Abstract: A singlet imaging system for imaging an object onto a detector includes a lens configured for producing transverse ray intercept curves which are substantially straight, sloped lines. A wavefront coding element is formed on a surface of the lens and configured such that a modulation transfer function of the lens and wavefront coding element, combined, exhibits reduced variation, over a range of spatial frequencies and caused, at least in part, by aberrations of the lens, as compared to a modulation transfer function of the lens alone, without the wavefront coding element. A post processor is configured for generating an improved modulation transfer function, over the range of spatial frequencies, as compared to the modulation transfer function of the lens and the wavefront coding element.

Abstract: Methods and systems are provided for obtaining a phase conjugate reconstruction beam for use in retrieving holographic information from a holographic storage medium. These methods and systems include generating a coherent light beam that is a reproduction of the reference beam used in storing the holographic information in the storage medium. This coherent light beam is then directed through the holographic storage medium at the same angle and location of the reference beam during recording of the hologram. The directed coherent beam is then reflected back through the storage medium so that the reflected coherent light beam provides a phase conjugate of the reference beam and passes through the storage medium at the same angle and location that the reference beam passed through the storage medium during recordation of the hologram.

Abstract: A laser processing apparatus includes a laser source (11), a spatial phase modulator (13) configured to modulate a phase of a laser beam emitted from the laser source, a synthetic data generator (17) configured to generate synthetic data by combining hologram image data representing a pattern image to be processed with position displacement hologram data for shifting the pattern image to a prescribed position, the synthetic data being input to the spatial phase modulator for the phase modulation of the laser beams, and a focusing optical unit (14) configured to guide the phase-modulated laser beam onto a surface to be processed to reproduce the pattern image on the processed surface.

Abstract: A hologram recording method for recording information of signal light as holograms in an optical recording medium, which includes illuminating signal light at the optical recording medium; illuminating reference light at the optical recording medium simultaneously with the signal light such that an interference pattern is formed by the signal light and the reference light intersecting in the optical recording medium; and shifting a region in the optical recording medium at which the signal light and the reference light intersect, by shifting an illumination position of the reference light along an optical axis of the signal light, thereby recording a plurality of holograms in the recording medium.

Abstract: Embodiments of the invention provide a system and method for providing a three-dimensional moving image from a non-fixed pixel display. In one embodiment, a display having a plurality of pixels is provided, wherein at least one of the pixels is non-fixed and dynamically adjustable. In addition, a pixel controller is provided for controlling at least one non-fixed and dynamically adjustable pixel. The pixel controller for moving at least one of the pixels to a first extent to changing the phase of a first photon and to a second different extent to change the phase of a second photon.

Abstract: A monocular holographic storage device or system to provide for compact recording and/or reading of data pages in a holographic storage medium. Also provided are methods for carrying out such data storage and/or data recovery using a monocular holographic storage device or system. Further provided are articles comprising holographic storage media for recording or for reading recorded data using such devices or systems.

Abstract: A hologram reading apparatus includes: a unit holding a hologram recording medium in which data page is recorded by irradiating as a single beam both reference light and signal light modulated by a spatial light modulator including a first pixel area for modulating the reference light and a second pixel area for modulating the signal light, a pitch of pixels in the first pixel area being different from that in the second pixel area; a Fourier transform lens subjecting reproduction light to a Fourier transformation; a filter disposed on a Fourier transform plane of the reproduction light by the Fourier transform lens, the filter shielding the reference light at a first spatial frequency band and transmitting the signal light at a second spatial frequency band; and a reading unit receiving the reproduction light transmitted through the filter and reading the data page modulated to the signal light included in the reproduction light.

Abstract: A complex amplitude type spatial optical modulation element, with which the amount of generation of 0th order diffraction light is low. An optical element is arranged by aligning a plurality of three dimensional cells C1(x, y) two dimensionally on an XY plane. Each individual cell is made of a light transmitting material and has a specific amplitude and a specific phase defined therein. The individual cell has a specific optical characteristic such that when predetermined incident light is provided from the upper surface or a lower surface of the cell, transmission emitted light, with which amplitude and phase of the incident light have been changed in accordance with the specific amplitude and the specific phase defined in the cell, is obtained from the lower surface or the upper surface of the cell.

Abstract: A complex amplitude type spatial optical modulation element, with which the amount of generation of 0 th-order diffraction light is low, is provided. An optical element is arranged by aligning a plurality of three-dimensional cells C1(x, y) two-dimensionally on an XY plane. Each individual cell is made of a light transmitting material and has a specific amplitude and a specific phase defined therein. The individual cell has a specific optical characteristic such that when predetermined incident light is provided from the upper surface of the cell, reflection emitted light, with which amplitude and phase of the incident light have been changed in accordance with the specific amplitude and the specific phase defined in the cell, is obtained from the upper surface of the cell.

Abstract: Disclosed is a holographic data storage device including holographic media for containing data, writing data to and reading data from. The storage device also includes at least one supplemental memory for containing at least a portion of a directory of the data contained in the holographic media. By locating directory information for the holographic media in a supplemental memory, areas of the holographic media that have not yet been written to can be determined prior to accessing the holographic media. In this way, activating photo-sensitive agents in unwritten areas of the holographic media can be avoided unless these areas are being written to.

Abstract: A complex amplitude type spatial optical modulation element, with which the amount of generation of 0th-order diffraction light is low. An optical element is arranged by aligning a plurality of three dimensional cells C1(x, y) two dimensionally on an XY plane. Each individual cell is made of a light transmitting material and has a specific amplitude and a specific phase defined therein. The individual cell has a specific optical characteristic such that when predetermined incident light is provided from the upper surface of the cell, reflection emitted light, with which amplitude and phase of the incident light have been changed in accordance with the specific amplitude and the specific phase defined in the cell, is obtained from the upper surface of the cell.

Abstract: A complex amplitude type spatial optical modulation element, with which the amount of generation of 0th-order diffraction light is low. An optical element is arranged by aligning a plurality of three-dimensional cells C1(x, y) two-dimensionally on an XY plane. Each individual cell is made of a light transmitting material and has a specific amplitude and a specific phase defined therein. The individual cell has a specific optical characteristic such that when predetermined incident light is provided from the upper surface of the cell, reflection emitted light, with which amplitude and phase of the incident light have been changed in accordance with the specific amplitude and the specific phase defined in the cell, is obtained from the upper surface of the cell.

Abstract: A system and a method for holographic storage mainly involve forming a holographic interference pattern in a holographic recording medium. The holographic storage system utilizes a light source to emit a coherent beam. The coherent beam is irradiated to a first reflector to form a divergent beam. The divergent beam is then irradiated to a second reflector to form collimating beams (a signal beam and a reference beam). The signal beam goes through a spatial light modulator (SLM) and is modulated by the SLM. After that, the reference beam and the modulated signal beam are irradiated to a convergent unit, and are directed to the holographic recording medium for forming the holographic interference pattern. The holographic storage system that the light source is split into a signal beam and a reference beam by a set of reflectors according to the reflection principle without involving refraction may employ wavelength multiplexing.

Abstract: A complex amplitude type spatial optical modulation element, with which the amount of generation of 0th-order diffraction light is low. An optical element is arranged by aligning a plurality of three dimensional cells C1(x, y) two dimensionally on an XY plane. Each individual cell is made of a light transmitting material and has a specific amplitude and a specific phase defined therein. The individual cell has a specific optical characteristic such that when predetermined incident light is provided from the upper surface of the cell, reflection emitted light, with which amplitude and phase of the incident light have been changed in accordance with the specific amplitude and the specific phase defined in the cell, is obtained from the upper surface of the cell.

Abstract: Beams of light emitted from a light source are incident on a polarizer. The direction of a transmission axis of the polarizer can be adjusted in advance such that the polarizer transmits P polarized light, and S polarized light is attenuated. Beams of light transmitted through a diffracting device and a collimator lens for incidence on a beam splitter are made up substantially only by P polarized light. Part of the beams of light, which is reflected on the beam splitter, is incident on a photodetector for feedback control of outputs from the light source. Since S polarized light is attenuated by the polarizer, only P polarized light is incident on the photodetector. Consequently, if the quantity of emitted laser beams changes, a ratio between the quantity of light for record and reproduction and the quantity of light for APC remains substantially constant, thereby increasing accuracy of detecting the intensity of laser beams, to avoid errors in record and reproduction.

Abstract: A voltage control circuit which can prevent the occurrence of imprint phenomenon is provided. In a voltage control circuit which applies voltage to a pair of electrodes including a first and a second electrode, a control unit switches the voltage applied to the pair of electrodes, in response to an operation mode of this circuit. In a normal mode, the control unit fixedly applies a first voltage to the first electrode and applies a data voltage of the first voltage or the second voltage to the second electrode, based on an instruction from the control unit. In an inversion mode, the second voltage is fixedly applied to the first electrode, and the data voltage of the first voltage or second voltage is applied to the second electrode. The control unit switches the mode between the normal mode and the inversion mode, in a predetermined cycle.

Abstract: The number M of a plurality of multiplexed recording mediums to be recorded in a projected area S on the surface of a recording medium satisfies the equation (1?) where n represents the refractive index of the recording medium, ? the wavelength in vacuum of light used to record and reproduce information, L the thickness of the recording medium, ±NAR the range of an angular spectrum in air of a reference beam, ±NAS the range of an angular spectrum in air of a reproduced beam applied to a light detector, S the projected area of a recording region to be recorded in one recording cycle onto the surface of the recording medium, N the number of bits to be recorded in one recording cycle, and Z the signal vs. signal noise ratio as a target ratio (Z=3).

Abstract: A holographic recording/reproducing apparatus that easily controls an incident angle of a reference beam and that is less sensitive to a tilt of a holographic recording medium, the holographic recording/reproducing apparatus including: a light source to emit a light; and an optical system to divide the emitted light into a reference beam and a signal beam, and to provide the reference beam and the signal beam to the holographic recording medium, wherein the optical system provides the signal beam to be incident on an upper surface of the holographic recording medium, and provides the reference beam to be guided along the inside of the holographic recording medium by reflection due to a refraction index difference between the holographic recording medium and the outside of the holographic recording medium.

Abstract: Provided are a method and system for determining states of spatial light modulator (SLM) pixels in a lithography system configured to print a desired pattern. The method includes determining diffraction orders associated with an ideal mask of a pattern to be printed by the lithography system, and then configuring the states of the SLM pixels to match all the diffraction orders that are relevant in the image formation.

Abstract: The present invention relates to an apparatus for reading from and/or writing to holographic storage media with a simplified common aperture setup. According to the invention an apparatus for reading a data page from and/or writing a data page to a holographic storage medium, with a coaxial arrangement of one or more reference beams and an object beam or a reconstructed object beam, has one or more spatial light modulators for generating the one or more reference beams by modulating a light beam with a modulation pattern having a spatial frequency higher than the spatial frequency of the data page.

Abstract: A holographic storage and regeneration system includes a holographic recording medium, a light source, a spatial light modulator, and a conjugate servo light guidance portion. The light source generates a signal light and a reference light. The spatial light modulator modulates the incident signal light and makes it incident onto the medium along the incident direction of the signal light. The guidance portion guides a reference light to incident onto the medium in one direction and reflects it in another direction. A reference light and a signal light interfere with each other to produce a holographic interference fringe. The reflected reference light is guided into a first image sensor to be used to analyze the incident angle of the reference light. When the reference light incidents onto the fringe of the medium through the guidance portion in a reverse direction relative to another direction, a conjugate regenerated light is generated.

Abstract: There is provided a hologram recording and reproducing apparatus for a hologram recording medium that stores optical interference fringes therein as a diffraction grating generated by coherent reference light and signal light. The hologram recording and reproducing apparatus includes a control circuit that is connected to a spatial light modulator and controls each pixel in such a way that the reference light is modulated according to information data to produce the signal light. The control circuit spatially classifies a plurality of pixels in the spatial light modulator into a central modulation area disposed on the optical axis and at least one annular modulation area sequentially disposed around the central modulation area in a concentric manner, and controls the pixels in the central modulation area and the pixels in the annular modulation area using respective different recording modulation methods to deliver the signal light through the central modulation area and the annular modulation area.

Abstract: A hologram reproducing apparatus is provided that can be reduced in size. A hologram reproducing apparatus of the invention reproduces signal information from a recorded media having a domain of diffraction grating that is irradiated with a record light beam containing a coherent reference light component and a signal light component spatially modulated according to the signal information substantially on the same optical axis and is recorded an interference of the reference light component and the signal light component.

Abstract: A hologram recorder is provided, in which coherent light from a light source is split into a signal beam and a reference beam, and the signal beam is modulated by a spatial light modulator to be directed to a hologram recording medium, while the reference beam is directed to the hologram recording medium to overlap with the signal beam for recording a hologram on the hologram recording medium. The hologram recorder includes a beam phase modulator provided with a plurality of optical devices (20p, 20p?) each configured to assume one of two modes such as ON mode and OFF mode, the ON mode for causing the reference beam to be passed or reflected in a predetermined direction toward the hologram recording medium, the OFF mode for causing the reference beam to be blocked or directed in another direction other than the predetermined direction. Each optical device (20p, 20p?) provides a phase difference 0 or ?.

Abstract: A device that provides light beam switching, agile steering of the light beam over a range of angles, and generation of arbitrary wavefront shapes with high spatial and temporal resolution. The agile device can include a volume diffractive structure comprising Bragg planes having one refractive index and the Bragg planes separated by regions containing an active optical medium. Electrodes (which may be the Bragg planes themselves, or may be arrayed adjacent to the active optical medium) are used to control the electric field intensity and direction across the structure, and thereby control the diffraction efficiency of the structure and the local phase delay imposed on a diffracted wavefront. Means are provided for addressing the many thousands of electrodes required for precise and rapid wavefront control. Applications include free-space atmospheric optical communications, near-eye displays, direct-view 3D displays, optical switching, and a host of other applications.

Abstract: A hologram recording/reproducing apparatus includes: a coherent light source; a spatial light modulator which spatially modulates light from the coherent light source; a Fourier transform lens which concentrates light modulated by the spatial light modulator upon a hologram medium; and a two-dimensional light-receiving element array which receives light from the hologram medium. The spatial light modulator is divided into a reference light area and a signal light area, and the divergence angle of reference light emitted from the reference light area is wider than the divergence angle of signal light emitted from the signal light area.

Abstract: Split machine learning systems can be used to generate an output for an input. When the input is received, a determination is made as to whether the input is within a first, second, or third range of values. If the input is within the first range, the output is generated using a first machine learning system. If the input is within the second range, the output is generated using a second machine learning system. If the input is within the third range, the output is generated using the first and second machine learning systems.

Abstract: An optical information recording device, a reproduction device, and a method enabling include a first spatial light modulator I for generating information light by spatially modulating light from a light source 143 by a plurality of pixels and a second spatial light modulator R for generating reference light by spatially modulating light from a light source by a plurality of pixels. The area I of the information light and the area R of the reference light on the entrance pupil surface of an objective lens 111 are formed such that one area surrounds the other area. The reference light is spatially modulated by the second spatial light modulator R such that interference is not easily generated between the reference lights in the information recording layer 3.

Abstract: An apparatus for writing and reading holograms, comprising a spatial light modulator (SLM) operable in phase mode, having a plurality of pixels for generating an object beam that overlaps with a reference beam; a holographic recording medium (HRM) in the path of the object beam; and a first lens element disposed in the path of the object beam between the SLM and the HRM; wherein the HRM is disposed at or near the Fourier transform plane of the first lens element.

Abstract: A hologram recording apparatus where holograms corresponding to incident angles of reference light are multiple-recorded onto a medium, including a recording light projection unit projecting the recording light onto a region of the medium; a reference light projection unit projecting the reference light onto the medium by intermittently changing an incident angle; an incident-angle variation projection unit changing the incident angle of the reference light; an incident-angle switching instruction unit giving an instruction for switching the incident angle; a feed-back control unit operating the incident-angle variation projection unit by feed-back control when the switching instruction of the incident angle has been given; and a feed-forward compensation unit learning a feed-back control signal which is outputted every switching instruction of the incident angle from the feed-back control unit, wherein a feed-forward compensation is made as to a next feed-back control signal on the basis of a result of the l

Abstract: There are provided a holographic recording method, a holographic recorder, a holographic recording/reproducing method, a holographic recorder/reproducer and a holographic recording medium as follows. Information is angle-multiplex-recorded as a hologram by a first format in which one of a signal light and a reference light branched from a laser light source intersects the other at a specified incident angle in a recording layer and the incident angle is altered at a specified angular pitch or a second format having a higher angle selectivity. When information is recorded in the second format having a higher angle selectivity, the incident angle can be adjusted to include such an incident angle that satisfies Bragg's conditions at the time of recording in the first format and compatibility of reproduction can be ensured between media having different angle selectivity.

Abstract: In a reproducing apparatus adapted to reproduce data recorded on a holographic recording medium, a reference light generator generates reference light for illuminating the holographic recording medium, and a coherent light generator generates coherent light having an intensity greater than the absolute value of a minimum amplitude of a reproduced image and having a phase equal to the phase of the reproduced image. An image signal acquisition unit senses the reproduced image produced by illuminating the holographic recording medium with the reference light and the coherent light, and acquires an image signal based on the reproduced image. A square root calculation unit calculates the square root of each of values constituting the image signal. A removal unit removes the component of the coherent light from the calculated square root, whereby the data recorded on the holographic recording medium is correctly reproduced.

Abstract: This invention relates to improved holograms, in particular suitable for security applications, and to methods and apparatus for their fabrication. A hologram storing a pair of images, the hologram comprising: a first stored image configured to replay at a first wavelength; and a second stored image configured to replay at a second wavelength different to said first wavelength; and wherein said first and second stored images are spatially complementary such that when replayed they appear together, substantially in register, and give the appearance of a single, substantially uninterrupted image.

Abstract: A holographic recording system with a simple structure is provided that can make a holographic recording beam follow a recording medium traveling even at high speed. The holographic recording system 10 includes a chopper lens 30 that travels in synchronization with and in a same direction as the holographic recording medium 14. The chopper lens 30 is formed so as to move the axes of incident information and reference beams relative to the recording medium and the chopper lens, and to irradiate them to an identical information recording region 15 in the holographic recording medium 14.

Abstract: A monocular holographic storage device or system to provide for compact recording and/or reading of data pages in a holographic storage medium. Also provided are methods for carrying out such data storage and/or data recovery using a monocular holographic storage device or system. Further provided are articles comprising holographic storage media for recording or for reading recorded data using such devices or systems.

Abstract: An inline type speckle multiplexed hologram recording apparatus and method is disclosed which can condense signal light and reference light in a sufficiently overlapping relationship with each other on a hologram recording medium without using a lens having a large aperture and a wide angle of view. A signal light region and a reference light region are displayed on a spatial light modulator, and laser light is intensity modulated with recording data displayed in the signal light region to produce signal light while the laser light having passed through the reference light region is used as reference light. The signal light and the reference light are diffused by a diffuser and then condensed in an overlapping relationship with each other on a hologram recording medium by a lens such that interference fringes produced thereby are recorded in the hologram recording medium.

Abstract: A hologram recording method includes generating a signal beam with data formed by superimposing pattern data, the pattern data representing a pattern in which a large number of plural kinds of pixels having different tone values are arranged in a two-dimensional manner, on an image data of respective pixels represented by tone values corresponding to density, and recording a hologram by irradiating a converted beam formed by Fourier transformation of the generated signal beam with a lens and a reference beam to an optical recording medium.

Abstract: There is provided a hologram recording method including: generating light of a pattern in which a plurality of unit blocks, which include at least one pixel and express luminance, are arrayed, the pattern being sectioned into a region of a signal beam and a region of a reference beam, and being generated such that the region of the reference beam includes a plurality of unit blocks whose numbers of pixels are different; collecting the generated light at a common optical system, and illuminating it onto an optical recording medium; and recording, as a hologram, data which the signal beam expresses.

Abstract: A spatial light modulator, in which light modulation elements are arranged in a same plane. In the spatial light modulator, a plurality of the light modulation elements are arranged such that there are at least two periods of periodic structure corresponding to an arrangement of the light modulation elements in an arbitrary direction in the plane where the light modulation elements are arranged.

Abstract: A spatial light modulator spatially modulates a laser beam to provide an object beam representing information to be recorded and having a predetermined frequency component, and spatially modulates a laser beam to provide a record reference beam having a frequency component equal to the predetermined frequency component. An objective lens simultaneously converges the object beam and the record reference beam on a record medium.

Abstract: An authentication system using a correlator that correlates an input with a reference wherein at least one of the input and reference comprises a phase volume mask having structures, preferably points, that are each less than about six microns in size and can have an aspect ratio (AR) greater than 1:1 so as to produce a phase encoded random pattern having millions of combinations in a mask that is as small as one square millimeter. The random pattern can be convolved with a second pattern, such as a biometric pattern, to produce a phase convolved mask. The correlator preferably is a nonlinear joint transform correlator that can use “chirp” encoding to permit the input to be located in a different plane than the reference. The correlator optically Fourier transforms images of the reference and input that are thereafter nonlinearly transformed and inverse Fourier transformed by a processor to determine the presence or absence of a correlation spike indicative of authenticity.

Abstract: The present invention relates to a holographic storage system, and more specifically to a holographic storage system using a phase spatial light modulator. According to the invention a holographic storage system with a phase SLM for imprinting a 2-dimensional phase data pattern onto an object beam includes a common path interferometer for converting the phase data pattern of the object beam into an intensity data pattern.

Abstract: An interference lithography system is described that is capable of exposing high resolution patterns in photosensitive media and employing yield increasing active stabilization techniques needed in production environments. The inventive device utilizes a division-of-wavefront interference lithography configuration which divides a single large field size optical beam using one or more mirrors, and is actively stabilized with a subsystem employing; a phase modulator operating on each divided wavefront section; a novel feedback apparatus for observing the relative phase shifts between interfering wavefront sections; and a control system for holding the relative phase shifts constant.

Abstract: An apodization system for achieving a substantially uniform intensity profile of a modulated reference beam on a holographic recording medium. The substantially uniform intensity profile serves to improve the quality of any and all recorded holograms. In high-density holographic storage, the apodization system reduces the required hologram extent while still, maintaining any fidelity constraints (power budget, imaging tolerances, error-rate, noise floor). Furthermore, in high-fidelity holographic storage, better control of the hologram recording parameters can be established. The improved control allows tighter specifications on the image quality to be achieved.

Abstract: Systems and methods for shearless digital hologram acquisition, including an apparatus incorporating an illumination source configured to produce a first beam of light, which is then split by a beamsplitter into a reference beam and an object illumination beam. The reference beam is directed onto a phase-shaping optical element which imparts a phase shift to the reference beam and returns the phase-shifted reference beam on itself to the beamsplitter. The object illumination beam is directed onto an object, and a portion of the beam is reflected back to the beamsplitter, which combines the phase-shifted reference beam and object illumination beam substantially coaxially. The combined beams are passed through a focusing lens which focuses them at a focal plane. A digital recorder is positioned at the focal plane to record the spatially heterodyne hologram formed by the focused phase-shifted reference beam and reflected object illumination beam.

Abstract: An optical information reproducing apparatus and an optical information reproducing method using the same are provided. The optical information reproducing apparatus includes: a light source; a beam splitter which splits a beam emitted from the light source into a reference beam and a temporary beam; a temporary beam splitter which splits the temporary beam into a pair of assistant beams; an incident optical system which inputs the reference beam and the assistant beams to a recording medium in which optical information is recorded; a reproduction beam detector which detects reproduction beams reproduced in response to the reference beam, sets the position of the reproduction beam having the largest light intensity as a reference position, and sets a signal region on the basis of the reference beam; and an assistant beam detector which compares the light intensity of the assistant beams incident on the signal region with each other and sets an incident angle of the reference beam.

Abstract: A radiation system for multiplexing radiation includes two radiation sub-sources. The sub-sources each provide a certain amount of radiation. The system further includes a member with reflecting surfaces. The surfaces are arranged in such a way that they receive the radiation from the sub-sources and combine this radiation. The radiation sub-sources may operate simultaneously or alternately. The surfaces may perform functions such as filtering or (de)magnifying.

Abstract: Methods and systems are described herein for calculating a wavelength to use for a reference beam in recovering data from a holographic storage medium along with calculating a rotation and a tilt for the storage medium in data recovery. These systems and method comprise determining intensity levels for a plurality of windows (or subsets of pixels) for a data page as the angle of the reference beam is adjusted. The angles corresponding to the angles where the maximum intensity of light is detected for each window is then used in determining the wavelength, tilt, and rotation in recovering subsequent data pages from the holographic storage medium.

Abstract: A method for storing holographic data in a medium having a reflection layer and a recording layer comprises: recording, rotating and repeating. An interference pattern is recorded at a recording position of the recording layer of the medium in a stationary state. The interference pattern is formed by an interference between an object beam and a reference beam which are irradiated into the recording layer from an opposite side of the reflection layer. The medium is rotated so as to shift the recording position by a distance of n×Sh where n is a positive integer and Sh is a predetermined recording shift amount. The recording and the rotating are repeated alternately.

Abstract: A complex amplitude spatial optical modulation element for low 0th-order diffraction light has a plurality of three-dimensional cells two-dimensionally on an XY plane. Each cell is light transmitting and defines a specific amplitude and phase. An upper surface of each cell has a first region in which a groove is formed and a second region at both sides of the first region with light blocking layers on upper surfaces. The groove has a bottom surface with an area set in accordance with the specific amplitude and a depth set in accordance with the specific phase of the corresponding cell.