EP2847579A1 - Method for determining features of a measurement object - Google Patents
Method for determining features of a measurement objectInfo
- Publication number
- EP2847579A1 EP2847579A1 EP13724746.6A EP13724746A EP2847579A1 EP 2847579 A1 EP2847579 A1 EP 2847579A1 EP 13724746 A EP13724746 A EP 13724746A EP 2847579 A1 EP2847579 A1 EP 2847579A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- measurement object
- rotation
- angle
- relative positions
- axis
- 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.)
- Withdrawn
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
- G01N23/02—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material
- G01N23/04—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material
- G01N23/046—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material using tomography, e.g. computed tomography [CT]
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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
- G01B15/00—Measuring arrangements characterised by the use of electromagnetic waves or particle radiation, e.g. by the use of microwaves, X-rays, gamma rays or electrons
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2223/00—Investigating materials by wave or particle radiation
- G01N2223/40—Imaging
- G01N2223/419—Imaging computed tomograph
Definitions
- the present invention describes a method for the dimensional determination of features on measurement objects with computed tomography methods, in which the measurement object is measured in a plurality of relative positions.
- the invention relates to a computed tomography method for the dimensional determination of features on a measurement object, in which the measurement object attached to a mechanical axis of rotation in several relative positions with respect to the sensor system, at least consisting of radiation source and 2-dimensional detector, in each case in several rotational positions an axis of rotation is irradiated by the radiation of the radiation source and respectively associated 2D transmission images are recorded, wherein the transmission images from the various relative positions are each assembled into a resulting radiographic image, which was taken with respect to the respective starting rotational angle of the various relative positions at the same rotational position, and off
- the resulting radiographic images are reconstructed by 3-dimensional volume information in voxel format (so-called voxel volume), in which voxel volume Date n are included for local beam absorption, wherein surface points are preferably generated from the voxel data, in the region of the material transitions.
- the measurement object only extends beyond the measuring range of the computer tomograph in the direction of the axis of rotation of the computer tomograph, several partial measurements are carried out, between which the measurement object runs along the axis of rotation is moved. In this case, the measuring object leaves the measuring range perpendicular to the axis of rotation in any of the rotational positions.
- the voxel volumes can then be assembled together and it can be a common determination of surface points based on z.
- Threshold method can be performed. Alternatively, surface points on the sub-volume can also be determined. The method is also known by moving the detector along a parallel to the axis of rotation axis.
- the radiographic images determined in the partial measurements can alternatively also be combined to resulting radiographic images per rotary position.
- the reconstruction then takes place on the composite set of transmission images.
- magnification of the image changes.
- a necessary correction of the radiographic images before combining was not yet known, which results in measurement deviations.
- the measurement object leaves the measuring area of the computer tomograph at right angles to the rotation axis in at least one rotational position, the measurement object is wider than the measurement area of the computer tomograph transversely to the rotation axis, then several partial measurements are carried out in which the measurement object is perpendicular to the rotation axis and simultaneously in a plane parallel to the detector plane is moved. In this procedure, only the combined or composite radiographic images corresponding to the respective rotational positions can be reconstructed. Again, magnification changes and perspective distortions occur. The method is also known by moving the detector perpendicular to the rotational axis direction in the detector plane.
- the measurement object is therefore scanned in its height and / or its width.
- a displacement of the measurement object with respect to the sensor always takes place in a plane parallel to the detector plane.
- the ratio describing the imaging scale changes from the distance detector - Focus point of the X-ray source to DUT - Focus point of the X-ray source.
- the measurement errors that occur as a result are not yet corrected and thus lead to the determination of incorrect dimensions on the measurement object.
- perspective distortions result in the different relative positions.
- the transmission images corresponding to the same angle from the different relative positions are not correctly combined by the two effects.
- the object of the present invention is the avoidance of measurement errors in the computed tomographic measurements of measurement objects in a plurality of relative positions between the measurement object and the x-ray sensor system.
- the invention provides in particular that the different relative positions are chosen so that the distance between the focal point of the radiation source (focal spot) and the axis of rotation remains the same.
- the invention provides that the different relative positions are on a circular path around the focal point of the radiation source and in a plane whose normal vector is parallel to the direction of the axis of rotation.
- Another proposal of the invention is characterized in that each adjacent relative positions are selected so that a part of the measurement object is detected in some of the rotational positions in each case two relative positions, so an overlap area exists.
- the entire mechanical axis of rotation During the movement of the entire mechanical axis of rotation to the new position, first the entire axis (lower part, fixed with the CMM or the translatory axes of the CMM is attached, and upper part, ie rotatable turntable with measuring object) including measuring object ONLY translationally shifted. Subsequently, the rotatable part of the rotation axis (ie the turntable) performs a rotational movement to rotate the measurement object in the starting angle position. Equally effective, the entire mechanical axis of rotation could be rotated around the focal spot.
- the invention is further characterized in that the respective rotational positions in the different relative positions are set in their starting angle so that the angle of incidence of the measuring object detecting area of the measuring radiation remains the same in relation to the Meß Congresskoordinatensystem, the measurement object in the overlapping area in the same Direction is irradiated, in particular the start rotation angle is thus changed by the angle by which the entire mechanical axis of rotation was moved around the focal spot.
- the aim is that the measurement object is arranged in the new position in the transition region in the starting rotational position so that it is irradiated in the same direction, as in the measurement in the first position. Otherwise the radiographic images could not be put together.
- the transition region thus ideally produces the same radiographic image (or part of the radiographic image) in both relative positions.
- the combining of the radiographs could then also be done by stitching. But this is not necessary if the positions and rotational positions are known.
- An inventive concept further provides that in each relative position, the respective further rotational positions are set equal with respect to the respective starting angle, preferably the rotational angle increment is constant.
- the invention also provides that the perspective distortions of the image on the radiation detector corrected by changing the starting angle and / or by the relative movement of the measurement object on a circular path are corrected be, preferably by resampling the respective radiographic image and / or by consideration in the reconstruction.
- the various relative positions are arranged on a circular path around the focal point of the radiation source, which is located in a plane which is spanned by the axis of rotation and the direct connection between detector center and radiation source.
- Another idea to be emphasized of the invention provides that when changing the relative position on a circular path, the entire mechanical axis of rotation is tilted according to the orbit position and the rotatable part of the axis of rotation remains together with the measurement object for determining the starting rotational angle in the rotational position.
- the invention is characterized in that the entire mechanical axis of rotation is tilted in the different relative positions in the plane of rotation axis and connection between the detector center and radiation source, that the angle of incidence of the measuring object detecting area of the measuring radiation remains the same in relation to the measuring object coordinate system, the Measuring object in the overlapping area is thus irradiated in the same direction.
- the perspective distortions of the image on the radiation detector resulting from a change in the starting angle and / or by the relative movement of the measurement object on a circular path are corrected, preferably by the inclination of the entire mechanical axis of rotation and / or by resampling at the respective one Radiation image and / or by consideration during reconstruction.
- the measured object assumes a changed angle of rotation after the relative displacement in front of the radiation source. This must be corrected by rotating the measurement object with the rotatable part of the mechanical axis of rotation so that the starting angle of rotation is adapted for the plurality of rotational positions in the form that the radiation direction remains the same with respect to the measuring object coordinate system.
- perspective distortions arise on the radiation detector, because at least parts of the measurement object are located after the relative displacement in an altered relative position to the detector and thus impinge the then passing through the measurement object partial beams at a different angle to the detector.
- These distortions are corrected in accordance with the invention by re-sampling the transmission images, since the size of the distortions is known on the basis of the known start angle, and / or by taking account of the distortion during the reconstruction algorithm.
- the various relative positions are assumed to be almost along a line parallel to the axis of rotation, the entire mechanical axis of rotation is tilted with the measurement object itself such that the angle of incidence of the measurement radiation which detects the measurement object remains the same with respect to the measurement object coordinate system.
- the perspective distortions are corrected by re-sampling on the radiographic image or by taking account of the reconstruction.
- FIG. 1 shows an arrangement of a measurement object in a first relative position in FIG
- FIG. 2 shows an arrangement of a measurement object in a second relative position in FIG
- the measurement object 1 shows an arrangement of a measurement object 1 in a first relative position with respect to an X-ray sensor system 2, comprising a radiation source, such as X-ray source with focal point or focal spot 3, and a detector 4.
- the measurement object 1 also called component-is rotatable about a rotation axis 5 , which is shown in plan view.
- the component 1 is fixedly mounted on the rotatable part of the rotation axis 5. In the illustrated first relative position, the angle 6 between the connection between the center 7 of the detector 4 and the focal spot 3 and the connection between the center of rotation axis 5 and the focal spot 3 is zero degrees.
- Parts of the measurement object 1 project in at least some of the rotational positions about the rotation axis 5 out of the area detectable by the detector 4, limited by the edges 8 and 9 of the radiation area projected into the plane of projection. Therefore, only the single hatched area 10 of the measurement object 1 can be detected and measured. The non-hatched area can not be measured. Duplicated hatched, the transitional or overlapping regions 11 and 12 of the measuring object 1 are shown, which are measured in further relative positions together with the areas not hatched in FIG. The transition region 11 is again detected and measured in the second relative position shown in FIG.
- the transition region 11 is exemplified in this first rotational position about the axis of rotation 5, so the rotational position of the starting angle, for example from the Beam 13 passes through the angle 14.
- the beam 13 strikes the detector 4 at an angle 15.
- further measurements are carried out to determine further regions of the measurement object 1 in at least one further relative position of the mechanical rotation axis 5 and the measurement object 1.
- the entire mechanical rotation axis 5 and the measurement object 1 are displaced on a circular path 16 around the focal spot 3.
- this circular path is located in the plane of the drawing, ie in a plane whose normal vector is parallel to the direction of the axis of rotation 5. This is a special case of the requirement of the constant distance between the focal point of the radiation source (focal spot 3) and the axis of rotation 5.
- FIG. 2 shows an arrangement for a second measurement, in which the measurement object 1 and the entire mechanical rotation axis 5 are displaced in a second relative position relative to the X-ray sensor system 2 on the circular path 16.
- the angle 6 ' shows the changed angle between the connection between the center of the detector 7 and focal point 3 and the connection between the axis of rotation 5 and the focal spot 3.
- FIG. 2 shows the measuring object 1 in the now changed starting angle for the various rotational positions about the axis of rotation. 5 for computer tomographic measurement, wherein the starting angle was changed exactly by the angle 6 '.
- the overlapping region 11 is detected by the measuring radiation, for example by the radiation beam 13 ', again at the same angle 14 as in the first relative position between the measurement object and the X-ray sensor system.
- FIGS. 1 and 2 An analogous procedure takes place in the displacement of the entire mechanical axis of rotation with the measurement object along a circular path, which is located in a plane which is formed from the axis of rotation and the direct connection between the detector center and radiation source (focal spot).
- the axis of rotation runs parallel to the longer, illustrated body edge of the measurement object 1 and in the plane of the drawing, and the measurement object is arranged centrally above the mechanical axis of rotation, ie in the direction of the axis of rotation.
- FIGS. 1 and 2 can be used for clarification. In the second relative position corresponding to Fig. 2 but then no adjustment of the starting rotation angle takes place, but the entire mechanical axis of rotation is tilted together with the measurement object in the drawing plane.
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Abstract
Method for determining features of a measurement object. The invention relates to a computer tomography method for dimensionally determining features on a measurement object, in which the measurement object fastened to a mechanical rotary shaft is x-rayed by the radiation from a radiation source in a plurality of positions relative to the sensor system, at least consisting of the radiation source and a two-dimensional detector, in each case in a plurality of rotational positions around a rotary shaft, and associated 2D x-ray images are recorded in each case, wherein those x-ray images from the different relative positions which are recorded in the same rotational position with respect to the particular starting angle of rotation of the different relative positions are each combined to form a resulting x-ray image, and three-dimensional volume information in the voxel format (so-called voxel volume) is calculated from the resultant x-ray images by means of reconstruction, wherein this voxel volume contains data relating to the local beam absorption, wherein surface points are preferably generated from the voxel data in the region of the material transitions. In order to avoid measurement errors during the computer tomographic measurements of measurement objects in a plurality of relative positions between the measurement object and the x-ray sensor system, it is proposed that the different relative positions are selected in such a manner that the distance between the focal point of the radiation source (focal spot) and the rotary shaft remains the same.
Description
Verfahren zum Bestimmen von Merkmalen eines Messobjekts Method for determining features of a measurement object
Die vorliegende Erfindung beschreibt ein Verfahren zur dimensionellen Bestimmung von Merkmalen an Messobjekten mit Computertomografieverfahren, bei denen das Messobjekt in mehreren Relativpositionen gemessen wird. The present invention describes a method for the dimensional determination of features on measurement objects with computed tomography methods, in which the measurement object is measured in a plurality of relative positions.
Insbesondere bezieht sich die Erfindung auf ein Computertomografie- Verfahren zur dimensioneilen Bestimmung von Merkmalen an einem Messobjekt, bei dem das auf einer mechanischen Drehachse befestigte Messobjekt in mehreren Relativpositionen bezüglich der Sensorik, zumindest bestehend aus Strahlungsquelle und 2-dimensionalen Detektor, jeweils in mehreren Drehstellungen um eine Drehachse von der Strahlung der Strahlungsquelle durchstrahlt wird und jeweils zugehörige 2D-Durchstrahlungsbilder aufgenommen werden, wobei die Durchstrahlungsbilder aus den verschiedenen Relativpositionen jeweils zu einem resultierenden Durchstrahlungsbild zusammengesetzt werden, die bezüglich des jeweiligen Startdrehwinkels der verschiedenen Relativpositionen bei der gleichen Drehstellung aufgenommen worden, und aus den resultierenden Durchstrahlungsbildern mittels Rekonstruktion 3- dimensionale Volumeninformationen im Voxelformat (so genanntes Voxelvolumen) berechnet werden, wobei in diesem Voxelvolumen Daten zur lokalen Strahlabsorption enthalten sind, wobei vorzugsweise aus den Voxeldaten, im Bereich der Materialübergänge, Oberflächenpunkte generiert werden.
Zur Einstellung der Drehstellungen des Drehtisches, der auch als mechanische Drehachse bezeichnet wird, besteht dieser aus einem feststehenden und einem drehbaren Teil. Insofern auf die Drehung oder Drehstellung der mechanischen Drehachse Bezug genommen wird, ist folgend immer der drehbare Teil gemeint. Der drehbare Teil wird dabei um eine mathematische Achse, die folgend vereinfacht „Drehachse" genannt wird, gedreht. Die Orientierung, also Richtung, und Lage, also beispielsweise eines Punktes, dieser Drehachse im Raum, wird auch als Lage der Drehachse bezeichnet. Insofern von der Richtung der mechanischen Drehachse gesprochen wird, ist also auch damit die Richtung der (mathematischen) Drehachse gemeint. Als Position der mechanischen Drehachse wird dagegen die Position im Raum bezeichnet, an der die gesamte mechanische Drehachse, also feststehender und drehbarer Teil, angeordnet ist. Wird die Position der mechanischen Drehachse verändert, beispielsweise in einer der drei lateralen, beispielsweise rechtwinklig zueinander stehenden Richtungen x, y und z, so ändert sich zwangsläufig auch die Lage der (mathematischen) Drehachse, allerdings nur derart, dass sie parallel verschoben wird, sich also ihre Orientierung nicht ändert. In particular, the invention relates to a computed tomography method for the dimensional determination of features on a measurement object, in which the measurement object attached to a mechanical axis of rotation in several relative positions with respect to the sensor system, at least consisting of radiation source and 2-dimensional detector, in each case in several rotational positions an axis of rotation is irradiated by the radiation of the radiation source and respectively associated 2D transmission images are recorded, wherein the transmission images from the various relative positions are each assembled into a resulting radiographic image, which was taken with respect to the respective starting rotational angle of the various relative positions at the same rotational position, and off The resulting radiographic images are reconstructed by 3-dimensional volume information in voxel format (so-called voxel volume), in which voxel volume Date n are included for local beam absorption, wherein surface points are preferably generated from the voxel data, in the region of the material transitions. To set the rotational positions of the turntable, which is also referred to as a mechanical axis of rotation, this consists of a fixed and a rotatable part. Insofar as reference is made to the rotation or rotational position of the mechanical axis of rotation, the following always means the rotatable part. The rotatable part is rotated about a mathematical axis, which is called "rotation axis" in the following: The orientation, ie direction, and position, for example of a point, of this axis of rotation in space is also referred to as position of the axis of rotation The direction of the mechanical axis of rotation is thus also referred to as the direction of the (mathematical) axis of rotation, whereas the position of the mechanical axis of rotation is referred to as the position in space at which the entire mechanical axis of rotation, ie fixed and rotatable part, is arranged. If the position of the mechanical axis of rotation is changed, for example in one of the three lateral directions x, y and z that are at right angles to each other, the position of the (mathematical) axis of rotation inevitably changes, but only in such a way that it is displaced in parallel So their orientation does not change.
Um Messobjekte komplett mit Computertomografie zu messen, die größer als der Messbereich des Computertomografen in der jeweils gewählten Vergrößerungseinstellung sind, existieren Verfahren, bei denen das Messobjekt in mehreren Teilmessungen jeweils nur teilweise erfasst wird. Es wird dabei unterschieden zwischen Verfahren, bei denen das Messobjekt in Richtung der Drehachse oder rechtwinkelig zur Drehachse größere Abmessungen als der Messbereich des Computertomografen aufweist. Zudem kann entweder das Messobjekt bezüglich der Strahlungsquelle und des Detektors bewegt werden oder nur der Detektor wird bewegt, um einen virtuell vergrößerten Detektor zu erhalten. Die Verfahren werden dabei auch kombiniert. In order to measure measuring objects completely with computer tomography, which are larger than the measuring range of the computer tomograph in the respectively selected magnification setting, there are methods in which the measuring object is only partially detected in several partial measurements. A distinction is made between methods in which the measurement object has larger dimensions in the direction of the axis of rotation or at right angles to the axis of rotation than the measuring range of the computer tomograph. In addition, either the measurement object with respect to the radiation source and the detector can be moved or only the detector is moved to obtain a virtually enlarged detector. The procedures are also combined.
Erstreckt sich das Messobjekt lediglich in Richtung der Drehachse des Computertomografen über den Messbereich des Computertomografen hinaus, so werden mehrere Teilmessungen durchgeführt, zwischen denen das Messobjekt entlang
der Drehachse verschoben wird. Hierbei verlässt das Messobjekt den Messbereich rechtwinkelig zur Drehachse in keiner der Drehstellungen. Hierdurch ist es möglich, die Teilmessungen getrennt voneinander auszuwerten, indem die jeweils zugeordneten Durchstrahlungsbilder rekonstruiert werden und Teil-Voxelvolumen berechnet werden. Die Voxelvolumen können im Anschluss zusammengesetzt werden und es kann eine gemeinsame Bestimmung von Oberflächenpunkten anhand von z. B. Schwellwertverfahren durchgeführt werden. Alternativ können auch Oberflächenpunkte an den Teilvolumen bestimmt werden. Das Verfahren ist auch durch Verschieben des Detektors entlang einer Parallelen zur Drehachsrichtung bekannt. If the measurement object only extends beyond the measuring range of the computer tomograph in the direction of the axis of rotation of the computer tomograph, several partial measurements are carried out, between which the measurement object runs along the axis of rotation is moved. In this case, the measuring object leaves the measuring range perpendicular to the axis of rotation in any of the rotational positions. This makes it possible to evaluate the partial measurements separately from one another by reconstructing the respectively assigned radiographic images and calculating partial voxel volumes. The voxel volumes can then be assembled together and it can be a common determination of surface points based on z. B. Threshold method can be performed. Alternatively, surface points on the sub-volume can also be determined. The method is also known by moving the detector along a parallel to the axis of rotation axis.
Die in den Teilmessungen ermittelten Durchstrahlungsbilder können alternativ auch je Drehstellung zu resultierenden Durchstrahlungsbildern zusammengefasst werden. Die Rekonstruktion erfolgt dann an den zusammengesetzten Satz von Durchstrahlungsbildern. Hierbei ist jedoch zu beachten, dass sich die Vergrößerung der Abbildung verändert. Eine notwendige Korrektur der Durchstrahlungsbilder vor dem Zusammenfassen war bislang nicht bekannt, wodurch Messabweichungen entstehen. The radiographic images determined in the partial measurements can alternatively also be combined to resulting radiographic images per rotary position. The reconstruction then takes place on the composite set of transmission images. However, it should be noted that the magnification of the image changes. A necessary correction of the radiographic images before combining was not yet known, which results in measurement deviations.
Verlässt das Messobjekt rechtwinkelig zur Drehachse in zumindest einer Drehstellung den Messbereich des Computertomografen, ist das Messobjekt also quer zur Drehachse breiter als der Messbereich des Computertomografen, so werden mehrere Teilmessungen durchgeführt, bei denen das Messobjekt rechtwinkelig zur Drehachse und gleichzeitig in einer Ebene parallel zur Detektorebene verschoben wird. Bei dieser Vorgehensweise können nur die den jeweiligen Drehstellungen entsprechenden zusammengefassten bzw. zusammengesetzten Durchstrahlungsbilder rekonstruiert werden. Es treten dabei wiederum Vergrößerungsänderungen und perspektivische Verzerrungen auf. Das Verfahren ist auch durch Verschieben des Detektors senkrecht zur Drehachsrichtung in der Detektorebene bekannt. If the measurement object leaves the measuring area of the computer tomograph at right angles to the rotation axis in at least one rotational position, the measurement object is wider than the measurement area of the computer tomograph transversely to the rotation axis, then several partial measurements are carried out in which the measurement object is perpendicular to the rotation axis and simultaneously in a plane parallel to the detector plane is moved. In this procedure, only the combined or composite radiographic images corresponding to the respective rotational positions can be reconstructed. Again, magnification changes and perspective distortions occur. The method is also known by moving the detector perpendicular to the rotational axis direction in the detector plane.
Bei den bekannten Verfahren wird das Messobjekt demnach in seiner Höhe und/oder seiner Breite abgerastert. Hierbei erfolgt eine Verschiebung des Messobjektes bezüglich der Sensorik immer in einer Ebene parallel zur Detektorebene. Hierdurch ändert sich das den Abbildungsmaßstab beschreibende Verhältnis aus dem Abstand Detektor
- Fokuspunkt der Röntgenquelle zu Messobjekt - Fokuspunkt der Röntgenquelle. Die hierdurch auftretenden Messfehler werden bislang nicht korrigiert und führen damit zu der Bestimmung falscher Maße am Messobjekt. Zudem ergeben sich durch die veränderten Auftreffrichtungen der Strahlung auf den Detektor in den unterschiedlichen Relativpositionen perspektivische Verzerrungen. Die jeweils dem gleichen Winkel entsprechenden Durchstrahlungsbilder aus den verschiedenen Relativpositionen werden durch beide Effekte nicht richtig zusammengesetzt. In the known method, the measurement object is therefore scanned in its height and / or its width. Here, a displacement of the measurement object with respect to the sensor always takes place in a plane parallel to the detector plane. As a result, the ratio describing the imaging scale changes from the distance detector - Focus point of the X-ray source to DUT - Focus point of the X-ray source. The measurement errors that occur as a result are not yet corrected and thus lead to the determination of incorrect dimensions on the measurement object. In addition, due to the changed directions of impact of the radiation on the detector, perspective distortions result in the different relative positions. The transmission images corresponding to the same angle from the different relative positions are not correctly combined by the two effects.
Aufgabe der vorliegenden Erfindung ist die Vermeidung von Messfehlern bei den computertomografischen Messungen von Messobjekten in mehreren Relativpositionen zwischen Messobjekt und Röntgensensorik. The object of the present invention is the avoidance of measurement errors in the computed tomographic measurements of measurement objects in a plurality of relative positions between the measurement object and the x-ray sensor system.
Zur Lösung der Aufgabe sieht die Erfindung insbesondere vor, dass die unterschiedlichen Relativpositionen so gewählt werden, dass der Abstand zwischen dem Fokuspunkt der Strahlungsquelle (Brennfleck) und der Drehachse gleich bleibt. To solve the problem, the invention provides in particular that the different relative positions are chosen so that the distance between the focal point of the radiation source (focal spot) and the axis of rotation remains the same.
Insbesondere sieht die Erfindung vor, dass sich die unterschiedlichen Relativpositionen auf einer Kreisbahn um den Fokuspunkt der Strahlungsquelle und in einer Ebene befinden, deren Normalenvektor parallel zur Richtung der Drehachse steht. In particular, the invention provides that the different relative positions are on a circular path around the focal point of the radiation source and in a plane whose normal vector is parallel to the direction of the axis of rotation.
Ein weiterer Vorschlag der Erfindung zeichnet sich dadurch aus, dass jeweils benachbarte Relativpositionen so gewählt werden, dass ein Teil des Messobjektes in einigen der Drehstellungen in jeweils beiden Relativpositionen erfasst wird, also ein Überlappungsbereich existiert. Another proposal of the invention is characterized in that each adjacent relative positions are selected so that a part of the measurement object is detected in some of the rotational positions in each case two relative positions, so an overlap area exists.
Insbesondere ist vorgesehen, dass bei Veränderung der Relativposition auf einer Kreisbahn der feststehende Teil der Drehachse nicht verdreht wird und der drehbare Teil der Drehachse zusammen mit dem Messobjekt zur Festlegung des Startdrehwinkels um den Winkel der veränderten Kreisbahnposition gedreht wird. In particular, it is provided that when changing the relative position on a circular path, the fixed part of the rotation axis is not rotated and the rotatable part of the rotation axis is rotated together with the measurement object for determining the start rotation angle by the angle of the changed orbit position.
Bei der Bewegung der gesamten mechanischen Drehachse an die neue Position wird zunächst die gesamte Ache (unterer Teil, der fest mit dem KMG bzw. den
translatorischen Achsen des KMGs befestigt ist, und oberer Teil, also drehbarer Drehteller mit Messobjekt) samt Messobjekt NUR translatorisch verschoben. Anschließend führt der drehbare Teil der Drehachse (also der Drehteller) eine Drehbewegung aus, um das Messobjekt in die Startwinkelstellung zu drehen. Gleichwirkend könnte auch die gesamte mechanische Drehachse um den Brennfleck rotiert werden. During the movement of the entire mechanical axis of rotation to the new position, first the entire axis (lower part, fixed with the CMM or the translatory axes of the CMM is attached, and upper part, ie rotatable turntable with measuring object) including measuring object ONLY translationally shifted. Subsequently, the rotatable part of the rotation axis (ie the turntable) performs a rotational movement to rotate the measurement object in the starting angle position. Equally effective, the entire mechanical axis of rotation could be rotated around the focal spot.
Die Erfindung zeichnet sich des Weiteren dadurch aus, dass die jeweiligen Drehstellungen in den verschiedenen Relativpositionen in ihrem Startwinkel so festgelegt werden, dass der Einfallswinkel des das Messobjekt erfassenden Bereiches der Messstrahlung im Bezug auf das Messobjektkoordinatensystem gleich bleibt, das Messobjekt im Überlappungsbereich also in der gleichen Richtung durchstrahlt wird, insbesondere der Startdrehwinkel also um den Winkel verändert wird, um den die gesamte mechanische Drehachse um den Brennfleck bewegt wurde. The invention is further characterized in that the respective rotational positions in the different relative positions are set in their starting angle so that the angle of incidence of the measuring object detecting area of the measuring radiation remains the same in relation to the Meßobjektkoordinatensystem, the measurement object in the overlapping area in the same Direction is irradiated, in particular the start rotation angle is thus changed by the angle by which the entire mechanical axis of rotation was moved around the focal spot.
Ziel ist es, dass das Messobjekt in der neuen Lage im Übergangsbereich in der Startdrehstellung so angeordnet ist, dass es in gleicher Richtung durchstrahlt wird, wie bei der Messung in der ersten Lage. Ansonsten könnten die Durchstrahlungsbilder nicht zusammengesetzt werden. Der Übergangsbereich erzeugt also idealer Weise in beiden Relativstellungen das gleiche Durchstrahlungsbild (bzw. Teil des Durchstrahlungsbildes). Das Vereinen der Durchstrahlungsbilder könnte sodann auch mittels Stitching erfolgen. Dies ist aber dann nicht nötig, wenn die Postionen und Drehstellungen bekannt sind. The aim is that the measurement object is arranged in the new position in the transition region in the starting rotational position so that it is irradiated in the same direction, as in the measurement in the first position. Otherwise the radiographic images could not be put together. The transition region thus ideally produces the same radiographic image (or part of the radiographic image) in both relative positions. The combining of the radiographs could then also be done by stitching. But this is not necessary if the positions and rotational positions are known.
Ein erfindungsgemäßer Gedanke sieht des Weiteren vor, dass in allen Relativpositionen die jeweils weiteren Drehstellungen bezüglich des jeweiligen Startwinkels gleich eingestellt werden, vorzugsweise die Drehwinkelschrittweite konstant ist. An inventive concept further provides that in each relative position, the respective further rotational positions are set equal with respect to the respective starting angle, preferably the rotational angle increment is constant.
Die Erfindung sieht auch vor, dass die durch Veränderung des Startwinkels und/oder durch die Relativbewegung des Messobjektes auf einer Kreisbahn entstehenden perspektivischen Verzerrungen der Abbildung auf dem Strahlendetektor korrigiert
werden, vorzugsweise durch Resampling-Verfahren am jeweiligen Durchstrahlungsbild und/oder durch Berücksichtigung bei der Rekonstruktion. The invention also provides that the perspective distortions of the image on the radiation detector corrected by changing the starting angle and / or by the relative movement of the measurement object on a circular path are corrected be, preferably by resampling the respective radiographic image and / or by consideration in the reconstruction.
Insbesondere wird aufgrund der Erfindung vorgeschlagen, dass die verschiedenen Relativpositionen auf einer Kreisbahn um den Fokuspunkt der Strahlungsquelle angeordnet sind, welche sich in einer Ebene befindet, die durch die Drehachse und die direkte Verbindung zwischen Detektormittelpunkt und Strahlungsquelle aufgespannt wird. In particular, it is proposed on the basis of the invention that the various relative positions are arranged on a circular path around the focal point of the radiation source, which is located in a plane which is spanned by the axis of rotation and the direct connection between detector center and radiation source.
Ein weiterer hervorzuhebender Gedanke der Erfindung sieht vor, dass bei Veränderung der Relativposition auf einer Kreisbahn die gesamte mechanische Drehachse entsprechend der Kreisbahnposition verkippt wird und der drehbare Teil der Drehachse zusammen mit dem Messobjekt zur Festlegung des Startdrehwinkels in der Drehstellung verbleibt. Another idea to be emphasized of the invention provides that when changing the relative position on a circular path, the entire mechanical axis of rotation is tilted according to the orbit position and the rotatable part of the axis of rotation remains together with the measurement object for determining the starting rotational angle in the rotational position.
Insbesondere ist die Erfindung dadurch gekennzeichnet, dass die gesamte mechanische Drehachse in den verschiedenen Relativpositionen so in der Ebene aus Drehachse und Verbindung zwischen Detektormitte und Strahlungsquelle verkippt wird, dass der Einfallswinkel des das Messobjekt erfassenden Bereiches der Messstrahlung im Bezug auf das Messobjektkoordinatensystem gleich bleibt, das Messobjekt im Überlappungsbereich also in der gleichen Richtung durchstrahlt wird. In particular, the invention is characterized in that the entire mechanical axis of rotation is tilted in the different relative positions in the plane of rotation axis and connection between the detector center and radiation source, that the angle of incidence of the measuring object detecting area of the measuring radiation remains the same in relation to the measuring object coordinate system, the Measuring object in the overlapping area is thus irradiated in the same direction.
Bevorzugterweise ist nach der Erfindung vorgesehen, dass die durch Veränderung des Startwinkels und/oder durch die Relativbewegung des Messobjektes auf einer Kreisbahn entstehenden perspektivischen Verzerrungen der Abbildung auf dem Strahlendetektor korrigiert werden, vorzugsweise durch die Neigung der gesamten mechanischen Drehachse und/oder durch Resampling am jeweiligen Durchstrahlungsbild und/oder durch Berücksichtigung bei der Rekonstruktion. Preferably, it is provided according to the invention that the perspective distortions of the image on the radiation detector resulting from a change in the starting angle and / or by the relative movement of the measurement object on a circular path are corrected, preferably by the inclination of the entire mechanical axis of rotation and / or by resampling at the respective one Radiation image and / or by consideration during reconstruction.
Aufgrund der erfindungs gemäßen Lehre wird für alle Teilmessungen mit dem gleichen Abbildungsmaßstab gearbeitet. Vorzugsweise werden perspektivische Verzerrungen korrigiert.
Erfindungsgemäß wird die Relativposition zwischen Messobjekt und Röntgensensorik für alle Teilmessungen so eingestellt, dass der gleiche Abbildungsmaßstab vorliegt. Dies wird erreicht, indem die Relativpositionen so gewählt werden, dass der Abstand zwischen dem Fokuspunkt der Strahlungsquelle und dem Messobjekt stets gleich ist. Hierzu ist insbesondere vorgesehen, dass die Relativpositionen auf Kreisbahnen um den Fokuspunkt eingestellt werden. Due to the teaching according to the Invention, the same magnification is used for all partial measurements. Preferably, perspective distortions are corrected. According to the invention, the relative position between the measurement object and the X-ray sensor system is set for all partial measurements such that the same imaging scale is present. This is achieved by selecting the relative positions so that the distance between the focal point of the radiation source and the measurement object is always the same. For this purpose, provision is made in particular for the relative positions to be set on circular paths around the focal point.
Besonders zu beachten ist, dass das Messobjekt nach der Relativverschiebung vor der Strahlungsquelle einen geänderten Drehwinkel einnimmt. Dieser muss durch Drehen des Messobjektes mit dem drehbaren Teil der mechanischen Drehachse so korrigiert werden, dass der Start-Drehwinkel für die mehreren Drehstellungen in der Form angepasst wird, dass die Strahlungsrichtung bezüglich des Messobjektkoordinatensystem gleich bleibt. Außerdem entstehen perspektivische Verzerrungen auf dem Strahlendetektor, weil sich zumindest Teile des Messobjektes nach der Relativverschiebung in einer veränderten Relativlage zum Detektor befinden und somit die sodann das Messobjekt durchstrahlenden Teilstrahlen in einem anderen Winkel auf den Detektor auftreffen. Diese Verzerrungen werden erfindungsgemäß durch Re-Sampling- Verfahren der Durchstrahlungsbilder korrigiert, da die Größe der Verzerrungen aufgrund des bekannten Start- Winkels bekannt ist, und/oder durch die Berücksichtigung der Verzerrung während des Rekonstruktionsalgorithmus. It should be noted in particular that the measured object assumes a changed angle of rotation after the relative displacement in front of the radiation source. This must be corrected by rotating the measurement object with the rotatable part of the mechanical axis of rotation so that the starting angle of rotation is adapted for the plurality of rotational positions in the form that the radiation direction remains the same with respect to the measuring object coordinate system. In addition, perspective distortions arise on the radiation detector, because at least parts of the measurement object are located after the relative displacement in an altered relative position to the detector and thus impinge the then passing through the measurement object partial beams at a different angle to the detector. These distortions are corrected in accordance with the invention by re-sampling the transmission images, since the size of the distortions is known on the basis of the known start angle, and / or by taking account of the distortion during the reconstruction algorithm.
Werden die verschiedenen Relativpositionen nahezu entlang einer Parallelen zur Drehachsrichtung eingenommen, wird erfindungs gemäß die gesamte mechanische Drehachse mit dem Messobjekt selbst so verkippt, dass wiederum der Einfallswinkel der Messstrahlung, die das Messobjekt erfasst, in Bezug auf das Messobjektkoordinatensystem gleich bleibt. Auch in diesem Fall werden die perspektivischen Verzerrungen durch Re-Sampling am Durchstrahlungsbild oder durch Berücksichtigung bei der Rekonstruktion korrigiert. If the various relative positions are assumed to be almost along a line parallel to the axis of rotation, the entire mechanical axis of rotation is tilted with the measurement object itself such that the angle of incidence of the measurement radiation which detects the measurement object remains the same with respect to the measurement object coordinate system. In this case too, the perspective distortions are corrected by re-sampling on the radiographic image or by taking account of the reconstruction.
Weitere Einzelheiten, Vorteile und Merkmale der Erfindung ergeben sich nicht nur aus den Ansprüchen, den diesen zu entnehmenden Merkmalen - für sich und/oder in
Kombination -, sondern auch aus der nachfolgenden Beschreibung von der Zeichnung zu entnehmenden bevorzugten Ausführungsbeispielen. Further details, advantages and features of the invention will become apparent not only from the claims, the features to be taken from them - for themselves and / or in Combination - but also from the following description of the drawing to be taken preferred embodiments.
Es zeigen: Show it:
Fig. 1 eine Anordnung eines Messobjektes in einer ersten Relativposition in 1 shows an arrangement of a measurement object in a first relative position in FIG
Bezug auf eine Röntgensensorik und Terms of an X-ray sensor and
Fig. 2 eine Anordnung eines Messobjektes in einer zweiten Relativposition in 2 shows an arrangement of a measurement object in a second relative position in FIG
Bezug auf die Röntgensensorik. Reference to the X-ray sensor.
Fig. 1 zeigt eine Anordnung eines Messobjektes 1 in einer ersten Relativposition bezüglich einer Röntgensensorik 2, umfassend eine Strahlungsquelle, wie Röntgenquelle mit Fokuspunkt bzw. Brennfleck 3, und einem Detektor 4. Das Messobjekt 1 - auch Bauteil genannt - ist um eine Drehachse 5 drehbar, die in Draufsicht dargestellt ist. Das Bauteil 1 ist fest auf dem drehbaren Teil der Drehachse 5 befestigt. In der dargestellten ersten Relativstellung beträgt der Winkel 6 zwischen der Verbindung zwischen Mitte 7 des Detektors 4 und dem Brennfleck 3 und der Verbindung zwischen der Drehachsmitte 5 und dem Brennfleck 3 null Grad. Teile des Messobjektes 1 ragen in zumindest einigen der Drehstellungen um die Drehachse 5 aus dem durch den Detektor 4 erfassbaren Bereich, begrenzt durch die Ränder 8 und 9 des in die Zeichenebene projizierten Strahlungsbereiches, heraus. Es kann daher nur der einfach schraffierte Bereich 10 des Messobjekts 1 erfasst und gemessen werden. Der nicht schraffierte Bereich kann nicht gemessen werden. Doppelt schraffiert sind die Übergangs- bzw. Überlappungsbereiche 11 und 12 des Messobjekts 1 dargestellt, die in weiteren Relativstellungen zusammen mit den in Fig. 1 nicht schraffierten Bereichen gemessen werden. Der Übergangsbereich 11 wird in der in Fig. 2 dargestellten zweiten Relativposition erneut erfasst und gemessen. 1 shows an arrangement of a measurement object 1 in a first relative position with respect to an X-ray sensor system 2, comprising a radiation source, such as X-ray source with focal point or focal spot 3, and a detector 4. The measurement object 1 -also called component-is rotatable about a rotation axis 5 , which is shown in plan view. The component 1 is fixedly mounted on the rotatable part of the rotation axis 5. In the illustrated first relative position, the angle 6 between the connection between the center 7 of the detector 4 and the focal spot 3 and the connection between the center of rotation axis 5 and the focal spot 3 is zero degrees. Parts of the measurement object 1 project in at least some of the rotational positions about the rotation axis 5 out of the area detectable by the detector 4, limited by the edges 8 and 9 of the radiation area projected into the plane of projection. Therefore, only the single hatched area 10 of the measurement object 1 can be detected and measured. The non-hatched area can not be measured. Duplicated hatched, the transitional or overlapping regions 11 and 12 of the measuring object 1 are shown, which are measured in further relative positions together with the areas not hatched in FIG. The transition region 11 is again detected and measured in the second relative position shown in FIG.
In Fig. 1 wird der Übergangsbereich 11 beispielhaft in dieser ersten Drehstellung um die Drehachse 5, also die Drehstellung des Startwinkels, zum Beispiel von dem
Strahlenbündel 13 unter dem Winkel 14 durchstrahlt. Das Strahlenbündel 13 trifft dabei im Winkel 15 auf den Detektor 4 auf. In Fig. 1, the transition region 11 is exemplified in this first rotational position about the axis of rotation 5, so the rotational position of the starting angle, for example from the Beam 13 passes through the angle 14. The beam 13 strikes the detector 4 at an angle 15.
Erfindungsgemäß erfolgen weitere Messungen zur Bestimmung weiterer Bereiche des Messobjektes 1 in zumindest einer weiteren Relativposition der mechanischen Drehachse 5 und des Messobjektes 1. Hierzu werden die gesamte mechanische Drehachse 5 und das Messobjekt 1 auf einer Kreisbahn 16 um den Brennfleck 3 verschoben. In dem in Fig. 1 dargestellten Beispiel befindet sich diese Kreisbahn in der Zeichenebene, also in einer Ebene, deren Normalenvektor parallel zur Richtung der Drehachse 5 steht. Dies ist ein Spezialfall der Forderung des konstanten Abstandes zwischen Fokuspunkt der Strahlungsquelle (Brennfleck 3) und der Drehachse 5. According to the invention, further measurements are carried out to determine further regions of the measurement object 1 in at least one further relative position of the mechanical rotation axis 5 and the measurement object 1. For this purpose, the entire mechanical rotation axis 5 and the measurement object 1 are displaced on a circular path 16 around the focal spot 3. In the example shown in FIG. 1, this circular path is located in the plane of the drawing, ie in a plane whose normal vector is parallel to the direction of the axis of rotation 5. This is a special case of the requirement of the constant distance between the focal point of the radiation source (focal spot 3) and the axis of rotation 5.
Fig. 2 zeigt eine Anordnung für eine zweite Messung, bei der das Messobjekt 1 und die gesamte mechanische Drehachse 5 in einer zweiten Relativposition bezüglich der Röntgensensorik 2 auf der Kreisbahn 16 verschoben angeordnet ist. Der Winkel 6' zeigt den dabei veränderten Winkel zwischen der Verbindung zwischen Detektormitte 7 und Brennfleck 3 und der Verbindung zwischen der Drehachse 5 und dem Brennfleck 3. Fig. 2 zeigt dabei das Messobjekt 1 im nun veränderten Startwinkel für die verschiedenen Drehstellungen um die Drehachse 5 zur computertomografischen Messung, wobei der Startwinkel genau um den Winkel 6' verändert wurde. Zumindest in dieser Startwinkelstellung wird wiederum der Überlappungsbereich 11 durch die Messstrahlung erfasst, und zwar beispielhaft durch das Strahlenbündel 13', wiederum unter dem gleichen Winkel 14 wie in der ersten Relativposition zwischen Messobjekt und Röntgensensorik. 2 shows an arrangement for a second measurement, in which the measurement object 1 and the entire mechanical rotation axis 5 are displaced in a second relative position relative to the X-ray sensor system 2 on the circular path 16. The angle 6 'shows the changed angle between the connection between the center of the detector 7 and focal point 3 and the connection between the axis of rotation 5 and the focal spot 3. FIG. 2 shows the measuring object 1 in the now changed starting angle for the various rotational positions about the axis of rotation. 5 for computer tomographic measurement, wherein the starting angle was changed exactly by the angle 6 '. At least in this starting angle position, in turn, the overlapping region 11 is detected by the measuring radiation, for example by the radiation beam 13 ', again at the same angle 14 as in the first relative position between the measurement object and the X-ray sensor system.
Hierdurch wird gewährleistet, dass das Messobjekt 1 in der Startwinkelposition in gleichen Messobjektbereichen in gleicher Richtung durchstrahlt wird und damit die Durchstrahlungslänge jeweils gleich ist und dass die jeweils dem gleichen Winkel entsprechenden Durchstrahlungsbilder aus den verschiedenen Relativpositionen richtig zusammengesetzt werden. Das Strahlenbündel 13' trifft jedoch nun im veränderten Winkel 15' auf den Detektor 4. Hierdurch kommt es zu perspektivischen Verzerrungen der Durchstrahlungsbilder. Diese werden erfindungsgemäß durch die bekannten Winkel
15 und 15' korrigiert, und die Durchstrahlungbilder entsprechend geresampelt bzw. wird die Verzerrung in der Rekonstruktion berücksichtigt. This ensures that the measuring object 1 is irradiated in the same direction in the starting angular position in the same measuring object areas and thus the transmission length is the same in each case and that the corresponding respective angle radiographic images from the different relative positions are correctly assembled. However, the beam 13 'now hits the detector 4 at the changed angle 15'. This results in perspective distortions of the radiographic images. These are inventively by the known angle 15 and 15 'are corrected, and the transmission images are sampled accordingly or the distortion is taken into account in the reconstruction.
Um das gesamte Messobjekt 1 computertomografisch zu erfassen, sind gegebenenfalls Messungen in weiteren Relativstellungen des Messobjektes 1 und der gesamten mechanischen Drehachse 5 durch Verschiebung entlang der Kreisbahn 16 notwendig. Analog zu dem in Fig. 2 erläuterten Vorgehen wird beispielsweise bei entgegengesetzter Bewegung um den Winkel 6' auf der Kreisbahn 16 der Überlappungsbereich 12 des Messobjektes 1 erfasst. Auch hierbei wird der Startdrehwinkel wiederum so eingestellt, dass die Durchstrahlung, in diesem Fall durch das Strahlenbündel 17, wieder in der gleichen Richtung erfolgt. In order to capture the entire measurement object 1 by computer tomography, measurements in further relative positions of the measurement object 1 and the entire mechanical rotation axis 5 by displacement along the circular path 16 may be necessary. Analogous to the procedure explained in FIG. 2, the overlap region 12 of the measurement object 1 is detected, for example, in the case of an opposite movement about the angle 6 'on the circular path 16. Again, the starting rotation angle is again set so that the transmission, in this case by the beam 17, again in the same direction.
Ein analoges Vorgehen erfolgt bei der Verschiebung der gesamten mechanischen Drehachse mit dem Messobjekt entlang einer Kreisbahn, welche sich in einer Ebene befindet, die aus der Drehachse und der direkten Verbindung zwischen Detektormittelpunkt und Strahlungsquelle (Brennfleck) gebildet wird. Im Gegensatz zu den Darstellungen in Fig. 1 und 2 verläuft die Drehachse parallel zur längeren, dargestellten Körperkante des Messobjektes 1 und in der Zeichnungsebene, und das Messobjekt ist mittig über der mechanischen Drehachse, also in Richtung der Drehachse angeordnet. Grundlegend können aber die Fig. 1 und 2 zur Verdeutlichung herangezogen werden. In der zweiten Relativposition entsprechend Fig. 2 erfolgt dann aber keine Anpassung des Startdreh winkels, sondern die gesamte mechanische Drehachse wird gemeinsam mit dem Messobjekt in der Zeichnungsebene gekippt.
An analogous procedure takes place in the displacement of the entire mechanical axis of rotation with the measurement object along a circular path, which is located in a plane which is formed from the axis of rotation and the direct connection between the detector center and radiation source (focal spot). In contrast to the illustrations in FIGS. 1 and 2, the axis of rotation runs parallel to the longer, illustrated body edge of the measurement object 1 and in the plane of the drawing, and the measurement object is arranged centrally above the mechanical axis of rotation, ie in the direction of the axis of rotation. Fundamentally, however, FIGS. 1 and 2 can be used for clarification. In the second relative position corresponding to Fig. 2 but then no adjustment of the starting rotation angle takes place, but the entire mechanical axis of rotation is tilted together with the measurement object in the drawing plane.
Claims
1. Computertomografie- Verfahren zur dimensioneilen Bestimmung von Merkmalen an einem Messobjekt, bei dem das auf einer mechanischen Drehachse befestigte Messobjekt in mehreren Relativpositionen bezüglich der Sensorik, zumindest bestehend aus Strahlungsquelle und 2-dimensionalen Detektor, jeweils in mehreren Drehstellungen um eine Drehachse von der Strahlung der Strahlungsquelle durchstrahlt wird und jeweils zugehörige 2D- Durchstrahlungsbilder aufgenommen werden, wobei die Durchstrahlungsbilder aus den verschiedenen Relativpositionen jeweils zu einem resultierenden Durchstrahlungsbild zusammengesetzt werden, die bezüglich des jeweiligen Startdrehwinkels der verschiedenen Relativpositionen bei der gleichen Drehstellung aufgenommen worden, und aus den resultierenden Durchstrahlungsbildern mittels Rekonstruktion 3-dimensionale Volumeninformationen im Voxelformat (so genanntes Voxelvolumen) berechnet werden, wobei in diesem Voxelvolumen Daten zur lokalen Strahlabsorption enthalten sind, wobei vorzugsweise aus den Voxeldaten, im Bereich der Materialübergänge, Oberflächenpunkte generiert werden, 1. Computed tomography method for the dimensional determination of features on a measurement object, wherein the mounted on a mechanical axis measurement object in several relative positions with respect to the sensor, at least consisting of radiation source and 2-dimensional detector, each in a plurality of rotational positions about a rotation axis of the radiation the radiation source is irradiated and respectively associated 2D radiographic images are taken, wherein the radiographic images from the different relative positions are each assembled into a resulting radiographic image, which was taken with respect to the respective starting rotational angle of the various relative positions at the same rotational position, and from the resulting radiographic images by means of reconstruction 3-dimensional volume information in voxel format (so-called voxel volume) are calculated, in which voxel volume data for local beam absorption are included , where surface points are preferably generated from the voxel data, in the area of the material transitions,
dadurch gekennzeichnet, characterized,
dass die unterschiedlichen Relativpositionen so gewählt werden, dass der Abstand zwischen dem Fokuspunkt der Strahlungsquelle (Brennfleck) und der Drehachse gleich bleibt. that the different relative positions are selected so that the distance between the focal point of the radiation source (focal spot) and the axis of rotation remains the same.
2. Verfahren nach zumindest einem der vorhergehenden Ansprüche, 2. Method according to at least one of the preceding claims,
dadurch gekennzeichnet, characterized,
dass sich die unterschiedlichen Relativpositionen auf einer Kreisbahn um den Fokuspunkt der Strahlungsquelle und in einer Ebene befinden, deren Normalenvektor parallel zur Richtung der Drehachse steht.
that the different relative positions are in a circular orbit around the focal point of the radiation source and in a plane whose normal vector is parallel to the direction of the axis of rotation.
3. Verfahren nach zumindest einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, 3. Method according to at least one of the preceding claims, characterized in that
dass jeweils benachbarte Relativpositionen so gewählt werden, dass ein Teil des Messobjektes in einigen der Drehstellungen in jeweils beiden Relativpositionen erfasst wird, also ein Überlappungsbereich existiert. that respective adjacent relative positions are selected such that a part of the measurement object is detected in some of the rotational positions in respectively two relative positions, ie an overlapping area exists.
4. Verfahren nach zumindest einem der vorhergehenden Ansprüche, 4. The method according to at least one of the preceding claims,
dadurch gekennzeichnet, characterized,
dass bei Veränderung der Relativposition auf einer Kreisbahn der feststehende Teil der Drehachse nicht verdreht wird und der drehbare Teil der Drehachse zusammen mit dem Messobjekt zur Festlegung des Startdrehwinkels um den Winkel der veränderten Kreisbahnposition gedreht wird. that when changing the relative position on a circular path of the fixed part of the rotation axis is not rotated and the rotatable part of the rotation axis is rotated together with the measurement object for determining the starting rotation angle by the angle of the changed orbit position.
5. Verfahren nach zumindest einem der vorhergehenden Ansprüche, 5. The method according to at least one of the preceding claims,
dadurch gekennzeichnet, characterized,
dass die jeweiligen Drehstellungen in den verschiedenen Relativpositionen in ihrem Startwinkel so festgelegt werden, dass der Einfallswinkel des das Messobjekt erfassenden Bereiches der Messstrahlung im Bezug auf das Messobjektkoordinatensystem gleich bleibt, das Messobjekt im Überlappungsbereich also in der gleichen Richtung durchstrahlt wird, insbesondere der Startdrehwinkel also um den Winkel verändert wird, um den die gesamte mechanische Drehachse um den Brennfleck bewegt wurde. the respective rotational positions in the different relative positions are determined in their starting angle such that the angle of incidence of the measuring area of the measuring radiation remains the same with respect to the measuring object coordinate system, ie the measuring object in the overlapping area is irradiated in the same direction, in particular the starting rotational angle the angle is changed by which the entire mechanical axis of rotation was moved around the focal spot.
6. Verfahren nach zumindest einem der vorhergehenden Ansprüche, 6. The method according to at least one of the preceding claims,
dadurch gekennzeichnet, characterized,
dass in allen Relativpositionen die jeweils weiteren Drehstellungen bezüglich des jeweiligen Startwinkels gleich eingestellt werden, vorzugsweise die Drehwinkelschrittweite konstant ist.
that in each relative position, the respective further rotational positions are set equal with respect to the respective starting angle, preferably the rotational angle increment is constant.
7. Verfahren nach zumindest einem der vorhergehenden Ansprüche, 7. The method according to at least one of the preceding claims,
dadurch gekennzeichnet, characterized,
dass die durch Veränderung des Startwinkels und/oder durch die Relativbewegung des Messobjektes auf einer Kreisbahn entstehenden perspektivischen Verzerrungen der Abbildung auf dem Strahlendetektor korrigiert werden, vorzugsweise durch Resampling-Verfahren am jeweiligen Durchstrahlungsbild und/oder durch Berücksichtigung bei der Rekonstruktion. in that the perspective distortions of the image on the radiation detector resulting from a change in the starting angle and / or by the relative movement of the measurement object on a circular path are corrected, preferably by resampling methods on the respective radiographic image and / or by consideration during the reconstruction.
8. Verfahren nach zumindest einem der vorhergehenden Ansprüche, 8. The method according to at least one of the preceding claims,
dadurch gekennzeichnet, characterized,
dass die verschiedenen Relativpositionen auf einer Kreisbahn um den Fokuspunkt der Strahlungsquelle angeordnet sind, welche sich in einer Ebene befindet, die durch die Drehachse und die direkte Verbindung zwischen Detektormittelpunkt und Strahlungsquelle aufgespannt wird. in that the various relative positions are arranged on a circular path around the focal point of the radiation source, which is located in a plane which is spanned by the axis of rotation and the direct connection between the detector center and the radiation source.
9. Verfahren nach zumindest einem der vorhergehenden Ansprüche, 9. The method according to at least one of the preceding claims,
dadurch gekennzeichnet, characterized,
dass bei Veränderung der Relativposition auf einer Kreisbahn die gesamte Drehachse entsprechend der Kreisbahnposition verkippt wird und der drehbare Teil der Drehachse zusammen mit dem Messobjekt zur Festlegung des Startdrehwinkels in der Drehstellung verbleibt. that when changing the relative position on a circular path, the entire rotation axis is tilted according to the circular path position and the rotatable part of the rotation axis remains together with the measurement object for determining the starting rotation angle in the rotational position.
10. Verfahren nach zumindest einem der vorhergehenden Ansprüche, 10. The method according to at least one of the preceding claims,
dadurch gekennzeichnet, characterized,
dass die gesamte mechanische Drehachse in den verschiedenen Relativpositionen so in der Ebene aus Drehachse und Verbindung zwischen Detektormitte und Strahlungsquelle verkippt wird, dass der Einfallswinkel des das Messobjekt erfassenden Bereiches der Messstrahlung im Bezug auf das Messobjektkoordinatensystem gleich bleibt, das Messobjekt im Überlappungsbereich also in der gleichen Richtung durchstrahlt wird.
that the entire mechanical axis of rotation in the different relative positions is tilted in the plane of rotation axis and connection between detector center and radiation source, that the angle of incidence of the measuring object detecting area of the measuring radiation remains the same in relation to the measuring object coordinate system, the measurement object in the overlapping area in the same Direction is irradiated.
11. Verfahren nach zumindest einem der vorhergehenden Ansprüche, 11. The method according to at least one of the preceding claims,
dadurch gekennzeichnet, characterized,
dass die durch Veränderung des Startwinkels und/oder durch die Relativbewegung des Messobjektes auf einer Kreisbahn entstehenden perspektivischen Verzerrungen der Abbildung auf dem Strahlendetektor korrigiert werden, vorzugsweise durch die Neigung der gesamten mechanischen Drehachse und/oder durch Resampling am jeweiligen Durchstrahlungsbild und/oder durch Berücksichtigung bei der Rekonstruktion.
in that the perspective distortions of the image on the radiation detector resulting from a change in the starting angle and / or by the relative movement of the measurement object on a circular path are corrected, preferably by the inclination of the entire mechanical axis of rotation and / or by resampling on the respective radiographic image and / or by taking into account the reconstruction.
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DE102012103984A DE102012103984A1 (en) | 2012-05-07 | 2012-05-07 | Method for determining features of a measurement object |
PCT/EP2013/059149 WO2013167461A1 (en) | 2012-05-07 | 2013-05-02 | Method for determining features of a measurement object |
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EP2847579A1 true EP2847579A1 (en) | 2015-03-18 |
Family
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EP13724746.6A Withdrawn EP2847579A1 (en) | 2012-05-07 | 2013-05-02 | Method for determining features of a measurement object |
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EP (1) | EP2847579A1 (en) |
DE (1) | DE102012103984A1 (en) |
WO (1) | WO2013167461A1 (en) |
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DE102015101378A1 (en) | 2014-01-30 | 2015-07-30 | Werth Messtechnik Gmbh | Apparatus and method for measuring characteristics of workpieces with computed tomography |
FR3073044B1 (en) * | 2017-10-27 | 2020-10-02 | Tiama | METHOD AND DEVICE FOR MEASURING DIMENSIONS BY X-RAYS, ON EMPTY GLASS CONTAINERS RUNNING IN LINE |
FR3073043B1 (en) * | 2017-10-27 | 2019-11-15 | Tiama | METHOD AND INSTALLATION FOR ONLINE DIMENSIONAL CONTROL OF MANUFACTURED OBJECTS |
US11604152B2 (en) * | 2019-10-09 | 2023-03-14 | Baker Hughes Oilfield Operations Llc | Fast industrial computed tomography for large objects |
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US5119408A (en) * | 1990-10-31 | 1992-06-02 | General Electric Company | Rotate/rotate method and apparatus for computed tomography x-ray inspection of large objects |
WO2003081220A2 (en) * | 2002-03-19 | 2003-10-02 | Breakaway Imaging, Llc | Computer tomograph with a detector following the movement of a pivotable x-ray source |
DE102005036527B4 (en) * | 2005-08-03 | 2008-05-21 | Yxlon International X-Ray Gmbh | X-ray CT test system and CT method for testing objects |
DE102006041033B4 (en) * | 2006-09-01 | 2017-01-19 | Siemens Healthcare Gmbh | Method for reconstructing a three-dimensional image volume |
DE102006046692B3 (en) * | 2006-09-29 | 2008-02-14 | Siemens Ag | X-ray image recording of non-central image area involves rotating support about axis through focus prior to each recording for non-central position so central ray of x-ray beam passes through center of region of interest during recording |
-
2012
- 2012-05-07 DE DE102012103984A patent/DE102012103984A1/en not_active Withdrawn
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2013
- 2013-05-02 WO PCT/EP2013/059149 patent/WO2013167461A1/en active Application Filing
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WO2013167461A1 (en) | 2013-11-14 |
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