JP2001084632A - Optical pickup device, wavelength selective optical element and objective lens - Google Patents
Optical pickup device, wavelength selective optical element and objective lensInfo
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- JP2001084632A JP2001084632A JP25989699A JP25989699A JP2001084632A JP 2001084632 A JP2001084632 A JP 2001084632A JP 25989699 A JP25989699 A JP 25989699A JP 25989699 A JP25989699 A JP 25989699A JP 2001084632 A JP2001084632 A JP 2001084632A
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- light
- light beam
- wavelength
- optical
- recording
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は厚みの異なる透明基板を
有する複数の光情報記録媒体の記録情報を記録再生する
ための光ピックアップ装置、そのための波長選択性光学
素子および対物レンズに関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup device for recording and reproducing information recorded on a plurality of optical information recording media having transparent substrates having different thicknesses, a wavelength-selective optical element and an objective lens therefor.
【０００２】[0002]
【従来の技術】近年、従来の光情報記録媒体であるＣＤ
と同程度の大きさで、記録再生が可能なＣＤ−Ｒや、記
録密度を高めたＤＶＤなど、記録面の透明基板の厚みや
記録再生用レーザ光の波長の異なる複数の光情報記録媒
体の開発が進み、これらの光情報記録媒体に対して、同
一の光ピックアップでの記録再生を可能とすることが求
められている。このため、使用波長に応じた複数のレー
ザ光源を備えながら、同一の対物レンズで記録面へ必要
な開口数でレーザ光を収束する光ピックアップが、各種
提案されている（例えば特開平８−５５３６３号公報、
同平１０−９２０１０など）。しかし、このため光学系
の構成が複雑となり、これにつれて使用部品点数が増加
するという問題があった。2. Description of the Related Art In recent years, a conventional optical information recording medium, CD
A plurality of optical information recording media having different thicknesses of a transparent substrate on a recording surface and a wavelength of a recording / reproducing laser beam, such as a CD-R capable of recording / reproducing and a DVD having a higher recording density, having the same size as that of the optical disc. As the development progresses, it is required that these optical information recording media can be recorded and reproduced by the same optical pickup. For this reason, various types of optical pickups have been proposed in which a plurality of laser light sources corresponding to the wavelengths used are provided, and the same objective lens converges the laser light on the recording surface with a necessary numerical aperture (for example, Japanese Patent Application Laid-Open No. 8-55363). No.
10-922010). However, for this reason, the configuration of the optical system becomes complicated, and the number of parts used increases accordingly.
【０００３】本発明者等は先に、同心円状に分割された
複数の輪帯からなり、各輪帯は、波長の異なる複数の光
源、及び／または、記録面の厚みの異なる透明基板に対
してほぼ回折限界に収差補正され、構成が簡素化された
光ピックアップを構成できる対物レンズを提案した（特
願平９−２８６９５４号）。この対物レンズは、使用波
長及び／または透明基板の厚みに応じて自動的に必要な
開口を得られるという機能を有している（以下、特殊対
物レンズという。）。しかし、レーザ光源と光検出器が
一体となったレーザ／検出器集積ユニットを使用した場
合、光検出器に入射するフレア光により、正確な検出が
出来ない場合が生じるという問題があった。これは特
に、ホログラムを利用して光束を偏向し光検出器に導く
方式のレーザ／検出器集積ユニットにおいて顕著であ
る。The present inventors have previously made up a plurality of concentrically divided annular zones, each of which has a plurality of light sources having different wavelengths and / or a transparent substrate having a different recording surface thickness. Thus, an objective lens capable of constructing an optical pickup whose aberration has been substantially corrected to the diffraction limit and whose configuration has been simplified has been proposed (Japanese Patent Application No. 9-286954). This objective lens has a function of automatically obtaining a necessary aperture according to the wavelength used and / or the thickness of the transparent substrate (hereinafter, referred to as a special objective lens). However, when a laser / detector integrated unit in which a laser light source and a photodetector are integrated is used, there is a problem that accurate detection cannot be performed due to flare light incident on the photodetector. This is particularly remarkable in a laser / detector integrated unit that uses a hologram to deflect a light beam and guide it to a photodetector.
【０００４】これに対し、レーザ光源、光源からのレー
ザビームを記録面に収束する対物レンズを含む１つの集
光光学系、および記録面からの反射光を検出する受光素
子からなり、透明基板の厚みが異なる少なくとも２種の
光情報記録媒体の記録再生用光ピックアップのための光
学系において、該光学系は、集光光学系の光束が光軸近
傍から外側に向かって輪帯状に３つの光束に分割される
手段を含み、光軸近傍から外側に向かって順次第１、第
２、第３光束としたとき、第１光束は全ての透明基板の
厚みの異なる記録媒体用であり、第２光束は主に厚い透
明基板を有する記録媒体用、第３光束は主に薄い透明基
板を有する記録媒体用であり、かつ、上記受光素子へ入
射するフレアを除去するための開口制限手段を設けるこ
とを提案した（特願平１０−１６９１６２号）。これ
は、レーザ光の収束点に形成されるサイドロープが光検
出器に入射するとフレアとなって、フオーカシング、ト
ラッキング時に光検出器の出力に変動を与え、さらに記
録面から外れた場所に副次的な収束点を形成するように
働き問題を生じていたため、よりサイドロープの大きい
ＣＤについてのフレア除去を行うことにより、特殊対物
レンズによる不使用光のフレアを効果的に除去し、構成
を複雑化することなく、低コストで、精度の高い制御を
可能にすることが出来たものである。On the other hand, a transparent light source comprising a laser light source, one condensing optical system including an objective lens for converging a laser beam from the light source on a recording surface, and a light receiving element for detecting reflected light from the recording surface. In an optical system for recording / reproducing optical pickups of at least two types of optical information recording media having different thicknesses, the optical system includes three light beams in a concentric manner from the vicinity of the optical axis to the outside. When the first, second, and third light fluxes are sequentially formed from the vicinity of the optical axis to the outside, the first light flux is used for recording media having different thicknesses on all transparent substrates, and The luminous flux is mainly for a recording medium having a thick transparent substrate, and the third luminous flux is mainly for a recording medium having a thin transparent substrate, and an aperture limiting means for removing a flare incident on the light receiving element is provided. (Special No. flat 10-169162). This is because when the side rope formed at the convergence point of the laser beam enters the photodetector, it becomes a flare, fluctuates the output of the photodetector during focusing and tracking, and further produces a secondary light at a position off the recording surface. Convergence point was formed, and a problem was caused. By removing the flare of the CD with a larger side lobe, the flare of the unused light by the special objective lens was effectively removed, and the configuration was complicated. Thus, high-precision control can be performed at a low cost without the need for conversion.
【０００５】[0005]
【発明が解決しようとする課題】ところが、近年、ＤＶ
Ｄに関しても、赤色レーザ光源と光検出器とを一体化し
たレーザ／検出器集積ユニットが普及し、さらにＤＶＤ
ドライブの高倍速化が進められる中、ＤＶＤのサイドロ
ーブによる光検出器上のフレアによる問題が生じてき
た。ＤＶＤでは１ビーム法の１つであるＤＰＤ法でトラ
ッキング誤差信号を検出する場合は問題にならなかった
が、３ビーム法を行うドライブにおいて、中心のビーム
のフレアが両サイドのディテクターに入射し、トラッキ
ング方向にレンズがティルトした場合、両サイドのディ
テクターの光量にアンバランスを起こしトラツキング信
号にオフセットを生じたり、また逆に補助ビームのフレ
アが中心のディテクターに入射し、クロストークを起こ
すといった問題が生じている。すなわち、ＤＶＤの記録
再生において、情報記録面に複数のビームによるスポッ
トがある間隔で隣接している場合、上記問題を生じる可
能性がある。尚、ＤＶＤの場合、合焦時には、デイテク
ター上でフレアは中心スポットの回りにある間隔を隔て
て輪帯状に分布している。焦点検出を非点収差で行う場
合は、この輪帯は楕円状である。フレア部分が複数のデ
ィテクターの間に来るようにディテクター間隔を設定す
れば、合焦時に発生する問題は改善されるが、記録面か
ら外れた場所に生じる副次的な収束点はディテクターに
入射するため、この問題は解決されない。本発明は、こ
のような問題を解決するための光ピックアップ装置、そ
の光ピックアップ装置に用いるための光学素子および対
物レンズを提案しようとするものである。However, in recent years, DV
As for D, a laser / detector integrated unit integrating a red laser light source and a photodetector has become widespread.
As the drive speed has been increased, a problem has arisen due to flare on the photodetector due to the side lobe of the DVD. In the case of DVD, when the tracking error signal was detected by the DPD method, which is one of the one-beam methods, there was no problem. However, in the drive using the three-beam method, the flare of the center beam was incident on the detectors on both sides. If the lens tilts in the tracking direction, the light quantity of the detectors on both sides will be unbalanced, causing an offset in the tracking signal, and conversely, the flare of the auxiliary beam will be incident on the central detector, causing crosstalk. Has occurred. That is, in the recording / reproducing of a DVD, the above-described problem may occur when a spot formed by a plurality of beams is adjacent to an information recording surface at a certain interval. In the case of a DVD, flares are distributed in a ring shape on the detector at an interval around the center spot at the time of focusing. When focus detection is performed with astigmatism, the orbicular zone is elliptical. If the detector spacing is set so that the flare portion is between multiple detectors, the problem that occurs during focusing will be improved, but the secondary convergence point that occurs off the recording surface will be incident on the detector Therefore, this problem is not solved. An object of the present invention is to propose an optical pickup device for solving such a problem, an optical element and an objective lens used for the optical pickup device.
【０００６】[0006]
【課題を解決するための手段】本発明の光ピックアップ
装置は、レーザ光源、光源からのレーザビームを記録面
に収束する対物レンズを含む１つの集光光学系、および
記録面からの反射光を検出する受光素子からなり、透明
基板の厚みが異なる少なくとも２種の光情報記録媒体の
記録再生用光ピックアップ装置のための光学系におい
て、該光学系は、集光光学系の光束が光軸近傍から外側
に向かって輪帯状に３つの光束に分割される手段を含
み、光軸近傍から外側に向かって順次第１、第２、第３
光束としたとき、第１光束はすべての透明基板の厚みの
異なる記録媒体用であり、第２光束は主に厚い透明基板
を有する記録媒体用、第３光束は主に薄い透明基板を有
する記録媒体用であり、薄い透明基板を有する記録媒体
の記録または再生時には記録面からの第２光束の反射光
が上記受光素子へ入射しないような光束制限を行い、厚
い透明基板を有する記録媒体の記録または再生時には記
録面からの第３光束の反射光が上記受光素子へ入射しな
いような光束制限を行ったことを特徴とする。しかし、
コスト面などの制約により、厚い透明基板を有する記録
媒体の記録または再生の精度をある程度まで犠牲にする
ことが許容される場合には、後者の光束制限を省略する
ことが出来る。An optical pickup device according to the present invention comprises a laser light source, one condensing optical system including an objective lens for converging a laser beam from the light source on a recording surface, and a device for reflecting reflected light from the recording surface. An optical system for an optical pickup device for recording / reproducing at least two types of optical information recording media, comprising a light receiving element to be detected and having different thicknesses of a transparent substrate, wherein the light flux of the condensing optical system is close to the optical axis. From the vicinity of the optical axis to the outside in the order of the first, second, and third
When the light flux is used, the first light flux is for a recording medium having a thickness of all transparent substrates different from each other, the second light flux is mainly for a recording medium having a thick transparent substrate, and the third light flux is mainly for a recording medium having a thin transparent substrate. When recording or reproducing data on a recording medium having a thin transparent substrate, the light beam is restricted so that the reflected light of the second light beam from the recording surface does not enter the light receiving element, and recording on a recording medium having a thick transparent substrate is performed. Alternatively, the light beam is restricted so that the reflected light of the third light beam from the recording surface does not enter the light receiving element during reproduction. But,
When it is permitted to sacrifice the recording or reproducing accuracy of a recording medium having a thick transparent substrate to a certain extent due to cost restrictions or the like, the latter restriction of the luminous flux can be omitted.
【０００７】二つの波長の異なるレーザ光源と、光源か
らのレーザビームを記録面に収束する対物レンズを含む
１つの集光光学系、および記録面からの反射光を検出す
る受光素子からなり、透明基板の厚みが異なる少なくと
も２種の光情報記録媒体の記録再生用光ピックアップの
ための光学系において、第１の波長の第１レーザ光源
は、薄い透明基板の光情報記録媒体の記録再生用であ
り、第２の波長の第２レーザ光源は、厚い透明基板の光
情報記録媒体の記録再生用であり、上記光学系は、集光
光学系の光束が光軸近傍から外側に向かって輪帯状に３
つの光束に分割される手段を含み（このような手段が対
物レンズに組み込まれているとき、このような対物レン
ズを、以下、特殊対物レンズという。）、光軸近傍から
外側に向かって順次第１、第２、第３光束としたとき、
第１光束はすべての透明基板の厚みの異なる記録媒体用
であり、第２光束は主に厚い透明基板を有する記録媒体
用、第３光束は主に薄い透明基板を有する記録媒体用で
あり、二つの光源からの光束が共通して通る部分に、薄
い透明基板を有する記録媒体の記録または再生時には第
２光束が第１光束および第３光束が集光する記録面上の
位置近傍には到達しないようにし、厚い透明基板を有す
る記録媒体の記録または再生時には第３光束が第１光束
および第２光束が集光する記録面上の位置近傍には到達
しないようにする機能を有する光束制限手段を有するこ
とを特徴とする。A transparent light source comprising two laser light sources having different wavelengths, one condensing optical system including an objective lens for converging a laser beam from the light source on a recording surface, and a light receiving element for detecting reflected light from the recording surface. In an optical system for an optical pickup for recording / reproducing at least two types of optical information recording media having different substrate thicknesses, a first laser light source having a first wavelength is used for recording / reproducing an optical information recording medium having a thin transparent substrate. The second laser light source of the second wavelength is for recording / reproducing an optical information recording medium having a thick transparent substrate, and the above optical system has a light flux of the condensing optical system in an annular shape from the vicinity of the optical axis to the outside. To 3
(In the case where such a means is incorporated in an objective lens, such an objective lens is hereinafter referred to as a special objective lens). When the first, second, and third light beams are used,
The first light beam is for a recording medium having a thick transparent substrate, the second light beam is for a recording medium having a thick transparent substrate, and the third light beam is mainly for a recording medium having a thin transparent substrate. During recording or reproduction on a recording medium having a thin transparent substrate, the second light beam reaches a portion near the position on the recording surface where the first light beam and the third light beam converge, at a portion where the light beams from the two light sources pass through in common. Light beam limiting means having a function of preventing the third light beam from reaching near the position on the recording surface where the first light beam and the second light beam converge during recording or reproduction on a recording medium having a thick transparent substrate. It is characterized by having.
【０００８】上記光束制限手段は、第１の波長の第１の
光束および第３の光束を透過し、第２の光束を回折し、
第２の波長の第１の光束および第２の光束を透過し、第
３の光束を回折する波長選択性回折格子であることが出
来る。また、上記光束制限手段は、第１の波長の第１の
光束および第３の光束を透過し、第２の光束を反射し、
第２の波長の第１の光束および第２の光束を透過し、第
３の光束を反射する波長選択性フィルターであることが
出来る。さらに、上記光束制限手段は、第１の波長の第
１の光束および第３の光束を透過し、第２の光束を吸収
し、第２の波長の第１の光束および第２の光束を透過
し、第３の光束を吸収する波長選択性フィルターである
ことができる。The light beam limiting means transmits the first light beam and the third light beam of the first wavelength, diffracts the second light beam,
It can be a wavelength-selective diffraction grating that transmits the first light beam and the second light beam of the second wavelength and diffracts the third light beam. Further, the light beam limiting means transmits the first light beam and the third light beam of the first wavelength, reflects the second light beam,
It may be a wavelength selective filter that transmits the first light beam and the second light beam of the second wavelength and reflects the third light beam. Further, the light beam limiting means transmits the first light beam and the third light beam of the first wavelength, absorbs the second light beam, and transmits the first light beam and the second light beam of the second wavelength. And it can be a wavelength selective filter that absorbs the third light flux.
【０００９】二つの光源からの光束が共通して通る部分
において、第１の光源からの光束と第２の光源からの光
束が、互いに偏光方向が直交した直線偏光である場合に
は、上記光束制限手段は、第１の波長の第１の光束およ
び第３の光束を透過し、第２の光束を回折し、第２の波
長の第１の光束および第２の光束を透過し、第３の光束
を回折する偏光ホログラム素子であることが出来る。In a portion where the light beams from the two light sources pass through in common, if the light beam from the first light source and the light beam from the second light source are linearly polarized light whose polarization directions are orthogonal to each other, The limiting means transmits the first light beam and the third light beam of the first wavelength, diffracts the second light beam, transmits the first light beam and the second light beam of the second wavelength, and transmits the third light beam. Can be a polarization hologram element that diffracts the light beam.
【００１０】上記光ピックアップ装置には、少なくと
も、一方の光情報記録媒体の記録再生には略同波長の複
数の光ビームが使用されることが出来る。また、同一波
長の光源からの光束を複数の光ビームとするための回折
格子が使用されてもよい。In the above optical pickup device, a plurality of light beams having substantially the same wavelength can be used for recording / reproducing at least one optical information recording medium. Further, a diffraction grating for converting a light beam from a light source having the same wavelength into a plurality of light beams may be used.
【００１１】上記ピックアップ装置は、少なくとも２つ
の波長の異なるレーザ光源を備え、少なくとも１つのレ
ーザ光源は光検出器と一体に構成されたレーザ／検出器
集積ユニットであることができる。また、上記ピックア
ップは、波長の異なる２つのレーザ光源を備え、２つの
レーザ光源は光検出器と一体に構成されたレーザ／検出
器集積ユニットであってもよい。[0011] The pickup device may include at least two laser light sources having different wavelengths, and at least one laser light source may be a laser / detector integrated unit integrally formed with a photodetector. Further, the pickup may include two laser light sources having different wavelengths, and the two laser light sources may be a laser / detector integrated unit integrally formed with the photodetector.
【００１２】上記光束制限手段は、二つの光源からの光
束が共通してとおる部分に配設され、特殊対物レンズと
一体的に移動可能にユニット化されていることが望まし
い。上記光束制限手段は、光ピックアップ装置の光路中
に配設される光学素子であって、該光ピックアップ装置
はレーザ光の光束を光軸近傍から外側に向かって輪帯状
に３つの光束に分割する手段を含み、光軸近傍から外側
に向かって順次第１、第２、第３光束としたとき、第１
光束はすべての透明基板の厚みの異なる記録媒体用であ
り、第２光束は主に厚い透明基板を有する記録媒体用、
第３光束は主に薄い透明基板を有する記録媒体用とされ
る。そして、上記光束制限手段は、上記分割手段の第２
光束の少なくとも一部に対して、波長の異なる２つのレ
ーザ光のうち長い波長のレーザ光は光情報記録媒体の情
報記録面からの反射光を検出する受光素子に受光され、
短い波長のレーザ光は受光素子に受光されないように
し、上記分割手段の第３光束の少なくとも一部に対し
て、波長の異なる２つのレーザ光のうち短い波長のレー
ザ光は光情報記録媒体の情報記録面からの反射光を検出
する受光素子に受光され、長い波長のレーザ光は受光素
子に受光されないようにする機能を有する。The light beam restricting means is preferably provided at a portion where the light beams from the two light sources pass through in common, and is preferably unitized so as to be movable integrally with the special objective lens. The light beam restricting means is an optical element disposed in an optical path of the optical pickup device, and the optical pickup device divides the light beam of the laser beam into three light beams in an annular shape from the vicinity of the optical axis to the outside. When the first, second, and third light beams are sequentially formed from the vicinity of the optical axis to the outside, the first
The luminous flux is for a recording medium having different thicknesses of all the transparent substrates, and the second luminous flux is mainly for a recording medium having a thick transparent substrate,
The third light beam is mainly used for a recording medium having a thin transparent substrate. The light beam restricting means is a second light source of the dividing means.
For at least a part of the light beam, a laser beam having a longer wavelength among the two laser beams having different wavelengths is received by a light receiving element that detects reflected light from an information recording surface of an optical information recording medium,
The short-wavelength laser light is prevented from being received by the light-receiving element, and at least a part of the third light beam of the splitting means, of the two laser lights having different wavelengths, the short-wavelength laser light is the information of the optical information recording medium. It has a function of receiving light received by a light receiving element that detects light reflected from a recording surface, and preventing long-wavelength laser light from being received by the light receiving element.
【００１３】さらに、上記光束制限手段は特殊対物レン
ズと一体化されていることが好ましい。すなわち、本発
明の光ピックアップ用の特殊対物レンズは、レーザ光の
光束を光軸近傍から外側に向かって輪帯状に３つの光束
に分割する手段を含み、光軸近傍から外側に向かって順
次第１、第２、第３光束としたとき、第１光束はすべて
の透明基板の厚みの異なる記録媒体用であり、第２光束
は主に厚い透明基板を有する記録媒体用、第３光束は主
に薄い透明基板を有する記録媒体用であり、該分割手段
の第２光束の少なくとも一部に対して、波長の異なる２
つのレーザ光のうち長い波長のレーザ光は光情報記録媒
体の情報記録面からの反射光を検出する受光素子に受光
され、短い波長のレーザ光は受光素子に受光されないよ
うにし、該分割手段の第３光束の少なくとも一部に対し
て、波長の異なる２つのレーザ光のうち短い波長のレー
ザ光は光情報記録媒体の情報記録面からの反射光を検出
する受光素子に受光され、長い波長のレーザ光は受光素
子に受光されないようにする機能を有する光束制限機能
（波長選択機能）を持たせる。Further, it is preferable that the light beam restricting means is integrated with a special objective lens. That is, the special objective lens for an optical pickup of the present invention includes a means for dividing the light beam of the laser beam into three light beams in an annular shape from the vicinity of the optical axis to the outside, and sequentially emits the light beam from the vicinity of the optical axis to the outside. When the first, second, and third light beams are used, the first light beam is for a recording medium having all transparent substrates having different thicknesses, the second light beam is mainly for a recording medium having a thick transparent substrate, and the third light beam is mainly for a recording medium having a thick transparent substrate. For a recording medium having a thin transparent substrate, and at least a part of the second light flux of the splitting means has different wavelengths.
The laser light having a longer wavelength among the two laser lights is received by a light receiving element for detecting the reflected light from the information recording surface of the optical information recording medium, and the laser light having a shorter wavelength is prevented from being received by the light receiving element. For at least a part of the third light beam, a laser beam having a shorter wavelength among two laser beams having different wavelengths is received by a light receiving element for detecting light reflected from an information recording surface of an optical information recording medium, and has a longer wavelength. The laser beam is provided with a light beam limiting function (wavelength selecting function) having a function of preventing the light from being received by the light receiving element.
【００１４】[0014]
【発明の実施の形態】以下図面を参照して、本発明をさ
らに詳細に説明する。図１は本発明の光ピックアップ装
置の構成を示す概念図である。波長が６５０ｎｍの短波
長光源である半導体レーザ１１からの光束は、回折格子
２６で３つの光束に分割される。これらの光束はビーム
スプリッタ１２を透過し、ビームスプリッタ１３で反射
し、集光レンズ１４で平行光束となり、光束制限手段１
５を透過し、絞り２５を経て特殊対物レンズ１６によっ
てＤＶＤなどの高密度記録用光ディスク１７の透明基板
１７’を介して情報記録面１７”上にスポットを形成す
る。情報記録面１７”で情報ピットにより変調された反
射光束は、再び対物レンズ１６、光束制限手段１５、集
光レンズ１４により収束光となり、ビームスプリッタ１
３およびビームスプリッタ１２で反射し、複合レンズ１
８により光検出器１９に収束する。一方、より記録密度
の低いＣＤなどの光ディスクの記録再生時には、波長が
７８０ｎｍの長波長光源である半導体レーザ２１はレー
ザ／検出器集積ユニット２に光検出器２２およびホログ
ラム２３と一体に組み込まれ、レーザ２１からの光束は
ビームスプリッタ１３を透過し、集光レンズ１４、特殊
対物レンズ１６によって情報記録面にスポットを形成す
る。変調された反射光は同じ光路を通り、ホログラム２
３によって光検出器２２へ入射する。図中３はフォーカ
ス制御およびトラッキング制御のための２次元アクチュ
エータであり、光束制御手段１５、絞り２５、特殊対物
レンズ１６はこれにより一体駆動される。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the drawings. FIG. 1 is a conceptual diagram showing the configuration of the optical pickup device of the present invention. A light beam from a semiconductor laser 11 which is a short wavelength light source having a wavelength of 650 nm is split by a diffraction grating 26 into three light beams. These light beams pass through the beam splitter 12, are reflected by the beam splitter 13, become parallel light beams by the condenser lens 14,
5, a spot is formed on the information recording surface 17 "via the transparent substrate 17 'of the optical disc 17 for high-density recording such as a DVD by the special objective lens 16 through the aperture 25. The information is recorded on the information recording surface 17". The reflected light flux modulated by the pits becomes convergent light again by the objective lens 16, the light flux restricting means 15, and the condenser lens 14, and is converged by the beam splitter 1.
3 and the beam splitter 12, the composite lens 1
8 converges on the photodetector 19. On the other hand, when recording / reproducing an optical disk such as a CD having a lower recording density, the semiconductor laser 21 which is a long-wavelength light source having a wavelength of 780 nm is integrated into the laser / detector integrated unit 2 integrally with the photodetector 22 and the hologram 23. The light beam from the laser 21 passes through the beam splitter 13 and forms a spot on the information recording surface by the condenser lens 14 and the special objective lens 16. The modulated reflected light passes through the same optical path, and the hologram 2
3 enters the photodetector 22. In the figure, reference numeral 3 denotes a two-dimensional actuator for focus control and tracking control, and the light flux control means 15, the aperture 25, and the special objective lens 16 are integrally driven by this.
【００１５】特殊対物レンズは、特に望ましくはその光
源側の屈折面は同心円状に分割された複数の輪帯面から
なり、各輪帯は、その球面収差を利用して波長の異なる
複数の光源、及び／または、厚みの異なる透明基板に対
してほぼ回折限界のスポットを生じるように収差補正さ
れたレンズである。中心部分の第１輪帯、その外側の第
２輪帯、最外側の第３輪帯からなる１実施例を下表に、
その収差図を図２に示す。 波長λ（nm） 635 780 焦点距離（mm） 3.36 3.39 必要開口数NA 0.60 0.45 面 ri di di' ni ni' １ 2.114 2.200 1.5383 1.5337 ２ -7.963 1.757 1.401 1.0 1.00 ３ ∞ 0.600 1.200 1.58 1.58 ４ ∞ 表中（’）が附されているのはＣＤ対応時である。It is particularly desirable that the refracting surface on the light source side of the special objective lens is composed of a plurality of concentrically divided annular zones, and that each annular zone uses a spherical aberration to generate a plurality of light sources having different wavelengths. And / or an aberration-corrected lens so as to generate a diffraction-limited spot on transparent substrates having different thicknesses. The following table shows an example including a first annular zone at the center, a second annular zone outside the first annular zone, and an outermost third annular zone.
The aberration diagram is shown in FIG. Wavelength λ (nm) 635 780 Focal length (mm) 3.36 3.39 Required numerical aperture NA 0.60 0.45 plane ri di di 'ni ni' 1 2.114 2.200 1.5383 1.5337 2 -7.963 1.757 1.401 1.0 1.00 3 ∞ 0.600 1.200 1.58 1.58 4 中 In the table (') Is for CD compatible.
【００１６】図２（ａ）はＤＶＤ対応時の収差補正状況
であり、NA＝0.45近傍の第２輪帯を除いて回折限界に補
正されている。同図（ｂ）はＣＤ対応時であり、第１輪
帯はその焦点深度の深さによって、第２輪帯は発生する
球面収差によって、ＣＤ記録面に回折限界のスポットを
形成する。それぞれの輪帯の非球面データは以下のよう
である。 非球面データ 第２面 第１ ０≦Ｈ＜1.279 （第１輪帯） (屈折面) 非球面 1.532≦Ｈ （第３輪帯） κ＝ -0.97700 A1＝ 0.63761×10-3 P1＝3.0 A2＝ 0.36688×10-3 P1＝4.0 A3＝ 0.83511×10-2 P1＝5.0 A4＝ -0.37296×10-2 P1＝6.0 A5＝ 0.46548×10-3 P1＝8.0 A6＝ -0.43124×10-4 P1＝10.0 第２ 1.279≦Ｈ＜1.532 （第２輪帯） 非球面 ｄ2＝2.1995 κ＝ -0.11481×10 A1＝ 0.70764×10-2 P1＝3.0 A2＝ -0.13388×10-1 P1＝4.0 A3＝ 0.24084×10-1 P1＝5.0 A4＝ -0.97636×10-2 P1＝6.0 A5＝ 0.93136×10-3 P1＝8.0 A6＝ -0.68008×10-4 P1＝10.0 第３面 κ＝ -0.24914×102 (屈折面) A1＝ 0.13775×10-2 P1＝3.0 A2＝ -0.41269×10-2 P1＝4.0 A3＝ 0.21236×10-1 P1＝5.0 A4＝ -0.13895×10-1 P1＝6.0 A5＝ 0.16631×10-2 P1＝8.0 A6＝ -0.12138×10-3 P1＝10.0 表中d2は、第２輪帯の形状を非球面形状式に従って光軸
まで延長したときの光軸との交点と、第３面との光軸上
の間隔を示している。図において、第２輪帯の幅は、NA
LからＣＤの必要開口数NA2よりわずかに大きいNAHま
で、すなわち1.279〜1.532とされている。また、非球面
は次式に基づくものである。FIG. 2 (a) shows the aberration correction situation in the case of DVD compatibility. The aberration is corrected to the diffraction limit except for the second annular zone near NA = 0.45. FIG. 2B shows a case where the CD is compatible, and the first orbicular zone forms a diffraction-limited spot on the CD recording surface due to the depth of focus thereof and the second orbicular zone due to the generated spherical aberration. The aspherical data of each ring zone is as follows. Aspheric surface data Second surface First 0 ≦ H <1.279 (1st zone) (refractive surface) Aspheric surface 1.532 ≦ H (3rd zone) κ = -0.97700 A 1 = 0.63761 × 10 -3 P 1 = 3.0 A 2 = 0.36688 × 10 -3 P 1 = 4.0 A 3 = 0.83511 × 10 -2 P 1 = 5.0 A 4 = -0.37296 × 10 -2 P 1 = 6.0 A 5 = 0.46548 × 10 -3 P 1 = 8.0 A 6 = -0.43124 × 10 -4 P 1 = 10.0 Second 2.279 ≦ H <1.532 (2nd annular zone) Aspherical surface d 2 = 2.1995 κ = -0.11481 × 10 A 1 = 0.70764 × 10 -2 P 1 = 3.0 A 2 = -0.13388 × 10 -1 P 1 = 4.0 A 3 = 0.24084 × 10 -1 P 1 = 5.0 A 4 = -0.97636 × 10 -2 P 1 = 6.0 A 5 = 0.93136 × 10 -3 P 1 = 8.0 A 6 = -0.68008 × 10 -4 P 1 = 10.0 Third surface κ = -0.24914 × 10 2 (refractive surface) A 1 = 0.13775 × 10 -2 P 1 = 3.0 A 2 = -0.41269 × 10 -2 P 1 = 4.0 A 3 = 0.21236 x 10 -1 P 1 = 5.0 A 4 = -0.13895 x 10 -1 P 1 = 6.0 A 5 = 0.16631 x 10 -2 P 1 = 8.0 A 6 = -0.12138 x 10 -3 P 1 = 10.0 d 2 in the table is the value when the shape of the second annular zone is extended to the optical axis according to the aspherical shape equation. The distance on the optical axis between the intersection with the optical axis and the third surface is shown. In the figure, the width of the second annular zone is NA
L to NAH required slightly larger than the numerical aperture NA 2 of the CD, that is, with 1.279 to 1.532. The aspherical surface is based on the following equation.
【数１】 但しＸは光軸方向の軸、Ｈは光軸と垂直方向の軸、光の
進行方向を正とし、ｒは近軸曲率半径、κは円錐形数、
Ａｊは非球面係数、Ｐｊは非球面のべき数（ただし、Ｐ
ｊ≧３）である。(Equation 1) Where X is the axis in the direction of the optical axis, H is the axis perpendicular to the optical axis, and the traveling direction of light is positive, r is the paraxial radius of curvature, κ is the number of cones,
Aj is the aspheric coefficient, and Pj is the power of the aspheric surface (where P
j ≧ 3).
【００１７】このように補正された特殊対物レンズで形
成されたビームスポットの形状は、図３、図４に示す。
図２（ａ）の場合の第２輪帯および同図（ｂ）の場合の
第３輪帯を透過した光は、情報記録面には収束せず、図
３、図４に見るようにサイドローブを形成する。このよ
うなサイドローブは、光検出器に入射すると、フレアと
なって、フォーカシング、トラッキング時に光検出器の
出力に変動を与えるだけでなく、記録面から外れた場所
に副次的な収束点を形成するように働く。図５はそれぞ
れ光束制限手段がない場合の、フォーカシングのための
光検出器の出力を示すいわゆるＳカーブであり、同図
（ａ）はＤＶＤの場合、同図（ｂ）はＣＤの場合を示
す。０位置で示す本来の合焦位置のほかに、ＤＶＤの場
合は左側に、ＣＤの場合は右側に小さいＳカーブを見る
ことが出来る。これがサイドローブの収束点によるもの
であり、焦点ずれが大きく出た場合、これを合焦位置と
誤判定する危険性が生じる。FIGS. 3 and 4 show the shape of the beam spot formed by the special objective lens corrected in this way.
The light transmitted through the second orbicular zone in the case of FIG. 2A and the third orbicular zone in the case of FIG. 2B does not converge on the information recording surface, and as shown in FIGS. Form lobes. When such a side lobe enters the photodetector, it becomes a flare and not only fluctuates the output of the photodetector at the time of focusing and tracking, but also creates a secondary convergence point at a position off the recording surface. Work to form. FIG. 5 is a so-called S-curve showing the output of the photodetector for focusing when there is no light beam limiting means. FIG. 5A shows the case of a DVD, and FIG. 5B shows the case of a CD. . In addition to the original in-focus position indicated by the 0 position, a small S curve can be seen on the left side for a DVD and on the right side for a CD. This is due to the convergence point of the side lobe, and when the defocus is large, there is a risk that this is erroneously determined as the in-focus position.
【００１８】図６は、光束制限手段がない場合の、光検
出器１９上のスポットを示す。光検出器は、ＡからＦま
での６つのディテクターから構成されており、フォーカ
ス誤差信号ＦＥ、トラッキング誤差信号ＴＥ、情報信号
ＲＦは、各ディテクターＡからＦまでの出力を、それぞ
れＡからＦとすると、図示しない演算回路で、以下の演
算をすることで得られる。 ＦＥ＝（Ａ＋Ｃ）−（Ｂ＋Ｄ） ＴＥ＝Ｅ−Ｆ ＲＦ＝Ａ＋Ｂ＋Ｃ＋Ｄ メインビーム、サブビームともにフレアが発生してお
り、メインビームのフレアがサブビーム用のディテクタ
ーＥ、Ｆに入射している。このためトラッキングのため
にレンズが移動したり、トラッキング方向にレンズが傾
いたりした場合にフレア成分も移動し、ディテクター
Ｅ、Ｆに入射する量も変化し、トラッキングがあってい
ない状態でＴＥ信号が０となり問題を起こす。FIG. 6 shows a spot on the photodetector 19 when there is no light beam limiting means. The photodetector is composed of six detectors A to F. The focus error signal FE, the tracking error signal TE, and the information signal RF assume that the outputs from the detectors A to F are A to F, respectively. , Can be obtained by performing the following operation using an arithmetic circuit (not shown). FE = (A + C)-(B + D) TE = EF RF = A + B + C + D Flares are generated in both the main beam and the sub beam, and the flare of the main beam is incident on detectors E and F for the sub beam. Therefore, when the lens moves for tracking or the lens tilts in the tracking direction, the flare component also moves, the amount of light incident on the detectors E and F also changes, and the TE signal is output when tracking is not performed. 0, causing a problem.
【００１９】このようなサイドローブが光検出器に入射
するのを防ぐ光束制限手段としては、図７のように、領
域Ｉ、領域II、領域IIIに同心円状に分割された波長選
択性の光束制限素子を使えばよい。領域Ｉは、波長６５
０ｎｍの光と、波長７８０ｎｍの光とを共に透過する。
領域IIは、波長７８０ｎｍの光を透過し、波長６５０ｎ
ｍの光を回折または反射または吸収する。領域IIIは、
波長６５０ｎｍの光を透過し、波長７８０ｎｍの光を回
折または反射または吸収する。すでに、領域IIがない波
長選択性の光束制限素子は、種々知られており、領域II
は、それらの技術の応用で製作が可能である。尚、領域
の大きさに関しては、光束制限素子を配置する位置にお
いて、特殊対物レンズの３つの光束の光軸からの離れ量
を計算し、ＤＶＤの記録または再生時には第２光束が第
１光束および第３光束が集光する記録面上の位置近傍に
は到達しないように、ＣＤ記録または再生時には第３光
束が第１光束および第２光束が集光する記録面上の位置
近傍には到達しないように、領域Ｉ、II、IIIを設定す
ればよい。As a light beam limiting means for preventing such side lobes from entering the photodetector, as shown in FIG. 7, a wavelength-selective light beam divided concentrically into region I, region II and region III is used. A limiting element may be used. Region I has a wavelength of 65
The light having a wavelength of 0 nm and the light having a wavelength of 780 nm are both transmitted.
Region II transmits light having a wavelength of 780 nm and has a wavelength of 650 nm.
m is diffracted or reflected or absorbed. Region III is
It transmits light having a wavelength of 650 nm and diffracts, reflects or absorbs light having a wavelength of 780 nm. Various types of wavelength-selective luminous flux limiting elements without Region II are already known.
Can be manufactured by applying those technologies. Regarding the size of the area, the distances of the three light beams of the special objective lens from the optical axis are calculated at the position where the light beam restricting element is arranged, and the second light beam is converted into the first light beam and the first light beam during recording or reproduction of DVD. The third light beam does not reach near the position on the recording surface where the first light beam and the second light beam converge during CD recording or reproduction so that the third light beam does not reach near the position on the recording surface where the third light beam condenses. Thus, the regions I, II, and III may be set.
【００２０】光源として１つの半導体レーザを用い、あ
るいはほぼ同一波長を持つ複数の半導体レーザを用いる
光ピックアップ装置においては、光束制限素子として、
上記のような波長選択性の素子を用いることは出来な
い。しかし、領域Ｉおよび領域IIは光を透過し、領域II
Iは光を反射または吸収する光束制限素子と、領域Ｉお
よび領域IIIは光を透過し、領域IIは光を反射または吸
収する光束制限素子とを、光路中に適宜挿脱することに
よって同じ作用を行わせることが出来る。In an optical pickup device using one semiconductor laser as a light source or a plurality of semiconductor lasers having substantially the same wavelength,
The above-described wavelength-selective element cannot be used. However, region I and region II transmit light and region II
I has the same function as a light beam limiting element that reflects or absorbs light, and a region I and a region III transmit light, and a region II has a light beam limiting element that reflects or absorbs light in the optical path. Can be performed.
【００２１】図８に第２実施例において、第１実施例と
同じ部材は同じ符号で示す。この場合も、光束制御手段
１５、絞り２５、特殊対物レンズ１６は一体的に移動可
能にユニット化することが望ましく、３は該ユニットの
アクチュエータである。この実施例においては、短波長
光についてもレーザ／検出器集積ユニット５を使用して
おり、種々の設計変更が可能である。In FIG. 8, in the second embodiment, the same members as those in the first embodiment are denoted by the same reference numerals. Also in this case, it is desirable that the light flux control means 15, the aperture 25, and the special objective lens 16 be integrally unitized so as to be movable integrally, and 3 is an actuator of the unit. In this embodiment, the laser / detector integrated unit 5 is used for short-wavelength light, and various design changes are possible.
【００２２】図９の光ピックアップ装置においては、第
１半導体レーザ１１、第２半導体レーザ２１、第１の光
検出器１９、第２の光検出器２２、ホログラム２３がレ
ーザ／検出器集積ユニット７としてユニット化されてい
る。第１の光ディスクを再生する場合、第１半導体レー
ザ１１から出射された光束は、ホログラム２３のディス
ク側の面、集光レンズ１４を透過し平行光束となる。さ
らに光束制限手段１５を透過し、絞り２５を経て特殊対
物レンズ１６によってＤＶＤなどの高密度記録用光ディ
スク１７の透明基板を介して情報記録面上にスポットを
形成する。情報記録面で情報ピットにより変調された反
射光束は、再び対物レンズ１６、光束制限手段１５、集
光レンズ１４により収束光となり、ホログラム２３で回
折され、第１の光源に対応した光検出器１９上へ入射
し、その出力信号を用いて、第１光ディスク１７に記録
された情報の読み取り信号が得られる。また、光検出器
１９上でのスポットの形状変化、位置変化による光量変
化を検出して、合焦検出やトラック検出を行い、２次元
アクチュエータにより、合焦、トラッキングのために対
物レンズユニットを移動させる。In the optical pickup device of FIG. 9, the first semiconductor laser 11, the second semiconductor laser 21, the first photodetector 19, the second photodetector 22, and the hologram 23 are composed of the laser / detector integrated unit 7. As a unit. When reproducing the first optical disk, the light beam emitted from the first semiconductor laser 11 passes through the disk-side surface of the hologram 23 and the condensing lens 14 and becomes a parallel light beam. Further, the light passes through the light beam restricting means 15 and passes through the stop 25 to form a spot on the information recording surface via the transparent substrate of the optical disk 17 for high density recording such as a DVD by the special objective lens 16. The reflected light flux modulated by the information pits on the information recording surface becomes convergent light again by the objective lens 16, the light flux limiting means 15, and the condenser lens 14, is diffracted by the hologram 23, and is detected by the photodetector 19 corresponding to the first light source. The signal is read upward and the read signal of the information recorded on the first optical disk 17 is obtained using the output signal. In addition, a change in the light amount due to a change in the shape and position of the spot on the photodetector 19 is detected, focus detection and track detection are performed, and the objective lens unit is moved for focusing and tracking by a two-dimensional actuator. Let it.
【００２３】第２の光ディスクを再生する場合、第２半
導体レーザ２１から出射された光束は、ホログラム２３
の半導体レーザ側の面で回折され、集光レンズ１４を透
過してほぼ平行光束となる。このホログラムの半導体レ
ーザ側の面は、光合成手段としての機能を果たす。さら
に光束制限手段１５を透過し、絞り２５を経て特殊対物
レンズ１６によってＣＤなどの記録用光ディスク１７の
透明基板を介して情報記録面上にスポットを形成する。
情報記録面で情報ピットにより変調された反射光束は、
再び対物レンズ１６、光束制限手段１５、集光レンズ１
４により収束光となり、ホログラム２３で回折され、第
２の光源に対応した光検出器２２上へ入射し、その出力
信号を用いて、第１光ディスク１７に記録された情報の
読み取り信号が得られる。When reproducing the second optical disk, the light beam emitted from the second semiconductor laser 21
Is diffracted by the surface on the side of the semiconductor laser, and passes through the condenser lens 14 to become a substantially parallel light beam. The surface of the hologram on the semiconductor laser side functions as a light combining means. Furthermore, a spot is formed on the information recording surface through the transparent substrate of the recording optical disk 17 such as a CD by the special objective lens 16 through the aperture 25 and through the aperture 25.
The reflected light flux modulated by the information pit on the information recording surface is
Again, the objective lens 16, the light beam limiting means 15, and the condenser lens 1
4, the light becomes convergent light, is diffracted by the hologram 23, is incident on the photodetector 22 corresponding to the second light source, and a read signal of information recorded on the first optical disc 17 is obtained by using the output signal. .
【００２４】上記の光束制限手段は、特殊対物レンズと
一体に構成する場合、同心円状に分割された複数の輪帯
を対物レンズの光源側あるいは光情報記録媒体側の屈折
面に設けることが出来る。図１０は、対物レンズの光源
側の第３輪帯面Ｓ３に、図７における領域IIIに相当す
る波長選択性、すなわち、波長６５０ｎｍの光を透過
し、波長７８０ｎｍの光を回折または反射または吸収す
る層を、また第２輪帯Ｓ２には領域IIに相当する波長選
択性、すなわち、波長７８０ｎｍの光を透過し、波長６
５０ｎｍの光を回折または反射または吸収する層を設け
たものである。各輪帯間の段差Ｓｓは、各輪帯の透過光
間の位相シフトを生じさせるためのものであり、対物レ
ンズを成形するときにこの段差Ｓｓが共に成形されても
良い。また、上記対物レンズは、プラスチックレンズあ
るいはガラスレンズであってもよいだけでなく、ガラス
レンズあるいはプラスチックレンズの光学面に樹脂層を
設けたハイブリッドレンズであっても良い。When the above-mentioned light flux limiting means is formed integrally with a special objective lens, a plurality of concentrically divided annular zones can be provided on the refracting surface of the objective lens on the light source side or on the optical information recording medium side. . FIG. 10 shows that the third annular surface S3 on the light source side of the objective lens has wavelength selectivity corresponding to the region III in FIG. 7, that is, transmits light having a wavelength of 650 nm and diffracts, reflects or absorbs light having a wavelength of 780 nm. The second ring zone S2 has a wavelength selectivity corresponding to the region II, that is, a layer having a wavelength of 780 nm and a wavelength of 6 nm.
It is provided with a layer that diffracts, reflects or absorbs 50 nm light. The step Ss between the ring zones is for causing a phase shift between the transmitted lights of the ring zones, and the step Ss may be formed together when the objective lens is formed. Further, the objective lens may be not only a plastic lens or a glass lens, but also a hybrid lens having a resin layer provided on an optical surface of the glass lens or the plastic lens.
【００２５】[0025]
【発明の効果】本発明の光ピックアップ装置は、複数の
光情報記録媒体の記録再生を１つの集光光学系で行なう
にあたり、特殊対物レンズによる不使用光のフレアを、
複数の光情報記録媒体の全てについて効果的に除去する
ことにより、構成を複雑化することなく、低コストで、
精度の高い制御を可能にした。According to the optical pickup device of the present invention, when recording / reproducing a plurality of optical information recording media with one condensing optical system, flare of unused light by a special objective lens is reduced.
By effectively removing all of the plurality of optical information recording media, without complicating the configuration, at low cost,
Highly accurate control is enabled.
【図１】本発明を実施する光ピックアップの１実施態様
の構成を示す概念図である。FIG. 1 is a conceptual diagram showing a configuration of an embodiment of an optical pickup embodying the present invention.
【図２】本発明に使用される特殊対物レンズの収差図で
ある。FIG. 2 is an aberration diagram of a special objective lens used in the present invention.
【図３】短波長光の収束スポットの光強度分布を示すグ
ラフである。FIG. 3 is a graph showing a light intensity distribution of a convergent spot of short-wavelength light.
【図４】長波長光の収束スポットの光強度分布を示すグ
ラフである。FIG. 4 is a graph showing a light intensity distribution of a convergent spot of long wavelength light.
【図５】フォーカシング制御のための光検出器の出力曲
線である。FIG. 5 is an output curve of a photodetector for focusing control.
【図６】光束制限手段がない場合の、光検出器上に形成
される光スポットを示す模式図である。FIG. 6 is a schematic diagram showing a light spot formed on a photodetector when there is no light beam limiting means.
【図７】本発明の光束制限手段の構成の１例を示す模式
図である。FIG. 7 is a schematic diagram showing an example of the configuration of the light beam restricting means of the present invention.
【図８】本発明を実施する光ピックアップの他の実施態
様の構成を示す概念図である。FIG. 8 is a conceptual diagram showing a configuration of another embodiment of the optical pickup embodying the present invention.
【図９】本発明を実施する光ピックアップのさらに他の
実施態様の構成を示す概念図である。FIG. 9 is a conceptual diagram showing a configuration of still another embodiment of the optical pickup embodying the present invention.
【図１０】本発明の光束制限手段を一体に設けた特殊対
物レンズの構成の１例を示す概念図である。FIG. 10 is a conceptual diagram showing an example of a configuration of a special objective lens integrally provided with a light flux restricting unit of the present invention.
１ 光ピックアップ ２，５，７ レーザ／検出
器集積ユニット ３ ２次元アクチュエータ １１，２１ 半導体レーザ １２ ビームスプリ
ッタ １３ ビームスプリッタ １４ 集光レンズ １５ 光束制限手段 １６ 特殊対物レン
ズ １７ 光ディスク １８ 複合レンズ １９，２２ 光検出器 ２３ ホログラム ２５ 絞り ２６ 回折格子Reference Signs List 1 optical pickup 2, 5, 7 laser / detector integrated unit 3 two-dimensional actuator 11, 21 semiconductor laser 12 beam splitter 13 beam splitter 14 condensing lens 15 light flux limiting means 16 special objective lens 17 optical disk 18 compound lens 19, 22 light Detector 23 Hologram 25 Aperture 26 Diffraction grating
Claims (17)
記録面に収束する対物レンズを含む１つの集光光学系、
および記録面からの反射光を検出する受光素子からな
り、透明基板の厚みが異なる少なくとも２種の光情報記
録媒体の記録再生用光ピックアップ装置のための光学系
において、 該光学系は、集光光学系の光束が光軸近傍から外側に向
かって輪帯状に３つの光束に分割される手段を含み、光
軸近傍から外側に向かって順次第１、第２、第３光束と
したとき、第１光束はすべての透明基板の厚みの異なる
記録媒体用であり、第２光束は主に厚い透明基板を有す
る記録媒体用、第３光束は主に薄い透明基板を有する記
録媒体用であり、 薄い透明基板を有する記録媒体の記録または再生時には
記録面からの第２光束の反射光が上記受光素子へ入射し
ないような光束制限を行ったことを特徴とする光ピック
アップ装置のための光学系A condensing optical system including a laser light source, an objective lens for converging a laser beam from the light source on a recording surface,
An optical system for recording / reproducing an optical pickup device for recording / reproducing at least two types of optical information recording media having different thicknesses of transparent substrates, the optical system comprising: The optical system includes means for dividing a light beam of the optical system into three annular light beams in a ring shape from the vicinity of the optical axis to the outside. When the first, second, and third light beams are sequentially formed from the vicinity of the optical axis to the outside, One light beam is for a recording medium having a thick transparent substrate, the second light beam is for a recording medium having a thick transparent substrate, and the third light beam is mainly for a recording medium having a thin transparent substrate. An optical system for an optical pickup device, wherein a light beam is restricted such that reflected light of a second light beam from a recording surface does not enter the light receiving element during recording or reproduction of a recording medium having a transparent substrate.
記録面に収束する対物レンズを含む１つの集光光学系、
および記録面からの反射光を検出する受光素子からな
り、透明基板の厚みが異なる少なくとも２種の光情報記
録媒体の記録再生用光ピックアップ装置のための光学系
において、 該光学系は、集光光学系の光束が光軸近傍から外側に向
かって輪帯状に３つの光束に分割される手段を含み、光
軸近傍から外側に向かって順次第１、第２、第３光束と
したとき、第１光束はすべての透明基板の厚みの異なる
記録媒体用であり、第２光束は主に厚い透明基板を有す
る記録媒体用、第３光束は主に薄い透明基板を有する記
録媒体用であり、 薄い透明基板を有する記録媒体の記録または再生時には
記録面からの第２光束の反射光が上記受光素子へ入射し
ないような光束制限を行い、 厚い透明基板を有する記録媒体の記録または再生時には
記録面からの第３光束の反射光が上記受光素子へ入射し
ないような光束制限を行ったことを特徴とする光ピック
アップ装置のための光学系2. One condensing optical system including a laser light source, and an objective lens for converging a laser beam from the light source on a recording surface,
An optical system for recording / reproducing an optical pickup device for recording / reproducing at least two types of optical information recording media having different thicknesses of transparent substrates, the optical system comprising: The optical system includes means for dividing a light beam of the optical system into three annular light beams in a ring shape from the vicinity of the optical axis to the outside. When the first, second, and third light beams are sequentially formed from the vicinity of the optical axis to the outside, One light beam is for a recording medium having a thick transparent substrate, the second light beam is for a recording medium having a thick transparent substrate, and the third light beam is mainly for a recording medium having a thin transparent substrate. When recording or reproducing a recording medium having a transparent substrate, the light beam is restricted so that the reflected light of the second light beam from the recording surface does not enter the light receiving element. No. An optical system for an optical pickup device reflected light of the light beam is equal to or subjected to light beam restriction which does not enter into the light receiving element
からのレーザビームを記録面に収束する対物レンズを含
む１つの集光光学系、および記録面からの反射光を検出
する受光素子からなり、透明基板の厚みが異なる少なく
とも２種の光情報記録媒体の記録再生用光ピックアップ
のための光学系において、 第１の波長の第１レーザ光源は、薄い透明基板の光情報
記録媒体の記録再生用であり、 第２の波長の第２レーザ光源は、厚い透明基板の光情報
記録媒体の記録再生用であり、 上記光学系は、集光光学系の光束が光軸近傍から外側に
向かって輪帯状に３つの光束に分割される手段を含み、
光軸近傍から外側に向かって順次第１、第２、第３光束
としたとき、第１光束はすべての透明基板の厚みの異な
る記録媒体用であり、第２光束は主に厚い透明基板を有
する記録媒体用、第３光束は主に薄い透明基板を有する
記録媒体用であり、 二つの光源からの光束が共通して通る部分に、 薄い透明基板を有する記録媒体の記録または再生時には
第２光束が第１光束および第３光束が集光する記録面上
の位置近傍には到達しないようにし、 厚い透明基板を有する記録媒体の記録または再生時には
第３光束が第１光束および第２光束が集光する記録面上
の位置近傍には到達しないようにする機能を有する光束
制限手段を有することを特徴とする光ピックアップ装置3. A laser light source having two different wavelengths, one condensing optical system including an objective lens for converging a laser beam from the light source on a recording surface, and a light receiving element detecting reflected light from the recording surface. An optical system for recording / reproducing an optical information recording medium for at least two types of optical information recording media having different transparent substrate thicknesses, wherein the first laser light source of the first wavelength is used for recording / reproducing the optical information recording medium having a thin transparent substrate. The second laser light source of the second wavelength is for recording / reproducing an optical information recording medium having a thick transparent substrate, and the optical system is arranged such that the light flux of the condensing optical system is directed outward from near the optical axis. Including means for splitting into three light beams in an annular shape,
When the first, second, and third light fluxes are sequentially formed outward from the vicinity of the optical axis, the first light flux is for a recording medium having all transparent substrates having different thicknesses, and the second light flux is mainly for a thick transparent substrate. The third light flux is mainly used for a recording medium having a thin transparent substrate, and the third light flux is used for recording or reproduction of a recording medium having a thin transparent substrate in a portion where light beams from two light sources pass commonly. The light beam is prevented from reaching near the position on the recording surface where the first light beam and the third light beam converge, and the third light beam is converted into the first light beam and the second light beam during recording or reproduction on a recording medium having a thick transparent substrate. An optical pickup device comprising a light beam restricting means having a function of preventing light from reaching near a position on a recording surface on which light is condensed.
２の光束を回折し、 第２の波長の第１の光束および第２の光束を透過し、第
３の光束を回折する波長選択性回折格子であることを特
徴とする請求項２の光ピックアップ装置4. The light beam restricting means transmits a first light beam and a third light beam of a first wavelength, diffracts a second light beam, and outputs a first light beam and a second light beam of a second wavelength. 3. The optical pickup device according to claim 2, wherein the optical pickup device is a wavelength-selective diffraction grating that transmits a light beam and diffracts a third light beam.
２の光束を反射し、 第２の波長の第１の光束および第２の光束を透過し、第
３の光束を反射する波長選択性フィルターであることを
特徴とする請求項２の光ピックアップ装置5. The light beam restricting means transmits a first light beam and a third light beam of a first wavelength, reflects a second light beam, and outputs a first light beam and a second light beam of a second wavelength. 3. The optical pickup device according to claim 2, wherein the optical pickup device is a wavelength-selective filter that transmits a light beam and reflects a third light beam.
２の光束を吸収し、 第２の波長の第１の光束および第２の光束を透過し、第
３の光束を吸収する波長選択性フィルターであることを
特徴とする請求項２の光ピックアップ装置6. The light beam restricting means transmits a first light beam and a third light beam of a first wavelength, absorbs a second light beam, and transmits a first light beam and a second light beam of a second wavelength. 3. The optical pickup device according to claim 2, wherein the filter is a wavelength-selective filter that transmits a light beam and absorbs a third light beam.
分において、第１の光源からの光束と第２の光源からの
光束は、互いに偏光方向が直交した直線偏光であり、 第１の波長の第１の光束および第３の光束を透過し、第
２の光束を回折し、 第２の波長の第１の光束および第２の光束を透過し、第
３の光束を回折する偏光ホログラム素子であることを特
徴とする請求項２の光ピックアップ装置7. In a portion where light beams from two light sources pass in common, the light beam from the first light source and the light beam from the second light source are linearly polarized light whose polarization directions are orthogonal to each other. A polarization hologram that transmits a first light beam and a third light beam of a wavelength, diffracts a second light beam, transmits a first light beam and a second light beam of a second wavelength, and diffracts a third light beam 3. The optical pickup device according to claim 2, wherein the optical pickup device is an element.
録再生には略同波長の複数の光ビームが使用されること
を特徴とする請求項１ないし請求項５の何れかの光ピッ
クアップ装置8. The optical pickup device according to claim 1, wherein a plurality of light beams having substantially the same wavelength are used for recording / reproducing at least one optical information recording medium.
ための回折格子が使用されること特徴とする請求項７の
光ピックアップ装置9. The optical pickup device according to claim 7, wherein a diffraction grating for converting a light beam from the light source into a plurality of light beams is used.
２つの波長の異なるレーザ光源を備え、少なくとも一つ
のレーザ光源は光検出器と一体に構成されたレーザ／検
出器集積ユニットであることを特徴とする請求項１ない
し請求項８の何れかの光ピックアップ装置10. The pickup device according to claim 1, further comprising at least two laser light sources having different wavelengths, wherein at least one laser light source is a laser / detector integrated unit integrally formed with a photodetector. An optical pickup device according to any one of claims 1 to 8.
つのレーザ光源を備え、二つのレーザ光源は光検出器と
一体に構成されたレーザ／検出器集積ユニットであるこ
とを特徴とする請求項１ないし請求項８の何れかの光ピ
ックアップ装置11. The pickup according to claim 1, wherein the pickup includes two laser light sources having different wavelengths, and the two laser light sources are a laser / detector integrated unit integrally formed with a photodetector. The optical pickup device according to claim 8.
の光束が共通してとおる部分に配設され、特殊対物レン
ズと一体的に移動可能にユニット化されていることを特
徴とする請求項１ないし請求項１０の何れかの光ピック
アップ装置12. The light beam restricting means is provided at a portion where light beams from two light sources pass through in common, and is unitized so as to be movable integrally with a special objective lens. The optical pickup device according to claim 1.
一体化されていることを特徴とする請求項１ないし請求
項１２の何れかの光ピックアップ装置13. An optical pickup device according to claim 1, wherein said light beam restricting means is integrated with a special objective lens.
を記録面に収束する対物レンズを含む１つの集光光学
系、および記録面からの反射光を検出する受光素子から
なり、透明基板の厚みが異なる少なくとも２種の光情報
記録媒体の記録再生用光ピックアップ装置のための光学
系において、 該光ピックアップ装置はレーザ光の光束を光軸近傍から
外側に向かって輪帯状に３つの光束に分割する手段を含
み、光軸近傍から外側に向かって順次第１、第２、第３
光束としたとき、第１光束はすべての透明基板の厚みの
異なる記録媒体用であり、第２光束は主に厚い透明基板
を有する記録媒体用、第３光束は主に薄い透明基板を有
する記録媒体用である光ピックアップ装置の光路中に配
設される光学素子であって、 薄い透明基板を有する記録媒体の記録あるいは再生の場
合は、第２光束の少なくとも一部に対して、光情報記録
媒体の情報記録面からの反射光は受光素子に受光されな
いようにし、 厚い透明基板を有する記録媒体の記録あるいは再生の場
合は、第３光束の少なくとも一部に対して、光情報記録
媒体の情報記録面からの反射光は受光素子に受光されな
いようにする機能を有することを特徴とする光束制限素
子14. A laser light source, one condensing optical system including an objective lens for converging a laser beam from the light source on a recording surface, and a light receiving element for detecting reflected light from the recording surface, wherein the thickness of the transparent substrate is In an optical system for an optical pickup device for recording and reproducing at least two different types of optical information recording media, the optical pickup device divides a light beam of a laser beam into three light beams in an annular shape from the vicinity of the optical axis to the outside. Means, first, second, third
When the light flux is used, the first light flux is for a recording medium having a thickness of all transparent substrates different from each other, the second light flux is mainly for a recording medium having a thick transparent substrate, and the third light flux is mainly for a recording medium having a thin transparent substrate. An optical element disposed in an optical path of an optical pickup device for a medium, wherein when recording or reproducing a recording medium having a thin transparent substrate, optical information recording is performed on at least a part of the second light flux. The light reflected from the information recording surface of the medium is prevented from being received by the light receiving element, and in the case of recording or reproduction on a recording medium having a thick transparent substrate, at least a part of the third light flux is used as the information of the optical information recording medium. A light beam limiting element having a function of preventing light reflected from a recording surface from being received by a light receiving element.
る２つのレーザ光源を含み、 第１の波長の第１レーザ光源は、薄い透明基板の光情報
記録媒体の記録再生用であり、 第２の波長の第２レーザ光源は、厚い透明基板の光情報
記録媒体の記録再生用であり、 上記光束制限素子は、 薄い透明基板を有する記録媒体の記録または再生時には
第２光束が第１光束および第３光束が集光する記録面上
の位置近傍には到達しないようにし、 厚い透明基板を有する記録媒体の記録または再生時には
第３光束が第１光束および第２光束が集光する記録面上
の位置近傍には到達しないようにする機能を有すること
を特徴とする請求項１４の光束制限素子15. The optical pickup device includes two laser light sources having different wavelengths, wherein the first laser light source of the first wavelength is for recording / reproducing on an optical information recording medium having a thin transparent substrate. The second laser light source is for recording / reproducing an optical information recording medium having a thick transparent substrate, and the light flux limiting element is configured such that when recording or reproducing a recording medium having a thin transparent substrate, the second light beam is a first light beam and a third light beam. The third light flux is prevented from reaching the vicinity of the position on the recording surface where the light flux condenses, and the position on the recording surface where the first light flux and the second light flux are condensed during recording or reproduction of a recording medium having a thick transparent substrate. 15. The light beam restricting element according to claim 14, having a function of preventing the light from reaching the vicinity.
２の光束を回折し、または反射し、あるいは吸収し、 第２の波長の第１の光束および第２の光束を透過し、第
３の光束を回折し、または反射し、あるいは吸収する波
長選択機能を有することを特徴とする請求項１５の光束
制限素子16. The light beam restricting and limiting means transmits a first light beam and a third light beam of a first wavelength, diffracts or reflects or absorbs a second light beam, and transmits the second light beam. 16. The light beam restricting element according to claim 15, further comprising a wavelength selecting function of transmitting the first light beam and the second light beam, and diffracting, reflecting, or absorbing the third light beam.
からのレーザビームを記録面に収束する対物レンズを含
む１つの集光光学系、および記録面からの反射光を検出
する受光素子からなり、透明基板の厚みが異なる少なく
とも２種の光情報記録媒体の記録再生用光ピックアップ
装置のための光学系において、 該光学系の対物レンズはレーザ光の光束を光軸近傍から
外側に向かって輪帯状に３つの光束に分割する手段を含
み、光軸近傍から外側に向かって順次第１、第２、第３
光束としたとき、第１光束はすべての透明基板の厚みの
異なる記録媒体用であり、第２光束は主に厚い透明基板
を有する記録媒体用、第３光束は主に薄い透明基板を有
する記録媒体用であり、 該分割手段の第２光束の少なくとも一部に対して、波長
の異なる２つのレーザ光のうち長い波長のレーザ光は光
情報記録媒体の情報記録面からの反射光を検出する受光
素子に受光され、短い波長のレーザ光は受光素子に受光
されないようにし、 該分割手段の第３光束の少なくとも一部に対して、波長
の異なる２つのレーザ光のうち短い波長のレーザ光は光
情報記録媒体の情報記録面からの反射光を検出する受光
素子に受光され、長い波長のレーザ光は受光素子に受光
されないようにする機能を有する光束制限機能（波長選
択機能）を持たせたことを特徴とする光ピックアップ用
対物レンズ17. A laser light source having two different wavelengths, one condensing optical system including an objective lens for converging a laser beam from the light source on a recording surface, and a light receiving element for detecting reflected light from the recording surface, In an optical system for an optical pickup device for recording and reproducing at least two types of optical information recording media having different thicknesses of a transparent substrate, an objective lens of the optical system directs a light beam of a laser beam from an area near an optical axis to an outer side. Means for splitting the light into three light beams, and the first, second, and third light beams are sequentially turned from the vicinity of the optical axis to the outside.
When the light flux is used, the first light flux is for a recording medium having a thickness of all transparent substrates different from each other, the second light flux is mainly for a recording medium having a thick transparent substrate, and the third light flux is mainly for a recording medium having a thin transparent substrate. For a medium, for at least a part of the second light flux of the splitting unit, a laser beam having a longer wavelength among two laser beams having different wavelengths detects reflected light from an information recording surface of an optical information recording medium. The short-wavelength laser light received by the light-receiving element is prevented from being received by the light-receiving element. At least a part of the third light beam of the splitting means, the short-wavelength laser light of the two laser lights having different wavelengths is A light beam limiting function (wavelength selecting function) having a function of preventing a long wavelength laser beam from being received by a light receiving element for detecting reflected light from an information recording surface of an optical information recording medium and preventing a long wavelength laser light from being received by the light receiving element. That The optical pick-up for the objective lens to the symptoms
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25989699A JP2001084632A (en) | 1999-09-14 | 1999-09-14 | Optical pickup device, wavelength selective optical element and objective lens |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25989699A JP2001084632A (en) | 1999-09-14 | 1999-09-14 | Optical pickup device, wavelength selective optical element and objective lens |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2001084632A true JP2001084632A (en) | 2001-03-30 |
Family
ID=17340452
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP25989699A Withdrawn JP2001084632A (en) | 1999-09-14 | 1999-09-14 | Optical pickup device, wavelength selective optical element and objective lens |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2001084632A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002334468A (en) * | 2001-05-08 | 2002-11-22 | Konica Corp | Optical pickup device and objective lens for it |
| JP2003322793A (en) * | 2002-05-08 | 2003-11-14 | Pentax Corp | Objective lens for optical head |
| CN1296746C (en) * | 2001-04-12 | 2007-01-24 | 柯尼卡株式会社 | Objective lens, optical pickup device and information recording regeneration method |
| US7596071B2 (en) | 2003-06-30 | 2009-09-29 | Ricoh Company, Ltd. | Objective lens, optical pickup, and optical information processing apparatus using the same |
-
1999
- 1999-09-14 JP JP25989699A patent/JP2001084632A/en not_active Withdrawn
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1296746C (en) * | 2001-04-12 | 2007-01-24 | 柯尼卡株式会社 | Objective lens, optical pickup device and information recording regeneration method |
| JP2002334468A (en) * | 2001-05-08 | 2002-11-22 | Konica Corp | Optical pickup device and objective lens for it |
| JP4590776B2 (en) * | 2001-05-08 | 2010-12-01 | コニカミノルタホールディングス株式会社 | Optical pickup device and objective lens for optical pickup device |
| JP2003322793A (en) * | 2002-05-08 | 2003-11-14 | Pentax Corp | Objective lens for optical head |
| US7596071B2 (en) | 2003-06-30 | 2009-09-29 | Ricoh Company, Ltd. | Objective lens, optical pickup, and optical information processing apparatus using the same |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A300 | Withdrawal of application because of no request for examination |
Free format text: JAPANESE INTERMEDIATE CODE: A300 Effective date: 20061205 |