CN1284149C - Polarization orthogonal double-channel holographic optical data storage method and its system - Google Patents
Polarization orthogonal double-channel holographic optical data storage method and its system Download PDFInfo
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Abstract
The present invention relates to a method and a system thereof for storing polarized orthogonal double-channel holographic optical data, which belongs to the field of optical storage. With the characteristic of the noninterference of an orthogonal light field and the inherent bragg selectivity of volume holographic recording, the method and the system of the present invention realize two-channel recording of information which is respectively modulated by an interfering field in the same position of an organic photopolymer recording medium which has the characteristic of isotropy, and the polarization directions of the two light fields of the interfering place are orthogonal. With the inherent bragg selectivity of a volume holographic storage method, the low crosstalk of data pages and the separate reproduction of the data pages are realized. The method and the system which are posed by the present invention enhance the parallelism of the storage process of optical data in multiples; meanwhile, the present invention keeps the parallelism in the reading process of the optical data unchanged, enhances recording rate and simultaneously reduces the asymmetry of the storage rate and the transmission rate of the optical data.
Description
Technical field the present invention relates to a kind of polarized orthogonal binary channels body holographic optics date storage method and system thereof, belongs to area of optical storage.
Background technology body holographic storage technology has storage density height (theoretical 1/ λ
3), memory capacity big (Aprilis company has realized 200GBytes/disk), transfer rate height (Stanford university realizes＞characteristics such as 6Gbits/sec), be a kind of novel page parallel optical memory technology that has potentiality.The storing process of general volume holographic storage method comprises single width storage, multiplexing storage and three processes of data read.Figure 1 shows that modal multiplexing storing process is the process diagrammatic sketch of angular multiplexed volume holographic storage method, specific as follows:
1, utilizes relevant reference light K
R1Thing light K with carrying information
S1In recording medium 7, interfere to form corresponding refractive index phase grating (volume hologram), finish first width of cloth recording of information, shown in Fig. 1-I;
2, with reference light K
R1Deflection one angle constitutes new reference light K
R2, make the volume hologram Prague mismatch of this reference light, thing light K to having write down
S1Direction remains unchanged but loads another information and constitutes new thing light K
S2, reference light K
R2With thing light K
S2In recording medium 7, interfere to form corresponding refractive index phase grating (volume hologram), finish second width of cloth recording of information.Shown in Fig. 1-2;
3, utilize the bragg selectivity of body holography, repetitive process 2 realizes the multiplexing storage of more information page or leaf in storage medium 7;
4, use the reference light K identical with writing down first width of cloth information
R1First width of cloth information record position in the incident recording medium 7 can obtain corresponding thing light K
S1Playback light K
S1_rWith with record second width of cloth information identical reference light K
R2Second width of cloth information record position in the incident recording medium 7 can obtain corresponding thing light K
S2Playback light K
S2_r, respectively shown in Fig. 2-III and Fig. 2-IV.The all available corresponding reference light of arbitrary width of cloth recorded information in the storage medium 7 reproduces separately at corresponding record position.
Volume holographic storage method is in concrete enforcement, the exemplary of the body hologram memory system of the most representative existing employing polymeric disk sheet material is the HDSS (body holographic data storage system) of Stanford university design, Fig. 2 is the main light channel structure figure of this system, horizon light axis wherein and vertical optical axis are only represented the relative position of each element in diagrammatic sketch, do not represent level and vertical on the physical direction in actual applications.System shown in Figure 2 is by being arranged in LASER Light Source 1, half-wave plate 4, pinhole filter 2, collimation lens 3, the polarization splitting prism 5 on the horizon light axis successively and being in reflective spatial light modulator 13, reflective diffuse component 16, fourier transform lens 9 on the vertical optical axis, placing storage medium 7, inverse fourier transform lens 10 and a detector C CD11 on the accurate translation universal stage to constitute, and wherein polarization splitting prism 5 is on the intersection point of horizon light axis and vertical optical axis.During record, the wavelength that LASER Light Source 1 produces is that the laser of 532nm is adjusted into the S polarization through half-wave plate 2 polarization states, after pinhole filter and collimation lens expand bundle, collimation, vertical incidence polarization splitting prism 5, the core of the S polarized light of incident is through reflective spatial light modulator 13 modulation, the picture dot of modulation is the P polarization, and transmission and propagate along the vertical optical axis when the polarization splitting prism 5 again constitutes the required thing light of record; The periphery of the S polarized light of incident polarization Amici prism 5 is after reflective diffuse component 16 and polarization are adjusted to the P polarization, and again by polarization splitting prism 5 transmissions, light beam is propagated along the vertical optical axis, constitutes the required reference light of record.Reflective spatial light modulator 13, fourier transform lens 9, storage medium 7, inverse fourier transform lens 10 and detector C CD11 constitute typical 4F structure, wherein f
1Focal length, f for fourier transform lens 9
2Focal length for inverse fourier transform lens 10.Reference light and thing light are interfered formation refractive index phase grating at the storage medium 7 that places spectrum face position, write down a data page.By the accurate translation and the Spin Control of disc, adopt the relevant multiplexing and multiplexing hybrid multiplex storing process that combines of displacement, be implemented in the high density high capacity storage of whole card.The process that reads is then with thing light light path blocking-up, uses reference light consistent when writing down at corresponding record position reading corresponding data page information.
This system has realized high storage density, memory capacity and transfer rate, but because the body holographic memory is under the identical situation of access procedure concurrency, memory rate is far below the characteristics of transfer rate, structure is stored and read to the single channel that the concurrency of this system is identical, cause the tangible asymmetry of record and transfer rate, recording rate is relatively slow.
Summary of the invention the objective of the invention is to propose a kind of polarized orthogonal binary channels body holographic optics date storage method and system thereof, improve the concurrency of storing process with the polarized orthogonal channel structure, make the concurrency of storing process double, it is constant to keep reading the process concurrency simultaneously, thereby reduce memory rate and transfer rate asymmetry, improve recording rate.
The storage means of the polarized orthogonal binary channels body holographic optics data that the present invention proposes comprises following each step:
(1) is a branch of reference light of S with polarization state and a branch of thing light constitutes the S recording channel, the a branch of reference light and a branch of thing light that are P with polarization state constitute the P recording channel, the recording light of above-mentioned recording channel is at a record position formation interference field of recording medium, with recording optical information;
(2) use in conjunction with hybrid multiplex storing process speckle multiplexed and that displacement is multiplexing, repeating step (1) process is carried out multiplexing storage in the whole recording medium;
(3) with polarization state be a branch of reference light of S, read the optical information of above-mentioned S recording channel in the respective record position by the reference light direction of S recording channel, with polarization state is a branch of reference light of P, reads the optical information of above-mentioned P recording channel in the respective record position by the reference light direction of P recording channel.
Medium in the said method is isotropic photopolymer material.
In the said method two bundle thing light is coaxial, and two bundle reference light symmetries are positioned at thing light both sides, and its angle is φ
c, φ
c＞＞φ, φ=Λ/L is Prague angle selectivity of record, and wherein Λ is the cycle of recorded hologram grating, and 0.1 μ m≤Λ≤10 μ m, L are the thickness of recording medium, 50 μ m≤L≤1000 μ m.
First kind of structure of the storage system of the polarized orthogonal binary channels body holographic optics data that the present invention proposes comprises: LASER Light Source, pinhole filter, collimation lens, first half-wave plate, first polarization splitting prism, second half-wave plate, second polarization splitting prism, the first transmission-type diffuse component, the first transmission-type spatial light modulator, the 3rd half-wave plate, catoptron, the 3rd polarization splitting prism, the second transmission-type spatial light modulator, the 4th polarization splitting prism, the second transmission-type diffuse component, the combined type shutter, fourier transform lens, recording medium, the inverse fourier transform lens, shutter and detector; Described LASER Light Source, pinhole filter, collimation lens, first half-wave plate, first polarization splitting prism, second half-wave plate, second polarization splitting prism and the first transmission-type diffuse component place primary optic axis, and the light beam of propagating along primary optic axis constitutes reference light C; Described first polarization splitting prism, the 3rd half-wave plate and catoptron place on second optical axis of the first polarization splitting prism reflected light direction, and the primary optic axis and second optical axis are orthogonal, and intersect on first polarization splitting prism; Described catoptron, the 3rd polarization splitting prism, the second transmission-type spatial light modulator and the 4th polarization splitting prism are on the 3rd optical axis, second optical axis and the 3rd optical axis are orthogonal, and intersect on the catoptron, the light formation polarization state of propagating along second, third optical axis is the thing light A of P, and reference light C and polarization state are that the thing light A of P constitutes the P recording channel; Described second polarization splitting prism, the first transmission-type spatial light modulator and the 4th polarization splitting prism are in the 4th optical axis, the 4th optical axis and primary optic axis are orthogonal, and intersect on second polarization splitting prism, the 4th optical axis is simultaneously orthogonal with the 3rd optical axis, and intersect on the 4th polarization splitting prism, light beam is propagated along the 3rd optical axis direction behind the 4th polarization splitting prism, and constituting polarization state is the thing light A of S; Described the 3rd polarization splitting prism folded light beam is propagated along the direction that is parallel to the 3rd optical axis after mirror reflects, constitutes reference light B behind the second transmission-type diffuse component, and reference light B and polarization state are that the thing light A of S constitutes the S recording channel; Be provided with combined type shutter, fourier transform lens, recording medium, inverse fourier transform lens and shutter on the optical axis between described the 4th polarization splitting prism and the detector successively; Before the described first transmission-type spatial light modulator and the second transmission-type spatial light modulator all placed fourier transform lens, its distance was the focal distance f of fourier transform lens
1, wherein the first transmission-type spatial light modulator is positioned on the 4th optical axis, and the second transmission-type spatial light modulator is positioned on the 3rd optical axis, and recording medium places on the fourier transform lens back focus; Recording medium also is on the inverse fourier transform lens front focus simultaneously, and detector places on the inverse fourier transform lens back focus, and the angle of reference light C behind fourier transform lens of the reference light B of S recording channel and P recording channel is φ
c
Second kind of structure comprises: LASER Light Source, half-wave plate, pinhole filter, collimation lens, polarization splitting prism, the first combined type shutter, the first reflective diffuse component, first reflective spatial light modulator, the second combined type shutter, the second reflective diffuse component, second reflective spatial light modulator, fourier transform lens, recording medium, inverse fourier transform lens, the 3rd combined type shutter and detector; Described LASER Light Source, half-wave plate, pinhole filter, collimation lens, polarization splitting prism, the first combined type shutter, the first reflective diffuse component, first reflective spatial light modulator are on the primary optic axis line; The described second combined type shutter, polarization splitting prism, the second reflective diffuse component, second reflective spatial light modulator, fourier transform lens, recording medium, inverse fourier transform lens, the 3rd combined type shutter and detector are on second optical axis, and first and second optical axis are orthogonal; Described polarization splitting prism places on the intersection point of first, second optical axis; After the first reflective diffuse component reflection, again through the light of polarization splitting prism reflection back propagation, constitute reference light B, after the reflection of first reflective spatial light modulator, the light formation polarization state of propagating after the polarization splitting prism reflection again is the thing light A of S, and reference light B and polarization state are that the thing light A of S constitutes the S recording channel; After the second reflective diffuse component reflection, the light of after the polarization splitting prism transmission, propagating again, constitute reference light C, after the reflection of second reflective spatial light modulator, it is the thing light A of P that the light of propagating after the polarization splitting prism transmission again constitutes polarization state, and reference light C and polarization state are that the thing light A of P constitutes the P recording channel; Described first reflective spatial light modulator and the first reflective diffuse component are positioned on the primary optic axis, equal the focal distance f of fourier transform lens with the light path of fourier transform lens
1, second reflective spatial light modulator and the second reflective diffuse component are positioned on second optical axis, equal the focal distance f of fourier transform lens with the light path of fourier transform lens
1, recording medium places on the fourier transform lens back focus; Recording medium is on the inverse fourier transform lens front focus simultaneously, and detector places on the inverse fourier transform lens back focus; The angle of reference light C behind fourier transform lens of the reference light B of S recording channel and P recording channel is φ
c
Polarized orthogonal binary channels body holographic optics date storage method and system thereof that the present invention proposes, the characteristics and the intrinsic bragg selectivity of body holographic recording that utilize the quadrature light field not interfere with each other, in the same position of organic photopolymer recording medium with isotropy feature, realize the binary channels record of the information that modulate respectively in the interference place of two light field polarization direction quadratures, and utilize the intrinsic bragg selectivity of volume holographic storage method, realize that low between data page crosstalked and the independent reproduction of data page.The method and system that the present invention proposes has improved the concurrency of optical data storage, make the concurrency of storing process double, the concurrency that keeps optical data to read in the process simultaneously is constant, improve recording rate, reduced the asymmetry of optical storage of data speed and transfer rate simultaneously.It is the laser instrument of 532nm that one embodiment of the present of invention adopt wavelength, has realized the access of the twin-channel data page of polarized orthogonal in thickness is organic photopolymer material of 200um.
Description of drawings
Fig. 1 is existing volume holographic storage method process flow diagram.
Fig. 2 is the body hologram memory system synoptic diagram of existing employing organic polymer disc material.
Fig. 3 is the polarized orthogonal binary channels volume holographic storage method process flow diagram that the present invention proposes.
Fig. 4 is first kind of version utilizing the polarized orthogonal binary channels body hologram memory system of the inventive method design, and spatial light modulator wherein is a transmission-type.
Fig. 5 is second kind of version utilizing the polarized orthogonal binary channels body hologram memory system of the inventive method design, and spatial light modulator wherein is reflective.
Among Fig. 1～Fig. 5, the 1st, LASER Light Source, the 2nd, pinhole filter, the 3rd, collimation lens, 4 is first half-wave plates, 41 is second half-wave plates, 42 is the 3rd half-wave plates, the 5th, polarization splitting prism, 51 is first polarization splitting prisms, 52 is second polarization splitting prisms, and 53 is the 3rd polarization splitting prisms, and 54 is the 4th polarization splitting prisms, the 6th, catoptron, the 7th, storage medium, 81 is first transmission-type diffuse components, 82 is second transmission-type diffuse components, the 9th, fourier transform lens, the 10th, the inverse fourier transform lens, the 11st, detector C CD, 121 is first transmission-type spatial light modulators, 122 is second transmission-type spatial light modulators, the 13rd, reflective spatial light modulator, 131 is first reflective spatial light modulators, 132 is second reflective spatial light modulators, the 14th, shutter, the 15th, the combined type shutter, 151 is first combined type shutters, 152 is second combined type shutters, 153 is the 3rd combined type shutters, the 16th, reflective reflecting element, 161 is first reflective diffuse components, 162 is second reflective diffuse components.
The polarized orthogonal binary channels volume holographic storage method that specific implementation method the present invention proposes, at first be a branch of reference light and a branch of thing light formation S recording channel of S with polarization state, the a branch of reference light and a branch of thing light that are P with polarization state constitute the P recording channel, the recording light of recording channel forms interference field at a record position of recording medium, realizes single binary channels optical information recorder; Utilize hybrid multiplex storing process speckle multiplexed and that displacement is multiplexing, repeat single binary channels optical information recorder process, realize multiplexing storage in the whole recording medium thereafter; Be a branch of reference light of S again with polarization state, read the optical information of above-mentioned S recording channel in the respective record position by the reference light direction of S recording channel, with polarization state is a branch of reference light of P, reads the optical information of above-mentioned P recording channel in the respective record position by the reference light direction of P recording channel.
In the said method two bundle thing light is coaxial, and two bundle reference light symmetries are positioned at thing light both sides, and its angle is φ
c, φ
c＞＞φ, φ=Λ/L, wherein Λ is the cycle of recorded hologram grating, 0.1 μ m≤Λ≤10 μ m, L is the thickness of recording medium, 50 μ m≤L≤1000 μ m.
Medium in the said method is isotropic photopolymer material, for example can use the HRF series holographic storage material of being produced by Dupont company, or the HMD series holographic storage material of producing by Aprilis company etc.
Figure 3 shows that the process flow diagram of the inventive method, recording medium wherein is the photopolymer material of thickness L.Wherein, Fig. 3-I is depicted as single binary channels recording process, and recording channel comprises by with K
SrBe reference light, K
SsFor the S channel of polarization of thing light with K
PrBe reference light, K
PsP channel of polarization for thing light.Two interchannel light field direction of vibration quadratures, according to the pacing items of the interference of light as can be known, two interchannels are not interfered, and interfere record only to take place respectively in S and P passage, separate records when therefore can realize two channel informations.Simultaneously in the binary channels of single shown in Fig. 3-I recording process, the thing light K of two passages
SsAnd K
PsCoaxial, reference light K
SrAnd K
PrBetween angle be φ
cBy in conjunction with hybrid multiplex method speckle multiplexed and that displacement is multiplexing, change the recording medium position, repeat process shown in Fig. 3-I, can realize the information record in the whole recording medium.Read in the process, because above-mentioned φ
cBe far longer than Prague angle selectivity φ of record, therefore satisfy the reference light K of S passage reading conditions
SrTo hologram Prague mismatch of P passage record, can not read the hologram of P passage record; Satisfy the reference light K of P passage reading conditions equally
PrTo hologram Prague mismatch of S passage record, can not read the hologram of S passage record; Thereby can utilize separately channel reference light that respective channel information is realized reading separately.Fig. 3-II is depicted as with the corresponding reference light K of S passage
SrReproduce S channel information K separately at corresponding information record position
S_rProcess, Fig. 3-III is depicted as with S passage corresponding reference light K
PrReproduce P channel information K separately at corresponding information record position
P_rProcess.
Figure 4 shows that first kind of structure of the polarized orthogonal binary channels body holographic optics data-storage system that utilizes the inventive method design, LASER Light Source 1 wherein, pinhole filter 2, collimation lens 3, first half-wave plate 4, first polarization splitting prism 51, second half-wave plate 41, second polarization splitting prism 52 and the first transmission-type diffuse component 81 place primary optic axis, constitute P channel reference light C; Wherein first polarization splitting prism 51, the 3rd half-wave plate 42 and catoptron 6 place on second optical axis of first polarization splitting prism, 51 reflected light directions, and the primary optic axis and second optical axis are orthogonal, and intersect on first polarization splitting prism 51; Wherein catoptron 6, the 3rd polarization splitting prism 53, the second transmission-type spatial light modulator 122 and the 4th polarization splitting prism 54 are on the 3rd optical axis, and second optical axis and the 3rd optical axis are orthogonal, and intersect on the catoptron 6; Wherein second polarization splitting prism 52, the first transmission-type spatial light modulator 121 and the 4th polarization splitting prism 54 are in the 4th optical axis, the 4th optical axis and primary optic axis are orthogonal, and intersect on second polarization splitting prism 52, the 4th optical axis is simultaneously orthogonal with the 3rd optical axis, and intersect on the 4th polarization splitting prism 54, light beam is propagated along the 3rd optical axis direction behind the 4th polarization splitting prism 54, constitutes P and S passage thing light A; The 3rd polarization splitting prism 53 folded light beams are wherein propagated along the direction that is parallel to the 3rd optical axis after mirror reflects, constitute S channel reference light B behind the second transmission-type diffuse component 82; Be provided with combined type shutter 15, fourier transform lens 9, recording medium 7, inverse fourier transform lens 10 and shutter 14 successively on the 4th polarization splitting prism 54 wherein and the optical axis between the detector 11; Wherein the first transmission-type spatial light modulator 121 and the second transmission-type spatial light modulator 122 place on the position of fourier transform lens 9 front focus, and recording medium 7 places on fourier transform lens 9 back focuses, and the focal length of fourier transform lens 9 is f
1Recording medium 7 also is on inverse fourier transform lens 10 front focus simultaneously, and detector 11 places on inverse fourier transform lens 10 back focuses, and the focal length of inverse fourier transform lens 10 is f
2S channel reference light B and the angle of P channel reference light C behind fourier transform lens 9 are φ
c
Describe the principle of work of first kind of structure below in detail.Among Fig. 4, the linearly polarized laser that LASER Light Source 1 is sent provides system required linear polarization directional light behind pinhole filter 2 filtering and collimation lens 3 collimations.The deflection that first half-wave plate 4 is realized linear polarization directional light polarization direction.Parallel beam is by the element group between first half-wave plate 4 and the fourier transform lens 9, realize necessity that record is required light beam deciliter and the loading of information, for holographic memory provides the light field polarized orthogonal but coaxial and be loaded with the thing light of different information and the reference light that symmetry is separated in both sides.Particularly, C is depicted as P channel reference light among Fig. 4, by the light field component of propagating as follows between first half-wave plate 4 and fourier transform lens 9: see through first polarization splitting prism 51, second half-wave plate 41, second polarization splitting prism 52 and the first transmission-type diffuse component 81 in turn and constitute, its polarization state is the P linear polarization.B is depicted as S channel reference light among Fig. 4, by the light field component of between first half-wave plate 4 and fourier transform lens 9, propagating as follows: 51 reflections of first polarization splitting prism, 42 transmissions of the 3rd half-wave plate, see through the second transmission-type diffuse component 82 in turn after catoptron 6, the 3rd polarization splitting prism 53 and catoptron 6 reflections and constitute, its polarization state is the S linear polarization.P channel reference light and S channel reference light are by behind the fourier transform lens 9, and the angle between its light wave is vowed is φ
cAngle φ=Λ/L (wherein Λ is the cycle of recorded hologram grating, and L is the thickness of recording medium) is selected in Prague in each passage storage, to guarantee that channel information can independently read.A is depicted as coaxial S and P passage thing light among Fig. 4, wherein S passage thing light is by the light field component of propagating as follows between first half-wave plate 4 and fourier transform lens 9: see through first polarization splitting prism 5 and second half-wave plate 41 in turn, after 52 reflections of second polarization splitting prism, see through the first transmission-type spatial light modulator, 121 load informations, and then constitute by the reflection of the 4th polarization splitting prism 54, its polarization state is the S linear polarization.P passage thing light is by the light field component of propagating as follows between first half-wave plate 4 and fourier transform lens 9: 51 reflections of first polarization splitting prism, 42 transmissions of the 3rd half-wave plate, catoptron 6 reflections, after 53 transmissions of the 3rd polarization splitting prism, see through the second transmission-type spatial light modulator, 122 load informations, and then seeing through the 4th polarization splitting prism 54 formations, its polarization state is the P linear polarization.The distribution of reference object ratio can realize by rotation first half-wave plate 4, second half-wave plate 41 and the 3rd half-wave plate 42 in interchannel energy distribution and the passage.Combined type shutter 15 is used for the control of light path break-make.In single binary channels storing process, open combined type shutter 15, two channel reference light and pass through fourier transform lens 9 with the thing light that is loaded with different information, near its spectrum face position, write down corresponding hologram with storage medium 7.In reading process, open shutter 14, open the reference path of respective channel, can realize the reproduction of respective channel data in the respective record position by control combination formula shutter 15, the playback light that reads is gathered by detector C CD11 behind inverse fourier transform lens 10, obtains information reproduction.
Figure 5 shows that second kind of structure of the polarized orthogonal binary channels body holographic optics data-storage system that utilizes the inventive method design, LASER Light Source 1 wherein, half-wave plate 4, pinhole filter 2, collimation lens 3, polarization splitting prism 5, the first combined type shutter, 151, the first reflective diffuse component 161, first reflective spatial light modulator 131 are on the primary optic axis line; The second combined type shutter 152 wherein, polarization splitting prism 5, the second reflective diffuse component 162, second reflective spatial light modulator 132, fourier transform lens 9, recording medium 7, inverse fourier transform lens 10, the 3rd combined type shutter 153 and detector 11 are on second optical axis, first and second optical axis are orthogonal, and polarization splitting prism 5 places on the intersection point of first, second optical axis; Wherein first reflective spatial light modulator 131 and the first reflective diffuse component 161 and second reflective spatial light modulator 132 and the second reflective diffuse component 162 all place on the position of fourier transform lens 9 front focus, recording medium 7 places on fourier transform lens 9 back focuses, and the focal length of fourier transform lens 9 is f
1Recording medium 7 also is on inverse fourier transform lens 10 front focus simultaneously, and detector 11 places on inverse fourier transform lens 10 back focuses, and the focal length of inverse fourier transform lens 10 is f
2S channel reference light B and the angle of P channel reference light C behind fourier transform lens 9 are φ
c
Describe the principle of work of second kind of structure below in detail.Among Fig. 5, the linearly polarized laser that LASER Light Source 1 is sent provides system required linear polarization directional light behind half-wave plate 4, pinhole filter 2 filtering and collimation lens 3 collimations.Wherein half-wave plate 4 realizations are used to adjust the distribution of luminous energy between the passage to the deflection of linear polarization directional light polarization direction.Parallel lines polarized light behind collimation lens 3 collimations is behind polarization splitting prism 5, the loading of axle top first reflective spatial light modulator, the 131 modulation realization information of transmitted light (being the P polarization), the polarization state of light of modulated unit is rotated into the S polarization constitutes the S passage through polarization splitting prism 5 reflections thing light simultaneously; The loading of axle top second reflective spatial light modulator, the 132 modulation realization information of reflected light (being the S polarization), the polarization state of light of modulated unit is rotated into the P polarization and sees through the thing light that polarization splitting prism 5 constitutes the P passage simultaneously.S passage thing light and P passage thing light are coaxial, shown in A among the figure.Parallel lines polarized light behind collimation lens 3 collimations is behind polarization splitting prism 5, outside lease making first reflective diffuse component 161 modulation of the axle of transmitted light (being the P polarization), form speckle field, the polarization state of speckle field is rotated into the reference light of S polarization through polarization splitting prism 5 reflection formation S passages simultaneously, shown in B among the figure; Outside lease making second reflective diffuse component 162 modulation of the axle of reflected light (being the S polarization) form speckle field, and the polarization state of speckle field is rotated into the P polarization and sees through the reference light that polarization splitting prism 5 constitutes the P passage simultaneously, shown in C among the figure.Included angle between B and C light beam are vowed by fourier transform lens 9 its light waves of back
cAngle φ=Λ/L (wherein Λ is the cycle of recorded hologram grating, and L is the thickness of recording medium) is selected in Prague in each passage storage, to guarantee that channel information can independently read.The first combined type shutter 151 is used for the control of S passage break-make among Fig. 5, and the second combined type shutter 152 is used for the control of P passage break-make, and the 3rd combined type shutter 153 is used to gather break-make control.In the single binary channels recording process, open the first combined type shutter, 151, the second combined type shutters 152, P, S passage ginseng, thing light are through writing down corresponding hologram with recording medium 7 behind the fourier transform lens 9 near its spectrum face position.Read in the process, open combined type shutter 153, keep gathering unimpeded, open corresponding reference light part in the combined type shutter 151, can read S passage corresponding information in the respective record position, open corresponding reference light part in the combined type shutter 152, can read P passage corresponding information in the respective record position.
Two kinds of structures of the present invention all adopt the multiplexing storage that realizes whole storage medium in conjunction with speckle multiplexed and the multiplexing hybrid multiplex of displacement.Speckle multiplexed speckle field is produced by diffuse component (transmission-type or reflective), and the characteristics that it has the sensitivity selected and has nothing to do with recording medium thickness have many good qualities in the body holographic memory of membrane structure recording medium.Servo the finishing of multiplexing circumferential and axial by disc that be shifted, its multiplexing minimum translocation distance is by speckle multiplexed selectivity decision.In an embodiment of the present invention, be the speckle field of the border circular areas generation of D for the reference light diameter, the multiplexing least displacement that is shifted is δ
r=1.22 λ f/D, and each is to unanimity.Serving as reasons for reference light, yardstick is L on two orthogonal directions
x* L
yThe speckle field that produces of square region, then the multiplexing least displacement of displacement on these two orthogonal directions is respectively δ
x=λ f/L
xAnd δ
y=λ f/L
yUsually the multiplexing least displacement amount of displacement is in micron dimension, for example, as λ=532nm, f=40mm, during D=2.5mm, multiplexing least displacement amount δ ≈ 10um is shifted.In the actual implementation process of system, take all factors into consideration the location and the addressing capability of material property and mechnical servo structure, choose the suitable multiplexing interval that radially and circumferentially is shifted, to obtain higher storage density and capacity.
Claims (5)
1, a kind of storage means of polarized orthogonal binary channels body holographic optics data is characterized in that this method comprises following each step:
(1) is a branch of reference light of S with polarization state and a branch of thing light constitutes the S recording channel, the a branch of reference light and a branch of thing light that are P with polarization state constitute the P recording channel, the recording light of above-mentioned recording channel is at a record position formation interference field of recording medium, with recording optical information;
(2) use in conjunction with hybrid multiplex storing process speckle multiplexed and that displacement is multiplexing, repeating step (1) process is carried out multiplexing storage in the whole recording medium;
(3) with polarization state be a branch of reference light of S, read the optical information of above-mentioned S recording channel in the respective record position by the reference light direction of S recording channel, with polarization state is a branch of reference light of P, reads the optical information of above-mentioned P recording channel in the respective record position by the reference light direction of P recording channel.
2, the method for claim 1 is characterized in that wherein said medium is isotropic photopolymer material.
3, the method for claim 1 is characterized in that wherein said two bundle thing light are coaxial, and two bundle reference light symmetries are positioned at thing light both sides, and its angle is φ
c, φ
c＞＞φ, φ=Λ/L is Prague angle selectivity of record, and wherein Λ is the cycle of recorded hologram grating, and 0.1 μ m≤Λ≤10 μ m, L are the thickness of recording medium, 50 μ m≤L≤1000 μ m.
4, a kind of storage system of polarized orthogonal binary channels body holographic optics data is characterized in that this system comprises: LASER Light Source, pinhole filter, collimation lens, first half-wave plate, first polarization splitting prism, second half-wave plate, second polarization splitting prism, the first transmission-type diffuse component, the first transmission-type spatial light modulator, the 3rd half-wave plate, catoptron, the 3rd polarization splitting prism, the second transmission-type spatial light modulator, the 4th polarization splitting prism, the second transmission-type diffuse component, the combined type shutter, fourier transform lens, recording medium, the inverse fourier transform lens, shutter and detector; Described LASER Light Source, pinhole filter, collimation lens, first half-wave plate, first polarization splitting prism, second half-wave plate, second polarization splitting prism and the first transmission-type diffuse component place primary optic axis, and the light beam of propagating along primary optic axis constitutes reference light C; Described first polarization splitting prism, the 3rd half-wave plate and catoptron place on second optical axis of the first polarization splitting prism reflected light direction, and the primary optic axis and second optical axis are orthogonal, and intersect on first polarization splitting prism; Described catoptron, the 3rd polarization splitting prism, the second transmission-type spatial light modulator and the 4th polarization splitting prism are on the 3rd optical axis, second optical axis and the 3rd optical axis are orthogonal, and intersect on the catoptron, the light formation polarization state of propagating along second, third optical axis is the thing light A of P, and reference light C and polarization state are that the thing light A of P constitutes the P recording channel; Described second polarization splitting prism, the first transmission-type spatial light modulator and the 4th polarization splitting prism are in the 4th optical axis, the 4th optical axis and primary optic axis are orthogonal, and intersect on second polarization splitting prism, the 4th optical axis is simultaneously orthogonal with the 3rd optical axis, and intersect on the 4th polarization splitting prism, light beam is propagated along the 3rd optical axis direction behind the 4th polarization splitting prism, and constituting polarization state is the thing light A of S; Described the 3rd polarization splitting prism folded light beam is propagated along the direction that is parallel to the 3rd optical axis after mirror reflects, constitutes reference light B behind the second transmission-type diffuse component, and reference light B and polarization state are that the thing light A of S constitutes the S recording channel; Be provided with combined type shutter, fourier transform lens, recording medium, inverse fourier transform lens and shutter on the optical axis between described the 4th polarization splitting prism and the detector successively; Before the described first transmission-type spatial light modulator and the second transmission-type spatial light modulator all placed fourier transform lens, its distance was the focal distance f of fourier transform lens
1, wherein the first transmission-type spatial light modulator is positioned on the 4th optical axis, and the second transmission-type spatial light modulator is positioned on the 3rd optical axis, and recording medium places on the fourier transform lens back focus; Recording medium also is on the inverse fourier transform lens front focus simultaneously, and detector places on the inverse fourier transform lens back focus, and the angle of reference light C behind fourier transform lens of the reference light B of S recording channel and P recording channel is φ
c
5, a kind of storage system of polarized orthogonal binary channels body holographic optics data is characterized in that this system comprises: LASER Light Source, half-wave plate, pinhole filter, collimation lens, polarization splitting prism, the first combined type shutter, the first reflective diffuse component, first reflective spatial light modulator, the second combined type shutter, the second reflective diffuse component, second reflective spatial light modulator, fourier transform lens, recording medium, inverse fourier transform lens, the 3rd combined type shutter and detector; Described LASER Light Source, half-wave plate, pinhole filter, collimation lens, polarization splitting prism, the first combined type shutter, the first reflective diffuse component, first reflective spatial light modulator are on the primary optic axis line; The described second combined type shutter, polarization splitting prism, the second reflective diffuse component, second reflective spatial light modulator, fourier transform lens, recording medium, inverse fourier transform lens, the 3rd combined type shutter and detector are on second optical axis, and first and second optical axis are orthogonal; Described polarization splitting prism places on the intersection point of first, second optical axis; After the first reflective diffuse component reflection, again through the light of polarization splitting prism reflection back propagation, constitute reference light B, after the reflection of first reflective spatial light modulator, the light formation polarization state of propagating after the polarization splitting prism reflection again is the thing light A of S, and reference light B and polarization state are that the thing light A of S constitutes the S recording channel; After the second reflective diffuse component reflection, the light of after the polarization splitting prism transmission, propagating again, constitute reference light C, after the reflection of second reflective spatial light modulator, it is the thing light A of P that the light of propagating after the polarization splitting prism transmission again constitutes polarization state, and reference light C and polarization state are that the thing light A of P constitutes the P recording channel; Described first reflective spatial light modulator and the first reflective diffuse component are positioned on the primary optic axis, equal the focal distance f of fourier transform lens with the light path of fourier transform lens
1, second reflective spatial light modulator and the second reflective diffuse component are positioned on second optical axis, equal the focal distance f of fourier transform lens with the light path of fourier transform lens
1, recording medium places on the fourier transform lens back focus; Recording medium is on the inverse fourier transform lens front focus simultaneously, and detector places on the inverse fourier transform lens back focus; The angle of reference light C behind fourier transform lens of the reference light B of S recording channel and P recording channel is φ
c
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| EP3846169A1 (en) * | 2019-12-31 | 2021-07-07 | Amethystum Storage Technology Co., Ltd. | Holographic storage device and method for simultaneously recording and reading on two sides |
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| KR101267310B1 (en) * | 2006-09-08 | 2013-05-23 | 삼성전자주식회사 | Method for improving quality of signals reproduced from a holographic storage medium and apparatus therefor |
| TWI467242B (en) * | 2012-05-29 | 2015-01-01 | Delta Electronics Inc | Projection apparatus for providing multiple viewing angle images |
| CN105486483B (en) * | 2016-01-11 | 2017-11-10 | 北京中科思远光电科技有限公司 | Multi-pulse laser beam combining method based on space-time multiplexing technology |
| CN110992990A (en) * | 2019-10-18 | 2020-04-10 | 北京理工大学深圳研究院 | Diffraction phase type holographic storage device |
| CN112748584B (en) * | 2021-01-19 | 2022-08-23 | 上海理工大学 | Compact vector optical field generator |
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