JP2636245B2 - Optical head for magneto-optical storage - Google Patents
Optical head for magneto-optical storageInfo
- Publication number
- JP2636245B2 JP2636245B2 JP62169461A JP16946187A JP2636245B2 JP 2636245 B2 JP2636245 B2 JP 2636245B2 JP 62169461 A JP62169461 A JP 62169461A JP 16946187 A JP16946187 A JP 16946187A JP 2636245 B2 JP2636245 B2 JP 2636245B2
- Authority
- JP
- Japan
- Prior art keywords
- magneto
- optical
- light
- optical storage
- photoelectric conversion
- 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.)
- Expired - Fee Related
Links
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B11/00—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor
- G11B11/10—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field
- G11B11/105—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field using a beam of light or a magnetic field for recording by change of magnetisation and a beam of light for reproducing, i.e. magneto-optical, e.g. light-induced thermomagnetic recording, spin magnetisation recording, Kerr or Faraday effect reproducing
- G11B11/10532—Heads
- G11B11/10541—Heads for reproducing
- G11B11/10543—Heads for reproducing using optical beam of radiation
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
- G11B7/09—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
- G11B7/0908—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for focusing only
- G11B7/0909—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for focusing only by astigmatic methods
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
- G11B7/09—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
- G11B7/0908—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for focusing only
- G11B7/0912—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for focusing only by push-pull method
Landscapes
- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Optical Head (AREA)
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、光磁気記憶の分野における光磁気記憶用光
ヘッドに関する。The present invention relates to an optical head for magneto-optical storage in the field of magneto-optical storage.
従来の光磁気記憶用ヘッドは、第６図に示すごとく半
導体レーザ601からの発散光を集束光学系602により光磁
気記憶媒体603上に集束し、反射光をビームスプリッタ6
04により取り出し、凸レンズ606、シリンドリカルレン
ズ607、４分割フォトダイオード608を用いて非点収差法
によるフォーカスエラー信号、ウォブリングピットによ
るトラックエラー信号を得、さらにビームスプリッタ60
5により光束を分離して、1/2波長板609、偏光ビームス
プリッタ610、凸レンズ611及び612、フォトダイオード6
13及び614を用いて光磁気信号を得るものであった。As shown in FIG. 6, a conventional magneto-optical storage head focuses divergent light from a semiconductor laser 601 on a magneto-optical storage medium 603 by means of a focusing optical system 602, and reflects reflected light into a beam splitter 6.
04, a convex lens 606, a cylindrical lens 607, and a four-division photodiode 608 are used to obtain a focus error signal by an astigmatism method, a track error signal by a wobbling pit, and a beam splitter 60.
The light beam is separated by 5, the half-wave plate 609, the polarizing beam splitter 610, the convex lenses 611 and 612, the photodiode 6
13 and 614 were used to obtain a magneto-optical signal.
しかしながら、前述の従来技術では発光部と受光部の
位置が大きさ隔たっており、ビームスプリッタ、複数の
レンズが必要であって、光ヘッドが大型になってしまう
という問題点を有している。However, in the above-described conventional technology, the positions of the light emitting unit and the light receiving unit are separated from each other by a large size, and a beam splitter and a plurality of lenses are required, which causes a problem that the optical head becomes large.
そこで本発明はこのような問題点を解決するものであ
り、その目的とするところは、最小限の素子を使用し
て、簡単な光学系を実現し小型な光磁気記憶用光ヘッド
を提供するところにある。Therefore, the present invention is to solve such a problem, and an object of the present invention is to provide a small-sized optical head for magneto-optical storage by realizing a simple optical system using a minimum number of elements. There.
本発明の光磁気用光ヘッドは、 点光源と、 該点光源からの発散光を光磁気記憶媒体に集束する集
束光学系と、 前記光磁気記憶媒体からの反射光を回折手段の同一領
域から発生する少なくともプラス１次光とマイナス１次
とに分割する前記回折手段と、 前記プラス１次光と前記マイナス１次光とをそれぞれ
受光する二つの光電変換素子と、 二つの前記光電変換素子の前方にそれぞれ配置した検
光子と、を有し、 前記回折手段を前記点光源と前記光磁気記憶媒体との
間の光路中に配置し、 二つの前記光電変換素子の出力の差信号から光磁気信
号を得ることを特徴とする。An optical head for magneto-optics according to the present invention includes: a point light source; a focusing optical system that focuses divergent light from the point light source on a magneto-optical storage medium; and reflected light from the magneto-optical storage medium from the same area of a diffraction unit. The diffracting means for splitting at least the generated plus first-order light and minus first-order light, two photoelectric conversion elements respectively receiving the plus first-order light and the minus first-order light, and two photoelectric conversion elements. An analyzer arranged in front of each other, the diffraction means being arranged in an optical path between the point light source and the magneto-optical storage medium, and a magneto-optical device based on a difference signal between outputs of the two photoelectric conversion elements. It is characterized by obtaining a signal.
第１図に、本発明の光磁気記憶用光ヘッドを示す。 FIG. 1 shows an optical head for magneto-optical storage according to the present invention.
点光源101からの発散光は集束光学系102により光磁気
記憶媒体103上に集束される。光磁気記憶媒体103からの
反射光は、再び集束光学系102を介して、光束を二分割
する機能を有するホログラフィック素子104等からなる
回折手段にいたる。分割された光束は検光子105及び106
を介して光電変換素子107及び108にいたり、サーボ信号
及び光磁気信号が得られる。The divergent light from the point light source 101 is focused on the magneto-optical storage medium 103 by the focusing optical system 102. The reflected light from the magneto-optical storage medium 103 passes through the focusing optical system 102 again and reaches a diffraction unit including a holographic element 104 having a function of dividing the light beam into two. The split light beams are analyzed by analyzers 105 and 106.
And servo signals and magneto-optical signals can be obtained.
この光磁気信号の検出方法に関しては、本発明者が最
近「光ヘッド」として特許出願を行なっている。The present inventor has recently filed a patent application for a method of detecting this magneto-optical signal as an “optical head”.
また本発明に利用可能なサーボ信号の検出方法に関し
ても、本発明者が最近「光記憶再生装置」として特許出
願を行なっている。In addition, the present inventor has recently filed a patent application as an “optical storage / reproducing device” for a servo signal detection method that can be used in the present invention.
第２図は、本発明の実施例である。 FIG. 2 shows an embodiment of the present invention.
半導体レーザ201を出射し、コリメータレンズ202によ
り平行光となった光束は、対物レンズ203により集束さ
れ、光磁気記憶媒体204上に光スポットを形成する。光
磁気記憶媒体204により反射された光は再び、対物レン
ズ203を介してホログラフィック素子205にいたる。ホロ
グラフィック素子205は、格子間隔が一端から他端にか
けて連続的に減少する不等ピッチグレーティングであ
る。これにより±１次回折光の一方は凸シリンドリカル
レンズ、他方は凹シリンドカルレンズを使用したもに相
当する、非点収差を発生する。ホログラフィック素子20
5により二つに分割された光は、再びコリメータレンズ2
02により集光され、偏光板206、207により検光され、フ
ォトダイオード208及び209にいたる。The light beam emitted from the semiconductor laser 201 and converted into parallel light by the collimator lens 202 is focused by the objective lens 203 to form a light spot on the magneto-optical storage medium 204. The light reflected by the magneto-optical storage medium 204 reaches the holographic element 205 via the objective lens 203 again. The holographic element 205 is an unequal-pitch grating in which the lattice spacing decreases continuously from one end to the other end. As a result, astigmatism is generated, which corresponds to the case where one of the ± 1st-order diffracted lights uses a convex cylindrical lens and the other uses a concave cylindrical lens. Holographic element 20
The light split into two by 5 is returned to the collimator lens 2 again.
The light is condensed by 02, is analyzed by the polarizing plates 206 and 207, and reaches the photodiodes 208 and 209.
第３図に本実施例に使用した半導体レーザ301、フォ
トダイオード302及び303、偏光板304及び305よりなる複
合素子を示す。第３図の矢印308は半導体レーザの偏光
方向、矢印309及び310は偏光板の偏光軸の方向を示す。
また、306、307はフォトダイオード上の光スポットを示
す。FIG. 3 shows a composite device including a semiconductor laser 301, photodiodes 302 and 303, and polarizing plates 304 and 305 used in this embodiment. Arrow 308 in FIG. 3 indicates the polarization direction of the semiconductor laser, and arrows 309 and 310 indicate the direction of the polarization axis of the polarizing plate.
Reference numerals 306 and 307 denote light spots on the photodiode.
二つのフォトダイオードの差信号の低周波成分よりフ
ォーカスエラー信号を得る。また高周波成分より光磁気
信号を選る。さらに、二つのフォトダイオードの和信号
により、プリピット信号及びウォブリングピットによる
トラックエラー信号を得る。上記の信号検出方法は、前
出の本発明者による出願「光記憶再生装置」に詳しい。A focus error signal is obtained from a low frequency component of a difference signal between the two photodiodes. Also, a magneto-optical signal is selected from the high frequency component. Further, a track error signal due to a pre-pit signal and a wobbling pit is obtained from the sum signal of the two photodiodes. The above signal detection method is described in detail in the above-mentioned application "optical storage and reproduction apparatus" by the present inventor.
第４図は本発明の他の実施例であって反射型のホログ
ラフィック素子404を用いた例である。これは、光路を
曲げて光ヘッドを薄型にする機能もかねている。FIG. 4 shows another embodiment of the present invention, in which a reflective holographic element 404 is used. This also has the function of bending the optical path to make the optical head thinner.
第５図に、この実施例に使用した複合素子を示す。50
2は４分割フォトダイオードであってこれにより、フォ
ーカスエラー信号を得る。FIG. 5 shows a composite device used in this example. 50
Reference numeral 2 denotes a four-division photodiode for obtaining a focus error signal.
光磁気信号は、４分割フォトダイオード502の全和信
号と、フォトダイオード503の信号の差信号により得
る。The magneto-optical signal is obtained by the difference signal between the sum signal of the four-division photodiode 502 and the signal of the photodiode 503.
以上述べたように本発明によれば、ビームスプリッタ
を省略でき、また凸レンズを減らすこともできるため、
点光源、集束光学系、回折手段、検光子、光電変換素子
という必要最小限の素子により小型の光磁気記憶用光ヘ
ッドを実現できる。As described above, according to the present invention, the beam splitter can be omitted and the number of convex lenses can be reduced.
A small optical head for magneto-optical storage can be realized by the minimum necessary elements such as a point light source, a focusing optical system, a diffraction means, an analyzer, and a photoelectric conversion element.
また、ホログラフィック素子や回折格子等の回折手段
の同一領域から発生した二つの回折光をそれぞれ検光子
を介して光電変換素子で受光して差信号をとる構成とし
ているので、回折格子の面上にごみ等が付着したり傷が
付いたりしても二つの回折光の強度に対して同様の影響
しか現れないため差信号をとったときにその影響が除去
される。したがって、回折手段上のごみや傷の影響を受
けない良好な光磁気信号を再生することができるという
効果がある。特に、回折格子等を用いた小型光ヘッドに
とって、これらの悪影響を除去できるということは信頼
性、量産性の点で非常に有益である。In addition, since two diffracted lights generated from the same area of the diffraction means such as a holographic element and a diffraction grating are each received by a photoelectric conversion element via an analyzer and a difference signal is obtained, a difference signal is obtained. Even if dust or the like adheres or is scratched, only the same effect appears on the intensities of the two diffracted lights, so the effect is removed when a difference signal is obtained. Therefore, there is an effect that a good magneto-optical signal which is not affected by dust and scratches on the diffraction means can be reproduced. In particular, for a small-sized optical head using a diffraction grating or the like, the fact that these adverse effects can be eliminated is very useful in terms of reliability and mass productivity.
第１図は、本発明の光磁気記憶用光ヘッドの構成図。 第２図は、本発明の実施例における光磁気記憶用光ヘッ
ドの構成図。 第３図は、本発明の実施例における複合素子の構成図。 第４図は、本発明の他の実施例における光磁気記憶用光
ヘッドの構成図。 第５図は、本発明の他の実施例における複合素子の構成
図。 第６図は、従来例における光磁気記憶用光ヘッドの構成
図。 101、201、301、401、501、601……半導体レーザ 102、602……集束光学系 103、204、403、603……光磁気記憶媒体 104、205、404……ホログラフィック素子 105、106……検光子 107、108……光電変換素子 202……コリメータレンズ 203、402……対物レンズ 206、207、304、305、405、406、504、505……偏光板 208、209、302、303、407、408、503、613、614……フ
ォトダイオード 306、307、506、507……光スポット 308、508……半導体レーザの偏光方向 309、310、509、510……偏光板の偏光軸の方向 502、608……４分割フォトダイオード 604、605……ビームスプリッタ 606、611、612……凸レンズ 607……シリンドリカルレンズ 609……1/2波長板 610……偏光ビームスプリッタFIG. 1 is a configuration diagram of an optical head for magneto-optical storage according to the present invention. FIG. 2 is a configuration diagram of an optical head for magneto-optical storage according to an embodiment of the present invention. FIG. 3 is a configuration diagram of a composite device according to an embodiment of the present invention. FIG. 4 is a configuration diagram of an optical head for magneto-optical storage according to another embodiment of the present invention. FIG. 5 is a configuration diagram of a composite device according to another embodiment of the present invention. FIG. 6 is a configuration diagram of an optical head for magneto-optical storage in a conventional example. 101, 201, 301, 401, 501, 601 Semiconductor lasers 102, 602 Focusing optical systems 103, 204, 403, 603 Magneto-optical storage media 104, 205, 404 Holographic elements 105, 106 … Analyzer 107, 108… Photoelectric conversion element 202… Collimator lens 203, 402… Objective lens 206, 207, 304, 305, 405, 406, 504, 505… Polarizing plate 208, 209, 302, 303, 407, 408, 503, 613, 614 ... Photodiodes 306, 307, 506, 507 ... Light spots 308, 508 ... Polarization direction of semiconductor laser 309, 310, 509, 510 ... Polarization axis direction of polarizing plate 502, 608 Four-split photodiode 604, 605 Beam splitter 606, 611, 612 Convex lens 607 Cylindrical lens 609 Half-wave plate 610 Polarizing beam splitter
Claims (1)
光学系と、 前記光磁気記憶媒体からの反射光を回折手段の同一領域
から発生する少なくともプラス１次光とマイナス１次と
に分割する前記回折手段と、 前記プラス１次光と前記マイナス１次光とをそれぞれ受
光する二つの光電変換素子と、 二つの前記光電変換素子の前方にそれぞれ配置した検光
子と、を有し、 前記回折手段を前記点光源と前記光磁気記憶媒体との間
の光路中に配置し、 二つの前記光電変換素子の出力の差信号から光磁気信号
を得ることを特徴とする光磁気記憶用光ヘッド。A point light source; a focusing optical system that focuses divergent light from the point light source on a magneto-optical storage medium; and at least plus one that generates reflected light from the magneto-optical storage medium from the same area of the diffraction means. The diffractive means for splitting the light into a secondary light and a minus primary light; two photoelectric conversion elements for receiving the plus primary light and the minus primary light, respectively; and two photoelectric conversion elements disposed in front of the two photoelectric conversion elements, respectively. An analyzer; wherein the diffraction means is disposed in an optical path between the point light source and the magneto-optical storage medium, and a magneto-optical signal is obtained from a difference signal between outputs of the two photoelectric conversion elements. Characteristic optical head for magneto-optical storage.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62169461A JP2636245B2 (en) | 1987-07-07 | 1987-07-07 | Optical head for magneto-optical storage |
| US07/213,813 US4933924A (en) | 1987-07-03 | 1988-06-30 | Optical head and magneto-optical read/write device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62169461A JP2636245B2 (en) | 1987-07-07 | 1987-07-07 | Optical head for magneto-optical storage |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6413246A JPS6413246A (en) | 1989-01-18 |
| JP2636245B2 true JP2636245B2 (en) | 1997-07-30 |
Family
ID=15887006
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62169461A Expired - Fee Related JP2636245B2 (en) | 1987-07-03 | 1987-07-07 | Optical head for magneto-optical storage |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2636245B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5272550A (en) * | 1991-10-11 | 1993-12-21 | International Business Machines Corporation | Hologram system |
| US5212572A (en) * | 1991-11-22 | 1993-05-18 | International Business Machines Corporation | Optical data storage system with compact holographic polarization-sensing or reflectivity-sensing optical storage head |
| US5331445A (en) * | 1992-08-18 | 1994-07-19 | International Business Machines Corporation | Increased Bragg angle sensitivity hologram system and method |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62103857A (en) * | 1985-10-31 | 1987-05-14 | Mitsubishi Electric Corp | Optical pickup device |
-
1987
- 1987-07-07 JP JP62169461A patent/JP2636245B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6413246A (en) | 1989-01-18 |
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| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |