JPH01179245A - Magneto-optical head - Google Patents
Magneto-optical headInfo
- Publication number
- JPH01179245A JPH01179245A JP33543787A JP33543787A JPH01179245A JP H01179245 A JPH01179245 A JP H01179245A JP 33543787 A JP33543787 A JP 33543787A JP 33543787 A JP33543787 A JP 33543787A JP H01179245 A JPH01179245 A JP H01179245A
- Authority
- JP
- Japan
- Prior art keywords
- light
- optical
- detection
- magneto
- recording medium
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 230000003287 optical effect Effects 0.000 claims abstract description 28
- 230000005415 magnetization Effects 0.000 claims description 4
- 230000010287 polarization Effects 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims 1
- 238000001514 detection method Methods 0.000 abstract description 31
- 230000000694 effects Effects 0.000 abstract description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 206010041662 Splinter Diseases 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
Classifications
-
- 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
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は光学手段と磁気的手段を併用して記録、再生、
消去を行う光磁気記録において記録媒体面上にレーザ光
を照射するとともに１反射光を受光し信号検出を行う光
磁気ヘッドに関する。[Detailed Description of the Invention] [Industrial Application Field] The present invention uses both optical means and magnetic means to record, reproduce, and
The present invention relates to a magneto-optical head that irradiates a laser beam onto the surface of a recording medium and receives one reflected beam to detect a signal in magneto-optical recording for erasing.
従来、光磁気ヘッドは記録媒体面からの反射光からハー
フミラ−等のビームスプリッタで一部を分離し、この分
離光を用いてサーボエラー信号を検出し、焦点合せ動作
、トラック追従動作に使用するとともに、残りの光をλ
／２板を介した後さらに偏光ビームスプリッタにより２
分割し、この２分割した光を各々光検出器にて受光し、
この２つの光検出器の差を取ることにより記録信号の再
生を行っていた。Conventionally, magneto-optical heads separate a portion of the light reflected from the surface of the recording medium using a beam splitter such as a half mirror, and use this separated light to detect a servo error signal and use it for focusing and track following operations. and the remaining light is λ
After passing through the /2 plate, the polarizing beam splitter
The light is divided into two parts, each of which is received by a photodetector,
Recorded signals were reproduced by taking the difference between these two photodetectors.
しかし、この従来の光磁気ヘッドは、２つの信号検出用
光検出器と、１以上のサーボエラー検出用光検出器とを
必要とし、ヘッド構成が複雑かつ大型化するという欠点
があった。またわずかな偏光面の向きの変化を検出して
信号を読み出すため、できるだけ多くの光景を信号検出
用に用いる必要があるにもかかわらず、サーボエラー検
出用に一部の光を分離しで用いていたため、信号検出用
の光量が低下し検出信号のＣ／Ｎを劣化させる要因とも
なっていた。However, this conventional magneto-optical head requires two photodetectors for signal detection and one or more photodetectors for servo error detection, which has the drawback of making the head configuration complicated and large. In addition, in order to read signals by detecting slight changes in the direction of the polarization plane, it is necessary to use as many sights as possible for signal detection, but some light is separated and used for servo error detection. As a result, the amount of light for signal detection decreases, which causes deterioration of the C/N of the detection signal.
本発明の目的は前記問題点を解消し、２組の信号検出用
光検出器と１以上のサーボエラー検出用光検出器を１つ
の光検出器にて兼用しヘッドを簡単かつ小型化するおと
もに、サーボエラー検出用の光を記録信号再生用の信号
検出に利用することにより、記録媒体からの反射光を最
大限記録信号再生に使用し、高いＣ／Ｎの検出信号を得
る光磁気ヘッドを提供することにある。SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and to simplify and downsize the head by using one photodetector as two sets of signal detection photodetectors and one or more servo error detection photodetectors. In both cases, the magneto-optical head uses the light for servo error detection to detect the signal for reproducing the recorded signal, thereby maximizing the use of the reflected light from the recording medium for reproducing the recorded signal, thereby obtaining a detection signal with a high C/N. Our goal is to provide the following.
本発明はレーザからの出射光を記録媒体面上に収束させ
、前記記録媒体の微小部分を加熱するとともに、前記微
小部分にバイアス磁界を印加し、前記微小部分の磁化方
向を任意に反転し、記録もしくは消去を行い、前記微小
部分に照射したレーザ光の反射光の偏光面の前記磁化方
向の違いによる変化を検出し再生を行う光磁気ヘッドに
おいて、収束レンズと、該収束レンズの直前もしくは直
後に配置され、かつ前記記録媒体からの反射光のうちＳ
偏光成分を反射させ、Ｐ偏光成分を透過させる偏光ビー
ムスプリッタと、前記偏光ビームスプリッタの光路分離
面の裏面に微小間隔を置いて概ね前記光路分離面に平行
に配置されビームを放射状に４分割し、互いに微小に異
なる角度を与えてビームを反射させる放射状に４分割さ
れ互いに微小角ずれて設定された光路分割ミラーと、前
記光路分割ミラーの対角をなす１組のミラーから反射さ
れる２本のサブビ・−ムが２つの２分割光検出部の分割
線上に集光され、残りの対角をなす２本のサブビームが
各々別々の光検出部に集光され、さらに前記偏光ビーム
スプリッタで反射されたＳ偏光成分が別の光検出部に集
光される複数の光検出部を備えた多分割光検出器とを有
することを特徴とする光磁気ヘッドである。The present invention focuses emitted light from a laser onto the surface of a recording medium, heats a minute portion of the recording medium, applies a bias magnetic field to the minute portion, and arbitrarily reverses the magnetization direction of the minute portion, In a magneto-optical head that performs recording or erasing, detects a change in the polarization plane of the reflected light of the laser beam irradiated to the minute portion due to the difference in the magnetization direction, and performs reproduction, a converging lens and a converging lens immediately before or after the converging lens. , and out of the reflected light from the recording medium, S
a polarizing beam splitter that reflects the polarized light component and transmits the P-polarized light component; and a polarizing beam splitter that is arranged approximately parallel to the optical path separating surface at a minute interval on the back side of the optical path separating surface of the polarizing beam splitter and divides the beam into four radially. , an optical path splitting mirror that is radially divided into four parts that reflect the beam at slightly different angles from each other and is set to be offset by a small angle from each other; and two mirrors that are reflected from a pair of mirrors that are diagonal to the optical path splitting mirror. The sub-beams are focused on the dividing line of the two 2-split photodetectors, and the remaining two diagonal sub-beams are focused on separate photodetectors, and then reflected by the polarizing beam splitter. The present invention is a magneto-optical head characterized by having a multi-division photodetector including a plurality of photodetectors in which the S-polarized light component is focused on another photodetector.
以下、本発明について図面を参照にして詳細に説明する
。Hereinafter, the present invention will be explained in detail with reference to the drawings.
第１図は本発明の一実施例を模式的に示す模式図である
。第１図において、１はレーザ、２はコリメータレンズ
、３はビームスプリッタ、６は収束レンズ、７は１／２
波長板、８は偏光ビームスプリッタ、９は光路分離面、
１０は光路分割ミラー、１１は光検出器である、
光磁気ヘッド１００においてレーザ１より発光されたレ
ーザ光はコリメータレンズ２、ビームスプリッタ３、対
物レンズ４を順に経て光磁気ヘッドｔｏ（＋外の記録媒
体５上に入射され、記録、再生、消去に用いられる。記
録媒体５にて反射されたレーザ光は再び光磁気ヘッド１
００内に入射し対物レンズ４を経てビームスプリッタ３
に入射し、ここで記録媒体５への入射光光路から分離さ
れ、収束レンズ６．１／２波長板７を経て偏光ビームス
プリッタ８に入射する。Ｏｉ光ビームスプリッタ８では
、レーザ光のＳ偏光成分は反射され、Ｐ偏光成分は透過
される。透過されたＰ偏光成分は、偏光ビームスプリッ
タ８の光路分離面９の裏側に微小間隔をおいて概ね前記
光路分離面９に平行に配置され、かつ放射状に４分割さ
れ、互いに微小角度ずれて設定された光路分割ミラーｌ
Ｏにて全反射され、放射状に４分割され、互いに微小に
異なる角度を有する一部のサブビームとして再び偏光ビ
ームスプリンタ８を通過して先のＳ偏光成分と概ね同一
方向に導かれる。前記Ｓ偏光成分と、４本のＰ偏光成分
のサブビームは１つの多分割光検出器１１に入射し、多
分割光検出器１１よりサーボエラー信号、記録信号の両
方が検出される。FIG. 1 is a schematic diagram schematically showing an embodiment of the present invention. In Figure 1, 1 is a laser, 2 is a collimator lens, 3 is a beam splitter, 6 is a converging lens, and 7 is 1/2
Wave plate, 8 is a polarizing beam splitter, 9 is an optical path separation surface,
10 is an optical path splitting mirror, and 11 is a photodetector. In the magneto-optical head 100, the laser beam emitted from the laser 1 passes through the collimator lens 2, the beam splitter 3, and the objective lens 4 in this order, and is sent to the magneto-optical head (+). The laser beam is incident on the recording medium 5 and used for recording, reproduction, and erasing.The laser beam reflected by the recording medium 5 is again directed to the magneto-optical head 1.
00 and passes through the objective lens 4 to the beam splitter 3.
The light enters the recording medium 5, is separated from the optical path of the light incident on the recording medium 5, passes through a converging lens 6, a 1/2 wavelength plate 7, and enters a polarizing beam splitter 8. In the Oi optical beam splitter 8, the S-polarized component of the laser beam is reflected, and the P-polarized component is transmitted. The transmitted P-polarized light component is arranged on the back side of the optical path separating surface 9 of the polarizing beam splitter 8 at a small interval and approximately parallel to the optical path separating surface 9, and is divided radially into four parts, which are set to be offset by a small angle from each other. optical path splitting mirror l
The light beam is totally reflected at the polarizing beam splitter 8 and is radially divided into four parts, which pass through the polarizing beam splinter 8 again as some sub-beams having slightly different angles from each other, and are guided in approximately the same direction as the previous S-polarized light component. The S-polarized component and the four P-polarized component sub-beams enter one multi-division photodetector 11, and both the servo error signal and the recording signal are detected by the multi-division photodetector 11.
第２図は多分割光検出器１１上の各検出部と入射ビーム
との関係の一例を模式的に示す図である。FIG. 2 is a diagram schematically showing an example of the relationship between each detection section on the multi-division photodetector 11 and an incident beam.
多分割光検出器１１は、２つの２分割光検出部１２゜１
３、及び第１．第２及び第３の光検出部１４，１５．１
６を有し、光路分割ミラー１０の対角をなす１組のミラ
ーから反射される２本のサブビームが２つの２分割光検
出部１２．１３の分割線上に各々導かれ、残りの対角を
なす２本のサブビームが各々第１．第２の光検出部１４
．１５に導かれ、前記Ｓ偏光成分が第３の光検出部１６
に導かれる。２分割光検出部１２゜１３からフォーカス
エラー検出を行う。各サブビームについてミラーの分割
線が形成するエツジ部分の交点が従来のナイフェツジ法
によるフォーカスエラー検出におけるナイフェツジと同
じ働きをし、ナイフェツジ法の原理に基づいて各２分割
光検出器においてフォーカスエラーが検出される。どち
らか一方の検出器のみを用いてフォーカスエラーを検出
することもできるが１本実施例の如く、２つの２分割検
出器を用いることにより、より精度良くフォーカスエラ
ーを検出することができる。The multi-division photodetector 11 includes two two-division photodetector sections 12゜1.
3, and 1st. Second and third photodetector 14, 15.1
6, and the two sub-beams reflected from a pair of diagonal mirrors of the optical path splitting mirror 10 are respectively guided onto the dividing line of the two two-split light detectors 12 and 13, and the remaining diagonals are The two sub-beams formed are the first and second sub-beams. Second photodetector 14
．． 15, and the S-polarized light component is guided to a third photodetector 16.
guided by. Focus error detection is performed from the two-split light detection unit 12°13. The intersection point of the edge portion formed by the mirror dividing line for each sub-beam functions in the same way as the knife in focus error detection using the conventional knife, and focus errors are detected in each two-split photodetector based on the principle of the knife. Ru. Although it is possible to detect focus errors using only one of the detectors, by using two two-split detectors as in this embodiment, focus errors can be detected with higher accuracy.
また、第１及び第２の光検出部１４．１５の出力の差を
取ることによりトランクエラーの検出を行う。Furthermore, a trunk error is detected by taking the difference between the outputs of the first and second photodetectors 14, 15.
フォーカスエラー検出と同様に各サブビームについてミ
ラーの分割線が形成するエツジ部分の交点が従来のプッ
シュプル法によるトラックエラー検出における２分割セ
ンサの分割線と同じ働きをし、プッシュプル法の原理に
基づいてトラックエラーが検出される。検出部はニアフ
ィールド近辺にあるが、光路分割をファーフィールドに
て行っているため、プッシュプル法を実現することがで
きる。Similar to focus error detection, the intersection of the edge portions formed by the mirror dividing line for each sub-beam functions in the same way as the dividing line of the two-split sensor in tracking error detection using the conventional push-pull method, and is based on the principle of the push-pull method. track error is detected. Although the detection section is located near the near field, the optical path division is performed in the far field, making it possible to implement the push-pull method.
さらに２つの２分割光検出部１２．１３及び第１．第２
の光検出部１４．１５の出力の和と、第３の光検出部１
６の出力との差を取ることにより記録信号を検出するこ
とができる。２分割光検出部１２．１３及び第１．第２
の光検出部１４．１５の出力の和は全てのＰ偏光成分の
大きさに相当し、第３の光検出部１６の出力のＳ偏光成
分の大きさとの差を取れば、従来の光磁気記録における
再生方法におけるのと全く・同様にこれが記録媒体５上
のビームが照射されている部分のカー回転角に対応した
値となるためである。以上の構成により１つの光検出器
を用いることにより、フォーカスエラー、トラッキング
エラーのサーボエラー信号の検出と記録信号検出の両方
を行うことができるとともに、光学部品点数も少なくて
済み、ヘッドの小型簡単化が図れる。Furthermore, two two-part light detection sections 12.13 and the first. Second
The sum of the outputs of the photodetectors 14 and 15 and the third photodetector 1
The recorded signal can be detected by taking the difference from the output of No. 6. The two-split light detection section 12.13 and the first. Second
The sum of the outputs of the photodetectors 14 and 15 corresponds to the size of all the P-polarized light components, and if the difference from the size of the S-polarized light component of the output of the third photodetector 16 is taken, the conventional magneto-optical This is because, just as in the reproduction method for recording, this value corresponds to the Kerr rotation angle of the portion of the recording medium 5 that is irradiated with the beam. With the above configuration, by using one photodetector, it is possible to detect both servo error signals such as focus errors and tracking errors, and to detect recording signals, and the number of optical components is also reduced, making it possible to make the head smaller and easier. can be achieved.
さらにサーボエラー信号検出のために記録信号検出用の
ビームからビームを分離して使用する必要がないため、
光の利用効率が上がり、再生信号のＣ／Ｎ比の増加に役
立つ利点もある。Furthermore, since there is no need to separate the beam from the recording signal detection beam for servo error signal detection,
This also has the advantage of increasing the efficiency of light use and helping to increase the C/N ratio of reproduced signals.
以上説明したように本発明の光磁気ヘッドによれば、サ
ーボエラー信号、記録信号の検出が１つの光検出器にて
行うことができ、光学部品点数も少なく、かつ光の利用
効率が高く、高い信号Ｃ／Ｎ比が得られる小型で簡単な
構成の光磁気ヘッドを実現できる効果がある。As explained above, according to the magneto-optical head of the present invention, a servo error signal and a recording signal can be detected with one photodetector, the number of optical components is small, and the light usage efficiency is high. This has the effect of realizing a small and simple magneto-optical head that provides a high signal C/N ratio.
第１図は本発明の一実施例を模式的に示す構成図、第２
図は第１図の多分割光検出器上の各検出部と入射ビーム
との関係を模式的に示す図である。
１・・・レーザ ２・・・コリメータレン
ズ３・・・ビームスプリッタ ４・・・対物レンズ５
・・・記録媒体 ６・・・収束レンズ７・・・
ｌ／２波長板 ８・・・偏光ビームスプリッタ９・
・・光路分離面 １０・・・光路分割ミラーｌ！
・・・光検出器 １２．１３・・・２分割光検
出部１４・・・第１の光検出部 １５・・・第２の光
検出部Ｉ６・・・第３の光検出部
特許出願人 １−１本電気株式会社
代 理 人 弁理士 菅 野 中 ゛・、、
＋
５記健鼻伜
第１図
第２図FIG. 1 is a configuration diagram schematically showing an embodiment of the present invention, and FIG.
The figure is a diagram schematically showing the relationship between each detection section on the multi-division photodetector of FIG. 1 and an incident beam. 1...Laser 2...Collimator lens 3...Beam splitter 4...Objective lens 5
...Recording medium 6...Convergent lens 7...
l/2 wavelength plate 8...Polarizing beam splitter 9...
... Optical path splitting surface 10... Optical path splitting mirror l!
...Photodetector 12.13...Two-split photodetector 14...First photodetector 15...Second photodetector I6...Third photodetector Patent applicant 1-1 Representative of Hondenki Co., Ltd. Patent attorney Naka Kanno ゛...
+ 5Kenhana 1 Figure 2
Claims (1)
前記記録媒体の微小部分を加熱するとともに、前記微小
部分にバイアス磁界を印加し、前記微小部分の磁化方向
を任意に反転し、記録もしくは消去を行い、前記微小部
分に照射したレーザ光の反射光の偏光面の前記磁化方向
の違いによる変化を検出し再生を行う光磁気ヘッドにお
いて、収束レンズと、該収束レンズの直前もしくは直後
に配置され、かつ前記記録媒体からの反射光のうちＳ偏
光成分を反射させ、Ｐ偏光成分を透過させる偏光ビーム
スプリッタと、前記偏光ビームスプリッタの光路分離面
の裏面に微小間隔を置いて概ね前記光路分離面に平行に
配置されビームを放射状に４分割し、互いに微小に異な
る角度を与えてビームを反射させる放射状に４分割され
互いに微小角ずれて設定された光路分割ミラーと、前記
光路分割ミラーの対角をなす１組のミラーから反射され
る２本のサブビームが２つの２分割光検出部の分割線上
に集光され、残りの対角をなす２本のサブビームが各々
別々の光検出部に集光され、さらに前記偏光ビームスプ
リッタで反射されたＳ偏光成分が別の光検出部に集光さ
れる複数の光検出部を備えた多分割光検出器とを有する
ことを特徴とする光磁気ヘッド。(1) Converge the emitted light from the laser onto the recording medium surface,
While heating the minute portion of the recording medium, applying a bias magnetic field to the minute portion, arbitrarily reversing the magnetization direction of the minute portion, recording or erasing, and reflecting light of the laser beam irradiated to the minute portion. A magneto-optical head that performs reproduction by detecting a change in the polarization plane due to the difference in the magnetization direction includes a converging lens and an S-polarized component of light reflected from the recording medium, which is disposed immediately before or after the converging lens. a polarizing beam splitter that reflects the P-polarized light component and transmits the P-polarized light component; An optical path splitting mirror that reflects the beam at slightly different angles and is divided into four parts radially and set apart from each other by a small angle, and two sub-beams that are reflected from a pair of mirrors that are diagonal to the optical path splitting mirror. is focused on the dividing line of the two two-split photodetectors, the remaining two diagonal sub-beams are focused on separate photodetectors, and the S-polarized component reflected by the polarization beam splitter. 1. A magneto-optical head comprising: a multi-division photodetector having a plurality of photodetectors whose light is focused on another photodetector.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP33543787A JPH01179245A (en) | 1987-12-28 | 1987-12-28 | Magneto-optical head |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP33543787A JPH01179245A (en) | 1987-12-28 | 1987-12-28 | Magneto-optical head |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH01179245A true JPH01179245A (en) | 1989-07-17 |
Family
ID=18288552
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP33543787A Pending JPH01179245A (en) | 1987-12-28 | 1987-12-28 | Magneto-optical head |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH01179245A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0273531A (en) * | 1988-09-09 | 1990-03-13 | Matsushita Electric Ind Co Ltd | Magneto-optical recording and reproducing device |
-
1987
- 1987-12-28 JP JP33543787A patent/JPH01179245A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0273531A (en) * | 1988-09-09 | 1990-03-13 | Matsushita Electric Ind Co Ltd | Magneto-optical recording and reproducing device |
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