JPH1069673A - Optical head device and composite anisotropic diffraction element using therefor - Google Patents
Optical head device and composite anisotropic diffraction element using thereforInfo
- Publication number
- JPH1069673A JPH1069673A JP8227086A JP22708696A JPH1069673A JP H1069673 A JPH1069673 A JP H1069673A JP 8227086 A JP8227086 A JP 8227086A JP 22708696 A JP22708696 A JP 22708696A JP H1069673 A JPH1069673 A JP H1069673A
- Authority
- JP
- Japan
- Prior art keywords
- diffraction grating
- light
- diffracted
- diffraction
- polarization
- 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.)
- Granted
Links
Landscapes
- Diffracting Gratings Or Hologram Optical Elements (AREA)
- Optical Head (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、光磁気記録媒体用
の光ヘッド装置及びそれに用いる複合異方性回折素子に
関する。[0001] 1. Field of the Invention [0002] The present invention relates to an optical head device for a magneto-optical recording medium and a composite anisotropic diffraction element used therefor.
【０００２】[0002]
【従来の技術】光磁気記録媒体用の光ヘッド装置におい
ては、光磁気記録媒体に記録されたカー回転角（偏光面
の回転角）を検出して用いている。このような光ヘッド
装置としては、図５のような構成のものが用いられてい
た。2. Description of the Related Art In an optical head device for a magneto-optical recording medium, a Kerr rotation angle (rotation angle of a polarization plane) recorded on the magneto-optical recording medium is detected and used. As such an optical head device, one having a configuration as shown in FIG. 5 has been used.
【０００３】図５において、４１は半導体レーザのよう
な光源、４２は単純回折格子、４３はビーム分離用のプ
リズム、４４は集光レンズ、４５は光磁気記録媒体、４
６はウオラストンプリズム、５１〜５５は光検出器を示
す。In FIG. 5, reference numeral 41 denotes a light source such as a semiconductor laser; 42, a simple diffraction grating; 43, a prism for separating beams; 44, a condenser lens;
Reference numeral 6 denotes a Wollaston prism, and reference numerals 51 to 55 denote photodetectors.
【０００４】図５の光ヘッド装置では、光源４１から出
射した光は、単純回折格子４２、プリズム４３を通過
し、集光レンズ４４で集光されて光磁気記録媒体４５に
到達する。この光磁気記録媒体４５で反射された戻り光
は、再度集光レンズ４４で集光され、プリズム４３に入
射して２つの光に分離される。In the optical head device shown in FIG. 5, light emitted from a light source 41 passes through a simple diffraction grating 42 and a prism 43, is condensed by a condenser lens 44, and reaches a magneto-optical recording medium 45. The return light reflected by the magneto-optical recording medium 45 is condensed again by the condenser lens 44, enters the prism 43, and is separated into two lights.
【０００５】分離された光の一方は、そのまま直進して
再度単純回折格子４２に入射して回折し、光検出器５
１、５２に到達する。この回折光は、フォーカスエラー
の検出、トラッキングエラーの検出に用いられる。分離
された光の他方は、プリズム４３内で反射されてウオラ
ストンプリズム４６に入射し、ここで回折されて光検出
器５３〜５５に到達する。この回折光は信号として検出
される。One of the separated lights goes straight as it is, enters the simple diffraction grating 42 again, and is diffracted.
1 and 52 are reached. This diffracted light is used for detecting a focus error and a tracking error. The other of the separated light is reflected in the prism 43 and enters the Wollaston prism 46, where it is diffracted and reaches the photodetectors 53 to 55. This diffracted light is detected as a signal.
【０００６】[0006]
【発明が解決しようとする課題】しかしこのような構成
の光ヘッド装置は、高価な結晶材料を用いており、部品
点数が多く、調整が複雑で、生産性が悪く、コストが高
く、形状が大きいという問題があった。本発明は、これ
らの問題点を解決した光ヘッド装置を提供することを目
的とする。However, an optical head device having such a structure uses an expensive crystal material, has a large number of parts, is complicated to adjust, has low productivity, is expensive, and has a large shape. There was a problem of being big. An object of the present invention is to provide an optical head device that solves these problems.
【０００７】[0007]
【課題を解決するための手段】本発明は、光源と光磁気
記録媒体との間に光分離回折素子を設け、光磁気記録媒
体からの戻り光を、光分離回折素子で２以上の光に分離
し、さらにそれらの光を回折させて光ヘッド装置の駆動
制御のための光検出器及び信号検出のための光検出器に
到達するようにした光ヘッド装置において、光分離回折
素子が単純回折格子と偏光回折格子とを有しており、戻
り光が単純回折格子で回折され、その０次でない回折光
の１つ以上の光が偏光回折格子に入射して回折されるこ
とを特徴とする光ヘッド装置を提供する。According to the present invention, a light separation / diffraction element is provided between a light source and a magneto-optical recording medium, and return light from the magneto-optical recording medium is converted into two or more lights by the light separation / diffraction element. In an optical head device that separates and further diffracts the light to reach a photodetector for drive control of the optical head device and a photodetector for signal detection, the light separation / diffraction element is simply diffracted. A grating and a polarization diffraction grating, wherein the return light is diffracted by the simple diffraction grating, and one or more of the non-zero-order diffracted lights are incident on the polarization diffraction grating and diffracted. An optical head device is provided.
【０００８】また、その単純回折格子で回折された、＋
１次と−１次の回折光が、夫々偏光特性の異なる偏光回
折格子に入射して回折される光ヘッド装置、及び、それ
らの偏光回折格子が少なくとも一方に内面に凹凸のある
基板を用いた液晶回折格子である光ヘッド装置、及び、
それらの光分離回折素子の光源側の基板外面にも単純回
折格子が形成され、３ビームを発生するようにされてい
る光ヘッド装置を提供する。[0008] In addition, + diffracted by the simple diffraction grating
An optical head device is used in which first-order and -1st-order diffracted lights are incident on and diffracted from polarization diffraction gratings having different polarization characteristics, and a substrate having at least one of these polarization diffraction gratings having irregularities on the inner surface. An optical head device which is a liquid crystal diffraction grating, and
Provided is an optical head device in which a simple diffraction grating is also formed on the outer surface of the substrate on the light source side of these light separation / diffraction elements to generate three beams.
【０００９】また、少なくとも一方に内面に凹凸のある
基板を用い、内部に封入した光学異方性材料との相互作
用による偏光回折格子を有する複合異方性回折素子にお
いて、少なくとも一方の基板の外面には凹凸による回折
格子が形成され、この外側の回折格子で回折された光の
０次でない回折光の１つ以上の光が内面の偏光回折格子
に入射して再度回折されるように配置されたことを特徴
とする複合異方性回折素子を提供する。Also, in a composite anisotropic diffraction element having at least one substrate having an uneven surface on an inner surface and having a polarization diffraction grating due to interaction with an optically anisotropic material encapsulated therein, Are formed so that at least one non-zero-order diffracted light of the light diffracted by the outer diffraction grating is incident on the inner surface polarization diffraction grating and is diffracted again. The invention provides a composite anisotropic diffraction element characterized in that:
【００１０】また、その２枚の基板ともに内面に凹凸の
ある基板を用い、一方の１次の回折光が入射側に凹凸が
ある偏光回折格子に、他方の１次の回折光が出射側に凹
凸がある偏光回折格子に入射するように配置された複合
異方性回折素子を提供する。[0010] Further, both of the two substrates use a substrate having irregularities on the inner surface, and one of the primary diffracted lights is on a polarization diffraction grating having irregularities on the incident side, and the other is diffracted on the emitting side. Provided is a composite anisotropic diffraction element arranged so as to be incident on a polarization diffraction grating having irregularities.
【００１１】[0011]
【発明の実施の形態】本発明では、光ヘッド装置の光分
離回折素子が単純回折格子と偏光回折格子とを有してお
り、戻り光が単純回折格子で回折され、その０次でない
回折光の１つ以上の光が偏光回折格子に入射して回折さ
れるようにされているので、光分離回折素子が小型でか
つ容易に製造できる。DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a light separation / diffraction element of an optical head device has a simple diffraction grating and a polarization diffraction grating. Since one or more lights are incident on the polarization diffraction grating and diffracted, the light separation / diffraction element can be manufactured in a small size and easily.
【００１２】特に、基板の内外面に凹凸による回折格子
を設け、内部に光学異方性材料を充填した複合異方性回
折素子を用いることにより、きわめて小型にできるとと
もに、その部分については組立後の調整が不要となる利
点を有する。In particular, by using a composite anisotropic diffraction element in which a diffraction grating is formed on the inner and outer surfaces of the substrate by using irregularities and filled with an optically anisotropic material, the size of the substrate can be extremely reduced. There is an advantage that adjustment of is unnecessary.
【００１３】図１、図２は本発明の複合異方性回折素子
の具体的な例の断面図である。図１は基本的な構成を示
し、図２は３ビーム発生用の第４の回折格子を設けた例
を示す。図１、図２において、１、２、３は回折格子、
４、５は基板、６は光学異方性材料の代表である液晶、
１０は半導体レーザ等の光源からの光、１１〜１６は光
磁気記録媒体からの戻り光の回折光を示す。図２の７は
３ビーム発生用の回折格子を示す。FIGS. 1 and 2 are cross-sectional views of a specific example of the composite anisotropic diffraction element of the present invention. FIG. 1 shows a basic configuration, and FIG. 2 shows an example in which a fourth diffraction grating for generating three beams is provided. 1 and 2, reference numerals 1, 2, and 3 denote diffraction gratings,
4 and 5 are substrates, 6 is a liquid crystal representative of an optically anisotropic material,
Numeral 10 indicates light from a light source such as a semiconductor laser, and 11 to 16 indicate diffracted light of return light from the magneto-optical recording medium. Reference numeral 7 in FIG. 2 shows a diffraction grating for generating three beams.
【００１４】図３、図４は、図１、図２の複合異方性回
折素子を用いた光ヘッド装置の具体的な例の模式図であ
る。図３は図１に対応し、図４は図２に対応している。
図３、図４において、２１は半導体レーザ等の光源、２
２は図１の複合異方性回折素子、２３は集光レンズ、２
４は光磁気記録媒体、３０は光源から出射し光磁気記録
媒体に到達した光、３１〜３６は光検出器を示す。図４
の２５は図２の複合異方性回折素子、３７は光源から出
射し光磁気記録媒体に到達した光を示す。FIGS. 3 and 4 are schematic views of specific examples of an optical head device using the composite anisotropic diffraction element shown in FIGS. 1 and 2. FIG. FIG. 3 corresponds to FIG. 1, and FIG. 4 corresponds to FIG.
3 and 4, reference numeral 21 denotes a light source such as a semiconductor laser,
2 is a composite anisotropic diffraction element of FIG. 1, 23 is a condenser lens, 2
Reference numeral 4 denotes a magneto-optical recording medium, 30 denotes light emitted from a light source and reaches the magneto-optical recording medium, and 31 to 36 denote photodetectors. FIG.
Reference numeral 25 denotes the composite anisotropic diffraction element shown in FIG. 2, and 37 denotes light emitted from the light source and reaching the magneto-optical recording medium.
【００１５】本発明では、光ヘッド装置の光分離回折素
子が単純回折格子と偏光回折格子とを有している。光磁
気記録媒体からの戻り光が単純回折格子で回折され、そ
の０次でない回折光の１つ以上の光が偏光回折格子に入
射して回折される。この２種類の回折格子が一体化され
ている。In the present invention, the light separating / diffraction element of the optical head device has a simple diffraction grating and a polarization diffraction grating. Return light from the magneto-optical recording medium is diffracted by the simple diffraction grating, and one or more non-zero-order diffracted lights are incident on the polarization diffraction grating and diffracted. These two types of diffraction gratings are integrated.
【００１６】具体的には、少なくとも一方に内面に凹凸
のある基板を用い、内部に封入した光学異方性材料との
相互作用による偏光回折格子を用い、これと基板外面に
設けた単純回折格子とにより複合異方性回折素子を構成
する。More specifically, at least one of the substrates has an irregular surface on the inner surface, a polarization grating based on the interaction with an optically anisotropic material encapsulated therein, and a simple diffraction grating provided on the outer surface of the substrate. These form a composite anisotropic diffraction element.
【００１７】基板の外面の単純回折格子は、ストライプ
状に回折格子を形成すればよい。これには、基板の外面
をエッチング、機械的な切削、プレス等により凹凸化し
て回折格子を形成することが生産性が良く好適である。
この場合、基板自体を直接加工してもよく、基板表面に
特定の屈折率の透明膜を形成しこれを加工するようにし
てもよい。このほか、部分的に基板自体の屈折率を変え
て回折格子として働くようにもできる。この外面の単純
回折格子は、光磁気記録媒体側に配置され、光磁気記録
媒体からの戻り光が単純回折格子で回折される。The simple diffraction grating on the outer surface of the substrate may be formed in a stripe shape. For this purpose, it is preferable that the outer surface of the substrate is made uneven by etching, mechanical cutting, pressing, or the like to form a diffraction grating with high productivity.
In this case, the substrate itself may be processed directly, or a transparent film having a specific refractive index may be formed on the substrate surface and then processed. In addition, the refractive index of the substrate itself can be partially changed to function as a diffraction grating. The simple diffraction grating on the outer surface is disposed on the magneto-optical recording medium side, and return light from the magneto-optical recording medium is diffracted by the simple diffraction grating.
【００１８】この、単純回折格子で回折された光のう
ち、その０次でない回折光の１つ以上の光が偏光回折格
子に入射するようにされる。この偏光回折格子は、基板
内面に形成された凹凸と内部に封入した光学異方性材料
との相互作用により、特定の偏光方向の光を回折する。
この基板内面の凹凸も、前記した基板の外面の単純回折
格子と同様に形成すればよい。Of the light diffracted by the simple diffraction grating, one or more non-zero-order diffracted lights are made to enter the polarization diffraction grating. This polarization diffraction grating diffracts light of a specific polarization direction by the interaction between the unevenness formed on the inner surface of the substrate and the optically anisotropic material enclosed therein.
The unevenness on the inner surface of the substrate may be formed in the same manner as the simple diffraction grating on the outer surface of the substrate.
【００１９】この光分離回折素子の偏光回折格子は、１
つのみとすることもできるが、＋１次と−１次の回折光
の両方の回折光を回折させるために２つの偏光回折格子
を形成することが好ましい。この２つの偏光回折格子
は、偏光依存性に差があるようにされることが好まし
い。The polarization diffraction grating of this light separation / diffraction element has the following structure.
There can be only one, but it is preferable to form two polarization diffraction gratings in order to diffract both the + 1st-order and the -1st-order diffracted light. Preferably, the two polarization gratings have a difference in polarization dependence.
【００２０】具体的には、一方はＰ波を回折させ、Ｓ波
は直進させ、他方はＳ波を回折させ、Ｐ波は直進させる
ような偏光依存性を有することが好ましい。このため、
基板内面の凹凸と光学異方性材料とで構成した偏光回折
格子の場合には、２つの偏光回折格子で凹凸がある面を
逆の基板にすることが好ましい。Specifically, it is preferable that one has a polarization dependency such that one diffracts a P-wave and the S-wave travels straight, and the other diffracts an S-wave and the P-wave travels straight. For this reason,
In the case of a polarization diffraction grating composed of the unevenness on the inner surface of the substrate and the optically anisotropic material, it is preferable that the surface of the two polarization diffraction gratings having the unevenness be the opposite substrate.
【００２１】特に、この偏光回折格子は、内部に封入す
る光学異方性材料と基板の凹凸との屈折率との関係が重
要になるので、凹凸の屈折率を調整する必要がある。こ
のため、基板自体が所望の屈折率であればそのまま使用
できるが、基板自体の屈折率と所望の屈折率とが異なる
場合には、基板表面に所望の屈折率の透明膜を形成する
ことが好ましい。この透明膜はエッチング等によりパタ
ーニングしてもよく、所望のパターンに直接形成しても
よい。In particular, the relationship between the refractive index of the optically anisotropic material to be enclosed therein and the refractive index of the unevenness of the substrate becomes important in this polarization diffraction grating, so it is necessary to adjust the refractive index of the unevenness. For this reason, if the substrate itself has a desired refractive index, it can be used as it is, but when the refractive index of the substrate itself is different from the desired refractive index, it is possible to form a transparent film having a desired refractive index on the substrate surface. preferable. This transparent film may be patterned by etching or the like, or may be formed directly into a desired pattern.
【００２２】具体的には、凹凸部の屈折率を、光学異方
性材料の常光屈折率か異常光屈折率に一致するようにさ
れる。光学異方性材料として液晶を用い、回折格子の長
手方向にラビングにより配向処理をした場合について説
明する。Specifically, the refractive index of the concave and convex portions is made to match the ordinary light refractive index or the extraordinary light refractive index of the optically anisotropic material. A case in which liquid crystal is used as an optically anisotropic material and alignment processing is performed by rubbing in the longitudinal direction of the diffraction grating will be described.
【００２３】凹凸部の屈折率を液晶の常光屈折率に一致
するようにすると、液晶分子が格子の長手方向に配列し
ているので、格子の長手方向に直交する方向に偏光方向
のある光は両方の屈折率は一致していることになるの
で、回折格子として働かず、光は直進する。一方、格子
の長手方向に偏光方向のある光は、見かけ上液晶の屈折
率が異常光屈折率となり、両方の屈折率は一致しなくな
るので、回折格子として働くことになり、光は回折され
る。When the refractive index of the concave / convex portions is made to match the ordinary light refractive index of the liquid crystal, since the liquid crystal molecules are arranged in the longitudinal direction of the lattice, light having a polarization direction perpendicular to the longitudinal direction of the lattice is Since the two refractive indices are the same, the light does not work as a diffraction grating and the light goes straight. On the other hand, light having a polarization direction in the longitudinal direction of the grating will act as a diffraction grating because the apparent refractive index of the liquid crystal becomes an extraordinary light refractive index and the two refractive indexes do not match, and the light is diffracted. .
【００２４】また、この凹凸部の屈折率を液晶の異常光
屈折率に一致するようにすると、液晶分子が格子の長手
方向に配列しているので、格子の長手方向に直交する方
向に偏光方向のある光は、見かけ上液晶の屈折率が常光
屈折率となるので、両方の屈折率は一致しなくなり、光
は回折される。一方、格子の長手方向に偏光方向のある
光は、両方の屈折率は一致していることになるので、回
折格子として働かず、光は直進する。When the refractive index of the concave and convex portions is made to coincide with the extraordinary light refractive index of the liquid crystal, since the liquid crystal molecules are arranged in the longitudinal direction of the lattice, the polarization direction is perpendicular to the longitudinal direction of the lattice. Since the refractive index of the liquid crystal has the ordinary refractive index of the ordinary light, the refractive indexes of the two liquids do not match, and the light is diffracted. On the other hand, light having a polarization direction in the longitudinal direction of the grating has the same refractive index, so that the light does not work as a diffraction grating and travels straight.
【００２５】このため、２つの回折格子の凹凸部を夫々
常光屈折率及び異常光屈折率と一致するような材料で構
成しておくことにより、異なる偏光特性を有するように
させうる。これにより、回折格子２と３では、一方でＰ
波成分が回折し、他方ではＳ波成分が回折することにな
る。For this reason, by forming the concave and convex portions of the two diffraction gratings with materials that match the refractive index of the ordinary light and the refractive index of the extraordinary light, respectively, different polarization characteristics can be obtained. Accordingly, in the diffraction gratings 2 and 3, P
The wave component is diffracted, while the S wave component is diffracted.
【００２６】図１のように液晶層を挟んだ２枚の基板に
凹凸部を形成する場合には、液晶が９０°ねじれるよう
に配向処理しておけば、両方の凹凸部が液晶の常光屈折
率と屈折率が一致するようにしておいてもよい。これ
は、凹凸部が光源側の基板５にある回折格子には液晶層
を通過することにより光の偏光方向が９０°回転して入
射するので、回折格子２と３では、一方でＰ波成分が回
折し、他方ではＳ波成分が回折することになる。As shown in FIG. 1, when forming an uneven portion on two substrates sandwiching a liquid crystal layer, if the liquid crystal is subjected to an orientation treatment so as to be twisted by 90 °, both the uneven portions are refracted by ordinary light of the liquid crystal. The index and the refractive index may be matched. This is because the polarization direction of the light is rotated by 90 ° to enter the diffraction grating having the concave and convex portions on the substrate 5 on the light source side by passing through the liquid crystal layer. Is diffracted, and on the other hand, the S-wave component is diffracted.
【００２７】図１の例では、単純回折格子である回折格
子１で回折された光は、直進する０次光の他に少なくと
も２方向に進行する。左側に進行した光は基板５の内面
に設けられた凹凸と光学異方性材料である液晶６とによ
る偏光回折格子である回折格子２で回折し光１１、１
２、１３となって、光検出器にに到達する。右側に進行
した光は基板４の内面に設けられた凹凸と光学異方性材
料である液晶６とによる偏光回折格子である回折格子３
で回折し、光１４、１５、１６となって光検出器に到達
する。In the example of FIG. 1, the light diffracted by the diffraction grating 1, which is a simple diffraction grating, travels in at least two directions in addition to the zero-order light traveling straight. The light traveling to the left is diffracted by the diffraction grating 2 which is a polarization diffraction grating formed by the unevenness provided on the inner surface of the substrate 5 and the liquid crystal 6 which is an optically anisotropic material.
2, 13 and reach the photodetector. The light traveling to the right is a diffraction grating 3, which is a polarization diffraction grating formed by unevenness provided on the inner surface of the substrate 4 and liquid crystal 6 which is an optically anisotropic material.
, And are converted into lights 14, 15, and 16 and reach the photodetector.
【００２８】ここで、光源からの光がＰ波とＳ波との両
成分を含む４５°傾いた偏光方向の光を用いることとす
る。光磁気記録媒体で反射した戻り光は、ある角度偏光
面が回転している。この戻り光を単純回折格子である回
折格子１で回折させて２つの回折格子２、３に導く。Here, it is assumed that the light from the light source is a light having a polarization direction inclined by 45 ° and including both P-wave and S-wave components. The return light reflected by the magneto-optical recording medium has its polarization plane rotated by a certain angle. This return light is diffracted by the diffraction grating 1 which is a simple diffraction grating, and guided to the two diffraction gratings 2 and 3.
【００２９】この左側の回折格子２では、０次の光１２
ではほぼＰ波となり、−１次と＋１次の光１１、１３は
ほぼＳ波となるようにし、右側の回折格子３では、０次
の光１５ではほぼＳ波となり、−１次と＋１次の光１
４、１６はほぼＰ波となるようにされる。このときに、
１１と１３と１５とのＳ波の合計と、１２と１４と１６
とのＰ波の合計との差を計算することにより、光磁気記
録媒体での偏光回転角を読み取りうる。In the diffraction grating 2 on the left side, the zero-order light 12
, The -1st and + 1st order lights 11 and 13 are made to be almost S waves, and the right diffraction grating 3 becomes almost the S wave for the 0th order light 15 and the -1st and + 1st order lights. Light 1
4 and 16 are made to be substantially P waves. At this time,
The sum of the S-waves of 11, 13, and 15, and 12, 14, and 16
By calculating the difference from the sum of the P-waves, the polarization rotation angle in the magneto-optical recording medium can be read.
【００３０】図２のように、単純回折格子である第４の
回折格子７を光源側の基板外面に設けることにより、３
ビーム発生用となしうる。この第４の回折格子７は、通
常は回折格子１、２、３とは格子のストライプの方向が
直交するようにされる。As shown in FIG. 2, by providing a fourth diffraction grating 7 which is a simple diffraction grating on the outer surface of the substrate on the light source side, a third diffraction grating 7 is provided.
It can be used for beam generation. Normally, the fourth diffraction grating 7 is arranged such that the directions of the stripes of the grating are orthogonal to the diffraction gratings 1, 2, and 3.
【００３１】また、回折格子１にはさまざなな湾曲格子
を形成したり、領域を分け各々の異なる湾曲格子を形成
したりすることによって、フォーカスエラー検出、トラ
ッキングエラー検出の機能を光ヘッド装置に持たせう
る。Further, by forming various curved gratings on the diffraction grating 1 or forming different curved gratings by dividing the region, the functions of focus error detection and tracking error detection can be provided to the optical head device. I can have it.
【００３２】複合異方性回折素子に用いる基板は、通常
のガラス、プラスチック等の基板が使用でき、必要に応
じて所望の屈折率の透明膜を積層して用いる。さらに、
必要に応じて、これにポリイミドの配向膜、間隙制御用
のスペーサ、電極、シール材等を用いる。As the substrate used for the composite anisotropic diffraction element, a substrate made of ordinary glass, plastic, or the like can be used. If necessary, a transparent film having a desired refractive index is laminated and used. further,
If necessary, an alignment film of polyimide, a spacer for controlling a gap, an electrode, a sealing material, and the like are used for this.
【００３３】光学異方性材料としては、液晶が代表的な
材料として用いられる。通常は正の誘電異方性のネマチ
ック液晶を用いればよい。上記の説明では、液晶は液体
状の材料を用いることで説明したが、高分子液晶も使用
できる。不必要な表面反射を抑制するために反射防止コ
ートを形成したり、回折格子を複雑な形状にして付加機
能を付与させてもよい。As the optically anisotropic material, liquid crystal is used as a typical material. Usually, a nematic liquid crystal having a positive dielectric anisotropy may be used. In the above description, the liquid crystal is described as using a liquid material, but a polymer liquid crystal can also be used. An anti-reflection coating may be formed to suppress unnecessary surface reflection, or the diffraction grating may be formed into a complicated shape to add an additional function.
【００３４】[0034]
【実施例】屈折率１．５２、厚さ２ｍｍのガラス基板の
上（外面側）に、ＳｉＯ2 膜を蒸着によって厚み０．６
μｍで形成し、フォトリソグラフィとドライエッチング
によって、ピッチ１．５μｍ、深さ０．６μｍの回折格
子１を形成した。この回折格子には、ＳＳＤ（Spot Siz
e Detection ）法によるフォーカスエラー検出用のパタ
ーンを形成した。EXAMPLE On a glass substrate having a refractive index of 1.52 and a thickness of 2 mm (outer surface side), an SiO 2 film having a thickness of 0.6 was formed by vapor deposition.
The diffraction grating 1 having a pitch of 1.5 μm and a depth of 0.6 μm was formed by photolithography and dry etching. This diffraction grating includes an SSD (Spot Siz
e Detection) A pattern for focus error detection by the method was formed.
【００３５】そのガラス基板の上記回折格子形成面と逆
の面（内面側）の＋１次光が通過する位置に、屈折率
１．７９、厚み１．４μｍのＳｉＯＮ系の膜をプラズマ
ＣＶＤ法により形成し、フォトリソグラフィとドライエ
ッチングによって、ピッチ８μｍ、深さ１．４μｍの回
折格子３を形成した。An SiON-based film having a refractive index of 1.79 and a thickness of 1.4 μm is formed by plasma CVD on a surface (inner side) of the glass substrate opposite to the surface on which the diffraction grating is formed, at a position where + 1st-order light passes. The diffraction grating 3 having a pitch of 8 μm and a depth of 1.4 μm was formed by photolithography and dry etching.
【００３６】厚み０．５ｍｍ、屈折率１．５２の第２の
ガラス基板の表面（内面側）に、屈折率１．５２、厚み
１．４μｍのＳｉＯＮ系の膜を同じくプラズマＣＶＤ法
により形成し、フォトリソグラフィとドライエッチング
によって、ピッチ８μｍ、深さ１．４μｍの回折格子２
を形成した。On the surface (inner side) of a second glass substrate having a thickness of 0.5 mm and a refractive index of 1.52, an SiON-based film having a refractive index of 1.52 and a thickness of 1.4 μm is formed by the same plasma CVD method. Diffraction grating 2 having a pitch of 8 μm and a depth of 1.4 μm by photolithography and dry etching
Was formed.
【００３７】第２のガラス基板の上記回折格子形成面と
逆の面（外面側）に、半導体レーザからの往路光が通過
する位置に、ＳｉＯ2 膜を蒸着法により形成し、フォト
リソグラフィとドライエッチングによって、ピッチ１６
μｍ、深さ０．５μｍの回折格子４を形成した。An SiO 2 film is formed by vapor deposition on a surface (outer surface side) of the second glass substrate opposite to the surface on which the diffraction grating is formed, at a position where the outward light from the semiconductor laser passes therethrough. Pitch 16 by etching
A diffraction grating 4 having a thickness of 0.5 μm and a depth of 0.5 μm was formed.
【００３８】上記２つの内面側のＳｉＯＮ系の膜の回折
格子面を相対向させるようにし、ストライプ方向を一致
させ、−１次回折光が回折格子２を通過するような配置
にして、周辺部をエポキシ樹脂でシールした。その後、
常光屈折率１．５２、異常光屈折率１．７９の液晶を注
入し、注入口を同じくエポキシ樹脂で封止して複合異方
性回折素子となる液晶素子を作成した。なお、２枚の基
板とも内面側にはポリイミドの薄膜を設け、格子の長手
方向に沿ってラビングしたものを用いた。このため、液
晶のねじれ角は０°とした。The diffraction grating surfaces of the two SiON-based films on the inner surface are made to face each other, the stripe directions are matched, and the arrangement is such that the −1st-order diffracted light passes through the diffraction grating 2. Sealed with epoxy resin. afterwards,
Liquid crystals having an ordinary light refractive index of 1.52 and an extraordinary light refractive index of 1.79 were injected, and the injection port was similarly sealed with an epoxy resin to prepare a liquid crystal element serving as a composite anisotropic diffraction element. Note that both substrates were provided with a polyimide thin film on the inner surface side and rubbed along the longitudinal direction of the lattice. For this reason, the twist angle of the liquid crystal was set to 0 °.
【００３９】上記液晶素子を用いて図４に示すように、
光ヘッド装置を作成し、光磁気デイスクのカー回転角を
読み取った。Using the above liquid crystal element, as shown in FIG.
An optical head device was prepared, and the car rotation angle of the magneto-optical disk was read.
【００４０】[0040]
【発明の効果】本発明では、光ヘッド装置の光分離回折
素子が単純回折格子と偏光回折格子とを有しており、戻
り光が単純回折格子で回折され、その０次でない回折光
の１つ以上の光が偏光回折格子に入射して回折されるよ
うにされているので、光分離回折素子が小型でかつ容易
に製造できる。According to the present invention, the light separation / diffraction element of the optical head device has a simple diffraction grating and a polarization diffraction grating. Since more than one light is incident on the polarization diffraction grating and diffracted, the light separation / diffraction element can be made small and easy.
【００４１】特に、基板の内外面に凹凸による回折格子
を設け、内部に液晶に代表される光学異方性材料を充填
した複合異方性回折素子を用いることにより、きわめて
小型化できるとともに、その部分については全ての回折
格子が一体化されていることになるので、回折格子の組
立後の調整が不要となる。In particular, the use of a composite anisotropic diffraction element in which a diffraction grating formed by irregularities is provided on the inner and outer surfaces of the substrate and the inside of which is filled with an optically anisotropic material typified by liquid crystal makes it possible to achieve a very small size. Since all the diffraction gratings are integrated in the portion, adjustment after assembly of the diffraction grating is not required.
【００４２】さらに、このように小型で調整不要の光分
離回折素子を用いているので、光ヘッド装置自体も小型
化でき、その部品点数も少ないので組み立ても容易であ
り、さらにその調整も容易になり、生産性も良い。本発
明は、本発明の効果を損しない範囲内で、種々の応用が
できる。Further, the use of such a small and light-adjusting light-separating / diffractive element makes it possible to reduce the size of the optical head device itself, and because the number of parts is small, the assembly is easy and the adjustment is easy. And good productivity. The present invention can be applied to various applications within a range that does not impair the effects of the present invention.
【図１】本発明の複合異方性回折素子の具体的な例の断
面図。FIG. 1 is a cross-sectional view of a specific example of a composite anisotropic diffraction element of the present invention.
【図２】本発明の複合異方性回折素子の他の具体的な例
の断面図。FIG. 2 is a cross-sectional view of another specific example of the composite anisotropic diffraction element of the present invention.
【図３】図１の複合異方性回折素子を用いた光ヘッド装
置の具体的な例の模式図。FIG. 3 is a schematic diagram of a specific example of an optical head device using the composite anisotropic diffraction element of FIG.
【図４】図２の複合異方性回折素子を用いた光ヘッド装
置の具体的な例の模式図。FIG. 4 is a schematic diagram of a specific example of an optical head device using the composite anisotropic diffraction element of FIG. 2;
【図５】従来の光ヘッド装置の例の模式図。FIG. 5 is a schematic view of an example of a conventional optical head device.
回折格子：１、２、３、７ 基板 ：４、５ 液晶 ：６ 光 ：１１〜１６ Diffraction grating: 1, 2, 3, 7 Substrate: 4, 5 Liquid crystal: 6 Light: 11 to 16
Claims (6)
素子を設け、光磁気記録媒体からの戻り光を、光分離回
折素子で２以上の光に分離し、さらにそれらの光を回折
させて光ヘッド装置の駆動制御のための光検出器及び信
号検出のための光検出器に到達するようにした光ヘッド
装置において、光分離回折素子が単純回折格子と偏光回
折格子とを有しており、戻り光が単純回折格子で回折さ
れ、その０次でない回折光の１つ以上の光が偏光回折格
子に入射して回折されることを特徴とする光ヘッド装
置。A light separating and diffractive element is provided between a light source and a magneto-optical recording medium, and a return light from the magneto-optical recording medium is separated into two or more lights by a light separating and diffractive element. In an optical head device that diffracts light to reach a photodetector for drive control of the optical head device and a photodetector for signal detection, the light separation / diffraction element has a simple diffraction grating and a polarization diffraction grating. An optical head device, wherein return light is diffracted by a simple diffraction grating, and at least one of non-zero-order diffracted lights enters a polarization diffraction grating and is diffracted.
次の回折光が、夫々偏光特性の異なる偏光回折格子に入
射して回折される請求項１記載の光ヘッド装置。2. The +1 order and -1 diffracted by a simple diffraction grating.
2. The optical head device according to claim 1, wherein the next diffracted light is incident on and diffracted by polarization diffraction gratings having different polarization characteristics.
凸のある基板を用いた液晶回折格子である請求項１又は
２記載の光ヘッド装置。3. The optical head device according to claim 1, wherein the polarization diffraction grating is a liquid crystal diffraction grating using a substrate having at least one of the substrates having an uneven inner surface.
純回折格子が形成され、３ビームを発生するようにされ
ている請求項１、２又は３記載の光ヘッド装置。4. The optical head device according to claim 1, wherein a simple diffraction grating is also formed on the outer surface of the substrate on the light source side of the light separation / diffraction element to generate three beams.
用い、内部に封入した光学異方性材料との相互作用によ
る偏光回折格子を有する複合異方性回折素子において、
少なくとも一方の基板の外面には凹凸による回折格子が
形成され、この外側の回折格子で回折された光の０次で
ない回折光の１つ以上の光が内面の偏光回折格子に入射
して再度回折されるように配置されたことを特徴とする
複合異方性回折素子。5. A composite anisotropic diffraction element comprising a substrate having at least one surface having irregularities on its inner surface and having a polarization diffraction grating due to interaction with an optically anisotropic material encapsulated therein.
A diffraction grating is formed on at least one of the outer surfaces of the substrate by irregularities, and one or more non-zero-order diffracted lights of the light diffracted by the outer diffraction grating are incident on the inner polarizing diffraction grating and diffracted again. A composite anisotropic diffractive element, wherein
用い、一方の１次の回折光が入射側に凹凸がある偏光回
折格子に、他方の１次の回折光が出射側に凹凸がある偏
光回折格子に入射するように配置された請求項５記載の
複合異方性回折素子。6. A substrate having unevenness on the inner surface for both substrates, one of the first-order diffracted light is provided on a polarization diffraction grating having an unevenness on an incident side, and the other is provided on an emission side. The composite anisotropic diffraction element according to claim 5, wherein the composite anisotropic diffraction element is arranged to be incident on a certain polarization diffraction grating.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22708696A JP3541575B2 (en) | 1996-08-28 | 1996-08-28 | Optical head device and composite anisotropic diffraction element used therefor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22708696A JP3541575B2 (en) | 1996-08-28 | 1996-08-28 | Optical head device and composite anisotropic diffraction element used therefor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH1069673A true JPH1069673A (en) | 1998-03-10 |
| JP3541575B2 JP3541575B2 (en) | 2004-07-14 |
Family
ID=16855288
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP22708696A Expired - Fee Related JP3541575B2 (en) | 1996-08-28 | 1996-08-28 | Optical head device and composite anisotropic diffraction element used therefor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3541575B2 (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2001042824A1 (en) * | 1999-12-08 | 2001-06-14 | Otm Technologies, Ltd. | Improved motion detector and components suitable for use therein |
| EP1437608A1 (en) * | 2001-09-13 | 2004-07-14 | Asahi Glass Company Ltd. | Diffraction device |
| WO2007119773A1 (en) * | 2006-04-12 | 2007-10-25 | Toyo Seikan Kaisha, Ltd. | Structure, forming method of structure, structure forming device, structure color and/or diffraction light reading method, and truth/false discriminating method |
| KR100779693B1 (en) | 2006-08-09 | 2007-11-26 | 주식회사 엘지에스 | Wave selection type diffractive optical elements and optical pickup device has them |
| JP4778662B2 (en) * | 2000-06-29 | 2011-09-21 | パナソニック株式会社 | Optical head device and optical information processing device |
| CN111033118A (en) * | 2017-09-12 | 2020-04-17 | 株式会社Lg化学 | Diffraction light guide plate and method for manufacturing diffraction light guide plate |
-
1996
- 1996-08-28 JP JP22708696A patent/JP3541575B2/en not_active Expired - Fee Related
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2001042824A1 (en) * | 1999-12-08 | 2001-06-14 | Otm Technologies, Ltd. | Improved motion detector and components suitable for use therein |
| JP4778662B2 (en) * | 2000-06-29 | 2011-09-21 | パナソニック株式会社 | Optical head device and optical information processing device |
| JP2011198463A (en) * | 2000-06-29 | 2011-10-06 | Panasonic Corp | Diffractive optical element, optical head device, and optical information processing device |
| EP1437608A1 (en) * | 2001-09-13 | 2004-07-14 | Asahi Glass Company Ltd. | Diffraction device |
| EP1437608A4 (en) * | 2001-09-13 | 2006-07-26 | Asahi Glass Co Ltd | Diffraction device |
| US7430076B2 (en) | 2001-09-13 | 2008-09-30 | Asahi Glass Company, Limited | Diffraction element |
| WO2007119773A1 (en) * | 2006-04-12 | 2007-10-25 | Toyo Seikan Kaisha, Ltd. | Structure, forming method of structure, structure forming device, structure color and/or diffraction light reading method, and truth/false discriminating method |
| US8139292B2 (en) | 2006-04-12 | 2012-03-20 | Toyo Seikan Kaisha, Ltd. | Structural body, a method for reading a structural color and/or diffraction light, and a truth/false discriminating method |
| KR100779693B1 (en) | 2006-08-09 | 2007-11-26 | 주식회사 엘지에스 | Wave selection type diffractive optical elements and optical pickup device has them |
| CN111033118A (en) * | 2017-09-12 | 2020-04-17 | 株式会社Lg化学 | Diffraction light guide plate and method for manufacturing diffraction light guide plate |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3541575B2 (en) | 2004-07-14 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US6271966B1 (en) | Optical head device including an optically anisotropic diffraction grating and process for its production | |
| EP0390610B1 (en) | Optical element and optical pickup device comprising the same | |
| JPH09304748A (en) | Liquid crystal lens and optical head device using the same | |
| JP4792679B2 (en) | Isolator and variable voltage attenuator | |
| JP3541575B2 (en) | Optical head device and composite anisotropic diffraction element used therefor | |
| JP2594548B2 (en) | Polarizing beam splitter | |
| JPH10302291A (en) | Polarization separation element and optical head using the element | |
| JP2002311242A (en) | Polarized light separating element, semiconductor laser unit and optical pickup device | |
| JP3994450B2 (en) | Manufacturing method of optical diffraction grating and optical head device using the same | |
| JP3711652B2 (en) | Polarization diffraction element and optical head device using the same | |
| JPH11306581A (en) | Broadband polarized light separating element and optical head using this broadband polarized light separating element | |
| JP3885251B2 (en) | Optical anisotropic diffraction grating, driving method thereof, and optical head device using the same | |
| JP4168680B2 (en) | Optical head device | |
| JP3947828B2 (en) | Optical head device and manufacturing method thereof | |
| JP2710809B2 (en) | Crossed diffraction grating and polarization rotation detector using the same | |
| JP3509399B2 (en) | Optical head device | |
| JP3713778B2 (en) | Optical head device | |
| JP4179645B2 (en) | Optical head device and driving method thereof | |
| JP2658818B2 (en) | Birefringent diffraction grating polarizer and optical head device | |
| JP4631679B2 (en) | Optical head device | |
| JPH09127335A (en) | Manufacture of optical head device and optical head device | |
| JP3596152B2 (en) | Method of manufacturing optical modulation element and method of manufacturing optical head device | |
| JP4420990B2 (en) | Optical head device | |
| JPH09185837A (en) | Optical head device | |
| JPH09297933A (en) | Optical head device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20031209 |
|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20040205 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20040309 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20040322 |
|
| R150 | Certificate of patent or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20080409 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090409 Year of fee payment: 5 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090409 Year of fee payment: 5 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100409 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100409 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110409 Year of fee payment: 7 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120409 Year of fee payment: 8 |
|
| S531 | Written request for registration of change of domicile |
Free format text: JAPANESE INTERMEDIATE CODE: R313531 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120409 Year of fee payment: 8 |
|
| R371 | Transfer withdrawn |
Free format text: JAPANESE INTERMEDIATE CODE: R371 |
|
| S531 | Written request for registration of change of domicile |
Free format text: JAPANESE INTERMEDIATE CODE: R313531 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120409 Year of fee payment: 8 |
|
| R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130409 Year of fee payment: 9 |
|
| LAPS | Cancellation because of no payment of annual fees |