CN100456371C

CN100456371C - Recording reproducing optical system, objective lens, and aberration correcting optical element

Info

Publication number: CN100456371C
Application number: CNB2006100753730A
Authority: CN
Inventors: 木村彻; 荒井则一
Original assignee: Konica Minolta Opto Inc
Current assignee: Konica Minolta Inc; Konica Minolta Opto Inc
Priority date: 2002-04-26
Filing date: 2003-04-23
Publication date: 2009-01-28
Anticipated expiration: 2023-04-23
Also published as: CN1848261A

Abstract

The invention discloses an object lens of optical system to record optical information and or regenerate the record, which comprises the following parts: one non-spherical plastic lens in one group with at least one diffraction surface, step-typed diffraction structure with multiple concentric ring-shaped regions on the diffraction surface, wherein the value aperture of optical information record media of lens is not less than 0.8, which satisfies the formulation: f2<f0<f1, wherein the f0 is focal distance (mm) of entire object lens system of beam wavelength from luminous source; the f1 is focal distance of entire object lens system of wavelength difference within short wavelength regulation from luminous source; f2 is focal distance of entire object lens system of wavelength difference within long wavelength regulation from luminous source.

Description

Record regenerating optical system, object lens and light pick-up device

The application is that application number is 03122264.1, the applying date is on April 23rd, 2003, the application people is Konica Corp, denomination of invention dividing an application for the application for a patent for invention of " record regenerating with optical system, object lens and light pick-up device ".

Technical field

The record regenerating that one of the present invention relates to carry out on optical information recording media in recording of information and the regeneration at least is with optical system, object lens, aberration compensation optical element, light pick-up device and record regenerator.

Use the research and development of the new high density optical disc systems of the blue semiconductor laser light source of wavelength 400nm degreeization and the object lens that numerical aperture (NA) is brought up to 0.85 degree to make progress in recent years.On the CD (following be called in this manual " high density DVD ") of NA0.85, use wavelength 400nm, can write down 20～30GB down as an example with the equal size of DVD (NA0.6 uses wavelength 650nm, memory capacity 4.7GB).

As the high NA object lens that are fit to the high density dvd system, the object lens of opening two groups of two formations putting down in writing in the flat 10-123410 communique the spy are known.Though these object lens are by separately making the refracting power of the light of corresponding high NA and optical surface the foozle sensitivity of each lens diminish on four faces, but existence becomes the problem that necessary part increases manufacturing cost because of the operation of assembling each lens, on the viewpoint of manufacturing cost, even in this high density dvd system, also wish as CD system and dvd system object lens are constituted one group one formation.And more hope the object lens that the high density dvd system is used become plastic lens in order to reduce cost.

The inventor has proposed as the plastic objective lens of opening the suitable high density dvd system of the conduct of the object lens the record in the 2001-324673 communique the spy with another inventor.NA be the plastic lens of 0.85 degree when variation of ambient temperature, the variation of the wave-front aberration that takes place because of the variations in refractive index of plastics becomes greatly and become problem on reality is used.In Fig. 1, show wave-front aberration relatively as the situation of the plastic lens temperature variation of one group of formation of NA0.85, focal length 2.5mm, design basis wavelength 405nm as an example.Be not difficult to find out that from Fig. 1 the plastic lens of numerical aperture 0.85 surpasses edge (the マレシヤ Le) limit under the temperature variation of ± 15 ° of degree, so the object lens that can not use as CD player same as before use.

Therefore, on CD player, use the occasion of high NA plastic objective lens, must compensate the variation of temperature variant wave-front aberration by certain means.Present inventor individual proposes to open the such light pick-up device of record in the 2002-082080 communique by way of compensation with the light pick-up device of the wave-front aberration variation of the temperatureization of the plastic objective lens of high NA the spy.

Yet, in this light pick-up device, because essential one side changes by the temperature variant wave-front aberration of photodetector motion ground inspection, the aberration compensation means of the variation that compensates wave-front aberration are moved, so motion ground detects the manufacturing cost increase that the means of temperature variant wave-front aberration variation make the means of aberration compensation means action become necessary part with this testing result of response and cause light pick-up device.

Summary of the invention

The present invention In view of the foregoing proposes, its objective is video disc recording regeneration that a kind of object lens in one group of formation using high NA are provided with compensate the record regenerating optical system that the spherical aberration that changes with objective temperature changes in the optical system, particularly provide a kind of wave-front aberration variation that can not need temperature variant object lens of detection and the record regenerating optical system of low cost manufacturing with moving.

Another object of the present invention provides a kind of light pick-up device of the CD that carries this record regenerating optical system and carries the record regenerator of the CD of this light pick-up device.

Another object of the present invention provides record regenerating that a kind of wave-front aberration that is suitable for compensating with the temperature variation of the plastic objective lens of one group of 1 formation of high NA changes object lens and the aberration compensation optical element with optical system.

In order to achieve the above object, the first record regenerating optical system of the present invention is a kind of record regenerating optical system of carrying out recording of information and regeneration on optical information recording media, comprise: light source, make from the light beam of above-mentioned light source outgoing and focus on object lens on the information recording surface of optical information recording media, and be configured in aberration compensation optical element in the light path between above-mentioned light source and the above-mentioned object lens, it is characterized in that: above-mentioned object lens are at least one one group of plastic lenss that constitute that forms aspheric surface and be formed with the diffraction surfaces with at least one diffraction structure of being made up of a plurality of concentric annular stepped region, above-mentioned aberration compensation optical element has the plastic lens that is formed with the diffraction structure of being made up of a plurality of concentric annular stepped region at least one face, and satisfies following formula (1), (2) and (3).

PD1＞0(1)

PD2＜0(2)

PR2＞0(3)

In the formula:

PD1 is the optical path difference φ that sees through on the wave front of the diffraction structure that forms on the i face of above-mentioned object lens being attached to _Bi(mm) conduct is used by φ apart from the function of the height hi (mm) of optical axis _Bi=hi (b _2iH _i ²+ b _4iH _i ⁴+ b _6iH _i ⁶+ ...) (A)

(at this ni is the diffraction progression with diffraction light of diffraction light efficient maximum in the diffraction light that takes place on the diffraction structure that is being formed on the i face to the optical path difference function representation of definition, b _2i, b _4i, b _6i... be respectively 2 times, 4 times, 6 times ... optical path difference function coefficients (also claiming the diffraction surfaces coefficient)) time, by PD1=∑ (2b _2iNi) Ding Yi diffraction efficiency (mm as diffraction lens ^-1);

PD2 is the optical path difference φ that sees through on the wave front of the diffraction structure that forms on the j face of the plastic lens of above-mentioned aberration compensation optical element being attached to _Bj(mm) as height h apart from optical axis _j(mm) function is used by φ _Bj=n _j(b _2jH _j ²+ b _4jH _j ⁴+ b _6jH _j ⁶+ ...) (B)

Optical path difference function representation (the n in the formula of definition _jBe to be formed on the diffraction progression that has the diffraction light of maximum diffraction optical efficiency in the diffraction light that the diffraction structure on the j face takes place, b _2j, b _4j, b _6i... be respectively 2 times, 4 times, 6 times ... optical path difference function coefficients (also claiming the diffraction surfaces coefficient)) time, by PD2=∑ (2b _2jN _j) definition the diffraction efficiency (mm as diffraction lens ^-1);

PR2 is the refractive index (mm as the refractor of the plastic lens of above-mentioned aberration compensation optical element ^-1).

As everyone knows, because the refractive index of plastic lens rises along with temperature and changes to the direction that diminishes, so when with 1 group of 1 formation plastic lens, spherical aberration changes to the over-compensation direction along with temperature rises.The first record regenerating optical system of the present invention, the aberration compensation optical element of the such plastic lens with positive refractive index of (3) formula is satisfied in configuration at light source and in as the light path between the object lens of one group of plastic lens that constitutes for the variation of offsetting the spherical aberration that is caused by this temperature variation.

Because the refracting power of plastic lens rises and diminishes along with temperature, so the direction variation that (3) formula diminishes to the lateral magnification of object lens is satisfied because of being included in plastic lens the aberration compensation optical element in the inclination angle of (the マ one ジ Na Le) light at the edge of the top of the light beam that penetrates from the aberration compensation optical element.When the lateral magnification of object lens diminishes, because the spherical aberration of under-compensation direction takes place, so can offset the spherical aberration of the object lens that change to the over-compensation direction that cause by variations in refractive index.

, as shown in Figure 1, in the plastic lens of high NA, because the variable quantity of the spherical aberration that is caused by temperature variation is big, so there is the residual danger of variation because of the spherical aberration that can not offset the object lens that cause because of temperature variation fully.Form the diffraction structure that constitutes by a plurality of concentric annular stepped region at this on by at least one face, make its diffraction efficiency satisfy (2) formula as far as possible at the plastic lens of aberration compensation optical element.Can select the inclination angle variable quantity of (マ one ジ Na Le) light of the top edges of the light beam that penetrates from the aberration compensation optical element that causes because of temperature variation whereby arbitrarily.When even the result uses the plastic objective lens of the big high NA of the variable quantity of temperature variant spherical aberration, total diopter unanimity that also can keep the plastic lens of aberration compensation optical element, and because by setting the absolute value of the ratio of total relatively dioptric diffraction efficiency greatly, can obtain desired refractive index, so can just in time offset the variation of the spherical aberration of the object lens that cause because of temperature variation.

In addition, when the aberration compensation optical element has a plurality of plastic lens, PR2 in (3) formula is included in the summation of all plastic lens refractive indexes in the aberration compensation optical element, the aberration compensation optical element constitutes in the mode that is included at least one plastic lens in the plastic lens in the aberration compensation optical element and has at least one diffraction surfaces, and at this moment the PD2 in (2) formula is formed in the summation of the refractive index of all diffraction surfaces on the plastic lens that is included in the aberration compensation optical element.

, when using the such wavelength light source of royal purple optical semiconductor laser, the axial chromatic aberration that produces in optical system becomes problem.The laser that penetrates from semiconductor laser is single wavelength (single mode), generally is considered to not take place axial chromatic aberration, but in fact has the instantaneous situation that mould is beated that causes of counting nm along with drifts such as temperature variation and output variations of centre wavelength.Though because of the beat wavelength change that causes of mould is small for number nm degree, but when using wavelength as the short royal purple photosemiconductor laser of 400nm degree, even because of beating of mould causes wavelength variations is very little, the value that the axial chromatic aberration that causes because of object lens also becomes very big.This is because become very big in the scattering of the wavelength coverage optical material of 400nm.Therefore when using royal purple light partly to lead the device laser instrument as light source, the axial chromatic aberration of compensation optical system in advance.

, because the diffraction efficiency of the plastic lens of aberration compensation optical element satisfies (2) formula, so be not that the occasion of diffraction lens is big by become plastic lens than aberration compensation optical element of the axial chromatic aberration that takes place on the aberration compensation optical element.Therefore when using the such short-wavelength light of royal purple optical semiconductor laser to do, when mould is beated generation, just can lose and keep good optically focused performance.

At this,, make its diffraction efficiency satisfy (1) formula by at least one face of object lens, forming the diffraction structure of forming by a plurality of concentric annular stepped region as far as possible.Whereby because the diffraction structure of the plastic lens by the aberration compensation optical element can be offset the axial chromatic aberration that has increased, often be in axial chromatic aberration and be suppressed very little state so see through aberration compensation optical element and the light beam of object lens focusing on the information recording surface of optical information recording media.

In addition, when the diffraction efficiency of object lens satisfies (1) formula, diminish because only diffraction efficiency is that part of when not forming diffraction structure as the refractive index ratio of the refractor of object lens on object lens, so the variable quantity of the spherical aberration of the object lens that the variations in refractive index during only because of temperature variation causes diminishes.So, because it is also out of question that refractive index to the plastic lens of the necessary aberration compensation optical element of the variation that compensates this spherical aberration is diminished, so that the plastic lens of aberration compensation optical element make easily.

That is to say, if adopt the first record regenerating optical system of the present invention, even then when temperature variation, also can be in the state that spherical aberration is suppressed very for a short time through the light beam on the information recording surface that focuses on optical information recording media behind aberration compensation optical element and the object lens, even and when semiconductor laser light resource generation mould is beated, also can be in the state that axial chromatic aberration is suppressed very for a short time, therefore can often safeguard the good focusing performance.Particularly because do not need the special variation of opening the wave-front aberration of the logistics that motion detection the light pick-up device of being put down in writing in the 2002-082280 communique causes because of temperature variation of picture, so can make the light pick-up device that carries first optical recording usefulness optical system of the present invention at low cost.

According to the above-mentioned first record regenerating optical system, the light of the following wavelength of light emitted 500nm, preferably the numerical aperture of the optical information recording media side of above-mentioned object lens is more than 0.75, and more preferably the numerical aperture of optical information recording media side is more than 0.80.

In addition, with in the optical system, object lens preferably have and satisfy the such wavelength characteristic of following formula (4) at first record regenerating:

f2＜f0＜f1 (4)

In the formula:

F0: the focal length (mm) of the above-mentioned whole objective system when the light wavelength that above-mentioned light source produces,

F1: the focal length (mm) of the above-mentioned whole objective system when the light wavelength that produces than above-mentioned light source has been lacked the wavelength of the wavelength difference of stipulating,

F2: the focal length (mm) of the above-mentioned whole objective system when the light wavelength that produces than above-mentioned light source has been grown the wavelength of the wavelength difference of stipulating.

The connotation of above-mentioned (4) formula is: by the effect of diffraction structure, when the light wavelength on inciding object lens becomes the wavelength difference of having lacked regulation, the back focusing of object lens changes to elongated direction, when the light wavelength on inciding object lens had been grown the wavelength of regulation, the back focal length of object lens changed to the direction that shortens.Therefore can correctly offset the spherical aberration variation of the object lens that cause because of temperature variation by the effect of aberration compensation optical element, and can suppress axial chromatic aberration very little through the light beam on the information recording surface that focuses on optical information recording media behind compensating optical element and the object lens.

Second record regenerating of the present invention is characterised in that with optical system: at least two kinds of light sources that comprise that wavelength is different; with make the optical information recording media that focuses on the object lens on the information recording surface of at least two kinds of different optical information recording medias of the thickness of the protective seam that is used for protecting information recording surface from the light beam of at least two of above-mentioned light source outgoing different wavelength carry out the record regenerating optical system of information record and/or information regeneration; above-mentioned record regenerating has with optical system and is configured in the light source that produces the wavelength light beam in above-mentioned at least two light beams of different wavelengths and the aberration compensation optical element in the light path between the above-mentioned object lens; above-mentioned object lens are that at least one face forms aspheric surface and has one group of plastic lens that constitutes of at least one diffraction surfaces that is formed with the diffraction structure of being made up of a plurality of concentric annular stepped region; the diffraction light of above-mentioned at least two light beams of different wavelengths has in the numerical aperture of the optical information recording media side of information record that carries out above-mentioned two kinds of optical information recording medias and/or the necessary regulation of information regeneration on the information recording surface of separately optical information recording media form the good such wavelength characteristic of wave front at least; above-mentioned aberration compensation optical element has at least one plastic lens that is formed with the diffraction structure of being made up of a plurality of concentric annular stepped region at least one face, and satisfies following formula (5); (6) and (7):

PD1＞0(5)

PD2＜0(6)

PR2＞0(7)

In the formula:

PD1 sees through the optical path difference φ that forms being attached on the wave front of the diffraction structure on the i face of above-mentioned object lens _Bi(mm) as height h apart from optical axis _i(mm) function is used by φ _Bi=ni (b _2IH _i ²+ b _4iH _i ⁴+ b _6iH _i ⁶+ ...) (A)

PD2 is the optical path difference that sees through on the wave front of the diffraction structure that forms on the j face of the plastic lens of above-mentioned aberration compensation optical element being attached to;

φ _Bj(mm) as height h apart from optical axis _j(mm) function is used by φ _Bj=(b _2jH _j ²+ b _4jH _j ⁴+ b _6jH _i ⁶+ ...) definition optical path difference function representation (n in the formula _jBe to be formed on the diffraction progression that has the diffraction light of maximum diffraction optical efficiency in the diffraction light that the diffraction structure on the j face takes place, b _2j, b _4j, b _6j... be respectively 2 times, 4 times, 6 times ... optical path difference function coefficients (also claiming the diffraction surfaces coefficient)) time, by PD2=∑ (2b _2jN _j) definition the diffraction efficiency (mm as diffraction lens ^-1);

PR2: as the refractive index (mm of the refractor of the plastic lens of above-mentioned aberration compensation optical element ^-1);

That is to say; second record regenerating is characterised in that with optical system: the different a plurality of light of each wavelength being made focus on each information recording surface of the different multiple optical information recording media of protective layer thickness the record regenerating that carries out the recording of information regeneration on the different multiple optical information recording media of the thickness of protective seam with object lens with in the optical system, dispose the aberration compensation optical element in the light source of the light of minimal wave length and the first road between the above-mentioned object lens in producing above-mentioned wavelength.

Because be formed on the diffracted beam that diffraction structure on the object lens has the light beam that makes the short wavelength the thin optical information recording media of protective seam is formed the such wavelength characteristic of good wave front; and the diffraction light with the light beam that makes the long wavelength forms the such wavelength characteristic of good wave front to the optical information recording media of protecting bed thickness; because by selectively switching; light wavelength in recording of information regeneration can make the light of wavelength separately focus on separately the information recording surface, regenerates so carry out recording of information with object lens on the different multiple optical information recording media of protective layer thickness.

In addition; the light of the following wavelength of 500nm is to protecting the thinnest optical information recording media in the numerical aperture more than 0.75 in the different multiple optical information recording media of protective layer thickness; by determining diffraction structure; so that becoming in the diffraction limit, the light of the following wavelength of this 500nm focuses on like that, can be with object lens compatible recording regenerative high-density DVD, a DVD and/or CD.

More preferably protective seam optical information recording media focuses on like that to become in the diffraction limit in the numerical aperture more than 0.80 in the different multiple optical information recording media of the relative protective layer thickness of the light of the following wavelength of 500nm.

At this moment the light beam of preferably using as record regenerating at the senior diffraction light that uses on the high density DVD more than 2 grades uses diffraction light than its low progression as the record regenerating light beam on DVD and/or CD.The light of the wavelength coverage separately of the wavelength coverage of the wavelength coverage of high density DVD that whereby can corresponding wavelength 400nm, the DVD of wavelength 650nm and/or the CD wavelength coverage of wavelength 780nm obtains high diffraction efficiency.For example, preferably use second-order diffraction light,, on DVD, use second-order diffraction light using first-order diffraction light on the DVD or on high density DVD, using three diffraction lights at high density DVD in occasion to the object lens of high density DVD and DVD compatibility.Promptly preferably make on high density DVD and use than the only higher leveled diffraction light of DVD.To the occasion of the object lens of high density DVD, DVD and CD compatibility, preferably on high density DVD, use second-order diffraction light in addition, on DVD, use first-order diffraction light, on CD, use three order diffraction light.

And these object lens are plastic lenss of one group of formation, and the diffraction structure that is formed on the object lens has the such diffraction efficiency of satisfied (5) formula.

In addition, the aberration compensation optical element has a plastic lens at least, and the refractive index of plastic lens satisfies (7) formula.Be pre-formed diffraction structure at least one face of this plastic lens, its diffraction efficiency satisfies (6) formula.

That is to say, in the second record regenerating optical system of the present invention, when high density DVD is carried out the information record regenerating, by with first record regenerating with the same action effect of optical system, even the light beam that sees through the minimal wave length on the information recording surface that focuses on optical information recording media behind aberration compensation optical element and the object lens is when temperature variation, also can be in the state that spherical aberration is suppressed very for a short time, even and when semiconductor laser light resource generation mould is beated, also be in axial chromatic aberration and be suppressed in very little state, so can often keep the good focusing performance of energy to high density DVD, thereby high density DVD is stably carried out recording of information regeneration.

With in the optical system, preferably, object lens have and satisfy the such wavelength characteristic of following formula (8) at second record regenerating.

f2＜f0＜f1 (8)

In the formula:

F0: the focal length of the above-mentioned whole objective system of minimal wave length (mm) in the light beam of above-mentioned at least two different wavelength,

F1: the focal length (mm) of the above-mentioned whole objective system when the shortest wavelength has been lacked the wavelength of wavelength difference of regulation in than above-mentioned at least two different wave lengths,

F2: the focal length (mm) of the above-mentioned whole objective system when the wavelength of the wavelength difference of having grown regulation at least than the shortest wavelength in above-mentioned two different wavelength light beams.

The connotation of above-mentioned (8) formula is: by the effect of diffraction structure, when minimal wave length becomes the wavelength difference of having lacked regulation, the back focusing of object lens changes to elongated direction, and only during the wavelength of elongated regulation, the back focal length of object lens changes to the direction that shortens in the light wavelength of minimal wave length.Therefore, when carrying out the information record regenerating of high density DVD, the spherical aberration that can correctly offset the object lens that cause because of temperature variation by the effect of aberration compensation optical element changes, and can suppress the axial chromatic aberration through the light beam on the information recording surface that focuses on optical information recording media behind compensating optical element and the object lens very little.

With in the optical system, for the such wavelength characteristic that makes object lens have satisfied (4) formula or (8) formula, and preferably determine diffraction structure, at above-mentioned first and second record regeneratings so that the diffraction efficiency of object lens satisfies following formula (9).

0.05＜PD1/PT1＜0.7(9)

PT1: the diopter (mm of above-mentioned whole objective system ^-1).

Because more than the lower limit of above-mentioned (9) formula, the diopter of the whole relatively objective system of diffraction efficiency is not undue deficiency, do not become under-compensation so that satisfy the aberration compensation optical element and the fashionable axial chromatic aberration of objective lens of (2) formula or (6) formula.And because below the upper limit of (9) formula, it is too surplus that the diopter of whole relatively objective system does not become diffraction efficiency, and institute is not so that the aberration compensation optical element and the fashionable axial chromatic aberration of objective lens of satisfied (2) formula or (6) formula become over-compensation.

Use in the optical system at record regenerating of the present invention, at least one diffraction is spaced apart pf (mm) at the ring-shaped area with optical axis vertical direction above-mentioned diffraction surfaces maximum numerical aperture of optical information recording media side in the diffraction surfaces of establishing object lens, if when the ring-shaped area with optical axis vertical direction above-mentioned diffraction surfaces during half numerical aperture of the maximum numerical aperture of the optical information recording media side of above-mentioned object lens is spaced apart ph (mm), preferably satisfy following formula (11).

1＜|(ph/pf)-2|＜10(11)

Above-mentioned (11) formula is the condition that the spherical aberration variable quantity when being used to make the light wavelength that is incident on the object lens to change by diffraction becomes desired value., be preferably in when the light wavelength that is incident on the object lens changes and determine diffraction structure, with in the object lens of optical system at record regenerating of the present invention so that satisfy following any occasion.

The first, even the light wavelength that is incident on the object lens changes, also be the almost indeclinable occasion of spherical aberration of object lens.Whereby, because can use the light source that causes the oscillation wavelength skew because of foozle, thus cancelled the part of essential selection light source, thus the record regenerating optical system can be made at low cost.

The second, when the light wavelength on being incident on object lens is elongated, be the occasion of the spherical aberration of object lens to the variation of under-compensation direction.The light generation mould of semiconductor laser light source rises along with temperature and changes, and oscillation wavelength changes to the long wave side.In addition, because the refractive index of plastic lens rises and diminishes along with temperature in the plastic lens of one group of formation, so spherical aberration changes to the over-compensation direction.That is to say because diffraction, when the light wavelength on being incident on object lens is elongated, because the spherical aberration of object lens changes to the under-compensation direction as far as possible, and the variation of the variation of the spherical aberration that the wavelength variations can offset because of temperature variation the time causes and the spherical aberration that causes because of variations in refractive index.So, because it is also no problem that the variable quantity of the spherical aberration of the object lens monomer that causes because of temperature variation is diminished.So the diffraction efficiency and/or the refractive index of aberration compensation optical element diminish.Thereby make and resembling compensating optical element and make easily.

With in the optical system, the lens thickness on the optical axis of establishing object lens is d (mm), when focal length is f (mm), preferably satisfies following formula (12) at record regenerating of the present invention.

0.8≤d/f≤2.4(12)

Above-mentioned (12) formula is to be used to obtain sufficient edge thickness, the condition of operating distance and good image height characteristic fully in the high NA plastic lens of 1 group of 1 formation.

More than the lower limit of (12) formula, because of edge thickness thin shaping easily within reason.And do not become undue big in the locational gaze angle of aspheric maximum effective diameter (angle of aspheric normal and optical axis) because of beam incident surface, institute is so that Mould Machining is accurate.Below the upper limit of (12) formula, big because undue change does not take place the astigmatism composition of the wave-front aberration of the light beam that tilts when going into to inject on the object lens, so can obtain the good object lens of image height characteristic.In addition, because the lens thickness on the optical axis does not become undue thick, thus the weight of object lens is lightened, and can guarantee sufficient operating distance.In addition, be that the f in (12) formula becomes the focal length of the whole objective system on minimal wave length under the occasion of tree thing of different multiple optical information recording medium compatibilities to protective layer thickness at object lens.

With in the optical system, preferably, the lateral magnification M of object lens monomer satisfies (10) formula at record regenerating of the present invention.More preferably, the lateral magnification M of object lens monomer satisfies (13) formula

0＜M＜1(10)

0＜M＜0.25(13)

Since compensate object lens in advance, so that the converging beam aberration from virtual object point is become minimum, so the parallel beam aberration that the variation of the spherical aberration that is caused by temperature variation is compared from infintie object point becomes under minimum such compensation occasion little.Whereby, because alleviated the burden of the aberration compensation optical element when the variation of offsetting because of the spherical aberration of the object lens of temperature variation, so reduced the diffraction efficiency and/or the refractive index of aberration compensation optical element.The result makes the aberration compensation optical element easy to manufacture.

In addition; at object lens are object lens occasions to the different multiple optic informating recording medium compatibility of the thickness of protective seam, the lateral magnification of the object lens monomer the when M in (10) formula is an information record regenerating on the thinnest optical information recording media of the protective seam that carrying out.The lateral magnification of the lateral magnification of the object lens monomer when at this moment carrying out the information record regenerating on the thinnest optical information recording media of protective seam and the object lens monomer when protecting information record regenerating on the optical information recording media of bed thickness both can equate, also can be different.

In addition, in the occasion of the lateral magnification that satisfies the object lens monomer (10) formula, record regenerating of the present invention is preferably in optical system has the coupled lens that is used for be transformed into converging beam from the divergent beams of light source in the light path between light source and the object lens.This coupled lens both can be and the same optical element of aberration compensation optical element, also can be another optical element separately, but from reducing record regenerating with the part count of optical system and the preferably same optical element of viewpoint that reduces cost.And on any in diffraction limit of converging beam best-focus by coupled lens.

Use in the optical system at record regenerating of the present invention, the compensation that changes in the object lens spherical aberration that causes because of temperature variation and the occasion of the compensation compatibility of the axial chromatic aberration of optical system, the interval of the direction that the optical axis of the diffraction ring-shaped area adjacent with object lens is vertical (the following ring-shaped area spacing that is called in this manual) is several μ m degree.When ring-shaped area spacing hour, the influence that the diffraction efficiency that the foozle that is formed by diffraction wheel band is caused descends becomes big, so existence can not obtain the worry of enough light utilization ratios.In addition, be 10 times of degree when following when the ring-shaped area spacing becomes wavelength, just become and can not ignore the influence that the diffraction efficiency to the polarization direction that is incident on the light on the diffraction structure descends, the theoretical value of diffraction efficiency becomes littler than 100%.At this, in order to relax the ring-shaped area spacing of object lens, and preferably by forming the diffraction structure of ring-shaped area on the two sides of object lens, the two sides by object lens is distributed in diffraction efficiency on two diffraction surfaces as diffraction surfaces, comes slow ring-shaped area gap of closing each diffraction surfaces.

In addition, because relax the ring-shaped area spacing of object lens, so that in the diffraction light that takes place by the diffraction structure of object lens more than the secondary senior diffraction light have maximum diffraction light efficient, the light beam that the most handy this senior diffraction light is used as the record regenerating of optical information recording media as far as possible.For example when the light beam of using as record regenerating with second-order diffraction light, and use the first-order diffraction light time to compare, can make the ring-shaped area spacing become 2 times.When becoming to diffraction surfaces on two sides with object lens, also can have maximum diffraction light efficient in order to make the senior diffraction light more than the secondary, and determine the diffraction structure of any one diffraction surfaces, but preferably have maximum amount and determine diffraction structure on two faces in order to make at the senior diffraction light on two diffraction surfaces.

In this manual; so-called in order to make senior diffraction light more than the secondary have spreading out light quantity and determine that the connotation of diffraction structure is the most as far as possible: at the ladder amount d (mm) of the optical axis direction that is parallel near the diffraction ring-shaped area the optical axis; integer m more than 2; be used for carrying out the light wavelength λ (mm) of information record regenerating (is that the multiple optical information recording media different to protective layer thickness is that compatible occasion is the light wavelength that is used for carrying out the information record regenerating on the thinnest optical information recording media of protective seam in the record regenerating optical system) on the optical information recording media, and the refractive index N λ of the object lens of wavelength X between set up

D=m λ/N λ-1) relation.

In addition, the diffraction structure that is formed on the object lens face has the structure of the jagged diffraction grating that glitters, and above-mentioned blazed diffraction grating structure preferably uses the electron beam scanning technique to make, or passes through the mould-forming making with the mould of electron beam scanning technique making.

As reduce technology that shape error makes fine blazed diffraction grating to the resist layer on the lens substrate in the control exposure after the irradiating electron beam, the technology that makes the Thickness Variation of resist layer form the blazed diffraction grating structure by development treatment is known, make by this electron beam scanning fabrication techniques or of die forming by the electron beam scanning fabrication techniques, even the object lens that diminish of ring-shaped area also can carry out shape error and make often littlely.

With in the optical system, the aberration compensation optical element can constitute by being used for the coupled lens of conversion from the divergent beams of light source at record regenerating of the present invention.At object lens are occasions to the object lens of the different multiple optical information recording media compatibility of the thickness of protective seam, can be made of the coupled lens of conversion from the divergent beams of the light source of the light that produces minimal wave length.And coupled lens has at least one plastic lens of the refractive index of satisfied (3) formula or (7) formula, and this plastic lens has at least one diffraction surfaces, and the summation of the diffraction efficiency of diffraction surfaces satisfies (2) formula or (6) formula.

Coupled lens also can be the lens that (1) is transformed into the divergent beams from light source the smaller divergent beams of the angle of divergence, also can be (2) be transformed into the collimation lens of substantially parallel light beam to the divergent beams from light source, also can be the lens that are transformed into converging beam from the divergent beams of light source.Occasion in (1), because the refractive index of coupled lens is little, institute is so that coupled lens is easy to manufacture.Occasion in (2) is not because the object point position of object lens changes with focussing force, so can obtain the good focusing characteristic.And in the occasion of (3) because the variation of the spherical aberration that is caused by temperature variation is littler than the occasion of (1) and (2), and because the coupled lens burden of the spherical aberration that causes in the temperature variation of offsetting because of object lens when changing, institute so that coupled lens make easily.

Coupled lens as the aberration compensation optical element also can be made of a plurality of lens, but from reducing record regenerating with on the components number of optical system and the viewpoint that reduces cost, preferably the plastic lens of one group of formation.And at this moment, the numerical aperture of the light source side of coupled lens is preferably in more than 0.15 below 0.50, whereby, because the variations in refractive index in the time of guaranteeing because of temperature variation cause from the inclination angle amount of (the マ one ジ Na Le) light at the edge of the outgoing beam of coupled lens enough greatly, so the compensation of the spherical aberration of the thing ball during to temperature variation is favourable.

With in the optical system, the aberration compensation optical element can be made of positive lens groups and negative lens group two groups at record regenerating of the present invention.At this moment, record regenerating has with optical system and is used for the coupled lens of conversion from the light source divergent beams, and the aberration compensation optical element is configured in the light path between this coupled lens and the object lens.At object lens are occasions to the object lens of the different multiple optical information recording media compatibility of protective layer thickness, and the aberration compensation optical element is used for conversion and constitutes from the coupled lens of the divergent beams of the light source that produces the shortest light of wavelength and the positive lens groups of the light path between the object lens and two groups of negative lens group by being configured in.Have in the parallel beam that for example is configured in collimation lens and object lens and by two groups of optical beam expanders that constitute of positive lens groups and negative lens group as aberration compensation optical element with such form.At this moment because can make the light beam between collimation lens and the aberration compensation optical element often remain parallel beam when collimation lens become glass lens, so dispose beam shaping prism but desirable because of easy.And the aberration compensation optical element comprises at least 1 plastic lens of the diffraction efficiency with satisfied (3) formula or (7) formula, and this plastic lens has at least one diffraction surfaces, and the summation of the diffraction efficiency of diffraction surfaces satisfies (2) formula or (6) formula.

In addition, also can constitute, but use on this viewpoint of component count of optical system, preferably two groups of two formations from reducing record regenerating by a plurality of lens by positive lens groups and two groups of aberration compensation optical elements that constitute of negative lens group.And from the viewpoint that the reduces cost plastic lens of two groups of two formations preferably.

Do not become undue little for the ring-shaped area spacing of the diffraction structure that makes the aberration compensation optical element in addition, and the said lens group is the plastic lens that is formed with at least one face by the diffraction structure of a plurality of concentric annular stepped region, and the above-mentioned negative lens group glass lens littler than the plastic lens of above-mentioned positive lens groups that be Abbe number, when the focal length of establishing above-mentioned just saturating group is that the focal length of fp (mm), above-mentioned negative lens group is f _N(mm) time, preferably satisfy following formula (14)

1.2≤|fp/f _N|≤2.4(14)

Making positive lens like this is the plastic lens with at least one diffraction surfaces, negative lens is a glass lens, variations in refractive index when satisfying the such formation of above-mentioned (14) formula and can guarantee because of temperature variation by having is drawn, and to go out the variable quantity at inclination angle of (マ one ジ Na Le) light at edge of light beam from the aberration compensation optical element enough big, thereby can delay the ring-shaped area spacing of the diffraction structure that closes the aberration compensation optical element.And at this moment more preferably select the big negative glass lens of glass material conduct of Abbe number, thereby the aberration that the axle look with optical system is produced is suppressed to very little favourable than the plastic lens of positive lens.

With in the optical system, the aberration compensation optical element can be used for conversion and constitutes from the coupled lens of the divergent beams of light source and one group of plastic lens that constitutes of the light path between the object lens by being configured at record of the present invention.At object lens are object lens occasions to the different multiple optical information recording media compatibility of the thickness of protective seam, are configured in as the plastic lens of one group of formation of aberration compensation optical element to be used for conversion from the coupled lens of the diverging light of the light source that produces the shortest wavelength light of wavelength and the light path between the object lens.Have the refractive index of satisfied (3) formula or (7) formula as the plastic lens of aberration compensation optical element, the summation of the diffraction efficiency of diffraction surfaces satisfies (2) formula or (6) formula simultaneously.Thereby can obtain one group one the so very simple aberration compensation optical element that constitutes.Particularly make the absolute value of refractive index of aberration compensation optical element identical with the absolute value of the refractive index of diffraction efficiency, and preferably when the symbol of these two values when being opposite mutually, because the system-wide diopter of aberration compensation optical element becomes 0, so this aberration compensation optical element is configured in the parallel beam easily.

In addition, use in the optical system at record regenerating of the present invention, preferably on the plastic lens of aberration compensation optical element, form plural diffraction surfaces, diffraction efficiency is distributed on a plurality of diffraction surfaces, can relax the ring-shaped area gap of each diffraction surfaces whereby, thereby the influence that the refractive index that the foozle because of the diffraction ring-shaped area is caused descends diminishes.

In addition, the senior diffraction light more than 2 grades has maximum diffraction light efficient in the diffracted ray that diffraction structure at the plastic lens of aberration compensation optical element produces for the ring-shaped area face of the plastic lens that relaxes the aberration compensation optical element also can make as far as possible, and this senior diffraction light is incident on the object lens as far as possible.For example be incident on occasion on the object lens at 2 order diffraction light, can make the ring-shaped area spacing is 2 times of occasion of a diffraction light.

In addition, use in the optical system at record regenerating of the present invention, diffraction structure with the structure that glitters of the such diffraction efficiency of satisfied (2) formula or (6) formula, preferably be formed on the convex surface as macroscopic view, because compare with the occasion that forms diffraction structure on as the plane of macroscopic view or concave surface, can make the drift angle that glitters become big, so when making this of the mould-forming of mould and glitter structure, even also transfer printing is correctly constructed in trickle glittering.In addition in this manual, the shape of so-called face " protruding (the recessed or plane) of macroscopic view " is identical with the connotation of " envelope of the end of each ring-shaped area ladder is protruding (recessed or plane) ".

In addition, use in the optical system at record regenerating of the present invention, by the Chromatically compensated optical element that configuration in the light path between light source and object lens is made of glass, can make the compensation record regenerating with the function branch of the axial chromatic aberration of optical system at Chromatically compensated optical element be formed on the diffraction structure on the object lens.Whereby, mend with the occasion of optical element for a short time, and can delay the ring-shaped area spacing of compound mirror because of the refractive index ratio that can make object lens does not dispose aberration in optical system at record regenerating.The result diminishes the decline of the refractive index that the foozle because of the diffraction ring-shaped area causes, and can obtain the high object lens of light utilization efficiency.As so Chromatically compensated optical element Chromatically compensated optical element of doublet type that the negative lens by the positive lens of the big relatively Abbe number of mutual neighbor configuration and relative little Abbe number constitutes and one group one the Chromatically compensated optical element of the diffraction type that constitutes that forms the derivative structure with positive diffraction efficiency are for example arranged.Both can constitute the record regenerating optical system, so that these Chromatically compensated optical elements are included in the aberration compensation optical element, also can constitute the record regenerating optical system, so that these Chromatically compensated optical elements are not included in the above-mentioned aberration compensation optical element.

The light pick-up device of optical information recording media of the present invention is characterised in that, it is to comprise at least: light source, make from the light beam of above-mentioned light source outgoing to focus on the Focused Optical system on the information recording surface of optical information recording media and receive the light pick-up device of optical information recording media of photodetector of being exported the electric signal of this light quantity of response by above-mentioned information recording surface beam reflected then, above-mentioned light-gathering optics is the record regenerating optical system of above-mentioned optical information recording media.

In addition, record regenerator of the present invention can carry out the regeneration of sound and/or record images and/or sound and/or image by carrying above-mentioned light pick-up device.

In addition, in this manual, so-called aberration compensation optical element is the optical element in the light path that is configured between the plastic objective lens of light source and one group of formation, is that what is called can make and sees through at the relative optical element that sees through in the wave-front aberration amount minimizing of the wave front of one group one the formation plastic objective lens of temperature when the temperature of afore mentioned rules only changes the temperature difference of afore mentioned rules with the wave-front aberration amount of the wave front of the plastic objective lens of one group of formation of the optical element of temperature when the temperature of regulation only changes the temperature difference of regulation.

In addition, so-called in this manual Chromatically compensated optical element is the optical element in the light path that is configured between the plastic objective lens of light source and one group of formation, is that what is called can make wavelength only change the different light transmission optical element of wavelength of the wavelength difference of regulation from the wavelength of regulation, the axial chromatic aberration of the aberration compensation optical element and the wave front of the plastic objective lens of one group of formation makes wavelength only change the different light transmission aberration compensation optical element of wavelength of the wavelength difference of regulation from the wavelength of afore mentioned rules relatively, the optical element that diminishes with axial chromatic aberration on the wave front of the plastic objective lens of one group of formation.

In addition, so-called in this manual " optical element that is called A is included in the optical element that is called B " though be with the optical element that is called A, be called B the transmission wave-front aberration separately of optical element bigger than the edge limit, the connotation that both wave-front aberration of wave front of the optical element that see through the optical element that is called A, is called B is in the scope of M is identical.And so-called " optical element that is called A is not included in the optical element that is called B " or " optical element that is called A separates with the optics that is called B " another optical element are identical with the connotation that the transmission wave-front aberration separately that is called the optical element of B is in the edge limit with the optical element that is called A.

In addition, in this manual, (optics) face that what is called is formed with diffraction surfaces or diffraction structure is meant and for example is being provided with on the face of lens concavo-convexly on the surface of optical element, makes it have the face that makes the incident beam diffraction.Zone that produces diffraction and the occasion that does not produce diffraction region are arranged on same optical surface, be meant the zone that produces diffraction.So-called in addition diffraction structure or diffraction image are meant the zone that produces this diffraction, for example on the surface of optical element being the center with the optical axis as concavo-convex shape forms as the ring-shaped area of concentric circles roughly, if and only see this section on the plane of optical axis containing, though then each ring-shaped area is considered to zigzag or stepped such shape, comprise the structure of such shape.

In addition, in this manual, so-called recording of information and regeneration are meant in recorded information on the information recording surface of optical information recording media as described above and regeneration and have been recorded in information on the information recording surface.Record regenerating of the present invention both can be only to be used to carry out record or only in the optical system of regeneration with optical system, also can be to be used to write down and both optical system of regenerating.And also can be to be used for certain optical information recording media is carried out record, and be used for optical system that another optical information recording media is regenerated, also can be to be used for certain optical information recording media is write down or regenerates, and be used for optical system that another optical information recording media is write down and regenerates.Be to comprise the meaning of sense information simply in this so-called regeneration in addition.

Description of drawings

Fig. 1 represents the figure of the temperature variant state of wave-front aberration of plastic lens of one group of formation of NA0.85 of the prior art, focal length 2.2mm, design basis wavelength 405nm.

The figure of the record regenerating of first embodiment with first light pick-up device formation of optical system represented to carry in Fig. 2 summary.

Fig. 3 is that the figure of the record regenerating of second embodiment with second light pick-up device formation of optical system represented to carry in summary.

Fig. 4 is the index path of the record regenerating of embodiment 1 with optical system.

Fig. 5 be illustrated in embodiment 1 the one-piece type collimation lens of diffraction when wavelength 405 ± 5nm spherical aberration and the curve of axial chromatic aberration.

Fig. 6 be illustrated in embodiment 1 the one-piece type object lens of diffraction when wavelength 405 ± 5nm spherical aberration and the curve of axial chromatic aberration.

Fig. 7 be the record regenerating that is illustrated in the one-piece type object lens combination of the one-piece type collimation lens of the diffraction that makes embodiment 1 and diffraction with optical system when wavelength 405 ± 5nm spherical aberration and the curve of axial chromatic aberration.

Fig. 8 is the figure of the record regenerating of expression embodiment 1 with the temperature characterisitic of optical system.

Fig. 9 is the figure of the record regenerating of expression embodiment 1 with the wavelength characteristic of optical system.

Figure 10 is the index path of the record regenerating of expression embodiment 2 with optical system.

Figure 11 be illustrated in embodiment 2 the one-piece type object lens of diffraction when wavelength 405 ± 5nm spherical aberration and the curve of axial chromatic aberration.

Figure 12 be the record regenerating that is illustrated in the diffraction integrated type optical beam expander that makes embodiment 2 and the one-piece type object lens combination of diffraction with light-source system when wavelength 405 ± 5nm spherical aberration and the curve of axial chromatic aberration.

Figure 13 is the figure of the record regenerating of expression embodiment 2 with the temperature characterisitic of optical system.

Figure 14 is the figure of the record regenerating of expression embodiment 2 with the wavelength characteristic of optical system.

Figure 15 is the index path of the record regenerating of expression embodiment 3 with optical system.

Figure 16 be illustrated in embodiment 3 the one-piece type object lens of diffraction when wavelength 405 ± 5nm spherical aberration and the curve of axial chromatic aberration.

Figure 17 be the record regenerating that is illustrated in the diffraction integrated type optical beam expander that makes embodiment 3 and the one-piece type object lens combination of diffraction with optical system when wavelength 405 ± 5nm spherical aberration and the curve of aberration.

Figure 18 is the figure of the record regenerating of expression embodiment 3 with the temperature characterisitic of optical system.

Figure 19 is the figure of the record regenerating of expression embodiment 3 with the wavelength characteristic of optical system.

Figure 20 is the index path of the record regenerating of expression embodiment 4 with optical system.

Figure 21 be the expression embodiment 4 the one-piece type object lens of diffraction when wavelength 405 ± 5nm spherical aberration and the curve of axial chromatic aberration.

Figure 22 be the expression aberration compensation optical element that makes embodiment 4 with the record regenerating usefulness optical system of the one-piece type object lens combination of diffraction when wavelength 405 ± 5nm spherical aberration and the curve of axial chromatic aberration.

Figure 23 is the figure of the record regenerating of expression embodiment 4 with the temperature characterisitic of optical system.

Figure 24 is the figure of the record regenerating of expression embodiment 4 with the wavelength characteristic of optical system.

Figure 25 is the index path of the record regenerating of expression embodiment 5 with optical system.

Figure 26 be illustrated in embodiment 5 the one-piece type coupled lens of diffraction when wavelength 405 ± 5nm spherical aberration and the curve of axial chromatic aberration.

Figure 27 be illustrated in embodiment 5 the one-piece type object lens of diffraction when wavelength 405 ± 5nm spherical aberration and the curve of axial chromatic aberration.

Figure 28 be the record regenerating usefulness optical system of the one-piece type object lens combination of the one-piece type coupled lens of diffraction and the diffraction of expression embodiment 5 when wavelength 405 ± 5nm spherical aberration and the curve of axial chromatic aberration.

Figure 29 is the figure of the record regenerating of expression embodiment 5 with the temperature characterisitic of optical system.

Figure 30 is the figure of the record regenerating of expression embodiment 5 with the wavelength characteristic of optical system.

Figure 31 is the index path of the record regenerating of expression embodiment 6 with optical system.

Figure 32 be illustrated in the one-piece type object lens combination of the one-piece type collimation lens of the diffraction that makes embodiment 6 and diffraction optical system when wavelength 405 ± 5nm spherical aberration and the curve of axial chromatic aberration.

Figure 33 be the record regenerating that is illustrated in the combination of the one-piece type object lens of the one-piece type collimation lens of the diffraction that makes embodiment 6, maqting type double lens and diffraction with optical system when wavelength 405 ± 5nm spherical aberration and the curve of axial chromatic aberration.

Figure 34 is the figure of the record regenerating of expression embodiment 6 with the temperature characterisitic of optical system.

Figure 35 is the figure of the record regenerating of expression embodiment 6 with the wavelength characteristic of optical system.

Figure 36 is the index path that is illustrated among the embodiment 7 when the information of high density DVD carried out record regenerating.

Figure 37 is the index path that is illustrated among the embodiment 7 when the information of DVD carried out record regenerating.

Figure 38 is the index path when in embodiment 7 information of CD being carried out record regenerating.

Figure 39 be illustrated in embodiment 7 the one-piece type collimation lens of diffraction when wavelength 405 ± 5nm spherical aberration and the curve of axial chromatic aberration.

Figure 40 be illustrated in embodiment 7 the one-piece type object lens of diffraction when wavelength 405 ± 5nm spherical aberration and the curve of axial chromatic aberration.

Figure 41 is the curve of the spherical aberration of the one-piece type object lens of diffraction when wavelength 650nm of expression embodiment 7.

Figure 42 is the curve that is illustrated in the spherical aberration of the one-piece type object lens of diffraction when wavelength 780nm of embodiment 7.

Figure 43 be record regenerating in the one-piece type object lens combination of the aberration compensation optical element that makes Fig. 7 and diffraction with optical system the spherical aberration during at wavelength 405 ± 5nm and the curve of axial chromatic aberration.

Figure 44 is the figure of the record regenerating of expression embodiment 7 with the temperature characterisitic of optical system.

Figure 45 is the figure of the record regenerating of expression embodiment 7 with the wavelength characteristic of optical system.

Figure 46 is that the figure of the record regenerating of the 3rd embodiment with the 3rd light pick-up device formation of optical system represented to carry in summary.

Figure 47 is the figure of the temperature characterisitic of record regenerating when with optical system the information of high density DVD being carried out record regenerating of expression embodiment 8.

Figure 48 is the figure of the temperature characterisitic of record regenerating when with optical system the information of DVD being carried out record regenerating of expression embodiment 8.

Figure 49 is the figure of the wavelength characteristic of record regenerating when with optical system the information of high density DVD being carried out record regenerating of expression embodiment 8.

Figure 50 is the figure of the wavelength characteristic of record regenerating when with optical system the information of DVD being carried out record regenerating of expression embodiment 8.

Embodiment

First, second and the 3rd embodiment of the present invention are described with reference to the accompanying drawings.

(first embodiment)

Fig. 2 is that the figure of the record regenerating of first embodiment with first light pick-up device formation of optical system represented to carry in summary.The light pick-up device 1 of Fig. 2 comprises: as one-piece type coupled lens 13 of semiconductor laser 11, the diffraction of light source and the one-piece type object lens 15 of diffraction.

Semiconductor laser 11 is that the GaN of the light beam of ejaculation wavelength 400nm degree is a bluish violet light laser.In addition, as the light source of the light beam of the degree that penetrates wavelength 400nm,, also can be the SHG bluish violet light laser that utilizes second harmonic except above-mentioned GaN is the bluish violet light laser.

The one-piece type coupled lens 11 of diffraction is the divergent beams of semiconductor laser 11 to be transformed into the collimation lens of the parallel light beam of relative optical axis, and is plastic lens.Also can become smaller lens and make the lens that are transformed into converging beam from the divergent beams of semiconductor laser as the one-piece type coupled lens 13 of diffraction in addition with the angle of divergence that makes from the divergent beams of semiconductor laser 11.

In addition, the roughly diffraction pattern of concentric circles is set on the face of one-piece type object lens 15 sides of the diffraction of the one-piece type coupled lens 13 of diffraction.Determine the diffraction pattern of the one-piece type coupled lens 13 of diffraction, so that satisfy above-mentioned (2) formula.Roughly the diffraction pattern of circular concentric also can be arranged on the face of semiconductor laser 11 sides of the one-piece type coupled lens 13 of diffraction in addition, also can be arranged on the face of semiconductor laser 11 sides and both of the face of diffraction one object lens 15 sides on.Though the relative optical axis of diffraction pattern of the one-piece type coupled lens 13 of diffraction forms roughly concentric circles in addition, and the diffraction pattern except that concentric circles also can be set.

The one-piece type object lens 15 of diffraction be the protective seam 16 of the light beam of the one-piece type coupled lens of the self-diffraction in the future CD 16 of employing by high-density recording at the lens of range of diffraction inner focusing under information recording surface 16b, the numerical aperture of CD 16 sides is more than 0.75.

The one-piece type object lens 15 of diffraction are aspherical plastic lenses of one group of formation, and the roughly diffraction pattern of concentric circles is set on the face of one-piece type coupled lens 13 sides of the diffraction of the one-piece type object lens 15 of diffraction.The diffraction image of the one-piece type object lens 15 of diffraction is determined according to the requirement of satisfying above-mentioned (1) formula, (4) formula, (9) formula and (11) formula.And the lens thickness of the one-piece type object lens 15 of diffraction on its optical axis determined according to the requirement of satisfying (12) formula on the following formula.

In addition, roughly the diffraction pattern of concentric circles both can be arranged on the face of one-piece type coupled lens 13 sides of diffraction of the one-piece type object lens 15 of diffraction, also can be provided with on both of face of the face of one-piece type coupled lens 13 sides of diffraction and CD 16 sides.Though the relative optical axis of diffraction pattern of the one-piece type object lens 15 of diffraction forms roughly concentric circles in addition, roughly concentric circles diffraction pattern in addition can be set also.

In addition, the one-piece type object lens 15 of diffraction have vertically extending of relative optical axis, and flange part 50 is arranged, thereby can utilize this flange part 50 that the one-piece type object lens 15 of diffraction are installed on the light pick-up device 1 more accurately.

From the divergent beams of semiconductor laser 11 outgoing after seeing through polarizing beamsplitter 15; a diffracted bodily form coupled lens 13 becomes parallel beam; become circularly polarized light through 1/4 wavelength plate 14, by becoming the hot spot that focuses on the information recording surface 16b by the one-piece type object lens 15 of diffraction through the protective seam 16a of CD 16 behind the unshowned diaphragm.The topworks 2 that the one-piece type object lens 15 of diffraction are configured on its periphery carries out focus control and tracking Control.

After the folded light beam of modulating by information pits on the information recording surface 16b is again by the one-piece type object lens 15 of diffraction, diaphragm, 1/4 wavelength sheet, become and be linear polarization, diffracted one-piece type coupled lens 13 becomes and is converging beam, reflected by polarizing beamsplitter 12, by producing astigmatism, be focused on the photodetector 19 through hurdle face coupled lens 17 and concavees lens 18.Can use the information of output signal reading and recording in CD 16 of photodetector 19 then.

Because the one-piece type object lens 15 of the diffraction of present embodiment are plastic lenss of one group of formation, so when the temperature of the one-piece type object lens 15 of diffraction along with and when rising from the rising of the heat release of topworks 2 and environment temperature, the direction that diminishes to refractive index changes, thereby its spherical aberration is changed to over-compensation direction direction.In addition, because the one-piece type coupled lens 13 of diffraction is plastic lenss, and its refractive index satisfies above-mentioned (3) formula, so when the temperature of the one-piece type lens 13 of diffraction rises with the rising of the heat release of topworks 2 and environment temperature, the direction that tails off to refractive index changes, thereby makes the light beam that penetrates from the one-piece type coupled lens 13 of diffraction become converging beam.Because this horizontal multiplying power that is equivalent to the one-piece type object lens 15 of diffraction diminishes, so along with the variation of this lateral magnification makes the spherical aberration of the one-piece type object lens 15 of diffraction change to the under-compensation direction.Because the refractive index of the one-piece type coupled lens 13 of diffraction and diffraction efficiency just in time can offset the one-piece type object lens 15 of diffraction and change and determine to the requirement that the spherical aberration of the under-compensation direction that changes with lateral magnification changes to the ball aberration that varies with temperature the over-compensation direction according to satisfying, though institute so that the light beam that penetrates from semiconductor laser 11 since during one-piece type object lens 15 temperature variation of process one-piece type coupled lens 13 of diffraction and diffraction also almost spherical aberration focus on steadily on the information recording surface 16b of CD 16.

In addition, the one-piece type object lens 15 of diffraction are because of being provided with the diffraction pattern that satisfies the such concentric circles roughly of above-mentioned (1) formula on optical surface, and axial chromatic aberration opposite in sign and the roughly the same axial chromatic aberration of its absolute value that the oscillation wavelength of relative response semiconductor laser 11 and diffraction pattern by the one-piece type coupled lens 13 of diffraction produce take place.Therefore the light beam from semiconductor laser 11 outgoing does not focus on the information recording surface 16b of CD 16 because of passing through one-piece type coupled lens 13 of diffraction and the one-piece type object lens 15 of diffraction with almost having axial chromatic aberration.

(second embodiment)

Fig. 3 is that the figure of the record regenerating of second embodiment with second light pick-up device formation of optical system represented to carry in summary.The light pick-up device of present embodiment is to carry the light pick-up device that can carry out the record regenerating usefulness optical system of recording of information regeneration with object lens to three kinds of different cd-rom usings of protective layer thickness from the light of three kinds of different light sources of wavelength compatiblely.

The 3rd a certain CD 22 among the various CD such as CD, the CD-R that second a certain CD among the CD 16 that three kinds of different CDs of protective layer thickness are high density DVD that protective seam is the thinnest and recording density is maximum, DVD, the DVD-ROM that protective seam is 0.6mm, DVD-RAM, DVD-R, the various DVD such as DVD-RW, DVD+RW and protective seam are 1.2mm, CD-RW, CD-Video, CD-ROM.

The light pick-up device 1 ' of Fig. 3 comprising: three kinds of semiconductor lasers of the semiconductor laser 32 of the 3rd light source of the semiconductor laser 11 of first light source of the light of using as the record regenerating that produces first CD 16, the light used as the semiconductor laser 31 of the secondary light source of the light of the regeneration usefulness that produces second CD 21, as the record regenerating that produces the 3rd CD 22, these semiconductor lasers are selected luminous by the thickness according to the CD protecting layer of recorded information.

Semiconductor laser 11 is that the GaN of emission wavelength 400nm degree is a bluish violet light laser, in addition, is the bluish violet light laser as the light source of the light beam of emission wavelength 400nm degree except that above-mentioned GaN, also can be the SHG bluish violet light laser that utilizes second harmonic.Semiconductor laser 31 is semiconductor lasers of the light beam of emission wavelength 650nm degree.Semiconductor laser 32 is infrared semiconductor lasers of the light beam of emission wavelength 780nm degree.

In addition, light pick-up device 1 ' comprise is as the one-piece type coupled lens 13 of diffraction and the one-piece type object lens 40 of diffraction of the collimation lens of the parallel beam that the divergent beams from semiconductor laser 11 is become parallel optical axis.

The one-piece type lens 40 of diffraction are the lens that can finish following function: make from semiconductor laser 11 and penetrate and focus on the information recording surface 16b in the mode in the range of diffraction in first numerical aperture by the protective seam 16a as first CD 16 of high density DVD through the light beam of the one-piece type coupled lens 13 of diffraction; and make from the divergent beams of semiconductor laser 31 emission by being that mode in the range of diffraction in the second value aperture focuses on the information recording surface 21b to become as the protective seam 21a of second CD 21 of DVD; and make from the divergent beams of semiconductor laser 32 emission and focus on the information recording surface 22b in the mode that becomes in the range of diffraction in the third value aperture by protective seam 22a as the 3rd CD 22 of CD; wherein first numerical aperture is more than 0.75; the second value aperture is 0.60 to 0.65, and the third value aperture is 0.45 to 0.50.

The one-piece type object lens 40 of diffraction are aspherical plastic lenses of one group of formation, and roughly concentric diffraction pattern is set on the face of diffraction one bodily form coupled lens 13 sides of the one-piece type object lens 40 of diffraction.The diffraction pattern of the one-piece type object lens 40 of diffraction can form good wave front according to the thin CD of the relative protective seam of diffraction light of short-wavelength beam, and the requirement that the diffraction light of face length wavelength light beam protects the CD of bed thickness can form good wave front is relatively determined.

In addition, the diffraction pattern of the one-piece type object lens 40 of diffraction is determined according to the requirement of satisfying above-mentioned (5) formula, (8) formula, (9) formula and (11) formula.The lens thickness of the one-piece type object lens 40 of diffraction on its optical axis determined according to satisfying above-mentioned formula (12).

In addition, roughly the diffraction pattern of concentric circles both can be arranged on the face of diffraction one bodily form coupled lens 13 sides of the one-piece type object lens 40 of diffraction, also can be arranged on both of face of the face of one-piece type lens 13 sides of diffraction and CD side.Though and the relative optical axis of diffraction pattern of the one-piece type object lens 40 of diffraction forms roughly concentric circles, and diffraction pattern in addition also can be set.The one-piece type object lens 40 of diffraction have vertically extending of relative optical axis in addition, and flange part 50 is arranged, by this flange part 50 can make the one-piece type object lens 40 of diffraction be installed in more accurately light pick-up device 1 ' on.

The one-piece type coupled lens 13 of diffraction is that handle is transformed into the collimation lens of the parallel beam that is parallel to optical axis from the divergent beams of semiconductor laser 11, and is plastic lens.In addition, also can become littler lens or make divergent beams be transformed into lens of converging beam etc. as the one-piece type coupled lens 13 of diffraction with the angle of divergence that makes from the divergent beams of semiconductor laser 11 from semiconductor laser 11.

In addition, the roughly diffraction pattern of concentric circles is set on the face of one-piece type object lens 40 sides of the diffraction of the one-piece type coupled lens 13 of diffraction.The diffraction pattern of the one-piece type coupled lens 40 of above-mentioned diffraction is determined according to the requirement of satisfying above-mentioned (6) formula.Roughly the diffraction pattern of concentric circles both can be arranged on the face of semiconductor laser 11 sides of the one-piece type coupled lens 13 of diffraction in addition, also can be arranged on both of face of the face of semiconductor laser 11 sides and one-piece type object lens 40 sides of diffraction.Though the relative optical axis of diffraction pattern of the one-piece type coupled lens 13 of diffraction forms roughly concentric circles, and diffraction pattern in addition also can be set.

From semiconductor laser 11 outgoing and divergent beams after seeing through polarizing beamsplitter 12; a diffracted bodily form coupled lens 13 becomes parallel beam, and one-piece type object lens 40 become the hot spot that focuses on the information recording surface 16b through the protective seam 16a of first CD 16 by diffraction behind polarizing beamsplitter 41, polarizing beamsplitter 42 and unshowned diaphragm.The topworks 2 that the one-piece type object lens 40 of diffraction are configured on its periphery carries out focus control and tracking Control.

After the folded light beam of modulating by information pits on the information recording surface 16b is again by the one-piece type object lens 40 of diffraction, diaphragm, polarized beam splitting device 42, polarized beam splitting device 41, diffracted one-piece type coupled lens 40 becomes and is converging beam, reflected by polarizing beamsplitter 12, by producing astigmatism, be focused on the photodetector 19 through hurdle face coupled lens 17 and concavees lens 18.Can use the information of output signal reading and recording in first CD 16 of photodetector 19 then.

Because the one-piece type object lens 40 of the diffraction of present embodiment are plastic lenss of one group of formation, so when the temperature of the one-piece type object lens 40 of diffraction along with and when rising from the rising of the heat release of topworks 2 and environment temperature, the direction that diminishes to refractive index changes, thereby its spherical aberration is changed to over-compensation direction direction.In addition, because reflecting one-piece type coupled lens 13 is plastic lenss, and its refractive index satisfies above-mentioned (7) formula, so when the temperature of the one-piece type lens 13 of diffraction rises with the rising of the heat release of topworks 2 and environment temperature, the direction that tails off to refractive index changes, thereby makes the light beam that penetrates from the one-piece type coupled lens 13 of diffraction become converging beam.Because this horizontal multiplying power that is equivalent to the one-piece type object lens 40 of diffraction diminishes, so, the spherical aberration of the one-piece type object lens 40 of diffraction is changed to the under-compensation direction along with the variation of this lateral magnification.Because the refractive index of the one-piece type coupled lens 13 of diffraction and diffraction efficiency just in time can offset the one-piece type object lens 15 of diffraction and change and determine to the requirement that the spherical aberration of the under-compensation direction that changes with lateral magnification changes to the ball aberration that varies with temperature the over-compensation direction according to satisfying, though institute so that the light beam that penetrates from semiconductor laser 11 since during one-piece type object lens 15 temperature variation of process one-piece type coupled lens 13 of diffraction and diffraction also almost spherical aberration focus on steadily on the information recording surface 16b of first CD 16.

In addition, the one-piece type object lens 40 of diffraction are because of being provided with the diffraction pattern that satisfies the such concentric circles roughly of above-mentioned (5) formula on optical surface, and the axial chromatic aberration opposite in sign and the roughly the same axial chromatic aberration of its absolute value that are produced by the diffraction pattern of the one-piece type coupled lens 13 of diffraction with reaction semiconductor laser instrument 11 and oscillation wavelength takes place.Therefore the light beam from semiconductor laser 11 outgoing does not focus on the information recording surface 16b of first CD 16 because of passing through one-piece type coupled lens 13 of diffraction and the one-piece type object lens 40 of diffraction with almost having axial chromatic aberration.

In addition; from the divergent beams of semiconductor laser 31 emission see through polarized beam splitting device 12 ' after; by polarized beam splitting device 41 reflection by polarized beam splitting device 42 and not shown diaphragm after, focus on the information recording surface 21b through the protective seam 21a of second CD 21 by the one-piece type object lens 40 of diffraction and to become hot spot.The one-piece type object lens 40 of diffraction are configured in its peripheral topworks 2 and carry out focus control and tracking Control.

After the folded light beam of modulating by information pits on the information recording surface 21b is again by the one-piece type object lens 40 of diffraction, diaphragm, polarized beam splitting device 42, by polarizing beamsplitter 12 ' reflection, by through hurdle face cemented lens 17 ' and concavees lens 18 ' generation astigmatism, be focused at photodetector 19 ' on.Can use the information of output signal reading and recording in second CD 21 of photodetector 19 then.

In addition; see through polarized beam splitting device 12 from semiconductor laser 32 emission and divergent beams " after; after being passed through not shown diaphragm by 42 reflections of polarized beam splitting device, focus on the information recording surface 22b through the protective seam 22a of the 3rd CD 22 by the one-piece type object lens 40 of diffraction and to become hot spot.The one-piece type object lens 40 of diffraction are configured in its peripheral topworks 2 and carry out focus control and tracking Control.

After the folded light beam of modulating by information pits on the information recording surface 22b is again by the one-piece type object lens 40 of diffraction, diaphragm, by polarizing beamsplitter 42 and polarized beam splitting device 12 in " after the reflection;, be focused at photodetector 19 " by producing astigmatism through hurdle cylindrical lens 17 " and concavees lens 18 ".Can use photodetector 19 then " the information of output signal reading and recording in the 3rd CD 22.

The unshowned 1/4 wavelength sheet of configuration in the light path separately between semiconductor laser 32 and the one-piece type lens 40 of diffraction in addition, between light pick-up device 1 ' between semiconductor laser 11 and the one-piece type object lens 40 of diffraction, semiconductor laser 31 and the one-piece type object lens 40 of diffraction.

Such light pick-up device 1 shown in Fig. 3 ' can optical information recording medias such as corresponding for example various CD such as CD, CD-R, CD-RW, CD-Video, CD-ROM, DVD, DVD-ROM, DVD-RAM, DVD-R, various DVD such as DVD-RW, DVD+RW, MD carry is on the player of compatibility or seat etc. or their AV equipment, personal computer, other the sound such as information terminal and/or image recording structure and/or regenerating unit of packing into.

(the 3rd embodiment)

Figure 46 is that the figure of the record regenerating of the 3rd embodiment with the 3rd light pick-up device formation of optical system represented to carry in summary.The light pick-up device of present embodiment is to carry the light pick-up device that can carry out the record regenerating usefulness optical system of recording of information regeneration with object lens to three kinds of different cd-rom usings of protective layer thickness from the light of three kinds of different light sources of wavelength compatiblely.

Three kinds of CDs that recording density is different are to use the high density of the short-wavelength beam of 400nm degree and recording density maximum and protective seam to be the 3rd CD 22 among the various CD such as CD, the CD-R of 1.2mm, CD-RW, CD-Video, CD-ROM as the second some CD 21 among DVD, the DVD-ROM of 0.6mm, DVD-RAM, DVD-R, the various DVD such as DVD-RW, DVD+RW and protective seam for record regenerating.

Light pick-up device 1 " comprising: the semiconductor laser 11 of first light source of the light of using as the record regenerating that produces first CD 23 and the assembly 80 that photodetector 19 incorporate first CDs are used; as the semiconductor laser 31 of the secondary light source of the light of the regeneration usefulness that produces second CD 21 and the assembly 90 that photodetector 19 ' incorporate second CD is used; the semiconductor laser 32 and photodetector 19 of the 3rd light source of the light of using as the record regenerating that produces the 3rd CD 22 " assembly 100 that incorporate the 3rd CD is used, and these semiconductor lasers are selectively luminous by the density according to the record of the CD of recorded information.

In addition, light pick-up device 1 " comprises that as the one-piece type coupled lens 60 of diffraction of the collimation lens of the parallel beam that becomes parallel optical axis from the divergent beams of semiconductor laser 11 and semiconductor laser 31 the one-piece type object lens 60 of this diffraction are configured in the light path that the light beam from semiconductor laser 11 and semiconductor laser 31 passes through together.

The one-piece type object lens 70 of diffraction are the lens that can finish following function: make from semiconductor laser 11 and penetrate and focus on the information recording surface 23b in the mode in the range of diffraction in first numerical aperture through the light beam of the one-piece type coupled lens 60 of the diffraction protective seam 23a by first CD 23; and make from light beam semiconductor laser 31 emission and by the one-piece type coupled lens 60 of diffraction by being that mode in the range of diffraction in the second value aperture focuses on the information recording surface 21b to become as the protective seam 21a of second CD 21 of DVD; and make from the divergent beams of semiconductor laser 32 emission and focus on the information recording surface 22b in the mode that becomes in the range of diffraction in the third value aperture by protective seam 22a as the 3rd CD 22 of CD; wherein first numerical aperture is about 0.65; the second value aperture is 0.60 to 0.65, and the third value aperture is 0.45 to 0.50.

The one-piece type object lens 70 of diffraction are aspherical plastic lenses of one group of formation, and roughly concentric diffraction pattern is set on the face of diffraction one bodily form coupled lens 60 sides of the one-piece type object lens 70 of diffraction.The diffraction pattern of the one-piece type object lens 60 of diffraction satisfies above-mentioned (A) formula, and determines this diffraction pattern in the requsst listed below.And the diffraction progression (being made as n2, n3 respectively) that has maximum amount the diffraction light that takes place when making from light beam incident that semiconductor laser 31 and semiconductor laser 32 penetrates is lower than the diffraction progression (being made as n1) that has maximum amount from semiconductor laser 11 emitted light beams incidents the time the diffraction light of launching.And have following wavelength characteristic: described wavelength characteristic can make from the diffraction light of the light beam of semiconductor laser 11 ejaculations and form good wave front at the information recording surface 23a of the first high CD 23 of recording density, the diffraction light of the light beam that penetrates from semiconductor laser 31 forms good wave front at the information recording surface 21a of second CD 21, form good wave front from the diffraction light of semiconductor laser 32 emitted light beams at the information recording surface 31a of the 3rd CD 31, therefore the wavelength coverage of corresponding each semiconductor laser of energy is kept high diffraction efficiency, thereby can carry out the recording of information regeneration corresponding with each CD compatiblely.

Specifically, can select (n1, n2, n3)=some combinations in (2,1,1), (4,3,2), (6,4,3), (8,5,4) and (10,6,5) as n1, n2 and n3.

In addition, be to carry compatiblely to carry out the occasion of the record regenerating of information record regenerating with object lens with the light pick-up device of optical system to high density DVD and two kinds of CDs of DVD, in selecting (n1, n2)=(2,1), (3,2), (4,2), (5,3), (6,4), (7,4), (8,5), (9,6), (10,6) certain is during as the combination of n1, n2, can corresponding semiconductor laser 11 and the wavelength coverage separately of semiconductor laser 31 keep high diffraction efficiency, thereby can suppress light loss.

In addition, roughly the diffraction pattern of concentric circles both can be arranged on the face of diffraction one bodily form coupled lens 60 sides of the one-piece type object lens 70 of diffraction, also can be arranged on both of face of the face of one-piece type lens 60 sides of diffraction and CD side.Though and the relative optical axis of diffraction pattern of the one-piece type object lens 70 of diffraction forms roughly concentric circles, and diffraction pattern in addition also can be set.In addition, the one-piece type object lens 70 of diffraction have vertically extending of relative optical axis, and flange part 50 is arranged, and can make the one-piece type object lens 70 of diffraction be installed in light pick-up device 1 more accurately by this flange part 50 " on.

The one-piece type coupled lens 70 of diffraction is that handle is transformed into the collimation lens of the parallel beam that is parallel to optical axis from the divergent beams of semiconductor laser 11; And is plastic lens.In addition; Also can become littler lens or make divergent beams be transformed into lens of converging beam etc. as the one-piece type coupled lens 70 of diffraction with the angle of divergence that makes from the divergent beams of semiconductor laser 11 and semiconductor laser 31 from semiconductor laser 11 and semiconductor laser 31.And also can be that the divergent beams from semiconductor laser 11 are transformed into parallel beam and will become less lens from the angle of divergence of the divergent beams of semiconductor laser 31; Also can be to make divergent beams be transformed into parallel beam, make the divergent beams of semiconductor laser 31 be transformed into the lens of converging beam from semiconductor laser 11. or also can be the lens that make divergent beams from semiconductor laser be transformed into collimated light beam and will diminish from the dispersion angle of the divergent beams of semiconductor laser 11; Also can be to make the divergent beams from semiconductor laser 31 be transformed into collimated light beam and make the lens that are transformed into converging beam from the divergent beams of semiconductor laser 11, or make the dispersion angle from the divergent beams of a semi-conductive laser instrument in semiconductor laser 11 and the semiconductor laser 31 become smaller and make the lens that are transformed into converging beam from the divergent beams of second half conductor laser.

In addition, the roughly diffraction pattern of concentric circles is set on the face of one-piece type object lens 70 sides of the diffraction of the one-piece type coupled lens 60 of diffraction.The diffraction pattern of the one-piece type coupled lens 60 of above-mentioned diffraction is determined according to the requirement of satisfying above-mentioned (B) formula.And the diffraction progression (being made as n1 ') that has maximum amount the diffraction light that produces when making the progression (being made as n2 ') that has the diffraction light of maximum amount when the light beam incident of penetrating from semiconductor laser in the diffraction light that produces than the light beam incident penetrated from semiconductor laser 11 hangs down to determine diffraction pattern.Therefore the wavelength coverage of corresponding each semiconductor laser of energy is kept high diffraction efficiency, thereby can collimate on the one-piece type object lens 70 of diffraction under making from the repressed very little state of divergent beams light loss of each semiconductor laser.

Specifically, also can select (n1 ', n2 ')=some combinations in (2,1), (3,2), (4,2), (5,3), (6,4), (7,4), (8,5), (9,6), (10,6) as n1 ' and n2 '.

In addition, from semiconductor laser 11, in the light path that the light beam of semiconductor laser 31 and semiconductor laser 32 passes through jointly during the one-piece type coupled lens 60 of (in the light path in Figure 46 between the one-piece type object lens 70 of polarizing beamsplitter 42 and diffraction) configuration diffraction, as the progression that has the diffraction light of maximum amount the diffraction light that produces when being located at light beam incident from the ejaculation of semiconductor laser 32 is n3 ', then at this moment, if select (n1 ', n2 ', n3 ')=(2,1,1), (4,3,2), (6,4,3), (8,5,4), (10,6,5) some in as n1 ', the combination of n2 ' and n3 ', then can swash first device 11 by corresponding semiconductor, each wavelength coverage of semiconductor laser 31 and semiconductor laser 32 is kept high-diffraction efficiency, thereby can suppress light loss.

Roughly the diffraction pattern of concentric circles both can be arranged on the face of semiconductor laser 11 sides of the one-piece type coupled lens 60 of diffraction in addition, also can be arranged on both of face of the face of semiconductor laser 11 sides and one-piece type object lens 70 sides of diffraction.Though the relative optical axis of diffraction pattern of the one-piece type coupled lens 60 of diffraction forms roughly concentric circles, and diffraction pattern in addition also can be set.

From the divergent beams of semiconductor laser 11 outgoing after by polarizing beamsplitter 12; diffracted one-piece type coupled lens 60 becomes parallel beam; behind polarizing beamsplitter 42 and unshowned diaphragm, become the hot spot that focuses on the information recording surface 23b through the diffracted one-piece type object lens 70 of the protective seam 23a of CD 23.The topworks 2 that the one-piece type object lens 70 of diffraction are configured on its periphery carries out focus control and tracking Control.

After the folded light beam by information pits modulation on the information recording surface 23b was again by the one-piece type object lens 70 of diffraction, diaphragm, polarized beam splitting device 42, diffracted one-piece type coupled lens 60 became and is converging beam, is focused on the photodetector 19.Can read the information that is recorded in first CD 23 with the output signal of photodetector 19 then.

From semiconductor laser 31 outgoing and divergent beams after by polarizing beamsplitter 12 reflections, by polarizing beamsplitter 42 and unshowned diaphragm after the protective seam 21a of CD 21 becomes the hot spot of diffracted one-piece type object lens focusing on information recording surface 21b.The topworks 2 that the one-piece type object lens 70 of diffraction are configured on its periphery carries out focus control and tracking Control.

After the folded light beam by information pits modulation on the information recording surface 21b is again by the one-piece type object lens 70 of diffraction, diaphragm, polarized beam splitting device 42, reflected by polarizing beamsplitter 12, by be focused at through hurdle face coupled lens 60 photodetector 19 ' on.Can use then photodetector 19 ' the information of output signal reading and recording in second CD 21.

Because the one-piece type object lens 70 of the diffraction of present embodiment are plastic lenss of one group of formation, so when the temperature of the one-piece type object lens 70 of diffraction along with and when rising from the rising of the heat release of topworks 2 and environment temperature, the direction that diminishes to refractive index changes, thereby its spherical aberration is changed to over-compensation direction direction.In addition, because reflecting one-piece type coupled lens 60 is plastic lenss, and its refractive index satisfies above-mentioned (c) formula, so when the temperature of the one-piece type lens 60 of diffraction rises with the rising of the heat release of topworks 2 and environment temperature, the direction that tails off to refractive index changes, thereby makes the light beam that penetrates from the one-piece type coupled lens 13 of diffraction become converging beam.Because this horizontal multiplying power that is equivalent to the one-piece type object lens 70 of diffraction diminishes, so, the spherical aberration of the one-piece type object lens 70 of diffraction is changed to the under-compensation direction along with the variation of this lateral magnification.Because the refractive index of the one-piece type coupled lens 60 of diffraction and diffraction efficiency just in time can offset the one-piece type object lens 70 of diffraction and change and determine to the requirement that the spherical aberration of the under-compensation direction that changes with lateral magnification changes to the ball aberration that varies with temperature the over-compensation direction according to satisfying, so that the light beam that penetrates from semiconductor laser 11 and semiconductor laser 31 because through one-piece type coupled lens 60 of diffraction and the one-piece type object lens 70 of diffraction, even during temperature variation also almost spherical aberration focus on steadily on the information recording surface separately of first CD 23 and second CD 21.

In addition, the one-piece type object lens 70 of diffraction are because of being provided with the diffraction pattern that satisfies the such concentric circles roughly of above-mentioned (A) formula on optical surface, and axial chromatic aberration opposite in sign and the roughly the same axial chromatic aberration of its absolute value that the oscillation wavelength of corresponding semiconductor laser 11 and semiconductor laser 31 and diffraction pattern by the one-piece type coupled lens 60 of diffraction produce take place.Therefore the light beam from semiconductor laser 11 and semiconductor laser 31 outgoing does not focus on respectively on the information recording surface separately of first CD 23 and second CD 21 because of passing through one-piece type coupled lens 60 of diffraction and the one-piece type object lens 70 of diffraction with almost having axial chromatic aberration.

In addition; after seeing through polarized beam splitting device 42 from the divergent beams of semiconductor laser 32 emission; after polarized beam splitting device 42 reflection, behind not shown diaphragm, focus on the information recording surface 22b through the protective seam 22a of the 3rd CD 22 by the one-piece type object lens 70 of diffraction and to become hot spot.The one-piece type object lens 70 of diffraction are configured in its peripheral topworks 2 and carry out focus control and tracking Control.

After the folded light beam by information pits modulation on the information recording surface 22b is again by the one-piece type object lens 70 of diffraction, diaphragm, reflected by polarizing beamsplitter 42, be focused at photodetector 19 " sensitive surface on.Then can be with photodetector 19 " output signal read the information that is recorded in the 3rd CD 22.

Such light pick-up device 1 shown in Figure 46 " can carry on the player of compatibility or seat etc. or their AV equipment, personal computer, other the sound such as information terminal and/or image recording structure and/or regenerating unit of packing into corresponding to optical information recording medias such as for example various CD such as CD, CD-R, CD-RW, CD-Video, CD-ROM, DVD, DVD-ROM, DVD-RAM, DVD-R, various DVD such as DVD-RW, DVD+RW, MD.

In addition; record regenerating optical system according to present embodiment; the high density DVD that the royal purple optical semiconductor laser is used with light source as record regenerating is as protective layer thickness 0.6mm; the CD that closely is close to of the numerical aperture 0.65 of object lens; but obviously; even the CD that closely is close to as the numerical aperture 0.85 of high density DVD protective layer thickness 0.1mm object lens (for example CD of the blue light drum specification of delivering in February, 2002) also can use technology of the present invention.

(embodiment)

Be described more specifically the present invention below by embodiment 1 to 8, but the present invention is not subjected to the qualification of these embodiment.In addition, the aspheric surface on each lens of embodiment is an X-axis with establishing optical axis direction, with the height of optical axis vertical direction be h, following several 1 expressions when radius-of-curvature of plane of refraction is γ, wherein establishing k is the circularity coefficient, A _2iBe asphericity coefficient.

[several 1]

Z = \frac{h^{2} / r}{1 + \sqrt{1 - (1 + k) h^{2} / r^{2}}} + Σ_{i = 0}^{\infty} A_{2 i} h^{2 i}

In addition, can represent with above-mentioned (A) formula as the optical path difference function of the diffraction structure that is arranged on the ring-shaped area on the present embodiment object lens, and as the optical path difference function phi that is arranged on the ring-shaped area diffraction structure on each aberration compensation optical element _bCan represent with above-mentioned (B) formula.

(embodiment 1)

Embodiment 1 is the record regenerating optical system of the best light pick-up device of being applicable to Fig. 2.Present embodiment is to make as the one-piece type collimation lens of the diffraction of aberration compensation optical element; With the optical system after the one-piece type object lens object lens combination of diffraction, use focal length 8mm, the plastic lens of one group of formation of NA0.28 is as the one-piece type collimation lens of diffraction, and the plastic lens of one group of formation of use focal length 2.2mm, NA0.85 is as the one-piece type object lens of diffraction.And make the face of the CD side of the one-piece type collimation lens of diffraction become diffraction surfaces with negative diffraction efficiency, make the face of the semiconductor laser side of the one-piece type object lens of diffraction become diffraction surfaces, the data of using optical system about the record regenerating of embodiment 1 have been shown in table 1 with positive diffraction efficiency.

Table 1

The face sequence number	r(mm)	d(mm)	Nλ	νd	Remarks
The face sequence number	r(mm)	d(mm)	Nλ	νd	Remarks		0		6.8314			Light source
1 2	22.1156 -4.3868	2.0000 10.0000	1.52469	56.5	The collimation lens object lens		0		6.8314			Light source
1 2	22.1156 -4.3868	2.0000 10.0000	1.52469	56.5	The collimation lens object lens	3 4	1.5943 -1.4072	3.2000 0.4059	1.52491	56.5	To thing
5 6	∞ ∞	0.1000	1.61949	30.0	Protective seam	3 4	1.5943 -1.4072	3.2000 0.4059	1.52491	56.5	To thing

Asphericity coefficient

	The 1st	The 2nd	The 3rd	The 4th
	The 1st	The 2nd	The 3rd	The 4th	k A ₄	-1.70020E+01 -3.13030E-05	-8.75470E-01 1.59370E-04	-7.00150E-01 5.73480E-03	-3.68897E+01 2.34529E-01

A ₆ A ₈ A ₁₀ A ₁₂ A ₁₄ A ₁₆ A ₁₈ A ₂₀

1.62780E-03 1.73310E-04 1.43140E-04 -5.76550E-05 -7.43870E-07 5.59960E-06 -7.34190E-07 -1.04210E-07

-4.06108E-01 3.24212E-01 -1.05497E-01 5.53253E-05

The diffraction surfaces coefficient

	The 1st	The 2nd	The 3rd
	The 1st	The 2nd	The 3rd	b ₂ b ₄ b ₆ b ₈ b ₁₀	3.87370E-03	4.12640E-03 -6.24970E-05	-2.30000E-02 -3.15710E-03 2.28830E-04 2.54720E-05 -3.06440E-05

Figure 4 illustrates the index path of the record regenerating of embodiment 1 with optical system.Spherical aberration when Fig. 5 is the wavelength 405 ± 5nm of the one-piece type collimation lens of diffraction of expression present embodiment and the curve of axial chromatic aberration, Fig. 6 be the one-piece type object lens of diffraction of expression present embodiment when wavelength 405 ± 5nm spherical aberration and the curve of axial chromatic aberration, Fig. 7 is that expression makes record regenerating after the combination of the one-piece type collimation lens of diffraction and diffraction one object lens with spherical aberration and the axial chromatic aberration of optical system when wavelength 405 ± 5nm.

As can be seen from Figure 5, when long wavelength side changed, the focal position was to the over-compensation side shifting in the incident light wavelength for the one-piece type collimation lens of the diffraction of present embodiment, and the long wavelength of incident is when short wavelength side changes, and the focal position is to the under-compensation side shifting.And can know from Fig. 6 and to find out that when the long wave side changed, the focal position was to the under-compensation side shifting in the incident light wavelength for the one-piece type object lens of the diffraction of present embodiment that when the short wavelength changed, the focal position was to the over-compensation side shifting in the incident light wavelength.As can be seen from Figure 7, make record regenerating after the combination of the one-piece type object lens of one-piece type collimation lens of diffraction and diffraction with the focal position of optical system and Wavelength-independent ground no change almost.

Show the temperature characterisitic of the record of embodiment 1 at Fig. 8 with optical system.Find out like that from Fig. 8, even with monomer is that spendable temperature range is one group one very narrow high NA plastic lens object lens of-10 to 40 degree, also can keep good optically focused characteristic by making the one-piece type collimation lens of these object lens and diffraction be combined in-20 to 85 temperature ranges of spending.

In addition, during wave-front aberration when accounting temperature changes, consider that in advance (its rate of change is-1.2 * 10 for the variations in refractive index of the plastic lens that causes because of temperature variation ^-4Degree) it is very little that the influence that because of the change of shape of plastic lens the wave front spherical aberration is changed and during the wavelength variations (its rate of change is+the 0.05nm/ degree) of royal purple semiconductor laser and change of refractive compare, so do not consider the change of shape of plastic lens.The design conditions of the wave-front aberration when the calculating above-mentioned temperature variation also embodiment 2 to 7 with later explanation are identical.

Figure 9 illustrates the wavelength characteristic of the record regenerating of embodiment with optical system.Though beating because of mould, the royal purple optical semiconductor laser causes that wavelength variations 1 is to 2nm, but on monomer, even because of the variation of wavelength 1 to 2nm causes the very big object lens of 0.07 λ rms that surpass the edge limit, by making the one-piece type combination of lenses of keeping of these object lens and diffraction,, the wavelength variations of 2nm also can keep good optically focused characteristic even taking place.

In addition, when the wave-front aberration that calculates when beating the wavelength variations that causes because of mould, because become with the focusing of object lens irrelevant, so object lens 40 are fixed on the best image point position of 405nm, wave-front aberration value in Fig. 9 comprises because of what moved best image point position and defocuses component, and also the embodiment 2 to 7 of following explanation is identical to calculate condition when beating wave-front aberration when becoming of the wavelength that causes because of above-mentioned mould.

(embodiment 2)

Embodiment 2 makes as the integrated type optical beam expander of aberration compensation optical element and the optical system of the one-piece type object lens combination of diffraction, with entrance pupil aperture 3.16mm, penetrate pupil footpath 4.50mm, the plastic lens of two groups of two formations of angular magnification 1.47 is as diffraction integrated type optical beam expander, and the plastic lens of one group of formation of usefulness focal length 2.2mm, NA0.85 is as the one-piece type object lens of diffraction.And make the two sides of the positive lens of diffraction integrated type optical beam expander become diffraction surfaces with negative diffraction efficiency.In the data of using optical system shown in the table 2 about the record regenerating of embodiment 2.

Table 2

The face sequence number	r(mm)	d(mm)	Nλ	νd	Remarks
The face sequence number	r(mm)	d(mm)	Nλ	νd	Remarks		0		∞			Light source
1 2 3 4	-14.6582 6.9680 21.5525 -5.0607	1.0000 2.7535 1.8000 10.0000	1.52491 1.52491	56.5 56.5	Optical beam expander		0		∞			Light source
1 2 3 4	-14.6582 6.9680 21.5525 -5.0607	1.0000 2.7535 1.8000 10.0000	1.52491 1.52491	56.5 56.5	Optical beam expander	5 6	1.7316 -1.8541	3.2700 0.4254	1.52491	56.5	Object lens
7 8	∞ ∞	0.1000	1.61949	30.0	Protective seam	5 6	1.7316 -1.8541	3.2700 0.4254	1.52491	56.5	Object lens

Asphericity coefficient

	The 1st	The 2nd	The 3rd	The 4th	The 5th	The 6th
	The 1st	The 2nd	The 3rd	The 4th	The 5th	The 6th	k A ₄ A ₆ A ₈ A ₁₀ A ₁₂ A ₁₄ A ₁₆ A ₁₈ A ₂₀	6.02232E+00 -2.34616E-04	-6.13661E+00 3.25639E-04	6.12260E+00 -1.37260E-04	-3.42170E-01 3.56160E-04	-6.56420E-01 6.41290E-03 7.70850E-04 -1.14780E-04 2.10380E-04 -3.51540E-05 -2.78870E-07 3.58030E-06 -8.40940E-07 3.59040E-08	-6.64430E+01 2.57010E-01 -3.92280E-01 3.25320E-01 -1.12520E-01 5.53250E-05

The diffraction surfaces coefficient

	The 3rd	The 4th	The 5th	The 6th
	The 3rd	The 4th	The 5th	The 6th	b ₂ b ₄ b ₆ b ₈ b ₁₀	1.33800E-02	1.24090E-02	-3.0000E-02 -1.36890E-03 -1.73920E-04 3.06390E-05 1.90120E-05	-6.50000E-02 -1.48810E-02 -1.15200E-03

Figure 10 illustrates the index path of the record regenerating of embodiment 2 with optical system.Figure 11 is the spherical aberration in the wavelength 405 ± 5nm of the one-piece type object lens of diffraction of expression present embodiment and the curve of axial chromatic aberration, and Figure 12 is that expression makes record regenerating after diffraction integrated type optical beam expander and the one-piece type object lens combination of diffraction with the spherical aberration in the wavelength 405 ± 5nm of optical system and the curve of axial chromatic aberration.

As can be seen from Figure 11, when long wavelength side changed, focus was to the under-compensation side shifting in the incident light wavelength for the one-piece type object lens of the diffraction of present embodiment, and when short wavelength side changed, the focal position was to the over-compensation side shifting in the incident light wavelength.And as can be seen from Figure 12, the record regenerating after the one-piece type object lens of diffraction integrated type optical beam expander and diffraction make up is changed hardly with optics system focus position and Wavelength-independent ground.

Figure 13 illustrates the temperature characterisitic of the record regenerating of present embodiment with optical system, as know from Figure 13 see, by making the combination of high NA plastic objective lens and diffraction integrated type optical beam expander, can make in the temperature range of-20 to 85 degree and keep good optically focused characteristic.

Figure 14 illustrates the wavelength characteristic of the record regenerating of embodiment with optical system.As know from Figure 14 see, by making the combination of high NA plastic objective lens and diffraction integrated type optical beam expander, change and also can keep the optically focused characteristic well even 2nm takes place wavelength.

(embodiment 3)

Embodiment 3 makes as the diffraction integrated type optical beam expander of aberration compensation optical element and the optical system after the one-piece type object lens combination of diffraction, with entrance pupil aperture 2.47mm, penetrate pupil footpath 4.50mm, the optical beam expander of two groups of two formations of angular magnification 1.84 is as diffraction integrated type optical beam expander, and the plastic lens of one group of formation of usefulness focal length 2.2mm, NA0.85 is as the one-piece type object lens of diffraction.The positive lens of diffraction integrated type optical beam expander is a plastic lens, negative lens be the Abbe number glass lens littler than positive lens (HOYA society system, FD110).And the face of the CD side of the positive lens of diffraction integrated type optical beam expander becomes to having the diffraction surfaces of negative diffraction efficiency, the face of the semiconductor laser side of the one-piece type object lens of diffraction becomes to having the diffraction surfaces of positive diffraction efficiency, and the data of using optical system about the record regenerating of embodiment 3 have been shown in table 3.

Table 3

The face sequence number	r(mm)	d(mm)	Nλ	νd	Remarks
The face sequence number	r(mm)	d(mm)	Nλ	νd	Remarks		0		∞			Light source
1 2 3 4	-4.9735 ∞ ∞ -4.3064	1.0000 3.2579 1.8000 10.0000	1.84203 1.52469	25.7 56.5	Optical beam expander		0		∞			Light source
1 2 3 4	-4.9735 ∞ ∞ -4.3064	1.0000 3.2579 1.8000 10.0000	1.84203 1.52469	25.7 56.5	Optical beam expander	5 6	1.5943 -1.4072	3.2000 0.4059	1.52491	56.5	Object lens
7 8	∞ ∞	0.1000	1.61949	30.0	Protective seam	5 6	1.5943 -1.4072	3.2000 0.4059	1.52491	56.5	Object lens

Asphericity coefficient

	The 4th	The 5th	The 6th
	The 4th	The 5th	The 6th	k A ₄ A ₆ A ₈ A ₁₀ A ₁₂ A ₁₄ A ₁₆ A ₁₈ A ₂₀	-6.25720E-01 2.67860E-05	-7.00150E-01 5.73480E-03 1.62780E-03 1.73310E-04 1.43140E-04 -5.76550E-05 -7.43870E-07 5.59960E-06 -7.34190E-07 -1.04210E-07	-3.68897E+01 2.34529E-01 -4.06108E-01 3.24212E-01 -1.05497E-01 5.53253E-05

The diffraction surfaces coefficient

	The 4th	The 5th
	The 4th	The 5th	b ₂ b ₄ b ₆ b ₈ b ₁₀	1.50000E-02	-2.30000E-02 -3.15710E-03 2.28830E-04 2.54720E-05 -3.06440E-05

Figure 15 illustrates the index path of the record regenerating of embodiment 3 with optical system.Figure 16 is the spherical aberration in the wavelength 405 ± 5nm of the one-piece type object lens of diffraction of expression present embodiment and the curve of axial chromatic aberration.Figure 17 be expression make after the one-piece type object lens combination of diffraction integrated type optical beam expander and diffraction record regenerating with optical system when wavelength 405 ± 5nm spherical aberration and the curve of axial chromatic aberration.

Can know from Figure 16 and to find out that when long wavelength side changed, the focal position was to the under-compensation side shifting in the incident light wavelength for the one-piece type object lens of the diffraction of present embodiment, when the short wavelength changed, the focal position was to the over-compensation side shifting in the incident light wavelength.And can know from Figure 17 and to find out, the record regenerating after the one-piece type object lens combination of diffraction integrated type optical beam expander and diffraction is changed hardly with optics system focus position and Wavelength-independent ground.

Figure 18 illustrates the temperature characterisitic of present embodiment record regenerating with optical system.As from know Figure 18 see, by make high NA plastic objective lens and diffraction integrated type optical beam expander the combination, can-20 to+85 the degree temperature ranges keep good optically focused characteristic.

Figure 19 illustrates the wavelength characteristic of the record regenerating of present embodiment with optical system, as from know Figure 19 see, by making the combination of high NA plastic objective lens and diffraction integrated type optical beam expander, also can keep good optically focused rerum natura even cause the wavelength variations of 2nm.

(embodiment 4)

Embodiment 4 is the optical systems as the one-piece type plastic lens of the diffraction of aberration compensation optical element and one-piece type object lens of diffraction and combination, use entrance pupil aperture 4.50mm, the plastic lens that penetrates pupil spare 4.70m numerical aperture and be one group of formation of 0 is as the aberration compensation optical element, use focal length 2.2mm, the plastic lens of one group of formation of NA0.85 is as the one-piece type object lens of diffraction, and the plane that makes the light source side of compensating optical element becomes to having the diffraction surfaces of negative diffraction efficiency, and the face of the semiconductor laser side of diffraction one bodily form object lens is become to having the diffraction surfaces of positive diffraction efficiency.The data of using optical system about the record regenerating of embodiment 4 have been shown in table 4.

Table 4

The face sequence number	r(mm)	d(mm)	Nλ	νd	Remarks
The face sequence number	r(mm)	d(mm)	Nλ	νd	Remarks		0		∞			Light source
1 2	∞ -8.0797	1.5000 5.0000	1.52491	56.5	Aberration compensation optics sub-prime		0		∞			Light source
1 2	∞ -8.0797	1.5000 5.0000	1.52491	56.5	Aberration compensation optics sub-prime	3 4	1.6893 -1.7971	3.0500 0.4188	1.52491	56.5	Object lens
5 6	∞ ∞	0.1000	1.61949	30.0	Protective seam	3 4	1.6893 -1.7971	3.0500 0.4188	1.52491	56.5	Object lens

Asphericity coefficient

	The 2nd	The 3rd	The 4th
	The 2nd	The 3rd	The 4th	k A ₄ A ₆ A ₈ A ₁₀ A ₁₂ A ₁₄ A ₁₆ A ₁₈ A ₂₀	-2.90480E-01 6.79410E-06	-6.63850E-01 9.31590E-03 7.52060E-04 -3.39780E-05 1.72060E-04 -5.12150E-05 -1.30990E-06 5.05470E-06 -6.42060E-07 -8.07010E-08	-5.74856E+01 2.36118E-01 -4.12553E-01 3.36605E-01 -1.12520E-01 5.53253E-05

The diffraction surfaces coefficient

Figure 20 illustrates the index path of the record regenerating of embodiment 4 with optical system.Figure 21 be the one-piece type object lens of diffraction of expression present embodiment when wavelength 405 ± 5nm spherical aberration and the curve of axial chromatic aberration, Figure 22 be make after the one-piece type object lens combination of aberration compensation optical element and diffraction record regenerating with optical system when wavelength 405 ± 5nm spherical aberration and the curve of axial chromatic aberration.

Can know from Figure 21 and to find out that when long wavelength side changed, the focal position was to the under-compensation side shifting in the incident light wavelength for the one-piece type object lens of the diffraction of present embodiment, when the short wavelength changed, the focal position was to the over-compensation side shifting in the incident light wavelength.And can know from Figure 22 and to find out, the record regenerating after the one-piece type object lens combination of aberration compensation optical element and diffraction is changed hardly with optics system focus and Wavelength-independent ground.

Figure 23 illustrates the temperature characterisitic of the record regenerating of present embodiment with optical system, as from know Figure 23 see, by making high NA plastic objective lens and aberration compensation optical element combination, can keep good optically focused characteristic in the temperature range of-2.0 to 85 degree.

Figure 24 illustrates the wavelength characteristic of the record regenerating of present embodiment with optical system, as know from Figure 24 see, by making high NA plastic objective lens and resemble the combination of positive compensating optical element, even cause that at wavelength the variation of 2nm also can keep good optically focused rerum natura.

(embodiment 5)

Embodiment 5 is the optical systems that make as after one-piece type coupled lens of the diffraction of aberration compensation optical element and the one-piece type object lens combination of diffraction, use focal length 11.02mm, light source side NA0.19, the plastic lens of one group of formation of lateral magnification-0.074 is as the one-piece type coupled lens of diffraction, and one group of plastic lens using focal length 2.2mm, CD side NA0.85, lateral magnification 0.015 is as the one-piece type object lens of diffraction.And make the face of the CD side of the one-piece type coupled lens of diffraction become diffraction surfaces, the two sides of the one-piece type object lens of diffraction is become to having the diffraction surfaces of positive diffraction efficiency with negative diffraction efficiency.The data of using optical system about the record regenerating of embodiment 5 have been shown in table 5.

Table 5

The face sequence number	r(mm)	d(mm)	Nλ	νd	Remarks
The face sequence number	r(mm)	d(mm)	Nλ	νd	Remarks		0		10.7681			Light source
1 2	27.4919 -6.3582	2.0000 10.0000	1.52469	56.5	Collimation lens		0		10.7681			Light source
1 2	27.4919 -6.3582	2.0000 10.0000	1.52469	56.5	Collimation lens	3 4	1.6162 -1.7141	3.2200 0.4207	1.52491	56.5	Object lens
5 6	∞ ∞	0.1000	1.61949	30.0	Protective seam	3 4	1.6162 -1.7141	3.2200 0.4207	1.52491	56.5	Object lens

Asphericity coefficient

	The 1st	The 2nd	The 3rd	The 4th
	The 1st	The 2nd	The 3rd	The 4th	k A ₄ A ₆ A ₈ A ₁₀ A ₁₂ A ₁₄ A ₁₆ A ₁₈ A ₂₀	-6.64490E+01 1.67874E-04	-2.79130E-01 1.87140E-04 9.71510E-06	-6.14610E-01 5.71410E-03 9.50000E-04 -1.05290E-04 2.46620E-04 -4.86960E-05 -4.08850E-06 4.50230E-06 -1.17090E-07 -1.40850E-07	-5.76940E+01 2.39310E-01 -3.94420E-01 3.25320E-01 -1.12520E-01 5.53253E-05

The diffraction surfaces coefficient

	The 2nd	The 3rd	The 4th
	The 2nd	The 3rd	The 4th	b ₂ b ₄ b ₆ b ₈ b ₁₀	4.50000E-03 -7.92940E-06	-1.90000E-02 -1.52060E-03 5.03590E-06 -2.92080E-05 1.58820E-05	-4.30000E-02

Figure 25 illustrates the index path of the record regenerating of embodiment 5 with optical system.Figure 26 be the expression present embodiment the one-piece type coupled lens of diffraction when wavelength 405 ± 5nm spherical aberration and the curve of axial chromatic aberration, Figure 27 be the one-piece type object lens of diffraction of expression present embodiment when wavelength 405 ± 5nm spherical aberration and the curve of axial chromatic aberration, Figure 28 be expression make record after the one-piece type object lens combination of the one-piece type coupled lens of diffraction and diffraction use again optical system when wavelength 405 ± 5nm spherical aberration and the curve of axial chromatic aberration.

Can clearly be seen that from Figure 26, the one-piece type coupled lens of the diffraction of embodiment in the incident light wavelength when long wavelength side changes, the focal position is to the over-compensation side shifting, when the short wavelength changed, the focal position was to the under-compensation side shifting in the incident light wavelength.And can know from Figure 27 and to see that when long wavelength side changed, the focal position was to the under-compensation side shifting in the incident light wavelength for the one-piece type object lens of the diffraction of present embodiment, when short wavelength side changed, the focal position was to over-compensation one side shifting in the incident light wavelength.And can know from Figure 28 and to see that the record regenerating that makes after the one-piece type object lens combination of the one-piece type coupled lens of diffraction and diffraction changes hardly with optics system focus position and Wavelength-independent ground.

Figure 29 illustrates the temperature characterisitic of the record regenerating of present embodiment with optical system.As from know Figure 29 find out, by making high NA plastic objective lens and aberration compensation optical element combination, can keep good optically focused characteristic in the temperature ranges of-20 to+85 degree.

Figure 30 illustrates the wavelength characteristic of the record regenerating of present embodiment with optical system.As from know Figure 30 find out, by making the combination of the one-piece type coupled lens of high NA plastic objective lens and diffraction, also can keep good optically focused rerum natura even the wavelength variations of 2nm takes place wavelength.

(embodiment 6)

Embodiment 6 makes as the one-piece type collimation lens of the diffraction of aberration compensation optical element, mating type double lens as Chromatically compensated optical element, optical system after the one-piece type object lens combination of diffraction, using focal length is 7mm, NA is that the plastic lens of one group of formation of 0.375 is as the one-piece type collimation lens of diffraction, use focal length 2.2mm, the plastic lens of one group of formation of CD side NA0.85 is as the one-piece type object lens of diffraction, the mating type double lens makes negative lens (the HOYA society system of Abbe number 25.7 in advance, FD110) and the positive lens of Abbe number 46.6 (HOYA society system, TAF5) combine, refractive index is zero.And the face that makes the CD side of the one-piece type collimation lens of diffraction becomes to having the diffraction surfaces of negative diffraction efficiency, makes the face of the light source side of the one-piece type object lens of diffraction become the diffraction surfaces with positive diffraction efficiency.The data of the record regenerating of relevant embodiment 6 with optical system have been shown in table 6.

Table 6

Asphericity coefficient

	The 1st	The 2nd	The 3rd	The 4th
	The 1st	The 2nd	The 3rd	The 4th	k A ₄ A ₆ A ₈ A ₁₀ A ₁₂ A ₁₄ A ₁₆ A ₁₈ A ₂₀	0.00000E+00 -5.06733E-04 9.24750E-06	-9.51220E-01 -8.21400E-04 -1.66060E-05	-5.88780E-01 2.13550E-03 1.15480E-03 6.20520E-05 8.80180E-05 -3.10960E-05 -4.08720E-07 3.55430E-06 -4.12270E-07 -8.96590E-08	-3.07710E+01 2.44047E-01 -4.09301E-01 3.28799E-01 -1.07700E-01 5.53253E-05

The diffraction surfaces coefficient

	The 2nd	The 6th
	The 2nd	The 6th	b ₂ b ₄ b ₆ b ₈ b ₁₀	1.00000E-02 -3.76180E-05 5.50180E-06	-1.20000E-02 -2.51740E-03 2.72100E-04 -2.22940E-05 -1.57370E-05

Figure 31 illustrates the index path of the record regenerating of embodiment 6 with optical system.Figure 32 makes

Optical system after the combination of the one-piece type object lens of one-piece type collimation lens of the diffraction of present embodiment and diffraction when wavelength 405 ± 5nm spherical aberration and the curve of axial chromatic aberration, Figure 33 be expression make after the one-piece type object lens combination of the one-piece type collimation lens of diffraction, mating type double lens and diffraction record regenerating with optical system when wavelength 405 ± 5nm spherical aberration and the curve of axial chromatic aberration.

Can know from Figure 32 and to find out, make optical system after the one-piece type object lens combination of the one-piece type collimation lens of diffraction of present embodiment and diffraction in the incident light wavelength when long wavelength side changes, the focal position is to the over-compensation side shifting, when short wavelength side changed, the focal position was to the under-compensation side shifting in incident wavelength.And can know from Figure 33 and to find out, the record regenerating after the one-piece type object lens combination of the one-piece type collimation lens of diffraction, mating type double lens and diffraction is changed hardly with optics system focus position and Wavelength-independent ground.

Figure 34 illustrates the temperature characterisitic of the record regenerating of present embodiment with optical system, as from can know Figure 34 see, by making high NA plastic objective lens and aberration compensation optical element combination, can keep good optically focused characteristic in the temperature range of-20 to+85 degree.

Figure 35 illustrates the wavelength characteristic of the record regenerating of present embodiment with optical system, as from know Figure 35 see, by making the one-piece type collimation lens combination of high NA plastic objective lens, mating type double lens and diffraction, also can keep good optically focused characteristic even the variation of 2nm takes place wavelength.In addition, in Figure 35, " record regenerating optical system " expression makes the optical system after the one-piece type object lens combination of the one-piece type collimation lens of diffraction, mating type double lens and diffraction, and " COL+OBJ " expression makes the optical system after one-piece type collimation lens of diffraction and the one-piece type object lens combination of diffraction.

(embodiment 7)

Embodiment 7 is record regenerating optical systems of the best light pick-up device of being applicable to Fig. 3.Present embodiment is the record regenerating optical system that can carry out recording of information regeneration to high density DVD, DVD and CD with object lens compatiblely, disposes as the one-piece type collimation lens of the diffraction of aberration compensation optical element in royal purple semiconductor laser that high density DVD uses and the light path between the one-piece type object lens of diffraction.And when the recording of information regeneration of carrying out corresponding DVD and CD, make from DVD and incide on the one-piece type object lens of diffraction with the divergent beams that semiconductor laser penetrates, make then on its information recording surface separately that focuses on DVD and CD with semiconductor laser and CD.

Use focal length as 7mm, NA be the plastic lens of one group of formation of 0.321 as the one-piece type collimation lens of diffraction, the plastic lens of one group of formation that uses focal length 2.0mm is as the one-piece type object lens of diffraction.And the NA of the one-piece type object lens of diffraction is 0.85 to high density DVD record regenerating the time, is 0.65 to the DVD record regenerating time, is 0.50 to the CD record regenerating time.And the face that makes the CD side of the one-piece type collimation lens of diffraction becomes to having the diffraction surfaces of negative diffraction efficiency, makes the face of the semiconductor laser side of the one-piece type object lens of diffraction become the diffraction surfaces with positive diffraction efficiency.

The data of using optical system about the record regenerating of embodiment 7 have been shown in table 7, have shown the index path of the record regenerating of present embodiment with optical system at Figure 36 to Figure 38.In the lens data of table 7, determine the diffraction coefficient of diffraction surfaces of the light source side of object lens, so that from the light incident of royal purple semiconductor laser the time, can produce second-order diffraction light.When the light of the infrared light semiconductor laser that the red light semiconductor laser of using from DVD, CD use is incident on the diffraction surfaces of determining like this, produce 1 order diffraction light, and because the diffraction coefficient reference wavelength (the manufacturing wavelength of so-called diffraction structure) of the face of the light source side of object lens is set at 380nm, so that from the light of royal purple optical semiconductor laser, the light of red light semiconductor laser, the light of infrared light semiconductor laser obtain high diffraction efficiency in wavelength coverage separately.

Table 7

[high density DVD]

The face sequence number	r(mm)	d(mm)	Nλ	νd	Remarks
The face sequence number	r(mm)	d(mm)	Nλ	νd	Remarks		0		6.0081			Light source
1 2	12.9312 -2.9472	2.0000 10.0000	1.52469	56.5	Collimation lens		0		6.0081			Light source
1 2	12.9312 -2.9472	2.0000 10.0000	1.52469	56.5	Collimation lens	3 4	1.5008 -4.0931	2.2000 0.6202	1.52469	56.5	Object lens
5 6	∞ ∞	0.1000	1.61949	30.0	Protective seam	3 4	1.5008 -4.0931	2.2000 0.6202	1.52469	56.5	Object lens

[DVD]

The face sequence number	r(mm)	d(mm)	Nλ	νd	Remarks
The face sequence number	r(mm)	d(mm)	Nλ	νd	Remarks		0		28.0316			Light source
3 4	1.5008 -4.0931	2.2000 0.6202	1.50661	56.5	Object lens		0		28.0316			Light source
3 4	1.5008 -4.0931	2.2000 0.6202	1.50661	56.5	Object lens	5 6	∞ ∞	0.1000	1.57756	30.0	Protective seam

[CD]

The face sequence number	r(mm)	d(mm)	Nλ	νd	Remarks
The face sequence number	r(mm)	d(mm)	Nλ	νd	Remarks		0		16.6423			Light source
3 4	1.5008 -4.0931	2.2000 0.6202	1.50500	56.5	Object lens		0		16.6423			Light source
3 4	1.5008 -4.0931	2.2000 0.6202	1.50500	56.5	Object lens	5 6	∞ ∞	0.1000	1.57062	30.0	Protective seam

Asphericity coefficient

	The 1st	The 2nd	The 3rd	The 4th
	The 1st	The 2nd	The 3rd	The 4th	k A ₄ A ₆ A ₈ A ₁₀ A ₁₂ A ₁₄ A ₁₆ A ₁₈ A ₂₀	0.00000E+00 -7.07536E-04 9.95558E-06	-9.57120E-01 -6.98220E-04 2.82640E-06	-5.00280E-01 6.18070E-03 -1.09230E-03 1.87750E-03 -2.46160E-04 -3.21180E-04 1.31040E-04 -1.15460E-05 5.97860E-06 -2.93260E-06	-1.16557E+02 8.27146E-02 -4.63821E-02 -5.32148E-03 6.93290E-03 6.14497E-04 4.59428E-05 -4.70737E-04

The diffraction surfaces coefficient

	The 2nd	The 3rd
	The 2nd	The 3rd	b ₂ b ₄ b ₆ b ₈ b ₁₀	3.50000E-02 1.46310E-04 -3.51000E-06	-2.50000E-02 -1.66580E-03 2.26340E-05 -1.07980E-04 -1.40910E-05

Figure 36 is the index path when the recording of information regeneration of carrying out corresponding high density DVD, and Figure 37 is the index path when the recording of information regeneration of carrying out corresponding DVD, and Figure 38 is the index path when the recording of information regeneration of carrying out corresponding CD.Figure 39 be the expression present embodiment the one-piece type collimation lens of diffraction when wavelength 405 ± 5nm spherical aberration and the curve of axial chromatic aberration, Figure 40 be the one-piece type lens of the diffraction of present embodiment when wavelength 405 ± 5nm spherical aberration and the curve of axial chromatic aberration, Figure 41 is the curve of the spherical aberration of the one-piece type object lens of the diffraction of present embodiment when wavelength 650nm, and Figure 42 is the curve of the spherical aberration of the one-piece type object lens of diffraction when wavelength 780nm of expression present embodiment.Figure 43 be expression make after the one-piece type object lens combination of aberration compensation optical element and diffraction record regenerating with optical system when wavelength 405 ± 5nm spherical aberration and the curve of axial chromatic aberration.

From Figure 39, can know and find out, the diffraction one collimation lens of present embodiment from the light wavelength of royal purple photosemiconductor laser when long wavelength side changes, the focal position is to the over-compensation side shifting, from the light wavelength of royal purple optical semiconductor laser when short wavelength side changes, the focal position is to the under-compensation side shifting.

Can clearly be seen that from Figure 40, the one-piece type object lens of the diffraction of present embodiment from the light wavelength of royal purple optical semiconductor laser when long wavelength side changes, the focal position is to the under-compensation side shifting, from the light wavelength of royal purple semiconductor laser when short wavelength side changes, the position of focus is to the over-compensation side shifting.

In addition, can know from Figure 43 and to find out, make the record regenerating optical system after the one-piece type object lens combination of aberration compensation optical element and diffraction, even during from the wavelength variations of royal purple optical semiconductor laser, the focal position is variation hardly also.

Temperature characterisitic when the record regenerating that figure 44 illustrates present embodiment carries out corresponding highdensity recording of information regeneration with optical system.As from know Figure 44 see, by making high NA plastic objective lens and aberration compensation optical element combination, can keep good optically focused characteristic in the temperature ranges of-20 to+85 degree.

Wavelength characteristic when the record regenerating that figure 45 illustrates present embodiment carries out the recording of information regeneration of corresponding high density DVD with light-source system.As know from Figure 45 see, by making high NA plastic objective lens and aberration compensation optical element combination, even when the variation of 2nm takes place wavelength, also can keep good optically focused characteristic.

(embodiment 8)

Embodiment 8 is record regenerating optical systems of the best light pick-up device of being applicable to Figure 46.Present embodiment is the record regenerating optical system that can carry out recording of information regeneration to high density DVD, the DVD of the density 0.6mm of protective seam and CD with object lens compatiblely, disposes the one-piece type collimation lens of diffraction as the aberration compensation optical element in the light path between royal purple optical semiconductor laser that high density DVD uses and the DVD usefulness red light semiconductor laser.And when carrying out, make from CD and incide on the one-piece type object lens of diffraction, make then on its information recording surface that focuses on CD with the divergent beams that red light semiconductor laser penetrates to the regeneration of the recording of information of CD.

Use focal length as 15mm, NA be the plastic lens of one group of formation of 0.173 as the one-piece type collimation lens of diffraction, the plastic lens of one group of formation that uses focal length 3.077mm is as the one-piece type object lens of diffraction.And the NA of the one-piece type object lens of diffraction is 0.65 to high density DVD record regenerating the time, is 0.61 to the DVD record regenerating time, is 0.50 to the CD record regenerating time.And the face that makes the CD side of the one-piece type collimation lens of diffraction becomes to having the diffraction surfaces of negative diffraction efficiency, makes the face of the semiconductor laser side of the one-piece type object lens of diffraction become the diffraction surfaces with positive diffraction efficiency.

The data of using optical system about the record regenerating of embodiment 8 have been shown in table 8, in the lens data of table 8, determine the diffraction coefficient of diffraction surfaces of the light source side of object lens, so that from the light incident of royal purple optical semiconductor laser the time, can produce second-order diffraction light.When the light of the infrared light semiconductor laser that the red light semiconductor laser of using from DVD, CD use is incident on the diffraction surfaces of determining like this, produce 1 order diffraction light, and because the diffraction coefficient reference wavelength (the manufacturing wavelength of so-called diffraction structure) of the face of the light source side of object lens is set at 380nm, so that in wavelength coverage separately, obtain high diffraction efficiency from the light of royal purple optical semiconductor laser, the light of red light semiconductor laser, the light of infrared light semiconductor laser.

The one-piece type collimation lens of diffraction is configured in the parallel beam that the light beam from royal purple optical semiconductor laser and red light semiconductor laser passes through together, two sides when the regeneration of the recording of information of corresponding high density DVD and during the information record regenerating of corresponding DVD, the aberration compensation optical element of the function that defocuses error the when function that the spherical aberration when having compensates changes and compensate semi-conductor's laser die are beated works, and the face diffraction surfaces coefficient of the CD side of the one-piece type collimation lens of definite diffraction, so that from the laser incident of royal purple optical semiconductor laser the time, can produce three order diffraction light.On the diffraction surfaces after determining like this, when from the light incident of the laser instrument of red light semiconductor, produce second-order diffraction light.Because the reference wavelength (the manufacturing wavelength that also claims diffraction structure) of the diffraction surfaces coefficient of the light source side of object lens is set at 415nm, so can in wavelength coverage separately, obtain high-level efficiency from the light of royal purple optical semiconductor laser with from the light of red light semiconductor laser.

The one-piece type object lens of the diffraction of present embodiment at bluish violet light laser and red light semiconductor laser light when long wavelength side changes, the focal position is to the over-compensation side shifting, from royal purple optical semiconductor laser and red light semiconductor laser light wavelength when short wavelength side moves, the focal position is to the under-compensation side shifting.The one-piece type object lens of the diffraction of present embodiment from the light wavelength of royal purple optical semiconductor laser when long wavelength side changes, the focal position is to under-compensation one side shifting, from the light wavelength of royal purple optical semiconductor laser and red light semiconductor laser when short wavelength side changes, the focal position is to the over-compensation side shifting.

Make the one-piece type object lens of diffraction of wavelength dependency and the record regenerating optical system after the one-piece type collimation lens combination of diffraction with such focal position, even during from royal purple optical semiconductor laser and the variation of red light semiconductor laser light wavelength, the focal position also changes hardly.

Temperature characterisitic when the temperature characterisitic the when record regenerating that figure 47 illustrates present embodiment carries out the recording of information regeneration of corresponding high density DVD with optical system, the record regenerating that figure 28 illustrates present embodiment are carried out the information record regenerating of corresponding DVD with optical system.As from know Figure 47 and 48 see, can-20 the degree to+50 the degree temperature ranges in keep good temperature characterisitic.

In Figure 47 and Figure 48, during wave-front aberration when accounting temperature changes, considered that plastic lens refractive index relative temperature changes that (its rate of change is-1.1 * 10 ^-4/ the degree and the wavelength variations of semiconductor laser (its rate of change to the royal purple optical semiconductor laser is+the 0.05nm/ degree, to red light semiconductor laser be+0.2nm), and do not consider the change of shape of plastic lens.

In Figure 49, wavelength characteristic when the record regenerating that shows present embodiment carries out the recording of information regeneration of corresponding high density DVD with optical system, the wavelength characteristic the when record regenerating that figure 50 illustrates present embodiment carries out the recording of information regeneration of corresponding DVD with optical system.As from know Figure 49 and Figure 50 see, also can keep good optically focused characteristic even to the regeneration of any video disc recording the time, cause the 2nm wavelength variations.

In Figure 49 and Figure 50, because during the wave-front aberration when calculating is beated the wavelength variations that causes because of mould, irrelevant with the focusing of object lens, (to the royal purple optical semiconductor laser is 4.05nm so object lens are fixed on the semiconductor laser reference wavelength, to red light semiconductor laser is 655nm) time best image point position on, the wave-front aberration value among Figure 49 and Figure 50 comprises because of what best image point position mobile caused and defocuses component.

Table 8

[high density DVD]

The face sequence number	r(mm)	d(mm)	Nλ	νd	Remarks
The face sequence number	r(mm)	d(mm)	Nλ	νd	Remarks		0		14.1147			Light source
1 2	22.7830 -5.0671	2.0000 10.0000	1.52469	56.5	Collimation lens		0		14.1147			Light source
1 2	22.7830 -5.0671	2.0000 10.0000	1.52469	56.5	Collimation lens	3 4	2.3622 -17.6862	2.0000 1.4434	1.52469	56.5	Object lens
5 6	∞ ∞	0.6000	1.53017	64.2	Protective seam	3 4	2.3622 -17.6862	2.0000 1.4434	1.52469	56.5	Object lens

[DVD]

The face sequence number	r(mm)	d(mm)	Nλ	νd	Remarks
The face sequence number	r(mm)	d(mm)	Nλ	νd	Remarks		0		16.4067			Light source
1 2	22.7830 -5.0671	2.0000 10.0000	1.50650	56.5	Collimation lens		0		16.4067			Light source
1 2	22.7830 -5.0671	2.0000 10.0000	1.50650	56.5	Collimation lens	3 4	2.3622 -17.6862	2.0000 1.6755	1.50650	56.5	Object lens
5 6	∞ ∞	0.6000	1.51436	64.2	Protective seam	3 4	2.3622 -17.6862	2.0000 1.6755	1.50650	56.5	Object lens

[CD]

The face sequence number	r(mm)	d(mm)	Nλ	νd	Remarks
The face sequence number	r(mm)	d(mm)	Nλ	νd	Remarks		0		52.4247			Light source
3 4	2.3622 -17.6862	2.0000 1.3435	1.50497	56.5	Object lens		0		52.4247			Light source
3 4	2.3622 -17.6862	2.0000 1.3435	1.50497	56.5	Object lens	5 6	∞ ∞	1.2000	1.51107	64.2	Protective seam

Asphericity coefficient

	The 1st	The 2nd	The 3rd	The 4th
	The 1st	The 2nd	The 3rd	The 4th	k A ₄ A ₆ A ₈ A ₁₀ A ₁₂	-1.15676E+01	-9.99570E-01 -1.12430E-04	-6.70590E-01 2.78110E-03 9.77230E-04 -2.45380E-04 3.75040E-05 -3.12700E-06	-1.75087E+02 8.50063E-03 -1.92307E-03 -7.96272E-06 2.23071E-05

The diffraction surfaces coefficient

	The 2nd	The 3rd
	The 2nd	The 3rd	b ₂ b ₄ b ₆ b ₈ b ₁₀	-1.00000E-02 -4.49650E-06	-2.00000E-02 -5.56790E-04 1.47480E-04 -6.27760E-05 7.11410E-06

In the lens data of the foregoing description 1 to 8, the diffraction coefficient of the diffraction surfaces of aberration compensation optical element and object lens is that basis is except the diffraction surfaces of the object lens of embodiment 7, the requirement that can make first-order diffraction light have maximum diffraction light efficient from the light incident of royal purple semiconductor laser the time determines that the reference wavelength of diffraction surfaces is 405nm.When making actual diffraction structure, it is positive integer that the iconal of representing with these diffraction surfaces coefficients is established m, by the m of the every variation reference wavelength of diffraction surfaces coefficient the ring-shaped area ladder is set doubly.Because be when establishing m=n (n is the integer more than 2), compare during with m=1, the ring-shaped area spacing becomes its n doubly, so the diffraction efficiency that the shape error because of the ring-shaped area ladder is caused descends for a short time, the n order diffraction light that at this moment is incident in the diffraction of light light on the diffraction structure takes place in the mode with big diffraction light efficient.But because n is when excessive, diffraction efficiency becomes big to the dependence of wavelength, so n is preferably in 2 to 10 scope.

Above-mentioned table 1 to 6 in, γ (mm) represents the paraxial radius-of-curvature of each face, d (mm) presentation surface spacing, the refractive index when N λ is illustrated in 405nm, ν d is illustrated in the Abbe number on the d line.And in Fig. 7, γ (mm) represents paraxial radius-of-curvature, d (mm) the presentation surface spacing of each face, the refractive index when N λ is 405nm when being illustrated in high density DVD, the refractive index when being 650nm with DVD time the, the refractive index when being 780nm with CD the time.

In addition, in above-mentioned each table and figure, have in multiply by 10 power product representation formula on E (or e), for example E-02 (=10 ^-2) occasion of such expression.

According to the present invention, with in the optical system, can compensate the variation that changes the wave-front aberration that causes because of objective temperature at the record regenerating of the CD of the plastic objective lens of 1 group of 1 formation using high NA.Particularly do not need to detect the variation of the wave front difference of the object lens that cause because of temperature variation with moving, can make the record regenerating optical system at low cost.

And, can provide and carry record regenerating with the light pick-up device of the CD of optical system with pick up the optical disc recording/reproducing apparatus of year this light pick-up device.

The record regenerating that the wave-front aberration that can also provide best-fit to cause in the plastic objective lens temperature variation that can compensate because of one group of formation of high NA changes is with the object lens and the aberration compensation optical element of optical system.

Claims

1. one kind is used for optical information recording media is carried out the object lens of the record regenerating of recording of information and/or regeneration with optical system, comprising:

One is configured to one group one and comprise the aspherical plastic lens of at least one diffraction surfaces, forms the diffraction structure that the ladder by a plurality of concentric areas constitutes on this diffraction surfaces,

Wherein, the numerical aperture of the optic informating recording medium side of described object lens is more than or equal to 0.8 and satisfy following formula

f2＜f0＜f1

In the formula: f0 is the focal length of whole objective system from the wavelength of the light beam of light emitted the time;

F1 is the focal length at whole objective system than from the wavelength of the wavelength difference of the short regulation of wavelength of the light beam of light emitted the time;

F2 is the focal length at the whole objective system than from the wavelength of the fixed wavelength difference of the wavelength calipers of the light beam of light emitted the time,

Wherein, satisfy following formula:

0.05＜PD1/PT1＜0.7

In the formula: PD1 is the optical path difference φ that sees through on the wave front of the diffraction structure that forms on the i face of above-mentioned object lens being attached to _BiWith by φ _Bi=ni (b _2iH _i ²+ b _4iH _i ⁴+ b _6iH _i ⁶+ ...) the optical path difference function representation of definition is during apart from the function of the height hi of optical axis, by PD1=∑ (2b _2iNi) Ding Yi the diffraction efficiency as diffraction lens is the diffraction progression that has the diffraction light of maximum diffraction light quantity in the diffraction light that takes place on the diffraction structure that is being formed on the i face at this ni, b _2i, b _4i, b _6i... be respectively 2 times, 4 times, 6 times ... the optical path difference function coefficients also claims the diffraction surfaces coefficient; PT1 is the diopter of whole objective system,

Wherein f0, f1, f2, φ _BiWith each the unit among the hi be mm, the unit of each among PD1 and the PT1 is mm ^-1

2. object lens as claimed in claim 1 is characterized in that: these object lens be used in by use that light beam that wavelength is less than or equal to 500nm writes down optical data media and/or the record regenerating optical system of regenerating information on.

3. object lens as claimed in claim 1; it is characterized in that: object lens have following wavelength characteristic: make the different light beam of at least two kinds of wavelength the two kind optical information recording medias different to protective layer thickness write down and/or several apertures of the necessary optical information recording media side of regenerating information in, on corresponding information recording surface, form a good wave front, and these object lens satisfy following formula:

f2′＜f0′＜f1′

The focal length of the whole objective system when f0 ' is the minimal wave length of the light beam at least two kinds of light beams in the formula;

F1 ' is the focal length of whole objective system when the wavelength of the wavelength difference of stipulating than the minimal wave length weak point of light beam,

F2 ' is the focal length of whole objective system when the wavelength of the wavelength difference more fixed than the minimal wave length calipers of light beam,

Wherein the unit of each among f0 ', f1 ' and the f2 ' is mm.

4. object lens as claimed in claim 3; it is characterized in that: object lens have following wavelength characteristic: make the diffraction light that has than the light beam of shorter wavelength form a good wave front on the carrier with thinner protective seam, and make the diffraction light of the light beam with long wavelength form a good wave front on the optical information recording media with thicker protective seam.

5. object lens as claimed in claim 3; it is characterized in that: minimal wave length is less than or equal to 500nm, and object lens have in the necessary numerical aperture more than or equal to 0.80 optical information recording media side of the enterprising line item of optical information recording media with thin protective layer and/or regenerating information.

6. object lens as claimed in claim 1 is characterized in that: at least one diffraction surfaces satisfies following formula in a plurality of diffraction surfaces of object lens:

0＜|(Ph/Pf)-2|＜10，

In the formula: Pf is the distance on the direction vertical with optical axis between the adjacent ring-shaped area of the maximum numerical aperture place of carrier side diffraction surfaces, and

Ph is the distance on the direction vertical with optical axis between as half the adjacent ring-shaped area of numerical aperture place diffraction surfaces of the maximum numerical aperture of carrier side,

Wherein the unit of each among Pf and the Ph is mm.

7. object lens as claimed in claim 1 is characterized in that: satisfy following formula:

0.8≤d/f≤2.4

In the formula: d is the thickness of object lens on optical axis, and

F is a focal length,

Wherein the unit of each among d and the f is mm.

8. object lens as claimed in claim 1 is characterized in that: the ring-type diffraction structure is formed on two faces of object lens.

9. object lens as claimed in claim 1, it is characterized in that: the n order diffraction diffraction of light efficient of provision wavelengths is greater than the diffraction efficiency of the diffraction light of any other grade that is produced by diffraction structure, and object lens with n order diffraction optical convergence on information recording surface so that optical information recording media is write down and/or regenerating information, wherein n is the integer except 0,1 and-1.

10. object lens as claimed in claim 1 is characterized in that: the single lateral magnification M of object lens satisfies following formula:

0＜M＜0.25。

11. object lens as claimed in claim 1 is characterized in that: be formed on diffraction structure on the object lens have form by the formation graphics art that uses electron beam or by using the molded jagged diffraction structure that glitters that forms of formation graphics art of electron beam.

12. object lens as claimed in claim 1 is characterized in that: satisfy following formula:

0.10＜PD1/PT1＜0.7。

13. a use the optical information recording media at least two kinds of different recording density write down and/or the optical system of the record regenerating of regenerating information on object lens, comprising:

A plastic lens, this plastic lens constitutes one group with an element, and comprising at least one aspheric surface and the diffraction surfaces that has the diffraction structure of forming by a plurality of concentric area ladders above at least one, described concentric area stepped design becomes: make the diffraction progression of the diffraction light that has maximum diffraction efficiency when having the light beam incident of long wavelength at least two light beams in the diffraction light that produces lower than the diffraction progression with maximum diffraction efficiency in the diffraction light that produces when having the light beam incident of minimal wave length;

Object lens satisfy following formula:

f2″＜f0″＜f1″

" the focal length of the whole objective system when being the minimal wave length of the light beam at least two light beams in the formula: f0;

F1 " is the focal length of the whole objective system when the wavelength difference of stipulating than the minimal wave length weak point of light beam;

F2 " be the focal length of the whole objective system when deciding the wavelength of wavelength difference than the minimal wave length calipers of light beam,

Wherein f0 ", f1 " and t2 " in each unit be mm.

14. object lens as claimed in claim 13 is characterized in that: the wavelength coverage of the shortest wavelength is 380nm to 420nm, and the wavelength coverage of long wavelength is 630nm to 670nm.

15. object lens as claimed in claim 14, it is characterized in that: n1 is the diffraction progression that has the diffraction light of maximum diffraction efficiency when being the light beam incident of 380nm to 420nm in the diffraction light that produces when wavelength, and n2 is the diffraction progression that has the diffraction light of maximum diffraction efficiency when being the light beam incident of 630nm to 670nm in the diffracted beam that produces when wavelength, the combination of n1 and n2 is (n1, n2)=(2,1), (3,2), (4,2), (5,3), (6,4), (7,4), (8,5), (9,6), in (10,6).

16. object lens as claimed in claim 14 is characterized in that: another wavelength coverage than long wavelength is 760nm to 800nm.

17. object lens as claimed in claim 16, it is characterized in that: n1 is the diffraction progression that has the diffraction light of maximum diffraction efficiency in the diffraction light that the light beam incident that is 380nm to 420nm produces when wavelength, n2 is the diffraction progression that has the diffraction light of maximum diffraction efficiency when being the light beam incident of 630nm to 670nm in the diffraction light that produces when wavelength, and n3 is the diffraction progression of the diffraction light with maximum diffraction efficiency in the diffraction light that produces when being the light beam incident of 760nm to 800nm when wavelength, n1, the combination of n2 and n3 be (n1, n2, n3)=(2,1,1), (4,3,2), (6,4,3), (8,5,4), (10,6,5) in one.

18. object lens as claimed in claim 13; it is characterized in that: object lens have one for the optical information recording media with tidemark density being write down and/or regenerating information is necessary, the numerical aperture of the optical information recording media side of 0.60 to 0.70 regulation; these object lens are the diffraction light that 0.55 to 0.65nm protective seam is assembled the light beam with minimal wave length by thickness, so that form good wave front on the information recording surface of the optical information recording media with tidemark density.

19. object lens as claimed in claim 13; it is characterized in that: object lens have one for the optical information recording media with tidemark density being write down and/or regenerating information is necessary, the numerical aperture of the optical information recording media side of regulation greater than 0.80; these object lens are the diffraction light that 0.07 to 0.13nm protective seam is assembled the light beam with minimal wave length by thickness, so that form good wave front on the information recording surface of the optical information recording media with tidemark density.

20. object lens as claimed in claim 13 is characterized in that: the single lateral magnification M of object lens satisfies following formula:

0＜M＜0.25。

21. object lens as claimed in claim 13 is characterized in that: the diffraction structure that is formed on the diffraction object lens has by the electron beam graph formation technology molded jagged diffraction structure that glitters that forms of mould that form or form explained hereafter by electron beam graph.