CN1749797A - Objective lens for optical disk, optical pickup device, optical disk recording/playing-back device and optical disk player - Google Patents
Objective lens for optical disk, optical pickup device, optical disk recording/playing-back device and optical disk player Download PDFInfo
- Publication number
- CN1749797A CN1749797A CN 200510096566 CN200510096566A CN1749797A CN 1749797 A CN1749797 A CN 1749797A CN 200510096566 CN200510096566 CN 200510096566 CN 200510096566 A CN200510096566 A CN 200510096566A CN 1749797 A CN1749797 A CN 1749797A
- Authority
- CN
- China
- Prior art keywords
- lens
- aberration
- optical disk
- optical
- numerical aperture
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Landscapes
- Lenses (AREA)
Abstract
The invention provides an objective lens for an optical disk having a numerical aperture of >=0.75, superior in terms of on-axis aberration, off-axis aberration, and eccentric aberration between surfaces, and constituted of a bi-aspherical single lens. The radius of curvature R1 at the apex of the 1st surface 1 of the lens 11 satisfied the expression (1-D)A<R 1<(1+D)A, A=B/C, B=0.85f(n-1), C=n(0.60866-0.11.t/f-0.1272.d/ f)(0.83+0.2.NA), where NA is the numerical aperture of the lens, (n) is the refractive index of the lens, (f)is focal distance, (t) is center thickness, and (d) is the thickness of the transmission layer of the optical disk. D=0.05.
Description
The application is to be that September 18, application number in 2002 are 02142703.8 the applying date, and denomination of invention is divided an application for " objective lens for optical disk, optical sensing means, optical disc recording/reproduction device and disc reproducing apparatus " application for a patent for invention.
Technical field
The present invention relates to have the objective lens for optical disk of the high-NA (NA) of realizing huge capacity compact discs, optical sensing means, optical disc recording/reproduction device and disc reproducing apparatus.
Background technology
In the past, CD CD employing numerical aperture (NA) was 0.45～0.5 object lens, utilized the laser of the about 780nm of wavelength to read or write.And the DVD CD adopts numerical aperture to be about 0.6 object lens, and the laser that utilizes wavelength to be about 650nm is read or write.
But,, developing a kind of shorter light source of wavelength that uses, the CD sensor-based system of future generation of the object lens that numerical aperture is higher in order to improve CD capacity.
And the shorter laser of wavelength can adopt the so-called blue look laser instrument of the about 400nm of wavelength.
Above-mentioned object lens with high-NA for example have the system of following reported literature.
(A)Jpn.J.Appl.Phys.Vol.39(2000)pp.978-979 M.Itonaga et al.“Optical Disk System Using High-Numerical Aperture Single ObjectiveLens and Blue LD”.
(B)Jpn.J.Appl.Phys.Vol.39(2000)pp.937-942 I.Ichimura et al.“Optical Disk Recording Using a GaN Blue-Violet Laser Diode”.
Wherein, a kind of signal-lens system that adopts numerical aperture 0.7 of document (A) report; A kind of system that adopts 2 compound lenss of numerical aperture 0.85 of document (B) report.
Its another feature is: contrast for the system margins that is caused with high NA reduces, the thickness of the regeneration transmission layer that coils is begun attenuate from the 1.2mm of CD or the 0.6mm of DVD.(A) becoming 0.12mm, (B) is 0.1mm.This is also relevant with the distribution method of the nargin size of system.The roughly preferred transmission layer thinner than 0.3mm.
Adopt the system of 2 compound lenss of above-mentioned (B), though numerical aperture is bigger than (A), it needs assembly process and 2 lens of needs, so its production efficiency is low, and the cost height.
Therefore, the signal-lens objective lens for optical disk of preferred value aperture more than 0.7 in the system of future generation.
Drive the signal-lens object lens of having narrated employing numerical aperture 0.6～0.8 in the flat 4-163510 communique the spy.
Moreover, in order to address the above problem, to relate to optical sensing means of the present invention and have: the lens, LASER Light Source and the light probe that have one of above-mentioned characteristic at least.
Said lens, its operating distance and by between the CD radius that is shone from above-mentioned LASER Light Source emitting laser preferably has following relation.
Operating distance＞0.005 * CD radius
Relating to optical disc recording/reproduction device of the present invention has: above-mentioned optical sensing means and utilize above-mentioned optical sensing means to come the device for reproducing recorded of record reproducing optical disc information.
Relating to disc reproducing apparatus of the present invention has: above-mentioned optical sensing means and utilize above-mentioned optical sensing means to reset to be recorded in the replay device of the information on the CD.
Summary of the invention
The known object lens that can design high-NA of past.For example, in " about the research of aperture " (Jitian is youth, the report of science instrumentation research institute of Northeastern University, in March, 1958 just too), be described in detail the method for designing of both-sided aspherical lens with high-NA than especially big aspheric surface aplanat.
Yet, only say so and can design, but fail to produce object lens with high-NA.In order actually to make this object lens, must be the design that to guarantee manufacturing tolerance.And, for reduce under the situation of optical source wavelength change or wavelength influence under the situation of certain width scope is arranged, must be the little object lens of aberration influence.
At this, under the situation of double surface non-spherical lens, the strictest and most important manufacturing tolerance is the off-centre (eccentric between face) between face and the face.So, as the axle of the aberration under object lens vertical incidence situation go up (axially) aberration and as the aberration under the oblique incidence situation spool outside (from axle) aberration, must satisfy simultaneously with the design performance and the manufacturing tolerance of two kinds of aberrations object lens that are representative.
But the design performance of lens and manufacturing tolerance especially if numerical aperture is higher than 0.75, then is difficult to both and takes into account.
In fact, this double surface non-spherical lens, off-axis aberration even do not considering under the situation that above-mentioned manufacturing tolerance designs, also is that the increasing with numerical aperture worsens, if consider manufacturing tolerance, then worsens more.That is to say,, must sacrifice axle and go up aberration and off-axis aberration characteristic in order to ensure bigger eccentric tolerance.
Even aberration is considered eccentric tolerance on the axle, also just deterioration is arranged slightly, still, off-axis aberration surpasses the lens of 0.6 high-NA, if the micron-sized tolerance that will guarantee to make can be brought huge sacrifice for numerical aperture.
And, about aberration, because at first will be can making lens itself as priority condition, so, must make the shape of lens, can satisfy manufacturing tolerance, can improve the aberration characteristic again as far as possible.
For above-mentioned reasons, the past is just being explored the shape of well behaved double surface non-spherical lens, and has delivered various reported literatures.Te Kaiping 5-241069 communique, it is the one example that the spy opens flat 4-163510 communique.
Open the form range of having narrated well behaved lens in the flat 4-163510 communique the spy.But the document is not spoken of and is guaranteed eccentric tolerance.Numerical aperture is unique to surpass the lens (wavelength 532nm, numerical aperture is 0.8 specification) of 0.75 embodiment 2, and the problem of existence is, even very little off-centre also can cause huge aberration.And, do not narrate aberration.
Have, the represented scope of these known references is quite extensive again, and the problem that exists in these scopes is that differing surely, actual design goes out good lens.
The present invention proposes just in view of the above problems, and its purpose is to provide a kind of objective lens for optical disk, and its numerical aperture is more than 0.75, aberration on the axle, decectration aberration between off-axis aberration and face is good, and the aberration characteristic is also good, adopts the double-sized non-spherical simple lens to constitute.
In order to address the above problem, relating to objective lens for optical disk of the present invention is that the two sides is that aspheric numerical aperture NA is the simple lens more than 0.75, and the radius of curvature R 1 on the 1st summit satisfies following formula:
(1-D)A＜R1＜(1+D)A
A＝B/C
B＝0.85f(n-1)
C＝n(0.60866-0.11·t/f-0.1272·d/f)(0.83+0.2·NA)
In the formula, n is the refractive index of these lens, and f is the focal length of these lens, and t is the center thickness (also can be described as a last thickness) of these lens, and d is that the thickness D of the transmission layer of this CD is a positive number, is 0.05 preferably, better is 0.04, and best is 0.03.
Moreover, in order to address the above problem, relating to objective lens for optical disk of the present invention and be that the two sides is is aspheric, numerical aperture NA is the simple lens more than 0.75, the angle u1 ' that the light of the maximum height of the inside of lens and optical axis form satisfies following formula:
(1-D)·K＜sin(u1′)＜(1+D)·K
K＝(0.60866-0.11·t/f-0.1272·d/f)(0.83+0.2·NA)·NA/0.85
In the formula, f is the focal length of these lens, and t is the center thickness of these lens, and d is the transmission layer thickness of this CD.D is a positive number, is 0.06 preferably, better is 0.05, and best is 0.04.
Relate to objective lens for optical disk of the present invention and have above-mentioned formation, the eccentric tolerance between the two sides of lens is in the scope that can make, but the deterioration degree of off-axis aberration characteristic reduces.
Have again, in order to address the above problem, relate to objective lens for optical disk of the present invention, to be that the two sides is aspheric, numerical aperture is the simple lens more than 0.75, below the angle of the angle that the 1st normal on the point of the light institute incident of maximum height and optical axis form for regulation.The angle of afore mentioned rules, 57 degree are for well, and 56 degree are for better, and 55 degree are best.
Moreover, relate to objective lens for optical disk of the present invention, be that two-sided to be aspheric, numerical aperture NA be the simple lens more than 0.75, the light of maximum height carries out the angle θ that the 1st normal in the point of incident and optical axis form can satisfy following formula.
θ＜α-(0.85-NA)/0.15 * 7.1 (degree)
For well, 56 degree are for better with 57 degree for α in the formula, and 55 degree are best.
Moreover the center thickness t and the focal distance f of preferred lens can satisfy following formula.
t＞(1+E)f
In the formula, E is the number more than 0, is preferably 0, more preferably 0.1, be preferably 0.2.
Have, the imaging multiplying power that preferably relates to objective lens for optical disk of the present invention is 0 again.That is to say that preferably, these object lens are no foozle at least, and, under the optical source wavelength situation consistent, directional light is carried out optically focused with the standard wavelength.
And, preferably, relate to objective lens for optical disk of the present invention and be designed to be suitable for the following light source of wavelength 450nm.
The present invention is thinner than DVD dish, CD dish for transmission layer, and especially thickness is the following CD of 0.4mm, has good characteristic.
In the present invention, focal distance f is preferably below the 10mm, if 3.5mm is with next better.
That is to say that the size of light beam (diameter) Φ is determined by following formula, depends on numerical aperture NA and focal distance f.
Φ＝2×NA×f
When focal length is 10mm, NA is 0.75 o'clock, Φ=15mm.This diameter can be described as bigger, because a lot of optical sensing means adopts the light beam of Φ＜5mm.So, wish that focal length is below the 10mm.Have again, if Φ=5mm, NA=0.75 then, f=3.33mm is so focal length is that 3.5mm is better.
And focal length is preferably more than 0, and 0.2mm is above better.
That is to say that operating distance depends on disk thickness, thin CD distance is big.Admissible system is that use glimmer dish uses the short microminiature lens of focal length according to very short operating distance.For example, if CD is made the table read/write architecture, then focal length is that 0.1mm also can design lens.So the following f of being limited to＞0 of focal length gets final product. still, in fact make too little lens, still do not have ripe method at present.Consider this point, we can say that also f＞0.2mm is present lower limit.
Preferably, the upper limit of lens thickness t makes operating distance dw according to the following formula defined for just stipulating.
dw＝fb-d/n′
In the formula, d is a disk thickness, and n ' is the CD refractive index, and fb is stipulated by above-mentioned formula by following formula regulation .R1.
fb＝f(1-t(n-1)/n/R1)
That is to say that if lens thicken, then operating distance shortens, in order to set up as lens, operating distance must be limited.So the upper limit of lens thickness becomes the scope that operating distance is a limit value.This scope is by the focal length of lens, thickness and disk thickness decision.
The scope of lens thickness for example can be set at below the above 3.5mm of 1.5mm.
The present invention can be applicable to the optical sensing means with above-mentioned objective lens for optical disk.Preferably, optical sensing means adopts above-mentioned objective lens for optical disk, makes light beam focus on irradiation along the track of CD, carries out the record or the playback of information signal.Preferably, the imaging multiplying power of optical sensing means is 0.
Description of drawings
Fig. 1 is the figure of the form of explanation object lens.
Fig. 2 is the figure of the light angle of explanation object lens inside and the 2nd 's imaging multiplying power.
Fig. 3 is expression lens thickness and the figure of the regression equation of asking u1 with the relation of the data of asking regression equation to use.
Fig. 4 is expression disk thickness and the figure of the regression equation of asking u1 with the relation of the data of asking regression equation to use.
Fig. 5 is the expression figure of picture multiplying power β with the relation of used data of the variation of numerical aperture and regression equation that hope for success.
Fig. 6 is the figure of derivation of the relational expression of explanation R1 and β '.
Fig. 7 is the figure of the relation of the center thickness of expression lens and the residual aberration that wavelength error (5nm) causes.
Fig. 8 is illustrated in the lens of focal length 2mm, refractive index 1.75, and the refractive index of glass becomes the variable quantity of the fb under 1.7486 the situation.
Fig. 9 is the sectional drawing of the object lens of the 1st embodiment.
Figure 10 is the longitudinal aberration diagram of the object lens of the 1st embodiment.
Figure 11 is the figure that the sine condition of the object lens of the 1st embodiment is discontented with capacity.
Figure 12 is the astigmatism figure of the object lens of the 1st embodiment.
Figure 13 represents to keep on one side refractive index and the thickness identical with the lens of the 1st embodiment, on one side R1 is changed and the situation of aberration increase in the lens designed a little.
Figure 14 is the sectional drawing of the object lens of the 2nd embodiment.
Figure 15 is the longitudinal aberration diagram of the object lens of the 2nd embodiment.
Figure 16 is the figure that the sine condition of the object lens of the 2nd embodiment is discontented with capacity.
Figure 17 is the astigmatism figure of the object lens of the 2nd embodiment.
Figure 18 is the sectional drawing of the object lens of the 3rd embodiment.
Figure 19 is the longitudinal aberration diagram of the object lens of the 3rd embodiment.
Figure 20 is the figure that the sine condition of the object lens of the 3rd embodiment is discontented with capacity.
Figure 21 is the astigmatism figure of the object lens of the 3rd embodiment.
Figure 22 is the sectional drawing of the object lens of the 4th embodiment.
Figure 23 is the longitudinal aberration diagram of the object lens of the 4th embodiment.
Figure 24 is the discontented capacity figure of sine condition of the object lens of the 4th embodiment.
Figure 25 is the astigmatism figure of the object lens of the 4th embodiment.
Figure 26 represents the figure of the geometric relation of lens.
Figure 27 is the figure of the light of expression maximum height to the relation of the 1st incident angle and aberration characteristic.
Figure 28 is expression to practical design value and the figure that compares according to the value that regression equation is determined.
Figure 29 is the sectional drawing of the object lens of the 5th embodiment.
Figure 30 is the longitudinal aberration diagram of the object lens of the 5th embodiment.
Figure 31 is the figure that the sine condition of the object lens of the 5th embodiment is discontented with capacity.
Figure 32 is the astigmatism figure of the object lens of the 5th embodiment.
Figure 33 is the sectional drawing of the object lens of the 6th embodiment.
Figure 34 is the longitudinal aberration diagram of the object lens of the 6th embodiment.
Figure 35 is the figure that the sine condition of the object lens of the 6th embodiment is discontented with capacity.
Figure 36 is the astigmatism figure of the object lens of the 6th embodiment.
Figure 37 is the sectional drawing of the object lens of the 7th embodiment.
Figure 38 is the longitudinal aberration diagram of the object lens of the 7th embodiment.
Figure 39 is the figure that the sine condition of the object lens of the 7th embodiment is discontented with capacity.
Figure 40 is the astigmatism figure of the object lens of the 7th embodiment.
Figure 41 is the figure of the embodiment of expression optical sensing means.
Figure 42 is the figure of the embodiment of expression optical disc recording/reproduction device.
Embodiment
Following with reference to accompanying drawing, describe the embodiment of objective lens for optical disk of the present invention in detail.
At first, before each conditional that objective lens for optical disk satisfied of explanation present embodiment, the basic axle relevant with the design of the lens of present embodiment of explanation earlier gone up the balance of aberration characteristic, off-axis aberration characteristic, eccentric tolerance.Wherein, so-called eccentric tolerance is to define by the increase that the wavefront aberration under the eccentric situation is arranged.
In the present embodiment, in order to ensure aberration, off-axis aberration and manufacturing tolerance on the axle, require following 3 conditions are carried out balance.
(1) for guaranteeing a last aberration, answers the spherical aberration of correcting lens.
(2) for guaranteeing off-axis aberration, lens should satisfy sine condition.
(3) for guaranteeing eccentric tolerance, the 2nd should be satisfied sine condition separately.
(4) in addition, descend, require to meet the following conditions for preventing the aberration characteristic.
(5) adopting the best of each wavelength under the situation with wavelength error to resemble the aberration increase of face should be fewer.Be referred to as the spherical aberration that causes by wavelength error.
To light source,, require to reduce the variation of the focal position that wavelength variations causes for the aberration under the situation that is limited in wavelength spread increases.Wavelength spread is to produce for the noise properties that improves semiconductor laser overlaps to form under the multimodal situation at overlapped high-frequency on the laser.At this, the focal length variations that so-called wavelength variations caused is less, is that expression requires to reduce a last aberration.
Below, at first describe the lens grown form of guaranteeing a last aberration and off-axis aberration in detail, illustrate that then the good lens of aberration characteristic are right.
Double surface non-spherical lens can satisfy 2 conditions (1) and (2) that are used to guarantee a last aberration and off-axis aberration simultaneously.The lens of can satisfy condition simultaneously (1) and (2) are called aplanat.
But a highest wisdom can satisfy condition (1) and (2), then can not satisfy the condition (3) that is used to guarantee eccentric tolerance.
But, if satisfy condition (2), satisfy condition substantially (3), then whole lens satisfy sine condition, and the 2nd face also satisfies sine condition basically, so the 1st face is also satisfying sine condition substantially aspect the relation at light height and refraction angle.
Have again, in the present embodiment, to the condition (1) that is used to guarantee a last aberration and off-axis aberration and (2) and be used to guarantee that the condition (3) of eccentric tolerance carries out balance, satisfaction pro-rata to the basic condition (3) that satisfies, therefore, spool last aberration and off-axis aberration can be guaranteed, the eccentric tolerance of lens can be guaranteed to produce again.
If (Jitian is the youth just too according to above-mentioned " about the research of aperture than especially big aspheric surface aplanat ", the report of science instrumentation research institute of Northeastern University, in March, 1958), then about double surface non-spherical lens, make focal length certain, lens radius being write music for a song adjust under the situation of change, in the category of quite wide vertex radius combination, clearly is to obtain to satisfy condition simultaneously the lens of (1) and (2).
Have again,, then represent eccentric adaptable lens between the opposite can satisfy condition (3) if according to Tanaka Kang Hong " aplanasia simple lens design and the application in Optical Disk System " optics 27,12 (1998) p720.
At this, in the design of the non-spherical lens of satisfy condition (1) and (2),, can be described as the lens strong so to eccentric tolerance accommodation if satisfy condition (3).But, as mentioned above, can not satisfy various conditions simultaneously fully.This is that the design freedom of lens has only 2 of aspheric surfaces, is 2 design freedoms because to 3 conditions.
Have, according to present inventor's analysis, as can be seen, numerical aperture is big more again, and is many more to condition (1)～(3) deviate from integrality.
In fact, if the numerical aperture that DVD CD is in the past used is a numerical aperture that 0.6 lens or CD CD are used is 0.45 lens, so because numerical aperture is little, so, even in very wide scope, change the setting of vertex radius, the increase that remains aberration is less, makes easily between a last aberration and the off-axis aberration to reach balance.No matter that is to say, be starting point with which radius, also all is to sacrifice some axle a little to go up aberration and off-axis aberration, can increase eccentric tolerance.
In contrast, if numerical aperture increases, wavelength decreases, then aberration and wavelength are inversely proportional to, and aberration is increased, and institute is not so that have nargin in the design.Therefore, to this lens, must strict regulations shape (paraxial shape).
At this, the present inventor finds: stipulating the focal length of lens, under the situation of lens thickness and disk thickness, the light that incides in the lens with identical height in the big lens of eccentric tolerance is almost irrelevant with the index of refraction in lens, and is basic identical with respect to the angle of optical axis in lens inside.And find that above-mentioned angle depends on disk thickness and lens thickness.
In the present embodiment, utilize this character, both made between condition (1)～(3) to reach balance, correspondingly guarantee each condition again.
Fig. 1 is the figure of explanation lens form.
Fig. 2 is the figure of the angle of light of explanation lens inside and the 2nd 's imaging multiplying power.
Be injected into the light beam L1 in the object lens 11 with optical axis, the light of maximum height reflects the 1st 1 of object lens 11 with paralleling, forms the angle of u1 with optical axis, in addition, reflects the 2nd 2 of object lens 11, forms the angle of u2 with optical axis.
Here, the expression numerical aperture is 0.85 o'clock a formula, and u1 is the angle in the light of the maximum height of the 1st 1 refraction and optical axis formation.But the aplanasia of satisfy condition in utilization (1) and (2) is carried out under the situation of aspherisation, also is that numerical aperture is the angle that 0.85 light forms.As previously mentioned, this angle depends on the center thickness t and the disk thickness d of the lens relative with the focal distance f of lens in the good lens of characteristic, and is irrelevant with the refractive index of lens.This formula is expressed as follows.
Sin(u1)＝0.60866-0.11t/f-0.1272d/f ……(6)
Fig. 3 is expression regression equation of finding the solution u1 relevant with lens thickness and the figure that finds the solution the relation of the used data of regression equation.Symbol among the figure: ◆ (black box) represents real design load; Straight line among the figure is represented by the definite value of regression equation.
Real design load is to be 2mm in focal distance f, and the refractive index n of the glass material of lens is 1.75, and the thickness d of the transmission layer of CD is under the situation of 0.1mm, changes the designed value of thickness t of lens.Real design load is very consistent with the value of being determined by regression equation, expresses the correctness of regression equation.
Fig. 4 is expression regression equation of finding the solution u1 relevant with disc thickness and the figure that finds the solution the relation of the used data of regression equation.Symbol among the figure ◆ (black box) represents real design load, the straight line among the figure are represented by the definite value of regression equation.
Real design load is to be 2mm in focal distance f, and the refractive index n of the glass material of lens is 1.75, when the thickness t of the transmission layer of lens is 3mm, and the value that the thickness d of change dish is designed.Real design load is very consistent with the value of being determined by regression equation, expresses the correctness of regression equation.
So, when utilizing following formula (6) to determine each constant of lens, it is very simple using paraxial formula.
But, these lens, the 1st and the 2nd face can satisfy sine condition individually basically.In the formula, the relation of u1 and u2 is decided by the 2nd imaging effect.But, so-called face can satisfy sine condition individually, is meant that the imaging multiplying power of the real light in the face and the height of light have nothing to do, and is to get the certain value identical with paraxial multiplying power.
That is to say, be β as if the paraxial imagery multiplying power of establishing the 2nd, and then the relation of following formula is set up.In the formula, up1, up2 are the inclinations of paraxial rays, and u1, u2 are the inclinations of real light.
β＝n·up1/up2＝n·sin(u1)/sin(u2)
In the formula, the light numerical aperture of maximum height, promptly sin (u2) is 0.85, so can get following formula
β＝n·sin(u1)/0.85
So, the present inventor has found that u1 (up1 and β) changes with numerical aperture.
This is because if satisfy condition (1) and (2), though then condition (3) still remains a point tolerance, if utilize the most peripheral of the lens of light refraction angle maximum to satisfy condition (3), then off-centre is had the strongest adaptive faculty.Therefore, β changes with numerical aperture.
The β that has considered numerical aperture can be expressed from the next through the β ' after generally (broad sense) is changed.The 2nd imaging multiplying power β ' has added numerical aperture (NA).
β’＝β(0.83+0.2·NA)
Fig. 5 is the figure of expression for the relation of the employed data of variation of obtaining the imaging multiplying power β ' relevant with numerical aperture and regression equation.Symbol among the figure ◆ represent real design load, the straight line among the figure are represented by the definite value of regression equation.
Real design load is to be 2mm in focal distance f, and the refractive index n of glass material is 1.75, and lens thickness t is under the situation of 2mm, changes numerical aperture and the value that designs.Real design load is quite consistent with the value of being determined by regression equation, the correctness of expression regression equation.
In the formula, following relation is arranged between R1 and the multiplying power β ':
R1＝f(n-1)/β’
Fig. 6 is the figure of the derivation of this formula of explanation.
f′＝R/(n-1)
The B of Fig. 6 represents that image planes (image space) 112 is the situation of refractive index n.Be injected into the 1st 101 of curvature R101 in the light L101 that parallels with optical axis from the 1st 101 vertex on the position of distance L with optical axis intersection.In the case, following relational expression is set up:
f′＝L/n
So the 1st 101 curvature R101 can be expressed from the next:
R101＝(n-1)f′＝(n-1)/n·L
The c of Fig. 6 is the figure of explanation to the biconvex lens expansion.The light that parallels with the optical axis of maximum height h is injected in the lenticular lens 113.L among the figure is equivalent to the L shown in Fig. 6 B.Definition according to multiplying power can get following formula:
β＝n·u1/u2＝n·f/L
Promptly become following formula:
L＝n·f/β
If use this formula, then available refractive index n, focal distance f, imaging multiplying power β represent the 1st 101 radius of curvature R 101:
R101＝(n-1)·f/β
Can obtain the relational expression of above-mentioned R1 and β ' like this.If ask R1, then can get following formula according to following formula:
R1＝B/C
B＝0.85f(n-1)
C＝n(0.60866-0.11·t/f-0.1272·d/f)(0.83+0.2·NA)
In numerical aperture is under the situation of the lens more than 0.75, and in order to design the lens that fully satisfy eccentric tolerance, according to above-mentioned radius of curvature R 1, with 0.05 for well, 0.04 is better, best below 0.03.
In the formula, sin (u1) and R1 are inversely proportional to.As the characteristic of sin function, if compare with u1, then the variation of sin (u1) is little, so the variation of u1 is big.That is to say, compare the wide ranges that u1 allowed with the scope that R1 is allowed.
If this relation is put in order, then can be expressed as the following condition relative with the 1st radius of curvature R 1:
(1-D)A＜R1＜(1+D)A ……(7)
A＝B/C
B＝0.85f(n-1)
C＝n(0.60866-0.11·t/f-0.1272·d/f)(0.83+0.2·NA)
In the formula, D is a positive number, is advisable with 0.05, and 0.04 is better, and 0.03 is best.
And the influence of the transmission layer of dish is smaller, in refractive index is 1.45～1.65 scope, does not have big variation.
Above-mentioned 0.03～0.05 amplitude, because the refractive index difference of this dish, this is the value that comprises because of the different fine differences that produce of refractive index of lens strictly speaking.
And the index of refraction in lens is low, and numerical aperture is that nargin increases during less than 0.75 value, therefore, is departing from this value 5%, can obtain the good design of cardinal principle.
Generally speaking, if satisfy the condition (7) relevant, then can satisfy a last aberration characteristic, off-axis aberration characteristic and eccentric tolerance (making the aberration increase) simultaneously with the radius of curvature R 1 of the 1st on lens.
Further remark additionally, the non-spherical lens of the embodiment of the invention both can be rotational symmetric lens (centered optical system) with respect to optical axis, also can be to make the such shape of the vicissitudinous slightly toric lens of aspherical shape (toric lens) according to the direction difference.Under the situation of shape as the toric lens, self-evident, also must make the 1st radius of curvature R 1 of all directions meet above-mentioned scope.
If the 1st radius of curvature R 1 is set in the scope shown in the condition (7), then the 2nd curvature of face radius R 2 utilizes following formula automatically to determine according to the focal distance f of having set.And this formula is easy to derive the basic form under the situation that provides two-sided radius and thickness, that calculate signal-lens paraxial focal length.
R2＝G/H
G＝f(n-1)(t(n-1)/n-R1)
H＝(R1-f(n-1))
Like this, decide the radius of curvature R 1 of the 1st vertex of surface and the radius of curvature R 2 of the 2nd vertex of surface.If according to this radius-of-curvature, under the situation of satisfy condition at the same time (1) and (2), make double-sized non-sphericalization, then from the aspheric shape of a kind of meaning decision.At this moment, the satisfaction of the sine condition of energy raising condition (3) can obtain the big lens of eccentric tolerance.
As mentioned above, (1) and the condition of can not both satisfying condition fully (2), (3) satisfy condition again.This is that the design freedom of lens has only 2 aspheric surfaces because for 3 conditions, and design freedom is 2.So, also can change a little the aspherical shape that obtains with said method, increase eccentric tolerance.In the case, though can not avoid degenerating of a last aberration or off-axis aberration,, can guarantee important manufacturing tolerance in order to obtain practical lens.
In other words, suitably sacrifice on the axle performance of aberration and off-axis aberration in when design and guarantee eccentric tolerance, between averages out.In addition, also can also regard this design project as the satisfaction degree to above-mentioned 3 conditions (1)～(3) carry out proportional distribution.
And, when like this aspherical shape being explored, if do not satisfy condition (6) or (7), so as the radius of the sphere of starting point, will cause eccentric tolerance, off-axis aberration or or the axle increase of going up aberration, can not do sends as an envoy to reaches the design of balance between the aberration.
But said lens because guaranteed eccentric tolerance, is not considered condition (4) and (5), so can not satisfy the adequate condition of guaranteeing the aberration characteristic.Below describe the aberration characteristic in detail.
Here, the center thickness t of lens and focal distance f satisfy following formula.
t＞(1+E)f
In the formula, E is the number more than 0, is advisable with 0, and 0.1 is better, and 0.2 is best.
Have under the situation of above-mentioned relation, improved the satisfaction of condition (4) and condition (5).
At first, increasing lessly about the aberration of the best image planes of each wavelength under the situation of wavelength error with condition (4), is because the big radius that can make lens the 1st (plane of incidence) of the center thickness of lens is bigger.In more detail: because if first radius-of-curvature increases, then the light of scioptics outboard end reduces to the incident angle θ (angle that the normal of lens face and light form) of lens, like this, the refraction effect of non-linear phenomenon reduces, its result, the increase of the spherical aberration under the situation of wavelength variations diminishes.
Fig. 7 is the relation of the center thickness and the residual aberration that wavelength error (5nm) is caused of lens.Residual aberration is a spherical aberration.This figure is that a plurality of NA of design are 0.85, and focal length is that the lens of 2.5mm are described.. glass material is the LAM70 of Ohara system.And, in lens design, adopted bigger eccentric tolerance.
As can be seen from Figure 7: if the thickness of lens the bigger aberration of 0.04 λ then occurs less than focal length.And, also as can be seen, thickness be 1.2 times 3mm of focal length when following aberration increase and become big.
Secondly, increase, having under the situation of wavelength spread about the aberration under the situation of the wavelength spread of have ready conditions (5), its the expansion in the situation of best image planes as inspection surface of centre wavelength under, at other wavelength, except that above-mentioned spherical aberration, also produce focus error.In fact, compare with spherical aberration, the influence of focus error is big, and especially under wavelength was situation below the 450nm (0.45 μ m), the dispersion of the refractive index of glass increased, so the influence of focus error is very big.
This focus error results from the variation of back focal length of the lens under the wavelength variations situation.The back focal length fb of lens can utilize according to paraxial approximate ray tracing formula and obtain.This is the relation of R1, t, n and following formula:
fb＝f(1-t(n-1)/n/R1)
According to the dispersion of glass, make the difference of the value of the fb under the situation that n changes become focus error.
It is 2mm that Fig. 8 is illustrated in focal length, and refractive index is in 1.75 the lens, and the variations in refractive index of glass is the variable quantity of the fb under 1.7486 the situation.The variable quantity of Fb is that axle is gone up aberration.And, this change of refractive, being equivalent to abbe number is about 45 the glass variations in refractive index when using the wavelength variations of the about 5nm under the situation in the wavelength about 400nm.Lens shape is a plano-convex lens, and R1 is 1.5mm.Reality lens be not plano-convex lens, but two-sided be sphere.Be aspheric surface more exactly.Paraxial all amounts of f, fb etc. are by the decision of the radius on summit, so no problem as spherical lens, still, the variation of fb consequently changes R1 and R2 with keeping focal length, the bending of lens are not had the situation of plano-convex lens of much influences very approaching.Judge according to Fig. 8, no problem.With reference to the accompanying drawings, aberration and lens thickness reduce pro rata on the axle, so, wish that lens thickness is thick as far as possible.
But in the format range of this instructions, the aberration that has off-centre to cause in complete aplanat increases to the 1st minimum radius surface.Wherein, above-mentioned aberration is being carried out under the situation of balance, not necessarily will adopt the radius of decectration aberration minimum, in being no more than the scope of conditional, can be the radius of approaching slightly different radius as the summit of aspherical shape, to aberration on the axle and the off-axis aberration weighing apparatus of making even.
So-called to the aberration weighing apparatus of making even, we can say to be meant design freedom that have only imperfection is introduced complete aplanat, itself also can increase degree of freedom the radius of lens, and averages out.
Certainly, surpassing under the situation that conditional changes, be difficult between the aberration and average out, so must observe conditional.
The variation of characteristic with numerical aperture more than has been described, its starting point is the variation of imaging multiplying power β, will be conceived to the light of maximum height of lens inside and angle u1 that optical axis the forms variation with numerical aperture in this further instruction.
At first, if numerical aperture changes, then u1 changes with numerical aperture substantially with being directly proportional.Change when narrating in addition and by β, identical reason makes it depart from the variation of direct ratio slightly.Say that exactly the variation of β is that the variation of u1 causes.
Consider this point, the interior angle when establishing NA and be beyond 0.85 is u1 '.U1 ' can be expressed from the next.
K＝(0.60866-0.11·t/f-0.1272·d/f)(0.83+0.2·NA)·NA/0.85
In the formula, f is a focal length, and t is the center thickness of dish, and d is the thickness of the transmission layer of CD, and NA is the numerical aperture of lens.
And, be under the situation of the lens more than 0.75 in numerical aperture, in order to design the lens that can fully guarantee eccentric tolerance, angle u1 ' considers internally, wishes in 0.06 scope, reaches 0.05 better, 0.04 is best.
If this relation is put in order, then can obtain following condition to interior angle u1 '.
(1-D)·K＜sin(u1′)＜(1+D)·K ……(8)
K＝(0.60866-0.11·t/f-0.1272·d/f)(0.83+0.2·NA)·NA/0.85
In the formula, D is a positive number, is preferably 0.06, more preferably 0.05, be preferably 0.04.
And the influence of the transmission layer of dish is smaller, and refractive index is in 1.45～1.65 the scope, not have big variation.
Above-mentioned 0.04～0.06 amplitude is the refractive index difference of this dish, strictly speaking, is that this numerical value comprises owing to the different very little differences that produce of the index of refraction in lens.
Moreover the refractive index of lens is low, and numerical aperture was less than 0.75 o'clock, and nargin increases, so can obtain roughly good value from this value by 6% with interior angle.
At this, the center thickness t and the focal distance f of lens satisfy following relational expression.
t＞(1+E)f
In the formula, E is the number more than 0, is preferably 0, more preferably 0.1, be preferably 0.2.
Above situation is concluded and to be got up to see, light and the angle u1 ' that optical axis forms to the maximum height of lens inside if satisfy condition 4, then can satisfy a last aberration characteristic, off-axis aberration characteristic and eccentric tolerance (the aberration increase that is caused) simultaneously.
Further supplementary notes are as follows.This non-spherical lens both can be to the rotational symmetric lens of optical axis (centered optical system), also can be the such shape of Tuo Aoyiku lens that aspherical shape is changed slightly according to direction.Self-evident, also must make the 1st radius-of-curvature and thickness of all directions meet above-mentioned scope under the latter's the situation.
Below expression relates to the embodiment of objective lens for optical disk of the present invention.
Represent aspheric surface with following polynomial expression in an embodiment.
Z＝CY
2/(1+(1-(1+K)C
2Y
2)0.5)+AR
4+BR
4+CR
8+DR
10+ER
12+FR
14
In the formula, Z is the distance from vertex of surface, and Y is the height from optical axis, and K is the constant of the cone, and A～F is the asphericity coefficient from 4 times to 14 times.For example, A is equivalent to the coefficient of 4 powers of Y.
＜the 1 embodiment 〉
Fig. 9 is the sectional drawing of the object lens of the 1st embodiment.The object lens of the 1st embodiment are called object lens 11
01
Be injected into object lens 11
01In light beam L reflect at the 1st 1 and the 2nd 2, see through the 3rd 3 and transmission layer of CD 21, by optically focused on signal recording surface.
The lens specification is as shown in table 1.
Table 1
| Design wavelength | 405nm |
| Numerical aperture | 0.85 |
| Focal length | 2mm |
| The entrance pupil diameter | 3.4mm |
| Disc thickness | 0.1mm |
| The | 0 |
Table 2
| The face sequence number | The face shape | Radius | Thickness | Refractive index | The constant of the |
| 1 | Aspheric surface | 1.71 | 2.75 | 1.85 | -0.9168291 |
| 2 | Aspheric surface | -75.9027 | 0.4605 | - | 2518.06 |
| 3 | - | Infinitely great | 0.1 | 1.62230752 | - |
| Image planes | - | - | - | - | - |
The 1st asphericity coefficient is as shown in table 3.
Table 3
| The coefficient of 4 powers of r | 0.013687371 |
| The coefficient of 6 powers of r | 0.00087533585 |
| The coefficient of 8 powers of r | 0.00087533585 |
| The coefficient of 10 powers of r | -0.00077467164 |
| The coefficient of 12 powers of r | 0.00030433925 |
| The coefficient of 14 powers of r | -5.3502493×10 -5 |
The 2nd asphericity coefficient is as shown in table 4.
Table 4
| The coefficient of 4 powers of r | 0.22363727 |
| The coefficient of 6 powers of r | -0.58889528 |
| The coefficient of 8 powers of r | 0.72567392 |
| The coefficient of 10 powers of r | -0.47382503 |
| The coefficient of 12 powers of r | 0.12985027 |
The recommendation of the R1 that calculates according to this lens specification, promptly the A value in the formula (7) is 1.731695.Deviating from of this recommendation and actual design value is 1.25%.
The characteristic of these lens satisfies condition (1) and (2) substantially, is the aplanat that condition (3) is kept a point tolerance.
At these lens 11
01In, the wavefront aberration on the axle is less, is 0.002 λ, can be described as aberrationless value in the practicality.The wavefront aberration characteristic of the incident ray of 0.5 degree outer with respect to axle is good, is 0.023.In addition, about the off-centre between the face important in manufacturing process, when off-centre was 3 μ m, the value of wavefront aberration is 0.036 λ, and was very good.
These lens 11
01The sine of angle of lens inside of high light line be sin (u1 ')=0.46.The recommendation of the sin that calculates according to this lens specification (u1 ') on the other hand, promptly the K in the formula (8) is 0.4511.This recommendation departs from actual design value 1.97%
Figure 10 is a longitudinal aberration diagram, and Figure 11 is the figure of the discontented capacity of expression sine condition.Figure 12 is astigmatism figure.
Figure 13 is that expression lens off-centre is the figure that aberration under the situation of 3 μ m increases situation.These lens are at the lens 11 of maintenance on one side with the 1st embodiment
01Identical refractive index and thickness, Yi Bian the 1st radius of curvature R 1 is only changed a bit design.
The increase of aberration represents that with white square numerical aperture is 0.75 situation; Use black box ◆ the expression numerical aperture is 0.85 situation.
The A value of the formula in each numerical aperture (7) is 1.767mm during numerical aperture 0.75; During numerical aperture 0.85 1.732mm.
According to Figure 13, as can be seen, if the limit of the aberration when eccentric is set at 0.04 λ, then the 1st radius of curvature R 1 be set at as the A value of recommendation at least 5% with interior relatively good, as if being set in 4%, then can be set at exactly below 0.04 λ.
Moreover, consider that if improve numerical aperture, then the aberration under the situation of R1 variation increases change greatly, so, be set at 3% with interior best.
But, be under 0.85 the situation in numerical aperture, aberration optimum and A deviation theory value about 1%.This is that the regression equation error causes, and above-mentioned scope is the value that it is taken into account.
And, under the situation of this lens specification, by the off-centre of 3 μ m, the aberration of 0.04 λ appears.Sometimes because the relation of specification also can only realize sizable value.Self-evident in this case, also be in order to reduce aberration, must to be controlled in the above-mentioned scope.
＜the 2 embodiment 〉
Figure 14 is the sectional drawing of the object lens of the 2nd embodiment.The object lens of the 2nd embodiment are called object lens 11
02
Be injected into object lens 11
02In light beam L on the 1st 1 and the 2nd 2, reflect, see through the 3rd 3 of CD 21 and transmission layer and on signal recording surface optically focused.
The lens specification is as shown in table 5.
Table 5
| Design wavelength | 405nm |
| Numerical aperture | 0.8 |
| Focal length | 1.750mm |
| The entrance pupil diameter | 2.8mm |
| The | 0 |
Table 6
| The face sequence number | The face shape | Radius | Thickness | Refractive index | The constant of the |
| 1 | Aspheric surface | 1.45 | 2.5 | 1.75 | -0.9753354 |
| 2 | Aspheric surface | 3.613636 | 0.395 | - | - |
| 3 | - | Infinitely great | 0.1 | 1.62230752 | -188.2991 |
| Image planes | - | - | - | - | - |
The 1st asphericity coefficient is as shown in table 7.
Table 7
| The coefficient of 4 powers of r | 0.023305393 |
| The coefficient of 6 powers of r | 0.017039056 |
| The coefficient of 8 powers of r | 0.0023431785 |
| The coefficient of 10 powers of r | -0.0023798936 |
| The coefficient of 12 powers of r | 0.0013373117 |
| The coefficient of 14 powers of r | -0.00035090993 |
The 2nd asphericity coefficient is as shown in table 8.
Table 8
| The coefficient of 4 powers of r | 0.17601287 |
| The coefficient of 6 powers of r | -0.54949768 |
| The coefficient of 8 powers of r | 0.50420582 |
| The coefficient of 10 powers of r | 0.12942116 |
| The coefficient of 12 powers of r | -0.37309714 |
According to the R1 recommendation that this lens specification calculates, promptly the A value of formula (7) is 1.4495mm.This recommendation departs from real design load 0.3%.This lens peculiarity is the aplanat of condition (3) slight surplus error of (1) and (2) of satisfying condition substantially.
Wavefront aberration on the axle is very little, is 0.001 λ, can be described as the practical aberrationless value that.With respect to the wavefront aberration of the incident ray of 0.5 degree outside the axle, characteristic is good, is 0.013 λ.In addition, about to eccentric between the very important face of manufacturing tolerance, the value 0.023 of wavefront aberration when eccentric 3 μ m, performance is fine.
These lens 11
02The sine of angle u1 ' of lens inside of high light line be sin (u1 ')=0.421.On the other hand, the recommendation of the sin that calculates according to this lens specification (u1 '), promptly the K in the formula (8) is 0.44.This recommendation departs from real design load 1.7%.
Figure 15 is a longitudinal aberration diagram, and Figure 16 is the figure of the discontented capacity of expression sine condition, and Figure 17 is astigmatism figure.
＜the 3 embodiment 〉
Figure 18 is the sectional drawing of the object lens of the 3rd embodiment, and the object lens of the 3rd embodiment are called object lens 11
03
Be injected into object lens 11
03Interior light beam L reflects at the 1st 1 and the 2nd 2, sees through the 3rd 3 and transmission layer of CD 21, optically focused on signal recording surface.
The lens specification is as shown in table 9.
Table 9
| Design wavelength | 405nm |
| Numerical aperture | 0.85 |
| Focal length | 2.2mm |
| The entrance pupil diameter | 3.74mm |
| Disc thickness | 0.1mm |
| The | 0 |
Table 10
| The face sequence number | The face shape | Radius | Thickness | Glass material | The constant of the |
| 1 | Aspheric surface | 1.812171 | 3.104 | NBF1 | - 0.3371789 |
| 2 | Aspheric surface | -6.507584 | 0.500289 | - | -845.6516 |
| 3 | - | Infinitely great | 0.1 | Polycarbonate | - |
| 4 | Image planes | - | - | - | - |
The 1st asphericity coefficient is as shown in table 11.
Table 11
| The coefficient of 4 powers of r | -0.00092006967 |
| The coefficient of 6 powers of r | -0.00025706693 |
| The coefficient of 8 powers of r | -0.00057872391 |
| The coefficient of 10 powers of r | 0.0002222827 |
| The coefficient of 12 powers of r | -5.6787923×10 -5 |
The 2nd asphericity coefficient is as shown in table 12.
Table 12
| The coefficient of 4 powers of r | 0.061448774 |
| The coefficient of 6 powers of r | -0.13995629 |
| The coefficient of 8 powers of r | 0.12867014 |
| The coefficient of 10 powers of r | -0.043733069 |
The refractive index of each glass material is as shown in table 13.
Table 13
| NBF1 | 1.76775590 |
| Polycarbonate | 1.62031432 |
According to the R1 recommendation that this lens specification calculates, promptly the A value of formula (7) is 1.81581mm.This recommendation departs from real design load 0.2%.This lens peculiarity satisfies condition (1) substantially, and still some does not satisfy condition 2, and therefore, comparing with the lens of the 1st embodiment is to have reduced the lens that the aberration when eccentric increases, and, be very near the aplanat that condition (3) is kept a point tolerance.
Wavefront aberration on the axle is 0.006 λ, and is very little, can be described as the practical aberrationless value that.The wavefront aberration of spending incident ray with respect to axle outer 0.5 is 0.069 λ, and characteristic is good.In addition, about eccentric between the very important face of manufacturing tolerance, the value 0.034 of wavefront aberration is good value when eccentric 5 μ m.
These lens 11
03The sine of angle u1 ' of lens inside of high light line be sin (u1 ')=0.466.On the other hand, and the sin that calculates according to this lens specification (u1 ') recommendation, promptly the K in the formula (8) is 0.464.This recommendation departs from real design load 0.43%.
Figure 19 is a longitudinal aberration diagram, and Figure 20 is the figure of the discontented capacity of expression sine condition, and Figure 21 is an astigmatism.
＜the 4 embodiment 〉
Figure 22 is the sectional drawing of the object lens of the 4th embodiment.The object lens of the 4th embodiment are called object lens 11
04
Be injected into object lens 11
04Interior light beam L is seen through the 3rd 3 and transmission layer of CD 21, optically focused on signal recording surface by the 1st 1 and the 2nd 2 refraction.
The lens specification is as shown in table 14.
Table 14
| Use wavelength | 405nm |
| Numerical aperture | 0.85 |
| Focal length | 0.88mm |
| The entrance pupil diameter | 1.496mm |
| Coil thick | 0.1mm |
| The | 0 |
The design load of lens is as shown in Table 15.
Table 15
| The face sequence number | The face shape | Radius | Thickness | Refractive index | The constant of the |
| 1 | Aspheric surface | 0.73 | 1.26 | 1.750 | -0.9974081 |
| 2 | Aspheric surface | -1.791429 | 0.173565 | 1 | -189.377 |
| 3 | - | Infinitely great | 0.1 | 1.62230752 | - |
| Image planes |
The 1st asphericity coefficient is shown in table 16.
Table 16
| The coefficient of 4 powers of r | 0.19868545 |
| The coefficient of 6 powers of r | -0.0061548457 |
| The coefficient of 8 powers of r | 0.80023321 |
| The coefficient of 10 powers of r | -2.8911336 |
| The coefficient of 12 powers of r | 5.5467879 |
| The coefficient of 14 powers of r | -4.4427687 |
The 2nd asphericity coefficient is shown in table 17.
Table 17
| The coefficient of 4 powers of r | 1.5351846 |
| The coefficient of 6 powers of r | -14.829258 |
| The coefficient of 8 powers of r | 33.428793 |
| The coefficient of 10 powers of r | 126.25085 |
| The coefficient of 12 powers of r | -558.31863 |
The R1 recommendation that calculates according to this lens specification, be that A value in the formula (7) is 0.734mm.The bias of this recommendation and real design load is 0.5%.
The characteristic of these lens can satisfy condition (1) and (2) basically, only condition (3) is still had error, is a kind of aplanat.
In these lens, the wavefront aberration on the axle is very little, is 0.002 λ, reality is used be we can say aberrationless.Wavefront aberration to the incident ray of 0.5 degree outside the axle is 0.008 λ.Characteristic is good.Have, about to eccentric between the very important face of manufacturing process, wavefront aberration is 0.037 λ when off-centre is 3 μ m, and is very good again.
The sine of the angle in the lens inside of the high light line of these lens is sin (u1 ')=0.45.On the other hand, the recommendation of the sin that calculates according to this lens specification (u1 '), be that K in the formula (6) is 0.4367.Bias between this recommendation and the real design load is 3.0%.
Figure 23 is a longitudinal aberration diagram, and Figure 24 is astigmatism figure, and Figure 25 represents that sine condition is discontented with capacity.
Moreover operating distance is 0.1735mm, and this is the best operating distance when adopting radius 25mm dish.Compare with 0.125mm, quite wide.
But, asphericity coefficient is changed slightly, eccentric tolerance is increased.In the case, can not avoid the deterioration of a last aberration or off-axis aberration.But manufacturing tolerance is very important concerning the lens that obtain fully big practicality.
In other words, by making a last aberration and the suitable deterioration of off-axis aberration,, find out equilibrium point design so that guarantee eccentric tolerance.Also can also be referred to as the satisfaction degree that meaning is pro-rata above-mentioned 3 conditions (1)～(3) to this operation.
And, when exploring aspherical shape like this, the angle (being designated hereinafter simply as incident angle) that the normal of the face at the 1st maximum light height place and optical axis form, if can not satisfy the defined terms formula, so, to cause eccentric tolerance, off-axis aberration or axle to go up off-axis aberration and increase, can not realize reaching between the aberration design of balance.Below describe this situation in detail.
The present inventor designs multiple lens, these lens are the aplanates of (1) and (2) of satisfying condition fully substantially, and improve satisfaction degree to condition (3) as far as possible, the refractive index of the focal length of lens, lens thickness, lens glass material has been carried out various variations and research.It found that: the light of maximum height has been arranged the relation of aberration when axle is gone up aberration, off-axis aberration and off-centre to the incident angle of the 1st on lens.And the design wavelength of lens is preferably below the 450nm, is specially 405nm.
Figure 26 is the figure of the geometric relationship in the expression lens.
Parallel the 1st 10 maximum height light L0 being injected into object lens 110 and the 1st 10 normal N on this light incidence point with optical axis and be formed into firing angle θ.20 is the 2nd.
Figure 27 is the figure of the light of expression maximum height to the relation of the 1st 10 incident angle and aberration characteristic.The A of Figure 27 is the off-axis aberration to 0.5 oblique incidence light, if the 1st 10 incident angle increases, then aberration increases.Among the figure, the refractive index of glass material is respectively: black rhombus ◆ be 1.55, and white rhombus ◇ is 1.65, and symbol △ is 1.75, and circlec method is 1.8, and white square is 1.85.
β among Figure 27 is that off-centre is aberration under the situation of 3 μ m between face.Among the figure, the refractive index of glass material is respectively: black box ■ is 1.55, pitch * be 1.65, the △ mark is 1.75, white square is 1.8, black rhombus ◆ be 1.85.
According to Figure 27, the increase of aberration be we can say with the increase of the 1st incident angle in linear relation substantially.But because the individual difference of designs such as lens design specification such as the focal length of lens, lens thickness, lens glass material refractive index and asphericity coefficient approximation method, above-mentioned straight line is variant slightly.Be substantially straight line with respect to the 1st incident angle.And when no matter aberration also can both well be proofreaied and correct on the axle, and aberration is below 0.006 λ.
This relation is general relation.That is to say that even the thickness of the refractive index of glass and lens is different, the perhaps therefore radius difference on the 1st the summit as long as above-mentioned angle equates, will form equal aberration characteristic.
At this, in order to obtain the good lens of eccentric tolerance and off-axis aberration, aberration when must be with 3 μ m eccentric is below 0.04 λ, is that lens shape below 0.03 λ is the basis with respect to the off-axis aberration of the oblique incidence of 0.5 degree, pro rata distributes above-mentioned condition (1)～(3) to design.
Here so-called pro-rata for example is meant as mentioned above, and in order to ensure eccentric tolerance, what sacrifice some off-axis aberration or axle is gone up aberration, and balance is carried out in condition (1)～(3).
As mentioned above, the lens of present embodiment are the aplanates of (1) and (2) of satisfying condition fully substantially, and aberration and off-axis aberration have obtained desirable correction substantially on the axle, but the aberration correction when eccentric is not too abundant, therefore carries out this pro-rata.
If according to this standard, then in numerical aperture was 0.85 lens, the light of maximum height must reduce to the 1st incident angle, 57 degree better, 56 degree are better, 55 degree are best.And it is very little that the change of shape of pro-rata is adopted in above-mentioned condition (1)～(3).
Be lower than in numerical aperture under 0.85 the situation, diminish with respect to the aberration increase of error, so same, if 57 degree better, 56 degree are better, the following best words of 55 degree, so, can provide very good lens, promptly to above-mentioned condition (1)～(3) good lens.
But under the situation of the lens that utilize mould to be shaped to make present embodiment, incident angle and Mould Machining difficulty have direct relation.So, wish that incident angle is as far as possible little.
Have, have in this molded lens by increase temperature the technological process that forms between mould and formed products, caused shaping is shunk, and makes the shape of formed products and mould produce small difference.So, be lower than in numerical aperture under 0.85 the situation, reducing incident angle according to numerical aperture has good result to manufacturing.
Therefore, during multiple lens design, find that then the 1st 10 incident angle θ is that 0.85 o'clock angle [alpha] has following relation basically with respect to numerical aperture if reduce numerical aperture in contrast. and α is the value of actual design gained.
θ=α-(0.85-NA)/0.15 * 7.1 (degree) ... (9)
In table 1 for example expression to the numerical aperture of lens and the relation of incident angle with following the 1st embodiment specification.Above-mentioned formula (9) is the regression equation that utilizes table 18 to calculate.
Table 18
| Numerical aperture | Angle (degree) |
| 0.60 | 39.8765 |
| 0.65 | 43.0969 |
| 0.70 | 46.2232 |
| 0.75 | 49.1485 |
| 0.80 | 51.6474 |
| 0.85 | 53.2516 |
Figure 28 represents the relation of numerical aperture and incident angle.α is 53.2516 degree.Among the figure, rhombus ◆ mark is represented the practical design value; Solid line is represented the value according to regression equation.
And, in Figure 28, expressed with lens thickness be 1.55mm, glass materials refractive index is other relevant routine data of lens of 1.75.Among the figure, black triangle ▲ mark represents that dotted line is represented the value according to the tropic to other routine actual design values.
The sort of situation no matter, all as can be seen, regression equation has reflected the practical design value well.And even other multiple lens design data have also obtained same result, above-mentioned regression equation (9) has very high precision as general expression.
In the formula, obtain the angle condition that the logarithm value aperture is lower than 0.85 situation.At first, if reduce numerical aperture, then the degree of tilt of the face of lens most peripheral (to the 1st incident angle) slows down natch.And therefore the restriction of above-mentioned condition (1)～(3) is also relaxed, so for example manufacturing tolerance is also relaxed.
Yet, be lower than in numerical aperture under 0.85 the situation, also with numerical aperture be 0.85 o'clock the same, when the 1st 10 incident angle increases, aberration characteristic degenerates, and has general characteristic.
So if the same according to 57 degree better less than the lens of 0.85 lens and numerical aperture 0.85 for numerical aperture, 56 degree are better, the following best condition of 55 degree designs, and so, can make good lens.Add the low above-mentioned advantage of bringing of numerical aperture, if the desired value that reduces to design according to the represented angle of regression equation so, can improve tolerance and performance.
So, be lower than in numerical aperture under 0.85 the situation, in by the scope that following conditional determined, set incident angle θ, can obtain better result thus to the 1st 10.
θ＜α-(0.85-NA)/0.15 * 7.1 (degree) ... (10)
In the formula, angle [alpha] is better with 57 degree, and 56 degree are better, and 55 degree are best.
But said lens is guaranteed eccentric tolerance, does not consider condition (4) and (5), so do not satisfy the adequate condition that can guarantee the aberration characteristic.Below describe the aberration characteristic in detail.
In the formula, the center thickness t and the focal distance f of lens satisfy following formula.
t＞(1+E)f
In the formula, E is the number more than 0, and 0 is better, and 0.1 is better, and 0.2 is best.
Have under the situation of above-mentioned relation, the satisfaction of condition (4) and condition (5) improves.
At first, increase lessly about the aberration of the best image planes of each wavelength under the situation of wavelength error with condition (4), this is because lens center thickness can make the radius of lens the 1st (plane of incidence) bigger when thicker.More detailed theory, if the 1st radius-of-curvature increases, then the light of scioptics outboard end reduces to the incident angle θ of lens (angle that the normal of lens face and light form), therefore, refraction effect as non-linear phenomena reduces, its result, the increase of the spherical aberration under the situation of wavelength variations diminishes.
From above-mentioned Fig. 7, as can be seen, as mentioned above,, then produce big aberration, reach more than 0.04 if lens thickness is thinner than focal length.And also as can be seen, thickness is below 1.2 times the 3mm of focal length, and it is big that the increase of aberration becomes.And, among Fig. 8, wish to increase lens thickness as far as possible.
In sum, if the incident angle of the 1st maximum light of lens and the thickness of lens satisfy these conditions, then can satisfy above-mentioned condition (1)～(3) simultaneously, aberration increase that promptly aberration characteristic, off-axis aberration characteristic, eccentric tolerance are caused on the axle and above-mentioned condition (4), (5), the i.e. little lens condition of surface aberration that wavelength error caused and aberration.
Further supplementary notes are as follows.This non-spherical lens both can be to the rotational symmetric lens of optical axis (centered optical system), also can be the toric lens shape that aspherical shape is changed a little according to the direction difference.In the latter case, self-evident, also must on each aspect that maximum height light is passed through, meet above-mentioned scope.
Below further expression relate to the embodiment of objective lens for optical disk of the present invention.
In an embodiment, represent aspheric surface with following polynomial expression.
Z＝CY
2/(1+(1-(1+K)C
2Y
2)0.5)+AR
4+BR
4+CR
8+DR
10+ER
12+FR
14
In the formula, X is the distance from the summit of face, and Y is the height from optical axis, and K is the constant of the cone, and A～F is the asphericity coefficient from 4 times to 14 times.For example A is equivalent to the coefficient of 4 powers of Y.
＜the 5 embodiment 〉
Figure 29 is the sectional drawing of the object lens of the 5th embodiment.The object lens of the 5th embodiment are called object lens 11
05
Be injected into object lens 11
05Light beam L reflect at the 1st 1 and the 2nd 2, see through the 3rd 3 and transmission layer of CD 21, optically focused on signal recording surface.
The lens specification is shown in table 19.
Table 19
| Design wavelength | 405nm |
| Numerical aperture | 0.85 |
| Focal length | 2mm |
| The entrance pupil diameter | 3.4mm |
| Disc thickness | 0.1mm |
| The | 0 |
Table 20
| The face sequence number | The face shape | Radius | Thickness | Refractive index | The constant of the |
| 1 | Aspheric surface | 1.71 | 2.75 | 1.85 | -0.9168291 |
| 2 | Aspheric surface | - 75.9027 | 0.4605 | - | 2518.06 |
| 3 | - | Infinitely great | 0.1 | 1.62230752 | - |
| Image planes | - | - | - | - | - |
The 1st asphericity coefficient is shown in table 21.
Table 21
| The coefficient of 4 powers of r | 0.013687371 |
| The coefficient of 6 powers of r | 0.00087533585 |
| The coefficient of 8 powers of r | 0.00087533585 |
| The coefficient of 10 powers of r | -0.00077467164 |
| The coefficient of 12 powers of r | 0.00030433925 |
| The coefficient of 14 powers of r | -5.3502493×10 -5 |
The 2nd asphericity coefficient is shown in table 22.
Table 22
| The coefficient of 4 powers of r | 0.22363727 |
| The coefficient of 6 powers of r | -0.58889528 |
| The coefficient of 8 powers of r | 0.72567392 |
| The coefficient of 10 powers of r | -0.47382503 |
| The coefficient of 12 powers of r | 0.12985027 |
These lens 11
05The angle of incidence of light of the 1st maximum height be 53.25 degree.These lens are the aplanates of (1) and (2) of satisfying condition substantially, and condition (3) is kept a point tolerance.
About wavefront aberration, the wavefront aberration on the axle is little, is 0.002, can be described as aberrationless value on reality is used.Wavefront aberration to the incident ray of 0.5 degree outside the axle is 0.023 λ, and characteristic is good.In addition, about to eccentric between the very important face of manufacturing tolerance, when off-centre was 3 μ m, the value of wavefront aberration is 0.036 μ m, and was fairly good.
Figure 30 is a longitudinal aberration diagram, and Figure 31 is the figure of the discontented capacity of expression sine condition, and Figure 32 is astigmatism figure.
＜the 6 embodiment 〉
Figure 33 is the sectional drawing of the object lens of the 6th embodiment.The object lens of the 6th embodiment are called object lens 11
06
Be injected into object lens 11
06Interior light beam L reflects at the 1st 1 and the 2nd 2, sees through the 3rd 3 and transmission layer of CD 21, optically focused on signal recording surface.
The lens specification is shown in table 23.
Table 23
| Design wavelength | 405nm |
| Numerical aperture | 0.8 |
| Focal length | 1.750mm |
| The entrance pupil diameter | 2.8mm |
| The | 0 |
Table 24
| The face sequence number | The face shape | Radius | Thickness | Refractive index | The constant of the |
| 1 | Aspheric surface | 1.45 | 2.5 | 1.75 | -0.9753354 |
| 2 | Aspheric surface | -3.613636 | 0.395 | - | - |
| 3 | - | Infinitely great | 0.1 | 1.62230752 | -188.2991 |
| Image planes | - | - | - | - | - |
The 1st asphericity coefficient is as shown in Table 25.
Table 25
| The coefficient of 4 powers of r | 0.023305393 |
| The coefficient of 6 powers of r | 0.017039056 |
| The coefficient of 8 powers of r | 0.0023431785 |
| The coefficient of 10 powers of r | -0.0023798936 |
| The coefficient of 12 powers of r | 0.0013373117 |
| The coefficient of 14 powers of r | -0.00035090993 |
The 2nd asphericity coefficient is shown in table 26.
Table 26
| The coefficient of 4 powers of r | 0.17601287 |
| The coefficient of 6 powers of r | -0.54949768 |
| The coefficient of 8 powers of r | 0.50420582 |
| The coefficient of 10 powers of r | 0.12942116 |
| The coefficient of 12 powers of r | -0.37309714 |
These lens 11
06The angle of incidence of light of the 1st maximum height be 51.41 degree.The formed angle of condition (9) with respect to numerical aperture 0.8 is 52.63 degree, so satisfy this condition.
These lens are the aplanates of (1) and (2) of satisfying condition substantially, and condition (3) is kept a point tolerance, and the wavefront aberration on the axle is very little, is 0.001 λ, we can say aberrationless in the reality use.
The off-axis aberration of incident angle 0.5 degree has the superperformance that wavefront aberration is 0.013 λ.And about eccentric between face very important in manufacturing tolerance, having wavefront aberration when off-centre is 3 μ m is the very good characteristic of 0.023 λ.
Figure 34 is a longitudinal aberration diagram, and Figure 35 is the figure of the discontented capacity of expression sine condition, and Figure 36 is astigmatism figure.
＜the 7 embodiment 〉
Figure 37 is the sectional drawing of the object lens of the 7th embodiment, and the object lens of the 7th embodiment are called object lens 11
07
Be injected into object lens 11
07Interior light beam L reflects at the 1st 1 and the 2nd 2, sees through the 3rd 3 and transmission layer of CD 21, optically focused on signal recording surface.
The lens specification is shown in table 27.
Table 27
| Design wavelength | 405nm |
| Numerical aperture | 0.85 |
| Focal length | 2.2mm |
| The entrance pupil diameter | 3.74mm |
| Disc thickness | 0.1mm |
| The | 0 |
Table 28
| The face sequence number | The face shape | Radius | Thickness | Glass material | The constant of the |
| 1 | Aspheric surface | 1.812171 | 3.104 | NBF1 | -0.3371789 |
| 2 | Aspheric surface | - 6.507584 | 0.500289 | - | -845.6516 |
| 3 | - | Infinitely great | 0.1 | Polycarbonate | - |
| 4 | Image planes | - | - | - | - |
The 1st asphericity coefficient is shown in table 29.
Table 29
| The coefficient of 4 powers of r | -0.00092006967 |
| The coefficient of 6 powers of r | -0.00025706693 |
| The coefficient of 8 powers of r | -0.00057872391 |
| The coefficient of 10 powers of r | 0.0002222827 |
| The coefficient of 12 powers of r | -5.6787923×10 -5 |
The 2nd asphericity coefficient is shown in table 30.
Table 30
| The coefficient of 4 powers of r | 0.061448774 |
| The coefficient of 6 powers of r | -0.13995629 |
| The coefficient of 8 powers of r | 0.12867014 |
| The coefficient of 10 powers of r | -0.043733069 |
The refractive index of each glass material is shown in table 31.
Table 31
| NBF1 | 1.76775590 |
| Polycarbonate | 1.62031432 |
These lens 11
07The incident angle of light of the 1st maximum height be 55.0 degree.
These lens 11
07Characteristic can satisfy condition basically (1), condition (2) is still more or less satisfied, therefore with the lens 11 of the 5th embodiment
05Compare, become the lens that the aberration when having suppressed eccentric increases.And, be seen as very near the aplanat that keeps a point tolerance from condition (3).
Wavefront aberration on the axle is 0.006 λ, and is very little, we can say aberrationless when reality is used.Wavefront aberration with respect to the incident ray of 0.5 degree outside the axle is 0.069 λ, and characteristic is good.Moreover, about eccentric between face very important in manufacturing tolerance, when being 5 μ m, off-centre has the wavefront aberration of 0.034 λ, and very good.
Figure 38 is a longitudinal aberration diagram, and Figure 39 is the figure of the discontented capacity of expression sine condition, and Figure 40 is astigmatism figure.
And, in the present embodiment the concrete numerical value of objective lens for optical disk utilization is illustrated.But the present invention is not limited only to these numerical value.The present invention can be applicable to the object lens that various CDs are used in the scope that does not break away from its main idea.
If specially enumerate the object lesson of numerical value, then in the present embodiment, CD, for example can adopt thickness range is the dish of the transmission layer of 0.01～0.3mm.And object lens for example can adopt the optical glass as NBF1, for example have the refractive index of 1.5～2.0 scopes.
And object lens of the present invention can be made with any manufacture method.Manufacture method has: glass is cut or the direct forming method of attrition process, the forming of glass method, adopt the forming of glass method of collosol and gel (sol-gel) method, and the method etc. that on the mother metal of the spherical lens shape of glass or plastics, forms aspherical layer with resin.
Below use the embodiment of Figure 41 Mingguang City sensing device.Optical sensing means 30 has: as blue look laser diode (LD) 31, beam splitter 32, object lens 33, light probe (PD) and the current-to-voltage converter (I-V) 34 of lasing light emitter.Example as beam splitter 32 can adopt polarizing beamsplitter.Object lens 33 are equivalent to each the object lens 11 of the foregoing description 1～7
01～11
07
Blue look LD31 for example sends the blue coloured light (laser) of about 405nm.Beam splitter 32 is isolated from blue look LD32 to the light of CD 35 and from the light of CD 35 to PD and I-V34.Object lens 33 adopt the object lens shown in the foregoing description.PD and I-V34 are transformed into electric current to incident light, again this electrorheological are changed into voltage, the line output of going forward side by side.
Optical sensing means 30 can be on CD 35 tracer signal (information).That is to say that blue look LD31 sends a kind of blue coloured light of using after being modulated by tracer signal that imported.This orchid coloured light accumulates on the CD 35 by beam splitter 32 and object lens 33.In CD 35, according to laser intensity recording information signal on signal recording surface from optical sensing means 30 irradiations.For example, on the surface of contact of CD 35 or groove, utilize the variation of pits or phase to come tracer signal.
Moreover optical sensing means 30 can be from replay signal on the CD 35.That is to say that the light of the prescribed strength that sends from blue look LD31 gathers on the signal recording surface of CD 35 by beam splitter 32 and object lens 33.Reflected light from CD 35 is input in PD and the I-V34 by object lens 33 and beam splitter 32, is transformed into voltage.Like this, export as voltage as the signal that writes down with the pits form on the surface of contact of the signal recording surface of CD 35 or the groove.
At this, object lens 33 preferably have following relation between the radius of its operating distance and the CD 35 that shone by the laser that penetrates from lasing light emitter:
Operating distance＞0.005 * CD radius.
Following with reference to Figure 42 the embodiment of Mingguang City dish device for reproducing recorded or disc reproducing apparatus.
Optical disc recording/reproduction device has: PRML (the partial response maximal phase seemingly) unit 50, controller unit 60, record compensating unit 70.And optical disc recording/reproduction device has above-mentioned optical sensing means.And this routine signal modulation system adopts 1-7RLL (run length limited code).
Like this, optical disc recording/reproduction device, to the decoding that the signal of reading from CD 35 usefulness optical sensing means 30 is stipulated, demodulation, output is reset with this., to the coding that the signal that is transfused to is stipulated, modulate, be written to by optical sensor 30 and carry out record in the CD 35.And can constitute the disc reproducing apparatus that the recording section that optical disc recording/reproduction device has is not set.
The effect of invention
As previously mentioned, if adopt the present invention, it is more than 0.75 that numerical aperture then can be provided, the object lens good, that adopt the signal-lens CD of double-sized non-spherical of the decectration aberration on the axle between aberration, off-axis aberration and face.
Claims (9)
1. objective lens for optical disk, its two sides are that aspheric, numerical aperture is the simple lens more than 0.75, and the angle that the 1st normal on the point of the light institute incident of maximum height and optical axis form is below 57 degree.
2. objective lens for optical disk, it is two-sided for aspheric, numerical aperture NA are the simple lens 0.75 or more, it is characterized in that: the angle θ of the 1st normal of the point of the light institute incident of maximum height and optical axis formation satisfies following formula
θ＜α-(0.85-NA)/0.15 * 7.1 (degree)
In the formula, α is 57 degree.
3. objective lens for optical disk as claimed in claim 1 or 2 is characterized in that: center thickness t and focal distance f satisfy following formula
t＞(1+E)f
Wherein E is the number greater than 0.
4. objective lens for optical disk as claimed in claim 1 or 2 is characterized in that the imaging multiplying power is 0.
5. objective lens for optical disk as claimed in claim 1 or 2 is characterized in that: from the light wavelength that is injected into the light source in the above-mentioned objective lens for optical disk is below the 450nm.
6. an optical sensing means is characterized in that having: claim 1 or 2 described objective lens for optical disk, LASER Light Source and light probe.
7. optical sensing means as claimed in claim 6 is characterized in that: above-mentioned objective lens for optical disk, and its operating distance and had following relation between the radius of the CD that is shone from above-mentioned LASER Light Source emitting laser:
Operating distance＞0.005 * CD radius.
8. optical disc recording/reproduction device is characterized in that having: the described optical sensing means of claim 6 and utilize above-mentioned optical sensing means to come record reproducing recording of information replay device on CD.
9. disc reproducing apparatus is characterized in that having: the described optical sensing means of claim 6 and utilize above-mentioned optical sensing means to reset to be recorded in the replay device of the information on the CD.
Applications Claiming Priority (7)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP289992/2001 | 2001-09-21 | ||
| JP290001/2001 | 2001-09-21 | ||
| JP2001289992 | 2001-09-21 | ||
| JP118318/2002 | 2002-04-19 | ||
| JP118489/2002 | 2002-04-19 | ||
| JP197996/2002 | 2002-07-05 | ||
| JP197990/2002 | 2002-07-05 |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN02142703A Division CN1410794A (en) | 2001-09-21 | 2002-09-18 | Objective lens for CD, optical sensing device, CD recording reproducing device and CD reproducing device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1749797A true CN1749797A (en) | 2006-03-22 |
Family
ID=36605340
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 200510096566 Pending CN1749797A (en) | 2001-09-21 | 2002-09-18 | Objective lens for optical disk, optical pickup device, optical disk recording/playing-back device and optical disk player |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1749797A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8089705B2 (en) | 2007-04-23 | 2012-01-03 | Hoya Corporation | Objective lens for optical pick-up |
| CN102411940A (en) * | 2006-11-08 | 2012-04-11 | 日立麦克赛尔株式会社 | Optical pickup lens |
-
2002
- 2002-09-18 CN CN 200510096566 patent/CN1749797A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102411940A (en) * | 2006-11-08 | 2012-04-11 | 日立麦克赛尔株式会社 | Optical pickup lens |
| CN101202068B (en) * | 2006-11-08 | 2013-07-03 | 日立麦克赛尔株式会社 | Optical pickup lens |
| CN102411940B (en) * | 2006-11-08 | 2014-11-12 | 日立麦克赛尔株式会社 | Optical pickup lens |
| US8089705B2 (en) | 2007-04-23 | 2012-01-03 | Hoya Corporation | Objective lens for optical pick-up |
| CN101295068B (en) * | 2007-04-23 | 2012-05-09 | Hoya株式会社 | Objective lens for optical pick-up |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN1185636C (en) | Optical pick-up, objective lens and device for reproducing and/or recording to optical record medium | |
| CN1286407A (en) | Object lens for optical pick-up and optical pick-up device | |
| CN1540646A (en) | Optical pick-up device, optical information recording and reproducing appts. extender lens, coupled lens and optical element for chromiatic aberration correction | |
| CN1259659C (en) | Optical system for recording regenerating, objective lens and optical pick device | |
| CN1707649A (en) | Optical pickup apparatus | |
| CN1410794A (en) | Objective lens for CD, optical sensing device, CD recording reproducing device and CD reproducing device | |
| CN1573402A (en) | Optical element, aberration correcting element, objective optical system, optical pickup device | |
| CN1351337A (en) | Object lens, focusing system, optical pickup device and recording/playing back device | |
| CN1678935A (en) | Object lens for optical pickup device, optical pickup device and optical information recording/reproducing device | |
| CN1922668A (en) | Optical pick-up, method of generating aberration for compensation and optical information processing apparatus using the same | |
| CN1896773A (en) | Optical disc drive and objective lens for the same | |
| CN1877716A (en) | Objective lens and optical information read/write device | |
| CN1296746C (en) | Objective lens, optical pickup device and information recording regeneration method | |
| CN1284159C (en) | Optical head device and optical information recording and reproducing device | |
| CN1655258A (en) | Optical pickup apparatus and diffractive optical element for optical pickup apparatus | |
| CN1685407A (en) | Optical element, objective optical element and optical pickup device | |
| CN1655256A (en) | Optical pick-up apparatus and optical information recording and/or reproducing apparatus | |
| CN1716404A (en) | Converging optical element and optical pickup apparatus | |
| CN1715985A (en) | Objective lens and optical pickup apparatus | |
| CN1571038A (en) | Objective lens for optical pickup device, optical pickup device, and optical information recording and reproducing device | |
| CN1603878A (en) | Optical pick-up system, optical pick-up device, and optical information recording and/or reproducing apparatus | |
| CN1244918C (en) | Optical pick-up device and its used objective | |
| CN1790508A (en) | Optical read device and objective | |
| CN1764959A (en) | Diffraction optical element, object optical system, optical pickup device and optical information recording/reproducing device | |
| CN1993749A (en) | Optical pickup apparatus and optical information recording and/or reproducing apparatus |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C02 | Deemed withdrawal of patent application after publication (patent law 2001) | ||
| WD01 | Invention patent application deemed withdrawn after publication |