Method for operating a coordinate measuring device, and device for carrying out same

Abstract

The invention relates to a method and a device for carrying out a computer tomography. Radiographs are recorded and used to determine the volume data, said radiographs being recorded when travelling along a mixed trajectory consisting of at least one circular measuring part (C1, C2) and at least one helical measuring part (H1, H2, H3).

Description

[0001] Description

[0002] Method for operating a coordinate measuring machine and device for carrying out

[0003] The invention relates to a method for operating a computed tomography scanner or computed tomography sensor (CT sensor), particularly preferably in a coordinate measuring machine (CMM) with computed tomography scanner or computed tomography sensor (CT sensor), and a corresponding device for carrying out the method.

[0004] In computed tomography (CT) using a CT scanner or CT sensor, the workpiece to be examined is positioned between a radiation source—in the case of X-ray computed tomography, an X-ray source (source)—and a radiation detector (detector). This allows the detector to acquire radiographic images of the workpiece at different rotational positions relative to the source and detector. These images are then reconstructed into a volumetric dataset (voxel volume, often simply referred to as "volume"). Typically, the workpiece is mounted on a rotary table to achieve the different rotational positions by rotating it around a central axis. Alternatively, the workpiece may remain stationary, with the source and detector rotating around the workpiece.In laminography, extended trajectories (also referred to as acquisition geometry, with corresponding characterizing acquisition geometry parameters) are provided for the movement of the workpiece, source, and detector relative to each other, particularly to enable the measurement of workpieces that cannot be tomographed using a 360° rotation, for example, because otherwise a collision of the workpiece with the source or detector would occur, or to examine workpieces more quickly than with computed tomography by acquiring radiographic images in a smaller number of rotational positions. The methods described in the present invention with regard to computed tomography measurement (computed tomography), in particular correction methods, are also applicable analogously to laminography.

[0005] The detector used to acquire the 2D radiographic images is usually planar, i.e., designed as a 2D detector, and consists of a scintillator layer in which the X-rays are converted into light, tubular light channels located behind it in the direction of radiation (which reduce crosstalk between different detector areas), and a pixel matrix directly behind it, i.e., a planar matrix camera such as a CCD or CMOS camera. Alternatively, similarly designed line detectors with one or a few lines are also known. However, to acquire large measurement areas, the workpiece must be moved perpendicular to the line direction and irradiated multiple times, which is time-consuming. In this case, individual layers are also reconstructed separately. Therefore, the invention advantageously uses planar detectors or detectors with a planar detection area such as a planar scintillator layer.

[0006] More cost-effective detectors are achievable if the scintillator layer and the matrix camera are built separately, with imaging optics positioned between them, and often the beam path is deflected to protect the camera (so-called mirror detectors), as described in US 7,400,704 and DE102020102849.

[0007] The reconstructed volume data can initially be used to conduct investigations concerning the interior of the workpiece, for example, to locate and characterize voids, pores, inclusions, fibers, or similar internal or near-surface features (such as cracks) (e.g., with regard to size, volume, location, orientation, number; material, etc.). To enable dimensional measurements, surface points are generated from the volume data, for example, in STL format (STL - Standard Triangulation Language), and linked to dimensions or similar parameters that describe the geometric properties of a workpiece. The computed tomography scanner is then configured as a coordinate measuring machine or coordinate measuring system. The invention also provides for this application in laminography processes, which are performed, for example, with the computed tomography scanner.To achieve precise measurements, one of the necessary conditions is that a high spatial resolution of the workpiece structures (structural resolution) is ensured, which usually results from the specific measurement task. Here, two dominant effects, among others, come into play: the focal spot size of the X-ray emitting spot (focus) of the X-ray tube and the pixel resolution of the detector used. The structural resolution is to be considered in the plane or length of the workpiece and is referred to here as the effective structural resolution, but it can be further refined by taking into account the CT geometry (position of source, workpiece, etc.).The axis of rotation and detector relative to each other (also referred to as the recording geometry), in particular the geometric image scale A, which results from the ratio FDD (focus to detector distance) to FOD (focus to object distance), i.e. the position of the workpiece between source and detector, more precisely between the focal spot (focus) of the source emitting the measurement radiation and the detector, can also be transformed into the detector plane and considered, and vice versa.

[0008] Known computed tomography (CT) methods include not only simple trajectories such as rotating the workpiece by 360° plus the cone angle of the X-rays detected by the detector (circle trajectory), but also helical trajectories, in which the workpiece and detector, or the workpiece and the source-detector unit, are shifted relative to each other in the direction of the rotation axis during the workpiece's rotation. Advantageously, this method images all areas of the workpiece with particularly low error in the center of the detector (central plane) in at least one rotational position, thus avoiding so-called cone-beam artifacts. Furthermore, CT methods are known as binning or...Detector binning is known, in which several adjacent detector pixels of the detector are combined into a single pixel, for example, 2x2 pixels, 4x4 pixels, or 8x8 pixels, to generate higher pixel intensities and thus lower-noise measurement signals. Automatic loading systems for computed tomography scanners are also known, in which the workpiece to be measured is placed on the rotary table by an automatic changer and subsequently removed and, if necessary, placed back into a magazine, as described, for example, in DE102012113109 of the applicant. However, solutions are also known in which the workpiece is loaded and unloaded by means of a robot, for example, by having the robot arm reach through a closable opening in the housing of the CT sensor, which is usually used to shield the X-rays, or by having an airlock in the shielding.

[0009] A disadvantage of known methods and devices is that measuring workpieces that are difficult to penetrate with radiation, such as batteries or battery components, especially for electric vehicles, requires high radiation energies. This results in either long measurement times for small focal spots or short measurement times for large focal spots, which reduces the achievable structural resolution. Consequently, small features on workpieces that require high structural resolution cannot be measured accurately enough in a short time.

[0010] The object of the present invention is therefore to enable computed tomography measurements in which the high energy required for irradiating workpieces that are difficult to penetrate results in high structural resolution even with short measurement times. Furthermore, low costs and low maintenance requirements are to be achieved.

[0011] To solve this problem, the invention provides for the use of an increased frame rate for detector readout, and / or the selection of a particularly short distance between the focal spot of the X-ray tube and the detector, and / or the use of a helical trajectory for at least part of the CT measurement. To further address this issue, the invention also proposes binned operation of the detector, which allows the frame rate to be increased even further in addition to the application of an AOI (array object interference).

[0012] An inventive method for operating a computed tomography sensor (CT sensor) for measuring workpieces provides a CT sensor, comprising at least: at least one radiation source (source), preferably an X-ray tube, for generating the measurement radiation; at least one radiation detector (detector) having several detector elements (detector pixels) sensitive to the measurement radiation, wherein detector pixels preferably form a 2D pixel matrix; and a rotary table for relative rotation between the workpiece and the unit consisting of the source and detector, preferably a rotary table for rotating the workpiece. The method further provides that transmission images are acquired with the detector in several rotational positions between the workpiece and the unit consisting of the source and detector, from which volume data are calculated by means of reconstruction, wherein surface data are preferably calculated from the volume data. The method is characterized by the fact thatthat one or more of the following measures are implemented during operation of the CT sensor: the detector is operated in an AOI (Area of ​​Interest) mode, wherein only a limited number of pixels within an AOI (Area of ​​Interest) are read out from the available detector pixels, preferably the limited area (AOI) is a rectangular sub-area of ​​the 2D pixel matrix, and wherein a higher frame rate is set compared to reading out all available detector pixels, the FDD (Focus Detector Distance) between the source, in particular the radiation-emitting focal spot of the source, and the detector is set low, preferably less than 500 mm, particularly preferably less than 300 mm, in order to achieve high efficiency in detecting the measurement radiation, a helical trajectory is followed for at least part of the CT measurement.In this process, in addition to the relative rotation of the workpiece, an offset along the direction of the rotary table's axis of rotation is set between successively acquired radiographic images by adjusting the workpiece and / or the source and detector unit in the direction of the rotary table's axis of rotation.

[0013] The invention is particularly characterized by the fact that a small FDD, preferably less than 500 mm, and especially less than 300 mm, is set, and at least part of the CT measurement is performed in the form of a helical trajectory. Preferably, the detector is operated with binning, preferably in 2x2 binning, 4x4 binning, or 8x8 binning, preferably with a higher frame rate than in unbinned operation.

[0014] It should also be emphasized that the AOI of the detector is set so small that the available bandwidth of the detector for transmitting the radiographic images allows for a particularly high frame rate, preferably the AOI is set so small that for very short integration times for acquiring the radiographic images, the waiting time between two successive image acquisitions is as short as possible.

[0015] Setting a small AOI (Automated Optical Interference) ensures particularly fast measurements. Firstly, a smaller AOI allows for faster data readout from the detector pixels, and secondly, it reduces the amount of data that the detector subsequently transmits and processes for further analysis, such as reconstruction. Both of these factors enable an increased frame rate, which, when shorter integration times are set for radiographic image acquisition, results in shorter waiting times between successive image acquisitions. Shorter integration times lead to less motion blur, thus enabling sharp image acquisition even with fast movements. Furthermore, the shorter waiting times increase the energy fraction of the measurement radiation used. Both of these factors contribute to faster measurement.

[0016] The invention is also characterized in that an X-ray tube is used as the source, in which the generator required for supplying the X-ray source with high voltage is arranged within the radiation protection housing, preferably flanged to the vacuum tube of the X-ray source, and particularly preferably a vacuum pump is flanged to the vacuum tube.

[0017] The invention provides, notably, that an X-ray tube with a transmission target is used as the source, and that high beam powers are set with a small focal spot size, preferably approximately 80 watts and a focal spot size of less than 25 pm. Transmission targets fundamentally enable relatively small focal spots, e.g., less than 25 mm, even at higher beam powers, e.g., 80 watts, thereby achieving both high beam power and high structural resolution.

[0018] In particular, the invention is characterized in that the CT sensor is operated in a coordinate measuring machine, preferably together with other sensors such as tactile, tactile-optical and / or optical sensors, wherein the sensors preferably provide measurement data in a uniform coordinate system.

[0019] Preferably, it is provided that internal or near-surface features such as cavities, pores, cracks, inclusions, fibers are determined from the volume data and / or that geometric properties, in particular dimensions of the workpiece, are determined from the surface data.

[0020] It should also be emphasized that a mixed trajectory consisting of circle measurement sections and helix measurement sections is set.

[0021] The inventive idea of ​​using mixed trajectories contributes to solving the problem underlying the invention, since a greater proportion of the energy density provided by the source is utilized, thereby reducing the measurement time or achieving more signal or a higher signal-to-noise ratio per measurement period. Details regarding mixed trajectories are described in detail below in this document within the context of a separate invention. However, the invention also provides for combining the solutions of the two inventions. In particular, the inventive idea described first here is intended to encompass all solutions of the mixed trajectory idea described below.

[0022] The invention also provides a device (computed tomography scanner / computed tomography sensor) for carrying out the method according to the invention. To achieve this, the invention proposes a computed tomography sensor (CT sensor) for measuring workpieces, wherein the CT sensor comprises at least:

[0023] - at least one radiation source (source), preferably an X-ray tube, for generating the measurement radiation, at least one radiation detector (detector) comprising several detector elements (detector pixels) sensitive to the measurement radiation, wherein detector pixels preferably form a 2D pixel matrix, and a rotary table for relative rotation between the workpiece and the unit consisting of the source and detector, preferably a rotary table for rotating the workpiece, and wherein the CT sensor is configured to record transmission images with the detector in several rotational positions between the workpiece and the unit consisting of the source and detector, from which volume data can be calculated by means of reconstruction, wherein surface data can preferably be calculated from the volume data, wherein the CT sensor is characterized in that the CT sensor has one or more of the following configurations: the detector is operable in at least one AOI mode (Area of ​​Interest mode),wherein only a limited number of pixels within an AOI (Area of ​​Interest) can be read out from the available detector pixels, preferably a rectangular sub-area of ​​the 2D pixel matrix being adjustable as the limited area (AOI), and wherein a higher frame rate is adjustable compared to reading out all available detector pixels, the FDD (Focus Detector Distance) between the source, in particular the radiation-emitting focal spot of the source, and the detector is designed to be small or is easily adjustable, preferably less than 500 mm, particularly preferably less than 300 mm, in order to achieve high efficiency in detecting the measurement radiation, preferably the CT sensor has a movement axis, particularly preferably a measurement axis, for adjusting the FDD, and a helical trajectory is adjustable for at least part of the CT measurement.In this invention, in addition to the relative rotation of the workpiece, an offset along the direction of the rotary table's axis of rotation can be set between successively acquired radiographic images, provided that the CT sensor has at least one measuring axis with which the workpiece and / or the source-detector unit can be adjusted in the direction of the rotary table's axis of rotation. The invention is particularly characterized in that a small FDD, preferably less than 500 mm, and especially less than 300 mm, can be set, and at least part of the CT measurement can be performed in the form of a helical trajectory.

[0024] Preferably, the detector is designed to be binned, preferably in 2x2 binning or 4x4 binning or 8x8 binning, preferably allowing a higher frame rate than in unbinned operation.

[0025] It should also be emphasized that the AOI of the detector can be adjusted so small that the available bandwidth of the detector for transmitting the radiographic images enables a particularly high frame rate, preferably the AOI can be adjusted so small that for very short integration times for acquiring the radiographic images, the waiting time between two successive image acquisitions is as short as possible.

[0026] The invention is also characterized in that an X-ray tube is arranged as the source, in which the generator required for supplying the X-ray source with high voltage is arranged within the radiation protection housing, preferably flanged to the vacuum tube of the X-ray source, and particularly preferably a vacuum pump is flanged to the vacuum tube.

[0027] The invention provides, notably, that an X-ray tube is arranged as the source, which has a transmission target, and that high beam powers with small focal spot size are adjustable, preferably approximately 80 watts of power and a focal spot size of less than 25 pm.

[0028] In particular, the invention is characterized in that the CT sensor is arranged in a coordinate measuring machine, preferably together with other sensors such as tactile, tactile-optical and / or optical sensors, wherein the sensors are preferably designed to provide measurement data in a uniform coordinate system.

[0029] Preferably, the device is provided to have an evaluation unit with which internal or near-surface features such as cavities, pores, cracks, inclusions, fibers can be determined from the volume data and / or with which geometric properties, in particular dimensions of the workpiece, can be determined from the surface data.

[0030] It should also be emphasized that a mixed trajectory consisting of circle measurement sections and helix measurement sections can be set. Possible details of these mixed trajectories are described below, and the invention provides for combining them as well.

[0031] The subject of an independent invention is a method for performing a mixed trajectory with a computed tomography scanner or computed tomography sensor (CT sensor) and a corresponding device for performing the method.

[0032] Well-known CT techniques include the previously described circle trajectories and helical trajectories. However, neither technique is inherently suitable for simultaneously achieving high structural resolution and accuracy while also requiring short scan times. Circle trajectories suffer from the disadvantage of cone-beam artifacts, which limit the achievable resolution and accuracy. Helical trajectories can avoid these effects, at least for slices imaged in the central plane, but the scan time is very long because the radiation dose received by the detector is low.

[0033] A further object of the present invention is therefore to provide a method and a device for carrying out the method that are suitable for enabling computed tomography measurements in which precise measurement of workpieces with high structural resolution is achievable even in short measurement times. In particular, a shorter measurement time with the same noise level, or lower noise with the same measurement time, should be achieved compared to the prior art. Furthermore, a more cost-effective device should be enabled that performs the required measurement with a shorter axis stroke for adjusting the offset in a helical trajectory, or allows for a larger measurement volume with the same axis stroke. In addition, a further reduction in time should be achieved by reducing the total number of radiographic images to be acquired and reconstructed.The invention provides a solution by using a mixed trajectory consisting of circle and helical measurement sections. In the simplest case, a circle trajectory is combined with a helical trajectory. However, combinations of multiple helical and circle measurement sections are also possible. This advantageously reduces the total number of radiographs required for the solution and makes better use of the available energy (dose) from the source, particularly because so-called empty images do not occur at the beginning and end of the measurement, i.e., areas not needed for reconstructing the volume data are not captured.

[0034] In particular, the use of mixed trajectories makes it possible to utilize a greater proportion of the energy density provided by the source, thereby reducing the measurement time or achieving more signal or a higher signal-to-noise ratio per measurement time.

[0035] The following solutions can preferably also be combined with the idea described above.

[0036] Another method according to the invention for operating a computed tomography sensor (CT sensor) for measuring a workpiece provides a CT sensor, at least comprising:

[0037] - at least one radiation source (source), preferably an X-ray tube, for generating the measurement radiation, at least one radiation detector (detector) comprising several detector elements (detector pixels) sensitive to the measurement radiation, wherein detector pixels preferably form a 2D pixel matrix, and a rotary table for relative rotation between the workpiece and the unit consisting of the source and detector, preferably a rotary table for rotating the workpiece, wherein the method further provides that transmission images are recorded with the detector in several rotational positions between the workpiece and the unit consisting of the source and detector, from which volume data are calculated by means of reconstruction, wherein surface data are preferably calculated from the volume data, wherein the method is characterized in that transmission images are recorded and used to determine the volume data.which are recorded during the traversal of a mixed trajectory consisting of at least one circle measurement section and at least one helix measurement section, preferably during the traversal of at least two helix measurement sections and at least one circle measurement section, and particularly preferably during the traversal of at least three helix measurement sections and at least two circle measurement sections.

[0038] The term "workpiece" refers to the entire workpiece, a collection of several workpieces, or even just a portion of a workpiece. For simplicity, we will henceforth refer only to the workpiece, thus characterizing the area to be measured. The terms "section of a workpiece" or "section of the workpiece" used below refer, accordingly, alternatively to the entire workpiece to be measured, the collection of several workpieces to be measured, or the portion of a workpiece to be measured, and denote a limited section of the overall area to be measured. The workpiece is subsequently described in so-called layers, where the layers are sections through the workpiece in a plane that is perpendicularly intersected by the direction of rotation of the rotary table.If the axis of rotation runs vertically, for example, the multiple layers of the workpiece extend one above the other in horizontal planes, resulting in a top layer and a bottom layer, which define the upper and lower edges of the workpiece in the horizontal plane, respectively. The top layer will henceforth be referred to as the upper edge of the workpiece, and the bottom layer as the lower edge of the workpiece.

[0039] The term "mixed trajectory" indicates that, for acquiring the required radiographic images, not only are circular measurement sections of a circular trajectory or helix measurement sections of a helix trajectory scanned, but rather measurement sections from both trajectories are scanned. As a result, volumetric data for the measurement volume acquired by the CT sensor are calculated.

[0040] A circle measurement section is a part or a complete circle trajectory in which radiographs are acquired in several rotational positions, without any additional offset, for example, in the direction of the rotary table's axis of rotation, between successively acquired radiographs. It is therefore a purely rotational movement of the workpiece being measured. In a complete circle trajectory, the workpiece is rotated from a starting position by an angle of slightly more than 360° to an end position, usually by 360° plus the fan angle of the radiation detected by the detector. However, circle trajectories are also available in which the workpiece is rotated by only slightly more than 180°, for example, 180° plus the fan angle; these are also known as rapid tomography. The starting position and end position refer to the position of the workpiece at the beginning and end of the measurement, respectively.The end of the recording of the multiple radiographic images may differ, in the case of a circle trajectory, only in the rotational position of the workpiece, but not in its position within the measuring volume.

[0041] A helical measurement section is a part or a complete helical trajectory in which radiographs are acquired in multiple rotational positions. In addition to rotating the workpiece, an offset along the direction of the rotary table's axis of rotation is introduced between successively acquired radiographs by moving the workpiece and / or the source-detector unit from the starting position to the end position along the rotary table's axis of rotation. This is therefore not a purely rotary movement; rather, the workpiece is moved along a helical path relative to the tube-detector unit. In a complete helical trajectory, the workpiece is rotated until, in conjunction with the offset along the rotary table's axis of rotation, all desired areas of the workpiece are imaged at the desired location on the detector.For example, a desired condition might be that all areas (layers) of the workpiece are imaged on the detector in at least one rotational orientation in the central plane, also known as the Tuy condition. Depending on the offset, a rotation of 360° or 180° might be required, each also including the fan angle. The start and end positions again refer to the position of the workpiece at the beginning and end of the acquisition of the multiple radiographic images, respectively, and may differ, in the case of a helical trajectory, in the rotational orientation of the workpiece and in its position within the measurement volume in the direction of the rotary table's axis of rotation.

[0042] The central plane is the plane to which the axis of rotation of the turntable is perpendicular and in which the central beam of the measurement radiation travels. Typically, the central beam strikes the detector perpendicularly or almost perpendicularly. In the following, the linear region of the detector that captures the central plane is referred to as the image center. The two edges of the measurement area captured by the detector that run parallel to the central plane are referred to as the edges of the measurement area or the field of view edges, for example, the lower and upper edges of the measurement area or the lower and upper field of view edges for the exemplary arrangement of the CT sensor components described below. The field of view edges are thus captured by the edges of the detector that are parallel to the image center.

[0043] In most cases, the source and detector are arranged horizontally opposite each other, meaning the central beam runs horizontally, the axis of rotation of the turntable runs vertically, and the detector plane is almost perpendicular to the central beam. The image center therefore runs horizontally. With regard to the image center, we will henceforth refer to top and bottom, or above and below, and thus to the upper and lower edges of the field of view. However, the invention also relates to a different arrangement of the aforementioned components in space, as well as to the reversal of directions. Top and bottom (or related terms such as above and below, upper and lower edges of the field of view, lower edge of the workpiece (or bottom layer) and upper edge of the workpiece (or top layer)) should then be interpreted accordingly.In particular, the following describes how the helix measuring sections are configured such that the starting position is arranged higher than the end position, or that a second helix measuring section, compared to a first helix section, captures a section located higher on the workpiece. The invention also includes alternative configurations in which these directions are reversed or the position of the workpiece sections is interchanged.

[0044] The inventive solutions are preferably distinguished below according to the size of the workpieces to be measured, in particular the extent of the workpiece in the direction of the rotary table's axis of rotation (e.g., height) compared to the extent of the measuring volume in this direction. Small parts extend to an extent equal to or less than half the extent of the measuring volume, i.e., they are at most half as high as the measuring volume. Medium-sized parts have a height that is at most equal to the height of the measuring volume. Large parts are taller than the measuring volume.

[0045] The following section describes the position of the workpiece for a starting position and an end position of a trajectory. Reference is made here to the position of the lower or upper edge of the workpiece. According to the invention, this edge is to be arranged in the central plane, at the lower edge of the measuring volume, or at the upper edge of the measuring volume. The invention also fundamentally encompasses all alternatives in which the lower or upper edge of the workpiece only approximates these positions, in particular, in which it is offset from the central axis in the direction of the rotary axis. Deviations from the specified positions are on the order of the pixel size of the detector transformed into the position of the rotary axis with the given geometric imaging scale, in particular the transformed size of one to approximately ten pixels.This ensures that the corresponding layer is completely imaged on the detector in all rotational positions. Furthermore, larger deviations are also provided for the lower and upper workpiece edges to achieve the predetermined positions relative to the lower and upper edges of the measuring volume. Thus, the invention also provides that, particularly in the case of helical trajectories, the workpiece is arranged offset towards the central plane, i.e., for example, the upper workpiece edge is arranged below the upper edge of the measuring volume or the lower workpiece edge is arranged above the lower edge of the measuring volume.The deviation from the required position can also be several millimeters or centimeters, preferably also several percent of the workpiece's extension in the direction of the rotary axis of the rotary table (workpiece height), for example up to 5% or up to 10% or up to 25% of the workpiece height, and up to 50% of the workpiece height for workpieces of low height.

[0046] In particular, the invention is characterized in that the mixed trajectory comprises a helix measuring section, in particular a single helix measuring section, and a circle measuring section, in particular a single circle measuring section, wherein the following applies to the helix measuring section:

[0047] - in the starting position, the lower workpiece edge (bottom layer) is arranged in the central plane, and in the end position, the upper workpiece edge (top layer) is arranged in the central plane, and wherein for the Circle measuring section: the entire workpiece is arranged within the measuring volume, the method is preferably applied to workpieces whose extent in the direction of the axis of rotation of the rotary table is less than or equal to half the extent of the measuring volume.

[0048] Preferably, the mixed trajectory comprises two helical measuring sections and one circular measuring section, in particular a single circular measuring section, wherein for the first helical measuring section: in the starting position, the lower workpiece edge (bottom layer) is arranged in the central plane, and in the end position, the upper workpiece edge (top layer) is arranged above the central plane in an intermediate position; and wherein for the second helical measuring section: in the starting position, the upper workpiece edge (top layer) is arranged in the intermediate position above the central plane, and in the end position, the upper workpiece edge (top layer) is arranged in the central plane; and wherein for the circular measuring section: the entire workpiece is arranged within the measuring volume, with the upper workpiece edge (top layer) arranged in the intermediate position above the central plane.wherein the circle measuring section is traversed between the two helix measuring sections, and wherein the method is preferably applied to workpieces whose extent in the direction of the rotary axis of the rotary table is less than or equal to half the extent of the measuring volume.

[0049] The previously described helix trajectory is divided here into two sub-trajectories, between which the circle trajectory is traversed. This advantageously saves positioning time when moving between the end position of one helix trajectory and the starting position of the circle trajectory.

[0050] It should also be emphasized that the mixed trajectory comprises two helical measuring sections and one circular measuring section, whereby for the first helical measuring section: in the starting position, the lower workpiece edge (bottom layer) is arranged in the central plane, and in the final position, the lower workpiece edge (bottom layer) is arranged at the lower edge of the measuring volume, and whereby for the second helical measuring section:

[0051] - In the starting position, the lower workpiece edge (bottom layer) is arranged at the lower edge of the measuring volume, and in the final position, the upper workpiece edge (top layer) is arranged in the central plane, and wherein for the Circle measuring section: the entire workpiece is arranged within the measuring volume, with the lower workpiece edge (bottom layer) being arranged at the lower edge of the measuring volume, wherein the Circle measuring section is traversed between the two Helix measuring sections, and wherein the method is preferably used for workpieces whose extent in the direction of the axis of rotation of the rotary table is less than or equal to the extent of the measuring volume.

[0052] The method described here with two separate helix trajectories has the advantage of saving positioning time, because the circle trajectory can be executed in the end position of the first helix trajectory without any further procedure.

[0053] As an alternative to the sequence first helix measuring section, circle measuring section, second helix measuring section, the invention also provides that the two helix measuring sections are carried out directly one after the other, preferably as one helix measuring section, and that the circle measuring section is carried out afterwards or before.

[0054] The invention is also characterized in that the mixed trajectory comprises three helix measuring sections and two circle measuring sections, wherein for the first helix measuring section the following applies: in the starting position the lower workpiece edge (lowest layer) is arranged in the central plane and

[0055] - In the end position, the lower workpiece edge (bottom layer) is arranged at the lower edge of the measuring volume, and where for the second helical measuring section: - in the starting position, the lower workpiece edge (bottom layer) is arranged at the lower edge of the measuring volume, and in the end position, the upper workpiece edge (top layer) is arranged at the upper edge of the measuring volume, and where for the third helical measuring section: in the starting position, the upper workpiece edge (top layer) is arranged at the upper edge of the measuring volume and

[0056] - In the final position, the upper workpiece edge (top layer) is arranged in the central plane, and wherein for the first Circle measuring section: the lower workpiece edge (bottom layer) is arranged at the lower edge of the measuring volume and the upper workpiece edge is arranged at least partially outside the measuring volume, and wherein for the second Circle measuring section: the upper workpiece edge (top layer) is arranged at the upper edge of the measuring volume and the lower workpiece edge is arranged at least partially outside the measuring volume, wherein the first Circle measuring section is traversed between the first and second Helix measuring sections and the second Circle measuring section is traversed between the second and third Helix measuring sections, and wherein the method is preferably applied to workpieces whose extent in the direction of the rotary axis of the rotary table is greater than the extent of the measuring volume.

[0057] The method described here with three separate helix trajectories offers the advantage of saving positioning time, because the two circle trajectories can be executed in the end positions of the first and second helix trajectories without any further procedure.

[0058] As an alternative to the sequence of first helix measuring section, first circle measuring section, second helix measuring section, second circle measuring section, third helix measuring section, the invention also provides that the first and second, or the second and third, or all three helix measuring sections are executed directly one after the other, preferably as a single helix measuring section each, or as only a single helix measuring section, and that the circle measuring sections are executed before or after these. It is also provided that two helix measuring sections are executed before or after one of the circle measuring sections, preferably as a single helix measuring section.

[0059] The invention provides, notably, that for each helix measuring section and each circle measuring section, a rotation is selected separately from the following possibilities: rotation by 180°, or 180° plus fan angle, or 360°, or 360° plus fan angle. The invention also provides for rotations of less than 180°. At least two different rotation positions are set for each partial trajectory.

[0060] In particular, the invention is characterized by the fact that the rotation is continuous, meaning that the rotational movement is not interrupted for the acquisition of radiographic images.

[0061] Preferably, the CT sensor is operated according to at least one of the methods of the invention described above, which are described, inter alia, in claims 8 to 15.

[0062] The invention also provides a device (computed tomography scanner / computed tomography sensor) for carrying out the method according to the invention. To achieve this, the invention proposes a computed tomography sensor (CT sensor) for measuring workpieces, wherein the CT sensor comprises at least: at least one radiation source (source), preferably an X-ray tube, for generating the measurement radiation; at least one radiation detector (detector) having several detector elements (detector pixels) sensitive to the measurement radiation, wherein the detector pixels preferably form a 2D pixel matrix; and a rotary table for relative rotation between the workpiece and the unit consisting of the source and detector, preferably a rotary table for rotating the workpiece. The CT sensor is configured to acquire transmission images with the detector in several rotational positions between the workpiece and the unit consisting of the source and detector, from which volume data can be calculated by means of reconstruction.wherein surface data can preferably be calculated from the volume data, wherein the CT sensor is characterized in that a mixed trajectory of circle measuring sections and helical measuring sections can be set, wherein the CT sensor has at least one measuring axis with which the workpiece and / or the unit of source and detector can be adjusted in the direction of the rotational axis of the rotary table, and which is configured to set a helical trajectory in which, in addition to the relative rotation of the workpiece, The position is adjustable along the direction of the rotary axis of the turntable between successively recorded radiographic images.

[0063] In particular, the invention is characterized in that the CT sensor is arranged in a coordinate measuring machine, preferably together with other sensors such as tactile, tactile-optical and / or optical sensors, wherein the sensors are preferably designed to provide measurement data in a uniform coordinate system.

[0064] Preferably, the device is provided to have an evaluation unit with which internal or near-surface features such as cavities, pores, cracks, inclusions, fibers can be determined from the volume data and / or with which geometric properties, in particular dimensions of the workpiece, can be determined from the surface data.

[0065] It should also be emphasized that the CT sensor is designed according to the ideas of the previous invention, which is described, inter alia, in claims 19 to 26.

[0066] Further details, advantages and features of the invention will become apparent not only from the claims and the features to be derived therefrom - individually and / or in combination - but also from the following description of the figures.

[0067] They show:

[0068] Fig. 1 shows an embodiment of the CT sensor according to the invention.

[0069] Fig. 2 shows a first embodiment of the method for operating a CT sensor,

[0070] Fig. 3 shows a second embodiment of the method for operating a CT sensor and Fig. 4 shows a third embodiment of the method for operating a CT sensor.

[0071] Figure 1 illustrates the invention by way of example. An exemplary CT sensor

[0072] The apparatus 1 comprises an X-ray source 3 with the focal spot 3a emitting the measuring radiation 4, the detector 5 with the detector pixels 6, and the rotary table 7, from which the workpiece 2 to be measured extends directly or indirectly via a workpiece holder 2a. For adjusting the FDD, the detector extends from a measuring axis 8, which allows adjustment in the central direction 4a of the measuring radiation 4, shown in the figure as a horizontal direction. Alternatively or additionally, a measuring axis corresponding to the measuring axis 8 can also be provided for the corresponding movement of the source 3 to adjust the FDD.

[0073] To achieve the additional adjustment of the workpiece 2 in the direction of the rotary axis 7a of the rotary table 7, which is necessary for a helical trajectory, the rotary table 7 originates from a vertical measuring axis 9. Alternatively, source 3 and detector 5 can also originate from corresponding measuring axes.

[0074] Further movement or measuring axes 10 and 11 may be provided to move the rotary table 7 with the workpiece 2 in the two other spatial directions relative to the unit consisting of source 3 and detector 5, in particular to adjust the distance to these and thus the effective geometric magnification (or geometric imaging scale) when imaging the workpiece 2 onto the detector 5. These axes may alternatively also be provided for the corresponding movement of source 3 and detector 5.

[0075] For setting an AOI 12, the area of ​​all pixels 6 can be restricted to an area 12, within which the pixels 6 are read and processed during image capture.

[0076] Figure 2 illustrates the inventive method for operating the CT sensor 1 for a first exemplary workpiece 2. For simplification, the figures

[0077] Figures 2 to 4 do not show or label all components of the CT sensor 1. However, the components shown in Figure 1 also apply. Figures 2 to 4 show in detail the position of the workpiece 2, in particular in an intermediate position P2x, or the position of the lower workpiece edge (or bottom layer) 2u or the upper workpiece edge (or top layer) 2o in the respective starting position PI and end position P2 of the respective partial trajectories or partial measurement sections (helix measurement sections H1, H2, H3 or circle measurement sections C1, C2) with respect to the central plane 13 or the measurement volume 14, in particular the upper edge of the measurement volume 14o or the lower edge of the measurement volume 14u. These reference symbols are shown once in the upper left of Figure 2 and also apply to the further illustrations in Figure 1. v (ocen right, bottom left, bottom right) as well as the representations of the further figures 3 and 4.

[0078] Figure 2 shows a workpiece 2 which, in the direction of the axis of rotation 7a of the rotary table 7, has an extent (height) that is less than half the extent of the measuring volume 14 (distance between the upper edge of the measuring volume 14o and the lower edge of the measuring volume 14u). According to a first method according to the invention, two helical measuring sections Hl and H2 and one circular measuring section CI are implemented. In the first helical measuring section Hl (shown in the upper half of Figure 2), the workpiece 2 is moved from the starting position Pl to the end position P2, rotating about and displacing it in the direction of the axis of rotation 7a. In the starting position PI, the workpiece 2 is arranged such that the lower workpiece edge 2u is located in the central plane 13. In the end position P2, the workpiece 2 is arranged in the intermediate position P2x, with the upper workpiece edge 2o located above the central plane 13.According to the invention, the intermediate position P2x encompasses the entire area in which the upper workpiece edge 20 is located above the central plane 13 and the lower workpiece edge 2u is located below the central plane 13. Preferably, the intermediate position P2x is selected such that the lower workpiece edge 2u and the upper workpiece edge 2o are equidistant from the central plane 13. Advantageously, the cone angle occurring when the workpiece 2 is mapped onto axis 5 is minimal. After the first helical measuring section H1, the circular measuring section CI is executed. In this section, the workpiece 2 in the intermediate position P2x is simply rotated about the axis of rotation 7a. Subsequently, the second helical measuring section H2 is executed (shown in the lower half of Figure 2), in which the workpiece 2 is moved from the starting position Pl to the end position P2, rotating about and shifting in the direction of the axis of rotation 7a.In the starting position PI, the workpiece is preferably still in the intermediate position P2x. In the final position P2, the workpiece 2 is arranged such that the upper workpiece edge 20 is located in the central plane 13.

[0079] As an alternative to the sequence helix measuring section Hl, circle measuring section CI, helix measuring section H2, the invention also provides that the two helix measuring sections Hl and H2 are carried out directly one after the other, preferably as one helix measuring section Hl -2, and that the circle measuring section CI is carried out afterwards or before.

[0080] Figure 3 illustrates the inventive method for operating the CT sensor 1 for a second exemplary workpiece 2, wherein the workpiece 2 has an extent (height) in the direction of the axis of rotation 7a of the rotary table 7 that is equal to or less than the extent of the measuring volume 14 (distance between the upper edge of the measuring volume 14o and the lower edge of the measuring volume 14u), but greater than half the extent of the measuring volume 14. According to a further method of the invention, two helical measuring sections H1 and H2 and one circular measuring section CI are implemented. In the first helical measuring section H1 (shown in the upper half of Figure 3), the workpiece 2 is moved from the starting position Pl to the end position P2, rotating about and displacing in the direction of the axis of rotation 7a. In the starting position PI, the workpiece 2 is arranged such that the lower workpiece edge 2u is located in the central plane 13.In the final position P2, the workpiece 2 is positioned such that its lower edge 2u is located at the lower edge 14u of the measuring volume 14. After the first helical measuring section Hl, the circle measuring section CI is executed. In this section, the workpiece 2 is simply rotated about the axis of rotation 7a in the final position P2 of the first helical measuring section Hl. Subsequently, the second helical measuring section H2 is executed (shown in the lower half of Figure 3), in which the workpiece 2 is moved from the starting position Pl to the final position P2, rotating about and shifting along the axis of rotation 7a. In the starting position PI, the workpiece is still in the final position P2 of the first helical measuring section Hl, meaning its lower edge 2u is located at the lower edge 14u of the measuring volume 14. In the final position P2, the workpiece 2 is positioned such that its upper edge 2o is located in the central plane 13.

[0081] Alternatively to the sequence: Helix measuring section Hl, Circle measuring section CI, Helix-

[0082] The invention also provides that the two helix measuring sections H1 and H2 are executed directly one after the other, preferably as one helix measuring section H1-2, and that the circle measuring section CI is executed either before or after.

[0083] Figure 4 illustrates the inventive method for operating the CT sensor 1 for a third exemplary workpiece 2, wherein the workpiece 2 has an extent (height) in the direction of the axis of rotation 7a of the rotary table 7 that is greater than the extent of the measuring volume 14 (distance between the upper edge of the measuring volume 14o and the lower edge of the measuring volume 14u). According to a further method of the invention, three helical measuring sections H1, H2 and H3 and two circular measuring sections CI and C2 are implemented. In the first helical measuring section H1 (shown in the upper third of Figure 4), the workpiece 2 is moved from the starting position Pl to the end position P2, whereby a rotation about and a displacement in the direction of the axis of rotation 7a takes place. In the starting position PI, the workpiece 2 is arranged such that the lower workpiece edge 2u is arranged in the central plane 13.In the final position P2, the workpiece 2 is positioned such that its lower edge 2u is located at the lower edge 14u of the measuring volume 14. After the first helical measuring section Hl, the circle measuring section CI is executed. In this section, the workpiece 2 is simply rotated about the axis of rotation 7a in the final position P2 of the first helical measuring section Hl. In this position (final position P2 of the first helical measuring section Hl), the upper edge 2o of the workpiece 2 is at least partially outside the measuring volume 14, specifically above the upper edge 10o of the measuring volume 14. Subsequently, the second helical measuring section H2 is executed (shown in the center of Figure 4), in which the workpiece 2 is moved from the starting position Pl to the final position P2, rotating about and shifting in the direction of the axis of rotation 7a.In the starting position PI, the workpiece is still in the end position P2 of the first helical measuring section H1, with the lower workpiece edge 2u located at the lower edge 14u of the measuring volume 14. In the end position P2, the workpiece 2 is positioned such that the upper workpiece edge 2o is located at the upper edge (14o) of the measuring volume 14. After the second helical measuring section H2, the second circular measuring section C2 is executed. In this section, the workpiece 2 is simply rotated around the axis of rotation 7a in the end position P2 of the second helical measuring section H2. In this position (end position P2 of the second helical measuring section H2), the lower edge 2u of the workpiece 2 is located at least partially outside the measuring volume 14, specifically below the lower edge 14u of the measuring volume 14.The third helical measuring section H3 is then executed (shown in the lower third of Figure 4), in which the workpiece 2 is moved from the starting position Pl to the end position P2, rotating about and shifting in the direction of the axis of rotation 7a. In the starting position PI, the workpiece is still in the end position P2 of the second helical measuring section H2, with the upper workpiece edge 20 thus located at the upper edge 140 of the measuring volume 14. In the end position P2, the workpiece 2 is positioned such that the upper workpiece edge 20 is located in the central plane 13.

[0084] As an alternative to the sequence helix measuring section H1, circle measuring section CI, helix measuring section H2, circle measuring section C2, helix measuring section H3, the invention also provides that two or all three of the helix measuring sections H1, H2, H3 are combined to form one helix measuring section H1-2, H2-3, H1-2-3, and that the circle measuring sections Cl, C2 are performed before or after the combined helix measuring sections H1-2, H2-3, H1-2-3. It is also provided that two helix measuring sections H1, H2 or H2, H3 are performed before or after one of the circle measuring sections Cl, C2, preferably as one helix measuring section H1-2, H2-3.

[0085] As an alternative to the arrangement of the workpiece 2 at the start positions PI and end positions P2 described in Figures 2 to 4, it is also provided that the workpiece 2 is arranged offset towards the central plane 13, in particular at least slightly offset, so that the specified positions are shifted slightly inwards (towards the central plane 13). This is provided according to the invention when the maximum cone angle is to be reduced in order to achieve more accurate measurement results. A corresponding deviation from the specified positions PI, P2 also occurs, for example, if the workpiece 2 is arranged closer to the detector 5 in the direction of the axis of rotation 7a at the same position (height), but together with the rotary table 7, thus setting a smaller geometric imaging scale, which also reduces the cone angle.

Claims

Patent claims Method for operating a coordinate measuring machine and device for carrying out 1. Method for operating a computed tomography sensor (CT sensor) (1) for measuring a workpiece (2), wherein the CT sensor (1) comprises at least: - at least one radiation source (source) (3), preferably an X-ray tube, for generating the measurement radiation (4), - at least one radiation detector (detector) (5) comprising several detector elements (detector pixels) (6) sensitive to the measurement radiation (4), wherein detector pixels (6) preferably form a 2D pixel matrix, and a rotary table (7) for relative rotation between the workpiece (2) and the unit consisting of the source (3) and detector (5), preferably a rotary table (7) for rotating the workpiece (2), wherein in several rotational positions between the workpiece (2) and the unit consisting of the source (3) and detector (5), transmission images are recorded with the detector (5), from which volume data are calculated by means of reconstruction, wherein surface data are preferably calculated from the volume data, characterized in that transmission images are recorded and used to determine the volume data, which are recorded when traversing a mixed trajectory consisting of at least one circle measurement section (Cl, C2) and at least one helix measurement section (Hl, H2, H3),preferably recorded during the scanning of at least two helical measurement sections (H1, H2, H3) and at least one circle measurement section (Cl, C2), particularly preferably recorded during the scanning of at least three helical measurement sections (H1, H2, H3) and at least two circle measurement sections (Cl, C2).

2. The method according to claim 1, characterized in that, that the mixed trajectory comprises a helix measuring section (Hl -2) and a circle measuring section (CI), wherein for the helix measuring section (Hl -2) the following applies: in the start position (PI) the lower workpiece edge (bottom layer) (2u) is arranged in the central plane (13) and in the end position (P2) the upper workpiece edge (top layer) (2o) is arranged in the central plane (13), and wherein for the circle measuring section (CI) the following applies: - the complete workpiece (2) is arranged within the measuring volume (14), the method being preferably applied to workpieces (2) whose extent in the direction of the axis of rotation (7a) of the rotary table (7) is less than or equal to half the extent of the measuring volume (14).

3. Method according to claim 1 or 2, characterized in that the mixed trajectory comprises two helical measuring sections (Hl, H2) and one circle measuring section (CI), wherein for the first helical measuring section (Hl) the following applies: in the starting position (PI) the lower workpiece edge (lowest layer) (2u) is arranged in the central plane (13) and - in the end position (P2) the upper workpiece edge (top layer) (2o) is arranged above the central plane (13) in an intermediate position (P2x), and where for the second helix measuring section (H2) the following applies: in the start position (PI) the upper workpiece edge (top layer) (2o) is arranged in the intermediate position (P2x) above the central plane (13) and - in the end position (P2) the upper workpiece edge (top layer) (2o) is arranged in the central plane (13), and wherein for the Circle measuring section (CI) the following applies: the complete workpiece (2) is arranged within the measuring volume (14), wherein the upper workpiece edge (top layer) (2o) is arranged above the central plane (13) in the intermediate position (P2x), wherein the Circle measuring section (CI) is traversed between the two Helix measuring sections (Hl, H2), and wherein the method is preferably applied to workpieces (2) whose extent in the direction of the axis of rotation (7a) of the rotary table (7) is less than or equal to half the extent of the measuring volume (14).

4. Method according to at least claim 1 or 2, characterized in that the mixed trajectory includes two helical measuring sections (H1, H2) and a circle- measuring section (CI) includes, where for the first helix measuring section (Hl) the following applies: in the starting position (PI) the lower workpiece edge (lowest layer) (2u) is arranged in the central plane (13) and - in the end position (P2) the lower workpiece edge (bottom layer) (2u) is arranged at the lower edge (14u) of the measuring volume (14), and wherein for the second helical measuring section (H2) the following applies: in the start position (PI) the lower workpiece edge (bottom layer) (2u) is arranged at the lower edge (14o) of the measuring volume (14) and in the end position (P2) the upper workpiece edge (top layer) (2o) is arranged in the central plane (13), and wherein for the circle measuring section (CI) the following applies: the entire workpiece (2) is arranged within the measuring volume (14), wherein the lower workpiece edge (bottom layer) (2u) is arranged at the lower edge (14u) of the measuring volume (14), wherein the circle measuring section (CI) is traversed between the two helical measuring sections (H1, H2), and wherein the method is preferably applied to workpieces (4) whose extent in The direction of the axis of rotation (7a) of the rotary table (7) is less than or equal to the extent of the measuring volume (14).

5. A method according to at least claim 1 or 2, characterized in that the mixed trajectory comprises three helical measuring sections (H1, H2, H3) and two circular measuring sections (Cl, C2), wherein for the first helical measuring section (H1) the following applies: in the start position (PI) the lower workpiece edge (lowest layer) (2u) is arranged in the central plane (13) and in the end position (P2) the lower workpiece edge (lowest layer) (2u) is arranged at the lower edge (14u) of the measuring volume (14), and wherein for the second helical measuring section (H2) the following applies: in the start position (P1) the lower workpiece edge (lowest layer) (2u) is arranged at the lower edge (14u) of the measuring volume (14) and - in the end position (P2) the upper workpiece edge (top layer) (2o) is arranged at the upper edge (14o) of the measuring volume (14), and where for the third helical measuring section (H3) the following applies: in the start position (PI) the upper workpiece edge (top layer) (2o) is arranged at the upper edge (14o) of the measuring volume (14) and - in the end position (P2) the upper workpiece edge (top layer) (2o) is arranged in the central plane (13), and the following applies to the first Circle measuring section (CI): - the lower workpiece edge (bottom layer) (2u) is located at the lower edge (14u) of the measuring volume (14) and the upper workpiece edge (2o) is located at least partially outside the measuring volume (14), and where the following applies to the second Circle measuring section (C2): - the upper workpiece edge (top layer) (2o) is arranged at the upper edge (14o) of the measuring volume (14) and the lower workpiece edge (2u) is arranged at least partially outside the measuring volume (14), wherein the first circle measuring section (CI) is traversed between the first (Hl) and second helix measuring section (H2) and the second circle measuring section (C2) is traversed between the second (H2) and third helix measuring section (H3), and wherein the method is preferably applied to workpieces (2) whose extent in the direction of the axis of rotation (7a) of the rotary table (7) is greater than the extent of the measuring volume (14).

6. Method according to at least one of the preceding claims 1 to 5, characterized in that for each helix measuring section (H1, H2, H3) and each circle measuring section (Cl, C2) a rotation is selected separately from the following possibilities: rotation by 180° or 180° plus fan angle or 360° or 360° plus fan angle.

7. Method according to at least one of the preceding claims 1 to 6, characterized in that the rotation is continuous, i.e. the rotational movement is not interrupted for the acquisition of radiographic images.

8. Method for operating a computed tomography sensor (CT sensor) for measuring workpieces, according to at least one of the preceding claims 1 to 7, wherein the CT sensor comprises at least: at least one radiation source (source), preferably an X-ray tube, for generating the measurement radiation, - at least one radiation detector (detector) comprising several detector elements (detector pixels) sensitive to the measurement radiation, wherein detector pixels preferably form a 2D pixel matrix, and a rotary table for relative rotation between the workpiece and the unit consisting of the source and detector, preferably a rotary table for rotating the workpiece, and wherein transmission images are recorded with the detector in several rotational positions between the workpiece and the unit consisting of the source and detector, from which volume data are calculated by means of reconstruction, wherein surface data are preferably calculated from the volume data, characterized in that one or more of the following measures are carried out during the operation of the CT sensor: - The detector is operated in an AOI (Area of ​​Interest) mode, wherein only a limited number of pixels within an AOI (Area of ​​Interest) are read out from the available detector pixels, preferably the limited area (AOI) is a rectangular sub-area of ​​the 2D pixel matrix, and wherein a higher frame rate is set compared to reading out all available detector pixels, the FDD (Focus Detector Distance) between the source, in particular the radiation-emitting stop spot of the source, and the detector is set small, preferably less than 500 mm, particularly preferably less than 300 mm, in order to achieve a high efficiency in detecting the measurement radiation. - For at least part of the CT measurement, a helical trajectory is followed, in which, in addition to the relative rotation of the workpiece, an offset along the direction of the rotary axis of the turntable is set between successively recorded radiographic images by adjusting the workpiece and / or the unit consisting of source and detector in the direction of the rotary axis of the turntable.

9. Method according to at least one of the preceding claims 1 to 8, characterized in that a small FDD, preferably less than 500 mm, particularly preferably less than 300 mm, is set and at least part of the CT measurement is performed in the form of a helical trajectory.

10. Method according to at least one of the preceding claims 1 to 9, characterized in that the detector is operated in binned mode, preferably in 2x2 binning or 4x4 binning or 8x8 binning, wherein preferably a higher frame rate is set than in unbinned operation.

11. Method according to at least one of the preceding claims 1 to 10, characterized in that the AOI of the detector is set so small that the available bandwidth of the detector for transmitting the radiographic images enables a particularly high frame rate, preferably the AOI is set so small that for very small integration times for acquiring the radiographic images the waiting time between two successive image acquisitions is as short as possible.

12. Method according to at least one of the preceding claims 1 to 11, characterized in that an X-ray tube is used as the source, wherein the generator required for supplying the X-ray source with high voltage is arranged within the radiation protection housing, preferably flanged to the vacuum tube of the X-ray source, and particularly preferably a vacuum pump is flanged to the vacuum tube.

13. Method according to at least one of the preceding claims 1 to 12, characterized in that an X-ray tube having a transmission target is used as the source, and high beam powers are set with a small focal spot size, preferably set to approximately 80 watts of power and a focal spot size of less than 25 gm.

14. Method according to at least one of the preceding claims 1 to 13, characterized in that the CT sensor is operated in a coordinate measuring machine, preferably together with further sensors such as tactile, tactile-optical and / or optical sensors, wherein the sensors preferably provide measurement data in a uniform coordinate system.

15. Method according to at least one of the preceding claims 1 to 14, characterized in that internal or near-surface features such as cavities, pores, cracks, inclusions, fibers are determined from the volume data and / or that geometric properties, in particular dimensions of the workpiece, are determined from the surface data.

16. Computed tomography sensor (CT sensor) (1) for measuring workpieces (2), wherein the CT sensor (1) comprises at least: - at least one radiation source (source) (3), preferably an X-ray tube, for generating the measurement radiation (4), at least one radiation detector (detector) (5) comprising several detector elements (detector pixels) (6) sensitive to the measurement radiation (4), wherein detector pixels (6) preferably form a 2D pixel matrix, and a rotary table (7) for relative rotation (circle trajectory) between the workpiece (2) and the unit consisting of the source (3) and detector (5), preferably a rotary table (7) for rotating the workpiece (2), and wherein the CT sensor (1) is configured to record transmission images with the detector (5) in several rotational positions between the workpiece (2) and the unit consisting of the source (3) and detector (5), from which volume data can be calculated by means of reconstruction, wherein surface data can preferably be calculated from the volume data, preferably a device for carrying out the method according to at least one of the preceding claims 1 to 15, characterized in that a mixed trajectory of circle measuring sections (Cl, C2) and helix measuring sections (Hl, H2, H3) is adjustable, wherein the CT sensor (1) has at least one measuring axis (9) with which the workpiece (2) and / or the unit of source (3) and detector (5) is adjustable in the direction of the axis of rotation (7a) of the rotary table (7), and which is configured to adjust a helix trajectory (Hl, H2, H3) in which, in addition to the relative rotation of the workpiece (2), an offset along the direction of the axis of rotation (7a) of the rotary table (7) is adjustable between successively acquired radiographic images.

17. Device according to claim 16, characterized in that the CT sensor (1) is arranged in a coordinate measuring machine, preferably together with further sensors such as tactile, tactile-optical and / or optical sensors, wherein the sensors are preferably configured to provide measurement data in a uniform coordinate system.

18. Device according to claim 16 or 17, characterized in that the device has an evaluation unit with which internal or near-surface features such as voids, pores, cracks, inclusions, fibers can be determined from the volume data and / or with which geometric properties, in particular dimensions on the workpiece (2), can be determined from the surface data.

19. Computed tomography sensor (CT sensor) (1 ) for measuring workpieces (2), according to at least one of the preceding claims 16 to 18, wherein the CT sensor (1) comprises at least: - at least one radiation source (source) (3), preferably an X-ray tube, for generating the measurement radiation (4), at least one radiation detector (detector) (5) which has several detector elements (detector pixels) (6) sensitive to the measurement radiation (4), wherein detector pixels (6) preferably form a 2D pixel matrix, and a rotary table (7) for relative rotation between the workpiece (2) and the unit consisting of the source (3) and detector (5), preferably a rotary table (7) for rotating the workpiece (2), and wherein the CT sensor (1) is configured to acquire transmission images with the detector (5) in several rotational positions between the workpiece (2) and the unit consisting of the source (3) and detector (5), from which volume data can be calculated by means of reconstruction, wherein surface data can preferably be calculated from the volume data, characterized in that the CT sensor (1) has one or more of the following configurations: the detector (5) is operable in at least one AOI mode (Area of ​​Interest mode), wherein only a limited number of pixels (12) within an AOI (Area of ​​Interest) can be read out from the available detector pixels (6), preferably a rectangular sub-area of ​​the 2D pixel matrix can be set as the limited area (AOI) (12).and wherein a higher frame rate can be set compared to reading out all available detector pixels (6), - The distance FDD (Focus Detector Distance) between the source (3), in particular the radiation-emitting focal spot (3a) of the source (3), and the detector (5) is designed to be small or adjustable to a small extent, preferably less than 500 mm, particularly preferably less than 300 mm, in order to achieve a high efficiency in detecting the measurement radiation (4); preferably the CT sensor (1) has a movement axis (8), particularly preferably a measurement axis, for adjusting the FDD. - for at least part of the CT measurement, a helical trajectory can be set, in which, in addition to the relative rotation of the workpiece (2), an offset along the direction of the axis of rotation (7a) of the rotary table (7) can be set between successively recorded radiographic images, by the CT sensor (1) having at least one measuring axis (9) with which the workpiece (2) and / or the unit consisting of source (3) and detector (5) can be adjusted in the direction of the axis of rotation (7a) of the rotary table (7).

20. Device according to at least one of the preceding claims 16 to 19, characterized by, that a small FDD, preferably less than 500 mm, particularly preferably less than 300 mm, is adjustable and at least part of the CT measurement can be performed in the form of a helical trajectory.

21. Device according to at least one of the preceding claims 16 to 20, characterized in that the detector (5) can be operated in binned mode, preferably in 2x2 binning or 4x4 binning or 8x8 binning, wherein preferably a higher frame rate can be set than in unbinned operation.

22. Device according to at least one of the preceding claims 16 to 21, characterized in that the AOI (12) of the detector (5) is adjustable to such a small extent that the available bandwidth of the detector (5) for transmitting the radiographic images enables a particularly high frame rate, preferably the AOI (12) is adjustable to such a small extent that for very small integration times for acquiring the radiographic images the waiting time between two successive image acquisitions is as short as possible.

23. Device according to at least one of the preceding claims 16 to 22, characterized in that an X-ray tube is arranged as the source (3), wherein the generator required for supplying the X-ray source (3) with high voltage is arranged within the radiation protection housing, preferably flanged to the vacuum tube of the X-ray source (3), and particularly preferably a vacuum pump is flanged to the vacuum tube.

24. Device according to at least one of the preceding claims 16 to 23, characterized in that an X-ray tube is arranged as the source (3) which has a transmission target and high beam powers with small focal spot size are adjustable, preferably approximately 80 watts power and focal spot size less than 25 pm.

25. Device according to at least one of the preceding claims 16 to 24, characterized in that the CT sensor (1) is arranged in a coordinate measuring machine, preferably together with further sensors such as tactile, tactile-optical and / or optical sensors, wherein the sensors are preferably configured to transmit measurement data in a uniform To provide a coordinate system.

26. Device according to at least one of the preceding claims 16 to 25, characterized in that the device has an evaluation unit with which internal or near-surface features such as voids, pores, cracks, inclusions, fibers can be determined from the volume data and / or with which geometric properties, in particular dimensions of the workpiece, can be determined from the surface data.

Images