【発明の詳細な説明】〔産業上の利用分野〕この発明は、光ディスク用レンズ、詳しくは半導体レー
ザーを光源とし、該半導体レーザーから放射された放射
光をコリメートレンズ系を介することなくそのまま対物
レンズに入射させることを可能とした光ディスク用レン
ズに関する。[Detailed Description of the Invention] [Field of Industrial Application] This invention uses an optical disk lens, specifically a semiconductor laser, as a light source, and directs the synchrotron radiation emitted from the semiconductor laser directly to an objective lens without passing through a collimating lens system. This invention relates to an optical disc lens that allows light to enter the optical disc.
光ディスク用レンズシステムとしては、レンズ系を通過
した半導体レーザーからのレーザー光が情報記録媒体た
るディスク上のピット面に収束し、その反射光が再びレ
ンズ系を通ってその戻り光の一部がビームスプリッタで
偏向されたのち、ディテクターに入り、金魚信号やトラ
ッキング信号が得られるように構成されているもの、あ
るいはディスクからの反射光を、レンズ及び平板を介し
て光源たる半導体レーザーに帰還させ、半導体レーザー
の出力光の変化をディテクターで検出するように構成さ
れたスクープ方式のものが知られている。In a lens system for optical discs, laser light from a semiconductor laser passes through a lens system and converges on the pit surface on the disc, which is an information recording medium.The reflected light passes through the lens system again, and a portion of the returned light becomes a beam. After being deflected by the splitter, the light enters the detector and is configured to obtain a goldfish signal or tracking signal, or the reflected light from the disk is returned to the semiconductor laser, which is the light source, via a lens and a flat plate. A scoop type device is known that is configured to use a detector to detect changes in laser output light.
光ディスク用レンズシステムは、その合焦やトラッキン
グ動作の際、半導体レーザー及び対物レンズが一体とな
って作動するので、制御信号に対する応動性をよくする
ために、光ディスク用レンズシステムの構成要素は、こ
れをできるだけ小型軽量化することが望ましい、また、
一般にこのシステムのレンズ系は光源からのレーザー光
をコリメートレンズで−たん平行光束にしたのち、この
平行光束を対物レンズでほぼ回折限界内に納まるように
収差補正が行われるので、このようなレンズ系では、一
般にコリメートレンズと対物レンズ、その他複数の調整
部品が必要であり、そのためシステムの性能劣化を起し
易く、またコスト高の要因となる。さらに、光ディスク
用レンズは、高密度に記録されたディスク上の信号を読
み取るのに少なくとも１μ程度の分解能を必要とし、そ
の上。In an optical disc lens system, the semiconductor laser and objective lens work together during focusing and tracking operations, so in order to improve responsiveness to control signals, the components of the optical disc lens system are It is desirable to make the
In general, the lens system of this system uses a collimating lens to convert the laser beam from the light source into a parallel beam, and then uses an objective lens to correct aberrations so that the parallel beam falls within the diffraction limit. The system generally requires a collimating lens, an objective lens, and a plurality of other adjustment parts, which tends to degrade the performance of the system and also causes high costs. Furthermore, lenses for optical discs require a resolution of at least about 1 μm in order to read signals on discs recorded at high density.
調整によるばらつきを考慮した必要な範囲の光学特性を
補正するために正弦条件の補正が重要となり、また、レ
ンズ系とディスクとの接触を防止するために作動距離を
長くすることが要求される。It is important to correct the sine condition in order to correct the optical characteristics within the necessary range considering variations due to adjustment, and it is also required to increase the working distance to prevent contact between the lens system and the disk.
これに加えて、第２図及び第３図を用いて後述するよう
に、半導体レーザーの放射光はその放射角のスライスレ
ベルを１／ｅ”で設定したとき、−殻内に、放射角は接
合面に垂直な方向には約３０゜前後、接合面に平行な方
向には約ｌＯ°前後の楕円状の発光放射パターンを持っ
たのとなる。このため、半導体レーザーからの放射光の
使用域を適切に規定する必要がある。In addition, as will be described later using FIGS. 2 and 3, when the radiation angle of the semiconductor laser is set at a slice level of 1/e", the radiation angle is within the -shell. It has an elliptical emission radiation pattern of about 30 degrees in the direction perpendicular to the bonding surface and about 10 degrees in the direction parallel to the bonding surface.For this reason, the use of synchrotron radiation from a semiconductor laser is difficult. It is necessary to define the area appropriately.
この発明は、コリメートレンズと対物レンズの作用を有
し、前記の諸間迎を解決した非球面レンズを提供するも
のである。The present invention provides an aspherical lens that has the functions of a collimating lens and an objective lens, and solves the above-mentioned problems.
この発明の光ディスク用レンズは、半導体レーザーと光
ディスクとの間に配置され、半導体レーザー側の面及び
ディスク側の面が共に正の屈折力を有する非球面からな
る光ディスク用レンズであり、上記非球面は、下式で示
す少なくとも入射高の１０乗に比例する項を含む非球面
であって、上記半導体レーザー側のＮＡを０．１２〜０
．２とし、ディスク側のＮＡが０．４以上になるように
構成され、下記の条件（１）〜（４）を満たすことを特
徴とする。The optical disc lens of the present invention is an optical disc lens that is disposed between a semiconductor laser and an optical disc, and is composed of an aspherical surface having both a semiconductor laser side surface and a disc side surface having positive refractive power, and wherein the aspherical surface is an aspherical surface including at least a term proportional to the 10th power of the incident height as shown in the following formula, and the NA on the semiconductor laser side is 0.12 to 0.
．． 2, is configured such that the NA on the disk side is 0.4 or more, and is characterized by satisfying the following conditions (1) to (4).
１．０（２） −１，０＜ Ｋ３ ＜０（４） Ｋ４＜ −１，０ただし、Ｘ ；光軸からＨの高さの点に於ける非球面頂点の接平
面からの距離Ｈ：光軸からの高さＣ：非球面の頂点の曲率（１／Ｒ）Ｋ ：円錐係数ｆ ：ディスク用レンズの焦点距離１、Ｏ：半導体レーザー発振面からのディスクのピット
面までの距離ｒ３：単レンズの光源側頂点近傍の曲率半径ｎ３：単レ
ンズの屈折率り、Ｅ、Ｆ、Ｇ ：各々の入射高に対する４乗、６乗、
８乗、１０乗に比例する項の係数第１図は、本発明の光ディスク用レンズを用いたレンズ
システムの一例を示しており、このシステムは半導体レ
ーザー１、ビームスプリッタ２、光ディスク用レンズ３
及びディテクター５で構成されている。尚、符号４はデ
ィスクのカバーガラスを示す、光源１からの光はビーム
スプリッタ２゜レンズ３及びカバーガラス４を通過して
ディスク上のピット面に収束し、その反射光の一部がビ
ームスプリッタ２で偏向されてディテクター５に入射す
る。1.0 (2) −1,0< K3 <0 (4) K4< −1,0 where, Height from the optical axis C: Curvature of the apex of the aspherical surface (1/R) K: Conic coefficient f: Focal length of the disk lens 1, O: Distance from the semiconductor laser oscillation surface to the pit surface of the disk r3: Radius of curvature n3 near the light source side vertex of the single lens: refractive index of the single lens, E, F, G: 4th power, 6th power of each incident height,
Coefficients of terms proportional to the 8th power and the 10th power FIG. 1 shows an example of a lens system using the optical disc lens of the present invention, and this system includes a semiconductor laser 1, a beam splitter 2, and an optical disc lens 3.
and a detector 5. The reference numeral 4 indicates a cover glass of the disk. Light from the light source 1 passes through the beam splitter 2, the lens 3, and the cover glass 4, and converges on the pit surface on the disk, and a part of the reflected light passes through the beam splitter. 2 and enters the detector 5.
半導体レーザーの発光放射パターンとエネルギーの強度
分布を２次元的に表示した第２図及び半導体レーザーの
発光放射パターンのうち、発光軸上のＮＡ＝０．１５に
対応するエネルギー強度分布の３次元図である第３図か
ら推察できるように、半導体レーザーの発光放射パター
ンからエネルギー分布に歪を生せしめることなく最大の
効率を得るためには、半導体レーザー側のＮＡは０．１
２〜０．２に設定することが好ましく、本発明における
半導体レーザー側のＮＡは理想的数値である０、１５程
度になるように構成される。Figure 2 is a two-dimensional representation of the emission radiation pattern and energy intensity distribution of the semiconductor laser, and a three-dimensional diagram of the energy intensity distribution corresponding to NA=0.15 on the emission axis of the emission radiation pattern of the semiconductor laser. As can be inferred from Figure 3, in order to obtain the maximum efficiency without causing distortion in the energy distribution from the emission radiation pattern of the semiconductor laser, the NA on the semiconductor laser side should be 0.1.
It is preferable to set it to 2 to 0.2, and the NA on the semiconductor laser side in the present invention is configured to be about 0.15, which is an ideal value.
ところで、従来この種の光学系は、−殻内に、コリメー
トレンズ系、対物レンズ系で夫々独自の補正が行われて
おり、従って、対物レンズに入射する光束の条件は１通
常工、０＝ψであるため無収差光として扱われていた。By the way, conventionally, in this type of optical system, unique corrections are performed in the collimating lens system and the objective lens system, respectively, within the shell. Therefore, the conditions for the light flux incident on the objective lens are 1 normal working, 0 = Since it is ψ, it was treated as aberration-free light.
これに対し、第１図に示すように光学系を構成した場合
には、本発明の対物レンズでは、１．Ｏが０．１＜ （
ｆ ／１．０）＜０．２５程度の有限であり、同時にビ
ームスプリッタ若しくは透明平板が介在するために、入
射光束に予め収差が存在する。したがって、後述の実施
例ではこの収差を含めた収差補正を行っている。尚、前
記条件（１）は、特に装置の大きさと正弦条件の補正を
示すものであり、また作動距離ＷＤを大きく保つための
条件でもある。On the other hand, when the optical system is configured as shown in FIG. 1, the objective lens of the present invention has 1. O is 0.1< (
f /1.0)<0.25, and at the same time, since a beam splitter or a transparent flat plate is present, an aberration already exists in the incident light beam. Therefore, in the embodiments described later, aberration correction including this aberration is performed. Note that the above-mentioned condition (1) particularly indicates the correction of the size of the device and the sine condition, and is also a condition for keeping the working distance WD large.
以下、前記の各条件（１）〜（４）について説明する。Each of the above conditions (1) to (4) will be explained below.
（１） ０．１＜ （ｆ／１．０）（０，２５この条件
のうち、ｆ／１．０が下限０．１をこえると装置が大型
化してしまい、所期の目的を達成できなくなる。また、
上限０．２５をこえると必要な良像範囲で正弦条件の補
正が困難となる。(1) 0.1< (f/1.0) (0,25 Among these conditions, if f/1.0 exceeds the lower limit of 0.1, the device will become larger and the intended purpose cannot be achieved. It will disappear. Also,
If the upper limit of 0.25 is exceeded, it becomes difficult to correct the sine condition within the necessary good image range.
（２）−１＜Ｋ３＜０この条件は対物レンズの光ｇａの非球面の形状を規定す
るもので、Ｋ３が上限０をこえると必要な範囲での正弦
条件の補正が困難となり、下限−１をこえると球面収差
が増大して中心部の補正が困難となる。(2) -1<K3<0 This condition defines the shape of the aspheric surface of the light ga of the objective lens, and if K3 exceeds the upper limit of 0, it will be difficult to correct the sine condition within the necessary range, and the lower limit - When the value exceeds 1, spherical aberration increases and correction at the center becomes difficult.
この条件はレンズ形状と対物レンズの光源側の非球面に
かかるパワーを規定するものであり、（ｎ３−１ ）□ ・ｆが上限１．０をこえると球面収差と軸外収差のバランス
が取れなくなり、また非点収差も増大する。下限０．５
をこえると、球面収差の補正が困難となる。This condition defines the lens shape and the power applied to the aspheric surface on the light source side of the objective lens, and when (n3-1) □ ・f exceeds the upper limit of 1.0, the spherical aberration and off-axis aberration are balanced. In addition, astigmatism also increases. Lower limit 0.5
If it exceeds , it becomes difficult to correct spherical aberration.
（４） Ｋ４＜−１，０この条件は対物レンズのディスク側非球面の形状を規定
し、また残存収差のバランスに関するものである。この
条件を外れると正弦条件が増大し、軸外のコマ収差が大
きくなり、球面収差とのバランスが取れなくなる。(4) K4<-1,0 This condition defines the shape of the disk-side aspheric surface of the objective lens and also relates to the balance of residual aberrations. If this condition is exceeded, the sine condition increases, the off-axis coma aberration increases, and it becomes impossible to balance it with the spherical aberration.
焦点距離ｆ ＝４．０ｍｍ作動距離＝３，０１１１１１１ディスク側のＮＡ＝０．４５゜ｆ ／１．０＝０．１６５６ 。Focal length f = 4.0mmWorking distance = 3,0111111Disc side NA = 0.45°f / 1.0 = 0.1656.
Ｋ３＝−８，５８５３８６６Ｘ１０−”Ｄ３＝−８，３
３２７８５７Ｘ１０″″４Ｅ３＝−６，９４４８７２３
Ｘ１０”−’Ｆ３＝−９．７０６９５１１Ｘ１０−”Ｇ
３＝−１，４４５０９０８Ｘ１０−’〔発明の効果〕１．０＝２４．１５ｍｍ使用波長＝ ７８０ｎｒｎレーザー側のＮＡ＝０．１５［（ｎ３−１）／ｒ３］・ｆ＝０．６９６８に４ニー６
．２１１００７５Ｄ４＝−３，１０１４６８８Ｘ１０−’Ｅ４＝−１．９
０６１６７１Ｘ１０”−’Ｆ４＝−４．４７４７１６７
Ｘ１０″″７Ｇ４冨５，３６１００９０ｘ１０”−８こ
の発明によれば、光ディスク用レンズシステムを、その
性能劣下を招くことなく小型軽量化することができ、従
来の諸問題点を解消することができる。また、半導体レ
ーザーの発光放射パターンからエネルギー分布に歪を生
ぜしめることなく最大の効率を得ることができる。K3=-8,5853866X10-"D3=-8,3
327857X10″″4E3=-6,9448723
X10"-'F3=-9.7069511X10-"G
3=-1,4450908X10-' [Effect of the invention] 1.0=24.15mm Used wavelength=780nrn NA on the laser side=0.15 [(n3-1)/r3]・4 knees to f=0.6968 6
．． 2110075 D4=-3, 1014688X10-'E4=-1.9
061671X10"-'F4=-4.4747167
X10''''7G4 depth 5,3610090x10''-8 According to the present invention, it is possible to reduce the size and weight of an optical disc lens system without deteriorating its performance, and it is possible to solve the conventional problems. Also, maximum efficiency can be obtained from the emission radiation pattern of the semiconductor laser without causing any distortion in the energy distribution.
第１図は本発明のレンズを用いた光ディスク用レンズシ
ステムの一例を示す断面図、第２図は半導体レーザーの
発光放射パターンとエネルギーの強度分布を２次元的に
表示した強度分布図、第３図は半導体レーザーの発光放
射パターンのうち、発光軸上のＮＡ＝０．１５に対応す
るエネルギー強度分布の３次元図、第４図は実施例の収
差曲線図である。１・・・・半導体レーザー、２・・・・ビームスプリッ
タ−１３・・・・非球面レンズ、ｒ３・・・・非球面レ
ンズの光源側非球面、ｒ４・・・・非球面レンズのディ
スク最Ｊ■Ｚ口FIG. 1 is a cross-sectional view showing an example of an optical disc lens system using the lens of the present invention, FIG. 2 is an intensity distribution diagram two-dimensionally displaying the emission radiation pattern and energy intensity distribution of a semiconductor laser, and FIG. The figure is a three-dimensional diagram of the energy intensity distribution corresponding to NA=0.15 on the emission axis among the emission radiation patterns of the semiconductor laser, and FIG. 4 is an aberration curve diagram of the example. 1... Semiconductor laser, 2... Beam splitter 13... Aspherical lens, r3... Aspherical surface on the light source side of the aspherical lens, r4... Disc top of the aspherical lens. J ■Z mouth
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1112514AJPH02118508A (en) | 1989-05-01 | 1989-05-01 | Lens for optical disk |
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1112514AJPH02118508A (en) | 1989-05-01 | 1989-05-01 | Lens for optical disk |
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP24028084ADivisionJPS61118708A (en) | 1984-11-14 | 1984-11-14 | Lens for optical disk |
| Publication Number | Publication Date |
|---|---|
| JPH02118508Atrue JPH02118508A (en) | 1990-05-02 |
| JPH0429048B2 JPH0429048B2 (en) | 1992-05-15 |
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1112514AGrantedJPH02118508A (en) | 1989-05-01 | 1989-05-01 | Lens for optical disk |
| Country | Link |
|---|---|
| JP (1) | JPH02118508A (en) |
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6639889B1 (en) | 1997-02-13 | 2003-10-28 | Samsung Electronics Co., Ltd. | Recording/reproducing apparatus including an optical pickup having an objective lens compatible with a plurality of optical disk formats |
| US6788636B2 (en) | 1997-03-28 | 2004-09-07 | Samsung Electronics Co., Ltd. | Optical pickup compatible with a digital versatile disk and a recordable compact disk using a holographic ring lens |
| US6791933B1 (en) | 1996-08-29 | 2004-09-14 | Samsung Electronics Co., Ltd. | Optical pickup using an optical phase plate |
| US6882614B2 (en) | 1996-02-14 | 2005-04-19 | Samsung Electronics Co., Ltd. | Recording/reproducing apparatus having an optical pickup device to read from and record information to disks of different thicknesses |
| US7372794B2 (en) | 2002-06-05 | 2008-05-13 | Samsung Electronics Co., Ltd. | Compatible optical pickup applying tilt to objective lens in proportion to radial movement of objective lens |
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| US6882614B2 (en) | 1996-02-14 | 2005-04-19 | Samsung Electronics Co., Ltd. | Recording/reproducing apparatus having an optical pickup device to read from and record information to disks of different thicknesses |
| US8503272B2 (en) | 1996-02-14 | 2013-08-06 | Samsung Electronics Co., Ltd. | Recording/reproducing apparatus having an optical pickup device to read from and record information to disks of different thicknesses |
| US8848502B2 (en) | 1996-02-14 | 2014-09-30 | Samsung Electronics Co., Ltd. | Recording/reproducing apparatus having an optical pickup device to read from and record information to disks of different thicknesses |
| US6791933B1 (en) | 1996-08-29 | 2004-09-14 | Samsung Electronics Co., Ltd. | Optical pickup using an optical phase plate |
| US7072114B2 (en) | 1996-08-29 | 2006-07-04 | Samsung Electronics Co., Ltd. | Optical pickup using an optical phase plate and which is compatible with optical recording media of different types |
| US6639889B1 (en) | 1997-02-13 | 2003-10-28 | Samsung Electronics Co., Ltd. | Recording/reproducing apparatus including an optical pickup having an objective lens compatible with a plurality of optical disk formats |
| US6788636B2 (en) | 1997-03-28 | 2004-09-07 | Samsung Electronics Co., Ltd. | Optical pickup compatible with a digital versatile disk and a recordable compact disk using a holographic ring lens |
| US6816449B2 (en) | 1997-03-28 | 2004-11-09 | Samsung Electronic Co., Ltd. | Optical pickup compatible with a digital versatile disk and a recordable compact disk using a holographic ring lens |
| US7046611B2 (en) | 1997-03-28 | 2006-05-16 | Samsung Electronics Co., Ltd. | Optical pickup compatible with a digital versatile disk and a recordable compact disk using a holographic ring lens |
| USRE43106E1 (en) | 1997-03-28 | 2012-01-17 | Samsung Electronics Co., Ltd. | Optical pickup compatible with a digital versatile disk and a recordable compact disk using a holographic ring lens |
| US7372794B2 (en) | 2002-06-05 | 2008-05-13 | Samsung Electronics Co., Ltd. | Compatible optical pickup applying tilt to objective lens in proportion to radial movement of objective lens |
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| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |