JPH0291840A - Magneto-optical detector - Google Patents
Magneto-optical detectorInfo
- Publication number
- JPH0291840A JPH0291840A JP24104988A JP24104988A JPH0291840A JP H0291840 A JPH0291840 A JP H0291840A JP 24104988 A JP24104988 A JP 24104988A JP 24104988 A JP24104988 A JP 24104988A JP H0291840 A JPH0291840 A JP H0291840A
- Authority
- JP
- Japan
- Prior art keywords
- output
- magneto
- magnetic disk
- optical
- magnetic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 230000003287 optical effect Effects 0.000 claims abstract description 13
- 238000001514 detection method Methods 0.000 claims description 18
- 230000010287 polarization Effects 0.000 claims description 10
- 230000000694 effects Effects 0.000 claims description 9
- 230000003321 amplification Effects 0.000 claims description 3
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 3
- 230000000903 blocking effect Effects 0.000 claims 1
- 230000005374 Kerr effect Effects 0.000 abstract description 9
- 238000011156 evaluation Methods 0.000 abstract description 5
- 238000005259 measurement Methods 0.000 description 4
- 230000008033 biological extinction Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 238000006073 displacement reaction Methods 0.000 description 2
- 230000003993 interaction Effects 0.000 description 2
- 230000005415 magnetization Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000001066 destructive effect Effects 0.000 description 1
- 230000005389 magnetism Effects 0.000 description 1
- 238000003908 quality control method Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/012—Recording on, or reproducing or erasing from, magnetic disks
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B33/00—Constructional parts, details or accessories not provided for in the other groups of this subclass
- G11B33/10—Indicating arrangements; Warning arrangements
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、磁性膜の磁気特性評価装置に係わり特に光と
磁気の相互作用である光磁気効果（カー効果）を応用し
て、磁気ディスクの磁気特性分布を、非接触、非破壊、
しかも迅速に測定するのに好適な光磁気検出装置に関す
る。Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an apparatus for evaluating the magnetic properties of a magnetic film, and in particular applies the magneto-optical effect (Kerr effect), which is the interaction between light and magnetism, to evaluate magnetic disks. magnetic property distribution, non-contact, non-destructive,
Moreover, the present invention relates to a magneto-optical detection device suitable for rapid measurement.
光磁気効果（カー効果〕の検出手段は、従来から光磁気
ディスク装置の光磁気再生法として利用されている。光
磁気再生は、レーザと磁性媒体との光磁気相互作用によ
るレーザ光の偏光面の微小変位を検出することによりな
される。かかる微小変位の検出には、例えば、差動検出
法が、光源からのノイズを抑えた光磁気検出法としてよ
く用いられている。なお、この種の技術は、「磁気記録
技術」日本工業技術センター（昭ｓ８） Ｐ、 ６６２
〜Ｐ、６６５に記載がある。Detection means for the magneto-optical effect (Kerr effect) have traditionally been used as a magneto-optical reproducing method for magneto-optical disk drives.Magneto-optical reproducing is based on the polarization plane of laser light due to magneto-optical interaction between a laser and a magnetic medium. This is done by detecting minute displacements.For the detection of such minute displacements, for example, the differential detection method is often used as a magneto-optical detection method that suppresses noise from the light source. The technology is "Magnetic Recording Technology" Japan Industrial Technology Center (S8) P, 662
~P, 665.
上記従来技術の差動検出法では、光源に起因するノイズ
の影響を完全には避けられない欠点がある。これに加え
て、光磁気検出信号が極めて微弱である場合には、精度
よく磁気情報を検出する点で問題があった。The conventional differential detection method described above has the drawback that it cannot completely avoid the influence of noise caused by the light source. In addition to this, when the magneto-optical detection signal is extremely weak, there is a problem in accurately detecting magnetic information.
光磁気再生法は、媒体を透過、或いは媒体表面で反射し
た光の偏光面の回転が、磁化の向きによりて異なるファ
ラデー効果、カー効果を利用する。The magneto-optical reproduction method utilizes the Faraday effect and the Kerr effect, in which the rotation of the polarization plane of light transmitted through a medium or reflected on the surface of the medium differs depending on the direction of magnetization.
例えば、カー効果による磁気情報の検出を、第２図に示
す光読み出しの原理に従って説明する。For example, detection of magnetic information using the Kerr effect will be explained according to the principle of optical readout shown in FIG.
同図において、Ｐは入射光の偏光方向、Ａは検光子（ア
ナライザ）の偏光方向である。磁化の向きに対応した偏
光面の回転をθ鮨θ−９偏光面をｉ＋−一とし、アナラ
イザの設定角を入射偏光方向と直交する位置（消光位置
）からφとする。膜の反射率をＲ１入射光強度をＰｏと
すれば、ＲＰｏがアナライザに入射する光強度となり、
＆＋、Ｌ−に対するアナライザ透過後の光強度１＋、
Ｉ−は、Ｉ ｔｈ−ＲＰｏ ｇｈｉ” （φ±θ）（１
）となる、しかるに、φ−θとすれば、！−を０にでき
るので、アナライザ透過後の出力光の変化は、最大コン
トラストになると考えられる。しかし、実際にはＩ−は
０にはならない、その理由は、２つの偏光子の偏光方向
を直交させたときの出力光の入射光に対する場合、すな
わち消光比ＥがＯにならないからである。実際の光学系
では、媒体や光学素子が間に入るので、消光比Ｅはさら
に悪化する。このため、光検出器の出力電流Ｉ＋は、１
＋−μａｐｔｐｏ Ｉｇｈｉ” ＜φ＋θ） ＋ Ｅ
１ （２１となる。ここで、μは検出器感度、Ｃ
は増幅器の利得である。（２）式に示すように、Ｅ項に
よる出力は、θに関係せず光源に含まれる雑音を含むな
ど、雑音源となるので好ましくない。この為、従来、差
動検出法を用いて、このＥ項をキャンセルすることが行
われているが、（２）式のＰｏの代わりにその変動Δｐ
、を代入した分だけの雑音が残ってしまう。In the figure, P is the polarization direction of the incident light, and A is the polarization direction of the analyzer. The rotation of the plane of polarization corresponding to the direction of magnetization is θ-9, and the plane of polarization is i+-1, and the set angle of the analyzer is φ from the position perpendicular to the incident polarization direction (extinction position). If the reflectance of the film is R1 and the incident light intensity is Po, then RPo is the light intensity incident on the analyzer,
&+, light intensity 1+ after passing through the analyzer for L-,
I- is I th-RPoghi” (φ±θ)(1
), but if φ−θ, then ! Since - can be set to 0, it is thought that the change in output light after passing through the analyzer will have the maximum contrast. However, in reality, I- does not become 0, because when the polarization directions of the two polarizers are orthogonal to each other, the extinction ratio E does not become 0 when the output light is relative to the incident light. In an actual optical system, the extinction ratio E is further deteriorated because a medium and an optical element are interposed. Therefore, the output current I+ of the photodetector is 1
+−μaptpo Ighi” <φ+θ) + E
1 (21, where μ is the detector sensitivity, C
is the gain of the amplifier. As shown in equation (2), the output due to the E term is undesirable because it includes noise included in the light source regardless of θ and becomes a noise source. For this reason, conventionally, a differential detection method has been used to cancel this E term, but instead of Po in equation (2), its variation Δp
, remains as much as the noise.
しかも、差動検出法では、光学系が複雑になるばかりで
なく、光学系、増幅器のアンバランスのために、Ｅ項を
完全に除去できないなど、精度のよい光磁気検出を行う
には問題がありた。Moreover, the differential detection method not only requires a complicated optical system, but also has problems in achieving accurate magneto-optical detection, such as the inability to completely remove the E term due to imbalance in the optical system and amplifier. There was.
本発明の目的は、光磁気効果の測定において、光学系を
複雑にすることなく、光源の出力変動の影響を除去する
光磁気検出手段を提供することにある。SUMMARY OF THE INVENTION An object of the present invention is to provide a magneto-optical detection means that eliminates the influence of output fluctuations of a light source in the measurement of magneto-optical effects without complicating the optical system.
上記目的は、検出信号の増幅段に微分器を接続すること
により達成される。The above object is achieved by connecting a differentiator to the amplification stage of the detection signal.
光検出器の増幅段に結合した微分器は、交流成分だけを
通過させ、直流成分を阻止するだけでなく、光源の動作
状態のゆりくりし変動に起因するノイズと、直流成分と
同Ｉｌ！に抑えるように動作する。The differentiator coupled to the amplification stage of the photodetector not only passes only the alternating current component and blocks the direct current component, but also eliminates noise due to gradual fluctuations in the operating state of the light source and the same Il! It works to keep it in check.
微分器は、また、入力電圧の時間変化の割合に比例した
出力電圧を得るので、磁場掃引に基づく光磁気信号のヒ
ステリシス変化の検出において、偏光面のカー回転によ
る信号の変化分を強調して取り出すことができる。The differentiator also obtains an output voltage proportional to the rate of time change of the input voltage, so when detecting hysteresis changes in magneto-optical signals based on magnetic field sweeps, it is possible to emphasize changes in the signal due to Kerr rotation of the plane of polarization. It can be taken out.
以下、本発明の一実施例を図面にもとすいて説明する。 An embodiment of the present invention will be described below with reference to the drawings.
第１図は、本発明の一実施例を示す磁気ディスク評価装
置の構成図である。同図において、レーザ光源１から出
力したレーザビーム２は、偏光子３で直線偏光となり、
集光レンズ４により磁気ディスク５に入射する。次に、
磁気ディスク５で微小に偏光した反射光６は、レンズ７
、検光子８を経て、検出器９で検出される。FIG. 1 is a block diagram of a magnetic disk evaluation apparatus showing an embodiment of the present invention. In the figure, a laser beam 2 output from a laser light source 1 becomes linearly polarized by a polarizer 3,
The light is incident on the magnetic disk 5 through the condensing lens 4 . next,
The reflected light 6 that has been slightly polarized by the magnetic disk 5 is passed through a lens 7.
, and is detected by a detector 9 after passing through an analyzer 8.
上記光学系で検出された光磁気信号１ｏは、増幅器１１
に接続した微分器１２で、磁場発生装置１３′ＶＣよる
掃引磁場にともなったヒステリシス変化分が強調された
後、デジタルストレージオシロスコープ１４からホスト
コンピュータ１５に転送される。但し、磁気ディスク面
に磁場を印加する磁場発生装置１３は、磁場掃引３１に
ともなった磁場発生装置自身の変形が、光磁気信号の検
出に影響しないために、光学系と独立して設置しである
。尚、本実施例では、磁場発生装置としてワイス形磁石
を用いた。次に、ホストコンピュータ１５は、取り込ん
だ信号の波形を図示すると共に、保磁力（ｇｃ）、角形
比などの磁気特性を計算表示する。更に、ホストコンピ
ュータ１５は、駆動系１６を制御し、測定位置をずらし
て上記操作を繰り返すことにより、磁気ディスクの磁気
特性分布マツプを作成する。The magneto-optical signal 1o detected by the optical system is transmitted to the amplifier 11
The differentiator 12 connected to the magnetic field generator 13' VC emphasizes the hysteresis change caused by the swept magnetic field, and then the data is transferred from the digital storage oscilloscope 14 to the host computer 15. However, the magnetic field generator 13 that applies a magnetic field to the magnetic disk surface cannot be installed independently of the optical system so that the deformation of the magnetic field generator itself caused by the magnetic field sweep 31 will not affect the detection of the magneto-optical signal. be. In this example, a Weiss magnet was used as the magnetic field generator. Next, the host computer 15 graphically illustrates the waveform of the captured signal, and calculates and displays magnetic properties such as coercive force (gc) and squareness ratio. Furthermore, the host computer 15 controls the drive system 16, shifts the measurement position, and repeats the above operations to create a magnetic property distribution map of the magnetic disk.
本発明によれば、光磁気効果（カー効果〕を応用した磁
気ディスク評価装置において、光磁気効果によるヒステ
リシス変化分を強調した光磁気信号が、光源雑音の影響
を抑えて検出されるので、光学系を複雑にすることなく
高精度、高Ｓ／Ｎ比での測定が可能となる。According to the present invention, in a magnetic disk evaluation device that applies the magneto-optical effect (Kerr effect), a magneto-optical signal that emphasizes the hysteresis change due to the magneto-optical effect is detected while suppressing the influence of light source noise. Measurement with high accuracy and high S/N ratio is possible without complicating the system.
上記の磁気ディスク評価装置では、磁気ディスクを破壊
することなく磁気特性分布を、非接触で迅速に測定でき
る。従りて、本装置をインラインの測定装置として利用
すれば、磁気ディスクの品質管理を容易にし、歩留まり
の向上に大きく貢献する。The magnetic disk evaluation device described above can quickly measure the magnetic property distribution in a non-contact manner without destroying the magnetic disk. Therefore, if this device is used as an in-line measuring device, it will facilitate quality control of magnetic disks and greatly contribute to improving yield.
第１図は本発明の一実施例の磁気ディスク評価装置の構
成図、第２図は光磁気再生における光読み出しの原理図
である。
１・・・・・・・・−・・レーザ光源
２・・・・・・・・・・−・レーザビーム３・・・・・
・・・−・・偏光子
４・・・・・・・・・・・・集光レンズ５・・・・・・
・・・・・・磁気ディスク６・・・・・・・・・・・・
反射ビーム０１０１０８６．０．、、レンズ
・・・・・・・・・・・・検光子
・・・・・・・・・・・・光検出器
・・・・・・・・・光磁気信号
・・・・・・・・・増幅器
・・・・・・・・・微分器
・・・・・−・・磁場発生装置
・・・・・・・・・デジタルストレージオシロスコープ
・・・・・・・・・ホストコンピュータ・・・・・−・
・円板駆動部
・・・・・・・・・レコーダFIG. 1 is a block diagram of a magnetic disk evaluation apparatus according to an embodiment of the present invention, and FIG. 2 is a diagram showing the principle of optical reading in magneto-optical reproduction. 1........- Laser light source 2........- Laser beam 3...
...... Polarizer 4 ...... Condensing lens 5 ...
・・・・・・Magnetic disk 6・・・・・・・・・・・・
Reflected beam 0101086.0. , Lens・・・・・・・・・Analyzer・・・・・・・・・Photodetector・・・・・・・Optical magnetic signal・・・・・・・・・Amplifier・・・・・・・・・Differentiator・・・・−・・Magnetic field generator・・・・・・・・・Digital storage oscilloscope・・・・・・・・・Host computer・・・・・・・－・
・Disk drive unit・・・・・・Recorder
Claims (1)
手段と、前記磁気ディスク面に磁場を印加する磁場発生
装置と、前記磁気ディスク面からの反射光の偏光状態を
検出する光検出手段からなる光学系において、光検出器
の増幅段に微分器を接続して検出信号を微分することに
より光源の動作状態に起因するノイズ成分を阻止すると
共に、光磁気効果による信号の変化分を強調して取り出
すことを特徴とする光磁気検出装置。1. A focusing means for focusing polarized laser light on a magnetic disk surface, a magnetic field generator for applying a magnetic field to the magnetic disk surface, and a light detection means for detecting the polarization state of light reflected from the magnetic disk surface. In this optical system, a differentiator is connected to the amplification stage of the photodetector to differentiate the detection signal, thereby blocking noise components caused by the operating status of the light source and emphasizing changes in the signal due to magneto-optical effects. A magneto-optical detection device characterized by a magneto-optical detection device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24104988A JPH0291840A (en) | 1988-09-28 | 1988-09-28 | Magneto-optical detector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24104988A JPH0291840A (en) | 1988-09-28 | 1988-09-28 | Magneto-optical detector |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0291840A true JPH0291840A (en) | 1990-03-30 |
Family
ID=17068550
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP24104988A Pending JPH0291840A (en) | 1988-09-28 | 1988-09-28 | Magneto-optical detector |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0291840A (en) |
-
1988
- 1988-09-28 JP JP24104988A patent/JPH0291840A/en active Pending
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