CN101361126B - Light source unit, optical detector unit, optical pickup device, and optical disk device - Google Patents

Abstract

A light source unit comprises a plurality of light sources emitting a plurality of light beams. A plurality of volume hologram elements are provided for the plurality of light sources respectively, each volume hologram element having a plane of incidence of an incoming light beam and a plane of outgoing radiation of a diffracted light beam which are perpendicular to each other, the plurality of volume hologram elements having mutually different Bragg conditions in which an optical intensity of a diffracted light beam is set to a maximum.

Description

Light source cell, optical detector unit, optic pick-up and optical disc apparatus

Technical field

The present invention relates to launch simultaneously the light source cell of light beam, detect the optical detector unit of light beam and beam emissions separately to the recording layer of CD and receive optic pick-up by the light beam of CD reflection, and the optical disc apparatus with this optic pick-up.

Background technology

In recent years, along with the progress of digital technology and the raising of data compression technique, be used for the information recording carrier of logger computer program, music information, video information (content) etc., comprise CD, such as, CD (read-only optical disc) and DVD (Digital video disc) attract much attention.The cheap CD of information regeneration that is used to carry out the information record of CD and CD is universal.CD-RW (CD-can rewrite) DVD-RAM, DVD-RW (DVD-can rewrite), DVD+RW (DVD+ can rewrite) etc. dominates the market at present as CD-RW.

In optical disc apparatus, become at orbit-shaped on the recording layer of CD of spirality or concentric circles and form the little luminous point of laser beam, record information on the dish, and the information regeneration that coils based on the reflected light of recording layer.

Simultaneously, the trend of the quantity of information of video information or content is to increase year by year, but expects the recorded information amount at individual CD, that is, memory capacity further increases.For example, blu-ray standard proposes as the method for the memory capacity that increases CD, makes its recording density be higher than the recording density of the DVD on the present visual field.

With the situation of the CD of blu-ray standard compatibility (be called BD dish) under, the thickness of substrate equals about 0.1mm, optical disc apparatus corresponding to the BD dish uses wavelength to equal the light source of 405mm, utilizing object lens to form NA is 0.85 focal spot, and the BD dish is carried out the reproduction of recording of information, information and the deletion of information.That is, DVD and BD dish has optical source wavelength, substrate thickness and the NA value that differs from one another.

For this reason, coil and have in the optical disc apparatus of single object lens and have such problem being suitable for access DVD dish and BD, if the characteristic of object lens is suitable for one of DVD dish and BD dish,, can produce aberration for another recording medium because the substrate thickness between DVD dish and the BD dish is poor.

The another kind of method that increases the memory capacity of CD is to use the CD (being called multilayer disc) with a plurality of recording layers.CD corresponding to multilayer disc actively carries out with the research that is suitable for the optical disc apparatus of access multilayer disc.For example, with reference to day patented claim No.63-113947 of the present disclosure, Jap.P. No.2988732 be entitled as " Volume holographic device for the spherical aberrationcorrection and the parallel data access in three-dimensional memory " Fr-PD-15ISOM2000, the document of Lee S.C. and Y.Kawata.

Yet, according to disclosed optical element in day patented claim No.63-113947 of the present disclosure, for the recording layer quantity that makes CD reaches tens layers, need utilize different recording mediums to form CD to every recording layer, make that like this cost that forms CD is too high.

According to disclosed optical disc apparatus in Jap.P. No.2988732,, in lens combination, produce aberration (coma) if a plurality of light source arrangement on identical plane, is used the light beam of the light source that is positioned at the optical axis outside.There is such problem, is difficult on panel surface, obtain the luminous point of diffraction limit.And the light of collimation lens is exported at a certain angle, for each light source, and the light quantity difference that object lens obtained, the problem that exists the light utilization ratio obviously to reduce.

According to disclosed optical element in above-mentioned document, the diffraction efficiency of volume hologram reduces, because volume hologram carries out multiexposure, multiple exposure.If spot number increases, the surperficial power of acquisition will reduce.And, if light source arrangement on surface perpendicular to optical axis, the light of collimation lens is exported at a certain angle, for each light source, light quantity and light quantity distribution that object lens obtained differ from one another.There is such problem: the light utilization ratio will occur and reduce and the symmetrical beam dot structure.

Summary of the invention

According to an aspect of the present invention, provide the improvement light source cell of eliminating the problems referred to above.

According to an aspect of the present invention, provide light source cell, optical detector unit, optic pick-up and be suitable for obtaining minimizing of device and the optical disc apparatus that do not reduce light utilization efficiency.

Solving or reducing in the embodiments of the invention of above-mentioned one or more problems, a kind of light source cell is provided, comprising: a plurality of light sources, launch a plurality of light beams; With a plurality of volume hologram elements, be respectively applied for a plurality of light sources, each volume hologram element has the plane of incidence of orthogonal incident beam and the output radiation face of diffracted beam, and a plurality of volume hologram elements have light intensity that differ from one another, diffracted beam and are maximum Bragg condition (Bragg condition).

Solving or reducing in the embodiments of the invention of above-mentioned one or more problems, a kind of light source cell is provided, comprising: a plurality of light source cells, launch a plurality of light beams; With a plurality of volume hologram elements, be respectively applied for a plurality of light sources, at least one of a plurality of volume hologram elements is used at least one of a plurality of light sources, and has the output radiation plane of the plane of incidence and the diffracted beam of orthogonal incident beam.

Solving or reducing in the embodiments of the invention of above-mentioned one or more problems, a kind of optical detector unit is provided, it detects a plurality of light beams individually, this optical detector unit comprises: a plurality of volume hologram elements, be respectively applied for a plurality of light beams, each volume hologram element has the plane of incidence of orthogonal corresponding light beam and the output radiation face of diffracted beam, and the light intensity that a plurality of volume hologram elements have the diffracted beam that differs from one another is maximum Bragg condition; A plurality of photoelectric detectors are respectively applied for a plurality of volume hologram elements, and each photoelectric detector receives from the light beam of a corresponding diffraction of a plurality of volume hologram elements.

Solving or reducing in the embodiments of the invention of above-mentioned one or more problems, a kind of optical detection unit is provided, it detects a plurality of light beams respectively, this optical detection unit comprises: a plurality of volume hologram elements, be respectively applied for a plurality of light beams, at least one of a plurality of volume hologram elements is used for a branch of at least of diffraction multiple laser bundle, and has the plane of incidence of orthogonal corresponding light beam and the output radiation face of diffracted beam; A plurality of photoelectric detectors are respectively applied for a plurality of volume hologram elements, and each photoelectric detector receives from the light of a corresponding diffraction of a plurality of volume hologram elements.

According to embodiments of the invention, can minimizing of implement device and do not reduce light utilization efficiency.

Other purpose of the present invention, feature and advantage following detailed description in conjunction with the drawings is apparent.

Description of drawings

Fig. 1 is the block diagram of the composition of optical disc apparatus in expression one embodiment of the invention.

Fig. 2 is the synoptic diagram of the optic pick-up in the key drawing 1.

Fig. 3 is a synoptic diagram of explaining the feature of volume hologram element.

Fig. 4 A and 4B are the synoptic diagram of the operation of the holographic element in the key drawing 2.

Fig. 5 is the synoptic diagram of the formation method of the holographic element in the key drawing 2.

Fig. 6 is the process flow diagram of the processing of explaining that when from the request of host apparatus receiving record the optical disc apparatus by Fig. 1 carries out.

Fig. 7 explains the process flow diagram that reproduces when asking the processing that the optical disc apparatus by Fig. 1 carries out when receiving from host apparatus.

Fig. 8 is the synoptic diagram of remodeling of the pick device of key drawing 1.

Fig. 9 is the synoptic diagram of remodeling of the pick device of key drawing 1.

Figure 10 is the synoptic diagram of remodeling of the pick device of key drawing 1.

Figure 11 is the synoptic diagram of remodeling of the holographic element of key drawing 2.

Figure 12 is a synoptic diagram of explaining the method for the holographic element that forms Figure 11.

Figure 13 A and Figure 13 B be the explain information luminous intensity distribute and the intensity distributions of diffraction light between the synoptic diagram of relation.

Figure 14 A and Figure 14 B be the explain information luminous intensity distribute and the intensity distributions of diffraction light between the synoptic diagram of relation.

Figure 15 A and Figure 15 B be the explain information luminous intensity distribute and the intensity distributions of diffraction light between the synoptic diagram of relation.

Figure 16 is the synoptic diagram of remodeling of the optic pick-up of key drawing 1.

Figure 17 is a synoptic diagram of explaining the optic pick-up of one embodiment of the invention.

Figure 18 is a synoptic diagram of explaining the optic pick-up of one embodiment of the invention.

Figure 19 is a synoptic diagram of explaining the optic pick-up of one embodiment of the invention.

Figure 20 is the synoptic diagram of remodeling of explaining the optic pick-up of Figure 19.

Figure 21 is a synoptic diagram of explaining the optic pick-up of one embodiment of the invention.

Figure 22 is the synoptic diagram of remodeling of explaining the optic pick-up of Figure 20.

Figure 23 is a synoptic diagram of explaining the optic pick-up of one embodiment of the invention.

Figure 24 is a synoptic diagram of explaining the optic pick-up in the optical disc apparatus of one embodiment of the invention.

Figure 25 is the synoptic diagram of remodeling of explaining the optic pick-up of Figure 24.

Figure 26 is a synoptic diagram of explaining the optic pick-up of one embodiment of the invention.

Figure 27 A, Figure 27 B and Figure 27 C are the synoptic diagram of explaining the holographic cell among Figure 26.

Figure 28 is the synoptic diagram of remodeling of explaining the optic pick-up of Figure 26.

Figure 29 is a synoptic diagram of explaining the optic pick-up of one embodiment of the invention.

Figure 30 A, Figure 30 B and Figure 30 C are the synoptic diagram of explaining the light of each the holographic cell emission from Figure 29.

Figure 31 A and Figure 31 B are the synoptic diagram of explaining the preparation method of each holographic element among Figure 29.

Figure 32 A and Figure 32 B are the synoptic diagram of explaining the operation of each holographic element among Figure 29.

Figure 33 A and Figure 33 B be the explain information luminous intensity distribute and the intensity distributions of diffraction light between the synoptic diagram of relation.

Figure 34 A and Figure 34 B be the explain information luminous intensity distribute and the intensity distributions of diffraction light between the synoptic diagram of relation.

Figure 35 A and Figure 35 B be the explain information luminous intensity distribute and the intensity distributions of diffraction light between the synoptic diagram of relation.

Figure 36 is the synoptic diagram of remodeling of explaining the optic pick-up of Figure 29.

Figure 37 is a synoptic diagram of explaining the optic pick-up of one embodiment of the invention.

Figure 38 A is a synoptic diagram of explaining the preparation method of the holographic element among Figure 37, and Figure 38 B is the synoptic diagram of operation of explaining the holographic element of Figure 37.

Figure 39 is the synoptic diagram of remodeling of explaining the optic pick-up of Figure 37.

Figure 40 is a synoptic diagram of explaining the optic pick-up of one embodiment of the invention.

Figure 41 is the synoptic diagram of remodeling of explaining the optic pick-up of Figure 40.

Figure 42 is a synoptic diagram of explaining the optic pick-up of one embodiment of the invention.

Figure 43 A, Figure 43 B and Figure 43 C are the synoptic diagram of explaining the holographic cell of Figure 42.

Embodiment

Referring now to accompanying drawing embodiments of the invention are described.

Fig. 1 represents the composition of the optical disc apparatus 20 of one embodiment of the invention.As shown in Figure 1, optical disc apparatus 20 comprises spindle motor 22, the optical pick-up unit 23 that is used for rotary CD 15, tracking motor 21, laser control circuit 24, scrambler 25, Drive and Control Circuit 26, signal processing circuit 28, buffer RAM 34, buffer manager for use 37, interface 38, flash memory 39, CPU 40 and the RAM 41 that is used for the radial drive optical pick-up unit 23 of edge dish 15.

In Fig. 1, arrow is only represented the flow direction of general signal or general information, does not represent the physical connection between each element of optical disc apparatus.In the present embodiment, optical disc apparatus 20 is suitable for recorded information on the single face multiplayer optical disk, and the single face multiplayer optical disk has the multilayer rewritable recording layer in the one side of dish.

Compact disk structure in the optical disc apparatus of Fig. 2 presentation graphs 1.As shown in Figure 2, CD 15 is three layers of CD of single face, and it has first recording layer (L1), second recording layer (L2) and the 3rd recording layer (L3) that the light incident side by laser beam is disposed in order.CD 15 generally is an information recording carrier, such as DVD.

Optic pick-up 34 is suitable for launching simultaneously laser to three layers of recording layer of CD 15 and receive simultaneously from three layers of recording layer beam reflected.

As shown in Figure 2, optic pick-up 23 in this embodiment comprises three light source (LDa, LDb, LDc), three holographic elements (71a, 71b, 71c), collimation lens 52, polarization mark device 54, quarter-wave plate 55, object lens 60, detect lens 58, cylindrical lens 73, two half prism (76a, 76b), three pin holes (75a, 75b, 75c), three photoelectric detector (PDa, PDb, PDc) and be used to drive the drive system (not shown) of object lens 60.

Each light source has the semiconductor laser that emission wavelength equals the laser beam of 660nm, and each light source has the identical characteristics of luminescence.

In this embodiment, all maximum intensity output radiations are set at+the Z direction from the instruction of the laser beam of each light emitted.Light source LDb be arranged to light source Lda+the X side is adjacent, light source LDc be arranged to light source LDb+the X side is adjacent.The light beam (P polarization) that is parallel to the plane of incidence of polarization beam apparatus 54 from each light emitted.

All holographic elements all are the volume hologram elements.The volume hologram element mean holographic element according to the value (Q value) of following formula (1) parameters calculated Q greater than 10, according to Corona Publishing Co., Ltd. publishes, the author is Jiro Koyama and Hiroshi Nishihara " Light waveelectron optics " 117-132 page or leaf.

Q＝2πλ ₀T/(n ₀JI ²) ....(1)

λ wherein ₀(in air: 660nm), T represents the thickness of holographic element, n to expression incident light wavelength ₀The refractive index of expression holographic element substrate, JI represents the spacing (holographic spacing) of pattern groove.

Known volume holographic element only diffraction wavelength and incident angle satisfies the specific diffraction conditions light of (being called Bragg condition).

Fig. 3 is a synoptic diagram of explaining the characteristic of volume hologram element.As shown in Figure 3, when Q=10, if incident angle satisfies Bragg condition, primary diffraction efficient P (%) is a peak value.In Fig. 3, α is formulated: α=sin (incident angle)/2sin (Bragg angle).

Thermoplastics is used for the material of each holographic element, and it is set to T=2mm, n ₀=1.5, and JI=0.7 * λ ₀/ n ₀If these values are applied to above-mentioned formula (1), the Q value is set at Q ≈ 5800 in this case.Satisfy the condition of volume hologram element fully.

If the material that resembles photopolymer (it is not easy the thick thickness of stroke) is used for the material of each holographic element, preferred material is clipped in two layers between the glass sheet, has enough big thickness to guarantee it.The material thickness T that satisfies Q＞10 o'clock is set at more than or equal to 4 microns.As for each holographic element, whole zone is set at holographic region.The Bragg condition of each holographic element differs from one another.

Holographic element 71a is arranged in light source Lda's+the Z side, enters holographic element 71a from the light of light source Lda.Shown in Fig. 4 A, from the light of light source Lda diffraction repeatedly in the holographic region HA of holographic element 71a, and on boundary surface interreflection.The light of diffraction is launched from holographic element 71a edge+directions X.Be equal to from the light of the exit point S1 emission of shooting without hitting the target from the light of holographic element 71a diffraction, the exit point S1 that shoots without hitting the target be positioned at the optical axis of collimation lens 52 and be positioned at the focal position of leaving collimation lens 52-the X side.Although enter holographic element 71b and holographic element 71c from the light of holographic element 71a diffraction, this diffraction light sees through them invariably, because do not satisfy Bragg condition.

Holographic element 71a utilizes the method for 2 known beam interferences to form, as shown in Figure 5.For example, enter holographic element (wherein also not forming hologram pattern) from the lower surface of reference light from accompanying drawing of reference light source Lr (being equal to light source Lda), the information light with light launching site S1 enters holographic element from the left-hand side of accompanying drawing.Therefore, at the inner hologram pattern that forms of holographic element.Like this, the holographic element 71a of formation hologram pattern is formed.

Return and come with reference to Fig. 2, holographic element 71b be arranged in light source LDb+the Z side, the light of light source LDb enters holographic element 71b.The light of light source LDb is at the holographic region of holographic element 71b diffraction repeatedly, and on boundary surface interreflection.The light of diffraction is launched from holographic element 71b edge+directions X.From the only diverging light of holographic element 71b diffraction, it is equal to from the light of the exit point S2 emission of shooting without hitting the target of the focal position that is positioned at collimation lens 52.Although enter holographic element 71c from the light of holographic element 71b diffraction, it sees through holographic element 71c invariably, because do not satisfy Bragg condition.

Holographic element 71c is arranged in light source LDc's+the Z side, and the light of light source LDc enters holographic element 71c.The light of light source LDc diffraction repeatedly in the holographic region of holographic element 71c, and on boundary surface interreflection.The light of diffraction is launched from holographic element 71c edge+directions X.From the light of holographic element 71c diffraction be equal to from be positioned at leave the above-mentioned exit point S2 that shoots without hitting the target+light of the exit point S3 emission of shooting without hitting the target of X side position.

That is to say that the light intensity that each holographic element has the diffraction light that differs from one another is maximum Bragg condition.Shown in Fig. 4 B, have intensity distributions with the symmetrical of holographic element from the diffraction light of holographic element emission, the half-breadth angle θ b of intensity distributions is greater than the half-breadth angle θ a of incident light.

Holographic element 71b forms in the mode similar to above-mentioned holographic element 71a with holographic element 71c.

Distance between the optical magnification that each distance between the exit point of shooting without hitting the target is determined according to collimation lens 52 and object lens 66 and the recording layer of each CD 15 is determined.

Exit point is set in the position on the optical axis that is positioned at collimation lens 52 because these are shot without hitting the target, the predetermined distance that is separated from each other, and each recording layer is corrected to the spherical aberration that the alternate position spike of object lens 60 causes.That is, each holographic element has the function of the aberration that correction causes to the alternate position spike of object lens 60 by recording layer.

And in preparation during holographic element, the aberration that will be used to proofread and correct high-order spherical aberration is added to holographic element, increases aberration and be the aberration (mainly being coma) that is used for proofreading and correct in the mobile generation of the tracking servo operation of object lens 60, can proofread and correct high-order spherical aberration and coma.

Collimation lens 52 is arranged in holographic element 71c's+the X side.After seeing through collimation lens 52, be converged to the light of assembling a little from the light of holographic element 71a diffraction.After seeing through collimation lens 52, be converged to parallel beam from the light of holographic element 71b diffraction.After seeing through collimation lens 52, convert the light of dispersing a little from the light of holographic element 71c diffraction to.

Polarization beam apparatus 54 is arranged in collimation lens 52+X side.The reflection coefficient of polarization beam apparatus 54 is different and different according to the polarization of incident light state.For example, polarization beam apparatus 54 is arranged to that the P polarization is had little reflection coefficient, and the S polarization is had big reflection coefficient.Therefore, the light of most of collimation lens 52 can see through polarization beam apparatus 54.

Quarter-wave plate 55 is arranged in polarization beam apparatus 54+X side, incident light is provided the optical phase difference of 1/4 wavelength.Quarter-wave plate 55+the X side, arrange object lens 60, make the light that sees through quarter-wave plate 55 be focused.

The light of light source Lda focuses on the first recording layer L1, and the light of light source LDb focuses on the second recording layer L2, and the light of light source LDc focuses on the 3rd recording layer L3.That is,, on each recording layer, can form luminous point simultaneously if make each light source simultaneously luminous.

Detection lens 58 are arranged in polarization beam apparatus 54-Z side, and the back light of polarization beam apparatus 54 edge-Z directions reflection is converged to convergent beam.

Cylindrical lens 73 is arranged in detection lens 58-Z side, and the light that detects lens 58 is produced astigmatism (astigmatism).

Half prism 76a is arranged in cylindrical lens 73-Z side, and edge+directions X is reflected in the contained light component that returns from the 3rd recording layer L3 in the light of cylindrical lens 73, and makes remaining light component see through half prism 76a.

Half prism 76b is arranged in half prism 76a's-the Z side, the contained light component that returns from the second recording layer L2 in the light of edge+directions X reflecting ﹠ transmitting half prism 76a, and make remaining light component see through half prism 76b.

Pin hole 75a is arranged in half prism 76a's+the X side, and the light that is reflected by half prism 76a enters pin hole 75a.Light by pin hole 75a is received by photoelectric detector Pda.Therefore, the light of photoelectric detector Pda reception mainly is the light that returns from the 3rd recording layer L3.

Pin hole 75b is arranged in half prism 76b's+the X side, and the light that is reflected by half prism 76b enters pin hole 75b.Light by this pin hole 75b is received by photoelectric detector PDb.Therefore, the light of photoelectric detector PDb reception mainly is the light that returns from the second recording layer L2.

Pin hole 75c is arranged in half prism 76b's-the Z side, and the light that sees through half prism 76a enters pin hole 75c.Light by this pin hole 75c is received by photoelectric detector PDc.Therefore, the light of photoelectric detector PDc reception mainly is the light that returns from the first recording layer L1.

Drive system comprises focus actuator and follows the trail of actuator, focus actuator is used for along the focus direction of the optical axis direction of object lens 60 object lens 60 being activated very little amount, follows the trail of actuator and is used for along the tracking direction perpendicular to the tangential direction of coiling track object lens 60 being activated very little amount.

Next, the operation of the above-mentioned optic pick-up 23 of brief explanation.

By holographic element 71a edge+directions X diffraction, and pass through holographic element 71b, holographic element 71c and collimation lens 52 from face polarization (P polarization) light of light source Lda emission, enter polarization beam apparatus 54 with the state of a little convergent beam.

By holographic element 71b edge+directions X diffraction, and pass through holographic element 71c and collimation lens 52 from face polarization (P polarization) light of light source LDb emission, mainly being that the state of parallel lines light beam enters polarization beam apparatus 54.

By holographic member's part 71c edge+directions X diffraction, and pass through collimation lens 54 from face polarization (P polarization) light of light source LDc emission, enter polarization beam apparatus 54 with the state of the light beam dispersed a little.

The major part of every bundle diffraction light sees through polarization beam apparatus 54 invariably, converts circularly polarized light to by quarter-wave plate 55, thereby focuses on every layer of recording layer of CD 15 as point by object lens 60.

Convert the circularly polarized light of opposite polarization to from the light of every layer of recording layer reflection of CD 15, the light that returns enters quarter-wave plate 55 by object lens 60, thereby converts the linearly polarized light (S polarization) perpendicular to external travel to.This light that returns enters polarization beam apparatus 54.

The back light that is polarized the reflection of beam splitter 54 edge-Z directions enters half prism 76a by detecting lens 58 and cylindrical lens 73.Light is reflected by half prism 76a, and the light component that returns from the 3rd recording layer L3 contained in back light is received by photoelectric detector Pda by pin hole 75a.

Back light by half prism 76a enters half prism 76b.Light is reflected by half prism 76b, and the light component that returns from the second recording layer L2 contained in this back light is received by photoelectric detector PDb by pin hole 75a.

Back light (the mainly light component that returns from the first recording layer L1) by half prism 76b is received by photoelectric detector PDc by pin hole 75c.

Each photoelectric detector constitutes and comprises a plurality of photoelectric detectors (or a plurality of light receiving area), these photoelectric detector outputs comprise dither signal information, reproduce the signal of data message, focus error message, tracking error information etc., and are similar to the known optical disc device.

Each photoelectric detector (or each light receiving area) produces signal according to the light-receiving amount by opto-electronic conversion respectively, and signal is outputed to reproducing signal treatment circuit 28.

Return with reference to Fig. 1, reproducing signal treatment circuit 28 obtains servosignal (focus error signal, tracking error signal etc.), addressing information, synchronizing information, RF signal etc. based on the output (a plurality of photoelectric conversion signal) of each photoelectric detector.

The servosignal that is obtained outputs to Drive and Control Circuit 26, and addressing information outputs to CPU 40, and synchronizing signal outputs to scrambler 25 and Drive and Control Circuit 26.28 pairs of RF signals of reproducing signal treatment circuit carry out decoding processing, error detection process etc.When detecting error, carry out correction processing, the reproduction data that obtained are stored in the buffer RAM 34 by buffer manager for use 37.Contained addressing information outputs to CPU 40 in reproducing data.

Based on the servosignal of reproducing signal treatment circuit 28, Drive and Control Circuit 26 produces the drive signal of drive system, and drive signal is outputed to optic pick-up 23.Therefore, carry out Tracing Control and focus control.

Drive and Control Circuit 26 produces the drive signal that drives tracking motor 21, is used for the instruction of the drive signal of drives spindle motor 22 based on CPU 40.The drive signal of motor outputs to tracking motor 21 and spindle motor 22.

The data (record data) that write down on CD 15, the data of reproducing from CD 15 (reproduction data) are stored in the buffer RAM 34 temporarily.The data I/O of buffer RAM 34 is by buffer manager for use 37 management.

Based on the instruction of CPU 40, scrambler 25 obtains to be stored in record data in the buffer RAM 34 by buffer manager for use 37, carries out the modulation of data, the interpolation of error correction code, and produces the write signal of CD 15.The write signal that is produced outputs to laser control circuit 24.

The emissive power of laser control circuit 24 each light source of control.For example, under the situation of record, the drive signal of each light source produces by laser control circuit 24 based on the light characteristic of write signal, record condition, each light source etc.

Interface 38 is the two-way exchange interfaces with host apparatus 90 (for example, PC).It is based on standard interface, such as, ATAPT (additional information packet interface), SCSI (small computer system interface) and USB (same universal serial bus).

The various programs of describing in the order code by CPU 40 translations, the light characteristic of each light source etc. are stored in the flash memory 39,

CPU 40 controls the operation of various piece and will control required data storage in RAM 41 and buffer RAM 34 according to the said procedure of storage in flash memory 39.

Next, explain the recording processing that optical disc apparatus 20 carries out when the record request of user data is received by host apparatus 90 with reference to Fig. 6.

The process flow diagram of Fig. 6 is used to a series of processing computings of explaining that CPU 40 carries out.User data is recorded on the first recording layer L1, the second recording layer L2 and the 3rd recording layer L3.

If by host apparatus 90 receiving record request commands, be set at the programmable counter of CPU 40 corresponding to the start address of the program of the process flow diagram of Fig. 6, recording processing begins.

In first step 401, request sends to Drive and Control Circuit 26, makes CD with preset lines speed (or angular velocity) rotation, notice reproducing signal treatment circuit 28, and the record request order is received by host apparatus 90.

In the step 403 below, the user data (record data) that is stored in the host apparatus 90 of buffer RAM 34 is divided at the user data that writes down on the first recording layer L1, at user data that writes down on the second recording layer L2 and the user data that writes down on the 3rd recording layer L3.

In the step 405 below, request sends to Drive and Control Circuit 26, makes luminous point to form near the target location corresponding to specified address.Therefore, carry out seek operation.If do not need seek operation, skip this processing.

In the step 407 below, allow record.Therefore, user data is recorded on every layer of recording layer of CD 15 by scrambler 25, laser control circuit 24 and optic pick-up 23.

In the step 409 below, judge whether to finish record.When not finishing, the result of judgement negates to judge once more later at the fixed time.When finishing record, the result of judgement is sure, and stops recording processing.

Carry out the record of every layer of recording layer simultaneously, the time of recording processing can reduce.

Next, reproduction processes will be described.To explain the reproduction processes of when from host apparatus 90 reception reproduction requests, being undertaken with reference to Fig. 7 by optical disc apparatus 20.

The process flow diagram of Fig. 7 is used to a series of processing computings of explaining that CPU 40 carries out.Reproduction processes is carried out simultaneously from the first recording layer L1, the second recording layer L2 and the 3rd recording layer L 3.

If receive from host apparatus 90 and to reproduce request commands, be set at the programmable counter of CPU 40 corresponding to the start address of the program of the process flow diagram of Fig. 7, reproduction processes begins.

In first step 501, when CD 15 was sent to Drive and Control Circuit 26 with preset lines speed (or angular velocity) rotation, notice reproducing signal treatment circuit 28 reproduced request command and is received by host apparatus 90.

In the step 503 below, transmit to Drive and Control Circuit 26, make luminous point near target location, to form corresponding to specified address.Therefore, carry out seek operation.If do not need seek operation, skip this processing.

Allow in the step 505 below to reproduce.Therefore, the current data that write down on every layer of recording layer of CD 15 are reproduced by optic pick-up 23 and reproducing signal treatment circuit 28.

In the step 507 below, judge whether to finish reproduction.When not finishing, the result of judgement negates that the schedule time is judged once more later and judges.When finishing reproduction processes, judgement as a result the time sure, control moves on to step 509.

In step 509, the reproduction data of the reproduction data of the first recording layer L1, the second recording layer L2 and the reproduction data of the 3rd recording layer are connected, and the data transmission of acquisition is to host apparatus 90.End of reproduction is handled.Carry out the reproduction of every layer of recording layer simultaneously, the time that is used for reproduction processes can reduce.

In the optical disc apparatus 20 of this embodiment, processing unit is realized by program and the CPU 40 that reproducing signal treatment circuit 28, CPU40 carry out.Can realize with hardware according to some processing units that the program of CPU 40 realizes.In addition, all processing units can be realized with hardware.

(Lda, LDb LDc) realize with three holographic elements light source cell by three light sources in the optic pick-up 23 of this embodiment.

As mentioned above, in the optic pick-up 23 of present embodiment, the holographic element 71c of the light that the holographic element 71b of the light that the holographic element 71a of the light of edge+directions X diffraction light sources Lda edge+Z direction emission, edge+directions X diffraction light sources LDb edge+Z direction are launched and edge+directions X diffraction light sources LDc edge+Z direction are launched is arranged in from each light emitted to object lens on the light path of 60 light.Not reducing performance may obtain to minimize.

Can realize minimizing and do not reduce the access definition of the CD with a plurality of recording layers, because it has optic pick-up 23, this optic pick-up 23 can obtain to minimize according to the optical disc apparatus 20 of present embodiment, and performance is reduced.

According to the optical disc apparatus 20 of present embodiment,, thereby can carry out fast recording to CD and handle with a plurality of recording layers because the record of the record of the record of the first recording layer L1, the second recording layer L2 and the 3rd recording layer L3 almost can carry out simultaneously.

According to the optical disc apparatus 20 of present embodiment,, thereby can carry out quick reproduction processes to CD with a plurality of recording layers because the reproduction of the reproduction of the reproduction of the first recording layer L1, the second recording layer L2 and the 3rd recording layer L3 almost can carry out simultaneously.

In this embodiment, also may almost write down simultaneously and reproduce.For example, can record the information on the first recording layer L1 from the second recording layer L2 information reproduction.

In this embodiment, as shown in Figure 8, utilize holographic element 77a, holographic element 77b and holographic element 77c to replace half prism 76a and half prism 76b, holographic element 77c can be formed at holographic element 77b-the Z side.

Holographic element 77a is the volume hologram element, the light that its edge+directions X diffraction returns from the 3rd recording layer L3.Holographic element 77b is the volume hologram element, the light that its edge+directions X diffraction returns from the second recording layer L2.Holographic element 77c volume hologram element, the light that its edge+directions X diffraction returns from the first recording layer L1.

Photoelectric detector PDc is arranged in holographic element 77c's+the X side.That is, (77a, 77b 77c) have the Bragg condition of the light intensity of the diffraction light that differs from one another for maximum to three holographic elements.(77a, 77b 77c) have the function of the aberration that correction causes by the alternate position spike of recording layer and object lens 60 to holographic element.

In this case, (77c) (Pda, PDb PDc) realize optical detector unit with three photoelectric detectors for 77a, 77b by three holographic elements.Do not need each pin hole.

In this case, as shown in Figure 9, the photoelectric detector among Fig. 8 can be in aggregates.It in handling, is positioned easily in assembling.

As shown in figure 10, can use holographic element 78a, the holographic element 78b and the holographic element 78c that increase identical functions, replace above-mentioned holographic element 77a, holographic element 77b and holographic element 77c, change output radiation light and incident light divergence detection lens 58 and give the cylindrical lens 73 of incident light astigmatism.Make like this to remove and detect lens 58 and cylindrical lens 73, can obtain further miniaturization.

In this case, (78c) (PDa, PDb PDc) realize optical detector unit with three photoelectric detectors for 78a, 78b by three holographic elements.

Although it is 3 situation that the foregoing description has been described the light source number, the invention is not restricted to present embodiment.

Although the foregoing description has been explained the situation of whole holographic elements as holographic region, the subregion (for example, the grey color part among Figure 11) that can also use predefined each holographic element is as holographic region HA.

Particularly, consider the amount of movement of object lens 60 when following the trail of, also may use zone than the big 0.2-0.4mm of opening diameter of object lens 60 as holographic region.Therefore, can improve light utilization efficiency.

In this case, as shown in figure 12, when forming holographic element 71a, the information light of launching from light launching site S1 enters holographic element by aperture AP.

When such restriction holographic region, preferably increase the exposure of information light, make its exposure when utilizing whole holographic region.

Can give each holographic element beam shaping function.If volume hologram element apparatus forms just like the information light of the intensity distributions PB2 shown in Figure 13 B (similar to common Gaussian distribution), the variations in refractive index in the light source side will become big.As shown in FIG. 13A, have such possibility, the intensity distributions PB1 of diffraction light can become the part Gaussian distribution, can change the form of the luminous point that forms on CD, the characteristics of signals deterioration.

Shown in Figure 14 A, in order to obtain to have the diffraction light of intensity distributions PB3 (being similar to the Gaussian distribution of axial symmetry) as shown in Figure 14B, it is fine effectively to have the information light exposure of intensity distributions PB4 of the direction skew that separates with the light source Lr of reference light with the peak strength position.

Shown in Figure 15 A,, effectively be the information light exposure of the general big and intensity PB6 that separate with the light source Lr of reference light shown in Figure 15 B with intensity in order to obtain the diffraction light of uniform strength distribution PB5.Then, can adjust the edge strength (RIM intensity) of diffraction light by the distribution of adjustment information luminous intensity.

In the above-described embodiments, as shown in figure 16, can use additional in addition holographic element 72a, holographic element 72b and holographic element 72c, replace holographic element 71a, holographic element 71b, holographic element 71c, with the lens function of the divergence that changes the relative incident light of output radiation light.Therefore, collimation lens 52 can be removed, further miniaturization can be obtained.

In this case, light source cell is realized by three light sources (LDa, LDb, LDc) and three holographic elements (72a, 72b, 72c).

Next, the optic pick-up of one embodiment of the invention is described.

Present embodiment uses each light source in holographic cell replacement the foregoing description.Except that optic pick-up, the formation of optical disc apparatus is identical with the foregoing description, and the descriptions thereof are omitted at this.

As shown in figure 17, the optic pick-up 23 of present embodiment comprises three holographic cells (HUa, HUb, HUc), three holographic elements (171a, 171b, 171c), collimation lens 52, quarter-wave plate 55, object lens 60 and is used to drive the drive system (it is not shown) of object lens 60.

All holographic elements all are the volume hologram elements, and the light intensity that each holographic element has the diffraction light that differs from one another is maximum Bragg condition.Each holographic element has the function of the aberration that correction causes to the alternate position spike of object lens 60 by recording layer.

Holographic element 171 is arranged in holographic element 171a's+the X side, holographic element 171C be arranged in holographic element 171b+the X side.Holographic cell HUa has semiconductor laser a1, photoelectric detector a2 and polarization holograms a3, and be arranged in holographic element 171a-the Z side.

Semiconductor laser a1 court+Z direction emission P polarized light.Polarization holograms a3 is arranged in semiconductor laser a1's+the Z side, places like this to make it low to the diffraction efficiency of P polarization, to the diffraction efficiency height of S polarization.

Photoelectric detector a2 be arranged in semiconductor laser a1 near, receive the back light be polarized hologram a3 deflection.Therefore, the light from semiconductor laser a1 emission enters holographic element 171a by polarization holograms a3.

The light of holographic cell HUa is at the holographic region of holographic element 171a diffraction repeatedly, interreflection on boundary surface.The light of diffraction is launched from holographic element 171a court+directions X.

From the only diverging light of holographic element 171a diffraction, its equal from the optical axis that is positioned at collimation lens 52-the Z side and be positioned at the exit point S2 that shoots without hitting the target-X the light of virtual launching site S1a emission.

Although it enters holographic element 171b and holographic element 171c, it does not satisfy the Bragg condition of these holographic elements, sees through invariably from the light of holographic element 171a diffraction.

Holographic cell HUb comprises semiconductor laser b1, photoelectric detector b2 and polarization holograms b3.Holographic cell Hub is arranged in holographic element 171b's+the Z side.

Semiconductor laser b1 court-Z direction emission P polarized light.Polarization holograms b3 is arranged in semiconductor laser b1's-the Z side, and it is placed like this and makes it low to the diffraction efficiency of P polarization, to the diffraction efficiency height of S polarization.

Photoelectric detector b2 be arranged in semiconductor laser b1 near, receive the back light be polarized hologram b3 deflection.Therefore, the light from semiconductor laser b1 emission enters holographic element 171b by polarization holograms b3.

The light of holographic cell HUb is at the holographic region of holographic element 171b diffraction repeatedly, interreflection on boundary surface.Light court+directions X emission from holographic element 171b diffraction.

From the only diverging light of holographic element 171b diffraction, it equals from the light of the exit point S2 emission of shooting without hitting the target.Although it enters holographic element 171c, it does not satisfy its Bragg condition, sees through invariably from the light of holographic element 171b diffraction.

Holographic cell HUc comprises semiconductor laser c1, photoelectric detector c2 and polarization holograms c3.Holographic cell HUc is arranged in holographic element 171c's-the Z side.

Semiconductor laser c1 court+Z direction emission P polarized light.Polarization holograms c3 is arranged in semiconductor laser c1's+the Z side, places like this to make it low to the diffraction efficiency of P polarization, to the diffraction efficiency height of S polarization.

Photoelectric detector c2 be arranged in semiconductor laser c1 near, receive the back light be polarized hologram c3 deflection.Therefore, the light from semiconductor laser c1 emission enters holographic element 171c by polarization holograms c3.

The light of holographic cell HUc is at the holographic region of holographic element 171c diffraction repeatedly, interreflection on boundary surface.Light court+directions X emission from holographic element 171c diffraction.

From the only diverging light of holographic element 171c diffraction, its equal to be positioned at collimation lens 52 optical axis+the Z side and be positioned at the exit point S2 that shoots without hitting the target+light of the exit point S3a emission of shooting without hitting the target of X side.

Collimation lens 52 is arranged in holographic element 171c's+the X side.Each of quarter-wave plate 55 and object lens 60 is arranged similar to the above embodimentsly.

The operation of the optic pick-up 23 of following brief explanation present embodiment.

Enter holographic element 171a from face polarization (P polarization) light of semiconductor laser a1 emission by polarization holograms a 3,, enter collimation lens 52 by holographic element 171b and holographic element 171c by holographic element 171a diffraction.

Enter holographic element 171b from face polarization (P polarization) light of semiconductor laser b1 emission by polarization holograms b3,, enter collimation lens 52 by holographic element 171c by holographic element 171b diffraction.

Enter holographic element 171c from face polarization (P polarization) light of semiconductor laser c1 emission by polarization holograms c3,, enter collimation lens 52 by holographic element 171c diffraction.

Each diffraction light that sees through collimation lens 52 is converted to circularly polarized light by quarter-wave plate 55, and focuses on every layer of recording layer of CD 15 as sparklet by object lens 60.

In this embodiment, the light of semiconductor laser a1 focuses on the first recording layer L1, and the light of semiconductor laser b1 focuses on the second recording layer L2, and the light of semiconductor laser c1 focuses on the 3rd recording layer L3.That is to say,, on each layer recording layer, form luminous point so simultaneously if make each semiconductor laser simultaneously luminous.

Yet, not as the foregoing description, the position of each luminous point on the rapid direction of Z differ from one another (with reference to Figure 17).That is, the distance of the rotation center of each luminous point and CD 15 differs from one another.

Convert the circularly polarized light of opposite polarization to from the light of CD 15 reflection, the light that returns enters quarter-wave plate 55 by object lens 60, thereby converts the linearly polarized light (S polarization) perpendicular to external travel to.This light that returns enters holographic element 171c by collimation lens 52.

In holographic element 171c, the light component court-Z direction diffraction that returns from the 3rd recording layer L3.The back light that sees through holographic element 171c enters holographic element 171b.

In holographic element 171b, the light component court+Z direction diffraction that returns from the second recording layer L2.The back light that sees through holographic element 171b enters holographic element 171a.

In holographic element 171a, the light component court-Z direction diffraction that returns from the first recording layer L1.Be polarized hologram c3 deflection from the light of holographic element 171c diffraction (light component that returns from the 3rd recording layer L3), c2 receives by photoelectric detector.

Be polarized hologram b3 deflection from the light of holographic element 171b diffraction (light component that returns from the second recording layer L2), b2 receives by photoelectric detector.

Be polarized hologram a3 deflection from the light of holographic element 171a diffraction (light component that returns from the first recording layer L1), a2 receives by photoelectric detector.

Each photoelectric detector constitutes similar to the above embodimentsly, and each photoelectric detector outputs to reproducing signal treatment circuit 28 with the signal of light-receiving amount.

In the optical disc apparatus 20 of present embodiment, light source cell is realized by three light sources (a1, b1, c1) and three holographic elements (171a, 171b, 171c).Optical detector unit is realized by three holographic elements (171a, 171b, 171c) and three photoelectric detectors (a2, b2, c2).

As mentioned above, in the optic pick-up 23 of present embodiment, the light beam of volume hologram element 171a diffraction semiconductor laser a1, diffraction light being sent to object lens 60, and the light that returns by object lens 60 of diffraction semiconductor laser a1 emitted light beams.The light beam of volume hologram element 171b diffraction semiconductor laser b1, diffraction light being sent to object lens 60, and the light that returns by object lens 60 of diffraction semiconductor laser b1 emitted light beams.The light beam of volume hologram element 171c diffraction semiconductor laser c1, diffraction light being sent to object lens 60, and the light that returns by object lens 60 of diffraction semiconductor laser c1 emitted light beams.Therefore, the miniaturization of optic pick-up and optical disc apparatus can be than the further raising of the foregoing description.

In the present embodiment, the position of the exit point of shooting without hitting the target that makes each holographic element at the optical axis direction of collimation lens 52 with all different perpendicular to optical axis direction.Therefore, the incident angle of the incident angle of the incident angle of the light component that returns from the first recording layer L1 and each holographic element, the light component that returns from the second recording layer L2, the light component that returns from the 3rd recording layer L3 can change.

Therefore, can be to have only the light component that returns from the 3rd recording layer L3 by holographic element 171c diffraction, have only the light component that returns from the second recording layer L2 by holographic element 171b diffraction, have only the light component that returns from the first recording layer L1 by holographic element 171a diffraction.

That is to say that the stalling characteristic of the back light of each holographic element can improve.

In the present embodiment, differ from one another in the incident direction of the incident light of two holographic elements disposed adjacent one another, the width of holographic element is less than the width of holographic cell.

At quantity of light source is that 3 situation is described the foregoing description.Yet, the invention is not restricted to present embodiment.

Next, the optic pick-up of the embodiment of the invention is described.

Not as the foregoing description, present embodiment is suitable for forming simultaneously a plurality of luminous points on the identical recordings layer.Except data processing and signal processing and optic pick-up, the formation of optical disc apparatus is same as the previously described embodiments.Represent with identical Reference numeral that with the foregoing description counter element components identical the descriptions thereof are omitted at this.Suppose that CD 15 is the DVD type CDs with one deck recording layer.

As shown in figure 18, the optic pick-up 23 of present embodiment comprise three light sources (LDa, LDb, LDc), three holographic elements (172a, 172b, 172c), collimation lens 52, polarization beam apparatus 54, quarter-wave plate 55, object lens 60, detect lens 58, cylindrical lens 73, three photoelectric detectors (PDa, PDb, PDc) and be used to drive the drive system (not shown) of object lens 60.

Each light source has the semiconductor laser that emission wavelength is the laser beam of 660nm, has the identical characteristics of luminescence.From the maximum intensity output radiation direction of the laser beam of each light emitted all be+the Z direction.

Light source LDb in abutting connection with light source LDa+the X side arranges, light source LDc in abutting connection with light source LDb+the X side arranges.The light beam (P polarization) that is parallel to the plane of incidence of polarization beam apparatus 54 from each light emitted.

All holographic elements all are the volume hologram elements, and the light intensity that each holographic element has the diffraction light that differs from one another is maximum Bragg condition.

Holographic element 172a is arranged in light source LDa's+the X side, and the light of light source LDa enters holographic element 172a.The light of light source LDa reflects in boundary surface repeatedly at the holographic region of holographic element 172a diffraction repeatedly.Diffraction light court+directions X the emission of holographic element 172a.From the only diverging light of holographic element 172a diffraction, its equal from be positioned at ghosting point S2+light of the exit point Sb1 reflection of shooting without hitting the target of Z side.

Though it enters holographic element 172b and holographic element 172c,, see through invariably from the light of holographic element 172a diffraction because it does not satisfy these Bragg conditions.

Holographic element 172b is arranged in light source LDb's+the Z side, and the light of light source LDb enters holographic element 172b.The light of light source LDb is in the holographic region of holographic element 172b diffraction repeatedly, reflection repeatedly on boundary surface.Light court+directions X emission from holographic element 172b diffraction.

From the only diverging light of holographic element 172b diffraction, it equals from the light of the exit point S2 emission of shooting without hitting the target.Though it enters holographic element 172c, do not satisfy Bragg condition, see through invariably from the light of holographic element 172b diffraction.

Holographic element 172c is arranged in light source LDc's+the Z side, and the light of light source LDc enters holographic element 172c.The light of light source LDc is in the holographic region of holographic element 172c diffraction repeatedly, reflection repeatedly on boundary surface.Light court+directions X emission from holographic element 172c diffraction.From the only diverging light of holographic element 172c diffraction, its equal from be positioned at the exit point S2 that shoots without hitting the target-light of the exit point S3b reflection of shooting without hitting the target of Z side.

Each distance between the exit point of shooting without hitting the target depends on the optical magnification determined by collimation lens 52, object lens 60 and the track space of CD 15.

Collimation lens 52 is arranged in holographic element 172c's+the X side.Polarization beam apparatus 54, quarter-wave plate 55, object lens 60, detection lens 58 and cylindrical lens 73 are arranged similar to the above embodimentsly.

Photoelectric detector PDb is arranged in cylindrical lens 73-Z side, and is arranged on the optical axis of cylindrical lens 73.Photoelectric detector PDa is arranged in photoelectric detector PDb's+the X side, photoelectric detector PDc be arranged in photoelectric detector PDb-the X side.

The operation of the optic pick-up 23 of following brief explanation present embodiment.

By holographic element 172a diffraction, enter polarization beam apparatus 54 from face polarization (P polarization) light of light source LDa emission by holographic element 172b, holographic element 172c and collimation lens 52.

By holographic element 172b diffraction, enter polarization beam apparatus 54 from face polarization (P polarization) light of light source LDb emission by holographic element 172c and collimation lens 52.

Entered polarization beam apparatus 54 by holographic element 172c diffraction by collimation lens 52 from face polarization (P polarization) light of light source LDc emission.The major part of each diffraction light sees through polarization beam apparatus 54 invariably, converts circularly polarized light to by quarter-wave plate 55, and focuses on the recording layer of CD 15 as sparklet by object lens 60.

The light of light source LDb focuses on the position A2 on first track with the optical axis intersection of object lens, the light of light source LDa focuses in two tracks of first track, be positioned at first track-position A1b on second track of Z side, the light of light source LDc focuses in two tracks of first track, be positioned at first track+position A3b on the 3rd track of Z side.

Convert the circularly polarized light of opposite polarization to from the light of CD 15 reflection, the light that returns enters quarter-wave plate 55 by object lens 60, makes it convert linearly polarized light (S polarization) perpendicular to external travel to.And this back light enters polarization beam apparatus 54.

The back light that is polarized the reflection of beam splitter 54 edge-Z directions is received by each photoelectric detector by detecting lens 58 and cylindrical lens 73.

The light that returns from position A1b is received by photoelectric detector PDa, and the light that returns from position A2 is received by photoelectric detector PDb, and the light component that returns from position A3b is received by photoelectric detector PDc.

In the optic pick-up 23 of present embodiment,, on three tracks, can form three luminous points simultaneously if make each light source simultaneously luminous.Therefore, it is possible writing down simultaneously and reproduce three tracks.Also may carry out the record and the reproduction of CD 15 simultaneously.

In the optic pick-up 23 of present embodiment, light source cell is realized by three light sources (LDa, LDb, LDc) and three holographic elements (172a, 172b, 172c).

In the optic pick-up 23 of present embodiment, the light of holographic element 172a edge+directions X diffraction light sources LDa edge+Z direction emission, the light of holographic element 172b edge+directions X diffraction light sources LDb edge+Z direction emission, the light of holographic element 172c edge+directions X diffraction light sources LDc edge+Z direction emission, these holograms are arranged on the optical axis of each surface of light source to the light of object lens 60.Can realize minimizing, can not cause performance to descend.

According to the optical disc apparatus of present embodiment, almost can carry out record, the record on second track and the record on the 3rd track on first track simultaneously, can carry out recording processing to CD apace.

According to the optical disc apparatus of present embodiment, almost can carry out the reproduction of first track, the reproduction of second track and the reproduction of the 3rd track simultaneously, can carry out reproduction processes to CD apace.

In the present embodiment, can also almost write down simultaneously and reproduce.For example, from the second track information reproduction, in the first track record information.

Next, the optic pick-up of one embodiment of the invention is described.

Not as the foregoing description, present embodiment is characterised in that optic pick-up is suitable for access DVD and BD.

Except optic pick-up, data processing and signal processing, the formation of optical disc apparatus is same as the previously described embodiments.Represent with identical Reference numeral that with the foregoing description corresponding elements components identical the descriptions thereof are omitted at this.Suppose that CD 15 is DVD and BD, DVD is CD 15a, and BD is CD 15b.

As shown in figure 19, the optic pick-up 23 of present embodiment comprises two light sources (LDd, Lde), coupled lens 79, holographic element 173, collimation lens 73, polarization beam apparatus 54, the quarter-wave plate 55 that is used for two wavelength, opening wavelength filter plate 57, object lens 60, detects lens 58, cylindrical lens 73, Amici prism 76c and is used to drive the drive system (not shown) of two photoelectric detectors (PDa, PDb) and object lens 60.

When CD is BD, use light source LDd, this light source has the semiconductor laser that emission wavelength is the laser beam of 405nm.From the maximum intensity output radiation direction of light source LDd emitted laser bundle be+directions X.

Light source LDd is arranged in the position of its luminous point corresponding to the focal position of collimation lens 52.When CD is DVD, use light source LDe, this light source has the semiconductor laser that emission wavelength is the laser beam of 660nm.During from the maximum intensity output radiation direction of light source LDe emitted laser bundle+the Z direction.The light beam (P polarization) that is parallel to the plane of incidence of polarization beam apparatus 54 from each emission of light source LDd and light source LDe.

Coupled lens 79 is arranged in light source LDe's+the Z side, makes from the optical convergence of light source LDe emission.Holographic element 173 is volume hologram elements, it be arranged in light source LDd+the X side and be arranged in coupled lens 79+the Z side, the light that sees through coupled lens 79 enters holographic element 173.

The light that sees through coupled lens 79 is at the holographic region of holographic element 173 diffraction repeatedly, and on boundary surface interreflection.Light court+directions X emission from holographic element 173 diffraction.

From the only diverging light of holographic element 173 diffraction, its equal from the focal position that is positioned at collimation lens 52+light of the exit point S4 reflection of shooting without hitting the target of X side.

Object lens 60 are suitable for BD most.Consider BD and the DVD substrate thickness difference exit point S4 that determines to shoot without hitting the target.Thereby proofread and correct the aberration that produces by BD and DVD substrate thickness difference.

Collimation lens 52 is arranged in holographic element 173+X side.Polarization beam apparatus 54, quarter-wave plate 55, object lens 60, detection lens 58, cylindrical lens 73 are arranged similar to the aforementioned embodimently.

Opening wavelength filter plate 57 is arranged on the light path between quarter-wave plate 55 and the object lens 60, and it is designed to opening diameter can be according to wavelength variations.

Carry out the opening restriction of the light of light source LDd, make the numerical aperture (NA) of object lens 60 be set at 0.85.Carry out the opening restriction of the light of light source LDe, make the numerical aperture (NA) of object lens 60 be set at 0.65.

The servo driving and the object lens 60 of opening wavelength filter plate 57 integrally carry out.

Amici prism 76c is arranged in cylindrical lens 73-Z side, when CD is DVD, and its edge+directions X reflection back light.Photoelectric detector PDa is arranged in this Amici prism 76c's+the X side, receives the back light of Amici prism 76c reflection.Photoelectric detector PDb is arranged in Amici prism 76c's-the Z side, receives the back light that sees through Amici prism 76c.

The operation of the optic pick-up 23 of following brief explanation present embodiment.

When CD was DVD, face polarization (P polarization) light that reflects from light source LDe entered holographic element 173 by coupled lens 79, and it is by holographic element 173 diffraction, and collimated lens 52 convert the light beam of dispersing slightly to, enter polarization beam apparatus 54.See through polarization beam apparatus 54 invariably, it is converted to circularly polarized light beam by quarter-wave plate 55, carries out the opening restriction with opening wavelength filter plate 57, and most of diffraction light focuses on the recording layer of CD 15a as sparklet by object lens 60.

Convert the circularly polarized light of opposite polarization to from the light of CD 15a reflection, the light that returns enters quarter-wave plate 55 by object lens 60 and opening wavelength filter plate 57, thereby is converted into the linearly polarized light (S polarization) perpendicular to external travel.This light that returns enters polarization beam apparatus 54.

Light enters Amici prism 76c by detecting lens 58 and cylindrical lens 73, and 76c reflects by Amici prism, and is polarized the back light that beam splitter 54 edge-Z directions reflect and is received by photoelectric detector PDa.

When CD was BD, face polarization (P polarization) light of launching from light source LDd saw through holographic element 173 invariably, converts parallel beam to collimation lens 52, enters polarization beam apparatus 54.

See through polarization beam apparatus 54 invariably, convert circularly polarized light to, carry out the opening restriction, come most of light of self-focus lens 52 to focus on the recording layer of CD 15b as sparklet by object lens 60 with opening wavelength green glow dish 57 with quarter-wave plate 55.

Convert the circularly polarized light of opposite polarization to from the light of CD 15b reflection, the light that returns enters 1/4th plectrums 55 by object lens 60 and opening wavelength filter plate 57, thereby is converted into the linearly polarized light (S polarization) perpendicular to external travel.This light that returns enters polarization beam apparatus 54.

The back light that is polarized the reflection of beam splitter 54 edge-Z directions enters Amici prism 76c by detecting lens 58 and cylindrical lens 73, sees through Amici prism 76c invariably, and PDb receives by photoelectric detector.

Under the situation of DVD, the light that enters object lens 60 becomes emission light, because the aberration that difference between substrate thickness and the BD substrate thickness and wavelength cause is corrected.

In the optic pick-up 23 of present embodiment, (LDd LDe) realizes with holographic element 173 light source cell by two light sources.

According to the optic pick-up 23 of present embodiment, can realize miniaturization, can not cause performance to descend because edge+directions X diffraction from light source LDe+holographic element 173 of the light that the Z direction is launched is arranged in from the optical axis of each surface of light source to the light of object lens 60.

Miniaturization that can implement device can not reduce the access definition of several CDs that substrate thickness differs from one another, because according to the optical disc apparatus of present embodiment, it has the optic pick-up that can obtain miniaturization, can not cause performance to descend.

In the present embodiment, as shown in figure 20, replace Amici prism 76c, can use holographic element 77d.This holographic element 77d is the volume hologram element, when CD is CD 15a, and its edge+directions X diffraction back light.Holographic element 77d also has correction because substrate thickness causes the function of aberration.In this case, (PDa PDb) realizes with holographic element 77d optical detector unit by two photoelectric detectors.

Next, the optic pick-up of one embodiment of the invention is described.

Not as the foregoing description, present embodiment is characterised in that optic pick-up is suitable for any one of access CD, DVD and BD.

Except optic pick-up, data processing and signal processing, the formation of optic pick-up is same as the previously described embodiments.Represent with identical Reference numeral that with the foregoing description counter element components identical the descriptions thereof are omitted at this.Suppose that CD 15 is any one of CD, DVD and BD, DVD is CD 15a, and BD is CD 15b, and CD is CD 15c.

As shown in figure 21, optic pick-up 23 comprises three light source (LDd, LDe, LDf), two Amici prism (76d, 76e), three holographic elements (174a, 174b, 174c), polarization beam apparatus 54, the quarter-wave plate 55 that is used for three wavelength, diffraction optical element 56, opening wavelength filter plate 57, object lens 60, detect lens 58, three photoelectric detector (PDa, PDb, PDc), cylindrical lens 73 and be used to drive the drive system (not shown) of object lens 60.

When CD is BD, use light source LDd, it has with laser beam form emission wavelength is the semiconductor laser of the light of 405nm.From the maximum intensity output radiation direction of light source LDd emitted laser bundle be+the Z direction.

When CD is DVD, use light source LDe.It has with laser beam form emission wavelength is the semiconductor laser of the light of 660nm.From the maximum intensity output radiation direction of light source LDe emitted laser bundle be+the Z direction.

When CD is BD, use light source LDf.It has with laser beam form emission wavelength is the semiconductor laser of the light of 780nm.From the maximum intensity output radiation direction of light source LDf emitted laser bundle be-the Z direction.The light beam (P polarization) that is parallel to the plane of incidence of polarization beam apparatus 54 from each light emitted.

Holographic element 174a is arranged in light source LDd's+the Z side, and the light of light source LDd enters.The light of light source LDd is in the holographic region of holographic element 174a diffraction repeatedly, reflection repeatedly on boundary surface.Diffraction light court+directions X the emission of the diffraction element 174a of parallel beam.

Holographic element 174b holographic element 174a+the X side, it be arranged in light source LDf-the Z side, the light of light source LDf enters.The light of light source LDf is at the holographic region of holographic element 174b diffraction repeatedly, and reflection repeatedly on boundary surface.Only parallel from holographic element 174b diffraction, the emission of court+directions X.

Holographic element 174c is arranged in holographic element 174b's+the X side, it be arranged in light source LDe+the Z side, the light of light source LDe enters.The light of light source LDe is at the holographic region of holographic element 174c diffraction repeatedly, and reflection repeatedly on boundary surface.The diffraction light of holographic element 174c converts the light of dispersing a little that court+directions X is dispersed to.

That is to say, in the present embodiment, increase each holographic element and change the lens function of output radiation light to the divergence of incident light.

Polarization beam apparatus 54 is arranged in holographic element 174c's+the X side.Quarter-wave plate 55, object lens 60, detection lens 58 and cylindrical lens 73 are arranged similar to the above embodimentsly.

Suppose object lens 60 optimum BD dish.So, increase aberration, the aberration that produces owing to the substrate thickness difference when forming to proofread and correct hologram pattern for holographic element 174b and holographic element 174c.

Diffraction optical element 56 is arranged in quarter-wave plate 55+X side, and carries out aberration compensation corresponding to each wavelength.Opening wavelength filter plate 57 is arranged in diffraction optical element 56+X side, and carries out the opening restriction corresponding to each wavelength.The servo driving and the object lens 60 of each of diffraction optical element 56 and opening wavelength filter plate 57 integrally carry out.

Amici prism 76d is arranged in cylindrical lens 73-Z side, when CD is CD, and its edge+directions X reflection back light.Photoelectric detector PDc is arranged in this Amici prism 76d's+X side and receive the back light that is reflected by Amici prism 76d by Amici prism 76d.

Amici prism 76e is arranged in Amici prism 76d's-the Z side, when CD is DVD, and its edge+directions X reflection back light.Photoelectric detector PDa is arranged in this Amici prism 76e's+the X side, and receives the back light that is reflected by Amici prism 76e.Photoelectric detector PDb is arranged in Amici prism 76e's-the Z side, and receives the back light that sees through Amici prism 76e.

The operation of the optic pick-up 23 of following brief explanation present embodiment.

When CD was DVD, face polarization (P polarization) light that reflects from light source LDf entered holographic element 174b, and it is by holographic element 174b diffraction.The light of diffraction converts parallel beam to and sees through holographic element 174c invariably, makes it enter polarization beam apparatus 54.

Most of diffraction light sees through polarization beam apparatus 54 invariably, is converted to circularly polarized light by quarter-wave plate 55.Carry out aberration compensation with diffraction light sources element 56, carry out the opening restriction, make it focus on the recording layer of CD 15a as sparklet by object lens 60 with opening wavelength filter plate 57.

The reflected light of CD 15a converts the circularly polarized light of opposite polarization to, enters diffraction optical element 56 as back light by object lens 60 and opening wavelength filter plate 57.The back light that diffracted optical element 56 converts parallel beam to enters quarter-wave plate 55, thereby is converted into the linearly polarized light (S polarization) perpendicular to external travel.This back light enters polarization beam apparatus 54.

The back light that is polarized the reflection of beam splitter 54 edge-Z directions enters Amici prism 76d by detecting lens 58 and cylindrical lens 73, sees through Amici prism 76d invariably.Light enters Amici prism 76e, and 76e reflects by Amici prism, makes the light of reflection be received by photoelectric detector PDa.

When CD was BD, face polarization (P polarization) light of launching from light source LDd entered holographic element 174a.Light is by holographic element 174a diffraction and convert parallel beam to, and it sees through holographic element 174b and holographic element 174c invariably, enters polarization beam apparatus 54.

Most of diffraction light sees through polarization beam apparatus 54 invariably, is converted to circularly polarized light by quarter-wave plate 55.Light sees through diffraction optical element 56 invariably, carries out the opening restriction by opening wavelength filter plate 57, focuses on the recording layer of CD 15b as sparklet by object lens 60.

Convert the circularly polarized light of opposite polarization to from the light of CD 15b reflection, enter diffraction optical element 56 by object lens 60 and opening wavelength filter plate 57 as back light.The back light that diffracted optical element 56 converts parallel beam to enters quarter-wave plate 55, thereby is converted into the linearly polarized light (S polarization) perpendicular to external travel.This back light enters polarization beam apparatus 54.

The back light that is polarized the reflection of beam splitter 54 edge-Z directions enters Amici prism 76d by detecting lens 58 and cylindrical lens 73.Light changes ground and sees through Amici prism 76d, enters Amici prism 76e.Light sees through Amici prism 76e invariably, and is received by photoelectric detector PDb.

When CD was CD, face polarization (P polarization) light of launching from light source LDe entered holographic element 174c.Light is converted to the light beam of dispersing a little by holographic element 174c diffraction, and enters polarization beam apparatus 54.

Most of diffraction light sees through polarization beam apparatus 54 invariably, is converted to circularly polarized light by quarter-wave plate 55.Carry out aberration compensation by diffraction optical element 56, carry out the opening restriction by opening wavelength filter plate 57, light focuses on the recording layer of CD 15c as sparklet by object lens 60.

Convert the circularly polarized light of opposite polarization to from the light of CD 15c reflection, enter diffraction optical element 56 by object lens 60 and opening wavelength filter plate 57 as back light.The light that returns from diffraction optical element 57 enters quarter-wave plate 55, thereby is converted into the linearly polarized light (S polarization) perpendicular to external travel.This back light enters polarization beam apparatus 54.

The back light that is polarized the reflection of beam splitter 54 edge-Z directions enters Amici prism 76d by detecting lens 58 and cylindrical lens 73.Light is reflected by Amici prism 76d, and is received by photoelectric detector PDc.

In the optic pick-up 23 of present embodiment, (LDf) (174a, 174b 174c) realize light source cell with three holographic elements for LDd, LDe by three light sources.

In the optic pick-up 23 of present embodiment, the holographic element 174b of the holographic element 174c of the light of the holographic element 174a of the light of edge+directions X diffraction light sources LDd edge+Z direction emission, edge+directions X diffraction diffraction light sources LDe edge+Z direction emission and the light of edge+directions X diffraction light sources LDf edge-Z direction emission is arranged on the optical axis of each surface of light source to the light of object lens 60.Can realize miniaturization, can not cause performance to descend.

In the present embodiment, each holographic element all increases lens function, and collimation lens can be removed, and can obtain the miniaturization of optic pick-up and optical disc apparatus.

In the present embodiment, the incident direction of the incident light of two holographic elements adjacent one another are differs from one another, and the width of holographic element is less than the width of light source.

In the present embodiment, as shown in figure 22, can replace Amici prism 76d, can replace Amici prism 76e with holographic element 77f with holographic element 77e, holographic element 77g can be arranged on holographic element 77f-the Z side.This holographic element 77e is the volume hologram element, when CD is CD, and its edge+directions X diffraction back light.Volume hologram element during holographic element 77f, when CD is DVD, its edge+directions X diffraction back light.Holographic element 77g is the volume hologram element, when CD is BD, and its edge+directions X diffraction back light.Photoelectric detector PDb is arranged in holographic element 77g's+the X side.

(77e, 77f 77g) have the Bragg condition of the light intensity of the diffraction light that differs from one another for maximum to holographic element.(77e, 77f 77g) have the function of correction by the aberration of substrate thickness difference generation to holographic element.(77e, 77f 77g) have given astigmatism for diffraction light to holographic element.In this case, (PDc) (77e, 77f 77g) realize optical detector unit with three holographic elements for PDa, PDb by the 3rd photoelectric detector.

Next, the optic pick-up of one embodiment of the invention is described.

Present embodiment is characterised in that, replaces each light source of the foregoing description with holographic cell.Represent with identical Reference numeral that with the foregoing description counter element components identical the descriptions thereof are omitted at this.

As shown in figure 23, the optic pick-up 23 of present embodiment comprises three holographic cell (HUd, HUe, HUff), three holographic element (175a, 175b, 175c), collimation lens 52, the quarter-wave plate 55 that is used for three wavelength, diffraction optical element 56, opening wavelength filter plate 57, object lens 60 and be used to drive the drive system (not shown) of object lens 60.

Holographic element 175b is arranged in holographic element 185a's+the X side, holographic element 175c be arranged in holographic element 175b+the X side.The light intensity that each holographic element has the diffraction light that differs from one another is maximum Bragg condition.

When CD is BD, use holographic cell HUd, it has the semiconductor laser d1 that emission wavelength is the laser beam of 405nm, photoelectric detector d2 and polarization holograms d 3, and be arranged in holographic element 175a-the Z side.Semiconductor laser d1 court+Z direction emission P polarized light.

Polarization holograms d3 is arranged in semiconductor laser d1's+the Z side, and it is set to and makes it low to the diffraction efficiency of P polarization, to the diffraction efficiency height of S polarization.Photoelectric detector d2 is arranged near the semiconductor laser d1, receives the back light that is polarized hologram d3 deflection.Therefore, the light from semiconductor laser d1 emission enters holographic element 175a by polarization holograms d3.

The light of holographic cell HUd is in the holographic region of holographic element 175a diffraction repeatedly, reflection repeatedly on boundary surface.Light court+directions X emission from holographic element 175a diffraction.

From the only diverging light of holographic element 175a diffraction, equal from the light of the exit point S2 emission of shooting without hitting the target.Although enter holographic element 175b and holographic element 175c from the light of holographic element 175a diffraction, it does not satisfy Bragg condition and sees through them invariably.

When CD is DVD, use holographic cell HUe, it has semiconductor laser e1, photoelectric detector e2 and the polarization holograms e3 that emission wavelength is the laser beam of 660nm.Holographic cell HUe is arranged in holographic element 175b's+the Z side.

Semiconductor laser e1 court-Z direction emission P polarized light.Polarization holograms e3 is arranged in semiconductor laser e1's-the Z side, and it is set at and makes it low to the diffraction efficiency of P polarization, to the diffraction efficiency height of S polarization.Photoelectric detector e2 be arranged in semiconductor laser e3 near, receive the back light be polarized hologram e3 deflection.Therefore, the light from semiconductor laser e1 emission enters holographic element 175 by polarization holograms e3.

The light of holographic cell HUe is in the holographic region of holographic element 175b diffraction repeatedly, reflection repeatedly on boundary surface.Light court+directions X emission from holographic element 175b diffraction.

From the only diverging light of holographic element 175b diffraction, equal from the light of the exit point S2 emission of shooting without hitting the target.Although enter holographic element 175c from the light of holographic element 17b diffraction, it does not satisfy Bragg condition, and light sees through holographic element 175c invariably.

When CD is CD, use holographic cell HUf, it has semiconductor laser f1, photoelectric detector f2 and the polarization holograms f3 that transmitted wave is the laser beam of 780nm.This holographic cell HUf is arranged in holographic element 175c's-the Z side.

Semiconductor laser f1 court+Z direction emission P polarized light.Polarization holograms f3 is arranged in semiconductor laser f1's+the Z side, and it is set to and makes it low to the diffraction efficiency of P polarization, to the diffraction efficiency height of S polarization.Photoelectric detector f2 is arranged near the semiconductor laser f1, receives the back light that is polarized hologram f3 deflection.Therefore, the light from semiconductor laser f1 emission enters holographic element 175c by polarization holograms f3.

The light of holographic cell HUf is in the holographic region of holographic element 175c diffraction repeatedly, reflection repeatedly on boundary surface.Light court+directions X emission from holographic element 175c diffraction.From the only diverging light of holographic element 175c diffraction, equal from the light of the exit point S2 emission of shooting without hitting the target.

Object lens 60 are suitable for BD most.When hologram pattern forms, for the aberration of proofreading and correct the aberration that is produced by the substrate thickness difference of BD and DVD is added to holographic element 175b.When hologram pattern forms, for the aberration of proofreading and correct the aberration that is produced by the substrate thickness difference of BD and CD is added to holographic element 175c.

Collimation lens 52 is arranged in holographic element 175c's+the X side.Quarter-wave plate 55, diffraction optical element 56, opening wavelength filter plate 57 and object lens 60 are arranged similar to the above embodimentsly.

The operation of the optic pick-up 23 of following brief explanation present embodiment.

When CD was DVD, the plane polarized light of launching from semiconductor laser e1 entered holographic element 175b by polarization holograms e3, by holographic element 175b diffraction, enters collimation lens 52 by holographic element 175c.

Light converts circularly polarized light to quarter-wave plate 55, carry out aberration compensation with diffraction light sources element 56, carry out the opening restriction with opening wavelength filter plate 57, the diffraction light that collimated lens 52 convert parallel beam to focuses on the recording layer of CD 15a as sparklet by object lens 60.

Convert the circularly polarized light of opposite polarization to from the light of CD 15a reflection, it enters diffraction optical element 56 as back light by object lens 60 and opening wavelength filter plate 57.

The back light that diffracted optical element 56 converts parallel beam to enters quarter-wave plate 55, makes it convert linearly polarized light perpendicular to external travel to.This back light enters holographic element 175c by collimation lens 52, sees through holographic element 175c invariably, and enters holographic element 175b.

In holographic element 175b, back light edge+Z direction diffraction.Be polarized hologram e3 deflection from the light of holographic element 175b diffraction, e2 receives by photoelectric detector.

When CD was the BD dish, the plane polarized light of launching from semiconductor laser d1 entered holographic element 175a by polarization holograms d3, enters collimation lens 52 by holographic element 175b and holographic element 175c.

Light converts circularly polarized light to quarter-wave plate 55, see through diffraction optical element 56 invariably, carry out the opening restriction with opening wavelength filter plate 57, the diffraction light that collimated lens 52 convert parallel beam to focuses on the recording layer of CD 15b by object lens 60 as sparklet.

Convert the circularly polarized light of opposite circumference to from the light of CD 15b reflection, enter diffraction optical element 56 by object lens 60 and opening wavelength filter plate 57 as back light.

The back light that diffracted optical element 56 converts parallel beam to enters quarter-wave plate 55, makes it convert linearly polarized light perpendicular to external travel to.This back light enters holographic element 175c by collimation lens 52, sees through holographic element 175b invariably and enters holographic element 175a.

In holographic element 175a, back light edge-Z direction diffraction.Be polarized hologram d3 deflection from the light of holographic element 175a diffraction, d2 receives by photoelectric detector.

When CD was CD, the plane polarized light of launching from semiconductor laser f1 entered holographic element 175c by polarization holograms f3, by holographic element 175c diffraction, enters collimation lens 52.

Light converts circularly polarized light to quarter-wave plate 55, carry out aberration compensation with diffraction optical element 56, carry out the opening restriction with opening wavelength filter plate 57, the diffraction light that collimated lens 52 convert parallel beam to focuses on the recording layer of CD 15c by object lens 60 as sparklet.

Convert the circularly polarized light of opposite circumference to from the light of CD 15c reflection, enter diffraction optical element 56 by object lens 60 and opening wavelength filter plate 57 as back light.

The back light that diffracted optical element 56 converts parallel beam to enters quarter-wave plate 55, makes it convert linearly polarized light perpendicular to external travel to.This back light enters holographic element 175c by collimation lens 52.

In holographic element 175c, back light edge-Z direction diffraction.Be polarized hologram f3 deflection from the light of holographic element 175c diffraction, f2 receives by photoelectric detector.

In the optical disc apparatus 20 of present embodiment, (f1) (175a, 175b 175c) realize light source cell with three holographic elements for d1, e1 by three light sources.(175c) (d2, e2 f2) realize optical detector unit with three photoelectric detectors for 175a, 175b by three holographic elements.

As mentioned above, in the optic pick-up 23 of present embodiment, be provided with volume hologram element 175a, 175b and 175c, the light beam of volume hologram element 175a diffraction semiconductor laser d1, light beam is sent to object lens 60, and the light that returns by object lens 60 from semiconductor laser d1 emitted light beams of diffraction, the light beam of volume hologram element 175b diffraction semiconductor laser e1, light beam is sent to object lens 60, and the light that returns by object lens 60 from semiconductor laser e1 emitted light beams of diffraction, the light beam of volume hologram element 175c diffraction semiconductor laser 1, light beam being sent to object lens 60, and the light that returns by object lens 60 from semiconductor laser f1 emitted light beams of diffraction.Can realize miniaturization, can not cause performance to descend.

In the present embodiment, the incident direction of the incident light of holographic element disposed adjacent one another differs from one another, and the width of holographic element is less than the width of holographic cell.

Next, the optic pick-up of one embodiment of the invention is described.

The optic pick-up 23 of present embodiment is to be suitable for launching simultaneously laser to three layers of recording layer of CD 15 and receive the optic pick-up of the detection light beam of three layers of recording layer simultaneously.

Suppose that CD 15 is three layers of dish that have first recording layer (L1), second recording layer (L2) and the 3rd recording layer (L3) from the order of the light incident side of laser beam, as shown in figure 24, CD 15 for example is a DVD type information recording carrier.

As shown in figure 24, the optic pick-up 23 of present embodiment comprises three light source (Ld1, Ld2, Ld3), collimation lens 52, two holographic elements (H1, H3), polarization beam apparatus 54, quarter-wave plate 55, object lens 60, collector lens 58, cylindrical lens 73, two half prism (76a, 76b), three pin hole (75a, 75b, 75c), three photoelectric detectors (Pd1, Pd2, Pd3) and be used to drive the drive system (not shown) of object lens 60.

Each emission wavelength of three light sources is the laser beam of 660nm.Light source Ld2 is arranged on the optical axis of collimation lens 52, light source Ld1 be arranged in light source Ld2+the Z side, light source Ld3 be arranged in light source Ld2-the Z side.Each light source is for example launched the P polarized light.From the maximum intensity output radiation direction of the laser beam of three light emitted all be+directions X.

Collimation lens 52 is arranged in each light source+X side, and will convert common parallel beam from the light of each light emitted to.In this case, when from the light transmission collimation lens 52 of light source Ld1 emission, it converts the parallel beam that tilts a little along directions X to, and this parallel beam clockwise direction vertically tilts a little.When from the light transmission collimation lens 52 of light source Ld3 reflection, it converts the parallel beam that tilts a little along directions X to, and this parallel beam counter clockwise direction vertically tilts a little.When from the light transmission collimation lens 52 of light source Ld2 emission, it converts parallel beam to.

Holographic element all is the volume hologram element, and it is described in front with reference to Fig. 3.Photopolymer can be used for the material of each holographic element.This photopolymer is the organic polymer recording materials, and it is used for WORM (write-once repeatedly reads) type holographic memory as a rule.Its performance significantly improves by processing in recent years, and thickness is the photopolymer excellent optical performance of hundreds of micron, and achieves success in the material development of the contraction of following when reducing to write down.

For example, the low-shrinkage photopolymer comprises two kinds of chemical property, and the low-shrinkage photopolymer utilizes the polymerization of kation cyclopolymerization mechanism.As a result, high photo sensitivity and high power capacity recording density can be compatible.By utilizing this photopolymer that is used for the volume hologram element, can realize efficient and high precision light beam synthesizer and luminous flux tripping device.

In addition, many thermoplasticss are used for WORM type holographic memory.For thermoplastics, colorant is mixed with each wavelength light by this thermoplastics, and record and reproduction are possible.For manufacturer, the processing of several millimeters thick is possible, its excellent optical performance, and achieve success in the development of the thermoplastics of the contraction of when reducing to write down, following.As a result, high photo sensitivity and high power capacity recording density can be compatible.Because thermoplastics like this, material itself are suitable for the volume hologram element as substrate, thereby can realize that beam synthesizing device and luminous flux tripping device are several millimeters thick, and efficient and high precision.

For example, each holographic element of being made by thermoplastics utilizes the method for the relevant exposure of 2 known light beams to form.

Holographic element H1 is arranged in collimation lens 52+X side, is set to from the light of light source Ld1 by collimation lens 52 to satisfy Bragg condition.Therefore, pass through the light of collimation lens 52 by holographic element H1 edge+directions X diffraction from light source Ld1.Convert the light beam of assembling a little to from the diffraction light (not shown Figure 24) of holographic element H1 emission, when the light of light source Ld2 focuses on the recording layer L2, design convergence in advance, make the light of light source Ld1 can focus on the recording layer L1 by optical parametric.

The light of the light of light source Ld2 and light source Ld3 does not satisfy the Bragg condition of holographic element H1 by collimation lens 52, sees through holographic element H1 invariably.

Holographic element H3 is arranged in holographic element H1's+the X side, and setting makes and can satisfy Bragg condition through the light of holographic element H1 invariably from light source Ld3 like this.Therefore, see through the light of holographic element H1 invariably by holographic element H3 edge+directions X diffraction from light source Ld3.

Convert the light beam of dispersing a little to from the diffraction light (not shown Figure 24) of holographic element H3 emission, when the light of light source Ld2 focuses on the recording layer L2, design divergence in advance, make the light of light source Ld3 can focus on the recording layer L3 by optical parametric.

From light source Ld2 emission, see through and see through holographic element H1 invariably and do not satisfied the Bragg condition of holographic element H3 by the light of holographic element H1 diffraction, see through holographic element H3 invariably.

The Bragg condition of holographic element H1 and holographic element H2 differs from one another, and holographic element is all arranged along directions X.Each angular magnification of each holographic element (=sin (output radiation angle)/sin (incident angle)) is less than 1.Holographic element H3 is arranged in collimation lens 52+X side, holographic element H1 be arranged in holographic element H3+the X side.

Polarization beam apparatus 54 is arranged in holographic element H3's+the X side.These polarization beam apparatus 54 reflection coefficients are different and different according to entering polarized state of light.For example, the reflection coefficient of 54 pairs of P polarizations of polarization beam apparatus is little, and this setting makes it just big to the reflection coefficient of S polarization.Therefore, can see through polarization beam apparatus 54 from most of light of each light source by holographic element H3.

Quarter-wave plate 55 is arranged in polarization beam apparatus 54+X side, incident light is provided the optical phase difference of 1/4 wavelength.Object lens 60 are arranged in this quarter-wave plate 55+X side, and the light by quarter-wave plate is focused.

The light of light source Ld1 focuses on the first recording layer L1, and the light of light source Ld2 focuses on second recording layer, and the light of light source Ld3 focuses on the 3rd recording layer L3.That is to say,, on three layers of recording layer of CD 15, can form luminous point simultaneously if make light source simultaneously luminous.

Collector lens 58 is arranged in polarization beam apparatus 54-Z side, and the light that returns from CD 15 that is polarized the reflection of beam splitter 54 edge-Z directions is become converging light.

Cylindrical lens 73 is arranged in collector lens 58-Z side, astigmatism is given the light of collector lens 58.Half prism 76a is arranged in cylindrical lens 73-Z side, the contained light component that returns from the 3rd recording layer L3 in the edge+directions X reflection light by cylindrical lens 73.

Half prism 76b is arranged in half prism 76a's-the Z side, the contained light component that returns from the second recording layer L2 in the light of edge+directions X reflecting ﹠ transmitting half prism 76a.

Pin hole 75a is arranged in half prism 76a's+the X side, is entered by half prism 76a reflected light.Light by this pin hole 75a is received by photoelectric detector Pd3.Therefore, the light that is received by Photoelectric Detection Pd3 mainly is the light that returns from the 3rd recording layer L3.

Pin hole 75b is arranged in half prism 76b's+the X side, and the light that is reflected by half prism 76b enters.Light by this pin hole 75b is received by photoelectric detector Pd2.Therefore, the light that is received by photoelectric detector Pd2 mainly is the light that returns from the second recording layer L2.

Pin hole 75c is arranged in half prism 76b's-the Z side, and the light by half prism 76b enters.Light by this pin hole 75c is received by photoelectric detector Pd1.Therefore, the light that is received by photoelectric detector Pd1 mainly is the light that returns from the first recording layer L1.

Drive system has the very little mobile focus actuator that is used for driving along focus direction object lens 60, and focus direction is the optical axis direction of object lens 60 and is used for along following the trail of the very little mobile tracking actuator that direction drives object lens 60.

The operation of the optic pick-up 23 of following brief explanation present embodiment.

After the collimated lens 52 of face polarization (P polarization) light from light source Ld1 emission convert parallel beam to,, see through holographic element H3 invariably, and enter polarization beam apparatus 54 by holographic element H1 diffraction.

After the collimated lens 52 of face polarization (P polarization) light from light source Ld2 emission convert parallel beam to, see through holographic element H1 and holographic element H3 invariably, and enter polarization beam apparatus 54.

After the collimated lens 52 of face polarization (P polarization) light from light source Ld3 emission convert parallel beam to, see through holographic element H1 invariably, by holographic element H3 diffraction, and enter polarization beam apparatus 54.

The most of light that enters polarization beam apparatus 54 sees through polarization beam apparatus 54 invariably, is converted to circularly polarized light by quarter-wave plate 55, focuses on by object lens 60 on every layer of recording layer of CD 15.

The light that is received by every layer of recording layer of CD 15 converts the circularly polarized light of opposite polarization to, and the light that returns enters quarter-wave plate 55 by object lens 60, makes it convert linearly polarized light (S polarization) perpendicular to external travel to.This back light enters polarization beam apparatus 54.

The back light that is polarized the reflection of beam splitter 54 edge-Z directions enters half prism 76a by optically focused prism 58 and cylindrical lens 73.Light is reflected by half prism 76a, and the light component that returns from the 3rd recording layer L3 contained in back light is received by photoelectric detector Pd3 by pin hole 75a.

The back light that sees through half prism 76a enters half prism 76b.Light is reflected by half prism 76b, and the contained light that returns from the second recording layer L2 is received by photoelectric detector Pd2 by pin hole 75b in giving back light.

The back light that sees through half prism 76b is received by photoelectric detector Pd1 by pin hole 75c.

Each pin hole is set, so that crosstalking between the recording layer of removal dish.

The formation of each photoelectric detector comprises two or more photoelectric detector components (or two or more light receiving areas), it is as the general optic disc device, and output contains dither signal information, reproduces the signal of data message, focus error message, tracking error information etc.Each photoelectric detector (or each photoelectricity reception area) produces signal respectively according to the light-receiving amount of opto-electronic conversion, and signal is outputed to feedback signal processing circuit 28.

Return with reference to Fig. 1, feedback signal processing circuit 28 obtains servosignal (focus error signal, tracking error signal), address information, synchronizing information, RF signal etc. based on the output (two or more photoelectric conversion signals) of each photoelectric detector of optic pick-up 23.

The servosignal that obtains is output to control circuit 26, and address information outputs to CPU 40, and synchronizing signal outputs to scrambler 25, Drive and Control Circuit 26 etc.

28 pairs of RF signals of feedback signal processing circuit carry out decoding processing, error detection process etc.When detecting error, it carries out correction processing, stores the signal of acquisition as feedback data by buffer manager for use 37 in buffering Ram34.Contained address information outputs to CPU 40 in return data.

Based on the servosignal of feedback signal processing circuit 28, Drive and Control Circuit 26 produces the drive signal of drive system, and signal is outputed to optic pick-up 23.Therefore, carry out Tracing Control and focus control.

Drive and Control Circuit 26 produces the drive signal of driving tracking motor 21 and the drive signal of drives spindle motor 22 based on the instruction of CPU 40.The drive signal output road tracking motor 21 and the spindle motor 22 of each motor.

The data (record data) that write down on CD 15, the data of reproducing from CD 15 (reproduction data) temporarily are stored in the buffer RAM 34.The I/O of the data of buffer RAM 34 is by buffer manager for use 37 management.

Based on the instruction of CPU 40, scrambler 25 carries out the modulation of data, the interpolation of error correction code etc. by the record data of buffer manager for use 37 acquisition storages in buffer RAM 34, produces the write signal of CD 15.The write signal that produces outputs to laser control circuit 24.

The emissive power of each light source of laser control circuit 24 control optic pick-ups 23.For example, under the situation of record, based on the light characteristic of write signal, record condition, each light source etc., the drive signal of each light source is produced by laser control circuit 24.

Interface 38 is and host apparatus 90 (for example, PC) two-way exchange interface.It is based on standard interface, such as ATAPI (AT Attachment Packet Interface accessory bag attaching mouth), SCSI (minicomputer interface) and USB (universal serial bus).The various programs of describing with decodable code in CPU 40, the light characteristic of each light source etc. are stored in the flash memory 39.

In the optic pick-up 23 of present embodiment, (Ld3) (H1 H3) realizes light source cell with two holographic elements for Ld1, Ld2 by three light sources.

Optic pick-up 23 according to present embodiment, three light source (Ld1, Ld2, Ld3) and the holographic element H1 that sees through invariably, the light of edge+directions X diffraction light sources Ld1 not, the light of diffraction light sources Ld2 and Ld3, see through the light edge+directions X diffraction of the light source Ld3 of holographic element H1 invariably, it has the light that makes light source Ld2 and sees through the holographic element H3 that the diffraction light of holographic element H1 sees through invariably from light source Ld2, holographic element H1 and holographic element H3, the plane of incidence of incident light is parallel with the output radiation face of diffraction light, the volume hologram element along three light sources (Ld1, Ld2, Ld3) and the optical axis between the object lens 66 arrange.Therefore, the utilization factor that need not reduce light can make the illuminator miniaturization, obtains miniaturization thereby performance is reduced.

It is possible need not reducing the access definition of the CD with two or more recording layers and obtain miniaturization.

According to the optical disc apparatus 20 of present embodiment,, thereby can carry out recording processing fast to CD because the record in the first recording layer L1, the record in the second recording layer L2 and the record in the 3rd recording layer L3 almost can carry out simultaneously.

According to the optical disc apparatus 20 of present embodiment,, thereby can carry out reproduction processes fast because the reproduction of the reproduction of the reproduction of the first recording layer L1, the second recording layer L2 and the 3rd recording layer L3 almost can carry out simultaneously.

In the above-described embodiments, can almost write down simultaneously and reproduce.For example, from the renewable information of the second recording layer L2, recorded information on the first recording layer L.

Next, the optic pick-up of one embodiment of the invention is described.

In the present embodiment, as shown in figure 25, replace half prism 76a and half prism 76b, (R3 R1) can be arranged on the optical axis of the back light between polarization beam apparatus 54 and the collector lens 58 two holographic elements.

Holographic element R3 and holographic element R1 have the Bragg condition that differs from one another, and the both is the plane of incidence of incident light and the parallel volume hologram element of output radiation face of diffraction light.

Holographic element R3 is arranged in polarization beam apparatus 54-Z side, and the contained light settings that returns from the 3rd recording layer L3 is for satisfying Bragg condition in being polarized the back light of beam splitter 54 edge-Z directions reflections.

Therefore, in back light the contained light that returns from the 3rd recording layer L3 by holographic element R3 diffraction.

Tilt a little from the diffraction light (not shown among Figure 25) of this holographic element R3 emission and the optical axis of collector lens 58.Holographic element R3 has the function of the aberration that correction produces to the difference of object lens 60 to the position of object lens 60 and the 3rd recording layer L3 by the position of the second recording layer L2.

Be polarized the light component that returns from the first recording layer L1 that comprises in the back light of beam splitter 54 edge-Z directions reflections and do not satisfy the Bragg condition of holographic element R3, just see through holographic element R3 invariably from the light component that the second recording layer L2 returns.

Holographic element R1 is arranged in holographic element R3's-the Z side, and the contained light component that returns from the first recording layer L1 is set at and satisfies Bragg condition in seeing through the back light of holographic element R3.Therefore, in back light the contained light that returns from the first recording layer L1 by holographic element R1 diffraction.

Tilt a little from the diffraction light (not shown Figure 25) of holographic element R1 emission and the optical axis of convergent lens 58.

Holographic element R1 has correction because the function of the position of the object lens 60 and the first recording layer L1 to the aberration of the difference generation of object lens 60 arrived in the position of the second recording layer L2.

At the Bragg condition that sees through holographic element R3 and the contained light component that returns from the second recording layer L2 does not satisfy holographic element R1 from the back light of holographic element R3 diffraction, just see through holographic element R1 invariably.

Therefore, each photoelectric detector can be arranged in identical scope, can produce normal focus signal at very little check point.That is, photoelectric detector Pd3 be arranged in photoelectric detector Pd2-the X side, photoelectric detector Pd1 be arranged in photoelectric detector Pd2+the X side.

In this case, (R3, R1) (Pd1, Pd2 Pd3) realize optical detector unit with three photoelectric detectors by holographic element.Do not need each pin hole.In this case, holographic element R1 can be arranged in polarization beam apparatus 54-the Z side, holographic element R3 can be arranged in holographic element R1-the Z side.

Therefore, detection system can miniaturization, does not reduce light utilization efficiency, thereby can realize the miniaturization of optic pick-up, can not cause performance to descend in addition.

Though it is 3 situation that the foregoing description is explained the light source number, the invention is not restricted to present embodiment.Though the foregoing description is explained the situation of three layers of recording layer with CD 15, the invention is not restricted to present embodiment.

In the above-described embodiments, high-order spherical aberration can be added in the information light that uses when forming each holographic element.Spherical aberration corrector also is possible fully.The aberration that causes because of the skew of object lens 60 when the Tracing Control can be added in the information light.In this case, corresponding to light source Ld2, can provide the holographic element that increases above-mentioned aberration compensation function.

Next, the optic pick-up of one embodiment of the invention is described.

Present embodiment is characterised in that, utilizes holographic cell to replace each light source in the foregoing description respectively.

Except optic pick-up, the formation of optical disc apparatus is same as the previously described embodiments.

As shown in figure 26, the optic pick-up 23 of present embodiment comprises three holographic cell (HU1, HU2, HU3), two holographic elements (H11, H31), collimation lens 52, quarter-wave plate 55, object lens 60 and be used to drive the drive system (not shown) of object lens 60.

Each holographic cell is respectively the holographic cell with identical characteristics.Shown in Figure 27 A, holographic cell HU2 has light source k2, photoelectric detector m2 and the polarization holograms n2 that emission wavelength is the laser beam of 660nm, and this holographic cell is arranged on the optical axis of collimation lens 52.

Light source k2 emission P polarized light.Polarization holograms n2 is arranged in light source k2's+the X side, and it is set to and makes it little to the reflection coefficient of P polarization, and is big to the reflection coefficient of S polarization.

Photoelectric detector m2 be arranged in light source k2 near, receive the back light be polarized hologram n2 deflection.Therefore the light from light source k2 emission enters collimation lens 52 by polarization holograms n2.

Holographic cell HU1 has light source k1, photoelectric detector m1 and the polarization holograms n2 that emission wavelength is the laser beam of 660nm shown in Figure 27 B, this holographic cell be arranged in holographic cell HU2+the Z side.

Light source k1 emission P polarized light.Polarization holograms n1 is arranged in light source k's+the X side, and it is set to and makes it little to the reflection coefficient of P polarization, and is big to the emission ratio of S polarization.

Photoelectric detector m1 be arranged in light source k1 near, receive the back light be polarized hologram n deflection.Therefore, the light from light source k1 emission enters collimation lens 52 by polarization holograms n1.

Shown in Figure 27 C, holographic cell HU3 has light source k3, photoelectric detector m3 and the polarization holograms n3 that emission wavelength is the 660nm light beam, this holographic cell be arranged in holographic cell HU2-the Z side.

Light source k3 emission P polarized light.Polarization holograms n3 is arranged in light source k3's+the X side, and it is set to and makes it little to the reflection coefficient of P polarization, and is big to the reflection coefficient of S polarization.

Photoelectric detector m3 is arranged near the light source k3, receives the back light that is polarized hologram n3 deflection.Therefore, the light from light emitted enters collimation lens 52 by deflection hologram n 3.

Holographic element H11 and holographic element H31 have the Bragg condition that differs from one another, and the both is the plane of incidence of incident light and the parallel volume hologram element of output radiation face of diffraction light.Each angular magnification of each holographic element is less than 1.Material uses thermoplastics or photopolymer, utilizes the relevant exposure method of 2 known light beams to form each holographic element.

Holographic element H11 is arranged in collimation lens 52+X side, and it is set to make from the light of holographic cell HU1 by collimation lens 52 satisfies Bragg condition.Therefore, holographic element H11 diffraction is from the light of light source cell HU1 by collimation lens 52.

Convert the light beam of assembling a little that the optical axis with object lens 60 tilts a little to from the light (not shown among Figure 26) of this holographic element H11 diffraction.Convergence designs in advance by optical parametric, makes the light of holographic cell HU1 can focus on the recording layer L1, and the light of light source HU2 can focus on the recording layer L2.

Holographic element H11 has the function of the aberration that correction produces to the difference the object lens 60 to the position of the object lens 60 and the first recording layer L1 by the position of the second recording layer L2.

The light of the light of holographic cell HU2 and holographic cell HU3 does not satisfy the Bragg condition of holographic element H11 by collimation lens 52, and they are invariably by holographic element H11.

Holographic element H31 is arranged in holographic element H11's+the X side, and it is set so that the light that sees through holographic element H11 from holographic cell HU3 can satisfy Bragg condition.Therefore, holographic element H31 diffraction sees through the light of holographic element H11 from holographic element HU3.

Convert the light beam of dispersing a little that the optical axis with object lens 60 tilts a little to from the light (not shown among Figure 26) of this holographic element H31 diffraction.Divergence designs in advance by optical parametric, makes the light of holographic cell HU2 can focus on the recording layer L2, and the light of holographic cell HU3 can focus on recording layer L3.

Holographic element H31 has correction because the function of the aberration of the difference generation between the object lens 60 is arrived in the position of the second recording layer L2 to the position of object lens 60 and the 3rd recording layer L3.

From holographic cell HU2, see through holographic element H11 and do not satisfy the Bragg condition of holographic element H31 from the light of holographic element H11 diffraction, they see through holographic element H31 invariably.

Quarter-wave plate 55 is arranged in holographic element H31's+the X side, object lens 60 be arranged in quarter-wave plate 55+the X side.

The operation of the optic pick-up 23 of following brief explanation present embodiment.

Enter collimation lens 52 from face polarization (P polarization) light of light source k1 emission by polarization holograms n1, it is seen through holographic element H31 invariably by holographic element H11 diffraction, enters quarter-wave plate 55.

Light converts circularly polarized light to by quarter-wave plate 55, and this light focuses on the recording layer L1 of CD 15 by object lens 60.

Enter collimation lens 52 from face polarization (P polarization) light of light source k2 emission by polarization holograms n2, see through holographic element H11 and holographic element H31 invariably, enter quarter-wave plate 55.

Light is converted to circularly polarized light by quarter-wave plate 55, and this light focuses on the recording layer L2 of CD 15 by object lens 60.

Enter collimation lens 52 from face polarization (P polarization) light of light source k3 emission by polarization holograms n3, see through holographic element H11 invariably,, enter quarter-wave plate 55 by holographic element H31 diffraction.

Light is converted to circularly polarized light by quarter-wave plate 55, and this light focuses on the recording layer L3 of CD 15 by object lens 60.

Therefore, if make each light source simultaneously luminous, on each recording layer, can form luminous point simultaneously.

Yet not as the foregoing description, each luminous point differs from one another along the position of Z axle.That is, each luminous point differs from one another from the distance of the rotation center of CD 15.

The light that receives from CD 15 converts the circularly polarized light of opposite polarization to, and the light that returns enters quarter-wave plate 55 by object lens 60, thereby makes it convert linearly polarized light (S polarization) perpendicular to external travel to.This light that returns enters holographic element H31, and the contained light that returns from the 3rd recording layer L3 is diffracted in back light.The optical axis of this diffraction light and collimation lens 52 tilts a little.

Back light by holographic element H31 enters holographic element H11, and the light component that returns from the first recording layer L1 in back light is diffracted.The optical axis of this diffraction light and collimation lens 52 tilts a little.

The light that returns by holographic element H11 enters collimation lens 52.The contained light component (by the light of holographic element H31 diffraction) that returns from the 3rd recording layer L3 is launched from collimation lens 52 towards holographic element HU3 in the back light that enters collimation lens 52, is received by photoelectric detector m3 by polarization holograms n3.

The contained light component (by the light of holographic element H11 diffraction) that returns from the first recording layer L1 is launched from collimation lens 52 towards holographic cell HU1 in the back light that enters collimation lens 52, is received by photoelectric detector m1 by polarization holograms n1.

The contained light component that returns from the second recording layer L2 (seeing through the light of each holographic element) emission from collimation lens 52 towards holographic cell HU2 is received by photoelectric detector m2 by polarization holograms n2 in the back light that enters collimation lens 51.

Each photoelectric detector constitutes as above-mentioned embodiment, and each photoelectric detector is according to the light-receiving amount output signal of reproducing signal treatment circuit 28.

As mentioned above, in the optic pick-up 23 of present embodiment, be provided with three light source (k1, k2, k3) and two holographic element (H11, H31), holographic element H11 is along the light of the direction diffraction light sources k1 that faces object lens 60 and the light that returns by object lens 60 along the light of launching from light source k in the face of the direction diffraction of photoelectric detector m1, and holographic element H31 is along the light of the direction diffraction light sources k3 that faces object lens 60 and the back light that passes through object lens 60 that reflects from light source k3 along the direction diffraction in the face of photoelectric detector m3.Each holographic element is the plane of incidence of the incident light volume hologram element parallel with the output radiation face of diffraction light, and each volume hologram element is arranged along X-direction.Therefore, the miniaturization of optic pick-up and optical disc apparatus is further improved by the foregoing description.

In the above-described embodiments, when needs are proofreaied and correct the aberration of light of holographic cell HU, as shown in figure 28, corresponding to holographic cell (HU1, HU2, three holographic elements HU3) (H13, H23, H33) can be used to replace two holographic elements (H11, H31).In this case, for example,, in the light of the holographic cell of correspondence, make from the maximum intensity output radiation direction of the light of each light emitted inclined light shaft by whole holographic elements and object lens 60 for separately 0 order diffraction light and primary diffraction light.

(H33) Bragg condition differs from one another holographic element for H13, H23, and they are plane of incidence volume hologram elements parallel with the output radiation face of diffraction light of incident light.

Holographic element H13 is arranged in collimation lens 52+X side, and it is set to the light that makes holographic cell HU1 and satisfies Bragg condition by collimation lens 52.Therefore, holographic element H13 diffraction is from the light of holographic cell HU1 by collimation lens 52.Convert the light beam of assembling a little to from the diffraction light (not shown among Figure 28) of this diffraction element H13 emission, the optical axis of itself and object lens 60 tilts a little, convergence designs in advance by optical parametric, make the light of holographic cell HU13 focus on the recording layer L1, the light of holographic cell HU2 focuses on the recording layer L2.

Holographic element H13 has correction because the function of the position of the object lens 60 and the first recording layer L to the aberration of the difference generation of object lens 60 arrived in the position of the second recording layer L2.

The light of the light of holographic cell HU2 and holographic cell HU3 does not satisfy the Bragg condition of holographic element H13 by collimation lens 52, sees through holographic element H13 invariably.

Holographic element H23 is arranged in holographic element H13's+the X side, and it is set to and makes the light that sees through holographic element H13 from holographic cell HU2 satisfy Bragg condition.Therefore, holographic element H23 diffraction sees through the light of holographic element H13 from holographic cell HU2.

Convert the light of the optical axis that is parallel to object lens 60 to from the diffraction light of this holographic element H23 emission.That is, the angular magnification of holographic element H23 is set at 0.

See through the light of holographic element H13 and do not satisfy the Bragg condition of holographic element H23 from the light of holographic element H13 diffraction from holographic cell HU3, they see through holographic element H23 invariably.

Holographic element H33 is arranged in holographic element H23's+the X side, and it is set to and makes the light that sees through holographic element H23 from holographic cell HU3 satisfy Bragg condition.Therefore, holographic element H 33 diffraction see through the light of holographic element H23 from holographic cell.

Tilt a little from the diffraction light (not shown among Figure 28) of this holographic element H33 emission and the optical axis of object lens 60, become the light beam of dispersing a little, the light that designs holographic cell HU2 in advance by optical parametric focuses on the divergence on the recording layer L2, makes the light of holographic cell HU3 focus on the recording layer L3.

Holographic element H33 has correction because the function of the position of object lens 60 and the 3rd recording layer L3 to the aberration of the difference generation of object lens 60 arrived in the position of the second recording layer L2.The diffraction light of the diffraction light of holographic element H13 and holographic element H23 does not satisfy the Bragg condition of holographic element H33, just sees through holographic element H33 invariably.

Light source is not limited to three of present embodiment.The quantity of the recording layer of CD 15 is not limited to three layers of present embodiment.

Next, the optic pick-up of invention one embodiment is described.

Not as the foregoing description, present embodiment is characterised in that, forms two and more luminous point simultaneously on identical recording layer.

Except optical disc apparatus, data processing and signal processing, the formation of optical disc apparatus is same as the previously described embodiments.

As shown in figure 29, the optic pick-up 23 of present embodiment comprises three light source (Ld1, Ld2, Ld3), two holographic element (H12, H32), collimation lens 52, three photoelectric detector (Pd1, Pd2, Pd3), polarization beam apparatus 54, quarter-wave plate 55, object lens 60, convergent lens 58, cylindrical lens 73 and be used to drive the drive system (not shown) of object lens 60.

Each light emitted wavelength is the laser beam of 660nm.Light source Ld2 is arranged on the optical axis of collimation lens 52, light source Ld1 be arranged in light source Ld2+the Z side, light source Ld3 be arranged in light source Ld2-the Z side.

Each light emitted P polarized light.From the maximum intensity output radiation direction of the laser beam of each light emitted be+directions X.

Collimation lens 52 is arranged in each light source+X side, converts the light of each light source to common parallel beam.Shown in Figure 30 A, if from the light transmission collimation lens 52 of light source Ld1 emission, light is converted into X axis to tilt clockwise+the common directional light of θ a1.Shown in Figure 30 B, if from the light transmission collimation lens 52 of light source Ld2 emission, light is converted into along the parallel light beam of X axis.Shown in Figure 30 C, if from the light transmission collimation lens 52 of light source Ld3 emission, light become counterclockwise by walking around with X axis-the common directional light of θ c1.

In this manual, tilt to be made as clockwise just (+), tilt to be made as counterclockwise negative (-).

Holographic element H12 and holographic element H32 have the Bragg condition that differs from one another, and the both is the plane of incidence of the incident light volume hologram element parallel with the output radiation face of diffraction light.Holographic element H12 is arranged in collimation lens 52+X side, holographic element H32 be arranged in holographic element H12+the X side.

Thermoplastics or photopolymer are used for the material of each holographic element, and each holographic element utilizes the relevant exposure method of 2 known light beams to form.For example, holographic element Hm does not also form hologram pattern, shown in Figure 31 A, when the reference light Lr of holographic element Hm enters left side (direction and inclination+θ a1 that level receives), information light Li enters from the left side (direction and inclination-θ a2 that level receives) of holographic element Hm, by forming holographic element H12 at the inner hologram pattern that forms of holographic element Hm.Light source Ld1 is not on the optical axis of collimation lens 52, owing to be arranged in+the Z side, the aberration that provides is identical with the aberration of reference light Lr, makes information light Li not have aberration like this.

That is to say that by light source Ld1 being arranged in+the Z side, rather than be arranged on the optical axis of collimation lens 52, holographic element H12 can aberration correction.

For the holographic element Hm that does not also form hologram pattern, shown in Figure 31 B, when (direction and inclination-θ c1 that level receives) enters on the left of the reference light Lr of holographic element Hm enters, information light Li enters from the left side (direction and inclination+θ c2 that level receives) of holographic element Hm, by forming holographic element H32 at the inner hologram pattern that forms of holographic element Hm.Light source Ld3 is not on the optical axis of collimation lens 52, owing to be arranged in-the Z side, the aberration that provides is identical with the aberration of reference light Lr, makes information light Li not have aberration like this.

That is to say that by light source Ld3 being arranged in-the Z side, rather than be arranged on the optical axis of collimation lens 52, holographic element H32 can aberration correction.

Pass through the light of collimation lens 52 by holographic element H12 diffraction, to satisfy the Bragg condition of holographic element H12 from light source Ld1.Holographic element H12 is along launching diffraction light with the direction of X-direction inclination-θ a2, shown in Figure 32 A.

From light source Ld2 by collimation lens 52 light and do not satisfy the Bragg condition of holographic element H12 from light source Ld3 by the light of collimation lens 52, they see through holographic element H12 invariably.

See through the light of holographic element H12 by holographic element H32 diffraction, to satisfy the Bragg condition of holographic element H32 from light source Ld3.Holographic element H32 is along launching diffraction light with the direction of X-direction inclination+θ c2, shown in Figure 32 B.

The diffraction light of holographic element H12 and do not satisfy the Bragg condition of holographic element H32 from the light that light source Ld2 sees through holographic element H12, they see through holographic element H32 invariably.

Holographic element H32 is arranged in collimation lens 52+X side, holographic element H12 be arranged in holographic element H32+the X side.The information light distribution is corrected, and equally sets with axially object is the same so that will distribute from the light intensity of each holographic element diffraction.

Because if volume hologram element H12 forms with the information light Li of the common gaussian intensity profile of reference light Lr and middle axle offset, shown in Figure 33 A, it is big that the variations in refractive index of top of space becomes.

Shown in Figure 33 B, there is such possibility, the intensity distributions of diffraction light can become local Gaussian and distribute, and can change the form of the luminous point that forms in CD, the characteristics of signals deterioration.

If volume hologram element H12 forms with the information light Li that space bottom has peak strength, shown in Figure 34 A, can obtain to have the diffraction light of the common gaussian intensity profile of axial symmetry, shown in Figure 34 B.

If the volume hologram element H12 information light Li formation of the intensity of light beam end greater than the intensity of beam center shown in Figure 35 A, will obtain the light beam end and have high-intensity diffraction light, shown in Figure 35 B.

The intensity distributions of adjustment information light Li can be adjusted the end intensity (RIM intensity) of diffraction light.This equals the ordinary beam of light shaping feature.

Have the intensity distributions axially symmetrical from the diffraction light of each holographic element emission with the optical axis of holographic element.Each holographic element is set to the half-breadth angle of intensity distributions of the diffraction light that makes emission greater than the half-breadth angle of intensity distribution of incident light.

Return and come with reference to Figure 29, polarization beam apparatus 54 be arranged in holographic element H32+the X side, quarter-wave plate 55, object lens 60, collector lens 58 and cylindrical lens 73 are arranged similar to the above embodimentsly.

Photoelectric detector Pd2 is arranged in cylindrical lens 73-Z side, and is arranged on the optical axis of cylindrical lens 73.Photoelectric detector Pd1 is arranged in photoelectric detector Pd2's-the X side, photoelectric detector Pd3 be arranged in photoelectric detector Pd2+the X side.

The operation of the optic pick-up 23 of following brief explanation present embodiment.

Enter holographic element H12 from face polarization (P polarization) light of light source Ld1 emission by collimation lens 52,, see through holographic element H32 invariably, enter polarization beam apparatus 54 by holographic element H12 diffraction.

Enter holographic element H12 from face polarization (P polarization) light of light source Ld2 emission by collimation lens 52, see through holographic element H12 and holographic element H32 invariably, enter polarization beam apparatus 54.

Enter holographic element H12 from face polarization (P polarization) light of light source Ld3 emission by collimation lens 52, it sees through holographic element H12 invariably, by holographic element H32 diffraction, enters polarization beam apparatus 54.

The most of light that enters polarization beam apparatus 54 sees through polarization beam apparatus invariably, is converted to circularly polarized light by quarter-wave plate 55, focuses on by object lens 60 on the recording layer of CD 15.

The light of light source Ld2 focuses at the position t2 with the optical axis intersection of object lens 60, the light of light source Ld1 position t2+the position t1 of Z side focuses on, the light of light source Ld3 position t2-the position t3 of Z side focuses on.

That is to say, focus in the position that the recording layer of CD 15 differs from one another from the light of each light emitted.

The light that receives from CD 15 converts the circularly polarized light of opposite polarization to, and the light that returns enters quarter-wave plate 55 by object lens 60, makes light convert linearly polarized light (S polarization) perpendicular to external travel to.This back light enters polarization beam apparatus 54.

The back light that is polarized the emission of beam splitter 54 edge-Z directions is received by each photoelectric detector by collector lens 58 and cylindrical lens 73.

The light that returns from position t1 is received by photoelectric detector Pd1, and the light that returns from position t2 is received by photoelectric detector Pd2, and the light that returns from position t3 is received by photoelectric detector Pd3.

The clearance D of each luminous point that forms on the recording layer of CD 15 depends on the gap d p of each light source in Z-direction, the angular magnification m of holographic element (=sin (output radiation angle)/sin (incident angle)), the focal distance f c of collimation lens 52, the focal distance f o of object lens 60.That is, be formulated this relation: satisfy m=(D/dp) * (fc/fo).

For example, when setting dp=6mm, fc=24mm during fo=4mm, under the situation of m=0.01, needs D=0.01.Because value=D/fc=0.25 of sin (number of degrees of incident angle), it can be set at sin (output radiation angle)=sin (incident angle) * 0.01=0.0025.

In this case, for example, photoelectric detector Pd2 can be used as 4 fens photoelectric detectors, and based on the output of photoelectric detector Pd2, the tracking error input that can carry out method of astigmatism detects with the focus error signal of recommending method.

In the optic pick-up 23 of present embodiment, (Ld3) (H12 H32) realizes light source cell with two holographic elements for Ld1, Ld2 by three light sources.

In the optic pick-up 23 of present embodiment, (Ld1, Ld2 Ld3) do not change with holographic element H12 to see through three light sources, from the optical diffraction of light source Ld1 and from the light of light source Ld2 and light source Ld3 diffraction not, diffracted from the light that sees through holographic element H12 of light source Ld3.

See through holographic element H32 and do not change, from the light that sees through holographic element H12 of light source Ld2 diffraction not, each holographic element has the plane of incidence of parallel incident light and the output radiation face of diffraction light, and each holographic element is the volume hologram element of arranging along X axis.

Therefore, illuminator can miniaturization, does not reduce the utilization factor of light, can realize miniaturization, can not cause performance to descend.

According to optical disc apparatus of the present invention,, thereby can carry out the reproduction processes of CD fast because the reproduction of two or more tracks can almost carry out simultaneously.

In the present embodiment, can also almost write down simultaneously and reproduce.For example, recorded information on a track is from other track information reproduction.

In the above-described embodiments, as shown in figure 36, it can replace with convergent lens 58 and cylindrical lens 73, and (R32, R22 R12) are arranged on the light path between polarization beam apparatus 54 and each photoelectric detector for three holographic elements.Holographic element R32, holographic element R22 and holographic element H12 have the Bragg condition that differs from one another, and they are plane of incidence volume hologram elements parallel with the output radiation face of diffraction light of incident light.

Holographic element R32 is arranged in polarization beam apparatus 54-Z side, and diffraction is polarized the contained light component that returns from position t3 in the back light of beam splitter 54 edge-Z directions reflections, is set to the receiving surface that converges to photoelectric detector Pd3.Holographic element R32 give diffraction light with astigmatism.

Be polarized the contained light component that returns from position t1 in the back light of beam splitter 54 edge-Z directions reflections and do not satisfy the Bragg condition of holographic element R32, just see through holographic element R32 invariably from the light component that position t2 returns.

Holographic element R22 is arranged in holographic element R32's-the Z side, and diffraction is the contained light component that returns from position t2 in seeing through the back light of holographic element R32, is set to the receiving surface that converges to photoelectric detector Pd2.Holographic element R22 give diffraction light with astigmatism.

Except the light component that returns from position t2 contained in seeing through the back light of holographic element R32, there is not light to satisfy the Bragg condition of holographic element R22, they see through holographic element R22 invariably.

Holographic element R12 is arranged in holographic element R22's-the Z side, and diffraction sees through the contained light component that returns from position t1 in the back light of holographic element R22, is set to the receiving surface that converges to photoelectric detector Pd1.Holographic element R12 give diffraction light with astigmatism.

The contained light component that returns from position t 1, do not have light to satisfy the Bragg condition of holographic element R12 in seeing through the back light of holographic element R22, they see through holographic element R12 invariably.

That is to say that (R32, R22 R12) have the lens function of change output radiation light to the divergence of incident light to three holographic elements.

Therefore, do not reduce the light utilization efficiency cocoa, can not cause performance to descend in addition so that the detection system miniaturization can realize the miniaturization of optic pick-up.

The optic pick-up 23 of present embodiment uses holographic cell.In this case, use each holographic element of back light that diffraction receives from the light of corresponding holographic cell emission with by corresponding holographic cell.

The optic pick-up of one embodiment of the invention is described below.

Not as the foregoing description, present embodiment has can respond all based on the CD (BD) of blu-ray standard enforcement and the CD of implementing based on dvd standard (DVD).

Except optic pick-up and data processing and signal processing, the formation of optical disc apparatus is same as the previously described embodiments.Represent with identical Reference numeral that with the foregoing description respective element components identical the descriptions thereof are omitted at this.

CD 15 is DVD or BD.When it needed by difference, DVD was expressed as CD 15d, and BD is expressed as CD 15b.

As shown in figure 37, the optic pick-up 23 of present embodiment comprises two light source (Lb, Ld), holographic element Hd, collimation lens 52, polarization beam apparatus 54, the quarter-wave plate 55 that is used for two wavelength, opening wavelength filter plate 57, object lens 60, collector lens 58, cylindrical lens 73, two photoelectric detectors (Pd, Pb), Amici prism 76 and be used to drive the drive system (not shown) of object lens 60.Object lens 60 are suitable for BD most.

When CD is BD, use light source Lb, its emission wavelength is the laser beam of 405nm.From the maximum intensity output radiation direction of light source Lb emitted laser bundle be+directions X.Light source Lb is arranged in the position of its luminous point corresponding to the focal position of collimation lens 52.

When CD is DVD, use light source Ld, its emission wavelength is the laser beam of 660nm.Light source Ld is near light source Lb, and it is arranged to satisfy from the light of light source Ld emission the Bragg condition of holographic element Hd.

From light source Lb and light source Ld emission P polarized light.The plane of incidence of incident light and volume hologram element parallel with the output radiation face of diffraction light, holographic element Hd are arranged on the light path between each light source and the collimation lens 52.Do not satisfy the Bragg condition of holographic element Hd from the light of light source Lb emission, just see through holographic element Hd invariably.

On the other hand, from the light of light source Ld emission by holographic element Hd diffraction, to satisfy the Bragg condition of holographic element Hd.Diffraction light is launched from holographic element Hd court+directions X.

This holographic element Hd be set to diffraction light is become more be equal to from the focal position that is positioned at collimation lens 52+diverging light of the light of the exit point S1 emission of shooting without hitting the target of X side.

For example, holographic element is shown in Figure 38 A.Reference light Lr enters the holographic element Hd that does not also form hologram pattern from light source Ld, and information light Li enters from the exit point S1 that shoots without hitting the target, by forming holographic element at the inner hologram pattern that forms of holographic element Hm.Determine with wavelength between the substrate thickness of the exit point S1 that shoots without hitting the target consideration BD and DVD.

That is to say that diffraction light converts the emission light of the aberration that produces between the substrate thickness of correction by BD and DVD to, shown in Figure 38 B.The angular magnification of holographic element Hd is less than 1.Material uses thermoplastics or photopolymer, utilizes the relevant exposure method of 2 known light beams to form holographic element Hd.

Collimation lens 52, polarization beam apparatus 54, quarter-wave plate 55, object lens 60, collector lens 58 and cylindrical lens 73 are arranged similar to the above embodimentsly.

Opening wavelength filter plate 57 is arranged on the light path between quarter-wave plate 55 and the object lens 60, and it is designed such that opening diameter can change according to wavelength.Carry out the opening restriction of the light of light source Lb, make the numerical aperture (NA) of object lens 60 be set at 0.85, carry out the opening restriction of light source Ld, make the numerical aperture (NA) of object lens 60 be set at 0.65.The servo driving of this opening wavelength filter plate 57 and object lens 60 integral body are carried out.

Amici prism 76 is arranged in cylindrical lens 73-Z side.When CD was DVD, back light was by the reflection of Amici prism 76 edge+directions Xs, and when CD was BD, back light saw through Amici prism 76 invariably.

Photoelectric detector Pd is arranged in Amici prism 76+X side, receives the back light of Amici prism 76 reflections.Photoelectric detector Pb is arranged in Amici prism 76-Z side, receives the back light that sees through Amici prism 76.

The operation of the optic pick-up 23 of following brief explanation present embodiment.

When CD was the BD dish, face polarization (P polarization) light that reflects from light source Lb saw through holographic element Hd invariably, converts parallel beam to collimation lens 52, enters polarization beam apparatus 54.

Light sees through polarization beam apparatus 54 invariably, converts circularly polarized light to quarter-wave plate 55, carries out the opening restriction with opening wavelength filter plate 57, and most of light of collimation lens 52 focuses on the recording layer of CD 15b by object lens 60.

The light that is received by CD 15b converts the circularly polarized light of opposite polarization to, and the light that returns enters quarter-wave plate 55 by object lens 60 and opening wavelength filter plate 57, makes it convert linearly polarized light (S polarization) perpendicular to external travel to.This back light enters polarization beam apparatus 54.

The back light that is polarized the reflection of beam splitter 54 edge-Z directions enters Amici prism 76 by convergent lens 58 and cylindrical lens 73, sees through Amici prism 76 invariably, and Pb receives by photoelectric detector.

When CD was DVD, face polarization (P polarization) light of launching from light source Ld entered holographic element Hd, and light is converted to the light of dispersing a little by holographic element Hd edge+directions X diffraction by collimation lens 52, enters polarization beam apparatus 54.See through polarization beam apparatus 54 invariably, converted to circularly polarized light by quarter-wave plate 55, carry out the opening restriction by opening wavelength filter plate 57, most of diffraction light focuses on the recording layer of CD 15d by object lens 60.

Convert the circularly polarized light of opposite polarization to by the light of the reception of CD 15, the light that returns enters quarter-wave plate 55 by object lens 60 and opening wavelength filter plate 57, makes it convert linearly polarized light (S polarization) perpendicular to external travel to.This back light enters polarization beam apparatus 54.

Light enters Amici prism 76 by convergent lens 58 and cylindrical lens 73, is reflected by Amici prism 76, and the back light that is polarized the reflection of beam splitter 54 edge-Z directions is received by photoelectric detector Pd.

When CD was DVD, the light that enters object lens 60 converted emission light to, proofreaied and correct the aberration by the substrate thickness of BD and the difference generation between the wavelength.When forming holographic element Hd, the aberration that increases high-order spherical aberration in addition and when Tracing Control, produce by the packing of object lens.

Utilize non-spherical lens, liquid crystal device etc. that high-order spherical aberration and coma are added to information light Li, at the inner hologram pattern that forms of holographic element Hm.

Because if reference light glitters, information light formation time will appear, if use this holographic element, the holographic element that utilizes this information light to form not only can be proofreaied and correct the aberration that the difference between BD substrate thickness and the wavelength produces, and proofreaies and correct the aberration that object lens produce when Tracing Control.

When CD was BD, it also had such holographic element, and it has the function of the aberration that correction produces by the packing of object lens when Tracing Control.

In the optic pick-up 23 of present embodiment, (Lb Ld) realizes light source cell with holographic element Hd by light source.

In the optic pick-up 23 of present embodiment, (Lb Ld) constitutes with holographic element Hd light source cell by two light sources.In holographic element Hd, the face of incident light is parallel with the output radiation face of diffraction light, and holographic element Hd is the volume hologram element, makes the light of light source Lb see through holographic element Hd, the light of holographic element Hd edge+directions X diffraction light sources Ld invariably.Therefore, do not reduce light utilization efficiency and just can make the illuminator miniaturization, it is possible not causing performance to descend and obtain miniaturization.

For the optic pick-up 23 of present embodiment, can realize miniaturization, and the access definition of the CD that substrate thickness is reduced differ from one another.

In the said method of present embodiment, as shown in figure 39, replace Amici prism 76, can use holographic element Rd.

In this holographic element Rd, the plane of incidence of incident light is parallel with the output radiation face of diffraction light.When CD is the BD dish, make back light see through this volume hologram element invariably, when CD was DVD, back light was by volume hologram element diffraction.

Photoelectric detector Pd is arranged near the converged position of diffraction light.Holographic element Rd also has the function of correction by the aberration of substrate thickness difference generation.In this case, (Pb Pd) realizes with holographic element Rd optical detector unit by two photoelectric detectors.

Therefore, do not reduce light utilization efficiency and can make the detection system miniaturization, can realize the miniaturization of optic pick-up, and can not cause performance to descend in addition.

Say that by the way for BD (optical source wavelength is 405nm), substrate thickness is designed to 0.1mm, because poor between substrate thickness and the wavelength, object lens 60 produce aberrations, and for DVD (optical source wavelength is 660nm), substrate thickness is designed to 0.6mm.

For this reason, when photoelectric detector Pd was arranged on the substrate identical with photoelectric detector Pb, holographic element Rd had interim aberration compensation function, and CD is DVD, offset error or sensitivity occur and descend in focus error signal.That is, because the light that returns from CD 15d enters collector lens 58 with the converging light state, and enter collector lens 58 from the light that CD 15b returns with the parallel beam state, photoelectric detector Pd must be arranged in photoelectric detector Pb front (+Z side).

Holographic element Rd produces the diffraction light of the aberration of correct convergence light, even it is arranged in same side with photoelectric detector Pd and photoelectric detector Pb, can obtain normal focus error signal, and can further obtain miniaturization and simplification.

The optic pick-up 23 of present embodiment can utilize holographic cell to constitute.In this case, use such holographic element, each of the back light that its diffraction receives from the light of corresponding holographic cell emission with by corresponding holographic cell.

Optic pick-up in one embodiment of the invention is described below.

Not as the foregoing description, present embodiment has any one feature that can respond based on CD (CD), DVD and the BD of CD standard.

Except optic pick-up and data processing and signal processing, the formation of optical disc apparatus is same as the previously described embodiments.Represent with identical Reference numeral that with the foregoing description respective element components identical the descriptions thereof are omitted at this.

Any one of CD, DVD and BD during CD 15.When needs were distinguished, DVD was expressed as CD 15d, and BD is expressed as CD 15b, and CD is expressed as CD 15c.

As shown in figure 40, the optic pick-up 23 of present embodiment comprises three light source (Lb, Ld, Lc), two Amici prism (76c, 76d), three holographic elements (Hb1, Hd1, Hc1), polarization beam apparatus 54, the quarter-wave plate 55 that is used for three wavelength, diffraction optical element 56, opening wavelength filter plate 57, object lens 60, collector lens 58, cylindrical lens 73, three photoelectric detector (Pb, Pd, Pc) and be used to drive the drive system (not shown) of object lens 60.

When CD is DVD, use light source Ld, its emission wavelength is the laser beam of 660nm.This light source Ld is arranged on the optical axis of polarization beam apparatus 54.

When CD is BD, use light source Lb, its emission wavelength is the laser beam of 405nm.This light source Lb is arranged in light source Ld's+the Z side.

When CD is CD, use light source Lc, its emission wavelength is the laser beam of 780nm.This light source Lc is arranged in light source Ld's-the Z side.

From the light of each light emitted should be the P polarization.Each holographic element is the plane of incidence of the incident light volume hologram element parallel with the output radiation face of diffraction light.Each angular magnification of each holographic element is less than 1.Material uses thermoplastics or photopolymer, utilizes the relevant exposure method of 2 known light beams to form each holographic element.

Holographic element Hb1 is arranged in each light source+X side, and it is set to is that light from light source Lb emission satisfies Bragg condition.Therefore, from the light of light source Lb emission by holographic element Hb1 diffraction.The optical axis of this diffraction light and object lens 60 is emission abreast almost.

On the other hand, do not satisfy the Bragg condition of holographic element Hb1, just see through holographic element Hb1 invariably from the light of light source Ld and light source Lc emission.Holographic element Hd1 is arranged in holographic element Hb1's+the X side, and it is set to and makes the light that sees through holographic element Hb1 from light source Ld satisfy Bragg condition.Therefore, see through the light of holographic element Hb1 by holographic element Hd1 diffraction from light source Ld.The optical axis of this diffraction light and object lens 60 is emission abreast almost.

On the other hand, see through the light of holographic element Hb1 and do not satisfy the Bragg condition of holographic element Hd1, just see through holographic element Hd1 invariably by the light of holographic element Hb1 diffraction from light source Lc.

Holographic element Hc1 is arranged in holographic element Hd1's+the X side, and it is set to and makes the light that sees through holographic element Hd1 from light source Lc satisfy Bragg condition.Therefore, see through the light of holographic element Hd1 by holographic element Hc1 diffraction from light source Lc.The optical axis of this diffraction light and object lens 60 is emission abreast almost.

On the other hand, do not satisfy the Bragg condition of holographic element Hc1, just see through holographic element Hc1 invariably from the light of holographic element Hb1 diffraction with from the light of holographic element Hd1 diffraction.

That is to say that each holographic element has the function of the divergence that changes output radiation light and incident light.For this reason, do not need collimation lens.When forming holographic element, use parallel beam information light can form holographic element.Putting in order of each holographic element is not limited thereto.

Polarization beam apparatus 54 is arranged in holographic element Hc1's+the X side, and quarter-wave plate 55, object lens 60, collector lens 58 and cylindrical lens 73 are arranged similar to the above embodimentsly.Object lens 60 are suitable for DVD most.

When hologram pattern formed, the aberration that is used to proofread and correct the aberration that the substrate thickness difference by BD and DVD produces added to holographic element Hb1, and the aberration that is used to proofread and correct by the aberration of the substrate thickness generation of CD and DVD adds to holographic element Hc1.

Diffraction light sources element 56 is arranged in quarter-wave plate 55+X side, carries out aberration compensation corresponding to each wavelength.Opening wavelength filter plate 57 is arranged in diffraction optical element 56+X side, carries out the opening restriction corresponding to each wavelength.

The servo driving of diffraction optical element 56 and opening wavelength filter plate 57 and object lens 60 integral body are carried out.

Amici prism 76c is arranged in cylindrical lens 73-Z side, when CD is CD, and the light that the reflection of its edge+directions X is returned.Photoelectric detector Pc is arranged in this Amici prism 76c's+the X side, receives the back light of Amici prism 76c reflection.Amici prism 76c sees through back light invariably, and when CD was BD or DVD, Amici prism 76c saw through back light invariably.

Amici prism 76d is arranged in Amici prism 76c's-the Z side, when CD is DVD, and the back light of its edge+directions X reflecting ﹠ transmitting Amici prism 76c.Photoelectric detector Pd is arranged in this Amici prism 76d's+the X side, receives the back light of Amici prism 76d reflection.

When CD was BD, Amici prism 76d saw through back light invariably.Photoelectric detector Pb is arranged in Amici prism 76d's-Z side and receive the back light that sees through Amici prism 76d.

Next, the operation of the optic pick-up 23 of brief explanation present embodiment.

Explain the operation of the optic pick-up 23 when CD is BD.Enter holographic element Hb1 from face polarization (P polarization) light of light source Lb emission, its holographic element Hb1 diffraction converts parallel beam to, sees through holographic element Hd1 and holographic element Hc1 invariably, enters polarization beam apparatus 54.Most of diffraction light sees through polarization beam apparatus 54 invariably, is converted to circularly polarized light by quarter-wave plate 55.

Be suitable for the aberration compensation of BD with diffraction optical element 56, be suitable for the opening restriction of BD with opening wavelength filter plate, light focuses on the recording layer of CD 15b by object lens 60.

The light that is received by CD 15b converts the circularly polarized light of opposite polarization to, and back light enters diffraction optical element 56 by object lens 60 and opening wavelength filter plate 57.The back light that diffracted optical element 56 converts parallel beam to enters quarter-wave plate 55, makes it convert linearly polarized light (S polarization) perpendicular to external travel to.This back light enters polarization beam apparatus 54.

The back light that is polarized the reflection of beam splitter 54 edge-Z directions enters Amici prism 76c by collector lens 58 and cylindrical lens 73, see through Amici prism 76c invariably, enter Amici prism 76d, see through Amici prism 76d invariably, light is received by photoelectric detector Pb.

Explain the operation of optic pick-up 23 when CD is DVD.Enter holographic element Hd1 from face polarization (P polarization) light of light source Ld emission, by holographic element Hd1 diffraction.Light is converted into parallel beam, sees through holographic element Hb1 and holographic element Hc1 invariably, enters polarization beam apparatus 54.

Most of diffraction light sees through polarization beam apparatus 54 invariably, is converted to circularly polarized light by quarter-wave plate 55.Light sees through diffraction optical element 56 invariably, is suitable for the opening restriction of DVD by opening wavelength filter plate 57.Light focuses on the recording layer of CD 15d by object lens 60.

The light that is received by CD 15d converts the circularly polarized light of opposite polarization to, and back light enters diffraction optical element 56 by object lens 60 and opening wavelength filter plate 57.The back light that diffracted optical element 56 converts parallel beam to enters quarter-wave plate 55, makes it convert linearly polarized light (S polarization) perpendicular to external travel to.This back light enters polarization beam apparatus 54.

The back light that is polarized beam splitter 54 reflections enters Amici prism 76c by collector lens 58 and cylindrical lens 73, sees through Amici prism 76c invariably, and light enters Amici prism 76d, and 76b reflects by Amici prism, and light is received by photoelectric detector Pd.

Explain the operation of optic pick-up 23 when CD is CD.Face polarization (P polarization) light transmission holographic element Hb1 and holographic element Hd1 from light source Lc emission enter holographic element Hc1, and light is converted to parallel beam by holographic element Hc1 diffraction, enters polarization beam apparatus 54.

Most of diffraction light sees through polarization beam apparatus 54 invariably, is converted to circularly polarized light by quarter-wave plate 55.Be suitable for the aberration compensation of CD with diffraction optical element 56, be suitable for the opening restriction of CD with opening wavelength filter plate 57, light focuses on the recording layer of CD 15c by object lens 60.

The light that is received by CD 15c converts the circularly polarized light of opposite polarization to, enters diffraction optical element 56 by object lens 60 and opening wavelength filter plate 57 as back light.The back light that diffracted optical element 56 converts parallel beam to enters quarter-wave plate 55, allows it become face polarization (S polarization) perpendicular to external travel.This back light enters polarization beam apparatus 54.

Light enters Amici prism 76c by collector lens 58 and cylindrical lens 73, and 76c reflects by Amici prism, and the back light that is polarized the reflection of beam splitter 54 edge-Z directions is received by photoelectric detector Pc.

In the optic pick-up 23 of present embodiment, (Lc) (Hb1, Hd1 Hc1) realize light source cell with three holographic elements for Lb, Ld by three light sources.

In the optic pick-up 23 of present embodiment, be provided with three light sources (Lb, Ld, Lc), holographic element Hb1 is seen through invariably, do not have the light of edge+directions X diffraction light sources Lb, the light of light source Ld and light source Lc does not have diffraction, sees through the light edge+directions X diffraction of holographic element Hb1 from light source Ld.See through holographic element Hd1 and do not change, seeing through holographic element Hb1 from light source Lc does not have diffractedly, sees through the light edge+directions X diffraction of holographic element Hd1 from light source Lc.

See through holographic element Hc1 invariably by each light of holographic element Hb1 diffraction with by each light of holographic element Hd1 diffraction, there is not diffraction, each holographic element has the parallel incident light plane of incidence and diffraction light output radiation face, and the volume hologram element is arranged along the direction of X-axis.

Therefore, do not reduce light utilization efficiency and can make the illuminator miniaturization, just can not realize miniaturization thereby performance is reduced.

In the present embodiment, as shown in figure 41, (Rc1, Rd1 Rb1) can replace convergent lens 58, cylindrical lens 73, Amici prism 76c and Amici prism 76d to use three holographic elements.

(Rc1, Rd1 Rb1) have the Bragg condition that differs from one another to three holographic elements, and each all is the plane of incidence volume hologram element parallel with the output radiation face of diffraction light of incident light.

Holographic element Rc1 is arranged in polarization beam apparatus 54-Z side, and when CD was CD, it was set to and makes back light satisfy Bragg condition.Therefore, when CD was CD, back light was by holographic element Rc1 diffraction, and focused on ad-hoc location.

The diffraction light that this holographic element Rc1 launches when having the aberration that the substrate thickness difference of proofreading and correct CD and DVD is produced has given astigmatism.When CD is BD or DVD, there is not back light to satisfy the Bragg condition of holographic element Hc1, light sees through holographic element Rc1 invariably.

Holographic element Rd1 is arranged in holographic element Rc1's-the Z side, and when CD was DVD, it was set to and makes back light satisfy Bragg condition.Therefore, when CD was DVD, back light was by holographic element Rd1 diffraction, and focused on ad-hoc location.

This holographic element Rd1 has given astigmatism to diffraction light.When CD is BD, there is not back light, satisfied the Bragg condition of holographic element Rd1 by the back light of holographic element Rc1 diffraction, they see through holographic element Rd1 invariably.

Holographic element Rb1 is arranged in holographic element Rd1's-the Z side, and when CD was BD, it was set to and makes back light satisfy Bragg condition.Therefore, when CD was BD, back light was by holographic element Rb1 diffraction, and focused on ad-hoc location.The diffraction light that this holographic element Rb1 launches when proofreading and correct the aberration of BD and the substrate thickness difference generation of DVD has given astigmatism.

Do not have back light by holographic element Rd1 diffraction, satisfied the Bragg condition of holographic element Rb1 by the back light of holographic element Rc1 diffraction, light sees through holographic element Rb1 invariably.

That is to say that (Rb1) each has lens function that is equal to convergent lens 58 and the lens function that is equal to cylindrical lens 73 to three holographic elements for Rc1, Rd1.(putting in order Rb1) is not limited thereto three holographic elements for Rc1, Rd1.

In this case, photoelectric detector Pc is arranged in from the converged position of the light of holographic element Rc1 diffraction, photoelectric detector Pd is arranged in from the converged position of the light of holographic element Rd1 diffraction, and photoelectric detector Pb is arranged in from the converged position of the light of holographic element Rb1 diffraction.That is, each photoelectric detector is arranged in same side.

In this case, (Pc) (Rc1, Rd1 Rb1) realize optical detector unit with three holographic elements for Pd, Pb by three photoelectric detectors.Therefore, do not reduce light utilization efficiency and can make the detection system miniaturization.Thereby may obtain the miniaturization of optic pick-up, cause performance to descend in addition.

Next, the optic pick-up of one embodiment of the invention is described.

Present embodiment replaces each light source in the foregoing description with holographic cell.As shown in figure 42, the optic pick-up 23 of present embodiment comprises three holographic cell (HUb, HUd, HUc), two holographic elements (Hb2, Hc2), collimation lens 52, the quarter-wave plate 55 that is used for three wavelength, diffraction optical element 56, opening wavelength filter plate 57, object lens 60 and have the drive system (not shown) that drives object lens 60.

When CD is DVD, use holographic cell HUd, shown in Figure 43 A, holographic cell HUd comprises that emission wavelength is the light source d1 of 660nm laser beam, photoelectric detector d2 and polarization holograms d3.Holographic cell HUd is arranged on the optical axis of collimation lens 52.

From light source d1 emission P polarized light.Polarization holograms d3 is arranged in light source d1's+the X side, and it is set to and makes it little to the reflection coefficient of P polarization, and is big to the reflection coefficient of S polarization.

Photoelectric detector d2 is arranged near the light source d1, receives the back light that is polarized hologram d3 deflection.Therefore, the light from light source d1 emission enters collimation lens 52 by polarization holograms d3.

When CD is the BD dish, use holographic cell HUb, shown in Figure 43 B, holographic cell HUb comprises that emission wavelength is light source b1, photoelectric detector b2 and the polarization holograms b3 of the laser beam of 405nm.Holographic cell HUb is arranged in holographic cell HUd's+the Z side.

From light source b1 emission P polarized light.Polarization holograms b 3 is arranged in light source b1's+the X side, and it is set to and makes it little to the reflection coefficient of P polarization, and is big to the reflection coefficient of S polarization.

Photoelectric detector b2 is arranged near the light source b1, receives the back light that is polarized hologram b3 deflection.Therefore, the light from light source b1 emission enters collimation lens 52 by polarization holograms b3.

When light source is CD, use holographic cell HUc, shown in Figure 43 C, holographic cell HUc comprises that emission wavelength is light source c1, photoelectric detector c2 and the polarization holograms c3 of the laser beam of 780nm.Holographic cell HUc is arranged in holographic cell HUd's-the Z side.

From light source c1 emission P polarized light.Polarization holograms c3 is arranged in light source c1's+the X side, and it is set to and makes it little to the reflection coefficient of P polarization, and is big to the reflection coefficient of S polarization.

Photoelectric detector c2 is arranged near the light source c1, receives the back light that is polarized hologram c3 deflection.Therefore, the light from light source c1 emission enters collimation lens 52 by polarization holograms c3.

Holographic element Hb2 and holographic element Hc2 have the Bragg condition that differs from one another, and each holographic element is the plane of incidence of the incident light volume hologram element parallel with the output radiation face of diffraction light.Each angular magnification of each holographic element is less than 1.Material uses thermoplastics or photopolymer, and each holographic element utilizes the relevant exposure method of 2 known light beams to form.

Holographic element Hb2 is arranged in collimation lens 52+X side, and it is set to make from the light of holographic cell HUb by collimation lens 52 satisfies Bragg condition.Therefore, pass through the light of collimation lens 52 by holographic element Hb2 edge+directions X diffraction from holographic cell HUb.From holographic cell HUd by collimation lens 52 light and do not satisfy the Bragg condition of holographic element Hb2 from holographic cell HUc by the light of collimation lens 52, they see through holographic element Hb2 invariably.

Holographic element Hc2 is arranged in holographic element Hb2's+the X side, and it is set to and makes the light that sees through holographic element Hb2 from holographic cell HUc satisfy Bragg condition.Therefore, see through the light of holographic element Hb2 by holographic element Hc2 edge+directions X diffraction from holographic cell HUc.The light transmission holographic element Hb2 of the light of holographic cell HUd and holographic element Hb2 diffraction does not satisfy the Bragg condition of holographic element Hc2, and they see through holographic element Hc2 invariably.

Object lens 60 are suitable for DVD most.So, holographic element Hb2 is increased aberration, to proofread and correct when hologram pattern forms aberration by the substrate thickness difference generation of BD and DVD.Holographic element Hc2 is increased aberration, to proofread and correct when hologram pattern forms aberration by the substrate thickness difference generation of CD and DVD.

Quarter-wave plate 55 is arranged in holographic element Hc2's+the X side.Diffraction optical element 56, opening wavelength filter plate 57 and object lens 60 are arranged similar to the above embodimentsly.

The operation of the optic pick-up 23 of following brief explanation present embodiment.

Explain the operation of the optic pick-up 23 when CD is BD.Enter collimation lens 52 from the plane polarized light of light source b1 emission by polarization holograms b3.Light enters holographic element Hb2 as parallel beam, by holographic element Hb2 diffraction.Converted to circularly polarized light by quarter-wave plate 55, be suitable for aberration compensation that sees through holographic element Hc2 and the opening restriction of BD by diffraction optical element 56.The opening that is suitable for BD by opening wavelength filter plate 57 limits, and light focuses on the recording layer of CD 15b by object lens 60.

The light that is received by CD 15b converts the circularly polarized light of opposite polarization to, and back light enters diffraction optical element 56 by object lens 60 and opening wavelength filter plate 57.The back light that diffracted optical element 56 converts parallel beam to enters quarter-wave plate 55, makes it convert linearly polarized light perpendicular to external travel to.This back light sees through holographic element Hc2 invariably, by holographic element Hb2 diffraction, enters polarization holograms b3 by collimation lens 52, is polarized hologram b3 deflection, and is received by photoelectric detector b2.

Explain the operation of the optic pick-up 23 when CD is DVD.Enter collimation lens 52 from the plane polarized light of light source d1 emission by polarization holograms d3.See through holographic element Hb2 and holographic element Hc2 invariably as parallel beam.

Light is converted to circularly polarized light by quarter-wave plate 55, sees through diffraction optical element 56 invariably, and the opening that is suitable for DVD by opening wavelength filter plate 57 limits, and light focuses on the recording layer of CD 15d by object lens 60.

The light that is received by CD 15d converts the circularly polarized light of opposite polarization to, and back light enters diffraction optical element 56 by object lens 60 and opening wavelength filter plate 57.The back light that diffracted optical element 56 converts parallel beam to enters quarter-wave plate 55, makes it convert linearly polarized light perpendicular to external travel to.This back light sees through holographic element Hc2 and holographic element Hb2 invariably, enters polarization holograms d3 by collimation lens 52, is polarized hologram d3 deflection, and is received by photoelectric detector d2.

Explain the operation of the optic pick-up 23 when CD is CD.Enter collimation lens 52 from the plane polarized light of light source c1 emission by polarization holograms c3.See through holographic element Hb2 as parallel beam, and enter holographic element Hc2.

Light is converted to circularly polarized light by quarter-wave plate 55, is undertaken by the aberration compensation of holographic element Hc2 diffraction and the opening restriction that is suitable for CD by diffraction optical element 56.Be suitable for the opening restriction of Cd by opening wavelength filter plate 57.Light focuses on the recording layer of CD 15c by object lens 60.

The light that is received by CD 15c converts the circularly polarized light of opposite polarization to, and back light enters diffraction optical element 56 by object lens 60 and opening wavelength filter plate 57.The back light that diffracted optical element 56 converts parallel beam to enters quarter-wave plate 55, makes it convert linearly polarized light perpendicular to external travel to.This back light is seen through holographic element Hb2 invariably by holographic element Hc2 diffraction, enters polarization holograms c3 by collimation lens 52, and is received by photoelectric detector c2.

As mentioned above, in the optic pick-up 23 of present embodiment, be provided with light source (b1, d1, c1), the holographic element Hc2 of the light that returns by object lens 60 of the light launched from light source c1 of the light of holographic element Hb2, the edge+directions X diffraction light sources c1 of the light that returns by object lens 60 from the light of light source b1 emission of the light of edge+directions X diffraction light sources b1 and diffraction and diffraction.Each holographic element is the plane of incidence of the incident light volume hologram element parallel with the output radiation face of diffraction light, and both arrange along X-direction.Therefore, can further improve the miniaturization of optic pick-up.

The invention is not restricted to the foregoing description, do not depart from the scope of the present invention and to retrofit.

In addition, the application is based on the Japanese patent application No.2006-012763 of Japanese patent application No.2005-336097 that submitted on November 21st, 2005 and submission on January 20th, 2006, and require the right of priority of above-mentioned two applications, its full content is incorporated herein by reference at this.

Claims (14)

1. light source cell comprises:

A plurality of light sources are launched a plurality of light beams; With

A plurality of volume hologram elements, be respectively applied for described a plurality of light source, each volume hologram element has the plane of incidence of incident beam and the output radiation face of diffracted beam, the plane of incidence of described incident beam and the output radiation face of described diffracted beam are perpendicular, described a plurality of volume hologram elements have differ from one another, the diffracted beam light intensity is set at maximum Bragg condition.

2. light source cell as claimed in claim 1, wherein, two adjacent volume holographic elements of described a plurality of volume hologram elements have the incident direction that differs from one another by a corresponding emitted light beams of described a plurality of light sources.

3. light source cell as claimed in claim 1, wherein, have intensity distributions with the symmetrical of this volume hologram element from the light of each diffraction of described a plurality of volume hologram elements, the half-breadth angle of the intensity distributions of diffracted beam is greater than the half-breadth angle of incident beam.

4. light source cell as claimed in claim 1, wherein, each volume hologram element has predetermined holographic region.

5. light source cell as claimed in claim 1, wherein, each volume hologram element has to change exports the lens function of diffracted beam with respect to the divergence of incident beam.

6. light source cell as claimed in claim 1, wherein, each volume hologram element is made by photopolymer or thermoplastics.

7. optical detector unit, it detects individually to a plurality of light beams, comprising:

A plurality of volume hologram elements, be respectively applied for described a plurality of light beam, each volume hologram element has the plane of incidence of incident beam and the output radiation face of diffracted beam, the plane of incidence of described incident beam and the output radiation face of described diffracted beam are perpendicular, described a plurality of volume hologram elements have differ from one another, the diffracted beam light intensity is set at maximum Bragg condition; With

A plurality of photoelectric detectors are respectively applied for described a plurality of volume hologram element, and each photoelectric detector receives from the light beam of a corresponding diffraction of described a plurality of volume hologram elements.

8. optical detector unit as claimed in claim 7, wherein, each of described a plurality of volume hologram elements has identical diffracted beam output radiation direction.

9. optical detector unit as claimed in claim 7, wherein, each volume hologram element has to change exports the lens function of diffracted beam with respect to the divergence of incident beam.

10. optical detector unit as claimed in claim 7, wherein, each volume hologram element is exported diffracted beam with astigmatism.

11. optical detector unit as claimed in claim 7, wherein, each volume hologram element is made by photopolymer or thermoplastics.

12. an optic pick-up, it transmits a light beam to CD and receives light beam from this CD reflection, comprising:

Light source cell as claimed in claim 1;

Optical system comprises object lens, and these object lens will focus on respectively on a plurality of recording layers of CD from a plurality of light beams of described light source cell emission; With

Photoelectric detector is used to receive the light beam from described CD reflection.

13. an optic pick-up, it transmits a light beam to CD and receives light beam from this CD reflection, comprising:

A plurality of light sources are launched a plurality of light beams;

Optical system comprises object lens, and these object lens will focus on respectively from described a plurality of light beams of described a plurality of light emitted on a plurality of recording layers of CD; With

Optical detector unit as claimed in claim 7, this optical detector unit are arranged on the light path of the light beam that returns by described object lens from CD, the light beam that returns with detection.

14. an optical disc apparatus, the reproduction that it is carried out from the information of CD comprises:

Optic pick-up as claimed in claim 12;

Processing unit is used to utilize the output of the photoelectric detector of optic pick-up, reproduces the information of current record on CD.

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