KR20020077771A - Holographic digital data storage system compatible with a cd/dvd player - Google Patents

Abstract

PURPOSE: A system for saving holographic digital compatible with a CD player and a DVD player is provided to reduce the equipment cost by adding holographic optical elements. CONSTITUTION: A system for saving holographic digital data compatible with a CD player and a DVD player includes a light source(102) generating a reference beam; a holographic optical element(104) recording an interference pattern of the reference beam and a plurality of beams having the specific size, thereby generating a plurality of reproducing beams corresponding to the specific sized beams if the reference beam is irradiated; a beam splitter(106) splitting the reproducing beams into reflecting beams and projecting beams, and using one of reflecting beams and projecting beams as a holographic reference beam; a spatial light modulator(122) modulating one of reflecting beams and projecting beams to correspond to a holographic input signal, thereby generating a holographic signal beam; a media(110) storing an interference pattern of the holographic reference beam and the holographic signal beam, reflecting the holographic reference beam for generating a CD/DVD reflecting beam proceeding the opposite direction of the holographic reference beam; a signal sensing element displaying the holographic reproducing beam and sensing the CD/DVD reflecting beam in case that holographic reference beam is irradiated.

Description

Holographic digital storage system compatible with CD players and DVD players {HOLOGRAPHIC DIGITAL DATA STORAGE SYSTEM COMPATIBLE WITH A CD / DVD PLAYER}

The present invention relates to a holographic digital storage system, and more particularly, to a holographic digital storage system compatible with a CD player and a DVD player.

Recently, holographic digital data storage systems have been actively researched as semiconductor lasers, charge coupled devices (CCDs), liquid crystal displays (LCDs), and the like have been developed. Holographic digital data storage systems have the advantages of large storage capacity and ultra-fast data transfer speed, and are already being used as fingerprint recognition systems for storing and reproducing fingerprints.

Such a holographic digital data storage system interferes with the object light transmitted from the target object and the reference light, and then reacts the interference fringe generated by the interference differently according to the amplitude and phase of the interference fringe. Write to a storage medium such as a crystal. By changing the angle of incidence of the reference light in the holographic digital data storage system, it is possible to realize the three-dimensional image of the object by recording not only the intensity of the object light but also the phase, which is composed of hundreds of pages of binary data. Thousands of holographic digital data may be stored in the same place in the storage medium.

11 illustrates a conventional transmissive holographic digital data storage system. The transmissive holographic digital data storage system comprises a light source 20, a beam expander 21, a beam splitter 22, two reflective mirrors 23, 24 and a spatial light modulator (SLM). : Spatial Light Modulator) 25, Media 26, and CCD 27.

The light source 20 generates an optical signal of a certain wavelength band, such as laser light, required by the holographic, and the optical expander 21 expands the size of the laser light. The optical separator 22 separates the laser light extended through the optical expander 21 into the reference light and the object light, and then transmits the reference light and the object light through different transmission paths.

The reference light is reflected by the reflection mirror 24, and the reflected reference light is transmitted to the media 26. On the other hand, the object light is reflected by the reflection mirror 23, and the reflected object light is transmitted to the spatial light modulator 25. The spatial light modulator 25 modulates the reflected object light in units of one page of the binary data of the contrast made by the pixels according to the input data, and the modulated object light is transmitted to the media 26.

If the data of the reflected object light is provided in units of frames, for example, it is preferable to be modulated in units of frames. When modulating the reflected object light in units of pages, the reflection angle of the reference light reflected by the reflection mirror 24 is changed little by little.

The interference fringes obtained by interfering the reflected reference light and the modulated object light are stored in the media 26, which depends on the data input to the spatial light modulator 25. In other words, the modulated object light incident on the media 26 is modulated in units of pages, and the reflected reference light is reflected at an angle corresponding to the modulated object light. The modulated object light and the reflected reference light cause interference within the media 26. According to the intensity of the interference fringes generated by the interference, a light induction phenomenon occurs inside the media 26, and as a result, the interference fringes are recorded on the media 26.

On the other hand, when only the reference light is irradiated to the media 26 to read the data recorded on the media 26, the reference light is diffracted by the interference fringes inside the media and restored to the checkered pattern composed of the contrast of the original pixel. Then, the restored checkerboard pattern is reflected on the CCD 27 to restore the original data. At this time, the reference light used to read the data recorded on the media 26 should be incident at an angle substantially the same as the reference light used when writing the data to the media 26.

FIG. 12 shows an internal configuration diagram of a conventional CD player or DVD player, in which a CD player or DVD player includes a high frequency superposition module 10, two mirrors 11 and 18, a polarizing prism 12, and a cylinder. It is composed of a radical lens 13, a photodiode 14, a λ / 4 plate 15, a disk 16, an objective lens 17, and the like. Detailed configuration and operation principle of such a CD / DVD player can be easily understood by those skilled in the art, detailed description thereof will be omitted.

However, in such a CD / DVD player and a holographic digital data storage system, as shown in FIGS. 11 and 12, the positions of detectors, for example, photodiodes, etc. are different from each other. There was a problem that mutual compatibility between graphic digital data storage systems is not possible. In other words, the CD / DVD player has a detector in the reflection direction and the holographic digital data storage system has a detector in the transmission direction, so that only one detector can be used for both systems. There was a problem in that different optical systems were used because the difference in the light size used in the player was also large.

Accordingly, the present invention has been made to solve the above-described problem, and using a holographic optical member having a multiplexing method and a plurality of beam sizes and beam aperture numbers produced by each multiplexing method, a CD player and a DVD player It is an object of the present invention to provide a holographic digital data storage system that is compatible with the system.

According to an exemplary embodiment of the present invention, a holographic digital data storage system compatible with a CD player and a DVD player, the light source generating a reference beam; A holographic optical member in which interference patterns of the reference beam and the plurality of specific size beams are recorded so that a plurality of reproduction beams corresponding to the plurality of specific size beams are generated when the reference beam is irradiated; A beam separator that separates the plurality of reproduction beams into a reflection beam and a transmission beam, respectively, wherein any one of the reflection beam and the transmission beam is used as a holographic reference beam; A spatial light modulator for generating a holographic signal beam by modulating any one of the reflected beam and the transmitted beam to correspond to a holographic input signal; Located where the interference pattern of the holographic reference beam and the holographic signal beam is formed, and reflects the holographic reference beam to generate a CD / DVD reflection beam, the path of the CD / DVD reflection beam is the holographic reference Media in the same but opposite direction as the path of the beam; And signal sensing means located on an extension line of the holographic signal beam and located on a path of the CD / DVD reflecting beam.

1 is a configuration diagram of a holographic digital storage system compatible with a CD player and a DVD player according to an embodiment of the present invention;

FIG. 2 illustrates an embodiment of the holographic beam splitter shown in FIG. 1;

3 is a configuration diagram of a holographic digital storage system compatible with a CD player and a DVD player according to another embodiment of the present invention;

FIG. 4 illustrates an embodiment of the holographic polarizing beam splitter shown in FIG. 3;

5 is a configuration diagram of a holographic digital storage system compatible with a CD player and a DVD player according to another embodiment of the present invention;

FIG. 6 illustrates an embodiment of the holographic polarizing beam splitter shown in FIG. 5;

7 is a configuration diagram of a holographic digital storage system compatible with a CD player and a DVD player according to another embodiment of the present invention;

FIG. 8 illustrates an embodiment of the holographic polarizing beam splitter shown in FIG. 7;

9 is a configuration diagram of a holographic digital storage system compatible with a CD player and a DVD player according to another embodiment of the present invention;

FIG. 10 illustrates an embodiment of the holographic optical member shown in FIG. 9;

11 is a block diagram of a conventional holographic digital storage system,

12 is an internal configuration diagram of a conventional CD or DVD player.

<Explanation of symbols for the main parts of the drawings>

102: light source

104: holographic beam splitter

106: beam splitter

108, 124, 126: lens

110: media

112, 120: mirror

114: charge coupled device (CCD)

116: photodiode (PD)

118: shutter

122: spatial light modulator

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

1 is a block diagram of a holographic digital data storage system compatible with a CD player and a DVD player according to an embodiment of the present invention, the light source 102, the holographic beam splitter 104, the beam splitter 106, Three lenses 108, 124, 126, media 110, two mirrors 112, 120, a charge coupled device (CCD) 114, a photodiode PD) 116, shutter 118, and spatial light modulator (SLM) 122.

The light source 102 is an essential component necessary for the recording and reproducing operation of the holographic digital data storage system. For example, a laser laser may be used, and the light source 102 may be most efficiently used for the media 110 for the holographic digital data storage system. It provides light in the wavelength band that can be used. Usable wavelength bands depend on the photo-sensitizer and initiator added to the media 110.

Holographic beam splitter 104 is fabricated using holographic memory material. The beam generated from the light source 102 is used as a reference beam, and when a specific size beam is incident at a predetermined angle with the reference beam, an interference fringe pattern of the reference beam and the specific size beam is recorded in the holographic beam splitter 104. .

2 illustrates one embodiment of a holographic beam splitter 104 fabricated using each multiple principle. For convenience, reference beams B _REF ^CD , B _REF ^DVD , B _REF ^HDDS corresponding to three angles of incidence of the rotatable holographic beam splitter 104 are shown, with each reference beam B _REF ^CD , B _REF ^DVD , B _REF ^HDDS have the same wavelength with only different angles of incidence. Reference beam B _REF ^CD, B _REF ^DVD, B _REF certain size beam corresponding to the ^HDDS B _CD, B _DVD, B _HDDS each of the reference beams B _REF ^CD, B _REF ^DVD, which is incident yirumyeonseo the B _REF ^HDDS and an angle The interference fringe patterns of the reference beams B _REF ^CD , B _REF ^DVD , B _REF ^HDDS and the specific size beams B _CD , B _DVD , B _HDDS are recorded in the holographic memory material by each multiplexing method. Specific size beams The beam size and shape of B _CD , B _DVD and B _HDDS depends on the medium to be recorded. When the respective reference beams B _REF ^CD , B _REF ^DVD and B _REF ^HDDS are incident on the corresponding holographic memory material on which the interference fringe pattern is recorded, the reproduction beam B of each specific size beam B _CD , B _DVD , B _{HDDS CD} ^RE , B _DVD ^RE , B _HDDS ^RE are created. The intensity of the reproduction beam may be expressed as the diffraction efficiency of the interference fringe pattern. In the case of a photopolymer, a diffraction efficiency of nearly 100% can be obtained.

In order to be compatible with a CD / DVD player in a holographic digital data storage system, first, the beam factor B _F of the CD / DVD player must be kept constant. In general, the beam factor of a CD player is 0.5769 μm ⁻¹ and the DVD has a beam factor of 0.9230 μm ⁻¹ . Beam factor (B _F ) is

Where? Is the wavelength of the beam and NA is the numerical aperture. If the wavelength? Varies, the CD / DVD player can be played back by adjusting the numerical aperture NA to keep the beam factor B _F constant. Numerical aperture NA

Where n is the index of refraction of the medium after passing through the lens, and α is the focusing angle with respect to the optical axis of the lens when a beam perpendicular to the lens is focused at the focal point. In other words, sinα is a function of the focal length (F) of the lens and the width (W) of the beam incident on the lens.

to be.

Therefore, the width W of the incident beam is

to be. As a result, by adjusting the width W of the incident beam to adjust N.A., the beam factor is kept constant and the CD / DVD player can be played back.

When using a Nd-YAG laser for a holographic digital data storage system with a wavelength λ of 532 nm, the focal length of the lens is 1 cm, and the beam is delivered into the air, the refractive index n is 1, Since ^CD beam factor B _F B _F and the beam factor of the DVD ^DVD each 0.5769㎛ ^-1, 0.9230㎛ ^-1, width (W _CD / _DVD W) of the beam required by the CD / DVD player, respectively

to be. Therefore, the beam widths (W _CD / W _DVD ) of specific size beams B _CD and B _DVD are 0.64495 cm and 1.12734 cm, respectively.

If a laser for DVD with a wavelength λ of 650 nm is used and the focal length F of the lens is 1 cm, the width of the beam (W _CD / W _DVD ) required for the CD / DVD player is respectively.

to be. Therefore, the beam widths (W _CD / W _DVD ) of specific size beams B _CD and B _DVD are 0.80900 cm and 1.49980 cm, respectively.

By using the holographic beam splitter 104 manufactured as described above, the beam size can be adjusted to be used in the holographic mode and the CD / DVD mode while using the same wavelength.

In the holographic mode, the reference beam B _REF ^HDDS is incident on the holographic beam splitter 104 at a constant angle of incidence. The holographic beam splitter 104 generates a reproduction beam B _HDDS ^RE corresponding to the reference beam B _REF ^HDDS and the specific size beam B _HDDS , and the beam separator 106 separates the reproduction beam B _HDDS ^RE into a reflected beam and a transmission beam. Let's do it. The reflected beam is irradiated onto the media 110 along path A. The shutter 118 on the path A operates to pass the reflective beam only in the recording state in the holographic mode and not to pass the reflective beam in the reproduction state. The reflected beam passing through the shutter 118 is reflected by the mirror 120 and then modulated by the spatial light modulator 122 to correspond to the input signal to become a holographic signal beam. The holographic signal beam is focused on the media 110 by the lens 124.

Meanwhile, the transmission beam is irradiated to the media 110 along the path B as a holographic reference beam, and the lens 108 serves to focus the holographic reference beam. The media 110 records the interference pattern of the holographic reference beam and the holographic signal beam.

By moving the media 110 up and down, the lens 124 (108) is in focus before the beam enters the media 110 or the lenses 124 (108) after the beam has entered the media 110. Can make a focal point. For example, when using shift multiplexing, it is desirable to cause the lens 124, 108 to focus before the beam enters the media 110 in the holographic mode, and in the CD / DVD mode, the beam is focused on the media ( It is desirable to focus the lenses 124 and 108 after entering the 110. If two lenses with different focal lengths are used as necessary, shorter focal lengths are used for HDDS, and longer focal lengths are used for CD / DVD.

In the reproduction state of the holographic mode, the shutter 118 is blocked so that only the transmission beam enters the media 110 through the path B. FIG. Since the transmission beam acts as a holographic reference beam, a reproduction beam of the holographic signal beam is generated in the traveling direction of the holographic signal beam incident on the media 110 in the recording state, and the reproduction beam of the holographic signal beam is a lens ( 126 is focused on and displayed on a charge coupled device (CCD) 114.

The reference beam by the CD / DVD mode, by alone rotate the graphic beam splitter 104 and to the reference beam B _REF ^CD / B _REF ^DVD incident at a constant angle of incidence, the holographic beam splitter 104 B _REF ^CD / B _REF ^DVD The reproduction beams B _CD ^RE / B _DVD ^RE corresponding to are generated. The beam splitter 106 separates the reproduction beams B _CD ^RE / B _DVD ^RE into two beams, a reflection beam and a transmission beam, and the shutter 118 blocks the progress of the reflection beam. The transmission beam enters CD / DVD media 110 via lens 108 via path B. The beam entering the media 110 has already been adjusted with the beam factor B _F. The reproduction beam generated by being reflected by the media 110 travels along path B and is reflected and transmitted again by the beam splitter 106 to form a reflection reproduction beam and a transmission reproduction beam, which is a holographic beam separator 104. The transmitted reproduction beam does not affect the reproduction signal, and only the reflection reproduction beam travels along the path C and is detected by the photodiode 116 or the charge coupled device (CCD) 114.

3 is a holographic digital data storage system 300 compatible with a CD player and a DVD player according to another embodiment of the present invention, the light source 302, λ / 2 plate 303, holographic polarizing beam splitter 304, beam splitter 306, three lenses 308, 324, 326, media 310, two mirrors 312, 320, charge coupled device (CCD) 314, photodiode (PD) 316, shutter 318, beam expander 321, and spatial light modulator (SLM) 322. Compared to FIG. 1, only λ / 2 plate 303, holographic polarization beam splitter 304 and beam expander 321 were added.

[lambda] / 2 plate 303 rotates the polarization direction by the required angle of the linearly polarized beam incident from the light source 302. The beam of rotated linearly polarized state is incident on the holographic polarization beam splitter 304.

The holographic polarizing beam splitter 304 is manufactured using a material having strong birefringence properties such as LiNbO ₃ or BaTiO _3, and the polarizations are different from each other by using a refractive index difference between an ordinary beam and an extraordinary beam. Even if another reference beam is incident, the reproduction beam corresponding to the reference beam is selectively reproduced.

4 illustrates one embodiment of a holographic polarizing beam splitter 304 fabricated using birefringence properties. Suppose you play a CD player and a DVD player using a horizontal / vertical polarization specific size beam B _{CD &} DVD for a CD / DVD. Horizontal / Vertical Polarization Specific Size Beam B for CD / DVD The _{CD & DVD} has the size and shape of the beam used in the CD player or DVD player, respectively. λ / 2 and the horizontal / vertical polarized reference beam B _REF incident from the plate 303, and is also incident yirumyeonseo the horizontal / vertical polarized reference beam B _REF and angle horizontal / vertical polarization certain size beam B _{CD & DVD} for CD / DVD. The interference pattern of the reference beam B _REF and the horizontal / vertical specific size beam B _{CD &} DVD for CD / DVD is recorded in the holographic polarizing beam splitter 304. Irradiated with a horizontal / vertical polarized reference beam B _REF In the playback mode, CD / DVD horizontal / vertical polarization certain size beam B readout beam corresponding to the _{CD & DVD} B _{CD & DVD} ^REF horizontal / vertical polarization incident direction of the extension line of a certain size beam B _{CD & DVD} for Is generated along the way. The reproduction beam B _{CD & DVD} ^REF consists of two horizontal / vertical beams corresponding to the horizontal / vertical polarization specific size beam B _{CD & DVD} .

Since the λ / 2 plate 303 is used to change polarization, no device for moving or rotating the holographic polarization beam splitter 304 is necessary. However, the beam expander 321 is added to change the beam factor of the CD player or the DVD player to the holographic beam factor using only the horizontal / vertical two polarizations.

In the CD / DVD mode, the? / 2 plate 303 is adjusted to change the polarization direction of the beam horizontally or vertically. The horizontal / vertical polarization direction means CD or DVD mode, respectively, and a reproduction beam B _{CD & DVD} ^RE having a corresponding beam size is generated and incident on the beam splitter 306. The beam splitter 306 splits the reproduction beam B _{CD & DVD} ^RE into two beams, the reflected beam and the transmitted beam, and the shutter 318 blocks the progress of the reflected beam. The rest of the process is the same as the CD / DVD mode process of the holographic digital data storage system shown in FIG.

In the holographic mode, the λ / 2 plate 303 is rotated by an arbitrary polarization angle to change the polarization of the beam. The polarization angle may be any angle, and a beam having any polarization angle is incident on the holographic polarization beam splitter 304 as a reference beam. The holographic polarizing beam splitter 304 generates the reproduction beam B _{CD & DVD} ^RE corresponding to the horizontal or vertical component among the reference beam B _REF , and the beam separator 306 separates the reproduction beam into the holographic reference beam and the holographic signal beam. do. The holographic reference beam travels along path B and the holographic signal beam travels along path A to form an interference pattern in media 310. A beam expander 321 is added on path A to adjust the beam size of the holographic signal beam. In the reproduction mode, the shutter 318 is operated so that only the holographic reference beam is incident on the media 310 to generate a holographic reproduction beam corresponding to the holographic signal beam, and the generated holographic reproduction beam is displayed on the CCD 314. do.

5 is a holographic digital data storage system 500 compatible with a CD player and a DVD player according to another embodiment of the present invention, which includes a light source 502, two λ / 2 plates 503, and 532. , Holographic polarization beam splitter 504, beam splitter 506, four lenses 508, 524, 526, 528, media 510, three mirrors 512, 520 530, charge coupled device (CCD) 514, photodiode (PD) 516, shutter 518, and spatial light modulator (SLM) 522. do. In the holographic digital data storage system 500 illustrated in FIG. 5, the optical path of the CD / DVD mode and the optical path of the holographic mode are separated. Compared to FIG. 1, two λ / 2 plates 503 and 532, a holographic polarizing beam splitter 504, a lens 528, and a mirror 530 were added, and the position of the shutter 518 was changed.

[lambda] / 2 plate 503 rotates a beam of linearly polarized light incident from light source 502 by a necessary angle. The beam of rotated linearly polarized state is incident on the holographic polarization beam splitter 504.

The holographic polarizing beam splitter 504 is manufactured using a material having strong birefringence properties such as LiNbO ₃ or BaTiO _3, and the polarizations are mutually different by using the refractive index difference between the normal beam and the extraordinary beam. Even if another reference beam is incident, the reproduction beam corresponding to the reference beam is selectively reproduced.

6 illustrates one embodiment of a holographic polarizing beam splitter 504 fabricated using birefringence characteristics. Horizontal / Vertical Polarization Specific Size Beam B for CD / DVD Plays CD players and DVD players using _{CD & DVD} , and holographic signals are reproduced using Horizontal / Vertical Polarization Specific Size Beams B _HDDSH and B _HDDSV for Holographic. Horizontal / Vertical Polarization Specific Size Beam B for CD / DVD The _{CD & DVD} has the size and shape of the beam used in the CD player or DVD player, respectively. The horizontal / vertical polarization reference beam B _REF is incident from the λ / 2 plate 503, and the horizontal / vertical polarization reference beam B _REF for CD / _{DVD is} also incident at an angle with the horizontal / vertical polarization reference beam B _REF . The horizontal / vertical polarization specific size beams B _HDDSH and B _HDDSV for _holographic are also incident at an angle to each other. In other words, when the horizontal polarization reference beam B _REF having a horizontal component is incident, two horizontal polarization specific size beams B _CD , B _HDDSH having different incidence angles are _recorded in the holographic polarization beam splitter 504, and the vertical polarization reference beam When B _REF is incident two vertically polarized specific size beams B _DVD and B _HDDSV with different angles of incidence are recorded. When the horizontal polarization reference beam B _REF is irradiated in the reproduction mode, two reproduction beams B _DVD ^RE and B _HDDSH ^RE corresponding to the incident direction extension _lines of the two horizontal polarization specific size beams B _CD and B _HDDSH are generated. For convenience of description, horizontal / vertical polarization specific size beams for CD / DVDs B _{CD & DVD} are used for CDs and DVDs respectively, and horizontal / vertical polarization specific size beams for holographics B _HDDSH and B _HDDSV are holographic reference beams and holographic signal beams, respectively. Assume that it is used as

In the CD mode, the λ / 2 plate 503 is adjusted to change the polarization direction of the beam horizontally. When the beam of horizontal polarization is incident on the holographic polarization beam splitter 504, the reproduction beam B _CD ^RE and the holographic reproduction beam B _HDDS ^RE for horizontal polarization are generated and travel in the path B and path C directions. The reproduction beam B _CD ^RE for CD, which proceeds to the path B, enters the media 510 through the shutter 518, the beam splitter 506, and the lens 508, and reproduces the CD for reflection reflected by the media 510. Beam B _CD ^RE is a signal beam for CD that is reflected by beam splitter 506 and then travels along path D and sensed by PD 516 or CCD 514. On the other hand, the reproduction beam B _HDDSH ^RE for holographic, which is a horizontal polarization traveling along the path C, enters the media 510 through the λ / 2 plate 532, the mirror 530, and the lens 530, but the media 510 Is a reflection type in the CD mode, the holographic reproduction beam B _HDDSH ^RE is reflected at an angle equal to the incident angle, and thus does not affect the reproduction of the CD. If necessary, additional shutters can be installed on the path C.

In the DVD mode, the? / 2 plate 503 is adjusted to change the polarization direction of the beam vertically. When the beam of vertical polarization is incident on the holographic polarization beam splitter 504, the reproduction beam B _DVD ^RE for _DVD and the holographic reproduction beam B _HDDSV ^{RE, which} are vertical polarizations, are generated and travel in the path B and path A directions. Graphic reproduction beam alone for reproducing the DVD player using a DVD reproducing beam B _DVD ^RE for proceeding to the path B, but goes to the path A B _HDDSV ^RE is reflected by the media 510 does not affect the DVD signal .

In holographic mode, the lambda / 2 plate 503 is adjusted such that the reference beam has a horizontal component and a vertical component. The holographic polarizing beam splitter 504 produces a reproduction beam in three directions. However, since the shutter 518 is operated, the beam does not proceed to the path B but the beam proceeds to the path A and the path C. The beam that travels along path A is modulated by the holographic signal beam corresponding to the input signal at SLM 522 and enters media 510. The beam propagating in the path C is a holographic reference beam, and the polarization direction is rotated by 90 degrees by the λ / 2 plate 532 to have the same polarization direction as the signal beam propagating in the path A. The interference pattern is recorded in the media 510. In the holographic reproduction mode, the lambda / 2 plate 503 is adjusted with the shutter 518 closed so that only the reference beam of horizontal polarization is incident on the holographic polarization beam splitter 504. Of the horizontally polarized reproduction beams generated by the holographic polarization beam splitter 504, the beam traveling in the path C is rotated by the media 510 by the polarization direction by the λ / 2 plate 532 as a holographic reference beam. Incident. Thus, the holographic reproduction beam travels on the extension of the path A and displayed on the CCD 514.

If necessary, by using each multiplexing technique, a specific size beam may be input to the holographic polarization beam splitter 504 while varying the angle of incidence of the reference beam in the CD / DVD mode and the holography mode. When recording the interference pattern with a specific size beam while rotating the holographic polarization beam splitter 504, the λ / 2 plate 503 shown in FIG. 5 is removed, and the position of the shutter 518 is moved to the path A. When the shutter 518 on the path A is closed except for the recording mode in the holographic mode, the holographic digital data storage system as shown in FIG.

7 is a holographic digital data storage system 700 compatible with a CD player and a DVD player according to another embodiment of the present invention, which includes a light source 702, two λ / 2 plates 703, and 732. , Holographic polarization beam splitter 704, beam splitter 706, four lenses 708, 724, 726, 728, media 710, three mirrors 712, 720 730, charge coupled device (CCD) 714, photodiode PD 716, shutter 718, spatial light modulator SLM 722, polarization Beam splitter 734. In the holographic digital data storage system 700 illustrated in FIG. 7, the optical path of the CD / DVD mode and the optical path of the holographic mode are separated. Compared to FIG. 1, a polarizing beam splitter 734 was added in addition to two λ / 2 plates 703, 732, a holographic polarizing beam splitter 704, a lens 728, and a mirror 730, and a shutter 718. ) Has been changed.

[lambda] / 2 plate 703 rotates a beam of linearly polarized light incident from light source 702 by the required polarization angle. The beam of rotated linearly polarized state is incident on the holographic polarization beam splitter 704.

The holographic polarizing beam splitter 704 is manufactured using a material having strong birefringence properties such as LiNbO ₃ or BaTiO ₃ . 8 illustrates one embodiment of a holographic polarizing beam splitter 704 fabricated using birefringence characteristics. Horizontal / Vertical Polarization for CD / DVD Specific size beam B _Plays CD players and DVD players using _{CD & DVD} and holographic signals using specific size beam B _HDDS for holographic. Horizontal / Vertical Polarization Specific Size Beam B for CD / DVDs Specific Size Beam B _HDDS for _{CD & DVD} and Holographic are incident at a certain angle. Horizontal / Vertical Polarization Specific Size Beam B for CD / DVD The _{CD & DVD} has the size and shape of the beam used in the CD player or DVD player, respectively. The holographic specific sized beam is preferably incident with a polarization angle of 45 degrees. For convenience of description, the horizontal / vertical polarization specific size beam B _{CD & DVD} for CD / DVD is used for CD and DVD, respectively, and the holographic specific size beam B _{HDDS which} is incident on the polarization light separator 734 at 45 degree polarization angle is horizontal and vertical. It is assumed that the beam of vertically polarized light is transmitted and the beam of vertically polarized light is reflected.

In the CD mode, the λ / 2 plate 703 is adjusted to change the polarization direction of the beam horizontally. When the beam of horizontal polarization is incident on the holographic polarization beam splitter 704, a horizontal polarization component is generated among the reproduction beam B _CD ^RE and the holographic reproduction beam B _HDDS ^RE for horizontal polarization. The reproduction beam for CD is sensed by PD 716 or CCD 714 via path B and path D as described above with reference to FIG. The horizontal polarization component of the holographic reproduction beam B _HDDS ^RE passes through the polarization beam splitter 734 and then moves along the path C to be reflected by the media 710 but does not affect the reproduction of the CD. When the beam intensity of the holographic reproduction beam B _HDDS ^RE is strong to affect reproduction, a shutter may be placed between the holographic polarization beam splitter 704 and the polarization beam splitter 734.

In the DVD mode, the λ / 2 plate 703 is used to return the polarization direction to the vertical direction, and the play beam B _DVD ^RE for DVD, which is vertically polarized, is detected via path B and path D as in CD, but the holographic The vertically polarized component of the dragon play beam B _HDDS ^RE is reflected by the polarization beam splitter 734 and travels to the path A while not affecting DVD playback.

In the holographic recording mode, the lambda / 2 plate 703 is adjusted to an arbitrary angle. The beam used in the CD / DVD player is blocked by the shutter 718 on path B, and only the holographic beam is separated by the polarizing beam splitter 734 into a horizontal polarizing beam and a vertical polarizing beam. The horizontally polarized beam passes through the polarization beam splitter 734 and is then converted into vertically polarized light by the λ / 2 plate 732 and is incident on the media 710 along the path C as a holographic reference beam. The vertically polarized beam is reflected by polarization beam splitter 734 and then modulated by spatial light modulator 722 and incident on media 710 along path A as a holographic signal beam. In the holographic reproduction mode, the? / 2 plate 703 is adjusted so that only the beam of the horizontal component is incident on the holographic polarization beam splitter 704. The shutter 718 is blocked to prevent the beam from traveling along path B, and the beam transmitted through the polarization beam splitter 734 and the λ / 2 plate 732 is incident on the media 710 as a holographic reference beam. The holographic reproduction beam is then displayed on the CCD 714 via the lens 726.

9 is a holographic digital data storage system 900 compatible with a CD player and a DVD player according to another embodiment of the present invention, which includes a light source 902, two beam splitters 905, 906, and three. Mirrors 907, 912, 920, holographic optical element (HOE) lens 909, media 910, charge coupled device (CCD) 914, photo It consists of a diode (PD) 916, a shutter 918, a beam expander 921, a spatial light modulator (SLM) 922, two lenses 924, and 926. The holographic digital data storage system 900 shown in FIG. 9 records the numerical apertures for CD / DVD and holographic by using the spatial multiplexing method or each multiplexing method on the HOE lens 909. The HOE lens 909 can obtain diffraction efficiency close to 100% using a photopolymer.

10 illustrates an embodiment of a HOE lens 909 manufactured using a spatial multiplexing method. Corresponding to the reference beam indicated by the thick solid line, the beam having a specific numerical aperture for CD / DVD and the beam having a specific numerical aperture for holographic are sequentially incident. It is desirable to use three different lenses 911 to obtain beams with three different numerical apertures. For convenience of explanation, it is assumed that the HOE lens 909 is manufactured so as to have the numerical aperture for the CD in the first position, the numerical aperture for the DVD in the second position, and the numerical aperture for the holographic in the third position.

The beam generated at the light source 902 is divided by the beam splitter 905 into a transmission beam and a reflection beam. The transmitted beam is reflected by the mirror 907 and then transmitted through the beam splitter 906 and irradiated to the HOE lens 909 as a reference beam. As the HOE lens 909 moves to a position corresponding to the CD / DVD mode or the holographic mode, a specific numerical aperture beam corresponding to each mode is irradiated onto the media 910 along the path B. As shown in FIG. The reflected beam, on the other hand, travels along path A. Specifically, the reflected beam passes through the shutter 918 and then passes through a beam expander 921 that expands the size of the beam to correspond to the holographic beam, and after being reflected by the mirror 920, the spatial light modulator 922. Is irradiated to the media 910 via the lens 924 as a holographic signal beam.

In the CD mode, the beam travels along the path B by blocking the shutter 918. The HOE lens 909 moves to the first position such that a beam having the numerical aperture required by the CD player is incident on the media 910. The beam reflected by the media 910 again acts as a reference beam to the HOE lens 909 to produce a beam having the same angle and opposite direction as the incident beam, and the generated beam is a beam splitter 906. ) Is reflected. The beam reflected by the beam splitter is sensed by the PD 916 or CCD 914. In the DVD mode, the HOE lens 909 may be moved to the second position.

In the holographic recording mode, the shutter 918 is opened and the HOE lens 909 also moves to the third position. The beam traveling to path B acts as a holographic reference beam and the beam traveling to path A acts as a holographic signal beam. In the holographic playback mode, the shutter 918 is blocked and the HOE lens 909 moves to the third position so that only the holographic reference beam is incident on the media 910, thereby holographic reproduction corresponding to the holographic reference beam. The beam is displayed on the CCD 914 on the extension of the holographic signal beam.

If necessary, the signal beam may be controlled using a polarizer and a wave plate instead of the shutter 918, or a wave plate may be placed before and after the HOE lens 909 to adjust the intensity of the detected beam.

Accordingly, the present invention further configures a holographic optical member such as a holographic beam splitter, a holographic polarizing beam splitter, or a holographic optical member lens to enable mutual compatibility of a CD / DVD player and a holographic digital data storage system. In addition, the cost of purchasing the equipment can be reduced.

Claims (13)

A holographic digital data storage system compatible with a CD player and a DVD player, A light source for generating a reference beam; A holographic optical member in which interference patterns of the reference beam and the plurality of specific size beams are recorded so that a plurality of reproduction beams corresponding to the plurality of specific size beams are generated when the reference beam is irradiated; A beam splitter for separating the plurality of reproduction beams into a reflection beam and a transmission beam, respectively, wherein any one of the reflection beam and the transmission beam is used as a holographic reference beam; A spatial light modulator for generating a holographic signal beam by modulating any one of the reflected beam and the transmitted beam to correspond to a holographic input signal; The interference pattern of the holographic reference beam and the holographic signal beam is stored, and the holographic reference beam is reflected to generate a CD / DVD reflection beam, wherein the CD / DVD reflection beam is opposite to the holographic reference beam. Media to follow along; And A holographic compatible with a CD player and a DVD player including a signal sensing means for displaying a holographic reproduction beam for the holographic signal beam and detecting the CD / DVD reflection beam when the holographic reference beam is irradiated Digital data storage system. The holographic digital data storage system compatible with a CD player and a DVD player according to claim 1, wherein the holographic optical member records the plurality of interference patterns by each multiplexing method. The CD of claim 2, wherein the plurality of interference patterns comprises an interference pattern between the reference beam and a specific size beam for CD / DVD and an interference pattern between the reference beam and the holographic specific size beam. Holographic digital data storage system compatible with players and DVD players The method of claim 1, wherein the holographic optical member is: Means for adjusting a polarization direction of the reference beam to generate a plurality of polarization beams; And A holographic polarization beam splitter for recording an interference pattern between the plurality of polarization beams and the plurality of specific sized beams corresponding to the plurality of polarization beams to produce the plurality of reproduction beams corresponding to the plurality of polarization beams A holographic digital data storage system compatible with a CD player and a DVD player, characterized in that it comprises a. 10. The holographic digital data storage system of claim 1, further comprising a beam expander for adjusting the size of the holographic signal beam. 2. The CD and DVD player of claim 1, wherein the reflected beam is modulated by the spatial light modulator to be the holographic signal beam, and the transmitted beam is the holographic reference beam. Holographic digital data storage system. 7. The holographic digital data storage system of claim 6, wherein the CD / DVD reflecting beam is focused by the signal sensing means after being reflected by the beam splitter. A holographic digital data storage system compatible with a CD player and a DVD player, A light source for generating a reference beam; First polarization adjusting means for adjusting a polarization direction of the reference beam to generate a plurality of polarization beams having a plurality of polarization components; Record an interference pattern between the plurality of polarization beams and a specific size beam for CD / DVD and an interference pattern between the plurality of polarization beams and a specific size beam for holographic, respectively, wherein the specific size beam for holographic When the plurality of polarizing beams are irradiated with each other, a polarization component generates a reproduction beam for CD / DVD corresponding to the specific size beam for CD / DVD and a holographic reproduction beam corresponding to the holographic specific size beam. The holographic optical beam may include: a holographic optical member having a plurality of holographic polarization components output through different paths; Second polarization control means for generating first and second holographic beams by matching polarization directions of the holographic reproduction beams, and using any one of the first and second holographic beams as a holographic reference beam; A spatial light modulator for generating a holographic signal beam by modulating another one of said first and second holographic beams to correspond to a holographic input signal; The interference pattern of the holographic reference beam and the holographic signal beam is stored, and the CD / DVD reflection beam is generated by reflecting the CD / DVD reproduction beam, wherein the CD / DVD reflection beam is formed of the CD / DVD reproduction beam. Media running in opposite directions; A signal sensing means for displaying a holographic reproduction beam corresponding to the holographic signal beam and sensing the CD / DVD reflection beam when irradiating the holographic reference beam; And Holographic digital compatible with CD players and DVD players comprising a beam separator for injecting the reproduction beam for CD / DVD into the media and for injecting the reflection beam for CD / DVD reflected by the media into the signal sensing means. Data storage system. 10. The holographic digital data storage system of claim 8, wherein the plurality of polarizing beams comprise horizontal / vertical polarization components. 10. The holographic digital data of claim 9, wherein the plurality of polarizing beams comprise any polarizing beams having an arbitrary phase difference other than the horizontal / vertical polarizing component. Storage system. The method of claim 10, wherein the holographic optical member is: Record an interference pattern between the arbitrary polarization beam and the holographic specific size beam corresponding to the arbitrary polarization beam, and when irradiating the arbitrary polarization beam, the holographic reproduction beam corresponding to the holographic specific size beam A holographic polarizing beam splitter produced; And And a polarization beam splitter for separating the holographic reproduction beam into the plurality of holographic polarization components. 12. A holographic digital data storage system compatible with a CD player and a DVD player. A holographic digital data storage system compatible with a CD player and a DVD player, A light source for generating a reference beam; A first beam splitter for splitting the reference beam into a first beam and a second beam and traveling in different paths; A spatial light modulator for generating a holographic signal beam by modulating the first beam to correspond to a holographic input signal; Recording the interference pattern between the second beam and the specific numerical aperture beam for CD / DVD and the interference pattern between the second beam and the specific numerical aperture beam for holographic, respectively, and irradiating the second beam A reproduction beam for CD / DVD corresponding to a specific numerical aperture beam for DVD and a holographic reproduction beam corresponding to the holographic specific numerical aperture beam, wherein the holographic reproduction beam proceeds as a holographic reference beam Holographic optical members; Record the interference pattern of the holographic reference beam and the holographic signal beam and reflect the CD / DVD playback beam to generate a signal beam for CD / DVD, wherein the CD / DVD reflection beam is the CD / DVD. Media running in the opposite direction of the dragon playback beam; Signal detection means for displaying the holographic signal beam when the holographic reference beam is incident and detecting the reflection beam for the CD / DVD; And A CD generated by the holographic optical member in accordance with the holographic principle, in which the second beam is incident on the holographic optical member, and corresponding to the signal beam for the CD / DVD, located in the path of travel of the second beam A holographic digital data storage system compatible with a CD player and a DVD player comprising a second beam splitter for injecting a signal reproduction beam for DVD / DVD into the signal sensing means. 13. The holographic optical member according to claim 12, wherein the holographic optical member has an interference pattern between the second beam and the specific numerical aperture beam for CD / DVD and the second beam and the specific numerical aperture beam for holographic by a spatial multiplexing method. A holographic digital data storage system compatible with CD and DVD players characterized by recording interference patterns.