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
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP2539350B2 (en) | Optical head device | |
JPH034976B2 (en) | ||
JPH08306091A (en) | Optical head | |
JPS5829155A (en) | Information reproducer by photomagnetic system | |
JP2790701B2 (en) | Optical information reproduction method | |
JPH0690817B2 (en) | Light pickup | |
JP3554844B2 (en) | Magneto-optical head device | |
JPH04182952A (en) | Optical information producing device | |
JPH07169129A (en) | Optical head | |
JPS5992457A (en) | Optical reproducer | |
JP2978269B2 (en) | Optical disk drive | |
JP2921801B2 (en) | Optical information reproducing device | |
JPS61198457A (en) | Optical pickup | |
KR960000270B1 (en) | Optical pick-up apparatus | |
JP2879601B2 (en) | Optical information recording / reproducing device | |
JP3211483B2 (en) | Optical pickup device | |
JPH04181537A (en) | Optical information reproducer | |
JPH04178941A (en) | Optical information reproducer | |
JP3083894B2 (en) | Optical playback device | |
JPH043575B2 (en) | ||
JPH0743833B2 (en) | Optical recording / reproducing device | |
JPH03178064A (en) | Optical head device | |
JP3095194B2 (en) | Magneto-optical information reproducing device | |
JPS63157341A (en) | Magneto-optical recording/reproducing head | |
JP2578413B2 (en) | Magneto-optical information reproducing device |