CN100409331C - Waveguide multilayer optical disk channel tracking method - Google Patents
Waveguide multilayer optical disk channel tracking method Download PDFInfo
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- CN100409331C CN100409331C CNB2006100968431A CN200610096843A CN100409331C CN 100409331 C CN100409331 C CN 100409331C CN B2006100968431 A CNB2006100968431 A CN B2006100968431A CN 200610096843 A CN200610096843 A CN 200610096843A CN 100409331 C CN100409331 C CN 100409331C
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Abstract
A channel tracking method for wave-guide multi-layer CD (Compact Disc) relates to a channel tracking method for optics pick-up equipment of wave-guide multi-layer CD in three-dimensional data storage. Laser enters into some layer of wave-guide multi-layer CD from its side face and a part of conduction light disperses from communication hole on the layer. Co -focal beam path made up of the first and second lens collects tracked channel and dispersion light coming from the left and right channels. Dispersion light passes the first and second apertures and is transformed into first electrical signal S1 and second electrical signal S2 by first and second photoelectric detector. After the first electrical signal S1decreaseing the second electrical signal S2, magnify the result as tracking error control signal of wave-guide multi-layer CD. Dispersion light passes a third aperture and is transformed into ultrawide-band signal by photomultiplier. It is suit for tracking of optics pick-up equipment with east structure.
Description
Technical field
The present invention is specifically related to the channel tracking method of multilayered waveguide read-only optical disc optic pick-up in the three-dimensional data storage device, belongs to the optical information technical field of memory.
Background technology
Traditional optical disc storage improves packing density by wavelength that reduces recording laser and the numerical aperture that increases object lens, and present optical disc storage surface density is near the spatial resolution limit that is caused by the electromagnetic wave diffraction effect.Therefore, super-high density optical storage technology of future generation might be based upon on the three-dimensional optical memory technology that breaks through the plane restriction.As a kind of accurate three-dimensional optical storage means, the loyal seminar of calendar year 2001 China Nanjing Normal University beam proposes a kind of multilayered waveguide optical storage technology (Zhongcheng Liang based on new principle, Tao Yang, HaiMing, Jianping Xie, A novel 3D multilayered waveguide memory.Proc.SPIEVol.4930, pp.134-137,2002; Chinese invention patent: ZL02138417.7; ZL02138418.5).The multilayered waveguide storer is formed by stacking by the multi-disc planar optical waveguide, and its principle and characteristics are to utilize the waveguide imperfection record data, utilizes the light scattering effect sense data of waveguide imperfection, utilizes waveguide that the effect of contraction of light is realized layer addressing and suppressed layer-to-layer signal transfer.
The Waveguide multilayer optical disk that utilizes the multilayered waveguide storage principle to make can make full use of the production technology that has CD now, improves information capacity exponentially, walks to have the optical storage road of independent intellecture property for China and opens up new direction.
The channel tracking technology is one of gordian technique in the optical disc storage system.Multiple factor can make main spot in the information readout, depart from channel, cause reading failure, for example the error that occurs during fabrication of CD channel separation, therefore wow and flutter that CD takes place when rotating or the like must adopt reasonable method to guarantee that main spot remains on the CD channel.Existing channel tracking method comprises flux of light method, process of heterodyning, vibration method or the like, but the brand-new storage principle of multilayered waveguide optical storage system and read characteristic and determined above method not play one's part to the full.
Computer Simulation calculation and the existing experiment carried out according to waveguide theory show: in the multilayered waveguide storage, the scattered light power of single pits is less, and this has higher requirement to signal detection system.Because more weak this problem of tracking signal directly affects feasibility and the practicality that multilayered waveguide is stored this information storage means, for this reason, we have proposed the channel tracking problem that method that a kind of multiple beam recommends solves the Waveguide multilayer optical disk storage system.
Summary of the invention
Technical matters: the objective of the invention is to propose a kind of channel tracking method of Waveguide multilayer optical disk, this method scattered light can make photodetector obtain enough strong tracking error signal and radiofrequency signal by the filtering diaphragm.
Technical scheme: channel tracking method of the present invention is as follows:
This method is coupled into wherein certain one deck with laser through cylindrical mirror from the side of Waveguide multilayer optical disk, the part light conducting will scatter out on this layer pits, the burnt light path of the copolymerization that utilizes first lens, second lens to form collect tracked channel and about the scattered light of two channels; Scattered light passes first diaphragm and second diaphragm, change into the first electric signal S1 and the second electric signal S2 respectively by first photodetector and second photodetector, the first electric signal S1 and the second electric signal S2 subtract each other the back and amplify the tracking error signal that forms Waveguide multilayer optical disk; Scattered light changes into radiofrequency signal by photomultiplier after passing the 3rd diaphragm.First diaphragm, second diaphragm, the 3rd diaphragm all are positioned on the image planes of second lens, and first diaphragm, second diaphragm respectively prop up door screen by three parallel rectangles to be formed, and the 3rd diaphragm is circular; First diaphragm, second diaphragm are that the center is symmetrically distributed with the 3rd diaphragm, the design of each aperture stop size is as follows: establish individual channel behind second lens imaging on image planes width be D, then the 3rd diaphragm diameter is D, and a late width of first diaphragm, second diaphragm also is D, and each late spacing is 2D; Go up a late center line and the 3rd diaphragm centreline space and take over, and following late center line and the 3rd diaphragm centreline space are taken back every 0.5D every 0.5D.
The Waveguide multilayer optical disk structure is as shown in Figure 1: comprise sandwich layer, covering and pits;
Laser is coupled into wherein certain one deck through cylindrical mirror from the side of Waveguide multilayer optical disk, because the refractive index of covering is lower with respect to sandwich layer, this light conducting will be propagated in sandwich layer, and since optical disc surface repressed pits, the part light conducting will scatter out on these pits.
First lens and second lens are formed the burnt light path of copolymerization, are used to collect scattered light.In order to obtain enough strong tracking signal, lens are not merely collected the scattered light of tracked channel, but collect tracked channel and about two scattered lights that channel sends.
First diaphragm, second diaphragm, the 3rd diaphragm are positioned at the image planes of lens, and the 3rd diaphragm is the circular hole diaphragm, are used to pick up radiofrequency signal; First diaphragm, second diaphragm are two groups of diaphragms that work the effect of recommending, and are used to obtain tracking error signal.First diaphragm, second diaphragm are that the center is symmetrically distributed with the 3rd diaphragm.In order to obtain enough strong tracking light, first diaphragm and second diaphragm prop up door screen by three groups to be formed, and a door screen is parallel to each other, and a door screen is corresponding with channel separation at interval, obtains the scattered light that a plurality of channels send.
Be close to photodetector and photomultiplier behind first diaphragm, second diaphragm, the 3rd diaphragm, light signal is converted into electric signal, the hot spot that sees through the 3rd diaphragm forms radiofrequency signal RF through photomultiplier; The hot spot that sees through first diaphragm, second diaphragm forms the tracking error signal electric signal on photodetector.
S1-S2=0 when tracking is correct;
Hot spot omits to the right when inclined to one side, and the S1 signal strengthens, S2 signal weakening, S1-S2＞0;
Hot spot omits left when inclined to one side, and the S2 signal strengthens, S1 signal weakening, S1-S2＜0;
This shows that if the output electric signal of two photodetectors is subtracted each other, its extent is just represented the BEAM SQUINT degree, direction that its positive and negative just expression departs from, Here it is tracking error signal.To control optical pickup apparatus after this error signal processing and amplifying, make whole pick-up do small moving, it just in time is incident upon on the CD channel thereby correct light beam.
Key of the present invention is to propose a kind of channel tracking method of Waveguide multilayer optical disk optic pick-up.The invention main points are: utilize the burnt light path of copolymerization to collect the scattered light of tracked channel of optical disc surface and left and right sides channel thereof, this scattered light can make photodetector obtain enough strong tracking error signal and radiofrequency signal by the filtering diaphragm of particular design.
Beneficial effect: according to above narration as can be known, the present invention has following characteristics:
A kind of channel tracking method of Waveguide multilayer optical disk optic pick-up is proposed.Utilize the burnt light path of copolymerization collect the tracked channel of optical disc surface and about the scattered light of two channels, this scattered light can make photodetector obtain enough strong tracking error signal and radiofrequency signal by the filtering diaphragm of particular design.
Description of drawings
The structural representation of Fig. 1 Waveguide multilayer optical disk.Sandwich layer 101, covering 102, pits 103 are arranged among the figure.
The channel tracking optical system of Fig. 2 Waveguide multilayer optical disk optical pickup.Laser 201 is arranged, cylindrical mirror 202, Waveguide multilayer optical disk 203, pits 204, the first lens 205, the second lens 206, the first diaphragm L1, the second diaphragm L2, the 3rd diaphragm L3, the first photodetector T1, the second photodetector T2 and photomultiplier T3 among the figure.
Fig. 3 diaphragm front elevation.The first diaphragm L1 is arranged among the figure, the second diaphragm L2, the 3rd diaphragm L3, on prop up late L12, following late L22.
The projection of channel hot spot on diaphragm when Fig. 4 (a) tracking is correct,
Fig. 4 (b) follows the tracks of the projection of channel hot spot on diaphragm when taking over,
Fig. 4 (c) follows the tracks of the projection of channel hot spot on diaphragm when taking back,
The device that accompanying drawing comprises has: sandwich layer 101, covering 102, pits 103; Laser 201, cylindrical mirror 202, Waveguide multilayer optical disk 203, pits 204, the first lens 205, the second lens 206, the first diaphragm L1, the second diaphragm L2, the 3rd diaphragm L3, the first photodetector T1, the second photodetector T2 and photomultiplier T3; Go up a late L12, following late L22.
Embodiment
The channel tracking method of Waveguide multilayer optical disk optic pick-up of the present invention:
Laser 201 is coupled into certain one deck wherein from Waveguide multilayer optical disk 202 sides, because the refractive index of covering is lower with respect to sandwich layer, this light conducting will be propagated in sandwich layer, and since optical disc surface repressed pits, the part light conducting will scatter out on these pits.
Three diaphragm L1, L2, L3 all are positioned on the image planes of second lens 202, L1 wherein, and each props up L2 door screen by three parallel rectangles and forms, and L3 is a circular iris.L1, L2 are that the center is symmetrically distributed with L3, and each aperture stop size design is as follows: establish individual channel through behind the lens imaging on image planes width be D, then the L3 diameter is D, L1, the late width of L2 also is D, each late spacing is 2D; Go up a late L11 center line and L3 centreline space and take over, and following late L12 center line and L3 centreline space are taken back every 0.5D every 0.5D.Be close to the first photodetector T1 and the second photodetector T2 and photomultiplier T3 behind the diaphragm, light signal is converted into electric signal, the hot spot that sees through the 3rd diaphragm L3 is the main beam of pickoff signals, forms radiofrequency signal RF on photomultiplier; See through two diaphragm L1, the hot spot of L2 is at T1, and the last formation of T2 follows track error signal S1, S2.
S1-S2=0 when tracking is correct;
Hot spot omits to the right when inclined to one side, and the S1 signal strengthens, S2 signal weakening, S1-S2＞0;
Hot spot omits left when inclined to one side, and the S2 signal strengthens, S1 signal weakening, S1-S2＜0;
This shows that if the output of two tracking photoelectric tubes is subtracted each other, its extent is just represented the BEAM SQUINT degree, direction that its positive and negative just expression departs from, Here it is tracking error signal.To remove to control the optical pickup apparatus that is contained in the rotating shaft after this error signal processing and amplifying, make whole pick-up do small moving, it just in time is incident upon on the CD channel thereby correct light beam.
During real work, channel tracking is correct, but because the length of each pits of CD is not necessarily identical, therefore the luminous flux by the first diaphragm L1 and the second diaphragm L2 also not necessarily equates, but this can not produce maloperation yet, because S1, the signal of S2 is all changing, and wherein also has information, and subtracting each other the tracking error signal that obtains by them will obtain average weight through low-pass filter, have only when the BEAM SQUINT channel, the low frequency component of tracking photoelectric tube output is changed.
Claims (1)
1. the channel tracking method of a Waveguide multilayer optical disk, it is characterized in that this method is coupled into wherein certain one deck with laser (201) through cylindrical mirror (202) from the side of Waveguide multilayer optical disk (203), the part light conducting will scatter out on this layer pits (204), the burnt light path of the copolymerization that utilizes first lens (205), second lens (206) to form collect tracked channel and about the scattered light of two channels; Scattered light passes first diaphragm (L1) and second diaphragm (L2), change into the first electric signal S1 and the second electric signal S2 respectively by first photodetector (T1) and second photodetector (T2), the first electric signal S1 and the second electric signal S2 subtract each other the back and amplify the tracking error control signal that forms Waveguide multilayer optical disk; Scattered light passes the 3rd diaphragm (L3) back and changes into radiofrequency signal by photomultiplier (T3); First diaphragm (L1), second diaphragm (L2), the 3rd diaphragm (L3) all are positioned on the image planes of second lens (206), and first diaphragm (L1), second diaphragm (L2) respectively prop up door screen by three parallel rectangles to be formed, and the 3rd diaphragm (L3) is circular; First diaphragm (L1), second diaphragm (L2) are that the center is symmetrically distributed with the 3rd diaphragm (L3), the design of each aperture stop size is as follows: establish individual channel after second lens (206) imaging on image planes width be D, then the 3rd diaphragm (L3) diameter is D, a late width of first diaphragm (L1), second diaphragm (L2) also is D, and each late spacing is 2D; Go up door screen (L12) center line and take over every 0.5D, and following late (L22) center line and the 3rd diaphragm (L3) centreline space are taken back every 0.5D with the 3rd diaphragm (L3) centreline space.
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| CNB2006100968431A CN100409331C (en) | 2006-10-20 | 2006-10-20 | Waveguide multilayer optical disk channel tracking method |
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| CNB2006100968431A CN100409331C (en) | 2006-10-20 | 2006-10-20 | Waveguide multilayer optical disk channel tracking method |
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| CN1932990A CN1932990A (en) | 2007-03-21 |
| CN100409331C true CN100409331C (en) | 2008-08-06 |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH113545A (en) * | 1997-06-12 | 1999-01-06 | Furukawa Electric Co Ltd:The | Optical rom card |
| JP2001325731A (en) * | 2000-05-15 | 2001-11-22 | Nippon Telegr & Teleph Corp <Ntt> | Optical recording medium and its reproducing device |
| CN1412753A (en) * | 2002-10-11 | 2003-04-23 | 南京师范大学 | Laminated light waveguide three-D data memory and single beam recording and reading access method |
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2006
- 2006-10-20 CN CNB2006100968431A patent/CN100409331C/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH113545A (en) * | 1997-06-12 | 1999-01-06 | Furukawa Electric Co Ltd:The | Optical rom card |
| JP2001325731A (en) * | 2000-05-15 | 2001-11-22 | Nippon Telegr & Teleph Corp <Ntt> | Optical recording medium and its reproducing device |
| CN1412753A (en) * | 2002-10-11 | 2003-04-23 | 南京师范大学 | Laminated light waveguide three-D data memory and single beam recording and reading access method |
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| Publication number | Publication date |
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| CN1932990A (en) | 2007-03-21 |
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Granted publication date: 20080806 Termination date: 20131020 |