CN1078727C - Optical pickup system - Google Patents
Optical pickup system Download PDFInfo
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- CN1078727C CN1078727C CN95105599A CN95105599A CN1078727C CN 1078727 C CN1078727 C CN 1078727C CN 95105599 A CN95105599 A CN 95105599A CN 95105599 A CN95105599 A CN 95105599A CN 1078727 C CN1078727 C CN 1078727C
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- diffraction
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- light source
- holographic disk
- light
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Abstract
The present invention relates to an optical read-out system reproducing information stored in a holographic disk with a pair of reflecting surfaces. The present invention comprises a pair of light sources, a light detecting unit, a diffraction device, a beam splitter arranged between a first detector and the holographic disk, an objective lens arranged between the beam splitter and the holographic disk, and a signal detecting unit for a first and a second signal detecting circuits. When a second light source is used for reproducing an information signal through the second reflecting surface of the holographic disk, a first light source detects the tracking and focusing errors of the first reflecting surface of the holographic disk to replace the errors of the second reflecting surface of the holographic disk. When the first light source is used for detecting a reproducing signal and the focusing error of the first reflecting surface of the holographic disk, the second light source is turned off.
Description
The present invention relates to a kind of optical pickup system, and more specifically, relate to a kind of new optical pickup system, this system can drive a CD with a plurality of reflectings surface.
Be illustrated in figure 1 as an optical pickup system 10 that is reproduced a signal by an information storage district from a conventional optic information recording disc, as laid-open U.S. Patents NO.5,111,449, its exercise question is " use has the optical pick-up device of the defraction grating device of two subregions ", is hereby incorporated by.Optical pickup system 10 comprises a light source 12, one first and one second defraction grating device 14,16, a collimation lens 18, object lens 20, a CD 22 and a photo-detector 24, wherein first diffraction element 14 be installed in photo-detector 24 near, incide on the CD 22 after by the three-beam of its generation by collimation lens 18 and object lens 20.Then, this three-beam reflects and incides on second diffraction element 16 by object lens 20 and collimation lens 18, and this element is installed in the position near CD 22, then by arriving photo-detector 24 behind second diffraction element, 16 diffraction.
One of major defect of above-mentioned optical pickup system 10 is to lack information recording area.In order to overcome this problem, proposed to adopt CD with a plurality of information storage layers.Figure 2 shows that a cut-open view with CD of a pair of reflection hologram film, this CD that is used for an optical pickup system is commonly called a holographic disk, as be disclosed in an exercise question among the unsettled total U.S. Patent application No. 08/340,941 of " CD and job operation thereof " (Optical Diskwith a Reflection Hologram Film and Method of Manufacturing the Same) with a reflection hologram film like that.Holographic disk 30 comprises a substrate 32; one deck first reflection hologram film 34; a transparent intermediate layer 36; one deck second reflection hologram film 38 and a protective clear layer 40, wherein each layer in first and second reflection hologram films can both reflect the light beam of certain wavelength and the light of other wavelength is passed through.As shown in the figure, a branch of from optical pickup system and have wavelength X
1Light beam I arrive first reflection hologram film 34 by protective clear layer 40, second reflection hologram film 38 and transparent intermediate layer 36, and reflected back optics read-out system.On the other hand, a branch of from optical pickup system and have wavelength X
2Light beam II arrive second reflection hologram film 38 by protective clear layer 40, and reflected back optics read-out system, thus compare with the CD that has only this reflection horizon of one deck of routine, the information storage area has increased by one times.
Therefore, a basic purpose of the present invention provides a kind of novel optical read-out system that can operate a holographic disk.
An optical pickup system, be used for reproducing the information signal that is stored on the holographic disk that comprises first and second record surfaces, each record surface has a plurality of along the tangential recording channel that is provided with of holographic disk, comprising: a pair of light source that is used for producing first and second light beams, and each light beam has different wavelength; A diffractive optical element, a rhombic system crystal base that comprises first and second diffraction elements that are positioned at its opposite flank, first diffraction element is provided with a plurality of diffraction grooves, be used for and be divided into three-beam by the light beam that light source sends, and this three-beam is delivered to first and second record surfaces to get on, the radial parallel of the direction of each diffraction groove and holographic disk wherein, radially with tangentially perpendicular, be provided with two diffraction subregions that are divided into by division line radially in second diffraction element, being used for being diffracted into one first detector from the three-beam of first record surface reflection gets on, two diffraction zones have the groove of different pitch, are used for making three-beam along different angle diffraction; A beam splitter, has a reflecting surface, the first bundle light that is used for first light source is sent is delivered on first record surface, and the second bundle light that secondary light source sends is reflexed on second record surface, wherein said diffractive optical element is set between first light source and the beam splitter, and described beam splitter is between diffractive optical element and object lens, and wherein reflecting surface tilts with respect to the optical axis from the light of each record surface reflection, and optical axis perpendicular to holographic disk tangentially with radially; A diffraction grating is arranged between secondary light source and the beam splitter, has a plurality of diffraction grooves, is used for the light beam after the holographic disk reflection is incided on one second detector; Object lens, between beam splitter and holographic disk, the every Shu Guang that is used for passing beam splitter focuses on each face of first and second record surfaces, and will converge to respectively on second diffraction element of diffraction grating and diffractive optical element from each light beam of each first and second record surfaces reflection; And one have a plurality of photronic first detectors, the intensity that each photoelectric cell can measuring beam, and produce a corresponding output with the beam intensity form; One second detector, have one can measuring beam intensity a photoelectric cell, and produce a corresponding output with the beam intensity form; Detecting signal unit with first and secondary signal testing circuit, be used to detect the information signal that reproduces from second record surface, first signal deteching circuit comprises a totalizer, and first and second subtracter, be used for and convert electric signal to from photronic output signal, and be used for producing a focus error signal from first record surface, a tracking error signal and a generating information and signal, wherein first light source is used for generating generating information and signal from first record surface of holographic disk, secondary light source is closed during this period, and when second record surface of holographic disk generates generating information and signal, also be used for detecting and follow the tracks of and focus error signal at secondary light source.
From the description of preferred embodiment being carried out below in conjunction with appended figure, the present invention will become obviously together with above-mentioned purpose and advantage with other, wherein:
Fig. 1 represents a simplified side view of a prior art optical pickup system;
Fig. 2 represents a sectional view with CD of a pair of reflection hologram film;
Figure 3 shows that a skeleton view with the corresponding to optical pickup system of a preferred embodiment of the present invention;
Figure 4 shows that a detailed perspective view of the diffractive optical element in the optical pickup system shown in Fig. 3;
Fig. 5 has provided a photo-detector in the optical pickup system shown in Fig. 3 and a skeleton view of a diffractive optical element;
Fig. 6 A-6C for example understands the point that incides the light beam on the detector receiving plane; And
Fig. 7 is the block scheme with the corresponding to signal deteching circuit of the present invention.
Fig. 3 is to the various views that Figure 7 shows that with the corresponding to creative optical pickup system of the preferred embodiments of the present invention.The same section of it should be noted that among the figure to be occurred has identical reference number.
As shown in Figure 3, comprise first and secondary light source 12A with the corresponding to optical pickup system 100 of the present invention, 12B, each in the light source has a different wavelength, such as λ
1, λ
2A diffractive optical element 50, a diffraction grating 102,56, one on 52, one object lens of a beam splitter comprise one first and one second record surface 33 on it, 35 holographic disk 30 and one first and one second detector 24,25, the first detectors 24 comprise five photoelectric cells, and second detector 25 has a photoelectric cell.
In system 100, when the first light source 12A when first record surface 33 of holographic disk 30 reproduces a signal, secondary light source 12B closes.At this moment, from the first light source 12A, a branch of smooth 13A that sends such as a semiconductor laser incides on first diffraction element 58 of first diffractive optical element 50 and is diffracted into 0 and ± 1 grade of three-beam 15A.The reflecting surface 54 that three-beam 15A partly sees through beam splitter 52 incides object lens 56, and object lens 56 converge to three-beam 15A on first record surface 33, and wherein first record surface 33 only reflects from the first light source 12A and has wavelength X
1Light beam 15A, it is transparent to the light beam with other wavelength.
This three light beam 15A is by 33 reflections of first record surface, and the three-beam 17A after the reflection incides on second diffraction element 60 of first diffractive optical element 50 by the reflecting surface 54 of object lens 56 and beam splitter 52.Because shown in Fig. 4,5, second diffraction element 60 has a pair of diffraction subregion, each subregion has a different pitch, and therefore, each bundle that second diffraction element 60 will be included in 0 among the three-beam 17A after the reflection and ± 1 grade of light beam is diffracted into three pairs 0 and ± 1 order diffraction light beam.By representing with 18,19 that second diffraction element 60 produces from a pair of+1 that is included in 0 grade of light beam among the light beam 17A (or-1) order diffraction light beam.This right+1 (or-1) order diffraction light beam 18,19 then is sent to first detector 24.For the purpose of simple and direct, do not mark among other light beams figure.
Referring to Fig. 4, first diffractive optical element 50 comprises first and second diffraction elements 58 that are positioned at its opposite flank, a rhombic system crystal base 68 of 60, wherein second diffraction element 60 again and then be provided with one first and one second diffraction subregion 64,66, the two by division line 62 separately, the radial parallel of division line 62 and holographic disk 30 is also vertical with the recording channel direction (promptly tangentially) of holographic disk 30.The linear grating groove that is formed on each in the diffraction subregion 64,66 has a predetermined pitch, and these grooves and division line 62 quadratures.Big than the first diffraction subregion 64 of set pitch in the second diffraction subregion 66 arranged again.Crystal base 68 is by a kind of transparent material, and (polycarbonate Polycarbonate) is made as PMMA (polymethylmethacrylate, Polymethyl Meta Acryllrate) or PC.It should be noted that radially aiming at of groove and holographic disk 30 on first diffraction element 58, thus parallel with the division line 62 on second diffraction element 60.
First detector 24 is divided into five photoelectric cells 70,72,74,76 and 78.Each photoelectric cell can both be surveyed from light beam spot, and for example 80,82,83,84,85 and 86 beam intensity.Among the three-beam 17A after the reflection each is restrainted diffracted subregion 64 and 66 and is diffracted into three pairs 0 grade and ± 1 order diffraction light beam.In a preferred embodiment of the invention, first detector 24 be set at reception by the three-beam 17A of diffraction subregion 64,66 diffraction+position of 1 grade or-1 grade light beam.Such as, light beam spot 80,83,85th, by diffraction subregion 66 diffraction+1 grade of light beam forms, and light beam spot 82,84,86th, by diffraction subregion 64 diffraction+1 grade of light beam forms.
Distinguishingly, in above-mentioned the setting, when each record surface 33 that is accurately positioned from 0 grade of the first light source 12A and ± 1 grade of three-beam 15A in holographic disk 30, on 35, be that holographic disk 30 is when being in just in time focusing position, 0 grade of light beam among the three-beam 17A after the reflection is by the first diffraction subregion, 64 diffraction of second diffraction element 60, and produces one+1 order diffraction light 19 thus.This+1 order diffraction light 19 is focused in the division line 90 of photoelectric cell 72 separately and 74 and forms a light beam spot 82.Another part of 0 order diffraction light beam among the three-beam 17A after the reflection diffraction in diffraction subregion 66 also produces+1 order diffraction light 18 thus.This first-order diffraction light 18 is focused on the photoelectric cell 76 and forms a light beam spot 80.After being included in the diffracted subregion 66 of-1 order diffraction light and 64 diffraction among the three-beam 17A after the reflection, a pair of light beam spot 83,84 of each self-forming on photoelectric cell 70.Three-beam 17A after the reflection+the diffracted subregion 66 of 1 order diffraction light and 64 diffraction after on photoelectric cell 78 a pair of light beam spot 85,86 of each self-forming.
Fig. 6 A is depicted as the light beam spot 82 that incides on the photoelectric cell 72,74, and this moment, holographic disk 30 was in just in time focusing position, and produces one zero to defocus error signal.If holographic disk 30 is removed from focusing position just in time, as away from object lens 56, light beam spot 82 incides on the photoelectric cell 74, shown in Fig. 6 B.If holographic disk 30 shifts near object lens 56, then light beam spot 82 incides on the photoelectric cell 72, shown in Fig. 6 C.
Referring to Fig. 7, suppose that S1 to S5 represents respectively from photoelectric cell 70,72,74,76 and 78 output signal, the focus error signal (FE) of the focusing error of the light beam 15A on first record surface 33 shown in the representative graph 3 can obtain from the difference of S2 and S3 by using first subtracter 94, for example deducts S3 with S2.Represent the tracking error signal (TE) of the tracking error of light beam 15A to obtain by using in the difference of second subtracter 96 from S1 and S5.Carry generating information and signal (RF) from the recorded information of record surface 33, can be by using totalizer 92 with output signal S2, S3 and S4 addition obtain.
Referring again to Fig. 3, in order to reproduce the recorded information from record surface 35, second detector 25 reads the information signal of reproduction from second record surface of holographic disk 30, and this moment, secondary light source 12B opened.From the focusing of first record surface 33 of holographic disk 30 and the error signal that tracking error signal also is used to focus on and follow the tracks of second record surface 35.In this case, from secondary light source 12B, the light beam 13B that sends as a semiconductor laser enters beam splitter 52 and by 54 partial reflections of the reflecting surface in the beam splitter 52, enters object lens 56 then.Then, light beam 13B is focused on by object lens 56 and by not being that the first transparent record surface 33 of light beam of λ 1 is incident on second record surface 35 to wavelength.Second record surface 35 is with light beam 13B reflected back eyepiece 56, thus the light beam 15B after the cremasteric reflex.Light beam 15B after the reflection is reflected to diffraction grating 102 by object lens 56 and by reflecting surface 54.Diffraction grating 102 is diffracted into 0 and ± 1 order diffraction light beam with light beam 15B.The position of second detector 25 makes+and 1 order diffraction light beam 20 incides on its receiving surface, thus can detect the generating information and signal on second record surface 35 of holographic disk 30.For the sake of simplicity, other light beams do not draw.Must be pointed out that accept on the surface if second position of detector makes-1 order diffraction light beam incide it, described-1 order diffraction light beam also can be used to detect the generating information and signal on second record surface.
Therefore, as mentioned above, this optical pickup system creative, that adopted a pair of light source can use in holographic disk.
The present invention is described, yet is not departing from the present invention under the situation of the scope defined in the appended claims, can also carry out other modifications and variations according to preferred embodiment.
Claims (6)
1, an optical pickup system is used for reproducing the information signal that is stored on the holographic disk that comprises first and second record surfaces, and each record surface has a plurality of along the tangential recording channel that is provided with of holographic disk, comprising:
The a pair of light source that is used for producing first and second light beams, each light beam has different wavelength;
A diffractive optical element, a rhombic system crystal base that comprises first and second diffraction elements that are positioned at its opposite flank, first diffraction element is provided with a plurality of diffraction grooves, be used for and be divided into three-beam by the light beam that light source sends, and this three-beam is delivered to first and second record surfaces to get on, the radial parallel of the direction of each diffraction groove and holographic disk wherein, radially with tangentially perpendicular, be provided with two diffraction subregions that are divided into by division line radially in second diffraction element, being used for being diffracted into one first detector from the three-beam of first record surface reflection gets on, two diffraction zones have the groove of different pitch, are used for making three-beam along different angle diffraction;
A beam splitter, has a reflecting surface, the first bundle light that is used for first light source is sent is delivered on first record surface, and the second bundle light that secondary light source sends is reflexed on second record surface, wherein said diffractive optical element is set between first light source and the beam splitter, and described beam splitter is between diffractive optical element and object lens, and wherein reflecting surface tilts with respect to the optical axis from the light of each record surface reflection, and optical axis perpendicular to holographic disk tangentially with radially;
A diffraction grating is arranged between secondary light source and the beam splitter, has a plurality of diffraction grooves, is used for the light beam after the holographic disk reflection is incided on one second detector;
Object lens, between beam splitter and holographic disk, the every Shu Guang that is used for passing beam splitter focuses on each face of first and second record surfaces, and will converge to respectively on second diffraction element of diffraction grating and diffractive optical element from each light beam of each first and second record surfaces reflection; And
One has a plurality of photronic first detectors, the intensity that each photoelectric cell can measuring beam, and produce a corresponding output with the beam intensity form;
One second detector, have one can measuring beam intensity a photoelectric cell, and produce a corresponding output with the beam intensity form;
Detecting signal unit with first and secondary signal testing circuit, be used to detect the information signal that reproduces from second record surface, first signal deteching circuit comprises a totalizer, and first and second subtracter, be used for and convert electric signal to from photronic output signal, and be used for producing a focus error signal from first record surface, a tracking error signal and a generating information and signal, wherein first light source is used for generating generating information and signal from first record surface of holographic disk, secondary light source is closed during this period, and when second record surface of holographic disk generates generating information and signal, also be used for detecting and follow the tracks of and focus error signal at secondary light source.
2, optical pickup system as claimed in claim 1, it is characterized in that, each detector comprises five photoelectric cells, first and the 4th photoelectric cell by the first tangential division line separately, second and the 3rd photoelectric cell by the second tangential division line separately, second and the 4th photoelectric cell by one radially division line separately, the 4th and the 5th photoelectric cell separated by the 3rd tangential division line.
3, optical pickup system as claimed in claim 1 is characterized in that, second detector has a photoelectric cell at least.
4, optical pickup system as claimed in claim 1 is characterized in that, focus error signal is by using first subtracter, obtains from the difference of the second and the 3rd photoelectric cell output signal.
5, optical pickup system as claimed in claim 1 is characterized in that, tracking error signal is by using second subtracter, obtains from the difference of the first and the 5th photronic output signal.
6, optical pickup system as claimed in claim 1 is characterized in that, generating information and signal obtains from totalizer, is about to second, third and the 4th photronic output signal addition.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN95105599A CN1078727C (en) | 1995-05-15 | 1995-05-15 | Optical pickup system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN95105599A CN1078727C (en) | 1995-05-15 | 1995-05-15 | Optical pickup system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1149176A CN1149176A (en) | 1997-05-07 |
| CN1078727C true CN1078727C (en) | 2002-01-30 |
Family
ID=5075540
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN95105599A Expired - Fee Related CN1078727C (en) | 1995-05-15 | 1995-05-15 | Optical pickup system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1078727C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101232204B (en) * | 2008-01-11 | 2011-08-10 | 华中科技大学 | High pressure equipment insulating power supply based on electro-optical transformation |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0320276A2 (en) * | 1987-12-09 | 1989-06-14 | Sharp Kabushiki Kaisha | Optical pickup device |
| US4908813A (en) * | 1986-12-10 | 1990-03-13 | Hitachi, Ltd. | Wavelength multiplexing optical recording apparatus |
| EP0496132A2 (en) * | 1990-12-21 | 1992-07-29 | Koninklijke Philips Electronics N.V. | Method of and apparatus for optically writing, reading and erasing a multi-plane record carrier, and record carrier suitable for said method and apparatus |
-
1995
- 1995-05-15 CN CN95105599A patent/CN1078727C/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4908813A (en) * | 1986-12-10 | 1990-03-13 | Hitachi, Ltd. | Wavelength multiplexing optical recording apparatus |
| EP0320276A2 (en) * | 1987-12-09 | 1989-06-14 | Sharp Kabushiki Kaisha | Optical pickup device |
| EP0496132A2 (en) * | 1990-12-21 | 1992-07-29 | Koninklijke Philips Electronics N.V. | Method of and apparatus for optically writing, reading and erasing a multi-plane record carrier, and record carrier suitable for said method and apparatus |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101232204B (en) * | 2008-01-11 | 2011-08-10 | 华中科技大学 | High pressure equipment insulating power supply based on electro-optical transformation |
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| Publication number | Publication date |
|---|---|
| CN1149176A (en) | 1997-05-07 |
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