Method and device for detecting defects in a measurement object

Abstract

The invention relates to a device for detecting defects in a measurement object (1), comprising a radiation source (2) for generating measurement radiation, a measurement holder for arranging the measurement object (1) on or in the measurement holder, and a detector (3) for the spatially resolved measurement of measurement radiation, wherein the detector (3) is arranged and designed to interact with the measurement holder so as to detect measurement radiation for a plurality of spatially different measurement points within a measurement region (4) on a measurement side of the measurement object when the measurement object (1) is arranged on or in the measurement holder. It is essential that the radiation source (2) is arranged and designed to interact with the measurement holder in order to apply the measurement radiation to a coupling-in region (8) of the surface of the measurement object (1) such that the measurement radiation enters the measurement object (1) within the coupling-in region (8), wherein the coupling-in region (8) is arranged outside the measurement region (4) and outside a measurement rear region which is opposite the measurement region (4) and arranged on the measurement rear side. The invention also relates to a method for detecting defects in a measurement object.

Description

[0001] title

[0002] Method and device for detecting defects in a measured object

[0003] Description

[0004] The invention relates to a method for detecting defects in a measurement object according to claim 1 and a device for detecting defects in a measurement object according to claim 12.

[0005] It is known that to detect defects such as the presence of foreign bodies in a test object, the object is exposed to measurement radiation from a radiation source. Using a detector, such as a CCD camera, a spatially resolved measurement of the measurement radiation is performed for a multitude of differently located measurement points within a measurement range on the surface of the test object. Typically, foreign bodies on the surface cause light scattering, resulting in a difference in the intensity of the measurement radiation compared to points without foreign bodies, thus enabling the detection and location of the foreign bodies.

[0006] Such methods for detecting foreign bodies are used in many technical fields to analyze the surfaces of objects being measured, especially planar objects such as films.

[0007] The present invention is based on the objective of providing a method and a device for detecting defects in a measuring object, so that defects located within the measuring object can also be detected within a short detection time.

[0008] This problem is solved by a method for detecting defects in a measurement object according to claim 1 and by a device for detecting defects in a measurement object according to claim 12. Advantageous embodiments are found in the dependent claims. The method according to the invention is preferably carried out using the device according to the invention, in particular an advantageous embodiment thereof.

[0009] 34912-P-WO Di / co 07.10.2025. The device according to the invention is preferably designed for carrying out the method according to the invention, in particular a preferred embodiment thereof.

[0010] Defect detection takes place on a measuring side of the object being measured. The object thus has a measuring side and a measuring back side opposite the measuring side. Between the measuring side and the measuring back side, an edge region is arranged adjacent to both, which has at least one edge. The edge region therefore has one or more boundary surfaces adjacent to both the measuring side and the measuring back side. The object being measured can have a circumferential edge region, in particular an edge region with four edge sides.

[0011] The inventive method for detecting defects in a measurement object comprises the process steps of providing the measurement object with a measuring side and a measuring back side opposite the measuring side and an edge region adjacent to the measuring side and the measuring back side with at least one edge side,

[0012] The measurement of the object being measured involves applying measurement radiation from a radiation source to the object being measured and capturing measurement radiation for a plurality of different measuring points located within a measuring range using a detector, wherein the measuring range is arranged on the measuring side.

[0013] It is essential that a coupling area on the surface of the object being measured is exposed to the measurement radiation, so that the measurement radiation enters the object being measured within the coupling area, wherein the coupling area is arranged outside the measurement area and is located outside a measurement rear area opposite the measurement area, arranged on the rear side of the object being measured.

[0014] The method according to the invention thus differs from previously known methods in that the measurement radiation enters the object being measured within a coupling area, wherein the coupling area is arranged outside the measurement area. The detection of defects therefore does not occur due to a difference in surface reflection.

[0015] 34912-P-WO Di / co 07.10.2025 The measurement object is exposed to radiation when its surface is exposed within the measurement area, as is the case, for example, with a known photographic imaging process and illumination of the object with a light source. By coupling the measurement radiation within a coupling area outside the measurement area, essentially the detection of measurement radiation that emerges from the measurement object within the measurement area and strikes the detector is achieved. The method according to the invention thus differs from previously known methods in that the measurement radiation propagates within the measurement object from a coupling area separate from the measurement area to a measurement volume, wherein the measurement volume is arranged between the measurement area and the measurement back area.This avoids the disadvantages of measuring radiation striking the detector directly from the radiation source or via direct reflection from an external surface, particularly from the surface of the object within the measuring area. Detecting measuring radiation that escapes from within the object due to scattering by defects such as foreign bodies or trapped gases within the measuring area and strikes the detector enables higher accuracy and / or faster defect detection. In particular, the inventive method also detects defects that do not lead to a change in the external reflection at the surface of the object within the measuring area, but merely cause a deflection and / or scattering of the measuring light within the object.

[0016] The method according to the invention thus differs from known transmitted light methods, such as transmitted light microscopy. In such methods, the measurement radiation is coupled in via the measurement back area. In the present method, however, the coupling area is located outside the measurement back area. In transmitted light methods, an object is detected due to the reduction of the measurement radiation passing through the object. As explained above, in contrast, in the method according to the invention, no or only a negligible amount of measurement radiation reaches the detector directly or after external reflection from a surface of the object. In the method according to the invention, a defect is therefore advantageously detected and localized by an increased intensity of the measurement radiation compared to areas without defects.

[0017] 34912-P-WO Di / co 07.10.2025 The invention enables high sensitivity even for small defects in the membrane, despite a limited spatial resolution of the detector. It is sufficient to detect the outgoing measurement radiation. This is particularly advantageous when the emitted radiation is detected over the entire area or substantially over the entire area of ​​the measurement range, in contrast to a scanning method that has unmeasured areas between the measurement points (undersampling).

[0018] It is therefore advantageous that, in the method according to the invention, the measurement is performed simultaneously for all measuring points. In imaging methods, the measurement data are typically acquired sequentially within a short time. The term "simultaneous" thus also includes the sequential acquisition of the measurement data for the measuring points within the technically necessary time span, preferably less than 0.5 s, and in particular less than 0.1 s.

[0019] In an advantageous embodiment, the coupling area is arranged at the edge of the object being measured. This offers the advantage of avoiding or at least reducing the impact of measurement radiation on the detector that is reflected at the edge and not coupled in. Furthermore, when measuring during transport of the object along a straight transport direction parallel to an edge, the radiation source can be easily positioned laterally next to the object without obstructing its transport.

[0020] In an advantageous embodiment, the coupling area is arranged on the measuring side or on the rear side, preferably on the measuring side. This is particularly advantageous when the object being measured has a flat geometry, such as films or plates, especially glass plates. Due to their small thickness, the edge has a correspondingly small height, so that illuminating the edge when the coupling area is arranged there requires high local precision. Furthermore, movement of the object perpendicular to the measuring area, for example due to inaccuracies or external influences during transport, can prevent the coupling of the measurement radiation at the edge or at least significantly reduce its intensity.

[0021] 34912-P-WO Tue / co 07.10.2025 It is therefore advantageous for the coupling area to be arranged on the measuring side or on the rear side of the measuring unit. A simple design is achieved by arranging the coupling area on the measuring side where the measuring unit is also located.

[0022] When arranging the coupling area on the measuring side or on the measuring rear side, it is advantageous that the object being measured is arranged with at least one bend, so that a normal vector of the measuring area is not parallel to a normal vector of the coupling area, in particular that the normal vector of the measuring area to the normal vector of the coupling area has an angle greater than 5°, in particular greater than 10°, preferably greater than 20° and / or that the normal vector of the measuring area to the normal vector of the coupling area has an angle less than 90°, in particular greater than 70°, preferably less than 50°.

[0023] This offers the advantage that any measurement radiation reflected from the surface of the object being measured in the coupling area does not, or only to a lesser extent, lead to this reflected measurement radiation hitting the detector due to the inclination of the coupling area relative to the measuring area.

[0024] Arranging a measurement object with a bend is particularly advantageous when using the inventive method for detecting defects in flexible measurement objects, especially films as the measurement object.

[0025] It is particularly advantageous that the bending of the object being measured occurs at a bending element, and that the bending element incorporates the radiation source. In this advantageous design, the radiation is applied to the object on the side facing the bending element. This allows for a simple instrument design. It is especially advantageous that the bending element is located on the rear side of the object being measured. This prevents the direct coupling of measurement radiation into the detector.

[0026] 34912-P-WO Di / co 07.10.2025 The method according to the invention is therefore particularly suitable for the detection of defects in flexible measuring objects, especially films.

[0027] Advantageously, the measurement radiation is coupled into the object at the coupling area in such a way that, without scattering influence from foreign bodies, especially defects, at least one multiple reflection, preferably at least one double reflection, particularly at least one triple reflection, and more preferably at least one quadruple reflection of the measurement radiation occurs within the object at the surfaces of the object, especially on the measuring side and the measuring back of the object. This ensures that the measurement radiation propagates from the coupling area to the measurement volume adjacent to the measurement area.

[0028] In particular, it is advantageous that the coupling of the measurement radiation into the object being measured takes place at the coupling area in such a way that total reflection of the measurement radiation occurs within the object being measured at the surfaces of the object being measured, in particular at the measuring side and the measuring back side of the object being measured.

[0029] As previously explained, the method according to the invention enables precise, rapid detection of defects in objects being measured, in particular in films as the object being measured.

[0030] In an advantageous embodiment, the object being measured is moved relative to the detector during the measurement. Advantageously, this movement is achieved using transport devices known per se, in particular for the linear conveying of the object along a straight transport line. The use of rollers for moving the object is particularly advantageous, especially at least one motor-driven roller. Likewise, the use of a conveyor belt and / or a conveying carriage for moving the object is within the scope of the invention.

[0031] The method according to the invention is particularly suitable for the detection of defects in measurement objects, the analysis and / or processing of which is carried out in a roll-to-roll process.

[0032] 34912-P-WO Di / co 07.10.2025. Advantageously, the object being measured is used as a base substrate in a roll-to-roll process, and the measurement is performed during the roll-to-roll process. The method according to the invention enables precise detection of defects at high processing speeds, particularly at high movement speeds of the object being measured relative to the detector.

[0033] The radiation source is preferably designed as a line source. This enables the application of radiation to a coupling area of ​​large width, in particular a width that extends over the entire width of the object being measured.

[0034] The coupling area advantageously extends completely across the width of the object being measured. In particular, a radiation source is preferably used which is configured to completely illuminate the coupling area of ​​the object being measured with measurement radiation. This enables the detection of defects across the entire width of the object being measured and, if the object is moved perpendicular to its width, allows for complete detection across its entire volume. It is therefore advantageous that, as described above, the object being moved relative to the detector during the measurement, and that the aforementioned width is perpendicular to the direction of movement of the object being measured.

[0035] The radiation source can be designed as a light source in a manner known per se. Designing the radiation source as a laser, particularly a diode laser, is advantageous for generating a directed measurement beam with high intensity in a simple manner. The wavelength of the measurement beam can be in the visible range, or it can be outside the visible range. Advantageously, the spectrum, and especially the wavelength of the measurement beam, is selected such that only minimal absorption occurs within the volume of the object being measured, apart from defects. Therefore, for objects that are essentially transparent in the visible range, the use of measurement beams in the visible range is advantageous.

[0036] The detection and preferably localization of the defects is preferably carried out by evaluating the intensity of the measurement radiation detected by the detector for the majority of points within the measurement range. In an advantageous embodiment, a limit value is defined.

[0037] 34912-P-WO Tue / co 07.10.2025 for the intensity, and locations where measurement radiation with an intensity greater than the limit value is detected are characterized as locations with defects. In a variation, the intensity of the measurement radiation at a measurement point is compared with a predefined mean measurement radiation or a predefined mean value over a large number of measurement points. If a deviation is greater than a predefined minimum deviation, in particular greater than a predefined minimum percentage deviation from the mean value, this measurement point is characterized as a location with a defect.

[0038] Investigations by the applicant show that the method according to the invention is particularly suitable for detecting defects in membrane films, especially membrane films used in the manufacture of fuel cells. It is desirable for membrane films to have no or only a small number of defects within the membrane film to avoid impairment of function due to defects or a reduction in the efficiency of the subsequent function. Particularly in the manufacture of fuel cells, it is essential to check the membrane films used for the manufacture of the fuel cell for defects, especially inclusions of foreign matter and / or gases, and especially cavities within the membrane film, since such defects adversely affect the function of the fuel cell.

[0039] Advantageously, the method according to the invention is used to detect defects in membrane films for the production of fuel cells. In particular, it is advantageous that the membrane films are handled in a roll-to-roll process. This ensures high throughput and easy handling of the membrane as a roll.

[0040] It is advantageous to use the device according to the invention described below, in particular an advantageous embodiment thereof, for detecting defects in a film for the manufacture of fuel cells, preferably by means of the method according to the invention, in particular an advantageous embodiment thereof. In particular, its use for detecting defects in a membrane film for the manufacture of fuel cells is advantageous.

[0041] 34912-P-WO Di / co 07.10.2025 Fuel cells, preferably polymer electrolyte fuel cells (especially PEMFC), are advantageous.

[0042] The aforementioned problem is further solved by a device for detecting defects in a measuring object according to claim 12.

[0043] The device according to the invention comprises a radiation source for generating measurement radiation, a measuring holder for arranging the object to be measured on or in the measuring holder, and a detector for spatially resolved measurement of measurement radiation. The detector is arranged and configured to interact with the measuring holder in such a way as to detect measurement radiation at several spatially different measuring points within a measuring range on one side of the object to be measured when the object is arranged on or in the measuring holder.

[0044] It is essential that the radiation source is arranged and designed to interact with the measuring holder in such a way as to impart the measurement radiation to a coupling area on the surface of the object being measured, so that the measurement radiation enters the object being measured within the coupling area, wherein the coupling area is arranged outside the measuring area and is located outside a rear measuring area opposite the measuring area, arranged on the rear side of the measuring object.

[0045] The device according to the invention thus has the advantages mentioned above for the method according to the invention; in particular, it is possible to carry out the method according to the invention by means of the device according to the invention.

[0046] Advantageously, the measuring holder is designed to move the object being measured relative to the detector, particularly along a linear direction of movement. Advantageously, the measuring holder is designed as a roller conveyor and has several rotatable rollers for moving the object being measured, preferably along a linear direction of movement. The measuring holder preferably has at least one, and preferably several, motor-driven rollers. Likewise, the design of the measuring holder as a conveyor belt and / or as a conveyor carriage for moving the object is within the scope of the invention.

[0047] 34912-P-WO Di / co 07.10.2025 As previously described, the measuring holder can be designed for linear transport, in particular as a conveyor belt or as a linear transport device containing a conveyor carriage.

[0048] In an advantageous embodiment, the object being measured is therefore moved relative to the detector during the measurement by means of the measuring holder.

[0049] Advantageously, the device according to the invention is designed to carry out a roll-to-roll process. This allows, as described above, the rapid characterization of objects to be measured, in particular flexible objects, and preferably film-like objects. Advantageously, the device therefore comprises an output roll holder and an end roll holder, as well as one or more steering elements for the object to be measured. Furthermore, the device preferably comprises one or more motor drives to enable the object to unroll from the output roll holder and to wind onto the end roll holder. The device is preferably designed such that the measuring area and the coupling area on the object to be measured are arranged between the output roll holder and the end roll holder.

[0050] As previously explained, the measuring fixture preferably has a deflection area to deflect the object being measured in a region outside the measuring range, so that the object being measured has at least one bend, and the radiation source is arranged and designed to interact with the measuring fixture such that a normal vector of the measuring range is not parallel to a normal vector of the coupling area, in particular that the normal vector of the measuring range to the normal vector of the coupling area has an angle greater than 5°, more particularly greater than 10°, preferably greater than 20°, and / or that the normal vector of the measuring range to the normal vector of the coupling area has an angle less than 90°, more particularly greater than 70°, preferably less than 50°. This results in the advantages previously listed for the method of deflecting the object being measured and creating a bend.

[0051] 34912-P-WO Di / co 07.10.2025 The measuring holder preferably has a deflection area with a bending element in the deflection area, as described above. In particular, the bending element preferably includes the radiation source.

[0052] The bending element preferably has a rotatable roller, in particular a conveyor roller, preferably a motor-driven conveyor roller, to enable transport of the object being measured. The radiation source is preferably arranged inside the bending element, and the bending element has openings and / or a surface transparent to the measurement radiation to allow the object being exposed to measurement radiation on the side of the object facing the bending element.

[0053] Preferably, the bending element is designed as a radiation source, in particular as a luminous cylinder, which is designed to emit the measurement radiation, preferably as a rotatable radiation source, in particular as a rotatable luminous cylinder.

[0054] In an advantageous embodiment of the method according to the invention, a measurement background is arranged on the rear side of the measuring device, either directly or, preferably, at a distance from the object being measured. The measurement background is preferably designed and arranged such that the detector's field of view, without the object being measured, is completely covered by the measurement background. The measurement background is preferably designed to absorb the measurement radiation. In particular, when designing the radiation source for generating measurement radiation in the visible range, it is advantageous to design the measurement background with a black surface. In the measurement setup, the object being measured is thus arranged between the measurement background and the detector. This avoids or at least reduces measurement interference due to stray radiation, especially in the wavelength range of the measurement radiation, which originates from the rear side of the measuring device, passes through the object being measured, and strikes the detector.

[0055] Advantageously, the coupling area is arranged such that measurement radiation which is reflected directly (without penetrating the object being measured) at the outer surface of the object being measured (direct reflection) does not reach the detector. This increases the measurement accuracy. Preferably, the measuring mount and the radiation source of the

[0056] 34912-P-WO Di / co 07.10.2025 The device according to the invention is arranged and designed to interact in such a way that measurement radiation which is reflected directly (without penetrating the object being measured) at the outer surface of the object being measured (direct reflection) does not hit the detector.

[0057] The method and device according to the invention are particularly suitable for the analysis of thin, planar measuring objects, especially films.

[0058] Advantageously, the method is therefore used to detect defects in a measurement object with a thickness of less than 1 mm, more preferably less than 0.5 mm, and particularly less than 0.1 mm. The width of the measurement object is preferably greater than 1 cm, more preferably greater than 5 cm, and more preferably greater than 20 cm. Preferably, the width of the measurement object is in the range of 1 cm to 100 cm, and particularly 1 cm to 50 cm.

[0059] The length of the object being measured is preferably greater than 5 cm, and particularly greater than 10 cm. The method, as described above, is particularly suitable for roll-to-roll processes. Therefore, the length of the object being measured is preferably greater than 1 m, preferably greater than 5 m, and particularly greater than 10 m. Preferably, the length of the object being measured is in the range of 10 cm to 1000 m, and particularly 20 cm to 500 m.

[0060] The object being measured is preferably moved in a transport direction parallel to the longitudinal extent of the object being measured.

[0061] In an advantageous embodiment, the coupling area is arranged on the measuring side, particularly directly adjacent to the measuring area. This has the advantage that the measurement radiation does not have to penetrate any intermediate volume of the object being measured between the coupling area and the measuring area, thus preventing a reduction in the intensity of the measurement radiation. In an alternative embodiment, the coupling area is arranged at a distance from the measuring area. This has the advantage of better preventing scattered radiation from the measurement radiation from reaching the detector.

[0062] To avoid interference radiation, in the method according to the invention the coupling of measurement radiation into the object being measured is preferably carried out essentially in the

[0063] 34912-P-WO Di / co 07.10.2025 Coupling area, in particular the intensity of the measurement radiation coupled into the object of measurement in the coupling area is preferably at least 90% of the intensity of the total measurement radiation coupled into the object of measurement, more preferably at least 95% of the intensity of the total measurement radiation coupled into the object of measurement, in particular at least 99% of the intensity of the total measurement radiation coupled into the object of measurement.

[0064] Further advantageous features and designs are described below with reference to exemplary embodiments and the figures. These show:

[0065] Figure 1 shows a first embodiment of a device according to the invention;

[0066] Figure 2 shows a top view of a measuring object according to Figure 1;

[0067] Figure 3 is a detailed enlargement of the representation shown in Figure 1;

[0068] Figure 4 shows a second embodiment of a device according to the invention;

[0069] Figure 5 shows a top view of a measuring object according to Figure 4 and

[0070] Figure 6 shows a third embodiment of a device according to the invention.

[0071] All figures are schematic representations, not to scale. Identical reference symbols within the figures denote identical or similarly functioning elements.

[0072] Figure 1 shows a first embodiment of a device according to the invention for detecting defects in a test object. The device comprises a radiation source 2, which in this case is a diode laser. The diode laser has a plurality of laser diodes that generate measurement radiation in the visible range with a wavelength of 607 nm. The diode laser is designed to generate measurement radiation with a line-like cross-sectional profile, such that the cross-sectional profile of the measurement radiation corresponds to an elongated rectangle. In the illustration according to Figure 1, the longitudinal extent of the rectangle is perpendicular to the plane of the drawing.

[0073] The device further comprises a detector 3 for detecting the measurement radiation, which in this case is designed as a CCD line camera. The line camera has 1,000 sensors arranged side by side in a straight line.

[0074] 34912-P-WO Di / co 07.10.2025 The object being measured 1 is designed as a film, in this case as a membrane for the production of a fuel cell.

[0075] The device includes a measuring holder designed for roll-to-roll detection. The measuring holder comprises an output roll holder 5 for rotatably receiving an output roll of the object being measured 1 and an end roll holder 6 for receiving an end roll of the object being measured 1. Furthermore, the device includes several support rollers, represented as circles, with the support roller located on the left in Figure 1 being designed as a deflection roller 7 (bending element). The device has a motor drive for rotating the end roll 6, enabling the film to unwind from the output roll, be transported along the direction indicated by an arrow in Figure 1 over the support rollers, and be wound onto the end roll.

[0076] In the embodiment shown in Figure 1, the measurement is taken from above. Accordingly, the side shown above represents the measuring side of the object being measured, and the side shown below represents the measuring back. The film has a circumferential edge, with Figure 1 showing a top view of one edge.

[0077] The detector is used to detect measurement radiation in a measurement range 4 at a plurality of different measurement points located within the measurement range 4, in this case as described above at 1000 measurement points arranged in a straight line, wherein the line of measurement points is perpendicular to the plane of the drawing according to the representation of Figure 1.

[0078] The coupling of the measurement radiation generated by the radiation source 2 takes place in a coupling area 8 of the measurement area 4 and outside a measurement rear area 4' located opposite the measurement area and arranged on the rear side of the measurement unit, see detailed enlargement in Figure 3. The guidance of the measurement object 1 over the deflecting roller 7 creates a deflection area in which the measurement object 1 has a bend corresponding to the curvature of the surface of the deflecting roller 7. The radiation source 2 is arranged and designed to interact with the measurement holder in such a way that a

[0079] 34912-P-WO Tue / co 07.10.2025 The normal vector VI of the measuring area 4 is not parallel to a normal vector V2 of the coupling area 8. As can be seen in Figure 3, the normal vector V2 forms an angle of approximately 45° with the normal vector VI. The measurement radiation from the measuring source 2 does not strike the coupling area 8 perpendicularly and therefore not parallel to the normal vector V2.

[0080] Figure 2 shows a top view of the measuring side of the foil-shaped measuring object 1 to illustrate the separate, non-overlapping arrangement of measuring area 4 and coupling area 8. The radiation source 2 is designed to completely and homogeneously illuminate the linear, narrow rectangular coupling area 8 with measurement radiation, so that the measuring object 1 is illuminated with measurement radiation across its entire width. The width is perpendicular to the flow rate of the measuring object 1. The measuring area 4 also covers the entire width of the measuring object 1. As previously described, the detector 3 has 1,000 sensors arranged in a row. Accordingly, the measuring area 4 is divided into 1,000 measuring areas arranged vertically one above the other, as shown in Figure 2.

[0081] In one embodiment of a method according to the invention using the device shown in Figure 1, the object 1 being measured is unrolled from the starting roll and wound onto the unroll, so that the object is moved along the direction indicated by an arrow. During the movement of the object, it is stimulated with measurement radiation by means of the radiation source 2, so that the measurement radiation enters the object 1, which is designed as a film, in the coupling area 8. The measurement radiation propagates within the object 1 and is scattered by any defects such as foreign bodies or enclosed cavities containing, for example, ambient air or other gases. A portion of the scattered measurement radiation exits the object 1 at the measurement side in measurement area 4 and strikes the sensors of the detector 1.By means of detector 1, the increased intensity in the presence of a defect makes it possible to detect that a defect is present and, furthermore, the spatial resolution of the large number of sensors of detector 3 allows for local localization of the defect.

[0082] 34912-P-WO Tue / co 07.10.2025 Figure 4 shows a modification of the embodiment depicted in Figure 1 as a second embodiment. To avoid repetition, only the essential differences are described below:

[0083] In the second embodiment, the radiation source 2 is arranged laterally at an edge of the object 1 being measured, thus behind the object 1 as shown in Figure 4. The radiation source 2 is designed to illuminate an edge of the object 1 corresponding to the width of the measuring area 4 with measurement radiation. As can be seen in Figure 5, which shows a top view of the object 1 of the device according to Figure 4, the coupling area 8 is thus arranged at an edge of the object 1 that is located at the top in the illustration of Figure 5.

[0084] In the first embodiment shown in Figure 1, a measurement background 8 is arranged at a distance of 2 cm from the rear surface of the object 1. The measurement background has a black surface, so that the contrast of the measurement radiation scattered by the defects is increased compared to the areas of the object that do not have radiation-scattering defects.

[0085] The second embodiment shown in Figure 2 has no measurement background.

[0086] Figure 6 shows a further development of the embodiment shown in Figure 4 as a third embodiment. In contrast to the second embodiment shown in Figure 4, in the third embodiment the deflection roller 7, which is designed as a bending element, incorporates the radiation source 2. The cylindrical surface of the deflection roller 7 is transparent to the measurement radiation, so that the measurement radiation passes from the interior of the deflection roller 7 through the surface and illuminates the rear side of the object 1 being measured, thus propagating the measurement radiation within the object by multiple reflections and total internal reflection. In a further modification, the surface of the deflection roller 7 has several holes through which the measurement radiation passes.

[0087] 34912-P-WO Tue / co 07.10.2025 The measurement radiation strikes the object 1 both at the area directly adjacent to the deflecting roller 7 and at areas of the object 1 on the rear side in the direction of movement, either upstream or downstream of the deflecting roller 7. This results in the measurement radiation striking at least one coupling area on the rear side, where it is coupled into the object 1 and propagates within the object 1 due to multiple or total reflection. Figure 6 schematically illustrates such a coupling area 8 on the rear side downstream of the deflecting roller 7 in the conveying direction.

[0088] 34912-P-WO Tue / co 07.10.2025 Reference list

[0089] 1 measuring object

[0090] 2 radiation source

[0091] 3 Detector

[0092] 4 Measuring range

[0093] 5 Output roller bracket

[0094] 6 End roller bracket

[0095] 7 Pulley

[0096] 8 Coupling area

[0097] 9 Measurement background

[0098] 34912-P-WO Tue / co 07.10.2025

Claims

Claims 1. Method for detecting defects in a measurement object (1), comprising the method steps Providing the object to be measured (1) with a measuring side and a measuring rear side opposite the measuring side and an edge region adjacent to the measuring side and the measuring rear side with at least one edge side, subjecting the object to being measured (1) with measurement radiation from a radiation source (2) and detecting measurement radiation for a plurality of spatially different measurement points located within a measurement area (4) by means of a detector (3), wherein the measurement area (4) is arranged on the measuring side, characterized in that an input area (8) of the surface of the object to being measured (1) is subjected to the measurement radiation, so that the measurement radiation enters the object to being measured (1) within the input area (8), wherein the input area (8) is arranged outside the measurement area (4) and is arranged outside a measurement rear area opposite the measurement area (4) and arranged on the measuring rear side.

2. Method according to claim 1, characterized in that the coupling area (8) is arranged on the edge side.

3. Method according to claim 1, characterized in that the coupling area (8) is arranged on the measuring side or on the measuring rear side, preferably on the measuring side.

4. Method according to claim 3, characterized in that, 34912-P-WO Tue / co 07.10.2025 that the object being measured (1) is arranged with at least one bend, such that a normal vector of the measuring area (4) is not parallel to a normal vector of the coupling area (8), in particular that the normal vector of the measuring area (4) to the normal vector of the coupling area (8) has an angle greater than 5°, in particular greater than 10°, preferably greater than 20° and / or that the normal vector of the measuring area (4) to the normal vector of the coupling area (8) has an angle less than 90°, in particular greater than 70°, preferably less than 50°.

5. Method according to claim 4, characterized in that the bending of the object being measured is carried out on a bending element which has the radiation source.

6. Method according to one of the preceding claims, characterized in that the object to be measured (1) is a flexible object to be measured (1), in particular a film.

7. Method according to claims 5 and 6, characterized in that the object being measured (1) is moved relative to the detector (3) during the measurement, in particular that the object being measured (1) is used as a base substrate in a roll-to-roll process and the measurement is carried out during the roll-to-roll process.

8. Method according to one of the preceding claims, characterized in that the radiation source (2) is designed as a line source.

9. Method according to any one of the preceding claims, characterized in that 34912-P-WO Tue / co 07.10.2025 that the coupling area (8) extends completely over a width of the object being measured (1), in particular that a radiation source (2) is used which is designed to completely expose the object being measured (1) and the coupling area (8) to measurement radiation, in particular that according to claim 5 the object being measured (1) is moved relative to the detector (3) during the measurement and the aforementioned width is perpendicular to the direction of movement of the object being measured (1).

10. Method according to one of the preceding claims, characterized in that a laser, in particular a diode laser, is used as the radiation source (2).

11. Method according to one of the preceding claims, characterized in that a membrane film, in particular a membrane film for the manufacture of fuel cells, is used as the object being measured (1).

12. Device for detecting defects in a test object (1), comprising a radiation source (2) for generating measurement radiation, a measuring holder for arranging the test object (1) on or in the measuring holder, and a detector (3) for spatially resolved measurement of measurement radiation, wherein the detector (3) is arranged and configured to interact with the measuring holder in such a way as to detect measurement radiation for several spatially different measurement points within a measuring range (4) on one side of the test object when the test object (1) is arranged on or in the measuring holder, characterized in that the radiation source (2) is arranged and configured to interact with the measuring holder in such a way as to impinge the measurement radiation on an input area (8) of the surface of the test object (1), so that the measurement radiation enters the test object (1) within the input area (8), wherein 34912-P-WO Tue / co 07.10.2025 22 the coupling area (8) is arranged outside the measuring area (4) and is arranged outside a measuring rear area opposite the measuring area (4) on the measuring rear side.

13. Device according to claim 12, characterized in that the measuring holder is designed for moving the object being measured (1) relative to the detector (3), in particular along a straight-line direction of movement, in particular that the measuring holder has a plurality of rollers for moving the object being measured, in particular for placing the object being measured on the rollers, preferably that the measuring holder has at least one motor-driven roller.

14. Device according to one of claims 12 to 13, characterized in that the measuring holder has a deflection area to deflect the object being measured (1) in an area outside the measuring area (4), so that the object being measured (1) has at least one bend and the radiation source (2) is arranged and designed to interact with the measuring holder such that a normal vector of the measuring area (4) is not parallel to a normal vector of the coupling area (8), in particular that the normal vector of the measuring area (4) to the normal vector of the coupling area (8) has an angle greater than 5°, in particular greater than 10°, preferably greater than 20° and / or that the normal vector of the measuring area (4) to the normal vector of the coupling area (8) has an angle less than 90°, in particular greater than 70°, preferably less than 50°.

15. Device according to claim 14, characterized in that the deflection area has a bending element which has at least one rotatable roller, wherein the radiation source is arranged in the rotatable roller, 34912-P-WO Tue / co 07.10.2025 23 in particular that the bending element has openings and / or a surface transparent to the measuring radiation, for applying measuring radiation to the object being measured on the side of the object being measured facing the bending element, in particular that the bending element is designed as a luminous cylinder which is designed to emit the measuring radiation, preferably as a rotatable radiation source, in particular as a rotatable luminous cylinder.

16. Use of a device according to one of claims 12 to 15 for detecting defects in a film for the manufacture of fuel cells, in particular a membrane film for the manufacture of fuel cells, preferably polymer electrolyte fuel cells. 34912-P-WO Di / co 07 / 10 / 2025

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