract: An apparatus for reading from a multilayer holographic storage medium with a coaxial arrangement of a reference beam and a reconstructed object beam is described. The apparatus has an objective lens for focusing the reference beam into the multilayer holographic storage medium such that the reference beam has a focal point behind or in front of a reflective layer of the multilayer holographic storage medium, wherein a distance between the objective lens and the multilayer holographic storage medium is set in accordance with an addressed layer of the multilayer holographic storage medium, and an imaging system with a fixed lens of focal length f and a movable lens of focal length f for re-collimating a reconstructed object beam, wherein for a specific position of the movable lens the imaging system assumes a 4f configuration.

Abstract: An optical disc for micro-holographic data storage, including: optically-enabled material configured to store holographic data; guide grooves; a first coating disposed on the guide grooves and configured to reflect a tracking beam and to transmit a read or record beam; and a second coating disposed to cover the guide grooves and disposed on the first coating.

Abstract: The present invention relates to a holographic storage system, and more specifically to a method for pixel detection in a coaxial holographic storage system. In a holographic storage system according to the invention, with a coaxial arrangement of an object beam and a reference beam the bright pixels within the object beam have a phase shift of essentially ? relative to the reference beam. For readout of a data page contained in a reconstructed object beam a detector detects an interference pattern generated by the interference between the reference beam and the reconstructed object beam.

Abstract: Techniques are provided for controlling the reading of optical data from a master disk in a holographic replication system. Imperfections in the master disk or movement of the disk during a recording process may cause source beams to deviate from target data tracks. In some embodiments, a detector system is used to determine the focus and alignment of the source beams on the master disk, as well as the tilt and rotation of the disk with respect to the holographic replication system. The detector system may detect deviations in the intensity distribution of the reflections of the source beams and generate an error signal corresponding to focusing, tracking, tilt, and/or rotational errors. Servo-mechanical devices may actuate optical components to compensate for such errors.

Abstract: A signal quality evaluating method necessary for a signal quality evaluation index and a margin design is provided for an apparatus utilizing hologram recording techniques. An evaluation index is used being obtained by dividing root sum square of standard deviations of luminance value distribution of on- and off-pixels obtained from reproduced signals, by a difference between average values.

Abstract: HROM replication methods, devices or systems are disclosed herein. Also disclosed herein are articles comprising conical reference (reconstruction) beam hologram elements to generate conical or conical like reference (reconstruction) beams which may be used in such HROM replication methods, devices or systems. Further disclosed herein are articles comprising a target medium which may be used in such HROM replication methods, devices or systems.

Abstract: A data page for use in a holographic data storage system, and to a method and an apparatus for writing to holographic storage media using such a data page are described. The data page has dark zones for each boundary between phase blocks of a phase mask of the holographic data storage system, which consist of switched-off pixels that are not used for encoding data, and which coincide with the boundaries between the phase blocks.

Abstract: In a recording apparatus capable of performing a curing process at high speed by curing a plurality of books at a time during recording and capable of performing recording of a recordable type, when recording is stopped once, the unit of books to be cured at a time is set smaller than that during continuous recording, in order to realize inexpensively both performing a curing process at high speed in hologram recording and realizing recording of a recordable type freely in a book unit. It is therefore possible to terminate recording in the unit of arbitrary books irrespective of the unit of books to be cured, and perform recording of a recordable type without loss.

Abstract: An optical information recording method of recording information three-dimensionally by irradiating a laser light beam onto a medium having a servo information plane on which address information and/or servo information is recorded, is disclosed. The method includes the steps of: dividing a laser light beam from one laser light source into laser light beams, the beam including a first light beam for reading the information, and a second light beam for recording information onto the recording medium; irradiating the first light beam onto the servo information plane to read the information from reflected light of the first light beam to read the information in which optical axes of the first light beam and second light beam are arranged coaxially; and irradiating the second light beam based on the read information to be focused onto a position in a depth direction perpendicular to a horizontal direction of the recording medium.

Abstract: Disclosed is an optical recording method. The optical recording method includes irradiating an area where a recording mark is formed in a medium with a pulse train of laser light, and irradiating the area where the recording mark is formed with continuous-wave laser light that is continuously output.

Abstract: The present techniques provide techniques for outputting counter-propagating parallel light waves to pre-record a holographic data disk. The parallel light waves are transmitted through a holographic system via a fiber optic bundle including a plurality of polarization-maintaining (PM) optical fibers. Each of the PM optical fibers in the fiber optic bundle may have one or more of a different wavelength, a different coherence length, and a different polarization orientation to reduce crosstalk in the disk. Furthermore, the fiber optic bundle array is rotated to produce interference spots indicative of micro-holograms according to the data track pitch of the holographic disk over which the fiber optic bundle is outputting the light waves.

Abstract: The present techniques provide methods and systems for recording micro-holograms on a holographic disk using a plurality of counter-propagating light beams in parallel. The parallel counter-propagating light beams overlap to form interference patterns on a data layer and over multiple data tracks in the holographic disk. Rotating the disk enables the parallel recording of micro-holograms over multiple data tracks, thus reducing recording time. Further, the illumination pattern may include illuminated spots and non-illuminated regions, such that each illumination spot may cover a relatively small fraction of the data layer plane, possibly controlling the depth spread of the recorded micro-hologram. In some embodiments, data in the parallel signal beams may be retrieved from a master holographic disk or may be modulated into the parallel signal beams.

Abstract: An optical information recording/reproducing apparatus and an optical information recording/reproducing method that record information using holography, wherein the optical information recording/reproducing apparatus includes a signal generation unit that generates two-dimensional data by a two-dimensional encoding method in which a lower-limit value of a number of continuous ON/OFF pixels in an array in one direction of pixels in a two-dimensional spatial light modulator is K(K?2, K: natural number); and a pickup that records the two-dimensional data, generated by the signal generation unit, on a hologram disc.

Abstract: A holographic data storing method includes the steps of: encoding original data to generate holographic data according to a codeword to symbol relation; and recording a hologram corresponding to the holographic data onto a holographic storage medium. In the codeword to symbol relation, a plurality of sample symbols corresponds to a plurality of codewords. Each of the sample symbols corresponds to a pattern having N*N pixels. There are M bright pixels in the N*N pixels, wherein N and M are positive integers and M is smaller than N*N. A hamming distance of the sample symbols is greater than or equal to 4, and a two-dimensional run-length of the sample symbols is greater than or equal to 2.

Abstract: The present techniques provide methods and systems for controlling the recording of micro-holograms using multiple counter-propagating light beams over multiple data tracks of a holographic disk. Imperfections in a holographic disk or movement of the disk during a recording process may cause signal beams to deviate from target data tracks. In some embodiments, a tracking beam is directed to a reference layer in the disk. Deviation of the reference beam from a target groove in the reference layer may be indicative of tracking errors. A detector may detect reflections of the tracking beam and generate an error signal in response to detected tracking errors. Servo-mechanical devices may actuate (e.g., radially, tangentially, or axially translate, rotate, and/or tilt) one or more optical components through which the counter-propagating light beams are emitted to compensate for tracking errors.

Abstract: A method and apparatus for recording and/or reproducing holographic data and a holographic information storage medium, wherein the apparatus for recording and/or reproducing holographic information includes an optical pickup emitting light onto a holographic information storage medium and receiving the emitted light. The optical pickup includes: a light source unit emitting a signal beam and a reference beam in a recording mode; and a focusing optical system focusing the signal beam and the reference beam on one focal point in the holographic information storage medium so that information can be recorded by using an interference pattern formed along a depth direction of the holographic information storage medium in the vicinity of the focal point, wherein the numerical aperture of the focusing optical system for the signal beam is different from the numerical aperture of the focusing optical system for the reference beam.

Abstract: A card connector which can interchangeably couple a holographic memory card or an electronic memory card to a card reader and/or writer which can then read and/or write to the coupled holographic memory card or electronic memory card. The card connector comprises: a memory card receiving section which can interchangeably receive the holographic memory card or the electronic memory card; and one or more card positioning members which cooperate with one or more card locating members on the coupled holographic memory card or the coupled electronic memory card to thereby repeatedly position the coupled holographic memory card or the coupled electronic memory card each time the holographic memory card or the electronic memory card is coupled to the card reader and/or writer, and is in a fully inserted card position, so that data can be read from and/or written to the coupled holographic memory card or the coupled electronic memory card.

Abstract: An optical information recording/reproducing apparatus includes an optical source unit that emits an optical beam toward an optical information recording medium mounted on the apparatus, an optical receiving unit that receives a reflected beam of the optical beam reflected from the optical information recording medium or a transmitted beam of the optical beam transmitted through the optical information recording medium to output an output signal in response to the reflected beam or transmitted beam, and a distinction unit that discriminates whether the optical information recording medium is a hologram disk for recording information by using a holography or a reflection-type optical disk for reproducing information by virtue of the reflected beam, in accordance with the output signal output.

Abstract: A plate body 2, multiple hologram layers 3 are provided in the thickness direction of the plate body 2, and at least one of the multiple hologram layers 3 is formed of spirally continuous hologram bands 4. Erasure areas 4A and 4B and non-erasure areas 4C and 4D of the hologram band 4 are provided in the length direction of the hologram band 4. Non-erasure areas 4E and 4F of the hologram band 4 are formed on both sides in the direction orthogonal to the length direction of the hologram band 4 in the erasure areas 4A and 4B.

Abstract: A method for calculation of recording depth in a holographic disk is disclosed. The method includes applying a first external voltage to one or more actuators coupled to an objective lens to focus a tracking beam of radiation having a first wavelength on a reference layer of the disk, wherein the reference layer comprises at least one of a partially dichroic coating or a partially metallized coating. The method also includes applying a second external voltage to the one or more actuators coupled to the objective lens to focus a recording beam of radiation on the reference layer of the disk, wherein the recording beam comprises a second wavelength different from the first wavelength of the tracking beam. The method further includes computing a difference between the first external voltage and the second external voltage.

Abstract: A holographic data storage system that includes a write head that includes a pixellated spatial light modulator and a separate or integral phase mask that varies the phase depending on the location in the phase mask that light passes through. The phase variation can be changed over time in a random, pseudo-random, or predetermined fashion. The spatial light modulator and phase mask can be implemented in a liquid crystal SLM (nematic, ferroeleletric, or other), in a DMD SLM, in a magneto-optical SLM, or in any other suitable manner.

Abstract: In an information memory apparatus having minute areas for storing information arranged in x, y and z directions three-dimensionally, parallel rays are irradiated to a memory area MA in a direction perpendicular to a z-axis to take projection images of the memory area MA while rotating the memory area MA around the z-axis little by little. The light rays irradiated at this time have a size which covers at least a direction of an x-y plane of the memory area. A computation unit PU finds data and addresses of minute areas distributed three-dimensionally by performing computation based upon the principle of computer tomography on the projection images. As for data writing, a change is given to optical transmissivity or light emission characteristics by irradiating laser light focused by a lens OL placed outside the memory area to a desired minute area and causing heat denaturation within the pertinent minute area.

Abstract: A method is disclosed to optimize the performance of a holographic data storage system, where that holographic data storage system comprises a plurality of calibratable components, and where each of the plurality of calibratable components comprises one or operational parameters, and where each of those operational parameter is associated with a nominal range. The method seriatim tests each calibratable component and measures the one or more operational parameters for that device. The method determines if the one or more operational parameters associated with each of the calibratable components fall within the associated nominal ranges. If an operational parameter associated with a selected calibratable component fall outside the associated nominal range, then the method recalibrates that selected calibratable component.

Abstract: In accordance with an embodiment, a circuit includes a photodetector (PD) array including a plurality of electrically isolated PD sections. Additionally, the circuit includes a switching matrix that includes a plurality of inputs and a plurality of outputs, and that can be selectively configured in a plurality of different switch configurations. Each of the electrically isolated PD sections is adapted to detect light (if any) and provide an electrical output signal, indicative of the light detected by the PD section (if any), to a different one of the inputs of the switching matrix. The switching matrix is adapted to combine the electrical output signals provided by the electrically isolated PD sections in a plurality of different manners, in dependence on which of the plurality of different switch configurations is selected.

Abstract: A hologram recording/reproducing device includes an optical section which irradiates a holographic recording medium with an optical beam; and a control unit which controls the optical section. The optical section includes a laser light source which emits the optical beam, and a spatial modulator which modulates the optical beam. By controlling the spatial modulator, the control unit displays a tilt-standard reference light pixel and a tilt-standard signal light pixel, and records a tilt-standard hologram.

Abstract: A method and apparatus for stably encoding/decoding data, and a method and apparatus for recording/reproducing data are disclosed. The method inserts decoding information into a data section including several predetermined-bit data, determines encoding values of the data according to a transition state of the data and a value of corresponding data, and generates the decoding information and the determined encoding values in units of the data section.

Abstract: Disclosed herein is a recording medium on or from which the recording or reproduction of data is stably performed. On the recording medium, data are recorded three-dimensionally by the irradiation of a recording laser beam. The recording medium includes a reflection control layer including a plurality of reflection layers stacked in a film thickness direction, each reflection layer having a connection terminal, each reflection layer exhibiting reflectivity and transmissivity changeable in response to an electrical signal supplied to the connection terminal and a recording layer disposed at a beam incidence side of the reflection control layer.

Abstract: A holographic memory device is described which records and reproduces binary image data by irradiating a holographic recording medium with signal light and reference light. The holographic memory device includes a system for aligning polarization of the signal light and reference light on the holographic recording medium by guiding the signal light and the reference light to be coaxially opposed. The holographic memory device further includes a random-phase modulation multiplex recorder and spatial-shift multiplex recorder that, together with the system for aligning polarization, significantly enhances recording density and improves recording capacity.

Abstract: A method for holographic data recording and simultaneous data readout without requiring additional optical power for readout illumination is provided. The method comprises reflecting a transmitted portion of a data light beam or of a reference light beam used for holographic recording of data in a holographic data storage medium. The reflected beam is configured to illuminate the holographic data storage medium from the opposite side with a polarization orthogonal to that of the recording beams, such that it provides a counter-propagating readout beam for real-time readout of currently being recorded hologram. Readout beam may also be configurable for accessing any one of the at least one previously recorded holograms. Systems using the methods of the invention are also provided.

Abstract: A holographic storage system for reading a hologram stored on a holographic storage medium. The system comprises: storage medium holding means; a spatial light modulator (SLM) for encoding a reference beam with a code pattern; a detector; and a servo control unit for determining a misalignment of the reference beam and the storage medium from the detected image and for acting upon the SLM to shift the code pattern. A method of reading a hologram stored on a holographic storage medium comprising: a) encoding a reference beam with a code pattern created by a spatial light modulator (SLM); b) detecting an image of the reconstructed hologram; c) determining a misalignment of the reference beam and the storage medium from the detected image; and d) shifting the code pattern on the SLM based at least in part on the misalignment.

Abstract: An apparatus and method to record data on a holographic storage medium, the apparatus including: a light processing unit to record the data on the holographic storage medium using a reference beam and a signal beam, the light processing unit including a light modulator to modulate the signal beam; and a control unit to control the light processing unit to record the data on the holographic storage medium, wherein the light modulator modulates the signal beam so that an image formed on a surface of the light modulator is shorter in a radial direction that is a scanning direction of the reference beam than in a tangential direction that is perpendicular to the radial direction.

Abstract: A hologram device includes: a light source for applying light to a hologram recording medium having a recording layer in which information recording is performed by interference fringes between signal light and reference light; a spatial modulation unit that generates the signal light and/or the reference light and generates a marker light in a predetermined position within an incident surface of the light from the light source by performing spatial light modulation on the light from the light source; a light applying unit that applies the light subjected to spatial light modulation by the spatial light modulation unit to the hologram recording medium via an objective lens; a light receiving unit that receives the light applied via the objective lens through the hologram recording medium; and a tilt detection unit that obtains a tilt error signal representing an error from an ideal angle of a tilt angle as an incident angle of the applied light via the objective lens to an information recording surface of the

Abstract: A holographic storage medium is proposed, and more specifically a holographic storage medium with an integrated phase mask layer. The holographic storage medium has a phase mask layer on top of a holographic storage layer, wherein the phase mask layer has one or more phase pattern areas for coupling-in a reference beam and imprinting a phase pattern on the reference beam, and one or more neutral areas for coupling-in an object beam and/or coupling-out a reconstructed object beam.

Abstract: In the specification and drawings, a collinear holographic storage method is described and shown with a controlling step to control the temperature of the collinear holographic storage media such that the writing temperature of the collinear holographic storage media is from between about 5° C. to about 50° C. higher than the reading temperature of the collinear holographic storage media.

Abstract: A holographic memory apparatus comprises first phase modulation means that adds phase information to each pixel of a signal beam to generate page data at recording time; oscillator light generation means that generates an oscillator light that is superimposed on, and interferes with, a diffracted light from a holographic recording medium at reproduction time; second phase modulation means that adds phase information to the oscillator light; and light detection means that detects an interference light generated by superimposing the oscillator light and the diffracted light from the holographic recording medium.

Abstract: A method for processing information is provided. The method includes directing a laser beam to a first track of a first layer of a holographic storage medium. The method also includes recording a base voltage based on a look-up table. The method includes directing the laser beam to a target track in the first layer, based on position information in tracks. Further, the method includes recording an offset voltage for the target track into the look-up table. Still further, the method includes directing the laser beam to a target layer based on position information in vertical wobbles. The method also includes recording an offset voltage for the target layer into the look-up table. Finally, the method includes determining a final voltage based on the look-up table and applying the final voltage to an actuator for moving the laser beam to a final target position in the holographic storage medium for recording and retrieval of information.

Abstract: A spatial light modulator (SLM) having a phase mask that is provided as an internal component thereof. The phase mask can be provided as a multilevel surface of relatively higher index of refraction material on an inner surface of a transmissive cover window or as a separate transmissive window between the cover window and the pixels of the SLM. If the phase mask is to be used with a liquid crystal SLM, then it may be desirable to planarize the surface of the cover window contacting the liquid crystal by providing a layer of relatively lower index of refraction material adjacent the multilevel surface. The phase mask can also be provided on the transmissive cover window by patterned ion deposition, exposing patterned light to a photopolymeric material, or in some other suitable fashion. Arranging for the pixel electrodes to be at one of multiple levels rather than lying in an exactly planar relationship can also effectively create the phase mask.

Abstract: A reproducing device for performing reproduction regarding a hologram recording medium where a hologram page is recorded in accordance with signal light, by interference between the signal light where bit data is arrayed with the information of light intensity difference in pixel increments, and reference light, includes: a reference light generating unit to generate reference light irradiated when obtaining a reproduced image; a coherent light generating unit to generate coherent light of which the intensity is greater than the absolute value of the minimum amplitude of the reproduced image, with the same phase as the reference phase within the reproduced image; an image sensor to receive an input image in pixel increments; and an optical system to guide the reference light to the hologram recording medium, and also guide the obtained reproduced image according to the irradiation of the reference light, and the coherent light to the image sensor.

Abstract: A reading device includes a spatial light modulator, a zoom lens set, an object lens, an image sensor, and an adjusting module. The spatial light modulator provides a reading beam. The zoom lens set forms the reading beam into a real image. The object lens focuses the real image onto a collinear holographic storage medium and thus produces a diffraction signal. The image sensor converts the diffraction signal into an electric signal. The adjusting module adjusts the optical magnification of the zoom lens set according to the quality of the diffraction signal.

Abstract: An optical information recording/reproducing apparatus equipped with a mechanism for moving an optical pickup to an arbitrary radial position of an optical information recording medium using holography. A total sum signal of signals is generated at the photodetector for receiving signals reproduced from the optical information recording medium, and a radial position of the pickup is obtained from the number of pulses in the total sum signal to thereby allow the pickup to move to an arbitrary radial position.

Abstract: Provided is a light-spot-position control apparatus including: a first-light-source; a second-light-source; a beam-splitter splitting a beam of the second-light-source into m beams; an optical-system allowing a first-beam of the first-light-source and the m beams to irradiate a disk-shaped recording-medium, where grooves and lands are alternately formed with an equal radial width to form the grooves in spiral/concentric shape through common-objective-lens, the optical-system allowing the three beams to irradiate the recording-medium so that an interval of m beam-spots is 1/m of track pitch; a tracking-control-mechanism tracking-controlling the beam by changing a relationship between the optical-axis and the recording-medium; a light-receiving unit individually receiving the m beams; an error-signal generator generating error-signals representing radial-position-errors of the spot-positions of the m beams with respect to the tracks based on received signals; an error-signal selector selecting at least one erro

Abstract: The present invention provides systems of recording holograms that reduce the writing time, increase the diffraction efficiency, improve the resolution, or restitute color. These systems are well suited for use with an updateable 3D holographic display using integral holography and photorefractive polymer.

Abstract: According to an aspect of the present invention, a data recording method in a holography optical memory system, for recording a two-dimensional pixel data page in a recording medium can be provided. In accordance with an embodiment of the present invention, the data recording method in a holography optical memory system can include recording sequentially the signal beams carrying one-dimensional pixel data lines, included in the original two dimensional pixel data page, in the recording medium by using the same reference beam. Here, the pixel data page can be recorded such that any two adjacent pixel data lines are partially overlapped with each other in an area of the recording medium.

Abstract: The present techniques provide systems and methods for modulation coding of data on optical disks, such as holographic data disks, and techniques for reading that data back from the disks. The techniques involve parsing a bit stream into a sequence of individual bit-patterns, and then using the individual bit patterns to select a symbol, or matrix, from a lookup table of previously selected matrices. The symbols are selected according to predetermined criteria that may help make the disk more resistant to interferences and errors, such as surface scratches, and the like. For example, criteria that may be used to select the symbols are the number of reflective and non-reflective regions within each matrix, and the number of sequential reflective regions, among others. The symbols may be written to the disk in a two-dimensional fashion, e.g., across adjacent tracks, or in a three-dimensional fashion, e.g., across adjacent data layers.

Abstract: The recording and reproducing apparatus has rotary drive unit (a motor) that rotationally drives a multilayer recordable recording medium 1; a reference-light-side recording and reproducing lens 6 and a recording-light-side recording and reproducing lens 7 that are disposed oppositely to the recording medium 1 which is rotationally driven by the rotary drive unit, an address detection lens 5 that is disposed opposite the recording medium 1 and that is provided separately from the recording and reproducing lenses 6 and 7; a light source 9 for recording and reproducing purpose that supplies recording reproduction light to the recording and reproducing lenses 6 and 7; and the address light source 9 that supplies address light to the address detection lens 5. The apparatus is configured in such a way that light whose center axis portion is optically hollow is supplied from the reference-light-side recording and reproducing lens 6 to the recording medium 1 during reproducing operation.

Abstract: An apparatus for reading from a multilayer holographic storage medium with a coaxial arrangement of a reference beam and a reconstructed object beam is described. The apparatus has an objective lens for focusing the reference beam into the multilayer holographic storage medium such that the reference beam has a focal point behind or in front of a reflective layer of the multilayer holographic storage medium, wherein a distance between the objective lens and the multilayer holographic storage medium is set in accordance with an addressed layer of the multilayer holographic storage medium, and an imaging system with a fixed lens of focal length f and a movable lens of focal length f for re-collimating a reconstructed object beam, wherein for a specific position of the movable lens the imaging system assumes a 4f configuration.

Abstract: A servo controlling apparatus of a holographic information recording/reproducing system changes the foci of reference light and signal light in a depth direction of a holographic information storage medium to record information over a plurality of information layers. A servo control is changed from a normal servo operation to a between-movement servo operation while movement between information layers is made during a recording operation, and the servo control is changed back to the normal servo operation when the movement between information layers is completed. The between-movement servo operation maintains a servo control state that exists before the movement between information layers.

Abstract: A data storage device including: a plastic substrate having a plurality of data volumes arranged along tracks in a plurality of stacked layers; a plurality of micro-holograms each contained in a corresponding one of the data volumes; a plurality of complementary volumes, each corresponding to and being substantially aligned with one of the data volumes; a plurality of micro-holograms each contained in a corresponding one of the complementary volumes; wherein, the presence or absence of a micro-hologram in each of the data volumes is indicative of a corresponding portion of data stored; and, the ones of the complementary volumes corresponding to the ones of the data volumes containing a micro-hologram do not contain a micro-hologram; and the ones of the complementary volumes corresponding to the ones of the data volumes not containing a micro-hologram contain a micro-hologram.

Abstract: In holographic recording by the angle multiplexing method, in order to allow a signal beam and a reference beam to sufficiently overlap with each other in a storage medium to decrease as much as possible a wastefully exposed region, which does not contribute to a signal recording, an optical pickup apparatus having a function which can control, for example, a size or a position of an aperture of the reference beam is used. An optical information reproducing apparatus or an optical information recording and reproducing apparatus using the optical pickup apparatus is used.

Abstract: A hologram disc reading and writing apparatus including a signal light source module, a beam splitter, a reference/reading light source, a reflector, and an optical reading head and a hologram disc reading apparatus are provided. A signal light beam emitted from the signal light source module is transmitted to a data region of a hologram disc through the beam splitter. The reference/reading light source, the signal light source module, and the optical reading head are disposed at the same side of the hologram disc. The reflector is disposed at the other side. A spherical wave light beam emitted from the reference/reading light source is transmitted through the data region and reflected by the reflector to form a phase conjugate light beam transmitted to and through the data region. The phase conjugate light beam is transformed to a data light beam transmitted to the optical reading head through the beam splitter.