CN102667932A - Objective lens for optical pickup device and optical pickup device - Google Patents

Objective lens for optical pickup device and optical pickup device Download PDF

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Publication number
CN102667932A
CN102667932A CN2010800584703A CN201080058470A CN102667932A CN 102667932 A CN102667932 A CN 102667932A CN 2010800584703 A CN2010800584703 A CN 2010800584703A CN 201080058470 A CN201080058470 A CN 201080058470A CN 102667932 A CN102667932 A CN 102667932A
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China
Prior art keywords
object lens
lens
information recording
formula
max
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CN2010800584703A
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Chinese (zh)
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小野雄树
木村彻
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Konica Minolta Opto Inc
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Konica Minolta Opto Inc
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Publication of CN102667932A publication Critical patent/CN102667932A/en
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B13/00—Optical objectives specially designed for the purposes specified below
    • G02B13/16—Optical objectives specially designed for the purposes specified below for use in conjunction with image converters or intensifiers, or for use with projectors, e.g. objectives for projection TV
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
    • G11B7/1372—Lenses
    • G11B7/1374—Objective lenses

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  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • General Physics & Mathematics (AREA)
  • Optical Head (AREA)
  • Lenses (AREA)
  • Moving Of The Head For Recording And Reproducing By Optical Means (AREA)
  • Optical Recording Or Reproduction (AREA)

Abstract

Disclosed are an objective lens for an optical pickup device and an optical pickup device capable of recording and playing information upon an optical disc, comprising a multilayered information recording surface, compactly and inexpensively. With the objective lens being a single lens, the image side numerical aperture (NA) having a value between 0.8 and 0.95, inclusive, and at room temperature (25+-3 DEG C), a first maximum of the offense against the sine condition (OSC) for the magnification (M) that satisfies the formula (1) is taken at the pupil radius (H1), and a second maximum thereof is taken at the pupil radius (H2), such that the formula (2) is satisfied when the pupil radius (H3) is greater than or equal to 0.9, and the derivative F(h) of the offense against the sine condition (OSC) satisfies the formulae (3)-(5): -0.003 = M = 0.003 (1) H1 < H2 < H3 (2) F(h) < 0.0 (h < H1) (3) F(h) > 0.0 (H1 < h < H2) (4) F(h) < 0.0 (H2 < h < H3) (5) Wherein the pupil radii (H1, H2, H3) are relative values when the mean radius of the objective lens is 1.

Description

Object lens that optical take-up apparatus is used and optical take-up apparatus
Technical field
The present invention relates to carry out object lens and the optical take-up apparatus that the optical take-up apparatus of recording of information and/or reproduction is used to the CD that has information recording surface more than three layers at thickness direction.
Background technology
Be well known that: the high density optical disc systems of using the blue purple semiconductor laser about wavelength 400nm to carry out recording of information and/or reproduction (following handle " record and/or reproduction " is recited as " recoding/reproduction "); The NA0.85 of one of which example; The CD that carries out information recording/regenerating with the specification of optical source wavelength 405nm for so-called Blu-ray Disc (below be called BD), DVD (NA0.6; Optical source wavelength 650nm; Memory capacity 4.7GB) CD of the diameter 12cm of identical size, can each layer the information of record 25GB.
Mostly existing BD is to have one deck or two-layer information recording surface, wants to preserve more multidata market demands according to a slice BD so that the BD with information recording surface more than three layers also practicability as the research of target in progress.And because the NA of the light beam when carrying out information recording/regenerating is greatly to 0.85; So in having the BD of a plurality of information recording surfaces; If an information recording surface is paid minimum spherical aberration; Then the spherical aberration of different other information recording surfaces of transparency carrier thickness just increases, and the problem that can not appropriately carry out information recording/regenerating is arranged.The problem of this spherical aberration is that the quantity of information recording surface more (promptly arriving the big more with the interval apart from maximum information recording surface to the surface apart from minimum information recording surface of surface) is just more obviously changed.
To this, patent documentation 1 discloses through making the coupled lens that is configured between light source and the object lens move the magnification that changes object lens at optical axis direction, can carry out the light beam that has suppressed three grades of spherical aberrations the optical take-up apparatus of optically focused for selected information recording surface.In this instructions, be called " focusing saltus step (Off オ one カ ス ジ ヤ Application プ) " to the information recording surface that should carry out information recording/regenerating from any information recording surface to the action that other information recording surfaces change sometimes.
The prior art document
Patent documentation
Patent documentation 1: No. 4144763 instructions of (Japan) special permission
Patent documentation 2: (Japan) spy opens the 2009-211775 communique
Summary of the invention
Invent problem to be solved
But the optical take-up apparatus of above-mentioned patent documentation 1 record is for example in order to carry out information recording/regenerating to the CD with information recording surface more than three layers, in selecting said CD, just needs the displacement of lengthening coupled lens arbitrarily during information recording surface.Elongated when the displacement of coupled lens, then the optical path length from the light source to object lens is just elongated, and the problem that can not seek the optical take-up apparatus miniaturization is for example arranged.And owing to need to drive the large-scale actuator of coupled lens, so the problem that has cost also to increase.Particularly for the slim optical take-up apparatus that requires miniaturization since the restriction that has the optical length from the light source to object lens not extend more obviously change so be difficult to tackle problem with BD of information recording surface more than three layers.
The object lens of patent documentation 2 have following problem.
(1) object lens of patent documentation 2 are owing to proofreading and correct the sine condition of design magnification, so there is the residual high-order spherical aberration when focusing saltus step to become big tendency in the whole zone of effective radius.Promptly because the ratio (about 5:1) of the three grade spherical aberration of the ratio of three grades of spherical aberrations during magnification change and Pyatyi spherical aberration during from the cover glass variation in thickness and Pyatyi spherical aberration has big departing from, so the object lens of patent documentation 2 are for maximum to differ from that three layer or more the information recording surface optically focused of BD bigger than two-layer BD uses be inappropriate to the transparency carrier thickness of information recording surface light beam.
The variable quantity of three grades of spherical aberrations during (2) owing to magnification change is little, so the object lens of patent documentation 2 just need big coupled lens amount of movement when the focusing saltus step, therefore, uses just improper for slim optical take-up apparatus.
The present invention has considered the problems referred to above and has developed; Purpose is the object lens and the optical take-up apparatus that provide a kind of optical take-up apparatus to use; Even in focusing also high-order spherical aberration such as not residual Pyatyi spherical aberration during saltus step; Can reduce the amount of movement of coupled lens, information recording/regenerating is carried out for the CD with multi-layered information recording face in compactness and low-cost one side on one side.
In this instructions, " transparency carrier thickness " is to inject the distance of face to information recording surface from the light beam of CD, has in the CD of a plurality of information recording surfaces at thickness direction, and transparency carrier thickness of information recording surface is different each other separately for they.Usually the object lens used of optical take-up apparatus are and the cover glass combination of specific thickness, and are minimum and decide (also being called the design cover thickness of glass to the thickness of this cover glass) by the correcting state of spherical aberration in order to make spherical aberration.The design cover thickness of glass has the identical situation of transparency carrier thickness with any information recording surface of CD, and condition of different is also arranged.The characteristic of object lens also changes because the thickness of cover glass changes then, so when the object lens characteristic that the discussion optical take-up apparatus is used, just need also consider cover glass thickness together.Therefore, this instructions uses the language of " cover glass " when the relevant object lens characteristic of narration, with " transparency carrier " difference of CD.(and by the way, though use " cover glass " this classical Chinese, it is glass that cover glass thickness is not limited to, and also can be resin).
The technical scheme of dealing with problems
The object lens of content of the present invention 1 record are to carry out the object lens that the optical take-up apparatus of recording of information and/or reproduction is used; Optical take-up apparatus has the wavelength X 1 of ejaculation (light source and the object lens of 390nm＜λ 1＜415nm) light beam; CD has the mutual different information recording surface of the distance (transparency carrier thickness) of injecting face to light beam more than three layers at thickness direction; Select in the said CD information recording surface arbitrarily; The light beam of the wavelength X 1 that penetrates from said light source through the information recording surface optically focused of said object lens, wherein to said selection
Said object lens are single element lens,
Picture number formulary value aperture (NA) is more than 0.8, below 0.95,
Under normal temperature (25 ± 3 ℃) environment; The sine condition violation amount of the magnification M of satisfied (1) formula is got first maximum value at pupil radius H1 respectively and is got second maximum value at pupil radius H2; And set 0.9 to pupil radius H3 when above; Satisfy (2) formula, and the derivative φ (h) of sine condition violation amount satisfies (3) ~ (5) formula.
－0.003≤M≤0.003 （1）
H1＜H2＜H3 （2）
φ（h）＜0.0（h＜H1） （3）
φ（h）＞0.0（H1＜h＜H2） （4）
φ（h）＜0.0（H2＜h＜H3） （5）
And said pupil radius H1, H2, H3 are the relative values that is set to the effective radius of said object lens at 1 o'clock.
Be fit to that the desired characteristic of object lens of BD is following two at least more than three layers.
Residual high-order spherical aberration during (characteristic 1) focusing saltus step is little.
The amount of movement of (characteristic 2) coupled lens when focusing saltus step is little.
The wholwe-hearted result who discusses of present inventors has found to be suitable for having the object lens of BD more than three layers that in practicality, can tolerate above-mentioned (characteristic 1) and (characteristic 2) level.Below be described in detail.
About (characteristic 1)
Present inventors discuss in the design of object lens, do not receive to satisfy the constraint of the prior art general knowledge of sine condition, can not solve existing technical matters through destroying sine condition.Therefore; Recognize shown in patent documentation 2 such; When being set at negative (injecting diverging light) to a design magnification, and when the sine condition that satisfies the design magnification for the whole zone in effective radius, and when setting the correcting state of coma; Then focusing during saltus step residual high-order spherical aberration become excessive, and the ratio (about 5:1) of the three grade spherical aberration of the ratio of three grades of spherical aberrations during magnification change and Pyatyi spherical aberration during from the cover glass variation in thickness and Pyatyi spherical aberration has big departing from.According to this opinion and present inventors find, in the said magnification M that satisfies (1) formula, making sine condition violate measurer through the position at the second pupil radius H2 has second maximum value, the high-order spherical aberration in the time of then can effectively suppressing to focus saltus step.
About (characteristic 2)
Coupled lens amount of movement when focusing saltus step in order to dwindle just needs to increase the spherical aberration variable quantity of relative magnification change.The result that present inventors discuss finds; In the said magnification M that satisfies (1) formula; Make sine condition violate measurer through position second maximum value is arranged in second pupil radius; High-order spherical aberration in the time of not only can effectively suppressing to focus saltus step, but also can increase three grades of spherical aberration variable quantities of relative magnification change.
Stability height and the desired characteristic of making easily of object lens have following two at least.
(characteristic 3) even relative optical surface (is called the face displacement) owing to foozle when the direction of light shaft positive cross has displacement to depart from, coma is also constant too much.
(characteristic 4) even relative optical surface has when departing from (being called the lens thickness error) owing to foozle at optical axis direction, spherical aberration is also constant too much.
Present inventors are wholwe-hearted, and the result who discusses has found; Through not only satisfy being fit to above-mentioned (characteristic 1) and (characteristic 2) these two characteristics of BD more than three layers; And the condition below satisfying for (characteristic 3) and (characteristic 4), then can provide to be to be fit to the object lens of BD more than three layers and to be stability object lens high and that make easily.
About (characteristic 3)
According to the present invention, owing to make sine condition violate measurer first maximum value is arranged, and it is excessive to suppress second maximum value of the second pupil radius H2, so the coma generating capacity can the displacement of inhibition face the time through position at the first pupil radius H1.
About (characteristic 4)
According to the present invention; Owing to make sine condition violate measurer first maximum value is arranged through position at the first pupil radius H1; And second maximum value that can suppress the second pupil radius H2 is excessive; So therefore the generating capacity of spherical aberration in the time of can also suppressing lens thickness generation error, can provide and make easier object lens.
That kind as described above; Because the residual high-order spherical aberration of the object lens (characteristic 1) of content 1 record of the present invention when the focusing saltus step is little; The amount of movement of (characteristic 2) coupled lens when focusing saltus step is little, and (characteristic 3) can inhibition face coma generating capacity during displacement, the generating capacity of spherical aberration when (characteristic 4) can suppress lens thickness and produce error; Make easier object lens so can provide; Therefore, the object lens of the application of the invention, the optical take-up apparatus that can provide small-sized, low cost and the good CD of recording to use with information recording surface more than three layers.
The object lens of content 2 records of the present invention are in the invention of content 1 record of the present invention, the formula below satisfying.
0.19≤H1≤0.62 （6）
0.74≤H2≤0.88 （7）
0.0013≤δF／f≤0.0064（8）
Wherein, f is the focal length of the said object lens of the said wavelength X 1 under normal temperature (25 ± 3 ℃) environment, and δ F (mm) is the PV value of sine condition violation amount, is set at OSC respectively in the sine condition violation amount said pupil radius H1, H2 Min(mm), OSC Max(mm) time, represent by following (9) formula.
δF=|OSC min－OSC max| （9）
Through satisfying (6), (7) formula, can set sine condition violation amount for the best and balance realizes above-mentioned (characteristic 1 ~ 4) well.Particularly, can carry out (characteristic 3) and (characteristic 4) well,, can carry out (characteristic 1) and (characteristic 2) well through satisfying (7) formula through satisfying (6) formula.And through making δ F/f more than the lower limit of (8) formula; High-order spherical aberration undercorrection that then can be when the effect that satisfies (characteristic 1 ~ 4) prevents to focus saltus step; On the other hand; Through making below the higher limit of (8) formula the high-order spherical aberration excessive correction in the time of then can preventing to focus saltus step.Therefore, preferred satisfied (8) formula.
The object lens of content 3 records of the present invention are in the invention of content 1 of the present invention or 2 records, when said first maximum value sine condition violation amount is set at OSC Min(mm), when being set at f (mm) to the focal length of the said wavelength X 1 under normal temperature (25 ± 3 ℃) environment, satisfy (10) formula.
－0.0021≤OSC min／f≤－0.0001（10）
When OSC Min/ f is as transverse axis, and when the coma of generation was as the longitudinal axis when being shifted the object lens face, both relations can be similar to by the parabolic function of following convex form.Therefore, through OSC Min/ f is set at the lower limit that surpasses (10) formula and less than the upper limit, the coma that produces in the time of can preventing the displacement of object lens face is excessive, can carry out (characteristic 3) more well.
The object lens of content 4 records of the present invention are in the invention of content 1 of the present invention or 2 records, when said second maximum value sine condition violation amount is set at OSC Max(mm), when being set at f (mm) to the focal length of the said wavelength X 1 under normal temperature (25 ± 3 ℃) environment, satisfy (11) formula.
－0.0001≤OSC max／f≤0.0062（11）
Through setting this structure for; When the lower limit the earth that makes sine condition violation amount than (11) formula is set with the fashionable coma correction state of skew ray beam; High-order spherical aberration undercorrection in the time of then can not becoming the focusing saltus step when the upper limit that makes sine condition violation amount than (11) formula is set with the fashionable coma correction state of skew ray beam littlely, then can not become the high-order spherical aberration excessive correction; Therefore, because the high-order spherical aberration can effectively suppress to focus saltus step time the and by preferred.
The object lens of content of the present invention 5 records are to carry out the object lens that the optical take-up apparatus of recording of information and/or reproduction is used; Optical take-up apparatus has the wavelength X 1 of ejaculation (light source and the object lens of 390nm＜λ 1＜415nm) light beam; CD has the mutual different information recording surface of the distance (transparency carrier thickness) of injecting face to light beam more than three layers at thickness direction; Select in the said CD information recording surface arbitrarily; The light beam of the wavelength X 1 that penetrates from said light source through the information recording surface optically focused of said object lens, wherein to said selection
Said object lens are single element lens,
Picture number formulary value aperture (NA) is more than 0.8, below 0.95,
Under normal temperature (25 ± 3 ℃) environment; When the cover glass thickness setting that becomes the spherical aberration of the magnification M that satisfies (1) formula minimum is T (mm); Make the skew ray bundle of angle of half field-of view 1 degree when said object lens are injected; Three grades of coma CM3 (λ rms) of the point of optically focused satisfy (12) formula via said cover glass thickness T, and the Pyatyi coma CM5 (λ rms) of the point of optically focused satisfies (13) formula via said cover glass thickness T
－0.003≤M≤0.003 （1）
0＜|CM3|≤0.026 （12）
0.002≤|CM5|≤0.039 （13）
Said three grades of coma CM3 are different with the symbol of said Pyatyi coma CM5.
The invention of content 5 of the present invention is the invention of content 1 of the present invention, is not the invention that shows from sine condition violation amount but from the viewpoint of coma.The result who discusses according to present inventors; Recognize shown in patent documentation 2 such; When being set at negative (injecting diverging light) to the design magnification; And when setting the correcting state of coma when satisfying the sine condition of design magnification for the whole zone in effective radius; Then focusing during saltus step residual high-order spherical aberration become excessive, and the ratio (about 5:1) of the three grade spherical aberration of the ratio of three grades of spherical aberrations during magnification change and Pyatyi spherical aberration during from the cover glass variation in thickness and Pyatyi spherical aberration has big departing from.So find; Under the situation of injecting the light beam of the said magnification M that satisfies (1) formula; Through making the skew ray bundle of angle of half field-of view 1 degree when said object lens are injected; Three grades of coma CM3 (λ rms) of the point of optically focused satisfy (12) formula via said cover glass thickness T; The Pyatyi coma CM5 (λ rms) of the point of optically focused comes its balance optimization with satisfying (13) formula via said cover glass thickness T, the high-order spherical aberration in the time of then can effectively suppressing to focus saltus step (can make (characteristic 1) well).And then through satisfying (1) formula, (12) formula, (13) formula; Make the amount of movement of the coupled lens when focusing saltus step also little (can making (characteristic 2) well); And can inhibition face coma (can make (characteristic 3) good) during displacement, when lens thickness produces error, can also suppress spherical aberration (can make (characteristic 4) good).
The object lens of content of the present invention 6 records are to carry out the object lens that the optical take-up apparatus of recording of information and/or reproduction is used; Optical take-up apparatus has the wavelength X 1 of ejaculation (light source and the object lens of 390nm＜λ 1＜415nm) light beam; CD has the mutual different information recording surface of the distance (transparency carrier thickness) of injecting face to light beam more than three layers at thickness direction; Select in the said CD information recording surface arbitrarily; The light beam of the wavelength X 1 that penetrates from said light source through the information recording surface optically focused of said object lens, wherein to said selection
Said object lens are single element lens,
Picture number formulary value aperture (NA) is more than 0.8, below 0.95,
Under normal temperature (25 ± 3 ℃) environment; When the cover glass thickness setting that becomes the spherical aberration of the magnification M that satisfies (1) formula minimum is T (mm); Make when spending said object lens inclining 1 that three grades of coma CM3* (λ rms) of the point of optically focused and Pyatyi coma CM5* (λ rms) satisfy (14) formula via said cover glass thickness T
－0.003≤M≤0.003 （1）
0.145≤|CM3*－CM5*|≤0.229 （14）
The present invention's invention that to be basis show with the different coma viewpoint of invention of content 5 records of the present invention.Promptly under the situation of injecting the light beam of the said magnification M that satisfies (1) formula; Three grades of coma CM3* (λ rms) of the point of optically focused and Pyatyi coma CM5* (λ rms) satisfied the optimization that its balance is sought on (14) formula ground via said cover glass thickness T when discovery was spent said object lens inclining 1 through making; High-order spherical aberration in the time of then can effectively suppressing to focus saltus step (, make (characteristic 1) well).And then through satisfying (14) formula; Make the amount of movement of the coupled lens when focusing saltus step also little (can making (characteristic 2) well); And can inhibition face coma (can make (characteristic 3) good) during displacement, when lens thickness produces error, can also suppress spherical aberration (can make (characteristic 4) good).When the state that from sine condition violation amount is zero is controlled sine condition violation amount; Make in the position of the first pupil radius H1 and sine condition is violated measurer first maximum value is arranged; And than the position of its second big pupil radius H2 and sine condition is violated measurer second maximum value is arranged; Then owing to three grades of coma CM3* increase or reduce from negative value from positive value; And Pyatyi coma CM5* reduces or increases to the directions opposite with three grades of coma CM3*, so be the symbol condition of different of symbol and the Pyatyi coma CM5* of three grades of coma CM3* as the scope of optimum balance.In view of this point, as the preferable range of guaranteeing three grades of coma CM3* and Pyatyi coma CM5* balance, the result of the wholwe-hearted research of present inventor has found above-mentioned (14) formula.
Content of the present invention 7 records be to carry out the object lens that the optical take-up apparatus of recording of information and/or reproduction is used; Optical take-up apparatus has the wavelength X 1 of ejaculation (light source and the object lens of 390nm＜λ 1＜415nm) light beam; CD has the mutual different information recording surface of the distance (transparency carrier thickness) of injecting face to light beam more than three layers at thickness direction; Select in the said CD information recording surface arbitrarily; The light beam of the wavelength X 1 that penetrates from said light source through the information recording surface optically focused of said object lens, wherein to said selection
Said object lens are single element lens,
Picture number formulary value aperture (NA) is more than 0.8, below 0.95,
The aspherical shape X of picture side's optical surface (h) has two change poles points in effective radius, and satisfies (15) ~ (18) formula,
0.524≤PV≤0.855 （15）
0.270≤D1≤0.340 （16）
0.780≤D2≤0.930 （17）
0.530≤D3≤0.640 （18）
Wherein,
D1 (mm): be the ratio of the effective radius of the aspherical shape X (h) of the picture side's optical surface said relatively object lens of radial height of getting first flex point,
D2 (mm): be the ratio of the effective radius of the aspherical shape X (h) of the picture side's optical surface said relatively object lens of radial height of getting second flex point,
D3 (mm): be the ratio of the effective radius of the second derivative of the aspherical shape X (h) of the picture side's optical surface said relatively object lens of radial height of getting maximum value,
PV: the absolute value of difference of maximal value and minimum value of second derivative that is the aspherical shape X (h) of picture side's optical surface.
The present invention is the invention that shows the invention of content 1 of the present invention from the viewpoint of lens shape.The i.e. condition of the preferred optical surface shape of regulation object lens CD side for the condition of the sine condition violation amount that satisfies content of the present invention 1 regulation.As long as promptly set the optical surface of the shape of satisfied (15) ~ (18) formula for; Residual high-order spherical aberration when just (characteristic 1) can be dwindled the focusing saltus step; (characteristic 2) makes the amount of movement of the coupled lens when focusing saltus step little, and (characteristic 3) can inhibition face aberration generating capacity during displacement, (characteristic 4) can also suppress the generating capacity of aberration when lens thickness produces error; Therefore, can provide manufacturing easier object lens
The object lens of content of the present invention 8 records are in the invention of content 1 to 7 each record of the present invention, and the transparency carrier thickness setting of minimum is T in said transparency carrier thickness MIN(mm), be transparency carrier thickness setting maximum in the said transparency carrier thickness T MAX(mm) time, under normal temperature (25 ± 3 ℃) environment, make the spherical aberration of said magnification M become satisfied (19) formula of minimum cover glass thickness T (mm),
T MAX·0.85≤T≤T MAX·1.1 （19）
And said object lens are made up of plastic material.
Usually optical take-up apparatus is when carrying out information recording/regenerating to CD; Utilization make object lens along said CD radially and/or tangential tilt (being called lens tilt in this instructions) and the coma that produces, can eliminate because the coma that the warpage of CD and inclination (be called in this instructions and coil inclination) produce.Therefore; The coma amount that when lens tilt, produces is little; And it is big to be used for the needed lens tilt amount of coma that calibration disc tilts, so need guarantee that the dynamic range of lens tilt amount of lens is enough big, produces the optical take-up apparatus problem with the consumes electric power increase of actuator that maximizes.
But in the optical take-up apparatus that BD uses; To the information recording surface L0 (100 μ m) of transparency carrier thicker when carrying out information recording/regenerating; Through coupled lens is moved at optical axis direction divergent beams are injected to object lens; Therefore, compare with the situation that parallel beam is injected, the coma amount during lens tilt is little.When realizing high NA by the object lens that plastic material constitutes; Then by temperature variation cause in light beam spot generation spherical aberration (being called the temperature aberration in this instructions) apparition; The object lens that constitute by plastic material of focal length 1.41mm for example; The variable quantity of the spherical aberration when changing for 30 ℃ is about 100m λ rms, has surpassed Ma Likeer (マ レ シ ヤ Le) boundary value 70m λ rms.
This is because existing DVD; NA is about 0.60 ~ 0.67, need not proofread and correct this spherical aberration so the amount of spherical aberration that is produced by temperature variation is smaller, but when being the object lens that BD uses; Then spherical aberration also is directly proportional with 4 powers of NA sometimes, is caused the big cause of amount of spherical aberration of generation by temperature variation.Therefore, the BD that plastic object lens are installed with optical take-up apparatus in, just need move the Tc aberration at optical axis direction through making coupled lens.
More than; In the optical take-up apparatus that BD uses; During using plastics system object lens to come information recording surface L0 carried out information recording/regenerating; Because the degree of divergence that in environment temperature is the light injected to object lens under the situation of high temperature becomes bigger,, can not proofread and correct the coma that tilts to cause by dish well so that the coma quantitative change during lens tilt gets is littler.Promptly produce the problem that will make following (characteristic 5) good (though for the glass object lens less than the sort of degree of plastic objective lens, also have and to make following (characteristic 5) good problem) more consumingly for plastic objective lens.
The tilt sensitivity of (characteristic 5) object lens when the information recording surface to the transparency carrier thicker carries out information recording/regenerating is too not little.Particularly under the situation of the plastics system of use object lens, in the process when the information recording surface to the transparency carrier thicker carries out information recording/regenerating, the lens tilt sensitivity when needing environment temperature to become high temperature is too not little.
About (characteristic 5)
The coma that present inventors produce during for lens tilt and the desired value that BD should satisfy with plastics system object lens more than three layers has been discussed.Now; Two-layer BD is carried out the plastics system that the is equipped with object lens that the optical take-up apparatus of information recording/regenerating has, and these object lens have the combination of the so zero magnification of cover glass thickness 87.5 μ m (being the equal of the situation that parallel beam is injected) in order to make the minimum and information recording surface L0 (100 μ m) that is designed in the transparency carrier thicker of spherical aberration and the centre of the information recording surface L1 (75 μ m) of transparency carrier thin thickness.As stated; The coma amount why the plastics system object lens that design like this produce when lens tilt is minimum; Be because in the implementation of information recording surface L0 being carried out information recording/regenerating sometimes environment temperature become high temperature, three grades of coma generating capacities that under this state, caused by object lens inclining (lens tilt) become CM (LT).Be exactly to need only the plastics system objective lens design of using BD more than three layers to become the minimum value of the coma amount that when lens tilt, produces bigger on the contrary, just can be competent at practicality than CM (LT).
As comparative example as after state; When information recording surface L0 is carried out information recording/regenerating; The two-layer BD that is set with 0.5 degree lens tilt state at high temperature (55 degree) is about 0.02 λ rms with the coma generating capacity CM (LT) of plastics system object lens, and three grades of coma CM (DT) that produce when with equal state CD being tilted with amount and the ratio of CM (LT) are about 0.36.The result that present inventors are suitable for the plastics system object lens that BD uses more than three layers to these values as desired value discussion finds: at normal temperature (25 ± 3 ℃) and satisfy in the magnification of (1), through make spherical aberration cover glass thickness T hour the lower limit of (19) formula more than set spherical aberration correcting state just can satisfy the desired value of CM (LT).And through making the cover glass thickness T below the upper limit of (19) formula; Then make CM (LT) fully big; The degree of convergence of the light beam that also prevents simultaneously when the thinnest information recording surface of transparency carrier thickness is carried out information recording/regenerating, to inject to object lens is excessive, can prevent that lens shift characteristics (referring to the aberration generating capacity when object lens are followed the tracks of in optical take-up apparatus) from worsening and the residual high-order spherical aberration when the thinnest information recording surface focusing saltus step of transparency carrier thickness becomes big problem.
The object lens of content 9 records of the present invention are in the invention of content 8 records of the present invention, (20) formula below satisfying.
T MAX·0.85≤T≤T MAX·1.0 （20）
Through making the zero cover glass thickness of spherical aberration correction one-tenth unlike T MAXThick, the degree of convergence of the light beam that can prevent more when the information recording surface to the transparency carrier thin thickness carries out information recording/regenerating, to inject to object lens is big.Therefore, can prevent more when the information recording surface to the transparency carrier thin thickness carries out information recording/regenerating that object lens produce big coma when lens are shifted.Than two-layer BD and the big BD more than three layers of the maximum difference of the transparency carrier thickness of information recording surface; The degree of convergence of the light beam of when the thinnest information recording surface of transparency carrier thickness is carried out information recording/regenerating, injecting to object lens is excessive; And the lens shift characteristics worsens easily, but the invention of content of the present invention can solve the bigger problem of this BD more than three layers.Promptly through making the cover glass thickness T satisfy the upper limit of (20) formula; The degree of convergence that just can be suppressed at the light beam of injecting to object lens when the thinnest information recording surface of transparency carrier thickness carried out information recording/regenerating is excessive; Consequently owing to can make the lens shift characteristics better, the residual high-order spherical aberration when the thinnest information recording surface of transparency carrier thickness is focused saltus step is also littler and by preferred.Thus, compare with the embodiment of patent documentation 2 and can bring into play better effect.
The object lens of content of the present invention 10 records are in the invention of content 1 to 7 each record of the present invention, and the transparency carrier thickness setting of minimum is T in said transparency carrier thickness MIN(mm), be transparency carrier thickness setting maximum in the said transparency carrier thickness T MAX(mm) time, under normal temperature (25 ± 3 ℃) environment, make the spherical aberration of said magnification M become satisfied (21) formula of minimum cover glass thickness T (mm),
T MAX·0.75≤T≤T MAX·1.0 （21）
And said object lens are made up of glass material.
Present inventors have discussed (characteristic 5) about the glass object lens.The coma that produces during promptly about lens tilt and the desired value that BD uses more than three layers glass object lens should satisfy has been discussed.Owing in the glass object lens, can almost ignore influence of temperature variation, so compare with the situation of the plastics system of use object lens, the degree of divergence of the light of injecting to object lens is not such big.Therefore; In the magnification M of normal temperature (25 ± 3 ℃) and satisfied (1); Discovery makes the spherical aberration cover glass thickness hour can be thinner, finds that consequently becoming (21) formula lower limit ground through making sets the desired value that the correcting state of spherical aberration just can satisfy three grades of coma generating capacity CM (LT) of lens tilt.And through making the cover glass thickness T be no more than the upper limit of (21) formula; The degree of convergence of the light beam that then can prevent when the thinnest information recording surface of transparency carrier thickness is carried out information recording/regenerating, to inject to object lens is excessive, can prevent that the lens shift characteristics from worsening and the residual high-order spherical aberration when the thinnest information recording surface focusing saltus step of transparency carrier thickness becomes big.
That kind as described above; Because the residual high-order spherical aberration of the object lens of content 8 of the present invention and 10 records when not only (characteristic 1) focused saltus step is little; The amount of movement of (characteristic 2) coupled lens when focusing saltus step is little; (characteristic 3) can inhibition face aberration generating capacity during displacement; (characteristic 4) can also suppress the generating capacity of aberration when lens thickness produces error, and (characteristic 5) also can make lens displacement tilt sensitivity come to keep good to the lens shift characteristics when the information recording surface to the transparency carrier thicker carries out information recording/regenerating not too smallly, owing to having the level that all characteristics can be competent in practicality; So the object lens of the application of the invention, the optical take-up apparatus that can provide small-sized, low cost and the good CD of recording to use with information recording surface more than three layers.
The object lens of content 11 records of the present invention are in the invention of content 10 records of the present invention, (22) formula below satisfying.
T MAX·0.8≤T≤T MAX·0.95 （22）
Through satisfying (22) formula, can make the lens shift characteristics better, make the residual high-order spherical aberration when the thinnest information recording surface of transparency carrier thickness is focused saltus step littler.
The object lens of content 12 records of the present invention are in the invention of content 1 to 11 each record of the present invention; Under normal temperature (25 ± 3 ℃) environment, the most peripheral tiltangle (degree) in the effective aperture of the refractive index N of said wavelength X 1 and object space optical surface satisfies (23) formula.
－59.8·N+158＜θ＜－59.8·N+166 （23）
The result of wholwe-hearted research such as present inventor finds that shown in figure 19, there is the most peripheral tiltangle in effective aperture of lensed refractive index N and object space optical surface in embodiments of the invention in certain condition and range.According to this opinion, according to the viewpoint defined of preferred lens shape of the present invention is exactly (23) formula.
The object lens of content of the present invention 13 records are in the invention of content 1 to 12 each record of the present invention, and the transparency carrier thickness setting of minimum is T in said transparency carrier thickness MIN(mm), be transparency carrier thickness setting maximum in the said transparency carrier thickness T MAX(mm) time, satisfy (24) formula,
0.03（mm）＜T MAX－T MIN＜0.06（mm）（24）
In the CD that satisfies (24) formula with information recording surface more than three layers; Residual high-order spherical aberration when (problem 1) focused saltus step as above-mentioned usually becomes big; The amount of movement of (problem 2) coupled lens when focusing saltus step usually becomes big; And lens tilt sensitivity usually became greatly when (problem 5) carried out information recording/regenerating at the information recording surface to the transparency carrier thicker, have such problem to become big, but the present invention solved big like this problem.
The optical take-up apparatus of content 14 records of the present invention has: the object lens of content 1 to 13 each record of the present invention and the coupled lens that can move at optical axis direction, move any information recording surface of selecting CD through making said coupled lens at optical axis direction.
Though the residual high-order spherical aberration the when optical take-up apparatus corresponding with the CD with information recording surface more than three layers has (problem 1) focusing saltus step usually becomes big; The amount of movement of (problem 2) coupled lens when focusing saltus step usually becomes big; But on the basis that object lens of the present invention are installed; Through being moved at optical axis direction, coupled lens selects in the said CD information recording surface arbitrarily; Then because (characteristic 1) residual high-order spherical aberration in the time of can reducing to focus saltus step; The amount of movement of (characteristic 2) coupled lens when focusing saltus step also suppresses little; And (characteristic 3) can suppress relative two optical surfaces because foozle and aberration generation when the light shaft positive cross direction be shifted, and (characteristic 4) can also be suppressed at lens thickness on the optical axis owing to foozle and the aberration generating capacity when optical axis direction departs from, so the optical take-up apparatus that can provide small-sized, low cost and the good CD with information recording surface more than three layers of recording to use.
The optical take-up apparatus of content 15 records of the present invention is that said coupled lens is made up of single element lens in the invention of content 14 records of the present invention.
The optical take-up apparatus of content 16 records of the present invention is in the invention of content 14 records of the present invention; Said coupled lens is made up of for these two groups positive lens groups and negative lens group, moves any information recording surface of selecting CD through at least one lens that makes said positive lens groups.
According to the present invention, can further suppress little to the amount of movement of coupled lens, compacter optical take-up apparatus can be provided.
Optical take-up apparatus of the present invention has a light source (first light source) at least.Certainly also can have multiple light source in order to tackle multiple CD.And optical take-up apparatus of the present invention has the light-gathering optics that is used for from first light beam optically focused on the information recording surface of first CD of first light source at least.In the optical take-up apparatus that can tackle multiple CD, light-gathering optics also can be second light beam optically focused on the information recording surface of second CD, the 3rd light beam optically focused on the information recording surface of the 3rd CD.Optical take-up apparatus of the present invention has the photo detector of acceptance from the folded light beam of the first optical disc information record surface at least.In the optical take-up apparatus that can tackle multiple CD, photo detector also can be accepted the folded light beam from the second optical disc information record surface, accepts the folded light beam from the 3rd optical disc information record surface.And in this manual, " object space " is meant light source side, and " as the side " is meant the CD side.
First CD has the transparency carrier and the information recording surface of thickness t 1.Second CD has thickness t 2 (transparency carrier of t1＜t2 and information recording surface.The 3rd CD has thickness t 3 (transparency carrier of t2＜t3 and information recording surface.Preferred first CD is BD, and second CD is DVD, and the 3rd CD is CD, but is not limited thereto.
First CD has the information recording surface more than three layers overlappingly at thickness direction.Promptly first CD is to have more than three layers from the light beam of CD at thickness direction to inject face to the distance of information recording surface (this instructions be called " transparency carrier the thickness ") CD of different information recording surfaces each other to it.Can certainly have the information recording surface more than four.Second CD and the 3rd CD also can have a plurality of information recording surfaces.And " maximum transparency carrier thickness " is meant in a plurality of information recording surfaces from the light beam of CD and injects the transparency carrier thickness of face to farthest information recording surface, and " minimum transparency carrier thickness " is meant the transparency carrier thickness of injecting the nearest information recording surface of face with the light beam of CD.
Transparency carrier thickness setting minimum in transparency carrier thickness is T MIN, be transparency carrier thickness setting maximum in the transparency carrier thickness T MAXThe time, preferred satisfied (24) formula,
0.03（mm）＜T MAX－T MIN＜0.06（mm） （24）
In the CD that satisfies (24) formula with information recording surface more than three layers; Residual high-order spherical aberration during the big problem as above-mentioned (problem 1) focusing saltus step usually becomes big; The amount of movement of (problem 2) coupled lens when focusing saltus step usually becomes greatly, but the present invention solves big like this problem.
Therefore, optical take-up apparatus is selected any information recording surface in a plurality of information recording surfaces of first CD, the light beam that penetrates from light source through object lens to selected information recording surface optically focused, carry out recording of information and/or reproduction thus.
In this instructions; BD utilizes light beam and the object lens about NA0.8 ~ 0.9 about wavelength 390 ~ 415nm to carry out recording of information/reproduction; Transparency carrier thickness is the general name of the BD series CD about 0.05 ~ 0.125mm; Include BD that only has single information recording surface and the BD with information recording surface more than three layers etc., optical take-up apparatus of the present invention can be tackled the BD that has information recording surface more than three layers at least.
And in this instructions; DVD utilizes the object lens about NA0.60 ~ 0.67 to carry out recording of information/reproduction; Be the general name of the DVD series CD about transparency carrier thickness 0.6mm, include DVD-ROM, DVD-Video, DVD-Audio, DVD-RAM, DVD-R, DVD-RW, DVD+R, DVD+RW etc.And in this instructions, CD utilizes the object lens about NA0.45 ~ 0.51 to carry out recording of information/reproduction, is the general name of the CD series CD about transparency carrier thickness 1.2mm, includes CD-ROM, CD-Audio, CD-Video, CD-R, CD-RW etc.About recording density, be that the recording density of BD is the highest, then the order according to DVD, CD reduces.
Thickness t 1, t2, t3 about transparency carrier then preferably satisfy following (25), (26), (27) formula, but are not limited thereto.
0.050mm≤t1≤0.125mm （25）
0.5mm≤t2≤0.7mm （26）
1.0mm≤t3≤1.3mm （27）
In this instructions, first light source, secondary light source, the 3rd light source be LASER Light Source preferably.Then preferably can use semiconductor laser, silicon laser instrument etc. as LASER Light Source.(28), (29) formula below the wavelength lambda 3 (λ 3＞λ 3) of second wavelength X 2 (λ 2＞λ 1) of first wavelength X 1 of first light beam that preferably penetrates from first light source, second light beam that penetrates from secondary light source, the 3rd light beam that penetrates from the 3rd light source satisfies.
1.5·λ1＜λ2＜1.7·λ1 （28）
1.8·λ1＜λ3＜2.0·λ1 （29）
As first CD, second CD, the 3rd CD and when using BD, DVD, CD respectively; First wavelength X 1 of first light source preferably 350nm above, below the 440nm; Be more preferably longer and shorter than 390nm than 415nm, second wavelength X 2 of secondary light source preferably 570nm above, below the 680nm, be more preferably 630nm above, below the 670nm; The wavelength lambda 3 of the 3rd light source preferably 750nm above, below the 880nm, be more preferably 760nm above, below the 820nm.
Also can be at least two light source cellizations in first light source, secondary light source, the 3rd light source.Said blocking for example is meant and fixedly is housed in a housing to first light source and secondary light source.Encapsidate of photo detector of stating after also can adding light source.
Preferably use photodetectors such as photodiode as photo detector.The light that on the information recording surface of CD, reflects is injected to photo detector, used its output signal then can access the signal that reads of the information that is recorded in each CD.And changed by the caused light quantity of change in shape, the change in location of point on the detection photo detector, the detection and tracking of focusing detect, and then can object lens moved in order to focus and to follow the tracks of according to this detection.Photo detector also can be made up of a plurality of photodetectors.Photo detector also can have key light detecting device and secondary photodetector.For example also can be such photo detector: the both sides at the photodetector of the employed key light of record-playback of receiving information be provided with two secondary photodetectors, utilize these two secondary photodetectors to accept to follow the tracks of the secondary light of adjustment usefulness.And photo detector also can have a plurality of photo detectors corresponding with each light source.
Light-gathering optics has coupled lens and object lens.Said coupled lens is meant and is configured between object lens and the light source, changes the lens combination of beam divergence angle.And collimating apparatus is a kind of of coupled lens, is the coupled lens that the light beam injected is penetrated as directional light or almost parallel light.Coupled lens can have only by positive lens groups situation about constituting and the situation with positive lens groups and negative lens group.Positive lens groups has a positive lens at least.Positive lens groups can only be a positive lens, also can have a plurality of lens.Have under the situation of negative lens group, negative lens group has a negative lens at least.Negative lens group can only be a negative lens, also can have a plurality of lens.Preferred coupled lens example is made up of a positive lens of single element lens, is perhaps made up by a negative lens of positive lens of single element lens and single element lens to constitute.
Be called " moving lens " to the lens that can move in the coupled lens of this instructions at optical axis direction.Handle " amount of movement of coupled lens " is according to using with " amount of movement of moving lens " identical meaning in this instructions.
As suppressing little method to the coupled lens amount of movement, the focal power of the lens combination that moves at optical axis direction in the lens combination of consideration handlebar formation coupled lens strengthens the method for (promptly shortening the focal length of the lens combination that moves at optical axis direction) when focusing saltus step.This is because the amount of movement of the lens combination that moves at optical axis direction is that the focal power bigger (focal length that is its lens combination is short more) of its lens combination is with regard to more little cause.But coupled lens by one group of situation about constituting under; When setting the focal length of the lens combination that moves at optical axis direction (promptly equaling the coupled lens focal length) short; Then become elliptical shape, might make recording of information and/or the reproduction of BD are broken down by the point of object lens optically focused.Its reason is in following narration.
The light beam that usually penetrates owing to the semiconductor laser that uses from the light source as optical take-up apparatus is an ellipticity, thus in the long axis of ellipse direction with short-axis direction and light quantity distribution is different.Because if the focal length of coupled lens is too short, the asymmetry of the light quantity distribution that then gets into to coupled lens just significantly so become elliptical shape by the point of object lens optically focused, might make recording of information and/or the reproduction of BD are broken down.Therefore, coupled lens by one group of situation about constituting under, be difficult to take into account the symmetry of the light quantity distribution that when the focusing saltus step necessary coupled lens amount of movement reduces and get into to coupled lens.
Above-mentioned in order to take into account, preferably set coupled lens for constitute two groups of structures by positive lens groups and negative lens group, move any information recording surface optically focused of selecting to CD at optical axis direction through at least one lens that makes positive lens groups.
For explanation is oversimplified, set coupled lens for constitute the thin lens combination of two groups of thickness of structure by positive lens and negative lens, when the focusing saltus step, positive lens is moved along optical axis direction.When the focal power positive lens is set at P P, be set at f to the focal length of positive lens P, be set at P to the focal power of negative lens N, be set at f to the focal length of negative lens N, when being L to the distance setting of positive lens and negative lens, then the focal distance f c of the focal power Pc of coupled lens total system and coupled lens total system is represented by following (30) formula.
Pc=P P+P N-L·P P·P N
Pc=1／fc
Pc=1／f P+1／f N－L／（f P·f N）（30）
At this, when the focal length object lens is set at fo, the magnification M that then constitutes light-gathering optics by coupled lens and object lens becomes following (31) formula.
Ｍ＝－fo／fc（31）
For the symmetry that makes the light quantity distribution that gets into to coupled lens good; Making by the shape of the point of object lens optically focused becomes circle, just need set the magnification M of optical system for optimum value for the ellipticity of the light beam that penetrates from the semiconductor laser that uses as light source.In the optical take-up apparatus that BD uses, the magnification optimum value of light-gathering optics is about-0.1.Consider the configuration space of the optical elements such as polarized light beam splitter that are configured between light source and the coupled lens, can not set the focal distance f c of coupled lens total system extremely shortly.And for make to BD carry out recording of information and/or object lens when reproducing not too short with the distance (yet being called operating distance) of BD, and make the optical take-up apparatus slimming, the optimum range of objective focal length f ' o is determined naturally.From more than; According to (31) formula, as the coupled lens that BD uses with optical take-up apparatus, the focal range of its total system need be the scope of certain regulation; The amount of movement of needed coupled lens in the time of can not only considering to focus saltus step is optionally set the focal distance f c of coupled lens total system little.
At this, in order to suppress little to the amount of movement of focusing during saltus step, preferably make the focal power PP of positive lens become big, and the focal distance f c of coupled lens total system is come the increase of the absolute value of the focal power PN of negative lens (reference (30) formula) not too shortly.
According to the above; In the coupled lens that constitutes by positive lens groups and these two lens combination of negative lens group; Through positive lens groups is moved at optical axis direction, then can take into account symmetry in focusing necessary positive lens groups amount of movement light quantity distribution little and that get into to coupled lens during saltus step.
The configuration of positive lens groups and negative lens group can be to begin the arranged in order according to negative lens group, positive lens groups from light source side, also can be to begin the arranged in order according to positive lens groups, negative lens group from light source side.Preferred configuration is for the former.
From more than, according to the viewpoint that reduces the coupled lens amount of movement, the preferred example of the coupled lens of optical take-up apparatus is to constitute a positive lens and a negative lens combination, begins the arranged in order according to negative lens, positive lens from light source side.But the present invention is not limited thereto, and according to the structure that the makes coupled lens simple viewpoint of trying one's best, also can access single element lens is the coupled lens options of a slice positive lens.
According to above reason,, at least one lens (preferably positive lens) of positive lens groups can be moved at optical axis direction in order to proofread and correct the spherical aberration that is produced at the selecteed information recording surface of first CD.For example carry out the record and/or the reproduction of any information recording surface of first CD; Then; When other information recording surfaces to first CD write down and/or reproduce; Make at least one lens in the positive lens groups of coupled lens group move the divergence that makes light beam and change, proofread and correct the spherical aberration that is produced when the different information recording surface focusing saltus step of first CD through the magnification change that makes object lens at optical axis direction.And because on the structure of optical take-up apparatus, the possibility of the various optical elements of configuration is high between moving lens and light source, so it is many to be difficult to obtain the situation of moving lens mobile space.Therefore, preferably short to the maximum moving distance of CD side to the maximum moving distance of light source side than reference position from moving lens from the reference position of moving lens.
Fig. 1 is the result's that discusses of expression present inventor figure.The present inventor plastics system, focal distance f=1.18mm, optical surface be aspheric surface or diffraction surfaces, as the object lens in number formulary value aperture 0.85 as example; In having first CD (BD) of a plurality of information recording surfaces, on the information recording surface that leaves to greatest extent, obtain respectively: the poor A of the maximum spherical aberration that produces when best focal point forms, produce maximum spherical aberration B when ℃ changing, when optical source wavelength ± 5nm variation, produce maximum spherical aberration C in environment temperature ± 30.Represent it with the bar-shaped curve of Fig. 1.This spherical aberration moves and makes the magnification change of object lens and can be corrected at optical axis direction through making coupled lens, and when using identical coupled lens, then the amount of movement of the total of amount of spherical aberration and coupled lens is suitable.
At this; Shown in Fig. 1 (a), Fig. 1 (b); Having in use under the situation of CD of two information recording surfaces, is that any object lens of non-refraction at spherical surface face, diffraction surfaces all are that the total of amount of spherical aberration is about 410 ~ 430m λ rms for optical surface, we can say that the amount of movement of coupled lens is smaller.On the other hand shown in Fig. 1 (c); Have in use under the situation of CD of four information recording surfaces; For optical surface be non-refraction at spherical surface face object lens then the total of amount of spherical aberration be 680m λ rms; The amount of movement of coupled lens is compared with the situation that use has the CD of two information recording surfaces, then needs about 1.5 times.More shown in Fig. 1 (d); For optical surface is the object lens of diffraction surfaces, has in use under the situation of CD of four information recording surfaces, as the effect of diffraction surfaces and reduced the spherical aberration that produces along with temperature variation; But for this reason and along with spherical aberration that wavelength change produced increases; Consequently the total of amount of spherical aberration is 660m λ rms, and the amount of movement of coupled lens is compared with the situation that use has the CD of two information recording surfaces, likewise needs about 1.5 times.
But when to set object lens for by glass and optical surface be non-refraction at spherical surface face; The spherical aberration B (=140m λ rms) that is caused by variation of ambient temperature roughly becomes zero, so the amount of movement of coupled lens littler (suitable with the correcting value of spherical aberration 540m λ rms among Fig. 1 (c)).And then when setting object lens for when being the diffraction surfaces of the spherical aberration that produces when proofreading and correct in wavelength variation by glass and optical surface; The spherical aberration B that is not only caused by variation of ambient temperature reduces; And the function of utilizing diffraction surfaces also reduces the spherical aberration C that is caused by optical source wavelength change, so the amount of movement of coupled lens littler (suitable with the correcting value of spherical aberration 500m λ rms among Fig. 1 (c)).Promptly preferred object lens are made up of glass material for the amount of movement that reduces coupled lens.Even but improved object lens like this; The amount of movement of the coupled lens when using CD relatively with two information recording surfaces; And the amount of movement of the coupled lens when using the CD with four information recording surfaces still is about twice; Therefore, then preferably to work hard more for the amount of movement that suppresses coupled lens.Likewise, also can the say so amount of movement of the coupled lens when using CD with three information recording surfaces or five above information recording surfaces.So the present invention can further reduce the amount of movement of coupled lens through the sine condition that destroys object lens.
In above-mentioned discussion; As the CD with two information recording surfaces (be set at the little information recording surface of distance of injecting face to the light beam of CD RL1, be set at RL2 to the big information recording surface of distance of injecting face to the light beam of CD) and hypothesis is that to inject face from the light beam of CD be 75 μ m to the distance of RL1, injecting face from the light beam of CD is the CD of 100 μ m to the distance of RL2.And then suppose it is that to inject face from the light beam of CD be 50 μ m to the distance of RL1 as the CD with four information recording surfaces (be set at the minimum information recording surface of distance of injecting face to the light beam of CD RL1, be set at RL4 to the information recording surface of injecting face to the light beam of CD) apart from maximum, injecting face from the light beam of CD is the CD of 100 μ m to the distance of RL4.
In this instructions, object lens are meant and in optical take-up apparatus, are configured in the position relative with CD to have the optical system of the light beam function of optically focused on the information recording surface of CD that penetrates from light source.Object lens are plastic lens or glass lenss of single element lens.The object lens that preferably constitute by the convex lens of single element lens.Object lens also can only be made up of plane of refraction, also can have the structure of the optical path difference of paying.And also can be on glass lens, to wait the hybrid lens of paying the optical path difference structure is set through light-cured resin, UV curable resin or heat-curing resin.The preferred plane of refraction of object lens is an aspheric surface.And it is aspheric surface that object lens preferably are provided with the fundamental plane of paying the optical path difference structure.Sometimes the optical surface that is called the optical surface of object lens light source side object space is called the optical surface of CD side the optical surface of picture side.In object lens, the radius-of-curvature absolute value of preferred light source side optical surface is than little as the radius-of-curvature absolute value of square optical surface.
As with reference to Fig. 1 explanation; When object lens are glass lenss, then need cause the spherical aberration of generation by temperature variation and coupled lens is moved, therefore in order to proofread and correct; Can reduce the amount of movement of coupled lens, quilt is preferred owing to can make the optical take-up apparatus miniaturization.
Setting object lens under the situation of glass lens, preferably using vitrification point Tg is below 500 ℃, is more preferably the glass material below 400 ℃.Because using vitrification point Tg is the glass material below 500 ℃ and can being shaped with lower temperature, so can prolong the life-span of mould.The glass material low as this vitrification point Tg for example has (strain) to live in the K-PG325 and the K-PG375 (all being ProductName) of field optical glass system.
When making glass lens forming, becoming important physics value is linear expansion coefficient α.Even it is the material below 400 ℃ that Tg has been selected in supposition, compare with resin material, still big with the temperature difference of room temperature.When using the big glass material of linear expansion coefficient α to carry out forming lens, crackle takes place when cooling easily.The linear expansion coefficient α of glass material preferably 200 (* 10 -7/ K) below, be more preferably 120 (* 10 -7/ K) below.
Because glass lens is usually great than the ratio of plastic lens, so when setting object lens for glass lens, then quality becomes big and the actuators that drive object lens are added with burden.Therefore, set object lens under the situation of glass lens, preferably using the little glass material of proportion.Be exactly preferred specific gravity below 4.0 specifically, more preferably proportion is below 3.0.
Object lens are under the situation of plastic lens, preferably use ester ring type hydrocarbon polymer materials such as cyclic olefin resinous materials.In addition; The following resin material of further preferred use; This numerical value material under 25 ℃ of temperature to the refractive index of the light of wavelength 405nm in 1.54 ~ 1.60 scopes, when temperature changes in-5 ℃ ~ 70 ℃ temperature ranges, to the variations in refractive index rate dN/dT of the light of wavelength 405nm (℃ -1)-20 * 10 -5~-5 * 10 -5(more preferably-10 * 10 -5~-8 * 10 -5) in the scope.In addition, object lens are under the situation of plastic lens, preferably make coupled lens also be plastic lens.
Below enumerate the preference of several kinds of ester ring type hydrocarbon polymers.
The 1st preference relates to the resin combination that comprises following segmented copolymer: said segmented copolymer has the polymer blocks [A] of the repetitive [1] that comprises following formula (1) expression and comprises repetitive [1] and the repetitive [2] of following formula (2) expression and/or the polymer blocks [B] of the repetitive [3] that following formula (3) is represented of following formula (1) expression, and the relation between the mole fraction b (mole %) of the repetitive [1] in mole fraction a of the repetitive [1] in the block [A] (mole %) and the block [B] is a>b.
[Chemical formula 1]
Figure BDA00001794214200201
(in the formula, R 1Represent the alkyl of hydrogen atom or carbon number 1 ~ 20, R 2-R 12Represent alkyl, the hydroxyl of hydrogen atom, carbon number 1 ~ 20, the alkoxy or the halogen group of carbon number 1 ~ 20 independently of one another.)
[Chemical formula 2]
Figure BDA00001794214200211
(in the formula, R 13Represent the alkyl of hydrogen atom or carbon number 1 ~ 20.)
[chemical formula 3]
Figure BDA00001794214200212
(in the formula, R 14And R 15Represent the alkyl of hydrogen atom or carbon number 1 ~ 20 independently of one another.)
In addition, the 2nd preference relates to the resin combination that comprises following polymkeric substance (A) and following polymkeric substance (B): said polymkeric substance (A) is that alpha-olefin and the monomer composition of the cyclic olefin that comprises formula (4) expression through making carbon number 2 ~ 20 at least carries out the polymkeric substance that addition polymerization obtains; Said polymkeric substance (B) is that the monomer composition of alpha-olefin that makes carbon number 2 ~ 20 and the cyclic olefin that comprises formula (5) expression carries out addition polymerization and the polymkeric substance that obtains.
[chemical formula 4]
Figure BDA00001794214200213
[in the formula, n is 0 or 1, and m is the integer more than 0 or 1, and q is 0 or 1, R 1~ R 18, R aAnd R bRepresent hydrogen atom, halogen atom or alkyl independently of one another, R 15~ R 18Bonding forms monocycle or many rings each other, and monocycle or many rings in the bracket can have two keys, in addition, and R 15And R 16, or R 17And R 18Between can also form alkylidene].
[chemical formula 5]
Figure BDA00001794214200221
[in the formula, R 19~ R 26Represent hydrogen atom, halogen atom or alkyl independently of one another.]
In order further to give performance for resin material, can also be to wherein adding adjuvant as follows.
(stabilizing agent)
The preferred interpolation is selected from least a kind of stabilizing agent in phenol stabilizer, hindered amines stabilizing agent, Phosphorus stabilizing agent and the sulphur class stabilizing agent.Through suitable selection and add these stabilizing agents, for example, change of optical property such as the gonorrhoea that is produced in the time of can be to the such short-wavelength light of prolonged exposure 405nm, variations in refractive index realizes more efficiently inhibition.
As preferred phenol stabilizer; Can use the stabilizing agent of conventional known; For example can enumerate: the acrylic acid 2-tert-butyl group-6-(the 3-tert-butyl group-2-hydroxy-5-methyl base benzyl)-4-methyl phenyl ester, acrylic acid 2; 4-two tertiary pentyls-6-(1-(3,5-two tertiary pentyls-2-hydroxyphenyl) ethyl) phenyl ester etc. is recorded in japanese kokai publication sho 63-179953 communique, the spy opens the acrylic ester compound in the flat 1-168643 communique; Propionic acid octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl) ester, 2,2 '-di-2-ethylhexylphosphine oxide (4-methyl-6-tert butyl phenol), 1; 1,3-three (2-methyl-4-hydroxyl-5-tert-butyl-phenyl) butane, 1,3; 5-trimethyl-2,4,6-three (3; The 5-di-tert-butyl-4-hydroxyl benzyl) (methylene-3-(3 ' for benzene, four; 5 '-di-t-butyl-4 '-hydroxyphenylpropionic acid ester)) methane [that is four (3-(3,5-di-t-butyl-4-hydroxyphenylpropionic acid)) pentaerythritol ester ,], the two substituted phenolic compounds of alkyl such as (3-(3-tertiary butyl-4-hydroxy-5-aminomethyl phenyl) propionic esters) of triethylene glycol; 6-(4-hydroxyl-3,5-di-tert-butyl amido)-2, the two hot sulfenyl-1,3,5-triazines of 4-, the two hot sulfenyl-1,3,5-triazines of 4-, the hot sulfenyl-4 of 2-, two (3,5-di-t-butyl-4-hydroxy benzenes the amido)-1,3,5-triazines etc. of 6-contain the phenolic compound of triazinyl; Or the like.
In addition,, can enumerate: two (2,2,6, the 6-tetramethyl-4-piperidyl) esters of decanedioic acid, succinic acid two (2,2 as preferred hindered amines stabilizing agent; 6,6-tetramethyl-4-piperidyl) ester, two (1,2,2,6, the 6-pentamethyl-4-piperidyl) esters of decanedioic acid, two (the N-octyloxies-2,2 of decanedioic acid; 6,6-tetramethyl-4-piperidyl) ester, two (N-benzyl oxygen base-2,2,6, the 6-tetramethyl-4-piperidyl) esters of decanedioic acid, decanedioic acid two (N-cyclohexyl oxygen base-2,2,6; 6-tetramethyl-4-piperidyl) ester, two (1,2,2,6, the 6-pentamethyl-4-piperidyl) 2-(3, the 5-di-tert-butyl-4-hydroxyl benzyl) of malonic acid-2-butyl ester, two (the 1-acryloyl groups-2 of malonic acid; 2,6,6-tetramethyl-4-piperidyl) 2, two (3, the 5-the di-tert-butyl-4-hydroxyl benzyl)-2-butyl esters of 2-, decanedioic acid two (1,2; 2,6,6-pentamethyl-4-piperidyl) ester, methacrylic acid 2,2,6,6-tetramethyl-4-piperidines ester, [3-(3 for 4-; 5-di-t-butyl-4-hydroxyphenyl) propionyloxy]-1-[2-(3-(3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy) ethyl]-2,2,6,6-tetramethyl piperidine, 2-methyl-2-(2,2; 6,6-tetramethyl-4-piperidyl) amino-N-(2,2,6,6-tetramethyl-4-piperidyl) propionamide, four (2,2; 6,6-tetramethyl-4-piperidyl) 1,2,3,4-butane tetracarboxylic acid esters, four (1,2; 2,6,6-pentamethyl-4-piperidyl) 1,2,3,4-butane tetracarboxylic acid esters etc.
In addition; As preferred Phosphorus stabilizing agent; So long as the stabilizing agent that is normally used in the conventional resin industry does not then have particular restriction; For example can enumerate: triphenyl phosphite, phosphorous acid diphenyl isodecyl ester, diisodecyl phenyl phosphite, tricresyl phosphite (nonyl phenyl) ester, tricresyl phosphite (dinonyl phenyl) ester, tricresyl phosphite (2; The 4-di-tert-butyl-phenyl) ester, 10-(3, the 5-di-tert-butyl-4-hydroxyl benzyl)-9,10-dihydro-9-oxy-10-phospho hetero phenanthrene-single phosphite ester compounds such as 10-oxide; 4,4 '-Ding fork-two (3-methyl-6-tert butyl phenyl diphosphorous acid esters in three last of the ten Heavenly stems), 4, two (the diphosphorous acid ester type compounds such as phenyl-dialkyl group (C12 ~ C15) phosphite ester) etc. of 4 '-isopropylidene.Wherein, preferred single phosphite ester compound, especially preferred tricresyl phosphite (nonyl phenyl) ester, tricresyl phosphite (dinonyl phenyl) ester, tricresyl phosphite (2, the 4-di-tert-butyl-phenyl) ester etc.
In addition, as preferred sulphur class stabilizing agent, for example can enumerate: 3; 3-dilauryl thiodipropionate, 3,3 '-thio-2 acid, two myristins, 3,3-distearylthiodi-propionate, 3; 3-thio-2 acid lauryl stearyl ester, four (β-lauryl sulfo-) propionic acid pentaerythritol ester, 3, two (the 2-dodecyl thio-ethyls)-2,4 of 9-; 8,10-four oxygen spiral shell [5,5] undecanes etc.
As the combined amount of above-mentioned each stabilizing agent, can in the scope of not destroying the object of the invention, suitably select, but with respect to ester ring type hydrocarbon type copolymer 100 mass parts, mix 0.01 ~ 2 mass parts usually, preferred 0.01 ~ 1 mass parts.
(surfactant)
Surfactant is the compound that in a part, has hydrophilic radical and hydrophobic grouping.Through utilizing surfactant that speed and the moisture of attachment of moisture on resin surface is regulated from the speed of above-mentioned surface evaporation, can prevent the gonorrhoea of resin combination.
As the hydrophilic radical of surfactant, specifically can enumerate: hydroxy alkyl more than 1 of hydroxyl, carbon number, hydroxyl, carbonyl, ester group, amino, amide group, ammonium salt, mercaptan, sulphonate, phosphate, PAG base etc.Wherein, amino can be any in primary amino radical, secondary amino group, the uncle's amino.As the hydrophobic grouping of surfactant, specifically can enumerate: the alkyl of carbon number more than 6, silicyl, carbon number fluoro-alkyl more than 6 etc. with carbon number alkyl more than 6.Wherein, can also have aromatic ring as its substituting group on the alkyl of carbon number more than 6.As alkyl, specifically can enumerate hexyl, heptyl, octyl group, nonyl, decyl, undecyl, dodecyl, tridecyl, myristyl, myristyl, stearyl, lauryl, palmityl, cyclohexyl etc.As aromatic ring, can enumerate phenyl etc.With regard to this surfactant, can in a part, have each at least 1 in aforesaid hydrophilic radical and the hydrophobic grouping, also can have each group more than 2.
As this type surfactant; More specifically, for example can enumerate: myristyl diethanolamine, 2-hydroxyethyl-2-hydroxyl lauryl amine, 2-hydroxyethyl-2-hydroxyl tridecyl amine, 2-hydroxyethyl-2-hydroxyl tetradecylamine, pentaerythritol monostearate, pentaerythritol stearic acid ester 2, pentaerythrite tristearate, two (2-hydroxyethyl-2-hydroxyl dodecyl) amine, alkyl (carbon number 8 ~ 18) benzyl dimethyl ammonium chloride, ethylenebis alkyl (carbon number 8 ~ 18) acid amides, stearyl diglycollic amide, lauryl diglycollic amide, myristyl diglycollic amide, palmityl diglycollic amide etc.Wherein, preferred amines or the amide compound that use with hydroxy alkyl.In the present invention, also can the combination of the above-claimed cpd more than 2 kinds be used.
As surfactant; The gonorrhoea of the shaping thing that causes from can effectively suppressing to follow the variation of temperature, humidity, the angle consideration that keeps the height transmittance of shaping thing; With respect to ester ring type hydrocarbon polymer 100 mass parts, preferably add the surfactant of 0.01 ~ 10 mass parts.With respect to ester ring type hydrocarbon polymer 100 mass parts, the addition of surfactant is 0.05 ~ 5 mass parts more preferably, further is preferably 0.3 ~ 3 mass parts.
(plastifier)
Plastifier is for the melt index (MI) of regulating multipolymer, adds as required.
As plastifier, can adopt known plastifier such as two (2-ethylhexyl) esters of hexane diacid, two (2-butoxyethyl group) esters of hexane diacid, two (2-ethylhexyl) esters of azelaic acid, dipropylene glycol dibenzoate, tri-n-butyl citrate, ATBC, epoxidised soybean oil, 2-ethylhexyl epoxidation tall oil, chlorinated paraffin, tri-2-ethylhexyl phosphate, tricresyl phosphate, phosphoric acid tert-butyl phenyl ester, tricresyl phosphate (2-ethylhexyl diphenyl) ester, dibatyl phithalate, phthalic acid two dissident's esters, phthalic acid two heptyl esters, phthalic acid ester in two ninth of the ten Heavenly Stems, phthalic acid two (undecyl) ester, phthalic acid two (2-ethylhexyl) ester, phthalic acid dinonyl, phthalic acid two isodecyl esters, phthalic acid two (tridecyl) ester, phthalic acid butyl benzyl ester, dicyclo-hexyl phthlate, decanedioic acid two (2-ethylhexyl) ester, tri trimellitate (2-ethylhexyl) ester, Santicizer 278, Paraplex G40, Drapex 334F, Plastolein 9720, Mesamoll, DNODP-610, HB-40.The confirming and under the permeability of not destroying multipolymer, condition, suitably to carry out of the selection of plastifier and addition to the patience of environmental change.
As these resins; The preferred cyclic olefin resins that uses; As concrete preference, can enumerate the ZEONEX of Nippon Zeon Co., Ltd.'s manufacturing, the APEL of Mitsui Chemicals manufactured, the TOPAS of TOPAS ADVANCED POLYMERS manufactured, the ARTON of JSR manufactured etc.
In addition, the Abbe number that preferably constitutes the material of object lens is more than 50.
In the picture number formulary value aperture (NA) that is object lens is under the situation of the single element lens that is made up of plastic material more than 0.8, below 0.95, and maximum transparency carrier thickness in the transparency carrier thickness of CD (being in information recording surface that deep-seated puts and the distance between the optical disc surface) is set at T MAX(mm) time, at normal temperature (25 ± 3 ℃) and in the cover glass thickness T (mm) of (19 ') formula below satisfying, satisfied (1) formula of magnification M that preferred spherical aberration becomes hour.
T MAX·0.8≤T≤T MAX·1.1 （19′）
T MAX·0.85≤T≤T MAX·1.1 （19）
－0.003≤M≤0.003 （1）
More preferably satisfy (19) formula.
The coma that produces during for lens tilt and the desired value that BD uses more than three layers plastics system object lens should satisfy has been discussed; Injecting the information recording surface of face highest distance position (being the thickest information recording surface of transparency carrier thickness) and carrying out in the implementation of information recording/regenerating being in light beam; Become in environment temperature under the situation of high temperature, it is about 0.36 that the three grades of coma CM (DT) that produce during disc tilt are set at the ratio of CM (LT).As previously mentioned; This ratio with two-layer BD is carried out in the optical take-up apparatus of the plastics system that is equipped with object lens of information recording/regenerating; Information recording surface L0 (100 μ m) to the transparency carrier thicker carries out in the implementation of information recording/regenerating, and the ratio of the CM (LT) of the three grades of coma CM (DT) when environment temperature becomes the object lens inclining under the high-temperature condition during with disc tilt equates.
Present inventors find these values as the result that desired value discussion is suitable for the plastics system object lens that BD uses more than three layers; At normal temperature (25 ± 3 ℃) and satisfy in the magnification of (1), through make spherical aberration cover glass thickness T hour the lower limit of (19) formula more than set spherical aberration correcting state just can satisfy the desired value of CM (LT).And CM (LT) is that the cover glass thickness T is thick more big with regard to setting more; But if the cover glass thickness T surpasses the upper limit of (19) formula; The degree of convergence of the light beam of then when the thinnest information recording surface of transparency carrier thickness is carried out information recording/regenerating, injecting to object lens is just excessive, owing to occur that the lens shift characteristics worsens and the residual high-order spherical aberration when the thinnest information recording surface focusing saltus step of transparency carrier thickness becomes big problem and not by preferably.
(20) formula below more preferably satisfying.
T MAX·0.85≤T≤T MAX·1.0 （20）
At this moment, preferred especially M=0.
Through making the cover glass thickness T satisfy the upper limit of (3) formula; The degree of convergence that is suppressed at the light beam of injecting to object lens when the thinnest information recording surface of transparency carrier thickness carried out information recording/regenerating more is excessive; Consequently owing to can make the lens shift characteristics better, the residual high-order spherical aberration when the thinnest information recording surface of transparency carrier thickness is focused saltus step is also littler and by preferred.
Conditional (20 ') below more preferably satisfying.
T MAX·0.9≤T≤T MAX·0.95 （20′）
At this moment, preferred especially M=0.
Then; In the picture number formulary value aperture (NA) that is object lens is under the situation of the single element lens that is made up of glass material more than 0.8, below 0.95, and maximum transparency carrier thickness in the transparency carrier thickness of CD (being in information recording surface that deep-seated puts and the distance between the optical disc surface) is set at T MAX(mm) time, at normal temperature (25 ± 3 ℃) and the thickness of (21) formula below satisfying be in the cover glass thickness T (mm), satisfied (1) formula of magnification M that preferred spherical aberration becomes hour.
T MAX·0.75≤T≤T MAX·1.0 （21）
－0.003≤M≤0.003 （1）
Owing to can almost ignore influence of temperature variation in the object lens that are made up of glass material, so compare with the situation of the plastics system of use object lens, the degree of divergence of the light of injecting to object lens is not such big.Therefore; In the magnification M of normal temperature (25 ± 3 ℃) and satisfied (1); Discovery makes the spherical aberration cover glass thickness T hour can be thinner, consequently finds to become through making (21) formula lower limit ground and sets the desired value that the correcting state of spherical aberration just can satisfy three grades of coma generating capacity CM (LT) that the lens displacement tilts.And through making the cover glass thickness T be no more than the upper limit of (21) formula; The degree of convergence of the light beam that then can prevent when the thinnest information recording surface of transparency carrier thickness is carried out information recording/regenerating, to inject to object lens is excessive, can prevent that the lens shift characteristics from worsening and prevent that the residual high-order spherical aberration when the thinnest information recording surface focusing saltus step of transparency carrier thickness from becoming big.
(22) formula below more preferably satisfying.
T MAX·0.8≤T≤T MAX·0.95 （22）
At this moment, preferred especially M=0.
The optimum condition of object lens sine condition is described below.As shown in Figure 2, so-called sine condition is the height h apart from optical axis 1Light when injecting abreast at relative lens and with optical axis, when the ejaculation angle of this light when lens penetrate is U, h 1/ sinU satisfies certain value.At it be and height h apart from optical axis 1The situation of the irrelevant certain value of height under, think then that sine condition is satisfied and in the effective aperture lateral magnification of each light be certain.This sine condition is the calculated value on axle, but outside carrying out axle, is effective in the correction of lateral magnification error (i.e. coma outside the axle).
On the other hand, at h 1/ sinU is not under the situation of certain value, then OSC=h 1/ sinU-f is defined as sine condition violation amount.Fig. 3 is as transverse axis, the curve of representing as the longitudinal axis apart from the height of optical axis the sine condition violation amount of object lens.Be to satisfy under the situation of object lens of sine condition, curve is consistent with the longitudinal axis, but is being not satisfy under the situation of object lens of sine condition, and that kind as shown in Figure 3 becomes curve and leaves from positive side of Y and/or minus side.Satisfy sine condition as if making near optical axis and effective aperture for the object lens that do not satisfy sine condition, then sine condition violation amount must have maximum value.At this, be set at OSC to the positive side maximum value of sine condition violation amount Max(value of maximum value just is not, negative situation also has) is set at OSC to minus side maximum value Min
The object lens of characteristic shown in Fig. 3 (a) are that sine condition violation measurer has a minus side maximum value OSC MinAnd there is not positive side maximum value OSC MaxExample.According to this object lens because face displacement sensitivity is little and axle to go up thickness error sensitivity little, so easy to manufacture, have on the other hand that high-order spherical aberration increases and changes little characteristic by the spherical aberration that magnification change causes along with moving of coupled lens.Therefore, when coupled lens being moved, might can increase by needed amount of movement for the information recording surface of selecting CD more than three layers.
Relatively, object lens of the present invention are the object lens of characteristic shown in Fig. 3 (b), and in above-mentioned magnification M, sine condition violation amount has a positive side maximum value OSC at least Max(also can be not necessarily positive value) (preferably only one).Violate measurer according to the sine condition shown in Fig. 3 (b) positive side maximum value OSC is arranged MaxObject lens; Owing to having high-order spherical aberration minimizing that produces along with moving of coupled lens and the spherical aberration variation characteristic greatly that causes by magnification change; So when coupled lens being moved, can dwindle needed amount of movement for the information recording surface of selecting CD more than three layers.
And in the example of Fig. 3 (b), sine condition violation amount has the maximum value that the positive side maximum value of ratio is positioned at optical axis side minus side more as describing anti-S word curve.
In the example of Fig. 3 (b), violating measurer for the magnification M that satisfies (1) formula at the first pupil radius H1 sine condition has the first maximum value OSC Min, the second pupil radius H2 (wherein, H1＜H2＜H3=effective radius more than 90% and sine condition is violated measurer the second maximum value OSCmax is arranged.The derivative φ (h) of so-called sine condition violation amount is meant and is taken at pupil radius the longitudinal axis shown in Figure 3, violates sine condition and measure when the transverse axis that sine condition is violated 1 rank differential of discharge curve.The meaning that is derivative φ (h) is: if less than pupil radius H1 for negative; Then the curve from optical axis direction outside sine condition violation conjointly amount tilts to minus side (left side of Fig. 3 (b)); If surpass pupil radius H1 less than H2 for just; Then the curve of sine condition violation amount tilts to positive side (right side of Fig. 3 (b)), and as if being negative above pupil radius H2 and less than H3, then the curve of sine condition violation amount tilts to minus side (left side of Fig. 3 (b)).Derivative φ (h) also can and likewise be negative between H2 and H3 in the place that surpasses pupil radius H3, perhaps also can be in the arbitrfary point that surpasses H3 to just changing.Wherein, (6), (7) formula below preferred H1, H2 satisfy.
0.19≤H1≤0.62 （6）
0.74≤H2≤0.88 （7）
And be set at f be wavelength X 1 under normal temperature (25 ± 3 ℃) environment for the focal length of object lens, being set at δ F (mm) is the PV value of sine condition violation amount, is set at OSC to the sine condition violation amount of pupil radius H1, H2 respectively Min(mm), OSC Max(mm) time, preferred satisfied following (8), (9) formula.
0.0013≤δF／f≤0.0064（8）
δF=|OSC min－OSC max| （9）
Because when the value of OSCmin becomes big, three grades of comas when then focusing saltus step increase, when the value of OSCmax becomes big, the Pyatyi coma when then focusing saltus step increases, so preferably satisfy (10), make both balances to (11) formula.
－0.0021≤OSC min／f≤－0.0001（10）
－0.0001≤OSC max／f≤0.0062（11）
The amount of movement that object lens also can preferentially dwindle coupled lens is set the shape of sine condition violation amount, and the residual aberration in the time of also can be preferentially the focusing saltus step suppresses the little shape of setting sine condition violation amount.
Under normal temperature (25 ± 3 ℃) environment; When the cover glass thickness setting that becomes the spherical aberration of the magnification M that satisfies (1) formula minimum is T (mm); Make the skew ray bundle of angle of half field-of view 1 degree when object lens are injected; Preferably three grades of coma CM3 (λ rms) of the point of optically focused satisfy (12) formula via the cover glass thickness T, and the Pyatyi coma CM5 (λ rms) of the point of optically focused satisfies (13) formula via the cover glass thickness T
-0.003≤M≤0.003 （1）
0＜|CM3|≤0.026 （12）
0.002≤|CM5|≤0.039 （13）
More preferably three grades of coma CM3 are different with the symbol of Pyatyi coma CM5.
And under normal temperature (25 ± 3 ℃) environment; When the cover glass thickness setting that becomes the spherical aberration of magnification M minimum is T (mm); Make preferably when spending object lens inclining 1 that three grades of coma CM3* (λ rms) of the point of optically focused and Pyatyi coma CM5* (λ rms) satisfy (14) formula via the cover glass thickness T
0.145≤|CM3*－CM5*|≤0.229 （14）
At this moment the symbol of also preferred CM3* and CM5* is different.
And preferably the aspherical shape X (h) of the side's of picture optical surface (the preferably big optical surface of radius-of-curvature) has two change poles points in effective radius, and satisfies (15) ~ (18) formula,
0.534≤PV≤0.855 （15）
0.270≤D1≤0.340 （16）
0.780≤D2≤0.930 （17）
0.530≤D3≤0.640 （18）
Wherein,
D1 (mm): be the ratio of the effective radius of the aspherical shape X (h) of the picture side's optical surface relative object lens of radial height of getting first flex point,
D2 (mm): be the ratio of the effective radius of the aspherical shape X (h) of the picture side's optical surface relative object lens of radial height of getting second flex point,
D3 (mm): be the ratio of the effective radius of the second derivative of the aspherical shape X (h) of the picture side's optical surface relative object lens of radial height of getting maximum value,
PV: the absolute value of difference of maximal value and minimum value of second derivative that is the aspherical shape X (h) of picture side's optical surface.
Viewpoint according to lens shape; Preferably in normal temperature (25 ± 3 ℃), for the effective aperture of the refractive index N of the object lens of wavelength X 1 and light source side (object space) optical surface (the preferably little optical surface of radius-of-curvature) satisfied (23) formula of tiltangle (degree) of periphery.
－59.8·N+158＜θ＜－59.8·N+166 （23）
Shown in figure 19, find that there is the most peripheral tiltangle in effective aperture of lensed refractive index N and object space optical surface in embodiments of the invention in certain condition and range.According to this opinion, according to the viewpoint defined of preferred lens shape of the present invention is exactly (23) formula.Figure 19 be normal temperature (25 ± 3 ℃) down the refractive index N of wavelength X 1 be taken at transverse axis, the effective aperture of object space optical surface the tiltangle (degree) of periphery be taken at the longitudinal axis and be drawn as embodiment 1 ~ 14 in the figure of curve.
Be used for to first CD carry out the needed object lens of information recording/regenerating as number formulary value aperture be set at NA1, be used for to second CD carry out the needed object lens of information recording/regenerating as number formulary value aperture be set at NA2 (NA1＞NA2), being used for being set at NA3 (NA2＞NA3) as number formulary value aperture to what the 3rd CD carried out the needed object lens of information recording/regenerating.Preferred NA1 is more than 0.8, below 0.95, is more preferably more than 0.8, below 0.9.Preferred especially NA1 is 0.85.NA2 preferably more than 0.55, below 0.7.Preferred especially NA2 is 0.60 or 0.65.NA3 preferably more than 0.4, below 0.55.Preferred especially NA3 is 0.45 or 0.53.
(32) formula below object lens preferably satisfy.
0.9≤d／f≤1.5（32）
Wherein, d representes the thickness (mm) of object lens on optical axis, and f representes the focal length of the object lens of first light beam.F preferably 1.0mm above, below the 1.8mm.
Under the situation of object lens that is the such short wavelength of reply BD, high NA CD,, then produce the axle outer light beam astigmatism and the problem that can not guarantee operating distance take place when object lens are injected easily if the thickness on the optical axis is excessive with the ratio of objective focal length.On the other hand, if the thickness on the optical axis is too small with the ratio of objective focal length, then generation face displacement sensitivity becomes big problem.Then can suppress to take place astigmatism and face displacement sensitivity through satisfying (32) formula.
The operating distance of the object lens when using first CD preferably 0.15mm above, below the 1.0mm.
Optical information recording/reproducing device of the present invention possesses the optical disc apparatus with above-mentioned optical take-up apparatus.
At this; The optical disc apparatus that is provided at optical information recording/reproducing device is described; Optical disc apparatus has only makes pallet by the mode of taking out to the outside; This pallet can be held in the state that carries CD from the optical information recording/reproducing device body of accommodating optical take-up apparatus etc., comprise in addition contain optical take-up apparatus etc. the optical disc apparatus body together by the mode of taking out to the outside.
Use the optical information recording/reproducing device of above-mentioned modes to be equipped with following structure member substantially, but be not limited thereto.The optical take-up apparatus of being accommodated by housing etc. is arranged, make the optical take-up apparatus drive source of searching motor etc. that optical take-up apparatus moves to interior week of CD or periphery with frame, have the frame of optical take-up apparatus to the optical take-up apparatus conveyer of the interior week of CD or the guide rail of periphery guiding etc. and make and drive spindle drive motor that CD is rotated etc.
Preferably the former mode also is provided with the pallet that can keep being equipped with compact disc states and the loader mechanism that is used to make tray sliding etc. outside these each structure members; The latter's mode then is not provided with pallet and loader mechanism, but the drawer suitable with frame (De ロ ワ one) device from each structure member to the outside that can pull out is set.
The effect of invention
According to the present invention, can provide not only compactness and cost low, and can carry out the optical take-up apparatus of information recording/regenerating CD with multi-layered information recording face.
Description of drawings
Fig. 1 is the figure that comes relatively to represent each spherical aberration according to the discussion result that the present inventor carries out;
Fig. 2 is the figure that is used to explain sine condition;
Fig. 3 is the figure of the example of the discontented capacity of expression sine condition;
Fig. 4 is the figure that optical take-up apparatus PU1 structure represented in summary;
Fig. 5 is taken at effective radius the longitudinal axis, violates sine condition and measure the curve of representing embodiment 1 at transverse axis;
Fig. 6 is taken at effective radius the longitudinal axis, violates sine condition and measure the curve of representing embodiment 2 at transverse axis;
Fig. 7 is taken at effective radius the longitudinal axis, violates sine condition and measure the curve of representing embodiment 3 at transverse axis;
Fig. 8 is taken at effective radius the longitudinal axis, violates sine condition and measure the curve of representing embodiment 4 at transverse axis;
Fig. 9 is taken at effective radius the longitudinal axis, violates sine condition and measure the curve of representing embodiment 5 at transverse axis;
Figure 10 is taken at effective radius the longitudinal axis, violates sine condition and measure the curve of representing embodiment 6 at transverse axis;
Figure 11 is taken at effective radius the longitudinal axis, violates sine condition and measure the curve of representing embodiment 7 at transverse axis;
Figure 12 is taken at effective radius the longitudinal axis, violates sine condition and measure the curve of representing embodiment 8 at transverse axis;
Figure 13 is taken at effective radius the longitudinal axis, violates sine condition and measure the curve of representing embodiment 9 at transverse axis;
Figure 14 is taken at effective radius the longitudinal axis, violates sine condition and measure the curve of representing embodiment 10 at transverse axis;
Figure 15 is taken at effective radius the longitudinal axis, violates sine condition and measure the curve of representing embodiment 11 at transverse axis;
Figure 16 is taken at effective radius the longitudinal axis, violates sine condition and measure the curve of representing embodiment 12 at transverse axis;
Figure 17 is taken at effective radius the longitudinal axis, violates sine condition and measure the curve of representing embodiment 13 at transverse axis;
Figure 18 is taken at effective radius the longitudinal axis, violates sine condition and measure the curve of representing embodiment 14 at transverse axis;
Figure 19 be the refractive index N of the said wavelength X 1 of normal temperature (25 ± 3 ℃) be taken at transverse axis, object space optical surface effective aperture the tiltangle (degree) of periphery be taken at the figure that the longitudinal axis is drawn as embodiment 1 ~ 14 curve;
Figure 20 is the figure of the CD side optical surface shape (sagging (サ グ) amount) of expression embodiment 1 object lens;
Figure 21 is the figure of the CD side optical surface shape (sag of chain) of expression embodiment 2 object lens;
Figure 22 is the figure of the CD side optical surface shape (sag of chain) of expression embodiment 3 object lens;
Figure 23 is the figure of the CD side optical surface shape (sag of chain) of expression embodiment 4 object lens;
Figure 24 is the figure of the CD side optical surface shape (sag of chain) of expression embodiment 5 object lens;
Figure 25 is the figure of the CD side optical surface shape (sag of chain) of expression embodiment 6 object lens;
Figure 26 is the figure of the CD side optical surface shape (sag of chain) of expression embodiment 7 object lens;
Figure 27 is the figure of the CD side optical surface shape (sag of chain) of expression embodiment 8 object lens;
Figure 28 is the figure of the CD side optical surface shape (sag of chain) of expression embodiment 9 object lens;
Figure 29 is the figure of the CD side optical surface shape (sag of chain) of expression embodiment 10 object lens;
Figure 30 is the figure of the CD side optical surface shape (sag of chain) of expression embodiment 11 object lens;
Figure 31 is the figure of the CD side optical surface shape (sag of chain) of expression embodiment 12 object lens;
Figure 32 is the figure of the CD side optical surface shape (sag of chain) of expression embodiment 13 object lens;
Figure 33 is the figure of the CD side optical surface shape (sag of chain) of expression embodiment 14 object lens;
Embodiment
Following with reference to the description of drawings embodiments of the invention.Fig. 4 is the figure that the present embodiment optical take-up apparatus PU1 structure of information recording/regenerating represented can carry out rightly for the CD BD that has three information recording surface RL1 ~ RL3 (being set at according to the little order of distance of injecting face to the light beam of CD is RL1, RL2, RL3) at thickness direction in summary.This optical take-up apparatus PU1 can be installed in optical information recording/reproducing device.And the present invention is not limited to present embodiment.For example Fig. 4 has represented the optical take-up apparatus that BD is special-purpose, but through object lens OBJ as BD/DVD/CD exchange with or the object lens used of individual configuration DVD/CD, also can set for is the optical take-up apparatus of BD/DVD/CD exchange usefulness.
Optical take-up apparatus PU1 has: object lens OBJ; Make object lens OBJ to focusing direction and tracking direction move with to CD radially and/or three actuator AC2 of tangential tilt; λ/4 wavelength plate QWP; The coupled lens CL of the negative lens group L3 that comprises the positive lens groups L2 that constitutes by a positive lens and constitute by a negative lens with negative power with positive light coke; The single shaft actuator AC1 that positive lens groups L2 is moved at optical axis direction; Polarizing prism PBS; Penetrate the semiconductor laser LD of 405nm laser beam (light beam); Sensor is used laser instrument SL; Acceptance is from the photo detector PD of information recording surface RL1 ~ RL3 folded light beam of BD.In the present embodiment, coupled lens CL is configured between polarizing prism PBS and the λ/4 wavelength plate QWP, also can be single element lens.In the present embodiment, object lens OBJ is the single element lens of plastics system or glass.
The situation of the first information record surface RL1 of BD being carried out recoding/reproduction at first is described.This situation is to utilize single shaft actuator AC1 to make the positive lens groups L2 of coupled lens CL move to the position of solid line.At this; The divergent beams transmission-polarizing light prism PBS of the light beam (λ 1=405nm) that penetrates from blue purple semiconductor laser LD and through the negative lens group L3 of coupled lens CL the angle of divergence increases; And then after becoming the weak convergence light beam through positive lens groups L2; Utilize λ/4 wavelength plate QWP and be transformed into circularly polarized light from rectilinearly polarized light; Utilize not shown diaphragm and limit its beam diameter, on first information record surface RL1, form a little through object lens OBJ and such shown in solid line via the transparency carrier PL1 of first thickness.
In the folded light beam of having been modulated by pits on the first information record surface RL1 once more behind transmission object lens OBJ, the diaphragm; Utilize λ/4 wavelength plate QWP and be transformed into rectilinearly polarized light from circularly polarized light; Positive lens groups L2 and negative lens group L3 through coupled lens CL become converging beam, are being utilized sensor to be converged on the sensitive surface of photo detector PD with laser instrument SL by polarizing prism PBS reflection back.And the output signal that uses photo detector PD utilizes three actuator AC2 to make object lens OBJ focusing and follows the tracks of, and reads the information that is recorded in first information record surface RL1 thus.
Then the situation of recoding/reproduction is carried out in explanation to the second information recording surface RL2 of BD.This situation is to utilize single shaft actuator AC1 to make the positive lens groups L2 of coupled lens CL move to dashdotted position.At this; The divergent beams transmission-polarizing light prism PBS of the light beam (λ 1=405nm) that penetrates from blue purple semiconductor laser LD and through the negative lens group L3 of coupled lens CL the angle of divergence increases; And then after becoming the almost parallel light beam through positive lens groups L2; Utilize λ/4 wavelength plate QWP and be transformed into circularly polarized light from rectilinearly polarized light; Utilize not shown diaphragm and limit its beam diameter, on the second information recording surface RL2, form a little through object lens OBJ and such shown in dot-and-dash line via the transparency carrier PL2 of second thickness (than first thicker).
In the folded light beam of having been modulated by pits on the second information recording surface RL2 once more behind transmission object lens OBJ, the diaphragm; Utilize λ/4 wavelength plate QWP and be transformed into rectilinearly polarized light from circularly polarized light; Positive lens groups L2 and negative lens group L3 through coupled lens CL become converging beam, are being utilized sensor to be converged on the sensitive surface of photo detector PD with laser instrument SL by polarizing prism PBS reflection back.And the output signal that uses photo detector PD utilizes three actuator AC2 to make object lens OBJ focusing and follows the tracks of, and reads the information that is recorded in the second information recording surface RL2 thus.
Then the situation of recoding/reproduction is carried out in explanation to the 3rd information recording surface RL3 of BD.This situation is to utilize single shaft actuator AC1 to make the positive lens groups L2 of coupled lens CL move to the position of dotted line.At this; The divergent beams transmission-polarizing light prism PBS of the light beam (λ 1=405nm) that penetrates from blue purple semiconductor laser LD and through the negative lens group L3 of coupled lens CL the angle of divergence increases; And then after becoming weak divergent beams through positive lens groups L2; Utilize λ/4 wavelength plate QWP and be transformed into circularly polarized light from rectilinearly polarized light; Utilize not shown diaphragm and limit its beam diameter, on the 3rd information recording surface RL3, form a little through object lens OBJ and such shown in dotted line via the transparency carrier PL3 of the 3rd thickness (than second thicker).
In the folded light beam of having been modulated by pits on the 3rd information recording surface RL3 once more behind transmission object lens OBJ, the diaphragm; Utilize λ/4 wavelength plate QWP and be transformed into rectilinearly polarized light from circularly polarized light; Positive lens groups L2 and negative lens group L3 through coupled lens CL become converging beam, are being utilized sensor to be converged on the sensitive surface of photo detector PD with laser instrument SL by polarizing prism PBS reflection back.And the output signal that uses photo detector PD utilizes three actuator AC2 to make object lens OBJ focusing and follows the tracks of, and reads the information that is recorded in the 3rd information recording surface RL3 thus.
In above embodiment, when CD being carried out recording of information and/or reproducing, for the coma that the warpage and the inclination of proofreading and correct owing to CD causes generation, utilize three actuator AC2 make object lens OBJ along CD radially and/or tangential tilt.Thus, can stably carry out recording of information and/or reproduction for CD with warpage, even and CD the situation of inclination is arranged in rotation, also can keep the quality of the point on the information recording surface well.
Embodiment
Then, can be in following explanation by the embodiment of the object lens of the foregoing description use.The design wavelength of object lens is 405nm or 407.5nm, and the R in the following table representes that radius-of-curvature, NA represent that numerical aperture, the n (OBL) of object lens represent that refractive index, n (C.G) for the objective lens design wavelength represent the refractive index for the design wavelength of CD transparency carrier.(lens data that comprises table) is 10 power multiplier (for example 2.5 * 10 afterwards -3) (for example 2.5 * E-3) represent to use E.The optical surface of object lens is respectively by be formed the axisymmetric aspheric surface around optical axis of the coefficient shown in the table 1 to the mathematical expression defined of mathematical expression 1 substitution.
[mathematical expression 1]
X ( h ) = ( h 2 / r ) 1 + 1 - ( 1 + k ) ( h / r ) 2 + &Sigma; i = 0 10 A 2 i h 2 i
At this, X (h) is that axle (being set at the direct of travel of light just), the κ of optical axis direction is that circular cone coefficient, A2i are that aspheric surface coefficient, h are that height, r to optical axis is paraxial radius-of-curvature.
(embodiment 1)
The lens data of table 1 expression embodiment 1.Table 2 expression the skew ray bundle of angle of half field-of view 1 degree when the object lens of embodiment 1 are injected three grades of spherical aberration CM3 and Pyatyi spherical aberration CM5 that Shi Zaidian produces and this object lens inclining 1 are spent at three grades of spherical aberration CM3* and Pyatyi spherical aberration CM5* via the some generation of cover glass thickness T optically focused.And Figure 20 representes the optical surface shape of the CD side of present embodiment object lens.Present embodiment is the multilayer BD (T of reply more than three layers MAX=0.1mm, T MIN=0.05mm) plastics system object lens, T=0.08mm.Fig. 5 representes the sine condition violation discharge curve of embodiment 1.In the present embodiment, f=1.41, H1=0.62, H2=0.87, δ F/f=0.0013, OSC Max/ f=0.0006, OSC Min/ f=-0.0008, CM3=0.002, CM5=-0.004, CM3*=-0163, CM5*=-0.017.
Figure BDA00001794214200361
(embodiment 2)
The lens data of table 3 expression embodiment 2.Table 4 expression the skew ray bundle of angle of half field-of view 1 degree when the object lens of embodiment 2 are injected three grades of spherical aberration CM3 and Pyatyi spherical aberration CM5 that Shi Zaidian produces and this object lens inclining 1 are spent at three grades of spherical aberration CM3* and Pyatyi spherical aberration CM5* via the some generation of cover glass thickness T optically focused.And Figure 21 representes the optical surface shape of the CD side of present embodiment object lens.Present embodiment is the multilayer BD (T of reply more than three layers MAX=0.1mm, T MIN=0.05mm) plastics system object lens, T=0.08mm.Fig. 6 representes the sine condition violation discharge curve of embodiment 2.In the present embodiment, f=1.41, H1=0.61, H2=0.88, δ F/f=0.0020, OSC Max/ f=-0.0001, OSC Min/ f=-0.0021, CM3=0.008, CM5=-0.002, CM3*=-0.088, CM5*=-0.011.
Figure BDA00001794214200371
(embodiment 3)
The lens data of table 5 expression embodiment 3.Table 6 expression the skew ray bundle of angle of half field-of view 1 degree when the object lens of embodiment 3 are injected three grades of spherical aberration CM3 and Pyatyi spherical aberration CM5 that Shi Zaidian produces and this object lens inclining 1 are spent at three grades of spherical aberration CM3* and Pyatyi spherical aberration CM5* via the some generation of cover glass thickness T optically focused.And Figure 22 representes the optical surface shape of the CD side of present embodiment object lens.Present embodiment is the multilayer BD (T of reply more than three layers MAX=0.1mm, T MIN=0.05mm) plastics system object lens, T=0.08mm.Fig. 7 representes the sine condition violation discharge curve of embodiment 3.In the present embodiment, f=1.41, H1=0.5, H2=0.85, δ F/f=0.0032, OSC Max/ f=0.0023, OSC Min/ f=-0.0009, CM3=0.007, CM5=-0.021, CM3*=-0.087, CM5*=-0.008.
Figure BDA00001794214200381
(embodiment 4)
The lens data of table 7 expression embodiment 4.Table 8 expression the skew ray bundle of angle of half field-of view 1 degree when the object lens of embodiment 4 are injected three grades of spherical aberration CM3 and Pyatyi spherical aberration CM5 that Shi Zaidian produces and this object lens inclining 1 are spent at three grades of spherical aberration CM3* and Pyatyi spherical aberration CM5* via the some generation of cover glass thickness T optically focused.And Figure 23 representes the optical surface shape of the CD side of present embodiment object lens.Present embodiment is the multilayer BD (T of reply more than three layers MAX=0.1mm, T MIN=0.05mm) glass object lens, T=0.08mm.Fig. 8 representes the sine condition violation discharge curve of embodiment 4.In the present embodiment, f=1.41, H1=0.395, H2=0.84, δ F/f=0.0043, OSC Max/ f=0.0029, OSC Min/ f=-0.0014, CM3=0.019, CM5=-0.022, CM3*=-0.098, CM5*=0.010.
Figure BDA00001794214200391
(embodiment 5)
The lens data of table 9 expression embodiment 5.Table 10 expression the skew ray bundle of angle of half field-of view 1 degree when the object lens of embodiment 5 are injected three grades of spherical aberration CM3 and Pyatyi spherical aberration CM5 that Shi Zaidian produces and this object lens inclining 1 are spent at three grades of spherical aberration CM3* and Pyatyi spherical aberration CM5* via the some generation of cover glass thickness T optically focused.And Figure 24 representes the optical surface shape of the CD side of present embodiment object lens.Present embodiment is the multilayer BD (T of reply more than three layers MAX=0.1mm, T MIN=0.05mm) glass object lens, T=0.08mm.Fig. 9 representes the sine condition violation discharge curve of embodiment 5.In the present embodiment, f=1.41, H1=0.42, H2=0.85, δ F/f=0.0045, OSC Max/ f=0.0025, OSC Min/ f=-0.0020, CM3=0.026, CM5=-0.018, CM3*=-0.106, CM5*=0.006.
Execute example 6)
The lens data of table 11 expression embodiment 6.Table 12 expression the skew ray bundle of angle of half field-of view 1 degree when the object lens of embodiment 6 are injected three grades of spherical aberration CM3 and Pyatyi spherical aberration CM5 that Shi Zaidian produces and this object lens inclining 1 are spent at three grades of spherical aberration CM3* and Pyatyi spherical aberration CM5* via the some generation of cover glass thickness T optically focused.And Figure 25 representes the optical surface shape of the CD side of present embodiment object lens.Present embodiment is the multilayer BD (T of reply more than three layers MAX=0.1mm, T MIN=0.05mm) glass object lens, T=0.08mm.Figure 10 representes the sine condition violation discharge curve of embodiment 6.In the present embodiment, f=1.41, H1=0.455, H2=0.82, δ F/f=0.0025, OSC Max/ f=0.0009, OSC Min/ f=-0.0015, CM3=0.007, CM5=-0.012, CM3*=-0.087, CM5*=0.000.
Figure BDA00001794214200411
(embodiment 7)
The lens data of table 13 expression embodiment 7.Table 14 expression the skew ray bundle of angle of half field-of view 1 degree when the object lens of embodiment 7 are injected three grades of spherical aberration CM3 and Pyatyi spherical aberration CM5 that Shi Zaidian produces and this object lens inclining 1 are spent at three grades of spherical aberration CM3* and Pyatyi spherical aberration CM5* via the some generation of cover glass thickness T optically focused.And Figure 26 representes the optical surface shape of the CD side of present embodiment object lens.Present embodiment is the multilayer BD (T of reply more than three layers MAX=0.1mm, T MIN=0.05mm) glass object lens, T=0.08mm.Figure 11 representes the sine condition violation discharge curve of embodiment 7.In the present embodiment, f=1.41, H1=0.435, H2=0.805, δ F/f=0.0025, OSC Max/ f=0.0012, OSC Min/ f=-0.0013, CM3=0.006, CM5=-0.013, CM3*=-0.172, CM5*=0.003.
Figure BDA00001794214200421
(embodiment 8)
The lens data of table 15 expression embodiment 8.Table 15 expression the skew ray bundle of angle of half field-of view 1 degree when the object lens of embodiment 8 are injected three grades of spherical aberration CM3 and Pyatyi spherical aberration CM5 that Shi Zaidian produces and this object lens inclining 1 are spent at three grades of spherical aberration CM3* and Pyatyi spherical aberration CM5* via the some generation of cover glass thickness T optically focused.And Figure 27 representes the optical surface shape of the CD side of present embodiment object lens.Present embodiment is the multilayer BD (T of reply more than three layers MAX=0.1mm, T MIN=0.05mm) glass object lens, T=0.08mm.Figure 12 representes the sine condition violation discharge curve of embodiment 8.In the present embodiment, f=1.41, H1=0.195, H2=0.74, δ F/f=0.0050, OSC Max/ f=0.0048, OSC Min/ f=-0.0002, CM3=-0.014, CM5=-0.031, CM3*=-0.133, CM5*=0.036.
Figure BDA00001794214200431
(embodiment 9)
The lens data of table 17 expression embodiment 9.Table 18 expression the skew ray bundle of angle of half field-of view 1 degree when the object lens of embodiment 9 are injected three grades of spherical aberration CM3 and Pyatyi spherical aberration CM5 that Shi Zaidian produces and this object lens inclining 1 are spent at three grades of spherical aberration CM3* and Pyatyi spherical aberration CM5* via the some generation of cover glass thickness T optically focused.And Figure 28 representes the optical surface shape of the CD side of present embodiment object lens.Present embodiment is the multilayer BD (T of reply more than three layers MAX=0.1mm, T MIN=0.05mm) plastics system object lens, T=0.08mm.Figure 13 representes the sine condition violation discharge curve of embodiment 9.In the present embodiment, f=1.27, H1=0.345, H2=0.765, δ F/f=0.0036, OSC Max/ f=0.0026, OSC Min/ f=-0.0009, CM3=-0.003, CM5=-0.022, CM3*=-0.083, CM5*=0.008.
Figure BDA00001794214200441
(embodiment 10)
The lens data of table 19 expression embodiment 10.Table 20 expression the skew ray bundle of angle of half field-of view 1 degree when the object lens of embodiment 9 are injected three grades of spherical aberration CM3 and Pyatyi spherical aberration CM5 that Shi Zaidian produces and this object lens inclining 1 are spent at three grades of spherical aberration CM3* and Pyatyi spherical aberration CM5* via the some generation of cover glass thickness T optically focused.And Figure 29 representes the optical surface shape of the CD side of present embodiment object lens.Present embodiment is the multilayer BD (T of reply more than three layers MAX=0.1mm, T MIN=0.05mm) plastics system object lens, T=0.08mm.Figure 14 representes the sine condition violation discharge curve of embodiment 10.In the present embodiment, f=1.27, H1=0.3, H2=0.77, δ F/f=0.0041, OSC Max/ f=0.0035, OSC Min/ f=-0.0005, CM3=-0.003, CM5=-0.022, CM3*=-0.083, CM5*=0.008.
Figure BDA00001794214200451
(embodiment 11)
The lens data of table 21 expression embodiment 11.Table 22 expression the skew ray bundle of angle of half field-of view 1 degree when the object lens of embodiment 11 are injected three grades of spherical aberration CM3 and Pyatyi spherical aberration CM5 that Shi Zaidian produces and this object lens inclining 1 are spent at three grades of spherical aberration CM3* and Pyatyi spherical aberration CM5* via the some generation of cover glass thickness T optically focused.And Figure 30 representes the optical surface shape of the CD side of present embodiment object lens.Present embodiment is the multilayer BD (T of reply more than three layers MAX=0.1mm, T MIN=0.05mm) plastics system object lens, T=0.08mm.Figure 15 representes the sine condition violation discharge curve of embodiment 11.In the present embodiment, f=1.27, H1=0.19, H2=0.795, δ F/f=0.0063, OSC Max/ f=0.0062, OSC Min/ f=-0.0001, CM3=0.001, CM5=-0.036, CM3*=-0.085, CM5*=0.023.
Figure BDA00001794214200461
(embodiment 12)
The lens data of table 23 expression embodiment 12.Table 24 expression the skew ray bundle of angle of half field-of view 1 degree when the object lens of embodiment 12 are injected three grades of spherical aberration CM3 and Pyatyi spherical aberration CM5 that Shi Zaidian produces and this object lens inclining 1 are spent at three grades of spherical aberration CM3* and Pyatyi spherical aberration CM5* via the some generation of cover glass thickness T optically focused.And Figure 31 representes the optical surface shape of the CD side of present embodiment object lens.Present embodiment is the multilayer BD (T of reply more than three layers MAX=0.1mm, T MIN=0.05mm) glass object lens, T=0.08mm.Figure 16 representes the sine condition violation discharge curve of embodiment 12.In the present embodiment, f=1.27, H1=0.405, H2=0.815, δ F/f=0.0035, OSC Max/ f=0.0020, OSC Min/ f=-0.0015, CM3=0.008, CM5=-0.019, CM3*=-0.093, CM5*=0.006.
Figure BDA00001794214200471
(embodiment 13)
The lens data of table 25 expression embodiment 13.Table 26 expression the skew ray bundle of angle of half field-of view 1 degree when the object lens of embodiment 13 are injected three grades of spherical aberration CM3 and Pyatyi spherical aberration CM5 that Shi Zaidian produces and this object lens inclining 1 are spent at three grades of spherical aberration CM3* and Pyatyi spherical aberration CM5* via the some generation of cover glass thickness T optically focused.And Figure 32 representes the optical surface shape of the CD side of present embodiment object lens.Present embodiment is the multilayer BD (T of reply more than three layers MAX=0.1mm, T MIN=0.05mm) glass object lens, T=0.08mm.Figure 17 representes the sine condition violation discharge curve of embodiment 13.In the present embodiment, f=1.27, H1=0.385, H2=0.82, δ F/f=0.0044, OSC Max/ f=0.0032, OSC Min/ f=-0.0013, CM3=0.009, CM5=-0.025, CM3*=-0.094, CM5*=0.012.
Figure BDA00001794214200481
(embodiment 14)
The lens data of table 27 expression embodiment 14.Table 28 expression the skew ray bundle of angle of half field-of view 1 degree when the object lens of embodiment 14 are injected three grades of spherical aberration CM3 and Pyatyi spherical aberration CM5 that Shi Zaidian produces and this object lens inclining 1 are spent at three grades of spherical aberration CM3* and Pyatyi spherical aberration CM5* via the some generation of cover glass thickness T optically focused.And Figure 33 representes the optical surface shape of the CD side of present embodiment object lens.Present embodiment is the multilayer BD (T of reply more than three layers MAX=0.1mm, T MIN=0.05mm) glass object lens, T=0.08mm.Figure 18 representes the sine condition violation discharge curve of embodiment 14.In the present embodiment, f=1.27, H1=0.305, H2=0.815, δ F/f=0.0061, OSC Max/ f=0.0054, OSC Min/ f=-0.0007, CM3=0.004, CM5=-0.039, CM3*=-0.089, CM5*=0.025.
Figure BDA00001794214200491
Table 29 gathers the characteristic value of representing embodiment 1 ~ 7, and table 30 gathers the characteristic value of representing embodiment 8 ~ 14
Figure BDA00001794214200501
The present invention is not limited to the embodiment that instructions is put down in writing, and it is that insider as this area understands that embodiment that puts down in writing according to this instructions and thought then include other embodiment, variation.The record of instructions and embodiment be eventually illustration as purpose, scope of the present invention by after the claim stated represent.
Symbol description
The blue purple semiconductor laser of OBJ object lens PU1 optical take-up apparatus LD
Three actuator PBS of AC1 single shaft actuator AC2 polarizing prism
CL coupled lens L2 positive lens groups L3 negative lens group
The PL1 first transparency carrier PL2 second transparency carrier PL3 the 3rd transparency carrier
The RL1 first information record surface RL2 second information recording surface RL3 the 3rd information recording surface
QWP λ/4 wavelength plates

Claims (16)

1. object lens that the optical take-up apparatus that carries out recording of information and/or reproduction is used; Optical take-up apparatus has the wavelength X 1 of ejaculation (light source and the object lens of 390nm＜λ 1＜415nm) light beam; CD has the mutual different information recording surface of the distance (transparency carrier thickness) of injecting face to light beam more than three layers at thickness direction; Select in the said CD information recording surface arbitrarily; Through the information recording surface optically focused of said object lens, it is characterized in that the light beam of the wavelength X 1 that penetrates from said light source to said selection
Said object lens are single element lens,
Picture number formulary value aperture (NA) is more than 0.8, below 0.95,
Under normal temperature (25 ± 3 ℃) environment; The sine condition violation amount of the magnification M of satisfied (1) formula is got first maximum value at pupil radius H1 respectively and is got second maximum value at pupil radius H2; And be set at 0.9 to pupil radius H3 when above; Satisfy (2) formula, and the derivative φ (h) of sine condition violation amount satisfies (3) ~ (5) formula
－0.003≤M≤0.003 （1）
H1＜H2＜H3 （2）
φ（h）＜0.0（h＜H1） （3）
φ（h）＞0.0（H1＜h＜H2） （4）
φ（h）＜0.0（H2＜h＜H3） （5）
Wherein, said pupil radius H1, H2, H3 are the relative values that is set to the effective radius of said object lens at 1 o'clock.
2. object lens as claimed in claim 1 is characterized in that, the formula below satisfying
0.19≤H1≤0.62 （6）
0.74≤H2≤0.88 （7）
0.0013≤δF／f≤0.0064（8）
Wherein, f is the focal length of the said object lens of the said wavelength X 1 under normal temperature (25 ± 3 ℃) environment, and δ F (mm) is the PV value of sine condition violation amount, is set at OSC respectively in the sine condition violation amount said pupil radius H1, H2 Min(mm), OSC Max(mm) time, represent by following (9) formula
δF=|OSC min－OSC max| （9）。
3. according to claim 1 or claim 2 object lens is characterized in that, when said first maximum value sine condition violation amount is set at OSC Min(mm), when being set at f (mm) to the focal length of the said wavelength X 1 under normal temperature (25 ± 3 ℃) environment, satisfy (10) formula
－0.0021≤OSC min／f≤－0.0001（10）。
4. according to claim 1 or claim 2 object lens is characterized in that, when said second maximum value sine condition violation amount is set at OSC Max(mm), when being set at f (mm) to the focal length of the said wavelength X 1 under normal temperature (25 ± 3 ℃) environment, satisfy (11) formula
－0.0001≤OSC max／f≤0.0062（11）。
5. object lens that the optical take-up apparatus that carries out recording of information and/or reproduction is used; Optical take-up apparatus has the wavelength X 1 of ejaculation (light source and the object lens of 390nm＜λ 1＜415nm) light beam; CD has the mutual different information recording surface of the distance (transparency carrier thickness) of injecting face to light beam more than three layers at thickness direction; Select in the said CD information recording surface arbitrarily; Through the information recording surface optically focused of said object lens, it is characterized in that the light beam of the wavelength X 1 that penetrates from said light source to said selection
Said object lens are single element lens,
Picture number formulary value aperture (NA) is more than 0.8, below 0.95,
Under normal temperature (25 ± 3 ℃) environment; When the cover glass thickness setting that becomes the spherical aberration of the magnification M that satisfies (1) formula minimum is T (mm); Make the skew ray bundle of angle of half field-of view 1 degree when said object lens are injected; Three grades of coma CM3 (λ rms) of the point of optically focused satisfy (12) formula via said cover glass thickness T; The Pyatyi coma CM5 (λ rms) of the point of optically focused satisfies (13) formula via said cover glass thickness T, and said three grades of coma CM3 are different with the symbol of said Pyatyi coma CM5
－0.003≤M≤0.003 （1）
0＜|CM3|≤0.026 （12）
0.002≤|CM5|≤0.039 （13）。
6. object lens that the optical take-up apparatus that carries out recording of information and/or reproduction is used; Optical take-up apparatus has the wavelength X 1 of ejaculation (light source and the object lens of 390nm＜λ 1＜415nm) light beam; CD has the mutual different information recording surface of the distance (transparency carrier thickness) of injecting face to light beam more than three layers at thickness direction; Select in the said CD information recording surface arbitrarily; Through the information recording surface optically focused of said object lens, it is characterized in that the light beam of the wavelength X 1 that penetrates from said light source to said selection
Said object lens are single element lens,
Picture number formulary value aperture (NA) is more than 0.8, below 0.95,
Under normal temperature (25 ± 3 ℃) environment; When the cover glass thickness setting that becomes the spherical aberration of the magnification M that satisfies (1) formula minimum is T (mm); Make when spending said object lens inclining 1 that three grades of coma CM3* (λ rms) of the point of optically focused and Pyatyi coma CM5* (λ rms) satisfy (14) formula via said cover glass thickness T
－0.003≤M≤0.003 （1）
0.145≤|CM3*－CM5*|≤0.229 （14）。
7. object lens that the optical take-up apparatus that carries out recording of information and/or reproduction is used; Optical take-up apparatus has the wavelength X 1 of ejaculation (light source and the object lens of 390nm＜λ 1＜415nm) light beam; CD has the mutual different information recording surface of the distance (transparency carrier thickness) of injecting face to light beam more than three layers at thickness direction; Select in the said CD information recording surface arbitrarily; Through the information recording surface optically focused of said object lens, it is characterized in that the light beam of the wavelength X 1 that penetrates from said light source to said selection
Said object lens are single element lens,
Picture number formulary value aperture (NA) is more than 0.8, below 0.95,
The aspherical shape X of picture side's optical surface (h) has two change poles points in effective radius, and satisfies (15) ~ (18) formula,
0.524≤PV≤0.855 （15）
0.270≤D1≤0.340 （16）
0.780≤D2≤0.930 （17）
0.530≤D3≤0.640 （18）
Wherein,
D1 (mm): the aspherical shape X (h) that is picture side's optical surface gets the radial height of first flex point and the ratio of the effective radius of said object lens,
D2 (mm): the aspherical shape X (h) that is picture side's optical surface gets the radial height of second flex point and the ratio of the effective radius of said object lens,
D3 (mm): the second derivative that is the aspherical shape X (h) of picture side's optical surface is got the radial height of maximum value and the ratio of the effective radius of said object lens,
PV: the second derivative that is the aspherical shape X (h) of picture side's optical surface is got the absolute value of the difference of maximal value and minimum value.
8. like each described object lens of claim 1 to 7, it is characterized in that transparency carrier thickness setting minimum in said transparency carrier thickness is T MIN(mm), be transparency carrier thickness setting maximum in the said transparency carrier thickness T MAX(mm) time, under normal temperature (25 ± 3 ℃) environment, make the spherical aberration of said magnification M become satisfied (19) formula of minimum cover glass thickness T (mm), and said object lens are made up of plastic material
T MAX·0.85≤T≤T MAX·1.1 （19）。
9. object lens as claimed in claim 8 is characterized in that, (20) formula below satisfying
T MAX·0.85≤T≤T MAX·1.0 （20）。
10. like each described object lens of claim 1 to 7, it is characterized in that transparency carrier thickness setting minimum in said transparency carrier thickness is T MIN(mm), be transparency carrier thickness setting maximum in the said transparency carrier thickness T MAX(mm) time, under normal temperature (25 ± 3 ℃) environment, make the spherical aberration of said magnification M become satisfied (21) formula of minimum cover glass thickness T (mm), and said object lens are made up of glass material
T MAX·0.75≤T≤T MAX·1.0 （21）。
11. object lens as claimed in claim 10 is characterized in that, (22) formula below satisfying
T MAX·0.8≤T≤T MAX·0.95 （22）。
12., it is characterized in that under normal temperature (25 ± 3 ℃) environment, the most peripheral tiltangle (degree) in the effective aperture of the refractive index N of said wavelength X 1 and object space optical surface satisfies (23) formula like each described object lens of claim 1 to 11
－59.8·N+158＜θ＜－59.8·N+166 （23）。
13., it is characterized in that transparency carrier thickness setting minimum in said transparency carrier thickness is T like each described object lens of claim 1 to 12 MIN(mm), be transparency carrier thickness setting maximum in the said transparency carrier thickness T MAX(mm) time, satisfy (24) formula
0.03（mm）＜T MAX－T MIN＜0.06（mm） （24）。
14. an optical take-up apparatus is characterized in that having: each described object lens of claim 1 to 13, at the coupled lens that optical axis direction can move, move any information recording surface of selecting CD through making said coupled lens at optical axis direction.
15. the described optical take-up apparatus of claim 14 is characterized in that said coupled lens is made up of single element lens.
16. the described optical take-up apparatus of claim 14 is characterized in that, said coupled lens is made up of for these two groups positive lens groups and negative lens group, moves any information recording surface of selecting CD through at least one lens that makes said positive lens groups.
CN2010800584703A 2009-12-25 2010-12-15 Objective lens for optical pickup device and optical pickup device Pending CN102667932A (en)

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JP2009-295184 2009-12-25
JP2009295184 2009-12-25
PCT/JP2010/072530 WO2011078022A1 (en) 2009-12-25 2010-12-15 Objective lens for optical pickup device and optical pickup device

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JP2007133967A (en) * 2005-11-10 2007-05-31 Canon Inc Optical information recording and reproducing device
CN101581824A (en) * 2008-05-16 2009-11-18 富士能株式会社 Objective lens, optical pickup device, and optical recording/reproducing apparatus

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Publication number Priority date Publication date Assignee Title
JP5128428B2 (en) * 2007-09-26 2013-01-23 パナソニック株式会社 OPTICAL HEAD, OPTICAL HEAD MANUFACTURING METHOD, AND OPTICAL DISK DEVICE
JP2009277295A (en) * 2008-05-14 2009-11-26 Hitachi Maxell Ltd Optical pickup lens
JP2010027183A (en) * 2008-07-24 2010-02-04 Hoya Corp Objective lens for optical information recording and reproducing device and optical information recording and reproducing device

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030152014A1 (en) * 2001-09-18 2003-08-14 Asahi Kogaku Kogyo Kabushiki Kaisha High NA objective lens for optical pick-up
JP2007133967A (en) * 2005-11-10 2007-05-31 Canon Inc Optical information recording and reproducing device
CN101581824A (en) * 2008-05-16 2009-11-18 富士能株式会社 Objective lens, optical pickup device, and optical recording/reproducing apparatus

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Application publication date: 20120912