Method and device for registering reference coordinate systems of a first optical sensor and at least one further optical sensor

Abstract

The invention relates to a method and a device for registering reference coordinate systems of a first optical sensor (2) and at least one further optical sensor (3) of a coordinate measuring apparatus, wherein a radial measurement accuracy of the first optical sensor (2) is higher than a radial measurement accuracy of the further optical sensor (3) and the axial measurement accuracy of the further optical sensor (3) is higher than an axial measurement accuracy of the first optical sensor (2), the method comprising the steps of: - detecting a plurality of measurement points of a first measurement point set; - detecting a plurality of measurement points of a further measurement point set using the further optical sensor (3); - identifying at least one corresponding reference element per measurement point set; - determining a transformation rule for transforming coordinate values between the reference coordinate systems on the basis of the coordinate values of the corresponding reference element.

Description

[0001] Applicant: Carl Zeiss Industrial Metrology GmbH

[0002] Our reference: P18.931WO 18.12.2025

[0003] Method and apparatus for registering reference coordinate systems of a first optical sensor and at least one further optical sensor

[0004] The invention relates to a method and a device for registering reference coordinate systems of a first optical sensor and at least one further optical sensor of a coordinate measuring machine.

[0005] Coordinate measuring machines are used, among other things, in the quality assurance of components, but also in other areas, to measure a test object, such as a component. With the help of at least one sensor, the coordinates of points on the surface of the test object can be determined, and based on these coordinates, the shape, size, position, and other properties of the test object can be determined. Such a measurement can also be part of, or a prerequisite for, an inspection of the test object, for example, to check compliance with desired dimensional tolerances.

[0006] One of the main components of a coordinate measuring machine is typically a measuring head, which may include at least one sensor. A coordinate measuring machine also includes at least one measuring arm or axes, whereby the measuring head can be moved along the axes, particularly during a measurement. Such an axis can be a linear axis or a rotational axis. Furthermore, the coordinate measuring machine includes a control unit and, optionally, an evaluation unit.

[0007] Coordinate measuring machines with tactile sensors are also known; these generate measuring points and their coordinates by touching the surface of the test object. Coordinate measuring machines with at least one optical sensor are also known, enabling non-contact acquisition of measuring points and their coordinates. So-called multi-sensor coordinate measuring machines, comprising at least two sensors, particularly at least two optical sensors, are also known. The output signals from different sensors of such a multi-sensor coordinate measuring machine can be used to perform various measurement functions. An optical sensor, for example, can be an image acquisition device that generates a two-dimensional image of the test object or a part thereof.Another optical sensor can be, in particular, a confocal white light sensor, which exhibits high axial measurement accuracy, i.e., high measurement accuracy along an optical axis of the sensor (z-axis). The image acquisition device can have high radial measurement accuracy, i.e., Applicant: Carl Zeiss Industrial Metrology GmbH.

[0008] Our reference: P18.931WO 18.12.2025 exhibits high measuring accuracy in a direction oriented perpendicular to the optical axis.

[0009] An optical sensor can be assigned a reference coordinate system, which can also be called a sensor-specific reference coordinate system. In the case of an image acquisition device, this reference coordinate system can be, in particular, a two-dimensional coordinate system, e.g., the image coordinate system. In the case of a confocal white light sensor, the reference coordinate system can be a one-dimensional coordinate system. Depending on the output signals of the respective sensor, coordinates can be determined for a measurement point in the corresponding sensor-specific reference coordinate system.

[0010] Coordinate measuring machines, however, generally allow the determination of coordinates in a reference coordinate system, which may differ from a sensor-specific reference coordinate system. If the output signal of an optical sensor does not allow the determination of the measurement point-specific coordinates in all desired dimensions, particularly in three dimensions, with respect to a reference coordinate system, the missing information can be determined depending on the spatial orientation of the reference coordinate system within the reference coordinate system. The spatial orientation of the reference coordinate system, in turn, can be determined depending on at least one axis position of the coordinate measuring machine. This will be explained in more detail below.

[0011] To further process the data, especially the coordinates determined by different sensors, it may be desirable to relate them to a common coordinate system, i.e., a reference coordinate system. This reference coordinate system can be the machine coordinate system, which will be explained in more detail below. To determine data, particularly coordinates, within the reference coordinate system, these can be determined in the sensor-specific reference coordinate system and then transformed into the reference coordinate system. This transformation can depend on the position of the sensor-specific coordinate system within the reference coordinate system. In a subsequent measurement operation, the coordinates for measurement points acquired with the different sensors can then be transformed into a common reference coordinate system based on this transformation.It is desired to determine this transformation for each sensor in such a way that it applies to the same applicant: Carl Zeiss Industrial Metrology GmbH.

[0012] Our reference: P18.931WO 18.12.2025

[0013] The same coordinate values ​​are determined at the measuring point.

[0014] The sensors, with their sensor-specific reference coordinate systems, are movably arranged within the reference coordinate system, in particular movably along and / or around axes of the reference coordinate system. Thus, their position can be determined as a function of a (rotational) position along or around these axes. For this purpose, the output signals from position and / or rotation angle sensors of the coordinate measuring machine are evaluated.

[0015] This may be particularly desirable when coordinate measurement points, based on output signals generated by different sensors, are to be displayed together, e.g., on a display device, or recorded in a measurement log. For this to be possible, it is necessary that the respective sensors generate accurate output signals, which can be achieved by calibrating / measuring each sensor.

[0016] On the other hand, it is necessary to determine the position of the reference coordinate systems relative to each other, or relative to a common reference coordinate system, very precisely so that the output signals of the various sensors can be spatially correctly related to one another. Likewise, knowledge of the relative position, which can be determined particularly in the reference coordinate system, can enable simplified control of the coordinate measuring machine, e.g., for positioning the sensors.

[0017] Typically, the coordinate systems of different sensors are registered by measuring a calibration object with the sensors. Based on the generated output signals and / or measurement points, especially the coordinate values, corresponding reference elements, e.g., reference points, can then be determined. Depending on these corresponding reference points, a relationship between the reference coordinate systems of the sensors and their relative position can then be determined, for example, in the form of a coordinate transformation and / or a translation.

[0018] Thus, registration can be the determination of a transformation or calculation rule, particularly specific to the sensor, to determine coordinates in a reference coordinate system based on a sensor output signal and, if applicable, based on the sensor's spatial orientation, especially in such a way that identical coordinate values ​​are determined for the same measuring point. Applicant: Carl Zeiss Industrial Metrology GmbH

[0019] Our reference: P18.931WO 18.12.2025

[0020] Transformations can also involve transforming coordinates in the sensor-specific reference coordinate system into the reference coordinate system. This coordinate transformation can include a translation and / or a rotation and / or a scaling. Registration can also involve determining the relative position of sensor-specific coordinate systems.

[0021] A calibration of the sensors is therefore generally based on the measurement of at least one reference element, which is part of a calibration standard. Here, a reference element or a reference point of the calibration standard is measured with each sensor, and from the difference in the coordinate values ​​of sensor-specific measurement points, which depend on the output signal and the spatial orientation of the sensor, and thus in particular on the axis positions of the coordinate measuring machine, a reference between the reference coordinate systems is then determined in a known manner, especially within the reference coordinate system. For precise registration, it is desirable that the spatial orientation of the reference element can be determined with high accuracy based on the measurements taken with both sensors. This can pose a challenge, especially when calibrating a two-dimensional image sensor with a confocal white light sensor.Thus, based on measurements taken with a two-dimensional image sensor, 2D coordinates can be determined very precisely, for example, with respect to the x- and y-axes of the reference coordinate system. Based on measurements taken with a confocal white light sensor, a 1D coordinate with respect to the z-axis of the reference coordinate system can be determined with high accuracy. However, a calibration sphere commonly used in the calibration of coordinate measuring machines (CMMs) is generally unsuitable for performing the described calibration and results in an inaccurate registration.

[0022] If a multi-sensor coordinate measuring machine includes sensors with different measurement accuracies in relation to different spatial directions, or sensors that each only perform a measurement along different spatial directions or have a desired measurement accuracy, then it is problematic with the registration methods described to reliably determine corresponding coordinates of reference elements.

[0023] The technical problem therefore arises of creating a method and a device for registering the reference coordinate systems of a first optical sensor and at least one further optical sensor of a coordinate measuring machine, enabling accurate registration. Applicant: Carl Zeiss Industrial Metrology GmbH

[0024] Our reference: P18.931WO 18.12.2025

[0025] A method is proposed for registering reference coordinate systems of a first optical sensor and at least one further optical sensor of a coordinate measuring machine, which can in particular be a multi-sensor coordinate measuring machine.

[0026] The various optical sensors can be integrated into a common measuring head. However, this is not mandatory. It is also conceivable that the various sensors are integrated into separate parts of the coordinate measuring machine or form separate parts. The various optical sensors are arranged in a fixed position relative to each other, whereby the relative position can be predetermined by the design. While it is also conceivable that the various sensors are arranged to be movable relative to each other, in this case the proposed method refers to registration in a particularly constant relative position. The two optical sensors can be arranged such that their optical axes are oriented parallel to each other.

[0027] The registration process was already explained in the introduction. If the registration serves to determine a relative position between the sensors, in particular their sensor-specific reference coordinate systems, then the registration can be used to determine, in particular, the relative position of sensor reference points, e.g., a so-called TCP (tool center point), and especially the distance between these points. This distance can be determined, in particular, perpendicular to the optical axis, especially if the optical axes of the optical sensors are oriented parallel. The registration of reference coordinate systems can therefore refer to the determination of a relative position between the reference coordinate systems or to a transformation rule for converting coordinate values ​​based on one of the reference coordinate systems into coordinate values ​​based on the remaining reference coordinate system.Registration can also refer to the determination of the relative position of the sensor-specific reference coordinate system or the transformation rule for converting coordinate values ​​in the various sensor-specific reference coordinate systems with respect to a machine coordinate system or the reference coordinate system.

[0028] For the purposes of this disclosure, an optical sensor is a unit whose output signal enables the determination of at least one coordinate of a measuring point or of a test object in a sensor-specific reference coordinate system. The sensor can therefore include elements for signal generation as well as elements for... Applicant: Carl Zeiss Industrial Metrology GmbH

[0029] Our reference: P18.931WO 18.12.2025

[0030] The evaluation of these signals includes the totality of which provides the described output signal.

[0031] A (sensor-specific) reference coordinate system was already explained in the introduction.

[0032] A reference coordinate system of an optical sensor is, in particular, a one-, two-, or three-dimensional coordinate system, and more specifically, a Cartesian coordinate system. A reference coordinate system can comprise a (reference coordinate-specific) longitudinal axis (x-axis), lateral axis (y-axis), and vertical axis (z-axis), which can be oriented orthogonally to each other. It is possible that one or more axes of the two sensor-specific reference coordinate systems are oriented parallel to each other, in particular the z-axes, where the z-axes can correspond to the optical axes of the sensors. A sensor-specific reference coordinate system can be a sensor-fixed coordinate system.

[0033] The optical sensor can generate an output signal that represents a coordinate value of a measurement point along at least one of these axes, or that can be evaluated to determine this coordinate value. It is conceivable that an optical sensor, particularly the further optical sensor, is a one-dimensional sensor. This generates an output signal that enables the determination of a coordinate value along a single spatial direction, e.g., along a single axis, of the reference coordinate system. This axis can be a z-axis of the reference coordinate system, especially the one-dimensional one. Such an output signal could, for example, be a distance value representing the distance between the measurement point and a reference point of the optical sensor along an optical axis of the sensor.

[0034] It is also conceivable that an optical sensor is a two-dimensional sensor. This generates an output signal, e.g., in the form of a two-dimensional image, which enables the determination of coordinate values ​​of one or more imaged points of the test object along two spatial directions, in particular axes of the reference coordinate system, where the reference coordinate system can in particular be a two-dimensional coordinate system.

[0035] Accordingly, an evaluation of an output signal from a three-dimensional sensor can enable the determination of the coordinate values ​​along all axes of the reference coordinate system, where the reference coordinate system is defined by: Carl Zeiss Industrial Metrology GmbH

[0036] Our reference: P18.931WO 18.12.2025 This can be, in particular, a two-dimensional coordinate system. For example, with an image acquisition device, taking into account the position of the focal point, coordinate values ​​can be determined along three axes.

[0037] The coordinate values ​​determined in the corresponding reference coordinate system can then be transformed or converted into the reference coordinate system. This transformation can be performed taking into account the spatial orientation of the respective sensor. By considering the spatial orientation, it is also possible to determine coordinate values ​​in a predetermined number, in particular three, dimensions of the reference coordinate system, even if the dimensionality of the reference coordinate system is lower.

[0038] To determine the spatial orientation, at least one axis position of the coordinate measuring machine can be defined. The term "axis" can refer to one of the defined directions of movement along which a component of the measuring machine can move translationally or rotationally. A coordinate measuring machine typically has one or more translational axes, which can correspond to the spatial directions X, Y, and Z. Depending on the design, additional rotational axes may be present, for example, for rotating the measuring head or a rotary table. Each axis enables movement along a travel path. The coordinate measuring machine may also include position or angle sensors for detecting an axis position.

[0039] The axis position can be the instantaneous position or orientation of an axis relative to its reference. For a translational axis, this is, for example, a linear position value; for a rotational axis, it is, for example, an angular value. All axis positions of the system can be recorded at any given time, providing a complete description of the machine's mechanical state.

[0040] The spatial position or pose of a sensor can then be determined from the combination of all axis positions, which together determine where the sensor is located spatially and how it is oriented.

[0041] If not all axis-specific coordinate values ​​and / or axis-specific coordinate values ​​can be completely determined by evaluating the sensor output signal with respect to the reference coordinate system, the remaining axis-specific coordinate values ​​and / or the complete determination can be carried out. Applicant: Carl Zeiss Industrial Metrology GmbH

[0042] Our reference: P18.931WO 18.12.2025 Axis-specific coordinate values ​​are determined in the sensor-specific reference coordinate system, taking into account additional information, such as information about the spatial orientation of the corresponding sensor or at least one set operating parameter of the sensor, such as a set focus value. This additional information can be determined, in particular, from the sensor itself. Specifically, the output signals of the position or angle sensors can be evaluated for this purpose.

[0043] In other words, the relative position of several elements of the coordinate measuring machine that are movable relative to each other, in particular an axis position and the resulting coordinates of the position of the measuring head, can be determined using sensors, whereby the coordinate values ​​along the remaining axes are then determined depending on this spatial position.

[0044] The radial measurement accuracy of the first optical sensor is higher than the radial measurement accuracy of the second optical sensor. Alternatively, the second optical sensor has no radial measurement accuracy. The axial measurement accuracy of the second optical sensor is higher than the axial measurement accuracy of the first optical sensor. Alternatively, the first optical sensor has no axial measurement accuracy.

[0045] Axial measurement accuracy can, in particular, refer to measurement accuracy along an optical axis or a main detection direction of the optical sensor. Thus, axial measurement accuracy can denote the accuracy with which measurement points can be detected along the optical axis, especially in a given spatial orientation of the optical sensor. The fact that the additional optical sensor lacks radial measurement accuracy can mean that, in a given spatial orientation of the additional optical sensor, it is not possible to detect radially displaced measurement points, i.e., points offset perpendicular to the optical axis, especially with a predetermined minimum accuracy.

[0046] Radial measurement accuracy can refer to measurement accuracy along a spatial direction that is oriented transversely, particularly perpendicularly, to the optical axis or the main detection direction. Thus, radial measurement accuracy can denote the accuracy with which measurement points transverse to the optical axis can be detected, especially in a predetermined spatial orientation of the optical sensor. The fact that the first optical sensor lacks axial measurement accuracy can mean that, in a predetermined spatial orientation of the first optical sensor, it is not possible to detect axially displaced measurement points, i.e., points offset along the optical axis, particularly with a predetermined [Applicant: Carl Zeiss Industrial Metrology GmbH]

[0047] Our reference: P18.931WO 18.12.2025

[0048] Minimum accuracy.

[0049] The fact that the radial measurement accuracy of the first optical sensor is higher than that of the second optical sensor describes the case where, for a given sensor pose (sensor position and / or sensor orientation), the second optical sensor cannot detect different measurement points that are radially spaced apart. Each optical sensor can have an optical axis, or each sensor can be assigned an optical axis. An example of such a sensor configuration is when the first optical sensor is a two-dimensional image acquisition device and the second optical sensor is a confocal white light sensor. With a two-dimensional image acquisition device, the coordinates of multiple measurement points can typically be determined in a single sensor pose, i.e., a single sensor position and / or sensor orientation, without changing the position of the image acquisition device.In particular, the image acquisition device generates output signals, e.g., in the form of grayscale or color value signals, for a large number of pixels, and coordinate values ​​can then be determined for each pixel based on these pixel-specific output signals. Preferably, however, coordinate values ​​are determined only for selected pixels. For example, grayscale or color value-based edge detection can be performed, and coordinate values ​​are then determined for the pixels that represent an edge.

[0050] In contrast, with the described white light sensor, only the coordinates of a single measurement point can typically be determined for a given sensor pose. Therefore, the sensor pose is usually changed to capture different measurement points and to determine the measurement point-specific coordinate values ​​for each point. The output signal of a white light sensor can be defined, in particular, as an intensity signal, especially an intensity signal per wavelength, or as a signal representing a distance value from a sensor reference point, e.g., the TCP of the white light sensor.

[0051] With respect to the (sensor-specific) reference coordinate system, axial measurement accuracy can refer to the measurement accuracy along a spatial direction along which the optical axis extends in the reference coordinate system. Similarly, radial measurement accuracy can refer to the measurement accuracy along a spatial direction perpendicular to this spatial direction of the optical axis (x- and y-axes). It is possible that the spatial direction is oriented parallel to an axis of the reference coordinate system. E.g., Applicant: Carl Zeiss Industrial Metrology GmbH

[0052] Our reference: P18.931WO 18.12.2025. The optical axis can be oriented parallel or concentric to the vertical axis (z-axis) specific to the reference coordinate system described above. In this case, high axial measurement accuracy results in high measurement accuracy along this vertical axis. However, it is not mandatory that such a spatial direction be oriented parallel to an axis of the reference coordinate system. In this case, high axial measurement accuracy can contribute to proportionally high measurement accuracy along several axes of the reference coordinate system.If the spatial direction is not parallel to an axis of the reference coordinate system, a coordinate value along that spatial direction can be used to determine the coordinate value along several axes of the reference coordinate system. However, the spatial direction-specific coordinate value may not be sufficient to completely determine the axis-specific coordinate values ​​with respect to the reference coordinate system, and coordinate values ​​along at least one other spatial direction are required for this. The fact that a sensor has a higher measurement accuracy along one spatial direction can include the case where no coordinate value along that spatial direction can be determined by evaluating the sensor output value of the remaining sensor.

[0053] The proposed procedure comprises the following steps:

[0054] In a first acquisition step, a plurality of measurement points from an initial set of measurement points are acquired by the first optical sensor, wherein the measurement points of the first set of measurement points are arranged in at least one registration area of ​​a surface of a calibration object. The registration area is therefore a surface region, and measurement points within this surface region are detectable by the first (and subsequent) optical sensor.

[0055] The registration area comprises at least two sub-areas with different reflection properties, in particular different reflectances. The calibration object has at least one optically detectable calibration feature located within the registration area of ​​the surface. This calibration feature can form one of the aforementioned sub-areas, in particular a first sub-area. Specifically, the calibration feature, or the sub-area in which the calibration feature is located, can have feature-specific reflection properties, in particular a reflectance, that differ from the reflection properties of another sub-area of ​​the registration area, which can in particular be an immediately adjacent sub-area. In particular, the sub-area in which the calibration feature is located is more reflective than the other sub-area.Applicant: Carl Zeiss Industrial Metrology GmbH.

[0056] Our reference number: P18.931WO 18.12.2025 therefore exhibits a higher reflectivity. The calibration object can also be designed such that the different sub-areas of the registration area have different transparency properties. For example, the sub-area in which the calibration feature is located can be opaque, while at least one other sub-area can be transparent.

[0057] The at least one calibration feature can be a line or dot structure, or a structure with a (different) predetermined geometric shape. It can be applied as a layer to a substrate. Thus, the calibration object can comprise a substrate and the at least one calibration feature. For example, a surface of the substrate can be coated with the calibration feature. The substrate can have different reflective properties than the calibration feature.

[0058] The reflection and transparency properties can refer to radiation from a predetermined wavelength range, e.g., white light radiation.

[0059] Each measurement point is assigned at least one piece of information that represents or is dependent on at least one sensor output value. It is possible for a measurement point to be assigned further (additional) information, such as a set operating parameter used to generate the sensor output value, e.g., a focus value. This information can be stored in a manner associated with the measurement point.

[0060] A measurement point can therefore denote a data point that represents at least one measurement point-specific piece of information. When acquiring measurement points, the information associated with each measurement point can be determined. For example, when acquiring the measurement points of the first set of measurement points, the measurement point-specific output signal of the first optical sensor can be acquired for each measurement point of the plurality of measurement points. Alternatively, one or more coordinate values ​​for the respective measurement point can be determined in the sensor-specific reference coordinate system. For the purposes of this disclosure, a measurement point can encompass or represent the information, i.e., the feature-specific output signal or at least one measurement point-specific coordinate value.

[0061] Such a calibration object can be produced by making the calibration object or a surface of the calibration object, in particular at least partially, available to the applicant: Carl Zeiss Industrial Metrology GmbH

[0062] Our reference: P18.931WO 18.12.2025

[0063] The calibration feature is coated. It is possible for the calibration object to be coated over its entire surface, with the at least one calibration feature being created by removing areas of the coating. This removal can be carried out by etching, in particular by chemical etching, electrolytic pickling, mechanical ablation, or plasma etching.

[0064] The calibration object or a support for the calibration object can be plate-shaped, in particular with at least one flat surface. The calibration object or at least the support can be made of glass, preferably fused silica, or of a ceramic material. Preferably, the calibration object or at least the support is made of a material with a low coefficient of thermal expansion, e.g., with a coefficient of expansion between 0 and 5 x 10⁻⁶. 6 1 / K, where this value describes a relative change in length per temperature change of one Kelvin.

[0065] Preferably, the registration area described above comprises a first sub-area containing the at least one calibration feature and an adjacent further area of ​​the surface exhibiting different reflection properties. These two areas can then form the sub-areas of the registration area. It is then possible to determine measurement points in the first set of measurement points that are measurement points in the sub-area containing the at least one calibration feature, as well as measurement points that are measurement points in the further sub-area. Measurement points in a sub-area here refer to measurement points that were generated during the measurement of a point or section of the calibration object in that sub-area. In other words, the measurement points in the first set of measurement points can include measurement points in both the first and the further sub-areas.

[0066] In particular, edge detection can be performed based on the recorded measurement points, whereby points lying on the edge are determined as reference element points of the first set of measurement points. Edge detection can be carried out using a known method. In other words, edge finding is performed in the registration area using known methods, with the reference element points lying on the identified edge.

[0067] It is also possible to determine selected, but not all, or all coordinate values ​​of this plurality of measuring points of the first set of measuring points, at least as a function of the corresponding sensor output value, namely in the applicant: Carl Zeiss Industrial Metrology GmbH

[0068] Our reference: P18.931WO 18.12.2025

[0069] The reference coordinate system of the first optical sensor or the reference coordinate system. These coordinate values ​​can be determined in a sensor-specific reference coordinate system, referring to the preceding explanations. In particular, it is possible to determine all axis-specific coordinate values ​​of the respective measurement points in the reference coordinate system, with at least one axis-specific coordinate value being determined as a function of the output signal of the optical sensor. The first optical sensor is preferably a two-dimensional sensor. However, the determination can also be carried out as a function of information about the spatial orientation of the sensor, which can be determined in particular as a function of motion information and position information.

[0070] In a second acquisition step, a plurality of measurement points from a further set of measurement points are acquired (analogously) with the additional optical sensor, whereby the measurement points of the further set of measurement points are arranged within the registration area of ​​the surface of the calibration object. Here, measurement points of the further set of measurement points can include measurement points in the first sub-area of ​​the registration area as well as measurement points in the further sub-area. This is done analogously to the acquisition of measurement points from the first set of measurement points. In particular, when acquiring the measurement points of the further set of measurement points, the measurement point-specific output signal of the additional optical sensor can be acquired for each measurement point of the plurality of measurement points. Alternatively, one or more coordinate values ​​for the respective measurement point can be determined in the sensor-specific reference coordinate system.

[0071] Each measurement point is therefore assigned information that represents at least one sensor output value, is dependent on it, and / or is additional information. Examples of additional information are explained in more detail below. Analogous to the previous explanations, selected (but not all), or even all, coordinate values ​​of this plurality of measurement points within the larger set of measurement points can be determined, at least as a function of the corresponding sensor output values, namely in the reference coordinate system of the larger optical sensor or in the reference coordinate system.

[0072] To record the measurement points, particularly the additional set of measurement points, and to determine the coordinate values ​​or additional information, a relative movement is performed between the respective sensor and the calibration object. Applicant: Carl Zeiss Industrial Metrology GmbH

[0073] Our reference: P18.931WO 18.12.2025

[0074] In particular, at least one sensor can be moved while the calibration object remains stationary. Alternatively, the calibration object can be moved while the optical sensor remains stationary. Finally, both the optical sensor and the calibration object can be moved.

[0075] To acquire the majority of measurement points in the first determination step, the first optical sensor can be positioned in exactly one or in several sensor poses within a machine coordinate system. To acquire the majority of measurement points in the second determination step, the additional optical sensor can be positioned in several sensor poses within the machine coordinate system.

[0076] The sensor pose refers to a sensor position and / or a sensor orientation. This can correspond to the position and / or orientation of the sensor-specific or fixed reference coordinate system in the reference coordinate system, i.e., in particular in the machine coordinate system.

[0077] The machine coordinate system can be a Cartesian coordinate system, comprising a longitudinal axis (x-axis), a transverse axis (y-axis), and a vertical axis (z-axis). The vertical axis can be parallel and oriented opposite to a weight force. The remaining axes can be perpendicular to each other and each perpendicular to the vertical axis.

[0078] The coordinate measuring machine can be configured to move the first and subsequent optical sensors and / or the calibration object relative to each other along these axes. In this configuration, one sensor can be moved while the calibration object remains stationary. Preferably, however, the calibration object is moved along at least one of these axes. These axes can therefore also be referred to as axes of motion. A position along these axes can be detected, for example, using a position sensor or a rotary angle sensor.

[0079] It is conceivable that the sensors are arranged on the coordinate measuring machine such that the optical axes are oriented parallel to the vertical axis (z-axis) of the machine coordinate system. In this case, a relative movement for acquiring measurement points can be performed in such a way that the distance between the sensor and the calibration object along the vertical axis remains constant. Applicant: Carl Zeiss Industrial Metrology GmbH

[0080] Our reference: P18.931WO 18.12.2025

[0081] The calibration object can be positioned on the surface of a measuring table within the detection range of the first optical sensor for measurement. Advantageously, the surface should be oriented parallel to the plane defined by the longitudinal (x-axis) and transverse (y-axis) axes of the machine coordinate system.

[0082] The measuring table and the calibration object placed on it can be illuminated with transmitted or reflected light for measuring the calibration object.

[0083] The measuring table can have a fixing feature on its surface designed for repeatable positioning of the calibration object. Alternatively, the calibration object can be positioned at the edge of the measuring table.

[0084] In an identification step, at least one corresponding reference element is determined for each set of measurement points, depending on the measurement points within that set and, in particular, the information assigned to these measurement points, such as a sensor output signal, a measurement point-specific coordinate value, or measurement point-specific additional information. For this purpose, exactly one or more measurement points can be identified that constitute a reference element or can be assigned to one. These measurement points can be referred to as reference element points. The identification of these measurement points can be achieved by evaluating the measurement point-specific sensor output signals, the measurement point-specific coordinate values, and / or by evaluating the additional information.If reference element points are identified based on measurement point-specific sensor output signals and / or by evaluating the measurement point-specific additional information, it is possible that coordinate values ​​are determined only for the identified reference element points.

[0085] In particular, edge detection can be performed to identify the reference element points. Specifically, if the first optical sensor is an image acquisition device, edge detection for the first set of measurement points can be performed using image evaluation methods, especially grayscale or color-value-based methods. If the optical sensor is a confocal white light sensor, edge detection for the subsequent set of measurement points can be performed by evaluating the distance values ​​and / or by evaluating additional information. In particular, an edge can be detected if the distance value and / or the additional information changes by more than a predetermined amount. Applicant: Carl Zeiss Industrial Metrology GmbH

[0086] Our reference: P18.931WO 18.12.2025

[0087] A reference element can, in particular, denote a reference point or a set of reference points. Corresponding reference elements represent the same point / section on the surface of the calibration object. If a reference point is defined as the corresponding reference element, it can be a measurement point from the described set of measurement points. However, it is also possible to define the reference point based on a plurality of measurement points from the respective set of measurement points, for example, as the center point of measurement points arranged in a circle or as a measurement point that can be uniquely identified in some other way.

[0088] In a determination step, a first transformation rule for determining coordinate values ​​based on an output signal of the first optical sensor and a further transformation rule for determining coordinate values ​​based on an output signal of the further optical sensor are determined in such a way that the coordinate values ​​of the corresponding reference element are the same or do not differ from each other by more than a predetermined amount.

[0089] Depending on these transformation rules, a transformation rule, in particular in the form of a shift vector, can then be determined that maps sensor reference points, e.g. the mentioned TCP, to each other.

[0090] Depending on these transformation rules, a transformation of coordinate values ​​between the reference coordinate systems can be determined, whereby this transformation can be determined depending on the coordinate values ​​of the corresponding reference element(s). A transformation rule can, in particular, be defined as or comprise a transformation matrix. The transformation can also be defined as or comprise a translation vector. In particular, it is possible that, by applying the transformation rule, coordinate values ​​of measurement points in the reference coordinate system of the first optical sensor can be transformed into the reference coordinate system of the second optical sensor, or vice versa. For example,One of the reference coordinate systems is designated as the reference coordinate system, and the transformation rule is then determined such that coordinate values ​​of measurement points in the remaining reference coordinate system are transformed into the reference coordinate system. Applicant: Carl Zeiss Industrial Metrology GmbH.

[0091] Our reference: P18.931WO 18.12.2025

[0092] The use of the calibration object designed as described above advantageously enables precise localization of the corresponding reference element in the sets of measurement points of the various optical sensors, which in turn allows a transformation rule to be determined with high accuracy.

[0093] In a preferred embodiment, the calibration object is designed as a chrome mask. More preferably, the optically detectable calibration feature is a chrome calibration feature. A chrome mask, which can also be called a photomask, typically comprises a substrate material, e.g., quartz or a ceramic material. This substrate can be coated, at least partially, with a layer of chrome.

[0094] In particular, the chromium mask can comprise a support body, preferably a plate-shaped support body, such as a glass plate, preferably a quartz glass plate, or a plate made of ceramic material, the surface of which is coated with chromium at least in sections. A chromium mask advantageously enables the application of chromium structures with extremely high accuracy, although the optical properties of chromium-coated and uncoated sections of the surface of the calibration object may differ. In particular, the calibration object can be designed such that a chromium-coated area has a higher reflectivity for radiation from a predetermined wavelength range, especially white light, than an area not coated with chromium.The calibration object can also be designed such that a chromium-coated area is opaque and an uncoated area, i.e., a chromium-free area, is transparent to radiation from a predetermined wavelength range, particularly white light. The adjacent area described above can also be referred to as a chromium-free area in the case of a chromium mask. The chromium-coated area can constitute the first sub-area described above, and the chromium-free area the second sub-area described above of the registration area.

[0095] The use of a chrome mask as a calibration object advantageously enables simple production of the calibration object, while allowing the previously explained precise identification of corresponding reference elements in the measurement point sets of the various optical sensors.

[0096] In another embodiment, the first optical sensor is a sensor for generating a two-dimensional image. The first optical sensor can therefore be an image acquisition device, in particular a CMOS or CCD sensor. The two-dimensional image can in particular be an RGB image or a grayscale image. Applicant: Carl Zeiss Industrial Metrology GmbH

[0097] Our reference: P18.931WO 18.12.2025. In particular, pixel values ​​of pixels in the two-dimensional image that represent a point or section of the first sub-area of ​​the registration area with the calibration feature can differ from pixel values ​​of the pixels that represent the further sub-area of ​​the registration area. In particular, such pixel values ​​can be reliably distinguishable. In other words, a two-dimensional image can be generated with such a sensor in which the first sub-area with the at least one calibration feature and preferably also the further sub-area of ​​the calibration object are depicted, wherein the corresponding image areas can be reliably identified as different image areas, for example by image evaluation methods.As explained previously, edge detection can be performed in particular to detect the edge pixels, i.e., pixels that define the boundary between the first and the subsequent sub-area. These edge pixels, or one of these edge pixels, can then be (a) reference element point(s).

[0098] In this embodiment, axis-specific coordinate values ​​can be determined for each pixel in the reference coordinate system of the first optical sensor, whereby these values ​​can depend on the respective pixel coordinate in an image coordinate system. Furthermore, the coordinate values ​​can also be determined depending on a focus value set during image generation. For example, it is conceivable that coordinate values ​​along the longitudinal and lateral axes of the reference coordinate system of the first sensor are determined depending on pixel coordinates, and a coordinate value along a vertical axis is determined depending on the set focus value. It is possible, for instance, that the longitudinal and lateral axes of the reference coordinate system of the first sensor are parallel to the two image axes of the generated image, which are oriented perpendicular to each other, and that the vertical axis is oriented perpendicular to these axes.

[0099] These coordinate values, or the coordinate values ​​of selected image points, e.g., edge image points, can then be transformed into the explained reference coordinate system or determined in it, in particular taking into account the spatial position of the first optical sensor in the reference coordinate system.

[0100] Such an optical sensor thus advantageously enables a very precise determination of the coordinate values ​​of the corresponding reference element, e.g., the coordinate values ​​of edge points, at least along two different spatial directions in the reference coordinate system. This, in turn, advantageously enables a precise determination of the transformation formula and thus accurate registration. Applicant: Carl Zeiss Industrial Metrology GmbH

[0101] Our reference: P18.931WO 18.12.2025

[0102] In a further embodiment, coordinate values ​​of a measuring point along two spatial directions, in particular along two axes, are determined in the reference coordinate system of the first sensor depending on pixel coordinates. The spatial directions can, in particular, be mutually perpendicular radial directions, i.e., directions that extend perpendicular to an axial direction in the reference coordinate system. This has been explained above. Alternatively or cumulatively, a coordinate value of a measuring point along a spatial direction in the reference coordinate system is determined depending on the set focus value. In particular, the focus value can be set using an autofocus function. This advantageously results—as explained above—in a simple and accurate determination of coordinate values.

[0103] In a further embodiment, the coordinate value of at least one coordinate of a measurement point from the set of further measurement points along at least one spatial direction in the reference coordinate system is determined by reflection. This can mean that properties of radiation reflected by the calibration object are evaluated to determine the coordinate value. In this embodiment, the further optical sensor or the coordinate measuring machine can include at least one illumination device that illuminates the calibration object, whereby this radiation is then reflected and can be used to determine the coordinate value. The illumination device can, in particular, be a white light illumination device, especially if the further optical sensor is designed as a confocal white light sensor.However, if the additional optical sensor is designed as an interferometric sensor, the lighting device can also generate radiation with wavelengths from a predetermined wavelength range that differs from the white light spectrum.

[0104] Reflection-based methods, such as confocal or interferometric methods, advantageously enable a very precise determination of a coordinate value of the measurement point along at least one spatial direction in the reference coordinate system. This coordinate value can then be transformed into, or determined within, the reference coordinate system described above, particularly taking into account the spatial orientation of the first optical sensor in the reference coordinate system. This, in turn, advantageously allows for a precise determination of the transformation procedure and thus accurate registration.

[0105] In a reflection-based determination, a coordinate value can be evaluated by assessing the properties of the reflected radiation. In particular, the output signal of a reflection-based sensor can provide a distance value along a [Applicant: Carl Zeiss Industrial Metrology GmbH]

[0106] Our reference: P18.931WO 18.12.2025

[0107] Represent spatial direction, whereby at least one coordinate value can be determined depending on the distance value.

[0108] The determination of at least one corresponding reference element can then be carried out depending on this coordinate value or a progression of this coordinate value for several measurement points, particularly in the reference coordinate system, which are assigned to the measurement points. For example, the measurement points in the first sub-area of ​​the registration area with the at least one calibration characteristic can be assigned distance-dependent coordinate values ​​that differ from the distance-dependent coordinate values ​​of measurement points in the further sub-area of ​​the registration area. This can be the case, in particular, if the distance-dependent coordinate values ​​represent a height profile of the surface of the calibration object.

[0109] This enables the precise determination of a reference element, such as an edge or the center point of a calibration feature. Reflection-based determination is particularly suitable when using a chrominoscope mask, especially since it typically provides high axial measurement accuracy and thus a reliable and precise determination of the corresponding reference element. This, in turn, advantageously leads to the accurate registration of a reference coordinate system for a reflection-based optical sensor, such as a confocal white light sensor or an interferometric sensor.

[0110] In another embodiment, the additional optical sensor is a reflection-based sensor. In a preferred embodiment, the reflection-based sensor is a confocal white light sensor. However, the reflection-based sensor can also be an interferometric sensor or another reflection-based sensor. Besides the previously described advantages of generally high measurement accuracy along its optical axis, the use of a reflection-based sensor offers the advantage that the distance value to the calibration object and the reference elements attached to it can also be used to reliably and accurately locate, in particular, the edges of the corresponding reference element.

[0111] In a further embodiment, at least the additional optical sensor for capturing the measurement points of the additional set of measurement points is moved relative to the calibration object. Then, at least one coordinate value in the reference coordinate system can be determined depending on movement information or information about the applicant: Carl Zeiss Industrial Metrology GmbH

[0112] Our reference: P18.931WO 18.12.2025 The measurement point-specific spatial positions of the additional optical sensor, which are set during movement, are determined and assigned to the measurement points. For example, depending on the movement information, position information, i.e., information about a spatial position and / or orientation of the additional optical sensor, i.e., information about the measurement point-specific spatial position, can be determined, or the movement information can be such position information, whereby at least one coordinate value can then be determined depending on the position information.

[0113] It is possible that the first optical sensor also performs the same movement to determine the coordinates of several measurement points within the first set of measurement points. However, this is not mandatory.

[0114] This makes it possible to determine a coordinate value for each measurement point along at least one, preferably all, spatial direction(s) in the reference coordinate system. In particular, coordinate values ​​along all axes of the reference coordinate system can thus be determined as a function of the information about the spatial orientation of the optical sensor and assigned to the measurement point. Specifically, it is possible for the relative movement between the additional optical sensor and the calibration object to occur perpendicular to the vertical axis (z-axis) of the sensor-specific reference coordinate system, which can, in particular, be parallel to the optical axis of the additional optical sensor.

[0115] In another embodiment, the additional information assigned to a measurement point within the set of measurement points is determined based on a property of a signal generated by the additional optical sensor when the measurement point is detected. The generated signal can, for example, be based on a reflection signal, i.e., reflected radiation. A sensor output value can be determined by evaluating the generated signal. However, the generated signal can also constitute the sensor output value itself.

[0116] For example, additional information can be obtained by determining a signal property of the generated signal, such as intensity information or an intensity profile. If the generated signal of the additional optical sensor exhibits one or more signal peaks, or if at least one signal peak is identified to determine the sensor output value, the additional information can also be a signal peak property, such as a [Applicant: Carl Zeiss Industrial Metrology GmbH]

[0117] Our reference: P18.931WO 18.12.2025

[0118] This could be signal peak width or signal peak symmetry. The additional information could also be information about the presence of exactly one or multiple signal peaks for a measurement point, or about the number of identified signal peaks.

[0119] Alternatively, the additional information can represent an operating parameter of the other optical sensor, such as an exposure time, which is set specifically for generating the sensor output value. This advantageously allows for a simple determination of the additional information, which in turn enables a simple and accurate identification of a corresponding reference element.

[0120] In a further embodiment, the additional information is information about the thickness of the calibration object, in particular about the availability of such thickness information for a specific measuring point. For this purpose, it may be necessary for the additional optical sensor to enable thickness measurement of a test object, whereby the thickness information can be encoded as part of the output signal. Particularly with a confocal white light sensor, thickness information can be determined if the signal generated by the additional optical sensor has several, in particular two, signal peaks, whereby the thickness information can be determined as a function of the distance between these signal peaks and, optionally, a previously known refractive index of the irradiated material. These signal peaks can be generated by changes in refractive index, e.g., during the transition from air to the calibration object or from the calibration object to air.Such thickness information is only available if the calibration object is transparent in the area of ​​the measured point or at least has a predetermined degree of transparency. If a measured point lies in an opaque area, e.g., the first sub-area (reference element) of the registration area described above, no thickness information is available due to the lack of transparency. Particularly with a calibration object that is transparent in an adjacent sub-area of ​​the registration area or has a predetermined degree of transparency, a reliable identification of the corresponding reference element can then advantageously be achieved. For example,Measurement points for which no thickness information is available can be identified as measurement points in / on the at least one calibration feature, i.e., in the first sub-area of ​​the registration area, while measurement points for which thickness information is available are identified as measurement points in the further sub-area. Then, for example, a midpoint of all measurement points lying in / on the calibration feature can be determined as a reference point. Applicant: Carl Zeiss Industrial Metrology GmbH.

[0121] Our reference: P18.931WO 18.12.2025

[0122] In another embodiment, the additional information is information about an exposure time. The exposure time can, in particular, be an automatically set exposure time, i.e., one that is calibrated or set using a control method. For example, the exposure time can be set depending on the intensity of the radiation detected by the additional optical sensor, i.e., the input signal, particularly in an automated manner. For example, the exposure time can be shortened with increasing intensity. If, for example, the additional sub-area of ​​the registration area, e.g., a chromium-free area, has a lower reflectivity than the first sub-area with the calibration feature, e.g.,Because the calibration object has a glass surface in the wider sub-area, it can be assumed that the intensity of the radiation reflected from this wider sub-area is lower than the intensity of the radiation reflected from the first sub-area. Therefore, the exposure time for acquiring measurement points in this wider sub-area is set, and in particular adjusted, to be longer than when acquiring measurement points on the calibration feature. Measurement points with shorter exposure times can then be identified as measurement points in / on the first sub-area containing the at least one calibration feature, while measurement points with longer exposure times are identified as measurement points in the wider sub-area.As explained above, depending on this identification, a reliable and accurate determination of the corresponding reference element can then be made, e.g., a center point of all measurement points in / on the at least one calibration feature.

[0123] In a further embodiment, the additional information is information about a property of at least one signal peak of a signal generated by the additional optical sensor when acquiring the measurement point. Such properties have already been explained above. In particular, the additional information can be information about the number of signal peaks present in the generated signal, which have been identified, especially using known methods. It can be assumed that the property of a signal peak for measurement points in a further sub-area of ​​the recording area, e.g., a chromium-free area, differs from the property of the signal peak for measurement points in / on the first sub-area with the calibration feature. Analogous to the previous explanations, this enables a reliable identification of the at least one calibration feature and thus a reliable and accurate determination of the corresponding reference element.Applicant: Carl Zeiss Industrial Metrology GmbH.

[0124] Our reference: P18.931WO 18.12.2025

[0125] In a further embodiment, the reference element is an edge of a calibration feature or is determined depending on an edge. In other words, the reference element can be an edge point or a set of edge points, particularly connected ones. Such an edge can be reliably and accurately identified in the first set of measurement points, as well as depending on the information assigned to the measurement points of the subsequent set of measurement points, thus enabling reliable and accurate localization of the reference element and therefore accurate registration. In particular, at least one edge point can be determined in each set of measurement points. Alternatively, the reference element is the center point of a calibration feature, particularly a point- or circular calibration feature. To determine the center point, an edge profile of the calibration feature can be determined, and the center point can be determined depending on the edge profile.Alternatively, the center point can be determined as the center point of all measurement points identified as measurement points at the edge of the calibration feature. This also enables a reliable and accurate determination of the reference element and thus precise registration.

[0126] In a further embodiment, to acquire the measurement points of the further set of measurement points, measurement points in a first sub-area of ​​the surface of a calibration object, which is in particular larger than or includes the registration area, are determined in a coarse acquisition pass with a first resolution, and in a fine acquisition pass, measurement points in a further sub-area of ​​the surface are determined with a further resolution, wherein the further resolution is higher than the first resolution and the further sub-area is determined depending on an evaluation of the measurement points in the first sub-area, wherein the measurement points in the further sub-area constitute the measurement points of the further set of measurement points.

[0127] In particular, by evaluating the measurement points in the first sub-area of ​​the surface, it can be determined in which section of this first sub-area a predetermined calibration feature is located. The subsequent sub-area can then be defined such that it is smaller than the first sub-area but includes the predetermined calibration feature. Specifically, this subsequent sub-area can then form the described registration area. This advantageously results in a rapid registration process.

[0128] A coarse scan with a sensor to generate a two-dimensional image can be performed with a first image resolution, and a fine scan with the sensor can be performed with a [Applicant: Carl Zeiss Industrial Metrology GmbH]

[0129] Our reference: P18.931WO 18.12.2025 Further image resolution is carried out, where the further image resolution is higher than the first image resolution. A coarse scan with a one-dimensional sensor, in particular a confocal white light sensor, can be carried out with an initial step size for capturing measurement points, where a fine scan with the sensor is then carried out with a further step size, the first step size being larger than the further step size.

[0130] In a further embodiment, the calibration object has at least one uncurved surface. In particular, the registration area with the at least one calibration feature can be a region of this uncurved surface. This advantageously results in a simple measurement of the calibration object, especially if the uncurved surface is oriented parallel to a plane spanned by two axes of movement (x- and y-axes) of the coordinate measuring machine, which are oriented at right angles to each other.

[0131] In another embodiment, a surface of the calibration object is oriented parallel to a plane defined by two axes of movement of the coordinate measuring machine, preferably oriented at right angles to each other. This advantageously results in a simple measurement of the calibration object, since only two of the three machine axes need to be moved. Preferably, the axes of movement defining the plane are the longitudinal and transverse axes (x-axis and y-axis) described above.

[0132] In a further embodiment, a relative movement between the calibration object and the additional optical sensor is performed to acquire the measurement points of the additional set of measurement points. A starting pose for this relative movement is determined and set based on the measurement points of the first set of measurement points. For example, the spatial position of a reference element can be determined by evaluating the measurement points of the first set of measurement points. The starting pose is determined such that the reference element is positioned within or as close as possible to the detection range of the additional optical sensor, or no more than a predetermined distance from the detection range. The starting pose can also be set based on a relative position between the additional optical sensor and the first optical sensor, which is typically predetermined by the design. For example, if...If a possible reference element is detected in the first set of measurement points and its coordinate values ​​are determined, the further optical sensor can be positioned with the coordinate measuring machine depending on the known relative position so that the possible reference element is located in the applicant: Carl Zeiss Industrial Metrology GmbH.

[0133] Our reference: P18.931WO 18.12.2025

[0134] The detection area of ​​the further optical sensor is arranged. It can be assumed that the actual relative position deviates from the previously known relative position, whereby the actual relative position can be determined using the method according to the invention.

[0135] For example, if, due to design specifications, a TCP of the second optical sensor is arranged along an axis of the reference coordinate system with a predetermined relative position to the TCP of the first optical sensor, and a reference element is detected along this axis in the first set of measurement points acquired from a sensor pose of the first sensor, then the second optical sensor can be moved into the starting pose by a movement along this axis by a distance corresponding to the relative position.

[0136] The positioning of the additional optical sensor in the starting pose can be described as pre-positioning or coarse positioning. Then, during the subsequent relative movement for capturing measurement points, which can also be referred to as fine positioning, measurement points can be acquired. Pre-positioning can be performed at a higher movement speed and / or with a larger step size than fine positioning.

[0137] A further proposed device is one for registering reference coordinate systems of a first optical sensor and at least one further optical sensor, wherein the device comprises the first and the at least one further optical sensor as well as a control and evaluation unit, the control and evaluation unit being configured to carry out a method according to one of the embodiments described in this disclosure. This results in the advantages already explained above. The control and evaluation unit can thus, in particular, perform the described steps of the method, especially control the acquisition steps and execute the identification and determination steps. It can be designed as a microcontroller or as an integrated circuit, or comprise one or more such.

[0138] In another embodiment, the device is part of a coordinate measuring machine, in particular a multi-sensor coordinate measuring machine. This advantageously allows for the simple and reliable registration of various optical sensors of a coordinate measuring machine. Applicant: Carl Zeiss Industrial Metrology GmbH

[0139] Our reference: P18.931WO 18.12.2025

[0140] The invention is explained in more detail using exemplary embodiments. The figures show:

[0141] Fig. 1 shows a schematic block diagram of a measuring head of a coordinate measuring machine,

[0142] Fig. 2 shows a schematic flowchart of a method according to the invention,

[0143] Fig. 3 shows a schematic flowchart of a method according to the invention in a further embodiment and

[0144] Fig. 4 shows an exemplary representation of a supplementary information card.

[0145] In the following, identical reference symbols denote elements with the same or similar technical characteristics.

[0146] Fig. 1 shows a schematic block diagram of a measuring head 1 of a multi-sensor coordinate measuring machine. The measuring head 1 comprises a first optical sensor 2, which can be configured, in particular, as a 2D image sensor. When acquiring measurement points, this sensor generates a two-dimensional color or grayscale image into which objects within a detection area are mapped. Each pixel of the generated image can be a measurement point of a first set of measurement points. A measurement point can therefore comprise the pixel coordinates of a pixel as well as a grayscale or RGB value.

[0147] The measuring head 1 additionally includes another optical sensor 3, which can be configured as a confocal white light sensor. A distance value can be assigned to a measuring point detected by the additional optical sensor 3 as a sensor output value or as a dependent variable. A measuring point can therefore encompass either this output value or the distance value. These sensors 2 and 3 are arranged in a fixed position relative to each other, i.e., with a constant relative position and orientation.

[0148] The first optical sensor 2 is assigned a sensor-specific reference coordinate system, which can subsequently be referred to as the first reference coordinate system UCS1. The second optical sensor 3 is also assigned a sensor-specific reference coordinate system, which can subsequently be referred to as the second reference coordinate system UCS2. The reference coordinate system of the first optical sensor 2 is a two-dimensional coordinate system and comprises an x-axis x1 and a y-axis (not shown) that is oriented perpendicular to the x-axis x1.

[0149] TI applicant: Carl Zeiss Industrial Metrology GmbH

[0150] Our reference number: P18.931WO 18.12.2025, and is oriented perpendicular to the plane of the drawing with respect to Fig. 1. This reference coordinate system can be an image coordinate system, where the axes x1 can be oriented parallel to a sensor surface of the image sensor. Also shown is an optical axis OA1 of the first optical sensor 2, which is oriented perpendicular to the axes described.

[0151] Also shown is a vertical axis z1, which can also be an axis of the reference coordinate system of the first optical sensor 2 and can be oriented perpendicular to the two remaining axes x1, particularly if, in addition to capturing pixel coordinates, it also allows the acquisition of a coordinate along this vertical axis z1, e.g., depending on a focus value set during image acquisition. This vertical axis z1 can, in particular, be oriented parallel to the optical axis OA1.

[0152] The reference coordinate system of the further optical sensor 3 is a one-dimensional coordinate system and includes a z-axis z2, which can correspond to an optical axis OA2 of the further optical sensor 2.

[0153] These reference coordinate systems BKS1, BKS2 are arranged in a fixed position relative to sensors 2, 3.

[0154] A reference coordinate system with a longitudinal axis xk and a vertical axis zk oriented perpendicular to it is also shown. The reference coordinate system also includes a transverse axis (not shown) that is oriented perpendicular to the longitudinal and vertical axes xk and zk, respectively. The optical axes OA1 and OA2 can be parallel to the vertical axis zk and thus also oriented parallel to it.

[0155] Coordinate values ​​of measurement points in the reference coordinate system, acquired by the first optical sensor 2, can be determined depending on the pixel coordinate and the spatial orientation of the measuring head 1 in the reference coordinate system. Coordinate values ​​of measurement points in the reference coordinate system, acquired by the second optical sensor 3, can be determined depending on the initial or distance value explained above, as well as the spatial orientation of the measuring head 1 in the reference coordinate system. The spatial orientation of the measuring head 1 can be determined—as previously explained—by evaluating the axis positions of the coordinate measuring machine.

[0156] It is desirable that such determined coordinates of a measuring point in the applicant: Carl Zeiss Industrial Metrology GmbH

[0157] Our reference: P18.931WO 18.12.2025

[0158] The reference coordinate system, which is captured by both the first sensor 2 and the second sensor 3, must be the same. For this to happen, it is necessary to register the reference coordinate systems; in other words, to determine a suitable transformation or calculation rule for calculating the coordinate values.

[0159] This also enables the identification of which pixel detected by the first optical sensor 2 in a given spatial orientation of the measuring head 1 corresponds to the measurement point detected by the second optical sensor 3 in the same spatial orientation. It is also possible to determine the distance between the optical axes OA1 and OA2 of sensors 2 and 3, where the distance is measured perpendicular to the optical axes. Furthermore, it is possible to determine the movement of the measuring head 1 within the reference coordinate system necessary to capture a selected measurement point, detected by the first optical sensor 2, with the second optical sensor 3.

[0160] The measuring head 1 also includes a tactile sensor 4. This is optional. Also shown is a control and evaluation unit 5, which is connected to the sensors 2, 3, 4 via data and / or signal transmission.

[0161] With respect to a radial spatial direction oriented transversely or orthogonally to the optical axis OA1 of the first optical sensor 2 (and which, in the illustrated embodiment, is oriented transversely to the z-axis z1 of the first reference coordinate system BKS1), the first optical sensor 2 can generate measurement points with a predetermined measurement accuracy based on the pixel coordinates. This measurement accuracy is higher than a measurement accuracy along an axial spatial direction oriented parallel to the optical axis OA1 (and which, in the illustrated embodiment, is oriented parallel or concentrically to the vertical axis z1 of the first reference coordinate system BKS1). In particular, it is possible that, at least when the first optical sensor 2 is in a constant spatial orientation, no different measurement points can be detected along the optical axis OA1.

[0162] With respect to an axial spatial direction oriented along the optical axis OA2 of the further optical sensor 3 (and which, in the illustrated embodiment, is parallel or concentric to the z-axis z2 of the second reference coordinate system BKS2), the further optical sensor 3 can generate measurement points with a predetermined measurement accuracy based on the output signals. In a radial spatial direction, i.e., perpendicular to the optical axis OA2, at least with a constant Applicant: Carl Zeiss Industrial Metrology GmbH

[0163] Our reference: P18.931WO 18.12.2025

[0164] Due to the spatial orientation of the additional optical sensor 3, no different measurement points can be recorded. In particular, no coordinate values ​​along these radial spatial directions can be determined based on the sensor output value of the additional sensor 3.

[0165] Overall, the radial measurement accuracy of the first optical sensor 2 is higher than that of the second optical sensor 3. This includes the case where no coordinate values ​​along radial spatial directions can be determined based on the sensor output values ​​of the second optical sensor 3. Similarly, the axial measurement accuracy of the second optical sensor 3 is higher than that of the first optical sensor 2. This includes the case where no coordinate values ​​along an axial spatial direction can be determined based on the sensor output values ​​of the first optical sensor 2.

[0166] Also shown is a calibration object 6 designed as a chrome mask, which is arranged in the detection areas of the optical sensors 2, 3.

[0167] This comprises a carrier body 7, which may in particular be made of at least partially transparent quartz glass, and a chromium calibration mark 8 arranged on a surface of the carrier body 7, which is applied to the carrier body 7 in particular by a coating process. The chromium calibration mark 8 is, for example, circular or dot-shaped and protrudes minimally, i.e., by a predetermined small amount, from the surface of the carrier body 7. The chromium calibration mark 8 covers the surface of the carrier body 7. A chromium-free area 9 is arranged spatially adjacent to the chromium calibration mark 8. The surface of the carrier body 7 is exposed in this chromium-free area 9. A surface area of ​​the calibration object 6, which includes both the calibration mark 8 and the chromium-free area 9, forms a registration area of ​​the surface.The sub-area of ​​the registration area formed by calibration feature 8 is a first sub-area of ​​this registration area. The sub-area formed by the chromium-free area 9 forms a further sub-area of ​​this registration area.

[0168] This configuration of the calibration object 6 as a chrome mask is purely exemplary. A calibration object 6 can also be used which has a calibration feature arranged on a surface, wherein the area with the calibration feature has a higher or lower reflectivity than an adjacent area of ​​the surface of the calibration object 6. Applicant: Carl Zeiss Industrial Metrology GmbH

[0169] Our reference: P18.931WO 18.12.2025

[0170] Fig. 2 shows a schematic flowchart of a method according to the invention. In a first acquisition step ES1, a plurality of measurement points from a first set of measurement points are acquired by the first optical sensor 2. The measurement points of the first set of measurement points lie within a registration area of ​​the surface of the calibration object 6 (see Fig. 1), which includes the chromium calibration feature 8 as well as at least a section of the chromium-free area 9, as the first and further sub-areas of the described registration area. In particular, the first optical sensor 2 can generate a two-dimensional image of this area. As explained above, each pixel can then correspond to a measurement point, or a measurement point can be determined for each pixel. Each measurement point can therefore contain information about image coordinates. Furthermore, a measurement point can contain information about a grayscale or RGB value.

[0171] In a second acquisition step ES2, a plurality of measurement points from a further set of measurement points are acquired using the additional optical sensor 3, whereby the measurement points of the further set of measurement points are also arranged within the described registration area. To acquire these measurement points, the additional optical sensor 3, in particular the measuring head 1, can be moved relative to the calibration object 6. For example, the calibration object 6 can be arranged on an xy-positioning table, and the table can be controlled accordingly to execute the relative movement. It is possible that the height of the positioning table can be changed in a z-direction, i.e., a direction perpendicular to the movement axes of the positioning table. Alternatively or cumulatively, a measuring head 1 with sensors 2 and 3 can be moved parallel to this z-direction.Alternatively, the additional optical sensor 3 is attached to movable elements of the coordinate measuring machine, in particular movable elements of so-called linear axes, whereby the movable elements can be controlled to execute the relative movement.

[0172] The control of the movement and the described acquisition of the measuring points can be controlled by the control and evaluation unit 5. The movement of the additional optical sensor 3 can be carried out in the spatial direction perpendicular to the optical axis OA2 of the additional optical sensor 3. In particular, the measuring head 1 shown in Fig. 1 can be moved to acquire the measuring points of the additional set of measuring points along the x-axis xk and / or along the y-axis (not shown) of a coordinate system of the coordinate measuring machine, i.e., the machine coordinate system, wherein the measuring head 1 with the additional optical sensor 3 is arranged such that its optical axis OA2 is oriented perpendicular to these axes. Applicant: Carl Zeiss Industrial Metrology GmbH

[0173] Our reference: P18.931WO 18.12.2025

[0174] It is possible, but not mandatory, that such a relative movement between the first sensor 2 and the calibration object 6 is also carried out in the first acquisition step ES1, especially if measurement points outside a detection range of the first optical sensor 2 are to be acquired in exactly one spatial position of the first optical sensor 2.

[0175] By recording the data, each measurement point on the surface in the further set of measurement points can be assigned information that corresponds to or depends on the corresponding sensor output value, e.g. a distance or intensity value.

[0176] Furthermore, coordinate values ​​for each measuring point can be determined with respect to exactly one, several, or all axes of the corresponding reference coordinate system BKS1, BKS2, e.g., by the control and evaluation unit 5, and assigned to the measuring point. These coordinate values ​​can be determined by evaluating the sensor output values.

[0177] Furthermore, coordinate values ​​for each measuring point can be determined with respect to exactly one, several, or all axes of the reference coordinate system, e.g., by the control and evaluation unit 5, and assigned to the measuring point. Alternative or cumulative information can also be taken into account during the determination, e.g., position information about the spatial location of the corresponding sensor 2, 3.

[0178] For example, a color or intensity value can be assigned to each pixel of a two-dimensional image generated by the first optical sensor 2. Coordinate values ​​along the x-axis x1 and y-axis of the first reference coordinate system BKS1, as shown in Fig. 1, can also be determined as a function of pixel coordinates and assigned to the measurement point. It is possible that a relative position between the image axes and these axes of the first reference coordinate system is known beforehand. For example, the image axes can be oriented parallel to these axes. A coordinate value with respect to the vertical axis z1 of the first reference coordinate system BKS1 can be determined as a function of a set focus value, which is set automatically, for example, by an autofocus function of the first optical sensor 2 and can be determined or read out, for example, by the control and evaluation unit 5.Applicant: Carl Zeiss Industrial Metrology GmbH.

[0179] Our reference: P18.931WO 18.12.2025

[0180] Image processing methods, which in particular evaluate the color or intensity values, can then be used to determine calibration feature measurement points, which correspond to measurement points on calibration feature 8 and thus in the first sub-area of ​​the registration area, and non-calibration feature measurement points, which lie in chromium-free areas 9 and thus in the further sub-area of ​​the registration area, as well as their coordinate values. In particular, a color- or gray-value-based edge detection method can be used to determine reference elements such as edges of a calibration feature 8 or the center points of a calibration feature 8, or reference element points, e.g., edge points, and their coordinates.

[0181] Each of the measurement points detected by the additional optical sensor 3 can be assigned the sensor output value it generates, which could be, for example, a distance value. Alternatively or cumulatively, additional information can also be assigned to the measurement point. Such additional information could, in particular, be information about the thickness of the calibration object 6 in the area of ​​the detected measurement point, or information about the availability of such information. Especially if the support body 7 is made of a transparent material, it can be assumed that measurement points to which no information about a thickness is assigned, or for which such information is not available, are measurement points on the calibration feature 8, and that measurement points to which information about the thickness is assigned, or for which such information is available, are non-calibration feature measurement points.

[0182] Further additional information can be information about the number of signal peaks and / or a property of at least one signal peak in a signal generated by the further optical sensor 3 during detection. In particular, if the carrier body 7 consists of a transparent material, it can be assumed that measurement points for which only exactly one signal peak is identifiable are measurement points on the calibration feature 8 and that measurement points for which several, in particular two, signal peaks are identifiable are non-calibration feature measurement points.

[0183] Further additional information can be information about an exposure time automatically set during the acquisition of the measurement point. In particular, if the carrier body 7 is made of a material with a lower reflectance than chromium, it can be assumed that measurement points acquired with a comparatively shorter exposure time are measurement points on the calibration feature 8 and that measurement points acquired with a comparatively longer exposure time are non-calibration feature measurement points. Applicant: Carl Zeiss Industrial Metrology GmbH

[0184] Our reference: P18.931WO 18.12.2025

[0185] The additional information can be generated by the optical sensor 3 and / or by the control and evaluation unit 5 and / or made available in a retrievable manner, for example as part of the sensor output value or as a separate signal. This provision can be carried out via a corresponding interface of the additional optical sensor 3.

[0186] For the measurement points detected by the additional optical sensor 3, coordinate values ​​can also be determined with respect to the previously described reference coordinate system and assigned to the measurement point. For this purpose, information about the spatial orientation of the additional optical sensor 3 (position information) during the detection of the measurement point can be evaluated. This position information can be determined based on motion information via the previously described relative motion. The relative motion can also be referred to as grid motion, whereby position information can be determined for each spatial orientation of the additional optical sensor 3 during the grid motion, and the coordinate values ​​of the measurement point can then be determined based on this position.The grid movement can be a movement with predetermined and, in particular, constant step sizes, whereby position information for a current measuring point is determined depending on the position information of the last recorded measuring point and the known step size for approaching the current position.

[0187] Position information can also be determined using sensors, for example by evaluating encoder output signals that represent the movement of a moving element of the coordinate measuring machine. In other words, the position information can be determined based on the axis position of the coordinate measuring machine as detected by sensors.

[0188] It is also conceivable that, depending on a measurement point-specific sensor output value, a coordinate value in relation to the previously explained z-axis z2 is determined as information and assigned to the respective measurement point.

[0189] Based on the measurement points of the additional measurement point set, a (supplementary) information map can be determined, which represents an assignment of the corresponding (additional) information to coordinate values, especially with respect to the longitudinal and transverse axes of the reference coordinate system. Applicant: Carl Zeiss Industrial Metrology GmbH

[0190] Our reference: P18.931WO 18.12.2025

[0191] The assignment and, if necessary, the determination of the assigned information can be part of the respective data acquisition steps ES1 and ES2. The measurement point can then encompass or represent the information.

[0192] In an identification step IS, depending on the measurement points of the respective sets of measurement points and the information assigned to these measurement points, at least one corresponding reference element per set of measurement points can be determined.

[0193] For example, corresponding edges or edge points can be determined in the two-dimensional image generated by the first optical sensor 2, as well as in the (additional) information map. If the calibration feature is a circular feature, a circle fit can be performed for each set of measurement points, depending on the edges or measurement points and their associated (additional) information, to determine a regression circle and a center point of this regression circle can be determined as a reference element. Coordinate values ​​of this center point can also be determined.

[0194] An edge point can also be detected in the first set of measurement points. Then, the measuring head 1 and / or the calibration object 6 can be moved along a trajectory along which the edge point is located. Then, with the additional optical sensor 3, measurement points can be acquired along the trajectory, where one measurement point corresponds to the edge point or where the edge point is located between two measurement points. The edge point can be detected, in particular, based on the change in the additional information.

[0195] A starting point of this trajectory, into which the measuring head 1 and / or the calibration object 6 is moved, can be determined depending on a previously known target relative position between the sensors 2, 3, whereby this target relative position is known e.g. due to design data but may deviate from an actual relative position, e.g. due to inaccuracies in assembly.

[0196] In a determination step BS, a first transformation rule for determining coordinate values ​​based on an output signal of the first optical sensor 2 and a further transformation rule for determining coordinate values ​​based on an output signal of the further optical sensor 3 can then be determined such that the coordinate values ​​of the corresponding reference element are the same or differ from each other by no more than a predetermined amount. Applicant: Carl Zeiss Industrial Metrology GmbH

[0197] Our reference: P18.931WO 18.12.2025. Furthermore, in the determination step BS, a transformation rule for transforming coordinate values ​​between the reference coordinate systems can be determined as a function of the coordinate values ​​of the corresponding reference element. Such procedures are known to those skilled in the art.

[0198] Fig. 3 shows a schematic flowchart of a further embodiment of a method according to the invention. To acquire the measurement points of the additional set of measurement points, in a coarse acquisition step GES, measurement points in a first sub-area of ​​the surface of a calibration object 6 are acquired with a first positional resolution in the reference coordinate system using the additional sensor 3. In particular, a coarse (supplementary) information map can be determined in the coarse acquisition step GES, wherein, in particular, coordinate values ​​with respect to the longitudinal and transverse axes of the reference coordinate system are determined with a first positional resolution.

[0199] This can be done by performing the relative movement in such a way that the further optical sensor 3 with the first position resolution is positioned at different points along these axes.

[0200] Then, in a rough identification step (GIS), a spatial area of ​​calibration feature 8 can be determined in the reference coordinate system. Furthermore, as explained previously, a reference element and its coordinate values, e.g., the center point of a regression circle and its coordinate values, can be determined based on the measurement points recorded in the rough data acquisition step (GES).

[0201] In a fine-scale acquisition step (FES), measurement points in a further sub-area of ​​the surface of the calibration object 6 can be determined with a higher positional resolution than the first. This further sub-area is then determined based on an evaluation of the measurement points in the first sub-area. In particular, the further sub-area can be defined such that it encompasses the spatial region of the calibration feature 8 identified in the coarse-scale acquisition step (GES). Alternatively, the further sub-area can be defined such that it comprises only one section or several different sections of the calibration feature 8, e.g., one or more sections with an edge of the calibration feature 8. Preferably, however, the further sub-area also includes a section of a chromium-free area 9 adjacent to the calibration feature. The further sub-area can therefore be smaller than the first sub-area.In particular, the further sub-area can form the registration area described. Applicant: Carl Zeiss Industrial Metrology GmbH.

[0202] Our reference: P18.931WO 18.12.2025

[0203] The measurement points recorded in the detailed data acquisition step (DEA) in the subsequent sub-area can then form the measurement points of the further data set. In particular, a reference element and its coordinate values, e.g., the center point of a regression circle and its coordinate values, can then be determined in a detailed identification step (DIS) based on the measurement points recorded in the detailed data acquisition step (DEA) – as explained previously.

[0204] Fig. 4 shows an exemplary representation of an additional information map. Values ​​on an abscissa can represent coordinate values ​​of measurement points with respect to a longitudinal axis xk of the reference coordinate system, which were determined based on the output signal of the additional optical sensor 3. Values ​​on an ordinate can represent coordinate values ​​of measurement points with respect to a transverse axis of this coordinate system. The duration of an exposure time for the acquisition of the respective measurement points is plotted above these values. Here, a hatched area represents shorter exposure times compared to the unhatched area. Since more light is reflected in the area of ​​the chrome calibration mark 8, a shorter exposure time is set by automated exposure control when acquiring measurement points on the chrome calibration mark 8 under constant illumination conditions.Therefore, the hatched area represents the chrome calibration feature 8. A circle fit can then be used to determine a regression circle and its center point M as a reference element. If this center point M and its coordinate values ​​are also determined in a two-dimensional image generated by the first optical sensor 2, and thus in the first reference coordinate system BCS1, then the transformation rule for transforming coordinate values ​​from the first reference coordinate system BCS1 to the second reference coordinate system BCS2, or vice versa, can be determined based on the coordinate values ​​of these center points M.

[0205] Applicant: Carl Zeiss Industrial Metrology GmbH

[0206] Our reference: P18.931WO 18.12.2025

[0207] Reference symbol list

[0208] 1 measuring head

[0209] 2 first optical sensor

[0210] 3 additional optical sensors

[0211] 4 tactile sensors

[0212] 5 Control and evaluation unit

[0213] 6 Calibration object

[0214] 7 Carrier bodies

[0215] 8 Chrome calibration feature

[0216] 9 chrome-free area

[0217] BKS1 reference coordinate system

[0218] BKS2 reference coordinate system

[0219] BS Determination Step

[0220] ES1 first recording step

[0221] ES2 second recording step

[0222] FES fine-tuning step

[0223] FIS Fine Identification Step

[0224] GES Rough Recording Step

[0225] M Center

[0226] OA1 optical axis

[0227] OA2 optical axis

Claims

Applicant: Carl Zeiss Industrial Metrology GmbH Our reference: P18.931WO 18.12.2025 Patent claims 1. A method for registering reference coordinate systems of a first optical sensor (2) and at least one further optical sensor (3) of a coordinate measuring machine, wherein an axial measurement accuracy of an optical sensor (2, 3) denotes a measurement accuracy along an optical axis (OA1, OA2) of the optical sensor (2, 3) and a radial measurement accuracy denotes a measurement accuracy transverse to the optical axis (OA1, OA2) of the optical sensor (2, 3), wherein a radial measurement accuracy of the first optical sensor (2) is higher than a radial measurement accuracy of the further optical sensor (3) or the further optical sensor (3) has no radial measurement accuracy, and the axial measurement accuracy of the further optical sensor (3) is higher than an axial measurement accuracy of the first optical sensor (2) or the first optical sensor (2) has no axial measurement accuracy, comprising the steps: - Acquiring a plurality of measurement points of a first set of measurement points with the first optical sensor (2), wherein a surface of the calibration object (6) comprises a registration area having a first and at least one further sub-area with different reflectances, wherein the measurement points of the first set of measurement points are arranged in the registration area of ​​the surface of the calibration object (6), wherein the calibration object (6) has at least one calibration feature (8) which is arranged in the registration area of ​​the surface, wherein each measurement point is assigned information which represents or depends on at least one sensor output value, - Capturing a plurality of measurement points of a further set of measurement points with the further optical sensor (3), wherein the measurement points of the further set of measurement points are arranged in the registration area of ​​the surface of the calibration object (6), wherein each measurement point is assigned information that represents or is dependent on at least one sensor output value and / or is additional information, - Identifying at least one corresponding reference element per set of measurement points, depending on the measurement points of the respective set of measurement points and the information assigned to these measurement points, - Determining a first transformation rule for determining coordinate values ​​based on an output signal from the first optical sensor and a further transformation rule for determining coordinate values ​​based on an output signal from the second optical sensor Applicant: Carl Zeiss Industrial Metrology GmbH Our reference: P18.931WO 18.12.2025 Sensors such that the coordinate values ​​of the corresponding reference element are the same or do not differ from each other by more than a predetermined amount.

2. Method according to claim 1, characterized in that the first optical sensor (2) is a sensor for generating a two-dimensional image.

3. Method according to claim 2, characterized in that coordinate values ​​of a measuring point of the first set of measuring points along two spatial directions in the reference coordinate system are determined by evaluating the image and / or a coordinate value of a measuring point along a spatial direction in the reference coordinate system is determined depending on the set focus value.

4. Method according to one of the preceding claims, characterized in that a coordinate value of at least one coordinate of a measuring point of the further set of measuring points along at least one spatial direction in the reference coordinate system is determined by reflection.

5. Method according to one of the preceding claims, characterized in that the further optical sensor (3) is a reflection-based sensor.

6. Method according to claim 5, characterized in that the further optical sensor is a confocal white light sensor.

7. Method according to one of the preceding claims, characterized in that at least the further optical sensor (3) is moved relative to the calibration object (6) for detecting the measurement points of the further set of measurement points.

8. Method according to one of the preceding claims, characterized in that the additional information is determined depending on a property of a signal generated by the further optical sensor (3) when detecting the measuring point or represents a set operating parameter of the further optical sensor (3).

9. Method according to one of the preceding claims, characterized in that the additional information is information about a thickness of the calibration object (6) Applicant: Carl Zeiss Industrial Metrology GmbH Our reference number is: P18.931WO 18.12.2025.

10. Method according to one of the preceding claims, characterized in that the additional information is information about an exposure time.

11. Method according to one of the preceding claims, characterized in that the additional information is information about a property of at least one signal peak of a signal generated by the further optical sensor (3) when detecting the measuring point.

12. Method according to one of the preceding claims, characterized in that a two-dimensional supplementary information map is determined, wherein the at least one corresponding reference element is determined by evaluating the supplementary information map.

13. Method according to one of the preceding claims, characterized in that the reference element - an edge of a calibration feature (8) or - is the center point of a calibration feature (8).

14. Method according to one of the preceding claims, characterized in that for recording the measuring points of the further set of measuring points - in a rough acquisition pass, measuring points in a first sub-area of ​​the surface of a calibration object (8) with a first resolution and - in a fine-scale acquisition pass, measurement points in a further sub-area with a further resolution are determined, wherein the further resolution is higher than the first resolution and the further sub-area is determined depending on an evaluation of the measurement points in the first sub-area, wherein the measurement points in the further sub-area form the measurement points of the further set of measurement points.

15. Method according to one of the preceding claims, characterized in that the calibration object (6) has at least one uncurved surface.

16. Method according to one of the preceding claims, characterized in that a surface of the calibration object (6) is oriented parallel to a plane spanned by two axes of movement of the coordinate measuring machine. Applicant: Carl Zeiss Industrial Metrology GmbH Our reference: P18.931WO 18.12.2025 17. Method according to one of the preceding claims, characterized in that a relative movement is carried out between the calibration object and the further optical sensor (3) to detect the measuring points of the further set of measuring points, wherein a starting pose of this relative movement is determined and set depending on the measuring points of the first set of measuring points.

18. Device for registering reference coordinate systems of a first optical sensor (2) and at least one further optical sensor (3), wherein the device comprises the first and the at least one further optical sensor (2, 3) and an evaluation device (5), wherein the evaluation device (5) is configured to perform a method according to any one of claims 1 to 17.

19. Device according to claim 18, characterized in that the device is part of a coordinate measuring machine.

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