CN115775568A

CN115775568A - Method and device for improving hologram recording and reading speed in cross-shift multiplexing

Info

Publication number: CN115775568A
Application number: CN202111045489.0A
Authority: CN
Inventors: 郑穆; 罗铁威; 田军; 胡德骄; 刘义诚; 陶晓晓
Original assignee: Guangdong Amethyst Information Storage Technology Co ltd
Current assignee: Guangdong Amethyst Information Storage Technology Co ltd
Priority date: 2021-09-07
Filing date: 2021-09-07
Publication date: 2023-03-10

Abstract

The invention provides a method and a device for simplifying the movement of an optical disk and improving the recording speed of a hologram in cross-shift multiplexing, wherein the method comprises the following steps: s1: utilizing a beam of reference light and a beam of signal light carrying input information to perform interference exposure at a recording position in a storage medium to form a hologram for recording data information; s2: shift multiplexing recording of the hologram is performed on the entire storage medium by using a shift multiplexing method; s3: rotating the optical head to change the direction of the grating vector, repeating the steps S1-S2, and recording holograms with different grating vector directions on the whole storage medium to realize the cross multiplexing recording of the holograms; s4: repeating step S3 completes the cross-shift multiplexing recording on the entire storage medium. The method provided by the invention realizes the cross multiplexing recording of the hologram by rotating the optical head to change the vector direction of the grating formed by interference. The process adopts the rotation of the optical head to replace the complex position movement of the medium, reduces the position control requirement of the storage medium, and ensures that the moving mechanism of the storage medium is simplified, the volume is relatively small and the access speed is faster.

Description

Method and device for improving hologram recording and reading speed in cross-shift multiplexing

Technical Field

The present invention relates to the field of holographic storage, and more particularly, to a method and apparatus for improving hologram recording and reading speed in cross-shift multiplexing.

Background

Spherical reference light shift multiplexing recording is a method of recording holograms using spherical waves as reference light. The medium is moved a small distance after recording a hologram, and the reproduced light intensity of the hologram is close to zero because the Bragg matching condition is difficult to satisfy after the spherical wave is moved, so that a new hologram can be recorded after the shift without crosstalk with the previous hologram, thereby realizing the shift multiplexing recording.

The principle of shift multiplex recording is shown in fig. 1. In shift multiplexing recording, signal light and spherical reference light are incident on a medium at different predetermined angles. In general, the direction of the grating vector for interference recording of the signal light and the reference light is on a plane determined by the optical axes of the signal light and the reference light.

As shown in fig. 2, shift multiplex recording is achieved by controlling the relative movement of the medium and the head along the plane, i.e. the displacement of the medium is along the direction of the grating vector. In this way, cross-talk between adjacent holograms can be avoided if the medium is shifted in the direction of the grating vector and in the direction perpendicular to the grating vector by a fixed interval, for example 1 μm,2 μm,5 μm and 500 μm, respectively. On the other hand, the number of multiplexing times can be further increased by improving the performance of the storage medium. As shown in fig. 3, on the basis of shift multiplexing, cross-overlay recording of holograms can be performed by rotating the medium in its plane by an angle of about 15 °,30 °,45 ° or more.

Fig. 4 and 5 show a method of performing such cross-shift multiplex recording on an optical disc. In fig. 4, the optical head is set at position a and position B with respect to the direction of the center of the medium, respectively, shift-multiplex recording is performed by moving the medium in the direction of the arrow, and after recording of one line is completed, the medium is rotated by a small angle to perform shift-multiplex hologram recording of the next line. The holograms recorded by the optical head at position a and position B have a grating vector angle of 180 deg., so that a cross-multiplexing of 180 deg. is achieved.

Fig. 5 shows a method of performing cross-multiplex recording at another angle. In the method, the optical head is moved to a position C and a position D with respect to the center of the medium, and the medium is subjected to shift multiplexing recording along an arrow shown in fig. 5, thereby realizing hologram recording with a specific angle grating vector.

However, recording on such an optical disc medium requires moving the optical disc medium over a long distance, which results in an increase in the volume of the optical disc drive and a decrease in the access speed.

Disclosure of Invention

The present invention is directed to overcoming at least one of the above-mentioned drawbacks of the prior art, and providing a method and apparatus for improving the recording and reading speed of holograms in cross-shift multiplexing, which is used to solve the problems of increasing the volume of an optical disc drive and reducing the access speed caused by moving an optical disc medium over a long distance when performing shift multiplexing recording/reading of holograms on a storage medium.

The technical scheme adopted by the invention comprises the following steps:

a method for increasing hologram recording speed in cross-shift multiplexing, comprising the steps of: s1: utilizing a beam of reference light and a beam of signal light carrying input information to perform interference exposure at a recording position in a storage medium to form a hologram for recording data information; s2: shift multiplexing recording of the hologram is performed on the entire storage medium by using a shift multiplexing method; s3: rotating the optical head to change the direction of the grating vector, repeating the steps S1-S2, and recording the holograms with different grating vector directions on the whole storage medium to realize the cross multiplexing recording of the holograms; s4: repeating step S3 completes the cross-shift multiplexing recording on the entire storage medium.

The method for improving the recording speed of the hologram changes the recording position of the hologram on the storage medium by moving the optical disc, thereby realizing the shift multiplexing recording on the optical disc; the optical head is rotated to change the grating vector direction, so that a plurality of holograms with different grating vector directions can be recorded in a crossed multiplexing mode at the same position, the rotation of the optical head is adopted to replace the complex position movement of a medium in the process, the position control requirement of the storage medium is reduced, the moving mechanism of the storage medium is simplified, the size is relatively small, and the access speed is higher.

In step S2, shift multiplexing recording of holograms is performed over the entire storage medium, in particular

When the storage medium is circular, firstly, the storage medium is translated along the radial direction to perform displacement multiplexing recording in the radial direction, and then the storage medium is rotated by a certain angle around the center of a circle and then translated along the radial direction to perform displacement multiplexing recording in the other radial direction;

when the storage medium is circular, firstly rotating the storage medium around the center of a circle to perform shift multiplexing recording on the circular optical channel, then radially moving the storage medium for a distance, and then rotating the storage medium around the center of a circle to perform shift multiplexing recording on the other circular optical channel;

when the storage medium is rectangular, the storage medium is translated along the first side to make it perform shift multiplex recording on the track, then the storage medium is returned to the original position and moved along the second side for a certain distance, and then the storage medium is translated along the first side to make it perform shift multiplex recording on another track.

In step S3, the optical head is rotated to change the direction of the grating vector, specifically:

changing the azimuth of the entrance face by rotating the optical head about a rotation axis, thereby changing the azimuth of the recorded holographic grating inside the medium.

There are three ways to change the azimuth angle of the recorded holographic grating inside the medium, the first way is to rotate the reference light around the optical axis of the signal light with the optical axis of the signal light as the rotation axis when the optical axis direction of the incident signal light is perpendicular to the storage medium. The second way is to rotate the optical system composed of the reference light and the signal light around a rotation axis perpendicular to the storage medium when the incident directions of the reference light and the signal light are not perpendicular to the storage medium. The third way is to rotate the signal light around the optical axis of the reference light with the optical axis of the reference light as a rotation axis when the incident direction of the reference light is perpendicular to the storage medium. The incident direction of the reference light and/or the signal light is changed in a simple manner, so that the grating vector direction of the recorded hologram is changed, a plurality of holograms can be recorded at the same position in a multiplexing manner, and the storage medium does not need to be moved in the process.

In the present invention, whether only the reference light is rotated; or only the signal light rotates or an optical system consisting of the reference light and the signal light rotates, and the rotation axes of the system are in the direction vertical to the storage medium; if the optical axis of the signal light is perpendicular to the storage medium, the reference light may rotate around the optical axis of the signal light with the optical axis of the signal light as a rotation axis, thereby changing the incident direction of the reference light; if the optical axis of the reference light is perpendicular to the storage medium, the signal light may rotate around the optical axis of the reference light with the optical axis of the reference light as a rotation axis, thereby changing the incident direction of the signal light; if the optical axes of the signal light and the reference light are not perpendicular to the storage medium, the optical system formed by the reference light and the signal light needs to rotate around a rotation axis, and the rotation axis should be perpendicular to the storage medium.

The reference light is spherical wave in the invention.

A method for improving the reading speed of a hologram in cross-shift multiplexing, when the optical axis direction of the incident signal light is perpendicular to a storage medium or when the optical axis directions of the incident reference light and the signal light are not perpendicular to the storage medium, using the same one of reference light, and reproducing the recorded hologram at any recording position on the storage medium by linear shift multiplexing and changing the incident direction of the reference light, comprising the following steps: r1: the optical head outputs a special reference light beam to irradiate a recording position of the hologram in the storage medium, and the hologram is read; r2: moving the optical disk to make the optical head align with all the holograms recorded in the shift multiplexing mode in turn to carry out the shift multiplexing reading of the whole storage medium; r3: rotating the optical head to change the incident direction of the reference light, repeating the steps R1-R2, reading the holograms with different grating vector directions on the whole storage medium, and realizing the cross multiplexing reading of the holograms; r4: repeating step R3 completes the cross-shift multiplexing read on the entire storage medium.

A method for increasing the reading speed of holograms in cross-shift multiplexing, when the optical axis direction of the incident reference light is perpendicular to the storage medium, using the same beam of reference light as above, receiving the reproduction light of different emitting directions on the storage medium by linear shift multiplexing and rotating the reading device, reproducing the recorded holograms at any recording position on the storage medium, comprising the following steps: r1: the optical head outputs a beam of specific reference light to irradiate the recording position of the hologram in the storage medium to read the hologram; r2: setting a reading device in one direction, moving the optical disk, and making the optical head align with all the holograms recorded in the shift multiplexing mode in sequence to carry out the shift multiplexing reading of the whole storage medium; r3: rotating the reading device to receive the reproduction light in other emergent directions, repeating the steps R1-R2, reading the holograms with different grating vector directions on the whole storage medium, and realizing the cross multiplexing reading of the holograms; r4: and repeating the step R3 to complete the cross-shift multiplexing reading on the whole storage medium.

A method for increasing the reading speed of a hologram in cross-shift multiplexing, when the optical axis direction of the incident reference beam is perpendicular to a storage medium, by using the same reference beam, and by using a linear shift multiplexing method and a method for setting a plurality of reading devices to simultaneously receive reproduction beams in different emitting directions on the storage medium, the recorded hologram is reproduced at any recording position on the storage medium, comprising the following steps: r1: the optical head outputs a beam of specific reference light to irradiate the recording position of the hologram in the storage medium to reproduce the hologram; r2: setting reading devices in multiple directions, receiving the reproduction light of multiple crossed holographic gratings, and reading parallel data; r3: moving the optical disk to make the optical head align with all the holograms recorded in the shift multiplexing mode in turn to carry out the shift multiplexing reading of the whole storage medium; r4: repeating step R3 completes the cross-shift multiplexing read on the entire storage medium.

Specifically, in step R2, moving the optical disc to make the optical head sequentially align with all holograms recorded in the shift multiplexing manner to perform shift multiplexing reading of the entire storage medium specifically includes:

when the storage medium is circular, the storage medium is made to translate along the radial direction to perform shift multiplexing reading in the radial direction, and then the storage medium is rotated around the center of a circle by a certain angle and then translated along the radial direction to perform shift multiplexing reading in the other radial direction.

When the storage medium is circular, the storage medium is firstly rotated around the center of a circle to perform shift multiplexing reading on the circular optical channel, and then the storage medium is radially moved for a distance and then rotated around the center of a circle to perform shift multiplexing reading on the other circular optical channel.

When the storage medium is rectangular, the storage medium is translated along the first edge direction to perform shift multiplexing reading on the track, then the storage medium is returned to the original position and is moved for a distance along the second edge direction, and then the storage medium is translated along the first edge direction to perform shift multiplexing reading on the other track.

A recording and reproducing apparatus for increasing a hologram recording speed in cross-shift multiplexing includes a light source, a reference light path, a signal light path, a reading device, and a medium stage; the light source is divided into two beams, wherein reference light which is transmitted to the storage medium through the reference light path and does not carry data information is adopted, and signal light which is transmitted through the signal light path and carries data information is adopted; the reference light and the signal light interfere on a storage medium supported by a medium platform, and interference fringes are recorded in the storage medium through exposure to form a hologram; when the reference light irradiates on the position of the storage medium where the holographic image is recorded, the signal light carrying the data information can be reproduced; the reading device is used for reading the data information reproduced by the reference light; the media platform also includes a media movement device for translating and/or rotating a storage medium supported by the media platform.

The invention provides a recording and reproducing device for improving the reading and writing speed of a hologram in cross-shift multiplexing, which comprises:

(1) If the direction of the optical axis of the incident signal light is perpendicular to the storage medium, the optical axis of the signal light can be used as a rotation axis of the reference light, and the reference light objective lens, the half-wave plate and the polarization beam splitter prism in the reference light path are assembled into a whole body capable of rotating around the optical axis of the signal light.

(2) If the direction of the optical axis of the incident reference light is perpendicular to the storage medium, the optical axis of the reference light can be used as a rotating axis of the signal light, and the half-wave plate, the polarization beam splitting prism and the Fourier lens in the signal light path are assembled into a whole body capable of rotating around the optical axis of the reference light.

Further, when the half-wave plate, the polarization beam splitter prism and the Fourier lens in the signal light path rotate around the optical axis of the reference light, the reading device also rotates along with the half-wave plate, the polarization beam splitter prism and the Fourier lens in the signal light path, so that the reading device can accurately detect the data information reproduced by the reference light.

(3) If the incident directions of the signal light and the reference light are not perpendicular to the storage medium, an axis perpendicular to the direction of the storage medium is taken as a rotating axis, and the half-wave plate, the reflecting prism and the Fourier lens in the signal light path, the reference light objective lens and the polarization beam splitting prism in the reference light path are assembled together to form a whole body capable of rotating around the axis perpendicular to the direction of the storage medium.

Further, when the half-wave plate, the reflecting prism and the Fourier lens in the signal light path rotate around an axis perpendicular to the direction of the storage medium, the reading device also rotates along with the reflecting prism and the Fourier lens in the signal light path, so that the reading device can accurately detect the data information reproduced by the reference light.

That is, the azimuth angle of the incident surface can be changed by rotating the whole of the reference optical path and the signal optical path, so that the grating vector direction of the recorded hologram is changed, and a plurality of holograms with different grating vector directions can be recorded in a multiplexing way on the same recording position.

Further, the reference optical path and the signal optical path share a segment of optical path, and the shared segment of optical path includes: the tunable semiconductor laser comprises a tunable semiconductor laser, a plurality of reflectors, a deformable prism, an optical isolator, a plurality of half-wave plates, an acousto-optic modulator, a beam expander, a polarization beam splitter prism, a plurality of Fourier lenses and a Nyquist aperture.

Compared with the prior art, the invention has the beneficial effects that: the method provided by the invention changes the vector direction of the grating formed by interference by rotating the optical head, thereby realizing cross multiplexing recording of the hologram. The process adopts the rotation of the optical head to replace the complex position movement of the medium, reduces the position control requirement of the storage medium, and ensures that the moving mechanism of the storage medium is simplified, the volume is relatively small and the access speed is faster.

Drawings

Fig. 1 is a schematic diagram of a spherical wave shift multiplex recording in the background art of the present invention.

Fig. 2 is a schematic diagram of vector directions of a reference light, a signal light and a hologram grating in the background art of the present invention.

Fig. 3 shows a cross-shift multiplexing recording method in a square medium according to the background art of the present invention.

Fig. 4 is a schematic diagram of cross-shift multiplexing in a circular optical disc medium in the background of the invention.

Fig. 5 is a schematic diagram of cross-shift multiplexing in a circular optical disc medium in the background of the invention.

Fig. 6 is a schematic flow chart of steps S1 to S4 in embodiment 1 of the present invention.

Fig. 7 is a schematic diagram of cross-shift multiplexing in a circular optical disc medium in

embodiments

1 and 2 of the present invention.

Fig. 8 is a schematic diagram of cross-shift multiplexing in a circular optical disc medium in

embodiments

1 and 2 of the present invention.

Fig. 9 is schematic diagrams of cross-shift multiplexing in square media in

embodiments

1 and 2 of the present invention.

Fig. 10 is a schematic view showing the vector directions of the reference light, the signal light, and the hologram grating in embodiment 3 of the present invention.

Fig. 11 is a schematic diagram showing the distribution of the raster vector directions of the cross-shift multiplexing recording in embodiment 3 of the present invention.

FIG. 12 is a schematic view showing the structure of a cross-shift multiplexing recording and reproducing apparatus according to embodiment 3 of the present invention.

FIG. 13 is a schematic structural diagram of a cross-shift multiplexing recording and reproducing apparatus according to embodiment 3 of the present invention.

FIG. 14 is a schematic structural diagram of a cross-shift multiplexing recording and reproducing apparatus according to embodiment 3 of the present invention.

Detailed Description

The drawings are only for purposes of illustration and are not to be construed as limiting the invention. For a better understanding of the following embodiments, certain features of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.

Example 1

As shown in fig. 6, the present embodiment provides a method for increasing a hologram recording speed in cross-shift multiplexing, comprising the steps of:

the position of the optical head relative to the storage medium is fixed.

Executing step S1: a hologram is formed by interference exposure of a reference beam and a signal beam carrying input information at a recording position of an optical head in a storage medium for recording data information.

And executing the step S2: shift-multiplex recording of holograms is performed over the entire storage medium using a shift-multiplex method.

As shown in fig. 7, the storage medium is a disk, and in the first step, the storage medium is translated in a radial direction to perform shift multiplexing recording in the radial direction, and in the second step, the storage medium is rotated around the center of a circle by a certain angle and then translated in the radial direction to perform shift multiplexing recording in another radial direction.

As shown in fig. 8, the storage medium is a disk, and in the first step, the storage medium is rotated around the center of the circle to perform shift multiplexing recording on the circular track, and in the second step, the storage medium is moved a distance in the radial direction and then rotated around the center of the circle to perform shift multiplexing recording on the other circular track.

As shown in fig. 9, the storage medium is a square plate, and the storage medium is first translated in a direction along a first edge of the storage medium to perform shift-multiplexed recording on the track; and the second step returns the storage medium to the original position, moves a distance along the direction of the second side, and then translates the storage medium along the direction of the first side to make the storage medium perform shift multiplexing recording on another track.

And executing the step S3: rotating the optical head to change the direction of the grating vector, repeating the steps S1-S2, and recording holograms with different grating vector directions on the whole storage medium to realize the cross multiplexing recording of the holograms; changing the azimuth of the entrance face by rotating the optical head about a rotation axis, thereby changing the azimuth of the recorded holographic grating inside the medium.

And when the direction of the optical axis of the incident signal light is vertical to the storage medium, the reference light is rotated around the optical axis of the signal light by taking the optical axis of the signal light as a rotating axis.

When the optical axis directions of the incident reference light and the signal light are not perpendicular to the storage medium, rotating an optical system formed by the reference light and the signal light around a rotating shaft, wherein the rotating shaft is perpendicular to the storage medium.

And when the optical axis direction of the incident reference light is perpendicular to the storage medium, the signal light is rotated around the optical axis of the reference light by taking the optical axis of the reference light as a rotating axis.

And executing the step S4: repeating step S3 completes the cross-shift multiplexing recording on the entire storage medium.

Preferably, the reference light is a spherical wave.

The embodiment provides a method for improving the recording speed of the hologram, and the direction of the grating vector formed by interference is changed by rotating the optical head in step S3, so that the cross-multiplexing recording of the hologram is realized. The process adopts the rotation of the optical head to replace the complex position movement of the medium, reduces the position control requirement of the storage medium, and ensures that the moving mechanism of the storage medium is simplified, the volume is relatively small and the access speed is faster.

Example 2

The present embodiment provides a method for increasing the hologram reading speed in cross-shift multiplexing, when the optical axis direction of the incident signal light is perpendicular to the storage medium or when the optical axis directions of the incident reference light and the signal light are not perpendicular to the storage medium, using the same reference light as that used in recording, to reproduce the recorded hologram at any recording position on the storage medium by linear shift multiplexing and changing the azimuth angle of the incident plane, specifically including the following steps: r1: the optical head outputs a special reference light beam to irradiate a recording position of the hologram in the storage medium, and the hologram is read; r2: moving the optical disc to make the optical head align with all the holograms recorded in the shift multiplexing mode in turn to perform shift multiplexing reading of the whole storage medium; r3: rotating the optical head to change the incident direction of the reference light, repeating the steps R1-R2, reading the holograms with different grating vector directions on the whole storage medium, and realizing the cross multiplexing reading of the holograms; r4: repeating step R3 completes the cross-shift multiplexing read on the entire storage medium.

The present embodiment further provides another method for increasing the hologram reading speed in cross-shift multiplexing, when the optical axis direction of the incident reference light is perpendicular to the storage medium, using the same one of reference light as above, to receive the other emergent direction reconstruction light on the storage medium through linear shift multiplexing and rotation of the reading device, and reconstructing the recorded hologram at any recording position on the storage medium, including the following steps: r1: the optical head outputs a beam of specific reference light to irradiate the recording position of the hologram in the storage medium to read the hologram; r2: setting a reading device in one direction, moving the optical disk, and making the optical head align with all the holograms recorded in the shift multiplexing mode in sequence to carry out the shift multiplexing reading of the whole storage medium; r3: rotating the reading device to receive the reproduction light in other emergent directions, repeating the steps R1-R2, reading the holograms with different grating vector directions on the whole storage medium, and realizing the cross multiplexing reading of the holograms; r4: repeating step R3 completes the cross-shift multiplexing read on the entire storage medium.

The present embodiment further provides another method for increasing the hologram reading speed in cross-shift multiplexing, when the optical axis direction of the incident reference light is perpendicular to the storage medium, by using the same bundle of reference light as above, a method for simultaneously receiving reproduction light in all exit directions on the storage medium by linear shift multiplexing and setting a plurality of reading devices, and reproducing the recorded hologram at any recording position on the storage medium, specifically comprising the following steps: r1: the optical head outputs a beam of specific reference light to irradiate the recording position of the hologram in the storage medium to read the hologram; r2: setting reading devices in multiple directions, receiving the reproduction light of multiple crossed holographic gratings, and reading parallel data; r3: moving the optical disk to make the optical head align with all the holograms recorded in the shift multiplexing mode in turn to carry out the shift multiplexing reading of the whole storage medium; r4: and repeating the step R3 to complete the cross-shift multiplexing reading on the whole storage medium.

Specifically, in step R2, moving the optical disc to make the optical head sequentially align with all holograms recorded in the shift multiplexing manner to perform shift multiplexing reading of the entire storage medium includes:

as shown in fig. 7, when the storage medium is circular, the storage medium is first translated in the radial direction to perform shift multiplexing reading in the radial direction, and then the storage medium is rotated by a certain angle around the center of a circle and then translated in the radial direction to perform shift multiplexing reading in another radial direction.

As shown in fig. 8, when the storage medium is circular, the storage medium is rotated around the center of the circle to perform shift multiplexing reading on the circular track, and then the storage medium is moved a distance in the radial direction and then rotated around the center of the circle to perform shift multiplexing reading on the other circular track.

As shown in fig. 9, when the storage medium is rectangular, the storage medium is translated in the direction of the first side of the storage medium to perform shift-multiplexing reading on the track, and then the storage medium is returned to the original position and moved in the direction of the second side of the storage medium for a distance, and then the storage medium is translated in the direction of the first side of the storage medium to perform shift-multiplexing reading on the other track.

Example 3

As shown in fig. 12, the present embodiment provides a recording and reproducing apparatus for increasing a hologram recording speed in cross-shift multiplexing, including a light source, a reference optical path, a signal optical path, a reading apparatus, and a medium stage.

The light source is divided into two beams, reference light which is transmitted to the storage medium through the reference light path and does not carry data information is adopted, and signal light which is transmitted through the signal light path and carries data information is adopted.

The reference light and the signal light interfere on a storage medium 150 supported by a medium stage, and interference fringes are recorded in the storage medium by exposure to form a hologram; when the reference light is irradiated on a location of the storage medium 150 where the hologram is recorded and has the same wavefront as that at the time of recording, the signal light carrying data information can be reproduced.

The reading device is used for reading the data information reproduced by the reference light, and the reading device is specifically a CMOS camera 140. After the signal light carrying the data information passes through the fourth fourier lens 114, the projected two-dimensional image information is collected by the reading device CMOS camera 140 and decoded and read.

The media platform also includes media movement means for translating and/or rotating the storage media 150 supported by the media platform.

As shown in fig. 12, the direction of the optical axis of the incident signal light is perpendicular to the storage medium 150, that is, the optical axis of the signal light is in the perpendicular direction, and the reference light objective lens 130, the half-wave plate 54 and the second polarization beam splitter prism 92 in the reference optical path are assembled as a whole rotatable about the optical axis of the signal light.

When the reference light objective lens 130, the fourth half-wave plate 54 and the second polarization beam splitter prism 92 in the reference light path are assembled into a whole body which can rotate around the optical axis of the signal light, the azimuth angle of the reference light incident on the storage medium 150 can be controlled by controlling the rotation of the whole body, as shown in fig. 10 and 11, and by changing the azimuth angle of the reference light incident on the storage medium 150 to change the grating vector direction of the recorded hologram, a plurality of holograms with different grating vector directions can be recorded on the same recording position of the storage medium 150, thereby realizing the cross-multiplexing of the holograms.

Specifically, as shown in fig. 12, the reference optical path and the signal optical path of the apparatus provided in the present embodiment share one optical path, and the shared one optical path includes: the tunable semiconductor laser device comprises a tunable semiconductor laser 10, a first reflecting mirror 21, a second reflecting mirror 22, a third reflecting mirror 23, an anamorphic prism 30, an optical isolator 40, a first half-wave plate 51, a second half-wave plate 52, an acousto-optic modulator 60, a beam expander 70, an aperture filter 80, a first polarization beam splitter prism 91, a first Fourier lens 111, a second Fourier lens 112 and a Nyquist aperture 120.

Specifically, the recording and reproducing apparatus operates as follows: the tunable semiconductor laser 10 outputs a beam of light, the beam of light sequentially passes through the second reflecting mirror 22, the first reflecting mirror 21, the anamorphic prism 30, the optical isolator 40, the first half-wave plate 51, the acousto-optic modulator 60, the third reflecting mirror 23, the second half-wave plate 52, the beam expander 70 and the small-aperture filter 80, the beam of light is separated into a reference beam and a signal beam through the first polarization beam splitter prism 91, the signal beam enters the fourth reflecting mirror 24, is reflected to the spatial light modulator 100 through the fourth reflecting mirror 24, loads a signal, is combined with the reference beam after being reflected through the first polarization beam splitter prism 91, the reference beam and the signal beam jointly pass through the first fourier lens 111, the nyquist small aperture 120 and the second fourier lens 112, the reference beam and the signal beam are separated through the second polarization beam splitter prism 92, the reference beam enters the fourth half-wave plate 54, enters the storage medium 150 through the reference beam objective 130, the signal beam enters the storage medium 150 after entering the third fourier lens (signal beam objective) 113, and interferes with the reference beam on the storage medium 150 supported by the medium platform to generate a holographic exposure.

If the same recording position needs to be subjected to cross multiplexing, the whole assembled by the reference light objective lens 130, the fourth half-wave plate 54 and the second polarization beam splitter prism 92 rotates around the optical axis of the signal light, the azimuth angle of the reference light incident on the storage medium 150 is controlled by controlling the rotation of the whole, and the vector direction of the hologram recorded by interference exposure with the signal light is changed by changing the azimuth angle of the reference light incident on the storage medium 150, so that a plurality of holograms with different grating vector directions can be recorded on the same recording position of the storage medium 150, and the cross multiplexing of the holograms is realized.

If the shift multiplexing recording of the hologram is to be performed on the storage medium, the storage medium 150 supported by the medium platform is translated and/or rotated by the medium moving device to implement the shift multiplexing recording of the hologram.

If the hologram recorded on the storage medium needs to be reproduced, the hologram is irradiated on the storage medium 150 through the same optical path by using the same reference beam to reproduce signal light carrying data information, and the signal light carrying data information is projected on the reading device CMOS camera 140 after passing through the fourth fourier lens 114. If the holograms recorded at the same recording position by cross-multiplexing are to be reproduced, the azimuth angle at which the reference beam is incident on the storage medium 150 is changed by controlling the above-described overall rotation rotatable about the optical axis of the signal beam, so that a plurality of holograms which are cross-multiplexed are reproduced.

The recording and reproducing apparatus for improving the recording speed of the hologram changes the incident direction of the reference light by the above-mentioned whole rotatable around the optical axis of the signal light, so that the grating vector direction of the hologram is changed, and a plurality of holograms with different grating vector directions can be recorded at the same position in a multiplexing manner.

As shown in fig. 13, this embodiment also provides another recording and reproducing apparatus for increasing the hologram recording speed in cross-shift multiplexing, in which the incident direction of the reference light is perpendicular to the storage medium 150, that is, the optical axis of the reference light is in the perpendicular direction. Meanwhile, a half-wave plate 53 is added in front of the polarization beam splitter prism 92 to change the polarization direction of the reference light and the signal light, so that the reference light is transmitted by the polarization beam splitter prism 92, and the signal light is reflected by the polarization beam splitter prism 92. The third fourier lens (signal light objective lens) 113, the half-wave plate 54 and the polarization beam splitting prism 92 in the signal light path are assembled as one body rotatable around the optical axis of the signal light.

The azimuth angle of the incident plane is changed by the whole body capable of rotating around the optical axis of the reference light so as to change the azimuth angle of the grating vector of the hologram, thereby multiplexing and recording a plurality of holograms with different grating vector directions on the same position.

As shown in fig. 14, this embodiment also provides another recording and reproducing apparatus for increasing the read-write speed of holograms in cross-shift multiplexing. The incident directions of the signal light and the reference light are not perpendicular to the storage medium 150. And a half-wave plate 53 is added behind the polarization beam splitting prism 92 to change the polarization direction of the signal light. The half-wave plate 54 is removed so that the polarization directions of the reference light and the signal light are the same. The half-wave plate 53, the reflecting prism 160 and the third fourier lens (signal light objective lens) 113 in the signal light path, and the reference light objective lens 130 and the second polarization beam splitter prism 92 in the reference light path are assembled together into a whole body which can rotate around the vertical direction; the vertical direction is a direction perpendicular to the storage medium 150.

The incident azimuth angles of the reference light and the signal light are changed through the whole body capable of rotating around the vertical direction to change the grating vector azimuth angle of the hologram, so that a plurality of holograms with different grating vector directions can be multiplexed and recorded on the same recording position of the same hologram line.

It should be understood that the above-mentioned embodiments of the present invention are only examples for clearly illustrating the technical solutions of the present invention, and are not intended to limit the specific embodiments of the present invention. Any modification, equivalent replacement, and improvement made within the spirit and principle of the claims of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for increasing the recording speed of holograms in cross-shift multiplexing, characterized by the steps of:

s1: utilizing a beam of reference light and a beam of signal light carrying data information to perform interference exposure at a recording position in a storage medium to form a hologram for recording the data information;

s2: shift multiplexing recording of the hologram is performed on the entire storage medium by using a shift multiplexing method;

s3: rotating the optical head to change the direction of the grating vector, repeating the steps S1-S2, and recording holograms with different grating vector directions on the whole storage medium to realize the cross multiplexing recording of the holograms;

s4: repeating step S3 completes the cross-shift multiplexing recording on the entire storage medium.

2. The method for increasing the recording speed of holograms in cross-shift multiplexing as claimed in claim 1, wherein the step S2 is to perform shift multiplexing recording of holograms on the whole storage medium, specifically:

3. The method for improving the recording speed of the hologram in the cross-shift multiplexing as claimed in claim 2, wherein the step S3 of rotating the optical head to change the direction of the grating vector is to change the azimuth angle of the incident surface by rotating the optical head around a rotation axis, so as to change the azimuth angle of the recorded holographic grating inside the medium, specifically:

when the direction of the optical axis of the incident signal light is perpendicular to a storage medium, the optical axis of the signal light is taken as a rotating axis, and the reference light is rotated around the optical axis of the signal light;

4. The method for improving the recording speed of the hologram in the cross-shift multiplexing as claimed in claim 2, wherein the step S3 of rotating the optical head to change the direction of the grating vector is to change the azimuth angle of the incident surface by rotating the optical head around a rotation axis, so as to change the azimuth angle of the recorded holographic grating inside the medium, specifically:

5. A method of increasing the recording speed of holograms in cross-shift multiplexing as claimed in any of claims 1 to 4, characterized in that the reference light is a spherical wave.

6. A method for increasing the reading speed of holograms in cross-shift multiplexing,

the method of reproducing a recorded hologram at any recording position on the storage medium by linear shift multiplexing and changing the incident direction of the reference light on the storage medium using the same one of the reference lights as in any one of claims 1, 2, and 3, comprising the steps of:

r1: the optical head outputs a beam of specific reference light to irradiate the recording position of the hologram in the storage medium to read the hologram;

r2: moving the optical disc to make the optical head align with all the holograms recorded in the shift multiplexing mode in turn to perform shift multiplexing reading of the whole storage medium;

r3: rotating the optical head to change the incident direction of the reference light, repeating the steps R1-R2, reading the holograms with different grating vector directions on the whole storage medium, and realizing the cross multiplexing reading of the holograms;

r4: and repeating the step R3 to complete the cross-shift multiplexing reading on the whole storage medium.

7. A method for increasing the reading speed of holograms in cross-shift multiplexing,

a method for reproducing a recorded hologram at any recording position on said storage medium by receiving reproduction light of other emission directions by linear shift multiplexing and rotating a reading device using a beam of reference light identical to any one of claims 1, 2, and 4, comprising the steps of:

r1: the optical head outputs a special reference light beam to irradiate a recording position of the hologram in the storage medium, and the hologram is read;

r2: setting a reading device in one direction, moving the optical disk, and making the optical head align with all the holograms recorded in the shift multiplexing mode in turn to carry out the shift multiplexing reading of the whole storage medium;

r3: rotating the reading device to receive the reproduction light in other emergent directions, repeating the steps R1-R2, reading the holograms with different grating vector directions on the whole storage medium, and realizing the cross multiplexing reading of the holograms;

8. A method for increasing the hologram reading speed in cross-shift multiplexing,

the method for reproducing the recorded hologram at any recording position on the storage medium by using a reference beam of light identical to any one of claims 1, 2 and 4, and simultaneously receiving the reproduced light in all the emission directions on the storage medium through linear shift multiplexing and setting a plurality of reading devices, comprises the following steps:

r2: setting reading devices in multiple directions, receiving the reproduction light of multiple crossed holographic gratings, and reading parallel data;

r3: moving the optical disk to make the optical head align with all the holograms recorded in the shift multiplexing mode in turn to carry out the shift multiplexing reading of the whole storage medium;

r4: repeating step R3 completes the cross-shift multiplexing read on the entire storage medium.

9. A method for increasing the reading speed of holograms in cross-shift multiplexing as claimed in claims 6-8, characterized in that moving the optical disc in step R2 so that the optical head is sequentially aligned with all holograms recorded in shift multiplexing for shift multiplexing reading of the entire storage medium comprises:

when the storage medium is circular, the storage medium is made to translate along the radial direction to perform displacement multiplexing reading in the radial direction, then the storage medium is rotated by a certain angle around the center of a circle and then translated along the radial direction to perform displacement multiplexing reading in the other radial direction;

when the storage medium is circular, firstly rotating the storage medium around the center of a circle to perform shift multiplexing reading on the circular optical channel, then radially moving the storage medium for a distance, and then rotating the storage medium around the center of a circle to perform shift multiplexing reading on the other circular optical channel;

when the storage medium is rectangular, the storage medium is translated along the first edge direction to perform shift multiplexing reading on the track, then the storage medium is returned to the original position and moved for a distance along the second edge direction, and then the storage medium is translated along the first edge direction to perform shift multiplexing reading on the other track.

10. A recording and reproducing apparatus for increasing a hologram recording speed in cross-shift multiplexing includes a light source, a reference light path, a signal light path, a reading device, and a medium stage;

the light source is divided into two beams, wherein reference light which is transmitted to the storage medium through the reference light path and does not carry data information is adopted, and signal light which is transmitted through the signal light path and carries data information is adopted;

the reference light and the signal light interfere on a storage medium supported by a medium platform, and interference fringes are recorded in the storage medium through exposure to form a hologram; when the reference light irradiates on the position of the storage medium where the hologram is recorded, the signal light carrying the data information can be reproduced; the reading device is used for reading the data information reproduced by the reference light;

the media platform further comprising a media movement device for translating and/or rotating a storage medium supported by the media platform,

the optical axis direction of the incident signal light is perpendicular to the storage medium;

and the reference light objective lens, the half-wave plate and the polarization beam splitting prism in the reference light path are assembled into a whole body which can rotate around the optical axis of the signal light.

11. A recording and reproducing apparatus for increasing a hologram recording speed in cross-shift multiplexing includes a light source, a reference light path, a signal light path, a medium stage, and a reading device;

the reference light and the signal light interfere on a storage medium supported by a medium platform, and interference fringes are recorded in the storage medium through exposure to form a hologram; the signal light carrying data information can be reproduced when the reference light is incident on the storage medium at a position where a hologram is recorded; the reading device is used for reading the data information reproduced by the reference light;

the direction of the optical axis of the incident reference light is vertical to the storage medium;

the half-wave plate, the Fourier lens and the polarization beam splitting prism in the signal light path are assembled into a whole body which can rotate around the optical axis of the reference light.

12. The recording and reproducing apparatus according to claim 11, wherein when the half-wave plate, the fourier lens, and the polarization beam splitting prism in the signal optical path are rotated around the optical axis of the reference light, the reading means are also rotated with the half-wave plate, the fourier lens, and the polarization beam splitting prism in the signal optical path.

13. A recording and reproducing apparatus for increasing a hologram recording speed in cross-shift multiplexing includes a light source, a reference light path, a signal light path, a medium stage, and a reading device;

the reference light and the signal light interfere on a storage medium supported by a medium platform, and interference fringes are recorded in the storage medium through exposure to form a hologram; the signal light carrying data information can be reproduced when the reference light is incident on a position where a hologram is recorded in the storage medium; the reading device is used for reading the data information reproduced by the reference light;

the optical axis directions of the incident signal light and the reference light are not perpendicular to the storage medium;

the half-wave plate, the reflecting prism and the Fourier lens in the signal light path, and the reference light objective lens and the polarization beam splitting prism in the reference light path are assembled into a whole body which can rotate around an axis vertical to the direction of the storage medium.

14. The recording and reproducing device as set forth in claim 13, wherein said reading device is rotated with the half-wave plate, the reflecting prism and the fourier lens in said signal optical path when the half-wave plate, the reflecting prism and the fourier lens in said signal optical path are rotated about an axis perpendicular to the direction of the storage medium.

15. The recording and reproducing device according to any one of claims 10 to 14, wherein said reference optical path shares an optical path with said signal optical path, the shared optical path including: the tunable semiconductor laser comprises a tunable semiconductor laser, a plurality of reflectors, a deformable prism, an optical isolator, a plurality of half-wave plates, an acousto-optic modulator, a beam expander, a polarization beam splitter prism, a plurality of Fourier lenses and a Nyquist aperture.