CN101295521A - Optical pickup device - Google Patents
Optical pickup device Download PDFInfo
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- CN101295521A CN101295521A CNA2008100921538A CN200810092153A CN101295521A CN 101295521 A CN101295521 A CN 101295521A CN A2008100921538 A CNA2008100921538 A CN A2008100921538A CN 200810092153 A CN200810092153 A CN 200810092153A CN 101295521 A CN101295521 A CN 101295521A
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
- G11B7/1365—Separate or integrated refractive elements, e.g. wave plates
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
- G11B7/1356—Double or multiple prisms, i.e. having two or more prisms in cooperation
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
- G11B7/1372—Lenses
- G11B7/1374—Objective lenses
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B2007/0003—Recording, reproducing or erasing systems characterised by the structure or type of the carrier
- G11B2007/0006—Recording, reproducing or erasing systems characterised by the structure or type of the carrier adapted for scanning different types of carrier, e.g. CD & DVD
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Abstract
A quarter-wave plate and a polarization beam splitter are used as means for guiding a laser beam to first and second objective lenses. A half of the circularly-polarized laser beam incident to the polarization beam splitter is reflected in the form of an S-polarized light component by the polarization beam splitter and guided to a first objective lens, and the other half is transmitted through the polarization beam splitter in the form of a P-polarized light component and guided to a second objective lens. The whole of light quantity of the laser beam reflected from an optical disk through the first or second objective lens passes substantially through the polarization beam splitter. Therefore, the light quantity of the laser beam guided to a photodetector can be enhanced.
Description
Technical field
The present invention relates to a kind of optical take-up apparatus, relate in particular to the optical take-up apparatus that is suitable for when utilizing a plurality of object lens to different types of dish irradiating laser.
Background technology
Along with exchange type optical take-up apparatus to different dish irradiating lasers is being developed in the variation of dish.In this optical take-up apparatus with Blu-ray Disc (hereinafter referred to as " BD ") and the corresponding optical take-up apparatus of HD DVD (High-Definition Digital Versatile Disc :) hereinafter referred to as " HD ", because the NA of the cover thickness of its dish and object lens (numerical aperture) difference, so be equipped with two object lens corresponding to each dish.In this case, owing to use the Wavelength of Laser band identical,, just expect according to a shared semiconductor laser as light source and will constitute from the mode that the laser of semiconductor laser is distributed to each object lens from the aspect of the simplification of cost and even formation.
For the emitted laser of semiconductor laser is distributed to two object lens, can utilize liquid crystal cells (cell) and polarization beam splitter (polarisation PVC one system ス プ リ Star ).Just, utilize liquid crystal cells to make the direction of polarized light of laser be varied to relative polarization beam splitter some for P polarized light and S polarized light.When being the P polarized light, laser sees through polarization beam splitter and is directed to the 1st object lens; When being the S polarized light, laser is directed to the 1st object lens by the polarization beam splitter reflection.In addition, also can be configured the leading portion by 1/2 wavelength plate being configured in polarization beam splitter and it is inserted take off and laser is distributed to two object lens in light path.
But, state in the use and produce following problem in the formation of liquid crystal cells, that is, because the cost of liquid crystal cells makes the cost increase of optical take-up apparatus; And, need the driving mechanism of liquid crystal cells just to make the formation of optical take-up apparatus and control become complicated.In addition, also produce following problem in making the slotting formation of taking off of above-mentioned 1/2 wavelength plate, that is, need to drive the formation of 1/2 wavelength plate, this makes the formation of optical take-up apparatus and control become complicated.
Be used under the recording situation at exchange type optical take-up apparatus, the laser light intensity during in order to ensure the dish irradiation preferably will only import to corresponding object lens from the laser of semiconductor laser.But, being used at exchange type optical take-up apparatus under the situation of regeneration usefulness, the laser light intensity during owing to the dish irradiation is that the intensity of renewable degree is enough, also can adopt the formation that laser is imported simultaneously two object lens thus.But, in this case, the viewpoint of the S/N from guarantee regenerated signal or focusing (focus) error signal and tracking error signal, the laser that also needs to shine dish maintains more than the setting with the light amount ratio that imports to the laser of photodetector.
Figure 11 is the figure of the configuration example of the expression optical take-up apparatus that carries object lens.After the emitted laser of semiconductor laser 51 were divided into 3 bundles by diffraction grating 52, by no polarized light catoptron 53 beam split, it 90% was reflected to collimation lens 54 sides.Then, laser is become directional light by collimation lens 54, so incide object lens 56 by catoptron 55 reflections and by optically focused on dish.Dish institute laser light reflected forms converging light by catoptron 55 reflections and by collimation lens 54.9% laser of the light quantity when then, semiconductor laser 51 being penetrated by no polarized light catoptron 53 beam split by optically focused to photodetector 57.
In this configuration example, be 10: 1 (transmitance/reflectivity that wherein, does not comprise each optical element, dish) to dish laser that shines and the light amount ratio that is directed to the laser of photodetector 57.
Figure 12 is the figure of the configuration example of the expression optical take-up apparatus that carries two object lens.In this configuration example, use half reflection prism 61 as mechanism with laser beam split to two object lens 62,64.After the emitted laser of semiconductor laser 51 were divided into 3 bundles by diffraction grating 52, by no polarized light catoptron 53 beam split, it 90% was reflected to collimation lens 54 sides.Then, laser is become directional light by collimation lens, so half by half reflection prism 61 reflection and be situated between by the 1st object lens 62 by optically focused on dish.On the other hand, the laser that sees through half reflection prism 61 by catoptron 63 reflections and be situated between by the 2nd object lens 64 by optically focused on dish.In this case, be situated between the light quantity that is irradiated to the laser on the dish by the 1st and the 2nd object lens 62,64 be semiconductor laser 51 laser when emitted light quantity 45%.
Dish institute laser light reflected is by catoptron 63 and 61 reflections of half reflection prism.At this moment, laser makes its light quantity be reduced to half by half reflection prism 61.Then, become converging light by collimation lens 54, and then by no polarized light catoptron 53 beam split.Its result, 2.25% laser of the light quantity when semiconductor laser 51 penetrates by optically focused to photodetector 57.
In this configuration example, be 20: 1 (transmitance/reflectivity that wherein, does not comprise each optical element, dish) to dish laser that shines and the light amount ratio that is directed to the laser of photodetector 57.
Like this, using under the situation of half reflection prism 61 as spectrophotometric unit two object lens, because toward the road with return in the road dim light 50% respectively, so be reduced in the past half (20: 1) to the laser of dish irradiation and the light amount ratio that is directed to the laser of photodetector 57.For this reason, the S/N of the signal exported of photodetector 57 just can not become the sufficient S/N that regenerates.
Summary of the invention
The optical take-up apparatus of a first aspect of the present invention has: LASER Light Source, and it penetrates the laser of provision wavelengths; First and second object lens, it makes above-mentioned laser convergence; Polarization beam splitter, it will distribute to above-mentioned first and second object lens from the laser of above-mentioned LASER Light Source; With 1/4 wavelength plate, it is configured between above-mentioned LASER Light Source and the above-mentioned polarization beam splitter, makes above-mentioned laser incide above-mentioned polarization beam splitter with circularly polarized light.
The optical take-up apparatus of a second aspect of the present invention has: LASER Light Source, and it penetrates the laser of provision wavelengths; First and second object lens, it makes above-mentioned laser convergence on recording medium; Polarization beam splitter, it will distribute to above-mentioned first and second object lens from the laser of above-mentioned LASER Light Source; First and second 1/4 wavelength plate, it is configured in the light path between above-mentioned polarization beam splitter and above-mentioned first and second object lens respectively; Photodetector, it is accepted by the aforementioned recording medium reflection and via the above-mentioned laser of above-mentioned polarization beam splitter, with 1/4 wavelength plate, it is configured between above-mentioned LASER Light Source and the above-mentioned polarization beam splitter, makes above-mentioned laser incide above-mentioned polarization beam splitter with circularly polarized light.
According to the optical take-up apparatus of first and second aspect, because use polarization beam splitter and cheap 1/4 wavelength plate conduct are used for importing to first and second object lens the mechanism of laser, so can suppress the cost of optical take-up apparatus.In addition owing to do not need to be used to drive the formation of liquid crystal cells and be used for 1/2 wavelength plate is inserted the formation unload, so can suppress to constitute so control complicated.Have again, optical take-up apparatus according to first and second aspect, because the catoptrical whole approximately light quantities from dish via first and second object lens are passed through polarization beam splitter, so the light quantity of the laser that is directed to photodetector is improved, can make the S/N of the signal that photodetector exports become the S/N of appropriate level.
The optical take-up apparatus of the third aspect of this aspect has: LASER Light Source, and it penetrates the laser of provision wavelengths; First and second object lens, it makes above-mentioned laser convergence; Polarization beam splitter, it will distribute to above-mentioned first and second object lens from the laser of above-mentioned LASER Light Source; With 1/2 wavelength plate, it is configured between above-mentioned LASER Light Source and the above-mentioned polarization beam splitter, makes above-mentioned laser incide above-mentioned polarization beam splitter with the rectilinearly polarized light of the polarizing axis inclination predetermined angular of above-mentioned relatively polarization beam splitter.
According to the optical take-up apparatus of the third aspect, because use polarization beam splitter and cheap 1/2 wavelength plate conduct are used for importing to first and second object lens the unit of laser, so can suppress the cost of optical take-up apparatus.In addition, identical with the optical take-up apparatus of first and second aspect, can suppress to constitute so control complicated, and can improve the S/N of the signal that photodetector exports.
The optical take-up apparatus of a fourth aspect of the present invention has: LASER Light Source, and it penetrates the laser of provision wavelengths; First and second object lens, it makes above-mentioned laser convergence; And polarization beam splitter, it will distribute to above-mentioned first and second object lens from the laser of above-mentioned LASER Light Source, according to the mode of the emitted above-mentioned laser of above-mentioned LASER Light Source, dispose above-mentioned LASER Light Source with the rectilinearly polarized light incident of the polarizing axis inclination predetermined angular of above-mentioned relatively polarization beam splitter.
Optical take-up apparatus according to fourth aspect, according to the mode of laser with the rectilinearly polarized light incident of the polarizing axis inclination predetermined angular of relative polarization beam splitter, the configuration LASER Light Source, thus, just do not need to dispose 1/4 wavelength plate or 1/2 wavelength plate in addition for laser being imported to first and second object lens, thereby can suppress the cost of optical take-up apparatus.Have again, identical with the optical take-up apparatus of first and second aspect, can suppress to constitute so control complicated, and can improve the S/N of the signal that photodetector exports.
The optical take-up apparatus of a fifth aspect of the present invention has: LASER Light Source, and it penetrates the laser of provision wavelengths; First and second object lens, it makes above-mentioned laser convergence on recording medium; Polarization beam splitter, it will distribute to above-mentioned first and second object lens from the laser of above-mentioned LASER Light Source; First and second 1/4 wavelength plate, it is configured in the light path between above-mentioned polarization beam splitter and above-mentioned first and second object lens respectively; And photodetector, it is accepted by the aforementioned recording medium reflection and via the above-mentioned laser of above-mentioned polarization beam splitter, and the emitted above-mentioned laser of above-mentioned LASER Light Source is with the rectilinearly polarized light incident of the polarizing axis inclination predetermined angular of above-mentioned relatively polarization beam splitter.
Optical take-up apparatus according to the 5th aspect, laser is with the rectilinearly polarized light incident of the angle of the polarizing axis inclination regulation of relative polarization beam splitter, thus, for laser being imported to first and second object lens, just can make the emitted laser of LASER Light Source successfully distribute to first and second object lens.Have again and since via first and second object lens from catoptrical all light quantities approximately of dish by polarization beam splitter, so the light quantity of the laser that is directed to photodetector is improved, and can improve the S/N of the signal that photodetector exports.
Description of drawings
Of the present invention above-mentioned and other purpose and new feature by reading the explanation of embodiment shown below with reference to following accompanying drawing, and can be clear and definite more completely.
Fig. 1 is the figure of the structure of the related optical take-up apparatus of expression first embodiment of the present invention.
Fig. 2 A, B represent the irradiating state of the related laser of first embodiment to photodetector.
Fig. 3 represents the state of the focus error signal that first embodiment is related.
Fig. 4 represents the configuration example of the signal computing circuit that first embodiment is related.
Fig. 5 A, B represent the formation of the optical take-up apparatus that second embodiment of the present invention is related.
Fig. 6 represents the formation of the optical take-up apparatus that the 3rd embodiment of the present invention is related.
Fig. 7 represents the modification of the optical take-up apparatus that the 3rd embodiment is related.
Fig. 8 A, B represent the formation of the optical take-up apparatus that the 4th embodiment of the present invention is related.
Fig. 9 A, B represent the modification of the optical take-up apparatus that the 4th embodiment is related.
Figure 10 A, B represent other modifications of the optical take-up apparatus that the 4th embodiment is related.
Figure 11 is the explanation figure that deals with problems of the present invention.
Figure 12 is the explanation figure that deals with problems of the present invention.
Wherein, accompanying drawing is specifically designed to explanation, and scope of the present invention is not limited.
Embodiment
＜the first embodiment 〉
Fig. 1 represents the formation (optical system) of the optical take-up apparatus that first embodiment is related.Among the figure, the 11st, penetrating wavelength is the semiconductor laser (LASER Light Source) of the blue laser about 405nm; The 12nd, the laser from semiconductor laser 11 is divided into 3 diffraction grating of restrainting; The 13rd, make 90% of incident laser reflect and make the no polarized light catoptron of the 10% parallel flat shape that sees through.No polarized light catoptron 13 be configured the relative angle (for example 45 °) of the inclined light shaft regulation of incident laser.
The 14th, 13 laser light reflected of no polarized light catoptron are transformed to the collimation lens of directional light; The 15th, be that 1/4 wavelength plate 16 of circularly polarized light is a polarization beam splitter with the laser beam transformation that sees through collimation lens 14.
The 17th, 16 laser light reflected of polarization beam splitter (S polarized light) are converged to the 1st object lens on the HD; The 18th, the catoptron that the laser (P polarized light) that sees through polarization beam splitter 16 is reflected; The 19th, make 18 laser light reflected of catoptron (P polarized light) be focused at the 2nd object lens on the BD; The 20th, be used to accept from the emission light of HD, BD and generate the photodetector of various signals.
At this, the 1st object lens 17 and the 2nd object lens 19 design according to the mode that laser suitably is focused on HD and the BD respectively.In addition, these the 1st and the 2nd object lens 17,19 are driven along focusing and tracking direction integratedly by object lens gear train (not shown).
The laser that semiconductor laser 11 is emitted, be divided into 3 bundles by diffraction grating 12 after, by no polarized light catoptron 13 beam split, 90% is reflected to collimation lens 14 sides.Then, laser is become directional light by collimation lens 14, and then is transformed to circularly polarized light by 1/4 wavelength plate 15 and incides polarization beam splitter 16.
Like this, by polarization beam splitter 16, make in the laser of institute's incident half as the S polarized light by polarization beam splitter 16 reflections, and remaining half just see through polarization beam splitter 16 as the P polarized light.Wherein, the laser of S polarized light component (below, be called " first laser ") be situated between by first object lens 17 by optically focused on dish, the laser of P polarized light component (below, be called " second laser ") is by after catoptron 18 reflections, be situated between by second object lens 19 by optically focused on dish.Thereby, the light quantity of the laser that shone to dish by first and second object lens 17,19 of being situated between be semiconductor laser 11 laser when emitted light quantity 45%.
First laser that reflected of dish is owing to incide polarization beam splitter 16 with the state of S polarized light, so about 100% by polarization beam splitter 16 reflections.In addition, second laser that dish is reflected is also owing to inciding polarization beam splitter 16 with the P polarized light state, so about 100% just sees through polarization beam splitter 16.
Then, first and second laser is become converging light by collimation lens 14, and then by no polarized light catoptron 13 beam split.4.5% of light quantity when its result, the light quantity that is directed to first and second laser of photodetector 20 are semiconductor laser 11 ejaculations.
In addition, first and second laser is owing to incide no polarized light catoptron 13 with converging light, so imported astigmatism (astigmatism, non-check and accept poor) by no polarized light catoptron 13.In the present embodiment, focus error signal is generated by method of astigmatism.In photodetector 20, dispose and cut apart sensor based on 4 of method of astigmatism.
In the present embodiment, be 10: 1 (transmitance/reflectivity that wherein, does not comprise each optical element, dish) to dish laser that shines and the light amount ratio that is directed to first and second laser of photodetector 20.Thereby the S/N that can make the signal that photodetector 20 exports is for to the sufficient S/N that regenerates.
In addition, in the present embodiment, laser via first and second object lens 17,19 shines to dish simultaneously, but, because the covering of HD and BD (cover) layer thickness is different, so for example second laser can not suitably be focused on the HD when using first laser that HD is regenerated, first laser can not suitably be focused on the BD when using second laser that BD is regenerated in addition, thus, can not have problems even receive first and second laser to regenerated signal etc. with common sensing pattern (photodetector 20) yet.
Just, shown in Fig. 2 A, when using first laser that HD is regenerated, second laser (flash of light) that HD reflected is not assembled on photodetector 20, in addition, shown in Fig. 2 B, when using second laser that BD is regenerated, first laser (flash of light) that BD reflected is not assembled on photodetector 20.Under this situation, the overlapping DC composition that flash of light is arranged on the signal that photodetector 20 is exported, but this DC composition is suitably deleted in the regenerative loop side.
In addition, when (Off オ one カ ス Yin き Write body) introduced in the focusing of object dish, also shown in Fig. 3 signal like that owing to just produce S word curve inadequately according to the laser that not have in the regeneration in first and second laser to use, focus on the anxiety that introducing is carried out so do not exist not make based on this S word curve.In addition, FEsh is the threshold values rank that sets for the S word curve of discerning the introducing object among Fig. 3.In addition, FE1 is based on the amplitude of first and second laser S word curve that employed laser generated in regeneration (real S word curve); FE2 is based on first and second laser does not have the S word curve that laser generated (the S word curve of forgery) of use in regeneration amplitude.
In addition, in the present embodiment, because the track space of BD and HD is different, so be suitable for the axially diffraction pattern of (in-line) mode in the diffraction pattern of diffraction grating 12.Thus, the object dish of no matter regenerating is that among BD, the HD which all can receive reflected light from each dish by common sensitive surface.In addition, because the DPP method of axial manner is a known method in the past, in this description will be omitted.
The formation of the signal computing circuit when Fig. 4 represents to use the DPP method.As shown in the figure, signal computing circuit is by adding circuit 101～104, subtraction circuit 105～107, adding circuit 111～116, subtraction circuit 117～119 with decide doubling circuit 118 and constitute.In addition, photodetector 20 comprise that main beam is subjected to that light uses 4 cut apart that sensors A～D, side beam be subjected to that light uses 4 cut apart sensor E～G, I～L.
Be made as under the situation of A～L the computing of TE=(A+B)-(C+D)-α { (E+I+F+J)-(G+K+H+L) } and generate tracking error signal (TE) cutting apart the signal that sensors A～L exports with 4.Computing by FE=(A+C)-(B+D), RF=A+B+C+D generates focus error signal (FE) and regenerated signal (RF).
In addition, utilize 1 light beam to recommend method and also can generate tracking error signal.At this moment, omit 4 and cut apart sensor E～L; Signal computing circuit is also recommended method along with 1 light beam and is changed.
More than, according to present embodiment, owing to used polarization beam splitter 16 and 1/4 cheap wavelength plate 21 as the unit that imports laser to first and second object lens 17,19, so can suppress the cost of optical take-up apparatus.In addition because do not need to be used to drive the formation of liquid crystal cells and be used to make 1/2 wavelength plate to insert the formation take off, so can suppress to constitute so control complicated.
And then, according to present embodiment, because all light quantities approximately of first and second laser that dish is reflected are by polarization beam splitter 16, so can improve the light quantity of the laser that is directed to photodetector 20, as above-mentioned, can make the laser to the dish irradiation is 10: 1 with the light amount ratio that is directed to first and second laser of photodetector 20.Thereby can make the S/N of the signal that photodetector 20 exported is the S/N of appropriate level.
Have again, according to present embodiment, when seeing through no polarized light catoptron 13, be imported into astigmatism from the reflected light that coils, so, need not dispose the lens element that astigmatism imports usefulness for focus error detection more in addition, thereby can realize the reduction of part number of packages and the inhibition of cost.
＜the second embodiment 〉
Fig. 5 A, B represent the formation (optical system) of the optical take-up apparatus that second embodiment is related.Fig. 5 A be from semiconductor laser 31 to the vertical view that erects the optical system till the catoptron 36,42, Fig. 5 B is the side view that erects the later optical system of catoptron 36,22.In addition, among Fig. 5 B, for facility is represented the part of lens mount 25 with cut-open view.
In the figure, the 31st, the semiconductor laser (LASER Light Source) of the blue laser about ejaculation wavelength 405nm, the 32nd, be the optical element after integrated by 1/4 wavelength plate 32a and diffraction grating 32b of circularly polarized light with laser beam transformation from semiconductor laser 31, the 33rd, polarization beam splitter.Semiconductor laser 31 emitted laser are transformed to circularly polarized light by 1/4 wavelength plate 32a.Thereby, inciding the laser of polarization beam splitter 33, its 50% (P polarized light component) sees through polarization beam splitter 33, and remaining 50% (S polarized light component) is by polarization beam splitter 33 reflections.
The 34th, 33 laser light reflected of polarization beam splitter (S polarized light) are transformed to the collimation lens of directional light, the 35th, catoptron, the 36th, with 35 laser light reflected of catoptron along the catoptron that erects towards the direction reflection of first object lens 38.
The 37th, be transformed to the one 1/4 wavelength plate of circularly polarized light with erecting catoptron institute laser light reflected, the 38th, make first object lens of laser convergence on BD that see through the one 1/4 wavelength plate 37.
The 39th, will see through the catoptron of laser (P polarized light) reflection of polarization beam splitter 33, the 40th, 39 laser light reflected of catoptron are transformed to the collimation lens of directional light, the 41st, catoptron, the 42nd, with 41 laser light reflected of catoptron along the catoptron that erects towards the direction reflection of second object lens 44.
The 43rd, be transformed to the 2 1/4 wavelength plate of circularly polarized light with erecting 42 laser light reflected of catoptron, the 44th, make second object lens of laser convergence on HD that see through the 2 1/4 wavelength plate 43.
The 45th, keep the lens mount of first object lens the 38, the 2 1/4 wavelength plate 43 and second object lens 44, the 46th, be used for the coil (part of known object lens gear train) that first object lens the 38, the 2 1/4 wavelength plate 43 and second object lens 44 and lens mount 45 are driven integratedly.
The 47th, to importing the detection lens of astigmatism towards the laser of photodetector 48 from polarization beam splitter 33, the 48th, be used to accept from the reflected light of HD, BD and generate the photodetector of various signals.In the present embodiment, utilize method of astigmatism to generate focus error signal.On photodetector 48, dispose as described later and cut apart sensor based on 4 of method of astigmatism.
At this, first object lens 38 and second object lens 44 are respectively according to the mode that laser suitably is focused on BD and the HD can being designed.In addition, these first and second object lens 38,44 by object lens gear train (with only illustrating coil 46 among the figure) focus on and tracking direction on by integrated driving.
In addition, in the present embodiment, first object lens 38 are made of glass, for than the high high weight of second object lens 44 that is made of plastics.In order to compensate unbalanced on the relevant weight, in the present embodiment, only the 2 1/4 wavelength plate 43 in the one 1/4 wavelength plate 37 and the 2 1/4 wavelength plate 43 is installed on the lens mount 45, the one 1/4 wavelength plate 37 is configured in Fig. 5 A installation the base side of optical element.
First laser that dish (BD) is reflected is advanced against the light path when coiling, and incides polarization beam splitter 33.At this moment, first laser is the P polarized light owing to seeing through the one 1/4 wavelength plate 17 relative polarization beam splitter 33 that becomes once more, thus, directly sees through polarization beam splitter 33.Thereafter, first laser is imported into astigmatism by detecting lens 27, and is converged to photodetector 28.
On the other hand, incide the laser of polarization beam splitter 33 by 1/4 wavelength plate 32a and diffraction grating 32b from semiconductor laser 31 Jie, its light quantity composition of 50% (below, be called " second laser ") through polarization beam splitter 33 and to catoptron 19 incidents.Second laser that catoptron 19 is reflected becomes directional light by collimation lens 20, and then by catoptron 21 with after erecting catoptron 42 reflections, is transformed to circularly polarized light and is incided second object lens 24 by the 2 1/4 wavelength plate 23.
Dish second laser that (HD) reflected is advanced against the light path when coiling and is incided polarization beam splitter 33.At this moment, second laser is the S polarized light owing to seeing through the 2 1/4 wavelength plate 23 relative polarization beam splitter 33 that becomes once more, thereby by polarization beam splitter 33 reflections.Thereafter, second laser is imported into astigmatism by detecting lens 27, is converged to photodetector 28.
In the present embodiment, be 1: 1 (transmitance/reflectivity that wherein, does not comprise each optical element, dish) to dish laser that shines and the light amount ratio that is directed to first and second laser of photodetector 28.In addition, to about 50% light quantity of the emitted laser of dish and photodetector 28 importing semiconductor laser 31.Thereby, can make the S/N of the signal that photodetector 28 exported become the sufficient S/N of regeneration.
In the present embodiment, laser via first and second object lens 38,44 is irradiated on the dish simultaneously, but it is same with first embodiment, because no laser of when regeneration (flash of light) is expanded greatly on photodetector 48, so also can realize regenerating smoothly by the processing of DC composition removal etc. even this laser (flash of light) incides photodetector 48.In addition, the circuit of the Fig. 4 shown in signal computing circuit can use in the above-described first embodiment.
More than, according to second embodiment, because first, second 1/4 wavelength plate 37,43 that uses first and second object lens 38,44 and use polarization beam splitter 33 and cheapness is as the mechanism that is used for importing to photodetector 48 laser, so can suppress the cost of optical take-up apparatus.In addition because do not need to be used to drive liquid crystal cells formation, be used for 1/2 wavelength plate is inserted the formation take off, so can avoid constituting and even control complicated.
And then, according to second embodiment, make whole approximately light quantities of first and second laser that dish is reflected be imported into photodetector 48 by polarization beam splitter 33.For this reason, the light quantity of the laser that imports to photodetector 48 is improved, as above-mentioned, can make the laser to the dish irradiation is 1: 1 with the light amount ratio that is directed to first and second laser of photodetector 48.Thereby the S/N of the signal that photodetector 48 can be exported more increases to being higher than above-mentioned first embodiment.
In addition, in the present embodiment, the pitch angle of the direction of polarized light of the laser of the polarizing axis of relative polarization beam splitter 33 is made as 45 degree, and making the light amount ratio by first laser after polarization beam splitter 33 beam split and second laser is 1: 1, but, the pitch angle of the direction of polarized light of the laser of polarizing axis that also can be by suitably adjusting relative polarization beam splitter 33 makes beyond the light amount ratio of first laser and second laser is set at 1: 1.
＜the three embodiment 〉
Present embodiment is the modification of above-mentioned first embodiment.Just, in above-mentioned first embodiment (Fig. 1), though utilize 1/4 wavelength plate to make laser become circularly polarized light and incide polarization beam splitter 16, but, even the direction of polarized light according to regulating laser with respect to the polarizing axis of polarization beam splitter 16 for the mode that tilts also can play and the same effect of above-mentioned first embodiment.Present embodiment relates to following structure, by the polarizing axis inclination of the relative polarization beam splitter 16 of the direction of polarized light that makes laser, and will distribute to first and second object lens 17,19 from the laser of semiconductor laser 11.
Fig. 6 represents the formation of the 3rd embodiment.In the present embodiment, 1/4 wavelength plate 15 in above-mentioned first embodiment is replaced as 1/2 wavelength plate 21.Other formation is identical with above-mentioned first embodiment (Fig. 1).
1/2 wavelength plate 21 be configured for example as shown in Figure 6 the direction of polarized light of the relative polarization beam splitter 16 of laser be that relative P direction of polarized light and S direction of polarized light tilt 45 °.Under this situation, incide the laser of polarization beam splitter 16, its half (S polarized light) by polarization beam splitter 16 reflections, remaining half (P polarized light) sees through polarization beam splitter 16.By regulating the direction of polarized light of the relative polarization beam splitter 16 of laser, the light amount ratio of the laser that is directed to first and second object lens 17,19 was changed since 1: 1.
After semiconductor laser 11 emitted laser became 3 bundles by diffraction grating 12, by no polarized light catoptron 13 beam split, 90% was reflected to collimation lens 14 sides.Then, laser is become directional light by collimation lens 14, and then adjusts direction of polarized light as described above by 1/2 wavelength plate 21.So laser incides polarization beam splitter 16.
Like this, by polarization beam splitter 16, make in the laser of institute's incident half as the S polarized light by polarization beam splitter 16 reflections, and remaining half just see through polarization beam splitter 16 as the P polarized light.Wherein, the laser of S polarized light component (first laser) be situated between by first object lens 17 by optically focused on dish, the laser of P polarized light component (second laser) by catoptron 18 reflection backs be situated between by second object lens 19 by optically focused on dish.Thereby, the light quantity of the laser that shone to dish by first and second object lens 17,19 of being situated between be semiconductor laser 11 laser when emitted light quantity 45%.
First laser that reflected of dish is owing to incide polarization beam splitter 16 with the state of S polarized light, so about 100% by polarization beam splitter 16 reflections.In addition, second laser that dish is reflected is also owing to inciding polarization beam splitter 16 with the P polarized light state, so about 100% just sees through polarization beam splitter 16.
Then, first and second laser is become converging light by collimation lens 14, and then by no polarized light catoptron 13 beam split.4.5% of light quantity when its result, the light quantity that is directed to first and second laser of photodetector 20 are semiconductor laser 11 ejaculations.
In addition, first and second laser, owing to incide no polarized light catoptron 13 with converging light, so imported astigmatism by no polarized light catoptron 13.In the present embodiment, identical with above-mentioned first embodiment, generate focus error signal by method of astigmatism.In photodetector 20, dispose in the same manner based on 4 of method of astigmatism and cut apart sensor with above-mentioned first embodiment.
In the present embodiment, be 10: 1 (transmitance/reflectivity that wherein, does not comprise each optical element, dish) to dish laser that shines and the light amount ratio that is directed to first and second laser of photodetector 20.Thereby the S/N that can make the signal that photodetector 20 exports is for to the sufficient S/N that regenerates.
Fig. 7 represents another other configuration example.In this configuration example, compare with the formation of Fig. 6, omitted 1/4 wavelength plate 15, for example as shown in Figure 7, is tilt 45 ° mode of relative P direction of polarized light and S direction of polarized light according to laser to the direction of polarized light of polarization beam splitter 16, and the configuration of noise spectra of semiconductor lasers 11 is regulated.Under this situation, incide the laser of polarization beam splitter 16, its half (S polarized light) by polarization beam splitter 16 reflections, remaining half (P polarized light) sees through polarization beam splitter 16.In addition, regulate with the optical axis position of rotation of the semiconductor laser 11 that is axle, regulate the direction of polarized light of laser thus, the light amount ratio of the laser that is directed to first and second object lens 17,19 was changed from 1: 1 polarization beam splitter 16.
According to the formation of Fig. 7, compare with the formation of above-mentioned first embodiment and Fig. 6, owing to omitted 1/4 wavelength plate 15 and 1/2 wavelength plate 21, so can realize further constituting simplification.
＜the four embodiment 〉
Present embodiment is the modification of above-mentioned second embodiment.Just, in above-mentioned second embodiment (Fig. 5 A, B), though utilize 1/4 wavelength plate 32a that laser is become circularly polarized light and incides polarization beam splitter 33, but, even the direction of polarized light according to regulating laser with respect to the polarizing axis of polarization beam splitter 33 for the mode that tilts also can play and the same effect of above-mentioned first embodiment.Present embodiment relates to following structure, by the polarizing axis inclination of the relative polarization beam splitter 33 of the direction of polarized light that makes laser, and will distribute to first and second object lens 38,44 from the laser of semiconductor laser 31.
Fig. 8 A, B represent the formation of the 4th embodiment.Fig. 8 A be from semiconductor laser 31 to the vertical view that erects the optical system till the catoptron 36,42, Fig. 8 B is the side view that erects the later optical system of catoptron 36,42.In addition, among Fig. 8 B, for convenience, the part of lens mount 45 is represented with cut-open view.
In the present embodiment, omitted 1/4 wavelength plate 32a in above-mentioned first embodiment.In addition, the tilt modes of 45 degree of semiconductor laser 31, the relative polarizing axis of the direction of polarized light of the laser when inciding polarization beam splitter 33 are to being that the position of rotation of axle is adjusted with the laser beam axis.Thereby, inciding the laser of polarization beam splitter 33, its 50% (P polarized light) sees through polarization beam splitter 33, and remaining 50% (S polarized light) is by polarization beam splitter 33 reflections.Other formation is identical with above-mentioned second embodiment (Fig. 5 A, B).
After semiconductor laser 31 emitted laser become 3 light beams by diffraction grating 32b, by polarization beam splitter 33 with 50% light quantity composition (first laser) to collimation lens 34 lateral reflections.Then, this first laser becomes directional light by collimation lens 34, and then by catoptron 35 with after erecting catoptron 36 reflections, is transformed to circularly polarized light and is incided first object lens 38 by the one 1/4 wavelength plate 37.
First laser that dish (BD) is reflected is advanced against the light path when coiling, and incides polarization beam splitter 33.At this moment, first laser is the P polarized light owing to seeing through the one 1/4 wavelength plate 37 relative polarization beam splitter 33 that becomes once more, thus, directly sees through polarization beam splitter 33.Thereafter, first laser is imported into astigmatism by detecting lens 47, and is converged to photodetector 28.
On the other hand, be situated between from semiconductor laser 31 and incided the laser of polarization beam splitter 33 by diffraction grating 32, its light quantity composition of 50% (second laser) sees through polarization beam splitter 33 and to catoptron 39 incidents.Second laser that catoptron 39 is reflected becomes directional light by collimation lens 40, and then by catoptron 41 with after erecting catoptron 42 reflections, is transformed to circularly polarized light and is incided second object lens 44 by the 2 1/4 wavelength plate 43.
Dish second laser that (HD) reflected is advanced against the light path when coiling and is incided polarization beam splitter 33.At this moment, second laser is the S polarized light owing to seeing through the 2 1/4 wavelength plate 43 relative polarization beam splitter 33 that becomes once more, thereby by polarization beam splitter 33 reflections.Thereafter, second laser is imported into astigmatism by detecting lens 47, is converged to photodetector 48.
In the present embodiment, be 1: 1 (transmitance/reflectivity that wherein, does not comprise each optical element, dish) to dish laser that shines and the light amount ratio that is directed to first and second laser of photodetector 48.In addition, to about 50% light quantity of the emitted laser of dish and photodetector 48 importing semiconductor laser 41.Thereby, can make the S/N of the signal that photodetector 48 exported become the sufficient S/N of regeneration.
In addition, regulate the direction of polarized light of laser, the light amount ratio of the laser that is directed to first and second object lens 38,44 was changed from 1: 1 polarization beam splitter 33.
Yet, in the formation of Fig. 8 A, B, the position of rotation that will be the semiconductor laser 31 of axle with the laser beam axis is adjusted, the pitch angle of polarizing axis that can be adjusted to the relative polarization beam splitter 33 of direction of polarized light of laser is 45 degree, but also 1/2 wavelength plate can be configured between semiconductor laser 31 and the polarization beam splitter 33, adjust the pitch angle of polarizing axis of the relative polarization beam splitter 33 of direction of polarized light of laser.
Fig. 9 A, B represent the figure of the configuration example under this situation.In this configuration example, between semiconductor laser 31 and polarization beam splitter 33, dispose with 1/2 wavelength plate 49a and diffraction grating 49b the optical element 49 after integrated.At this, optical element 49 is constituted as: when the pitch angle according to the polarizing axis of the relative polarization beam splitter 33 of the direction of polarized light of laser is the modes of 45 degree when making 1/2 wavelength plate 49a location, the diffraction of diffraction grating 49b just makes 3 light beams suitable location on the track of BD and HD.Thereby, when the assembling of optical system, do not need in addition the configuration of diffraction grating 49b to be adjusted, can realize the raising of operation.
More than, embodiments of the present invention have been described, but the present invention is not limited to these embodiments, and embodiments of the present invention also can be carried out various changes except above-mentioned points.
For example, in the above-mentioned first and the 3rd embodiment, be 9: 1 though make the splitting ratio of no polarized light catoptron 13, also can be splitting ratio in addition.
In addition, in the above-mentioned second and the 4th embodiment, in order to compensate unbalanced on weight of first object lens 38 and second object lens 44, the 2 1/4 wavelength plate 43 is disposed at lens mount 45, the one 1/4 wavelength plate 37 is configured in base side, but, for example under the situation of the degree that the weight difference between 38 lightweights of first object lens and this two object lens is not exerted an influence to the drive characteristic of object lens, for example, as Figure 10 A, shown in the B, also the one 1/4 wavelength plate 37 can be disposed at lens mount 45 sides, with the one 1/4 wavelength plate 37, first object lens 38, the 2 1/4 wavelength plate 43 and second object lens 44 integrally drive with lens mount 45.
And, like this one 1/4 wavelength plate 37 and the 2 1/4 wavelength plate 43 all are being disposed under the situation of lens mount 45, also can they are integrated, that is, also can on the light path of first and second laser, dispose 1/4 common wavelength plate.
In addition, embodiments of the present invention in the scope of the technological thought shown in the scope of claim, can suit to carry out various changes.
Claims (11)
1, a kind of optical take-up apparatus has:
LASER Light Source, it penetrates the laser of provision wavelengths;
First and second object lens, it makes above-mentioned laser convergence;
Polarization beam splitter, it will distribute to above-mentioned first and second object lens from the laser of above-mentioned LASER Light Source; With
1/4 wavelength plate, it is configured between above-mentioned LASER Light Source and the above-mentioned polarization beam splitter, makes above-mentioned laser incide above-mentioned polarization beam splitter with circularly polarized light.
2, optical take-up apparatus according to claim 1 is characterized in that,
Possess flat no polarized light catoptron, press the state configuration of the inclined light shaft of above-mentioned relatively laser in the diffusion light path of its above-mentioned laser between above-mentioned LASER Light Source and above-mentioned 1/4 wavelength plate,
The part of the above-mentioned laser that above-mentioned LASER Light Source is emitted is seen through above-mentioned no polarized light catoptron and incides above-mentioned photodetector from the part of above-mentioned 1/4 wavelength plate towards the above-mentioned laser of above-mentioned no polarized light catoptron by the direction reflection of above-mentioned no polarized light catoptron to above-mentioned 1/4 wavelength plate.
3, a kind of optical take-up apparatus possesses:
LASER Light Source, it penetrates the laser of provision wavelengths;
First and second object lens, it makes above-mentioned laser convergence on recording medium;
Polarization beam splitter, it will distribute to above-mentioned first and second object lens from the laser of above-mentioned LASER Light Source;
First and second 1/4 wavelength plate, it is configured in the light path between above-mentioned polarization beam splitter and above-mentioned first and second object lens respectively;
Photodetector, its accept by the aforementioned recording medium reflection and via the above-mentioned laser of above-mentioned polarization beam splitter and
1/4 wavelength plate, it is configured between above-mentioned LASER Light Source and the above-mentioned polarization beam splitter, makes above-mentioned laser incide above-mentioned polarization beam splitter with circularly polarized light.
4, a kind of optical take-up apparatus has:
LASER Light Source, it penetrates the laser of provision wavelengths;
First and second object lens, it makes above-mentioned laser convergence;
Polarization beam splitter, it will distribute to above-mentioned first and second object lens from the laser of above-mentioned LASER Light Source; With
1/2 wavelength plate, it is configured between above-mentioned LASER Light Source and the above-mentioned polarization beam splitter, makes above-mentioned laser incide above-mentioned polarization beam splitter with the rectilinearly polarized light of the polarizing axis inclination predetermined angular of above-mentioned relatively polarization beam splitter.
5, optical take-up apparatus according to claim 4 is characterized in that,
Possess:
Flat no polarized light catoptron, in the diffusion light path of its above-mentioned laser between above-mentioned LASER Light Source and above-mentioned 1/2 wavelength plate by with the state configuration of the inclined light shaft of above-mentioned laser,
The part of the above-mentioned laser that above-mentioned LASER Light Source is emitted is seen through above-mentioned no polarized light catoptron and incides above-mentioned photodetector from the part of above-mentioned 1/2 wavelength plate towards the above-mentioned laser of above-mentioned no polarized light catoptron by the direction reflection of above-mentioned no polarized light catoptron to above-mentioned 1/2 wavelength plate.
6, a kind of optical take-up apparatus has:
LASER Light Source, it penetrates the laser of provision wavelengths;
First and second object lens, it makes above-mentioned laser convergence; With
Polarization beam splitter, it will distribute to above-mentioned first and second object lens from the laser of above-mentioned LASER Light Source,
According to the mode of the emitted above-mentioned laser of above-mentioned LASER Light Source, dispose above-mentioned LASER Light Source with the rectilinearly polarized light incident of the polarizing axis inclination predetermined angular of above-mentioned relatively polarization beam splitter.
7, optical take-up apparatus according to claim 6 is characterized in that,
Possess flat no polarized light catoptron, press the state configuration of the inclined light shaft of above-mentioned relatively laser in the diffusion light path of its above-mentioned laser between above-mentioned LASER Light Source and above-mentioned polarization beam splitter,
The part of the above-mentioned laser that above-mentioned LASER Light Source is emitted is seen through above-mentioned no polarized light catoptron and incides above-mentioned photodetector from the part of above-mentioned polarization beam splitter towards the above-mentioned laser of above-mentioned no polarized light catoptron by the direction reflection of above-mentioned no polarized light catoptron to above-mentioned polarization beam splitter.
8, a kind of optical take-up apparatus has:
LASER Light Source, it penetrates the laser of provision wavelengths;
First and second object lens, it makes above-mentioned laser convergence on recording medium;
Polarization beam splitter, it will distribute to above-mentioned first and second object lens from the laser of above-mentioned LASER Light Source;
First and second 1/4 wavelength plate, it is configured in the light path between above-mentioned polarization beam splitter and above-mentioned first and second object lens respectively; With
Photodetector, it is accepted by the aforementioned recording medium reflection and via the above-mentioned laser of above-mentioned polarization beam splitter,
The emitted above-mentioned laser of above-mentioned LASER Light Source is with the rectilinearly polarized light incident of the polarizing axis inclination predetermined angular of above-mentioned relatively polarization beam splitter.
9, optical take-up apparatus according to claim 8 is characterized in that,
According to the mode of the emitted above-mentioned laser of above-mentioned LASER Light Source, adjust with the laser beam axis position of rotation of the above-mentioned LASER Light Source that is axle with the rectilinearly polarized light incident of the polarizing axis inclination afore mentioned rules angle of above-mentioned relatively polarization beam splitter.
10, optical take-up apparatus according to claim 8 is characterized in that,
Dispose in the light path between above-mentioned LASER Light Source and above-mentioned polarization beam splitter and be used to make 1/2 wavelength plate of above-mentioned laser with the rectilinearly polarized light incident of the polarizing axis inclination afore mentioned rules angle of above-mentioned relatively polarization beam splitter.
11, optical take-up apparatus according to claim 10 is characterized in that,
Be used for the laser that above-mentioned LASER Light Source is emitted be divided into 3 the bundle diffraction grating and above-mentioned 1/2 wavelength plate by integrated.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2007-114038 | 2007-04-24 | ||
| JP2007114038A JP2008269735A (en) | 2007-04-24 | 2007-04-24 | Optical pickup device |
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| Publication Number | Publication Date |
|---|---|
| CN101295521A true CN101295521A (en) | 2008-10-29 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNA2008100921538A Pending CN101295521A (en) | 2007-04-24 | 2008-04-08 | Optical pickup device |
Country Status (4)
| Country | Link |
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| JP (1) | JP2008269735A (en) |
| KR (1) | KR20080095782A (en) |
| CN (1) | CN101295521A (en) |
| TW (1) | TW200842862A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106464788A (en) * | 2014-06-27 | 2017-02-22 | 富士胶片株式会社 | Imaging device |
| CN108549197A (en) * | 2018-03-15 | 2018-09-18 | 中国科学院上海应用物理研究所 | It is a kind of original position luminous flux monitoring and exposure dose compensation method |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102487175A (en) * | 2010-12-27 | 2012-06-06 | 北京国科世纪激光技术有限公司 | Laser output method and laser output apparatus |
-
2007
- 2007-04-24 JP JP2007114038A patent/JP2008269735A/en active Pending
-
2008
- 2008-02-19 TW TW097105681A patent/TW200842862A/en unknown
- 2008-04-08 CN CNA2008100921538A patent/CN101295521A/en active Pending
- 2008-04-23 KR KR1020080037481A patent/KR20080095782A/en not_active Application Discontinuation
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106464788A (en) * | 2014-06-27 | 2017-02-22 | 富士胶片株式会社 | Imaging device |
| CN106464788B (en) * | 2014-06-27 | 2019-05-03 | 富士胶片株式会社 | Photographic device |
| CN108549197A (en) * | 2018-03-15 | 2018-09-18 | 中国科学院上海应用物理研究所 | It is a kind of original position luminous flux monitoring and exposure dose compensation method |
| CN108549197B (en) * | 2018-03-15 | 2020-04-17 | 中国科学院上海应用物理研究所 | In-situ luminous flux monitoring and exposure dose compensation method |
Also Published As
| Publication number | Publication date |
|---|---|
| TW200842862A (en) | 2008-11-01 |
| KR20080095782A (en) | 2008-10-29 |
| JP2008269735A (en) | 2008-11-06 |
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