Measuring system and method for measuring the thickness of flat objects

Abstract

With regard to particularly reliable measurement, a measuring system (1) for measuring the thickness of flat objects (2), comprising a sensor (3a) which measures the distance to a flat object (2) in a contactless manner and a support device having a flat support element (6) for supporting the flat object (2) on a support surface (11) of the support element (6) during a measurement, wherein the sensor (3a) is arranged for a distance measurement in the direction of the support surface (11), is designed and developed in a simple manner with simple design means such that the support element (6) has at least one passage, extending from the support surface (11) through the support element (6), for suctioning air from a region above the support surface (11) through the at least one passage. The invention further relates to a corresponding method for measuring the thickness of flat objects (2).

Description

[0001] MEASURING SYSTEM AND METHOD FOR MEASURING THE THICKNESS OF FLAT OBJECTS

[0002] The invention relates to a measuring system for measuring the thickness of flat objects, comprising a sensor that measures the distance to a flat object without contact and a support device with a flat support element for supporting the flat object on a support surface of the support element during a measurement, wherein the sensor is arranged in the direction of the support surface for a distance measurement.

[0003] Furthermore, the present invention relates to a method for measuring the thickness of flat objects with a measuring system, wherein the measuring system has a sensor that measures the distance to a flat object without contact and a support device with a flat support element for supporting the flat object on a support surface of the support element during a measurement, wherein the sensor is arranged in the direction of the support surface for a distance measurement.

[0004] In the production of film-like products or films that can form flat objects to be measured (hereinafter also referred to as measurement objects), a consistent thickness is very important, for example, to reliably ensure the desired function of the product. To demonstrate a stable manufacturing process, it is essential to be able to reproducibly measure a thickness that is as consistent as possible. The materials can have very different structures, for example, thin, soft, or porous. The thickness can also vary greatly depending on the type of film, ranging from as little as 0.5 μm to several millimeters, depending on the application.

[0005] In most cases, qualitative thickness testing takes place offline. This means that a sample piece is taken from a production batch and then measured for thickness. The measurement method must achieve sub-micrometer precision while simultaneously guaranteeing a precisely defined measuring surface. A key prerequisite for the thickness measurement method is traceability to reference dimensions. To verify the reliability of a testing method, repeatability to a target dimension must be reliably possible. This allows measurement results to be compared over a long period of time, and absolute and relative deviations can be identified.

[0006] Probably the most common method is tactile. With this method, resolutions down to the nanometer range can be reliably achieved in offline measurements. The main criticism lies in the poor reproducibility of this technique, because a tactile measuring system exerts a force on the sample and can change the thickness of the material during the measurement depending on its properties. Depending on the design of the probe tip or the set force, the result can vary even on the same sample.

[0007] As an alternative, there are non-contact measurement methods such as optical, capacitive, or radiometric methods that enable better reproducibility. A distinction is made between single-sided methods, which require a reference as a reference point, and double-sided methods, which use two sensors. Single-sided measurement involves the uncertainty that disturbances affect the reference surface during the measurement that cannot be detected. Disturbances can include contamination on the reference surface, air pockets or wrinkles in the material being measured, as well as a change in the spatial position of the reference object. A change in the distance between the reference surface and the measuring system has a particularly significant impact, as this directly influences the thickness measurement result.The one-sided method can be implemented using capacitive, optical, ultrasonic, or even radiometric principles, although these disturbances significantly limit the maximum precision and repeatability of the measuring system, regardless of the principle. Radiometric systems can ideally achieve a precision of less than one micrometer, but have additional requirements such as a radiation protection officer or specific calibration for each material. Furthermore, one-sided methods are particularly suitable for inline measurements in production because they can be more easily integrated into a production line. The two-sided methods are used for inline and offline measurements. By measuring from both sides, the disturbances mentioned in the one-sided method can be largely eliminated. The second sensor is located in place of the reference object and, like the first sensor, records a distance signal to the measurement object.Subtracting the two distance signals to the object to be measured yields the thickness of the material between the sensors, assuming the distance between the two sensors is known. The challenges here are calibrating the base distance between the two sensors and guiding the object between the sensors during the thickness measurement.

[0008] Both methods have the problem that the positioning of the object to be measured plays a crucial role in how precisely and reproducibly the thickness can be determined. When using a roller guide, wrinkles or overlaps can occur that neither the single-sided nor the double-sided measurement method can detect. Furthermore, the belt tension must always be uniform and must not change the thickness of the object being measured due to the tensile force. Placing the material on a surface has the disadvantages already discussed in connection with single-sided thickness measurement.

[0009] For this reason, a method for offline measurement must be found that minimizes these challenges and enables the highest possible reproducibility and resolution. To achieve this, a method must be developed that enables reproducible local positioning of the measurement object and also prevents interference such as wrinkles, air pockets, or contamination.

[0010] The present invention is therefore based on the object of specifying a measuring system and a method of the type mentioned at the outset, according to which a particularly reliable measurement is made possible in a simple manner using structurally simple means.

[0011] According to the invention, the above object is achieved by a measuring system having the features of claim 1 and by a method having the features of claim 15.

[0012] According to this, the measuring system according to claim 1 is designed and developed in such a way that the support element has at least one passage extending from the support surface through the support element for sucking air from a region above the support surface through the at least one passage.

[0013] Furthermore, the method according to claim 15 is designed and developed in such a way that the support element has at least one passage extending from the support surface through the support element for sucking air from a region above the support surface through the at least one passage and that the flat object to be measured is sucked onto the support surface during the measurement by means of air sucked through the at least one passage.

[0014] In accordance with the invention, it was first recognized that the above object is achieved in a surprisingly simple manner by cleverly designing the support element. In a further embodiment, it was then specifically recognized that a design of the support element with at least one passage extending from the support surface through the support element is particularly suitable for achieving the object, wherein the passage(s) are designed to suck air from an area above the support surface through the at least one passage. This enables the flat object to be measured to be securely fixed to the support surface, wherein any folds, bubbles and / or bulges in the object and / or air cushions beneath the object can be largely eliminated by sucking air out through the passages.As a result, the flat object to be measured can be provided with a homogeneous and flat surface or measuring surface for the measurement. This ensures reproducible measured values ​​and thus a reliable measurement of the thickness. Consequently, the measuring system and method according to the invention provide a measuring system and method that enable particularly reliable measurement in a simple manner using simple structural means.

[0015] For particularly reliable measurements, it is advantageous if the support element has as many passages as possible for extracting air. This allows the object to be measured to be provided with a homogeneous and flat surface or measuring area for measurement in a particularly simple and reliable manner. For this purpose, the support element can have passages created by drilling, erosion or other mechanical processing. In a particularly advantageous manner, the support element can comprise a porous material or be formed from a porous material, with one or more passages being formed by individual or interconnected pores in the material. It is advantageous that the passages formed in this way usually have a very small diameter and do not deform the material of the object to be measured during suction, or only deform it very slightly, due to the suction force exerted on the object to be measured by the suction.

[0016] Specifically, the porous material can be a metal or a ceramic, or it can consist of a metal or a ceramic. Both materials are suitable for the implementation of the measuring system due to their strength and other material properties.

[0017] Furthermore, the porous material can advantageously be a metal foam or comprise a metal foam, for example, porous aluminum or titanium. The specific choice of material can be based on the material of the object to be measured in order to ensure the most reliable thickness measurement possible.

[0018] For particularly reliable measurements, the support element can be coupled to a vacuum pump. This ensures that the flat object to be measured has a homogeneous and flat surface. The vacuum pump can be connected to the support element, and specifically to at least one passage in the support element, via suitable hose or line connections.

[0019] To ensure a suitably homogeneous and flat surface of the object to be measured, and thus with a view to particularly reliable measurement, the vacuum pump can be equipped with a control or regulation for a predefined suction force for a flat object placed on the support surface. This can prevent the object to be measured from being sucked onto the support surface with excessive suction force, which could potentially damage or deform the object to be measured. For example, if the passage(s) have such a large diameter that there is a risk that the object to be measured will be partially sucked into the passage(s). Using such a control or regulation, the predefined suction force can be easily adjusted to the individual properties and characteristics of the object to be measured.

[0020] In a further advantageous manner, the support element can have a measuring insert or measuring attachment, each with a closed surface, which with its surface forms a partial region of the support surface, wherein the partial region is preferably an inner region of the support surface. Such a measuring insert can be integrated into the support element so that the support surface and the surface of the measuring insert are aligned or lie in one plane. As an alternative to such a measuring insert, a measuring attachment can also be used, for example one positioned on the support surface, wherein its surface is then positioned in a plane above the support surface. Depending on the individual situation, the object to be measured can have different mechanical properties. For example, the object to be measured can be made of a soft, porous material.The use of such a measuring insert or measuring attachment enables adaptation to such different mechanical properties of the object to be measured, whereby the measuring insert or measuring attachment is usually made of a solid or rigid material and in particular without passages and is to be arranged in the measuring range of the sensor(s). In concrete terms, a portion of the support element can be replaced by a measuring insert or measuring attachment without passages. The object to be measured is therefore not influenced or deformed in the area of ​​the measuring insert or measuring attachment by the force of the sucked in air or by the passages, whereby the advantages of positioning using negative pressure are nevertheless retained, since in the outer area, i.e. around the measuring insert or measuring attachment, the same effect and the same conditions are created as in the case without a measuring insert or measuring attachment.Possible air pockets or wrinkles in the area of ​​the measuring insert or measuring attachment are largely removed by the suppression of the surrounding areas.

[0021] Furthermore, with a view to particularly reliable and precise measurement, the measuring system can have a sensor holder with a low thermal expansion coefficient, wherein the sensor holder can be bow-shaped and alternatively or additionally can be made of, for example, Invar or a ceramic or can comprise Invar or a ceramic. By selecting a material for the sensor holder with a low thermal expansion coefficient, influences on the measurement due to temperature fluctuations can be reduced or largely avoided. Invar or a ceramic can be used as a particularly suitable material for this. With a bow-shaped design, secure positioning of the sensor at a desired measuring point on the object to be measured is possible, whereby the sensor holder can virtually encompass the support element.

[0022] Furthermore, to ensure the most reliable and accurate measurement possible, the sensor holder can be mechanically decoupled from the support element. This largely eliminates any kind of mutual influence between these components.

[0023] In a further advantageous manner, the measuring system can have a second sensor which is arranged in the direction of the support element for distance measurement. In this case, for example, the second sensor can measure from below against the support element, while the original sensor - the first sensor - measures from above against the object to be measured. Depending on the strength of the negative pressure generated when the object to be measured is sucked in, the support element can in some cases also be bent slightly, which directly affects the measurement using the first sensor. In this case, the distance between the object to be measured and the first sensor increases by the same amount as the distance from the second sensor to the support element decreases. This interference effect can thus be compensated for by measuring with the second sensor against the support element.

[0024] For particularly reliable and simple measurements, the sensor and / or the second sensor can be capacitive or optical sensors. The choice of measurement principle can be easily tailored to the specific application.

[0025] To simplify the design of the measuring system, the measuring system can include a base body for mounting or arranging the support element. This allows for a particularly stable and accurate measuring system to be realized.

[0026] In a particularly simple design, the base body can have several webs on which the support element rests, forming air channels between the webs. This allows for a simple and effective connection of a vacuum pump to the support element or to the passage(s) in the support element. Alternatively, or in addition to the base body, the support element can also have such webs, forming air channels for the vacuum pump to extract air.

[0027] In a particularly practical manner, the measuring system can have a handle connected to the base body, wherein the handle preferably has a cable duct for connecting cables of the sensor(s). The handle enables easy transport and thus simple operation of the measuring system at different measuring locations. A cable duct suitably integrated into the handle or arranged on the handle enables simple, protected and thus safe accommodation of one or more connecting cables. It is particularly advantageous if the handle is suitably arranged above the sensor holder. This prevents a user from mistakenly grasping the measuring system by the sensor holder. The sensor holder is usually part of the - possibly already calibrated - measuring section and could be damaged by improper handling.This is reliably avoided by this arrangement of the handle.

[0028] In the following, aspects and advantages of embodiments of the measuring system and method described above are explained in more detail:

[0029] A fundamental basis for reliable non-contact thickness measurement of a flat sample or a flat object or measurement object consists of a distance measurement using a sensor, for example a capacitive sensor, and a support surface for the measurement object, which is provided with one or more openings through which air can be drawn in. The goal is a non-contact thickness measurement without applying point loads to the measurement object using a non-contact sensor, as well as the flush support of the measurement object on the support surface by preferably drawing air in over the entire surface through the opening(s) in the support surface.

[0030] For high-precision measurements, a measuring surface that is absolutely or as flat as possible is required. This is achieved using a negative pressure created by the passages in the support surface beneath the measuring object. The passages in the support surface are connected to a vacuum pump, which creates the negative pressure. This draws air through the openings and presses the measuring object against the support surface. Any existing wrinkles, bubbles, bulges, or air pockets are thereby removed, creating a homogeneous, flat measuring surface on the support surface. The negative pressure holds the measuring object in place during the measurement and ensures reproducible measured values.

[0031] Potential influences from external forces, such as those associated with tactile measurement principles or the positioning of the measurement object, are not present here. By controlling the negative pressure beneath the support surface, sufficient force is generated for positioning, but not enough for elastic or plastic deformation of the measurement object. In comparison, other fixation alternatives such as clamps or tensioning cannot create such controlled measurement conditions.

[0032] In order to achieve a flat support of the measuring object, it is advantageous if there are a large number of passages in the support surface. The passages can be machined into the support surface by drilling, eroding or other mechanical processing. It is particularly advantageous if the material of the support element, for example a support plate, is itself made of a porous material. Metal foams such as porous aluminum or titanium are conceivable here. Porous ceramics are also conceivable. With such materials, the pores in the material form the desired passages through which the air is sucked in by the support surface. It is important that the pores do not form isolated air pockets in the material, but are connected to one another so that a passage is present and an air flow can occur. The particular advantage of porous materials is that the number of passages is many times higher than, for example,with holes. At the same time, the passages have a significantly smaller cross-section than holes. This allows a sufficiently large total cross-section to be achieved from all passages. As a result, the vacuum pump only needs to generate a relatively low vacuum to securely hold the measurement object. Smaller passages also have the advantage that the measurement object cannot be drawn into the passages, or can only be drawn into them with great difficulty, which could distort the measurement or damage the measurement object. Furthermore, the machining required to create the holes is eliminated.

[0033] The thickness is measured using a non-contact sensor, which, in exemplary embodiments of the measuring system, measures the distance to the measuring object on the support surface from above. The support surface is formed by the surface or support surface of a support element in the form of a support plate. The support plate is attached to a base body. The sensor is mounted in a stable measuring bracket at a fixed distance from the support surface. To ensure that the distance of the sensor relative to the support surface does not change, it is expedient for the measuring bracket to be made of a material with a low thermal expansion coefficient, for example Invar or ceramic. In exemplary embodiments, the measuring bracket is mechanically decoupled from the support plate.

[0034] In a first step, the sensor's measured value against the support surface can be determined and saved. The measurement can then be performed with the target object. The thickness of the target object can be determined with high precision from the difference between the two measured values ​​in a known manner.

[0035] The sensor can be an optical sensor, such as a laser triangulation sensor, a confocal chromatic sensor, or an interferometer. Optical sensors detect the surface of the measurement object. However, with transparent or opaque measurement objects, light can penetrate the material and distort the measured value. Alternatively, the sensor can use a capacitive measuring principle. This does not depend on the optical properties of the measurement object, but rather on its electrical properties, in particular the conductivity or permittivity of the material. Capacitive sensors are characterized by particularly high resolution, which enables the thickness measurement of even particularly thin films with high precision.

[0036] For particularly precise measurements, it may be useful to have a second sensor measuring from below against the support element. The vacuum pump's negative pressure may cause the support element to bend slightly, which directly impacts the one-sided thickness measurement. The lower sensor measures the underside of the support element, such as a support plate. If the position of the support plate changes due to the negative pressure, the distance to the lower sensor changes. The distance between the measurement object and the upper sensor increases by the same amount, and by changing the position of the lower sensor, this disturbance can be completely eliminated.

[0037] With this design, the environmental influence on both sensors is identical and compensates for itself through the subtraction of the measured values. The degree of deflection of the support element and the dynamic changes caused by the vacuum pump have no influence on the thickness measurement result. Possible vibrations generated by the vacuum pump can be compensated for in the same way as the deflection with the lower sensor. By compensating for the deflection of the support element and using the highly thermally stable and torsion-resistant material of the measuring bracket, resolutions in the sub-micrometer range can be achieved.

[0038] Depending on the application, the measuring object can have different mechanical properties. In the case of a soft, porous material, it is possible to integrate a solid measuring insert in the measuring area of ​​the sensors. In this case, a section of the support element or the support plate can be replaced by an insert made of solid material without openings. The advantages of positioning using negative pressure are nevertheless retained, since in the outer area, i.e. in the area without the measuring insert, the same conditions apply as in the case without the measuring insert. Possible air pockets or wrinkles in the area of ​​the measuring insert are removed by the negative pressure in the surrounding areas. The sensors both measure onto the measuring insert instead of the support plate. The measuring insert is only connected to the support plate. The compensation effect is also retained with this technology, as in the case without a measuring insert.

[0039] Thanks to the variable design, objects with a wide range of mechanical properties can be measured offline with sub-micrometer precision. The system is calibrated by referencing the measuring insert or the porous support element or the porous support plate. The reference is verified by observing the thickness value without the measuring object. If the system's subtraction value is zero, no calibration is necessary and the measurement conditions are reproducibly stable. If a deviating result occurs, the support surface and measuring insert must be cleaned. A review of the thickness signal can determine whether measurements can be continued or whether recalibration is necessary.Zeroing the measuring channel for the thickness signal on an evaluation electronics corresponds to a recalibration state and enables repeatability to previous measurements.

[0040] As a result, embodiments of the measuring system according to the invention can form a reliable measuring system with a porous support for measuring the thickness of films.

[0041] There are now various possibilities for advantageously embodying and developing the teaching of the present invention. Reference is made, on the one hand, to the dependent claims and, on the other hand, to the following explanation of preferred embodiments of the measuring system according to the invention and the method according to the invention with reference to the drawing. In conjunction with the explanation of the preferred embodiments with reference to the drawing, generally preferred embodiments and developments of the teaching are also explained. The drawing shows:

[0042] Fig. 1 shows a perspective view of an embodiment of the measuring system according to the invention,

[0043] Fig. 2 in a side view the embodiment from Fig. 1 ,

[0044] Fig. 3 in a side view, cut, the embodiment of Fig. 1 and

[0045] Fig. 4 in a top view, sectioned, the embodiment from Fig. 1.

[0046] Fig. 1 shows a perspective view of an embodiment of the measuring system 1 according to the invention for measuring the thickness of a flat object 2 or a flat sample 2. A non-contact sensor 3a—an upper sensor 3a—is mounted in a sensor holder 4 designed as a measuring bracket 4 and measures against the surface of the flat object 2. The flat object 2 is a section of a thin film whose thickness is measured offline in the test laboratory. The flat object 2 is arranged on a support plate 6 of a support device, which serves as a support element 6 and is in turn positioned on a base body 5.

[0047] Fig. 2 shows the exemplary embodiment in a side view. The measuring system 1 comprises a base body 5, in or on which a support plate 6 is mounted. For this purpose, the base body 5 has webs 7 on which the support plate 6 rests, forming air channels 8. This allows air to be drawn in through passages in the support plate 6 (not shown here). The air channels 8 lead to an air connection 9, which can be connected to a vacuum pump (not shown here).

[0048] The measuring bracket 4 is arranged in the base body 5 – mechanically separated from the support plate 6. The measuring bracket 4 is made of a material with a low thermal expansion coefficient, in this example made of Invar. Mounts 10a, 10b for capacitive sensors 3a, 3b are attached to the measuring bracket 4. The mounts 10a, 10b are designed as circumferential clamps. The upper surface of the support plate 6 serves as the support surface 11 for the measuring object 2. The support plate 6 contains a measuring insert 12 made of solid metal, which is mounted opposite the upper sensor 3a and acts as a reference surface for the thickness measurement. The sensor 3b – a lower sensor 3b – measures from below against the support plate 6 and detects its position.

[0049] Fig. 3 shows the exemplary embodiment in a sectional view. For transporting the measuring system 1, it has a handle 13. The handle 13 is mechanically decoupled from the measuring bracket 4 and firmly connected to the base body 5. The handle 13 has a cable duct 14a in which connecting cable(s) (not shown here) for the upper sensor 3a are routed. The handle 13 is designed such that it can be used, on the one hand, to transport the measuring system 1 and, on the other hand, to protect the measuring bracket 4 against collision. A further cable duct 14b is formed in the base body 5 for connecting cables of the second or lower sensor 3b.

[0050] Fig. 4 shows the embodiment of the measuring system 1 in a sectional plan view with the base body 5 and the measuring bracket 4, which is arranged mechanically decoupled from the base body 5.

[0051] The embodiment according to Figs. 1 to 4 shows a measuring system 1 for measuring the thickness of flat objects 2, comprising a non-contact measuring sensor 3a for detecting the flat object 2 and a support plate 6 with a support surface 11 on which the flat object 2 rests, wherein the sensor 3a is arranged opposite the support surface 11. The support surface 11 has a plurality of passages through which air can be drawn in.

[0052] The support plate 6 is made of a porous material with interconnected pores, and the support plate 6 is connected to a vacuum pump via air ducts. Furthermore, the support plate 6 has a measuring insert 12 made of solid material, i.e., without pores.

[0053] Furthermore, the measuring system 1 has a measuring bracket 4 made of material with a low thermal expansion coefficient. The upper sensor 3a in the embodiment shown here can be a capacitive or optical sensor 3a, with the measuring system 1 having a second sensor 3b that measures from below against the support plate 6. The second sensor 3b serves to compensate for movements of the support plate 6 that change its position relative to the first sensor 3a. From the difference between the signals of the two sensors 3a, 3b, the thickness of the flat object 2 can be measured very precisely and independently of changes in the position of the support plate 6, such as deflection due to the negative pressure.

[0054] With regard to further advantageous embodiments of the measuring system according to the invention and the method according to the invention, reference is made to the general part of the description and to the appended claims in order to avoid repetition.

[0055] Finally, it should be expressly pointed out that the exemplary embodiments described above serve only to explain the claimed teaching, but do not limit it to the exemplary embodiments.

[0056] 1 measuring system

[0057] 2 flat sample, flat object a, b sensor

[0058] 4 measuring brackets, sensor holder

[0059] 5 basic bodies

[0060] 6 Support plate, support element

[0061] 7 bridges

[0062] 8 air ducts

[0063] 9 Air connection a, b bracket

[0064] 11 Support surface

[0065] 12 measuring insert

[0066] 13 Handle a, b Cable duct

Claims

Claims 1. Measuring system (1) for measuring the thickness of flat objects (2), comprising a sensor (3a) which measures the distance to a flat object (2) in a contactless manner and a support device with a flat support element (6) for supporting the flat object (2) on a support surface (11) of the support element (6) during a measurement, wherein the sensor (3a) is arranged for a distance measurement in the direction of the support surface (11), characterized in that the support element (6) has at least one passage extending from the support surface (11) through the support element (6) for sucking air from a region above the support surface (11) through the at least one passage.

2. Measuring system (1) according to claim 1, characterized in that the support element (6) comprises a porous material or is formed from a porous material, wherein one or more passages are formed by a single or interconnected pores of the material.

3. Measuring system (1) according to claim 2, characterized in that the porous material comprises a metal or a ceramic or consists of a metal or a ceramic.

4. Measuring system (1) according to claim 2, characterized in that the porous material is a metal foam or comprises a metal foam, for example porous aluminum or titanium.

5. Measuring system (1) according to one of claims 1 to 4, characterized in that the support element (6) is coupled to a vacuum pump.

6. Measuring system (1) according to claim 5, characterized in that the vacuum pump has a control or regulation for a predeterminable suction force for a flat object (2) placed on the support surface (11).

7. Measuring system (1) according to one of claims 1 to 6, characterized in that the support element (6) has a measuring insert (12) or measuring attachment, each with a closed surface, which forms with its surface a partial area of ​​the support surface (11), wherein the partial area is preferably an inner area of ​​the support surface (11).

8. Measuring system (1) according to one of claims 1 to 7, characterized in that the measuring system (1) has a sensor holder (4) with a low thermal expansion coefficient, wherein the sensor holder (4) can be bow-shaped and / or can be made of Invar or a ceramic or can have Invar or a ceramic.

9. Measuring system (1) according to claim 8, characterized in that the sensor holder (4) is mechanically decoupled from the support element (6).

10. Measuring system (1) according to one of claims 1 to 9, characterized in that the measuring system (1) has a second sensor (3b) which is arranged for distance measurement in the direction of the support element (6).

11. Measuring system (1) according to one of claims 1 to 10, characterized in that the sensor (3a) and / or the second sensor (3b) are capacitive or optical sensors (3a, 3b) or is a capacitive or optical sensor (3a, 3b).

12. Measuring system (1) according to one of claims 1 to 11, characterized in that the measuring system (1) has a base body (5) for supporting or arranging the support element (6).

13. Measuring system (1) according to claim 12, characterized in that the base body (5) has a plurality of webs (7) on which the support element (6) rests, so that air channels (8) are formed between the webs (7), and / or that the support element (6) has a plurality of webs, so that air channels are formed between the webs.

14. Measuring system (1) according to claim 12 or 13, characterized in that the measuring system (1) has a handle (13) connected to the base body (5), wherein the handle (13) preferably has a cable duct (14a) for connecting lines of the sensor (3a, 3b) or the sensors (3a, 3b).

15. Method for measuring the thickness of flat objects (2) with a measuring system (1), in particular with a measuring system (1) according to one of claims 1 to 14, wherein the measuring system (1) has a sensor (3a) which measures the distance to a flat object (2) in a contactless manner and a support device with a flat support element (6) for supporting the flat object (2) on a support surface (11) of the support element (6) during a measurement, wherein the sensor (3a) is arranged for a distance measurement in the direction of the support surface (11), characterized in thatthat the support element (6) has at least one passage extending from the support surface (11) through the support element (6) for sucking air from a region above the support surface (11) through the at least one passage and that the flat object (2) to be measured is sucked onto the support surface (11) during the measurement by means of air sucked through the at least one passage.

Images