DE102019216231A1 - Device and method for the dimensional measurement of sharp edges - Google Patents

Abstract

A device (110) for the dimensional measurement of a test object (112) is proposed. The device (110) has a plurality of lighting devices (116) which are set up to each generate at least one lighting pattern and to illuminate a surface of the test object (112) in a structured manner with the lighting pattern. The lighting devices (116) are arranged relative to one another in such a way that the test specimen (112) is illuminated from at least two spatial directions. The lighting patterns can be clearly assigned to the respective generating lighting device (116). The device (110) has a plurality of image recording devices (118). The image recording devices (118) are set up in each case to record at least one image of test patterns generated in response to the illumination of the illumination pattern from the surface of the test object (112). The recorded test samples each have a plurality of test features. The device (110) has at least one evaluation unit (120). The evaluation unit (120) is set up to assign the test features to the respective lighting device (116). The evaluation unit (120) is set up to determine information about the surface of the test object (112) by evaluating the assigned test features.

Description

Field of the invention

The invention relates to a device and a method for the dimensional measurement of a test object. The present invention relates in particular to the field of coordinate measuring technology, for example for measuring test objects such as components.

State of the art

In industrial metrology, the dimensional measurement of sharp edges, such as knife edges or tear-off edges on turbine blades, is becoming increasingly important. Methods known for measuring test objects with sharp edges can only be used to a very limited extent and are neither accurate nor high-resolution. In particular, these known methods cannot be used for extensive digitization of the edge or its surroundings.

Object of the invention

It is therefore the object of the present invention to provide a device and a method for the dimensional measurement of at least one test object which at least largely avoid the disadvantages of known devices and methods. In particular, a high-precision and rapid determination should take place.

Disclosure of the invention

This object is achieved by a device and a method having the features of the independent patent claims. Preferred configurations, which can be implemented individually or in combination, are presented in the dependent claims.

In the following, the terms “have”, “have”, “comprise” or “include” or any grammatical deviations therefrom are used in a non-exclusive manner. Accordingly, these terms can relate both to situations in which, besides the feature introduced by these terms, no further features are present, or to situations in which one or more further features are present. For example, the expression “A has B”, “A has B”, “A includes B” or “A includes B” can refer to the situation in which, apart from B, there is no other element in A (ie to a situation in which A consists exclusively of B) as well as to the situation in which, in addition to B, one or more further elements are present in A, for example element C, elements C and D or even further elements.

Furthermore, it should be noted that the terms “at least one” and “one or more” as well as grammatical modifications of these terms or similar terms, if these are used in connection with one or more elements or features and are intended to express that the element or feature simply or can be provided several times, usually only used once, for example when the feature or element is introduced for the first time. If the feature or element is subsequently mentioned again, the corresponding term “at least one” or “one or more” is generally no longer used, without restricting the possibility that the feature or element can be provided once or several times. Furthermore, the terms “preferably”, “in particular”, “for example” or similar terms are used below in connection with optional features, without this limiting alternative embodiments. Features introduced by these terms are optional features, and it is not intended to use these features to restrict the scope of protection of the claims and in particular of the independent claims. Thus, as the person skilled in the art will recognize, the invention can also be carried out using other configurations. In a similar way, features which are introduced by “in an embodiment of the invention” or by “in an exemplary embodiment of the invention” are understood as optional features, without this being intended to limit alternative configurations or the scope of protection of the independent claims. Furthermore, by means of these introductory expressions, all possibilities of combining the features introduced in this way with other features, be it optional or non-optional features, remain untouched.

In a first aspect of the present invention, a device for the dimensional measurement of a test object is proposed.

The term “test specimen” as it is used here is a broad term to which its usual and common meaning should be assigned, as understood by the person skilled in the art. The term is not limited to any specific or adapted meaning. The term can, without limitation, relate in particular to an object to be measured of any shape. For example, the test item can be selected from the group consisting of a workpiece and a component to be measured. For example, it can be with the test item be a knife edge or a spoiler edge of a turbine blade.

The term “dimensional measurement” as used here is a broad term to which its usual and common meaning should be assigned, as understood by the person skilled in the art. The term is not limited to any specific or adapted meaning. The term can, without limitation, relate in particular to determining at least one spatial coordinate of the test object, for example at least one point on a surface of the test object. The dimensional measurement can include determining at least one geometric property and / or a surface quality of the test object. The dimensional measurement can include determining dimensions of the test object, such as a change in surface curvature and / or a radius of an edge and / or a shape of an edge and / or a position of an edge and / or a roughness of an edge. The dimensional measurement can include a two-dimensional, preferably a three-dimensional, measurement of the test piece, in particular a planar measurement of the test piece. The dimensional measurement can include determining a plurality of surface space coordinates. The determined surface spatial coordinates can be used for a highly precise digitization of the test object. The device can, for example, be or comprise a coordinate measuring machine. The dimensional 3D measurement of a test piece can include a determination of a deviation of its delimiting surface from a specified target surface, as is evident from the target geometry of the test piece, and an indication of this deviation in calibrated, in particular traced back, metric units. The tolerable deviations and / or differences between actual and target surfaces can be dependent on the location wavelength. In the industrial environment, the rough categorizations for this spatial wavelength dependency are divided into so-called position tolerances, also referred to as long-wave, shape tolerances, also referred to as medium-wave, and surface and / or roughness tolerances, also referred to as short-wave.

The device has a plurality of lighting devices which are set up to generate at least one lighting pattern in each case and to illuminate a surface of the test object in a structured manner with the lighting pattern. The lighting devices are arranged relative to one another in such a way that the test specimen is illuminated from at least two spatial directions. The lighting patterns can be clearly assigned to the respective generating lighting device. The device has a plurality of image recording devices. The image recording devices are set up to record at least one image of test patterns generated in response to the illumination of the illumination pattern from the surface of the test object. The recorded test samples each have a plurality of test features. The device has at least one evaluation unit. The evaluation unit is set up to assign the test features to the respective lighting device. The evaluation unit is set up to determine information about the surface of the test piece by evaluating the assigned test features.

The term “lighting devices” as used here is a broad term which is to be given its usual and common meaning as understood by those skilled in the art. The term is not limited to a special or customized meaning. The term can, without limitation, relate in particular to a device which is set up to generate a light beam. In the context of the present invention, “light” can be understood to mean electromagnetic radiation in at least one spectral range selected from the visible spectral range, the ultraviolet spectral range and the infrared spectral range. The term visible spectral range basically comprises wavelengths from 380 nm to 780 nm. The term infrared (IR) spectral range basically comprises wavelengths from 780 nm to 1000 µm, with the range from 780 nm to 1.4 µm as near infrared (NIR), and the range from 15 µm to 1000 µm is called far infrared (FIR). The term ultraviolet basically comprises wavelengths from 100 nm to 380 nm. In the context of the present invention, preference is given to using IR light, that is to say light from the infrared spectral range. The term “light beam” can basically be understood to mean an amount of light that is emitted in a specific direction.

The term “lighting pattern” as used here is a broad term to which its usual and common meaning should be assigned, as understood by the person skilled in the art. The term is not limited to any specific or adapted meaning. The term can, without limitation, relate in particular to a predetermined and / or predefined beam distribution, also called a pattern, of light beams generated by the lighting device. The lighting pattern can be determined by an emission characteristic of a beam emanating from the lighting device. The lighting patterns can each have a plurality of lighting features. The term “lighting feature” as used here is a broad term to which its customary and common meaning is to be assigned, as understood by the person skilled in the art. The term is not limited to any specific or adapted meaning. The term can, without limitation, relate in particular to an element of the lighting pattern, for example a point or a line. The lighting patterns can each have at least one regular arrangement of the lighting features or at least one non-regular arrangement, in particular a random arrangement, of the lighting features. The lighting patterns can each have a point pattern and / or a line pattern and / or a grid, for example. The lighting devices can be set up to generate and / or project a point cloud. The lighting patterns can be selected depending on the measurement task.

The lighting devices can each have at least one light source, for example at least one light-emitting diode (LED) and / or at least one laser source. The lighting devices can have a plurality of light sources, for example light sources of different colors. The lighting devices can each have at least one stencil or mask for generating the lighting pattern. The lighting devices can each have at least one imaging optics and / or diffraction optics. The lighting devices can each have at least one optical fiber. The optical fiber can have at least one fiber outlet with refractive and / or diffractive optics. The use of optical fibers can enable the greatest possible compactness. As an alternative or in addition, the lighting devices can each have at least one laser projector. The laser projector can be set up to generate a random pattern. The term “structured lighting”, as it is used here, is a broad term which is to be given its usual and common meaning as understood by the person skilled in the art. The term is not limited to any specific or adapted meaning. The term can, without limitation, relate in particular to illuminating the surface of the test object with a predefined illumination pattern.

The lighting patterns can be clearly assigned to the respective generating lighting device. The lighting patterns can each have at least one piece of identification information. The term “identification information” as used here is a broad term to which its customary and common meaning should be assigned, as understood by the person skilled in the art. The term is not limited to any specific or adapted meaning. The term can, without limitation, relate in particular to information by means of which a generated lighting pattern can be clearly assigned to a lighting device. The identification information can be a known local group and / or an ID-coding subpattern and / or a wavelength of the light beams generated by the lighting device and / or a switch-on time or switch-on time interval. For example, a local group can be a well-known random pattern. The image recording devices can be set up to determine the identification information. The image recording devices on which the respective test pattern is imaged can be designed, for example with regard to resolution and / or color channels, in such a way that the identification information can be recorded.

The identification information can alternatively or additionally also take place via the temporal assignment of certain switch-on times of the lighting to certain shutter times of the cameras used.

The lighting devices can have coherent light sources. In this way, “speckle interferometry” approaches can be integrated, in which the topography of a rough test object when irradiated with coherent light when viewed in the far field. leads to a grainy image, which is due to partially destructive interference from surface areas with different heights.

The lighting devices can illuminate the surface of the test piece simultaneously or sequentially. For example, some of the lighting devices can be operated simultaneously and others sequentially to them. In particular when using more than three lighting devices, for example four, five, six, ten and more lighting devices, sequential switching can take place. Otherwise a coding depth could be too great.

The lighting devices can be arranged relative to one another in such a way that the test specimen is illuminated from at least two spatial directions. The dimensional measurement can take place in a coordinate system, for example a Cartesian coordinate system or a spherical coordinate system. Other coordinate systems are also conceivable. An origin or zero point of the coordinate system can be at a point on the device. The term “spatial direction”, as used here, is a broad term to which its usual and common meaning should be assigned, as understood by the person skilled in the art. The term is not limited to any specific or adapted meaning. The term can, without limitation, refer in particular to a spatial alignment of the beam distribution of the refer to the respective lighting pattern. In particular, the spatial direction can be defined by a central beam of the beam distribution. For example, three lighting devices can be provided, the lighting devices being arranged with respect to one another in such a way that the central rays of the beam distributions propagate perpendicular to one another.

As used herein, the term “image pickup device” is a broad term to which its customary and common meaning should be given, as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. The term can, without limitation, relate in particular to a device which is set up to record at least one image. A “recording of an image” can be understood to mean capturing and / or recording an image. The image recording device can have at least one camera, for example at least one camera chip. The camera can for example have at least one CMOS camera and / or at least one CCD camera. The image recording devices can have different viewing directions.

The term “test sample” as it is used here is a broad term to which its usual and common meaning should be assigned as understood by the person skilled in the art. The term is not limited to any specific or adapted meaning. The term can, without limitation, refer in particular to a reflection pattern or scattering pattern generated by the surface of the test piece in response to the illumination of the illumination pattern. The test pattern can be generated by reflecting the structured light on the surface of the test object. The test pattern can be generated by scattering the structured light on the surface of the test object. The recorded test samples each have a plurality of test features. The term “test feature” as used here is a broad term to which its customary and common meaning should be assigned, as understood by the person skilled in the art. The term is not limited to any specific or adapted meaning. The term can, without limitation, relate in particular to an element of the test pattern which was generated from the surface of the test piece in response to an illumination feature.

An “evaluation unit” can generally be understood to mean an electronic device which is set up to evaluate images recorded by the image recording devices. For example, one or more electronic connections between the image recording devices and the evaluation unit can be provided for this purpose. The evaluation unit can for example comprise at least one data processing device, for example at least one computer or microcontroller. The data processing device can have one or more volatile and / or non-volatile data memories, it being possible for the data processing device to be set up in terms of programming, for example, to control the image recording devices. The evaluation unit can furthermore comprise at least one interface, for example an electronic interface and / or a man-machine interface such as an input / output device such as a display and / or a keyboard. The evaluation unit can, for example, have a central or decentralized structure. Other configurations are also conceivable. The evaluation unit can have at least one A / D converter.

The evaluation unit is set up to assign the test features to the respective lighting device. As stated above, the lighting patterns can each have at least one piece of identification information. The evaluation unit can be set up to determine the identification information in the images of the test pattern and to assign the test features to the respective generating lighting device on the basis of the identification information. The evaluation unit is set up to determine information about the surface of the test piece by evaluating the assigned test features. The term “information about the surface”, as used here, is a broad term to which its customary and common meaning should be assigned, as understood by the person skilled in the art. The term is not limited to any specific or adapted meaning. The term can, without limitation, relate in particular to information about a surface spatial coordinate. The information about the surface can further relate to a geometric property of the surface and / or about the surface properties, for example information about a change in surface curvature and / or a radius of an edge and / or about a shape of an edge and / or about a position of an edge and / or a roughness of an edge. The information about the surface can include a deviation of the surface from a predetermined target surface, as it emerges from the target geometry of the test object, and / or an indication of this deviation in calibrated, in particular traced back, metric units. The test pattern assigned to a lighting device can be changed in relation to the generating lighting pattern; in particular, the test pattern can have deviations and / or distortions compared to the generating lighting pattern. The evaluation unit can be set up to this To determine deviations and / or distortions and to determine the information about the surface of the test object from these.

The device can have at least one measuring cell, for example a multi-walled measuring cell. The term “measuring cell” as it is used here is a broad term to which its usual and common meaning should be assigned, as understood by the person skilled in the art. The term is not limited to any specific or adapted meaning. The term can, without limitation, relate in particular to a volume in which a dimensional measurement of the test object can take place. The measuring cell can have an opening through which the test item can be introduced into the measuring cell. For example, the device can have a three-walled measuring cell. In particular, the measuring cell can have at least three boundary surfaces. The measuring cell can have more than three boundary surfaces. For example, the measuring cell can be designed as a matrix and / or backdrop that completely or partially surrounds the test item. For example, the matrix and / or backdrop can be variable, in particular adaptable to the test object. The boundary surfaces can be designed as partially transparent panes or as Lambert scatterers. For example, the boundary surfaces can be designed as focusing screens. For example, the boundary surfaces can have a surface for which Lambert's law applies to each surface element of the boundary surface, in particular a side of the boundary surface facing the test object.

The images of the test samples can be deflectometric and / or photogrammetric. The term “deflectometric”, as used here, is a broad term to which its customary and common meaning is to be assigned, as understood by the person skilled in the art. The term is not limited to any specific or adapted meaning. The term can, without limitation, refer in particular to the fact that the image has a test pattern generated by reflection on the surface of the test object. The term “photogrammetric”, as used here, is a broad term to which its customary and common meaning should be assigned, as understood by the person skilled in the art. The term is not limited to any specific or adapted meaning. The term can, without limitation, refer in particular to the fact that the image has a test pattern generated on the surface of the test object by scattering. The test patterns can each have stripe projections and / or line projections and / or pattern projections. The term “photogrammetric” can also include stereo images, which can be used for stereo reconstruction of the test item. In particular, the device can be set up to carry out a so-called “refractive stereo” method, as will be described further below. The device can be set up to recalculate the geometry of a light-refracting transparent object, that is to say of the test object, by recording the changes in direction of directed rays. This can be used for the production and / or qualification of parts with additive methods, in which typically the structures to be measured cannot be viewed from any perspective without shadowing.

In one embodiment, the images of the test patterns can be deflectometric. The test item can have a reflective surface. A lighting device which is set up to illuminate the test object in a structured manner can be arranged on each of the boundary surfaces of the measuring cell. Light beams generated by the lighting devices can strike the surface of the test object and be specularly reflected by it. At least some of the reflected light rays can strike one of the boundary surfaces.

For example, the image recording devices can be set up to record test patterns reflected and / or scattered from the surface of the test object in response to the illumination pattern. The evaluation unit can be set up to determine the information about the surface of the test object by comparing the reflected and / or scattered test patterns with the generating lighting patterns.

The boundary surfaces can be designed as partially transparent panes. The term “partially transparent”, as it is used here, is a broad term to which its usual and common meaning should be assigned, as understood by the person skilled in the art. The term is not limited to any specific or adapted meaning. The term can, without limitation, relate in particular to the transparency of the panes. The discs can be made of transparent plastic, for example. The panes can at least partially transmit incident light rays. The panes can be set up to weaken an intensity of an incident light beam, in particular by scattering. The panes can be designed as a ground glass. The disks can be configured to capture an image of the reflected test patterns. In each case one or more image recording devices can be arranged behind the panes in a direction of propagation of the reflected light beams. For example, the device can have three image recording devices, one image recording device each being arranged behind a pane. The panes can each have a frosted side, which is facing away from the image pickup device. The reflected test samples can generate light spots on the matted side. The image recording devices can be set up to photograph the focusing screen arranged in front of them. The image recording devices can be set up to record the test patterns recorded on the panes.

Reference marks can be attached to each of the disks. The reference marks can be designed and / or arranged in such a way that they obscure as little area of the panes as possible. The reference marks can be small compared to a diameter of the light spots of the reflected rays that fall on the focusing screen. The lighting devices can be arranged in the reference marks. The reference marks can be used to calibrate the image recording devices.

The evaluation unit can be set up to identify the light spots in the images of the image recording devices. For example, the evaluation unit can be set up to carry out at least one image processing algorithm, in particular an algorithm for recognizing features. The image processing algorithm can include filtering and / or background reduction and / or transformation. The image processing algorithm can include selecting a region of interest (ROI).

The evaluation unit can be set up to determine an emission characteristic of the light beams reflected from the surface of the test piece in response to the lighting pattern and hit the boundary surfaces and to provide the information about the surface of the test piece by comparing the determined emission characteristic with a previously known emission characteristic of the respective lighting device determine. If the radiation characteristics of the lighting devices are known, the evaluation unit can be set up to reconstruct from the images which of the rays were reflected from the surface of the test object and which passed the test object. The evaluation unit can be set up to reconstruct from the images which lighting device generated a recorded test feature. The information about the surface of the test object can be inferred from the distortion of the light beam distributions, in particular a spatial directional distribution of the beams that has changed compared to the known emission characteristics.

Light beams generated by the lighting devices can run past the test specimen and can be recorded by an image recording device opposite the respective lighting device. For example, for an embodiment of the device with a multi-walled measuring cell, light rays passing the test object can strike an opposing boundary surface. An image recording device arranged behind the boundary surface can, as described above, record an image of the incident light beams. The evaluation unit can be set up to identify, from the recorded image, areas of the lighting pattern, in particular emission intervals, which were not shaded by the test specimen, and to determine the information about the surface of the test specimen from these areas. For example, the evaluation unit can be set up to determine the information about the surface of the test object using a shadow casting method.

As an alternative or in addition, the images of the test patterns can include stereo images which can be used for stereo reconstruction of the test specimen. In particular, the device can be set up to carry out a so-called “refractive stereo” method. The device can be set up to recalculate the geometry of a light-refracting transparent object, that is to say of the test object, by recording the changes in direction of directed rays. For example, the test specimen can have a light-permeable material. In particular, the test specimen can have a refractive index different from air. The lighting device can be set up to generate at least one directed light beam, in particular a multiplicity of directed light beams. If one of the light rays falls on the surface of the test piece, a portion of the surface of the test piece is reflected and / or scattered and can be evaluated by deflectometry. This proportion can be small. For example, the test item can have an anti-reflective surface. The portion that has passed through the material of the test object can be recorded by at least one of the image recording devices. The evaluation unit can be set up to determine a change in direction of the light beams and from this to determine the information about the surface of the test object. In one embodiment, two of the lighting devices from the plurality of lighting devices can be arranged at spatially different locations, for example axially spaced apart, and illuminate the test object from at least two spatial directions. “Axially spaced” can be understood to mean that the coordinates of the two lighting devices differ in one direction. For example, a first lighting device can have the coordinates x, y and z1 and the second lighting device the coordinates x, y and z2. The Lighting devices can in particular lie in one plane. For example, the device can have at least two lighting devices per delimitation area, which are arranged distributed over the delimitation areas, for example evenly distributed. The device can have at least two image recording devices which are set up to record the transmitted light beams at at least two spatially different positions. The evaluation unit can be set up to determine changes in direction of the light beams from the recorded images and to determine the information about the surface of the test object therefrom. In particular, checkerboard patterns or other regular patterns can be used. Such patterns can be advantageous because the information about the surface of the test piece can be determined simply from the specific change in the recorded pattern. The manifold directionally structured bundles present due to the large number of lighting devices can thus be used to determine the information about the surface of the test object.

The device can be set up to move the test specimen along at least one axis, in particular relative to the boundary surfaces

Alternatively or additionally, in particular when measuring a non-reflective surface of the test object, the images can have scattered test patterns. The evaluation unit can be set up to evaluate the images of the test pattern using at least one triangulation method. The image recording devices can be set up to record test patterns scattered on the surface of the test object in response to the illumination pattern from at least two triangulation perspectives. The term “scattered test sample”, as used here, is a broad term to which its customary and common meaning should be assigned, as understood by the person skilled in the art. The term is not limited to any specific or adapted meaning. The term can, without limitation, relate in particular to a test pattern which was generated by scattering the light rays of the illumination pattern on the surface of the test piece. For example, the device can have four image recording devices. The measuring cell can have four corners. In each case one image recording device can be arranged at one corner of the measuring cell. An image recording from four triangulation perspectives can thus be possible. The image recording devices can have cameras with distortion independent of the working distance. The evaluation unit can be set up to evaluate the recorded test pattern photogrammetrically and to determine the information about the surface of the test object. From the images, known photogrammetric methods can be used to deduce spatial coordinates of the surface of the test object on which the identifiable light rays, for example pattern sections, were scattered. In this embodiment, the device can preferably have more than three lighting devices. In the event that a coding depth of the identification information for a large number of lighting devices becomes too great, it is possible to switch to sequential switching of the lighting devices.

For a photogrammetric determination of the information about the surface of the test object, the boundary surfaces of the measuring cell can preferably be designed as Lambert-scattering. For example, the boundary surfaces can be made of Spectralon ™. As an alternative or in addition, the triangulation perspectives can each be designed with such a large field angle that the entire opposing boundary surface can be captured in each case. Alternatively or additionally, the image recording devices can be designed with multi-aperture systems for different working distances. In this embodiment too, the device can preferably have more than three lighting devices. The lighting devices can be designed using fiber endoscopic technology, in particular to preserve the usable area. As stated above, at least one reference mark can be provided on each of the boundary surfaces. The lighting devices are preferably arranged in the reference marks so that they effectively do not take up any usable area. With a large number of lighting devices and image recording devices, it is also possible to work with systems with small field angles. The number of image recording devices can be selected depending on their parameters, working distances, depths of focus and field angles, since these determine which volume sections within the measuring cell can be imaged sharply, in particular sufficiently sharply, by the respective camera. In addition, the number of cameras required and their arrangement can depend on how many sufficiently sharp camera perspectives are required for how many and / or which measuring cell volume segments.

The device can be set up to carry out a roughness measurement on the surface of the test object. In particular, when a large number of structured lighting devices are installed, which preferably generate beam bundles that are preferably directionally distributed but approximately collimated and, in particular with regard to beam parameters and direction, are known a roughness measurement technique can be implemented. The large number of lighting devices allows a wide variety of possible combinations of light directions, light wavelengths and beam cross-sections for illuminating surface segments of the test object. From a combination of the deflectometric images, which are created by reflecting the structured light on the surface of the test piece on the known Lambert-scattering boundary surface, and the photogrammetric images, which are created by scattering similar and also known rays directly on the surface of the test piece, a measurement of the bidirectional reflectance distribution function (BRDF) of segments of the surface of the test object may be possible. The BRDF is a measure of the surface roughness of the surface segment. The number and distribution of the directional lighting devices can depend on the one hand on which relative orientations occur and / or can occur between the beam axis of the respective light source and the surface of the test object. In addition, the beam divergence and the desired spatial wavelength interval within which the surface roughness is to be measured can likewise determine the number and distribution of both lighting devices and / or image recording devices.

As stated above, the measuring cell can be designed as a matrix and / or backdrop which completely or partially surrounds the test item. For example, the matrix and / or backdrop can cover the test object completely in an x, y plane and partially in a z direction. The matrix and / or backdrop can be variable, in particular adaptable to the test item. The matrix and / or backdrop can have a plurality of Lambert-scattering boundary surfaces which the lighting devices, the image recording devices and the reference marks have. The boundary surfaces can be designed to be actuatable, it being possible for a distance and / or orientation of the boundary surfaces to the test object to be adjustable by means of actuators. For example, a connection with a length li can be provided between a delimitation surface and an actuator. By changing the length li, a distance and / or orientation of the boundary surfaces to the test object can be set. Since the actuators have spatially fixed and known positions Pi, a clear statement about the position and direction of the triangulation perspectives can be generated _{via the length l i.} A so-called extrinsic calibration of the camera system can thus be carried out. This can be stabilized with the aid of the intrinsic calibrations and reference to the reference marks. The lengths li can also be adapted and / or varied during operation, for example in order to follow a contour of the test object and / or in order to optimize optical conditions for the different measuring principles. By moving the matrix and / or the backdrop, and thus the position of the reference marks in space, the validity of the intrinsic calibrations of the installed optics can be checked.

1. a) Erzeugen jeweils mindestens eines Beleuchtungsmusters mit einer Mehrzahl von Beleuchtungsvorrichtungen und strukturiertes Beleuchten einer Oberfläche des Prüflings mit den Beleuchtungsmustern und/oder Durchstrahlen des Prüflings mit gerichteter strukturierter Beleuchtung, wobei die Beleuchtungsvorrichtungen derart relativ zueinander angeordnet sind, dass der Prüfling aus mindestens zwei Raumrichtungen beleuchtet wird, wobei die Beleuchtungsmuster der jeweiligen erzeugenden Beleuchtungsvorrichtung eindeutig zuordbar sind;
2. b) Aufnehmen jeweils mindestens eines Bildes von, in Antwort auf die Beleuchtung der Beleuchtungsmuster von der Oberfläche des Prüflings erzeugten, Prüfmustern mit einer Mehrzahl von Bildaufnahmevorrichtungen, wobei die aufgenommenen Prüfmuster eine Mehrzahl von Prüfmerkmalen aufweisen;
3. c) Zuordnen der Prüfmerkmale der jeweiligen Beleuchtungsvorrichtung mit einer Auswerteeinheit und Bestimmen einer Information über die Oberfläche des Prüflings durch Auswerten der zugeordneten Prüfmerkmale.

In a further aspect of the present invention, a method for the dimensional measurement of a test object is proposed. A device according to the invention is used in the method. The procedure consists of the following steps:

1. a) Generating at least one lighting pattern in each case with a plurality of lighting devices and structured lighting of a surface of the test specimen with the lighting patterns and / or irradiation of the test specimen with directed structured lighting, the lighting devices being arranged relative to one another in such a way that the test specimen illuminates from at least two spatial directions is, wherein the lighting pattern of the respective generating lighting device can be clearly assigned;
2. b) recording in each case at least one image of test patterns generated in response to the illumination of the lighting pattern from the surface of the test specimen with a plurality of image recording devices, the recorded test patterns having a plurality of test features;
3. c) Assigning the test features of the respective lighting device with an evaluation unit and determining information about the surface of the test object by evaluating the assigned test features.

The method steps can be carried out in the specified order, with one or more of the steps also being able to be carried out at least partially simultaneously and with one or more of the steps being able to be repeated several times. In addition, further steps can additionally be carried out regardless of whether they are mentioned in the present application or not.

For details and embodiments in relation to the method, reference is made to the description of the device according to the invention.

Furthermore, within the scope of the present invention, a computer program is proposed which, when running on a computer or computer network, for example a cloud, executes the method according to the invention in one of its configurations, in particular method steps b) and c).

Furthermore, within the scope of the present invention, a computer program with program code means is proposed in order to carry out the method according to the invention in one of its configurations when the program is executed on a computer or computer network. In particular, the program code means can be stored on a computer-readable data carrier.

In addition, within the scope of the present invention, a data carrier is proposed on which a data structure is stored which, after being loaded into a working and / or main memory of a computer or computer network, can execute the method according to the invention in one of its configurations.

In the context of the present invention, a computer program product with program code means stored on a machine-readable carrier is also proposed in order to carry out the method according to the invention in one of its configurations when the program is executed on a computer or computer network.

A computer program product is understood to mean the program as a tradable product. It can basically be in any form, for example on paper or a computer-readable data carrier, and can in particular be distributed via a data transmission network. For example, the evaluation of the resulting and / or resulting image material can be available as a web service, for example via a secure connection to the manufacturer's servers. This can be advantageous if there are insufficient computer resources available on site.

Finally, within the scope of the present invention, a modulated data signal is proposed which contains instructions that can be executed by a computer system or computer network for executing a method according to one of the described embodiments.

• Ausführungsform 1: Vorrichtung zur dimensionellen Vermessung eines Prüflings, wobei die Vorrichtung eine Mehrzahl von Beleuchtungsvorrichtungen aufweist, welche eingerichtet sind, jeweils mindestens ein Beleuchtungsmuster zu erzeugen und eine Oberfläche des Prüflings strukturiert mit dem Beleuchtungsmuster zu beleuchten, wobei die Beleuchtungsvorrichtungen derart relativ zueinander angeordnet sind, dass der Prüfling aus mindestens zwei Raumrichtungen beleuchtet wird, wobei die Beleuchtungsmuster der jeweiligen erzeugenden Beleuchtungsvorrichtung eindeutig zuordbar sind, wobei die Vorrichtung eine Mehrzahl von Bildaufnahmevorrichtungen aufweist, wobei die Bildaufnahmevorrichtungen eingerichtet sind, um jeweils mindestens ein Bild von, in Antwort auf die Beleuchtung der Beleuchtungsmuster von der Oberfläche des Prüflings erzeugten, Prüfmustern aufzunehmen, wobei die aufgenommenen Prüfmuster jeweils eine Mehrzahl von Prüfmerkmalen aufweisen, wobei die Vorrichtung mindestens eine Auswerteeinheit aufweist, wobei die Auswerteeinheit eingerichtet ist, um die Prüfmerkmale der jeweiligen Beleuchtungsvorrichtung zuzuordnen, wobei die Auswerteeinheit eingerichtet ist, um eine Information über die Oberfläche des Prüflings durch Auswerten der zugeordneten Prüfmerkmale zu bestimmen.

In summary, the following embodiments are particularly preferred in the context of the present invention:

• Embodiment 1: Device for dimensional measurement of a test specimen, the device having a plurality of lighting devices which are each set up to generate at least one lighting pattern and to illuminate a surface of the test specimen in a structured manner with the lighting pattern, the lighting devices being arranged relative to one another in such a way that that the test specimen is illuminated from at least two spatial directions, the lighting patterns being clearly assignable to the respective generating lighting device, the device having a plurality of image recording devices, the image recording devices being set up to each take at least one image of, in response to the illumination of the lighting pattern to record test samples generated by the surface of the test piece, the recorded test samples each having a plurality of test features, the device at least one evaluation unit, wherein the evaluation unit is set up to assign the test features of the respective lighting device, wherein the evaluation unit is set up to determine information about the surface of the test object by evaluating the assigned test features.

Embodiment 2: Device according to the preceding embodiment, the images of the test samples being deflectometric and / or photogrammetric.

Embodiment 3: Device according to one of the preceding embodiments, the lighting patterns each having at least one piece of identification information.

Embodiment 4: Device according to the preceding embodiment, the identification information being a known local group and / or an ID-encoding subpattern and / or a wavelength and / or a switch-on time or switch-on time interval, the image recording devices being set up to determine the identification information.

Embodiment 5: Device according to one of the preceding embodiments, the lighting patterns each having a plurality of lighting features, the lighting patterns each having at least one regular arrangement of the lighting features or at least one non-regular arrangement of the lighting features.

Embodiment 6: Device according to one of the preceding embodiments, wherein the lighting devices illuminate the surface of the test object simultaneously or sequentially.

Embodiment 7: Device according to one of the preceding embodiments, wherein the lighting devices each have at least one optical fiber, the optical fiber has at least one fiber output with refractive and / or diffractive optics.

Embodiment 8: Device according to one of the preceding embodiments, the lighting devices each having at least one laser projector.

Embodiment 9: Device according to one of the preceding embodiments, wherein the lighting devices have one or more coherent light sources.

Embodiment 10: Device according to one of the preceding embodiments, the device having at least one multi-walled measuring cell, the measuring cell having at least three boundary surfaces, the boundary surfaces being designed as partially transparent panes or as Lambert scatterers.

Embodiment 11: Device according to the preceding embodiment, each of the boundary surfaces having at least one reference mark.

Embodiment 12: Device according to one of the two preceding claims, wherein the measuring cell completely surrounds the test object.

Embodiment 13: Device according to one of the preceding embodiments, wherein the image recording devices are set up to record test patterns reflected and / or scattered from the surface of the test object in response to the illumination pattern, the evaluation unit being set up to compare the reflected and / or scattered Test pattern to determine the information about the surface of the test object with the generating lighting patterns.

Embodiment 14: Device according to one of the preceding embodiments, wherein the evaluation unit is set up to identify areas of the illumination pattern from the recorded image which were not shaded by the test specimen and to determine the information about the surface of the test specimen from these areas.

Embodiment 15: Device according to one of the preceding embodiments, wherein the evaluation unit is set up to determine the information about the surface of the test object from the recorded images using a refractive stereo method.

Embodiment 16: Device according to the preceding embodiment, wherein the device is set up to move the test specimen along at least one axis.

Embodiment 16: Device according to one of the preceding embodiments, wherein the image recording devices are set up to record scattered test patterns from at least two triangulation perspectives on the surface of the test specimen in response to the illumination pattern, the evaluation unit being set up to photogrammetrically evaluate the recorded test pattern and the information to be determined via the surface of the test object.

Embodiment 17: Device according to one of the preceding embodiments, wherein the device is set up to carry out a roughness measurement on the surface of the test specimen.

Embodiment 18: Device according to one of the preceding embodiments, the device having the at least one multi-walled measuring cell, the measuring cell having at least three boundary surfaces, the boundary surfaces being designed as partially transparent panes, the image recording devices being set up in response to the surface of the test object to record light rays reflected and / or scattered on the lighting pattern and striking the boundary surfaces.

Embodiment 19: Device according to the previous embodiment, the evaluation unit being set up to determine an emission characteristic of the light beams reflected from the surface of the test object in response to the lighting pattern and striking the boundary surfaces and by comparing the determined emission characteristic with a previously known emission characteristic of the respective lighting device to determine the information about the surface of the test piece.

1. a) Erzeugen jeweils mindestens eines Beleuchtungsmusters mit einer Mehrzahl von Beleuchtungsvorrichtungen und strukturiertes Beleuchten einer Oberfläche des Prüflings mit den Beleuchtungsmustern und/oder Durchstrahlen des Prüflings mit gerichteter strukturierter Beleuchtung, wobei die Beleuchtungsvorrichtungen derart relativ zueinander angeordnet sind, dass der Prüfling aus mindestens zwei Raumrichtungen beleuchtet wird, wobei die Beleuchtungsmuster der jeweiligen erzeugenden Beleuchtungsvorrichtung eindeutig zuordbar sind;
2. b) Aufnehmen jeweils mindestens eines Bildes von, in Antwort auf die Beleuchtung der Beleuchtungsmuster von der Oberfläche des Prüflings erzeugten, Prüfmustern mit einer Mehrzahl von Bildaufnahmevorrichtungen, wobei die aufgenommenen Prüfmuster eine Mehrzahl von Prüfmerkmalen aufweisen;
3. c) Zuordnen der Prüfmerkmale der jeweiligen Beleuchtungsvorrichtung mit einer Auswerteeinheit und Bestimmen einer Information über die Oberfläche des Prüflings durch Auswerten der zugeordneten Prüfmerkmale.

Embodiment 20: A method for the dimensional measurement of a test object, a device according to one of the preceding embodiments being used in the method, the method having the following steps:

1. a) Generating at least one lighting pattern in each case with a plurality of lighting devices and structured lighting of a surface of the test specimen with the lighting patterns and / or irradiation of the test specimen with directed structured lighting, the lighting devices being arranged relative to one another in such a way that the test specimen illuminates from at least two spatial directions is, wherein the lighting pattern of the respective generating lighting device can be clearly assigned;
2. b) recording in each case at least one image of test patterns generated in response to the illumination of the lighting pattern from the surface of the test specimen with a plurality of image recording devices, the recorded test patterns having a plurality of test features;
3. c) Assigning the test features of the respective lighting device with an evaluation unit and determining information about the surface of the test object by evaluating the assigned test features.

Figure list

Further details and features of the invention emerge from the following description of preferred exemplary embodiments, in particular in conjunction with the subclaims. The respective features can be implemented individually or in combination with one another. The invention is not restricted to the exemplary embodiments. The exemplary embodiments are shown schematically in the figures. The same reference numerals in the individual figures denote elements that are the same or functionally the same or correspond to one another in terms of their functions.

• 1A und 1B eine schematische Darstellung einer erfindungsgemäßen Vorrichtung und eines beispielhaften resultierenden Prüfmusters;
• 2A und 2B ein weiteres Ausführungsbeispiel einer erfindungsgemäßen Vorrichtung und eines beispielhaften resultierenden Prüfmusters;
• 3 ein weiteres Ausführungsbeispiel einer erfindungsgemäßen Vorrichtung; und
• 4 ein weiteres Ausführungsbeispiel einer erfindungsgemäßen Vorrichtung.

Show in detail:

• 1A and 1B a schematic representation of a device according to the invention and an exemplary resulting test sample;
• 2A and 2 B a further embodiment of a device according to the invention and an exemplary resulting test pattern;
• 3 another embodiment of a device according to the invention; and
• 4th another embodiment of a device according to the invention.

Embodiments

1A shows a schematic representation of a device according to the invention 110 for dimensional measurement of a test item 112 . The surface of the test piece is essentially reflective here. For example, the test item 112 be selected from the group consisting of a workpiece and a component to be measured. For example, it can be with the test item 112 be a knife edge or a spoiler edge of a turbine blade. The dimensional measurement can include determining at least one spatial coordinate of the test object 112 include, for example, at least one point on a surface of the test object 112 . The determined surface spatial coordinates can lead to a highly precise digitization of the test object 112 be used. The device 110 can for example be or comprise a coordinate measuring machine.

The device 110 has a plurality of lighting devices 116 which are set up to generate at least one illumination pattern and a surface of the test object 112 structured to illuminate with the lighting pattern. In 1A are three lighting devices 116 shown, which each generate a lighting pattern. In 1A are each from the lighting fixtures 116 emitted radiation beam shown. The lighting fixtures 116 are arranged relative to one another in such a way that the test object 112 is illuminated from at least two spatial directions. For example, three lighting devices 116 be provided, the lighting devices 116 are arranged to one another in such a way that the central rays of the beam distributions propagate perpendicular to one another. The lighting pattern can be one of the lighting device by an emission characteristic 116 outgoing ray bundle be determined. The lighting patterns can each have a plurality of lighting features. The lighting patterns can each have at least one regular arrangement of the lighting features or at least one non-regular arrangement, in particular a random arrangement, of the lighting features. The lighting patterns can each have a point pattern and / or a line pattern and / or a grid, for example. The lighting fixtures 116 can be set up to generate and / or project a point cloud. The lighting patterns can be selected depending on the measurement task.

The lighting fixtures 116 can each have at least one light source 114 have, for example at least one light-emitting diode (LED) and / or at least one laser source. The lighting fixtures 116 may have a plurality of light sources, for example light sources of different colors. The lighting fixtures 116 can each have at least one stencil or mask for generating the illumination pattern. The lighting fixtures 116 can each have at least one imaging optics and / or diffraction optics. The lighting fixtures 116 can each have at least one optical fiber. The optical fiber can have at least one fiber output with imaging and / or diffraction optics. The use of optical fibers can enable the greatest possible compactness. Alternatively or additionally, the Lighting devices each have at least one laser projector. The laser projector can be set up to generate a random pattern.

The lighting patterns are of the respective generating lighting device 116 clearly assignable. The lighting patterns can each have at least one piece of identification information. The identification information can be a known local group and / or an ID-encoding subpattern and / or a wavelength of the lighting device 116 generated light beams and / or a switch-on time or switch-on time interval. For example, a local group can be a well-known random pattern. The imaging devices 118 can be set up to determine the identification information. The imaging devices 118 , on which the respective test pattern is mapped, can be designed in such a way, for example with regard to resolution and / or color channels, that the identification information can be recorded.

As an alternative or in addition, the identification information can also be provided via the temporal assignment of certain switch-on times of the lighting to certain shutter times of the cameras used.

The lighting fixtures 116 can have one or more coherent light sources. "Speckle interferometry" approaches can be integrated in which the topography of a rough test object when irradiated with coherent light leads to a grainy image when viewed in the far field, which can be attributed to partially destructive interferences of surface areas with different heights.

The lighting fixtures 116 can the surface of the test object 112 illuminate simultaneously or sequentially. For example, some of the lighting devices 116 operated simultaneously and others sequentially to these. In particular when using more than three lighting devices 116 , for example four, five, six, ten and more lighting devices 116 , sequential switching can take place. Otherwise a coding depth could be too great.

The device 110 has a plurality of image pickup devices 118 on. The image recording devices are set up to record at least one image of test patterns generated in response to the illumination of the illumination pattern from the surface of the test object. The imaging devices 118 can each have at least one camera, for example at least one camera chip. The camera can for example have at least one CMOS camera and / or at least one CCD camera. The imaging devices 118 can have different viewing directions.

The recorded test samples each have a plurality of test features. The test pattern can be created by reflecting the structured light on the surface of the test object 112 be generated. The test pattern can be created by scattering the structured light on the surface of the test object 112 be generated.

The device 110 has at least one evaluation unit 120 on. The evaluation unit 120 can for example comprise at least one data processing device, for example at least one computer or microcontroller. The data processing device can have one or more volatile and / or non-volatile data memories, it being possible for the data processing device to be set up in terms of programming, for example, to control the image recording devices. The evaluation unit 120 can furthermore comprise at least one interface, for example an electronic interface and / or a man-machine interface such as an input / output device such as a display and / or a keyboard. The evaluation unit 120 can for example be set up centrally or decentrally. Other configurations are also conceivable. The evaluation unit 120 can have at least one A / D converter.

The evaluation unit 120 is set up to check the characteristics of the respective lighting device 116 assign. The evaluation unit 120 is set up to provide information about the surface of the test object 110 to be determined by evaluating the assigned test characteristics. As stated above, the lighting patterns can each have at least one piece of identification information. The evaluation unit 120 can be set up to determine the identification information in the images of the test pattern and, on the basis of the identification information, the test features of the respective generating lighting device 116 assign. The information about the surface can include a geometric property of the surface and / or about surface properties, for example information about a change in surface curvature and / or a radius of an edge and / or about a shape of an edge and / or about a position of an edge and / or a roughness of an edge. The information about the surface can include a deviation of the surface from a predetermined target surface, as it emerges from the target geometry of the test object, and / or an indication of this deviation in calibrated, in particular traced back, metric units. The a lighting device 116 assigned test pattern can be changed in relation to the generating lighting pattern, in particular the test pattern can have deviations and / or distortions compared to the generating lighting pattern. The evaluation unit 120 can be set up to determine these deviations and / or distortions and from these the information about the surface of the test object 112 to determine.

As in 1A shown, the device 110 at least one measuring cell 122 have, for example a multi-walled measuring cell. The measuring cell 122 may have an opening through which the test object 112 into the measuring cell 122 can be introduced. For example, as in 1A shown the device 110 a three-walled measuring cell 122 exhibit. In particular, the measuring cell 122 at least three boundary surfaces 124 exhibit.

1A shows an embodiment of a deflectometric determination of the information about the surface of the test object 112 . The examinee 112 can have a reflective surface. At each of the boundary surfaces 124 can be a lighting device 116 be arranged, which is set up to the test object 112 structured to illuminate. From the lighting fixtures 116 generated light rays can hit the surface of the test object 112 meet and be specularly reflected by this. At least some of the reflected light rays can hit one of the boundary surfaces 124 to meet. For example, the image recording devices 118 be set up from the surface of the specimen 112 record reflected and / or scattered test patterns in response to the illumination pattern. The evaluation unit 120 can be set up to obtain the information about the surface of the test object by comparing the reflected and / or scattered test patterns with the generating lighting patterns 112 to determine.

The boundary surfaces 124 can be designed as partially transparent panes. The discs can be made of transparent plastic, for example. The panes can at least partially transmit incident light rays. The panes can be set up to weaken an intensity of an incident light beam, in particular by scattering. The panes can be designed as a ground glass. The disks can be configured to capture an image of the reflected test patterns. One or more image recording devices in each case 118 can be arranged behind the panes in a direction of propagation of the reflected light rays. For example, the device 110 three imaging devices 118 each having an image pickup device 118 is arranged behind a disc. The panes can each have a matted side, which is the image recording device 118 is turned away. The reflected test samples can generate light spots on the matted side. The imaging devices 118 can be set up to photograph the ground glass in front of them. The imaging devices 118 can be set up to record the test patterns captured on the wafers. Reference marks can be placed on each of the disks 126 to be appropriate. The reference marks 126 can be designed and / or arranged in such a way that they obscure as little surface area of the panes as possible. The reference marks 126 can be small compared to a diameter of the light spots of the reflected rays that fall on the focusing screens. The lighting fixtures 116 can in the reference marks 126 be arranged. The reference marks 126 can for a calibration of the image recording devices 118 be used. The reference marks 126 can be used as a reference for identifying inspection features.

1B shows of the image pickup devices 118 of 1A resulting recorded test samples. The boundary surfaces in 1A are denoted by a, b, c. The recorded image on the boundary surfaces a to c is in each case in 1B shown. The recorded reference marks 126 are with reference symbols 128 designated. The evaluation unit 120 can be set up, the light spots in the images of the image recording devices 118 to identify. For example, the evaluation unit 120 be set up to carry out at least one image processing algorithm, in particular an algorithm for recognizing features. The image processing algorithm can include filtering and / or background reduction and / or transformation. The image processing algorithm can include selecting a region of interest (ROI).

The evaluation unit 120 can be set up to emit a radiation characteristic of the surface of the test object 112 to determine light beams reflected in response to the lighting pattern and striking the boundary surfaces and by comparing the determined emission characteristic with a previously known emission characteristic of the respective lighting device 116 the information about the surface of the test object 112 to determine. The evaluation unit 120 can, if the radiation characteristics of the lighting devices are known 116 , be set up to reconstruct from the images which of the rays from the surface of the test object 112 were reflected and which passed the test item. The evaluation unit 120 can be set up to reconstruct from the images which one Lighting device 116 a recorded inspection characteristic was generated. From the distortions of the light beam distributions, in particular a spatial directional distribution of the beams that has changed compared to the known emission characteristics, the information about the surface of the test object can be accessed 112 getting closed.

From the lighting fixtures 116 generated light rays can on the test object 112 walk past and from one of the respective lighting fixtures 116 opposite imaging device 118 be included. For example, on the test item 112 passing light rays on an opposite boundary surface 124 to meet. One behind the boundary 124 arranged image pickup device 118 can, as described above, take an image of the incident light rays. The evaluation unit 120 can be set up to identify areas of the illumination pattern, in particular emission intervals, from the recorded image, which areas are from the test object 112 were not shaded, and from these areas the information about the surface of the test object 112 to determine. For example, the evaluation unit 120 be set up to keep the information about the surface of the test specimen 112 to be determined by a shadow casting method.

As an alternative or in addition, the images of the test patterns can include stereo images, which are used for stereo reconstruction of the test object 112 can be used. In particular, the device 110 be set up to carry out a so-called “refractive stereo” process. A measurement setup for such a procedure is in 4th shown. The device 110 can be set up a geometry of a light-refracting transparent object, that is to say of the test object 112 to calculate back by recording the changes in direction of directed rays. For example, the test item 112 comprise a translucent material. In particular, the test object 112 have a refractive index different from air. The lighting device 116 can be set up to generate at least one directed light beam, in particular a multiplicity of directed light beams. If one of the light rays falls on the surface of the test object 112 becomes part of the surface of the test object 112 reflected and / or scattered and can be evaluated by deflectometry. This proportion can be small. For example, the test item 112 have an anti-reflective surface. The through the material of the test object 112 The transmitted portion can be from at least one of the image recording devices 118 are recorded. The evaluation unit 120 can be set up to determine a change in direction of the light beams and from this the information about the surface of the test object 112 to determine. In the embodiment shown here, two of the lighting devices 116 from the majority, in particular more than three, of lighting devices 116 be arranged at spatially different locations, for example axially spaced, and the test object 112 Illuminate from at least two spatial directions. For example, a first lighting device 116 have the coordinates x, y and z1 and the second lighting device 116 the coordinates x, y and z2. The lighting fixtures 116 can in particular lie in one plane. For example, the device 110 at least two lighting devices 116 per boundary surface 124 have which on the boundary surfaces 124 are arranged distributed, for example evenly distributed. The device 110 can have at least two image capture devices 118 which are designed to receive the transmitted light beams at at least two spatially different positions. The evaluation unit 120 can be set up to determine changes in direction of the light beams from the recorded images and, from this, to determine the information about the surface of the test object 112 to determine. In particular, checkerboard patterns or other regular patterns can be used. Such patterns can be advantageous because the specific change in the recorded pattern simply provides information about the surface of the test object 112 can be determined. The result of the multitude of lighting devices 116 existing manifold directionally structured bundles can thus be used to determine the information about the surface of the test object 112 can be used.

The device 110 can be set up to the test specimen 112 to move along at least one axis, in particular relative to the boundary surfaces.

2A shows an embodiment in which the information about the surface of the test piece 112 is determined photogrammetrically. This method is particularly suitable for measuring a non-reflective surface of the test object 112 . The evaluation unit 120 can be set up to evaluate the images of the test patterns by at least one triangulation method. The imaging devices 118 can be set up to stick to the surface of the test specimen 112 test patterns scattered in response to the illumination pattern from at least three triangulation perspectives. For example, the device 110 four imaging devices 118 exhibit. The measuring cell 122 can have four corners. One image recording device each 118 can at one corner of the measuring cell 122 be arranged. An image recording from four triangulation perspectives TP1, TP2, TP3 and TP4 can thus be possible. The Imaging devices 118 can have cameras with working distance-independent distortion.

2 B shows of the image pickup devices 118 of 1A resulting recorded test samples, each for the triangulation perspectives TP1, TP2, TP3 and TP4. The evaluation unit 120 can be set up to photogrammetrically evaluate the recorded test pattern and the information about the surface of the test object 112 to determine. The images can be used to determine spatial coordinates of the surface of the test object using known photogrammetric methods 112 are closed at which the identifiable light rays, for example pattern sections, were scattered. In this embodiment, the device 110 preferably more than three lighting devices 116 exhibit. In the event that a coding depth of the identification information for a large number of lighting devices 116 becomes too large, the lighting devices can be switched on sequentially 116 be evaded.

For a photogrammetric determination of the information about the surface of the test object, the boundary surfaces 124 the measuring cell 122 be preferably designed as a Lambert spreader. For example, the boundary surfaces 124 be made of Spectralon ™. Alternatively or additionally, the triangulation perspectives can each be designed with such a large field angle that in each case the entire opposing boundary surface 124 can be captured. Alternatively or additionally, the image recording devices 118 be designed with multi-aperture systems for different working distances. In this embodiment, too, the device 110 preferably more than three lighting devices 116 exhibit. The lighting fixtures 116 can be designed using fiber endoscopic technology, in particular to preserve the usable area. As stated above, at least one reference mark 126 on each of the boundary surfaces 124 be provided. The lighting devices are preferred 116 in the reference marks 126 arranged so that they effectively do not take up any floor space. With a large number of lighting devices 116 and imaging devices 118 can also be used with systems with small field angles. The number of the image capture devices 118 depth of focus and field angles can be selected as a function of its parameters, working distances, since these determine which volume sections within the measuring cell can be imaged sharply, in particular sufficiently sharply, by the respective camera. In addition, the number of cameras required and their arrangement can depend on how many sufficiently sharp camera perspectives are required for how many and / or which measuring cell volume segments.

The device 110 can be set up to measure the roughness on the surface of the test specimen 112 perform. Especially when installing a large number of structured lighting devices 116 which preferably generate beam bundles that are preferably directionally distributed but approximately collimated and, in particular, with respect to beam parameters and direction known, a roughness measurement technique can also be implemented. The large number of lighting devices 116 allows a wide variety of light direction, light wavelength and beam cross-section combinations for illuminating surface segments of the test object 112 . From a combination of deflectometric images obtained by reflecting the structured light on the surface of the test object 112 arise on the known boundary surface designed as a Lambert scatterer, and the photogrammetric images, which by scattering similar and also known rays directly on the surface of the test object 112 a measurement of the bidirectional reflectance distribution function (BRDF) of segments of the surface of the test object can arise 112 to be possible.

As in 3 shown, the measuring cell can 122 have more than three boundary surfaces. For example, the measuring cell 122 be designed as a matrix and / or backdrop, which the test object 112 completely or partially surrounds. For example, the matrix and / or backdrop can represent the test item 112 Cover completely in an x, y-plane and partially in a z-direction. For example, the matrix and / or backdrop can be variable, in particular on the test object 112 customizable. The matrix and / or backdrop can have a plurality of Lambert-scattering boundary surfaces 124 have which the lighting devices 116 who have favourited Imaging Devices 118 and the reference marks 126 exhibit. The boundary surfaces 124 can be configured to be actuatable, with a spacing and / or orientation of the boundary surfaces 124 to the test item 112 can be adjustable by actuators. For example, a connection with a length l _{i can be} provided between a delimiting surface and an actuator, i indicating the number of actuators. In 3 two lengths l _i and l ₂ for two actuator positions P ₁ and P _{2 are} shown by way of example. By changing the length l _i , a distance and / or orientation of the boundary surfaces to the test object can be achieved 112 be adjustable. Since the actuators have spatially fixed and known positions Pi, a clear statement about the position and direction of the triangulation perspectives can be generated _{via the length l i.} A so-called extrinsic calibration of the camera system can thus be carried out. This can be done with the aid of the intrinsic calibrations and reference to the reference marks 126 be stabilized. The lengths li can also be adapted and / or varied during operation, for example around a contour of the test object 112 to follow and / or to optimize optical conditions for the different measuring principles. By moving the matrix and / or the backdrop, and thus the position of the reference marks 126 in the room, the validity of the intrinsic calibrations of the installed optics can be checked.

List of reference symbols

110

contraption

112

Test item

114

Light source

116

Lighting device

118

Image capture device

120

Evaluation unit

122

Measuring cell

124

Boundary surface

126

Reference mark

128

recorded reference mark

Claims (10)

Device (110) for the dimensional measurement of a test object (112), wherein the device (110) has a plurality of lighting devices (116) which are each set up to generate at least one lighting pattern and a surface of the test object (112) structured with the lighting pattern to illuminate, wherein the lighting devices (116) are arranged relative to one another in such a way that the test object (112) is illuminated from at least two spatial directions, the lighting patterns of the respective generating lighting device (116) being clearly assignable, the device (110) having a plurality of image recording devices (118), the image recording devices (118) being set up to each record at least one image of test patterns generated in response to the illumination of the illumination pattern from the surface of the test object (112), the recorded test patterns each having a plurality of inspection characteristics onwe The device (110) has at least one evaluation unit (120), the evaluation unit (120) being set up to assign the test features to the respective lighting device (116), the evaluation unit (120) being set up to provide information about the Determine the surface of the test specimen (112) by evaluating the assigned test features. Device (110) according to the preceding claim, wherein the images of the test patterns are deflectometric and / or photogrammetric and / or strip projections and / or line projections and / or pattern projections. Device (110) according to one of the preceding claims, wherein the lighting patterns each have at least one piece of identification information, the identification information being a known local group and / or an ID-encoding subpattern and / or a wavelength and / or a switch-on time or switch-on time interval. Device (110) according to one of the preceding claims, wherein the lighting devices (116) each have at least one optical fiber, the optical fiber having at least one fiber output with refractive and / or diffractive optics. Device (110) according to one of the preceding claims, wherein the device (110) has at least one multi-walled measuring cell (122), wherein the measuring cell (122) has at least three boundary surfaces (124), the boundary surfaces (124) as partially transparent panes or as Lambert spreaders are designed. Device (110) according to one of the preceding claims, wherein the image recording devices (118) are set up to record test patterns reflected and / or scattered from the surface of the test object (112) in response to the illumination pattern, the evaluation unit (120) being set up in order to determine the information about the surface of the test specimen (112) by comparing the reflected and / or scattered test patterns with the generating lighting patterns. Device (110) according to one of the preceding claims, wherein the evaluation unit (120) is set up to identify areas of the illumination pattern from the recorded image which were not shaded by the test object (112), and from these areas the information about the surface of the test item (112) to be determined. Device (110) according to one of the preceding claims, wherein the evaluation unit (120) is set up to determine the information about the surface of the test object (112) from the recorded images using a refractive stereo method. Device (110) according to one of the preceding claims, wherein the image recording devices (118) are set up to generate test patterns from at least two scattered on the surface of the test object (112) in response to the illumination pattern Record triangulation perspectives, the evaluation unit (120) being set up to photogrammetrically evaluate the recorded test pattern and to determine the information about the surface of the test object (112). A method for the dimensional measurement of a test object (112), wherein a device (110) according to one of the preceding claims is used in the method, the method comprising the following steps: a) Generating at least one lighting pattern with a plurality of lighting devices (116) and structured lighting of a surface of the test specimen (112) with the lighting patterns and / or irradiating the test specimen with directed structured lighting, the lighting devices (116) being arranged in this way relative to one another that the test specimen (112) is illuminated from at least two spatial directions, the lighting pattern being clearly assignable to the respective generating lighting device (116); b) recording in each case at least one image of test patterns generated in response to the illumination of the illumination pattern from the surface of the test object (112) with a plurality of image recording devices (118), the recorded test patterns having a plurality of test features; c) Assigning the test features of the respective lighting device (116) with an evaluation unit (120) and determining information about the surface of the test object (112) by evaluating the assigned test features.

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