Method and apparatus for non-contact and non-destructive measurement of coated surfaces

Abstract

To improve the quality of surface parameter measurements, particularly the measurement of the thickness of coatings applied to a surface, by measuring their infrared radiation. [Solution] An apparatus for non-contact and non-destructive testing of a surface by measuring its infrared radiation in response to thermal excitation comprises one or more electromagnetic radiation sources (220), each adapted to emit excitation radiation directed toward the surface (17) to be tested. One or more detectors (120) equipped with a pixel array (121) are directed toward the surface (17) and record the response to the excitation radiation as a function of time. A control unit (60) receives values ​​from the pixels and determines the time at which the values ​​were measured, taking into account non-gate measurements in the pixel array (121). The control unit (60) also controls the pulsing of one or more radiation sources (220).

Description

[Technical Field]

[0001] The present invention relates to a method for non-contact and non-destructive measurement of surface parameters of an object. The method also relates to an apparatus for performing such a method. [Background technology]

[0002] Non-contact surface testing, based on the generation and measurement of temporary, periodic heating and cooling processes, utilizes an excitation source to heat the surface under test, as well as an infrared detector to measure the infrared radiation emitted from the heated surface. If electromagnetic radiation in the ultraviolet, optical, or infrared range is used for excitation, this method is called photothermal testing or photothermal radiation measurement.

[0003] One important parameter that can be measured using this method is the thickness of the coating applied to the surface.

[0004] U.S. Patent Application Publication 2006 / 0096677 relates to different methods and systems for temperature measurement and heat treatment, particularly for measuring heating results on a disk-shaped wafer from both sides, with multiple electromagnetic radiation sources positioned above and below the wafer.

[0005] A further apparatus is described in U.S. Patent Application Publication No. 2013 / 0037720, which uses one or more non-coherent electromagnetic radiation sources, a detector positioned on the detection axis and including a measurement area, a test area defining a region of the test surface to be measured, and an imaging device positioned on the detection axis to map the test area onto the measurement area of ​​the detector. The radiation sources are adapted to generate pulsed or intensity-modulated excitation radiation, for example, a flashlight directed onto the surface to be tested in the test area.

[0006] U.S. Patent Application Publication 2019 / 0318444A1 describes a method for measuring the temperature decay of a coating using a pixel-based detector. Here, the coating is moved across a radiation source and a detector. Temperature values ​​at different time points after irradiation are recorded using the travel time between the irradiation site and the detection site. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] U.S. Patent Application Publication No. 2006 / 0096677 [Patent Document 2] U.S. Patent Application Publication No. 2013 / 0037720 [Patent Document 3] U.S. Patent Application Publication No. 2019 / 0318444A1 [Overview of the project] [Problems that the invention aims to solve]

[0008] In some aspects, the objective is to improve the quality of surface parameter measurements, particularly the quality of measurements of the thickness of coatings applied to a surface, by measuring their infrared radiation.

[0009] This objective is achieved by the method of claim 1. [Means for solving the problem]

[0010] Therefore, this method includes at least the following:

[0011] Radiation time t p Then, radiation pulses are emitted from at least one electromagnetic radiation source and directed onto the surface to be measured. Such radiation pulses temporarily heat the surface. The radiation pulses can be emitted in a beam along the associated radiation axis. The radiation pulses have an emission time t p It is generated by n, where n is the pulse exponent.

[0012] Receive detected radiation emitted by a surface in response to radiation pulses by at least one detector, the detector including a plurality of pixels. The detected radiation typically depends on the temperature of the surface.

[0013] Read out the value v of the pixels of the detector in a series of consecutive frames k. These values represent the signal from the pixels at time t i,j,k i.e., they represent the state of the pixels at time t i,j,k such as the thermal state. Time t i,j,k depends on the time t of each frame k i,j,k as well as the position i, j of the pixels within the detector. In other words, time t k is a non-constant function of the pixel positions i, j. i,j,k

[0014] Determine the time t from the position i, j and the frame k by the control unit. In other words, the position i, j as well as the time t k are used to determine the time t i,j,k from time t k to time t i,j,k

[0015] Determine the parameters by the control unit using the value v i,j,k and these times t i,j,k

[0016] In other words, this method takes into account that the readout pixel signal value v i,j,k represents the pixel signal not only at the time t of the frame k k but also at the time t that depends on the position i, j of the pixels within the detector. i,j,k

[0017] This is the case in many pixel-based detectors, especially pixel-based infrared detectors, where the readout is at the time t of the frame kThis method takes into account that the signal value is not "gated" across all pixels, meaning it does not represent the pixel value at a common time for all pixels. Rather, at least some values ​​of different pixels are measured at different times. Therefore, this method uses a more precise time for the measurement, and thus the value v i,j,k This will allow for a more accurate analysis of the time series.

[0018] The detector, value v i,j,k But time t i,j,k This method is particularly useful for bolometric detectors that describe the temperature of pixels, such as microbolometers. In such detectors, the values ​​are typically not gated, or at least not gated across the entire pixel array, i.e., the value v i,j,k different time t i,j,k This represents the pixel temperature (and therefore the surface temperature) at that point.

[0019] In photothermal radiation measurements, it is advantageous that the detector is fitted to detect wavelengths larger than 1 μm, for example, between 1 μm and 25 μm. For example, a microbolometer would be fitted to detect wavelengths between 4 μm and 20 μm, particularly between 8 μm and 12 μm.

[0020] Radiation time t p To simplify the evaluation of how a surface reacts to a given radiation pulse n at t, p The value v over time i,j,k The decay of can be analyzed. To do so, time t i,j,k and radiation time t p The analysis can be performed over several frames k as a function of relative time between them. Therefore, this method allows us to Radiation time t p For a given radiation pulse, the time offset t' is for several frames k between the given radiation pulse and the next radiation pulse. i,j,k =t i,j,k -t pThe steps to determine, Time offset t' i,j,k Value v as a function of i,j,k The steps include determining the parameters from the decay, It can include...

[0021] Many suitable detectors, for a given frame k, will determine the value of the detector's pixels v i,j,k It generates data packets containing the frame k time t. k This can also be shown. This time can be derived, for example, from the time it takes for a data packet to be transmitted to the control unit, or it can be encoded as a time value in the data packet (for example, based on a shared time reference between the control unit and the detector).

[0022] If the frame is synchronized with the excitation pulse, the value v i,j,k Processing is easier. Therefore, in some embodiments, this method is at least the following, namely, The control unit controls the value v for each frame k. i,j,k Includes at least one frame k time t k A step of receiving at least one data packet that indicates, The control unit determines one or more time t of the received data packets k The radiation time t for subsequent excitation pulses is a function of t. p The steps to determine, It can include...

[0023] To further facilitate data analysis, the pulse emission time t p The subsequent radiation pulse should be determined so that it falls between two consecutive frames k1 and k2. Therefore, the control unit determines the radiation time t of the "subsequent" excitation pulse so that it falls between the frame periods of the two consecutive frames k1 and k2. pThis can be determined. The "frame period" is defined as follows: each frame period is defined for all pixels i,j, and for k=k1 or k=k2, time t i,j,k It extends between the minimum and maximum values.

[0024] For example, the emission time t of the subsequent excitation pulse p This is the time t derived from at least one previous frame k data packet. k This can be determined from this, which allows the system to adapt to the time of the frame. This is especially useful if the detector is in "free continuation" mode, that is, if its frame is not synchronized with the outside world.

[0025] Time t of frame k k is the value v i,j,k The control unit can determine this from the arrival time of the data packet containing the data. However, to account for the signal delay from the measurement head to the control unit, the control unit adds a non-zero offset O. t It can be added.

[0026] This method can also be used to process the values ​​of two frames k' and k'' recorded from different first and second positions relative to the surface, for example, from different positions of the same detector relative to the surface, or from two different detectors, but at different positions relative to the surface. In this case, this method does at least the following: The control unit controls the value v of the first frame k'. i’,j’,k’ and the value v of the second frame k'' i’’,j’’,k’’ Upon receiving, the first frame and the second frame are from different first and second positions, a) By the same detector being moved between different positions, or b) Two different detectors placed in different positions, The steps to be recorded, The control unit detects the radiation from the same location on the surface, and pixels P in the first frame k' and second frame k'' receive the radiation. i’,j’ and P i’’,j’’ The step of determining the pair, It can include...

[0027] Determining such pairs of pixels makes it possible to identify the pixels that receive light from the same point on the surface while viewing it from different directions. Therefore, the measurement results derived from the pairs of pixels can be used to gain a better understanding of the parameters at that point, for example, to calculate a more accurate version of the parameters.

[0028] In this case, this method is The control unit records several first frame k' values ​​v from a first position. i’,j’,k’ and the value of some second frame k'' recorded from the second position v i’’,j’’,k’’ The steps to receive, The control unit, a) Pixel P in the first frame i’,j’ value v i’,j’,k’ and these times t i’,j’,k’ Using this, we make the first estimation of the parameters, and b) Pixel P in the second frame i’’,j’’ value v i’’,j’’,k’’ and these times t i’’,j’’,k’’ We use this to determine the second estimate of the parameter, and pixel P i’,j’ and P i’’,j’’ However, the step is a pair of steps that receive detected radiation from the same location on the surface, The control unit performs the steps of combining the first and second estimations of the parameters to obtain the combined parameters, It can include...

[0029] This is based on the understanding that processing only the values ​​from the first frame, and then only the values ​​from the second frame, in order to obtain the first and second estimates, can result in a more accurate estimate. Only after this process are the two estimates combined.

[0030] As mentioned, the first frame k' and the second frame k'' can be recorded by two different detectors, which can be positioned at different locations relative to the surface.

[0031] Alternatively, the first frame k' and the second frame k'' can be recorded by the same detector. In this case, this method involves moving the detector from a first position to a second position relative to the surface between recording the first frame k' and the second frame k''. In this context, "moving the detector relative to the surface" means relative movement, which can be achieved by moving the detector and / or moving the surface in order to change the relative position between these two.

[0032] In another embodiment, as summarized below, the objective is to improve the measurement of coating thickness or other parameters of different objects. In some embodiments, the objective is to detect the coating thickness or other parameters of specific features of a coated object, such as edges, cavities within the object, and corners.

[0033] In this embodiment, a method for non-contact and non-destructive measurement of a surface by measuring its infrared radiation may include the following steps:

[0034] At least one electromagnetic radiation source is provided. The radiation source is adapted to emit excitation radiation in an excitation beam along a relevant radiation axis that can be directed onto the surface being measured. The number of electromagnetic radiation sources depends, in particular, on the surface being measured, if the object having that surface is a 3D object, then the surface being measured has different orientations.

[0035] At least one detector is provided and positioned at a measurement location, which is located on a detection axis oriented toward the surface to be measured. In response to radiation emitted from an electromagnetic radiation source and impacting the surface to be measured, the detector receives detection radiation emitted by the surface to be measured. The detector includes multiple pixels.

[0036] A control unit is provided and connected to at least one detector and an electromagnetic radiation source.

[0037] This method defines at least two measurement locations where a detector receives radiation from a surface after radiation emission from an electromagnetic radiation source. It is possible to have different detectors at these measurement locations, or to move the detectors between the measurement locations, or to move the object being measured so that the detectors are positioned at these measurement locations.

[0038] The control unit can synchronize the radiation signals received from at least two measurement locations for a given pixel of the detector for each of the at least two measurement locations by applying a time shift to a common point in time based on the start time of the detected radiation signal for radiation emission from an electromagnetic radiation source.

[0039] If all measurement positions are occupied by separate detectors, the total radiation response from the surface can be detected in a single measurement in a single positioning step. If only one detector is provided, the total radiation response from the surface should be detected in a number of measurements in positioning steps equal to the number of measurement positions. If a limited number of detectors are provided, this can result in a reduced number of measurements in a reduced number of positioning steps; for example, with four detectors at the four corners of the object being measured, two measurements are required: the first for all four corners and the second for the remaining four corners.

[0040] For more than one measurement, i.e., several positioning steps, the radiation signal can be transmitted to the control unit along with time information from the electromagnetic radiation source related to the emission of radiation at each positioning step.

[0041] In some embodiments, the control unit synchronizes radiation signals received from each of several pixels of the detector by applying a time shift to a common point in time for the detector based on the start time of the detected radiation signal, which may be a first pixel in a first column and row, or it may be a different pixel, in particular, opposite a predetermined pixel from the synchronization between detectors.

[0042] In a further embodiment, an apparatus for non-contact and non-destructive measurement of a surface by measuring its infrared radiation may include: one or more electromagnetic radiation sources, each adapted to emit excitation radiation in an excitation beam along a relevant radiation axis that can be directed toward the surface to be measured; one or more detectors at one or more respective measurement positions, positioned on a detection axis directed toward the surface to be measured and receiving detection radiation emitted by the surface to be measured in response to radiation emitted from the electromagnetic radiation sources and impacting the surface to be measured; and a control unit connected to the detectors and electromagnetic radiation sources, each of at least one detector including a plurality of pixels. The control unit is configured to position at least one detector at at least two measurement positions, each of which the detector is positioned to receive radiation from the surface to be measured after the emission of radiation from the electromagnetic radiation sources, and the control unit is configured to synchronize the radiation signals received from at least two measurement positions for a given pixel of the detector for each of the at least two measurement positions by applying a time shift based on the start time of the detected radiation signal in response to the emission of radiation from the electromagnetic radiation sources to a common point in time.

[0043] In some embodiments, the control unit separately shifts the time of each detector based on the start time of the detected radiation signal across all pixels P i,j By applying this to a common point in time, multiple pixels P of this detector i,j The device can be configured to synchronize the radiation signals received from it. These features can be independent and relate only to the apparatus for non-contact and non-destructive measurement of a surface by measuring its infrared radiation as described in the preamble of claim 18.

[0044] When these features are realized in the apparatus described in claim 19, this synchronization may apply specifically to a given pixel, ranging from synchronization between detectors.

[0045] Multiple detectors and / or electromagnetic radiation sources can be positioned at predetermined distances along the detection axis at the corners, edges, or continuous surfaces of the covered object. The detectors and electromagnetic radiation sources can be combined to form a measuring head.

[0046] The observation cones of detectors positioned at two adjacent measurement locations can overlap in the area where the surface to be measured can be placed. This allows for improved measurement of areas that are at a certain distance from the detector and therefore have lower resolution.

[0047] The radiation source can be positioned concentrically with the detection axis of the associated detector.

[0048] The apparatus may include a predetermined number of detectors configured to be positioned around the object to be measured, and the observation cones of the detectors are oriented such that the entire surface of interest of the coated object lies within the field of view of at least one of the observation cones. The surface of interest may be the entire surface of the object or a portion thereof, which may be, for example, an area where the quality of the coating should be checked.

[0049] A predetermined number of detectors is one or more detectors, which can be positioned around an object being measured in a series of separate image acquisition events (i.e., frame acquisition events) so that after all image acquisition events, the entire surface of interest of the object can be covered. Between two image acquisition events, one or more detectors are moved (7) and / or rotated relative to the object being measured.

[0050] A predetermined number of detectors can be one or more detectors, and between two image acquisition events, the object is moved and / or rotated to position it relative to one or more detectors, thereby achieving positioning of the observation cone. After all image acquisition events have occurred, the entire surface of interest of the covered object has been in the field of view of at least one of the observation cones at least once.

[0051] Such a device may include multiple detectors and / or electromagnetic radiation sources positioned at predetermined distances along the detection axis at the corners, edges, and / or across continuous surfaces of the covering object.

[0052] The observation cones of two adjacent detectors, or the observation cone of one detector moving between two subsequent positions, or the observation cone of one detector between two subsequent positions of a moving and / or rotating object, can overlap in areas of the object's surface. Such overlapping areas, which can be measured by more than one detector, allow for improved measurements.

[0053] In a further embodiment of the apparatus, the radiation source can be positioned concentrically with the detection axis of the associated detector.

[0054] This apparatus may include a predetermined number of detectors configured to be positioned around an object having a surface to be measured, with the observation cones of the detectors oriented such that the entire surface of interest of the coated object lies within the field of view of at least one of the observation cones. Such a surface of interest may be only a portion of the object's entire surface. If the entire surface of the coated object is covered, this is called a solid angle of 4π.

[0055] With one or more detectors, complete coverage can be achieved when one or more detectors are positioned around the object being measured in a series of separate imaging events, covering the entire surface of interest of the object after all imaging events, by moving and / or rotating one or more detectors relative to the object being measured between two imaging events. This approach reduces the number of detectors required at the cost of subsequent imaging events, but this means that the measurement will be slower, and the illumination conditions with the flashlight must be set to ensure that an illumination level above the illumination threshold that produces a sufficient illumination response is achieved.

[0056] When an object is moved and / or rotated between two image acquisition events to position it relative to one or more detectors and achieve positioning of the observation cone, a further 4π approach is applied to a predetermined number of detectors of one or more detectors, provided that after all image acquisition events have occurred, the entire surface of interest of the coated object has been in the field of view of at least one of the observation cones at least once. Instead of moving the detectors, it is also possible to move and rotate the coated object being measured.

[0057] For the entire 4π approach, since the detector contains multiple pixels, the control unit can be configured to synchronize radiation signals received from multiple pixels from different detectors by applying a time shift to a common point in time based on the start time of the detected radiation signals.

[0058] In all embodiments, a thickness map can be provided as a result of the measurement. The thickness map spatially resolves the thickness of an object at a surface of interest. Such a thickness map allows for a rapid visual check of the quality of a coating measured by this method and the apparatus according to one embodiment. In addition, such a visual representation allows those skilled in the art to detect anomalies in the coating and correct the coating parameters to achieve better results for subsequent coatings.

[0059] The above method can be carried out by a control unit programmed to do so.

[0060] The present invention also provides an apparatus adapted to perform this method, in particular, with at least the following elements, namely: A radiation source configured to emit pulsed excitation radiation onto the surface to be measured, A detector arranged to detect radiation emitted by a surface in response to excitation radiation, comprising a plurality of pixels, A control unit configured and programmed to perform this method, Regarding devices including...

[0061] Further embodiments of the present invention are described in the dependent claims.

[0062] Preferred embodiments of the present invention will now be described with reference to the drawings, but these are intended to illustrate and not limit the current preferred embodiments of the present invention. [Brief explanation of the drawing]

[0063] [Figure 1] This is a schematic perspective view of multiple measuring heads and a covering object with a parallelepiped shape. [Figure 2] This is a schematic perspective view of multiple measuring heads and a cylindrical coated object. [Figure 3] This diagram shows the radiation levels measured over time for multiple pixels on the measurement head. [Figure 4] This is an illustration of the pixel array of the measuring head, along with the associated measurements and associated time stamps. [Figure 5] This is a schematic perspective view of a covering object with multiple measuring heads and a spherical shape. [Figure 6] This is a highly schematic detail diagram showing the cross-section of an object, the measuring head, the surface area of ​​the pixels on the measuring head, and the measured thickness of the coating on these measuring heads. [Figure 7] This figure shows a further embodiment of an apparatus for non-contact and non-destructive surface testing, with fewer measuring heads and a configuration for reorienting the measuring heads and / or objects. [Figure 8] These are two figures showing radiation levels measured over time for multiple pixels at two different measurement locations. [Figure 9] This diagram shows the object to be measured and the four measuring heads at four measurement positions. [Figure 10] This diagram shows the object to be measured and a single measuring head at a specific measurement position, illustrating the rotation of the object to move the measuring head to a specific further measurement position. [Figure 11] This figure shows a schematic embodiment of the device. [Figure 12] This figure shows examples of several timing aspects. [Figure 13] This diagram shows several steps in the method for operating the device. [Modes for carrying out the invention]

[0064] Figure 11 shows a schematic diagram of a device having one or more camera-type measuring heads 20 for examining the surface 17 of an object 10.

[0065] Each measuring head 20 (hereinafter also referred to as "IR sensor") measures pixel P i,jThe detector 120 includes an array 121. While this technique can also be used with a one-dimensional pixel array, the array 121 can be a two-dimensional array for more efficient surface evaluation. The pixels detect, for example, IR radiation in the infrared (IR) wavelength range described above.

[0066] As mentioned, the detector 120 can be a microbolometer, where pixels absorb wavelengths of interest, and each pixel is equipped with a temperature sensor to detect the temperature increase due to absorbed irradiation. However, other types of IR-sensitive pixels can be used in the same way.

[0067] Furthermore, each measuring head 20 may include an imaging system 122 adapted to project a portion of the surface 17 onto the pixel array 120 along the detection axis 28.

[0068] The apparatus also includes at least one radiation source 220 adapted to generate radiation pulses. The radiation source 220 may be a flashlight that generates electromagnetic radiation that is at least partially absorbed by the surface 17. The light is optionally emitted forward toward the surface 17 of the covered workpiece through a diffuser 223 and an optional measuring window 14.

[0069] The measurement window 14, if present, should have spectral transmittance adapted to transmit radiation pulses and radiation returning from the surface 17.

[0070] The radiation source 220 can be a high-peak-intensity flashlight or laser suitable for causing sufficient localized heating of the surface 17. A diffuser 223 can be provided to distribute the light from the radiation source 220 more evenly. Instead of, or in addition to, the diffuser 223 may be provided with a spectral filter to block unwanted radiation from the radiation source 220, such as hard UV radiation.

[0071] In the illustrated embodiment, the radiation source 220 is located on the measuring head 20, for example, as described in U.S. Patent Application Publication No. 2013 / 0037720A1. The radiation source 220 can be positioned concentrically with respect to the detector 120 and the detection axis 28.

[0072] In the illustrated embodiment, each measuring head 20 includes a radiation source 220. However, if there are several measuring heads 20, only a subset of these heads may include radiation sources.

[0073] In yet another embodiment, one or more radiation sources 220 can be provided separately from the measurement head.

[0074] The apparatus further includes a control unit 60 for controlling its components. The measuring head 20 may include a head controller 29 for controlling the components within the measuring head 20.

[0075] The control unit 60 may include, for example, a microcontroller and / or a local computer and / or a remote computer (server). For example, it may monitor any user-operable controls of the device and drive the display 61. In particular, it may communicate with the head controller 29 to receive data from the detector 120 as described below. It may be adapted to process the measured data, as also described below.

[0076] During operation, the control unit 60 operates the radiation source 220 to generate radiation pulses, and subsequently over several frames k, pixels P i,j value v i,j,k This process is performed. Thus, for each pixel, this monitors the temperature decay after the radiation pulse, as known from photothermal thickness measurement techniques. This makes it possible to generate a map of the quality or thickness of the coating on surface 17.

[0077] However, for good accuracy, this type of signal processing is based on the duration of the radiation pulse (in this case, the radiation time t). p ) and pixel P in frame k recorded after the radiation pulse. i,j Sampling time t i,j,k We benefit from knowing the precise temporal relationship between [the two events].

[0078] However, as mentioned above, the time t when the frame was recorded k Even if we know (for example, the start time of the frame), the sampling time t i,j,k This can be a function of pixel coordinates i,j. This is due to the fact that, in contrast to CCD cameras, many IR-sensitive detectors do not provide overall "gating" for all pixels. Rather, pixel P i,j The pixels are sampled continuously (individually or in groups). For example, if pixels are read continuously row by row (see Figure 4), within each row, and column by column, with a constant time Δt between each pixel, then a given pixel P in frame k i,j Sampling time t i,j,k teeth, t i,j,k =t k +Δt·((j-1)+n·(i-1)) (1) Given by , n is the number of pixels per row (i.e., n is the number of columns), and i,j are 1-based pixel coordinates.

[0079] It should be noted that rules other than Equation 1 can be applied depending on the detector system. However, generally, time t i,j,k i, j, and t k It becomes a non-constant function of, that is, t i,j,k =f(i,j,t k ) (2) And f is a known function.

[0080] In some embodiments, time t i,j,kis determined by the head controller 29 and then, for each pixel individually or by providing appropriate timing parameters, the value v i,j of pixel P i,j,k can be transmitted from the detector 120 to the control unit 60 together with it.

[0081] However, in other embodiments, the head controller 29 may not be equipped to determine the time t i,j,k This is particularly true when using a standard detector and / or when there is no common time base between the control unit 60 and the head controller 29. In such cases, the head controller 29 will only transmit to the control unit 60 a data packet P containing an array of values v i,j,k for frame k. Such a data packet will also include frame time data indicating the time t k of the frame. This frame time data can be explicitly encoded in the data packet, for example, for some time frames shared between the detector 120 and the head controller 29, or it can be transmitted implicitly, i.e., because it can be derived (at least approximately) from the time when the head controller 29 transmitted the data packet.

[0082] FIG. 12 shows some aspects of the timing in one example. This figure shows the time t along its horizontal axis and has three rows. The top row, labeled R, shows the pixel readout of the detector 120. The second row, labeled P, shows the data packet sent from the head controller 29 to the control unit 60, and the third row, labeled L, shows the time of the radiation pulse generated by the radiation source 220.

[0083] As can be seen from row R, the actual pixel readout starts at time t k for frame k and is continuous and can extend over the frame period, for example, with a duration t1. The value v i,j,k is at time ti,j,k is a readout at

[0084] In a simple approach, the head controller 29 is adapted to repeatedly read out frames at a normal frame rate such as 60 hertz, as shown. During the frame period 80, there can be a gap of duration t’1 during which pixels are not read out, as shown.

[0085] The readout value v of the frame i,j,k can then be transmitted to the control unit 60 as a data packet 81 via, for example, USB, Ethernet, or another communication channel. This transmission is typically slower but has a substantially constant time offset k O O t = t’ k - t k (3) with a time t’ k occurring at

[0086] The duration t2 of the packet 81 may be different from t1 and depends on the transfer speed of the data transmission.

[0087] Even if the head controller 29 and the control unit 60 do not share a common time base and the head controller 29 does not explicitly embed the frame time t k into the data packet 81, the control unit 60 can determine the frame time t k from the above equation (3) at least approximately, by the arrival time t’ k of the data packet 81, the "packet time".

[0088] (Instead of using the start times t k , t’ k , other timing parameters such as the center or end of the frame and the packet can be used.)

[0089] The control unit 60 is the emission time t during which the radiation source (220) emits radiation pulsesp It can also be controlled.

[0090] As mentioned, to facilitate data analysis, each radiation time t p It should be placed slightly before frame period 80, and advantageously in the gap between two consecutive frame periods of 80.

[0091] Therefore, when the radiation pulse L arrives, the control unit 60 sets the start time t of the next frame. k Predicting that the radiation pulse L is t p The predicted start time t is set so as not to overlap with the first frame period 80 after that. k The time before t p This can generate radiation pulses.

[0092] For example, if the length of the radiation pulse is t L If so, t p This is the predicted start time t of the first frame period 80 that follows. k at least 1.5·t L It is calculated to be the previous one, thereby reducing the risk of duplication. On the other hand, in addition, or instead, t p This is the predicted start time t of the first frame period 80 that follows. k 8·t L The calculation can be performed as follows:

[0093] For accurate measurement, length t L It should be short, for example, less than 1ms.

[0094] In some embodiments, as described, t p This allows the calculation to be performed so that the radiation pulse L falls within the gap between two consecutive frame periods 80, making it possible to use the frame period 80 preceding the radiation pulse for the previous decay measurement and / or pre-pulse measurement, and the one following the radiation pulse for the next decay measurement.

[0095] Time tp For a more precise selection, the control unit 60 is offset O t You should know (Equation (3)).

[0096] Offset O t This can be determined in advance and, for example, derived from the specifications of the detector 120 and the transmission channel between the detector 120 and the control unit 60.

[0097] However, in other embodiments, a time offset O is used with calibration measurement. t It is possible to make a decision. In order to do so, a) Packet time t' k Regarding generating light pulses L at different times, and b) The value of the next arriving data packet 81 v i,j,k Monitoring Test measurements can be performed using this method.

[0098] If the light pulse falls within the frame period of 80, the pixel value v received in step b) i,j,k This will show the temperature increase and decrease across different pixels i,j. In this case, based on equation (1) or (2) and equation (3), the parameter O t A model with the following characteristics can be set up to predict the rise and fall of the signal across frames, and the measured result can be O t It can be adapted.

[0099] Figure 13 shows some of the steps that can be performed during measurement.

[0100] In step S10, the radiation pulse L is emitted for a duration t p It is released, t p For example, as determined above.

[0101] In step S12 (which may come after step S10, or may overlap with step S10 if frame recording also begins before the radiation pulse), frame k is recorded.

[0102] For each frame k, the pixel value v i,j,k This is read in step S14.

[0103] In step S16, the pixel value v i,j,k These are transmitted to the control unit 60, and they arrive at a time different from these recording times.

[0104] In step S18, the control unit 60, as described above, time t i,j,k To decide.

[0105] Steps S14 to S18 are repeated for all frames k to be recorded for a given radiation pulse.

[0106] Time t p To analyze the thermal response of surface 17 to a radiation pulse, the temperature value v after the pulse was used. i,j,k The decay of is important. This analysis is based on the pulse time t. p It is best performed in the time frame for . Therefore, in some embodiments, the control unit 60 radiates time t p For a given radiation pulse, the pixel values ​​v for several frames k following the pulse i,j,k Time offset t' i,j,k =t i,j,k -t p It is adapted to determine the time offset t'. Then the control unit 60 determines the time offset t'. i,j,k Value v as a function of i,j,k The parameters of interest can be determined from the damping. This determination allows us to parameterize the thermal model of the surface by the value v i,j,k (t' i,j,k It may include conforming to the requirements.

[0107] Optionally, in such analysis, the value of k of at least one frame prior to the radiation pulse v i,j,k It can also be used.

[0108] This apparatus and method can be used to measure various parameters of a coated surface.

[0109] As mentioned, the important parameter is the thickness of the coating on the surface.

[0110] Given pixel P i,j To measure the coating thickness at the point where it receives radiation, the control unit 60 uses pixels P across frame k to adapt the thermal model of the coating and its substrate. i,j value v i,j,k (t' i,j,k ) can be adapted to use. The coating thickness is a parameter of this model, and its value can be determined during the adaptation process.

[0111] For example, if the thickness of a coating is known but its composition can change, another parameter that can be measured is the composition of the coating. In this case, again, the model is fitted to the measurements, and the composition is one of the fitted parameters of the model.

[0112] Other parameters include surface porosity, surface composition, or any other parameters that affect how the temperature decays after a radiation pulse.

[0113] The parameter may be another parameter that can be derived from the types of parameters described above, such as a surface quality parameter or an index of coating defects.

[0114] As shown in Figure 11, the device may include several measuring heads 20. In this case, at least some area 105 of the surface 17 can be observed by at least two of the measuring heads 20, as will be described in more detail below, and these can be used to obtain more accurate results.

[0115] Furthermore, if there are several measurement heads 20 with overlapping fields of view, these can be set to the same time t to make it easier to measure the duration of radiation pulses with respect to the frame. k It can be synchronized to record frames.

[0116] Next, we will describe some examples demonstrating applications and further variations.

[0117] Figure 1 shows a schematic perspective view of an object 10 having a coated surface 17 in the shape of a parallelepiped, with multiple measuring heads 20. The shape of the coated object is not usually a specific simple geometric object, of course, but includes several different geometric features. In this sense, Figure 2 shows a schematic perspective view of a coated object in the shape of a cylinder 10' with multiple measuring heads 20, and Figure 5 shows a schematic perspective view of a coated object in the shape of a sphere 10'' with multiple measuring heads 20. Thus, reference numeral 10 is used for any such object that usually has a flat or continuous surface, edges and corners. Further deviations from a simple continuous surface may be, for example, cavities, depressions and embossments. Actual objects may include some and combinations of the surface features shown in these drawings. Such coated objects may have corners 11 and edges 12, which increases the need for thorough checking and assurance of the coating.

[0118] Each measuring head 20 may include at least an irradiation sensor, formed by an IR-sensitive detector 120 having multiple pixels, as described above, and may include a radiation source, in particular, a flashlight 220 as described above. In further figures, such a radiation source 220 is shown arranged around the detector 120, but other configurations are possible, as will be described below.

[0119] The measuring head may have multiple radiation sources, or it may share a radiation source with one or more irradiation sensors.

[0120] The measuring head 20 may also include two or more irradiation sensors, for example, arranged around the central radiation source 220.

[0121] To improve the accuracy of the recording, a separate detector 120, or simply a reference numeral 20, may be provided as part of the measuring head for each angle 11.

[0122] If the covering object 10 is very long, for example, one or more additional measuring heads 20 can be provided, depending on the length of the edges, and positioned to be oriented toward the edges 12 between the corners.

[0123] It is also possible to reduce the number of sensors 20 by rotating and oriented the object 10 being checked with relative movement to the measuring head 20, so that the measuring head 20 continuously checks all corners 11 and edges 12.

[0124] An additional measuring head 20 can be placed on the fixed and presented object for continuous checking. This will be explained in relation to Figure 7.

[0125] Figures 1, 2, and 5 through 7 each show the condition of the object being checked and the measuring head 20 positioned at the moment of illumination of the object and measurement of its radiation response. Reference numeral 20 is used to indicate a measuring head equipped with an IR sensor (optionally equipped with a radiation source), while reference numerals 21, 22, and 23 are used if the specific location of such a measuring head equipped with an IR-sensitive detector is shown in the drawings.

[0126] Each measuring head 20 is equipped with a surrounding measuring cone (the term “cone” advantageously also covers a variety of other volumetric structures, e.g., pyramids) during the measurement cycle, each having detection axes 25, 26, or 27 directed directly toward a corner, edge, and / or continuous surface. The detector 120 of the measuring head 20 “sees” the surface of an object by detecting infrared radiation emitted or reflected from different areas of the surface. Each sensor captures this radiation through an imaging system 122, for example, as shown in Figure 11, which directs the radiation onto a pixel array 121, with each pixel corresponding to a specific area of ​​the object. The field of view of the detector 120 of each measuring head 20 is determined by the area it can observe, and the resolution of the detector determines how finely the surface is divided into detectable areas.

[0127] To ensure that the entire surface 17 of an object is measured, multiple measuring heads 20 can be positioned around the object 10. These fields of view can overlap, enabling comprehensive coverage. This overlap is particularly useful for capturing entire critical features such as edges and corners. For example, as seen in Figure 6, a point on an edge may be within the detection range of multiple detectors 120, for example, one oriented along the edge and another covering an adjacent surface. Similarly, a point on a corner may be observed by a detector oriented toward an adjacent surface.

[0128] Each detector 120 can collect a series of values ​​representing the radiation from its assigned portion of the object's surface 17. These values ​​are combined to form a complete representation of the infrared radiation across the entire surface 17. This configuration ensures that every point on the object, from flat surfaces to complex geometric shapes such as corners and edges, is within the detection range of at least one sensor, providing accurate and continuous coverage.

[0129] For example, any surface point, such as point 16 midway on the edge 12 between two corners 11, is located within the detection cones of at least two detectors 120, for example, two angle-oriented sensors or one angle-oriented sensor and one sensor oriented toward the intermediate edge 12. Multiple measuring heads 20 are arranged so that the entire surface 17 of the coated object to be measured is covered by at least one measuring head 20. In other words, the number of measuring heads 20 can be selected so that for every point on the entire surface 17 of the coated object, there is a detected value measured after the object is irradiated.

[0130] The measurement itself primarily uses the irradiation level detected after reaching a peak value of 44, but it may be advantageous to begin detecting the irradiation before the flashlight (i.e., the radiation pulse) is induced, especially in order to detect the peak value of 44. Such points are not points in a mathematical sense, of course, but predetermined regions around such mathematical points depending on the resolution of the sensor. This is also true for edge points and corner points, which actually form rounded regions at the edge or corner points (because they are covered by a coating of finite thickness).

[0131] The radiation source 220 can be installed separately or, for example, around the measurement head 20. Similar to the detector, the radiation cone of the radiation source must cover the entire area being measured, and if several radiation sources are used, there must be overlap in the radiation cones. This ensures that the entire measurement area is covered, while simultaneously increasing the irradiation energy in areas further away from the radiation source.

[0132] Figure 4 illustrates the pixel array of the measuring head, along with associated measurements and associated time stamps. Each detector 120 contains an array of sensor pixels oriented toward the surface being inspected. Each square 200, 201, 211, and 212 represents a pixel in the pixel array 121 and relates to the smallest measurable area portion of the object. Different measurable areas do not necessarily have the same surface size.

[0133] The radiation emitted by an object during and after irradiation can be detected pixel by pixel at measurement intervals defined for each pixel, as described above.

[0134] Detector 120 can have a predetermined frame refresh rate, and each frame has a value v for all pixels. i,j The entire array is delivered, i,j is P 1,1 From P m,n These are pixel coordinates in the ranges of 0 to m-1 and 0 to n-1, respectively. Pixel P i,j The start of the measurement interval for this is t (i-1)*n+j It is marked as such.

[0135] After the frame cycle is complete, the cycle starts again at the first pixel, 211.

[0136] Pixel value v i,j,k The time t to record i,j,k This can be calculated using equation (1) or (2) above. Figure 3 shows an alternative diagram illustrating this.

[0137] In Figure 3, curve 41 is pixel P i,j This represents the value over time for [the relevant factor].

[0138] Figure 3 shows a graph of time-series measurements for multiple such pixels on one measuring head 20. The horizontal axis in Figure 3 represents time before correction by equation (1) or (2).

[0139] The pixel measurement value starts at a high response value (marked here as 44) depending on the moment in time the flashlight illuminates the background, and then decreases to the end of the measurement (marked around 45). Pixel P i,j Line 41 for is not a continuous curve, but pixel P i,j The irradiation response for P consists of discrete values ​​when read out. Since the sensor is read out continuously, 1,1 From P m,nThe lines for different pixels up to are time-shifted. As mentioned, Figure 3 shows the measured values ​​v i,j This is not a time-synchronous representation (i.e., there is no modification to equation (1) or (2)).

[0140] In general, and for all embodiments described herein, if there are several measuring heads 20, 21, 22, then one value v for each of them i,j,k time t i,j,k For example, this can be determined by the control unit 60 using equations (1) or (2) and (3), but depending on the hardware, Δt and / or O t It may be necessary to apply different parameters, such as different values ​​for each measurement head.

[0141] Furthermore, if there are several measuring heads 20, 21, and 22, these frame captures can be synchronized. Therefore, the control unit 60 can synchronize the same frame time t k The timing of the radiation pulses can be adapted to send a trigger signal that synchronizes the measurement head to record the frame. This simplifies the timing of the radiation pulses. The control unit 60 sets the timing of the radiation pulses t p It is especially useful if you can control it.

[0142] The measurement heads 20, 21, and 22 can be synchronized so that each measurement head simultaneously detects the same pixel, for example, the first pixel 211 of each array. It is also possible to synchronize the measurement heads with an unequal number of pixels. In this case, the first pixel of the array is synchronized with all measurement heads, and time compensation for the remaining pixels is calculated within the measurement server. This will be further explained in relation to Figures 8 to 10.

[0143] Different Pixel P i,jLine 41 for is shown to begin at level 44. Level 44 is not a predetermined threshold, and this can be the highest measurement during or after the flashlight, which may differ for different pixels, and the level 44' measured here is shown to differ for different pixels. In addition, typically, pixel P i,j Prior to this starting point 42, there are continuous measurements, which correspond to an increasing illumination level 48. This increasing illumination level occurs for all pixels.

[0144] As shown in Figures 8 to 10 and as described above, a synchronized measurement system can use only one server as the control unit 60 and several measurement head positions 20. In other words, signals measured by all different measurement heads 20, or by the same measurement head at different measurement positions as described in relation to Figure 10, are transmitted to the same control unit 60. The main advantages achieved are increased accuracy due to optimized synchronization and improved brightness due to the overlapping illumination of several measurement heads.

[0145] The overlapping region 105, as shown in Figure 6, is observed by more than one measurement head. Using radiation data from a single point on the object captured by at least two measurement heads 20, the system can optimize the evaluation process. The quality of the measurements can be further improved by taking overlapping surface measurements with different measurement heads and by calculating or comparing the measurements from the measurement heads.

[0146] Instead of transferring the signals measured by multiple measuring heads 20 to the same control unit when images are simultaneously taken by illumination, it is also possible to reduce the number of heads and reorient the measuring heads 20 and / or object 10 to take additional photographs when the illumination effect, as shown by curve 41 in Figure 3, disappears. This time is marked as the end of the measurement time 45 in Figure 3.

[0147] By synchronizing the camera frame with the flash of one or more radiation sources, a highly accurate overall image can be obtained, and as described above, the synchronization can occur over several images over time. In this regard, each measurement head 20 receives an irradiation response 41 from the illuminated surface. The irradiation response 41 is measured at pixel P i,j The measurement begins at time 42. Without modification of equation (1) or (2), the start time 42 will differ for different pixels of the same measurement, and in the case of several measurement heads, this will also differ for pixels "looking" at the same region, as shown by region 105 in Figure 6, which is covered by more than one measurement. As described above, the control unit applies a specific time shift 40 for each pixel of each measurement head 20 to synchronize the measurement response. In this regard, Figure 3 shows the measurements arriving at the control unit before the application of different time shifts, already modified for any effects of any reorientation of the measurement head 20 or object 10 across several images, as shown in relation to Figure 7.

[0148] Inducing radiation pulses can form the basis for synchronization and is calculated to be the starting point t1 46 for all measurement heads 20.

[0149] By properly positioning the measurement head, detected reflections of radiation during and after irradiation can be eliminated. This prevents misreadings from specular reflections. The aforementioned overlap of the detection cones also eliminates confusing reflections, as explained in relation to Figure 6.

[0150] By distributing several measuring heads 20, particularly as shown in Figures 1, 2, and 5, it becomes possible to measure the coating of an object, such as the coating of a battery cell, over a large angular range or around an entire portion, referred to as 4π. Using several measuring heads, depending on the holder, it becomes possible to cover the entire object 10 in a single measurement, resulting in considerable time savings. However, this synchronous method allows for the use of fewer measuring heads 20.

[0151] In some embodiments of this device, depending on the shape and arrangement of the measuring head, 1 cm 2 It is possible to measure more than 15,000 measurement points. This makes it possible to cover an area of ​​less than 0.1 mm per measurement point with a macro optical system. Of course, the actual pixel size is independent of the measurement results by synchronization as shown in Figure 3, meaning that pixel synchronization always works the same way regardless of how large the area represented by the pixel is.

[0152] By accurately measuring the coating around an object, it is possible to determine how much coating material (volume) has been applied. This can be done with a single measurement after coating, without contact. In this context, "single measurement" also refers to taking multiple images after the reorientation of the measuring head and the object, as explained in relation to Figure 7.

[0153] By using a single control unit 60, it becomes possible to provide a single measurement software that can be applied to all measurement heads 20 along with time shifts. Of course, using a single control unit 60 also results in considerable cost savings. System parameters can also be read from an external system, controlled, and stored centrally. This advantage also applies to continuously capturing images with the reoriented measurement heads 20 and object 10.

[0154] Figure 6 shows a very schematic detail of the cross-section of object 10, the measuring heads 21 and 22, the corresponding surface areas 222 and 322 of the pixels 200 of these measuring heads 21 and 22, respectively, and the thicknesses 5 and 5' calculated based on measurements of these measuring heads 21 and 22, respectively.

[0155] The right measuring head 21 may include a flashlight 220 and a concentric detector 120 as a radiation source. The center of the measuring head 21's illumination and observation cone is positioned along an axis 25 above the corner 11. A second measuring head 22 on the left is positioned on the edge 12 of the object 10, or, in a further embodiment not shown in the drawings, a measuring head 23 is positioned on a continuous surface 15 of the object 10 as shown in Figure 2. The pixels of the left measuring head 22 are observing a region 322 of the surface, indicated by the arrows in the plane of the figure. Each pixel is associated with a specific surface region. The pixels of the right measuring head 21 are observing a region 222 of the surface, indicated by the arrows in the plane of the figure.

[0156] When an image (frame) is taken, the flashlight 220 synchronizes, and each pixel area 222 and 322 receives radiation from the relevant specific surface area. Each pixel area 222 and 322 is read multiple times until the end of the measurement cycle (marked 45 in Figure 3), and the data over time (v i,j,k This data is then transferred to the control unit 60. This data can be visualized by the curve 41 in Figure 3.

[0157] Since the data is read continuously, the control unit 60 performs the time shift 40 relative to a common starting point 46, that is, using equation (1) or (2) to set the time t i,j,k It is adapted for calculation.

[0158] When each measuring head 21 is considered individually, different curves 41 allow for the calculation of the coating thickness distribution 101 based on the measurement of the right measuring head 21. The same applies to the calculation of the coating thickness distribution 102 based on the measurement of the left measuring head 22.

[0159] For every surface point of object 10, the thickness of coating 5 or 5' can be determined.

[0160] In some embodiments, as described, there may be a measurement overlap region 105 where both measuring heads 21 and 22 provide results. This is due to the fact that the surface is covered by the measured surface regions in pixel region 222 and pixel region 322. This overlap region 105 may be much larger or smaller than shown in Figure 6. This makes it possible to calculate a specific modified thickness value 103 for each point in the region covered by both (or three or more) measuring heads 20.

[0161] The calculated modified thickness can be used as an additional reference for the full measuring area of ​​each measuring head involved. This improves measurement performance in terms of accuracy and precision. This is shown as the lengths of the double arrows 200, 222, and 322 changing depending on the distance from the relevant measuring head.

[0162] As stated, the measuring head 20 can be synchronized by the control unit 60. Such synchronization involves, after the flash, the synchronization of the start point of the measurement 46, i.e., the frame period, which is related to the maximum value of the measured radiation response. Optionally, this is done for each pixel P i,j It can also include synchronization of the read window.

[0163] Figure 7 shows a further embodiment of the apparatus for non-contact and non-destructive testing of a surface, with fewer measuring heads, here two heads 21 and 21', and a configuration in which the measuring heads, here head 21', and / or the object are reoriented from 10A to 10R. It is possible to replace taking images (i.e., frames) simultaneously around the entire object 10 by taking subsequent images with fewer measuring heads 21. Here, it is shown that only two heads 21 and 21' are positioned at two corners 11 on the object 10A.

[0164] Images from synchronized flashlights are captured and processed as described above in relation to Figures 3, 4, and 6. The measuring head 21' is then moved upward, while the object is rotated from position 10A to 10R. This rotation follows arrow 6. The movement of head 21' positions the head at the same predefined and predetermined distance from different angles of the object. In Figure 7, the measuring head 21 "sees" the angle from which the measuring head 21' was initially positioned. Of course, it is also possible to reorient the object 10A to different rotated objects by moving it laterally, so that a new angle is examined each time. Figure 7 shows that images of the object's surface can be produced sequentially, thus reducing the number of cameras and radiation sources.

[0165] If necessary, an additional radiation source 220' can be provided. Here, the radiation source 220' is positioned at a long-range angle opposite the measuring head 21, and thus, for object 10R, the two radiation sources 220 for object 10A are positioned relative to the measuring head 21 and 21'. In this context, it is preferable to have a radiation source 220 provided independently of the measuring heads 21 and 21'.

[0166] After synchronizing the measured irradiation levels by knowing a common starting level 44 and a continuous shift 40 for a common starting point 46 for each pixel, the same results as the eight-head setup in Figure 1 can be obtained with just one measurement head 20, even when images are taken continuously.

[0167] Figure 8 shows two graphs of radiation values ​​measured over time for multiple pixels at two measurement positions 400, 401, 402, 403, or 404, as shown in Figures 9 and 10. The radiation response of the detector at the first measurement position receives reference numeral 431, and the radiation response of the detector at the second measurement position receives reference numeral 432. The radiation response 431 or 432 is taken by the measurement head 20 and transmitted to the control unit. Thus, the series of curves are the same curves described in relation to Figure 3.

[0168] Synchronization 47 between the radiation responses 431 and 432 at two measurement locations is achieved by selecting a common synchronized starting point 46' for the radiation response 441 of a given pixel at the first measurement location and for the radiation response 442 of a given pixel at the second measurement location. This synchronization involves a shift 40' between the responses of the measurement head 20 at the two measurement locations (i.e., calculation of equations (1) or (2) and (3)).

[0169] In transmitting the time of a flash event, it is not important whether there are two separate detectors at two measurement locations, or whether one detector is moved between the two measurement locations, or whether an object is moved to create two different measurement locations for a single detector.

[0170] Figure 9 shows the object 10M to be measured and four measuring heads at four measuring positions 401, 402, 403, and 404, while Figure 10 shows the object 10M' to be measured and one measuring head at a specific measuring location 400, showing rotation or linear movement or both of the object 10M' for relative movement of the measuring head to a specific further measuring position. At measuring positions 401, 402, 403, and 404, there may be separate measuring heads 20, or these positions may be reached through rotation or displacement as shown in Figure 10.

[0171] Figure 9 further illustrates the surface coverage through these four measurement positions 401, 402, 403, and 404. The four measurement positions 401, 402, 403, and 404 are shown as being in front of the four front corners of the parallelepiped. The detectors at these positions detect surfaces 411 and 412, respectively, which include the entire surface 17 with edges and corners, as well as partial surfaces with partial edges and corners. In short, these four measurement positions look at the front "half" of the parallelepiped. This relates to the edge region, and the strip runs over surface 411 and ends in region 412, which is covered by more than one measurement, as already shown in Figure 6, marked by reference numeral 105.

[0172] As described above, there may be areas of the surface 17 that are covered by more than one measurement, such as area 105 in Figure 6 or Figure 11. These measurements can be simultaneous measurements performed at the same time by two or more detectors 120 located at different positions (as shown in Figure 9), or they can be sequential measurements involving relative movement of the object 10 between measurements with respect to the detectors 120 (as shown in Figure 10).

[0173] In this case, the first and second measurements are taken from at least a first position and a second position (relative to the object), and the first and second positions are different.

[0174] Therefore, more generally speaking, the control unit 60 controls the value of one or more first frames k' (for the first measurement) vi’,j’,k’ and the value v of one or more second frames k'' (for the second measurement) i’’,j’’,k’’ Upon receiving, the first and second frames are recorded from different first and second positions. These frames are, By the same detector 120 moved relative to the surface 17 between two different positions, or Two different detectors 120 positioned at different locations It can be recorded.

[0175] The control unit 60 receives detected radiation from the same location on the surface, and the pixel P in the first frame k' and the second frame k'' receives radiation from the same location on the surface. i’,j’ and P i’’,j’’ Determine the pairs. In other words, each such pair consists of one pixel in the first frame and one pixel in the second frame, both pixels receiving light from the same point on surface 17.

[0176] In order to pair pixels in this way, the control unit 60 is required to know the coordinate transformation between the pixel coordinates i', j' and i'', j'' of the first and second frames.

[0177] This coordinate transformation can be calculated from the shape of the surface 17, as well as from known first and second positions, the orientation of the detector at those positions, and the mapping generated by the detector imaging system 122.

[0178] In another, more flexible embodiment, the coordinate transformation can be established by displaying images of the first and second frames on the display 61 and by receiving input from the user to identify corresponding points in the first and second frames. The control unit 60 can then determine the mapping between the first and second frames to identify pairs of pixels based on the user input.

[0179] Once the pixel pairs are determined by the control unit 60, these values ​​v i,j,k The results are combined to obtain an improved estimate of the parameters (e.g., thickness) of the surface 17 at the surface point where each pair of pixels receives radiation.

[0180] Such improved estimations can be obtained in various ways.

[0181] In one class of embodiments, the control unit 60 controls pixel P in the first frame k'. i’,j’ value v i’,j’,k’ and these times t i’,j’,k’ The first estimate of the parameter P1 is determined using this. In particular, this is the value v over several first frames k'. i’,j’,k’ and these times t i’,j’,k’ These are combined. For example, this can be a parameterized model of the thermal behavior of coating 17 during irradiation, using curve fitting, where one of the model's (optionally multiple) parameters is the parameter to be determined.

[0182] Similarly, the control unit 60 controls the pixel value v of the second frame k''. i’’,j’’,k’’ and these times t i’’,j’’,k’’ We use this to determine the second estimated parameter P2.

[0183] The first estimate P1 and the second estimate P2 of the parameter can then be combined, for example, by calculating the mean or weighted mean of P1 and P2.

[0184] In other embodiments, the "improved estimation" of the parameter is, for example, one of which is a value v as a function of time. i’,j’,k’ We predict that the other is a function of time and the value v i’’,j’’,k’’ By providing a thermal response model with two dependent (output) variables that predicts the value v, i’,j’,k’ and value v i’’,j’’,k’’ It can also be obtained by processing simultaneously. The aforementioned model is pixel P i’,j’ and Pi’’,j’’ It may have additional parameters depending on the ratio of signal intensity received from the surface point (which thereby explains the distance and projection angle).

[0185] As can be seen from the above, an apparatus is provided for non-contact and non-destructive testing of a surface by measuring its infrared radiation in response to thermal excitation, which comprises one or more electromagnetic radiation sources 220, each adapted to emit excitation radiation directed onto the surface 17 to be tested. One or more detectors 120, each equipped with a pixel array 121, are directed toward the surface 17 and record the response to the excitation radiation as a function of time. A control unit 60 receives values ​​from the pixels, and these values ​​are recorded over time t i,j,k The control unit 60 can control the timing of one or more radiation sources 220 and / or identify pairs of pixels that record the same point on the surface 17 from different viewpoints. [Explanation of Symbols]

[0186] 5. Thickness (measured by the first measuring head) 5' (thickness measured by the second measuring head) 5'' thickness (by combined measurement) 6 Rotating Arrows 7 Changing Arrows 10. Covered object (parallel hexahedron) 10' Covered object (cylindrical object) 10'' Covered object (sphere) 10A Covering object at the first position 10M (fixed and positioned) covering object 10M' Covered object (displaced and rotated for measurement) 10T Covered object in the second position (after rotation) 11 Corners of the covering object 12 Edge of the covering object 12' Further edges of the covering object 13 Representation of the spherical surface of a covered sphere 15. Flat or curved continuous surfaces 16 A point on the surface, in this case on the edge. 17 Surface 20 Optional measurement head equipped with a radiation source Measuring heads positioned at 21 corners 22 edge-positioned measuring heads 23 Measuring head positioned on a continuous or flat surface 25 (Sensor detection axis pointed towards the corner) 26 (Sensor detection axis facing the edge) 27 (Sensor detection axis facing the surface) 28 (Typical) detection axes 29 Head Controller 40 P i,j Time shifts regarding 40' Time shift between the two measurement locations 41 pixels P i,j Curve of radiation measurements for 41' Curve of radiation measurement for a given pixel, for example, the first pixel. 42 pixels P i,j Start time of measurement for 42' Start time at the measurement location 43 Axis of radiation measurement 44. Maximum measured radiation response after flash. 44' Higher maximum value for a specific pixel 45 End of measurement time 46 Synchronized start time for one measuring head 46' Synchronized start time for a specific measurement location 47 Synchronization of responses regarding radiation 49-hour time axis 60 control units 61 displays 80 frame cycle 81 data packets 101 Calculated thickness from the first measurement 102 Calculated thickness from the second measurement 103 Calculated thickness from more than one measurement Area covered by more than one measurement 120 Irradiation detector 121 Pixel array 122 Imaging system 200 Pixel i,j 201 Time marker for reading a pixel 211 First pixel of the first line 212 Second pixel of the first line 220 Flash, radiation source 222 21-pixel area 322 22-pixel area 400 Fixed single measurement position used for multiple measurements 401 First measurement position 402 Second measurement position 403 Third measurement position 404 Fourth measurement position 411 Surface of interest (entire surface with edges and corners) 412 Surface of interest (partial with partial edges and corners) 420 Displacement of the covering object 10M' between measurement positions 431 Radiation response of the detector at the first measurement position 432 Radiation response of the detector at the second measurement position 441 Radiation response of a given pixel at the first measurement position 442 Radiation response of a given pixel at the second measurement position

Claims

1. A method for non-contact and non-destructive measurement of surface (17) parameters by measuring the infrared radiation emitted from the surface (17), Radiation time (t ｐ ) comprising the steps of emitting a radiation pulse by at least one electromagnetic radiation source (220) and directing the radiation pulse onto the surface to be measured, The step of receiving detected radiation emitted by the surface (17) in response to the radiation pulse by at least one detector (120), wherein the detector (120) has a plurality of pixels (P ｉ，ｊ ) including steps, Pixels (P) in a series of consecutive frames (k) ｉ，ｊ The value of (v) ｉ，ｊ，ｋ This is a step to read out ) The aforementioned value is time (t) ｉ，ｊ，ｋ This represents the signal from the aforementioned pixel in ) Time (t) ｉ，ｊ，ｋ ) is the time (t) of frame (k). ｋ ) and pixels (P) in the detector (120) ｉ，ｊ The step, which depends on the position (i, j) of ), includes, The aforementioned method, The control unit (60) determines the time (t) from the position (i, j) and the frame (k) ｋ ), and the time (t ｉ，ｊ，ｋ ), and a step of determining The control unit controls the value (v ｉ，ｊ，ｋ ) and value (v ｉ，ｊ，ｋ ) time (t ｉ，ｊ，ｋ A method further comprising the step of determining the parameter using ).

2. The method according to claim 1, wherein the detector (120) is a bolometric detector.

3. Radiation time (t ｐ For a given radiation pulse at ), the time offset (t') for several frames (k) between the given radiation pulse and the next radiation pulse is defined. ｉ，ｊ，ｋ = t ｉ，ｊ，ｋ -t ｐ ) and Time offset (t' ｉ，ｊ，ｋ The value (v) as a function of ) ｉ，ｊ，ｋ The method according to claim 1 or 2, comprising the step of determining the parameter from the decay of ).

4. The control unit (60) controls the value (v) for each frame (k). ｉ，ｊ，ｋ ) including the time (t) of at least one frame (k) ｋ The step of receiving a data packet that indicates ) The control unit (60) controls one or more of the time (t) of the received data packets. ｋ The radiation time (t) for subsequent radiation pulses is a function of t ｐ The method according to claim 1 or 2, comprising the step of determining ).

5. The radiation time of the subsequent radiation pulse (t ｐ The method according to claim 4, wherein the control unit (60) determines that the subsequent radiation pulse falls between the frame periods of two consecutive frames (k1, k2).

6. The control unit (60) controls the value (v ｉ，ｊ，ｋ The arrival time and offset (O) of the data packet. ｔ ) from frame (k) time (t ｋ The method according to claim 1 or 2, further comprising the step of determining ).

7. The control unit controls the value of the first frame (k') (v ｉ’，ｊ’，ｋ’ ) and the value of the second frame (k'') (v ｉ’’，ｊ’’，ｋ’’ The step of receiving the first frame and the second frame from different first and second positions, a) By the same detector (120) that is moved between different positions, or b) Steps are recorded by two different detectors (120) located at different positions. The control unit (60) receives the detected radiation from the same location on the surface in the first frame (k') and the second frame (k'') pairs of pixels (P ｉ’，ｊ’ , P ｉ’’，ｊ’’ The method according to claim 1 or 2, comprising the step of determining ).

8. The control unit (60) records the values ​​(v) of several first frames (k') recorded from the first position. ｉ’，ｊ’，ｋ’ ) and the values ​​(v) of some second frames (k'') recorded from the second position ｉ’’，ｊ’’，ｋ’’ The steps to receive ) and The control unit (60) will, a) Pixels (P) in the first frame ｉ’，ｊ’ The value of (v) ｉ’，ｊ’，ｋ’ ) and value (v ｉ’，ｊ’，ｋ’ ) time (t ｉ’，ｊ’，ｋ’ Using ), the first estimation of the parameter (P1), and b) Pixels (P) in the second frame ｉ’’，ｊ’’ The value of (v) ｉ’’，ｊ’’，ｋ’’ ) and value (v ｉ’’，ｊ’’，ｋ’’ ) time (t ｉ’’，ｊ’’，ｋ’’ A step in which a second estimation (P2) of the parameter is determined using the pixel (P ｉ’，ｊ’ , P ｉ’’，ｊ’’ ) is a pair that receives the detected radiation from the same location on the surface, step and The method according to claim 7, comprising the step of combining a first estimate (P1) and a second estimate (P2) of the parameter to obtain a combined parameter using the control unit.

9. The method according to claim 7, wherein the first frame (k') and the second frame (k'') are recorded by two different detectors (120).

10. The first frame (k') and the second frame (k'') are recorded by the same detector (120). The method according to claim 7, further comprising the step of moving a detector (120) from a first position to a second position between recording a first frame (k') and a second frame (k'') with respect to the surface.

11. The control unit (60) performs the steps of displaying the images of the first frame and the second frame on the display (61), The control unit (60) receives user input that identifies corresponding points in the first frame and the second frame, The method according to claim 7, comprising the step of determining a mapping between the first frame and the second frame by the control unit (60) and based on the user input.

12. The control unit (60) controls several first frame (k') values ​​(v ｉ’，ｊ’，ｋ’ ) and some values ​​of the second frame (k'') (v ｉ’’，ｊ’’，ｋ’’ The method according to claim 7, which includes the step of receiving ).

13. Includes several measuring heads (20), The above method allows the frame to be used at the same time (t ｋ The method according to claim 1 or 2, further comprising the step of synchronizing the measuring head (20) to record in ).

14. An apparatus for carrying out the method according to claim 1 or 2, A radiation source (220) configured to emit pulsed excitation radiation onto the surface to be measured, A detector (120) arranged to detect radiation emitted by the surface in response to the pulsed excitation radiation, the detector (120) including an array of pixels (121), An apparatus comprising a control unit (60) programmed to perform the method described above.

15. A method for non-contact and non-destructive measurement of a surface (17) by measuring the infrared radiation emitted from the surface (17), The steps include providing at least one electromagnetic radiation source (220) adapted to emit excitation radiation with an excitation beam along a relevant radiation axis that can be directed onto the surface to be measured, The steps include providing at least one detector (120) at measurement positions (400; 401, 402, 403, 404) located on detection axes (25, 26, 27) oriented toward the surface to be measured (411, 412), The steps include receiving detected radiation emitted by the surfaces to be measured (411, 412) in response to radiation emitted from the electromagnetic radiation source (220) and impacting the surfaces to be measured (411, 412), The steps include providing at least one detector (120) and a control unit connected to the electromagnetic radiation source (220), Each of the provided at least one detector (120) has multiple pixels (P ｉ，ｊ , 200, 201, 211, 212) Including, The method determines at least two measurement positions (400; 401, 402, 403, 404) where the detector (120) receives radiation from surfaces (411, 412) that are measured after the emission of radiation from the electromagnetic radiation source (220), A method in which the control unit synchronizes the radiation signals (41) received from the at least two measurement positions for a predetermined pixel (441, 442) of the detector for each of the at least two measurement positions by applying a time shift (40') to a common time (46') based on the start time (42') of the detected radiation signal for the emission of radiation from the electromagnetic radiation source (220).

16. In a single positioning step, detectors (120) are provided at all measurement positions (401, 402, 403, 404) around the surface (411, 412) of the object (10M) to be measured in order to receive a radiation signal (41), or, The method according to claim 15, wherein at least one detector (120) is provided at one or more measurement positions (400) around the object to be measured (10M'), and the method is characterized in that, in one or more positioning steps, the object to be measured (10M, 10M') is displaced relative to or from the detector (120) to receive a radiation signal (41) continuously from the detector in each of the positioning steps, and the radiation signal (41) is transmitted to the control unit along with information indicating the time for which the radiation signal (41) was recorded in relation to the emission of radiation in each of the positioning steps.

17. The control unit applies a time shift (40) to each of the multiple pixels (P) of the detector (120) based on the start time (42) of the detected radiation signal (41) to a common time point (46). ｉ，ｊ The method according to claim 15, wherein the radiation signal (41) received from ) is synchronized.

18. An apparatus for non-contact and non-destructive measurement of a surface (17) by measuring the infrared radiation emitted from the surface (17), One or more electromagnetic radiation sources (220) each adapted to emit excitation radiation with an excitation beam along a relevant radiation axis that can be directed onto the surface to be measured, At least one detector (120) at each of the one or more measurement positions (400; 401, 402, 403, 404) is positioned on detection axes (25, 26, 27) oriented toward the surface to be measured (411, 412), and in response to radiation emitted from the electromagnetic radiation source (220) and impacting the surface to be measured (411, 412), receives detection radiation emitted by the surface to be measured (411, 412), The system includes a detector (120) and a control unit connected to the electromagnetic radiation source (220), Each of at least one detector (120) has multiple pixels (P ｉ，ｊ , 200, 201, 211, 212) Including, The control unit is configured to position at least one detector (120) at at least two measurement positions (400; 401, 402, 403, 404) where the detector (120) is positioned to receive radiation from surfaces (411, 412) that are measured after the emission of radiation from the electromagnetic radiation source (220). The control unit is configured to synchronize the radiation signals (41) received from the at least two measurement positions for each of the at least two measurement positions with respect to predetermined pixels (441, 442) of the detector by applying a time shift (40') to a common time (46') based on the start time (42') of the detected radiation signal for the emission of radiation from the electromagnetic radiation source (220).

19. A device for non-contact and non-destructive measurement of a surface by measuring the infrared radiation emitted from the surface, One or more electromagnetic radiation sources, each adapted to emit excitation radiation with an excitation beam along a relevant radiation axis that can be directed onto the surface to be measured, At least one detector at each of the one or more measurement positions, positioned on a detection axis oriented toward the surface to be measured, and receiving detection radiation emitted by the surface to be measured in response to radiation emitted from the electromagnetic radiation source and impacting the surface to be measured, The detector and the control unit connected to the electromagnetic radiation source are included, Each of the at least one detectors includes a plurality of pixels, The control unit is configured to position the at least one detector at at least two measurement positions, where the at least one detector is positioned to receive radiation from the surface to be measured after the emission of radiation from the electromagnetic radiation source. The control unit is configured to synchronize the radiation signals received from the at least two measurement positions for a predetermined pixel of the detector for each of the at least two measurement positions by applying a time shift to a common point in time based on the start time of the detected radiation signal for the emission of radiation from the electromagnetic radiation source.

20. A device for non-contact and non-destructive measurement of a surface by measuring the infrared radiation emitted from the surface, One or more electromagnetic radiation sources, each adapted to emit excitation radiation with an excitation beam along a relevant radiation axis that can be directed onto the surface to be measured, At least one detector at each of the one or more measurement positions, positioned on a detection axis oriented toward the surface to be measured, and receiving detection radiation emitted by the surface to be measured in response to radiation emitted from the electromagnetic radiation source and impacting the surface to be measured, The detector and the control unit connected to the electromagnetic radiation source are included, Each of the at least one detectors includes a plurality of pixels, The control unit is configured to synchronize radiation signals received from a plurality of pixels of a detector by applying a time shift to all pixels based on the start time of the detected radiation signal, separately for each of the detectors.

21. The apparatus according to claim 20, wherein a plurality of detectors (120) and / or electromagnetic radiation sources (220) are arranged at predetermined distances along the detection axis on the corners (11), edges (12), or continuous surfaces (17) of the covering object.

22. The observation cones of the detector (120) at two adjacent measurement positions (400; 401, 402, 403, 404) overlap in an area where the surface to be measured can be positioned, and / or The apparatus according to claim 20 or 21, wherein the electromagnetic radiation source (220) is arranged concentrically with the detection axis of the associated detector (120).

23. The apparatus includes a predetermined number of detectors (120) configured to be arranged around the object (10) to be measured. The apparatus according to claim 20 or 21, wherein the observation cone of the detector (120) is oriented such that the entire surface of interest of the coated object (10) is within the field of view of at least one of the observation cones.

24. A predetermined number of detectors (120) are at least one detector (20, 21), At least one detector (120) is positioned around the object (10A, 10R) to be measured in a series of separate image acquisition events, and after all image acquisition events, it covers the entire surface of interest of the object (10). The apparatus according to claim 23, wherein between two image acquisition events, at least one detector (21', 21'') moves (7) and / or rotates relative to the object being measured (10R).

25. A predetermined number of detectors (120) are at least one detector (20, 21), The apparatus according to claim 23, wherein between two image acquisition events, an object (10A to 10R) is moved and / or rotated to position the object (10R) with respect to at least one detector (21''), and after all image acquisition events have occurred, the positioning of the observation cone is achieved such that the entire surface of interest of the covered object (10) has been within the field of view of at least one of the observation cones at least once.

Images