Non-contact thickness measurement detection method and detection equipment

Abstract

The invention relates to the technical field of detection, and provides a non-contact thickness measurement detection method and detection equipment, a set of multi-dimensional, high-precision and self-adaptive thickness measurement system is constructed by fusing two non-contact detection technologies of laser and ultrasonic, a complete closed loop is formed from signal acquisition and processing to result fusion compensation, and the thickness measurement accuracy is improved. The method effectively breaks through the thickness measurement limitation of a single technology, adapts to complex and variable industrial measurement scenes, realizes accurate and stable measurement of the thickness of a measured object, gives consideration to dynamic compensation and environment adaptation, provides reliable technical support for the fields of high-end manufacturing, precision detection and the like, assists in improving the product quality control level, and has a wide application prospect. And the non-contact thickness measurement technology is promoted to develop to intelligence and high precision.

Description

Technical Field

[0001] The present application relates to the field of detection technology, and in particular to a non-contact thickness measurement method and detection equipment. Background Art

[0002] As industrial manufacturing moves towards high precision and intelligence, the demand for non-contact thickness measurement technology has surged in fields such as electronic chips, high-end equipment manufacturing, and precision instruments. Existing non-contact thickness measurement technologies are mainly divided into two major branches: laser thickness measurement and ultrasonic thickness measurement. Laser thickness measurement relies on laser triangulation and laser interferometry, and uses the high-resolution characteristics of laser to accurately capture the surface morphology information of objects. It is widely used in surface flatness detection and small thickness measurement scenarios; ultrasonic thickness measurement is based on the reflection characteristics of ultrasonic waves at the interfaces of different media. It calculates the thickness by analyzing the echo time difference and is good at penetrating and detecting the internal interlayer structure of the object. It is common in the thickness detection of multi-layer composite materials and metal plates; the two have matured and gradually explored the integration of multiple technologies from the application of a single technology, but the existing integration scheme is still in its early stages and has not formed a systematic and efficient collaborative thickness measurement system.

[0003] Existing attempts at laser and ultrasonic fusion thickness measurement rely on relatively independent acquisition of laser displacement and ultrasonic signals, lacking precise spatiotemporal registration mechanisms. Lasers focus on surface topography, while ultrasonics focus on internal interlayers. Signal acquisition times are asynchronous, and spatial coordinate systems are not unified. Consequently, the two types of signals cannot correspond to the same measurement time and space, leading to cumulative errors during superposition and calculation, hindering the benefits of fusion. Furthermore, in industrial scenarios, interference factors such as object motion, equipment vibration, and ambient temperature fluctuations are frequent. The lack of dynamic coordinated compensation for these multiple interference factors leads to a sharp decline in thickness measurement accuracy under complex working conditions. Most approaches fail to address the balance between signal quality and thickness measurement accuracy under complex working conditions to achieve non-contact thickness measurement. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the present application provides a non-contact thickness measurement method and detection equipment.

[0005] In a first aspect, the present application provides a non-contact thickness measurement method, the method comprising: emitting a laser beam and a broadband ultrasonic beam toward the surface of an object to be measured, acquiring a laser displacement signal and an ultrasonic echo signal reflected by the object to be measured, performing spatiotemporal registration on the laser displacement signal and the ultrasonic echo signal, and monitoring the movement speed of the object to be measured and the vibration of a detection device to dynamically compensate for the laser displacement signal and the ultrasonic echo signal;

[0006] The ultrasonic echo signal is analyzed using a waveform deconvolution algorithm to identify and locate the interlayer interface of the object being measured. The initial thickness value of the object being measured at the measurement point is calculated based on the time difference of the interlayer interface reflection in the ultrasonic echo signal. At the same time, the laser displacement signal is processed using laser triangulation to measure the surface morphology of the object being measured at the measurement point. The vertical distance from the surface morphology of the object being measured at the measurement point to the location of the interlayer interface in the ultrasonic echo signal is calculated to determine the actual thickness value of the object being measured at the measurement point. The emission angle of the broadband ultrasonic beam is dynamically adjusted according to the surface morphology.

[0007] A weight coefficient is dynamically assigned based on the signal-to-noise ratio of the laser displacement signal and the confidence level of the positioning of the interlayer interface in the ultrasonic echo signal. The initial thickness value and the actual thickness value are fused according to the weight coefficient to determine the thickness value of the measured object at the measuring point. At the same time, the ambient temperature, the surface state of the measured object, and the movement speed of the measured object are obtained in real time to compensate and correct the thickness value.

[0008] As an optional implementation, the compensation logic of the laser displacement signal and the ultrasonic echo signal includes:

[0009] Obtain the velocity of the object being measured along the axis of the laser beam, reconstruct the frequency of the ultrasonic echo signal based on the Doppler effect principle, and correct the acquisition time of the laser displacement signal in real time based on the geometric relationship of the triangulation method;

[0010] Monitor the vibration of the detection equipment to determine the phase offset of the laser displacement signal, and correct and compensate the laser displacement signal through the phase unwrapping algorithm;

[0011] The vibration displacement of the equipment is determined according to the vibration of the detection equipment, and the propagation path of the ultrasonic echo signal is adjusted in real time based on the vibration displacement of the equipment, and the emission angle of the broadband ultrasonic beam is adjusted. At the same time, the time delay compensation amount is determined according to the propagation path of the ultrasonic echo signal to compensate the ultrasonic echo signal.

[0012] As an optional implementation, the execution sub-logic of the spatiotemporal registration includes:

[0013] A laser beam and a broadband ultrasonic beam are emitted toward the surface of the object being measured, and a timestamp signal is generated simultaneously to preliminarily align the emission times of the laser beam and the broadband ultrasonic beam;

[0014] Acquire the laser displacement signal and ultrasonic echo signal reflected by the measured object, calculate the time difference between the laser displacement signal and the ultrasonic echo signal through the cross-correlation algorithm, and perform interpolation correction on the time point of the ultrasonic echo signal based on the time difference and the difference in acquisition frequency;

[0015] Determine the laser coordinate system of the laser displacement signal and the ultrasonic coordinate system of the ultrasonic echo signal, and judge the conversion relationship between the laser coordinate system and the ultrasonic coordinate system. Dynamically adjust the spatial relationship between the laser displacement signal and the ultrasonic echo signal according to the conversion relationship to perform spatiotemporal alignment of the laser displacement signal and the ultrasonic echo signal.

[0016] As an optional implementation manner, the identification and positioning logic of the inter-layer interface includes:

[0017] The ultrasonic echo signal is decomposed into multiple frequency bands by wavelet packet decomposition, the energy entropy value of each frequency band is calculated, and the frequency bands are filtered according to the energy entropy value to obtain the interface reflection signal;

[0018] The interface reflection signal is processed by waveform deconvolution algorithm to separate the interface reflection wave and identify the reflection waveform of each interlayer interface;

[0019] The peak position of the reflected waveform of each interlayer interface is determined by a dynamic threshold search algorithm, and the location of the interlayer interface in the measured object is determined in combination with the propagation velocity of the ultrasonic echo signal to identify and locate the interlayer interface.

[0020] As an optional implementation manner, the logic for adjusting the emission angle of the broadband ultrasonic beam includes:

[0021] Perform curvature analysis on the surface topography of the object at the measurement point, calculate the Gaussian curvature and average curvature of each measurement point to identify the surface feature area, refine the surface feature area through morphological operations, and extract the topography parameters of the object, including surface roughness and surface slope;

[0022] Configure the roughness threshold and slope threshold, compare the surface roughness and surface slope with the roughness threshold and slope threshold respectively, and preliminarily adjust the emission angle of the broadband ultrasonic beam;

[0023] After preliminarily adjusting the emission angle of the broadband ultrasonic beam, new laser displacement signals and ultrasonic echo signals are acquired in real time to respectively determine the initial and actual thickness values ​​of the object being measured at the measurement point.

[0024] Compare the fluctuations of the initial thickness value and the actual thickness value before and after adjustment, as well as the changes in the signal-to-noise ratio of the ultrasonic echo signal, and comprehensively judge whether to adjust the emission angle of the broadband ultrasonic beam again.

[0025] As an optional implementation, the surface topography measurement sub-logic includes:

[0026] Monitor the laser spot area formed by the laser beam on the surface of the object being measured, divide the laser spot area into multiple sub-areas, and process each sub-area through local binary pattern to form texture features;

[0027] The displacement of the laser displacement signals of adjacent frames is calculated by the phase correlation method to obtain the surface changes of the object being measured;

[0028] Through laser triangulation, combined with the conversion relationship between the laser coordinate system and the ultrasonic coordinate system, the laser displacement signal is converted into three-dimensional space, and the surface morphology of the object at the measurement point is measured through the iterative closest point algorithm based on the surface changes and texture characteristics of the object.

[0029] As an optional implementation, the thickness value compensation correction logic includes:

[0030] Acquire the ambient temperature in real time, configure the temperature threshold, compare the ambient temperature with the temperature threshold to determine the expansion properties of the object being measured, and calculate the thickness change of the object being measured based on the expansion properties of the object being measured;

[0031] Analyze the relationship between surface roughness and the phase deviation of the laser displacement signal to calculate the thickness compensation of the measured object, and perform spectrum analysis on the laser displacement signal to determine whether there is any abnormality on the surface of the measured object. If there is any abnormality on the surface of the measured object, dynamically adjust the delay compensation of the ultrasonic echo signal;

[0032] Obtain the moving speed of the object being measured along the axis of the laser beam, reconstruct the frequency of the ultrasonic echo signal based on the Doppler effect principle, and dynamically adjust the acquisition frequency of the laser displacement signal and the ultrasonic echo signal according to the moving speed of the object being measured;

[0033] After adjusting the laser displacement signal and the ultrasonic echo signal, the ambient temperature, the surface state of the object being measured, the movement speed of the object being measured and the thickness value of the object being measured at the measuring point are continuously obtained, and the thickness value is compensated and corrected in combination with the thickness change of the object being measured and the thickness compensation amount.

[0034] As an optional implementation manner, the weight coefficient allocation sub-logic includes:

[0035] The signal-to-noise ratio of the laser displacement signal is determined by a sliding window algorithm, and the confidence level of the interlayer interface location in the ultrasonic echo signal is determined based on the reflection waveform of each interlayer interface.

[0036] The signal-to-noise ratio of the laser displacement signal and the confidence level of the location of the interlayer interface in the ultrasonic echo signal are used to assign weight coefficients to the laser displacement signal and the ultrasonic echo signal through fuzzy logic;

[0037] The thickness variation trend of the measured object is predicted through historical measurement data, and the weight coefficients of the laser displacement signal and the ultrasonic echo signal are corrected according to the thickness variation trend of the measured object.

[0038] As an optional implementation manner, the thickness value determination sub-logic includes:

[0039] According to the weight coefficients of the laser displacement signal and the ultrasonic echo signal, the initial thickness value and the actual thickness value are fused by the weighted average method to obtain the fused thickness value;

[0040] Calculate the thickness deviation between the fused thickness value and the mean of historical measurement data, configure the deviation threshold, compare the thickness deviation with the deviation threshold to identify outliers, and use cubic spline interpolation to fit the normal fused thickness value to replace the outliers;

[0041] Monitor the signal-to-noise ratio of the laser displacement signal and the confidence level of the location of the interlayer interface in the ultrasonic echo signal to determine whether to correct the weight coefficients of the laser displacement signal and the ultrasonic echo signal again to correct the fusion thickness value;

[0042] Continuously obtain multiple frames of corrected fused thickness values, and determine the thickness value of the measured object at the measuring point according to the average value of the multiple frames of corrected fused thickness values.

[0043] In a second aspect, the present application provides a non-contact thickness measurement device, the device comprising: a laser group and an ultrasonic group;

[0044] The laser group is used to emit a laser beam to the surface of the measured object and receive a laser displacement signal reflected by the measured object, measure the surface topography of the measured object at the measuring point by processing the laser displacement signal, and determine the actual thickness value of the measured object at the measuring point;

[0045] The ultrasonic group is used to transmit a broadband ultrasonic beam to the surface of the object to be measured and obtain ultrasonic echo signals to identify and locate the interlayer interface of the object to be measured, and calculate the initial thickness value of the object to be measured at the measuring point by analyzing the ultrasonic echo signals.

[0046] Compared with the existing technology, the beneficial effects of this application are: by integrating the two non-contact detection technologies of laser and ultrasound, a multi-dimensional, high-precision and self-adaptive thickness measurement system is constructed, forming a complete closed loop from signal acquisition, processing to result fusion and compensation, effectively breaking through the thickness measurement limitations of a single technology, adapting to complex and changeable industrial measurement scenarios, and achieving accurate and stable measurement of the thickness of the measured object, taking into account dynamic compensation and environmental adaptation, providing reliable technical support for high-end manufacturing and precision testing and other fields, helping to improve product quality control level, and promoting the development of non-contact thickness measurement technology towards intelligence and high precision.

[0047] Synchronously emitting laser beams and broadband ultrasonic beams can simultaneously obtain information reflecting the surface morphology and internal interlayer structure of the object, making up for the shortcomings of a single signal dimension, providing a data basis for comprehensive thickness measurement, and allowing the thickness measurement results to better reflect the true state of the object; by performing time and space alignment on the laser displacement signal and the ultrasonic echo signal, ensuring the precise matching of the laser displacement signal and the ultrasonic echo signal in the time and space dimensions, so that different signals correspond to the same measurement time and space, avoiding thickness measurement errors caused by time and space misalignment, and laying a solid data foundation for subsequent accurate thickness calculation; monitoring the movement speed of the object being measured and the vibration of the detection equipment to dynamically compensate for the laser displacement signal and the ultrasonic echo signal, effectively resisting external dynamic interference, so that the signal quality remains stable under complex working conditions, and improving the reliability of thickness measurement.

[0048] The waveform deconvolution algorithm is used to analyze the ultrasonic echo signal to identify and locate the interlayer interface of the measured object. The different interlayer interfaces inside the measured object can be clearly identified, providing an accurate basis for the interface position calculation for the initial thickness value. Even complex multi-layer structures can be accurately distinguished, ensuring the accuracy of the initial thickness value calculation basis. The laser displacement signal is processed by the laser triangulation method to measure the surface morphology of the measured object, calculate the vertical distance from the surface morphology to the positioning position of the interlayer interface, and obtain the actual thickness value. The high resolution of the laser for surface details is used to supplement the shortcomings of ultrasonic thickness measurement in terms of surface morphology correlation, and the vertical distance calculation makes the actual thickness value more consistent with the actual thickness of the object. At the same time, the ultrasonic beam emission angle is adjusted according to the surface morphology, so that the broadband ultrasonic beam can better adapt to the surface state of the measured object, indirectly improving the accuracy of the initial thickness value and the actual thickness value calculation.

[0049] The weight coefficient is assigned according to the signal-to-noise ratio of the laser signal and the confidence level of the positioning position of the interlayer interface, so that the fused thickness value is inclined towards the thickness measurement result with good signal quality, avoiding the dominance of the final result by a single signal error. The fused thickness value combines the advantages of both technologies, improves the stability and accuracy of the thickness measurement result, and adapts to the scenarios with different signal quality in different measurement areas. The ambient temperature, surface state and motion speed compensation are integrated to correct the thickness in multiple dimensions, thereby effectively eliminating the influence of changes in the external environment and the object's own state on the thickness measurement, so that the thickness value remains accurate and reliable under variable working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be derived from these drawings without inventive work. Among them:

[0051] Figure 1 A flow chart of a non-contact thickness measurement method provided in an embodiment of the present application;

[0052] Figure 2 A logic diagram for identifying and locating the interlayer interface of a non-contact thickness measurement method provided in an embodiment of the present application;

[0053] Figure 3 A logic diagram for adjusting the emission angle of a broadband ultrasonic beam in a non-contact thickness measurement method provided in an embodiment of the present application;

[0054] Figure 4 This is a device structure diagram of a non-contact thickness measurement device provided in an embodiment of the present application.

[0055] Reference numerals:

[0056] 1. Laser group; 2. Ultrasonic group; 3. Base; 4. Positioning platform for the object to be measured. DETAILED DESCRIPTION

[0057] In order to make the objectives, technical solutions and advantages of the embodiments of the present application more obvious and easy to understand, the technical solutions in the embodiments of the present application are clearly and completely described below in conjunction with the drawings in the specification. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments.

[0058] Example 1:

[0059] like Figure 1 As shown, a flow chart of a non-contact thickness measurement method is provided for an embodiment of the present application, and the method includes:

[0060] S1. Emit a laser beam and a broadband ultrasonic beam toward the surface of the object to be measured, obtain the laser displacement signal and ultrasonic echo signal reflected by the object to be measured, perform spatiotemporal registration on the laser displacement signal and ultrasonic echo signal, and monitor the movement speed of the object to be measured and the vibration of the detection equipment to dynamically compensate the laser displacement signal and ultrasonic echo signal.

[0061] Furthermore, the execution sub-logic of spatiotemporal registration includes:

[0062] A laser beam and a broadband ultrasonic beam are emitted toward the surface of the object being measured, and a timestamp signal is generated simultaneously to preliminarily align the emission times of the laser beam and the broadband ultrasonic beam;

[0063] Acquire the laser displacement signal and ultrasonic echo signal reflected by the measured object, calculate the time difference between the laser displacement signal and the ultrasonic echo signal through the cross-correlation algorithm, and perform interpolation correction on the time point of the ultrasonic echo signal based on the time difference and the difference in acquisition frequency;

[0064] Determine the laser coordinate system of the laser displacement signal and the ultrasonic coordinate system of the ultrasonic echo signal, and judge the conversion relationship between the laser coordinate system and the ultrasonic coordinate system. Dynamically adjust the spatial relationship between the laser displacement signal and the ultrasonic echo signal according to the conversion relationship to perform spatiotemporal alignment of the laser displacement signal and the ultrasonic echo signal.

[0065] If there is a difference in the emission time of the laser beam and the broadband ultrasonic beam, the reflected signal will not correspond to the same measurement time, affecting the accuracy of subsequent signal analysis. Therefore, it is necessary to preliminarily align the emission times; a synchronous trigger circuit is set inside the detection equipment, which connects the laser emitter and the ultrasonic transducer. When the measurement start instruction is issued, the synchronous trigger circuit simultaneously sends a trigger signal to the laser emitter and the ultrasonic transducer, causing both to emit the laser beam and the broadband ultrasonic beam. At the same time as the trigger signal is sent, the synchronous trigger circuit generates a timestamp signal as the starting time mark for signal acquisition; thus, through hardware-level synchronous triggering, the preliminary alignment of the emission time of the laser beam and the ultrasonic beam is achieved, laying the foundation for subsequent precise time calibration, and ensuring that the two types of signals have basic consistency in the time dimension.

[0066] Although preliminary time alignment has been performed, due to factors such as the response characteristics of the laser transmitter and ultrasonic sensor and signal transmission delay, there is still a time difference between the actually acquired laser displacement signal and the ultrasonic echo signal, and further calibration is required to achieve precise synchronization. After receiving the laser displacement signal and ultrasonic echo signal reflected by the measured object, the laser displacement signal and the ultrasonic echo signal are analyzed by a cross-correlation algorithm. The cross-correlation algorithm calculates the correlation with the other signal by sliding one of the signals, finds the position with the highest correlation, and thus determines the time difference between the two. At the same time, the acquisition frequencies of the laser displacement signal and the ultrasonic echo signal are obtained. According to the The ultrasonic echo signal is interpolated based on the calculated time difference and the difference in acquisition frequency. Specifically, on the entire time axis of the acquired ultrasonic echo signal, appropriate sampling points are inserted according to the time difference and the difference in acquisition frequency to correct the time point of the ultrasonic echo signal so that the ultrasonic echo signal and the laser displacement signal are accurately aligned in time. Through the cross-correlation algorithm and interpolation processing, the time deviation between the laser displacement signal and the ultrasonic echo signal caused by hardware differences is effectively eliminated, and the precise synchronization of the two types of signals in the time dimension is achieved, which improves the time consistency of the laser displacement signal and the ultrasonic echo signal, and provides an accurate time basis for subsequent spatial alignment.

[0067] The laser displacement signal and ultrasonic echo signal acquire data based on their respective sensor coordinate systems. In order to fuse and analyze the two types of signals, it is necessary to determine the spatial conversion relationship between the two and dynamically adjust it according to the actual measurement situation to ensure that the laser displacement signal and the ultrasonic echo signal correspond to the same position of the object being measured. During the installation and commissioning phase of the detection equipment, a calibration plate is used to calibrate the laser emitter and ultrasonic transducer. The calibration plate has feature points with known precise positions. The laser emitter obtains the three-dimensional coordinates of the feature points on the calibration plate through laser triangulation to establish a laser coordinate system. The ultrasonic transducer transmits a broadband ultrasonic beam to the calibration plate and receives the ultrasonic echo signal. The feature point position is calculated based on the echo time and ultrasonic propagation speed to establish an ultrasonic coordinate system. Then, by analyzing the two sets of feature point coordinates, the rotation matrix and translation vector between the laser coordinate system and the ultrasonic coordinate system are calculated through the spatial coordinate conversion algorithm to determine the conversion relationship between the two.

[0068] During the actual measurement process, when the object being measured moves or the detection equipment undergoes slight displacement, the camera monitors the position changes of the laser spot and the broadband ultrasonic beam on the surface of the object being measured. Based on the monitored position changes and in combination with the conversion relationship between the laser coordinate system and the ultrasonic coordinate system, the spatial relationship between the laser displacement signal and the ultrasonic echo signal is dynamically adjusted in real time. Preferably, when the laser spot is detected to be offset, the spatial mapping position of the ultrasonic echo signal is adjusted accordingly based on the offset and the conversion relationship to ensure that the two types of signals always correspond to the same measurement position on the object being measured. Through precise calibration and dynamic adjustment, a conversion relationship between the laser coordinate system and the ultrasonic coordinate system is established, which can adapt to position changes during the measurement process, achieving precise spatial registration of the laser displacement signal and the ultrasonic echo signal, providing a reliable spatial foundation for subsequent signal fusion and thickness measurement calculation. After spatiotemporal registration, the laser displacement signal and the ultrasonic echo signal achieve precise correspondence in both time and space, creating favorable conditions for subsequent dynamic signal compensation, analysis and processing, and accurate calculation of the thickness of the object being measured, thereby improving the measurement accuracy and reliability of the detection equipment.

[0069] Specifically, the compensation logic of the laser displacement signal and the ultrasonic echo signal includes:

[0070] Obtain the velocity of the object being measured along the axis of the laser beam, reconstruct the frequency of the ultrasonic echo signal based on the Doppler effect principle, and correct the acquisition time of the laser displacement signal in real time based on the geometric relationship of the triangulation method;

[0071] Monitor the vibration of the detection equipment to determine the phase offset of the laser displacement signal, and correct and compensate the laser displacement signal through the phase unwrapping algorithm;

[0072] The vibration displacement of the equipment is determined according to the vibration of the detection equipment, and the propagation path of the ultrasonic echo signal is adjusted in real time based on the vibration displacement of the equipment, and the emission angle of the broadband ultrasonic beam is adjusted. At the same time, the time delay compensation amount is determined according to the propagation path of the ultrasonic echo signal to compensate the ultrasonic echo signal.

[0073] The movement of the object under test, especially the movement along the axis of the laser beam, will cause the ultrasonic echo signal to produce a Doppler effect, affecting the echo frequency and phase. The tangential movement will change the position of the laser spot on the surface of the object under test, resulting in the acquisition deviation of the laser displacement signal. Therefore, it is necessary to compensate the signal according to the movement speed of the object under test to eliminate the measurement error caused by the movement. A laser Doppler velocimeter emits a low-power laser beam to the object under test, receives the laser reflected back from the surface of the object under test, and analyzes the frequency change of the reflected laser, so as to measure the movement speed of the object under test along the axis of the laser beam in real time. After the movement speed of the object under test is detected, the frequency of the ultrasonic echo signal is reconstructed according to the principle of the Doppler effect. Specifically, the frequency offset caused by the Doppler effect is calculated based on the movement speed of the object under test and the propagation speed of ultrasonic waves in the medium, and then the frequency of the ultrasonic echo signal is adjusted to restore the ultrasonic echo signal to the frequency characteristics of the object under test when it is in a stationary state.

[0074] For the laser displacement signal, a high-speed camera monitors the laser spot area formed by the laser beam on the surface of the measured object in real time and determines the position change of the laser spot area on the measured object. Based on the geometric relationship of triangulation, the relationship between the position change of the laser spot area and the tangential motion speed of the measured object is analyzed. When the laser spot area is detected to be offset due to the tangential motion of the measured object, the acquisition time of the laser displacement signal is corrected in real time based on the offset and the motion speed of the measured object. If the tangential motion of the measured object causes the laser spot area to reach a certain position early, the acquisition time of the laser displacement signal is delayed accordingly to ensure that the acquired laser displacement signal accurately reflects the current position of the measured object. The collaborative operation of the laser Doppler velocimeter and the high-speed camera effectively eliminates the influence of the measured object motion on the ultrasonic echo signal and the laser displacement signal. This ensures that both types of signals can still accurately reflect the actual position and status of the measured object even when the measured object is in motion, thereby improving the accuracy and reliability of non-contact thickness measurement in dynamic measurement scenarios.

[0075] During operation, the detection equipment will be affected by vibrations from the external environment or its own operation. These vibrations will cause phase shifts in the laser displacement signal and changes in the propagation path of the ultrasonic echo signal, thereby affecting the accuracy of the measurement results. Therefore, it is necessary to compensate for the signal error caused by the vibration. Accelerometers and gyroscopes are used at the laser emitter and ultrasonic transducer to obtain real-time acceleration and angular velocity information of the detection equipment in three directions to monitor the vibration of the detection equipment. At the same time, the jitter of the laser spot is photographed by a high-speed camera, and the acceleration, angular velocity and jitter of the laser spot are fused through the Kalman filter algorithm to determine the vibration displacement of the detection equipment. For the laser displacement signal, the phase shift of the laser displacement signal is determined based on the determined vibration displacement of the equipment. The laser displacement signal is corrected and compensated through the phase unwrapping algorithm to eliminate the phase error caused by the vibration of the equipment and restore the laser displacement signal to the accurate phase state.

[0076] The propagation path of the ultrasonic echo signal is adjusted in real time according to the vibration displacement of the equipment. Specifically, when it is detected that the vibration of the equipment causes the position of the ultrasonic transducer to change, the propagation path of the ultrasonic echo signal from transmission to reception is recalculated. According to the new propagation path, the time delay compensation amount that needs to be compensated is determined, and the ultrasonic echo signal is compensated accordingly according to the time delay compensation amount to ensure the time accuracy of the ultrasonic echo signal. At the same time, the emission angle of the broadband ultrasonic beam is adjusted according to the vibration displacement of the equipment, so that the broadband ultrasonic beam can be more accurately directed to the measurement point of the object to be measured, reducing the signal reflection deviation caused by equipment vibration.

[0077] By monitoring the vibration of the equipment in real time to determine the phase offset of the laser displacement signal and the propagation path of the ultrasonic echo signal, the interference of equipment vibration on the laser displacement signal and the ultrasonic echo signal can be effectively suppressed, the signal error caused by equipment vibration can be eliminated, the signal quality and measurement stability can be improved, and accurate measurement results can be obtained even in an equipment vibration environment. The accuracy and reliability of the laser displacement signal and ultrasonic echo signal after vibration compensation are significantly improved, providing high-quality data for subsequent operations such as precise interlayer interface identification and thickness measurement based on these two types of signals, ensuring the accuracy and reliability of the entire non-contact thickness measurement process, and avoiding the transmission of vibration errors to subsequent measurement links.

[0078] S2. Analyze the ultrasonic echo signal through the waveform deconvolution algorithm to identify and locate the interlayer interface of the object under test. Based on the time difference of the interlayer interface reflection in the ultrasonic echo signal, calculate the initial value of the thickness of the object under test at the measurement point. At the same time, process the laser displacement signal through the laser triangulation method to measure the surface morphology of the object under test at the measurement point. Calculate the vertical distance from the surface morphology of the object under test at the measurement point to the positioning position of the interlayer interface in the ultrasonic echo signal to determine the actual value of the thickness of the object under test at the measurement point, and dynamically adjust the emission angle of the broadband ultrasonic beam according to the surface morphology.

[0079] Specifically, if Figure 2 As shown, the identification and positioning logic of the inter-layer interface includes:

[0080] The ultrasonic echo signal is decomposed into multiple frequency bands by wavelet packet decomposition, the energy entropy value of each frequency band is calculated, and the frequency bands are filtered according to the energy entropy value to obtain the interface reflection signal;

[0081] The interface reflection signal is processed by waveform deconvolution algorithm to separate the interface reflection wave and identify the reflection waveform of each interlayer interface;

[0082] The peak position of the reflected waveform of each interlayer interface is determined by a dynamic threshold search algorithm, and the location of the interlayer interface in the measured object is determined in combination with the propagation velocity of the ultrasonic echo signal to identify and locate the interlayer interface.

[0083] Ultrasonic echo signals contain multiple frequency components, including a mixture of environmental noise, equipment interference signals, and interface reflection signals. To accurately identify interlayer interfaces, it is necessary to separate the effective signals that truly reflect the interface information from the complex ultrasonic echo signals. Therefore, the ultrasonic echo signals must be decomposed and filtered by frequency band. Wavelet packet decomposition is used to decompose the ultrasonic echo signals into multiple frequency bands, making the ultrasonic echo signals present clearer characteristics at different frequency scales. After decomposition, the energy entropy value of each frequency band is calculated. The energy entropy value can reflect the complexity and energy distribution of the signal within the frequency band. A screening threshold for the energy entropy value is set to filter out frequency bands with energy entropy values ​​greater than the screening threshold. These filtered frequency bands contain more effective signals related to interlayer interface reflections, while frequency bands with energy entropy values ​​less than or equal to the screening threshold often correspond to noise or invalid signals and are therefore eliminated. Wavelet packet decomposition and energy entropy screening effectively remove noise and interference components from the ultrasonic echo signals, highlighting the interface reflection signals, laying the foundation for subsequent more accurate analysis of the interlayer interface reflection waveform, and improving the accuracy and reliability of interlayer interface identification.

[0084] When ultrasound propagates inside the object being measured, the reflected waves from different interlayer interfaces will overlap and alias each other, making it difficult to directly distinguish the reflection characteristics of each interlayer interface from the original ultrasonic echo signal. Therefore, a waveform deconvolution algorithm is needed to separate the aliased reflected waves, so as to accurately identify the reflection waveform of each interlayer interface; the interface reflection signal obtained by processing the filter is processed by the waveform deconvolution algorithm. The waveform deconvolution algorithm is based on the basic principle of deconvolution. Through continuous iterative optimization, it tries to find a suitable deconvolution kernel. During the iterative process, the waveform deconvolution algorithm adjusts the parameters of the deconvolution kernel according to the characteristics of the interface reflection signal, so that the interface reflection signal after deconvolution can restore the original characteristics of each interlayer interface to the greatest extent. Initial reflection waveform; During the optimization process, regularization constraints are introduced to avoid overfitting of noise by the waveform deconvolution algorithm. By balancing the signal fitting degree and regularization constraints, the waveform deconvolution algorithm can remove the aliasing of interface reflection signals while maintaining the authenticity and reliability of interface reflection signals; Finally, after processing by the waveform deconvolution algorithm, the interface reflection waves that were originally mixed together are successfully separated, and the reflection waveform of each interlayer interface is clearly presented; The waveform deconvolution algorithm effectively solves the problem of interface reflection wave aliasing in ultrasonic echo signals, accurately separates the reflection waveforms of each interlayer interface, provides clear and accurate signal characteristics for accurately determining the position of the interlayer interface, and significantly improves the accuracy of interlayer interface identification.

[0085] In the reflection waveform of the separated interlayer interface, it is necessary to accurately find the peak position of each reflection waveform, because the peak position corresponds to the reflection time of the ultrasonic echo signal at the interlayer interface. Combined with the propagation speed of the ultrasonic echo signal, the spatial position of the interlayer interface in the measured object can be determined. However, due to the differences in the amplitude and shape of the reflection waveforms of different interlayer interfaces, a fixed threshold is difficult to adapt to all situations, so a dynamic threshold search algorithm is needed; the dynamic threshold search algorithm is used to analyze the overall characteristics of the reflection waveform, which include the amplitude range and change trend of the reflection waveform; then, a threshold range is dynamically determined based on the characteristics of the reflection waveform.

[0086] Within this threshold range, the dynamic threshold search algorithm searches for peak positions in the reflected waveform that meet the requirements. To further improve positioning accuracy, the peak positions found are refined. Combined with the known ultrasonic propagation velocity in the measured object, the spatial position of each interlayer interface in the measured object is calculated based on the time corresponding to the peak position, thereby accurately locating the interlayer interface. The dynamic threshold search algorithm can adapt to the reflected waveforms of interlayer interfaces of different shapes and accurately find the peak positions. Combined with the ultrasonic propagation velocity in the measured object, the spatial position of the interlayer interface in the measured object is accurately determined, providing key position information for subsequent calculation of the initial thickness value, ensuring the accuracy of thickness measurement. The precisely determined spatial position of the interlayer interface allows the calculation of the initial thickness value of the measured object at the measurement point based on the time difference of the interlayer interface reflection in the ultrasonic echo signal. It also provides an accurate internal interface reference for the subsequent calculation of the actual thickness value combined with the surface topography measured by laser, playing a decisive role in the accuracy of the entire thickness measurement process.

[0087] Furthermore, the surface topography measurement sub-logic includes:

[0088] Monitor the laser spot area formed by the laser beam on the surface of the object being measured, divide the laser spot area into multiple sub-areas, and process each sub-area through local binary pattern to form texture features;

[0089] The displacement of the laser displacement signals of adjacent frames is calculated by the phase correlation method to obtain the surface changes of the object being measured;

[0090] Through laser triangulation, combined with the conversion relationship between the laser coordinate system and the ultrasonic coordinate system, the laser displacement signal is converted into three-dimensional space, and the surface morphology of the object at the measurement point is measured through the iterative closest point algorithm based on the surface changes and texture characteristics of the object.

[0091] The laser displacement signal can only reflect the position information of the surface of the object being measured, but in order to more comprehensively describe the surface morphology, it is necessary to extract the surface texture features and surface changes. By processing the laser spot area, this information can be obtained, thereby providing richer data support for accurate measurement of surface morphology; when the laser beam is irradiated on the surface of the object being measured to form a laser spot, the laser spot area is detected and divided into multiple sub-areas of appropriate sizes. Each sub-area is processed by the local binary pattern. The local binary pattern algorithm generates a code reflecting the texture features of the sub-area by comparing the grayscale value relationship between the central pixel and the surrounding pixels in the sub-area, thereby forming a texture feature description of the sub-area.

[0092] At the same time, the laser displacement signals of adjacent frames are analyzed by the phase correlation method. The phase correlation method can accurately calculate the displacement between the laser displacement signals of adjacent frames, thereby obtaining the changes in the surface of the object under test at different times, including surface undulations and surface deformation. Through local binary pattern processing and phase correlation analysis, not only the texture characteristics of the surface of the object under test are obtained, but also the surface changes are accurately captured, providing rich and accurate data for subsequent measurement of surface morphology, making the description of the surface morphology more comprehensive and detailed.

[0093] The two-dimensional laser displacement signal cannot intuitively display the three-dimensional morphology of the surface of the object being measured. In order to achieve comprehensive and accurate measurement of the surface morphology, the laser displacement signal needs to be converted into three-dimensional space, so that the actual shape of the surface can be more realistically reflected. The laser displacement signal is converted into three dimensions through the laser triangulation method, combined with the conversion relationship between the laser coordinate system and the ultrasonic coordinate system. The laser triangulation method calculates the three-dimensional coordinates of the surface point of the object being measured in the laser coordinate system based on the emission angle, receiving angle and imaging position of the laser spot of the laser beam. Then, according to the conversion relationship between the laser coordinate system and the ultrasonic coordinate system, these three-dimensional coordinates are converted into a unified spatial coordinate system. Combined with the texture characteristics and surface changes of the object being measured, the surface point data obtained at different measurement positions and angles are fused through the iterative closest point algorithm. The iterative closest point algorithm continuously iterates to find the best matching relationship between the two sets of surface point data, aligns and merges them, and finally obtains the surface morphology of the object being measured at the measurement point.

[0094] The successfully obtained surface topography can intuitively and accurately present the three-dimensional shape of the surface of the object being measured. Combined with texture characteristics and surface changes, it can more realistically reflect the actual surface conditions, providing a reliable basis for subsequent analysis of surface features, calculation of topography parameters, and adjustment of the emission angle of the broadband ultrasonic beam. The accurate surface topography provides a data basis for calculating the curvature of each measuring point on the surface and extracting topography parameters. It also provides an intuitive reference for dynamically adjusting the emission angle of the broadband ultrasonic beam according to the surface topography, which helps to improve the accuracy and adaptability of thickness measurement.

[0095] Specifically, if Figure 3 As shown, the logic for adjusting the emission angle of the broadband ultrasonic beam includes:

[0096] Perform curvature analysis on the surface topography of the object at the measurement point, calculate the Gaussian curvature and average curvature of each measurement point to identify the surface feature area, refine the surface feature area through morphological operations, and extract the topography parameters of the object, including surface roughness and surface slope;

[0097] Configure the roughness threshold and slope threshold, compare the surface roughness and surface slope with the roughness threshold and slope threshold respectively, and preliminarily adjust the emission angle of the broadband ultrasonic beam;

[0098] After preliminarily adjusting the emission angle of the broadband ultrasonic beam, new laser displacement signals and ultrasonic echo signals are acquired in real time to respectively determine the initial and actual thickness values ​​of the object being measured at the measurement point.

[0099] Compare the fluctuations of the initial thickness value and the actual thickness value before and after adjustment, as well as the changes in the signal-to-noise ratio of the ultrasonic echo signal, and comprehensively judge whether to adjust the emission angle of the broadband ultrasonic beam again.

[0100] In order to gain a deeper understanding of the surface characteristics of the object being measured, it is necessary to further analyze the surface morphology, identify the surface feature areas, and extract the morphological parameters that can quantify the surface; perform curvature analysis on the surface morphology of the object being measured at the measurement point, and calculate the Gaussian curvature and average curvature of each measurement point. The Gaussian curvature and average curvature can reflect the degree of curvature and shape characteristics of the surface at the measurement point. According to the calculated curvature value, the curvature threshold range is set, and the measurement points with similar curvature characteristics are divided into different surface feature areas, including convex areas, concave areas, and flat areas.

[0101] For each surface feature area, morphological operations are used for refinement. Morphological operations remove noise points and irregular edges in the surface feature area through operations such as corrosion and expansion, making the boundaries of the surface feature area clearer and more accurate. Finally, the morphological parameters of the object under test are extracted based on the refined surface feature area. For surface roughness, it is quantified by calculating the standard deviation of the height values ​​of each measuring point in the surface feature area, while for surface slope, it is determined by calculating the angle between the normal vector of each measuring point in the surface feature area and the reference plane. Through curvature analysis, morphological operations and parameter extraction, the surface feature area of ​​the object under test is accurately identified, and important morphological parameters such as surface roughness and surface slope are quantified, providing accurate data for a comprehensive understanding of surface morphological characteristics, and also providing a quantitative basis for the subsequent adjustment of the emission angle of the broadband ultrasonic beam according to the surface morphology.

[0102] Based on the comparison results of the morphological parameters and the preset thresholds, the requirements of the current surface morphology for the emission angle of the broadband ultrasonic beam can be judged. In order to make the ultrasonic beam more effectively irradiate the surface of the object to be measured and obtain a more accurate ultrasonic echo signal for thickness measurement, it is necessary to preliminarily adjust the emission angle of the broadband ultrasonic beam according to the judgment results; pre-configure the roughness threshold and slope threshold, and compare the extracted surface roughness and surface slope with the corresponding roughness threshold and slope threshold respectively. If the surface roughness is greater than the roughness threshold, it means that the surface is relatively rough. At this time, the emission angle of the broadband ultrasonic beam is increased so that the broadband ultrasonic beam can irradiate the surface of the object to be measured in a wider range. This can increase the contact area between the broadband ultrasonic beam and the surface of the object to be measured, improve the coverage range of the ultrasonic echo signal, and reduce the signal loss caused by surface roughness.

[0103] If the surface slope is greater than the slope threshold, it indicates that the surface is tilted to a large extent. At this time, the emission angle of the broadband ultrasonic beam is adjusted so that the broadband ultrasonic beam is incident as perpendicularly as possible to the surface slope direction to ensure that the broadband ultrasonic beam can be reflected more effectively, thereby improving the intensity and quality of the ultrasonic echo signal and avoiding the weakening or inability to receive the reflected signal due to an improper incident angle. By comparing the morphological parameters with the corresponding threshold and adjusting the emission angle of the broadband ultrasonic beam accordingly, the emission of the broadband ultrasonic beam is more in line with the actual surface conditions of the object being measured, thereby improving the utilization rate of the broadband ultrasonic beam and the quality of the ultrasonic echo signal, and providing better signal conditions for the subsequent accurate measurement of the initial and actual thickness values.

[0104] After preliminarily adjusting the emission angle of the broadband ultrasonic beam, it is necessary to verify whether the current emission angle is appropriate and whether it can improve the accuracy of the measurement. Therefore, it is necessary to re-acquire the laser displacement signal and ultrasonic echo signal, and calculate the initial thickness value and actual thickness value of the measured object at the measurement point based on these new signals, so as to compare and analyze with the results before adjustment; after preliminarily adjusting the emission angle of the broadband ultrasonic beam, the laser emitter and ultrasonic transducer work again according to the adjusted parameters, and acquire new laser displacement signals and ultrasonic echo signals in real time to determine the initial thickness value and actual thickness value of the measured object at the measurement point respectively according to the above contents; by re-acquiring the laser displacement signal and ultrasonic echo signal and determining the initial thickness value and actual thickness value, new measurement results can be obtained based on the adjusted emission angle of the broadband ultrasonic beam, providing data support for evaluating the effect of the current emission angle adjustment, and helping to determine whether the current emission angle can improve the accuracy and reliability of the measurement.

[0105] The measurement results obtained after the preliminary adjustment of the emission angle of the broadband ultrasonic beam are not optimal. In order to further improve the accuracy and reliability of the measurement, it is necessary to conduct a comprehensive comparative analysis of the initial thickness value, actual thickness value and signal-to-noise ratio of the ultrasonic echo signal before and after the adjustment to determine whether the emission angle needs to be adjusted again to achieve the best measurement effect; the initial thickness value and actual thickness value obtained after the preliminary adjustment of the emission angle are compared with the corresponding values ​​before the adjustment to obtain the fluctuation of the initial thickness value and the actual thickness value, and at the same time analyze the change in the signal-to-noise ratio of the ultrasonic echo signal before and after the adjustment.

[0106] If the initial and actual thickness values ​​fluctuate significantly after adjustment, and the signal-to-noise ratio of the ultrasonic echo signal does not significantly improve or even decreases, it indicates that the currently adjusted emission angle is inappropriate and the emission angle of the broadband ultrasonic beam needs to be adjusted again. At this time, based on the current topographic parameters and measurement results, the emission angle should be adjusted again by a certain angle increment each time after the initial adjustment. If the initial and actual thickness values ​​tend to be stable after adjustment, and the signal-to-noise ratio of the ultrasonic echo signal is significantly improved, it indicates that the currently adjusted emission angle is relatively appropriate and does not need to be adjusted again. The current measurement result can be used for subsequent thickness value fusion and compensation correction operations. By comprehensively comparing and analyzing the measurement data before and after adjustment, it is possible to accurately determine whether the current emission angle of the broadband ultrasonic beam has reached the optimal state, avoid measurement errors caused by an inappropriate emission angle, further improve measurement accuracy and reliability, and ensure more accurate thickness measurement results. After determining the final emission angle of the broadband ultrasonic beam, the measurement results obtained based on this emission angle will be used for subsequent operations such as weight coefficient allocation, thickness value fusion, and compensation correction, playing a key role in the accuracy of the entire thickness measurement process and the reliability of the final measurement results.

[0107] S3. Dynamically assign a weight coefficient based on the signal-to-noise ratio of the laser displacement signal and the confidence level of the positioning position of the interlayer interface in the ultrasonic echo signal. According to the weight coefficient, the initial thickness value and the actual thickness value are fused to determine the thickness value of the measured object at the measuring point. At the same time, the ambient temperature, the surface state of the measured object, and the movement speed of the measured object are obtained in real time to compensate for the corrected thickness value.

[0108] Furthermore, the weight coefficient allocation sub-logic includes:

[0109] The signal-to-noise ratio of the laser displacement signal is determined by a sliding window algorithm, and the confidence level of the interlayer interface location in the ultrasonic echo signal is determined based on the reflection waveform of each interlayer interface.

[0110] The signal-to-noise ratio of the laser displacement signal and the confidence level of the location of the interlayer interface in the ultrasonic echo signal are used to assign weight coefficients to the laser displacement signal and the ultrasonic echo signal through fuzzy logic;

[0111] The thickness variation trend of the measured object is predicted through historical measurement data, and the weight coefficients of the laser displacement signal and the ultrasonic echo signal are corrected according to the thickness variation trend of the measured object.

[0112] The signal-to-noise ratio of the laser displacement signal and the confidence level of the interlayer interface location in the ultrasonic echo signal can directly reflect the reliability and accuracy of the two signals. In order to reasonably balance the contributions of the two signals when fusing the initial thickness value and the actual thickness value, it is necessary to first accurately calculate these two key indicators. For the laser displacement signal, a sliding window is performed on the time series of the laser displacement signal with a fixed time length as the window length. Within each window, the signal-to-noise ratio of the laser displacement signal within the window is determined by calculating the ratio of the useful power of the laser displacement signal to the noise power. The signal-to-noise ratio results of multiple consecutive windows are statistically analyzed, and the average value is taken to obtain the final signal-to-noise ratio of the laser displacement signal used for weight allocation.

[0113] Based on the identification and positioning of the interlayer interface, the characteristics of the reflected waveform of each interlayer interface are analyzed, and the ultrasonic echo signal is evaluated from multiple dimensions such as the clarity of the reflected waveform of the interlayer interface, the peak stability and the similarity with the theoretical waveform. Combined with the energy distribution of the ultrasonic echo signal, the confidence of the positioning position of each interlayer interface is comprehensively judged. If the reflected waveform of a certain interlayer interface is clear, the peak is prominent and the repeatability is good, a higher confidence is given; conversely, if the reflected waveform of the interlayer interface is fuzzy and there is interference, the confidence is lowered; finally, the confidence of all interlayer interfaces is comprehensively calculated to obtain the overall confidence of the positioning position of the interlayer interface in the ultrasonic echo signal; thereby, the quality of the laser displacement signal and the ultrasonic echo signal can be comprehensively and accurately quantified, providing an objective and reliable basis for the reasonable allocation of subsequent weight coefficients, avoiding the blindness of weight allocation, and improving the scientific nature of data fusion.

[0114] The relationship between the signal-to-noise ratio of the laser displacement signal and the confidence of the positioning position of the interlayer interface in the ultrasonic echo signal and the weight coefficient is not a simple linear relationship, and it is difficult to accurately calculate it through a fixed formula. Fuzzy logic can handle this uncertainty and nonlinear relationship, and flexibly allocate weight coefficients according to signal quality, so that the weight allocation is more in line with the actual measurement situation; establish fuzzy logic, including input variables, fuzzification modules, rule bases, inference engines and output variables, and use the signal-to-noise ratio of the laser displacement signal and the confidence of the positioning position of the interlayer interface in the ultrasonic echo signal as input variables. The fuzzification module converts the precise numerical value into fuzzy language variables, including low, medium and high, and pre-sets a series of fuzzy rules in the rule base. If the signal-to-noise ratio of the laser displacement signal is high and exceeds If the confidence level of the interlayer interface positioning in the acoustic echo signal is high, then based on the advantages of the laser displacement signal in surface topography measurement and the ultrasonic echo signal in interlayer interface positioning, by comparing the contribution of the two to the thickness value calculation in the current measurement scenario, a weight coefficient is dynamically allocated. Preferably, when the measurement requirement focuses on the impact of surface topography details on thickness, a higher weight is given to the laser displacement signal. When the interlayer structure of the measured object is complex and the positioning of the interlayer interface is more critical to the thickness value calculation, a higher weight is given to the ultrasonic echo signal. This makes the weight allocation more in line with the actual measurement requirements and the characteristics of the laser displacement signal and the ultrasonic echo signal. These rules are summarized based on a large amount of experimental data and actual measurement experience, covering various possible signal quality combinations.

[0115] Based on the input fuzzy linguistic variables, the inference engine searches for matching rules in the rule base and performs inference operations through the fuzzy inference algorithm to obtain preliminary fuzzy values ​​of weight coefficients. Finally, the fuzzy values ​​are converted into precise numerical values ​​through the defuzzification module to obtain the weight coefficients of the laser displacement signal and the ultrasonic echo signal. In this way, the weight coefficients can be dynamically and flexibly allocated according to the quality of the laser displacement signal and the ultrasonic echo signal, fully considering the uncertainty factors in the measurement process, making the weight allocation more in line with the actual situation, and improving the accuracy and reliability of the thickness value fusion.

[0116] The thickness of the object being measured will change with factors such as time and working conditions. If the weight coefficient is assigned only based on the current signal quality, it will not be able to adapt to the impact of thickness changes. By analyzing historical measurement data to predict the thickness change trend and correcting the weight coefficient accordingly, the weight assignment can be more forward-looking and the accuracy of the measurement results can be improved. The measurement data within a certain period of time is recorded, including the initial thickness value, actual thickness value, laser displacement signal-to-noise ratio, and confidence level of the positioning position of the interlayer interface in the ultrasonic echo signal for each measurement. The historical measurement data is processed through a time series analysis algorithm to predict the future thickness change trend of the object being measured, including whether the thickness is increasing, decreasing, or remaining stable.

[0117] According to the predicted thickness change trend, a corresponding weight correction strategy is formulated. If the predicted thickness shows an upward trend and the laser displacement signal has a higher sensitivity in measuring thickness changes, the weight coefficient of the laser displacement signal is appropriately increased; conversely, if the ultrasonic echo signal can better reflect the thickness change trend, the weight of the ultrasonic echo signal is increased. By continuously monitoring the thickness change trend and correcting the weight coefficient in real time according to the actual situation, the distribution of the weight coefficient is always adapted to the actual state of the measured object; thereby, the dynamic changes in the thickness of the measured object can be fully considered, the weight distribution is more adaptive and forward-looking, and the measurement error caused by fixed weights is avoided, further improving the accuracy and reliability of thickness measurement. The corrected weight coefficient is used for the subsequent calculation of the fused thickness value, so that the fusion result can more accurately reflect the actual thickness of the measured object, and at the same time provides a more reasonable weight basis for subsequent judgment of whether the weight coefficient needs to be corrected again and for thickness value compensation correction.

[0118] Furthermore, the thickness value determination sub-logic includes:

[0119] According to the weight coefficients of the laser displacement signal and the ultrasonic echo signal, the initial thickness value and the actual thickness value are fused by the weighted average method to obtain the fused thickness value;

[0120] Calculate the thickness deviation between the fused thickness value and the mean of historical measurement data, configure the deviation threshold, compare the thickness deviation with the deviation threshold to identify outliers, and use cubic spline interpolation to fit the normal fused thickness value to replace the outliers;

[0121] Monitor the signal-to-noise ratio of the laser displacement signal and the confidence level of the location of the interlayer interface in the ultrasonic echo signal to determine whether to correct the weight coefficients of the laser displacement signal and the ultrasonic echo signal again to correct the fusion thickness value;

[0122] Continuously obtain multiple frames of corrected fused thickness values, and determine the thickness value of the measured object at the measuring point according to the average value of the multiple frames of corrected fused thickness values.

[0123] The initial thickness value is calculated based on the ultrasonic echo signal, and the actual thickness value is determined after measuring the surface topography in combination with the laser displacement signal. The two reflect the thickness information of the object being measured from different angles. By fusing the two through weighted averaging, the advantages of the two signals can be comprehensively utilized to obtain a more accurate thickness measurement result. According to the weight coefficients of the laser displacement signal and the ultrasonic echo signal assigned and corrected in the previous steps, as well as the calculated initial thickness value and actual thickness value, a weighted average calculation is performed. The initial thickness value is multiplied by the weight coefficient of the ultrasonic echo signal, and the actual thickness value is multiplied by the weight coefficient of the laser displacement signal. The two products are then added to obtain a fused thickness value. By fusing the initial thickness value and actual thickness value through weighted averaging, the respective advantages of the laser displacement signal and the ultrasonic echo signal are fully utilized, the limitations of single signal measurement are compensated, and the fused thickness value can more accurately reflect the actual thickness of the object being measured, thereby improving the accuracy and reliability of thickness measurement.

[0124] During the measurement process, due to various accidental factors, including sudden noise interference and momentary equipment failure, the fusion thickness value may fluctuate abnormally. These abnormal values ​​will seriously affect the accuracy of the measurement results. Therefore, it is necessary to judge and process the abnormal values ​​of the fusion thickness value to ensure the reliability of the final thickness value. First, the thickness deviation between the fusion thickness value and the mean of the historical measurement data is calculated. The fusion thickness values ​​within a certain period of time are statistically analyzed, and their average value is calculated as the mean of the historical measurement data. Then, according to the measurement accuracy requirements and actual measurement conditions, the appropriate deviation threshold is configured.

[0125] The calculated thickness deviation is compared with the deviation threshold. If the thickness deviation is greater than the deviation threshold, the fused thickness value is judged as an outlier and processed using the cubic spline interpolation method. The normal fused thickness values ​​before and after the outlier are selected as nodes, and a smooth curve is fitted using the cubic spline interpolation algorithm. The normal fused thickness value corresponding to the time point is calculated based on the curve to replace the original outlier. Through outlier judgment and processing, abnormal data caused by accidental factors are effectively eliminated, the interference of outliers on the measurement results is avoided, the fused thickness value is made more stable and reliable, and the anti-interference ability and measurement accuracy of the entire thickness measurement process are improved.

[0126] During the measurement process, the signal-to-noise ratio of the laser displacement signal and the confidence level of the interlayer interface location in the ultrasonic echo signal will change, which will affect the rationality of the previously assigned weight coefficient. To ensure the accuracy of the thickness value, it is necessary to monitor the signal quality in real time and dynamically adjust the weight coefficient according to the changes. The signal-to-noise ratio of the laser displacement signal and the confidence level of the interlayer interface location in the ultrasonic echo signal are continuously monitored. When a significant change in signal quality is detected, that is, a sudden drop in the signal-to-noise ratio of the laser displacement signal or a significant increase in the confidence level of the ultrasonic echo signal, the new signal quality indicator is input into the fuzzy logic.

[0127] Based on the new input variables, fuzzy logic re-performs inference operations according to pre-set rules to obtain a new weight coefficient. The new weight coefficient is compared with the currently used weight coefficient. If the difference is greater than the set weight threshold, the fused thickness value is recalculated using the new weight coefficient to obtain a corrected fused thickness value. By dynamically monitoring the signal quality and correcting the weight coefficient, it can promptly adapt to changes in signal quality during the measurement process, ensure that the weight distribution is always in a reasonable state, make the fused thickness value more accurately reflect the actual thickness of the measured object, and improve the adaptability and measurement accuracy of the thickness measurement process.

[0128] In order to improve the accuracy and stability of thickness measurement results and avoid the influence of accidental errors in single measurements, it is necessary to perform statistical analysis on the fused thickness values ​​after correction of multiple frames and take the average as the final thickness value to obtain more reliable measurement results; continuously store the fused thickness values ​​after correction of multiple frames. When the number of stored frames reaches the set number, these fused thickness values ​​are summed and then divided by the number of frames to calculate the average value. The average value is the final thickness value of the measured object at the measuring point; thereby effectively reducing the accidental error of a single measurement, improving the accuracy and stability of the measurement results, and making the final thickness value more truly reflect the actual thickness of the measured object at the measuring point, providing basic data for subsequent thickness value compensation correction based on environmental factors.

[0129] Specifically, the thickness compensation correction logic includes:

[0130] Acquire the ambient temperature in real time, configure the temperature threshold, compare the ambient temperature with the temperature threshold to determine the expansion properties of the object being measured, and calculate the thickness change of the object being measured based on the expansion properties of the object being measured;

[0131] Analyze the relationship between surface roughness and the phase deviation of the laser displacement signal to calculate the thickness compensation of the measured object, and perform spectrum analysis on the laser displacement signal to determine whether there is any abnormality on the surface of the measured object. If there is any abnormality on the surface of the measured object, dynamically adjust the delay compensation of the ultrasonic echo signal;

[0132] Obtain the moving speed of the object being measured along the axis of the laser beam, reconstruct the frequency of the ultrasonic echo signal based on the Doppler effect principle, and dynamically adjust the acquisition frequency of the laser displacement signal and the ultrasonic echo signal according to the moving speed of the object being measured;

[0133] After adjusting the laser displacement signal and the ultrasonic echo signal, the ambient temperature, the surface state of the object being measured, the movement speed of the object being measured and the thickness value of the object being measured at the measuring point are continuously obtained, and the thickness value is compensated and corrected in combination with the thickness change of the object being measured and the thickness compensation amount.

[0134] Ambient temperature changes cause the object being measured to expand and contract, resulting in thickness variations. If temperature is not considered, the measured thickness value will not accurately reflect the object's true thickness. Therefore, it is necessary to obtain the ambient temperature in real time and compensate for the thickness change based on the temperature change. The ambient temperature is obtained in real time and compared with pre-configured temperature thresholds based on pre-stored thermal expansion parameters of the object being measured (these parameters are obtained through temperature-thickness relationship experiments on the object being measured). The expansion properties of the object being measured are determined, that is, whether the object is in an expanded or contracted state. The thickness change caused by the temperature change is then calculated based on the thermal expansion parameters and the temperature change. This thickness change is then added to or subtracted from the final measured thickness value to compensate for the temperature effect. This effectively eliminates the influence of temperature changes on the thickness measurement result, ensuring that the measured thickness value more accurately reflects the true thickness of the object being measured at the current temperature, thereby improving the measurement accuracy and applicability of the thickness measurement process in different temperature environments.

[0135] The surface roughness of the object being measured will affect the reflection characteristics of the laser displacement signal, resulting in phase deviation, which in turn affects the accuracy of thickness measurement. At the same time, abnormal conditions on the surface of the object being measured will change the propagation characteristics of the ultrasonic echo signal. Therefore, it is necessary to analyze the impact of the surface state on the ultrasonic echo signal and make corresponding compensation corrections; analyze the relationship between the surface roughness parameters and the phase deviation of the laser displacement signal. This relationship needs to be obtained by fitting experimental data, and calculate the thickness compensation amount caused by surface roughness.

[0136] At the same time, the laser displacement signal is analyzed spectrally. By identifying abnormal features in the signal spectrum, it is determined whether there are abnormal conditions such as oil and water stains on the surface of the measured object. When an abnormality is detected on the surface of the measured object, the delay compensation of the ultrasonic echo signal is dynamically adjusted according to the type and degree of the abnormality. If there is oil on the surface of the measured object, the propagation speed of the ultrasonic wave on the measured object will change. In this case, the propagation time of the ultrasonic echo signal is adjusted accordingly to correct the thickness measurement error caused by the abnormal surface of the measured object. Finally, the calculated thickness compensation and the adjusted delay compensation of the ultrasonic echo signal are applied to the current thickness value to complete the compensation correction for the influence of surface conditions. This effectively eliminates the interference of surface conditions on the laser displacement signal and ultrasonic echo signal, improves the accuracy of thickness measurement, makes the measurement result more truly reflect the actual thickness of the measured object, and enhances the adaptability of the thickness measurement process to different surface conditions.

[0137] The speed of the object being measured along the axis of the laser beam will cause the ultrasonic echo signal to produce a Doppler frequency shift, affecting the frequency characteristics of the signal. It will also affect the acquisition time of the laser displacement signal and the ultrasonic echo signal. In order to obtain accurate thickness measurement results, it is necessary to compensate and correct the signal according to the speed of the object being measured. By obtaining the speed of the object being measured along the axis of the laser beam, the frequency of the ultrasonic echo signal is reconstructed according to the principle of the Doppler effect. By adjusting the acquisition frequency of the ultrasonic echo signal, it is restored to the frequency characteristics of the object in the static state, eliminating the influence of the Doppler frequency shift.

[0138] At the same time, according to the movement speed of the object being measured, the acquisition frequency of the laser displacement signal and the ultrasonic echo signal is dynamically adjusted. When the movement speed of the object being measured is faster, the acquisition frequency of the laser displacement signal and the ultrasonic echo signal is increased to ensure that the signals of the object at different positions can be accurately captured. When the object moves slowly, the acquisition frequency is appropriately reduced to reduce the amount of data processing. Finally, based on the frequency reconstruction and the signal after acquisition frequency adjustment, the thickness value is recalculated and combined with the thickness value previously compensated for the ambient temperature and surface condition to obtain the final compensated thickness value.

[0139] This effectively eliminates the effects of Doppler frequency shift and measured object motion on signal acquisition, ensuring that the ultrasonic echo signal and laser displacement signal can accurately reflect the actual state of the measured object, improving the accuracy and reliability of thickness measurement when the object is in motion, and adapting to dynamic measurement scenarios. The final compensated and corrected thickness value comprehensively considers the influence of multiple factors such as ambient temperature, surface state, and movement speed, and can most accurately reflect the actual thickness of the measured object. This thickness value can serve as the ultimate basis for applications such as product quality assessment and production process control, and also provides accurate data support for subsequent data analysis and optimization.

[0140] Example 2:

[0141] like Figure 4 As shown, an embodiment of the present application provides a device structure diagram of a non-contact thickness measurement device, which includes a laser group 1, an ultrasonic group 2, a base 3 and a positioning platform 4 for the object to be measured.

[0142] Laser group 1 is used to emit a laser beam to the surface of the object to be measured and receive the laser displacement signal reflected by the object to be measured. By processing the laser displacement signal, the surface morphology of the object to be measured at the measurement point is measured, and the actual thickness value of the object to be measured at the measurement point is determined.

[0143] After receiving the start measurement instruction, laser group 1 directionally emits a laser beam toward the surface of the object to be measured, providing basic incident light for the subsequent acquisition of laser displacement signals and surface topography measurement. This is the starting action that triggers laser measurement in the entire thickness measurement process. It then receives the laser displacement signal reflected by the object to be measured, processes and analyzes the laser displacement signal according to the logical steps in the method, and measures the surface topography of the object to be measured at the measurement point. The vertical distance to the positioning position of the interlayer interface in the ultrasonic echo signal is then determined based on the surface topography to determine the actual thickness value of the object to be measured at the measurement point.

[0144] Ultrasonic group 2 is used to transmit a broadband ultrasonic beam to the surface of the object to be measured and obtain ultrasonic echo signals to identify and locate the interlayer interface of the object to be measured, and calculate the initial value of the thickness of the object to be measured at the measuring point by analyzing the ultrasonic echo signals.

[0145] After receiving the start measurement instruction, ultrasonic group 2 emits a broadband ultrasonic beam to the surface of the object under test. It uses the broadband characteristics to cover the reflection requirements of the interfaces between different materials and different depths inside the object under test, providing incident waves of diverse frequencies for identifying the interlayer interfaces. This is the initial excitation action for ultrasonic thickness measurement. It receives the ultrasonic echo signal reflected by the object under test, processes the ultrasonic echo signal through wavelet packet decomposition and waveform deconvolution algorithm to identify and locate the interlayer interface of the object under test, and calculates the initial thickness value of the object under test at the measurement point based on the time difference of the interlayer interface reflection in the ultrasonic echo signal.

[0146] After receiving the start measurement instruction, ultrasonic group 2 cooperates with laser group 1 to synchronously emit the laser beam and broadband ultrasonic beam according to the trigger signal, and generate a timestamp signal at the same time, preliminarily aligning the emission time of the laser beam and the broadband ultrasonic beam, and then obtains the laser displacement signal and ultrasonic echo signal reflected by the object to be measured, and performs spatiotemporal registration on the laser displacement signal and the ultrasonic echo signal to achieve alignment of the ultrasonic echo signal and the laser displacement signal in the time and space dimensions, providing basic alignment data for subsequent thickness measurement.

[0147] A laser group 1, an ultrasonic group 2 and a positioning platform 4 for the object to be measured are provided on the base 3. The base 3 is fixedly connected to the laser group 1 and the ultrasonic group 2. The base 3 is slidably connected to the positioning platform 4 for the object to be measured to realize the movement and positioning of the positioning platform 4 for the object to be measured; the positioning platform 4 for the object to be measured is used to fix and position the object to be measured.

[0148] The base 3 provides a stable installation foundation for the laser group 1 and the ultrasonic group 2, and realizes a fixed connection through a mechanical connection structure. The mechanical connection structure includes a mounting flange and a bolt group, which ensures the coordinated pointing of the laser beam and the broadband ultrasonic beam in space, and meets the hardware layout requirements for the spatiotemporal alignment of multi-source signals in the thickness measurement method. At the same time, it is slidably connected to the positioning platform 4 of the object to be measured through a sliding guide rail, thereby realizing the movement and precise positioning of the positioning platform 4 of the object to be measured.

[0149] The positioning platform 4 of the object to be measured firmly fixes the object to be measured through a clamp to prevent the object to be measured from moving during the measurement process, realizes the precise positioning of the object to be measured on the platform, ensures that the laser beam and broadband ultrasonic beam emitted by the laser group 1 and the ultrasonic group 2 can cover the preset measurement points, and provides the position basis of the object to be measured for stable and repeatable measurement in the thickness measurement method.

[0150] Before thickness measurement begins, an operator or an automatic loading and unloading system places the object to be measured on a positioning platform. The positioning platform secures the object using a fixture. Then, based on the object's size and measurement requirements, the positioning platform is controlled to move along guide rails. In conjunction with the measurement ranges of laser group 1 and ultrasonic group 2, the area to be measured is precisely moved to within the coverage of the laser beam and broadband ultrasonic beam. This completes the positioning of the object before measurement and provides stable and accurate spatial positioning of the object. If multiple points on the object need to be measured, the positioning platform is controlled to move the object along a preset measurement path, which includes point-by-point scanning and area traversal. Each measurement point is sequentially moved to the effective measurement position of laser group 1 and ultrasonic group 2. Laser group 1 and ultrasonic group 2 synchronously acquire the laser displacement signal and ultrasonic echo signal at the corresponding point, ensuring the thickness measurement method's requirements for measuring the object at multiple locations. During the measurement process, the positioning platform continuously maintains the object's position stable or fine-tunes it according to the correction path, coordinating the calculation of initial and actual thickness values ​​and fusion corrections until the thickness measurement process for all measurement points is completed and a complete thickness measurement result is output.

[0151] Since the principle of solving the problem by the device in the embodiment of the present application is similar to the method described above in the embodiment of the present application, the implementation of the device refers to the implementation of the method, and the repeated parts will not be repeated.

Claims

1. A non-contact thickness measurement method, characterized in that: include: The system emits a laser beam and a broadband ultrasonic beam to the surface of the object to be measured, obtains the laser displacement signal and ultrasonic echo signal reflected by the object to be measured, performs spatiotemporal registration on the laser displacement signal and ultrasonic echo signal, and monitors the movement speed of the object to be measured and the vibration of the detection equipment to dynamically compensate for the laser displacement signal and ultrasonic echo signal; The ultrasonic echo signal is analyzed using a waveform deconvolution algorithm to identify and locate the interlayer interface of the object being measured. The initial thickness value of the object being measured at the measurement point is calculated based on the time difference of the interlayer interface reflection in the ultrasonic echo signal. At the same time, the laser displacement signal is processed using laser triangulation to measure the surface morphology of the object being measured at the measurement point. The vertical distance from the surface morphology of the object being measured at the measurement point to the location of the interlayer interface in the ultrasonic echo signal is calculated to determine the actual thickness value of the object being measured at the measurement point. The emission angle of the broadband ultrasonic beam is dynamically adjusted according to the surface morphology. A weight coefficient is dynamically assigned based on the signal-to-noise ratio of the laser displacement signal and the confidence level of the positioning of the interlayer interface in the ultrasonic echo signal. The initial thickness value and the actual thickness value are fused according to the weight coefficient to determine the thickness value of the measured object at the measuring point. At the same time, the ambient temperature, the surface state of the measured object, and the movement speed of the measured object are obtained in real time to compensate and correct the thickness value.

2. A non-contact thickness measurement method according to claim 1, characterized in that: The compensation logic of the laser displacement signal and the ultrasonic echo signal includes: Obtain the velocity of the object being measured along the axis of the laser beam, reconstruct the frequency of the ultrasonic echo signal based on the Doppler effect principle, and correct the acquisition time of the laser displacement signal in real time based on the geometric relationship of the triangulation method; Monitor the vibration of the detection equipment to determine the phase offset of the laser displacement signal, and correct and compensate the laser displacement signal through the phase unwrapping algorithm; The vibration displacement of the equipment is determined according to the vibration of the detection equipment, and the propagation path of the ultrasonic echo signal is adjusted in real time based on the vibration displacement of the equipment, and the emission angle of the broadband ultrasonic beam is adjusted. At the same time, the time delay compensation amount is determined according to the propagation path of the ultrasonic echo signal to compensate the ultrasonic echo signal.

3. A non-contact thickness measurement method according to claim 2, characterized in that: The execution sub-logic of the spatiotemporal registration includes: A laser beam and a broadband ultrasonic beam are emitted toward the surface of the object being measured, and a timestamp signal is generated simultaneously to preliminarily align the emission times of the laser beam and the broadband ultrasonic beam; Acquire the laser displacement signal and ultrasonic echo signal reflected by the measured object, calculate the time difference between the laser displacement signal and the ultrasonic echo signal through the cross-correlation algorithm, and perform interpolation correction on the time point of the ultrasonic echo signal based on the time difference and the difference in acquisition frequency; Determine the laser coordinate system of the laser displacement signal and the ultrasonic coordinate system of the ultrasonic echo signal, and judge the conversion relationship between the laser coordinate system and the ultrasonic coordinate system. Dynamically adjust the spatial relationship between the laser displacement signal and the ultrasonic echo signal according to the conversion relationship to perform spatiotemporal alignment of the laser displacement signal and the ultrasonic echo signal.

4. A non-contact thickness measurement method according to claim 3, characterized in that: The identification and positioning logic of the inter-layer interface includes: The ultrasonic echo signal is decomposed into multiple frequency bands by wavelet packet decomposition, the energy entropy value of each frequency band is calculated, and the frequency bands are filtered according to the energy entropy value to obtain the interface reflection signal; The interface reflection signal is processed by waveform deconvolution algorithm to separate the interface reflection wave and identify the reflection waveform of each interlayer interface; The peak position of the reflected waveform of each interlayer interface is determined by a dynamic threshold search algorithm, and the location of the interlayer interface in the measured object is determined in combination with the propagation velocity of the ultrasonic echo signal to identify and locate the interlayer interface.

5. A non-contact thickness measurement method according to claim 4, characterized in that: The adjustment logic of the emission angle of the broadband ultrasonic beam includes: Perform curvature analysis on the surface topography of the object at the measurement point, calculate the Gaussian curvature and average curvature of each measurement point to identify the surface feature area, refine the surface feature area through morphological operations, and extract the topography parameters of the object, including surface roughness and surface slope; Configure the roughness threshold and slope threshold, compare the surface roughness and surface slope with the roughness threshold and slope threshold respectively, and preliminarily adjust the emission angle of the broadband ultrasonic beam; After preliminarily adjusting the emission angle of the broadband ultrasonic beam, new laser displacement signals and ultrasonic echo signals are acquired in real time to respectively determine the initial and actual thickness values ​​of the object being measured at the measurement point. Compare the fluctuations of the initial thickness value and the actual thickness value before and after adjustment, as well as the changes in the signal-to-noise ratio of the ultrasonic echo signal, and comprehensively judge whether to adjust the emission angle of the broadband ultrasonic beam again.

6. A non-contact thickness measurement method according to claim 5, characterized in that: The surface topography measurement sub-logic includes: Monitor the laser spot area formed by the laser beam on the surface of the object being measured, divide the laser spot area into multiple sub-areas, and process each sub-area through local binary pattern to form texture features; The displacement of the laser displacement signals of adjacent frames is calculated by the phase correlation method to obtain the surface changes of the object being measured; Through laser triangulation, combined with the conversion relationship between the laser coordinate system and the ultrasonic coordinate system, the laser displacement signal is converted into three-dimensional space, and the surface morphology of the object at the measurement point is measured through the iterative closest point algorithm based on the surface changes and texture characteristics of the object.

7. A non-contact thickness measurement method according to claim 6, characterized in that: The thickness value compensation correction logic includes: Acquire the ambient temperature in real time, configure the temperature threshold, compare the ambient temperature with the temperature threshold to determine the expansion properties of the object being measured, and calculate the thickness change of the object being measured based on the expansion properties of the object being measured; Analyze the relationship between surface roughness and the phase deviation of the laser displacement signal to calculate the thickness compensation of the measured object, and perform spectrum analysis on the laser displacement signal to determine whether there is any abnormality on the surface of the measured object. If there is any abnormality on the surface of the measured object, dynamically adjust the delay compensation of the ultrasonic echo signal; Obtain the moving speed of the object being measured along the axis of the laser beam, reconstruct the frequency of the ultrasonic echo signal based on the Doppler effect principle, and dynamically adjust the acquisition frequency of the laser displacement signal and the ultrasonic echo signal according to the moving speed of the object being measured; After adjusting the laser displacement signal and the ultrasonic echo signal, the ambient temperature, the surface state of the object being measured, the movement speed of the object being measured and the thickness value of the object being measured at the measuring point are continuously obtained, and the thickness value is compensated and corrected in combination with the thickness change of the object being measured and the thickness compensation amount.

8. A non-contact thickness measurement method according to claim 7, characterized in that: The weight coefficient allocation sub-logic includes: The signal-to-noise ratio of the laser displacement signal is determined by a sliding window algorithm, and the confidence level of the interlayer interface location in the ultrasonic echo signal is determined based on the reflection waveform of each interlayer interface. The signal-to-noise ratio of the laser displacement signal and the confidence level of the location of the interlayer interface in the ultrasonic echo signal are used to assign weight coefficients to the laser displacement signal and the ultrasonic echo signal through fuzzy logic; The thickness variation trend of the measured object is predicted through historical measurement data, and the weight coefficients of the laser displacement signal and the ultrasonic echo signal are corrected according to the thickness variation trend of the measured object.

9. A non-contact thickness measurement method according to claim 8, characterized in that: The thickness value determination sub-logic includes: The initial thickness value and the actual thickness value are fused by weighted average method according to the weight coefficient of the laser displacement signal and the ultrasonic echo signal to obtain the fused thickness value; Calculate the thickness deviation between the fused thickness value and the mean of historical measurement data, configure the deviation threshold, compare the thickness deviation with the deviation threshold to identify outliers, and use cubic spline interpolation to fit the normal fused thickness value to replace the outliers; Monitor the signal-to-noise ratio of the laser displacement signal and the confidence level of the location of the interlayer interface in the ultrasonic echo signal to determine whether to correct the weight coefficients of the laser displacement signal and the ultrasonic echo signal again to correct the fusion thickness value; Continuously obtain multiple frames of corrected fused thickness values, and determine the thickness value of the measured object at the measuring point according to the average value of the multiple frames of corrected fused thickness values.

10. A non-contact thickness measurement device, used to implement a non-contact thickness measurement method according to any one of claims 1 to 9, characterized in that: Included: laser group (1) and ultrasound group (2); The laser group (1) is used to emit a laser beam to the surface of the object to be measured, and receive a laser displacement signal reflected by the object to be measured, and to measure the surface topography of the object to be measured at a measuring point by processing the laser displacement signal, and to determine the actual value of the thickness of the object to be measured at the measuring point; The ultrasonic group (2) is used to transmit a broadband ultrasonic beam to the surface of the object to be measured and obtain an ultrasonic echo signal to identify and locate the interlayer interface of the object to be measured, and calculate the initial value of the thickness of the object to be measured at the measuring point by analyzing the ultrasonic echo signal.

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