CN1767020A - Optical pickup apparatus and objective optical element - Google Patents

Abstract

The invention provides an optical pickup apparatus capable of realizing simplification of its constitution and cost reduction of the apparatus in the optical pickup apparatus on which an objective optical system is mounted, having a phase structure and capable of performing recording and/or reproduction of information suitably to three kinds of disks including a high density optical disk using a blue-purple laser light source, a DVD and a CD and having recording density different from each other and to provide an objective optical element. The optical pickup apparatus capable of performing recording and/or reproduction to three kinds of disks having recording density different from each other is characterized in that: the objective optical element with single-element lens is provided with a phase structure compensating at least one of a spherical aberration due to a difference between a protective substrate thickness t 1 and a protective substrate thickness t 2 and a spherical aberration due to a difference between a first wavelength lambda 1 and a second wavelength lambda 2; and a diffractive optical element that has a superimposed type diffractive structure having a wavelength selectivity for an diffraction action by which the first light flux and the second light flux are not diffracted, but the third light flux is diffracted.

Description

To thing optical element and optical take-up apparatus

Technical field

The present invention relates to a kind of can to different types of optical information recording media carry out interchangeably recording of information and/or reproduction optical take-up apparatus and to the thing optical element.

Background technology

In recent years, with regard to optical take-up apparatus, propelling as reproduction be recorded in the CD information or to the light source of cd-rom recording of information and the short wavelengthization of the LASER Light Source that is used, for example, make blue violet semiconductor laser, utilize the 2nd high frequency waves to carry out the blue SHC laser instrument etc. of the wavelength conversion of infrared semiconductor laser, wavelength is practical for the laser light source of 400-420nm.When using these blue violet semiconductor laser light sources, when using numerical aperture (NA) object lens identical with DVD (digital universal disc), can to diameter the information of the video disc recording 15-20GB of 12cm, being increased at the NA with object lens under 0.85 the situation, can be the information of the video disc recording 23-25GB of 12cm to diameter.Below, in this manual, will use the CD and the magneto-optic disk of blue-violet laser light source to be referred to as ' high density compact disc '.

In addition; using NA is in the high density compact disc of 0.85 object lens, because the coma aberration that disc tilt (skew: crooked) produces increase, so design protective seam thinner than DVD (with respect to the 0.6mm of DVD; be 0.1mm), to reduce the crooked coma aberration amount that causes.But, can be as long as think to the suitable recoding/reproduction information of such high density compact disc, the value of just not talkative product as compact disc player/writer is sufficient.At present, if according to DVD that sells the varied information of record or the reality of CD (compact disk), can be not enough only then to high density compact disc recoding/reproduction information, even if for example the user is to all DVD or CD recoding/reproduction information equally suitably, but improved the commodity value of the compact disc player/writer of using as high density compact disc like this.Under this background, have with the optical take-up apparatus on the compact disc player/writer the suitably performance of recoding/reproduction information of interchangeability limit is kept on the equal limit of high density compact disc and one of DVD and CD but expectation is loaded into high density compact disc.

As but high density compact disc and one of DVD and CD are all kept the suitably method of recoding/reproduction information of interchangeability limit in the limit, consideration is optionally switched high density compact disc optical system and DVD or the CD method with optical system corresponding to the recording density of the CD of recoding/reproduction information, but owing to need a plurality of optical systems, so be unfavorable for miniaturization, in addition, cost increases.

Therefore, in order to simplify the formation of optical take-up apparatus, realize cost degradation, with regard to optical take-up apparatus with interchangeability, preferably share high density compact disc with optical system and DVD or CD optical system, try one's best and reduce the number of the optics that constitutes optical take-up apparatus.In addition, share at the formation that object optical system is helped optical take-up apparatus most of CD configuration simplify, cost degradation.In addition, for the multiple CD that obtains having nothing in common with each other for the recoding/reproduction wavelength shared to object optical system, need in to object optical system, form the phase place structure of wavelength dependency with spherical aberration.

In the patent documentation 1, put down in writing a kind ofly have diffraction structure as phase place structure, can be used for jointly high density compact disc and existing DVD and CD to object optical system and loaded this optical take-up apparatus to object optical system.

Patent documentation 1: No. the 1304613rd, European publication

Yet, in the above-mentioned patent documentation 1 record can to 3 different discs carry out information record interchangeably and/or the optical take-up apparatus that reproduces in to the thing optical element owing to be along optical axis direction and object lens and form the structure that optical element that phase place constructs engages, so than relatively large, and it is heavy, when following the tracks of or focus on, make the burden of the actuator that drives it become big, therefore, existence has to use large-scale actuator, the densification that can't realize optical take-up apparatus and problem of energy saving.

Summary of the invention

The present invention has considered the problems referred to above and has made, its purpose is to provide a kind of and realizes constructing the optical take-up apparatus of simplification, cost degradation and to the thing optical element, this optical take-up apparatus loads following to the thing optical element, this has phase place structure to the thing optical element, can suitably carry out recording of information and/or reproduction to comprising the high density compact disc that uses the blue-violet laser light source and 3 kinds of different dishes of recording density of DVD and CD.

In order to address the above problem; 1 to the thing optical element be a kind of optical take-up apparatus to the thing optical element; the 1st light beam by the 1st wavelength X 1 that will penetrate from the 1st light source is that the information recording surface of the 1st optical information recording media of t1 forms the optically focused hot spot at protective substrate thickness; the reproduction of execution information and/or record; the 2nd light beam by the 2nd wavelength X 2 (λ 1＜λ 2) that will penetrate from the 2nd light source is that (information recording surface of the 2nd optical information recording media of t1≤t2) forms the optically focused hot spot to t2 at protective substrate thickness; the reproduction of execution information and/or record is characterized in that:

Described to the thing optical element be to the described the 1st and the 2nd optical information recording media common use to the thing optical element, be when having two phase places structures such as the 1st phase place structure and the 2nd phase place structure, at least one face is aspheric single element lens to the thing optical element

One of utilize described the 1st phase place to construct to compensate in the spherical aberration that the difference of spherical aberration that the difference of described protective substrate thickness t 1 and described protective substrate thickness t 2 causes or described the 1st wavelength X 1 and described the 2nd wavelength X 2 causes at least,

When the spherical aberration that produces when utilizing described the 2nd phase place to construct to compensate described the 1st wavelength X 1 to change in ± 10nm scope, described the 1st wavelength X 1 change in ± 10nm scope the best picture point of generation move, produce during variation of ambient temperature+spherical aberration in one of at least.

By the thing optical element being made as single element lens, can realize simplification, the cost degradation based on manufacturing process, the miniaturization of light-weighted actuator with described.In addition, utilize the 1st phase place structure to obtain the exchange of the 1st optical information recording media and the 2nd optical information recording media, in the spherical aberration that the best picture point of generation moved, produces during variation of ambient temperature when the spherical aberration that produces when utilizing the 2nd phase place to construct to compensate described the 1st wavelength X 1 to change in ± 10nm scope, described the 1st wavelength X 1 changed in ± 10nm scope one of at least, thereby can provide recording to the 1st optical information recording media good to the thing optical element.

In addition, in above-mentioned 1 the formation, so-called ' phase place structure ' is meant at each and takes turns the structure that interband is given phase differential.

In addition, so-called ' forming the optically focused hot spot ' is meant at the corrugated aberration to softening under (マ レ シ ヤ Le) state below the boundary, making light geometrical optics ground roughly be focused into 1 point.

Description of drawings

Fig. 1 is the pie graph that schematically illustrates optical take-up apparatus PU2.

Embodiment

In this manual; to use blue violet semiconductor laser or bluish violet SHG laser instrument to be referred to as ' high density compact disc ' with the CD (being also referred to as optical information recording media) of light source as information recording/regenerating; remove utilize NA be 0.85 object optical system is carried out recording of information/reproduction; and the thickness of protective seam is the CD (BD for example: the blue beam dish), also comprise and utilize NA for 0.65-0.67 object optical system to be carried out recording of information/reproduction of 0.1mm left and right sides specification; the thickness of protective seam is the CD (for example HD-DVD: also abbreviate HD as) of 0.6mm left and right sides specification.In addition, except that the thickness of the CD that on this information recording surface, has the CD of this protective seam, also be included in the diaphragm that has a few nm-tens nm left and right thicknesses on the information recording surface or protective seam or diaphragm be 0 CD.In addition, in this manual, in high density compact disc, also comprise and use blue violet semiconductor laser or bluish violet SHG laser instrument as the magneto-optic disk of information recording/regenerating with light source.

In addition, in this manual, so-called DVD is the general designation of DVD series CDs such as DVD-ROM, DVD-Video, DVD-Audio, DVD-RAM, DVD-R, DVD-RW, DVD+R, DVD+RW, and so-called CD is the general designation of CD series CDs such as CD-ROM, CD-Audio, CD-Video, CD-R, CD-RW.In the recording density, high density compact disc is the highest, reduces successively by the order of DVD, CD.

The following describes and be used to realize that the best of above-mentioned purpose constitutes.

2 described to the thing optical element for the thing optical element with regard to item 1, it is characterized in that: described the 1st phase place structure is overlapping type diffraction structure, the cross sectional shape that this overlapping type diffraction structure will comprise optical axis is that stair-stepping pattern arrangement becomes concentric circles, and surface level number by each regulation, the section of making displacement is corresponding to the hop count size of this surface level quantity height, and this overlapping type diffraction structure has the wavelength selectivity that does not make described the 1st beam diffraction, makes the diffraction of described the 2nd beam diffraction.

So-called ' overlapping type diffraction structure ' is meant following structure: it is a plurality of optical functions zone at center that at least one optical function face is divided into the optical axis, it is the zone of the wheel belt shape at center that in this a plurality of optical functions zone at least one is divided into the optical axis, and, take turns the discontinuous section difference that specified quantity is set in the band at each, simultaneously, dispose the wheel band that is provided with this discontinuous segment difference continuously.Overlapping type diffraction structure is also referred to as multilevel structure, DOE structure, for example, diffraction structure is that the optical function face with optical element is divided into the optical axis is a plurality of bands of taking turns at center, should take turns band and forming zigzag respectively, and the structure of the stage shape of specified quantity also is set in this sawtooth portion.Thus, can provide diffraction to optical element with wavelength selectivity.In addition, the height in the hop count of stage shape or stage, width etc. can suitably design.Particularly, open in flat No. 1706018 the record as the spy.

In addition, so-called ' optical function face ' is meant that utilization reflects or diffraction is helped the face that hot spot forms on this face.

If use 2 a described overlapping type diffraction structure to be used as the 1st phase place structure, then owing to can independently controlling the phase place of the 2nd light beam, so can compensate spherical aberration well to the 2nd light beam with wavelength selectivity of diffraction.As a result, can provide recording to the 2nd optical information recording media good to the thing optical element.

3 described to the thing optical element for the thing optical element with regard to item 2, it is characterized in that: the path difference that is additional on described the 1st light beam by a section difference of described overlapping type diffraction structure is 2 * λ 1, so be set in 2 times the degree of depth that is equivalent to the 1st wavelength X 1 by a section difference by the path difference conversion, can all guarantee high diffraction efficiency (transmitance) to the light beam of any wavelength with overlapping type diffraction structure.

4 described to the thing optical element for the thing optical element with regard to item 3, it is characterized in that: the surface level number of described regulation is 5.The diffraction efficiency that is received the light beam of diffraction by overlapping type diffraction structure depends on that not only a section is poor, also depends on surface level quantity.By this surface level quantity is set at 5, can make the diffraction efficiency maximum of the 2nd light beam.

5 described to the thing optical element for the thing optical element with regard to item 1, it is characterized in that: described the 1st phase place structure is the zigzag diffraction structure, establishing the diffraction number of times with the maximum diffraction light quantity in the diffraction light that is produced when described the 1st light beam incides described sawtooth diffraction structure is dor1, when the diffraction number of times with the maximum diffraction light quantity in the diffraction light that is produced when described the 2nd light beam incides described sawtooth diffraction structure is dor2, when satisfying following formula, describedly make described dor1 the diffraction light optically focused of described the 1st light beam to the information recording surface of described the 1st optical information recording media to the thing optical element, described dor2 the diffraction light optically focused that makes described the 2nd light beam is to the information recording surface of described the 2nd optical information recording media, dor1＞dor2, wherein, dor1 is an even number.

So-called ' zigzag diffraction structure ' is meant following structure, being about to that the optical function face is divided into the optical axis is a plurality of optical functions zone at center, it is the zone of the wheel belt shape at center that in this a plurality of optical functions zone at least one is divided into the optical axis, and, take turns the discontinuous section difference that specified quantity is set in the band at each, simultaneously, the optical axis direction cross section is a zigzag.

As the 1st phase place structure, also can use 5 a described sawtooth pattern diffraction structure with wavelength selectivity of diffraction number of times, can all have high diffraction efficiency at light beam to any wavelength in, compensate spherical aberration well to the 2nd light beam.

6 described to the thing optical element for the thing optical element with regard to item 5, it is characterized in that: described diffraction number of times dor1 is 2, described diffraction number of times dor2 is 1.If the diffraction number of times dor1 of the 1st light beam is made as 2, the diffraction number of times dor2 of the 2nd light beam is made as 1, then can make the compensation characteristic of the spherical aberration of the 2nd light beam best.

7 arbitrary described for the thing optical element to the thing optical element with regard to item 1-6, it is characterized in that: described the 2nd phase place structure is the zigzag diffraction structure, establishing the diffraction number of times with the maximum diffraction light quantity in the diffraction light that is produced when described the 1st light beam incides described sawtooth diffraction structure is dor1 ', when the diffraction number of times with the maximum diffraction light quantity in the diffraction light that is produced when described the 2nd light beam incides described sawtooth diffraction structure is dor2 ', when satisfying following formula, describedly make the inferior diffraction light optically focused of described dor1 ' of described the 1st light beam to the information recording surface of described the 1st optical information recording media to the thing optical element, the inferior diffraction light optically focused of described dor2 ' that makes described the 2nd light beam to the information recording surface of described the 2nd optical information recording media, dor1 '＞dor2 '.

As the 2nd phase place structure,, then can guarantee high diffraction efficiency to the 1st light beam and the 2nd light beam if use 7 a described sawtooth pattern diffraction structure with wavelength selectivity of diffraction number of times.Particularly, preferably use a combination of the described diffraction number of times of 8-10.

8 described to the thing optical element for the thing optical element with regard to item 7, it is characterized in that: described diffraction number of times dor1 ' is 2, described diffraction number of times dor2 ' is 1.

9 described to the thing optical element for the thing optical element with regard to item 7, it is characterized in that: described diffraction number of times dor1 ' is 5, described diffraction number of times dor2 ' is 3.

10 described to the thing optical element for the thing optical element with regard to item 7, it is characterized in that: described diffraction number of times dor1 ' is 10, described diffraction number of times dor2 ' is 6.

11 arbitrary described for the thing optical element to the thing optical element with regard to item 1-6, it is characterized in that: described the 2nd phase place is configured to path difference and gives structure, when establishing n and be natural number, utilize this path difference give structure be additional to path difference on described the 1st light beam be described the 1st wavelength X 1 5n doubly, utilize this path difference give structure be additional to path difference on described the 2nd light beam be described the 2nd wavelength X 2 3n doubly.

' path difference is given structure ' is to be with the structure that constitutes by central area that comprises optical axis and a plurality of wheel that has trickle section difference in the outside of this central area and cut apart, be meant structure with following characteristic, promptly under set point of temperature, path difference at the integral multiple that sees through the wavelength that produces incident beam between the corrugated of adjacent wheels band, under the situation that temperature changes from described set point of temperature, follow change of refractive, see through the integral multiple that the path difference that produces between the corrugated of adjacent wheels band departs from the wavelength of incident beam.Path difference is given structure and is also referred to as NPS (Non Periodic Surface) structure, phase place structure.

As the 2nd phase place structure, also can use 34 a described path difference to give structure with wavelength selectivity of additional path difference.Generally, can guarantee that wheel band gap ratio sawtooth pattern diffraction structure is big because path difference is given structure, thus can provide the light utilization ratio high to the thing optical element.

12 arbitrary described for the thing optical element to the thing optical element with regard to item 1-11, it is characterized in that: described the 1st phase place structure is formed on the optical surface of light source side, described the 2nd phase place structure is formed on the optical surface of optical information recording media side.Thus, the wheel interband that can guarantee the 1st phase place structure that the amount of spherical aberration that compensates Duo than the 2nd phase place structure is apart from greatly.

13 arbitrary described for the thing optical element to the thing optical element with regard to item 1-12, it is characterized in that: be m1 when establishing design multiplying power with respect to described the 1st wavelength, when being m2, satisfy following formula, m1=m2=0 with respect to the design multiplying power of described the 2nd wavelength.

By satisfying following formula, can the tracking with to the 1st optical information recording media and the 2nd optical information recording medium recorder/reproduction the time drive the coma aberration that is produced and become 0.

14 arbitrary described for the thing optical element to the thing optical element with regard to item 1-13, it is characterized in that: is the low melting point glass manufacturings that are less than or equal to 400 degree by tr pt Tg.By using this low-melting glass, can be when realizing the mould long lifetime, the viscosity during owing to fusion is low, so can utilize moulding to transcribe the phase place structure well.As this tr pt Tg is the low melting point glass that is less than or equal to 400 degree, and K-PG325, the K-PG375 of field optics society system arranged.

15 arbitrary described for the thing optical element to the thing optical element with regard to item 1-13, it is characterized in that: by resin manufacture.Described by using to the thing optical element, can because light weight reduces so can realize focusing on the power consumption that drives or follow the tracks of the actuator that drives usefulness, actuator can be become small-sized with the mass-produced at an easy rate while of stable performance.In addition, because the viscosity of molten condition is low, so can utilize moulding to transcribe the phase place structure well.

16 arbitrary described for the thing optical element to the thing optical element with regard to item 1-13, it is characterized in that: make resin bed be fitted in the lens surface of glass,, form described the 1st phase place structure or described the 2nd phase place structure on the surface of described resin bed.By using the stock of glass, can provide good temp characteristic to the thing optical element.In addition, as the material as resin bed, ultraviolet curable resin or heat-curing resin are fit on making.

17 for the thing optical element with regard to item 15 or 16 described to the thing optical element, it is characterized in that: follow the symbol of variations in refractive index rate of temperature variation opposite with described resin, making diameter is that the particle that is less than or equal to 30nm is distributed in the described resin.

Symbol as if the variations in refractive index rate of following temperature variation is opposite with described resin, and making diameter is that the particle that is less than or equal to 30nm is distributed in the resin, then obtains when keeping the mouldability of resin, follows the little material of variations in refractive index of temperature variation.Thus, can be provided at and can utilize moulding to come with the mass-produced at an easy rate while of stable performance, light weight and follow the variations in refractive index of temperature variation little to the thing optical element.

1st light beam of 18 optical take-up apparatus by the 1st wavelength X 1 that will penetrate from the 1st light source is that the information recording surface of the 1st optical information recording media of t1 forms the optically focused hot spot at protective substrate thickness; the reproduction of execution information and/or record; the 2nd light beam by the 2nd wavelength X 2 (λ 1＜λ 2) that will penetrate from the 2nd light source is that (information recording surface of the 2nd optical information recording media of t1≤t2) forms the optically focused hot spot to t2 at protective substrate thickness; the reproduction of execution information and/or record; the 3rd light beam by the 3rd wavelength X 3 (λ 2＜λ 3) that will penetrate from the 3rd light source is that (information recording surface of the 3rd optical information recording media of t2＜t3) forms the optically focused hot spot to t3 at protective substrate thickness; the reproduction of execution information and/or record is characterized in that: have

Single element lens to the thing optical element, be to described the 1st to the 3rd optical information recording media common use to the thing optical element, the phase place structure that one of has in the spherical aberration that the difference of spherical aberration that the difference of compensation described protective substrate thickness t 1 and described protective substrate thickness t 2 causes or described the 1st wavelength X 1 and described the 2nd wavelength X 2 causes at least, simultaneously, at least one face is an aspheric surface; With

Diffraction optical element, it is the diffraction optical element that is configured in the common light path of described the 1st to the 3rd light beam, form overlapping type diffraction structure, this structure is that the cross sectional shape that will comprise optical axis is that stair-stepping pattern arrangement becomes concentric circles and by the surface level number section of the making displacement of each regulation structure corresponding to the height of the hop count of this surface level quantity, has the wavelength selectivity that does not make described the 1st light beam and described the 2nd beam diffraction, makes the diffraction of described the 3rd beam diffraction.

If allow exchange performance, and the exchange performance both sides of the 1st optical information recording media and the 3rd optical information recording media that the thing optical element had the 1st optical information recording media and the 2nd optical information recording media, although then obtain can corresponding to the high-performance of 3 kinds of optical information recording medium recorder/reproductions to the thing optical element, but owing to the formation complexity to the thing optical element, so weight or constructions cost increase.Usually, in optical take-up apparatus, owing to utilize actuator to come high-speed driving to the thing optical element, so maximize or the viewpoint of thermal value increase etc. from the contact actuator, the weight of thing optical element is increased becomes problem.In addition, if the formation of thing optical element is complicated, then the external diameter to the thing optical element must become greatly, so produce the problem that can not be loaded in the slim optical take-up apparatus.

Therefore, optical take-up apparatus of the present invention allows the exchange performance that the thing optical element is had described the 1st optical information recording media and described the 2nd optical information recording media, allows diffraction optical element have the exchange performance of described the 1st optical information recording media and described the 3rd optical information recording media.Thus, can constitute single element lens to the thing optical element, can realize simplification, cost degradation, lightweight, the minor diameterization of described manufacturing process to the thing optical element described.

In addition, allowing described diffraction optical element have under the situation of exchange performance of described the 1st optical information recording media and described the 3rd optical information recording media, on design characteristics, preferably has the diffraction characteristic that only selectively makes the 3rd beam diffraction.Particularly, become concentric circles and be shifted corresponding to the overlapping type diffraction structure of the height of the hop count of this surface level quantity if constitute the cross sectional shape to comprise optical axis and be stair-stepping arranged in patterns, then can have this diffraction characteristic by surface level number, the section of making of each regulation.

The optical take-up apparatus of item 19 is with regard to item 18 described optical take-up apparatus, it is characterized in that: described phase place structure is overlapping type diffraction structure, the cross sectional shape that this overlapping type diffraction structure will comprise optical axis is that stair-stepping pattern arrangement becomes concentric circles, and surface level number by each regulation, the section of making displacement is corresponding to the height of the hop count of this surface level quantity, and this overlapping type diffraction structure has the wavelength selectivity that does not make described the 1st light beam and described the 3rd beam diffraction, makes the diffraction of described the 2nd beam diffraction.

If use 19 a described overlapping type diffraction structure to be used as the 1st phase place structure, then owing to can independently controlling the phase place of the 2nd light beam, so can compensate spherical aberration well to the 2nd light beam with wavelength selectivity of diffraction.As a result, can provide the optical take-up apparatus good to the recording of the 2nd optical information recording media.

The optical take-up apparatus of item 20 is with regard to item 19 described optical take-up apparatus, and it is characterized in that: the path difference that is additional on described the 1st light beam by a section difference of described overlapping type diffraction structure is 2 * λ 1.

Be set in 2 times the degree of depth that is equivalent to the 1st wavelength X 1 by a section difference by the path difference conversion, can all guarantee high diffraction efficiency (transmitance) the light beam of any wavelength with overlapping type diffraction structure.

The optical take-up apparatus of item 21 is with regard to item 20 described optical take-up apparatus, and it is characterized in that: the surface level number of described regulation is 5.The diffraction efficiency that is received the light beam of diffraction by overlapping type diffraction structure depends on that not only a section is poor, also depends on surface level quantity.By this surface level quantity is set at 5, can make the diffraction efficiency maximum of the 2nd light beam.

The optical take-up apparatus of item 22 is with regard to item 18 described optical take-up apparatus, it is characterized in that: described phase place structure is the zigzag diffraction structure, establishing the diffraction number of times with the maximum diffraction light quantity in the diffraction light that is produced when described the 1st light beam incides described sawtooth diffraction structure is dor1, diffraction number of times with the maximum diffraction light quantity in the diffraction light that is produced when described the 2nd light beam incides described sawtooth diffraction structure is dor2, when the diffraction number of times with the maximum diffraction light quantity in the diffraction light that is produced when described the 3rd light beam incides described sawtooth diffraction structure is dor3, when satisfying following formula, describedly make described dor1 the diffraction light optically focused of described the 1st light beam to the information recording surface of described the 1st optical information recording media to the thing optical element, described dor2 the diffraction light optically focused that makes described the 2nd light beam is to the information recording surface of described the 2nd optical information recording media, described dor3 the diffraction light optically focused that makes described the 3rd light beam is to the information recording surface of described the 3rd optical information recording media, dor1＞dor2 〉=dor3, wherein, dor1 is an even number.

As the 2nd phase place structure, also can use 22 a described sawtooth pattern diffraction structure with wavelength selectivity of diffraction number of times, when the 1st light beam and the 3rd light beam are had high diffraction efficiency, can compensate spherical aberration well to the 2nd light beam.As a result, can provide recording to the 2nd optical information recording media good to the thing optical element.

The optical take-up apparatus of item 23 is with regard to item 22 described optical take-up apparatus, and it is characterized in that: described diffraction number of times dor1 is 2, and described diffraction number of times dor2 is 1, and described diffraction number of times dor3 is 1.Thus, can make the compensation characteristic of the spherical aberration of the 2nd light beam best.

24 optical take-up apparatus is characterized in that with regard to the arbitrary described optical take-up apparatus of item 18-23: described phase place structure is formed on the optical surface of described light source side to the thing optical element.Thus, the wheel interband that can guarantee the 1st phase place structure that the amount of spherical aberration that compensates Duo than the 2nd phase place structure is apart from greatly.

The optical take-up apparatus of item 25 is with regard to the arbitrary described optical take-up apparatus of item 18-24, it is characterized in that: described the 1st light beam and described the 2nd light beam be all being parallel to described light beam state incident to the thing optical element, becomes 0 so can the tracking with to the 1st optical information recording media and the 2nd optical information recording medium recorder/reproduction the time drive the coma aberration that is produced.

The optical take-up apparatus of item 26 is characterized in that with regard to the arbitrary described optical take-up apparatus of item 18-25: described is the low melting point glass manufacturings that are less than or equal to 400 degree by tr pt Tg to the thing optical element.By using this low-melting glass, can be when realizing the mould long lifetime, the viscosity during owing to fusion is low, so can utilize moulding to transcribe the phase place structure well.As this tr pt Tg is the low melting point glass that is less than or equal to 400 degree, and K-PG325, the K-PG375 of field optics society system arranged.

27 optical take-up apparatus is characterized in that with regard to the arbitrary described optical take-up apparatus of item 18-25: described to the thing optical element by resin manufacture.By using resin in to the thing optical element, can because light weight reduces so can realize focusing on the power consumption that drives or follow the tracks of the actuator that drives usefulness, actuator can be become small-sized with the mass-produced at an easy rate while of stable performance described.In addition, because the viscosity of molten condition is low, so can utilize moulding to transcribe the phase place structure well.

28 optical take-up apparatus is characterized in that with regard to the arbitrary described optical take-up apparatus of item 18-25: describedly make resin bed be fitted in the lens surface of glass to the thing optical element, on the surface of described resin bed, form described phase place structure.By using the stock of glass, can provide good temp characteristic to the thing optical element.In addition, as the material as resin bed, ultraviolet curable resin or heat-curing resin are fit on making.

29 optical take-up apparatus is characterized in that with regard to item 27 or 28 described optical take-up apparatus: follow the symbol of variations in refractive index rate of temperature variation opposite with described resin, making diameter is that the particle that is less than or equal to 30nm is distributed in the described resin.

Symbol as if the variations in refractive index rate of following temperature variation is opposite with described resin, and making diameter is that the particle that is less than or equal to 30nm is distributed in the resin, then obtains when keeping the mouldability of resin, follows the little material of variations in refractive index of temperature variation.Thus, can be provided at and can utilize moulding to come with the mass-produced at an easy rate while of stable performance, light weight and follow the variations in refractive index of temperature variation little to the thing optical element.

The optical take-up apparatus of item 30 is with regard to the arbitrary described optical take-up apparatus of item 18-29, it is characterized in that: described also have following phase place structure to the thing optical element, the best picture point of generation moves, produces during in variation of ambient temperature during variation in ± 10nm scope for the spherical aberration that described the 1st wavelength X 1 of this phase place structure compensation produces when changing in ± 10nm scope, described the 1st wavelength X 1+in the spherical aberration one of at least.

Obtain the exchange of the 1st optical information recording media and the 3rd optical information recording media by utilizing described the 1st phase place structure, in the spherical aberration that the best picture point of generation moved, produces during in variation of ambient temperature when the spherical aberration that produces when utilizing described the 2nd phase place to construct to compensate described the 1st wavelength X 1 to change in ± 10nm scope, described the 1st wavelength X 1 changed in ± 10nm scope one of at least, thereby can provide recording to the 1st optical information recording media good to the thing optical element.

The optical take-up apparatus of item 31 is with regard to the arbitrary described optical take-up apparatus of item 18-30, and it is characterized in that: described the 3rd light beam incides described in the thing optical element after being transformed into divergent beams by the overlapping type diffraction structure of described diffraction optical element.By the overlapping type diffraction structure that utilizes described diffraction optical element described the 3rd optical beam transformation is divergent beams, makes it to incide described, can compensate the spherical aberration that the difference of protective substrate thickness t 1 and protective substrate thickness t 3 causes the thing optical element.

The optical take-up apparatus of item 32 is with regard to item 31 described optical take-up apparatus, it is characterized in that: be formed at Abbe number on the d line of the described overlapping type diffraction structure in the described diffraction optical element in the scope of 40-80, the path difference that is additional on described the 1st light beam by a section difference of described overlapping type diffraction structure is 5 * λ 1.

Under the situation in the scope of Abbe number on the d of the described overlapping type diffraction structure line at 40-80, if be set in 5 times the degree of depth that is equivalent to the 1st wavelength X 1 by the path difference conversion, then utilize this section difference to be additional to path difference on the 2nd light beam and become 3 times of the 2nd wavelength X 2 by a section difference that will described overlapping type diffraction structure.Thus, can improve the transmitance of described diffraction optical element to the 1st light beam and the 2nd light beam, can provide also can be corresponding to the optical take-up apparatus that writes at a high speed to described the 1st optical information recording media and the 2nd optical information recording media.

The optical take-up apparatus of item 33 is with regard to item 32 described optical take-up apparatus, and it is characterized in that: the described prescribed level face quantity of described overlapping type diffraction structure is 2.Be set at 2 by surface level number, can make the design load maximum of the diffraction efficiency of described the 3rd light beam described overlapping type diffraction structure.

The optical take-up apparatus of item 34 is with regard to item 31 described optical take-up apparatus, it is characterized in that: be formed at Abbe number on the d line of the described overlapping type diffraction structure in the described diffraction optical element in the scope of 20-40, the path difference that is additional on described the 1st light beam by a section difference of described overlapping type diffraction structure is 7 * λ 1.

Under the situation in the scope of Abbe number on the d of the described overlapping type diffraction structure line at 20-40, if be set in 7 times the degree of depth that is equivalent to the 1st wavelength X 1 by the path difference conversion, then utilize this section difference to be additional to path difference on the 2nd light beam and become 4 times of the 2nd wavelength X 2 by a section difference that will described overlapping type diffraction structure.Thus, can improve the transmitance of described diffraction optical element to the 1st light beam and the 2nd light beam, can provide also can be corresponding to the optical take-up apparatus that writes at a high speed to described the 1st optical information recording media and the 2nd optical information recording media.

The optical take-up apparatus of item 35 is with regard to item 34 described optical take-up apparatus, and it is characterized in that: in the overlapping type diffraction structure of described diffraction optical element, described prescribed level face quantity is 3 or 4.Be set at 3 or 4 by surface level number, can make the design load maximum of the diffraction efficiency of described the 3rd light beam described overlapping type diffraction structure.

The optical take-up apparatus of item 36 is with regard to item 31 described optical take-up apparatus, it is characterized in that: described diffraction optical element has along the formation of optical axis direction stacking material C and material D, Abbe number on the d line of material C is in the scope of 45-65, and, refractive index on the d line is in the scope of 1.45-1.55, Abbe number on the d line of material D is in the scope of 20-40, and, refractive index on the d line is in the scope of 1.55-1.70, and described overlapping type diffraction structure is formed in the interface of described material C and described material D.

If as diffraction optical element as described in constituting as described in the item 36, then because can obtain transmitance (diffraction efficiency) diffraction optical element all high to the light beam of any wavelength, also can be so can provide corresponding to the optical take-up apparatus that writes at a high speed to any optical information recording media.

The optical take-up apparatus of item 37 is with regard to item 36 described optical take-up apparatus, it is characterized in that: the path difference that is additional on described the 1st light beam by a section difference of described overlapping type diffraction structure is 2 * λ 1, so can make the design load maximum of the transmitance (diffraction efficiency) of the light beam of each wavelength.

The optical take-up apparatus of item 38 is with regard to item 37 described optical take-up apparatus, it is characterized in that: in the overlapping type diffraction structure of described diffraction optical element, described prescribed level face quantity is 5 or 6, so can make the design load maximum of the transmitance (diffraction efficiency) of the light beam of each wavelength.

39 optical take-up apparatus is characterized in that with regard to the arbitrary described optical take-up apparatus of item 18-38: described diffraction optical element be make it to incide after the angle of divergence of described the 1st light beam of conversion described to the coupling optical element in the thing optical element.Have the function of diffraction optical element by making it to incide described coupling optical element after the angle of divergence that makes conversion the 1st light beam, can cut down the components number of optical take-up apparatus the thing optical element.

40 optical take-up apparatus is characterized in that with regard to the arbitrary described optical take-up apparatus of item 18-39: described diffraction optical element be make it to incide behind the beam diameter of described the 1st light beam of conversion described to the optical beam expander optical system in the thing optical element.Described the optical beam expander optical system of thing optical element is had the function of diffraction optical element by making to make it to incide behind conversion the 1st beam diameter, can cut down the components number of optical take-up apparatus.

The optical take-up apparatus of item 41 is characterized in that with regard to the arbitrary described optical take-up apparatus of item 18-40: described to thing optical element and described diffraction optical element formation one, carry out to follow the tracks of driving.It is 0 that tracking when making described the 3rd optical information recording medium recorder/reproduction drives the coma aberration that is produced, and can obtain better tracking.

The optical take-up apparatus of item 42 is with regard to the arbitrary described optical take-up apparatus of item 18-41, it is characterized in that: described optical take-up apparatus is configured in described the 1st light source and described in the light path between the thing optical element, possesses Chromatically compensated optical element, the described diffraction structure that the best picture point of thing optical element is moved of generation when in ± 10nm scope, changing that this Chromatically compensated optical element forms described the 1st wavelength X 1 of compensation.

In addition, so-called ' aberration ' is meant the dislocation of optically focused hot spot on optical axis direction of wavelength variations front and back.But establishing the optically focused hot spot here is the locational hot spot that is formed at corrugated aberration minimum.Factor as wavelength variations, laser instrument vibration when supposing the individual difference that comprises laser instrument, mode hopping, temperature variation, but because aberration constitutes problem is the wavelength variations of not following etc. moment with respect to the action of the dislocation on the optical axis direction, actuator, so mainly be compensated for as object with mode hopping.

The optical take-up apparatus of item 43 is with regard to item 42 described optical take-up apparatus, and it is characterized in that: described Chromatically compensated optical element is the optical element identical with described diffraction optical element.By allowing the diffraction optical element of exchange function have the function of Chromatically compensated element, can cut down the components number of optical take-up apparatus with described the 1st optical information recording media and described the 3rd optical information recording media.

The optical take-up apparatus of item 44 is with regard to the arbitrary described optical take-up apparatus of item 18-43, it is characterized in that: described optical take-up apparatus has spherical aberration compensation mechanism, when this spherical aberration compensation mechanism compensates described the 1st wavelength X 1 and changes in ± 10nm scope by the described spherical aberration that the thing optical element is produced, during in variation of ambient temperature by in the described spherical aberration that the thing optical element is produced one of at least, so can widen tolerance to the oscillation wavelength of described the 1st light source, in addition, can widen spendable temperature range.

The optical take-up apparatus of item 45 is with regard to item 44 described optical take-up apparatus, it is characterized in that: described spherical aberration compensation mechanism has and can make light beam to described mobile optical element that the incident angle of thing optical element is changed and the actuator that moves this mobile optical element along optical axis direction by moving along optical axis, so, can guarantee that the compensation range of spherical aberration is wide making described mobile optical element move along optical axis direction under the situation of compensating for spherical aberration.

The optical take-up apparatus of item 46 is with regard to item 45 described optical take-up apparatus, it is characterized in that: described mobile optical element is described diffraction optical element, so, can cut down the components number of optical take-up apparatus by allowing the described diffraction optical element of exchange function move along optical axis direction with described the 1st optical information recording media and described the 3rd optical information recording media.

47 optical take-up apparatus is characterized in that with regard to item 44 described optical take-up apparatus: described spherical aberration compensation mechanism is a liquid crystal cell.Under the situation of utilizing described liquid crystal cell compensating for spherical aberration, need not movable part can finish, so help the miniaturization of optical take-up apparatus.

The optical take-up apparatus of item 48 is with regard to the arbitrary described optical take-up apparatus of item 18-47, it is characterized in that: also have oscillator and drive described actuator the thing optical element, when described the 3rd optical information recording media being carried out recording of information/reproduction, following described tracking to the thing optical element drives, it is described to the thing optical element to come oscillator to drive by described actuator, so when described the 3rd optical information recording media being carried out recording of information/reproduction, by offsetting the coma aberration that the inclination of thing optical element is produced by described, with drive the coma aberration that produces by described tracking to the thing optical element, obtain better tracking all the time.

In this manual, so-called the thing optical element is meant under the state that optical information recording media is seated in the optical take-up apparatus, on the position of the most close optical information recording media side, configuration, that the have the optically focused effect relatively optical element of Ying Yuqi.

According to the present invention, as a kind of optical take-up apparatus, load following to the thing optical element, this has the phase place structure to the thing optical element, can use high density compact disc and 3 kinds of dishes DVD and CD, that recording density is different of blue-violet laser light source suitably carry out recording of information and/or reproduction to comprising, can obtain realizing its constitute simplify, the optical take-up apparatus of cost degradation and to the thing optical element.

Below, with figure embodiments of the present invention are described.At first, illustrate with Fig. 1 of the present invention to the thing optical element with use this optical take-up apparatus to the thing optical element.

Fig. 1 schematically illustrates high density compact disc BD, DVD and the arbitrary pie graph that can suitably carry out the optical take-up apparatus PU2 of recording of information/reproduction of CD.The optical specification of BD is the 1st wavelength X 1=405nm; the thickness t 1=0.1mm of protective seam PL1; numerical aperture NA1=0.85; the optical specification of DVD is the 2nd wavelength X 2=655nm; the thickness t 2=0.6mm of protective seam PL2, numerical aperture NA2=0.65, the optical specification of CD is the 3rd wavelength X 3=785nm; the thickness t 3=1.2mm of protective seam PL3, numerical aperture NA3=0.51.But the thickness of wavelength, protective seam and the combination of numerical aperture are not limited thereto.

Optical take-up apparatus PU2 comprises: blue violet semiconductor laser LD1, and luminous when BD being carried out recording of information/reproductions, the bluish violet color laser light beam (the 1st light beam) of ejaculation 405nm; Laser module LM has the 2nd luminous point EP2, sensitization of the infrared laser light beam (the 3rd light beam) of the 1st luminous when DVD being carried out recording of information/reproductions, as to penetrate the red laser light beam (the 2nd light beam) of 655nm luminous point EP1, luminous when CD being carried out recording of information/reproduction, ejaculation 785nm from the 1st photographic department DS1 of the folded light beam of the information recording surface RL2 of DVD, sensitization the 2nd photographic department DS2 and the prism PS from the folded light beam of the information recording surface RL3 of CD; The photodetector PD that BD uses; To thing optical element OL; 2 shaft actuator AC1; 1 shaft actuator AC2; Collimation lens COL as coupling optical element or mobile optical element; The 1st polarized beam splitting device BS1; The 2nd polarized beam splitting device BS2; To the sensor leads SEN that uses from the additional astigmatism of the folded light beam of information recording surface RL1, RL2 and RL3; 1/4 wavelength plate QWP; Aperture STO corresponding to the numerical aperture NA1 of BD; Carry out the wavelength selective filters WF of the numerical aperture restriction of DVD and CD.In addition, the light source as BD uses except that above-mentioned blue violet semiconductor laser LD1, also can use bluish violet SHG laser instrument.

With regard to optical take-up apparatus PU2, when BD being carried out recording of information/reproduction, utilize 1 shaft actuator AC2 that the position of solid line among Fig. 1 is adjusted in the position of collimation lens COL, penetrate the 1st light beam with state from collimation lens COL with parallel beam.Afterwards, make blue violet semiconductor laser LD1 luminous.Among Fig. 1; its opticpath of stating of line drawing is such strictly according to the facts; the divergent beams that penetrate from blue violet semiconductor laser LD1 are reflected by the 1st polarized beam splitting device BS1; by the 2nd polarized beam splitting device BS2; after being transformed to parallel beam by collimation lens COL; by 1/4 wavelength plate QWP; thereby be transformed to rotatory polarization from linear polarization; come the confine optical beam diameter by aperture STO; see through after the wavelength selective filters WF, by thing optical element OL is constituted the hot spot that is formed on the information recording surface RL1 through the protective seam PL1 of BD.Utilizing the 2 shaft actuator AC1 that are configured on its periphery to carry out to thing optical element OL focuses on or follows the tracks of.

After folded light beam after information recording surface RL1 is by the information pits modulation sees through thing optical element OL, aperture STO once more, by 1/4 wavelength plate QWP, thereby be transformed to linear polarization from rotatory polarization once more, COL becomes converging beam by collimation lens, after seeing through the 2nd polarized beam splitting device BS2, the 1st polarized beam splitting device BS1, by the additional astigmatism of sensor leads SEN, converge on the light-sensitive surface of photodetector PD.In addition, can use the output signal of photodetector PD to come the information of reading and recording in BD.

In addition, with regard to optical take-up apparatus PU2, when DVD being carried out recording of information/reproduction, utilize 1 shaft actuator AC2 that the position of dotted line among Fig. 1 is adjusted in the position of collimation lens COL, penetrate the 2nd light beam with state from collimation lens COL with parallel beam.The position of collimation lens COL of this moment is comparison BD more close position to thing optical element OL when carrying out recording of information/reproduction.Afterwards, make the 1st luminous point EP1 luminous.Among Fig. 1; as its opticpath that dotted line is described; the divergent beams that penetrate from the 1st luminous point EP1 are reflected by prism PS and the 2nd polarized beam splitting device BS1; after being transformed to parallel beam by collimation lens COL; by 1/4 wavelength plate QWP; thereby be transformed to rotatory polarization from linear polarization, after coming the confine optical beam diameter, by thing optical element OL is constituted the hot spot that is formed on the information recording surface RL2 through the protective seam PL2 of DVD by wavelength selective filters WF.Utilizing the 2 shaft actuator AC1 that are configured on its periphery to carry out to thing optical element OL focuses on or follows the tracks of.

After folded light beam after information recording surface RL2 is by the information pits modulation sees through thing optical element OL, wavelength selective filters WF once more, by 1/4 wavelength plate QWP, thereby be transformed to linear polarization from rotatory polarization once more, COL becomes converging beam by collimation lens, reflect by the 2nd polarized beam splitting device BS2, in prism PS, behind 2 secondary reflections, converge on the 1st photographic department DS1.In addition, can use the output signal of the 1st photographic department DS1 to come the information of reading and recording in DVD.

In addition, with regard to optical take-up apparatus PU2, when CD being carried out recording of information/reproduction, utilize 1 shaft actuator AC2 to adjust collimation lens COL, to be in position (position of dotted line among Fig. 1) identical when DVD being carried out recording of information/reproduction.Afterwards, make the 2nd luminous point EP2 luminous.Among Fig. 1; as its opticpath that dot-and-dash line is described; the divergent beams that penetrate from the 2nd luminous point EP2 are reflected by prism PS and the 2nd polarized beam splitting device BS1; after being transformed to divergent beams by collimation lens COL; by 1/4 wavelength plate QWP; thereby be transformed to rotatory polarization from linear polarization, after coming the confine optical beam diameter, by thing optical element OL is constituted the hot spot that is formed on the information recording surface RL3 through the protective seam PL3 of CD by wavelength selective filters WF.Utilizing the 2 shaft actuator AC1 that are configured on its periphery to carry out to thing optical element OL focuses on or follows the tracks of.

After folded light beam after information recording surface RL3 is by the information pits modulation sees through thing optical element OL, wavelength selective filters WF once more, by 1/4 wavelength plate QWP, thereby be transformed to linear polarization from rotatory polarization once more, COL becomes converging beam by collimation lens, reflect by the 2nd polarized beam splitting device BS2, in prism PS, behind 2 secondary reflections, converge on the 2nd photographic department DS2.In addition, can use the output signal of the 2nd photographic department DS2 to come the information of reading and recording in CD.

Two faces to thing optical element OL of present embodiment are aspheric surface, form the zigzag diffraction structure on the aspheric surface of light source side.This zigzag diffraction structure is to be used to compensate because of the protection bed thickness of BD and the phase place structure of the different spherical aberrations that cause of protection bed thickness of DVD; the diffraction number of times dor1 of the maximum diffraction light quantity in the diffraction light that will produce in the time of will having the 1st light beam incident is made as 2; the diffraction number of times dor2 of the maximum diffraction light quantity in the diffraction light that will produce in the time of will having the 2nd light beam incident is made as 1; the diffraction number of times dor3 of the maximum diffraction light quantity in the diffraction light that will produce in the time of will having the 3rd light beam incident is made as 1, will make wavelength (flash of lightization wavelength X B) and be made as 405nm.

Like this, determining that the diffraction efficiency of sawtooth pattern diffraction structure of the wavelength dependency of diffraction number of times is 100% for the 1st light beam, is 88.3% for the 2nd light beam, is 100% for the 3rd light beam, and the light beam of any wavelength is all had high diffraction efficiency.

It is above-mentioned that thing optical element OL is preferably used glass or makes diameter is to be less than or equal to the resin that the oxide of 30nm disperses to form.

Generally, if micropowder is blended in the transparent resin material, then produce scattering of light, transmitance descends, thus be difficult to as optical material, but, in fact can not produce scattering as can be known by making micropowder form the size littler than the wavelength of transmitted beam.

Plastic resin (also can abbreviate resin as) rises along with temperature, and refractive index descends, but inorganic particulate is along with temperature rises, and refractive index rises.Therefore, also know by their the character effect that cancels each other out, thereby do not produce variations in refractive index.The inorganic particulate that optical element of the present invention is less than or equal to 30 nanometers, is preferably less than or equals 20 nanometers by making, be more preferably the 10-15 nanometer is distributed to as the material in the resin of stock and forms.Therefore, can provide the temperature dependency that do not have refractive index or the low-down optical element of temperature dependency of refractive index.

For example, make niobium oxide (Nb ₂O ₅) particulate be distributed in the allyl resin.Volume ratio as the plastics of stock is 80, and the ratio of niobium oxide is about 20, with they even mixing.There is the problem of cohesion easily in particulate, provides electric charge to make it technology such as dispersion but utilize to particle surface, can produce necessary disperse state.

As described later, the mixing of resin and particle, online execution when disperseing to be preferably in the ejection formation of optical element.At this moment, after mixing, disperseing, be shaped to before the optical element, preferably do not cool off, solidify.

In addition,, can suitably increase and decrease this volume ratio, also can mix and make it behind the multiple nano-scale inorganic particulate to disperse in order to control refractive index to the variation of temperature ratio.

Ratio is 80: 20 in above-mentioned example, promptly 4: 1, but can suitably adjust between (9: 1)-60: 40 (3: 2) at 90: 10.If lacked than 9: 1, then temperature variation inhibition effect diminishes, and on the contrary, if surpass 3: 2, then the mouldability owing to resin has problems, so bad.

Particulate is inorganics preferably, and oxide preferably.In addition, preferably the state of oxidation saturated, be more preferably unoxidized oxide.

Being that inorganics is in order to suppress lowly with the reaction as the plastic resin of macromolecular organic compound, in addition, is the deterioration that oxide can prevent to follow use.Especially waited under the harsh condition in high temperatureization or irradiating laser, easy accelerating oxidation is if but the particulate of this inorganic oxide then can be prevented the deterioration that oxidation causes.

In addition, for the resin oxidation that prevents that other factors from causing, much less, also can add preventing oxygenant.And, as the plastic resin of stock preferably suitably adopt special be willing to 2002-308933 number, specially be willing to 2002-309040 number, special resin described in being willing to 2002-308964 number etc.

Below, the method to the thing optical element of moulding present embodiment is described.As mentioned above, just make particle be distributed to technology in the finely divided resin, the known method that allows particle have electric charge.

For example, tabular plastic resin is filled in the container, makes particle inject in this container, disperse, heat in this container, make the plastic resin fusion.At this moment, dispersed particle is dispersed in the plastic resin of fusion.At this moment, in order to prevent precipitation, also can stir or apply electric field, magnetic field, or ultrasound wave is provided.

In addition, also consider when making the plastic resin ejection formation of fusion, use and wait the method for adding particle at the embedding stirrer.At this moment, because be mixed into spiral fashion on line, so can form disperse state well.

Here, make disperseed the cooling of atomic plastic resin one end, solidified after, when fusion and ejection formation, utilize heating, fusion more once more, disperse state changes, or produces small sintering in the resin of particle periphery, so bad.Especially producing under the situation of sintering, the position of sintering, light penetration can descend, and worry can not be used as optical element.

Therefore, preferably make a fusion of plastic resin, and the limit disperses particle, the limit keeps the state of fusion and dispersion constant, obtains the moulding product.That is, being preferably in and making diameter is after the particle that is less than or equal to 30 nanometers is distributed in the plastic resin of molten condition, to keep molten condition to flow into unchangeably in the mould, obtains the moulding product.

In addition, the collimation lens COL in the present embodiment is made as aspheric surface with two faces, forms overlapping type diffraction structure on the aspheric surface of CD side.This overlapping type diffraction structure is following structure, this structure has the wavelength selectivity that does not make the 1st light beam and the 2nd beam diffraction, makes the diffraction of the 3rd beam diffraction, a section difference converts by path difference and is set at 7 times the degree of depth that is equivalent to the 1st wavelength X 1, the surface level quantity that forms in each pattern is set at 4, and the section of making displacement is corresponding to 3 sections height of surface level quantity 4.

Because the refractive index of relative the 1st wavelength X 1 of collimation lens COL is 1.649231, so section difference Δ 1 is Δ 1=7 * 0.405/ (1.649231-1)=4.367 micron.

Because the path difference L that is additional to the 1st light beam by section difference Δ 1 is 7 times of the 1st wavelength X 1,, not seen through by any land used former state of doing so the 1st light beam utilizes overlapping type diffraction structure.

In addition, because the refractive index of relative the 2nd wavelength X 2 of collimation lens COL is 1.592675, so being additional to path difference M on the 2nd light beam by section difference Δ 1 is M=4.367 * (1.592675-1)/0.655=3.95, be roughly 4 times of the 2nd wavelength X 2, the 2nd light beam also utilizes overlapping type diffraction structure, not seen through by any land used former state of doing.

On the other hand, because the refractive index of relative the 3rd wavelength X 3 of collimation lens COL is 1.583833, so being additional to path difference N on the 3rd light beam by section difference Δ 1 is N=4.367 * (1.583833-1)/0.785=3.24, the phase differential of the 3rd light beam by section difference Δ 1 front and back surface level (deducting optically the phase differential for the integral multiple size of equiphase 2 π) is 2 π * 0.24.Because the surface level quantity in pattern is 4,, produce 1 time diffraction light so the phase differential of the 3rd light beam just in time is 4 * 2 π * 0.24 , 2 π in pattern.

Like this, overlapping type diffraction structure is divergent beams by only optionally making the 3rd beam diffraction with the 3rd optical beam transformation that incides collimation lens COL, the spherical aberration that the protective layer thickness of compensation BD and the protective layer thickness difference of CD cause.

In addition, the diffraction efficiency of 0 diffraction light of the 1st light beam that overlapping type diffraction structure produces (seeing through light) is 100%, the diffraction efficiency of 0 diffraction light of the 2nd light beam (seeing through light) is 88.8%, the diffraction efficiency of 1 diffraction light of the 3rd light beam is 81.0%, and any light beam is all obtained high diffraction efficiency.

In addition, by driving collimation lens COL along optical axis direction, can compensate the spherical aberration of the hot spot on the information recording surface RL1 that is formed at BD by 1 shaft actuator AC2.Thickness difference XOR thickness distribution that the foozle of the focusing jump between the information recording layer of the variations in refractive index of the objective system that the generation reason of utilizing the spherical aberration that the position adjustment of collimation lens COL compensates for example is the wavelength difference that causes of the foozle of the 1st light source LD1, follow temperature variation or index distribution, 2 layers of dish, 4 layers of multilayer disc such as dish, the protective seam of high density compact disc causes etc.

In addition, be formed at the method for the spherical aberration of the hot spot on the information recording surface RL1 of BD by way of compensation, along optical axis direction drives the method for lens, also can use the phase control element of utilizing liquid crystal except that above-mentioned.Because this method of utilizing phase control element to come compensating for spherical aberration is known, omit detailed explanation here.

In addition, in the present embodiment, constitute and be respectively applied for DVD/CD with among laser module LM and the blue violet semiconductor laser LD1, but be not limited thereto, the light source that also can use on a chip light source that forms the luminous point that penetrates each wavelength light beam, maybe will penetrate each wavelength light beam is contained in a light source in the housing.

But 3 actuators that also can use oscillator to drive thing optical element OL replace 2 shaft actuator AC1, when CD being carried out recording of information/reproduction, if constituting the tracking that follows thing optical element OL drives to make thing optical element OL oscillator is driven, then, obtain better tracking all the time by offsetting coma aberration that produces by inclination and the coma aberration that produces by tracking driving to the thing optical element to thing optical element OL.At this moment, preferably have tracking driving direction and the amount that is used to detect to thing optical element OL, the direction of determining the oscillator driving and the detection part of amount.

(embodiment 1)

The following describes embodiment.Embodiment 1 is that optical take-up apparatus shown in Figure 1 the best can be to BD and DVD record and/or information reproduction the time is to the thing optical element.Present embodiment the thing optical element is used overlapping type diffraction structure in the 1st phase place structure, in the 2nd phase place structure, use the zigzag diffraction structure.Table 1 illustrates the lens data of embodiment 1.

[table 1]

Embodiment 1 lens data

The focal distance f of object lens ₁=2.2mm f ₂=2.33mm

Image planes side numerical aperture NA1:0.85 NA2:0.65

Multiplying power m1:0 m2:0

The 1st	ri	di(408nm)	ni(408nm)	di(658nm)	ni(658nm)
						0		∞		∞
1 (diaphragm diameter)		0.0(φ3.74mm)		0.0(φ3.00mm)
						2	1.51092	2.7218	1.58088	2.7218	1.54201
2′	1.51114	0.0058		0.0058
						3	-4.34310	0.7220	1.00000	0.5167	1.00000
3′	-4.57662	0.0055		0.0055
						4	∞	0.0875	1.81829	0.5000	1.57759
5	∞

* di ' expression is from the displacement of di face to the d ' face.

The 2nd (0mm≤h≤1.5mm)

Asphericity coefficient

κ -8.3883E-01

A4 1.2349E-02

A6 1.7825E-03

A8 4.1580E-04

A10 -1.9458E-04

A12 9.4828E-05

A14 -4.8971E-08

A18 -2.3937E-08

Path difference function (HD:0 time DVD:1 time manufacturing wavelength 858nm)

C2 5.2068E-03

C4 -8.2816E-04

C6 -3.0096E-04

C8 8.0071E-05

C10 -5.9393E-05

The 2nd ' face (1.5mm＜h)

Asphericity coefficient

κ -8.5040E-01

A4 1.1532E-02

A6 1.4352E-03

A8 5.3870E-04

A10 -1.0806E-04

A12 9.5991E-05

A14 -1.2971E-05

A16 -1.8571E-06

The 3rd (0mm≤h≤0.724mm)

Asphericity coefficient

κ -2.8463E+01

A4 1.5123E-01

A6 -3.0848E-02

A8 1.3536E-01

A10 1.1740E-01

A12 -1.8602E-01

A14 -2.0101E-01

A16 2.3207E-01

Path difference function (HD:2 time DVD:1 time manufacturing wavelength 408nm)

C2 -2.6782E-02

C4 1.4623E-02

C6 -5.8807E-02

C8 -3.3239E-02

C10 2.9169E-02

The 3rd ' face (0.724mm＜h)

Asphericity coefficient

κ -7.1388E+01

A4 1.2626E-01

A8 -5.1183E-02

A8 -1.3075E-02

A10 1.0554E-02

A12 -5.5870E-05

A14 -6.9040E-04

A18 -1.2880E-04

Path difference function (HD:2 DVD:1 System Zao Bo Long 408nm)

C2 -3.3777E-02

C4 3.8380E-03

C6 -7.9583E-03

C8 3.6009E-03

C10 2.6098E-04

(embodiment 2)

Embodiment 2 is that optical take-up apparatus shown in Figure 1 the best can be to BD and DVD record and/or information reproduction the time is to the thing optical element.Present embodiment to thing optical element use zigzag diffraction structure in the 1st layer structure and the 2nd layer structure.Table 2 illustrates the lens data of embodiment 2.

[table 2]

Embodiment 2 lens datas

BD: wavelength 408nm, NA0.85, diaphragm diameter φ 3.74mm, focal length 2.19mm, multiplying power m1=0

DVD: wavelength 658nm, NA0.65, diaphragm diameter φ 2.92mm, focal length 2.28mm, multiplying power m2=0

[paraxial data]

The face sequence number	r(mm)	d(mm)	N 408	N 658	n d	v d	Remarks
								OBJ		d0					Luminous point
STO		0.0000					Aperture
								1	(following table)	2.6100	1.56088	1.54201	1.54500	56.5	Object lens
2	(following table)	d1
							3	∞	d2	1.61838	1.57729	1.58300	29.9	Protective seam
4	∞

d0 _BD＝∞，d0 _DVD＝∞，d1 _BD＝0.6955，d1 _DVD＝0.4595，d2 _BD＝0.0875，d2 _DVD＝0.6000

[the 1st paraxial radius-of-curvature, asphericity coefficient [the 2nd paraxial radius-of-curvature, asphericity coefficient,

The diffraction number of times, make wavelength, path difference function coefficients] the diffraction number of times, make wavelength, path difference function coefficients number]

	The 1st
				AREA1 (0≤h≤1.470)	AREA2 (1.470≤h)
r	0.16003E+01	0.14503E+01
			κ A4 A6 A8 A10 A12 A14 A16 A18 A20	-0.69759E+00 0.19073E-01 0.29142E-02 0.19191E-02 -0.11345E-02 0.43871E-03 0.14121E-03 -0.12241E-03 0.40143E-04 -0.37526E-05	-0.60683E+00 0.712373E-02 0.47259E-03 0.13594E-02 -0.11580E-02 0.24480E-03 0.20431E-03 -0.16629E-03 0.47056E-04 -0.49059E-05
dor1/dor2	+2/+1	+2/+1
			λB	395nm	408nm
C2 C4 C8 C8 C10 C12	-0.10408E-01 0.26118E-02 0.64081E-03 -0.15882E-03 0.74834E-04 0.16438E-05	-0.32198E-04 0.47110E-03 -0.27645E-03 -0.11577E-03 -0.21487E-04 0.47998E-05

	The 2nd
				AREA3 (0≤h≤0.705)	AREA4 (0.705≤h)
r	-0.14000E+01	-0.19885E+01
			κ A4 A6 A8 A10 A12 A14 A16 A18 A20	-0.99016E+01 0.19102E+00 0.25038E+00 0.67639E-01 -0.35295E-01 0.11623E-01 -0.15094E-02 -0.25902E-03 0.15519E-03 -0.31407E-04	-0.57468E+02 0.12161E+00 -0.11229E+00 0.68498E-01 -0.34503E-01 0.11666E-01 -0.18233E-02 -0.16008E-03 0.15519E-03 -0.31407E-04
dor1/dor2	+10/+6	+10/+6
			λB	408nm	408nm
C2 C4 C6 C8 C10 C12	0.10902E-01 -0.12436E-01 -0.18154E-01 -0.54043E-02 0.77483E-02 0.00000E+00	-0.46731E-05 0.10324E-03 -0.23946E-04 0.49847E-04 0.24277E-04 -0.25523E-04

(embodiment 3)

Embodiment 3 is that optical take-up apparatus shown in Figure 1 the best can be to BD, DVD and CD record and/or information reproduction the time is to the thing optical element.Present embodiment to thing optical element use zigzag diffraction structure in the 1st layer structure and the 2nd layer structure.Table 3 illustrates the lens data of embodiment 3.

[table 3]

Embodiment 3 lens datas

HD: wavelength 405nm, NA0.87, diaphragm diameter φ 3.74mm, focal length 2.20mm, multiplying power m1=0

DVD: wavelength 655nm, NA0.65, diaphragm diameter φ 2.82mm, focal length 2.29mm, multiplying power m2=0

CD: wavelength 785nm, NA0.49, diaphragm diameter φ 2.20mm, focal length 2.25mm, multiplying power m3=-0.079

[paraxial data]

The face sequence number	r(mm)	d(mm)	N 405	N 655	N 785	n d	v d	Remarks
									OBJ		d0						Luminous point
STO		0.1000						Aperture
									1	1.7212	2.6500	1.59794	1.57686	1.57278	1.58000	55.0	Object lens
2	-5.1209	d1
								3	∞	d2	1.62230	1.57995	1.57326	1.58546	29.9	Protective seam
4	∞

d0 _BD＝∞，d0 _DVD＝∞，d0 _CD＝30.000，d1 _BD＝0.8836，d1 _DVD＝0.4599，d1 _CD＝0.2130，

d2 _BD＝0.1000，d2 _DVD＝0.6000，d2 _CD＝1.2000

[asphericity coefficient]

	The 1st	The 2nd
			κ A4 A6 A8 A10 A12 A14 A16 A18 A20	-0.65304E+00 0.99796E-02 0.77332E-03 0.20940E-02 -0.11888E-02 0.28323E-03 0.21358E-03 -0.16956E-03 0.45165E-04 -0.43064E-05	-0.91636E+01 0.10223E+00 -0.97621E-01 0.81148E-01 -0.42512E-01 0.11361E-01 -0.123931E-02 0.00000E+00 0.00000E+00 0.00000E+00

[path difference function coefficients]

	The 1st	The 2nd
			dor1/dor2/dor3	+2/+1/+1	+3/+2/+2
λB	405nm	405nm
			C2 C4 C6 C8 C10	-0.12829E-01 0.11572E-02 0.36418E-03 0.11007E-03 0.18491E-04	-0.80018E-02 -0.80255E-02 0.3B433E-03 0.35407E-03 0.69999E-04

(embodiment 4)

Embodiment 4 is that optical take-up apparatus shown in Figure 1 the best can be to HD-DVD, DVD and CD record and/or information reproduction the time is to the thing optical element.Present embodiment to thing optical element use zigzag diffraction structure in the 1st layer structure and the 2nd layer structure.Table 4 illustrates the lens data of embodiment 4.

[table 4]

Embodiment 4 lens datas

HD: wavelength: 405nm, NA0.87, diaphragm diameter φ 4.00mm, focal length 2.99mm, multiplying power m1=0

DVD: wavelength 655nm, NA0.65, diaphragm diameter φ 3.96mm, focal length 3.05mm, multiplying power m2=0

CD: wavelength 785nm, NA0.47, diaphragm diameter φ 2.80mm, focal length 3.04mm, multiplying power m3=0

[paraxial data]

The face sequence number	r(mm)	d(mm)	N 405	N 655	N 785	n d	v d	Remarks
									OBJ		∞						Luminous point
STO		0.0000						Aperture
									1	1.9543	2.3000	1.56702	1.54702	1.54316	1.55000	55.0	Object lens
2	-9.8737	d1
								3	∞	d2	1.61950	1.57721	1.57042	1.58276	29.7	Protective seam
4	∞

d1 _HD＝1.3813，d1 _DVD＝1.4347，d1 _CD＝1.0575，

d2 _HD＝0.6000，d2 _DVD＝0.6000，d2 _CD＝1.2000

[asphericity coefficient]

	The 1st	The 2nd
			κ A4 A6 A8 A10 A12	-0.75360E+00 0.31704E-02 0.46671E-03 -0.11132E-03 0.33864E-04 -0.47967E-05	-0.82111E+02 0.19470E-01 -0.51261E-02 0.53752E-03 -0.13614E-04 0.00000E+00

[path difference function coefficients]

	The 1st	The 2nd
			dor1/dor2/dor3	+2/+1/+1	+3/+2/+2
λB	405nm	405nm
			C2 C4 C6 C8 C10	0.21212E-02 -0.13977E-03 -0.74642E-05 -0.85522E-05 0.10475E-05	-0.55686E-02 -0.16757E-02 0.39867E-03 -0.32364E-04 -0.15612E-05

(embodiment 5)

Embodiment 5 is as the most preferred embodiment by the optical system that thing optical element and collimation lens are constituted of optical take-up apparatus shown in Figure 1.Present embodiment to the thing optical element in, as phase place structure, form the zigzag diffraction structure, in collimation lens, form overlapping type diffraction structure.Table 5 illustrates the lens data of embodiment 5.

[table 5]

Embodiment 5 lens datas

BD: wavelength 405nm, NA0.85, diaphragm diameter φ 3.74mm, focal length 2.86mm, multiplying power m1=0

DVD: wavelength 655nm, NA0.65, diaphragm diameter φ 2.90mm, focal length 2.82mm, multiplying power m2=0

CD: wavelength 785nm, NA0.51, diaphragm diameter φ 2.42mm, focal length 2.29mm, multiplying power m3=-0.12

[paraxial data]

The face sequence number	r(mm)	d(mm)	N 405	N 655	N 785	n d	v d	Remarks
									OBJ		d0						Luminous point
1	-609.80	1.5000	1.64923	1.59266	1.58383	1.60000	23.0	Collimation lens
									2	-9.5948	d1
STO		0.1000															Aperture
								4	1.7658	2.6500	1.59794	1.57686	1.57278	1.58000	55.0	Object lens
5	-3.8522	d2
								6	∞	d3	1.62230	1.57995	1.57326	1.58548	29.9		Protective seam
7	∞

d0 _BD＝14.0770，d0 _DVD＝15.4754，d0 _CD＝15.4754，d1 _BD＝5.0000，d1 _DVD＝3.6017，d1 _CD＝3.6017，

d2 _BD＝0.6674，d2 _DVD＝0.4589，d2 _CD＝0.2998、d3 _BD＝0.1000，d3 _DVD＝0.6000，d3 _CD＝1.2000

[asphericity coefficient]

	The 2nd	The 4th	The 5th
				κ A4 A8 A8 A10 A12 A14 A16 A18 A20	-0.12786E+01 -0.96881E-04 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00	-0.62683E+00 0.10341E-01 0.11898E-02 0.22890E-02 -0.11516E-02 0.29813E-03 0.21377E-03 -0.16962E-03 0.45196E-04 -0.428077E-05	0.39566E+00 0.99505E-01 -0.96848E-01 0.81413E-01 -0.42252E-01 0.11468E-01 -0.11986E-02 -0.20853E-04 0.00000E+00 0.00000E+00

[path difference function coefficients]

	The 2nd	The 4th
			dor1/dor2/dor3	0/0/+1	+2/+1/+1
λB	785nm	405nm
			C2 C4 C8 C8 C10	0.28855E-01 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00	-0.16111E-01 0.12615E-02 0.46951E-03 0.14268E-03 0.25277E-04

Claims (48)

1, a kind of optical take-up apparatus to the thing optical element; described optical take-up apparatus is that the information recording surface of the 1st optical information recording media of t1 forms the optically focused hot spot at protective substrate thickness by the 1st light beam that makes the 1st wavelength X 1 that penetrates from the 1st light source; carry out the reproduction and/or the record of information; and the 2nd light beam by making the 2nd wavelength X 2 (λ 1＜λ 2) that penetrates from the 2nd light source is that (information recording surface of the 2nd optical information recording media of t1≤t2) forms the optically focused hot spot to t2 at protective substrate thickness; carry out the reproduction and/or the record of information, it is characterized in that:

Described to the thing optical element be by described the 1st optical information recording media and the 2nd optical information recording media shared to the thing optical element, be have that the 1st phase place structure and the 2nd phase place construct that these two phase places are constructed and at least one face be aspheric single element lens to the thing optical element

In the spherical aberration of utilizing described the 1st phase place to construct to compensate spherical aberration that the difference by described protective substrate thickness t 1 and described protective substrate thickness t 2 causes and causing by the difference of described the 1st wavelength X 1 and described the 2nd wavelength X 2 one of at least,

The best picture point that the spherical aberration that is produced when utilizing described the 2nd phase place to construct to compensate described the 1st wavelength X 1 to change in ± 10nm scope, described the 1st wavelength X 1 are produced during variation in ± 10nm scope moves, produced during in variation of ambient temperature+in the spherical aberration one of at least.

2, according to claim 1 to the thing optical element, it is characterized in that:

Described the 1st phase place structure is overlapping type diffraction structure, the cross sectional shape that this overlapping type diffraction structure will comprise optical axis is that stair-stepping pattern arrangement becomes concentric circles, and surface level number by each regulation, the section of making only is shifted the height corresponding to the hop count of this surface level number, and this overlapping type diffraction structure has the wavelength selectivity that does not make described the 1st light beam generation diffraction and make the diffraction of described the 2nd light beam generation diffraction.

3, according to claim 2 to the thing optical element, it is characterized in that:

The path difference that is additional on described the 1st light beam by a section difference of described overlapping type diffraction structure is 2 * λ 1.

4, according to claim 3 to the thing optical element, it is characterized in that:

The surface level number of described regulation is 5.

5, according to claim 1 to the thing optical element, it is characterized in that:

Described the 1st phase place structure is the zigzag diffraction structure, establish the diffraction number of times with the maximum diffraction light quantity in the diffraction light that is produced when described the 1st light beam incides described sawtooth diffraction structure is dor1, when the diffraction number of times with the maximum diffraction light quantity in the diffraction light that is produced when described the 2nd light beam incides described sawtooth diffraction structure is dor2, when satisfying following formula, described described dor1 the diffraction light optically focused that the thing optical element is made described the 1st light beam is to the information recording surface of described the 1st optical information recording media, and described dor2 the diffraction light optically focused that makes described the 2nd light beam is to the information recording surface of described the 2nd optical information recording media:

Dor1＞dor2, wherein, dor1 is an even number.

6, according to claim 5 to the thing optical element, it is characterized in that:

Described diffraction number of times dor1 is 2, and described diffraction number of times dor2 is 1.

7, arbitrary described according to claim 1-6 to the thing optical element, it is characterized in that:

Described the 2nd phase place structure is the zigzag diffraction structure, establish the diffraction number of times with the maximum diffraction light quantity in the diffraction light that is produced when described the 1st light beam incides described sawtooth diffraction structure is dor1 ', when the diffraction number of times with the maximum diffraction light quantity in the diffraction light that is produced when described the 2nd light beam incides described sawtooth diffraction structure is dor2 ', when satisfying following formula, the described inferior diffraction light optically focused of described dor1 ' that the thing optical element is made described the 1st light beam is to the information recording surface of described the 1st optical information recording media, and the inferior diffraction light optically focused of described dor2 ' that makes described the 2nd light beam is to the information recording surface of described the 2nd optical information recording media:

dor1’＞dor2’。

8, according to claim 7 to the thing optical element, it is characterized in that:

Described diffraction number of times dor1 ' is 2, and described diffraction number of times dor2 ' is 1.

9, according to claim 7 to the thing optical element, it is characterized in that:

Described diffraction number of times dor1 ' is 5, and described diffraction number of times dor2 ' is 3.

10, according to claim 7 to the thing optical element, it is characterized in that:

Described diffraction number of times dor1 ' is 10, and described diffraction number of times dor2 ' is 6.

11, arbitrary described according to claim 1-6 to the thing optical element, it is characterized in that:

Described the 2nd phase place is configured to path difference and gives structure, when establishing n and be natural number, utilize this path difference give structure be additional to path difference on described the 1st light beam be described the 1st wavelength X 1 5n doubly, utilize this path difference give structure be additional to path difference on described the 2nd light beam be described the 2nd wavelength X 2 3n doubly.

12, arbitrary described according to claim 1-11 to the thing optical element, it is characterized in that:

Described the 1st phase place structure is formed on the optical surface of light source side, and described the 2nd phase place structure is formed on the optical surface of optical information recording media side.

13, arbitrary described according to claim 1-12 to the thing optical element, it is characterized in that:

Be m1 when establishing design multiplying power with respect to described the 1st wavelength, when being m2, satisfy following formula with respect to the design multiplying power of described the 2nd wavelength:

m1＝m2＝0。

14, arbitrary described according to claim 1-13 to the thing optical element, it is characterized in that:

By tr pt Tg is that the low melting point glass that is less than or equal to 400 degree is made.

15, arbitrary described according to claim 1-13 to the thing optical element, it is characterized in that:

Be formed from a resin.

16, arbitrary described according to claim 1-13 to the thing optical element, it is characterized in that:

Make resin bed be fitted in the lens surface of glass,, form described the 1st phase place structure or described the 2nd phase place structure on the surface of described resin bed.

17, according to claim 15 or 16 described, it is characterized in that the thing optical element:

Follow the symbol of variations in refractive index rate of temperature variation opposite with described resin, making diameter is that the particle that is less than or equal to 30nm is distributed in the described resin.

18, a kind of optical take-up apparatus is that the information recording surface of the 1st optical information recording media of t1 forms the optically focused hot spot at protective substrate thickness by the 1st light beam that makes the 1st wavelength X 1 that penetrates from the 1st light source, carries out the reproduction and/or the record of information; The 2nd light beam by making the 2nd wavelength X 2 (λ 1＜λ 2) that penetrates from the 2nd light source is that (information recording surface of the 2nd optical information recording media of t1≤t2) forms the optically focused hot spot to t2, carries out the reproduction and/or the record of information at protective substrate thickness; And the 3rd light beam by making the 3rd wavelength X 3 (λ 2＜λ 3) that penetrates from the 3rd light source is that (information recording surface of the 3rd optical information recording media of t2＜t3) forms the optically focused hot spot to t3 at protective substrate thickness, carry out the reproduction and/or the record of information, it is characterized in that, comprise: single element lens to the thing optical element, be by described the 1st to the 3rd optical information recording media shared to the thing optical element, phase place structure one of at least in the spherical aberration that has spherical aberration that compensation causes by the difference of described protective substrate thickness t 1 and described protective substrate thickness t 2 and cause by the difference of described the 1st wavelength X 1 and described the 2nd wavelength X 2, and at least one face is an aspheric surface; With

Diffraction optical element, it is the diffraction optical element that is configured in the common optical pathways of described the 1st to the 3rd light beam, form overlapping type diffraction structure, this overlapping type diffraction structure is that the cross sectional shape that will comprise optical axis is that stair-stepping pattern arrangement becomes concentric circles and only is shifted structure corresponding to the height of the hop count of this surface level number by the surface level number section of making of each regulation, has the wavelength selectivity that does not make described the 1st light beam and described the 2nd light beam generation diffraction and make the diffraction of described the 3rd light beam generation diffraction.

19, optical take-up apparatus according to claim 18 is characterized in that:

Described phase place structure is overlapping type diffraction structure, the cross sectional shape that this overlapping type diffraction structure will comprise optical axis is that stair-stepping pattern arrangement becomes concentric circles, and surface level number by each regulation, the section of making only is shifted the height corresponding to the hop count of this surface level number, and this overlapping type diffraction structure has the wavelength selectivity that does not make described the 1st light beam and described the 3rd light beam generation diffraction and make the diffraction of described the 2nd light beam generation diffraction.

20, optical take-up apparatus according to claim 19 is characterized in that:

The path difference that is additional on described the 1st light beam by a section difference of described overlapping type diffraction structure is 2 * λ 1.

21, optical take-up apparatus according to claim 20 is characterized in that:

The surface level number of described regulation is 5.

22, optical take-up apparatus according to claim 18 is characterized in that:

Described phase place structure is the zigzag diffraction structure, establish the diffraction number of times with the maximum diffraction light quantity in the diffraction light that is produced when described the 1st light beam incides described sawtooth diffraction structure is dor1, diffraction number of times with the maximum diffraction light quantity in the diffraction light that is produced when described the 2nd light beam incides described sawtooth diffraction structure is dor2, when the diffraction number of times with the maximum diffraction light quantity in the diffraction light that is produced when described the 3rd light beam incides described sawtooth diffraction structure is dor3, when satisfying following formula, describedly make described dor1 the diffraction light optically focused of described the 1st light beam to the information recording surface of described the 1st optical information recording media to the thing optical element, described dor2 the diffraction light optically focused that makes described the 2nd light beam is to the information recording surface of described the 2nd optical information recording media, and described dor3 the diffraction light optically focused that makes described the 3rd light beam is to the information recording surface of described the 3rd optical information recording media:

Dor1＞dor2 〉=dor3, wherein, dor1 is an even number.

23, optical take-up apparatus according to claim 22 is characterized in that:

Described diffraction number of times dor1 is 2, and described diffraction number of times dor2 is 1, and described diffraction number of times dor3 is 1.

24, according to the arbitrary described optical take-up apparatus of claim 18-23, it is characterized in that:

Described phase place structure is formed on the optical surface of described light source side to the thing optical element.

25, according to the arbitrary described optical take-up apparatus of claim 18-24, it is characterized in that:

Described the 1st light beam and described the 2nd light beam are all to be parallel to described light beam state incident to the thing optical element.

26, according to the arbitrary described optical take-up apparatus of claim 18-25, it is characterized in that:

Described is that the low melting point glass that is less than or equal to 400 degree is made to the thing optical element by tr pt Tg.

27, according to the arbitrary described optical take-up apparatus of claim 18-25, it is characterized in that:

Described the thing optical element is formed from a resin.

28, according to the arbitrary described optical take-up apparatus of claim 18-25, it is characterized in that:

Describedly resin bed is fitted on the lens surface of glass, on the surface of described resin bed, forms described phase place structure the thing optical element.

29, according to claim 27 or 28 described optical take-up apparatus, it is characterized in that:

Follow the symbol of variations in refractive index rate of temperature variation opposite with described resin, making diameter is that the particle that is less than or equal to 30nm is distributed in the described resin.

30, according to the arbitrary described optical take-up apparatus of claim 18-29, it is characterized in that:

Described also have following phase place structure to the thing optical element, the best picture point that the spherical aberration that described the 1st wavelength X 1 of this phase place structure compensation is produced when changing in ± 10nm scope, described the 1st wavelength X 1 are produced during variation in ± 10nm scope moves, produced during in variation of ambient temperature+in the spherical aberration one of at least.

31, according to the arbitrary described optical take-up apparatus of claim 18-30, it is characterized in that:

Described the 3rd light beam incides described in the thing optical element after the overlapping type diffraction structure by described diffraction optical element is transformed into divergent beams.

32, optical take-up apparatus according to claim 31 is characterized in that:

Be formed at Abbe number on the d line of the described overlapping type diffraction structure in the described diffraction optical element in the scope of 40-80, the path difference that is additional on described the 1st light beam by a section difference of described overlapping type diffraction structure is 5 * λ 1.

33, optical take-up apparatus according to claim 32 is characterized in that:

The described prescribed level face quantity of described overlapping type diffraction structure is 2.

34, optical take-up apparatus according to claim 31 is characterized in that:

Be formed at Abbe number on the d line of the described overlapping type diffraction structure in the described diffraction optical element in the scope of 20-40, the path difference that is additional on described the 1st light beam by a section difference of described overlapping type diffraction structure is 7 * λ 1.

35, optical take-up apparatus according to claim 34 is characterized in that:

In the overlapping type diffraction structure of described diffraction optical element, described prescribed level face quantity is 3 or 4.

36, optical take-up apparatus according to claim 31 is characterized in that:

Described diffraction optical element has the material C of making and material D along the stacked structure of optical axis direction, Abbe number on the d line of wherein said material C in the scope of 45-65 and the refractive index on the d line in the scope of 1.45-1.55, and the Abbe number on the d line of described material D in the scope of 20-40 and the refractive index on the d line in the scope of 1.55-1.70, described overlapping type diffraction structure is formed on the interface of described material C and described material D.

37, optical take-up apparatus according to claim 36 is characterized in that:

The path difference that is additional on described the 1st light beam by a section difference of described overlapping type diffraction structure is 2 * λ 1.

38, according to the described optical take-up apparatus of claim 37, it is characterized in that:

In the overlapping type diffraction structure of described diffraction optical element, described prescribed level face quantity is 5 or 6.

39, according to the arbitrary described optical take-up apparatus of claim 18-38, it is characterized in that:

Described diffraction optical element be make it to incide after the angle of divergence of described the 1st light beam of conversion described to the coupling optical element in the thing optical element.

40, according to the arbitrary described optical take-up apparatus of claim 18-39, it is characterized in that:

Described diffraction optical element be make it to incide behind the beam diameter of described the 1st light beam of conversion described to the optical beam expander optical system in the thing optical element.

41, according to the arbitrary described optical take-up apparatus of claim 18-40, it is characterized in that:

Described to thing optical element and described diffraction optical element formation execution tracking integratedly driving.

42, according to the arbitrary described optical take-up apparatus of claim 18-41, it is characterized in that:

Described optical take-up apparatus is configured in described the 1st light source and described in the light path between the thing optical element, and comprising Chromatically compensated optical element, this Chromatically compensated optical element forms in order to compensate the described diffraction structure that the best picture point of thing optical element is moved that described the 1st wavelength X 1 is produced during variation in the scope of ± 10nm.

43, according to the described optical take-up apparatus of claim 42, it is characterized in that:

Described Chromatically compensated optical element is the optical element identical with described diffraction optical element.

44, according to the arbitrary described optical take-up apparatus of claim 18-43, it is characterized in that:

Described optical take-up apparatus has spherical aberration compensation mechanism, when this spherical aberration compensation mechanism compensates described the 1st wavelength X 1 and changes in the scope of ± 10nm during by the described spherical aberration that the thing optical element is produced with in variation of ambient temperature by in the described spherical aberration that the thing optical element is produced one of at least.

45, according to the described optical take-up apparatus of claim 44, it is characterized in that:

Described spherical aberration compensation mechanism has and can make light beam to described mobile optical element that the incident angle of thing optical element is changed and the actuator that moves this mobile optical element along optical axis direction by moving along optical axis.

46, according to the described optical take-up apparatus of claim 45, it is characterized in that:

Described mobile optical element is described diffraction optical element.

47, according to the described optical take-up apparatus of claim 44, it is characterized in that:

Described spherical aberration compensation mechanism is a liquid crystal cell.

48, according to the arbitrary described optical take-up apparatus of claim 18-47, it is characterized in that:

Also have oscillator and drive described actuator, when described the 3rd optical information recording media being carried out recording of information/reproductions, follow described tracking and drive, come the oscillator driving described the thing optical element by described actuator to the thing optical element to the thing optical element.

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