WO2011039127A1 - Apparatus and method for measuring the form of freeform surfaces - Google Patents

Apparatus and method for measuring the form of freeform surfaces Download PDF

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Publication number
WO2011039127A1
WO2011039127A1 PCT/EP2010/064212 EP2010064212W WO2011039127A1 WO 2011039127 A1 WO2011039127 A1 WO 2011039127A1 EP 2010064212 W EP2010064212 W EP 2010064212W WO 2011039127 A1 WO2011039127 A1 WO 2011039127A1
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Prior art keywords
measuring
axis
free
scanning
scanning arm
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PCT/EP2010/064212
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German (de)
French (fr)
Inventor
Jonathan Becker
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Robert Bosch Gmbh
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Publication of WO2011039127A1 publication Critical patent/WO2011039127A1/en

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    • 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
    • G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
    • 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
    • G01B11/002—Measuring arrangements characterised by the use of optical techniques for measuring two or more coordinates
    • G01B11/005—Measuring arrangements characterised by the use of optical techniques for measuring two or more coordinates coordinate measuring machines
    • G01B11/007—Measuring arrangements characterised by the use of optical techniques for measuring two or more coordinates coordinate measuring machines feeler heads therefor

Definitions

  • the invention relates to a device for measuring the shape of free-flowing surfaces of measuring objects according to the preamble of claim 1 and to a method for measuring the shape of free-form surfaces on measuring objects with such a device.
  • DE 198 08 273 A1 shows an interferometric measuring device for detecting the shape of rough surfaces, wherein a spatially coherent Strahlungser- generating unit is provided which emits a potentially coherent radiation, and a separation in a section with the components of a modulation interferometer and the components a measuring probe is made and the measuring probe is coupled via an optical fiber arrangement with the modulation interferometer and can be used away from the modulation interferometer.
  • Such interferometric measuring devices are used in shape measuring machines.
  • the probe is integrated in an optical probe arm, which is mechanically interchangeable, for example, via a magnetic coupling with a measuring machine.
  • the modulation interferometer as part of the optical measuring device is also connected to the measuring machine.
  • the optical connection between the optical measuring device and the measuring probe takes place via the optical fiber arrangement.
  • Known shape measuring machines with point-measuring optical scanning arms use arrangements for moving the Tatstarm scanning point along a
  • an optical or interferometric probe arm has a limited acceptance angle, which limits the permissible variation of the surface slope of the surface to be measured.
  • an arrangement basically only cylindrical, conical or flat surfaces can be measured.
  • the measurement of, for example, spherical, rotationally symmetric or aspherical surfaces is not possible since the permissible acceptance angle is exceeded from a certain inclination of the surface to the optical axis of the scanning arm.
  • DE 10 2007 024 197 A1 of the applicant proposed an improved device for measuring the shape of free-form surfaces, in which the scanning arm is rotatable in a plane such that the measuring beam is perpendicular or within an acceptance angle of the scanning arm to be measured Free-form surface hits.
  • the optical axis, along which the measuring beam extends coincides with the scanning arm axis defined by the longitudinal extent of the scanning arm.
  • areal measuring optical systems for example in the form of a white light interferometer.
  • Such systems require objectives which generate light wave fronts adapted to the surface to be measured.
  • the lenses for free-form surfaces are very complex and correspondingly expensive.
  • the object of the invention is to provide an improved shape measuring device in which the travel paths of the scanning arm, which are comparatively large in the prior art, are minimized.
  • the proposed Tastarman extract should be robust.
  • the object is to provide a measuring method with a correspondingly optimized device for minimizing the routes.
  • the invention is based on the idea of designing a particularly robust arrangement in that the optical measuring beam extends at right angles to the longitudinal axis defined by the longitudinal extension of the scanning arm, in particular by the optical measuring beam in or on the scanning arm, preferably by 90 ° is deflected and that the pivot axis about which the scanning arm is rotatably arranged, parallel and spaced from the Tastarmachse and thereby the sampling point, ie the spot of the measuring beam on the measuring object, cuts.
  • the optical measuring beam extends at right angles to the longitudinal axis defined by the longitudinal extension of the scanning arm, in particular by the optical measuring beam in or on the scanning arm, preferably by 90 ° is deflected and that the pivot axis about which the scanning arm is rotatably arranged, parallel and spaced from the Tastarmachse and thereby the sampling point, ie the spot of the measuring beam on the measuring object, cuts.
  • Axis along which the measuring beam extends preferably set perpendicular or at an acceptance angle to the free-form surface of the measurement object.
  • Interferometer are used. It is very particularly preferred if the distance between the Tastarmachse and the pivot or rotation axis - taking into account the necessary optics for focusing the measuring beam in the sampling point - is as low as possible.
  • the pivot angle position of the scanning arm about the pivot axis and thus the angle between the measuring beam and the object to be measured can be detected in the scanning point.
  • the pivot axis or a pivot drive is very particularly preferably associated with an angle encoder.
  • control means which are designed in such a way that the scanning arm with measuring beam extending at right angles thereto can be moved along a predefined or predetermined path such that the measuring beam is perpendicular or at an acceptance angle to the free-form measurement to be measured.
  • Surface is oriented in the sampling point. It is particularly expedient if means for rotating the measurement object are provided. Due to the rotatable arrangement of the measurement object, it is possible to record a multi-dimensional shaping surface with a sensing arm which is rotatably mounted only about the pivot axis about its scanning point.
  • the scanning arm is part of an interferometric measuring device, wherein the scanning arm is connected to a modulation interferometer, for example via an optical fiber arrangement.
  • the interferometric measuring device enables the optical measurement of the surface of the test object.
  • the optical fiber arrangement allows the free movement of the scanning arm along the web line and the rotation of the scanning arm about the axis parallel to the Tastarmachse pivot axis.
  • the invention also leads to a method for measuring the shape of free-form surfaces on test objects using a device designed as described above.
  • 1 shows a schematic representation of the basic structure of a device for measuring the shape of free-form surfaces on DUTs and 2 shows the relative positioning of such a device during the measuring operation, in which the scanning arm is moved along a path line relative to the object of measurement driven rotatably.
  • FIG. 1 shows a detail of a device 1 for measuring the shape of free-form surfaces on measurement objects. For better orientation is a Cartesian
  • the scanning arm 2 is connected via an optical fiber arrangement 3 to a white light modulation interferometer (not shown), which is known per se and forms part of the device 1.
  • the probe arm 2 is fixed to a holder 4, which is pivotable about a pivot axis S by means of a stepping motor, not shown, wherein the pivot axis S is arranged parallel to and spaced from the Tastarmachse T.
  • the pivot axis S is perpendicular to the plane defined by the x and the z axis.
  • the double arrow marked with the reference numeral 5 symbolizes the possible pivoting directions (circumferential directions) into which the scanning arm 2 is pivotable about the pivot axis S extending along the y-axis of the coordinate system.
  • the measuring radiation is deflected by 90 °, so that a measuring beam 6 leaves the scanning arm 2 along an optical axis O, which is perpendicular, i. perpendicular to Tastarmachse T, is oriented.
  • the measuring beam 6 is focused in a sampling point A (spot) on the measurement object not shown in detail in FIG.
  • the pivot axis S is arranged such that it passes through the sampling point A, that intersects this.
  • the holder 4 is part of a Winkelencoders 7, with which the pivot angle position of the sensing arm 2 to the
  • Pivot axis S can be measured and evaluated with a control device, not shown, so as to drive the stepper motor, not shown accordingly. in such a way that the optical axis O is always perpendicular to the free-form surface to be measured during the movement of the scanning arm 2 along a path 9, which is oriented along the Z-axis, for example.
  • the scanning arm 2 is preferably moved in such a way that it always maintains a constant distance to the measurement object.
  • FIG. 2 shows the probe arm 2 of the device 1 according to FIG. 1 during a measuring process.
  • a rotationally symmetrical measurement object 8 is rotatably driven about a rotation axis R.
  • the scanning arm 2 is controlled by control means, not shown, such that the scanning arm 2 moves along a path line 9, at right angles to the measuring beam 6 exits along the optical axis O.
  • the optical axis O is perpendicular to the scanning point A on the measuring object 8, regardless of the position of the scanning arm 2 on the web line.
  • the sensing arm T is outside a cylindrical portion of the measuring object 8 and is along the z-axis, which is parallel to the axis of rotation R moves, while the measuring object 8 rotates about the rotation axis R.
  • the scanning arm T is rotated about the pivot axis S by a pivot angle which can be detected with an angle encoder, so that the optical axis O continues to be perpendicular to the measurement object 8, more precisely to the sampling point A on the free-form surface to be measured is oriented that from the position marked with 2, a conically contoured section is measured. Further pivoting then takes place in the position marked with 3, from which the cone angle changes.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Length Measuring Devices By Optical Means (AREA)
  • Length Measuring Devices With Unspecified Measuring Means (AREA)

Abstract

The invention relates to an apparatus (1) for measuring the form of freeform surfaces on measurement objects (8) having a point-measuring optical and/or interferometric scanning arm (2) which defines a scanning arm axis (T) and is pivotable about a pivot axis (S), and having a measurement beam (6) which can be focussed onto the freeform surface in a scanning point (A) and extends along an optical axis (O). Provision is made according to the invention for the optical axis (O) to be orientated at a right angle to the scanning arm axis (T) and for the pivot axis (S) to be orientated parallel to the scanning arm axis (T) and for the pivot axis (S) to intersect with the scanning point (A).

Description

Beschreibung  description
Vorrichtung und Verfahren zur Formmessung von Freiform-Flächen Stand der Technik Device and method for measuring the shape of free-form surfaces Prior art
Die Erfindung betrifft eine Vorrichtung zur Formmessung von Freifrom-Flächen an Messobjekten gemäß dem Oberbegriff des Anspruchs 1 sowie ein Verfahren zur Formmessung von Freiform-Flächen an Messobjekten mit einer derartigen Vorrichtung. The invention relates to a device for measuring the shape of free-flowing surfaces of measuring objects according to the preamble of claim 1 and to a method for measuring the shape of free-form surfaces on measuring objects with such a device.
Die DE 198 08 273 A1 zeigt eine interferometrische Messvorrichtung zum Erfassen der Form rauher Oberflächen, wobei eine räumlich koheränte Strahlungser- zeugungseinheit vorgesehen ist, die eine zeitlich kurzkoheränte und breitbandige Strahlung abgibt, und eine Trennung in einem Abschnitt mit den Komponenten eines Modulationsinterferometers und den Komponenten einer Messsonde vorgenommen und die Messsonde über eine Lichtleitfaseranordnung mit dem Modulationsinterferometer gekoppelt ist und vom Modulationsinterferometer entfernt verwendbar ist. DE 198 08 273 A1 shows an interferometric measuring device for detecting the shape of rough surfaces, wherein a spatially coherent Strahlungser- generating unit is provided which emits a kurzkoheränte and broadband radiation, and a separation in a section with the components of a modulation interferometer and the components a measuring probe is made and the measuring probe is coupled via an optical fiber arrangement with the modulation interferometer and can be used away from the modulation interferometer.
Derartige interferometrische Messeinrichtungen werden in Form-Messmaschinen eingesetzt. Dabei ist die Messsonde in einen optischen Tastarm integriert, der beispielsweise über eine Magnetkupplung auswechselbar mit einer Messmaschine mechanisch verbunden ist. Das Modulationsinterferometer als Bestandteil des optischen Messgerätes ist ebenfalls an die Messmaschine angebunden. Die optische Verbindung zwischen dem optischen Messgerät und der Messsonde erfolgt über die Lichtleitfaseranordnung. Such interferometric measuring devices are used in shape measuring machines. In this case, the probe is integrated in an optical probe arm, which is mechanically interchangeable, for example, via a magnetic coupling with a measuring machine. The modulation interferometer as part of the optical measuring device is also connected to the measuring machine. The optical connection between the optical measuring device and the measuring probe takes place via the optical fiber arrangement.
Bekannte Formmessmaschinen mit punktmessenden optischen Tastarmen ver- wenden Anordnungen zur Bewegung des Tatstarm-Abtastpunktes entlang einerKnown shape measuring machines with point-measuring optical scanning arms use arrangements for moving the Tatstarm scanning point along a
Bahnlinie. Ein optischer oder interferometrischer Tastarm hat jedoch einen be- grenzten Akzeptanzwinkel, was die zulässige Variation der Oberflächenneigung der zu messenden Oberfläche begrenzt. Somit können mit einer solchen Anordnung grundsätzlich nur zylindrische, kegelförmige oder ebene Flächen vermessen werden. Die Vermessung von beispielsweise kugelförmigen, rotationssym- metrischen oder asphärischen Oberflächen ist nicht möglich, da ab einer bestimmten Neigung der Oberfläche zur optischen Achse des Tastarms der zulässige Akzeptanzwinkel überschritten wird. Railway line. However, an optical or interferometric probe arm has a limited acceptance angle, which limits the permissible variation of the surface slope of the surface to be measured. Thus, with such an arrangement basically only cylindrical, conical or flat surfaces can be measured. The measurement of, for example, spherical, rotationally symmetric or aspherical surfaces is not possible since the permissible acceptance angle is exceeded from a certain inclination of the surface to the optical axis of the scanning arm.
Aus diesem Grund wurde in der DE 10 2007 024 197 A1 der Anmelderin eine verbesserte Vorrichtung zur Formmessung von Freiform-Flächen vorgeschlagen, bei der der Tastarm in einer Ebene derart drehbar ist, dass der Messstrahl senkrecht oder innerhalb eines Akzeptanzwinkels des Tastarms auf die zu messende Freiform-Fläche trifft. Bei der bekannten Vorrichtung fällt die optische Achse, entlang derer sich der Messstrahl erstreckt, mit der von der Längserstreckung des Tastarms definierten Tastarmachse zusammen. For this reason, DE 10 2007 024 197 A1 of the applicant proposed an improved device for measuring the shape of free-form surfaces, in which the scanning arm is rotatable in a plane such that the measuring beam is perpendicular or within an acceptance angle of the scanning arm to be measured Free-form surface hits. In the known device, the optical axis, along which the measuring beam extends, coincides with the scanning arm axis defined by the longitudinal extent of the scanning arm.
Weiterhin sind flächenhaft messende optische Systeme, beispielsweise in Form eines Weißlicht-Interferometers bekannt. Solche Systeme benötigen Objektive, welche für die zu messende Oberfläche angepasste Lichtwellen-Fronten erzeu- gen. Die Objektive für Freiform-Flächen sind sehr aufwändig und entsprechend teuer. Furthermore, areal measuring optical systems, for example in the form of a white light interferometer are known. Such systems require objectives which generate light wave fronts adapted to the surface to be measured. The lenses for free-form surfaces are very complex and correspondingly expensive.
Offenbarung der Erfindung Ausgehend von dem vorgenannten Stand der Technik liegt der Erfindung dieDISCLOSURE OF THE INVENTION Based on the aforementioned prior art, the invention is the
Aufgabe zugrunde, eine verbesserte Formmessvorrichtung anzugeben, bei der die im Stand der Technik vergleichsweise großen Fahrwege des Tastarms minimiert sind. Bevorzugt soll die vorzuschlagende Tastarmanordnung robust sein. Darüber hinaus besteht die Aufgabe darin, ein Messverfahren mit einer entspre- chend optimierten Vorrichtung zur Minimierung der Fahrwege anzugeben. The object of the invention is to provide an improved shape measuring device in which the travel paths of the scanning arm, which are comparatively large in the prior art, are minimized. Preferably, the proposed Tastarmanordnung should be robust. In addition, the object is to provide a measuring method with a correspondingly optimized device for minimizing the routes.
Diese Aufgabe wird hinsichtlich der Vorrichtung mit den Merkmalen des Anspruchs 1 und hinsichtlich des Verfahrens mit den Merkmalen des Anspruchs 5 gelöst. Vorteilhafte Weiterbildungen der Erfindung sind in den Unteransprüchen angegeben. In den Rahmen der Erfindung fallen sämtliche Kombinationen aus zumindest zwei von in der Beschreibung, den Ansprüchen und/oder den Figuren offenbarten Merkmalen. Zur Vermeidung von Wiederholungen sollen vorrichtungsgemäß offenbarte Merkmale als verfahrensgemäß offenbart gelten und beanspruchbar sein. Ebenso sollen verfahrensgemäß offenbarte Merkmale als vorrichtungsgemäß offenbart gelten und beanspruchbar sein. This object is achieved with regard to the device having the features of claim 1 and with regard to the method having the features of claim 5. Advantageous developments of the invention are specified in the subclaims. In the context of the invention, all combinations of at least two of the in the description, the claims and / or the figures fall disclosed features. In order to avoid repetition, features disclosed according to the device should be regarded as disclosed according to the method and be able to be claimed. Likewise, according to the method disclosed features should be considered as device disclosed and claimed claimable.
Der Erfindung liegt der Gedanke zugrunde, eine besonders robuste Anordnung dadurch zu konzipieren, dass sich der optische Messstrahl rechtwinklig zu der von der Längserstreckung des Tastarms definierten Längsachse erstreckt, insbesondere dadurch, dass der optische Messstrahl im oder am Tastarm, vor- zugsweise um 90°, abgelenkt wird und dass die Schwenkachse, um die der Tastarm drehbar angeordnet ist, parallel und mit Abstand zur Tastarmachse verläuft und dabei den Abtastpunkt, also den Spot des Messstrahls auf dem Messobjekt, schneidet. Aus einer derartigen Anordnung ergibt sich neben einem robusten Aufbau der Vorteil, dass lediglich kleine, rein rotatorische Bewegungen realisiert werden müssen, um die optische Achse des Abtastpunktes, d.h. die optischeThe invention is based on the idea of designing a particularly robust arrangement in that the optical measuring beam extends at right angles to the longitudinal axis defined by the longitudinal extension of the scanning arm, in particular by the optical measuring beam in or on the scanning arm, preferably by 90 ° is deflected and that the pivot axis about which the scanning arm is rotatably arranged, parallel and spaced from the Tastarmachse and thereby the sampling point, ie the spot of the measuring beam on the measuring object, cuts. From such an arrangement, in addition to a robust construction, there is the advantage that only small, purely rotational movements must be realized in order to control the optical axis of the sampling point, i. the optical
Achse, entlang derer sich der Messstrahl erstreckt, bevorzugt senkrecht oder unter einem Akzeptanzwinkel zur Freiformfläche des Messobjektes einzustellen. Insgesamt können hierdurch große Fahrwege einer Führungsmaschine für den Tastarm minimiert werden, was insgesamt in einem schnelleren und präziseren Messvorgang resultiert. Als Messeinrichtung kann beispielsweise ein WhitePoint-Axis along which the measuring beam extends, preferably set perpendicular or at an acceptance angle to the free-form surface of the measurement object. Overall, as a result, large travel distances of a guide machine for the probe can be minimized, resulting in a total of a faster and more accurate measurement. As a measuring device, for example, a WhitePoint
Interferometer zum Einsatz kommen. Ganz besonders bevorzugt ist es, wenn der Abstand zwischen der Tastarmachse und der Schwenk- bzw. Drehachse - unter Berücksichtigung der notwendigen Optik zur Fokussierung des Messstrahls im Abtastpunkt - möglichst gering ist. Interferometer are used. It is very particularly preferred if the distance between the Tastarmachse and the pivot or rotation axis - taking into account the necessary optics for focusing the measuring beam in the sampling point - is as low as possible.
In Weiterbildung der Erfindung ist mit Vorteil vorgesehen, dass die Schwenkwinkelposition des Tastarms um die Schwenkachse und damit der Winkel zwischen Messstrahl und Messobjekt im Abtastpunkt erfassbar ist. Ganz besonders bevorzugt ist hierfür der Schwenkachse bzw. einem Schwenkantrieb ein Winkelenco- der zugeordnet. In a development of the invention, it is advantageously provided that the pivot angle position of the scanning arm about the pivot axis and thus the angle between the measuring beam and the object to be measured can be detected in the scanning point. For this purpose, the pivot axis or a pivot drive is very particularly preferably associated with an angle encoder.
Besonders zweckmäßig ist es, Steuermittel vorzusehen, die derart ausgebildet sind, dass mit diesen der Tastarm mit sich rechtwinklig dazu erstreckendem Messstrahl derart entlang einer vorgegebenen bzw. vorgebbaren Bahnlinie be- wegbar ist, dass der Messstrahl senkrecht oder unter einem Akzeptanzwinkel zur zu messenden Freiform-Fläche im Abtastpunkt orientiert ist. Besonders zweckmäßig ist es, wenn Mittel zum Rotieren des Messobjektes vorgesehen sind. Durch die drehbare Anordnung des Messobjektes ist es möglich, mit einem Tastarm, der nur um die Schwenkachse um seinen Abtastpunkt drehbar gelagert ist, eine mehrdimensionale Formfläche aufzunehmen. Dies ermöglicht beispielsweise die Messung der Oberfläche einer Kugel, indem der Tastarm auf einen Punkt der Kugeloberfläche ausgerichtet wird, die Kugeloberfläche durch die Rotationsbewegung der Kugel durch den Abtastpunkt bewegt und so die Kugel oberflächenlinienförmig abgetastet wird. It is particularly expedient to provide control means which are designed in such a way that the scanning arm with measuring beam extending at right angles thereto can be moved along a predefined or predetermined path such that the measuring beam is perpendicular or at an acceptance angle to the free-form measurement to be measured. Surface is oriented in the sampling point. It is particularly expedient if means for rotating the measurement object are provided. Due to the rotatable arrangement of the measurement object, it is possible to record a multi-dimensional shaping surface with a sensing arm which is rotatably mounted only about the pivot axis about its scanning point. This makes it possible, for example, to measure the surface of a sphere by aligning the scanning arm with a point on the surface of the sphere, moving the surface of the sphere by the rotation of the sphere through the scanning point and thus scanning the sphere in a surface-line pattern.
Ganz besonders zweckmäßig ist es, wenn der Tastarm Teil einer interferometri- schen Messeinrichtung ist, wobei der Tastarm beispielsweise über eine Lichtleitfaseranordnung mit einem Modulationsinterferometer verbunden ist. Die interfe- rometrische Messeinrichtung ermöglicht die optische Vermessung der Oberfläche des Prüfobjektes. Dabei erlaubt die Lichtleitfaseranordnung die freie Bewegung des Tastarms entlang der Bahnlinie sowie die Drehung des Tastarms um die parallel zur Tastarmachse verlaufende Schwenkachse. It is particularly expedient if the scanning arm is part of an interferometric measuring device, wherein the scanning arm is connected to a modulation interferometer, for example via an optical fiber arrangement. The interferometric measuring device enables the optical measurement of the surface of the test object. In this case, the optical fiber arrangement allows the free movement of the scanning arm along the web line and the rotation of the scanning arm about the axis parallel to the Tastarmachse pivot axis.
Die Erfindung führt auch auf ein Verfahren zur Formmessung von Freiform- Flächen an Messobjekten unter Verwendung einer wie zuvor beschrieben ausgebildeten Vorrichtung. Dabei ist es Kern des Verfahrens, die erfindungsgemäße Vorrichtung derart anzusteuern, dass der Tastarm mit dem sich senkrecht dazu erstreckenden Messstrahl derart entlang einer Bahnlinie bewegt wird, dass der Messstrahl während der Messung senkrecht oder unter einem Akzeptanzwinkel zur Freiform-Fläche orientiert ist. The invention also leads to a method for measuring the shape of free-form surfaces on test objects using a device designed as described above. In this case, it is the core of the method to control the device according to the invention in such a way that the scanning arm with the measurement beam extending perpendicularly thereto is moved along a line such that the measurement beam is oriented perpendicular or at an acceptance angle to the free-form surface during the measurement.
Weitere Vorteile, Merkmale und Einzelheiten der Erfindung ergeben sich aus der nachfolgenden Beschreibung eines bevorzugten Ausführungsbeispiels sowie anhand der Zeichnungen. Further advantages, features and details of the invention will become apparent from the following description of a preferred embodiment and from the drawings.
Diese zeigen in: These show in:
Fig. 1 : in einer schematischen Darstellung den prinzipiellen Aufbau einer Vorrichtung zur Formmessung von Freiform-Flächen an Messobjekten und Fig. 2: die Relativpositionierung einer derartigen Vorrichtung während des Messbetriebs, bei welchem der Tastarm entlang einer Bahnlinie relativ zu dem rotierbar angetriebenen Messobjekt bewegt wird. 1 shows a schematic representation of the basic structure of a device for measuring the shape of free-form surfaces on DUTs and 2 shows the relative positioning of such a device during the measuring operation, in which the scanning arm is moved along a path line relative to the object of measurement driven rotatably.
In den Figuren sind gleiche Elemente und Elemente mit der gleichen Funktion mit den gleichen Bezugszeichen gekennzeichnet. In the figures, like elements and elements having the same function are denoted by the same reference numerals.
In Fig. 1 ist ausschnittsweise eine Vorrichtung 1 zur Formmessung von Freiform- Flächen an Messobjekten gezeigt. Zur besseren Orientierung ist ein kartesischesFIG. 1 shows a detail of a device 1 for measuring the shape of free-form surfaces on measurement objects. For better orientation is a Cartesian
Koordinatensystem mit den Achsen x, y und z vorgegeben. Coordinate system with the axes x, y and z specified.
Zu erkennen ist ein langgestreckter, stabförmiger Tastarm 2, der sich sich entlang der y-Achse des Koordinatensystems erstreckt und dessen Längserstreckung bzw. Längsachse eine Tastarmachse T definiert. Der Tastarm 2 ist über eine Lichtleitfaseranordnung 3 mit einem nicht dargestellten, an sich bekannten, einen Bestandteil der Vorrichtung 1 bildenden Weißlicht-Modulationsinterfero- meter verbunden. Der Tastarm 2 ist an einem Halter 4 festgelegt, der mittels eines nicht dargestellten Schrittmotors um eine Schwenkachse S verschwenkbar ist, wobei die Schwenkachse S parallel und mit Abstand zur Tastarmachse T angeordnet ist. Die Schwenkachse S steht senkrecht auf der von der x- und der z- Achse definierten Ebene. Der mit dem Bezugszeichen 5 gekennzeichnete Doppelpfeil symbolisiert die möglichen Schwenkrichtungen (Umfangrichtungen), in die der Tastarm 2 um die sich entlang der y-Achse des Koordinatensystems erstreckende Schwenkachse S verschwenkbar ist. Innerhalb des Tastarms 2 wird die Messstrahlung um 90° umgelenkt, so dass ein Messstrahl 6 den Tastarm 2 entlang einer optischen Achse O verlässt, die rechtwinklig, d.h. senkrecht zur Tastarmachse T, orientiert ist. Der Messstrahl 6 ist in einem Abtastpunkt A (Spot) auf dem in Fig. 1 nicht näher dargestellten Messobjekt fokussiert. Die Schwenkachse S ist derart angeordnet, dass diese durch den Abtastpunkt A verläuft, diesen also schneidet. Evident is an elongate, rod-shaped probe arm 2, which extends along the y-axis of the coordinate system and whose longitudinal extent or longitudinal axis defines a Tastarmachse T. The scanning arm 2 is connected via an optical fiber arrangement 3 to a white light modulation interferometer (not shown), which is known per se and forms part of the device 1. The probe arm 2 is fixed to a holder 4, which is pivotable about a pivot axis S by means of a stepping motor, not shown, wherein the pivot axis S is arranged parallel to and spaced from the Tastarmachse T. The pivot axis S is perpendicular to the plane defined by the x and the z axis. The double arrow marked with the reference numeral 5 symbolizes the possible pivoting directions (circumferential directions) into which the scanning arm 2 is pivotable about the pivot axis S extending along the y-axis of the coordinate system. Within the scanning arm 2, the measuring radiation is deflected by 90 °, so that a measuring beam 6 leaves the scanning arm 2 along an optical axis O, which is perpendicular, i. perpendicular to Tastarmachse T, is oriented. The measuring beam 6 is focused in a sampling point A (spot) on the measurement object not shown in detail in FIG. The pivot axis S is arranged such that it passes through the sampling point A, that intersects this.
In dem gezeigten Ausführungsbeispiel ist der Halter 4 Bestandteil eines Winkelencoders 7, mit dem die Schwenkwinkelposition des Tastarms 2 um die In the embodiment shown, the holder 4 is part of a Winkelencoders 7, with which the pivot angle position of the sensing arm 2 to the
Schwenkachse S messbar und mit einer nicht dargestellten Steuereinrichtung auswertbar ist, um so den nicht dargestellten Schrittmotor entsprechend ansteu- ern zu können, vorzugsweise derart, dass die optische Achse O beim Verfahren des Tastarms 2 entlang einer Bahnlinie 9, die beispielsweise entlang der Z- Achse orientiert ist, immer senkrecht auf der zu vermessenden Freiform-Fläche steht. Bevorzugt wird der Tastarm 2 dabei derart bewegt, dass dieser immer ei- nen konstanten Abstand zum Messobjekt einhält. Pivot axis S can be measured and evaluated with a control device, not shown, so as to drive the stepper motor, not shown accordingly. in such a way that the optical axis O is always perpendicular to the free-form surface to be measured during the movement of the scanning arm 2 along a path 9, which is oriented along the Z-axis, for example. The scanning arm 2 is preferably moved in such a way that it always maintains a constant distance to the measurement object.
Bevorzugt ist ein Abstand a von typischerweise weniger als 10 mm zwischen der Tastarmachse T und der Schwenkachse S einstellbar. In Fig. 2 ist der Tastarm 2 der Vorrichtung 1 gemäß Fig. 1 während eines Messvorgangs gezeigt. Preferably, a distance a of typically less than 10 mm between the Tastarmachse T and the pivot axis S is adjustable. FIG. 2 shows the probe arm 2 of the device 1 according to FIG. 1 during a measuring process.
Ein rotationssymmetrisches Messobjekt 8 ist rotierbar um eine Rotationsachse R angetrieben. Der Tastarm 2 wird von nicht dargestellten Steuermitteln derart an- gesteuert, dass sich der Tastarm 2 entlang einer Bahnlinie 9 bewegt, rechtwinklig zu der der Messstrahl 6 entlang der optischen Achse O austritt. Zu erkennen ist, dass die optische Achse O senkrecht im Abtastpunkt A auf dem Messobjekt 8 steht und zwar unabhängig von der Position des Tastarms 2 auf der Bahnlinie. In einer mit 1. gekennzeichneten Position befindet sich der Tastarm T außerhalb eines zylindrischen Abschnittes des Messobjektes 8 und wird entlang der z-Achse, die parallel zur Rotationsachse R verläuft, bewegt, während das Messobjekt 8 um die Rotationsachse R rotiert. In der mit 2. gekennzeichneten Position wird der Tastarm T um die Schwenkachse S um einen Schwenkwinkel, der mit einem Winkelencoder erfassbar ist, rotiert, damit die optische Achse O weiterhin senkrecht zum Messobjekt 8, genauer zum Abtastpunkt A auf der zu vermessenden Freiform-Fläche orientiert ist, dass ab der mit 2. gekennzeichneten Position ein konisch konturierter Abschnitt vermessen wird. Ein weiteres Verschwenken erfolgt dann in der mit 3. gekennzeichneten Position, ab welcher sich der Konus- winkel ändert. A rotationally symmetrical measurement object 8 is rotatably driven about a rotation axis R. The scanning arm 2 is controlled by control means, not shown, such that the scanning arm 2 moves along a path line 9, at right angles to the measuring beam 6 exits along the optical axis O. It can be seen that the optical axis O is perpendicular to the scanning point A on the measuring object 8, regardless of the position of the scanning arm 2 on the web line. In a position marked with 1, the sensing arm T is outside a cylindrical portion of the measuring object 8 and is along the z-axis, which is parallel to the axis of rotation R moves, while the measuring object 8 rotates about the rotation axis R. In the position indicated by 2, the scanning arm T is rotated about the pivot axis S by a pivot angle which can be detected with an angle encoder, so that the optical axis O continues to be perpendicular to the measurement object 8, more precisely to the sampling point A on the free-form surface to be measured is oriented that from the position marked with 2, a conically contoured section is measured. Further pivoting then takes place in the position marked with 3, from which the cone angle changes.

Claims

Ansprüche claims
1. Vorrichtung zur Formmessung von Freiform-Flächen an Messobjekten (8) mit einem eine Tastarmachse (T) definierenden und um eine Schwenkachse (S) verschwenkbaren punktmessenden optischen und/oder interferrometrischen- der Tastarm (2), und mit einem auf die Freiform-Fläche in einem Abtastpunkt (A) fokussierbaren, sich entlang einer optischen Achse (O) erstreckenden Messtrahl (6), dadurch gekennzeichnet, dass die optische Achse (O) rechtwinklig zur Tastarmachse (T) und die Schwenkachse (S) parallel zur Tastarmachse (T) orientiert sind und dass die Schwenkachse (S) den Abtastpunkt (A) schneidet. 1. A device for measuring the shape of free-form surfaces on DUTs (8) with a Tastarmachse (T) defining and pivotable about a pivot axis (S) point-measuring optical and / or interferrometric- the sensing arm (2), and with a free-form on the Surface in a sampling point (A) focusable, along an optical axis (O) extending measuring beam (6), characterized in that the optical axis (O) at right angles to Tastarmachse (T) and the pivot axis (S) parallel to Tastarmachse (T ) and that the pivot axis (S) intersects the sampling point (A).
2. Vorrichtung nach Anspruch 1 , 2. Apparatus according to claim 1,
dadurch gekennzeichnet,  characterized,
dass der Schwenkachse (S) ein Winkelencoder (7) zum Erfassen einer absoluten oder relativen Schwenkwinkelposition des Tastarms (2) vorgesehen sind.  in that an angle encoder (7) for detecting an absolute or relative pivot angle position of the sensing arm (2) is provided on the pivot axis (S).
3. Vorrichtung nach einem der Ansprüche 1 oder 2, 3. Device according to one of claims 1 or 2,
dadurch gekennzeichnet,  characterized,
dass Steuermittel vorgesehen sind, mit denen der Tastarm (2) mit senkrecht oder unter einem Akzeptanzwinkel zur Freiform-Fläche stehenden optischen Achse (O) entlang einer Bahnlinie (9) bewegbar ist.  in that control means are provided with which the scanning arm (2) can be moved along a line (9) with an optical axis (O) which is perpendicular or at an acceptance angle to the free-form surface.
4. Vorrichtung nach einem der vorhergehenden Ansprüche, 4. Device according to one of the preceding claims,
dadurch gekennzeichnet,  characterized,
dass Mittel zum Rotieren des Messobjektes (8) vorgesehen sind.  in that means for rotating the measurement object (8) are provided.
5. Verfahren zur Formmessung von Freiform-Flächen an Messobjekten (8) mit einer Vorrichtung (1) nach einem der vorhergehenden Ansprüche, 5. A method for measuring the shape of free-form surfaces on measuring objects (8) with a device (1) according to one of the preceding claims,
dadurch gekennzeichnet, dass der Tastarm (2) mit senkrecht oder unter einem Akzeptanzwinkel zur Freiform-Fläche stehenden optischen Achse (O) entlang einer Bahnlinie (9) bewegt wird. characterized, the scanning arm (2) is moved along a path (9) with an optical axis (O) perpendicular or at an acceptance angle to the free-form surface.
PCT/EP2010/064212 2009-10-01 2010-09-27 Apparatus and method for measuring the form of freeform surfaces WO2011039127A1 (en)

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EP0600800A1 (en) * 1992-12-04 1994-06-08 Commissariat A L'energie Atomique Procedure and device to acquire an image, in three dimensions, of a small object with a light pencil and a calibration method for such an acquirement
DE19808273A1 (en) 1998-02-27 1999-09-09 Bosch Gmbh Robert Interferometric measuring device for detecting the shape or the distance, especially of rough surfaces
US20060101660A1 (en) * 2004-11-18 2006-05-18 Tokyo Seimitsu Co., Ltd. Detector supporting mechanism
US20080131838A1 (en) * 2004-10-28 2008-06-05 Gc Corporation Measured object mounting tool and production method of three-dimensional shape data of dental prosthesis using that tool
DE102007024197A1 (en) 2007-05-24 2008-11-27 Robert Bosch Gmbh Device and method for measuring the shape of free-form surfaces

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Publication number Priority date Publication date Assignee Title
EP0600800A1 (en) * 1992-12-04 1994-06-08 Commissariat A L'energie Atomique Procedure and device to acquire an image, in three dimensions, of a small object with a light pencil and a calibration method for such an acquirement
DE19808273A1 (en) 1998-02-27 1999-09-09 Bosch Gmbh Robert Interferometric measuring device for detecting the shape or the distance, especially of rough surfaces
US20080131838A1 (en) * 2004-10-28 2008-06-05 Gc Corporation Measured object mounting tool and production method of three-dimensional shape data of dental prosthesis using that tool
US20060101660A1 (en) * 2004-11-18 2006-05-18 Tokyo Seimitsu Co., Ltd. Detector supporting mechanism
DE102007024197A1 (en) 2007-05-24 2008-11-27 Robert Bosch Gmbh Device and method for measuring the shape of free-form surfaces

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