Abstract: A method for determining a rotational speed of a rotatably mounted component of a machine is disclosed, wherein image data of a marked region of the machine component are obtained in the form of a plurality of frames via a video camera, and the image data are evaluated, in order to determine the periodicity of the rotation of the machine component from the change over time of the image data in the frames of the machine component. The video camera is configured by selecting an active region for obtaining the image data from the total number of pixels of the video camera, in which an observation area is imaged, which is passed through by the marked region during the rotation of the machine component, wherein the active region comprises only a portion of the total number of pixels of the video camera, to increase the frame rate correspondingly.

Abstract: A laser displacement meter includes: a laser array beam source unit including a plurality of lasers emitting beams with different wavelengths; a lens array unit including a plurality of lenses for focusing laser beams; a reflected beam lens array unit including a plurality of focusing lenses for focusing the beam reflected on the surface of the object; an optical filter array unit including a plurality of optical filters through which the reflected beam is selectively transmitted; and a photodetector array unit including a plurality of photodetectors for detecting the beam transmitted through the optical filters.

Abstract: An appliance for recording an image of an ocular fundus includes an irradiating device with a radiation source and optical components for generating an illumination strip. A scanning device is set up to cause a scanning movement of the illumination strip for the purpose of scanning the ocular fundus. An optoelectronic sensor senses detection light issuing from the ocular fundus. The optoelectronic sensor has a plurality of sensor rows and is set up such that charges contained in one sensor row are each shifted, with a time delay, into a further sensor row. A control means is connected to the scanning device and/or to the optoelectronic sensor and is set up to control the scanning movement and/or the time delay.

Abstract: An optical writing head includes a light emitting device array having a plurality of light emitting device that emit parallel rays of light, and an optical unit arranged between the light emitting device array and an image plane to form an image by the rays of light emitted from the light emitting devices on the image plane. The optical unit includes a two-dimensional grating.

Abstract: A print head system useful for xerographic printing includes an LED bar print head; a photoreceptor, the photoreceptor having a conductive surface; a sensor, the sensor being disposed on the LED bar, the LED bar being disposed a conjugate distance from the photoreceptor, wherein the sensor and the photoreceptor are configured to enable a measurement of the conjugate distance.

Abstract: According to aspects of the embodiments, there is provided methods of dynamically focusing an LED print bar or printhead using piezoelectric stacks. The stack is mounted on either end of the LED bar to adjust the focus of the bar against the photoreceptor surface. The piezo level could be either controlled through active feedback of some description such as optical or electrical, or as a service or manufacturing input. With electronic control, focus adjustments can be made by the machine, and dynamically, if needed. In one embodiment, a flextensional cell structure is employed to amplify the movement of the piezo stack to move the LED bar in the order of >50 microns closer or away from the photoreceptor surface.

Abstract: An optical information recording/reproducing apparatus, to apply holograms of an angle multiplex recording method therein includes: a light source to emit a light beam; a divider unit to divide the light beam into a signal beam and a reference light; an angle variable unit to change an angle of the reference light incident upon an optical information recording medium; a spatial light modulator unit to add information to the signal beam; an objective lens to irradiate the signal beam on the medium; an image pickup unit to detect a diffracted light generating from a recording region, when the reference light is irradiated on the medium; and an optical element to shape a form of light flux of the reference light, so that a light flux diameter of the reference light in a multiplex direction becomes larger than the light flux diameter of the reference light in a pitch direction.

Abstract: In an optical information recording device and optical information recording method for angularly multiplexing and recording data on pages on the same recording region on a hologram disk, data on each page is sequentially generated by sequentially dividing input data in predetermined units, the pages to be recorded on the same recording region are divided into page groups so that pages to be recorded adjacently by the angular multiplexing may not belong to the same group, each page group is individually subjected to inter-page coding processing for computing an error-correcting code and adding the computed error-correcting code, and data on the pages subjected to the inter-page coding processing is angularly multiplexed and recorded on the hologram disk.

Abstract: An optical information recording/reproducing apparatus, to apply holograms of an angle multiplex recording method therein includes: a light source to emit a light beam; a divider unit to divide the light beam into a signal beam and a reference light; an angle variable unit to change an angle of the reference light incident upon an optical information recording medium; a spatial light modulator unit to add information to the signal beam; an objective lens to irradiate the signal beam on the medium; an image pickup unit to detect a diffracted light generating from a recording region, when the reference light is irradiated on the medium; and an optical element to shape a form of light flux of the reference light, so that a light flux diameter of the reference light in a multiplex direction becomes larger than the light flux diameter of the reference light in a pitch direction.

Abstract: An optical information reproducing apparatus and an optical information reproducing method using the same are provided. The optical information reproducing apparatus includes: a reference beam providing unit which inputs a reference beam to a reproduction recording area to be reproduced and a peripheral recording area around the reproduction recording area on an optical information recording medium, a peripheral beam detecting unit which transmits a reproduction beam reproduced from the reproduction recording area in response to the reference beam and detects a peripheral beam reproduced from the peripheral recording area, a tracking servo unit which analyzes optical information of the detected peripheral beam and controls a tracking position, and a reproduction beam detecting unit which detects the reproduction beam having pass through the peripheral beam detecting unit.

Abstract: A signal conditioning unit processes a data signal from an optical pickup unit. The signal conditioning unit includes a single-ended channel and a dual-ended channel. One of the single-ended channel and the dual-ended channel is selected as an active channel, and a reference level of a signal in the active channel is calibrated. The signal in the active channel is adjusted within a dynamic range of a digital signal processing stage, and the data signal of the active channel is converted to a digital signal at the digital signal processing stage.

Abstract: There is provided an optical multiplexer including: a substrate having a plurality of beam transmitting portions; and diffraction gratings diffracting beams irradiated to the beam transmitting portions at different angles, each diffraction grating being formed in the corresponding beam transmitting portion. Accordingly, it is possible to reduce an alignment error and manufacturing cost and to reduce the entire size of a recording apparatus or a reproducing apparatus.

Abstract: In an apparatus for conditioning a signal from an optical pickup unit (OPU), a single-ended channel includes a first signal processing block to calibrate a dark level of a single-ended signal corresponding to a single-ended output of the OPU, if any, and to center the single-ended signal. A dual-ended channel includes a second signal processing block to calibrate a dark level of a dual-ended signal corresponding to a dual-ended output of the OPU, if any, and to center the dual-ended signal. A multiplexer selects one of the single-ended channel and the dual-ended channel, and outputs a selected signal. A digital signal processing stage converts the selected signal to a digital signal.

Abstract: A holographic memory system includes a spatial light modulator having multiple modulators for spatially modulating at least a portion of a light beam emitted from a light source and rendering it as an information light beam, and a light sensing device for reading the information light beam taken out of a recording medium. The spatial light modulator and the light sensing device are integrally formed on the same substrate.

Abstract: An optical data-storage hard disk drive that uses stationary Phase-Change Microhead Array Chips in place of conventional flying-heads, rotary voice-coil actuators, or other similar types of servo-tracking mechanisms to simultaneously record and/or reproduce data to and/or from a multitude of data-tracks located across the data-surfaces of a multitude of phase-change based disc media using a multitude of microheads.

Abstract: According to one embodiment, a signal transmission circuit includes: a first electro optical converter converting a read electric signal to a first optical signal having an optional wavelength ?R; a first photo-electric converter configured to reconvert the first optical signal to the read electric signal; a second electro optical converter converting a electric signal to be recorded to a second optical signal having a wavelength ?W different from the ?R; a second photo-electric converter reconverting the second optical signal to the electric signal to be recorded; a first optical multiplexer/demultiplexer connected to the first electro optical converter and the second photo-electric converter, and multiplexing and demultiplexing the first and second optical signals; a second optical multiplexer/demultiplexer multiplexing and demultiplexing the first and second optical signals; and an optical transmission medium connected to the first and second optical multiplexers/demultiplexers, and transmits the multiplex

Abstract: Provided are methods of recording and reading optical information in a recording medium using holography. In the method of recording optical information, a first recording operation is performed for recording optical information in a first recording region in an overlapping manner by allowing a reference beam and a signal beam with data loaded to interfere with each other in the first recording region, the reference beam being angularly multiplexed at predetermined intervals. Furthermore, a second recording operation is performed for recording optical information in a second recording region adjacent to the first recording region in an overlapping manner by allowing the reference beam and the signal beam to interfere with each other in the second recording region, the reference beam being angularly multiplexed between the predetermined intervals.

Abstract: In a holographic digital data storage system, a light source generates a reference beam, a holographic optical element saves a plurality of interference patterns between the reference beam and a plurality of beams of specific sizes and a beam splitter splits each reproduced beam into a holographic signal beam and a holographic reference beam. A medium records an interference pattern between the holographic reference beam and the holographic signal beam and reflecting the holographic reference beam to generate a reflective information beam and, if only the holographic reference beam is illuminated, a displaying means displays a holographic reproduced beam for the holographic signal beam and detecting the reflective information beam.

Abstract: A holographic memory system includes a light source for generating a reference beam having a wavelength; and a photodetecting device for selectively detecting a reconstructed signal beam corresponding to the reference beam. The photodetecting device includes a band-pass filter for transmitting light of a wavelength band including the wavelength of the reconstructed signal beam while blocking light having a wavelength deviating from the wavelength band; and a photodetecting unit for detecting the light transmitted through the band-pass filter.

Abstract: A data reading apparatus and method of operating the data reading apparatus. The data reading apparatus is adapted to reading data stored inside an optical storage device. The data reading apparatus has a light source and an image sensor. The light source emits light and illuminates the read-out section of the optical storage device. The image sensor captures the reflected light from the read-out section of the optical storage device to form an image. The data reader may further incorporate an image processor for receiving the image from the image sensor and converting the image into digital data before outputting the data to a host. The forgoing image sensor includes a linear image semsor.

Abstract: In a holographic digital data storage system, holographic page data has at least two concentric patterns with the optical information arranged within an outermost pattern of at least two concentric patterns. Since at least two concentric patterns in the holographic page data are deformed into at least two elliptic patterns in the diffracted beam caused by irradiation of the reference beam, at least two elliptic patterns are extracted from the diffracted beam and then at least two elliptic patterns are estimated to generate at least two estimated concentric patterns. A compensated vector between said at least two elliptic patterns and said at least two estimated concentric patterns is used to reconstruct the optical information from the diffracted beam.

Abstract: The image recording method and image recording apparatus synchronize phase of a light deflector with rotation of a drum in response to the drum start point detection signal generated each time the drum rotates once, expose the two-dimensional image of one frame formed by a group of light sources disposed two-dimensionally onto the recording medium while causing the image at rest on the recording medium relatively thereto, thereafter move the optical system in the auxiliary scanning direction by an integral multiple of a pixel pitch forming one frame as well as deflect an angle of the light deflector in the main scanning direction by one frame so as to expose the next frame and on for one rotation of the drum.

Abstract: Method of storing and retrieving information by exposing cells of a storage medium to a first beam of light having a first set of properties affecting the optical properties of said storage medium, and by exposing a plurality of individual cells, forming a page of information, of said storage medium to a second beam of light having a second set of properties. A third light beam from said storage medium forms an image of said page on a detecting means. The detected light image is converted into electric data signals, each bit of said data signals corresponding to a cell of said storage medium. The first beam of light is generated by a first light source and there is provided an electrooptical means having an electric input for receiving data and being arranged for modulating said first light beam in dependance of said data.

Abstract: An optical disk apparatus of the present invention forms, in a first embodiment, two laser beams for erasure of data and irradiates the two laser beams from a single erasing head 102 so that focuses 207 and 208 thereof may be disposed on a same track of an optical disk 206. In order to construct the erasure head so as to provide two beams, either a two beam semiconductor laser 201 may be used or a beam from a semiconductor laser 215 may be divided into two beams. For the means for dividing the beam into two beams, a Wollaston polarizing prism 216, a Bragg diffraction grating 218, a Foucault prism 219 or some other suitable element can be used. Meanwhile, in a second embodiment, data are reproduced by an optical equivalence method using an optical disk 82, 100 or 206 of a phase change medium which exhibits a phase difference smaller than 180 degrees in reflected light therefrom based on recorded data. The phase difference preferably ranges from 120 degrees to 150 degrees.

Abstract: A confocal scanning microscope can process two-dimensional or third-dimensional optical information at high speed and can be simplified in arrangement. The confocal scanning microscope includes an optical coupling device array composed of a plurality of optical coupling devices arranged on a common substrate in a one-dimensional or two-dimensional fashion, and an objective lens, wherein each of the optical coupling devices has a light-emitting portion and a light-receiving portion closely disposed on the common substrate, and reflected-back light obtained from a target object after light emitted from the light-emitting portion has been reflected on the target object is received and detected near a confocal position by the light-receiving portion.

Abstract: An encryption method and apparatus for holographic data storage are disclosed. In a system using orthogonal phase-code multiplexing, data is encrypted by modulating the reference beam using an encryption key K represented by a unitary operator. In practice, the encryption key K corresponds to a diffuser or other phase-modulating element placed in the reference beam path, or to shuffling the correspondence between the codes of an orthogonal phase function and the corresponding pixels of a phase spatial light modulator. Because of the lack of Bragg selectivity in the vertical direction, the phase functions used for phase-code multiplexing are preferably one dimensional. Such phase functions can be one-dimensional Walsh functions. The encryption method preserves the orthogonality of reference beams, and thus does not lead to a degradation in crosstalk performance.

Abstract: Apparatus and methods for reading an optical disk are provided that use a compact two-dimensional arrangement of beams, with each beam aligned with a track on an optical disk, to provide a compact assembly having a reduced degree of aberration of the outermost beams while maintaining specified minimum distances between the beams. A preferred embodiment uses a two-dimensional diffractive element to split an illumination beam into a plurality of reading beams aligned with the tracks in a two-dimensional arrangement. In an alternative embodiment, a two-dimensional diffractive element is used to stagger the beams so that some tracks on the disk are skipped, further reducing the area of the beams and increasing the number of tracks that may be read simultaneously.

Abstract: Methods and apparatus are provided for illuminating an optical disk in a multi-track optical disk reader. A laser beam is collimated and focused onto an area including multiple, adjacent data tracks on the optical disk. To minimize noise caused by interference resulting from the reflection of multiple beams from the optical disk the coherency of the laser beam is reduced. This is accomplished by one or more of the following techniques: passing the laser beam through a multi-mode optical fiber, combining laser beams from multiple independent laser sources, and modulating the laser operating current at high frequency.

Abstract: A multi-track optical read/write head uses a light valve to split the beam from a single laser diode to a large number of channels, recorded on an optical disc or tape. Readout is achieved by line illumination and a linear array of detectors. The number of channels in the light valve exceeds the number of recorded tracks and a single light valve channel is smaller than the optical resolution of the system. The division into a large number of channels allows to modulate the width of the written mark in order to achieve increased data recording density.

Abstract: An optical disk initializing apparatus includes the first optical system having a gain waveguide laser, a collimator lens, diffraction gratings, and a 45.degree. mirror, the second optical system having a 680-nm red laser, a polarizing beam splitter, a collimator lens, and a .lambda./4 plate, a dichroic mirror, an objective lens, an optical sensor, a phase compensator, a voltage-current conversion amplifier, and an objective lens actuator. The first optical system outputs a first beam for initialization. The second optical system outputs a second beam having a wavelength different from that of the first beam. The dichroic mirror multiplexes the beam emerging from the first optical system and the second beam emerging from the second optical system. The objective lens focuses an output beam emerging from the dichroic mirror on a phase change recording or magneto-optical recording optical disk. The optical sensor detects a focusing error signal from a return beam of the second beam reflected by the optical disk.

Abstract: An optical beam recording device for performing image recording by focusing a plurality of light beams modulated according to an image signal through a focusing optical system onto a photosensitive member, including a light source having a plurality of arrayed light emitting portions for emitting the plurality of light beams; a light detecting device located at a given position for detecting a detecting light beam of the plurality of light beams; and a control device for controlling a focused condition of the plurality of light beams on the photosensitive drum according to a result of detection of the detecting light beam by the light detecting device. With this arrangement, shift of a focal position can be detected with high accuracy without increasing a response speed of the light detecting device and inviting the complication of configuration.

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: A first optical head comprising: a laser diode (LD) array, including N LDs having N emitting portions respectively arranged in a line at a predetermined interval, for emitting N laser beams of single mode; an optical system for forming a single spot as a pixel on a recording medium from the N laser beams such that images of the N emitting portions are contracted and overlapped each other; and a driver for driving the N LDs according to a single video signal. A second optical head comprising: M LD arrays, each including N LDs having N emitting portions respectively arranged in a line and emitting N laser beams of single mode from the N emitting portions; an optical system for forming M single spots as M pixels on a recording medium from the M of N laser beams such that images of the N emitting portions of each LD arrays are contracted and overlapped each other on the recording medium; and a driver for driving the M LD arrays according to M video signals respectively.

Abstract: A method of reading data from an optical disk comprises providing means for illuminating the required part of the disk and acquiring the optical image of a plurality of tracks, providing a detector matrix comprising a plurality of detectors, each of the detectors being capable of producing an output signal which is proportional to the intensity of the light detected by it causing an optical image corresponding to an illuminated area to fall on the detector matrix, transferring the output signal of the detector matrix to image processing means, determining position coordinates of the track center for each data track, by analyzing the output signal of the detector matrix, saving in memory means expected track center data, comprising position coordinates of the track center located by the analysis of the output signal, and if an actually detected track center is shifted with respect to the expected track center, electronically moving the track center position.

Abstract: An apparatus for controlling to support hard disk and/or CD-ROM drives through the PCMCIA interface of a notebook computer system. The apparatus comprises a PCMCIA controller connected to the ISA bus of said computer system for implementing PCMCIA interface functions, and an ATA controller also connected to the ISA bus for implementing ATA interface functions. The apparatus further comprises a multiplexer circuit connected both to the PCMCIA controller and the ATA controller for the apparatus to perform either the PCMCIA or the ATA interface functions under control of a selection signal.

Abstract: The present invention comprises an optical write/read device including a light emitting/receiving portion having light emitting elements and light receiving elements which are arranged in parallel with one another, and a simple optical system. In the optical system, light emitted from the light emitting element is lead to an information recording medium, and light reflected on the information recording medium among lights emitted from the light emitting elements is lead to the light receiving element. Accordingly, the light emitting element can be used as a recording light source and a reading light source, and further the light receiving elements arranged in parallel with the light emitting elements can be used as an optical detector. The information recording medium employed by the optical write/read device includes a column of positional aligning marks.

Abstract: A method of reading data from an optical disk comprises providing means for illuminating the required part of the disk and acquiring the optical image of a plurality of tracks, providing a detector matrix comprising a plurality of detectors, each of the detectors being capable of producing an output signal which is proportional to the intensity of the light detected by it causing an optical image corresponding to an illuminated area to fall on the said detector matrix, transferring the output signal of the detector matrix to image processing means, determining position coordinates of the track center for each data track, by analyzing the output signal of the said detector matrix, saving in memory means expected track center data, comprising position coordinates of the track center located by the analysis of the output signal, and if an actually detected track center is shifted with respect to the expected track center, electronically moving the track center position.

Abstract: A method of reading data from an optical disk comprises providing means for illuminating the required part of the disk and acquiring the optical image of a plurality of tracks, providing a detector matrix comprising a plurality of detectors, each of the detectors being capable of producing an output signal which is proportional to the intensity of the light detected by it causing an optical image corresponding to an illuminated area to fall on the said detector matrix, transferring the output signal of the detector matrix to image processing means, determining position coordinates of the track center for each data track, by analyzing the output signal of the said detector matrix, saving in memory means expected track center data, comprising position coordinates of the track center located by the analysis of the output signal, and if an actually detected track center is shifted with respect to the expected track center, electronically moving the track center position.

Abstract: A method of reading data from an optical disk comprises providing means for illuminating the required part of the disk and acquiring the optical image of a plurality of tracks, providing a detector matrix comprising a plurality of detectors, each of the detectors being capable of producing an output signal which is proportional to the intensity of the light detected by it causing an optical image corresponding to an illuminated area to fall on the said detector matrix, transferring the output signal of the detector matrix to image processing means, determining position coordinates of the track center for each data track, by analyzing the output signal of the said detector matrix, saving in memory means expected track center data, comprising position coordinates of the track center located by the analysis of the output signal, and if an actually detected track center is shifted with respect to the expected track center, electronically moving the track center position.

Abstract: A multilayer optical disk system, which includes an optical disk unit having a number of connected optical disks. A number of light sources, such as diode lasers, are used to provide a number of light beams of different wavelengths. A wavelength multiplexer combines the light beams into a single beam which is then axially dispersed so that light of different wavelengths are simultaneously focuses onto the different optical disks. A wavelength demultiplexer splits light reflected from the optical disks according to wavelength to produce separate beams which are then separately detected.

Abstract: An optical information storage apparatus includes a differential type optical switch element, and an optical fiber. The optical switch element shifts from a non-emission state to an emission state upon reception of an optical input. The optical fiber constitutes a first optical path. The optical fiber receives an optical output emitted from the optical switch element through at least one end face, guides the optical output, and causes an output beam to be incident, as the optical input, onto the optical switch element.

Abstract: A peristrophic multiplexing system directs a signal light beam and reference light beam onto a selected recording spot in the recording medium. The light beams collectively define a plane of interaction. Either the recording medium or the signal/reference beam are rotated relative to the other through a succession of peristrophic multiplexing angles. Those angles cause relative rotation about an axis that is not perpendicular to the plane of selectivity. The rotation occurs contemporaneously with the modulating of the hologram on the medium.

Abstract: An optical recording, erasing and playback system. One or more functions in a conventional optical disc system are performed by one or more holographic optical elements (HOE). Exemplary of the functions performed by the HOE are collimation, beam shaping, combining of beams, and focusing. According to preferred embodiments, volume HOEs are utilized.

Abstract: A method of reading data from an optical disk comprises providing means for illuminating the required part of the disk and acquiring the optical image of a plurality of tracks, providing a detector matrix comprising a plurality of detectors, each of the detectors being capable of producing an output signal which is proportional to the intensity of the light detected by it causing an optical image corresponding to an illuminated area to fall on the said detector matrix, transferring the output signal of the detector matrix to image processing means, determining position coordinates of the track center for each data track, by analyzing the output signal of the said detector matrix, saving in memory means expected track center data, comprising position coordinates of the track center located by the analysis of the output signal, and if an actually detected track center is shifted with respect to the expected track center, electronically moving the track center position.

Abstract: A wavelength-multiple optical memory is provided which is capable of performing high density recording/reading at room temperature. A large number of cylindrical recording members, each of which is made up of plural portions along a central axis of the cylinder and plural sizes which vary slightly in a direction perpendicular to the central axis, are formed on a substrate. The cylindrical recording members may be of circular cylindrical or elliptical cylindrical shape. It is preferable that recording material layers of the cylindrical recording members have complex refractive indexes which are different from each other. A difference in size of the recording material layers of the circular or elliptical cylinders having sizes closest to each other is preferably in a range of 1/5000 to 1/5 of an average of the sizes, are even more preferably in a range of 1/500 to 1/10. Wavelength-multiple recording is performed by changing a wavelength of a light beam emitted from a light source within a very narrow range.

Abstract: The invention relates to an optical computing element for use in an optical computer utilizing computing light rays having a plurality of wavelength components. The optical computing element comprises a photo-chemical hole burning element which functions as a wavelength selecting filter of the computing light rays. Therefore, the optical computer using the photo-chemical hole burning element of the invention can perform arithmetic operations by taking advantage of differences in optical wavelength. The computer can efficiently perform bulky arithmetic processing, and can also speedily perform arithmetic operations through simultaneous parallel processing for information.

Abstract: Information is recorded by creating recording hole at a predetermined wavelength position on a memory element with a characteristic of wavelength selective optical data storage. Because the memory element is pit-like, it causes diffraction of a light beam transmitted through or reflected by it. The diffracted beams are detected for positioning a beam spot right on the selected memory element.

Abstract: A recording medium for wavelength selective optical data storage has at least one memory element on which information is recorded by creating recording holes on the absorption spectrum thereof. The spectrum has at least one prerecorded hole for identifying the wavelength positions of the recording holes.

Abstract: A first memory element and a second memory element have characteristics of wavelength selective optical data storage. Information is recorded on the first memory element by creating recording holes by a narrow band light beam at specific wavelength positions within a broad inhomogenous absorption line. The second element has at least one prerecorded hole at a specific wavelength position thereof for detecting the wavelength positions of the recording holes.

Abstract: A digital information recording and reproducing method for significantly improving the transfer rate of digital information, comprises the steps of: forming a plurality of light beam guide tracks on a recording medium capable of multiple light-wavelength recording, the tracks being spaced apart by a predetermined pitch and each of the tracks comprising a series of pre-pits disposed in a scan direction and spaced apart by an interval longer than the diameter of a spot of a light beam for use in recording and reproducing; and recording and reproducing an information bit by changing the light beam to have a different wavelength predetermined n times in a predetermined order while the light beam is scanned by one interval of the pre-pits.