Device and method for measuring inhomogeneous surfaces by means of active laser thermography
Patent Information
- Application Number
- EP2023714654
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-03-28
- Filing Date
- 2023-03-21
- Publication Date
- 2025-02-05
AI Technical Summary
Active laser thermography measurements are compromised by inhomogeneous surfaces, such as contamination, leading to incorrect results and reduced testing efficiency due to the need for surface cleaning, which affects the testing machine's output and cycle times.
A device with a shading mechanism that adjusts the measuring range to exclude defect-causing areas, using mechanical movements, laser optics, mirror systems, and apertures, allowing for partial masking of the measuring area to prevent error-causing surfaces from being included in the measurement.
This approach reduces measurement errors, increases testing speed, and enhances output by accelerating the measurement process while maintaining accurate evaluation of the test features, even on contaminated surfaces.
Smart Images
Figure 1.1
Abstract
Description
[0001] Device and method for measuring inhomogeneous surfaces using active laser thermography
[0002] The present invention relates to a device for measuring inhomogeneous surfaces by means of active laser thermography according to the preamble of claim 1, as well as to a method for measuring inhomogeneous surfaces by means of active laser thermography according to the preamble of claim 6.
[0003] Test specimens are tested using active laser thermography. However, this measurement method is affected by inhomogeneous surfaces with regard to their absorption and emission levels of electromagnetic waves. Typically, this refers to contamination on the test surface, usually caused by previous processes. This can lead to inaccurate measurements due to problematic surfaces. Once contaminated, retesting is only possible by prior cleaning of the test surfaces. However, this negatively impacts the performance of the testing machine.
[0004] This is where the present invention comes in and sets itself the task of proposing an improved device for measuring inhomogeneous surfaces using active laser thermography, in particular a device that eliminates or at least mitigates the problems outlined above. In particular, a device for measuring inhomogeneous surfaces using active laser thermography is proposed that avoids or at least mitigates measurement errors and / or enables higher output or shorter measurement cycle times.
[0005] According to the invention, this object is achieved by a device having the characterizing features of claim 1. The fact that the observation device B is further configured to detect defect-causing surfaces on the test surface, wherein the device comprises a shading device A configured to change the measuring area such that a new measuring area is created while excluding the defect-causing surface, allows the disadvantages outlined above to be overcome or at least mitigated. By manipulating the measuring area, particularly with regard to size, geometry, position, etc., the defect-causing areas can be excluded from the measurement. These excluded areas are not considered for further evaluation.The manipulation of the measuring range can be achieved by mechanical movement of the probe, spot-varying laser optics, mirror systems and / or apertures.
[0006] An increase in inspection speed and achievable output can also be achieved. Since the measurement time is determined by the component-specific measurement frequency, an increase in performance can be expected, especially through the acceleration or replacement of manipulation processes. Partial masking of the measurement area is considered acceptable if the area still to be evaluated is sufficiently large to allow for meaningful evaluation of the features to be tested.
[0007] Further advantageous embodiments of the proposed invention emerge in particular from the features of the subclaims. The subject matter and features of the various claims can, in principle, be combined with one another in any desired way.
[0008] In an advantageous embodiment of the invention, it can be provided that the observation device comprises an observation means or an observation means and a semi-transparent mirror.
[0009] In a further advantageous embodiment of the invention, it can be provided that the observation means comprises a thermal imaging camera or is designed as a thermal imaging camera.
[0010] In a further advantageous embodiment of the invention, it can be provided that the shading device comprises a first movable mirror and a second movable mirror.
[0011] In a further advantageous embodiment of the invention, it can be provided that the shading device comprises a first diaphragm plate with a diaphragm plate drive, and a second diaphragm plate with a diaphragm plate drive.
[0012] A further object of the present invention is to propose an advantageous method for measuring inhomogeneous surfaces by means of active laser thermography with a device according to the invention.
[0013] According to the invention, this object is achieved by a method having the characterizing features of claim 6. Further advantageous embodiments of the proposed invention emerge in particular from the features of the subclaims. The subject matter or features of the various claims can, in principle, be combined with one another in any desired manner.
[0014] Further features and advantages of the present invention will become clear from the following description of preferred embodiments with reference to the accompanying drawings.
[0015] Fig. 1 shows a device according to the invention in a first embodiment;
[0016] Fig. 2 shows a device according to the invention in a first embodiment.
[0017] The following reference symbols are used in the figures:
[0018] A shading device
[0019] B Observation facility
[0020] 1 Laser source / laser optics
[0021] 2 laser beam
[0022] 3 means of observation
[0023] 4 mirrors
[0024] 5 (first) movable mirror
[0025] 6 (second) movable mirror
[0026] 7 Working area / test surface
[0027] 8 Original measuring range
[0028] 9 Error-causing surface
[0029] 10 Newly created measuring range
[0030] 11 (first) aperture plate
[0031] 12 Aperture disc drive for first aperture disc
[0032] 13 (second) aperture plate
[0033] 14 Aperture disk drive for the second aperture disk. Features and details described in connection with a method naturally also apply in connection with the device according to the invention, and vice versa, so that the disclosure of the individual aspects of the invention always refers to each other. Furthermore, a method according to the invention that may be described can be carried out with the device according to the invention.
[0034] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a" and "an" and "the" are intended to include the plural forms unless the context clearly indicates otherwise. It will also be understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of the recited features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed elements.
[0035] First, reference is made to Fig. 1.
[0036] A device for measuring inhomogeneous surfaces by means of active laser thermography essentially comprises a laser beam source or laser optics 1 which emits a laser beam 2, an observation device B and a shading device A.
[0037] The observation device B may comprise an observation means 3 or an observation means 3 and a mirror 4.
[0038] The observation device 3 may in particular be a thermal imaging camera.
[0039] The shading device A may comprise a first movable mirror 5 and a second movable mirror 6.
[0040] Further aspects of the present invention will become clear from the following description of a method for measuring inhomogeneous surfaces using active laser thermography, using the device for measuring inhomogeneous surfaces using active laser thermography. It is understood that only a few selected method steps are presented here, as they are helpful for understanding the method according to the invention. The method may include further steps or intermediate steps known to those skilled in the art.
[0041] Laser beam 1 emerges from laser source 1 with a variable laser spot and is deflected by movable mirrors 5 and 6. The reflected beams impinge on a working area 7. A measuring area 8 is irradiated and simultaneously observed by observation device B. Observation can be performed via observation device 3 and semi-transparent mirror 4 along the beam path, or independently of the mirror system, i.e., only with observation device 3. An error-causing surface 9 is located in the measuring area 8.
[0042] The observation device B, in particular the observation means 3, detects the defect-causing surface 9, in particular contamination. The information can be transmitted to a suitable data processing system, which in turn can control the shading device A. A personal computer running suitable image processing algorithms can be used as the data processing system.
[0043] The measuring area 8 is shifted, in particular by changing the laser beam width and adjusting the mirrors 5 and 6. The newly created measuring area 10 can be combined by taking several images.
[0044] Fig. 2 shows an alternative embodiment of the device according to the invention.
[0045] The alternative embodiment of the device for measuring inhomogeneous surfaces using active laser thermography also includes a laser optics 1 from which a laser beam 2 emerges. The shading device A here essentially comprises a first diaphragm disk 11 with a diaphragm disk drive 12, as well as a second diaphragm disk 13 with a diaphragm disk drive 14.
[0046] Furthermore, an alternative embodiment of the device according to the invention also comprises an observation device B comprising an observation means 3. Further aspects of the present invention will become clear from the following description of a method for measuring inhomogeneous surfaces using active laser thermography using the device for measuring inhomogeneous surfaces using active laser thermography. It is understood that only a few selected method steps are presented here, as they are helpful for understanding the method according to the invention. The method may comprise further steps or intermediate steps known to those skilled in the art.
[0047] A laser beam 2 emerges from a laser source 1 and strikes apertured screens 3 and 4. The resulting laser spot strikes the test surface 7. This process is observed using the observation device B, specifically the observation device 3. A defect-causing surface is located in the measurement area. The screen 3 or 4 is adjusted so that the resulting glare shades the defect-causing areas.
[0048] With regard to the design of the observation device B, in particular the observation means 3, with regard to the detection and evaluation of defect-causing surfaces, reference can be made to the above statements.
[0049] It is evident that the embodiments are based on the basic idea according to the invention to propose a device for measuring inhomogeneous surfaces by means of active laser thermography, comprising the laser optics 1 which can emit a laser beam 2 onto a test surface to form a measuring area, and an observation device B for thermographic observation of the test surface, which is characterized in that the observation device B is further configured to detect defect-causing surfaces on the test surface, wherein the device comprises a shading device A which is configured to change the measuring area in such a way that a new measuring area is created while excluding the defect-causing surface.
Claims
Claims 1. Device for measuring inhomogeneous surfaces using active laser thermography, comprising a laser source (1) that can emit a laser beam (2) onto a test surface (7) to form a measuring area (8), and an observation device (B) for thermographic observation of the test surface (7), characterized in that - the observation device (B) is further equipped to detect fault-causing surfaces (9) on the test surface (7), wherein - the device comprises a shading device (A) configured to change the measuring area (8) such that a new measuring area (10) is created, excluding the error-causing surface (9). Device according to claim 1, characterized in that the observation device comprises an observation means (3) or an observation means (3) and a semi-transparent mirror (4). Device according to at least one of the preceding claims, characterized in that the observation means (3) comprises a thermal imaging camera or is configured as a thermal imaging camera. Device according to at least one of the preceding claims, characterized in that the shading device (A) comprises a first movable mirror (5) and a second movable mirror (6).Device according to at least one of the preceding claims, characterized in that the shading device (A) comprises a first aperture disc (11) with an aperture disc drive (12), and a second aperture disc (13) with an aperture disc drive (14). Method for measuring inhomogeneous surfaces using active laser thermography with a device according to at least one of the preceding claims, characterized by the following method steps: - Emitting a laser beam (2) onto a test surface (7) to form a measuring area (8); - thermographic observation of the test surface (7), as well as detection of defect-causing surfaces (9) on the test surface (7) by the observation device (B); - Change of the measuring range (8) by excluding a detected fault-causing surface (9) by the shading device A; - Continuation of the measurement without the error-causing surface (9) in a newly created measuring area (10). Method according to claim 6, characterized in that the change of the measuring area (8) is effected by shifting the measuring area, namely by changing the laser beam width and adjusting the mirrors (5 and 6). Method according to at least one of the preceding claims, characterized in that the change of the measuring area (8) is effected by adjusting the aperture disk (3 and / or 4) so that the resulting glare effect shadows the error-causing areas (9). Method according to at least one of the preceding claims, characterized in that the newly created measuring area (10) can be composed by taking several images.