CN109712649B - Holographic storage system and manufacturing method thereof - Google Patents
Holographic storage system and manufacturing method thereof Download PDFInfo
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- CN109712649B CN109712649B CN201711012634.9A CN201711012634A CN109712649B CN 109712649 B CN109712649 B CN 109712649B CN 201711012634 A CN201711012634 A CN 201711012634A CN 109712649 B CN109712649 B CN 109712649B
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Abstract
A storage disk, a holographic storage system, and a method for manufacturing the same. The holographic storage system comprises a holographic light source module, a storage disc, a light guide module, a detector and a calculator. The holographic light source module is at least used for providing servo reading light. The light guide module is used for receiving the servo reading light provided by the holographic light source module and guiding the servo reading light to the storage disc, wherein when the servo reading light is guided to the storage disc, the servo reading light is diffracted on the storage disc and becomes servo diffracted light leaving from the storage disc. The detector is used to receive the servo diffracted light exiting from the storage disk. The calculator is electrically connected to the detector and is used for calculating the offset of the storage disk in a first direction through at least one image formed by the servo diffracted light, wherein the first direction is parallel to the Bragg degeneracy direction of the servo reading light. After calculating the offset of the storage disk, the reading state of the servo reading light can be adjusted to more accurately read the information of the storage disk.
Description
Technical Field
The invention relates to a storage disc (storage disk), a holographic storage system (holographic storage system) and a manufacturing method thereof.
Background
With the development of science and technology, the required storage amount of electronic documents is also increasing. A common storage method is to record magnetic or optical changes on the surface of a storage medium, such as a magnetic disc or an optical disc, as the basis of the stored data. However, as the required storage volume of electronic documents increases, the technical development of holographic storage has begun to be highlighted.
The holographic storage technique is to write image data into a storage medium (photosensitive material) after interference is generated between signal light and reference light. When reading data, image data can be generated by re-irradiating the reference light onto the storage medium (photosensitive material). Then, the generated image data is read by the detector. However, during reading, the disc accommodating the storage medium (photosensitive material) may be shifted, so that the reading result will be distorted.
Disclosure of Invention
The holographic storage system comprises a holographic light source module, a storage disk, a light guide module, a detector and a calculator, wherein the holographic light source module can provide servo reading light to the light guide module and emit the servo reading light into the storage disk through the guidance of the light guide module. The servo reading light is diffracted in the storage disc to become servo diffracted light and carry the alignment information of the storage disc. Then, the servo diffracted light is guided by the light guide module and received by the detector, and an image with the alignment point is formed. The calculator is used for calculating the offset of the storage disk in the Bragg degeneracy direction of the servo reading light through the alignment point of the image. After calculating the offset of the storage disk, the reading state of the servo reading light can be adjusted to more accurately read the information of the storage disk.
An embodiment of the present invention provides a holographic storage system, which includes a holographic light source module, a storage disk, a light guide module, a detector and a calculator. The holographic light source module is at least used for providing servo reading light. The light guide module is used for receiving the servo reading light provided by the holographic light source module and guiding the servo reading light to the storage disc, wherein when the servo reading light is guided to the storage disc, the servo reading light is diffracted on the storage disc and becomes servo diffracted light leaving from the storage disc. The detector is used to receive the servo diffracted light exiting from the storage disk. The calculator is electrically connected to the detector and is used for calculating the offset of the storage disk in a first direction through at least one image formed by the servo diffracted light, wherein the first direction is parallel to the Bragg degeneracy direction of the servo reading light.
In some embodiments, the calculation method of the calculator substantially satisfies the following: y is the offset of the storage disc in the first direction, and x is the offset of at least one pair of points in the image.
In some embodiments, the holographic storage system further comprises a determiner. The determiner is electrically connected to the detector and is used for determining the offset direction of the storage disk through a plurality of images formed by the servo diffracted light in a time interval.
In some embodiments, the holographic light source module is used for providing signal light and reference light, and the storage disc includes a storage layer. The storage layer is used for recording page information generated by interference of the signal light and the reference light, and the servo reading light is diffracted by the storage layer to become servo diffracted light.
In some embodiments, the storage layer has a first area for recording page information generated by interference of the signal light and the reference light, and a second area for diffracting the servo read light into servo diffracted light, wherein the first area covers the second area.
In some embodiments, the first region and the second region of the storage layer comprise the same photosensitive material.
In some embodiments, the storage layer has a grating pattern, and a main direction of a grating vector (grating vector) of the grating pattern is orthogonal to the first direction.
In some embodiments, the holographic storage system and the light guide module together form one of an off-axis (off-axis) system and an on-axis (on-axis) system through the holographic light source module.
In some embodiments, the wavefront form of the servo read light parallel to the bragg degeneracy direction is a spherical wave.
In some embodiments, the wavefront of the servo read beam parallel to the Bragg degeneracy direction has a first curvature r1And a wavefront having a second curvature r orthogonal to its Bragg degeneracy direction2And a first curvature r1>Second curvature r2≧0。
In some embodiments, the holographic storage system further comprises an actuator. The actuator is electrically connected to the calculator and is used for adjusting the state of the servo reading light according to the calculation result of the calculator.
In some embodiments, the holographic storage system further comprises an auxiliary light source module and an auxiliary detector. The auxiliary light source module is used for providing auxiliary servo reading light, wherein the auxiliary servo reading light is guided to the storage disc through the light guide module, and is diffracted on the storage disc to become auxiliary servo diffracted light leaving from the storage disc. The auxiliary detector is used for receiving the auxiliary servo diffracted light and is electrically connected to the calculator, wherein the calculator is used for calculating the Fourier space angle of the servo diffracted light and the auxiliary servo diffracted light and positioning the position of the storage disc according to the calculation result.
In some embodiments, the holographic storage system further comprises an auxiliary light source module and an auxiliary detector. The auxiliary light source module is used for providing auxiliary servo reading light, wherein the auxiliary servo reading light is guided to the storage disc through the light guide module, and is diffracted on the storage disc to become auxiliary servo diffracted light leaving from the storage disc. The auxiliary detector is used to receive the auxiliary servo diffracted light and is electrically connected to the calculator, wherein the calculator is used to calculate the Fourier space angle between the servo diffracted light and the auxiliary servo diffracted light, and position the storage disc according to the calculation result.
An embodiment of the present invention provides a method for manufacturing a holographic storage system, including the following steps. The servo reference light and the servo signal light are irradiated to a storage layer of the storage disc, and interference is generated between the servo reference light and the servo signal light through the servo reference light, so that alignment information is recorded on the storage layer, the alignment information is used for enabling the servo reading light to be diffracted through the storage layer to become servo diffracted light, when the servo diffracted light is received by a detector and becomes an image, the image shows the offset information of the storage disc in a first direction, and the first direction is parallel to the degenerate Bragg direction of the servo reading light. The reference light and the signal light are irradiated to the storage layer, and interference is generated through the reference light and the signal light, so that page information is recorded in the storage layer. Writing the offset calculation formula of the storage disc into the calculator so that the calculator calculates the offset of the storage disc in the first direction through the image.
In some embodiments, the wavefront form of the servo reference light parallel to the bragg degeneracy direction thereof is a spherical wave.
In some embodiments, the wavefront of the servo reference light parallel to its Bragg degeneracy direction has a first curvature r1And a wavefront having a second curvature r orthogonal to its Bragg degeneracy direction2And a first curvature r1>Second curvature r2≧0。
One embodiment of the present invention provides a storage disc, which includes a storage layer. The storage layer has a first area for recording page information generated by interference of the signal light and the reference light, and a second area for diffracting the servo read light through the storage layer into servo diffracted light, wherein when the servo diffracted light is received by the detector and becomes an image, the image shows offset information of the storage disc in a first direction, and the first direction is parallel to a Bragg degeneracy direction of the servo read light.
Drawings
FIG. 1 is a schematic optical path diagram illustrating a holographic storage system according to a first embodiment of the present invention;
FIGS. 2A-2C are side views respectively illustrating a portion of a storage disc being written to according to a certain embodiment of the present invention;
FIG. 2D is a side view of a storage location storing page information and alignment information of a disc according to some embodiments of the present invention;
FIGS. 3A and 3B are schematic diagrams respectively illustrating different images according to some embodiments of the present invention;
FIG. 4 is a diagram illustrating the relationship between the offset of the alignment point and the offset of the storage disc;
FIG. 5 is a schematic diagram illustrating optical paths of a holographic storage system according to a second embodiment of the present invention;
FIG. 6 is a schematic diagram illustrating optical paths of a holographic storage system according to a third embodiment of the present invention.
Detailed Description
While the spirit of the invention will be described in detail and with reference to the drawings, those skilled in the art will understand that various changes and modifications can be made without departing from the spirit and scope of the invention as taught herein.
Fig. 1 is a schematic optical path diagram illustrating a holographic storage system 100A according to a first embodiment of the present invention. As shown in fig. 1, the holographic storage system 100A includes a storage disc 102, a holographic light source module 110, a light guide module 120, a detector 140, and a calculator 150. In addition, the holographic storage system 100A shown in fig. 1 can be regarded as a schematic diagram of aligning the storage disc 102.
The holographic light source module 110 includes a light emitter (not shown) and a Spatial Light Modulator (SLM) 112. The light emitter may be, for example, a laser light source, which emits a light beam toward the spatial light modulator 112, and then the spatial light modulator 112 may modulate the light beam after receiving the light beam from the laser light source, so that the holographic light source module 110 may provide a signal light, a reference light or a servo reading light to the light guide module 120. For example, the holographic light source module 110 shown in fig. 1 provides the servo reading light L to the light guide module 120.
The light guide module 120 includes a first lens 121, a Polarizing Beam Splitter (PBS) 122, a second lens 123, a quarter-wave plate 124, a first objective lens 125, and a third lens 126. Through the lens assembly, the light guide module 120 is configured to receive the light beam provided by the holographic light source module 110 and guide the light beam to the storage disc 102 and the detector 140.
The storage disc 102 includes a storage layer 104 and a reflective layer 105, and the storage layer 104 is stacked on the reflective layer 105. The storage layer 104 may be formed of a photosensitive material and has a grating pattern 106, wherein a main direction of a grating vector (grating vector) of the grating pattern 106 is indicated by a direction K. The reflective layer 105 may be used to reflect the light beam incident on the storage disc 102, and specifically, the light beam incident on the storage disc 102 reflects from the reflective layer 105 and exits the storage disc 102 after passing through the storage layer 104. In addition, the storage layer 104 of the storage disc 102 has the alignment information and the page information recorded therein, and the alignment information and the page information are recorded in the same layer. Specifically, fig. 2A to 2C are schematic side views of the process of writing the bit information and the page information on the storage disc 102 according to some embodiments of the present invention, wherein fig. 2A to 2C are schematic side views respectively illustrating the writing process on the storage disc 102. In order not to unduly complicate the drawings, the storage disc 102 of fig. 2A-2C does not depict the raster pattern 106 of fig. 1.
As shown in fig. 2A, the storage layer 104 of the storage disc 102 is stacked on the reflective layer 105, and the storage layer 104 is in a state where no information is recorded, i.e., no information is recorded by interference generated by the signal light and the reference light.
As shown in FIG. 2B, the servo signal light S1 and the servo reference light R1 are irradiated onto the storage layer 104 of the storage disc 102, so that the servo signal light S1 and the servo reference light R1 interfere with each other in the storage layer 104, thereby recording the alignment information on the storage layer 104. In addition, the wavefront of the servo reference light R1 parallel to the bragg degeneracy direction thereof can be a spherical wave, and the wavefront of the servo reference light R1 parallel to the bragg degeneracy direction thereof has the first curvature R1And a wavefront having a second curvature r orthogonal to its Bragg degeneracy direction2Wherein the first curvature r1>Second curvature r2≧ 0, thereby increasing the tolerance of Bragg matching (Bragg matched). Furthermore, according to the above relation, when the second curvature r is larger than the first curvature r2When the wavefront is zero, the wavefront of the servo reference light R1 orthogonal to the Bragg degeneracy direction is a plane wave.
As shown in fig. 2C, the signal light S2 and the reference light R2 can be irradiated onto the storage layer 104 of the storage disc 102, so that the signal light S2 and the reference light R2 interfere with each other in the storage layer 104, and page information can be recorded in the storage layer 104. In some embodiments, the steps of writing the alignment information and the page information to the storage disc 102 may be performed simultaneously, or the alignment information may be written first and then the page information may be written.
Fig. 2D is a side view of a storage location for storing page information and alignment information of the disc 102 according to some embodiments of the present invention. The storage disc 102 of fig. 2D does not depict the raster pattern 106 of fig. 1 in order not to unduly complicate the drawing. As shown in fig. 2D, the storage layer 104 of the storage disc 102 may have a first area a1 and a second area a 2. The first area a1 is for recording surface information, and the second area a2 is for recording alignment information. The first region a1 and the second region a2 of the storage layer 104 include the same photosensitive material, and the first region a1 covers the second region a2, i.e., the first region a1 and the second region a2 may overlap with each other.
Please return to fig. 1. The detector 140 is disposed such that the light guide module 120 is optically coupled between the storage disc 102 and the detector 140, and is configured to receive the light beam exiting from the storage disc 102, and the detector 140 can form a corresponding image through the received light beam. In addition, the detector 140 may be a charge-coupled device (CCD). The calculator 150 is electrically connected to the detector 140 and is used for calculating the offset of the storage disc 102 through the image formed by the detector 140 after receiving the light beam, as will be described in detail below.
After the holographic light source module 110 provides the servo reading light L to the light guide module 120, the first lens 121 of the light guide module 120 may receive the servo reading light L from the holographic light source module 110, and the servo reading light L sequentially passes through the first polarization beam splitter 122, the second lens 123, and the quarter wave plate 124, and then enters the first objective lens 125. The servo read light L may be directed through the first objective lens 125 toward the storage disc 102 and then into the storage disc 102.
After the servo reading light L is guided to enter the storage disc 102 through the first objective lens 125, the servo reading light L diffracts on the storage layer 104 of the storage disc 102 and leaves the storage disc 102 as servo diffracted light D, and the servo diffracted light D at least carries the alignment information recorded on the storage disc 102. In this regard, the Bragg degeneracy direction of the servo read light L is represented by direction B, which is orthogonal to the main direction of the grating vector of the grating pattern 106 (direction K). Note that, although the direction B shown in fig. 1 is a direction pointing into the paper, it may be a direction pointing into the paper.
The servo diffracted light D exiting from the storage disc 102 may enter the light guide module 120, be guided by the first objective lens 125 through the first PBS 122 to the third lens 126, and then enter the detector 140. When the detector 140 receives the servo diffracted light D, the servo diffracted light D may be correspondingly imaged as shown in fig. 3A or fig. 3B, wherein fig. 3A and fig. 3B are schematic diagrams respectively illustrating different images 160A and 160B according to the first embodiment of the invention.
In fig. 3A and 3B, the images 160A and 160B are respectively viewed as single page images. For convenience of description, the images 160A and 160B are represented by 30 × 30 pixels, respectively. By storing the alignment information recorded on the disc 102 (see fig. 1), an alignment point 162 exists in the image 160A, and an alignment point array 164 exists in the image 160B, wherein the alignment point array 164 has a plurality of alignment points 162. In some embodiments, the alignment point 162 can be a focused spot of the servo diffracted light D on the detector 140, and the alignment point array 164 can be a focused spot array of the servo diffracted light D on the detector 140.
Whether the servo diffracted light D forms an image with a single pair of spots (as shown in image 160A of FIG. 3A) or multiple pairs of spots (as shown in image 160B of FIG. 3B), it can represent the alignment information of the storage disc 102 (see FIG. 1). In addition, although not shown, the image 160A of fig. 3A and the image 160B of fig. 3B may also present page information of the storage disc 102 (see fig. 1).
Please return to fig. 1. After the servo diffracted light D forms the image 160A as shown in FIG. 3A or the image 160B as shown in FIG. 3B, the calculator 150 can calculate the offset of the storage disc 102 in the direction B through the alignment point 162 of the image 160A or 160B, i.e. the offset of the storage disc 102 in parallel with the Bragg degeneracy direction of the servo read light L.
Specifically, when the relative position relationship between the servo read beam L and the storage disc 102 changes due to the deviation of the storage disc 102, if the storage disc 102 is deviated along the bragg degeneracy direction parallel to the servo read beam L, the servo read beam L can still diffract within the storage disc 102 because the servo read beam L can satisfy the bragg degeneracy condition. However, since the storage disc 102 is shifted, the position 162 (shown in fig. 3A or fig. 3B) is also shifted accordingly, and therefore, the calculator 150 can calculate the shift amount of the storage disc 102 in the direction B according to the shift amount of the position 162 (shown in fig. 3A or fig. 3B). That is, the holographic storage system 100A can calculate the offset of the storage disc 102 in the direction B through the offset of the received servo diffracted light D.
In some embodiments, the offset of the storage disc 102 may be positively correlated with the offset of the alignment point 162 (shown in fig. 3A or fig. 3B) in the image. For example, the offset of the storage disc 102 and the offset of the alignment point 162 (shown in fig. 3A or fig. 3B) in the image can be proportional, as shown in fig. 4, where fig. 4 is a diagram illustrating the offset of the alignment point and the offset of the storage disc, and the x-axis is the offset of the storage disc and the y-axis is the offset of the alignment point. Since the offset of the storage disc and the offset of the corresponding point in the image are in a direct proportion relationship, the offset of the storage disc can be calculated by the calculator in a way that substantially satisfies the following conditions: and y is k x, wherein y is the offset of the storage disc in the direction B, and x is the offset of the alignment point in the image.
Please return to fig. 1. After the holographic storage system 100A calculates the offset of the storage disc 102 in the direction B through the calculator 150, the position of the storage disc 102 can be corrected, for example, the holographic storage system 100A may include an actuator 152. The actuator 152 is electrically connected to the calculator 150 and is configured to adjust the state of the servo reading light L according to the calculation result of the calculator 150. Specifically, the actuator 152 may be connected to the elements of the holographic light source module 110 or the storage disc 102, and when the storage disc 102 is shifted in the direction B, the actuator 152 may adjust the state of the servo reading light L by correcting the position of the elements of the holographic light source module 110 or the position of the storage disc 102.
On the other hand, to prevent the servo read light L from being diffracted within the storage disc 102, in some embodiments, the wavefront form of the servo read light L parallel to the Bragg degeneracy direction thereof may be a spherical wave, and the wavefront of the servo read light L parallel to the Bragg degeneracy direction thereof has a third curvature r3And the wavefront having a fourth curvature r orthogonal to its Bragg degeneracy direction4Wherein the third curvature r3>Fourth curvature r4≧ 0, to increase the Bragg matching tolerance of the servo read light L to the storage disk 102. Further, according to the above relation, when the third curvature r is larger than the first curvature r3When the wavefront is zero, the wavefront of the servo reading light L orthogonal to the bragg degeneracy direction thereof is a plane wave.
In addition, the holographic storage system 100A may include a determiner 154. The determiner 154 is electrically connected to the detector 140. When the detector 140 receives the servo diffracted light D at a time interval and forms a plurality of images, the determiner 154 can be used to determine the shifting direction of the storage disc 102 according to the plurality of images in a state where the storage disc 102 is continuously shifted. Specifically, the determiner 154 can determine the offset direction of the storage disc 102 according to the moving direction of the alignment point 162 (shown in fig. 3A or fig. 3B) in the image.
Fig. 5 is a schematic optical path diagram illustrating a holographic storage system 100B according to a second embodiment of the present invention. At least one difference between the present embodiment and the first embodiment is that the holographic storage system 100B of the present embodiment is an off-axis (off-axis) system formed by the holographic light source module 110 and the light guide module 120, and the holographic storage system 100A of the first embodiment is an on-axis system formed by the holographic light source module 110 and the light guide module 120. As shown in fig. 5, the light guiding module 120 includes a fourth lens 127, a half-wave plate 128, a second pbs 129, a reflector 130, a third pbs 131, a polarizer 132, a fifth lens 133, and a second objective lens 134.
The holographic light source module 110 may provide the servo reading light L toward the fourth lens 127 of the light guide module 120. The servo read beam L may pass through the half-wave plate 128, the second PBS 129, the mirror 130, the vibrating mirror 132, the fifth lens 133 from the fourth lens 127, and then enter the second lens 134. Through the second objective lens 134, the servo read light L can be directed toward the storage disc 102 and then into the storage disc 102. Then, the servo diffracted light D sequentially passes through the second objective lens 134 and the third PBS 131 from the storage disc 102, and enters the detector 140 after being reflected by the third PBS 131. In the same manner as the first embodiment, after the detector 140 receives the servo diffracted light D and forms an image correspondingly, the calculator 150 can calculate the offset of the storage disc 102 in the direction B, which is not described herein again.
Referring to fig. 6, fig. 6 is a schematic optical path diagram illustrating a holographic storage system 100C according to a third embodiment of the present invention. At least one difference between the present embodiment and the first embodiment is that the holographic storage system 100C of the present embodiment further includes an auxiliary light source module 170 and an auxiliary detector 172, wherein the auxiliary light source module 170 and the auxiliary detector 172 are disposed adjacent to the holographic light source module 110 and the detector 140, respectively. In order not to complicate the drawing, the position of the auxiliary light source module 170 and the auxiliary detector 172 are shown in the same location as the holographic light source module 110 and the detector 140, respectively, in the optical path of the holographic storage system 100C.
The auxiliary light source module 170 is disposed such that the light guide module 120 is optically coupled between the auxiliary light source module 170 and the storage disc 102, and the auxiliary detector 172 is disposed such that the light guide module 120 is optically coupled between the storage disc 102 and the auxiliary detector 172. The auxiliary light source module 170 includes a spatial light modulator 174 and is configured to provide auxiliary servo reading light L ', wherein the auxiliary servo reading light L ' is guided by the light guide module 120 to enter the storage disc 102 and then diffracts on the storage disc 102 to become auxiliary servo diffracted light D ' exiting from the storage disc 102. The auxiliary servo diffracted light D' can enter the auxiliary detector 172 from the light guide module 120. That is, the optical paths of the servo read light L and the assist servo read light L 'and the servo diffracted light D and the assist servo diffracted light D' may be substantially the same.
The assist detector 172 receives assist servo diffracted light D' and is electrically connected to the calculator 150. When the auxiliary detector 172 receives the auxiliary servo diffracted light D ', the auxiliary servo diffracted light D' can be correspondingly imaged. That is, at the same time point, the detector 140 and the auxiliary detector 172 can receive the images formed by the servo diffracted light D and the auxiliary servo diffracted light D', respectively. Then, the calculator 150 is used to calculate the Fourier space angle between the servo diffracted light D and the auxiliary servo diffracted light D', and position the storage disc 102 according to the calculation result.
For example, when the detector used is a four-quadrant photo detector (quad photo detector) or a position detector of a single photodiode (photo diode), rather than a one-dimensional or two-dimensional photo detector, the frequency of the diffracted light spot is higher than the frequency required for actual positioning, and the time sequence of the diffracted light spot is used as a position code. For example, the encoding format may include an encoding start, a position signal, and an encoding end, 111111 is the encoding start, and 0000000000 to 1111111111 may be used as the position signal except 3 consecutive 1 or more or 3 consecutive 0 or more, and the position signal may even use an ECC code, and 000000 is the encoding end. When the detector used is a one-or two-dimensional optical signal detector, the light spot is encoded in the direction of the quadrature bragg degeneracy, which allows spatial encoding to be used, i.e. the manner of encoding is simplified and the start and end of encoding to be removed, compared to the above-described temporal encoding. Further, the calculator 150 can calculate the offset of the storage disc 102 in different directions (the bragg degeneracy direction of the servo read light L and the auxiliary servo read light L ') through the servo read light L and the auxiliary servo read light L', so as to locate the absolute position of the storage disc 102.
In summary, the holographic storage system of the present invention includes a holographic light source module, a storage disc, a light guide module, a detector, and a calculator, wherein the holographic light source can provide servo reading light to the light guide module and emit the servo reading light into the storage disc through the guidance of the light guide module. The servo reading light is diffracted in the storage disc to become servo diffracted light and carry the alignment information of the storage disc. Then, the servo diffracted light is guided by the light guide module and received by the detector, and an image with the alignment point is formed. The calculator is used for calculating the offset of the storage disc in the Bragg degeneracy direction of the servo reading light through the alignment point of the image. After calculating the offset of the storage disk, the reading state of the servo reading light can be adjusted to more accurately read the information of the storage disk.
Although the present invention has been described with reference to the above embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention.
Claims (16)
1. A holographic storage system, comprising:
a holographic light source module at least used for providing a servo reading light;
a storage disc;
a light guide module for receiving the servo reading light provided by the holographic light source module and guiding the servo reading light to the storage disc, wherein when the servo reading light is guided to the storage disc, the servo reading light diffracts on the storage disc and becomes a servo diffracted light leaving from the storage disc;
a detector for receiving the servo diffracted light exiting from the storage disc; and
a calculator electrically connected to the detector, wherein the calculator is used to form an image with at least one pair of points through the servo diffracted light, and the calculator calculates the offset of the storage disc in a first direction through at least one offset of the at least one pair of points on the image, wherein the first direction is parallel to the Bragg degeneracy direction of the servo read light.
2. A holographic storage system according to claim 1, wherein said calculator is configured to calculate in a manner that: y is an offset of the storage disc in the first direction, and x is the at least one offset of the at least one pair of locations in the image.
3. A holographic storage system according to claim 2, further comprising:
a determiner electrically connected to the detector for determining the offset direction of the storage disk through the plurality of images formed by the servo diffracted light in a time interval.
4. The holographic storage system of claim 1, wherein the holographic light source module is configured to provide a signal light and a reference light, and the storage disc comprises a storage layer configured to record page information generated by interference of the signal light and the reference light, and the servo read light is diffracted by the storage layer to become the servo diffracted light.
5. The holographic storage system of claim 4, wherein the storage layer has a first area for recording page information generated by the signal light and the reference light through interference, and a second area for diffracting the servo read light into the servo diffracted light, and the first area covers the second area.
6. The holographic storage system of claim 5, in which the first region and the second region of the storage layer comprise the same photosensitive material.
7. A holographic storage system according to claim 4, in which the storage layer has a grating pattern, and the principal direction of the grating vectors of the grating pattern is orthogonal to the first direction.
8. The holographic storage system of claim 1, wherein the holographic storage system forms one of an off-axis system and an on-axis system through the holographic light source module and the light guide module.
9. The holographic storage system of claim 1, in which the wavefront form of the servo read light parallel to its bragg degeneracy direction is a spherical wave.
10. The holographic storage system of claim 9, in which the wavefront of the servo read light parallel to its bragg degeneracy direction has a first curvature r1And a wavefront having a second curvature r orthogonal to its Bragg degeneracy direction2And a first curvature r1>Second curvature r2≧0。
11. The holographic storage system of claim 1, further comprising:
at least one actuator electrically connected to the calculator for adjusting the state of the servo reading light according to the calculation result of the calculator.
12. The holographic storage system of claim 1, further comprising:
an auxiliary light source module for providing an auxiliary servo reading light, wherein the auxiliary servo reading light is guided to the storage disc through the light guide module, and is diffracted on the storage disc to become an auxiliary servo diffracted light leaving from the storage disc; and
an auxiliary detector for receiving the auxiliary servo diffracted light and electrically connected to the calculator, wherein the calculator is used for calculating the Fourier space angle between the servo diffracted light and the auxiliary servo diffracted light and positioning the position of the storage disc according to the calculation result.
13. A method for making a holographic storage system, comprising:
irradiating a servo reference light and a servo signal light to a storage layer of a storage disc, and generating interference with the servo signal light through the servo reference light, and recording alignment information on the storage layer, the alignment information being used for enabling a servo reading light to be diffracted through the storage layer to become a servo diffracted light, wherein when the servo diffracted light is received by a detector and becomes an image with at least one pair of points, the image shows at least one offset of the at least one pair of points on the image;
irradiating a reference light and a signal light to the storage layer, and generating interference through the reference light and the signal light, so as to record a page information on the storage layer; and
writing an offset calculation formula of the storage disc into a calculator so that the calculator calculates an offset of the storage disc in a first direction through at least one offset of the at least one pair of points on the image, wherein the first direction is parallel to the Bragg degeneracy direction of the servo reading light.
14. The method of claim 13, wherein the offset calculation substantially satisfies the following equation: y is an offset of the storage disc in the first direction, and x is the at least one offset of the at least one pair of locations in the image.
15. The method of claim 13, wherein the wavefront form of the servo reference beam parallel to its bragg degeneracy direction is a spherical wave.
16. The method of claim 15, wherein the wavefront of the servo reference beam has a first curvature r parallel to its bragg degeneracy direction1And a wavefront having a second curvature r orthogonal to its Bragg degeneracy direction2And a first curvature r1>Second curvature r2≧0。
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| Application Number | Priority Date | Filing Date | Title |
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| CN201711012634.9A CN109712649B (en) | 2017-10-26 | 2017-10-26 | Holographic storage system and manufacturing method thereof |
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| CN201711012634.9A CN109712649B (en) | 2017-10-26 | 2017-10-26 | Holographic storage system and manufacturing method thereof |
Publications (2)
| Publication Number | Publication Date |
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