CN101105956B

CN101105956B - Optical pickup apparatus, objective optical element and optical information recording and/or reproducing apparatus

Info

Publication number: CN101105956B
Application number: CN2007101283915A
Authority: CN
Inventors: 野村英司; 中村健太郎
Original assignee: Konica Minolta Opto Inc
Current assignee: Konica Minolta Opto Inc
Priority date: 2006-07-14
Filing date: 2007-07-10
Publication date: 2012-06-20
Anticipated expiration: 2027-07-10
Also published as: CN101105956A; CN101123100A; CN101123100B

Abstract

An optical pickup apparatus comprises: a first light source; a second light source; a third light source; and an objective optical element. The objective optical element comprises at least two areas comprising first and second optical path difference providing structures. A third light flux from the third light source passing the first optical path difference providing structure forms first and second best focuses. The third light flux passing the objective optical element forms a spot comprising a central spot portion; an intermediate spot portion; and a peripheral spot portion. The central spot portion is used for recording and/or reproducing information for a third optical disk, and the intermediate and peripheral spot portions are not used for recording and/or reproducing information for the third optical disk. The peripheral spot portion is formed on the third optical disk by the third light flux through the second optical path difference providing structure.

Description

Optical take-up apparatus, to thing optical element and optical data recording/reproducing device

Technical field

The present invention relates to interchangeable mode to different CDs can carry out the optical take-up apparatus of recording of information and/or playback, to thing optical element and optical data recording/reproducing device.

Background technology

In recent years; In optical take-up apparatus; The short wavelengthization of the laser light source that uses as the playback of the information that has been used for writing down on the CD or to the light source of the recording of information of CD has obtained progress; For example, blue violet semiconductor laser, the laser light source of wavelength 400～420nm of blue SHG laser instrument etc. that utilizes the 2nd higher-order wave to carry out the wavelength conversion of infrared semiconductor laser are being realized practicability.If use these blue violet semiconductor lasers; Then under the situation of using the numerical aperture (NA) identical to the thing optical element with DVD (digital universal disc); Can carry out the recording of information of 15～20GB for the CD of diameter 12cm; Make NA to the thing optical element up to 0.85 situation under, can carry out the recording of information of 23～25GB for the CD of diameter 12cm.Below, in this manual, the CD and the photomagneto disk that use the blue-violet laser light source are generically and collectively referred to as " high density compact disc ".

In addition; In the high density compact disc that uses NA0.85 to the thing optical element; Increase owing to resulting from the coma aberration that the gradient (crooked) of CD takes place; So have with DVD in situation compare design protective seam thinner (, being 0.1mm) for the 0.6mm of DVD to reduce high density compact disc because of the crooked coma aberration amount that causes.But, to speak of and can only suitably carry out recording of information/playback such high density compact disc, the value of the not talkative sometimes goods as compact disc player/writer is sufficient.If according to now selling the DVD that has write down diversified information, the reality of CD (mini disk); It is not enough then can only carrying out recording of information/playback to such high density compact disc; Improved the commodity value of the compact disc player/writer of using as high density compact disc even for example also can likewise, suitably carry out recording of information/playback this point for all DVD of user, CD, this point is understandable.According to such background, even hope that the optical take-up apparatus of installation in compact disc player/writer that high density compact disc is used etc. has for high density compact disc, DVD and then be that any of CD can be kept the interchangeability function of recording/reproducing information suitably again.

As for high density compact disc, DVD and then be that any of CD can be kept the interchangeability method of recording/reproducing information suitably again; Can consider to change selectively the method for the optical system that optical system that high density compact disc uses and DVD, CD use according to the recording density of the CD of recording/reproducing information; But because a plurality of optical systems must be arranged; So to miniaturization is disadvantageous, in addition, cost has increased.

Thereby; Simplification, cost degradation for the structure of seeking to realize optical take-up apparatus; Even in having the optical take-up apparatus of interchangeability, the optical system that optical system that high density compact disc uses and DVD, CD are used becomes common system and reduces the optics number that constitutes optical take-up apparatus as far as possible is comparatively desirable.And making common becomes best to thing optical element this point to simplification, the cost degradation of the structure of optical take-up apparatus with dispose opposed to each other the thing optical element is become of CD.In addition, for obtain for the mutually different multiple CD of recording/reproducing wavelength common to the thing optical element, be necessary that in the path difference that forms the wavelength interdependence with spherical aberration gives structure to object optical system.

In document 1, put down in writing have as path difference give structure diffraction structure, for high density compact disc, existing DVD and CD can jointly use to object optical system and this optical take-up apparatus to object optical system has been installed.

No. the 1304689th, [document 1] European publication

Yet; For used in the optical take-up apparatus of in above-mentioned patent documentation 1, having put down in writing, can carry out recording of information and/or playback with interchangeable mode to 3 different CDs to the thing optical element; Design specification according to optical take-up apparatus; There is the danger of the deficiency in light quantity be used to write down and/or reset, or is difficult to take place the danger of suitable flare at the record that carries out CD, DVD and/or playback time.

Summary of the invention

The present invention has considered above-mentioned problem, reaches one of following at least purpose.At first; The optical take-up apparatus that its purpose is to provide following, to thing optical element and optical data recording/reproducing device: even the lens that used monolithic are as to the thing optical element; Also can suitable flare take place at the record of CD, DVD and/or playback time, can suitably carry out recording of information and/or playback to 3 kinds of different dishes of recording density of high density compact disc, DVD and CD etc.In addition, its purpose be to provide the optical take-up apparatus of the simplification that can realize its structure, cost degradation, to thing optical element and optical data recording/reproducing device.Moreover, its purpose be to provide for 3 kinds of different CDs whole improve the light utilization ratio and guarantee the optical take-up apparatus of sufficient light quantity, to thing optical element and optical data recording/reproducing device.

The optical take-up apparatus relevant with the present invention has: first light source that penetrates first light beam of first wavelength X 1; Penetrate the secondary light source of second light beam of second wavelength X 2 (λ 2＞λ 1); Penetrate the 3rd light source of the 3rd light beam of wavelength lambda 3 (λ 3＞λ 2); And to the thing optical element; Be used to make the information recording surface of above-mentioned first beam condenser in the 1st CD of protective substrate with thickness t 1; Make above-mentioned second beam condenser (on the information recording surface of the 2nd CD of the protective substrate of t1≤t2), make above-mentioned the 3rd beam condenser in having thickness t 3 (on the information recording surface of the 3rd CD of the protective substrate of t2＜t3) in having thickness t 2.

Above-mentioned optical take-up apparatus through make above-mentioned first beam condenser on the information recording surface of above-mentioned the 1st CD, make above-mentioned second beam condenser on the information recording surface of above-mentioned the 2nd CD, make above-mentioned the 3rd beam condenser on the information recording surface of above-mentioned the 3rd CD, carry out recording of information and/or playback.

Above-mentioned optical surface to the thing optical element has at least two zones of the neighboring area on every side of middle section and above-mentioned middle section, and above-mentioned middle section has first path difference and gives structure, and above-mentioned neighboring area has second path difference and gives structure.Above-mentioned to the thing optical element make above-mentioned first beam condenser through above-mentioned above-mentioned middle section to the thing optical element on the information recording surface of above-mentioned the 1st CD so that can carry out recording of information and/or playback; Make above-mentioned second beam condenser through above-mentioned above-mentioned middle section to the thing optical element on the information recording surface of above-mentioned the 2nd CD so that can carry out recording of information and/or playback, make above-mentioned the 3rd beam condenser through above-mentioned above-mentioned middle section to the thing optical element on the information recording surface of above-mentioned the 3rd CD so that can carry out recording of information and/or playback.In addition; Above-mentioned to the thing optical element make above-mentioned first beam condenser through above-mentioned above-mentioned neighboring area to the thing optical element on the information recording surface of above-mentioned the 1st CD so that can carry out recording of information and/or playback, make above-mentioned second beam condenser through above-mentioned neighboring area on the information recording surface of above-mentioned the 2nd CD so that can carry out recording of information and/or playback.

It is the structure that has first foundation structure at least that above-mentioned first path difference is given structure, above-mentioned first foundation structure be make other the diffraction light quantity of any number of times of 1 time diffraction light amount ratio of first light beam that has passed through first foundation structure big, other the diffraction light quantity of any number of times of 1 time diffraction light amount ratio of second light beam is big, other the big path difference of diffraction light quantity of any number of times of 1 time diffraction light amount ratio of the 3rd light beam is given structure.

It is the structure that has set foundation structure at least that above-mentioned second path difference is given structure, above-mentioned set foundation structure be make other the diffraction light quantity of any number of times of x time diffraction light amount ratio of first light beam that has passed through set foundation structure big, other the big path difference of diffraction light quantity of any number of times of y time diffraction light amount ratio of second light beam gives structure.

Description of drawings

Fig. 1 is the figure that sees relevant with the present invention example to thing optical element OL from optical axis direction.

Fig. 2 is shown schematically in the sectional view that the path difference in thing optical element OL be provided with relevant with the present invention given several examples (a)～(d) of structure.

Fig. 3 is the figure that has roughly represented the shape of the luminous point relevant with the present invention.

Fig. 4 is the figure that roughly representes the structure of the optical take-up apparatus relevant with the present invention.

Fig. 5 is the sectional view that schematically shows relevant with the present invention example to thing optical element OL.

Fig. 6 is the longitudinal spherical aberration figure (a)～(c) about the BD of the embodiment relevant with the present invention 1, DVD, CD.

Fig. 7 is the longitudinal spherical aberration figure (a)～(c) about the BD of the embodiment relevant with the present invention 2, DVD, CD.

Fig. 8 is the longitudinal spherical aberration figure (a)～(c) about the BD of the embodiment relevant with the present invention 3, DVD, CD.

Embodiment

Comparatively desirable form of the present invention below is described.

(item 1) a kind of optical take-up apparatus that carries out recording of information and/or playback for CD has: first light source that penetrates first light beam of first wavelength X 1; Penetrate the secondary light source of second light beam of second wavelength X 2 (λ 2＞λ 1); Penetrate the 3rd light source of the 3rd light beam of wavelength lambda 3 (λ 3＞λ 2); And to the thing optical element; Be used to make the information recording surface of above-mentioned first beam condenser in the 1st CD of protective substrate with thickness t 1; Make above-mentioned second beam condenser in having thickness t 2 (on the information recording surface of the 2nd CD of the protective substrate of t1≤t2); Make above-mentioned the 3rd beam condenser in having thickness t 3 (on the information recording surface of the 3rd CD of the protective substrate of t2＜t3)

Above-mentioned optical take-up apparatus through make above-mentioned first beam condenser on the information recording surface of above-mentioned the 1st CD, make above-mentioned second beam condenser on the information recording surface of above-mentioned the 2nd CD, make above-mentioned the 3rd beam condenser on the information recording surface of above-mentioned the 3rd CD, carry out recording of information and/or playback, it is characterized in that:

Above-mentioned optical surface to the thing optical element has at least two zones of the neighboring area on every side of middle section and above-mentioned middle section, and above-mentioned middle section has first path difference and gives structure, and above-mentioned neighboring area has second path difference and gives structure,

Above-mentioned to the thing optical element make above-mentioned first beam condenser by above-mentioned above-mentioned middle section to the thing optical element on the information recording surface of above-mentioned the 1st CD so that can carry out recording of information and/or playback; Make above-mentioned second beam condenser by above-mentioned above-mentioned middle section to the thing optical element on the information recording surface of above-mentioned the 2nd CD so that can carry out recording of information and/or playback; Make above-mentioned the 3rd beam condenser by above-mentioned above-mentioned middle section to the thing optical element on the information recording surface of above-mentioned the 3rd CD so that can carry out recording of information and/or playback

Above-mentioned to the thing optical element make above-mentioned first beam condenser through above-mentioned above-mentioned neighboring area to the thing optical element on the information recording surface of above-mentioned the 1st CD so that can carry out recording of information and/or playback; Make above-mentioned second beam condenser through above-mentioned above-mentioned neighboring area to the thing optical element on the information recording surface of above-mentioned the 2nd CD so that can carry out recording of information and/or playback

It is the structure that has first foundation structure at least that above-mentioned first path difference is given structure,

Above-mentioned first foundation structure be make other the diffraction light quantity of any number of times of 1 time diffraction light amount ratio of first light beam that has passed through first foundation structure big, other the diffraction light quantity of any number of times of 1 time diffraction light amount ratio of second light beam is big, other the big path difference of diffraction light quantity of any number of times of 1 time diffraction light amount ratio of the 3rd light beam is given structure.

It is the structure that has set foundation structure at least that above-mentioned second path difference is given structure,

Above-mentioned set foundation structure be make other the diffraction light quantity of any number of times of x time diffraction light amount ratio of first light beam that has passed through set foundation structure big, other the big path difference of diffraction light quantity of any number of times of y time diffraction light amount ratio of second light beam gives structure, satisfies following formula (8).

0.9·(x·λ1)/(n1-1)≤(y·λ2)/(n2-1)≤1.2·(x·λ1)/(n1-1)(8)

Wherein, x refers to the integer beyond 0,

Y refers to the integer beyond 0,

N1 refers to the refractive index under first light beam of thing optical element,

N2 refers to the refractive index under second light beam of thing optical element.

Optical take-up apparatus described in (item 2) item 1 is characterized in that:

Above-mentioned set foundation structure is the some of second foundation structure, the 4th foundation structure or the 5th foundation structure,

Above-mentioned second foundation structure be make other the diffraction light quantity of any number of times of 5 times diffraction light amount ratio of first light beam that has passed through above-mentioned second foundation structure big, other the diffraction light quantity of any number of times of 3 times diffraction light amount ratio of second light beam is big, other the big path difference of diffraction light quantity of any number of times of the diffraction light amount ratio of 3 times of the 3rd light beam and 2 times is given structure

Above-mentioned the 4th foundation structure be make other the diffraction light quantity of any number of times of 3 times diffraction light amount ratio of first light beam that has passed through above-mentioned the 4th foundation structure big, other the diffraction light quantity of any number of times of 2 times diffraction light amount ratio of second light beam is big, other the big path difference of diffraction light quantity of any number of times of the diffraction light amount ratio of 2 times of the 3rd light beam and 1 time is given structure

Above-mentioned the 5th foundation structure be make other the diffraction light quantity of any number of times of 10 times diffraction light amount ratio of first light beam that has passed through above-mentioned the 5th foundation structure big, other the diffraction light quantity of any number of times of 6 times diffraction light amount ratio of second light beam is big, other the big path difference of diffraction light quantity of any number of times of 5 times diffraction light amount ratio of the 3rd light beam is given structure.

Optical take-up apparatus described in (item 3) item 1 or the item 2 is characterized in that:

The above-mentioned set foundation structure that has been overlapping that above-mentioned second path difference is given structure and some structures of the 3rd foundation structure or the 4th foundation structure,

Above-mentioned the 3rd foundation structure be make other the diffraction light quantity of any number of times of 2 times diffraction light amount ratio of first light beam that has passed through above-mentioned the 3rd foundation structure big, other the diffraction light quantity of any number of times of 1 time diffraction light amount ratio of second light beam is big, other the big path difference of diffraction light quantity of any number of times of 1 time diffraction light amount ratio of the 3rd light beam is given structure

Above-mentioned the 4th foundation structure be make other the diffraction light quantity of any number of times of 3 times diffraction light amount ratio of first light beam that has passed through above-mentioned the 4th foundation structure big, other the diffraction light quantity of any number of times of 2 times diffraction light amount ratio of second light beam is big, other the big path difference of diffraction light quantity of any number of times of the diffraction light amount ratio of 2 times of the 3rd light beam and 1 time is given structure.

Optical take-up apparatus described in each of (item 4) item 1 to item 3 is characterized in that:

Above-mentioned is single element lens to the thing optical element.

Optical take-up apparatus described in each of (item 5) item 1 to item 4 is characterized in that:

Above-mentioned is plastic lens to the thing optical element.

Optical take-up apparatus described in each of (item 6) item 1 to item 4 is characterized in that:

Above-mentioned is glass lens to the thing optical element.

Optical take-up apparatus described in each of (item 7) item 1 to item 6 is characterized in that:

Above-mentioned optical surface to the thing optical element has around above-mentioned neighboring area and has the neighboring area that the 3rd path difference is given structure,

Make above-mentioned first beam condenser through above-mentioned above-mentioned neighboring area to the thing optical element on the information recording surface of above-mentioned the 1st CD so that can carry out recording of information and/or playback,

It is the some structures that have above-mentioned second foundation structure, above-mentioned the 3rd foundation structure, above-mentioned the 4th foundation structure or above-mentioned the 5th foundation structure at least that above-mentioned the 3rd path difference is given structure,

Optical take-up apparatus described in each of (item 8) item 1 to item 6 is characterized in that:

Above-mentioned optical surface to the thing optical element has the neighboring area as plane of refraction around above-mentioned neighboring area,

Make above-mentioned first beam condenser through above-mentioned above-mentioned neighboring area to the thing optical element on the information recording surface of above-mentioned the 1st CD so that can carry out recording of information and/or playback.

Optical take-up apparatus described in each of (item 9) item 1 to item 8 is characterized in that:

Be provided with that first path difference gives structure above-mentionedly be provided with the 4th path difference on to the different optical surface of the optical surface of thing optical element and give structure.

Optical take-up apparatus described in each of (item 10) item 1 to item 9 is characterized in that:

Conditional (9), (10) below above-mentioned first wavelength X 1, above-mentioned second wavelength X 2 and above-mentioned wavelength lambda 3 satisfy.

1.5×λ1＜λ2＜1.7×λ1 (9)

1.9×λ1＜λ3＜2.1×λ1 (10)

Optical take-up apparatus described in each of (item 11) item 1 to item 10 is characterized in that:

In for the common light path of above-mentioned first light beam, above-mentioned second light beam and above-mentioned the 3rd light beam and above-mentioned, the opening limiting element is set between to thing optical element and above-mentioned first light beam, above-mentioned second light beam and above-mentioned the 3rd light beam,

Above-mentioned opening limiting element has the first area of approaching optical axis at least and compares with above-mentioned first area from optical axis second area far away,

Above-mentioned first area sees through the whole of above-mentioned first light beam, above-mentioned second light beam and above-mentioned the 3rd light beam; Above-mentioned second area sees through above-mentioned first light beam and above-mentioned second light beam but does not make above-mentioned the 3rd beam condenser on above-mentioned first area that has seen through above-mentioned opening limiting element and above-mentioned above-mentioned the 3rd beams focusing position to the thing optical element

Above-mentioned the 3rd light beam that has passed through above-mentioned first area incides on the above-mentioned above-mentioned middle section to the thing optical element.

Optical take-up apparatus described in (item 12) item 11 is characterized in that:

Above-mentioned optical take-up apparatus has λ/4 wavelength sheets, and above-mentioned opening limiting element and above-mentioned λ/4 wavelength sheets are integrated.

Optical take-up apparatus described in (item 13) item 11 is characterized in that:

Formula below satisfying (1 ").

0.02≤L/f＜0.05 (1”)

(14) a kind of in optical take-up apparatus, use to the thing optical element, above-mentioned optical take-up apparatus has: first light source that penetrates first light beam of first wavelength X 1; Penetrate the secondary light source of second light beam of second wavelength X 2 (λ 2＞λ 1); And the 3rd light source that penetrates the 3rd light beam of wavelength lambda 3 (λ 3＞λ 2); Above-mentioned optical take-up apparatus uses above-mentioned first light beam to have the recording of information and/or the playback of the 1st CD of the protective substrate of thickness t 1; Use above-mentioned second light beam to have thickness t 2 (recording of information and/or the playback of the 2nd CD of the protective substrate of t1≤t2); Use above-mentioned the 3rd light beam to have thickness t 3 (recording of information and/or the playback of the 3rd CD of the protective substrate of t2＜t3)

Above-mentionedly make above-mentioned first beam condenser on the information recording surface of above-mentioned the 1st CD to the thing optical element; Make above-mentioned second beam condenser on the information recording surface of above-mentioned the 2nd CD; Make above-mentioned the 3rd beam condenser on the information recording surface of above-mentioned the 3rd CD, it is characterized in that:

0.9·(x·λ1)/(n1-1)≤(y·λ2)/(n2-1)≤1.2·(x·λ1)/(n1-1)(8)

Wherein, x refers to the integer beyond 0,

Y refers to the integer beyond 0,

Described in (15) 14 to the thing optical element, it is characterized in that:

Described in (16) 14 or 15 to the thing optical element, it is characterized in that:

(17) 14 to described in each of item 16 to the thing optical element, it is characterized in that:

Above-mentioned is single element lens to the thing optical element.

(18) 14 to described in each of item 17 to the thing optical element, it is characterized in that:

Above-mentioned is plastic lens to the thing optical element.

(19) 14 to described in each of item 17 to the thing optical element, it is characterized in that:

Above-mentioned is glass lens to the thing optical element.

(20) 14 to described in each of item 19 to the thing optical element, it is characterized in that:

(21) 14 to described in each of item 19 to the thing optical element, it is characterized in that:

(22) 14 to described in each of item 21 to the thing optical element, it is characterized in that:

(23) 14 to described in each of item 22 to the thing optical element, it is characterized in that:

1.5×λ1＜λ2＜1.7×λ1 (9)

1.9×λ1＜λ3＜2.1×λ1 (10)

(item 24) a kind of optical data recording/reproducing device with optical take-up apparatus, above-mentioned optical take-up apparatus has: first light source that penetrates first light beam of first wavelength X 1; Penetrate the secondary light source of second light beam of second wavelength X 2 (λ 2＞λ 1); Penetrate the 3rd light source of the 3rd light beam of wavelength lambda 3 (λ 3＞λ 2); And to the thing optical element; Be used to make the information recording surface of above-mentioned first beam condenser in the 1st CD of protective substrate with thickness t 1; Make above-mentioned second beam condenser in having thickness t 2 (on the information recording surface of the 2nd CD of the protective substrate of t1≤t2); Make above-mentioned the 3rd beam condenser in having thickness t 3 (on the information recording surface of the 3rd CD of the protective substrate of t2＜t3); Above-mentioned optical take-up apparatus through make above-mentioned first beam condenser on the information recording surface of above-mentioned the 1st CD, make above-mentioned second beam condenser on the information recording surface of above-mentioned the 2nd CD, make above-mentioned the 3rd beam condenser on the information recording surface of above-mentioned the 3rd CD, carry out recording of information and/or playback, it is characterized in that:

0.9·(x·λ1)/(n1-1)≤(y·λ2)/(n2-1)≤1.2·(x·λ1)/(n1-1)(8)

Wherein, x refers to the integer beyond 0,

Y refers to the integer beyond 0,

Comparatively desirable form of the present invention below at length is described.

The optical take-up apparatus relevant with the present invention has at least 3 light sources of first light source, secondary light source, the 3rd light source.Moreover, optical take-up apparatus of the present invention have be used to make first beam condenser in the information recording surface of the 1st CD, second beam condenser in information recording surface, the Focused Optical system of the 3rd beam condenser on the information recording surface of the 3rd CD of the 2nd CD.In addition, optical take-up apparatus of the present invention has the photo detector of acceptance from the folded light beam of the information recording surface of the 1st CD, the 2nd CD or the 3rd CD.

The 1st CD has the protective substrate and the information recording surface of thickness t 1.The 2nd CD has thickness t 2 (protective substrate and the information recording surface of t1≤t2).The 3rd CD has thickness t 3 (protective substrate and the information recording surface of t2＜t3).Comparatively it is desirable to, the 1st CD is a high density compact disc, and the 2nd CD is DVD, and the 3rd CD is CD, but is not limited thereto.In addition; The situation of t1＜t2 is compared with the situation of t1=t2; While utilize monolithic the thing optical element is carried out the record and/or the playback of 3 different CDs, tracking characteristics when making the record reproducing of the 3rd CD good this point that becomes is the comparison difficulty, but form of the present invention can realize this point.Have, the 1st CD, the 2nd CD and the 3rd CD can be the CDs with multilayer of a plurality of information recording surfaces again.

In this manual, as the example of high density compact disc, can enumerate the CD that the thickness that the thing optical element is carried out recording of information/playback, protective substrate that utilizes NA0.85 is about the specification of 0.1mm (BD for example: Blu-ray disc).In addition, as other the example of high density compact disc, can enumerate and utilize that NA0.65's to 0.67 carry out the CD (for example HD DVD: also only be called HD) that recording of information/playback, protective substrate thickness are about the specification of 0.6mm to the thing optical element.In addition, the thickness that in high density compact disc, is also contained in CD, the protective substrate of the diaphragm (in this manual, supposing that protective substrate also comprises diaphragm) of the thickness that has several approximately～tens nm on the information recording surface is 0 CD.In addition, in high density compact disc,, suppose also to comprise the photomagneto disk that uses blue violet semiconductor laser, bluish violet SHG laser instrument as the light source of recording of information and/or playback.Moreover; In this manual; So-called DVD; Be to utilize the thickness that the thing optical element is carried out recording of information/playback, protective substrate of NA0.60 to 0.67 to be about the general name of the DVD series CD of 0.6mm, comprise DVD-ROM, DVD-Video, DVD-Audio, DVD-RAM, DVD-R, DVD-RW, DVD+R, DVD+RW etc.In addition; In this manual; So-called CD is to utilize the thickness that the thing optical element is carried out recording of information/playbacks, protective substrate about NA0.45～0.53 to be about the general name of the serial CD of CD of 1.2mm, comprises CD-ROM, CD-Audio, CD-Video, CD-R, CD-RW etc.In addition, about recording density, the recording density of high density compact disc is the highest, and the order of secondly pressing DVD, CD reduces.

Have again, about thickness t 1, t2, the t3 of protective substrate, conditional (11), (12), (13) below preferably satisfying, but be not limited thereto.

0.0750mm≤t1≤0.125mm or 0.5mm≤t1≤0.7mm (11)

0.5mm≤t2≤0.7mm (12)

1.0mm≤t3≤1.3mm (13)

In this manual, first light source, secondary light source, the 3rd light source laser light source preferably.As laser light source, preferably use semiconductor laser, silicon laser instrument etc.Conditional (9), (10) below the wavelength lambda 2 (λ 3＞λ 2) of second wavelength X 2 (λ 2＞λ 1) of first wavelength X 1 of first light beam that penetrates from first light source, second light beam that penetrates from secondary light source, the 3rd light beam that penetrates from the 3rd light source preferably satisfies.

1.5×λ1＜λ2＜1.7×λ1 (9)

1.9×λ1＜λ3＜2.1×λ1 (10)

In addition; Under the situation of using BD or HD, DVD and CD as the 1st CD, the 2nd CD and the 3rd CD respectively; First wavelength X 1 of first light source comparatively it is desirable to more than or equal to 350nm and smaller or equal to 440nm, even more ideal be more than or equal to 380nm and smaller or equal to 415nm; Second wavelength X 2 of secondary light source comparatively it is desirable to more than or equal to 570nm and smaller or equal to 680nm, even more ideal be more than or equal to 630nm and smaller or equal to 670nm, the wavelength lambda 3 of the 3rd light source comparatively it is desirable to more than or equal to 750nm and smaller or equal to 880nm, even more ideal be more than or equal to 760nm and smaller or equal to 820nm.

In addition, can carry out blocking at least 2 light sources in first light source, secondary light source, the 3rd light source.So-called blocking for example refers to first light source and secondary light source fixedly is contained in 1 packaging body, but is not limited thereto, and loosely comprises the state of having fixed 2 light sources with the mode that can not carry out aberration correction.In addition, except light source, can with after the photo detector stated be contained in 1 packaging body.

As photo detector, preferably use the photodetector of optical diode etc.The light that on the information recording surface on the CD, has reflected incides on the photo detector, use its output signal, the information that can obtain on each CD, writing down read signal.Moreover, detecting the change in shape because of the luminous point on the photo detector, the light quantity variation that change in location produces, the detection of focusing, session detect.According to this detection, can make the thing optical element is moved so that can focus, follow the tracks of.Photo detector can be made up of a plurality of photodetectors.Photo detector can have key light detecting device and sub-photodetector.For example, can make on the two sides of the photodetector of accepting to be used for the key light that recording of information resets and 2 sub-photodetectors are set, utilize these 2 sub-photodetectors to accept to follow the tracks of the such photo detector of sub-light of adjustment usefulness.In addition, about photo detector, can have a plurality of photo detectors corresponding with each light source.

Focused Optical system has the thing optical element.Focused Optical system can only have the thing optical element, but Focused Optical system is except to also having the relay lens of collimation lens etc. the thing optical element.So-called relay lens refers to single lens or lens combination that dispose, that change the angle of divergence of light beam between to thing optical element and light source.Collimation lens is a kind of of relay lens, is to make the light that incides in the collimation lens become the lens that directional light penetrates.Moreover Focused Optical system can have the optical element that the light beam that has penetrated from light source is divided into the diffraction optical element that is used for main beam that recording of information resets and two sub-beams that are used to follow the tracks of etc. etc.In this manual, so-called to the thing optical element, refer in optical take-up apparatus with the CD opposed position on dispose, have a optical system with the function of beam condenser on the information recording surface of CD that has penetrated from light source.Comparatively it is desirable to; So-called to the thing optical element, refer in optical take-up apparatus with the CD opposed position on dispose, have the optical system of the function of beam condenser on the information recording surface of CD that has penetrated from light source and then the driver capable of using optical system of displacement integratedly on optical axis direction at least.The thing optical element can be made up of a plurality of lens and the optical element more than or equal to two, also can constitute by a object lens, comparatively it is desirable to the object lens of monolithic by monolithic.In addition, can be glass lens, also can be plastic lens the thing optical element, in addition, also can be on glass lens, to be provided with the hybrid lens that path difference is given structure with ray hardening resin etc.The thing optical element is had under the situation of a plurality of lens, can use glass lens and plastic lens with mixing.The thing optical element being had under the situation of a plurality of lens, can be to have the combination that path difference is given planar optics system and the non-spherical lens of structure (can have path difference give structure also can not have path difference to give structure).In addition, to the plane of refraction of thing optical element aspheric surface preferably.In addition, the thing optical element is provided with preferably aspheric surface of basal plane that path difference gives structure.

In addition, will make the thing optical element under the situation of glass lens, and preferably use glass branchpoint Tg smaller or equal to 400 ℃ glass material.Through the glass material of use glass branchpoint Tg smaller or equal to 400 ℃, owing to can carry out the lower shaping of temperature, so can prolong the life-span of metal pattern.As so low glass material of glass branchpoint Tg, for example there be (strain) to live in K-PG325, the K-PG375 (all being the goods name) of field optical glass system.

But, because the proportion of glass lens is generally great than the ratio of resin lens, so if will make glass lens to the thing optical element, then weight becomes big, to driving concerning the driver of thing optical element burden.Therefore, making the thing optical element under the situation of glass lens, preferably use the little glass material of proportion.Specifically, proportion is comparatively desirable smaller or equal to 3.0, and proportion is even more ideal smaller or equal to 2.8.

In addition; To make the thing optical element under the situation of plastic lens; Preferably use the resin material of cyclic olefin series; Even in cyclic olefin series, use for the refractive index under 25 ℃ of the temperature of wavelength 405nm be in 1.54 to 1.60 the scope, follow-5 ℃ of temperature variation to 70 ℃ the temperature range the variations in refractive index rate dN/dT for wavelength 405nm (℃ ^-1) be-20 * 10 ^-5To-5 * 10 ^-5(even more ideal is-10 * 10 ^-5To-8 * 10 ^-5) scope in resin material even more ideal.In addition, making the thing optical element under the situation of plastic lens, preferably relay lens is also made plastic lens.

Perhaps, " アサ-マ Le resin " as being suitable for the resin material to the thing optical element of the present invention, except above-mentioned cyclic olefin series, arranged.So-called " アサ-マ Le resin " is in becoming the resin of fertile material, to have disperseed the resin material of diameter smaller or equal to the particle of 30nm.At this, above-mentioned particle has the variations in refractive index rate of variations in refractive index rate opposite in sign with the temperature variation of following the resin that becomes fertile material.In general, if admixed finepowder is last in transparent resin material, then owing to produce scattering of light; Transmissivity descends; So be difficult to use, but become the size littler, known scattering do not take place in fact than the wavelength of transmitted light beam through the size that makes micropowder as optical material.

The refractive index Yin Wendu of resin material rises and descends, if but temperature rises the then refractive index of inorganic particulate rising.Therefore, work the also known variations in refractive index that do not produce through the mode that these character are lumped together to cancel each other.As the material to the thing optical element of the present invention; Through be utilized in the resin that becomes fertile material disperse 30 nanometers, comparatively it is desirable to smaller or equal to 20 nanometers, even more ideal be the material of the inorganic particulate of 10～15 nanometers, can provide the temperature dependency of the temperature dependency that do not have refractive index or refractive index extremely low to the thing optical element.

For example, in acryl resin, disperseed niobium oxide (Nb ₂O ₅) particulate.The resin that becomes fertile material is about 20 ratio by volume for about 80, niobium oxide, and it is mixed equably.Though there is the problem of the easy aggegation of particulate, utilize to give electric charge to particle surface and make its technology of disperseing etc., can produce necessary disperse state.

As after state, the mixing of the resin that becomes fertile material with online mode when being preferably in the injection molding to the thing optical element and particle, dispersion.In other words, mixing, disperseing back before be configured as, preferably do not cooling off, solidify the thing optical element.

Have again,, can suitably increase and decrease this volume ratio, also can mix the inorganic particulate of multiple nano-scale and make its dispersion in order to control the ratio for variation of temperature of refractive index.

In ratio, in above-mentioned example, be 80: 20, promptly 4: 1, but can suitably adjustment between 90: 10 (9: 1) to 60: 40 (3: 2).If lacked than 9: 1, the effect that then suppresses temperature variation is little, on the contrary, if surpass 3: 2, then owing to having problems aspect the formability of resin, so be unfavorable.

Particulate is inorganics preferably, and then oxide preferably.And, preferably the state of oxidation saturated, at this non-oxidizing oxide more than degree.

In order to suppress lowlyer with the reaction that becomes as the resin of the fertile material of macromolecular organic compound, be that the inorganics this point is comparatively desirable, in addition,, can prevent to follow the mis-behave of use through being oxide.Particularly under the such harsh condition of high temperatureization, irradiating laser, accelerating oxidation easily, but so long as the particulate of such inorganic oxide just can prevent the mis-behave that causes because of oxidation.

In addition, for the oxidation of the resin that prevents to cause, also can add antioxidant certainly because of other main cause.

By the way, as the resin that becomes fertile material, the spy that can use suitably, comparatively ideally at Japanese publication communique open 2004-144951 number, the spy opens 2004-144954 number and special open 2004-144953 number etc. in the resin of that kind put down in writing.

Do not do special qualification as the inorganic fine particles of in thermoplastic resin, disperseing, and the change of refractive rate that can cause from the Yin Wendu of resulting thermoplastic resin constituent (be decided to be later on | dn/dT|) at random select little such inorganic fine particles that can reach the object of the invention.Specifically; It is comparatively desirable using oxide microparticle, slaine particulate, semiconductor microactuator particle etc., and it is comparatively desirable from these particulates, suitably being chosen in the particulate that does not produce absorption, luminous, fluorescence etc. in the wavelength region may of using as optical element.

As the oxide microparticle that uses in the present invention; Can use the metal that constitutes metal oxide is a kind of from be made up of Li, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Rb, Sr, Y, Nb, Zr, Mo, Ag, Cd, In, Sn, Sb, Cs, Ba, La, Ta, Hf, W, Ir, Tl, Pb, Bi and rare earth metal a group, selecting or more than or equal to the metal oxide of 2 kinds metal; Specifically, for example can enumerate monox, titanium dioxide, zinc paste, aluminium oxide, zirconia, hafnia, niobium oxide, tantalum oxide, magnesium oxide, calcium oxide, strontium oxide strontia, baryta, indium oxide, tin oxide, massicot, as lithium niobate, potassium niobate, lithium tantalate, the magnalium oxide (MgAl of the double oxide that constitutes by these oxides ₂O ₄) etc.In addition; As the oxide microparticle that uses in the present invention; Also can use rare-earth oxide; Specifically, also can enumerate scandium oxide, yttria, lanthana, cerium oxide, praseodymium oxide, neodymia, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosia, holimium oxide, oxidation bait, thulium oxide, ytterbium oxide, luteium oxide etc.As the slaine particulate, can enumerate carbonate, phosphate, sulfate etc., specifically, can enumerate lime carbonate, aluminum phosphate etc.

In addition; Semiconductor microactuator particle among so-called the present invention; Mean the particulate that semiconducting crystal is formed; As the concrete composition example that this semiconducting crystal is formed, can enumerate the compound, tin oxide (the IV) (SnO that constitute by a plurality of periodic table the 14th family's elements of the simple substance, silit (SiC) etc. of periodic table the 16th family's elements such as simple substance, selenium, tellurium of simple substance, phosphorus periodic tables such as (black phosphorus) the 15th family's element of periodic table the 14th family's element of carbon, silicon, germanium, tin etc. ₂), artificial gold (II, IV) (Sn (II) Sn (IV) S ₃), artificial gold (IV) (SnS ₂); Artificial gold (II) (SnS); Stannic selenide (II) (SnSe); Tellurium tin (II) (SnTe); Vulcanized lead (II) (PbS); Lead selenide (II) (PbSe); Periodic table the 14th family's element that lead telluride (II) (PbTe) waits and the compound of periodic table the 16th family's element; Boron nitride (BN); Boron phosphide (BP); Arsenic boron (BAs); Aluminium nitride (AlN); Aluminum phosphate (AlP); Aluminium arsenide (AlAs); Aluminium antimonide (AlSb); Gallium nitride (GaN); Gallium phosphide (GaP); Gallium arsenide (GaAs); Gallium antimonide (GaSb); Indium nitride (InN); Indium phosphide (InP); Indium arsenide (InAs); The belonging to group 13 of periodic table element of indium antimonide (InSb) etc. and the compound (or III-V compound semiconductor) of periodic table the 15th family's element; Aluminium sulfide (Al ₂S ₃), aluminum selenide (Al ₂Se ₃), sulfuration gallium (Ga ₂S ₃), gallium selenide (Ga ₂Se ₃), tellurium gallium (Ga ₂Te ₃), indium oxide (In ₂O ₃), indium sulfide (In ₂S ₃), indium selenide (In ₂Se ₃), tellurium indium (In ₂Te ₃) the belonging to group 13 of periodic table element that waits and the compound of periodic table the 16th family's element; Thallium chloride (I) (TlCl); Thallium bromide (I) (TlBr); The belonging to group 13 of periodic table element that thallium iodide (I) (TlI) waits and the compound of periodic table the 17th family's element; Zinc paste (ZnO); Zinc sulphide (ZnS); Zinc selenide (ZnSe); Zinc telluridse (ZnTe); Cadmium oxide (CdO); Cadmium sulfide (CdS); Cadmium selenide (CdSe); Cadmium telluride (CdTe); Mercuric sulphide (HgS); Mercury selenide (HgSe); Periodic table the 12nd family's element of tellurium mercury (HgTe) etc. and the compound (or II-VI compound semiconductor) of periodic table the 16th family's element; Arsenones (III) (As ₂S ₃), arsenic selenide (III) (As ₂Se ₃), arsenic telluride (III) (As ₂Te ₃), antimony trisulfide (III) (Sb ₂S ₃), antimony selenide (III) (Sb ₂Se ₃), antimony telluride (III) (Sb ₂Te ₃), bismuth sulfide (III) (Bi ₂S ₃), bismuth selenide (III) (Bi ₂Se ₃), bismuth telluride (III) (Bi ₂Te ₃) periodic table the 15th family's element that waits and the compound of periodic table the 16th family's element, cupric oxide (I) (Cu ₂O), copper selenide (I) (Cu ₂Se) etc. periodic table the 11st family's element and the compound of periodic table the 16th family's element; Cupric chloride (I) (CuCl); Copper bromide (I) (CuBr); Cupric iodide (I) (CuI); Silver chloride (AgCl); Periodic table the 11st family's element of silver bromide (AgBr) etc. and the compound of periodic table the 17th family's element; Periodic table the 10th family's element that nickel oxide (II) (NiO) waits and the compound of periodic table the 16th family's element; Cobalt oxide (II) (CoO); Periodic table the 9th family's element that cobalt sulfide (II) (CoS) waits and the compound of periodic table the 16th family's element; Tri-iron tetroxide (Fe ₃O ₄), the compound of iron sulfide (II) periodic table the 8th family's element and periodic table the 16th family's element (FeS) etc., manganese oxide (II) periodic table the 7th family's element and compound, molybdenum sulfide (the IV) (MoS of periodic table the 16th family's element (MnO) etc. ₂), tungsten oxide (IV) (WO ₂) periodic table the 6th family's element that waits and the compound of periodic table the 16th family's element, vanadium oxide (II) (VO), vanadium oxide (IV) (VO ₂), tantalum oxide (V) (Ta ₂O ₅) periodic table the 5th family's element of waiting and compound, the titanium dioxide (TiO of periodic table the 16th family's element ₂, Ti ₂O ₅, Ti ₂O ₃, Ti ₅O ₉) periodic table the 2nd family's element of periodic table the 4th family's element that waits and the compound of periodic table the 16th family's element, magnesium sulfide (MgS), magnesium selenide (MgSe) etc. and compound, cadmium oxide (II) chromium (the III) (CdCr of periodic table the 16th family's element ₂O ₄), cadmium selenide (II) chromium (III) (CdCr ₂Se ₄), copper sulfide (II) chromium (III) (CuCr ₂S ₄), mercury selenide (II) chromium (III) (HgCr ₂Se ₄) the sulfur family spinels, the barium titanate (BaTiO that wait ₃) etc.Have again, similarly illustration such as G.Schmid etc.; At Adv.Mater., 4 volumes, (BN) that has reported in 494 pages (1991) ₇₅(BF ₂) ₁₅F ₁₅Or like D.Fenske etc.; At Angew.Chem.Int.Ed.Engl., 29 volumes, the Cu that has reported in 1452 pages (1990) ₁₄₆Se ₇₃(triethyl phosphine) ₂₂The semiconductor atom group that such structure has been determined.

In general, the dn/dT of thermoplastic resin has negative value, promptly follows the rising refractive index of temperature to reduce.Thereby, in order to reduce the thermoplastic resin constituent effectively | dn/dT| preferably makes the big particulate of dn/dT be dispersed in the above-mentioned thermoplastic resin constituent.Using under the atomic situation of dn/dT that has with thermoplastic resin as the value of prosign, the absolute value of atomic dn/dT preferably liken to into the dn/dT of the thermoplastic resin of fertile material little.Moreover, preferably use have with as the particulate of the dn/dT of the dn/dT opposite in sign of the thermoplastic resin of fertile material, promptly have the particulate of the dn/dT of positive value.Through such particulate is dispersed in the thermoplastic resin, available few amount reduces the thermoplastic resin constituent effectively | dn/dT|.Can suitably select dispersed atomic dn/dT according to value as the dn/dT of the thermoplastic resin of fertile material; But particulate is dispersed under the situation in the thermoplastic resin that in general optical element is used comparatively ideally, and atomic dn/dT is than-20 * 10 ^-6Be greatly comparatively desirable, than-10 * 10 ^-6Greatly then even more ideal.As the big particulate of dn/dT, preferably for example use potassium nitride, zinc sulphide, zinc paste, lithium niobate, lithium tantalate etc.

On the other hand, particulate is dispersed under the situation in the thermoplastic resin, is hoping as the difference of the thermoplastic resin of fertile material and atomic refractive index little.Result according to inventors' research can know, if the difference of thermoplastic resin and dispersed atomic refractive index is little, then is difficult to cause scattering under the situation of light transmission making.Also found when making particulate be dispersed in the thermoplastic resin; Particle is big more, causes the scattering when having made light transmission more easily, if but the difference of thermoplastic resin and dispersed atomic refractive index is little; Even then use bigger particulate, the degree that scattering of light takes place is also less.The difference of thermoplastic resin and dispersed atomic refractive index is that 0～0.3 scope is comparatively desirable, and then is that 0～0.15 scope is then even more ideal.

The refractive index of the thermoplastic resin that is used comparatively ideally as optical element is about 1.4～1.6 mostly; As the material that in these thermoplastic resins, makes it to disperse, for example use monox, lime carbonate, aluminum phosphate, aluminium oxide, magnesium oxide, magnalium oxide etc. comparatively ideally.

In addition, can know, can reduce the dn/dT of thermoplastic resin constituent effectively through the lower particulate of refractive index ratio is disperseed.About having disperseed refractive index low atomic thermoplastic resin constituent | the reason that dn/dT| reduces; Though also do not understand its details; But can think that atomic refractive index is low more, the temperature variation of the volume fraction of the inorganic fine particles in the resin combination is not more reducing resin combination | work on the direction of dn/dT|.As the lower particulate of refractive index ratio, for example use monox, lime carbonate, aluminum phosphate comparatively ideally.

It is difficult that the minimizing effect, photopermeability, desirable refractive index etc. of the dn/dT of thermoplastic resin constituent are all improved simultaneously; According to the characteristic that thermoplastic resin is required; Consider the size of the dn/dT of particulate self, atomic dn/dT with as the difference of the dn/dT of the thermoplastic resin of fertile material and atomic refractive index etc., can suitably select to be dispersed in the particulate in the thermoplastic resin.Moreover, suitably select with as the phasic property of the thermoplastic resin of fertile material, promptly for the dispersed of thermoplastic resin and to use the particulate this point that is difficult to cause scattering be comparatively desirable keeping aspect the photopermeability.

For example, at the cyclic olefin polymer that will be comparatively ideally be used for optical element as under the situation of fertile material, as not only keeping photopermeability, but also reducing | the particulate of dn/dT|, can use monox comparatively ideally.

About above-mentioned particulate, can use a kind of inorganic fine particles, maybe can merge and use multiple inorganic fine particles.Have the inorganic fine particles of different character through use, also can improve the characteristic that necessitates more efficiently.

In addition, the atomic mean particle diameter relevant with the present invention is comparatively desirable more than or equal to 1nm and smaller or equal to 30nm, more than or equal to 1nm and then even more ideal smaller or equal to 20nm, more than or equal to 1nm and particularly desirable smaller or equal to 10nm.Under the situation of mean particle diameter less than 1nm, the difficulty because the dispersion of inorganic fine particles becomes, existence can not obtain the danger of desirable performance; So mean particle diameter is comparatively desirable more than or equal to 1nm, in addition, if mean particle diameter surpasses 30nm; Then because the resulting thermoplastic resin constituent muddiness etc. that becomes; The transparency descends, and exists light transmittance less than 70% danger, so mean particle diameter is comparatively desirable smaller or equal to 30nm.The volume averaging value of the diameter (ball conversion particle diameter) when said here mean particle diameter refers to each particle is scaled the ball of identical volume.

Moreover the shape of inorganic fine particles is not done special qualification, but can use spherical particulate suitably.Specifically; The minimum diameter of particle (draw and the situation of 2 wiring that atomic periphery is joined under this wiring between minimum value and value)/maximum gauge (drawing and the situation of 2 wiring that atomic periphery is joined under this wiring between the maximal value of distance) be 0.5～1.0th, comparatively desirable, be 0.7～1.0 even more ideal.

In addition, even also do not do special restriction about the distribution of particle diameter, but in order to present effect more efficiently, the particle diameter that has wide distribution with use is compared, and can use the particle diameter with narrow distribution suitably.

Below record is about to the thing optical element.The neighboring area on every side that at least one optical surface of thing optical element is had middle section, middle section.Even more ideal is, at least one optical surface of thing optical element is had neighboring area around the neighboring area.Through neighboring area is set, can more suitably carry out record and/or playback for the CD of high NA.Middle section preferably comprises the zone to the optical axis of thing optical element, but also can be the zone that does not comprise the optical axis of thing optical element.Be preferably in and be provided with middle section, neighboring area and neighboring area on the same optical surface.As shown in fig. 1, on same optical surface, middle section CN, neighboring area MD, neighboring area OT being arranged to the optical axis is that the concentric circles at center is comparatively desirable.In addition, in middle section, be provided with first path difference and give structure, in the neighboring area, be provided with second path difference and give structure the thing optical element.Under the situation with neighboring area, neighboring area can be a plane of refraction, also can in neighboring area, be provided with the 3rd path difference and give structure.Middle section, neighboring area and neighboring area be respectively in abutting connection with being comparatively desirable, but also can be gapped a little betwixt.

To the area of the middle section of thing optical element more than or equal to 70% zone in be provided with first path difference to give structure be comparatively desirable, even more ideal more than or equal to 90%.Even more ideal is on whole of middle section, to be provided with first path difference and to give structure.To the area of the neighboring area of thing optical element more than or equal to 70% zone in be provided with second path difference to give structure be comparatively desirable, even more ideal more than or equal to 90%.Even more ideal is on whole of neighboring area, to be provided with second path difference and to give structure.To the area of the neighboring area of thing optical element more than or equal to 70% zone in be provided with the 3rd path difference to give structure be comparatively desirable, even more ideal more than or equal to 90%.Even more ideal is on whole of neighboring area, to be provided with the 3rd path difference and to give structure.

Have, said in this manual path difference is given structure again, is the general name for the structure of the additional path difference of incident beam.Give in path difference and also to comprise the phase differential of giving phase differential in the structure and give structure.In addition, give at phase differential and comprise diffraction structure in the structure.Path difference is given structure and is had jump, comparatively it is desirable to have a plurality of jumps.Utilize this jump to additional path difference of incident beam and/or phase differential.Utilizing path difference to give the additional path difference of structure can be the integral multiple of the wavelength of incident beam, also can be wavelength non-integral multiple of incident beam.The interval of available period disposes jump on the optical axis vertical direction, also available aperiodic interval disposes jump on the optical axis vertical direction.

Path difference is given a plurality of endless belt that structure preferably has with the optical axis concentric circles that is the center.In addition, path difference is given structure and can be taked various section shapes (section shape in comprising the face of optical axis).Giving the section shape of structure as the most general path difference, is that the section shape that comprises optical axis that the path difference of that kind of record among Fig. 2 (a) is given structure is jagged situation.Give under the situation of structure section and look like stair-steppingly being provided with path difference on the optical element on plane, give the jagged section shape that is under the situation of structure as Fig. 2 (a) but on non-spherical lens face etc., be provided with same path difference.Thereby supposition also comprises stair-stepping section shape in the said in this manual jagged section shape.First path difference of this instructions is given structure and second path difference and is given the structure that structure can make the different jagged path difference of its section shape overlapping and give structure, for example Fig. 2 (b) be overlapping carefully jagged structure and structure of thick jagged structure.

Can be provided with on different optical surface that first path difference that in the middle section to the thing optical element, is provided with is given structure and second path difference that in the neighboring area to the thing optical element, is provided with is given structure, be provided with but be preferably on the same optical surface to the thing optical element.Through on same optical surface, being provided with, owing to can reduce the core shift error when making, so be comparatively desirable.In addition, compare, first path difference is set on the face to light source one side of thing optical element gives structure and second path difference to give structure be comparatively desirable with face to CD one side of thing optical element.In addition, have the 3rd path difference and give under the situation of neighboring area of structure in that the thing optical element is had, preferably also to give structure be on the same optical surface the 3rd path difference to be set to give structure giving structure and second path difference with first path difference.

Have again, give under the situation of structure in that the thing optical element is had the 4th path difference, be preferably in and be provided with first path difference and give on the different optical surface of optical surface that structure and second path difference give structure and being provided with.In addition, be preferably in and on the face to CD one side of thing optical element the 4th path difference be set and give structure.

To the thing optical element make respectively through be provided with give the middle section of structure to first path difference of thing optical element first light beam, second light beam and the 3rd beam condenser for forming the optically focused luminous point.Comparatively it is desirable to, to the thing optical element make through be provided with give structure to first path difference of thing optical element first beam condenser of middle section on the information recording surface of the 1st CD so that can carry out recording of information and/or playback.In addition, to the thing optical element make through be provided with give structure to first path difference of thing optical element second beam condenser of middle section on the information recording surface of the 2nd CD so that can carry out recording of information and/or playback.Moreover, to the thing optical element make through be provided with give structure to first path difference of thing optical element the 3rd beam condenser of middle section on the information recording surface of the 3rd CD so that can carry out recording of information and/or playback.In addition; Under thickness t 2 condition of different of the protective substrate of the thickness t 1 of the protective substrate of the 1st CD and the 2nd CD, first path difference gives that structure is proofreaied and correct spherical aberration that the difference because of the thickness t 2 of the protective substrate of the thickness t 1 of the protective substrate of the 1st CD and the 2nd CD takes place for first light beam of giving structure through first path difference and second light beam and/or the spherical aberration that takes place because of the difference of wavelength of first light beam and second light beam is comparatively desirable.Moreover first path difference is given structure and is given for having passed through first path difference that first light beam and the 3rd light beam of structure are proofreaied and correct spherical aberration that the difference because of the thickness t 3 of the protective substrate of the thickness t 1 of the protective substrate of the 1st CD and the 3rd CD takes place and/or the spherical aberration that takes place because of the difference of wavelength of first light beam and the 3rd light beam is comparatively desirable.

In addition, the spot diameter that utilizes the luminous point that the spot diameter passed through the 3rd light beam that first path difference of thing optical element is given structure is formed the luminous point that the 3rd light beam forms forms for first best focal point and the 3rd light beam of minimum is for than first best focal point, second little best focal point secondly.Have again,, suppose that referring to width of light beam becomes minimum point in the scope that certain defocuses at this said best focal point.That is, what is called utilizes the 3rd light beam to form first best focal point and second best focal point is that the scope inner light beam width that in the 3rd light beam, defocuses at certain is that minimum point exists 2 points at least.Have again, give in the 3rd light beam of structure light quantity for maximum diffraction light forms first best focal point, light quantity is comparatively desirable for next big diffraction light forms second best focal point having passed through first path difference.In addition;, its difference bigger than the diffraction efficiency of the diffraction light that forms second best focal point in the diffraction efficiency of the diffraction light that forms first best focal point is under the situation more than or equal to 15% (more preferably greater than equaling 30%), and the such effect of the present invention of light utilization ratio that can improve in the 3rd light beam becomes more remarkable.

In addition; Record and/or playback that the luminous point that the luminous point that the 3rd light beam forms in first best focal point is used for record and/or the playback of the 3rd CD, form at second best focal point the 3rd light beam is not used in the 3rd CD are comparatively desirable, but do not negate that the record and/or the playback that are not used in the 3rd CD of the 3rd light beam forms in first best focal point luminous point, the luminous point that the 3rd light beam forms in second best focal point are used for the record of the 3rd CD and/or such form of resetting.Have again; On face, first path difference is set and gives under the situation of structure light source one side of thing optical element, can consider second best focal point compare with first best focal point approach to the situation of thing optical element and to thing optical element situation far away the two.For example, form under the situation of second best focal point at 0 diffraction light of the 3rd light beam, the position of second best focal point is compared with first best focal point that 1 diffraction light that utilizes the 3rd light beam forms and is approached the thing optical element.On the other hand, form under the situation of second best focal point at 2 diffraction lights of the 3rd light beam, the position of second best focal point is compared from far away to the thing optical element with first best focal point that 1 diffraction light that utilizes the 3rd light beam forms.

Moreover first best focal point and second best focal point satisfy following formula (1).

0＜L/f＜0.05 (1)

Wherein, f [mm] refers to the focal length of giving above-mentioned the 3rd light beam of structure, above-mentioned first best focal point of formation through above-mentioned first path difference, and L [mm] refers to the distance between above-mentioned first best focal point and above-mentioned second best focal point.

Have, it is even more ideal to satisfy following formula (1 ') again.

0.01≤L/f≤0.043 (1’)

Have, it is particularly desirable to satisfy following formula (1 ") again.

0.016≤L/f≤0.042 (1”)

In addition, L is comparatively desirable more than or equal to 0.03mm and smaller or equal to 0.11mm.Moreover f is comparatively desirable more than or equal to 1.8mm and smaller or equal to 3.0mm.

For the light utilization ratio of the record that not only can improve the 3rd CD and/or playback time, but also can keep sufficient light utilization ratio at the record and/or the playback time of the 1st CD and the 2nd CD, it is comparatively desirable satisfying above-mentioned formula (1), (1 ') or (1 ").

In addition, to the thing optical element make respectively through be provided with give structure to second path difference of thing optical element first light beam and second beam condenser of neighboring area for forming the optically focused luminous point.Comparatively it is desirable to, to the thing optical element make through be provided with give structure to second path difference of thing optical element first beam condenser of neighboring area on the information recording surface of the 1st CD so that can carry out recording of information and/or playback.In addition, to the thing optical element make through be provided with give structure to second path difference of thing optical element second beam condenser of neighboring area on the information recording surface of the 2nd CD so that can carry out recording of information and/or playback.In addition; Under thickness t 2 condition of different of the protective substrate of the thickness t 1 of the protective substrate of the 1st CD and the 2nd CD, second path difference gives that structure is proofreaied and correct spherical aberration that the difference because of the thickness t 2 of the protective substrate of the thickness t 1 of the protective substrate of the 1st CD and the 2nd CD takes place for first light beam of giving structure through second path difference and second light beam and/or the spherical aberration that takes place because of the difference of wavelength of first light beam and second light beam is comparatively desirable.

In addition, as comparatively desirable form, can enumerate the 3rd light beam that has passed through the neighboring area and be not used in the record of the 3rd CD and/or the form of playback.Make the 3rd light beam that passed through the neighboring area at the record of the 3rd CD and/or not help the formation of optically focused luminous point on resetting be comparatively desirable.That is, through be provided with give structure to second path difference of thing optical element the 3rd light beam of neighboring area at the record of the 3rd CD and/or to form flare on resetting be comparatively desirable.As shown in Figure 3; Passed through in the luminous point that the 3rd light beam to the thing optical element forms on the information recording surface of the 3rd CD; By from optical axis one side (or optical spot centre portion) order toward the outer side, the high SCN of optical spot centre portion of light quantity density, the luminous point pars intermedia SMD that light quantity density is lower than optical spot centre portion, the luminous point periphery SOT that light quantity density is higher but lower than optical spot centre portion than luminous point pars intermedia are arranged.Optical spot centre portion is used for the recording of information and/or the playback of CD, and luminous point pars intermedia and luminous point periphery are not used in the recording of information and/or the playback of CD.In above-mentioned, this luminous point periphery is said into flare.That is the 3rd light beam that second path difference of, having passed through in the neighboring area to the thing optical element, to be provided with is given structure forms the luminous point periphery on the information recording surface of the 3rd CD.Have again, at the optically focused luminous point of this said the 3rd light beam or the luminous point luminous point in first best focal point preferably.In addition, even in second light beam that has passed through the thing optical element, the luminous point that on the information recording surface of the 2nd CD, forms preferably also has optical spot centre portion, luminous point pars intermedia, luminous point periphery.

Have again; Give structure and made through the 3rd light beam and forming on the information recording surface of the 3rd CD under the situation of the such structure of flare through second path difference is set in the neighboring area to the thing optical element the neighboring area of thing optical element; Use first light beam for the record that carries out the 1st CD and/or playback, produce the 1st wavelength has changed or when having produced temperature variation, taken place significantly high order from design wavelength the such problem of spherical aberration.Have again,, refer to more than or equal to 5 times and smaller or equal to 9 times spherical aberration in the spherical aberration of this said high order.Therefore; Second path difference is given second foundation structure, four foundation structure or five foundation structure of structure through stating after having; Even use first wavelength, the 1st wavelength to change or under the situation that has produced temperature variation, also can reduce the spherical aberration of high order from design wavelength for the 1st CD.It is desirable to satisfy following formula (2) and (2 ') especially.Even more ideal is satisfies following formula (2 ").

δSAH/δλ≤0.010(λrms/nm) (2)

δSAH＝√((δSA5) ²+(δSA7) ²+(δSA9) ²) (2’)

δSAH/δλ≤0.008(λrms/nm) (2”)

Wherein, δ SA5 refers to: with wavelength from the use wavelength shift of 408nm the light beam of wavelength of λ x carry out the record and/or the playback time of above-mentioned the 1st CD; Become 5 times the spherical aberration that takes place under 0 the multiplying power for spherical aberration SA3 to the multiplying power of thing optical element and 3 times at the light beam of the wavelength of λ x; δ SA7 refers to: the record and/or the playback time that carry out above-mentioned the 1st CD at the light beam with the wavelength of above-mentioned λ x; Become 7 times the spherical aberration that takes place under 0 the multiplying power for spherical aberration SA3 to the multiplying power of thing optical element and 3 times at the light beam of the wavelength of λ x; δ SA9 refers to: with wavelength from the use wavelength shift of 408nm the light beam of wavelength of above-mentioned λ x carry out the record and/or the playback time of above-mentioned the 1st CD, become 9 times the spherical aberration that takes place under 0 the multiplying power for spherical aberration SA3 to the multiplying power of thing optical element and 3 times at the light beam of the wavelength of λ x.δ λ refers to the absolute value of the difference of 408nm and λ xnm.δ λ is preferably smaller or equal to 10nm.

In addition; In order to reduce the spherical aberration of high order; Be decided to be transverse axis, above-mentioned first light beam has been passed through above-mentionedly to be decided to be in the curve map of the longitudinal axis by the above-mentioned path difference that the thing optical element is given during to the thing optical element in the distance from optical axis with above-mentioned radial direction to the thing optical element, the width that the above-mentioned curve map under the above-mentioned design wavelength from above-mentioned first light beam to the thing optical element has squinted the wavelength of 5nm has an above-mentioned path difference discontinuous and above-mentioned discontinuous is more than or equal to 0 and be comparatively desirable smaller or equal to 0.2 λ 1.Having, is that curve map does not have discontinuous portion under 0 the situation at the width of path difference again.

In addition, second path difference is given structure and is preferably given first light beam and second light beam of structure and proofread and correct the chromosphere surface aberration because of the change generation of the trace of the wavelength of first light source and secondary light source having passed through second path difference.The change of the trace of so-called wavelength, refer to ± 10nm is with interior change.For example; First light beam from wavelength X 1 changed ± during 5nm; Utilize second path difference to give the change of the spherical aberration of first light beam that structure compensation passed through the neighboring area, making the variable quantity of the corrugated aberration on the information recording surface of the 1st CD is comparatively desirable more than or equal to 0.010 λ 1rms and smaller or equal to 0.095 λ 1rms.In addition; Second light beam from wavelength X 2 changed ± during 5nm; Utilize second path difference to give the change of the spherical aberration of second light beam that structure compensation passed through the neighboring area, making the variable quantity of the corrugated aberration on the information recording surface of the 2nd CD is comparatively desirable more than or equal to 0.002 λ 2rms and smaller or equal to 0.03 λ 2rms.Thus, recoverable results from by the aberration as the discreteness of the foozle of the wavelength of the laser instrument of light source, wavelength that individual error causes.

Second path difference is given structure and is preferably given first light beam and second light beam of structure and also proofread and correct the spherical aberration that takes place because of the temperature variation to the thing optical element having passed through second path difference.For example; To the temperature variation of thing optical element ± 30 ℃ the time; Utilize second path difference to give the change of the spherical aberration of first light beam that structure compensation passed through the neighboring area or second light beam; Making the variable quantity of the corrugated aberration on the information recording surface of the 1st CD is comparatively desirable more than or equal to 0.010 λ 1rms and smaller or equal to 0.095 λ 1rms, and making the variable quantity of the corrugated aberration on the information recording surface of the 2nd CD is comparatively desirable more than or equal to 0.002 λ 2rms and smaller or equal to 0.03 λ 2rms.

Under the situation that the thing optical element is had neighboring area, to the thing optical element make through to first beam condenser of the neighboring area of thing optical element on the information recording surface of the 1st CD so that can carry out recording of information and/or playback.In addition, in first light beam that has passed through neighboring area, the record and/or the playback time that are preferably in the 1st CD have been proofreaied and correct its spherical aberration.

In addition, as comparatively desirable form, can enumerate that second light beam that has passed through neighboring area is not used in the record and/or the playback of the 2nd CD, the 3rd light beam that has passed through neighboring area is not used in the record of the 3rd CD and/or the form of playback.It is comparatively desirable making second light beam that passed through neighboring area and the 3rd light beam not help the formation of the optically focused luminous point on the information recording surface of the 2nd CD and the 3rd CD respectively.That is, under the situation that the thing optical element is had neighboring area, it is comparatively desirable on the information recording surface of the 3rd CD, forming flare through the 3rd light beam to the neighboring area of thing optical element.In other words, having passed through the 3rd light beam to the neighboring area of thing optical element, on the information recording surface of the 3rd CD, to form the luminous point periphery be comparatively desirable.In addition, under the situation that the thing optical element is had neighboring area, it is comparatively desirable on the information recording surface of the 2nd CD, forming flare through second light beam to the neighboring area of thing optical element.In other words, having passed through second light beam to the neighboring area of thing optical element, on the information recording surface of the 2nd CD, to form the luminous point periphery be comparatively desirable.

Have the 3rd path difference in neighboring area and give under the situation of structure, the 3rd path difference is given structure and can given first light beam of structure and proofread and correct the chromosphere surface aberration because of the change generation of the trace of the wavelength of first light source having passed through the 3rd path difference.The change of the trace of so-called wavelength, refer to ± 10nm is with interior change.For example; First light beam from wavelength X 1 changed ± during 5nm; Utilize the 3rd path difference to give the change of the spherical aberration of first light beam that structure compensation passed through neighboring area, making the variable quantity of the corrugated aberration on the information recording surface of the 1st CD is comparatively desirable more than or equal to 0.010 λ 1rms and smaller or equal to 0.095 λ 1rms.

The 3rd path difference is given structure and is preferably given first light beam of structure and also proofread and correct the spherical aberration that takes place because of the temperature variation to the thing optical element having passed through the 3rd path difference.For example; To the temperature variation of thing optical element ± 30 ℃ the time; Utilize the 3rd path difference to give the change of the spherical aberration of first light beam that structure compensation passed through neighboring area, making the variable quantity of the corrugated aberration on the information recording surface of the 1st CD is comparatively desirable more than or equal to 0.010 λ 1rms and smaller or equal to 0.095 λ 1rms.

Have, first path difference is given the structure that structure preferably has first foundation structure at least again.

First foundation structure be make other the diffraction light quantity of any number of times of 1 time diffraction light amount ratio of first light beam that has passed through first foundation structure big, other the diffraction light quantity of any number of times of 1 time diffraction light amount ratio of second light beam is big, other the big path difference of diffraction light quantity of any number of times of 1 time diffraction light amount ratio of the 3rd light beam is given structure.First foundation structure preferably makes first light beam, second light beam path difference different respectively with the angle of diffraction of the 3rd light beam of having passed through first foundation structure give structure.In addition, the jump amount of the optical axis direction of first foundation structure preferably for the 1st light beam give roughly 1 wavelength part of the 1st wavelength path difference, give the path difference of roughly 0.6 wavelength part of the 2nd wavelength, give the such jump amount of path difference of roughly 0.5 wavelength part of the 3rd wavelength for the 3rd light beam for the 2nd light beam.

In addition; Also can directional light or almost parallel light incided the purpose on the thing optical element by the purpose of the purpose of proofreading and correct the spherical aberration that takes place based on temperature variation, correcting colour aberration and/or at the record and/or the playback time of whole CDs, the structure of will be on first foundation structure overlapping the 3rd foundation structure or the 5th foundation structure makes first path difference and gives structure.

The 3rd foundation structure be make other the diffraction light quantity of any number of times of 2 times diffraction light amount ratio of first light beam that has passed through the 3rd foundation structure big, other the diffraction light quantity of any number of times of 1 time diffraction light amount ratio of second light beam is big, other the big path difference of diffraction light quantity of any number of times of 1 time diffraction light amount ratio of the 3rd light beam is given structure.The 3rd foundation structure preferably makes the angle of diffraction of second light beam that has passed through the 3rd foundation structure give structure with the different path difference of angle of diffraction of first light beam and the 3rd light beam.In addition, the jump amount of the optical axis direction of the 3rd foundation structure preferably for the 1st light beam give roughly 2 wavelength part of the 1st wavelength path difference, give the path difference of roughly 1.2 wavelength parts of the 2nd wavelength, give the such jump amount of path difference of roughly 1 wavelength part of the 3rd wavelength for the 3rd light beam for the 2nd light beam.The 5th foundation structure be make other the diffraction light quantity of any number of times of 10 times diffraction light amount ratio of first light beam that has passed through the 5th foundation structure big, other the diffraction light quantity of any number of times of 6 times diffraction light amount ratio of second light beam is big, other the big path difference of diffraction light quantity of any number of times of 5 times diffraction light amount ratio of the 3rd light beam is given structure.The jump amount of the optical axis direction of the 5th foundation structure preferably for the 1st light beam give roughly 10 wavelength part of the 1st wavelength path difference, give the path difference of roughly 6 wavelength parts of the 2nd wavelength, give the such jump amount of path difference of roughly 5 wavelength parts of the 3rd wavelength for the 3rd light beam for the 2nd light beam.

In addition, to give structure be the structure that has set foundation structure at least to second path difference.

So-called set foundation structure, be passed through set foundation structure first light beam x time diffraction light amount ratio other any number of times the diffraction light quantity greatly, other the big path difference of diffraction light quantity of any number of times of y time diffraction light amount ratio of second light beam gives structure.Have, x and y satisfy following formula (8) again.

0.9·(x·λ1)/(n1-1)≤(y·λ2)/(n2-1)≤1.2·(x·λ1)/(n1-1)(8)

Wherein, x refers to the integer beyond 0, and y refers to the integer beyond 0, and n1 refers to the refractive index under first light beam of thing optical element, and n2 refers to the refractive index under second light beam of thing optical element.

As the foundation structure that satisfies above-mentioned formula (8), for example can enumerate second foundation structure, the 4th foundation structure or the 5th foundation structure.

Second foundation structure be make other the diffraction light quantity of any number of times of 5 times diffraction light amount ratio of first light beam that has passed through second foundation structure big, other the diffraction light quantity of any number of times of 3 times diffraction light amount ratio of second light beam is big, other the big path difference of diffraction light quantity of any number of times of the diffraction light amount ratio of 3 times of the 3rd light beam and 2 times is given structure.Have, in the 3rd light beam, 3 times the diffraction light quantity preferably diffraction light quantity than 2 times is big again.The jump amount of the optical axis direction of second foundation structure preferably for the 1st light beam give roughly 5 wavelength part of the 1st wavelength path difference, give the path difference of roughly 3 wavelength parts of the 2nd wavelength, give the such jump amount of path difference of roughly 2.5 wavelength parts of the 3rd wavelength for the 3rd light beam for the 2nd light beam.The 4th foundation structure be make other the diffraction light quantity of any number of times of 3 times diffraction light amount ratio of first light beam that has passed through the 4th foundation structure big, other the diffraction light quantity of any number of times of 2 times diffraction light amount ratio of second light beam is big, other the big path difference of diffraction light quantity of any number of times of the diffraction light amount ratio of 2 times of the 3rd light beam and 1 time is given structure.Have, in the 3rd light beam, 2 times the diffraction light quantity preferably diffraction light quantity than 1 time is big again.The jump amount of the optical axis direction of the 4th foundation structure preferably for the 1st light beam give roughly 3 wavelength part of the 1st wavelength path difference, give the path difference of roughly 1.9 wavelength parts of the 2nd wavelength, give the such jump amount of path difference of roughly 1.6 wavelength parts of the 3rd wavelength for the 3rd light beam for the 2nd light beam.Have again; Second foundation structure, the 4th foundation structure or the 5th foundation structure (particularly second foundation structure and the 5th foundation structure) have the function that when the wavelength of temperature rising, first light source, secondary light source and the 3rd light source has stretched, reduces spherical aberration; Thus; The excessive of spherical aberration that the refractive index of the plastics when following temperature to rise descends can be compensated, good spherical aberration can be obtained.Have again, compare, the degree of depth of the jump of second foundation structure is shoaled with the 5th foundation structure.In addition, also can on the female aspheric surface (basal plane) different, be provided with second path difference and give second foundation structure of structure, the 4th foundation structure or the 5th foundation structure with other foundation structure.In addition, be preferably in the light beam that has been set on one side incident give above-mentioned path difference, on one side second foundation structure, the 4th foundation structure or the 5th foundation structure as far as possible not to incident female aspheric surface (basal plane) of exerting an influence of light beam on be provided with second path difference and give second foundation structure of structure, the 4th foundation structure or the 5th foundation structure.Moreover, second foundation structure, the 4th foundation structure or the 5th foundation structure that second path difference is given structure preferably along with the direction of light shaft positive cross on leave optical axis and get into optical element the inboard, with certain position be the border along with leaving optical axis towards the outside of optical element such structure.(that is, preferably deepen gradually, be the structure that the border shoals with certain position.)

Have again, comparatively it is desirable to satisfy following formula (8 ').

0.95·(x·λ1)/(n1-1)≤(y·λ2)/(n2-1)≤1.05·(x·λ1)/(n1-1)(8’)

As the structure that satisfies above-mentioned formula (8 '), for example can enumerate second foundation structure or the 5th foundation structure etc.Have, the 4th foundation structure does not satisfy formula (8 ') again.

In addition; Second path difference is given preferably overlapping other the structure of foundation structure on above-mentioned set foundation structure of structure; As other foundation structure, the 3rd preferably above-mentioned foundation structure, the 4th above-mentioned foundation structure or the 6th foundation structure some.The 6th foundation structure be make other the diffraction light quantity of any number of times of 0 time diffraction light amount ratio of first light beam that has passed through the 6th foundation structure big, other the diffraction light quantity of any number of times of 1 time diffraction light amount ratio of second light beam is big, other the big path difference of diffraction light quantity of any number of times of 0 time diffraction light amount ratio of the 3rd light beam is given structure.The 6th foundation structure preferably has the structure of the little step structure on a plurality of 4 rank; The jump amount of the optical axis direction of the single order of little step structure be for the 1st light beam give roughly 2 wavelength part of the 1st wavelength path difference, give the path difference of roughly 1.2 wavelength parts of the 2nd wavelength, give the such jump amount of path difference of roughly 1 wavelength part of the 3rd wavelength for the 3rd light beam for the 2nd light beam; Little step structure as 4 utmost points is whole, preferably become for the 1st light beam give roughly 8 wavelength parts of the 1st wavelength path difference, give the path difference of roughly 5 wavelength parts of the 2nd wavelength, give the such structure of path difference of roughly 4 wavelength parts of the 3rd wavelength for the 3rd light beam for the 2nd light beam.

In addition, also can directional light or almost parallel light be incided the purpose on the thing optical element, give overlapping again the 3rd foundation structure on the structure in second path difference by the purpose of correcting colour aberration and/or at the record and/or the playback time of whole CDs.

Moreover, be under the situation of plastic lens to the thing optical element, preferably have and have the neighboring area that the 3rd path difference is given structure.In this case, the 3rd path difference is given some structures that structure preferably has the first above-mentioned foundation structure, second foundation structure, the 3rd foundation structure, the 4th foundation structure, the 5th foundation structure or the 8th foundation structure at least.The 8th foundation structure be make other the diffraction light quantity of any number of times of 4 times diffraction light amount ratio of first light beam that has passed through the 8th foundation structure big, other the diffraction light quantity of any number of times of the diffraction light amount ratio of 3 times of second light beam and 2 times is big, other the big path difference of diffraction light quantity of any number of times of 2 times diffraction light amount ratio of the 3rd light beam is given structure.In addition, the jump amount of the optical axis direction of the 8th foundation structure preferably for the 1st light beam give roughly 4 wavelength part of the 1st wavelength path difference, give the path difference of roughly 2.5 wavelength parts of the 2nd wavelength, give the such jump amount of path difference of roughly 2 wavelength parts of the 3rd wavelength for the 3rd light beam for the 2nd light beam.Have, give under the situation that structure has the 3rd foundation structure in second path difference, the 3rd path difference is given structure and is preferably had first foundation structure, second foundation structure, the 4th foundation structure, the 5th foundation structure or the 8th foundation structure.On the other hand, give under the situation that structure has the 4th foundation structure in second path difference, the 3rd path difference is given structure and is preferably had first foundation structure, second foundation structure, the 3rd foundation structure, the 5th foundation structure or the 8th foundation structure.In addition, from the viewpoint of making, owing to second foundation structure is made easily, so be comparatively desirable.In addition; From the viewpoint that can suppress the amplitude of variation of the diffraction slope of following temperature variation or wavelength change or light utilization ratio less; The 3rd foundation structure or the 4th foundation structure are comparatively desirable, but particularly in the 4th foundation structure transmissivity some declines are arranged.Thereby, can select the 3rd path difference to give the foundation structure of structure according to purpose.

Be under glass lens or the situation to the thing optical element, preferably having neighboring area as plane of refraction by アサ-lens that マ Le resin constitutes.

In addition, also can be respectively give structure, second path difference and give structure and the 3rd path difference and give structure and be divided into a plurality of zones, in each zone, constitute by different foundation structure with first path difference.Particularly can give structure and the 3rd path difference and give structure and be divided into a plurality of zones, in each zone, constitute by different foundation structure with second path difference.For example; Give inside region and the exterior lateral area outside it that structure is divided into a side that approaches optical axis with second path difference; Inside region has been made second foundation structure overlapping and the structure of the 3rd foundation structure, exterior lateral area has been made the structure of the 7th foundation structure of except second foundation structure and the 3rd foundation structure, stating after overlapping.

In addition, from the viewpoint that the manufacturing that makes metal pattern becomes easily, makes the metastatic of metal pattern to become good, preferably do not make the spacing width of jump too small.Thereby; Designing path difference that overlapping a plurality of foundation structure becomes the basis when giving structure; Taking place under the situation of spacing width smaller or equal to the endless belt of 5 μ m, preferably removing such spacing width and obtain final path difference smaller or equal to the endless belt of 5 μ m and give structure.Be under the situation of convex at the endless belt of spacing width, remove through the endless belt of pruning and get final product, be under the situation of concavity, remove through the landfill endless belt and get final product at the endless belt of spacing width smaller or equal to 5 μ m smaller or equal to 5 μ m.

Thereby the spacing width that at least the first path difference is given structure is greatly comparatively desirable than 5 μ m all.Comparatively it is desirable to, first path difference is given structure, second path difference and is given structure and the 3rd path difference to give whole spacing width of structure bigger than 5 μ m.

In addition, the jump amount leaves nothing to be desired greatly.Give in the path difference that becomes the basis that overlapping a plurality of foundation structures have obtained under the big situation of the value of rank quotient of difference benchmark of certain endless belt of structure; Reduce by 10 λ B/ (n-1) (μ m) through the jump amount that makes endless belt, can reduce excessive jump amount and optical property is not exerted an influence.Have again,, can set value arbitrarily, but preferably 10 λ B/ (n-1) (μ m) are decided to be reference value as the value of benchmark.λ B representes the design wavelength (μ m) of first light beam, and n representes the refractive index of the optical element among the wavelength X B.

In addition, so-called spacing width refers to the width with an endless belt of light shaft positive cross direction.In addition, so-called jump amount refers to the degree of depth of jump of the endless belt of optical axis direction.

In addition, be comparatively desirable viewpoint from the few this point of elongated endless belt making, give in whole endless belt of structure in first path difference, (jump amount/spacing width) is comparatively desirable smaller or equal to 1, even more ideal is smaller or equal to 0.8.Even more ideal is, gives in whole endless belt of structure in whole path difference, and (jump amount/spacing width) is comparatively desirable smaller or equal to 1, and even more ideal is smaller or equal to 0.8.

Will be in order the thing optical element to be decided to be NA1 as the side numerical aperture to the 1st optical disk data reproducing and/or recorded information are necessary; Will be for to the 2nd optical disk data reproducing and/or recorded information necessary being decided to be NA2 as the side numerical aperture (NA1 >=NA2) will be in order to be decided to be NA3 (NA2＞NA3) to the thing optical element as the side numerical aperture to the 3rd optical disk data reproducing and/or recorded information are necessary to the thing optical element.NA1 is more than or equal to 0.8 and smaller or equal to 0.9 or more than or equal to 0.55 and be comparatively desirable smaller or equal to 0.7.Particularly NA1 is 0.85 to be comparatively desirable.NA2 is more than or equal to 0.55 and be comparatively desirable smaller or equal to 0.7.Particularly NA2 is 0.60 to be comparatively desirable.In addition, NA3 is more than or equal to 0.4 and be comparatively desirable smaller or equal to 0.55.Particularly NA3 is 0.45 or 0.53 to be comparatively desirable.

When the use of the 3rd light beam, it is comparatively desirable in being equivalent to more than or equal to 0.9NA3 and the part smaller or equal to the scope of 1.2NA3 (even more ideal is more than or equal to 0.95NA3 and smaller or equal to 1.15NA3), having formed the middle section of thing optical element and the border of neighboring area.Even more ideal is in being equivalent to the part of NA3, to have formed the middle section of thing optical element and the border of neighboring area.In addition; When the use of second light beam, the border that in being equivalent to more than or equal to 0.9NA2 and the part smaller or equal to the scope of 1.2NA2 (even more ideal is more than or equal to 0.95NA2 and smaller or equal to 1.15NA2), has formed the neighboring area of thing optical element and neighboring area is comparatively desirable.Even more ideal is, in being equivalent to the part of NA2, has formed the border with neighboring area, the neighboring area of thing optical element.When the use of first light beam, the border that in being equivalent to more than or equal to 0.9NA1 and the part smaller or equal to the scope of 1.2NA1 (even more ideal is more than or equal to 0.95NA1 and smaller or equal to 1.15NA1), has formed the outside of the most peripheral of thing optical element is comparatively desirable.Even more ideal is, in being equivalent to the part of NA1, has formed the border to the outside of the most peripheral of thing optical element.

To pass through the 3rd beam condenser to the thing optical element under the situation on the information recording surface of the 3rd CD, it is comparatively desirable that spherical aberration has discontinuous of at least 1 position.In this case, when the use of the 3rd light beam, in more than or equal to 0.9NA3 and scope, exist discontinuous to be comparatively desirable smaller or equal to 1.2NA3 (even more ideal is more than or equal to 0.95NA3 and smaller or equal to 1.15NA3).Even will pass through second beam condenser to the thing optical element under the situation on the information recording surface of the 2nd CD, it also is comparatively desirable that spherical aberration has discontinuous of at least 1 position.In this case, when the use of second light beam, in more than or equal to 0.9NA2 and scope, exist discontinuous to be comparatively desirable smaller or equal to 1.2NA2 (even more ideal is more than or equal to 0.95NA2 and smaller or equal to 1.1NA2).

In addition; Spherical aberration continuous, do not have discontinuous situation and will pass through the 3rd beam condenser to the thing optical element under the situation on the information recording surface of the 3rd CD, the absolute value of longitudinal spherical aberration is more than or equal to 0.03 μ m, the absolute value of longitudinal spherical aberration is comparatively desirable smaller or equal to 0.02 μ m in NA3 in NA2.Even more ideal is, in NA2 the absolute value of longitudinal spherical aberration more than or equal to 0.08 μ m, in NA3 the absolute value of longitudinal spherical aberration smaller or equal to 0.01 μ m.In addition; To pass through second beam condenser to the thing optical element under the situation on the information recording surface of the 2nd CD, the absolute value of longitudinal spherical aberration is more than or equal to 0.03 μ m, the absolute value of longitudinal spherical aberration is comparatively desirable smaller or equal to 0.005 μ m in NA2 in NA1.

In addition, because diffraction efficiency depends on the endless belt degree of depth of diffraction structure, so, can suitably set diffraction efficiency for each wavelength of middle section according to the purposes of optical take-up apparatus.For example, in the optical take-up apparatus that the 1st CD is write down and reset, second, third CD is only reset, paying attention to first light beam, to set the diffraction efficiency of middle section and/or neighboring area be comparatively desirable.On the other hand; In the optical take-up apparatus of the 1st CD only being reset, the second, the 3rd CD being write down and reset, the diffraction efficiency of middle section is decided to be payes attention to second, third light beam, the diffraction efficiency of neighboring area be decided to be to pay attention to second light beam be comparatively desirable.

Under any situation,, can guarantee to utilize the high diffraction efficiency of first light beam of each regional area weighted average calculation through satisfying following conditional (14).

η11≤η21 (14)

Wherein, The diffraction efficiency of first light beam in the η 11 expression middle sections; The diffraction efficiency of first light beam in the η 21 expression neighboring areas has again, is decided to be in the diffraction efficiency with middle section under the situation of the light beam of paying attention to second, third wavelength; The diffraction efficiency step-down of first light beam of middle section; But the numerical aperture of the 1st CD than the big situation of the numerical aperture of the 3rd CD under, if in the effective diameter integral body of first light beam, consider, then the influence that descends of the diffraction efficiency of middle section is so not big.

In addition, preferably satisfy following formula (3).

η13≥40％ (3)

Wherein, η 13 is light utilization ratios of the 3rd light beam in the middle section.

Have, the light utilization ratio in this instructions can define as following again.To be formed first path difference give structure and second path difference give structure (giving structure) with the 3rd path difference to the thing optical element and cut off under the situation of the light beam that incides the zone beyond the determination object with measure in light quantity in the airy disc of the optically focused luminous point that formed on the information recording surface of the corresponding CD of the light beam that uses be decided to be A; To be by forming with same material and having a same focal length; Thickness on the axle; Numerical aperture; The corrugated aberration; Do not form first path difference and give structure; Second path difference give structure and the 3rd path difference give structure to the thing optical element and cut off under the situation of the light beam that incides the zone beyond the determination object with measure in light quantity in the airy disc of the optically focused luminous point that formed on the information recording surface of the corresponding CD of the light beam that uses when being decided to be B by the value of A/B calculating.Have, so-called at this said airy disc, the optical axis that refers to the optically focused luminous point is the circle of radius centered r ' again.Use r '=0.61 λ/NA to represent.

For the light utilization ratio that not only can improve the record that carries out the 3rd CD and/or playback time, but also can carry out the record and/or the playback of first CD and second CD well, light (blaze) wavelength of preferably will shining is decided to be the wavelength between first wavelength and second wavelength.Even more ideal is to be decided to be more than or equal to 405nm and smaller or equal to 600nm.

In addition; Giving in the 3rd light beam of structure having passed through first path difference, is comparatively desirable in the difference of light quantity and the light quantity of the diffraction light that forms second best focal point poor, that promptly form the diffraction light of first best focal point of the light quantity of the light quantity of the diffraction light of the diffraction number of times that becomes maximum light quantity and the diffraction light of the diffraction number of times that becomes secondly big light quantity more than or equal to 15%.Even more ideal is more than or equal to 30%.

First light beam, second light beam and the 3rd light beam can be used as directional light and incide in the thing optical element, also can be used as diverging light or restrain light to incide in the thing optical element.Comparatively it is desirable to, the multiplying power m1 for to the incident beam of thing optical element of first light beam satisfies following formula (4).

-0.02＜m1＜0.02 (4)

On the other hand, make first light beam incides the situation in the thing optical element as diverging light under, the multiplying power m1 to the thing optical element that first light beam incides in the thing optical element time preferably satisfies following formula (4 ').

-0.10＜m1＜0.00 (4’)

In addition, make under second light beam incides the situation in the thing optical element as directional light or almost parallel light, the multiplying power m2 for to the incident beam of thing optical element of second light beam preferably satisfies following formula (5).

-0.02＜m2＜0.02 (5)

On the other hand, make second light beam incides the situation in the thing optical element as diverging light under, the multiplying power m2 to the thing optical element that second light beam incides in the thing optical element time preferably satisfies following formula (5 ').

-0.10＜m2＜0.00 (5’)

In addition, make under the 3rd light beam incides the situation in the thing optical element as directional light or almost parallel light, the multiplying power m3 for to the incident beam of thing optical element of the 3rd light beam preferably satisfies following formula (6).

-0.02＜m3＜0.02 (6)

Under the situation that satisfies above-mentioned (6) formula, that is,, the thing optical element is preferably had the 4th path difference give structure making under the 3rd light beam incides the situation in the thing optical element as directional light or almost parallel light.The 4th path difference is set on to the thing optical element and gives under the situation of structure, be preferably in and be provided with first path difference and give on the different optical surface of optical surface that structure and second path difference give structure and being provided with.In addition, be preferably on the face to CD one side of thing optical element and be provided with.The 4th path difference is given the preferably structure of correcting colour aberration of structure.In addition, the 4th path difference is given some structures that structure preferably has second foundation structure, the 3rd foundation structure, the 5th foundation structure or the 6th foundation structure.Have again; Give under the situation that structure has the 3rd foundation structure in the 4th path difference; For first light beam and second light beam; The 4th path difference is given structure also can have the function of proofreading and correct the spherical aberration that the difference because of the thickness t 2 of the protective substrate of the thickness t 1 of the protective substrate of the 1st CD and the 2nd CD takes place, and has this function respectively owing to giving structure with second path difference, so be comparatively desirable.

Under the situation that satisfies above-mentioned (6), also can give structure, second path difference and give at least one that structure and the 3rd path difference give structure (comparatively it is desirable to two, even more ideal be whole) and go up foundation structure that superimposed (overlapping) have the function of chromatic aberation correction etc. and replace being provided with the 4th path difference and give structure in first path difference.For example, can make and give structure, second path difference in first path difference and give some structures that structure and the 3rd path difference are given superimposed second foundation structure, the 3rd foundation structure, the 5th foundation structure or the 6th foundation structure at least one of structure.Particularly under the situation that satisfies above-mentioned (4), (5) and (6); Particularly make first light beam, second light beam and the 3rd light beam whole incide the situation of thing optical element as directional light and the 4th path difference be not set in to the thing optical element give under the situation of structure, be preferably in first path difference and give overlapping the 3rd foundation structure on the structure.

On the other hand, make the 3rd light beam incides the situation on the thing optical element as diverging light under, the multiplying power m3 for to the incident beam of thing optical element of the 3rd light beam preferably satisfies following formula (7).

-0.10＜m3＜0.00 (7)

In addition, the thing optical element is had under the situation of plastic lens, it well is comparatively desirable that temperature characterisitic is remained.In this case, it is comparatively desirable satisfying following conditional (16).Moreover it is comparatively desirable in wavelength characteristic and temperature characterisitic, keeping good balance.In order to satisfy such characteristic, preferably satisfy following conditional (16) and (17).

+0.0005(WFEλrms/(℃·mm))≤δSAT1/f’≤+0.0020(WFEλrms/(℃·mm)) (16)

-0.00020(WFEλrms/(℃·mm))≤δSATλ/f’≤-0.00002(WFEλrms/(nm·mm)) (17)

Wherein, δ SAT1 representes to use the record of the CD under the wavelength (in this case, supposing the wavelength variation of not following temperature variation) and/or the δ SA3/ δ T (rate of temperature changes of 3 spherical aberrations) to the thing optical element of playback time.What is called is used wavelength, refers to the wavelength of the light source that in the optical take-up apparatus that has the thing optical element, uses.Comparatively it is desirable to, using wavelength is more than or equal to 400nm and smaller or equal to the wavelength of the scope of 415mm and through carrying out the record of CD and/or the wavelength of playback to the thing optical element.Can not as above-mentioned, set under the situation of using wavelength, with 408nm as using wavelength, can obtain to the δ SAT1 of thing optical element with after the δ SAT2, the δ SAT3 that state.Have, WFE has represented to have showed with the corrugated aberration situation of 3 spherical aberrations again.In addition, δ SA λ representes to use the record of the CD under the wavelength and/or the δ SA3/ δ λ (the wavelength change rates of 3 spherical aberrations) of playback time.In addition, environment temperature room temperature preferably.So-called room temperature is more than or equal to 10 ℃ and smaller or equal to 40 ℃, preferably 25 ℃.F ' refers to the focal length to the thing optical element under the light beam (preferably 408nm) of wavelength X 1.

Say that further except the spherical aberration to the thing optical element that causes because of temperature variation changed, preferably the wavelength change of the light source of temperature variation was followed in consideration.It is comparatively desirable satisfying following conditional (18).

0(WFEλrms/(℃·mm))≤δSAT2/f’≤+0.0020(WFEλrms/(℃·mm)) (18)

Wherein, δ SAT2 refers in the wavelength variation of following temperature variation is 0.05nm/ ℃ light source and carries out the record of CD and/or the δ SA3/ δ T to the thing optical element of playback time.

Even more ideal is to satisfy following conditional (18 ').

0(WFEλrms/(℃·mm))≤δSAT2/f’≤+0.0015(WFEλrms/(℃·mm)) (18’)

In addition, relay lens, this relay lens of having collimation lens etc. at the Focused Optical system of optical take-up apparatus are under the situation of plastic lens, and the conditional (19) below satisfying is comparatively desirable.

0(WFEλrms/(℃·mm))≤δSAT3/f’≤+0.0015(WFEλrms/(℃·mm)) (19)

Wherein, δ SAT3 refer to the record that in the wavelength variation of following temperature variation is 0.05nm/ ℃ light source, carries out high density compact disc and/or playback time comprise relay lens and to the whole δ SA3/ δ T of the optical system of thing optical element.

The operating distance to the thing optical element when in addition, using the 3rd CD (WD) is more preferably greater than equaling 0.15mm and smaller or equal to 1.5mm.Comparatively it is desirable to, more than or equal to 0.2mm and smaller or equal to 0.4mm.Secondly, when using the 2nd CD to the WD of thing optical element more preferably greater than equaling 0.3mm and smaller or equal to 0.7mm.Moreover, when using the 1st CD to the WD of thing optical element more preferably greater than equal 0.4mm and smaller or equal to 0.9mm (under the situation of t1＜t2, more preferably greater than equal 0.6mm and smaller or equal to 0.9mm).

In addition, in order to stretch above-mentioned WD a little, be under the situation of single element lens to the thing optical element, it is preferably thin as much as possible that the axle of these lens is gone up thickness.On the other hand, if too thin, be under the situation of plastic lens then at lens, influence of temperature variation is too big, is unfavorable.Therefore, it is comparatively desirable satisfying following conditional (15).

1≤T/f≤1.13 (15)

Wherein, T (mm) expression is gone up thickness to the axle of thing optical element, the focal length to the thing optical element in f (mm) expression the 3rd light beam.Have again, the axle of thing optical element is gone up thickness more preferably greater than equaling 2.31mm and smaller or equal to 2.61mm.

To the entrance pupil of thing optical element footpath when using the 1st CD more preferably greater than equaling φ 2.8mm and smaller or equal to φ 4.5mm.

Have again, when the tracking of the 3rd CD that carries out CD etc., from be reduced in the sensor of following the tracks of usefulness as far as possible, passed through the viewpoint of the influence that the unwanted light of middle section produces, and the conditional below satisfying (1 ") be comparatively desirable.

0.02≤T/f＜0.05 (1”)

The conditional that even more ideal is below satisfying (1 " ')

0.032≤T/f＜0.05 (1”’)

But if as above-mentioned, strengthen the distance of the 1st best focal point and the 2nd best focal point, then when the recording/reproducing of the 3rd CD, the light beam that has passed through the neighboring area also incides on the photo detector, the possibility of the accuracy of the recording/reproducing that exerts an influence.In order to reduce the possibility that causes this influence; Under the situation that satisfies above-mentioned conditional (1 "); comparatively it is desirable to: 1) in neighboring area and/or neighboring area, be provided for that the 3rd light beam is made flare and make its structure of disperseing far, 2) the opening limiting element is set.

At first, explain in neighboring area and/or neighboring area and be provided for the 3rd light beam is made the situation that flare makes its structure of disperseing far.

Comparatively desirable state through the 3rd light beam of neighboring area and/or neighboring area at first is described when the recording/reproducing of the 3rd CD.Under the situation of the recording/reproducing of having imagined the 3rd CD; Among the longitudinal spherical aberration figure of the 3rd light beam that is decided to be amount from the height of optical axis, with transverse axis on the direction that the longitudinal axis is decided to be with light shaft positive cross; If passed through the amount of the 3rd light beam of the middle section of thing optical element greatly, then can be described as comparatively desirable situation with the absolute value of the difference of the amount of the 3rd light beam that has passed through neighboring area and/or neighboring area.Therefore; Be to satisfy the situation of above-mentioned conditional (1 ") and imagined among the longitudinal spherical aberration figure of recording/reproducing of the 3rd CD; under the situation of minimum value of having passed through the absolute value of the difference in the amount of the amount of the 3rd light beam of the middle section of thing optical element and the 3rd light beam that has passed through neighboring area and/or neighboring area, preferably as following, carry out smaller or equal to 10 μ m.Comparatively it is desirable to; Be provided for that the 3rd light beam is made flare in the difference of amount in for part and make its path difference of disperseing far give structure, make the minimum value of having passed through the difference in the amount of the amount of the 3rd light beam of the middle section of thing optical element and the 3rd light beam that has passed through neighboring area and/or neighboring area bigger than 10 μ m smaller or equal to the optical axis height of 10 μ m.Promptly; Comparatively it is desirable to; In the longitudinal spherical aberration figure that satisfies above-mentioned conditional (1 "), the minimum value of having passed through the difference in the amount of amount and the 3rd light beam that has passed through neighboring area and/or neighboring area (also can be the zone smaller or equal to necessary numerical aperture of the 3rd CD) of the 3rd light beam of the middle section (also can be the zone more than or equal to necessary numerical aperture of the 3rd CD) to the thing optical element is bigger than 10 μ m.Even more ideal is, bigger than 15 μ m.

In addition; Under the situation of the formula of satisfying condition (1 "), second path difference is given structure and/or the 3rd path difference and is given structure and except other foundation structure, preferably have the 7th foundation structure as the 3rd light beam is made the structure that flare makes it disperse far in its a part of zone at least.The 7th foundation structure be make other the diffraction light quantity of any number of times of 0 time diffraction light amount ratio of first light beam that has passed through the 7th foundation structure big, other the diffraction light quantity of any number of times of 0 time diffraction light amount ratio of second light beam is big, the 3rd light beam ± other the big path difference of diffraction light quantity of any number of times of 1 time diffraction light amount ratio gives structure.In addition, the jump amount of the optical axis direction of the 7th foundation structure preferably for the 1st light beam give roughly 5 wavelength part of the 1st wavelength path difference, give the path difference of roughly 3 wavelength parts of the 2nd wavelength, give the such jump amount of path difference of roughly 2.5 wavelength parts of the 3rd wavelength for the 3rd light beam for the 2nd light beam.And then the shape of the 7th foundation structure preferably repeats the shape of the concavo-convex binary shape of single order.As an example; Can enumerate that the inside region that approaches optical axis of giving structure with second path difference has made second foundation structure overlapping and the structure of the 3rd foundation structure, the exterior lateral area of leaving optical axis of comparing with inside region of second path difference being given structure has made the structure of second foundation structure, the 3rd foundation structure and the 7th foundation structure overlapping.Particularly be preferably in the part of optical axis height of that kind of having narrated in the paragraph of front the 7th foundation structure is set.Under most situation, it is desirable to comparatively that a side of leaving optical axis in the neighboring area is provided with the 7th foundation structure, the side that approaches optical axis in neighboring area is provided with the 7th foundation structure.

Secondly, the comparatively desirable state of second light beam that when the recording/reproducing of the 2nd CD, passes through neighboring area be described.Under the situation of the recording/reproducing of having imagined the 2nd CD; In longitudinal spherical aberration figure; If passed through the amount of second light beam of the middle section of thing optical element greatly, then can be described as comparatively desirable situation with the absolute value of the difference of the amount of second light beam that has passed through neighboring area and/or neighboring area.Therefore; Be to satisfy the situation of above-mentioned conditional (1 ") and imagined among the longitudinal spherical aberration figure of recording/reproducing of the 2nd CD; under the situation of minimum value of having passed through the absolute value of the difference in the amount of the amount of second light beam of the middle section of thing optical element and neighboring area and second light beam that has passed through neighboring area, preferably as following, carry out smaller or equal to 10 μ m.Comparatively it is desirable to; Be provided for that second light beam is made flare in the difference of amount in for part and make its path difference of disperseing far give structure, make the minimum value of having passed through the difference in the amount of the amount of second light beam of the middle section of thing optical element and neighboring area and second light beam that has passed through neighboring area bigger than 10 μ m smaller or equal to the optical axis height of 10 μ m.Promptly; Comparatively it is desirable to; In the longitudinal spherical aberration figure that satisfies above-mentioned conditional (1 "), passed through the minimum value of the difference in the amount of the amount of second light beam of the middle section of thing optical element and neighboring area (also can be the zone smaller or equal to necessary numerical aperture of the 2nd CD) and second light beam that has passed through neighboring area (also can be the zone more than or equal to necessary numerical aperture of the 2nd CD) bigger than 10 μ m.Even more ideal is, bigger than 15 μ m.

In addition, under the situation of the formula of satisfying condition (1 "), be preferably in the 3rd path difference and give being provided with in the structure second light beam is made the structure that flare makes it disperse far.For example, can enumerate in the 3rd path difference is given its a part of zone at least of structure as the one of which example and have the 3rd foundation structure as second light beam is made the structure that flare disperses it significantly.In addition, owing to use which kind of foundation structure to decide as second light beam being made the relation that flare makes comparatively desirable this point basis of its structure of disperseing significantly and other path difference give structure, so cannot treat different things as the same.As an example; Can enumerate the inside region that approaches optical axis of giving structure with the 3rd path difference and make the structure that only is made up of the 3rd foundation structure, the exterior lateral area of leaving optical axis of comparing with inside region of the 3rd path difference being given structure makes the structure that only is made up of second foundation structure.In addition; In this example, the inside region that the inside region of also can be again giving structure with the 3rd path difference is divided into two zones, will be in a side who more approaches optical axis has made the 7th foundation structure overlapping and the structure of the 3rd foundation structure, the inside region that will be in a side who leaves optical axis make the structure that only is made up of the 3rd foundation structure.As another example, also can make with the 3rd path difference give that structure is divided into two zones, the inside region that will be in a side who more approaches optical axis has made the 7th foundation structure overlapping and the structure of second foundation structure, the exterior lateral area that will be in a side who leaves optical axis make the structure that only is made up of second foundation structure.

Secondly, explain 2) the situation that the opening limiting element is set.As stated; Give under the situation that structure gives the 7th foundation structure second path difference being given structure and/or the 3rd path difference; According to optical design, exist the 3rd light beam that takes place by the 7th foundation structure+1 diffraction light and/or-1 diffraction light incide the possibility on the photo detector.In order to prevent this point, the opening limiting element is set preferably.In this case, there is no need to give structure and/or the 3rd path difference to second path difference gives structure and gives the 7th foundation structure.

Be preferably in to first light beam, second light beam and the 3rd light beam be in the common light path and with the thing optical element is compared a side that approaches first light source, secondary light source and the 3rd light source the opening limiting element is set.In addition, the opening limiting element has the first area of approaching optical axis and compares the second area that leaves optical axis with the first area.The first area sees through the whole of first light beam, second light beam and the 3rd light beam; Second area sees through first light beam and second light beam, does not make the 3rd beam condenser on first area that has seen through the opening limiting element and the 3rd beams focusing position to the thing optical element.In addition; As second area, just like the dichroism light filter such see through first light beam and second light beam, do not make it be concentrated on the locational kind of the 3rd beams focusing of having passed through the first area through the 3rd light beam is seen through and as diffraction optical element through first light beam and second light beam, become flare and do not make it be concentrated on the locational kind of the 3rd beams focusing of having passed through the first area through making the 3rd light beam.Suppose that the 3rd light beam that has passed through the first area incides on the middle section to the thing optical element.Concrete example as such opening limiting element; Can use dichroism light filter or diffraction optical element comparatively ideally, particularly can use comparatively ideally in approaching the zone of optical axis and to see through blue light, red light and infrared light, leave and see through blue light and red light in the zone of optical axis, do not see through the dichroism light filter of infrared light.

In addition, optical take-up apparatus has under most situation and is used for linearly polarized light is converted into circularly polarized light or converts circularly polarized light the λ/4 wavelength sheets of linearly polarized light into, and the opening limiting element can be realized integrated with this λ/4 wavelength sheets.

As the comparatively desirable example of λ/4 wavelength sheets, roughly can enumerate following 3 kinds, but be not limited thereto.As first kind of λ/4 wavelength sheets, can enumerate the λ/4 wavelength sheets of high molecule liquid crystal layer with the liquid crystal polymer of having hardened.For example; Make the phase plate that possesses the 1st organic thin film layer and the 2nd organic thin film layer; 1/2 wavelength of length of delay, the 2nd organic thin film layer the 1st organic thin film layer has to(for) the light that is in certain zone (for example viewing area) for the light of this same area have 1/4 wavelength length of delay and also with the 1st become the 1st organic thin film layer with the 2nd organic thin film ply the optical axis of optical axis and the 2nd organic thin film layer with set angular cross, the 1st and the 2nd organic thin film layer is a high molecule liquid crystal layer etc.In more detail, for example can the spy of publication communique be opened the content application put down in writing in the 2004-198942 communique in the λ/4 wavelength sheets of first kind.

As second kind of λ/4 wavelength sheets, can enumerate and have structural birefringent λ/4 wavelength sheets.For example can enumerate 2 kinds of different medium of refractive index (for example, 100～300nm) alternately arranges and has the birefringent refractive index cycle structure of display structure property, utilizes this structural birefringence to cause the λ/4 wavelength sheets of phase differential with small Cycle Length.In addition; As another example; Can enumerate the multi-disc wavelength piece element that uses concavo-convex periodic structure, determine the physical dimension of wavelength piece element and make the λ/4 wavelength sheets of its combination with the mode that improves light transmission with λ/2＜P＜λ (P is structural cycle (μ m), and λ is wavelength (μ m)).About the latter's example, in more detail, for example can the spy of publication communique be opened the content application put down in writing in the 2006-139263 communique in the λ/4 wavelength sheets of second kind.

As the third type of λ/4 wavelength sheets, can enumerate range upon range of and only be transformed to linearly polarized light or be transformed to the λ/4 wavelength sheets of the such multilayered polymer film of circularly polarized light from linearly polarized light from circularly polarized light in the certain wavelengths zone.In more detail, for example can be with the content application of having put down in writing among the open communique EP1134068 of European patent in the λ/4 wavelength sheets of the third type.

The optical data recording/reproducing device relevant with the present invention has the optical disc apparatus that has above-mentioned optical take-up apparatus.

At this; If the optical disc apparatus about in optical data recording/reproducing device, equipping explains, then in optical disc apparatus, have from the optical data recording/reproducing device main body of having held optical take-up apparatus etc. only will be under the state that CD has been installed retainable pallet each optical disc apparatus main body of being fetched into outside mode and will having held optical take-up apparatus etc. be fetched into outside mode.

Structural elements below having equipped substantially in the optical data recording/reproducing device of the modes of stating in the use, but be not limited thereto.These structural elements are optical take-up apparatus of in casing etc., being received, make the optical take-up apparatus of search motor that optical take-up apparatus moves towards the interior week or the periphery of CD together with casing etc. drive source, have the casing of optical take-up apparatus towards the delivery unit of the optical take-up apparatus of the interior week of CD or the guiding rail of periphery guiding etc. with carry out spindle motor that the rotation of CD drives etc.

In the former mode; Except these each structural elements; Also be provided with under the state that CD has been installed retainable carriage and the filling mechanism that is used to make carriage to slide etc.; In the latter's mode, there are not carriage and filling mechanism, be preferably in the rotary draw work that is equivalent to be drawn out to outside underframe and be provided with each structural elements.

According to the present invention; Even use the single element lens conduct to the thing optical element; Can suitable flare take place at the record of CD or DVD and/or playback time also, can provide for 3 kinds of different CDs of recording density of high density compact disc, DVD and CD etc. can suitably carry out the optical take-up apparatus of recording of information and/or playback, to thing optical element and optical data recording/reproducing device and can realize the optical take-up apparatus of simplification, the cost degradation of its structure, to thing optical element and optical data recording/reproducing device.In addition, can provide for 3 kinds of different CDs whole can improve the light utilization ratio, can guarantee the optical take-up apparatus of sufficient light quantity, to thing optical element and optical data recording/reproducing device.

[embodiment]

Below, with reference to description of drawings example of the present invention.Fig. 4 is the figure of structure of optical take-up apparatus PU1 that roughly representes can suitably carry out for BD, DVD and CD as different CDs this example of recording of information and/or playback.Can such optical take-up apparatus PU1 be installed in the optical data recording/reproducing device.At this, the 1st CD is decided to be BD, the 2nd CD is decided to be DVD, the 3rd CD is decided to be CD.Have again, the invention is not restricted to this example.

Optical take-up apparatus PU1 is made up of following part: in a packaging body, constituted luminous under the situation of BD being carried out recording of information and/or playback and penetrate the blue violet semiconductor laser LD1 (the 1st light source) of blue-violet laser light beam (the 1st light beam) of wavelength 408nm and luminous and penetrate the light source packaging body LDP of red laser diode LD2 (the 2nd light source) of the laser beam (the 2nd light beam) of wavelength 658nm under the situation of DVD being carried out recording of information and/or playback; By luminous under the situation of CD being carried out recording of information and/or playback and penetrate plastic single lens (to the thing optical element) OL of the polyolefin series of the common photodetector PD1 (also can have a plurality of light accepting parts that BD usefulness and DVD use) that hololaser HL, BD and DVD that infrared semiconductor laser LD3 (the 3rd light source) and the photodetector PD2 that accepts from the folded light beam of the information recording surface RL3 of CD of the laser beam (the 3rd light beam) of wavelength 785nm constitute use, 1 group of structure; 2 through-drive device AC1; 1 through-drive device AC2; By the optical beam expander EXP that disposes in the common light path of jointly passing through at the 1st to the 3rd light beam, constituted by 1 through-drive device AC2 movable the 1st lens L1, the 2nd lens L2 on optical axis direction; The 1st polarization beam splitter BS1; The 2nd polarization beam splitter BS2; 1/4 wavelength sheet QWP; Be used for add the sensing lens SEN of astigmatism from the folded light beam of information recording surface RL1; In the light path that the 1st light beam and the 2nd light beam pass through, dispose, be the 1st collimation lens COL1 of parallel beam with the 1st light beam and the 2nd optical beam transformation; And only in the light path that the 3rd light beam passes through, dispose, be the 2nd collimation lens COL2 of parallel beam with the 3rd optical beam transformation.In addition, the light source as BD uses except above-mentioned blue violet semiconductor laser LD1, also can use bluish violet SHG laser instrument.Have, the relay lens that first light beam passes through, promptly the 1st collimation lens COL1 is preferably in the structure that the path difference that has second foundation structure on the optical surface is given the such function that has the correcting colour aberration of structure again.

Shown in Fig. 1 and Fig. 5; In the object lens OL of this example, it is the concentric circles at center that the neighboring area MD that on the aspherics face of light source one side, will comprise the middle section CN of optical axis, disposed around it and then the neighboring area OT that around it, has disposed form with the optical axis.Have again, do not represent the ratio of the area etc. of middle section, neighboring area, neighboring area exactly.

In optical take-up apparatus PU1; BD is being carried out under the situation of recording of information and/or playback; Utilizing 1 through-drive device AC2 to adjust the position of the 1st lens L1 so that after penetrating the 1st light beam under the state of optical beam expander EXP, make blue violet semiconductor laser LD1 luminous at parallel beam.As describing its opticpath with solid line among Fig. 4; Behind the divergent beams that utilized the 1st polarization beam splitter BS1 to reflect to penetrate from blue violet semiconductor laser LD1; Utilize collimation lens COL1 to be transformed to parallel beam; Utilize its diameter of optical beam expander EXP expansion,, utilize not shown diaphragm confine optical beam diameter through 1/4 wavelength sheet QWP; After inciding on the object lens OL under the state of directional light, become the luminous point that forms at information recording surface RL1 from this protective substrate PL1 through BD.The light beam of optical surface that middle section CN, neighboring area MD, neighboring area OT and CD one side of object lens OL have been passed through in utilization forms the optically focused luminous point on the information recording surface RL1 of BD.Object lens OL be utilized in its circumferential arrangement 2 through-drive device AC1 focus on and follow the tracks of.

After the folded light beam of utilizing information pits to modulate on the information recording surface RL1 has seen through object lens OL, 1/4 wavelength sheet QWP, optical beam expander EXP and the 2nd polarization beam splitter BS2 once more; Utilize the 1st collimation lens COL1 to make converging beam; After having seen through the 1st polarization beam splitter BS1; Utilize sensing lens SEN to add astigmatism, on the sensitive surface of photodetector PD1, restrain.Then, use the output signal of photodetector PD1, can read the information that on BD, has write down.

In addition; In optical take-up apparatus PU1; DVD is being carried out under the situation of recording of information and/or playback, utilizing 1 through-drive device AC2 to adjust the position of the 1st lens L1 so that after penetrating the 2nd light beam under the state of optical beam expander EXP, make red laser diode LD2 luminous at parallel beam.As describing its opticpath with dotted line among Fig. 4; Behind the divergent beams that utilized the 1st polarization beam splitter BS1 to reflect to penetrate from red laser diode LD2; Utilize collimation lens COL1 to be transformed to parallel beam; Utilize its diameter of optical beam expander EXP expansion,, utilize not shown diaphragm confine optical beam diameter through 1/4 wavelength sheet QWP; After inciding on the object lens OL under the state of directional light, become the luminous point that forms at information recording surface RL2 from this protective substrate PL2 through DVD.The light beam of optical surface that middle section CN, neighboring area MD and CD one side of object lens OL have been passed through in utilization forms the optically focused luminous point, is optical spot centre portion on the information recording surface RL2 of DVD.The light beam that has passed through neighboring area OT becomes flare, forms the luminous point periphery.Object lens OL be utilized in its circumferential arrangement 2 through-drive device AC1 focus on and follow the tracks of.

After the folded light beam of utilizing information pits to modulate on the information recording surface RL2 has seen through object lens OL, 1/4 wavelength sheet QWP, optical beam expander EXP and the 2nd polarization beam splitter BS2 once more; Utilize the 1st collimation lens COL1 to make converging beam; After having seen through the 1st polarization beam splitter BS1; Utilize sensing lens SEN to add astigmatism, on the sensitive surface of photodetector PD1, restrain.Then, use the output signal of photodetector PD1, can read the information that on DVD, has write down.

In addition; In optical take-up apparatus PU1; CD is being carried out under the situation of recording of information and/or playback; Utilizing 1 through-drive device AC2 to adjust the position of the 1st lens L1, make infrared semiconductor laser LD3 luminous so that penetrate the 3rd light beam (embodiment 1) under the state of optical beam expander EXP or the state at parallel beam down behind ejaculation the 3rd light beam (embodiment 2) at weak divergent beams.As describing its opticpath with a dot-and-dash line among Fig. 4, utilize the 2nd collimation lens COL2 to be transformed to parallel beam from the divergent beams that infrared semiconductor laser LD3 has penetrated.Thereafter; Utilize the 2nd polarization beam splitter BS2 reflection; Utilize optical beam expander EXP to change to weak divergent beams or after expanding its diameter original state of parallel beam under; Through 1/4 wavelength sheet QWP, after having incided on the object lens OL under the state of weak limited diverging light or directional light, become the luminous point that forms at information recording surface RL3 from this protective substrate PL3 through CD.The light beam of optical surface that middle section CN and CD one side of object lens OL have been passed through in utilization forms the optically focused luminous point, is optical spot centre portion on the information recording surface RL3 of CD.The light beam that has passed through neighboring area OT and neighboring area MD becomes flare, forms the luminous point periphery.Object lens OL be utilized in its circumferential arrangement 2 through-drive device AC1 focus on and follow the tracks of.

After the folded light beam of utilizing information pits to modulate on the information recording surface RL3 has seen through object lens OL, 1/4 wavelength sheet QWP, optical beam expander EXP once more, utilize the 2nd polarization beam splitter BS2 reflection, utilize the 2nd collimation lens COL2 to be transformed to converging beam.On photodetector PD2 restrain thereafter.Then, use the output signal of photodetector PD2, can read the information that on CD, has write down.

In the time of on first light beam that has penetrated from blue violet semiconductor laser LD1 has incided thing optical element OL; Second path difference that first path difference of middle section is given structure, neighboring area is given the 3rd path difference of structure and neighboring area and is given the spherical aberration that structure is suitably proofreaied and correct first light beam, can suitably carry out recording of information and/or playback to the thickness t 1 of protective substrate.In addition; In the time of on second light beam that has penetrated from red laser diode LD2 has incided thing optical element OBJ; Second path difference that first path difference of middle section is given structure and neighboring area is given structure and is suitably proofreaied and correct and result from difference of wavelength and the spherical aberration of second light beam that takes place of difference and first light beam and second light beam of thickness of protective substrate of BD and DVD; Because neighboring area makes second light beam on the information recording surface of DVD, become flare, so can suitably carry out recording of information and/or playback to the DVD of the thickness t 2 of protective substrate.In addition; When the 3rd light beam that has penetrated from infrared semiconductor laser LD3 has incided thing optical element OL has been gone up; First path difference of middle section is given structure and is suitably proofreaied and correct and result from difference of wavelength and the spherical aberration of the 3rd light beam that takes place of difference and first light beam and the 3rd light beam of thickness of protective substrate of BD and CD; Because second path difference of neighboring area is given structure and neighboring area makes the 3rd light beam on the information recording surface of CD, become flare, so can suitably carry out recording of information and/or playback to the CD of the thickness t 3 of protective substrate.In addition, because first path difference of middle section is given structure the diffraction efficiency of the 3rd light beam that in record reproducing, uses is become well, so can obtain light quantity for sufficient the 3rd light beam of record reproducing.In addition; Second path difference of neighboring area give structure for first light beam and second light beam because of the reason wavelength departure of the foozle of laser instrument etc. during reference wavelength, recoverable chromosphere surface aberration or when temperature variation has taken place, proofread and correct the spherical aberration of following temperature variation and taking place.

[embodiment]

< embodiment 1 >

Secondly, the embodiment that can be used for above-mentioned example is described.In following embodiment, be the plastic lens of the polyolefin series of monolithic to the thing optical element.Giving structure to having formed first path difference on whole of the middle section CN of the optical surface of thing optical element.On whole of the neighboring area of optical surface MD, form second path difference and given structure.On whole of the neighboring area OT of optical surface, form the 3rd path difference and given structure.

In addition, in embodiment 1, first path difference is given structure becomes the structure of having only first foundation structure, schematically as shown in Fig. 2 (a), becomes jagged shape.To become other the light quantity of diffraction light of any number of times (also comprise 0 time, be transmitted light) of light amount ratio of 1 time diffraction light of the 1st light beam big as first basic constructional design of jagged diffraction structure, other the light quantity of diffraction light of any number of times (also comprise 0 time, be transmitted light) of the light amount ratio of 1 time diffraction light of the 2nd light beam is big, other the light quantity of diffraction light of any number of times (also comprise 0 time, be transmitted light) of the light amount ratio of 1 time diffraction light of the 3rd light beam is big.

In embodiment 1, second path difference gives that structure has become second foundation structure overlapping and the structure of the 3rd foundation structure, has become the shape of two kinds of jagged diffraction structures overlapping.To become other any number of times of light amount ratio of 5 times diffraction light of the 1st light beam (also to comprise 0 time as second basic constructional design of bigger jagged diffraction structure; Be transmitted light) the light quantity of diffraction light big; Other any number of times of the light amount ratio of 3 times diffraction light (transmitted light) of the 2nd light beam (also comprises 0 time; Be transmitted light) the light quantity of diffraction light big; Other any number of times of the light amount ratio of the diffraction light of 3 times of the 3rd light beam and 2 times (also comprises 0 time; Be transmitted light) the diffraction light quantity big.To become other the light quantity of diffraction light of any number of times (also comprise 0 time, be transmitted light) of light amount ratio of 2 times diffraction light of the 1st light beam big as the 3rd basic constructional design of less jagged diffraction structure, other the light quantity of diffraction light of any number of times (also comprise 0 time, be transmitted light) of the light amount ratio of 1 time diffraction light (transmitted light) of the 2nd light beam is big, other the diffraction light quantity of any number of times (also comprise 0 time, be transmitted light) of the light amount ratio of 1 time diffraction light of the 3rd light beam is big.

In embodiment 1, the 3rd path difference is given structure becomes the structure of having only second foundation structure, becomes the shape of having only a kind of jagged diffraction structure.

In addition, in embodiment 1, first path difference is given structure, second path difference and is given structure, the 3rd path difference and give on the optical surface that structure all is arranged on light source one side, is plane of refraction to the optical surface of CD one side of thing optical element.In addition, in embodiment 1, limited diverging light incides on the thing optical element a little less than the conduct of the 3rd light beam.

In table 1, represent lens data.Have again, after this, suppose and use E (for example, 2.5E-3) to represent 10 power multiplier (for example, 2.5 * 10 ^-3).

To form the optical surface of thing optical element with respectively in mathematical expression 1 substitution the mathematical expression behind the coefficient represented is stipulated in the table around optical axis axisymmetricly aspheric surface.

[mathematical expression 1]

X (h) = \frac{(h^{2} / r)}{1 + \sqrt{1 - (1 + κ) {(h / r)}^{2}}} + Σ_{i = 0}^{10} A_{2 i} h^{2 i}

At this, X (h) is the axle (direct of travel of light just is decided to be) of optical axis direction, and κ is the circular cone coefficient, A _2iBe the aspheric surface coefficient, h is the height from optical axis.

In addition, the mathematical expression after being updated in the path difference function of mathematical expression 2 with the coefficient of representing in will showing is stipulated the optical path length that the light beam of each wavelength given by diffraction structure.In addition, path difference of the present invention is given the also available following method in addition of structure and is designed, and also available following performance is in addition represented.

[mathematical expression 2]

Φ (h) = \frac{λ}{λ_{B}} \times dor \times Σ_{i = 0}^{6} C_{2 i} h^{2 i}

Wherein, λ is the wavelength of incident beam, and λ B is design wavelength (the photochemical wavelength of shining), and dor is the diffraction number of times, C _2iIt is the coefficient of path difference function.

In Fig. 6 (a), Fig. 6 (b), Fig. 6 (c), the longitudinal spherical aberration figure of expression embodiment 1.1.0 of the longitudinal axis of longitudinal spherical aberration figure, expression NA0.85 or Φ 3.74mm.Have again, in embodiment 1, L=0.036mm.f＝2.311mm。Thereby, L/f=0.036/2.311=0.016.In addition; In embodiment 1; BD with the wavelength change of light beam+situation of 5nm under, the variable quantity of 3 spherical aberrations is-0.134 λ rms, the variable quantity of 5 spherical aberrations is-0.031 λ rms; The variable quantity of 7 spherical aberrations is-0.006 λ rms, and the variable quantity of 9 spherical aberrations is-0.001 λ rms.Thereby, be 0.138 λ rms from the variable quantity of the spherical aberration of 3 times to 9 times totals.In addition; In embodiment 1, use at BD light beam wavelength change+situation of 5nm and change that to make 3 times spherical aberration for the incident multiplying power to first light beam of thing optical element be that SA5 is-0.009 λ rms under 0 the situation; SA7 is 0.009 λ rms, and SA9 is-0.003 λ rms.Thereby δ SAH is 0.013 λ rms, and δ SAH/ δ λ is 0.0026 (λ rms/nm).In addition, using wavelength is 408nm, and the environment temperature in the wavelength characteristic is 25 ℃.

In addition, about the temperature characterisitic to the thing optical element of embodiment 1, δ SAT1 is+rms/ ℃ of 0.0035WFE λ.In addition, because the f ' to the thing optical element under first wavelength is 2.2mm, so δ SAT1/f ' is+0.0016WFE λ rms/ (℃ mm).

[table 1]

< embodiment 2 >

Below, record embodiment 2.

The lens data of expression embodiment 2 in following table 2.In addition, in Fig. 7 (a), Fig. 7 (b), Fig. 7 (c), the longitudinal spherical aberration figure of expression embodiment 2.1.0 of the longitudinal axis of longitudinal spherical aberration figure, expression NA0.85 or Φ 3.74mm.Have again, in embodiment 2, L=0.098mm.f＝2.334mm。Thereby, L/f=0.098/2.334=0.042.In addition; In embodiment 2; BD with the wavelength change of light beam+situation of 5nm under, the variable quantity of 3 spherical aberrations is-0.188 λ rms, the variable quantity of 5 spherical aberrations is-0.021 λ rms; The variable quantity of 7 spherical aberrations is 0.030 λ rms, and the variable quantity of 9 spherical aberrations is-0.016 λ rms.Thereby, be 0.192 λ rms from the variable quantity of the spherical aberration of 3 times to 9 times totals.In addition; In embodiment 2, use at BD light beam wavelength change+situation of 5nm and change that to make 3 times spherical aberration for the incident multiplying power to first light beam of thing optical element be that SA5 is 0 λ rms under 0 the situation; SA7 is 0.037 λ rms, and SA9 is-0.016 λ rms.Thereby δ SAH is 0.042 λ rms, and δ SAH/ δ λ is 0.0084 (λ rms/nm).In addition, using wavelength is 408nm, and the environment temperature in the wavelength characteristic is 25 ℃.

In addition, about the temperature characterisitic to the thing optical element of embodiment 2, δ SAT1 is+rms/ ℃ of 0.0027WFE λ.In addition, because the f ' to the thing optical element under first wavelength is 2.2mm, so δ SAT1/f ' is+0.0012WFE λ rms/ (℃ mm).

[table 2]

< embodiment 3 >

Below, record embodiment 3.With the difference of embodiment 1 be in a part (zone of neighboring area one side) to the part of the neighboring area of the thing optical element zone of one side (neighboring area) and neighboring area overlapping the 7th foundation structure as being used for the 3rd light beam is made the structure that flare makes it disperse far.If change another kind of saying; Then also can make following structures: the inside region that approaches optical axis of giving structure with second path difference has made second foundation structure overlapping and the structure of the 3rd foundation structure; The exterior lateral area of leaving optical axis of comparing with inside region of second path difference being given structure has made the structure of second foundation structure, the 3rd foundation structure and the 7th foundation structure overlapping, and the 3rd path difference is given that inside region that being in of structure approach a side of optical axis has made the 7th foundation structure overlapping and the structure of second foundation structure, will be compared the exterior lateral area that is in a side who more leaves optical axis with the inside region that the 3rd path difference is given structure and make the structure that only is made up of second foundation structure.Have again; In embodiment 3, will become to make other the diffraction light quantity of any number of times of 0 time diffraction light amount ratio of the 1st light beam big as the 7th basic constructional design of the structure of binary shape, other the diffraction light quantity of any number of times of 0 time diffraction light amount ratio of the 2nd light beam is big, the 3rd light beam ± other the diffraction light quantity of any number of times (also comprise 0 time, be transmitted light) of 1 time diffraction light amount ratio is big.

The lens data of expression embodiment 3 in following table 3.In addition, in Fig. 8 (a), Fig. 8 (b), Fig. 8 (c), the longitudinal spherical aberration figure of expression embodiment 3.1.0 of the longitudinal axis of longitudinal spherical aberration figure, expression NA0.85 or Φ 3.74mm.Have again, in embodiment 3, L=0.098mm.f＝2.334mm。Thereby, L/f=0.098/2.334=0.042.In addition; In embodiment 3; BD with the wavelength change of light beam+situation of 5nm under, the variable quantity of 3 spherical aberrations is-0.188 λ rms, the variable quantity of 5 spherical aberrations is-0.021 λ rms; The variable quantity of 7 spherical aberrations is 0.030 λ rms, and the variable quantity of 9 spherical aberrations is-0.016 λ rms.Thereby, be 0.192 λ rms from the variable quantity of the spherical aberration of 3 times to 9 times totals.In addition; In embodiment 3, use at BD light beam wavelength change+situation of 5nm and change that to make 3 times spherical aberration for the incident multiplying power to first light beam of thing optical element be that SA5 is 0 λ rms under 0 the situation; SA7 is 0.037 λ rms, and SA9 is-0.016 λ rms.Thereby δ SAH is 0.042 λ rms, and δ SAH/ δ λ is 0.0084 (λ rms/nm).In addition, using wavelength is 408nm, and the environment temperature in the wavelength characteristic is 25 ℃.

In addition, about the temperature characterisitic to the thing optical element of embodiment 3, δ SAT1 is+rms/ ℃ of 0.0027WFE λ.In addition, because the f ' to the thing optical element under first wavelength is 2.2mm, so δ SAT1/f ' is+0.0012WFE λ rms/ (℃ mm).

[table 3]

The present invention is not limited to the embodiment that puts down in writing in the instructions but comprises other embodiment, variation this point, according to embodiment or the thought put down in writing in this instructions, is conspicuous for the practitioner of this area.The record of instructions and embodiment are purpose all the time with the illustration, scope of the present invention by after claims of stating represent.

Claims

1. an optical take-up apparatus carries out recording of information and/or playback for CD, and this optical take-up apparatus has: first light source that penetrates first light beam of first wavelength X 1; Penetrate the secondary light source of second light beam of second wavelength X 2; Penetrate the 3rd light source of the 3rd light beam of wavelength lambda 3; And to the thing optical element; This is used to make the information recording surface of above-mentioned first beam condenser in the 1st CD of the protective substrate with thickness t 1 to the thing optical element; Make above-mentioned second beam condenser on the information recording surface of the 2nd CD of protective substrate, make above-mentioned the 3rd beam condenser on the information recording surface of the 3rd CD of protective substrate, wherein with thickness t 3 with thickness t 2; λ 2＞λ 1, λ 3＞λ 2, t1≤t2, t2＜t3

The optical surface of above-mentioned light source side to the thing optical element have middle section and above-mentioned middle section around at least two zones of neighboring area, above-mentioned middle section has first path difference and gives structure, above-mentioned neighboring area has second path difference and gives structure,

Above-mentioned first foundation structure be make other the diffraction light quantity of any number of times of 1 time diffraction light amount ratio of first light beam that has passed through first foundation structure big, other the diffraction light quantity of any number of times of 1 time diffraction light amount ratio of second light beam is big, other the big path difference of diffraction light quantity of any number of times of 1 time diffraction light amount ratio of the 3rd light beam is given structure

Above-mentioned set foundation structure be make other the diffraction light quantity of any number of times of x time diffraction light amount ratio of first light beam that has passed through set foundation structure big, other the big path difference of diffraction light quantity of any number of times of y time diffraction light amount ratio of second light beam gives structure, satisfies following formula (8):

0.9·(x·λ1)/(n1-1)≤(y·λ2)/(n2-1)≤1.2·(x·λ1)/(n1-1)

(8)

Wherein, x refers to the integer beyond 0,

Y refers to the integer beyond 0,

2. the optical take-up apparatus described in claim 1 is characterized in that:

3. the optical take-up apparatus described in claim 2 is characterized in that:

With above-mentioned set foundation structure overlapping above-mentioned the 4th foundation structure be make other the diffraction light quantity of any number of times of 3 times diffraction light amount ratio of first light beam that has passed through above-mentioned the 4th foundation structure big, other the diffraction light quantity of any number of times of 2 times diffraction light amount ratio of second light beam is big, other the big path difference of diffraction light quantity of any number of times of the diffraction light amount ratio of 2 times of the 3rd light beam and 1 time is given structure.

4. optical take-up apparatus as claimed in claim 3 is characterized in that:

Above-mentioned is single element lens to the thing optical element.

5. the optical take-up apparatus described in each of claim 1 to 4 is characterized in that:

Above-mentioned is plastic lens to the thing optical element.

6. the optical take-up apparatus described in each of claim 1 to 4 is characterized in that:

Above-mentioned is glass lens to the thing optical element.

7. the optical take-up apparatus described in each of claim 1 to 4 is characterized in that:

The optical surface of above-mentioned light source side to the thing optical element has around above-mentioned neighboring area and has the neighboring area that the 3rd path difference is given structure,

It is the some structures that have second foundation structure, the 3rd foundation structure, the 4th foundation structure or the 5th foundation structure at least that above-mentioned the 3rd path difference is given structure,

Above-mentioned the 3rd path difference give above-mentioned second foundation structure that structure has be make other the diffraction light quantity of any number of times of 5 times diffraction light amount ratio of first light beam that has passed through above-mentioned second foundation structure big, other the diffraction light quantity of any number of times of 3 times diffraction light amount ratio of second light beam is big, other the big path difference of diffraction light quantity of any number of times of the diffraction light amount ratio of 3 times of the 3rd light beam and 2 times is given structure

Above-mentioned the 3rd path difference give above-mentioned the 3rd foundation structure that structure has be make other the diffraction light quantity of any number of times of 2 times diffraction light amount ratio of first light beam that has passed through above-mentioned the 3rd foundation structure big, other the diffraction light quantity of any number of times of 1 time diffraction light amount ratio of second light beam is big, other the big path difference of diffraction light quantity of any number of times of 1 time diffraction light amount ratio of the 3rd light beam is given structure

Above-mentioned the 3rd path difference give above-mentioned the 4th foundation structure that structure has be make other the diffraction light quantity of any number of times of 3 times diffraction light amount ratio of first light beam that has passed through above-mentioned the 4th foundation structure big, other the diffraction light quantity of any number of times of 2 times diffraction light amount ratio of second light beam is big, other the big path difference of diffraction light quantity of any number of times of the diffraction light amount ratio of 2 times of the 3rd light beam and 1 time is given structure

Above-mentioned the 3rd path difference give above-mentioned the 5th foundation structure that structure has be make other the diffraction light quantity of any number of times of 10 times diffraction light amount ratio of first light beam that has passed through above-mentioned the 5th foundation structure big, other the diffraction light quantity of any number of times of 6 times diffraction light amount ratio of second light beam is big, other the big path difference of diffraction light quantity of any number of times of 5 times diffraction light amount ratio of the 3rd light beam is given structure.

8. the optical take-up apparatus described in each of claim 1 to 4 is characterized in that:

The optical surface of above-mentioned light source side to the thing optical element has the neighboring area as plane of refraction around above-mentioned neighboring area,

9. the optical take-up apparatus described in each of claim 1 to 4 is characterized in that:

Above-mentioned to the thing optical element, give and be provided with the 4th path difference on the different optical surface of the optical surface of light source side of structure and give structure with being provided with first path difference,

Above-mentioned the 4th path difference is given the structure that structure is the correcting colour aberration.

10. the optical take-up apparatus described in each of claim 1 to 4 is characterized in that:

Conditional (9), (10) below above-mentioned first wavelength X 1, above-mentioned second wavelength X 2 and above-mentioned wavelength lambda 3 satisfy:

1.5×λ1＜λ2＜1.7×λ1 (9)

1.9×λ1＜λ3＜2.1×λ1 (10)。

11. the optical take-up apparatus described in each of claim 1 to 4 is characterized in that:

12. the optical take-up apparatus described in claim 11 is characterized in that:

13. the optical take-up apparatus described in claim 11 is characterized in that:

Formula below satisfying (1 "):

0.02≤L/f＜0.05 (1”)

Wherein, f refers to the focal length of giving above-mentioned the 3rd light beam of structure, formation first best focal point through above-mentioned first path difference, and its unit is mm, and distance, its unit that L refers between first best focal point and second best focal point are mm,

Above-mentioned first best focal point is to utilize to have passed through above-mentioned above-mentioned first path difference to the thing optical element and give the position of the spot diameter of the luminous point that above-mentioned the 3rd light beam of structure forms for minimum, and above-mentioned second best focal point is that the spot diameter of the luminous point that forms of above-mentioned the 3rd light beam is compared time little position with the spot diameter of the luminous point that forms at above-mentioned the 3rd light beam of above-mentioned first best focal point.

14. one kind to the thing optical element, in optical take-up apparatus, uses, this optical take-up apparatus has: first light source that penetrates first light beam of first wavelength X 1; Penetrate the secondary light source of second light beam of second wavelength X 2; And the 3rd light source that penetrates the 3rd light beam of wavelength lambda 3; Above-mentioned optical take-up apparatus uses above-mentioned first light beam to have the recording of information and/or the playback of the 1st CD of the protective substrate of thickness t 1; Use above-mentioned second light beam to have the recording of information and/or the playback of the 2nd CD of the protective substrate of thickness t 2; Use above-mentioned the 3rd light beam to have the recording of information and/or the playback of the 3rd CD of the protective substrate of thickness t 3; Wherein, λ 2＞λ 1, λ 3＞λ 2, t1≤t2, t2＜t3

0.9·(x·λ1)/(n1-1)≤(y·λ2)/(n2-1)≤1.2·(x·λ1)/(n1-1)

(8)

Wherein, x refers to the integer beyond 0,

Y refers to the integer beyond 0,

15. described in claim 14 to the thing optical element, it is characterized in that:

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

17. as claimed in claim 16 to the thing optical element, it is characterized in that:

Above-mentioned is single element lens to the thing optical element.

18. described in each of claim 14 to 17 to the thing optical element, it is characterized in that:

Above-mentioned is plastic lens to the thing optical element.

19. described in each of claim 14 to 17 to the thing optical element, it is characterized in that:

Above-mentioned is glass lens to the thing optical element.

20. described in each of claim 14 to 17 to the thing optical element, it is characterized in that:

21. described in each of claim 14 to 17 to the thing optical element, it is characterized in that:

22. described in each of claim 14 to 17 to the thing optical element, it is characterized in that:

23. described in each of claim 14 to 17 to the thing optical element, it is characterized in that:

1.5×λ1＜λ2＜1.7×λ1 (9)

1.9×λ1＜λ3＜2.1×λ1 (10)。

24. an optical data recording/reproducing device has optical take-up apparatus, this optical take-up apparatus has: first light source that penetrates first light beam of first wavelength X 1; Penetrate the secondary light source of second light beam of second wavelength X 2; Penetrate the 3rd light source of the 3rd light beam of wavelength lambda 3; And to the thing optical element; This is used to make the information recording surface of above-mentioned first beam condenser in the 1st CD of the protective substrate with thickness t 1 to the thing optical element; Make above-mentioned second beam condenser on the information recording surface of the 2nd CD of protective substrate, make above-mentioned the 3rd beam condenser on the information recording surface of the 3rd CD of protective substrate, wherein with thickness t 3 with thickness t 2; λ 2＞λ 1, λ 3＞λ 2, t1≤t2, t2＜t3

Above-mentioned optical take-up apparatus through make above-mentioned first beam condenser on the information recording surface of above-mentioned the 1st CD, make above-mentioned second beam condenser on the information recording surface of above-mentioned the 2nd CD, make above-mentioned the 3rd beam condenser on the information recording surface of above-mentioned the 3rd CD, carry out recording of information and/or playback, this optical data recording/reproducing device is characterised in that:

0.9·(x·λ1)/(n1-1)≤(y·λ2)/(n2-1)≤1.2·(x·λ1)/(n1-1)

(8)

Wherein, x refers to the integer beyond 0,

Y refers to the integer beyond 0,