JPH04182952A - Optical information producing device - Google Patents
Optical information producing deviceInfo
- Publication number
- JPH04182952A JPH04182952A JP31068290A JP31068290A JPH04182952A JP H04182952 A JPH04182952 A JP H04182952A JP 31068290 A JP31068290 A JP 31068290A JP 31068290 A JP31068290 A JP 31068290A JP H04182952 A JPH04182952 A JP H04182952A
- Authority
- JP
- Japan
- Prior art keywords
- light
- information
- region
- optical
- 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.)
- Pending
Links
- 230000003287 optical effect Effects 0.000 title claims abstract description 51
- 230000010287 polarization Effects 0.000 claims abstract description 28
- 230000004907 flux Effects 0.000 claims abstract description 18
- 230000005381 magnetic domain Effects 0.000 claims abstract description 13
- 238000006243 chemical reaction Methods 0.000 claims description 29
- 238000003384 imaging method Methods 0.000 claims description 15
- 210000001747 pupil Anatomy 0.000 claims description 11
- 239000004065 semiconductor Substances 0.000 claims description 7
- 238000001514 detection method Methods 0.000 claims description 5
- 230000005374 Kerr effect Effects 0.000 abstract description 5
- 230000005540 biological transmission Effects 0.000 abstract 3
- 230000005684 electric field Effects 0.000 description 11
- 238000000034 method Methods 0.000 description 11
- 238000010586 diagram Methods 0.000 description 9
- 230000005415 magnetization Effects 0.000 description 7
- 230000002093 peripheral effect Effects 0.000 description 5
- 238000003708 edge detection Methods 0.000 description 4
- 150000001875 compounds Chemical class 0.000 description 3
- 229920000049 Carbon (fiber) Polymers 0.000 description 1
- 239000004917 carbon fiber Substances 0.000 description 1
- 238000013500 data storage Methods 0.000 description 1
- 239000003989 dielectric material Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 210000003128 head Anatomy 0.000 description 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
- 230000001179 pupillary effect Effects 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は情報を光学的情報記録担体に記録及び／又は再
生する光学的情報記録再生装置に関し、とくに情報記録
担体に記録された情報を磁気光学効果を利用して再生す
る光学ヘッド部分を改良した光学的情報再生装置に関す
るものである。Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an optical information recording/reproducing device for recording and/or reproducing information on an optical information recording carrier, and in particular, it relates to an optical information recording/reproducing device for recording and/or reproducing information on an optical information recording carrier. The present invention relates to an optical information reproducing device that has an improved optical head portion that reproduces information using optical effects.
光学的情報記録再生装置は、記録媒体の大きさに比べて
、データの記憶容量が大きいという特徴があり、コンピ
ュータの外部記憶手段として利用されている。なかでも
光磁気情報記録装置は、データの書換えが可能なことで
有用である。このような記憶手段を用いて情報の記録、
再生を行う方式にはマーク間記録方式、およびマーク長
記録方式（エツジ記録方式）が知られている。後者は前
者に比べてデータ容量を上げ得る点で有利であるとされ
ているが、この方式によって記録された記録媒体から正
確に情報を再生するためには光学ヘッド部分で、情報ビ
ットのエツジ位置を正確に読み取る必要がある。Optical information recording and reproducing devices are characterized by a large data storage capacity compared to the size of the recording medium, and are used as external storage means for computers. Among these, magneto-optical information recording devices are useful because data can be rewritten. Recording information using such storage means,
Known reproduction methods include an inter-mark recording method and a mark length recording method (edge recording method). The latter method is said to be advantageous in that it can increase the data capacity compared to the former method, but in order to accurately reproduce information from a recording medium recorded using this method, the edge position of the information bit must be adjusted in the optical head section. must be read accurately.
通常、光磁気記録媒体用の光学ヘッドにおいては、光源
としての半導体レーザからの光束を対物レンズにより微
小スポットに集光し、このスポット光を用いてマーク間
記録方式でデータの記録を行っており、また、この微小
スポット光の情報ヒツトからの反射光量の変化を差動検
出して情報の再生を行っている。Normally, in an optical head for magneto-optical recording media, a light beam from a semiconductor laser as a light source is focused onto a minute spot using an objective lens, and this spot light is used to record data using the mark-to-mark recording method. Furthermore, information is reproduced by differentially detecting changes in the amount of reflected light from the information hit of this minute spot light.
このような従来の差動検出方式においては、入射直線偏
光の偏光方向と４５度をなす偏光軸方向を有する偏光ビ
ームスプリッタ−を用いて、反射光を２つの信号光に分
解し、この両光束から２つの信号を検出し、これから差
動信号を作り出していた。In such a conventional differential detection method, a polarizing beam splitter whose polarization axis direction is at an angle of 45 degrees with the polarization direction of the incident linearly polarized light is used to separate the reflected light into two signal lights, and these two light beams are split into two signal lights. The two signals were detected and a differential signal was created from them.
このように従来はマーク、長記録方式において、ガウス
分布状の光量分布を有する微小スポット光を投光し、情
報ビットからの反射光の光量変化を差動検出する方式が
使われているが、投光スポット光の光量分布がある広が
りを有するガウス分布であるため、エツジ検出能力が低
いという問題点がある。Conventionally, in mark and long recording methods, a method has been used in which a minute spot light having a Gaussian distribution of light intensity is emitted, and changes in the light intensity of the reflected light from the information bits are differentially detected. Since the light intensity distribution of the projected spot light is a Gaussian distribution with a certain spread, there is a problem that the edge detection ability is low.
このような問題点を解決し、光磁気記録媒体からの少な
い反射光量をより有効に利用するためにさらなる改良が
望まれていた。Further improvements have been desired in order to solve these problems and more effectively utilize the small amount of reflected light from the magneto-optical recording medium.
本発明は上記事情にもとづいてなされたものでマーク長
記録方式を用いた記録された情報ビットからの再生にお
いて、エツジ検出能力が高く光量利用効率の高い小型光
学ヘッドを備えた光学的情報再生装置を提供しようとす
るものである。The present invention has been made based on the above circumstances, and is an optical information reproducing device equipped with a compact optical head that has high edge detection ability and high light intensity utilization efficiency in reproducing information bits recorded using the mark length recording method. This is what we are trying to provide.
このため本発明の光学的情報再生装置では、半導体レー
ザからの直線偏光光束を対物レンズを介して、光磁気記
録媒体から成る情報記録面上においてスポット光となる
ように１つの情報トラック上に投光し、前記スポット光
の反射光束を受光光学系に導き、前記導かれた受光光束
を前記情報トラックの方向にそって第１、第２の２つの
領域に分割し、第１の領域の光束を第１の要素光電変換
光検出器上に結像させ、第２の領域の光束を第２の要素
光電変換光検出器上に結像させる瞳分割光束偏向光学系
に導き、前記要素光電変換光検出器からの出力信号の差
分信号を用いて前記情報記録面に記録された情報磁区の
エツジを検出するようにしている。Therefore, in the optical information reproducing apparatus of the present invention, a linearly polarized light beam from a semiconductor laser is projected onto one information track through an objective lens so as to become a spot light on an information recording surface made of a magneto-optical recording medium. the reflected light beam of the spot light is guided to a light receiving optical system, the guided received light beam is divided into two areas, a first and a second area along the direction of the information track, and the light beam of the first area is is guided to a pupil splitting beam deflection optical system which forms an image on a first elemental photoelectric conversion photodetector, and a beam in a second area is imaged on a second elemental photoelectric conversion photodetector, The edge of the information magnetic domain recorded on the information recording surface is detected using the difference signal of the output signal from the photodetector.
以下図面に従い本発明の光学的情報再生装置を説明する
。The optical information reproducing apparatus of the present invention will be explained below with reference to the drawings.
第１図〜第６図は本発明の第１実施例を説明するための
図である。1 to 6 are diagrams for explaining a first embodiment of the present invention.
第１図は本発明の光学的情報再生装置に用いられる光磁
気記録再生用光ヘッドの概略図である。FIG. 1 is a schematic diagram of an optical head for magneto-optical recording and reproducing used in the optical information reproducing apparatus of the present invention.
同図において、１は波長λ（λ＝８３０ｎｍ、）の直線
偏光（この電界ベクトル方向をＥで示す）を発する半導
体レーザ、２はこの光束を平行光束に変換するコリメー
タレンズ、３はＥ方向の偏光成分はほとんど透過し、こ
れと直交する方向の偏光成分を１００％反射する第１の
偏光ビームスプリッタ−１４は対物レンズである。５は
対物レンズにより結像された投光スポット、６は光磁気
記録媒体である光磁気ディスクに設けられた１つの情報
トラック、７は光スポットのトラッキング用に設けられ
た案内溝である。８はＳ偏光を１００％反射し、ｐ偏光
の一部を反射する第２の偏光ビムスプリッター、９は透
過波面である。１ｏは光束の位相差を調整する位相差調
整光学素子、１１は１／２波長板であり、１２はＳ偏光
を１ｏｏ％反射し、ｐ偏光を１００％透過する第３の偏
光ビームススプリッターであり、１３．１４は各々結像
レンズ、１５．１６は各々２つのプリズムがら成る瞳光
束分割素子、１７．１８は各々１７−１゜１７−２．お
よび１８−１．１８−２から成る２分割光電変換素子で
ある。In the figure, 1 is a semiconductor laser that emits linearly polarized light of wavelength λ (λ = 830 nm, ) (this electric field vector direction is indicated by E), 2 is a collimator lens that converts this light beam into a parallel light beam, and 3 is a collimator lens in the E direction. The first polarizing beam splitter 14, which transmits most of the polarized light components and reflects 100% of the polarized light components in the direction perpendicular to the polarized light components, is an objective lens. 5 is a projected light spot imaged by an objective lens; 6 is one information track provided on a magneto-optical disk which is a magneto-optical recording medium; and 7 is a guide groove provided for tracking the light spot. 8 is a second polarizing beam splitter that reflects 100% of S-polarized light and a portion of P-polarized light; 9 is a transmitted wavefront. 1o is a phase difference adjusting optical element that adjusts the phase difference of the light beam, 11 is a 1/2 wavelength plate, and 12 is a third polarizing beam splitter that reflects 100% of S-polarized light and transmits 100% of P-polarized light. , 13.14 are imaging lenses, 15.16 are pupil beam splitting elements each consisting of two prisms, and 17.18 are 17-1°, 17-2. and 18-1, 18-2.
半導体レーザ１から発した光束は、直線偏光であり、そ
の電界ベクトルの方向は、図中Ｅで示される方向である
。この方向をｐ偏光方向とし、これと直交する方向をＳ
偏光方向とする。この光束はコリメータレンズ２により
平行光束に変換される。この光束は第１の偏光ビームス
プリッタ−３を透過し、対物レンズ４により不図示の光
磁気ディスクの透明基盤を透過し、ＴｂＦｅＣｏなどＣ
つ光磁気記録膜を有する情報トラック６上に光スポット
５として結像される。The light beam emitted from the semiconductor laser 1 is linearly polarized light, and the direction of its electric field vector is the direction indicated by E in the figure. This direction is the p polarization direction, and the direction perpendicular to this is S
Polarization direction. This light beam is converted into a parallel light beam by the collimator lens 2. This light beam passes through the first polarizing beam splitter 3, passes through the transparent substrate of a magneto-optical disk (not shown) through the objective lens 4, and is made of carbon fiber such as TbFeCo.
A light spot 5 is imaged onto an information track 6 having a magneto-optical recording film.
この光磁気記録膜により、磁気カー効果を受けた反射光
束は、Ｅの方向と直交するＳ偏光成分を有し、この偏光
成分は第１の偏光ビームスプリッタ−３により全て反射
され、一方元々のｐ偏光成分はその一部が反射され、第
２の偏光ビームスプリッタ−８に入射する。第２の偏光
ビームスプリッタ−８は、Ｓ偏光成分を１００％反射し
、ｐ偏光成分はその一部を透過するという特性を有する
。したがって、第２の偏光ビームスプリッタ−８を透過
後の光束９は全てｐ偏光成分であり、不図示のオートフ
ォーカス制御用フォーカス検出光学系、オートトラッキ
ング制御用トラッキング検出光学系へと導かれる。これ
ら各検出光学系は従来公知の各種方式を用いる事ができ
る。Due to this magneto-optical recording film, the reflected light beam subjected to the magnetic Kerr effect has an S polarization component perpendicular to the direction of E, and this polarization component is completely reflected by the first polarization beam splitter 3, while the original A part of the p-polarized light component is reflected and enters the second polarization beam splitter 8. The second polarizing beam splitter 8 has a characteristic of reflecting 100% of the S-polarized light component and partially transmitting the P-polarized light component. Therefore, the luminous flux 9 after passing through the second polarizing beam splitter 8 is entirely a p-polarized component, and is guided to a focus detection optical system for autofocus control and a tracking detection optical system for autotracking control (not shown). Various conventionally known systems can be used for each of these detection optical systems.
他方第２の偏光ビームスプリッタ−８により反射された
光束は位相差調整光学素子１０を透過する。この光学素
子は後はど述べる１／２波長板１１を通過した光束とこ
れを通過しない周辺領域部の光束との光路長差によって
発生する位相差をゼロに調整するものである。つまり、
１／２波長板１１の常光線に対する屈折率をｎｏ、厚さ
をｄとし、この位相差調整素子１０の屈折率をｎとする
と、ｎｏ−ｄ＝ｎ−ｄとなるように光学的に等方向な透
明誘電体から成るこの素子の厚みＤを決めればよい。こ
の光学素子通過後の中央部の光束は１／２波長板１１を
透過する。１／２波長板１１はこれを透過するｐ偏光、
Ｓ偏光がその電界ベクトルの角度をなしている。他方周
辺領域部の光束はこの１／２波長板を通らないので偏光
方向は回転されない。１２はこの光束をｐ偏光、Ｓ偏光
に分離するための偏光ビームスプリッタ−であり、ｐ偏
光成分光束は結像レンズ１３、さらに瞳分割プリズム１
５により結像され、プリズム１５−１を透過した光束は
結像面近傍に設けられた２分割光電変換素子１７−１へ
入射し、プリズム１５−２を透過した光束は結像面近傍
に設けられた２分割充電変換素子１７−２へ入射する。On the other hand, the light beam reflected by the second polarizing beam splitter 8 is transmitted through the phase difference adjusting optical element 10. This optical element adjusts to zero the phase difference caused by the optical path length difference between the light beam that has passed through the half-wave plate 11 and the light beam in the peripheral area that does not pass through the half-wave plate 11, which will be described later. In other words,
If the refractive index of the half-wave plate 11 for ordinary rays is no, the thickness is d, and the refractive index of the phase difference adjustment element 10 is n, then it is optically equal so that no-d=nd. What is necessary is to determine the thickness D of this element made of a transparent dielectric material with a certain direction. After passing through this optical element, the central light beam passes through the 1/2 wavelength plate 11. The 1/2 wavelength plate 11 transmits p-polarized light,
S-polarized light forms the angle of the electric field vector. On the other hand, since the light beam in the peripheral region does not pass through this half-wave plate, the polarization direction is not rotated. 12 is a polarizing beam splitter for separating this light beam into p-polarized light and S-polarized light;
The light beam formed by the prism 15-1 and transmitted through the prism 15-1 enters the two-split photoelectric conversion element 17-1 provided near the image-forming surface, and the light flux transmitted through the prism 15-2 enters the two-split photoelectric conversion element 17-1 provided near the image-forming surface. It enters the two-part charging conversion element 17-2.
他方Ｓ偏光成分光束は偏光ビームスプリッタ−１２によ
り反射され、結像レンズ１４、瞳分割プリズム１６によ
り結像され、プリズム１６−１を透過した光束は結像面
近傍に設けられた要素光電変換素子１８〜１へ入射し、
プリズム１６−２を透過した光束は結像面近傍に設けら
れた要素光電変換素子１８−２へ入射する。２分割光電
変換素子１７．１８は情報トラック方向（Ｘ方向）に垂
直な方向（ｙ方向）に分割軸を有している。On the other hand, the S-polarized component light beam is reflected by the polarizing beam splitter 12, and is imaged by the imaging lens 14 and the pupil splitting prism 16, and the light beam transmitted through the prism 16-1 is transferred to an elemental photoelectric conversion element provided near the image forming surface. 18-1,
The light beam that has passed through the prism 16-2 is incident on an elemental photoelectric conversion element 18-2 provided near the imaging plane. The two-split photoelectric conversion elements 17 and 18 have a split axis in a direction (y direction) perpendicular to the information track direction (X direction).
第２図は光磁気記録膜に記録された情報磁区のエツジ上
にスポット光５が入射した場合を示している。FIG. 2 shows the case where the spot light 5 is incident on the edge of the information magnetic domain recorded on the magneto-optical recording film.
入射光束１９上での電界ベクトルの方向は先の第１図の
場合と同じであり、２０で示される。スポット光５が入
射する情報磁区はエツジ２３を境に２１．２２で示され
るように互いにその磁化の方向が異なっている。入射ス
ポット光５の波面の内、磁化２１の影響を受ける領域を
５−１、磁化２２の影響を受ける領域を５−２とする。The direction of the electric field vector on the incident light beam 19 is the same as in FIG. 1 above, and is indicated by 20. The information magnetic domains on which the spot light 5 is incident have different directions of magnetization, as shown by 21 and 22, with the edge 23 as a boundary. In the wavefront of the incident spot light 5, a region affected by the magnetization 21 is designated as 5-1, and a region affected by the magnetization 22 is designated as 5-2.
波面５−１の光は磁化２１による磁気カー効果を受け、
反射光束２４のこの領域に対応する部分の光束２４−１
は、カー回転を受け、その電界ベクトルは２５で示され
る。The light with wavefront 5-1 receives the magnetic Kerr effect due to magnetization 21,
Luminous flux 24-1 of the portion corresponding to this region of reflected luminous flux 24
undergoes Kerr rotation and its electric field vector is denoted by 25.
一方、波面５−２の光は磁化２２による磁気カー効果を
受け、反射光束２４のこの領域に対応する部分の光束２
４−２は、２４−１とは反対方向へ偏光面が回転し、２
６で示されるような電界ベクトルとなる。On the other hand, the light with the wavefront 5-2 is subjected to the magnetic Kerr effect due to the magnetization 22, and the light beam 2 of the portion of the reflected light beam 24 corresponding to this region
4-2 has a polarization plane rotated in the opposite direction to 24-1, and 2
The electric field vector becomes as shown by 6.
この反射光束は対物レンズ４を透過後、第１の偏光ビー
ムスプリッタ−３、第２の偏光ビームスプリッタ−８に
より反射され、位相差調整光学素子１０，１／２波長板
１１に向かう。この１／２波長板通過後の光束内での偏
光成分をみると、第３図に示すようになる。After passing through the objective lens 4, this reflected light beam is reflected by the first polarizing beam splitter 3 and the second polarizing beam splitter 8, and heads toward the phase difference adjusting optical element 10 and the 1/2 wavelength plate 11. If we look at the polarized light components within the light beam after passing through this 1/2 wavelength plate, it becomes as shown in FIG.
第３図は、ｌ／２波長板１１を通過後の光束を第３図の
偏光ビームスプリッタ−１２の手前から見た図であり、
］／２波長板１１を通過した中央部の光束２８．２９内
での偏光方向は各々３２．３３て示され、１／２波長板
１１を通過しない周辺部光束２７．３０の偏光方向３１
．３４と９０度異なっている。FIG. 3 is a view of the light beam after passing through the 1/2 wavelength plate 11, viewed from in front of the polarizing beam splitter 12 in FIG.
]/2 The polarization directions of the central light beams 28 and 29 that have passed through the half-wave plate 11 are shown as 32 and 33, respectively, and the polarization directions of the peripheral light beams 27 and 30 that do not pass through the half-wave plate 11 are shown as 31.
．． 34 and 90 degrees different.
したがって、この光束が第３図の偏光ビームスプリッタ
−１２を透過した後のｐ偏光成分を見ると、第４図に示
すように成る。第４図において、透過光束の中心部２８
．２９、周辺部２７．３０の偏光方向は先の第３図の電
界ベクトルのｐ偏光成分と成り、各々３６．３７、さら
に３５．３８となる。Therefore, when looking at the p-polarized light component after this light flux passes through the polarizing beam splitter 12 shown in FIG. 3, it becomes as shown in FIG. 4. In FIG. 4, the central part 28 of the transmitted light beam
．． 29, and the polarization directions of the peripheral portions 27 and 30 are the p-polarized components of the electric field vector shown in FIG. 3, and are respectively 36.37 and 35.38.
同様にして、第３図の偏光ヒームスプリッター１２を反
射した後のＳ偏光成分を見ると、第５図に示すようにな
る。第５図において、反射光束の中心部２８．２９、周
辺部２７．３０の偏光方向は先の第３図の電界ベクトル
のＳ偏光成分となり４０．４１、さらに３９．４２に示
す電界ベクトルとなる。Similarly, when looking at the S-polarized light component after being reflected by the polarizing heam splitter 12 of FIG. 3, it becomes as shown in FIG. 5. In Fig. 5, the polarization directions of the central part 28.29 and the peripheral part 27.30 of the reflected light flux become the S polarization component of the electric field vector shown in Fig. 3, 40.41, and further become the electric field vector shown in 39.42. .
第６図は第３の偏光ビームスプリッタ−１２を透過した
後の第４図に示したｐ偏光成分の光束が結像レンズ１３
、瞳分割プリズム１５により要素光電変換素子１．７−
１．１７−２上に結像されるようすを示すものである。FIG. 6 shows that the p-polarized light component shown in FIG. 4 after passing through the third polarizing beam splitter 12 is transferred to the imaging lens 13.
, elemental photoelectric conversion element 1.7- by the pupil splitting prism 15
This shows how the image is formed on 1.17-2.
光束上半部２７．２８からの光束は結像レンズ透過後、
瞳分割プリズム１５−１により上部へ光束が曲げられ、
要素光電変換素子１７−１上に結像される。この光束内
の偏光成分は、第４図に示したように光束２７と２８と
で互いに位相が逆になっている。したがって要素光電変
換素子１７−１上に結像されるスポット光は光束２７と
２８とがｏｕｔ−ｏｆ−ｐｈａｓｅで干渉した結果であ
り、光強度は両者単独の強度の和よりも少なくなる。After the light flux from the upper half of the light flux passes through the imaging lens,
The light beam is bent upward by the pupil splitting prism 15-1,
An image is formed on the elemental photoelectric conversion element 17-1. As shown in FIG. 4, the polarized light components in this light beam have opposite phases in light beams 27 and 28. Therefore, the spot light imaged on the element photoelectric conversion element 17-1 is the result of out-of-phase interference between the light beams 27 and 28, and the light intensity is less than the sum of the intensities of both alone.
他方下部光束２９．３０からの光束は結像レンズ透過後
、瞳分割プリズム１５−２により下部へ光束が曲げられ
、要素光電変換素子１７−２上に結像される。この光束
内の偏光成分は第４図に示したように光束２９．３０と
は互いに同位相である。したがって要素光電変換素子１
７−２上に結像されるスポット光は光束２９．３０とが
１ｎ−ｐｈａ ｓ ｅで干渉した結果であり、光強度は
両者単独の強度の和よりも多くなる。On the other hand, the light beams from the lower light beams 29 and 30 pass through the imaging lens, are bent downward by the pupil splitting prism 15-2, and are imaged onto the elemental photoelectric conversion element 17-2. As shown in FIG. 4, the polarization components in this light beam are in phase with the light beams 29 and 30. Therefore, element photoelectric conversion element 1
The spot light imaged on 7-2 is the result of interference with the light beam 29.30 at 1n-phase, and the light intensity is greater than the sum of the intensities of the two alone.
したがって２分割光電変換素子１７−１．１７−２上に
は等しくない光強度が入射し、この２つの要素光電変換
素子からの出力信号の差信号４３はマイナスとなる。Therefore, unequal light intensities are incident on the two-part photoelectric conversion elements 17-1 and 17-2, and the difference signal 43 between the output signals from these two element photoelectric conversion elements becomes negative.
一方、第３の偏光ビームスプリッタ−１２を反射した後
の第５図に示すＳ偏光成分光束が結像レンズ１４、瞳分
割プリズム１６により要素光電変換素子１８−１．１８
−２上に作るスポット光の光量についても同様に、光束
上部２７．２８からの光束が１ｎ−ｐｈａｓｅで干渉し
た結果としての光強度と、下部２９．３０からの光束が
ｏｕｔ−ｏｆ−ｐｈａｓｅで干渉した結果としての光強
度との差が生じ、差信号はプラスとなる。On the other hand, after being reflected by the third polarizing beam splitter 12, the S-polarized component light beam shown in FIG.
Similarly, regarding the light intensity of the spot light created on -2, the light intensity is the result of the interference of the light flux from the upper part 27.28 in the 1n-phase, and the light intensity as a result of the light flux from the lower part 29.30 being out-of-phase. A difference in light intensity occurs as a result of the interference, and the difference signal becomes positive.
スポット光５の照射内に情報磁区エツジが存在しない場
合には、第２図の反射光束２４内に電界ベクトルの方向
差が発生せず、したがって第３図に示したような反射光
束の２８．２９、または２７．３０での電界ベクトルの
方向差が発生しない。したがって各々の要素光電変換光
検出器上に結像されるスポット光の光量は等しく、差信
号はゼロとなる。If there is no information magnetic domain edge within the irradiation of the spot light 5, no difference in the direction of the electric field vector will occur in the reflected light beam 24 shown in FIG. 2, and therefore the 28. No difference in direction of the electric field vector occurs at 29 or 27.30. Therefore, the light intensity of the spot light imaged on each element photoelectric conversion photodetector is equal, and the difference signal becomes zero.
以上述べたように、本実施例においては、瞳分割プリズ
ム１５により、結像レンズ通過後の光束は偏向され、各
要素光電変換光検出器の有効受光面の中心に結像スポッ
トの中心が一致するようになる。このため従来の問題点
であった、空間分割光電変換光検出器の継目の光不感領
域での光量ロスを小さく出来、光磁気記録媒体からの少
ない反射光量を有効に利用する事ができる。As described above, in this embodiment, the light beam after passing through the imaging lens is deflected by the pupil splitting prism 15, and the center of the imaging spot coincides with the center of the effective light receiving surface of each element photoelectric conversion photodetector. I come to do it. Therefore, it is possible to reduce the loss of light amount in the light-insensitive area of the joint of the space-division photoelectric conversion photodetector, which was a problem in the conventional art, and it is possible to effectively utilize the small amount of reflected light from the magneto-optical recording medium.
さらに、格２分割光電変換素子からの差信号同士からさ
らに差信号を作り、これを用いれば、エツジを境とする
磁化変化の向きを検出することができる。すなわち、２
分割光電変換素子１７−■、１７−２からの差信号をＳ
ｌ、同じく２分割光電変換素子１８−１．１８−２から
の差信号を８２とし、この信号同士の差５ｌ−３２をエ
ツジ検出信号とすれば、光スポットが磁区を走査する時
第７図に示すような信号が得られ、エツジの変化の方向
に対応したエツジ検出信号を得ることができる。第７図
において４４−１．４４−２．４４−３はそれぞれ１つ
の情報磁区を示す。この中の矢印は磁化の方向を示して
いる。Further, by creating a difference signal from the difference signals from the case-two-split photoelectric conversion elements and using this, it is possible to detect the direction of magnetization change with the edge as the boundary. That is, 2
The difference signals from the split photoelectric conversion elements 17-■ and 17-2 are
Similarly, if the difference signal from the two-split photoelectric conversion element 18-1 and 18-2 is 82, and the difference 5l-32 between these signals is used as the edge detection signal, when the light spot scans the magnetic domain, as shown in FIG. A signal as shown in is obtained, and an edge detection signal corresponding to the direction of edge change can be obtained. In FIG. 7, 44-1.44-2.44-3 each indicate one information magnetic domain. The arrows in this figure indicate the direction of magnetization.
第８図は瞳分割プリズムの代わりの他の手段を示す図で
ある。FIG. 8 is a diagram showing another means in place of the pupil splitting prism.
同図において、４５は第２の偏光ビームスプリッタ−８
からの反射光束であり、４６は４６−１４．６−２の２
つのレンズ光軸を距離Ｇづらした複合レンズであり、そ
の断面は第９図に示すようである。結像レンズ４６−１
を透過した光束は２分割充電変換素子４７−１上に結像
し、結像レンズ４６−２を透過した光束は２分割光電変
換素子４７−２上に結像する。この複合レンズを先の実
施例の結像レンズと瞳分割プリズムの対と置き換える事
により、同じ機能を果たす光学系を実現できる。In the figure, 45 is the second polarizing beam splitter 8
, and 46 is 2 of 46-14.6-2.
It is a compound lens in which the optical axes of the two lenses are shifted by a distance G, and its cross section is as shown in FIG. Imaging lens 46-1
The light beam that has passed through the imaging lens 46-2 forms an image on the two-part charging conversion element 47-1, and the light beam that has passed through the imaging lens 46-2 forms an image on the two-part photoelectric conversion element 47-2. By replacing this compound lens with the pair of imaging lens and pupil splitting prism in the previous embodiment, an optical system that performs the same function can be realized.
以上説明したように、本発明は光磁気記録膜によって生
じる磁気カー効果のＳ偏光成分を用いて従来の光磁気ヘ
ッドの構造を複雑化することなく高精度に情報磁区エツ
ジを検出できる光量利用効率の高い光磁気ディスク用の
光ヘッドを実現するものである。As explained above, the present invention provides a light amount utilization efficiency that allows information magnetic domain edges to be detected with high precision without complicating the structure of a conventional magneto-optical head by using the S-polarized light component of the magnetic Kerr effect produced by a magneto-optical recording film. The present invention is intended to realize an optical head for a magneto-optical disk with high performance.
第１図は本発明の光学的情報再生装置に用いられる光ヘ
ッドの概略図、
第２図は記録された情報磁区のエツジ上にスポット光が
入射した場合を示す図、
第３図は１／２は波長板通過後の光束の偏光成分を示す
図、
第４図及び第５図は偏光ビームスプリッタ−通過後の光
束の偏光成分を示す図、
第６図は偏光ビームスプリッタ−通過後の光束が光電変
換素子上に結像される様子を示す図、第７図は光電変換
素子からの信号を示す図、第８図及び第９図は瞳分割プ
リズムの代わりに複合レンズを用いた例を説明する図で
ある。
１・・・半導体レーザ
２・・・コリメータレンズ
３・・・第１の偏光ビームスプリッタ−４・・・対物レ
ンズ
５・・・ 投光スポット
６・・・光磁気ディスクに設けられた情報トラック７・
・・トラッキング用に設けられた案内溝８・・・第２の
偏光ビームスプリッタ−１０・・・位相差調整光学素子
１１・・・１／２波長板
１２・・・第３の偏光ビームスプリッタ−１３，１４・
・・結像レンズ
１５．１６・・・瞳光束分割素子、
１７．１８・・・２分割光電変換素子FIG. 1 is a schematic diagram of an optical head used in the optical information reproducing apparatus of the present invention, FIG. 2 is a diagram showing a case where a spot light is incident on the edge of a recorded information magnetic domain, and FIG. 2 is a diagram showing the polarization component of the light beam after passing through the wave plate, FIGS. 4 and 5 are diagrams showing the polarization component of the light beam after passing through the polarizing beam splitter, and FIG. 6 is a diagram showing the polarization component of the light beam after passing through the polarizing beam splitter. Figure 7 is a diagram showing the signal from the photoelectric conversion element, and Figures 8 and 9 are examples in which a compound lens is used instead of the pupil splitting prism. FIG. 1... Semiconductor laser 2... Collimator lens 3... First polarizing beam splitter 4... Objective lens 5... Light projection spot 6... Information track 7 provided on the magneto-optical disk・
...Guide groove 8 provided for tracking...Second polarizing beam splitter 10...Phase difference adjusting optical element 11...1/2 wavelength plate 12...Third polarizing beam splitter 13,14・
...Imaging lens 15.16...Pupillary beam splitting element, 17.18...Two-split photoelectric conversion element
Claims (2)
レンズを介して微小スポット光として、垂直磁気記録媒
体から成る情報記録面上に設けられた１つの情報トラッ
クに導き、 前記情報記録面からの反射光を、前記対物レンズを介し
て受光光学系により第１、第２の空間的に分離された要
素光電変換光検出器から成る２分割光電変換光検出器に
導き、前記情報トラック上に記録された情報の再生を行
う光学的情報再生装置において、 前記受光光学系は、前記反射光束を前記情報トラック方
向に第１、第２の領域に分割し、前記第１の領域の光束
を前記第１の要素光検出器上に結像させ、前記第２の領
域の光束を前記第２の要素光電検出器上に結像させる瞳
分割結像系を有し、前記２分割光電変換光検出器からの
信号を用いて前記情報トラック上の情報を検出する事を
特徴とする光学的情報再生装置。(1) A light beam from a semiconductor laser is guided by a projection optical system as a minute spot light through an objective lens to one information track provided on an information recording surface made of a perpendicular magnetic recording medium, and from said information recording surface. The reflected light of In an optical information reproducing device that reproduces recorded information, the light receiving optical system divides the reflected light beam into a first region and a second region in the information track direction, and divides the light flux of the first region into the first region and the second region. a pupil division imaging system that forms an image on a first elemental photodetector and images a light flux of the second region on the second elemental photodetector; the two-split photoelectric conversion light detection An optical information reproducing device characterized in that information on the information track is detected using a signal from a device.
レンズを介して微小スポット光として、垂直磁気記録媒
体からなる情報記録面上に設けられた情報磁区に導き、
前記情報磁区からの反射光を前記対物レンズを介して受
光光学系により第１、第２の空間的に分離された要素光
電変換検出器から成る２分割光電変換光検出器に導き、
前記情報記録面上に記録された情報磁区エッジの再生を
行う光学的情報再生装置において、 前記受光光学系は、前記情報記録面からの反射光束内の
一部の領域の光束の偏光方向を９０度回転させる偏光方
向回転光学素子と、 前記領域内の光束とこの領域外の光束との位相差をある
値に調整可能な位相差調整光学素子と、前記偏光方向回
転光学素子および／または位相差調整光学素子を透過し
た光束を第１、第２の領域に分割し、前記第１の領域の
光束を前記第１の要素光検出器上に結像させ、前記第２
の領域の光束を前記第２の要素光電検出器上に結像させ
る光束分割結像系とを有し、 前記２分割光電変換光検出器からの差信号を用いて前記
情報磁区のエッジを検出する事を特徴とする光学的情報
再生装置。(2) A light beam from a semiconductor laser is guided by a projection optical system as a minute spot light through an objective lens to an information magnetic domain provided on an information recording surface of a perpendicular magnetic recording medium;
guiding the reflected light from the information magnetic domain through the objective lens to a two-split photoelectric conversion photodetector consisting of first and second spatially separated elementary photoelectric conversion detectors by a light receiving optical system;
In the optical information reproducing device that reproduces information magnetic domain edges recorded on the information recording surface, the light receiving optical system may change the polarization direction of a partial region of the light beam reflected from the information recording surface by 90 degrees. a polarization direction rotation optical element that rotates the polarization direction by a degree, a phase difference adjustment optical element that can adjust the phase difference between the light beam within the region and the light flux outside the region to a certain value, and the polarization direction rotation optical element and/or the phase difference. The light flux transmitted through the adjustment optical element is divided into a first and second region, the light flux of the first region is imaged on the first element photodetector, and the light flux of the first region is imaged on the first element photodetector.
a beam splitting imaging system that images a beam of light in a region on the second element photoelectric detector, and detects an edge of the information magnetic domain using a difference signal from the two-split photoelectric conversion photodetector. An optical information reproducing device characterized by:
Priority Applications (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31068290A JPH04182952A (en) | 1990-11-16 | 1990-11-16 | Optical information producing device |
| DE69126160T DE69126160T2 (en) | 1990-03-16 | 1991-03-15 | Optical information recording / reproducing apparatus |
| EP91302268A EP0447265B1 (en) | 1990-03-16 | 1991-03-15 | Optical information recording/reproducing apparatus |
| US08/165,548 US5581532A (en) | 1990-03-16 | 1993-12-13 | Optical information recording/reproducing apparatus for accurately detecting magnetic domain edges |
| US08/282,768 US5712840A (en) | 1990-03-16 | 1994-07-29 | Optical information recording/reproduciing apparatus having two-division detectors |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31068290A JPH04182952A (en) | 1990-11-16 | 1990-11-16 | Optical information producing device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH04182952A true JPH04182952A (en) | 1992-06-30 |
Family
ID=18008187
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP31068290A Pending JPH04182952A (en) | 1990-03-16 | 1990-11-16 | Optical information producing device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH04182952A (en) |
-
1990
- 1990-11-16 JP JP31068290A patent/JPH04182952A/en active Pending
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