WO1987003957A1 - Opto-electronic process for inspecting surfaces - Google Patents

Opto-electronic process for inspecting surfaces Download PDF

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Publication number
WO1987003957A1
WO1987003957A1 PCT/CH1986/000175 CH8600175W WO8703957A1 WO 1987003957 A1 WO1987003957 A1 WO 1987003957A1 CH 8600175 W CH8600175 W CH 8600175W WO 8703957 A1 WO8703957 A1 WO 8703957A1
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WO
WIPO (PCT)
Prior art keywords
filters
information
disturbances
principle
electronic
Prior art date
Application number
PCT/CH1986/000175
Other languages
German (de)
French (fr)
Inventor
Wilfried Schoeps
Original Assignee
Sin/Schweiz. Institut Für Nuklearforschung
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Sin/Schweiz. Institut Für Nuklearforschung filed Critical Sin/Schweiz. Institut Für Nuklearforschung
Publication of WO1987003957A1 publication Critical patent/WO1987003957A1/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • 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
    • G01B11/303—Measuring arrangements characterised by the use of optical techniques for measuring roughness or irregularity of surfaces using photoelectric detection means

Definitions

  • the aim of the invention is to detect and localize very small disturbances in solid and liquid surfaces.
  • the method is suitable for. For example, very good - in order to detect faults already during the production process (in-line) and to intervene in the process if necessary (regulation).
  • the speed of the inspection is practically only limited by the mechanical movement of the material to be inspected.
  • Figure 1 shows an example of a measuring channel.
  • a measuring channel In principle, it is a modified Schlieren optics.
  • the emitted light is parallellated from a point-shaped light source 1 with the aid of a parabolic mirror 2. It passes through a beam splitter 3, then the strip mirror 4 and falls perpendicularly onto the surface to be examined 7. If the surface is completely smooth and without any interferences, the light from 7 will travel back the same way through the open strips of «4 and at the beam splitter 3 divided and a part fall on the detector 5. If there is a disturbance 9 (elevation) on the surface 7, the light is deflected in the region of the elevation or its edges. Part of the light now falls on the playful strips 4 and is deflected to the detector 6. If the disturbance involves many very small increases v (roughness), then instead of one or a few light beams, many of these are deflected. It is therefore possible to use the described method to obtain information about the basic roughness as well as individual disturbances in surfaces.
  • v
  • FIG. 2 shows schematically the structure of a measuring channel with a possible arrangement of different filters for information processing.
  • An alternating current generator 15 drives the punctiform lamp 1.
  • the measuring channel 10 with the detectors 5 and 6 corresponds to the arrangement described above in FIG. cause a difference or a division of the two detector signals 5 and 6.
  • the filters 12 and 13 can be narrowband amplifiers, tuned to the frequency of the generator 15.
  • the evaluation circuit 14 removes the carrier frequency of the generator 15 and supplies the information about a possible disturbance under the measuring channel on the surface 7 to be examined.
  • Figure 3 shows an arrangement like Figure 2, which has an additional detector 16 for detecting holes.
  • the signal of 16 is processed in a similar manner to the signals of 5 and 6.
  • Figure 4 shows the known method of synchronous demodulation.
  • the generator 15 is coupled to the evaluation circuit 14.
  • the information about the faults from the evaluation circuit 14 can be used for the monitoring, display, storage, regulation and automation by means of suitable electronic / information technology apparatus.

Abstract

The process enables the inspection of large solid or liquid surfaces for the presence of microscopically small defects at a very high measurement speed. It is characterized by the use of several or many measurement channels (schlieren optics) and by processing the information on defects on or in the surface investigated by means of suitable, possibly multi-stage, filters. It is thus possible to achieve measurement sensitivities and speeds which were hitherto impossible.

Description

OPT0/ELEKTR0NISCHES VERFAHREN ZUR INSPEKTION VON OBERFLAECHENOPT0 / ELECTRICAL METHOD FOR INSPECTING SURFACES
Das Ziel der Erfindung ist es sehr kleine Störungen in festen und flüssigen Oberflächen zu erkennen und zu lokalisieren.The aim of the invention is to detect and localize very small disturbances in solid and liquid surfaces.
Durch die Anordnung mehrerer oder vieler Messkanäle kann man eine prakisch unbegrenzte Oberfläche inspizieren.By arranging several or many measuring channels, a practically unlimited surface can be inspected.
Das Verfahren eignet sich z. Bsp. sehr gut-, um Störungen schon während des Produktionsprozesses (in-line) zu erkennen und gegebenenfalls in den Prozess einzugreifen (Regelung).The method is suitable for. For example, very good - in order to detect faults already during the production process (in-line) and to intervene in the process if necessary (regulation).
Da das Verfahren, wie nachstehend an einigen Beispielen erläutert, keinerlei bewegte mechanische Teile verwendet, ist die Geschwindigkeit der Inspektion praktisch nur durch die mechanische Bewegung des zu inspizierenden Materials begrenzt.Since the method does not use any moving mechanical parts, as will be explained below using some examples, the speed of the inspection is practically only limited by the mechanical movement of the material to be inspected.
In Bild 1 ist beispielgebend ein Messkanal dargestellt. Im Prinzip handelt es sich um eine abgewandelte Schlierenoptik. Von einer punktfβrmigen Lichtquelle 1 wird das ausgesendete Licht mit Hilfe eines Parabolspiegels 2 paralellisiert. Es durchläuft einen Strahlteiler 3, ansschliessend den Streifenspiegel 4 und fällt senkrecht auf die zu untersuchende Oberfläche 7. Wenn die Oberfläche gänzlich glatt und ohne Störungen ist, wird das Licht von 7 durch die offenen Streifen von «4 den gleichen Weg wieder zυrflcklaufen und am Strahlteiler 3 geteilt und ein Teil auf den Detektor 5 fallen. Befindet sich auf der Oberfläche 7 eine Störung 9 (Erhöhung), so vird im Bereich der Erhöhung oder deren Kanten das Licht abgelenkt. Ein Teil des Lichtes fällt jetzt auf die verspielten Streifen 4 und vird zum Detektor 6 abgelenkt. Handelt es sich bei der StOrung um viele sehr kleine ErhOhungenv(Rauhigkeit), so verden statt eines oder einiger Lichtstrahlen viele solche ausgelenkt. Es ist somit möglich die beschriebene Methode dazu zu benutzen, um Informationen Ober die Grundrauhigkeit wie auch einzelner Störungen in Oberflächen zu erhalten.Figure 1 shows an example of a measuring channel. In principle, it is a modified Schlieren optics. The emitted light is parallellated from a point-shaped light source 1 with the aid of a parabolic mirror 2. It passes through a beam splitter 3, then the strip mirror 4 and falls perpendicularly onto the surface to be examined 7. If the surface is completely smooth and without any interferences, the light from 7 will travel back the same way through the open strips of «4 and at the beam splitter 3 divided and a part fall on the detector 5. If there is a disturbance 9 (elevation) on the surface 7, the light is deflected in the region of the elevation or its edges. Part of the light now falls on the playful strips 4 and is deflected to the detector 6. If the disturbance involves many very small increases v (roughness), then instead of one or a few light beams, many of these are deflected. It is therefore possible to use the described method to obtain information about the basic roughness as well as individual disturbances in surfaces.
Bild 2 zeigt schematisch den Aufbau eines Messkanals mit einer möglichen Anordnung verschiedener Filter zur Informationsaufbereitung. Ein Wechselstromgenerator 15 treibt die punktfβr ige Lampe 1. Der Messkanal 10 mit den Detektoren 5 und 6 entspricht der oben beschriebenen Anordnung von Bild 1. Das Filter 11 kann z.Bsp. eine Differenz oder eine Division der beiden Detektorsignale 5 und 6 bewirken. Die Filter 12 und 13 kOnnen schmalbandige Verstärker, auf die Frequenz des Generators 15 abgestimmt, sein. Die Auswerteschaltung 14 (Demodulator) entfernt die Trägerfrequenz des Generators 15 und liefert die Information Ober eine βgliche StOrung unter dem Messkanal auf der zu untersuchenden Oberfläche 7.Figure 2 shows schematically the structure of a measuring channel with a possible arrangement of different filters for information processing. An alternating current generator 15 drives the punctiform lamp 1. The measuring channel 10 with the detectors 5 and 6 corresponds to the arrangement described above in FIG. cause a difference or a division of the two detector signals 5 and 6. The filters 12 and 13 can be narrowband amplifiers, tuned to the frequency of the generator 15. The evaluation circuit 14 (demodulator) removes the carrier frequency of the generator 15 and supplies the information about a possible disturbance under the measuring channel on the surface 7 to be examined.
Bild 3 zeigt eine Anordnung wie Bild 2, die einen zusätzlichen Detektor 16 zur Erfassung von LOchern besitzt. Das Signal von 16 wird auf ähnliche Art und Weise aufgearbeitet wie die Signale von 5 und 6.Figure 3 shows an arrangement like Figure 2, which has an additional detector 16 for detecting holes. The signal of 16 is processed in a similar manner to the signals of 5 and 6.
In Bild 4 ist das bekannte Verfahren der Synchron-Demodulation dargestellt. Der Generator 15 ist Bit der Auswerteschaltung 14 gekoppelt. Die Information Ober die Störungen aus der Auswerteschaltung 14 kann fflr die Ueberwachung, Anzeige, Speicherung, Regelung und Automatisierung mittels geeigneter elektronischer/informations¬ technischer Apparate verwendet werden.Figure 4 shows the known method of synchronous demodulation. The generator 15 is coupled to the evaluation circuit 14. The information about the faults from the evaluation circuit 14 can be used for the monitoring, display, storage, regulation and automation by means of suitable electronic / information technology apparatus.
Mit dem beschriebenen Verfahren lässt sich eine wesentliche Steigerung der Messempfindlichkeit erreichen und gleichzeitig die Messgeschwindigkeit sehr stark steigern.With the described method, a significant increase in measuring sensitivity can be achieved and at the same time the measuring speed can be increased very strongly.
Bei mehr- oder vielkanaligen Anordnungen fflr grosse zu untersuchende Oberflächen hat man zusätzlich eine gewisse Redundanz, da bei Ausfall eines Messkanals zumindest mit den anderen weiterhin gemessen werden kann. Dieses Prinzip ist z.Bsp. in der Natur sehr weit verbreitet. Wenn man fflr die Messkanäle und die Informationsaufbereitung die heute üblichen Technologien anwendet, so ergeben sich auch sehr kostengüns ige Lösungen. In the case of multi-channel or multi-channel arrangements for large surfaces to be examined, there is also a certain redundancy, since if one measuring channel fails, measurements can continue to be made with the others. This principle is e.g. very widespread in nature. If one uses the usual technologies for the measurement channels and the information processing, then very cost-effective solutions result.

Claims

OPTO/ELEKTRONISCHES VERFAHREN ZUR INSPEKTION VON OBERFLAECHENPatentansprüche OPTO / ELECTRONIC METHOD FOR INSPECTING SURFACE PATENT CLAIMS
1. Verfahren zur Inspektion von grossen Oberflächen, dadurch gekennzeichnet, dass sehr kleine Objekte, Störungen, Irregularitäten, Rauhigkeiten etc., nachfolgend Störungen genannt, mit sehr grosser Geschwindigkeit erkannt werden kβnnen.1. Method for the inspection of large surfaces, characterized in that very small objects, disturbances, irregularities, roughness etc., hereinafter referred to as disturbances, can be recognized at a very high speed.
2. Verfahren nach Anspruch 1. Dadurch gekennzeichnet, dass die inspizierten Oberflächen festen oder auch flüssigen Charakter haben kOnnen.2. The method according to claim 1. characterized in that the inspected surfaces can have a solid or liquid character.
3. Verfahren nach Ansprüchen 1. und 2. Dadurch gekennzeichnet, dass verschiedene physikalische Prinzipien in geeigneter Art und Weise (mehrstufig) kombiniert werden, um eine bisher nicht erreichte Messempfindlichkeit zu erreichen.3. The method according to claims 1 and 2, characterized in that different physical principles are combined in a suitable manner (in several stages) in order to achieve a measurement sensitivity that has not been achieved before.
4. Verfahren nach Ansprüchen 1. bis 3. Dadurch gekennzeichnet, dass die zu untersuchende Oberfläche und die Störungen optisch mittels eines oder mehrerer Messkanäle, bestehend aus einer Schlierenoptik und eines oder mehreren opto/elektronischen Detektoren beobachtet werden und dass die enthaltene Information über die Störungen mittels eines oder mehrerer zusätzlicher elektronischer Informationsfilters zur Erhöhung der Messempfindlichkeit aufgearbeitet wird.4. The method according to claims 1 to 3, characterized in that the surface to be examined and the disturbances are observed optically by means of one or more measuring channels, consisting of a Schlieren lens system and one or more opto / electronic detectors, and that the information contained about the disturbances is worked up by means of one or more additional electronic information filters to increase the measurement sensitivity.
5. Verfahren nach Ansprflchen 1. bis 4. Dadurch gekennzeichnet, dass es sich bei den Informationsfiltern nach Anspruch 4., um Filter handelt, die die Information von einem oder von mehreren Detektor-Signalen aufarbeiten. Die Filter kOnnen folgender Art sein: nach dem Prinzip der Differenz- und Summenbildung, nach dem Prinzip der Division/Multiplikation (Normalisierung) nach dem Prinzip der Interferenzbildung, nach dem Prinzip der schmalbandigen Trägerfrequenztechnik, nach dem Prinzip der Synchron - Demodulation. Alle Filter können Verstärker enthalten.5. The method according to claims 1 to 4, characterized in that the information filters according to claim 4 are filters which process the information from one or more detector signals. The filters can be of the following types: according to the principle of difference and sum formation, according to the principle of division / multiplication (normalization) according to the principle of interference formation, according to the principle of narrowband carrier frequency technology, according to the principle of synchronous demodulation. All filters can contain amplifiers.
6. Verfahren nach Ansprflchen 1. bis 5. Dadurch gekennzeichnet, dass die zu untersuchenden Oberflächen sich mit sehr grosser Geschwindigkei , nur durch die Geschwindigkeit des bewegten Materials begrenzt, an der bei den Ansprflchen 4. und 5. erwähnten Anordnung vorbei bewegen können, da das Verfahren keinerlei mechanisch bewegten Teile benutzt.6. Method according to claims 1 to 5, characterized in that the surfaces to be examined are limited at a very high speed, only by the speed of the material being moved, past the arrangement mentioned in claims 4 and 5, since the process does not use any mechanically moving parts.
7. Verfahren nach Ansprüchen 1. bis 6. Dadurch gekennzeichnet, dass die erhaltene Information über die Störungen zur Ueberwachung, Anzeige, Speicherung, Regelung und Automatisierung mittels geeigneter elektronischer/informationstechnischer Apparate verwendet werden kann. 7. The method according to claims 1 to 6, characterized in that the information received about the disturbances for monitoring, display, storage, regulation and automation can be used by means of suitable electronic / information technology apparatus.
PCT/CH1986/000175 1985-12-17 1986-12-15 Opto-electronic process for inspecting surfaces WO1987003957A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH536385A CH669663A5 (en) 1985-12-17 1985-12-17
CH5363/85-2 1985-12-17

Publications (1)

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WO1987003957A1 true WO1987003957A1 (en) 1987-07-02

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EP (1) EP0250490A1 (en)
AU (1) AU6726987A (en)
CH (1) CH669663A5 (en)
WO (1) WO1987003957A1 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2626383A1 (en) * 1988-01-27 1989-07-28 Commissariat Energie Atomique CONFOCAL CONFIGURED OPTICAL MICROSCOPY METHOD WITH SCAN AND DEPTH OF EXTENDED FIELD AND DEVICES FOR IMPLEMENTING THE METHOD
WO1990005297A1 (en) * 1988-10-31 1990-05-17 Schweizerische Eidgenossenschaft Psi Paul Scherrer Institut A device for the simultaneous contactless testing of a plurality of points on a test sample and its application
US5357283A (en) * 1989-01-19 1994-10-18 Tesler Vladimir E Reflected modulated television system

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10125751C2 (en) * 2001-05-18 2003-04-03 Willing Gmbh Dr Ing Luminaire for sampling surfaces

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
LU56099A1 (en) * 1967-05-18 1970-01-14
US3736065A (en) * 1972-05-09 1973-05-29 Philco Ford Corp Radiation sensitive means for detecting optical flaws in glass
GB2025041A (en) * 1978-06-27 1980-01-16 Domtar Inc Graininesssensor
FR2491615A1 (en) * 1980-10-04 1982-04-09 Gast Theodor OPTOELECTRONIC MEASUREMENT METHOD AND DEVICES FOR DETERMINING THE QUALITY OF DIFFUSED REFLECTION SURFACES
DE3428435A1 (en) * 1984-08-01 1986-02-06 Erwin Sick Gmbh Optik-Elektronik, 7808 Waldkirch Roughness probe

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
LU56099A1 (en) * 1967-05-18 1970-01-14
US3736065A (en) * 1972-05-09 1973-05-29 Philco Ford Corp Radiation sensitive means for detecting optical flaws in glass
GB2025041A (en) * 1978-06-27 1980-01-16 Domtar Inc Graininesssensor
FR2491615A1 (en) * 1980-10-04 1982-04-09 Gast Theodor OPTOELECTRONIC MEASUREMENT METHOD AND DEVICES FOR DETERMINING THE QUALITY OF DIFFUSED REFLECTION SURFACES
DE3428435A1 (en) * 1984-08-01 1986-02-06 Erwin Sick Gmbh Optik-Elektronik, 7808 Waldkirch Roughness probe

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2626383A1 (en) * 1988-01-27 1989-07-28 Commissariat Energie Atomique CONFOCAL CONFIGURED OPTICAL MICROSCOPY METHOD WITH SCAN AND DEPTH OF EXTENDED FIELD AND DEVICES FOR IMPLEMENTING THE METHOD
EP0327425A1 (en) * 1988-01-27 1989-08-09 Commissariat A L'energie Atomique Method for optical scanning microscopy in confocal arrangement with large depth of field and apparatus to perform this method
US4965441A (en) * 1988-01-27 1990-10-23 Commissariat A L'energie Atomique Method for the scanning confocal light-optical microscopic and indepth examination of an extended field and devices for implementing said method
WO1990005297A1 (en) * 1988-10-31 1990-05-17 Schweizerische Eidgenossenschaft Psi Paul Scherrer Institut A device for the simultaneous contactless testing of a plurality of points on a test sample and its application
US5357283A (en) * 1989-01-19 1994-10-18 Tesler Vladimir E Reflected modulated television system

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Publication number Publication date
CH669663A5 (en) 1989-03-31
AU6726987A (en) 1987-07-15
EP0250490A1 (en) 1988-01-07

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