JPS6149604B2 - - Google Patents
Info
- Publication number
- JPS6149604B2 JPS6149604B2 JP7091085A JP7091085A JPS6149604B2 JP S6149604 B2 JPS6149604 B2 JP S6149604B2 JP 7091085 A JP7091085 A JP 7091085A JP 7091085 A JP7091085 A JP 7091085A JP S6149604 B2 JPS6149604 B2 JP S6149604B2
- Authority
- JP
- Japan
- Prior art keywords
- detection device
- spot position
- position detection
- light spot
- light beam
- 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.)
- Expired
Links
- 238000001514 detection method Methods 0.000 claims description 19
- 238000005259 measurement Methods 0.000 claims description 7
- 239000000284 extract Substances 0.000 claims description 6
- 230000003287 optical effect Effects 0.000 claims description 3
- 230000004907 flux Effects 0.000 claims 4
- 230000001133 acceleration Effects 0.000 description 14
- 238000010586 diagram Methods 0.000 description 5
- 238000006073 displacement reaction Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 230000035945 sensitivity Effects 0.000 description 2
- 239000003990 capacitor Substances 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000012811 non-conductive material Substances 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/30—Measuring arrangements characterised by the use of optical techniques for measuring roughness or irregularity of surfaces
- G01B11/306—Measuring arrangements characterised by the use of optical techniques for measuring roughness or irregularity of surfaces for measuring evenness
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Length Measuring Devices By Optical Means (AREA)
- Optical Recording Or Reproduction (AREA)
Description
【発明の詳細な説明】
〔発明の利用分野〕
本発明は、回転円板の面振れを光学的に測定す
る装置に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an apparatus for optically measuring surface runout of a rotating disk.
従来、回転円板の面振れの測定には、静電容量
型の微小変位計が一般に用いられているが、被測
定面が導電材料から成つている必要があり、ガラ
ス円板にTeなどの非導電材料が蒸着された回転
円板などの面振れは測定することができない。こ
のような被測定面の材料に対する制約を取り除く
ため本発明では、光を面振れ測定用のプローブに
用いている。
Conventionally, capacitance-type micro-displacement meters have been generally used to measure the surface runout of rotating disks, but the surface to be measured must be made of a conductive material, and the glass disk must be made of a material such as Te. It is not possible to measure the surface runout of a rotating disk or the like on which a non-conductive material is deposited. In order to remove such restrictions on the material of the surface to be measured, the present invention uses light as a probe for measuring surface runout.
本発明の目的は、簡単な構成で、測定範囲や測
定感度が被測定面の面振れの大きさにあわせて容
易に調整でき、しかも信頼度の高い面振れ測定装
置を提供することにある。
SUMMARY OF THE INVENTION An object of the present invention is to provide a highly reliable surface runout measuring device that has a simple configuration, has a measurement range and measurement sensitivity that can be easily adjusted according to the magnitude of surface runout on a surface to be measured.
まず、本発明の原理を第１図を用いて説明す
る。第１図において、１は円板で３を中心に矢印
の方向に回転している。光ビーム１００は、円板
１の面にほぼ垂直に入射し、点１０で反射する。
通常反射した光束２００は点１０における面の方
向によつて入射光束１００とは異なつた方向を向
いている。今、点１０を原点として第１図のよう
にｘ，ｙ，ｚ軸をとる。すなわち、ｘは点１０に
おける回転方向、ｙは半径の方向、ｚは円板１の
回転軸の方向である。点１０における接面とｘ軸
となす角をとすると、点１０における円板１の
ｚ軸方向の振れ（上下振れと呼ぶ）の大きさｚと
の間に、
ｄｚ／ｄｘ＝tan
なる関係がある。半径ｒの円板は、一定角速度ω
で回転しているとすれば
ｄｚ／ｄｘ＝１／ｒω ｄｚ／ｄｔ
一方、反射光束２００のｘ軸方向の振れ角をθと
すれば、θ＝２であるから
ｄｚ／ｄｔ＝ｒω・tanθ／２
である。ここで、充分小さな振れ角に対しては
ｄｚ／ｄｔ＝ｒωθ／２
従つて、上下振れの大きさｚは
ｚ＝ｒω／２∫θdt
で与えられる。又、上下振れの加速度αは
αｄ２ｚ／ｄｔ２＝ｒω／２ ｄθ／ｄｔ
で与えられる。
First, the principle of the present invention will be explained using FIG. In FIG. 1, 1 is a disk rotating around 3 in the direction of the arrow. A light beam 100 is incident approximately perpendicularly to the surface of the disk 1 and is reflected at a point 10.
Normally, the reflected light beam 200 is oriented in a different direction than the incident light beam 100, depending on the direction of the surface at the point 10. Now, take the x, y, and z axes as shown in Figure 1 with point 10 as the origin. That is, x is the rotation direction at the point 10, y is the radial direction, and z is the direction of the rotation axis of the disk 1. Assuming that the angle between the tangent surface at point 10 and the x-axis is the magnitude z of the deflection (called vertical deflection) of the disc 1 in the z-axis direction at point 10, there is the relationship dz/dx=tan. be. A disk of radius r has a constant angular velocity ω
If it is rotating at It is 2. Here, for a sufficiently small deflection angle, dz/dt=rωθ/2 Therefore, the magnitude z of the vertical deflection is given by z=rω/2∫θdt. Further, the vertical vibration acceleration α is given by αd 2 z/dt 2 =rω/2 dθ/dt.
このように、反射光束２００の角度θを測定す
れば、それから、上下振れの大きさ及び加速度を
知ることができる。そこで本発明では、ほぼ平行
な光束を回転円板の被測定面にほぼ垂直に入射
し、該被測定面からの反射光束を、入射光束の照
射位置に応じた信号を出力する光点位置検出装置
で受光することにより、入射光束の振れ角を検出
する。そして、第１の発明では、該光点位置検出
装置の出力の積分値を求めることにより、上下振
れの大きさを測定する。その際入射平行光束の傾
きや光点位置検出装置の位置調整ずれ等の影響を
取り除くため、光点位置検出装置の出力の交流成
分を取り出し、この交流成分の積分値を求める。
また、第２の発明では、上下振れの大きさに加え
て、光点位置検出装置の出力の微分値を求めて上
下振れの加速度を測定し、上下振れの大きさ及び
加速度を測定する。上下振れの大きさ及び加速度
の測定は、自動焦点制御系の設計に不可欠な要素
である。すなわち、上下振れの大きさは、自動焦
点用アクチユエータのストロークを設定するため
に必要であり、一方、上下振れ加速度は自動焦点
用アクチユエータの推力を設定するために必要で
あり、自動焦点用アクチユエータの推力は上下振
れ加速度より大きくする必要がある。 In this way, by measuring the angle θ of the reflected light beam 200, it is possible to know the magnitude and acceleration of vertical vibration. In view of this, in the present invention, a light spot position detection method is adopted in which a substantially parallel light beam is incident almost perpendicularly on the surface to be measured of a rotating disk, and the reflected light beam from the surface to be measured is outputted as a signal corresponding to the irradiation position of the incident light beam. By receiving the light with the device, the deflection angle of the incident light beam is detected. In the first invention, the magnitude of vertical vibration is measured by determining the integral value of the output of the light spot position detection device. At this time, in order to eliminate the influence of the inclination of the incident parallel light beam, the positional adjustment deviation of the light spot position detection device, etc., the AC component of the output of the light spot position detection device is extracted, and the integral value of this AC component is determined.
Further, in the second invention, in addition to the magnitude of the vertical vibration, the acceleration of the vertical vibration is measured by determining the differential value of the output of the light spot position detection device, and the magnitude and acceleration of the vertical vibration are measured. Measuring the magnitude of vertical vibration and acceleration is an essential element in the design of an automatic focus control system. That is, the magnitude of the vertical runout is necessary to set the stroke of the autofocus actuator, while the vertical runout acceleration is necessary to set the thrust of the autofocus actuator, and the magnitude of the vertical runout is necessary to set the stroke of the autofocus actuator. The thrust needs to be greater than the vertical vibration acceleration.
以下、実施例により本発明を説明する。第２図
は、本発明による測定装置の一実施例を示す構成
図である。図に於て１は回転円板で、２は被測定
面である。３は回転中心で、４は、円板１を回転
させるためのモータである。５は、ほぼ平行な光
束を出射する光源、例えばHe−Neレーザあるい
は半導体レーザである。光源５から出た平行光束
は、偏光プリズム６で反射し、円板１の面２にほ
ぼ垂直な方向に向けられてλ／４板７を通つて、
面２の点１０に入射する。点１０における面の方
向に従つてわずかに向きをかえられた反射光束
は、λ／４板７、偏向プリズム６を通つて光点位
置検出器８に入射する。光点位置検出器８は、反
射光束２００の位置９に応じて出力端子２０Ａ，
２０Ｂに電流が流れ、抵抗Ｒによつて電圧が発生
する。この電圧の差ＶABは、光点９の変位量をｘ
（通常、光点位置検器８の中心でｘ＝０）、光点位
置検出器８の電流感度をαとすると
ＶAB＝Ｒ・α・ｘ
となる。光ビーム２００の変位量ｘは、光ビーム
２００のふれ角をθ（第１図の定義による）、測
定点１０から光点位置検出器８までの距離をｌと
すれば、θが充分小さい時は
ｘ＝ｌθ
となる。
The present invention will be explained below with reference to Examples. FIG. 2 is a configuration diagram showing an embodiment of the measuring device according to the present invention. In the figure, 1 is a rotating disk, and 2 is a surface to be measured. 3 is a rotation center, and 4 is a motor for rotating the disc 1. Reference numeral 5 denotes a light source that emits a substantially parallel light beam, such as a He--Ne laser or a semiconductor laser. The parallel light beam emitted from the light source 5 is reflected by the polarizing prism 6, directed in a direction substantially perpendicular to the surface 2 of the disk 1, and passes through the λ/4 plate 7.
It is incident on point 10 on surface 2. The reflected light beam whose direction is slightly changed according to the direction of the surface at the point 10 passes through the λ/4 plate 7 and the deflection prism 6 and enters the light spot position detector 8 . The light spot position detector 8 outputs output terminals 20A and 20A depending on the position 9 of the reflected light beam 200.
A current flows through 20B, and a voltage is generated by the resistor R. This voltage difference V AB is the displacement amount of the light spot 9 x
(Normally, x=0 at the center of the light spot position detector 8), and if α is the current sensitivity of the light spot position detector 8, then V AB =R·α·x. If the deflection angle of the light beam 200 is θ (according to the definition in FIG. 1) and the distance from the measurement point 10 to the light spot position detector 8 is l, then the displacement amount x of the light beam 200 is calculated as follows when θ is sufficiently small. becomes x=lθ.
測定円板の回転数をω、測定点１０の半径r′と
すれば、先に述べた原理によつて、この円板の測
定面２の上下振れ量ｚの時間微分は
ｄｚ／ｄｔ＝ｒ′ω／２・ＶＡＢ／ｌＲα
となる。従つて、電圧の差ＶABを積分すれば、上
下振れ量ｚが求められるが、普通ＶABは、直流成
分を持つており、単純に積分すると、時間ととも
に発散し不都合である。ＶABの直流成分を発生さ
せる原因は、入射ビーム１００のわずかな傾むき
や光点位置検出器８の位置調整のわずかなずれな
どによつており、完全に、直流成分を０にするこ
とは、ほとんど不可能に近い。このような不都合
を取り除くため、電圧差ＶABの交流成分のみを取
り出すようにする必要がある。 If the rotational speed of the measuring disk is ω and the radius of the measuring point 10 is r', then according to the principle mentioned above, the time differential of the vertical runout z of the measuring surface 2 of this disk is dz/dt=r ′ω/2·V AB /lRα. Therefore, if the voltage difference V AB is integrated, the amount of vertical deviation z can be obtained, but V AB usually has a DC component, and if it is simply integrated, it will diverge over time, which is inconvenient. The causes of the DC component of V AB are due to the slight inclination of the incident beam 100 and the slight deviation in the position adjustment of the light spot position detector 8, and it is impossible to completely reduce the DC component to 0. , almost impossible. In order to eliminate this inconvenience, it is necessary to take out only the alternating current component of the voltage difference V AB .
第３図に、光点位置検出器８の出力から、上下
振れ量、および上下振れ加速度を検出する回路構
成を示す。第３図において２１は差動増巾器で、
先に述べたＶABを発生させる回路である。２２，
２３は、コンデンサーと抵抗で、直流成分をカツ
トすることが目的であり、いわゆる微分回路であ
るが、その時定数１／RCは、測定円板の回転周
期より充分大きく取る必要がある。この出力３０
Ａは、上下振れ量の速度変動を表わしている。２
４および２５は、それぞれ積分回路、および微分
回路であり、３０Ｂおよび３０Ｃは、上下振れ量
および上下振れ加速度に比例した出力が得られ
る。それぞれの比例定数は、ｒ，ω，ｌ，Ｒ，
α、および回転定数など、全て既知の量から求め
ることができる。すなわち、本実施例によれば、
上下振れ量および上下振れ加速度の絶対値の測定
が容易に行なえる。なお、本実施例では、上下振
れ加速度を測定するため、直流成分をカツトし交
流成分を取り出す回路の出力の微分値を得ている
が、この回路の時定数１／RCは測定円板の回転
周期より充分大きくとつてあり、微分値検出に悪
さをしないようになつている。すなわち、上下振
れの周波数は、回転周期以上であるので、交流成
分を取り出す回路の出力の微分値でも、上下振れ
加速度を正確に測定できるものである。 FIG. 3 shows a circuit configuration for detecting the amount of vertical vibration and the acceleration of vertical vibration from the output of the light spot position detector 8. In Fig. 3, 21 is a differential amplifier;
This is a circuit that generates the V AB mentioned earlier. 22,
23 is a so-called differential circuit whose purpose is to cut off the DC component using a capacitor and a resistor, but its time constant 1/RC must be sufficiently larger than the rotation period of the measuring disk. This output 30
A represents the speed fluctuation of the amount of vertical runout. 2
4 and 25 are an integrating circuit and a differentiating circuit, respectively, and 30B and 30C provide outputs proportional to the amount of vertical vibration and the vertical vibration acceleration. The respective proportionality constants are r, ω, l, R,
α, rotation constant, etc. can all be determined from known quantities. That is, according to this embodiment,
The absolute value of vertical runout amount and vertical runout acceleration can be easily measured. In this example, in order to measure the vertical vibration acceleration, the differential value of the output of a circuit that cuts the DC component and extracts the AC component is obtained, but the time constant 1/RC of this circuit is dependent on the rotation of the measurement disk. It is set to be sufficiently larger than the period, so that it does not impair differential value detection. That is, since the frequency of the vertical vibration is greater than the rotation period, the vertical vibration acceleration can be accurately measured even with the differential value of the output of the circuit that extracts the alternating current component.
さらに、測定面２の反射率のムラや光源５の強
度の変動などの影響をなくすために、第４図に示
した回路を用いる。すなわち、第４図は２０Ａ，
２０Ｂの出力電圧Ｖ20A，Ｖ20Bの差ＶABと和V+
を、差動増巾器２１と加算回路２６によつて発生
させ、割り算回路２７によつてＶAB／V+に比例
する出力ｖを端子Duより取り出す回路であり、
第３図の差動増巾器２１のかわりに用いる。V+
は、光位置検出器８の特性により、光ビーム２０
０の光量に比例しているから、反射率のむらや光
源の強度変化などの影響を全く受けなくなる。ま
た、このようにすると被測定面２の蒸着膜の種類
が異なるような円板の上下振れを測定するような
場合でも、反射率の違いによる測定値の補正を行
なう必要がなく、どのような円板であつてもつね
に上下振れ量、および上下振れ加速度の絶対値を
得ることができる。 Furthermore, in order to eliminate the effects of uneven reflectance on the measurement surface 2 and fluctuations in the intensity of the light source 5, the circuit shown in FIG. 4 is used. That is, Fig. 4 shows 20A,
20B output voltage V 20A , V 20B difference V AB and sum V +
is generated by a differential amplifier 21 and an adder circuit 26, and an output v proportional to V AB /V + is taken out from a terminal Du by a divider circuit 27.
It is used in place of the differential amplifier 21 in FIG. V +
Due to the characteristics of the optical position detector 8, the light beam 20
Since it is proportional to the amount of light at 0, it is completely unaffected by uneven reflectance or changes in the intensity of the light source. In addition, in this way, even when measuring the vertical runout of a disk with different types of vapor deposited films on the surface to be measured 2, there is no need to correct the measured values due to the difference in reflectance. It is possible to always obtain the vertical runout amount and the absolute value of the vertical runout acceleration for a disc.
以上の如く本発明によれば、光を用いて回転円
板の面振れを測定するので被測定面の材料に対す
る制約が少なく、しかも検出器出力の交流成分を
用いるので、入射光束の傾むきや光点位置検出器
の位置ずれに強く、調整が容易な装置で信頼度の
高い面振れ測定を行なえる。
As described above, according to the present invention, since the surface runout of the rotating disk is measured using light, there are fewer restrictions on the material of the surface to be measured, and since the alternating current component of the detector output is used, the inclination of the incident light beam is Highly reliable surface runout measurement can be performed with a device that is resistant to positional deviation of the light spot position detector and is easy to adjust.
第１図は、本発明の原理を説明するための図、
第２図は、本発明の一実施例の構成図、第３図
は、第２図に示した実施例の装置から、上下振れ
量および上下振れ加速度を算出する回路を示す構
成図。第４図は、被測定面の反射率のムラや光源
の光量変化などの影響を取り除く回路を示す構成
図である。
FIG. 1 is a diagram for explaining the principle of the present invention,
FIG. 2 is a block diagram of an embodiment of the present invention, and FIG. 3 is a block diagram showing a circuit for calculating the vertical runout amount and vertical runout acceleration from the apparatus of the embodiment shown in FIG. FIG. 4 is a configuration diagram showing a circuit that eliminates the effects of uneven reflectance of the surface to be measured and changes in the amount of light from the light source.
Claims (1)
の照射位置に応じた信号を出力する光点位置検出
装置と、該平行光束を回転円板の被測定面にほぼ
垂直に入射し、該被測定面からの反射光束を上記
光点位置検出装置に導く光学系と、上記光点位置
検出装置の出力の交流成分を取り出す回路と、該
交流成分の積分値を取り出す回路とを具備したこ
とを特徴とする回転円板の面振れ測定装置。 ２ 上記光点位置検出装置は、上記固射光束を受
光して電気信号に変換する光検出器と、該光検出
器からの２つの出力によつて該光検出器に入射す
る上記反射光束の該光検出器の中心位置に対する
ずれを示す信号を得る差動手段とからなることを
特徴とする特許請求の範囲第１項記載の面振れ測
定装置。 ３ 上記光点位置検出装置は、上記光検出器の２
つの出力の和を得る手段と、この手段の出力と上
記差動手段の出力の比を得る手段とを有すること
を特徴とする特許請求の範囲第２項記載の面振れ
測定装置。 ４ ほぼ平行な光束を出射する光源と、入射光束
の照射位置に応じた信号を出力する光点位置検出
装置と、該平行光束を回転円板の被測定面にほぼ
垂直に入射し、該被測定面からの反射光束を上記
光点位置検出装置に導く光学系と、上記光点位置
検出装置の出力の交流成分を取り出す回路と、該
交流成分の積分値を取り出す回路と、上記光点位
置検出装置の出力の微分値を取り出す回路とを具
備したことを特徴とする回転円板の面振れ測定装
置。 ５ 上記光点位置検出装置は、上記反射光束を受
光して電気信号に変換する光検出器と、該光検出
器からの２つの出力によつて該光検出器に入射す
る上記反射光束の該光検出器の中心位置に対する
ずれを示す信号を得る差動手段とからなることを
特徴とする特許請求の範囲第４項記載の面振れ測
定装置。 ６ 上記光点位置検出装置は、上記光検出器の２
つの出力の和を得る手段と、この手段の出力と上
記差動手段の出力の比を得る手段とを有すること
を特徴とする特許請求の範囲第５項記載の面振れ
測定装置。[Scope of Claims] 1. A light source that emits a substantially parallel light beam, a light spot position detection device that outputs a signal according to the irradiation position of the incident light beam, and a light spot position detection device that outputs a signal according to the irradiation position of the incident light beam, and a light source that emits a substantially parallel light beam approximately perpendicular to a surface to be measured of a rotating disk. an optical system that guides the reflected light flux from the surface to be measured to the light spot position detection device, a circuit that extracts an alternating current component of the output of the light spot position detection device, and a circuit that extracts an integral value of the alternating current component. A surface runout measuring device for a rotating disk, characterized by comprising: 2. The light spot position detection device includes a photodetector that receives the fixed light flux and converts it into an electrical signal, and a light spot position detection device that detects the reflected light flux incident on the photodetector by two outputs from the photodetector. 2. The surface runout measuring device according to claim 1, further comprising differential means for obtaining a signal indicating the deviation of the photodetector from the center position. 3 The above-mentioned light spot position detection device
3. The surface runout measuring device according to claim 2, further comprising means for obtaining the sum of two outputs, and means for obtaining a ratio between the output of this means and the output of said differential means. 4 A light source that emits a substantially parallel light beam; a light spot position detection device that outputs a signal according to the irradiation position of the incident light beam; an optical system that guides the reflected light flux from the measurement surface to the light spot position detection device; a circuit that extracts the alternating current component of the output of the light spot position detection device; a circuit that extracts the integral value of the alternating current component; and the light spot position. 1. A surface runout measuring device for a rotating disk, comprising a circuit for extracting a differential value of an output of a detection device. 5. The light spot position detection device includes a photodetector that receives the reflected light beam and converts it into an electrical signal, and detects the position of the reflected light beam incident on the photodetector using two outputs from the photodetector. 5. The surface runout measuring device according to claim 4, further comprising differential means for obtaining a signal indicating a deviation from the center position of the photodetector. 6 The above-mentioned light spot position detection device
6. The surface runout measuring device according to claim 5, further comprising means for obtaining the sum of two outputs, and means for obtaining a ratio between the output of this means and the output of said differential means.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7091085A JPS60227105A (en) | 1985-04-05 | 1985-04-05 | Measuring instrument for surface deflection |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7091085A JPS60227105A (en) | 1985-04-05 | 1985-04-05 | Measuring instrument for surface deflection |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP791086A Division JPS61228306A (en) | 1986-01-20 | 1986-01-20 | Surface deflection measuring device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60227105A JPS60227105A (en) | 1985-11-12 |
| JPS6149604B2 true JPS6149604B2 (en) | 1986-10-30 |
Family
ID=13445139
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7091085A Granted JPS60227105A (en) | 1985-04-05 | 1985-04-05 | Measuring instrument for surface deflection |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60227105A (en) |
-
1985
- 1985-04-05 JP JP7091085A patent/JPS60227105A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60227105A (en) | 1985-11-12 |
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