Methods for the visual representation of test information

Abstract

Method for the visual representation of test information obtained from a test object using a non-destructive ultrasonic testing method, comprising the following process steps: - Acquisition of test information using an ultrasonic probe that is positioned or moved along a surface of the test object relative to the test object, - Acquisition of spatially resolved image data depicting the ultrasonic probe and the test object during the acquisition of the test information, - Generating user-specific information, at least based on the test information, - Displaying user-specific information in superimposition with image data or with image information derived from the spatial shape of the test object, characterized in that the superimposed display is carried out in the following manner: Top view of the ultrasonic probe or a synthetically generated symbol representing the ultrasonic probe, as well as of the surface of the test object in the state of acquiring the test information, in combination a) with a linear display symbol to visualize a main direction of sound propagation attributable to the ultrasound probe, b) with spatially resolved, user-specific information that can be displayed on the surface of the test object, which is obtained within the test object orthogonally to the surface of the test object on which the spatially resolved, user-specific information is displayed, as well as generating and displaying a cross-sectional view through the test object in which the user-specific information is displayed using false color representation in at least one of the following forms: - Ultrasound wave propagation within the test object along the depicted section through the test object, - Ultrasound wave signals projected onto the cross-sectional view of the test object, originating from a volume area of ​​the test object being traversed in projection orthogonal to the section shown, whereby the display of user-specific information takes place in real time depending on the position and orientation of the ultrasound probe relative to the test object.

Description

Technical field

[0001] The invention relates to a method for the visual representation of test information acquired from a test object using a non-destructive ultrasonic testing method, in which the test information is acquired by means of an ultrasonic transducer that is positioned or moved along a surface of the test object relative to the test object. Furthermore, spatially resolved image data are acquired from the ultrasonic transducer and the test object during the acquisition of the test information, and user-specific information is determined, at least on the basis of the test information, and displayed in superimposition with the image data or with image information derived from the spatial shape of the test object. State of the art

[0002] Non-destructive testing (NDT) techniques play a central role in quality assurance and verification and are used both during and after the manufacturing of components and structures. Potential or existing quality defects within components, such as material flaws, cracks, or other signs of material degradation, can be detected using NDT techniques without affecting the usability of the component itself.

[0003] Common NDT techniques utilize acoustic and / or electromagnetic waves to penetrate and examine three-dimensional objects, some of which are highly complex. For inspection purposes, at least one probe equipped with an ultrasonic transducer, eddy current sensor, or magnetic field sensor is guided along the object's surface in a contacting manner. Particularly in cases of objects that are difficult to access or have complex surface structures, it is necessary to use handheld, non-destructive probe arrangements, which are the main focus of the following discussion.

[0004] For example, in the case of non-destructive testing of a three-dimensional object with a handheld ultrasonic probe, the person performing the test must ensure that the probe, hereinafter referred to as NDT, covers as much of the entire surface of the object being tested as possible, and that it is held in a specific position, oriented as orthogonally as possible to the object's surface, in order to obtain reliable measurement data during the test. Undoubtedly, this presents a demanding task for the operator, especially since, with large objects that have complex surfaces, a complete measurement of the object's volume is both time-consuming and requires a high level of concentration from the operator, who must maintain the probe with the most precise spatial orientation possible.The position must be relative to the object surface. Positional deviations from an ideal measurement configuration with defined tolerances between the probe and the object surface inevitably lead to faulty and therefore unreliable measurement signals.

[0005] In addition to the requirements for the concentration of the person performing the inspection, there is also the requirement for spatially resolved measurement signal acquisition. This means that the spatial position of the NDT (Non-Destructive Testing) device must be precisely recorded during the inspection of the object in order to store the measurement signals obtained with the NDT device together with the spatial information describing the respective measurement position, for example, in the format of Cartesian coordinates. In this way, a spatially resolved data analysis of the measurement data acquired from the object being inspected can be carried out.

[0006] A measuring system and a method for the non-destructive testing of a pipeline segment using a manually operated ultrasonic measuring device are described in German patent application DE 10 2013 009 127 A1. For spatial position detection, optical markers are attached to the hand-held ultrasonic measuring device and detected using an optical 3D tracking system. The spatial coordinates of the ultrasonic measuring head acquired in this way, as well as the measurement data obtained from the pipeline segment, are combined into a single data set and made available accordingly.

[0007] In addition to conventional evaluation and display methods for interpreting measurement data acquired from a test object using an ultrasound probe, such as standard A- or B-scan displays, approaches exist to visually process the measurement data and fuse it with the immediate physiological visual impression of a person performing the measurement task or with a visual representation of the current measurement process on the test object. This involves visually superimposing the data with virtual representations. For the person performing the measurement, this method of optically superimposing the real measurement scenario with metrologically acquired and user-specific information provides an artificially generated visual impression of the physical properties of the test object's interior.

[0008] The superimposed display of the real test situation and the metrologically acquired and computer-aided evaluated and processed measurement signals can be realized on a monitor that displays a video image of the measurement scenario superimposed with computer-aided processed measurement information. Similarly, so-called VR glasses are also suitable for this purpose, which allow a person a clear view of the test object under investigation and thus of the current measurement situation, and at the same time provide synthetically processed image information based on currently acquired ultrasound time signals, adapted to the size of the real measurement scenario, in a visually perceptible manner.

[0009] Particularly in connection with medical sonographic examinations, such VR systems are used, which are able to present a doctor with a cross-sectional view through the body cross-section captured by the ultrasound probe in the form of a graphically processed B-scan when performing a sonographic examination on the human body.

[0010] German patent application DE 10 2011 089 856 A1 describes an inspection system for a test object in which local test results are projected onto a surface area of ​​the test object using a projection system. For this purpose, an amplitude A, a current time signal, and a threshold exceedance are displayed near a current measuring point, i.e., at the location of the testing tool.

[0011] Document US 2015 / 0122055A1 describes a system and a method for performing non-destructive testing on a test object using an ultrasonic transducer. The sensor signals from the transducer are fed to a computer, where they are evaluated and processed for graphical display on a monitor. The test scene, consisting of the test object and the typically handheld transducer 30, is recorded with a camera and also displayed on the monitor.

[0012] The publication DE 10 2015 211 025 A1 describes a monitoring method for checking the correct positioning of a test sensor relative to the surface of a test object to be measured.

[0013] The publication DE 10 2012 202 279 A1 discloses a marking method for the visual representation of those areas of a test object that have already been scanned and measured using a probe.

[0014] Publication US 2015 / 0 039 245 A1 explains an optical overlay of the process of non-destructive testing on a test object with virtually visible additional information, which enables the person performing the test to maneuver the probe head according to a defined test plan.

[0015] German patent application DE 24 41 768 A1 describes an ultrasonic transducer with an attached bar whose longitudinal extent indicates the main direction of ultrasonic propagation. Light sources are mounted along the length of the bar to indicate reflection events. The strength of a reflection signal can also be encoded and displayed via an additional light source array.

[0016] German patent application DE 102 59 658 A1 discloses a method for evaluating ultrasonic signals, in which a test specimen examined using an angle probe is shown in a cross-sectional view in which defect signals are displayed. The known method is an offline method suitable for subsequent data evaluation. Description of the invention

[0017] The invention is based on the objective of further developing a method for the visual representation of test information obtained from a test object using a non-destructive ultrasonic testing method and fused with the real test situation for visual perception using the superimposition method described above, in such a way as to improve the user-friendliness of such systems, particularly when examining technical test objects. Specifically, the aim is to increase the information density of the displayable test information about the testing process and, at the same time, to make its interpretation more intuitively perceptible for the system user. The goal is to achieve a qualitatively improved and faster testing procedure on a test object compared to previous techniques.

[0018] The solution to the underlying problem is specified in claims 1 and 2. Advantageously developing features of the invention are the subject of the dependent claims and can be found in the further description with reference to the exemplary embodiments.

[0019] In established sonographic examinations of technical or medical test objects, such as human subjects, ultrasound fields are typically applied perpendicular to the surface of the test object. The ultrasound signals acquired in this configuration are displayed as cross-sectional images, usually in the form of so-called B-scans. Non-destructive testing of technical test objects, for example, plate-shaped objects with a weld seam, presents particular challenges, especially with regard to correct ultrasound wave coupling into the test object, complete measurement of critical areas of the test object, error-free detection of the ultrasound waves from within the test object, and the evaluation and display of the ultrasound measurements for the purpose of an intuitively accessible assessment of the in-situ acquired data.

[0020] The proposed method for the visual representation of test information obtained from a test object using a non-destructive ultrasonic testing method comprises the following steps. An ultrasonic transducer is moved and / or positioned along the surface of the test object for the purpose of transmitting and detecting ultrasonic waves and acquiring the resulting test information. During the ultrasonic measurement, spatially resolved image data are acquired from both the ultrasonic transducer and the test object being non-destructively tested, depicting the measurement scenario. Preferably, an optical camera and / or a 3D scanner is used to capture the entire measurement scenario, i.e., at least the test object and the ultrasonic transducer as it is moved or positioned relative to the test object.

[0021] At least on the basis of the ultrasonic echo time signals determined with the help of the ultrasonic probe, the so-called test information, user-specific information is generated depending on the type and purpose of the test, which is ultimately superimposed with the image data obtained from the measurement scenario or with image information derived from the spatial shape of the test object into one of the following visual representations: In a top-down view of the ultrasonic probe and the surface of the test object, a linear display symbol is generated as user-specific information during the acquisition of test information to visualize a main sound propagation direction attributable to the ultrasonic probe, with the reflection locations of the ultrasonic waves propagating within the test object being additionally marked along the linear display symbol on the test object surface and / or on the test object surface opposite it.

[0022] Ultrasonic wave coupling into the test object usually occurs at a predefined angle relative to the test object's surface, typically 30, 45, 60, 70, or 80°. Of course, other angles of incidence between 0° and 90° relative to the test object's surface are also possible.

[0023] Another visualization of the test information is achieved through a top-down view of the ultrasonic probe and the surface of the test object during the acquisition of the test information. This is combined with spatially resolved, user-specific information displayed on the test object surface. This information is presented in false colors, as alphanumeric symbols, and / or as geometric markings or bar graphs. The user-specific information, visually perceptible on the test object surface, characterizes the physical properties of the test object within those volume areas located orthogonally beneath the test object surface where each user-specific piece of information is displayed.One particularly preferred display method involves superimposing an A-scan or A-scan information along the linear display symbol that visualizes the main direction of sound propagation. In this display, the signal amplitudes of the time-resolved detected ultrasound signals are shown either as a function graph or as a histogram along the linear display symbol.

[0024] In another visualization variant, a surface area marker is generated in a top-down view of the ultrasonic probe and its surface during the acquisition of test information. Ultrasonic waves propagate along and / or below this marker within the test object. This provides the user with information about the spatial extent of the test object volume projected onto the surface and scanned by the ultrasonic probe.

[0025] In another form of visualization of test information obtained with the help of the ultrasonic probe, a cross-sectional view through the test object is generated either based on the recorded image data or on information derived from the spatial shape of the test object, into which the user-specific information is displayed using a false color representation in one of the following ways: Starting from the point of ultrasonic wave coupling or generation within the test object, the sound propagation path of the ultrasonic waves within the test object is illustrated along the depicted cross-section through the test object. It is also possible, by means of appropriate windowing, to display only partial sections or at least a partial section of the ultrasonic propagation path along the cross-section through the object.

[0026] Another alternative for displaying user-specific information overlaid with a cross-sectional view through the test object involves projecting ultrasound wave signals and / or information derived from them into the plane of the cross-sectional view through the test object, originating from a volume area of ​​the sound-permeated test object in projection orthogonal to the displayed cross-sectional plane.

[0027] The aforementioned visually perceptible presentation options offer the person performing ultrasonic testing on the test object immediate and intuitive insight into the physical properties within the object and, furthermore, the assurance that the testing process is being carried out correctly and completely. The visual representation of user-specific information, superimposed on the test object or a schematic graphic representation of the object (for example, a simulated cross-section or longitudinal section), can be customized in type and scope depending on the specific testing task at hand.

[0028] In addition to the possibility of using a monitor to superimpose user-specific information onto the image data representing the measurement scenario, 2D or 3D projection systems, for example in the form of VR glasses, are equally suitable for visually presenting the user-specific information to the person involved in the measurement task, preferably depending on the position and orientation of the ultrasound probe relative to the test object under real-time conditions.

[0029] In a further preferred embodiment, based on spatially resolved image data depicting the test object and using a test plan, at least one surface area of ​​the test object is identified that is to be examined with the ultrasonic probe. Of particular interest here are test objects that have at least one weld seam, along which the ultrasonic probe is to be guided on the surface of the probe for the purpose of weld seam inspection. In this process, at least one surface area to be examined is visually marked in a top view of the surface of the test object in a first way, for example, by color, a pattern, or a border.The person responsible for the measurement task thus receives information about the surface area of ​​the test object to be scanned and examined with the ultrasonic probe. This allows for the economical and time-optimized examination of particularly large and complex test objects. When the probe scans and measures a measurement point located within the surface area marked in the first way, the successfully measured location or area is marked in a second way, which differs from the first in terms of color and / or pattern. This area marking allows the test object to be examined completely and in the shortest possible time, as it avoids the need to repeatedly scan the same surface area with the ultrasonic probe.

[0030] The advantages and the wide variety of solutions for visualizing test information obtained from an ultrasonic testing method on a test object are explained in detail below with reference to the illustrated examples. Brief description of the invention

[0031] The invention is described below by way of example, without limiting the general concept of the invention, with reference to the drawings. The drawings show: Fig. 1 Schematic representation of the measurement setup, Fig. 2a Top view of a test scenario overlaid with user-specific information, Fig. 2b Sectional view through the test object superimposed with user-specific information, Fig. 3a Top view of the test scenario showing the volume of the test object through which the ultrasound wave propagated; bottom view: Cross-sectional view through the test object showing the ultrasound wave propagation path (A-scan), Fig. 3b top view: Top view of the test scenario showing A-scans projected onto the surface of the test object; bottom view: Sectional view through the test object showing ultrasonic wave propagation paths (A-scans) projected into the section plane. Fig. 4a-c Top view illustrations to support ultrasonic probe guidance Fig. 5a, b Top view of the test scenario with synthetic representation of user-specific test information and the ultrasonic probe, and Fig. 6 ultrasonic probes with light source Ways to implement the invention, industrial applicability

[0032] Fig. Figure 1 shows a schematic representation of components for performing an ultrasound wave-based examination on a test object 1, with a simultaneous visual representation of the test information acquired during the ultrasound wave examination. A manually operated ultrasound probe 2 is provided for performing the ultrasound wave-based examination of the test object 1. This probe can be moved and positioned freely along the surface 3 of the test object 1. The ultrasound probe 2, which can be configured as a conventional ultrasound probe with a discretely predefined angle of incidence or as a phased-array probe, is connected to a computer unit 4. The computer unit evaluates and processes the test information acquired from the test object 1 by the ultrasound probe 2, usually in the form of discrete ultrasound time signals.The recorded ultrasound time signals, which represent ultrasound wave reflection events in the form of time- and distance-resolved signal amplitudes along a predefinable ultrasound wave incident direction within the test object 1, form the basis for the generation of user-specific information, which is individually generated depending on the test task and presented visually to a person entrusted with the test task.

[0033] Additionally, an image acquisition system 5 is provided that captures the measurement or test scenario with spatial resolution. Preferably, a spatially resolved camera is suitable as the image acquisition system 5, which captures the test object 1 and the ultrasonic probe 2, which is mounted on the surface 3 of the test object 1, in a top view during the measurement procedure. The image data acquired with the aid of the image acquisition system 5 are supplied to the computer unit 4, in which the image data are fused with the user-specific information generated on the basis of the test information and visually displayed in a format adapted to each other in terms of shape and size by means of a display unit 6. The display unit 6 is in Fig. 1 a portable monitor unit which communicates with the computing unit 4 via a wireless information interface 7.

[0034] The portable monitor unit displays a live image of the surface 3 of the test object 1 with the ultrasonic probe 2 positioned on the surface 3. Additionally, the user-specific information generated by the processing unit 4 is superimposed on the portable monitor unit 7 with the image data from the image acquisition system 5 in a coded manner, preferably as a false-color display. In this way, a person responsible for the inspection task gains immediate knowledge of the internal structure of the test object 1, since the user-specific inspection information is displayed in an orientation- and movement-identical manner with the movement and orientation of the ultrasonic probe 2 on the surface 3 of the test object 1.

[0035] As an alternative to using a portable monitor unit 7, functionally equivalent or similar visualization systems can also be used, such as VR glasses, hologram displays, etc. Regardless of the technical implementation of the visual representation of the user-specific information generated on the basis of the ultrasound time signals, this information is displayed to a person entrusted with the inspection task with direct spatial reference to the test object and the ultrasound probe.

[0036] The in Fig. 1 Illustrated test object 1 is plate-shaped and has a weld seam 8 that linearly penetrates the test object 1 in length and depth, which is to be examined using the ultrasonic probe 2.

[0037] In Fig. Figure 2a shows a solution-oriented top-down view of the test scenario overlaid with user-specific information, which in this form is shown on the in Fig. The portable monitor unit 7 is illustrated in Figure 1. The ultrasonic probe 2 is positioned and shown relative to the weld seam 8 of the test object 1. The following user-specific information is superimposed on the measurement situation depicted in the top view: A circular symbol 9, indicating the exact position and orientation of the ultrasonic probe 2, is shown directly superimposed on the ultrasonic probe 2. A linear symbol 10 is illustrated to indicate the main direction of ultrasonic wave propagation, representing the sound path of the ultrasonic waves emanating from the ultrasonic probe 2 projected onto the surface of the test object 1 along the main direction of sound propagation.

[0038] The image of an A-scan A is represented in superimposition with the linear symbol 10. The representation can be seen as a function graph, as shown in... Fig. As can be seen in Figure 2a, the results can be displayed as a histogram or in false color. In both forms of representation, the detected signal amplitudes along the sound propagation path within the test object 1 are clearly shown on the surface 3 of the test object.

[0039] In addition to the linear symbol 10, dot markings visually highlight the locations where the ultrasonic waves emanating from the ultrasonic probe 2 are reflected on the top and bottom of the test object 1.

[0040] Additionally, along the linear symbol 10, the distance to the ultrasonic probe 2 is indicated by a marker 12 below which a significant reflection event occurs within the test object 1. In addition to the local marker 12, the reflectance of the reflection event and the distance to the ultrasonic probe 2 can optionally be represented numerically. In the case of the Fig. In the test situation 2a illustrated, there is a reflection event 3 mm along the main direction of sound propagation measured from the ultrasonic probe 2, at which 70% of the sound energy is reflected.

[0041] In Fig. Figure 2b illustrates a further, supplementary representation in the form of a cross-sectional view through the test object 1. The cross-sectional view is based on geometric information about the test object 1, for example, the plate thickness of the test object 1, which has the weld seam 8. In the cross-sectional view, a symbol 13 representing the ultrasonic probe 2 is shown schematically. Starting from the symbolized ultrasonic probe 13, the sound path of an ultrasonic wave 14 is shown schematically, which is reflected in the form of a zigzag line between the top surface 30 and the bottom surface 3u of the test object 1 during its propagation.

[0042] Furthermore, the reflectance along the zigzag line is displayed in false-color code. At the location of a reflection event, which occurs in Fig. 2a, indicated by marking 12 in the top view, a higher reflectance is visually represented in the corresponding area 12' by a lighter color. In the case of the Fig. 2b, the reflection event is therefore located near the top surface 3o within the test object 1.

[0043] Furthermore, according to the presentation Fig. As can be seen from Figure 2b, the ultrasonic waves are directed into the plate-shaped test object 1 at an angle of incidence 15 that can be set by the ultrasonic probe. The angle of incidence 15 can be selected individually, preferably with the aid of a phased-array ultrasonic probe.

[0044] Fig. Figure 3a, the upper illustration, shows a top view D of the test object 1 and the ultrasonic probe 2, whose position is indicated by the circular symbol 9. Using a false-color representation, where the brightness level represents the reflectance, the area on the surface 3 of the test object 1 over which the ultrasonic probe 2 has already been manually moved is color-coded. Thus, in addition to the current position of the ultrasonic probe 2, the user-specific information is provided by the circular symbol 9 in the case of... Fig. Figure 3a shows an overview of the reflectivity within the already measured test object volume, in orthogonal projection to the surface 3 of the test object 1. Using false-color representation, surface areas where ultrasound waves are strongly reflected within the test object are highlighted in light colors. Conversely, those surface areas where the ultrasound waves can propagate unhindered within the test object and are therefore only reflected at the underside of the test object are marked with dark colors.

[0045] Under the in Fig. Figure 3a shows a top view D, and a sectional view S illustrates the ultrasound wave propagation at the current position of the ultrasound probe along the main direction of sound propagation in false color. The false color representation of the ultrasound wave, which forms a zigzag pattern due to reflection events occurring on the top and bottom surfaces, makes locally occurring reflection events within the test object visually perceptible with high contrast.

[0046] In Fig. Figure 3b shows a top view D of the test object 1 including the ultrasonic probe 2 positioned on it. In contrast to the image representation in Fig. 3a D, in which the color-coded reflectance of volume regions directly below the surface 3 of the test object 1 is projected onto the surface, is shown in Fig. Figure 3b shows the reflectance of an ultrasonic wave projected onto surface 3, propagating in the main direction of sound propagation, comparable to an A-scan. By longitudinally moving the ultrasonic probe along the weld seam 8, an A-scan is performed at each point of sound penetration using the ultrasonic probe 2, which is oriented largely orthogonally to the weld seam. The sum of all A-scans is shown in the top view in Fig. Figure 3b D is shown. In the section view S shown directly below, a superposition of all individual zigzag-shaped ultrasound wave paths orthogonal to the section plane can be seen, each represented by a false-color coding that reflects the respective reflectance along the ultrasound wave paths (A-scans).

[0047] In Fig. Figure 4a shows a top view of the surface 3 of a test object 1 with a weld 8, next to which the ultrasonic probe 2 is positioned on the surface 3 of the test object 1, its location and position being further characterized by a synthetically generated symbol 9. Fig. 4b additionally shows a color-coded area 16, which schematically replicates the size and shape of the weld seam 8.

[0048] In Fig. In section 4c, the areas 17 to the left and right of the weld 8 are marked, within which the person performing the inspection must move the ultrasonic probe 2. The marked areas 17 change their preferably color coding as soon as the ultrasonic probe 2 has passed over a point within the areas 17 and successfully measured. In this way, the person performing the inspection immediately identifies the areas to be measured and also receives information about which areas have already been successfully measured. This avoids duplicate measurements.

[0049] The shape and size of the marked surface areas to be measured 17 depend on predefinable parameters, such as weld geometry, test object thickness, ultrasonic probe type, either conventional angled transducer with predefined angle of incidence or phased-array probe, etc.

[0050] For the test procedure, the ultrasonic probe must be moved across the surface of the test object 1 at as uniform a speed as possible to ensure a consistent distance between adjacent measuring points. To provide the operator with continuous visual or audible feedback, thus ensuring the ultrasonic measurement is controlled and successful, additional information, preferably color-coded, is displayed on the screen. This information can be, for example, a clearly marked, visually perceptible symbol that will appear as an alarm if the ultrasonic probe is handled incorrectly or improperly.A successful measurement is characterized by the correct positioning of the ultrasonic probe on the surface of the test object for ultrasound coupling, and by the reflection of the ultrasonic waves propagating within the probe, at least at the back of the test object. The reflected ultrasonic wave components are detected by the ultrasonic probe and fed to the processing unit for further evaluation and storage. If all the aforementioned criteria required for a successful ultrasonic measurement are met, a positive feedback signal can be provided to the person performing the test, either visually or, if necessary, audibly, using the display technology. However, if one of the aforementioned criteria is not met, the person can be informed accordingly with a visually perceptible alarm signal.

[0051] Another embodiment for displaying user-specific information signals unforeseen reflection events within the test object 1 to the person responsible for the test task. This occurs as soon as the normally usual back wall echo signal is superimposed or shadowed by an ultrasonic event located in front of the back wall of the test object in the direction of ultrasonic propagation. Fig. Figure 5a shows a top view of a plate-shaped test object 1, within whose plate-shaped volume an elongated incompleteness is contained. This incompleteness is to be detected and displayed by manually scanning the surface 3 of the test object 1 with the ultrasonic probe 2. The false-color representation 18, depicting the reflectance of the areas within the test object 1, is shown in a top view both over the surface 3 of the test object 1 and over the hand-held ultrasonic probe 2, so that neither the ultrasonic probe 3 nor the hand 20, which contains user-specific information encoded in the false-color representation 18, are obscured. Furthermore, the ultrasonic probe 2 is marked as a synthetic symbol 9, which is also concentrically surrounded by another ring-shaped marking symbol 20. The ring-shaped marking symbol 20 is, for example,Marked in green, it informs the person responsible for the test that all test criteria, as mentioned above, are met and that the ultrasonic waves are reflected at the back wall of the test object, i.e., there are no imperfections along the ultrasonic path between the ultrasonic wave probe and the probe back wall.

[0052] Furthermore, the person responsible for the inspection task is presented with the ultrasonic wave measurement distance and the reflectance at the back of the test object in the form of numerical values. In the illustrated case, the ultrasonic waves propagate from the location of the ultrasonic probe 2 to the back of the test object over a distance of 11 mm. At the back of the test object, the ultrasonic waves are reflected back with a reflectance of 30%.

[0053] In contrast, in Fig. Figure 5b illustrates the case in which the handheld ultrasonic probe is positioned on a surface area of ​​the test object 1 where the ultrasonic waves emitted by the ultrasonic probe 2 are already strongly reflected at a distance of 7 mm with a reflectance of 50%. In this case, the ring-shaped marker symbol 20 appears red and, as an alarm color, alerts the person responsible for the inspection task to a detected material defect within the test object 1.

[0054] As an alternative to the synthetic generation of the ring-shaped marking symbol 20, which appear differently in each case, in a preferred embodiment, see Fig.6, the ultrasonic probe 2 is combined with an additional light source 21, which can appear visually in different ways, e.g., through a different light pattern, continuously or flashing, or through different colors. Multicolor LEDs are particularly suitable for this purpose. Reference symbol list 1 test object 2 ultrasound probes 3 Surface of the test object 30 Top 3u underside 4 Calculation unit 5 Image acquisition system 6 Display unit 7 wireless communication interface 8 weld seam 9 circular symbol 10 linear symbol 11 reflection points on the test specimen surface 12 Mark 13 Symbol 14 Ultrasound wave 15 sound angles 16 weld area 17 marked surface area 18 False color representation 19 Hand 20 ring-shaped marking symbol 21 light bulbs A A-Scan D Top view of the test object S Sectional view through the test object

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