JPH0375505A - Extraction of interference fringe - Google Patents
Extraction of interference fringeInfo
- Publication number
- JPH0375505A JPH0375505A JP21163789A JP21163789A JPH0375505A JP H0375505 A JPH0375505 A JP H0375505A JP 21163789 A JP21163789 A JP 21163789A JP 21163789 A JP21163789 A JP 21163789A JP H0375505 A JPH0375505 A JP H0375505A
- Authority
- JP
- Japan
- Prior art keywords
- image
- interference fringes
- picked
- images
- reference value
- 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
- 238000000605 extraction Methods 0.000 title claims 2
- 238000005259 measurement Methods 0.000 claims abstract description 22
- 230000003287 optical effect Effects 0.000 claims abstract description 22
- 239000007787 solid Substances 0.000 claims description 17
- 238000003384 imaging method Methods 0.000 claims description 16
- 238000005305 interferometry Methods 0.000 claims 1
- 230000015654 memory Effects 0.000 abstract description 12
- 238000000034 method Methods 0.000 description 6
- 238000000691 measurement method Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 238000003672 processing method Methods 0.000 description 2
- 206010041662 Splinter Diseases 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
Landscapes
- Instruments For Measurement Of Length By Optical Means (AREA)
- Length Measuring Devices By Optical Means (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、光干渉式測定システムにおいて、被測定面の
撮像後に、画像処理によって撮像画面から実体像を残し
て干渉縞を抽出する方法に関する。[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for extracting interference fringes by leaving a solid image on the imaging screen through image processing after imaging a surface to be measured in an optical interference measurement system. .
光干渉式測定システム例えば面精度測定法は、等厚干渉
を利用して、実体像上の干渉縞の本数や輪郭それらの分
布状況を観測し、表面の微細形状を評価するために利用
される。このような光学的な測定法は、いずれも、被測
定物に対し非接触状態で測定できること、表面状態を直
接肉眼で観測できることなどの特徴がある。Optical interferometric measurement systems, such as the surface accuracy measurement method, use equal thickness interference to observe the number and contours of interference fringes on a stereoscopic image and their distribution, and are used to evaluate the fine shape of the surface. . All of these optical measurement methods have characteristics such as being able to measure the object to be measured without contacting it, and being able to directly observe the surface state with the naked eye.
通常、干渉縞は、被測定面の実体像上に明度差として現
れるが、明瞭でないため、明暗の縞の識別は、この種の
計測で困難な作業である。Normally, interference fringes appear as a difference in brightness on a solid image of a surface to be measured, but because they are not clear, distinguishing between bright and dark fringes is a difficult task in this type of measurement.
C発明の目的〕
したがって、本発明の目的は、光干渉式測定システムに
おいて、被測定面の撮像画面から実体像と干渉縞とを同
じ位置関係のまま分離し、干渉縞を抽出する画像処理的
な手法を提供し、計測の容易化を図ることである。C. Object of the Invention] Therefore, an object of the present invention is to provide an image processing method for separating a solid image and interference fringes from an imaging screen of a surface to be measured while maintaining the same positional relationship and extracting interference fringes in an optical interference measurement system. The objective is to provide a method that facilitates measurement.
光干渉式測定システムは、例えばマイケルソン干渉計の
原理によって、干渉縞を発生させて、その干渉縞の乱れ
具合から表面の仕上げ程度を観測する。この場合、干渉
縞は、被測定面の上に重なった状態となっている。この
観測時に、被測定面または基準反射面に光学系の焦点深
度の方向に微小な移動量が与えられるならば、干渉縞は
、視野平面内で縞ピッチの方向に移動する。The optical interference measurement system generates interference fringes based on the principle of a Michelson interferometer, for example, and observes the degree of surface finish from the degree of disturbance of the interference fringes. In this case, the interference fringes are superimposed on the surface to be measured. During this observation, if a small amount of movement is given to the surface to be measured or the reference reflective surface in the direction of the depth of focus of the optical system, the interference fringes will move in the direction of the fringe pitch within the viewing plane.
本発明は、この点に着目し、被測定面または基償反射面
を光学系の焦点深度の方向に微小な量だけ移動させ、そ
の移動の前後で被測定面およびその上の干渉縞を撮像す
る。このあと、本発明は、画像処理によって、両者の撮
像画面上の対応画素の明度差と基準値とを比較し、この
比較の大小結果に応じて、その画素を実体像または干渉
縞として識別していく。Focusing on this point, the present invention moves the surface to be measured or the reference reflective surface by a minute amount in the direction of the depth of focus of the optical system, and images the surface to be measured and the interference fringes thereon before and after the movement. do. After that, the present invention uses image processing to compare the brightness difference of corresponding pixels on both imaging screens with a reference value, and identifies the pixel as a solid image or an interference fringe depending on the magnitude of this comparison. To go.
このように、両者の撮影画面で、変化のない部分を実体
像とし、また変化のある部分を干渉縞とすることによっ
て、撮影画面上から実体像と干渉縞とが画像処理によっ
て分離できることになる。In this way, by using the unchanged portions of both shooting screens as the solid image and the changing portions as the interference fringes, the solid image and interference fringes can be separated from the shooting screen through image processing. .
第1図は、光干渉式測定システム1の構成を示している
。FIG. 1 shows the configuration of an optical interferometric measurement system 1. As shown in FIG.
光源2は、光干渉に適切な波長例えば5000(A)の
測定光3を発生し、ビームスプリンタ4、対物レンズ5
を経て被測定面6に照射するとともに、対物レンズ7を
経て、基準反射面8にも照射し、反射光として、被測定
面6に照射し、その被測定面6および基準反射面8から
の反射光がビームスプリッタ4上で重なった際に干渉し
表面で干渉縞を発生させる。なお、この実施例で、基準
反射面8は、振動子9によって固定部分に取り付けられ
ており、光学系の焦点深度の方向に振動により微小な移
動量だけ移動できるようになっている。A light source 2 generates measurement light 3 with a wavelength suitable for optical interference, for example, 5000 (A), and a beam splinter 4 and an objective lens 5.
The light is irradiated onto the surface to be measured 6 via the objective lens 7, and is also irradiated onto the reference reflective surface 8 as reflected light. When the reflected lights overlap on the beam splitter 4, they interfere and generate interference fringes on the surface. In this embodiment, the reference reflecting surface 8 is attached to a fixed part by a vibrator 9, and can be moved by a small amount of movement by vibration in the direction of the depth of focus of the optical system.
そして、この移動量は、測定時の測定光3のl/4波長
程度の値に設定される。The amount of movement is set to a value of approximately 1/4 wavelength of the measurement light 3 at the time of measurement.
被測定面6の実体像およびその干渉縞は、工業用テレビ
10によって撮像され、画像メモリ11に記憶される。A solid image of the surface to be measured 6 and its interference fringes are captured by an industrial television 10 and stored in an image memory 11.
そして、画像処理装置12は、本発明に基づくプログラ
ムを内蔵しており、画像メモリ11のデータを読み込み
、画像モニタ13に撮像画面を表示するほか、本発明に
よる画像処理のプログラムに基づいて、画像処理を行い
、撮像画面から実体像と干渉縞とを分離し、それぞれの
メモリ14.15に記憶させていく。The image processing device 12 has a built-in program based on the present invention, and in addition to reading data from the image memory 11 and displaying the captured screen on the image monitor 13, it also processes images based on the image processing program according to the present invention. Processing is performed to separate the solid image and the interference fringes from the image capture screen, and store them in the respective memories 14 and 15.
第2図は、本発明の動作順序を示している。FIG. 2 shows the operating sequence of the present invention.
まず、最初に、工業用テレビlOは、被測定面6の像お
よび基準反射面からの反射光による干渉縞を光学系の焦
点深度方向の微小な移動量の前後で撮像し、第3図(1
1(2)のような2つの撮像画面を画像メモリ11に記
憶させる。2回の撮像の前後で、光学系は、測定光3の
波長に応した微小な移動! (1/4波長程度)で、光
学系の焦点深度の方向に移動している。そして、この微
小な移動量は、振動子9を用い、基準反射面8に積極的
な振動を与えることによって、または通常の測定環境の
微弱な外部振動を消極的に利用することによって与えら
れる。もちろん、これらの微小な移動量は、光学系の焦
点深度の範囲内であるから、被測定面6の結像状態に影
響せず、撮影画質上無視できる。なお、2つの撮像画面
は、移動の前後となるように、振動周期を考慮して撮像
され、工業用テレビ10のフレーム速度を尺度とすると
、はぼ連続している。First, the industrial television IO captures the image of the surface to be measured 6 and the interference fringes caused by the reflected light from the reference reflective surface before and after a small amount of movement of the optical system in the depth of focus direction. 1
Two imaging screens such as 1 and 2 are stored in the image memory 11. Before and after the two images are taken, the optical system moves minutely according to the wavelength of the measurement light 3! (about 1/4 wavelength), and is moving in the direction of the focal depth of the optical system. This small amount of movement can be provided by actively applying vibration to the reference reflecting surface 8 using the vibrator 9, or by passively using the weak external vibration of the normal measurement environment. Of course, these small amounts of movement are within the range of the depth of focus of the optical system, so they do not affect the imaging state of the surface to be measured 6 and can be ignored in terms of image quality. Note that the two imaging screens are taken in consideration of the vibration period so as to be before and after the movement, and are approximately continuous if the frame rate of the industrial television 10 is used as a measure.
仮に測定光3の波長が5000(A)であり、光学系の
焦点深度方向の移動量が振動の全振幅として0.1〔μ
m〕であるとき、焦点深度は振動の振幅よりも充分に大
きいため、撮像画面の合焦状態は、移動の前後で変化し
ない。しかし、干渉縞は、第3図(1) (2)に例示
するように、視野の平面内で縞ピッチの半分近く移動す
る。視野内の干渉縞の本数が視野内で数本ないし10数
本現れる光学倍率で撮影したと過程すれば、視野ピッチ
の半分近くの移動は、画像上非常に大きな変化となって
・現れる。ここで、前述の通り、2回目の干渉縞が最初
の干渉縞の間にくるのが最良と考えられるため、最適な
移動量は、測定光3の1/4波長程度である。Suppose that the wavelength of measurement light 3 is 5000 (A), and the amount of movement of the optical system in the depth of focus direction is 0.1 [μ
m], the depth of focus is sufficiently larger than the amplitude of the vibration, so the in-focus state of the imaging screen does not change before and after the movement. However, as illustrated in FIGS. 3(1) and 3(2), the interference fringes move approximately half the fringe pitch within the plane of the field of view. If the photograph is taken at an optical magnification such that the number of interference fringes within the field of view is several to ten or more, a movement of nearly half the field of view pitch will appear as a very large change in the image. Here, as described above, it is considered best for the second interference fringe to be between the first interference fringes, so the optimal movement amount is about 1/4 wavelength of the measurement light 3.
このように、はぼ連続して微小な移動量の前後で撮像さ
れた両者の撮像画面では、静止状態の被測定面の実体像
の上に振動状態の干渉縞が重なっており、両者の撮像画
面の明度変化の少ない部分は、実体像であり、また明度
変化の多い部分は、移動前後の干渉縞である。In this way, in the two images taken almost continuously before and after a small amount of movement, the interference fringes in the vibration state are superimposed on the solid image of the measured surface in the stationary state, and the two images are The portion of the screen with little change in brightness is the real image, and the portion with much change in brightness is the interference fringes before and after movement.
そこで、画像処理装置12は、両者の撮像画面の対応画
素の明度差と、画像の明度特性に応じて予め設定した基
準値とを比較していく。両者の撮像画面の対応画素の明
度差が基準以下であれば、その画素は、実体像と判別さ
れる。そこで、画像処理装置12は、実体像用のメモリ
14にいずれかの実体像レベルを記憶させるか、または
それらの平均値を記憶させ、また干渉縞用のメモリ15
に干渉縞レベルとして例えば白に相当する値を代入する
。また明度差が基準以上であるとき、その画素は干渉縞
と判別される。そこで、画像処理装置12は、実体像用
のメモリ14にいずれかの明るいレベルの値を入れ、ま
た干渉縞用のメモリ15に暗いレベルを代入していく。Therefore, the image processing device 12 compares the difference in brightness between the corresponding pixels of the two imaging screens with a reference value set in advance according to the brightness characteristics of the images. If the difference in brightness between corresponding pixels on both imaging screens is less than the standard, that pixel is determined to be a real image. Therefore, the image processing device 12 causes the memory 14 for stereoscopic images to store one of the stereoscopic image levels or their average value, and also stores the memory 15 for interference fringes.
For example, a value corresponding to white is substituted into the interference fringe level. Furthermore, when the brightness difference is equal to or greater than the reference value, the pixel is determined to be an interference fringe. Therefore, the image processing device 12 inputs one of the bright level values into the memory 14 for the stereoscopic image, and also substitutes the dark level value into the memory 15 for interference fringes.
このようにして、画像処理装置I2は、以上の手順で、
両者の撮像画面の全画素を例えば走査方向に処理してい
き、第3図の(31(41のように、縞のない実体像と
干渉縞を主体とした画面とを分離状態で再現していく。In this way, the image processing device I2 performs the steps described above.
All pixels of both imaging screens are processed, for example, in the scanning direction, and a solid image without fringe and a screen mainly composed of interference fringes are reproduced in a separated state, as shown in (31 (41) in Fig. 3). go.
このようにして、両者の撮像画面から実体像と干渉縞の
像とが分離状態で得られる。In this way, the real image and the interference fringe image are obtained in a separated state from both imaging screens.
以上の説明は、干渉縞が白地に黒い線で現れる場合を想
定しており、画像処理上、白黒レベルが反転した場合に
は、明暗の判断を逆に設定する。The above explanation assumes that interference fringes appear as black lines on a white background, and when the black and white level is reversed in image processing, the determination of brightness and darkness is set to be reversed.
また、干渉縞画面抽出時に、そのまま2値化することも
可能であるが、干渉縞は、すでに述べた通り、多く不鮮
明であり、他の画像処理の手法による特徴づけの併用を
考慮して、干渉縞をそのままの明るさで抽出する方式で
説明した。しかし、必要によって、予め2値化すること
も可能である。It is also possible to binarize the image as it is when extracting the interference fringe screen, but as mentioned above, many of the interference fringes are unclear, so considering the combination of characterization using other image processing methods, We have explained the method of extracting interference fringes with their original brightness. However, if necessary, it is also possible to perform binarization in advance.
干渉縞の抽出時に、両画面のそれぞれがら取り出すと、
干渉縞の本数が2倍近くなることもおき得るので、必要
に応じて、両者の撮像画面のうち例えば後画面のほうが
暗いときにのみ干渉縞用のメモリ15へ取り出すことに
より、いずれが一方のみの干渉縞を抽出することも可能
である。When extracting interference fringes, if you take out each piece of both screens,
Since the number of interference fringes may nearly double, if necessary, by retrieving them to the interference fringes memory 15 only when, for example, the rear screen of both imaging screens is darker, it is possible to eliminate which one is the only one. It is also possible to extract interference fringes.
本発明では、はぼ連続して撮像された2つの画面の対応
画素の明度差と基準値との比較結果によって、被測定面
の実体像および干渉縞とが画像処理の分野で分離でき、
はぼ同質の画像の比較であるから処理の合理化が図れる
ほか、実体画像とこれに対応する干渉縞とが別画像とし
て観測できるため、干渉縞の本数や輪郭またその縞ピッ
チなどの計測が容易となる。In the present invention, the solid image of the surface to be measured and the interference fringes can be separated in the field of image processing based on the results of comparison between the brightness difference of corresponding pixels of two screens imaged more or less continuously and a reference value.
In addition to streamlining the processing since the comparison is made between images of substantially the same quality, the actual image and the corresponding interference fringes can be observed as separate images, making it easy to measure the number of interference fringes, their contours, and the pitch of their fringes. becomes.
また、撮像過程で、光学系、基準反射面または被測定面
に焦点深度の方向の微小な移動を利用する方式のため、
通常干渉縞の計測で特に、嫌がられる外部振動に対して
も、移動量が焦点深度の範囲内であれば実体像と干渉縞
との分離を可能にできる。In addition, because the method uses minute movements in the direction of the depth of focus in the optical system, reference reflective surface, or measured surface during the imaging process,
Even in the case of external vibrations, which are generally disliked in the measurement of interference fringes, it is possible to separate the real image and interference fringes as long as the amount of movement is within the depth of focus.
第1図は測定システムのブロック線図、第2図は本発明
の測定方法のフローチャート図、第3図は2つの撮像画
面と分離後の実体像および干渉縞の説明図である。
1・・光干渉式測定システム、2・・光源、3・・測定
光、4・・ビームスプリッタ、5・・対物レンズ、6・
・被測定面、7・・対物レンズ、8・・基準反射面、9
・・振動子、10・・工業用テレビ、11・・画像メモ
リ、12・・画像処理装置、13・・画像モニタ、14
.15・・メモリ。
特 許 出 願人株式会社日平トヤマ
代 理 人 弁理士 中 川 國 男第
2
図
第
図
r7ノ
r2ノ
r3ノ
r4ノFIG. 1 is a block diagram of the measurement system, FIG. 2 is a flowchart of the measurement method of the present invention, and FIG. 3 is an explanatory diagram of two imaging screens, a separated solid image, and interference fringes. 1. Optical interference measurement system, 2. Light source, 3. Measurement light, 4. Beam splitter, 5. Objective lens, 6.
・Measurement surface, 7. Objective lens, 8. Reference reflective surface, 9.
... Vibrator, 10... Industrial TV, 11... Image memory, 12... Image processing device, 13... Image monitor, 14
.. 15...Memory. Patent Applicant Nippei Toyama Co., Ltd. Agent Patent Attorney Kunio Nakagawa Figure 2 Figure r7, r2, r3, r4
Claims (1)
の画像を光学系の焦点深度方向で測定光の波長に応じた
微小な移動量の前後で撮像し、両者の撮像画面上の対応
画素の明度差と基準値とを比較し、基準値以下の明度差
の画素を実体像と判断し、実体像用の画面上で同画素を
実体像レベルとして記憶し、かつ干渉縞用の画面上で同
画素を干渉縞レベルとして記憶し、また基準値以上の明
度差の画素を干渉縞と判断し、明度の高い方の値を実体
像用の画面上で同画素を実体像レベルとして記憶し、か
つ干渉縞用の画面上で明度の低い方の値を同画素を干渉
縞レベルとして記憶することを特徴とする干渉縞の抽出
方法。In an optical interferometry measurement system, images of the surface to be measured including interference fringes are captured before and after a minute movement according to the wavelength of the measurement light in the focal depth direction of the optical system, and the corresponding pixels on both imaging screens are The brightness difference is compared with a reference value, and pixels with a brightness difference less than the reference value are determined to be a solid image, and the same pixels are stored as a solid image level on the screen for the solid image, and the pixels are stored on the screen for the interference fringe. The same pixel is stored as an interference fringe level, and a pixel with a brightness difference of more than a reference value is determined to be an interference fringe, and the value with higher brightness is stored as a solid image level for the same pixel on the screen for a solid image, An interference fringe extraction method characterized in that the lower brightness value on the screen for interference fringes is stored as the interference fringe level for the same pixel.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP21163789A JP2847536B2 (en) | 1989-08-17 | 1989-08-17 | Interference fringe extraction method |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP21163789A JP2847536B2 (en) | 1989-08-17 | 1989-08-17 | Interference fringe extraction method |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH0375505A true JPH0375505A (en) | 1991-03-29 |
JP2847536B2 JP2847536B2 (en) | 1999-01-20 |
Family
ID=16609077
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP21163789A Expired - Lifetime JP2847536B2 (en) | 1989-08-17 | 1989-08-17 | Interference fringe extraction method |
Country Status (1)
Country | Link |
---|---|
JP (1) | JP2847536B2 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US10957472B2 (en) | 2015-10-15 | 2021-03-23 | Suncall Corporation | Method for manufacturing shunt resistor |
-
1989
- 1989-08-17 JP JP21163789A patent/JP2847536B2/en not_active Expired - Lifetime
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US10957472B2 (en) | 2015-10-15 | 2021-03-23 | Suncall Corporation | Method for manufacturing shunt resistor |
US11488750B2 (en) | 2015-10-15 | 2022-11-01 | Suncall Corporation | Shunt resistor |
Also Published As
Publication number | Publication date |
---|---|
JP2847536B2 (en) | 1999-01-20 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US10771697B2 (en) | Still image stabilization/optical image stabilization synchronization in multi-camera image capture | |
CN105453133B (en) | Image processing apparatus and method, eye fundus image processing unit, image capturing method and eye fundus image filming apparatus and method | |
CN108562541B (en) | Lensless holographic microscopic speckle noise removing method and device based on matrix decomposition | |
KR940010960B1 (en) | Orthosteroscopic image system | |
JPH08160305A (en) | Laser scanning microscope | |
TWI500963B (en) | An image capturing device and method | |
JPH048996B2 (en) | ||
JP3794744B2 (en) | Focusing surface detection method, image input / output device, and optical microscope | |
KR20210047486A (en) | Method for Obtaining Image with High Speed Based on Lensless Camera | |
US4620223A (en) | Interferometric deformation analysis system | |
CN109003228A (en) | A kind of micro- big visual field automatic Mosaic imaging method of dark field | |
DE112020002180T5 (en) | NORMAL INCIDENCE PHASE-SHIFT DEFLECTOMETRY SENSOR, SYSTEM AND METHOD FOR INSPECTING A SURFACE OF A SAMPLE | |
US5054925A (en) | Method for aligning an interferometer | |
JP3783813B2 (en) | Confocal microscope | |
JPH0375505A (en) | Extraction of interference fringe | |
JPH08289329A (en) | Stereoscopic image pickup device | |
JP3488762B2 (en) | Image processing apparatus and image processing method | |
JP7362324B2 (en) | Inspection method, manufacturing method and inspection device for image display device | |
JPH08254499A (en) | Displaying/appearance inspection device | |
JPH0518714A (en) | Speckle image displacement measuring apparatus | |
JP3652014B2 (en) | Distance measuring device | |
JP3851395B2 (en) | Optical member inspection apparatus and optical member inspection method | |
JP2009031323A (en) | Eyepiece barrel of microscope and microscope system | |
JPS6139018A (en) | Device for entering three-dimensional information of substance in optical microscope | |
JP2014142213A (en) | Photographing parameter determination device and control method of the same |