A laser large-range high-precision three-way joint measuring method and device

Abstract

A kind of laser wide-range high-precision three-way joint measurement method and device, at the crack of the structure to be measured both ends, respectively, the corresponding receiving device B of emission device A is arranged, with the plane where crack is as reference to establish three-dimensional rectangular coordinate system, when the position of the light spot emitted by emission device A is identified to change, main control circuit in receiving device B runs and calculates light spot position change data, finally calculates the displacement in horizontal direction, longitudinal direction and vertical direction;The present application realizes the accurate measurement of crack in horizontal direction, longitudinal direction and depth direction, has greater measurement range, can adapt to complex engineering environment, and has higher measurement precision and reliability.

Description

Technical Field

[0001] This invention relates to the field of engineering measurement technology, and in particular to a laser large-range high-precision three-dimensional seam measurement method and device. Background Technology

[0002] In many large-scale engineering structures, such as bridges, dams, and tunnels, deformation monitoring is crucial. Among these, crack monitoring is a key indicator for assessing structural safety. Traditional crack measurement methods often struggle to simultaneously meet the requirements of large measurement range and high accuracy. For example, some contact measuring instruments have limited ranges and are susceptible to environmental interference, while some non-contact measurement methods lack ideal accuracy. With the continuous development of engineering technology, the need for large-range, high-precision measurement methods for cracks in three directions (lateral, longitudinal, and depth) is becoming increasingly urgent.

[0003] Traditional crack measurement methods mainly include mechanical measurement, electrical measurement, and some simple optical measurement methods. Mechanical measurement methods, such as vernier calipers and micrometers, can provide a certain level of accuracy within a small measuring range, but their range is limited, and they are inconvenient to operate in practical engineering applications. They are difficult to use for measuring long-distance cracks on large structures, and their applicability to crack measurements in special environments (such as high temperature, high humidity, and strong corrosion) is poor. Electrical measurement methods, such as resistance strain gauge sensors, are susceptible to electromagnetic interference and have poor long-term stability; their measurement accuracy is also difficult to guarantee in complex environments. Existing optical measurement methods, such as ordinary image recognition-based methods, while having the advantage of non-contact measurement, struggle to balance the requirements of large measuring range and high accuracy, and exhibit significant errors in depth measurements.

[0004] With the rapid development of laser technology, it has many advantages such as good directionality, high brightness, good monochromaticity, and strong coherence, providing new solutions for crack measurement. For example, patent application CN219454983U discloses an optical crack measuring instrument. During crack measurement, the laser detector is kept at a constant distance from the ground to improve the accuracy of crack measurement. However, it cannot measure cracks from multiple directions, and there is no corresponding algorithm to improve accuracy. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a laser large-range high-precision three-dimensional crack measurement method and device, so as to realize accurate measurement of cracks in the transverse, longitudinal and depth directions, with a large measurement range, adaptable to complex engineering environments, and with high measurement accuracy and reliability.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A high-precision, three-dimensional gap measurement method using laser with a large range includes the following steps:

[0008] Step 1: At both ends of the crack in the structure to be tested, a transmitting device A and a corresponding receiving device B are respectively arranged. The transmitting device A transmits a laser beam signal to the receiving device B, and the receiving device B collects and processes the image spot signal.

[0009] Step 2: Establish a three-dimensional rectangular coordinate system based on the plane where the crack is located. One coordinate axis is parallel to the expected lateral expansion direction of the crack, another coordinate axis is parallel to the expected longitudinal expansion direction of the crack, and the third coordinate axis is perpendicular to the depth direction of the crack surface. The position coordinates of the centroid of the initial laser beam signal spot in the three directions are determined in the three-dimensional coordinate system. During measurement, when the change in the spot position is detected, the main control circuit in the receiving device B calculates the spot position change data and finally calculates the displacement of the spot in the lateral, longitudinal, and vertical directions, which is the displacement of the crack.

[0010] Step 3: Combine the displacement of the light spots in the horizontal, vertical and longitudinal directions with the measurement time information to generate crack data for a certain time period and archive it.

[0011] The transmitting device A is fixed on one side of the gap being measured. A laser emitting head 2 is installed on the protruding end 1 of the transmitting device A. The laser emitting head 2 is arranged in the X, Y, and Z directions respectively, with at least two emitting heads in each direction. Alternatively, the light path emitted by the laser emitting head 2 is divided into two or more paths to form a symmetrical dual-light knife or multi-light knife.

[0012] The receiving device B is a cubic opaque box fixed on the other side of the slit being measured. The protruding end 1 of the transmitting device A extends into the receiving device B. Two photoelectric devices 3 are arranged on the inner wall of the receiving device B in the X, Y, and Z directions respectively to receive the laser beam signal emitted by the transmitting device A. The X, Y, and Z direction images received by the photoelectric devices 3 are used to run a spot centroid algorithm or data fitting method through the main control circuit inside the receiving device B to obtain the spot centroid data and displacement data.

[0013] The aforementioned optoelectronic device 3 is a CCD or PSD.

[0014] The laser beam signal emitted by the transmitting device A is generated by modulating the laser beam into a linear light source, with at least two transmitting heads in each direction, or by dividing the emission light path into two or more paths to form a symmetrical dual-beam or multi-beam beam. In the dual-beam beam, each group of beams consists of two parallel lasers, forming the shape required for measurement.

[0015] Error compensation for measurement is achieved by using the symmetrical double-light blade: when the rotation of the protruding end 1 of the transmitting device A causes an error, the symmetrical double-light blade and the corresponding photoelectric device 3 are arranged so that the rotation of the transmitting end causes the laser image data received by the corresponding double photoelectric device 3 in the receiving device B to increase and decrease, thereby realizing data compensation and correction and eliminating the influence of the rotation of the protruding end 1 of the transmitting device A on the measurement results.

[0016] The displacement in step 2 is measured in the following specific process:

[0017] Step (2.1): The protruding end 1 of the transmitting device A is equipped with a laser emitting head 2 as the light source end in the X, Y and Z directions. The laser light source emitted in the X, Y and Z directions corresponds to the photoelectric device 3 in the three directions of the inner wall of the receiving device B, or the dual light knife or multi light knife divided into two or more paths corresponds to the photoelectric device (3) in the three directions of the inner wall of the receiving device B.

[0018] Step (2.2): When the gap to be measured changes displacement only along the X direction, the transmitting device A fixed on one side changes displacement. After it emits laser, the spot signal received by the receiving device B at the receiving end also changes. Based on the change of the center of gravity of the spot, the change of the spot displacement in the X direction can be calculated.

[0019] Step (2.3) and similarly step (2.2) are performed. When the gap only changes displacement along the Y direction, the light spot signal is received at the receiving end, and the change in the light spot displacement in the Y direction can be calculated based on the change in the center of gravity of the light spot.

[0020] Step (2.4) and similarly step 2.2: when the gap only changes displacement along the Z direction, the light spot signal is received at the receiving end, and the change in the light spot displacement in the Z direction can be calculated based on the change in the center of gravity of the light spot.

[0021] Step (2.5): The actual movement of the gap occurs simultaneously in multiple directions. The change in the centroid displacement of the light spot in the three directions calculated at the receiving end according to steps (2.2)-(2.4) is the change in the gap displacement.

[0022] The displacement change is obtained using a spot centroid algorithm or a data fitting method. Specifically, the spot centroid algorithm calculates the center position of the spot at a given moment based on a weighted average of pixel grayscale values, as shown in the following formula:

[0023] x_c=ΣΣ(x_ij*I_ij) / ΣΣ(I_ij)

[0024] y_c=ΣΣ(y_ij*I_ij) / ΣΣ(I_ij)

[0025] Where x_c and y_c are the coordinates of the light spot center; I_ij is the gray value of pixel (i,j) after background subtraction, and x_ij and y_ij are the pixel coordinates in the horizontal and vertical directions, respectively; subtracting the light spot center coordinates obtained at different times gives the change in displacement.

[0026] The data fitting method described above is as follows: assuming the light spot intensity distribution conforms to a two-dimensional Gaussian model, a light spot region is selected, and the Levenberg-Marquardt method is used to fit the pixel coordinates and gray values. The center of the light spot is obtained through fitting, as shown in the following formula:

[0027]

[0028] Where I(x,y) represents the light intensity at the selected spot area coordinates, A is the peak amplitude of the spot, B is the background gray level, (X0,Y0) is the coordinates of the spot center, and σx and σy are the standard deviations in the x and y directions, representing the width of the spot. Subtracting the spot center coordinates obtained at different times gives the change in displacement.

[0029] The measuring device for implementing the above method includes a transmitting device A and a receiving device B;

[0030] The transmitting device A is fixed on one side of the gap being measured. A laser emitting head 2 is installed on the protruding end 1 of the transmitting device A. The laser emitting head 2 is arranged in the X, Y, and Z directions respectively, with at least two emitting heads in each direction. Alternatively, the light path emitted by the laser emitting head 2 is divided into two or more paths to form a symmetrical dual-light knife or multi-light knife.

[0031] The receiving device B is a cubic opaque box fixed on the other side of the slit being measured. The protruding end 1 of the transmitting device A extends into the receiving device B. Two photoelectric devices 3 are arranged on the inner wall of the receiving device B in the X, Y, and Z directions respectively to receive the laser beam signal emitted by the transmitting device A. The X, Y, and Z direction images received by the photoelectric devices 3 are used to obtain the center of gravity data and displacement data of the laser beam using a laser beam centroid algorithm or a data fitting method.

[0032] Compared with the prior art, the advantages of the present invention are:

[0033] (1) This invention utilizes the high coherence and directional stability of laser light, combined with an optical system, to achieve high-precision measurement of cracks. When using a laser, the high energy density of the laser beam and the ability to produce a very small spot size allow for more precise positioning, thus improving measurement accuracy.

[0034] (2) The present invention uses linear CCD or PSD in the optical system design, which can improve the resolution to the micrometer level, thus ensuring high-precision measurement results.

[0035] (3) In image recognition, the present invention uses a spot centroid algorithm or data fitting method to improve the spot center extraction accuracy by an order of magnitude, with an accuracy of more than 0.01 mm, which is of great significance in the detection of micro-cracks.

[0036] (4) By applying the principle of optical knife, the laser beam is modulated into a high-precision linear light source and designed into the shape required for measurement. It can be used in three measurement directions to convert the light generated by the laser source into an optical knife that is projected onto the photoelectric device 3 of the receiving device B to receive the light source signal. The photoelectric device 3 is a large-range linear array CCD or PSD photoelectric receiving element. Through circuit processing, the light source part can be independently adjusted, which is convenient for application. The application of optical knife and large-range linear array photoelectric device can realize large-range measurement to ensure that the received signal does not miss the target.

[0037] (5) The receiving device B of the present invention has two laser beams (from the transmitting device A) and two photoelectric devices 3 (from the receiving device B) arranged in each of the three measurement directions as photoelectric receiving parts. The setting of two photosensitive elements (CCD circuit diagram) can calculate and compensate for the measurement error caused by the rotation of the transmitting device A, thereby improving the accuracy. In addition, by using dual elements, when a certain part has an abnormal failure, the other part can play a backup role, thereby improving the stability of the system.

[0038] (6) The measurement method of the present invention is non-contact, which can avoid backlash error and improve the stability of measurement.

[0039] In summary, this invention, through the application of an optical system, a spot centroid calculation method, and a data fitting method, can measure and monitor the changes in length, width, and depth of cracks. Compared with existing unidirectional and two-dimensional measurement methods, this invention can more comprehensively calculate crack deformation, possessing significant scientific value and broad engineering application prospects. This will not only provide strong technical support for the safety monitoring of large-scale infrastructure but will also promote further development and innovation in the field of engineering measurement technology. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the light source end A of the present invention.

[0041] Figure 2 This is a schematic diagram of the B-end receiver of the present invention.

[0042] Figure 3 This is a schematic diagram of the optical blade of the present invention parallel to three directions, wherein... Figure 3 (a) in the text is parallel to the Z direction. Figure 3 In the diagram, (b) is parallel to the X direction. Figure 3(c) in the equation is parallel to the Y direction.

[0043] Figure 4 This is a schematic diagram of the device structure of the present invention. Detailed Implementation

[0044] The present invention will now be described in detail with reference to the accompanying drawings.

[0045] A high-precision, three-dimensional gap measurement method using laser with a large range includes the following steps:

[0046] Step 1: Construct the measuring device:

[0047] At both ends of the crack in the structure under test, a launching device A is respectively arranged. Figure 1 ) and the corresponding receiving device B ( Figure 2 The laser emission and reception are completed. The transmitting device A and the receiving device B together form the measurement device S, which implements the entire method. Specifically:

[0048] The transmitting device A is fixed to one side of the gap being measured. A laser emitting head 2 is mounted on the protruding end 1 of the transmitting device A. Figure 1 As shown, the beams are arranged in the X, Y, and Z directions, with two transmitters in each direction, or the beam path is split into two to form a symmetrical dual beam knife; the dual beam knife makes each beam knife a pair of parallel lasers, forming the shape required for measurement.

[0049] Receiver B is a cubic, opaque box fixed to the other side of the slit being measured. The protruding end 1 of transmitter A extends into receiver B, serving as a light source. Figure 2 As shown, according to the principle of geometric optics, two photoelectric devices 3 are arranged in each direction inside the receiving device B to receive the light knife signal emitted by the transmitting device A. The X, Y, and Z direction images received by the photoelectric devices 3 serve as the receiving end. Specifically, the light spot centroid data and displacement data are obtained through the light spot centroid algorithm or the data fitting method.

[0050] Step 2: Lateral, longitudinal, and depth displacement measurements:

[0051] A three-dimensional coordinate system is established, using the plane containing the crack as a reference. One coordinate axis is parallel to the expected lateral propagation direction of the crack, another is parallel to the expected longitudinal propagation direction, and the third is perpendicular to the depth direction of the crack surface. The transmitting device A is fixed to one side of the crack being measured, considered as part of that side of the crack, and a designed optical scalpel (such as...) is used. Figure 3As shown, receiver B is fixed on the other side of the gap being measured and is considered as part of the whole on the other side of the gap. Transmitter A emits a laser to receiver B. Receiver B collects the image spot signal and calculates the position coordinates of the center of gravity of the laser beam in three directions in the three-dimensional coordinate system. When the position of the spot changes, the main control circuit in receiver B calculates the change data of the spot position and finally calculates the displacement of the spot in the horizontal, vertical and vertical directions.

[0052] Step 3: Output the measurement results:

[0053] After completing the above steps, the core measurement data of the crack in the transverse, longitudinal, and depth directions can be supplemented with other information, such as measurement time data, to generate crack data for a certain time period for archiving, so that engineering technicians can analyze and archive the measurement results.

[0054] The aforementioned optical blade is an "optical ruler" in laser measurement. It is created by modulating a laser beam into a high-precision linear light source and designing it into the shape required for measurement. Two parallel light rays are used in each of the three measurement directions to form the shape of the optical blade, as shown below. Figure 3 The image shows the 3D display effect of the light knife. In actual measurement, each group of light knives consists of two parallel lasers.

[0055] The pattern of the emitted light blade is as follows Figure 3 In this system, two parallel light scalpels are emitted in each of the three measurement directions. Figure 3 This describes the 3D display effect of the laser beam. The laser head is designed with a dual-beam arrangement, allowing for additional error compensation measurements on top of the basic measurements. When the rotation of the protruding end 1 of the transmitting device A introduces errors, the symmetrical arrangement of the dual laser beams and corresponding photoelectric devices 3 ensures that the rotation of the transmitting end causes one of the laser image data received by the corresponding dual photoelectric devices 3 in the receiving device B to increase while the other decreases. This achieves data compensation and correction, eliminating the influence of the rotation of the protruding end 1 of the transmitting device A on the measurement results.

[0056] Step (2.1), refer to Figure 1 The protruding end 1 of the transmitting device A is equipped with a laser emitting head 2 as a light source in the X, Y, and Z directions. The laser light sources emitted in the X, Y, and Z directions correspond to the X, Y, and Z directions of the inner wall of the receiving device B, or the dual-light knife or multi-light knife divided into two or more paths correspond to the X, Y, and Z directions of the inner wall of the receiving device B.

[0057] Step (2.2): When the gap changes displacement only along the X direction, the transmitting device A fixed on one side changes displacement. After it emits laser, the receiving device B receives the light spot signal at the receiving end, which also changes. Based on the change of the center of gravity of the light spot (the light spot formed by the light knife on the photoelectric device 3 of the receiving device B), the change of the light spot displacement in the X direction can be calculated.

[0058] Step (2.3) and similarly step (2.2) are performed. When the gap only changes displacement along the Y direction, the light spot signal is received at the receiving end, and the change in the light spot displacement in the Y direction can be calculated based on the change in the center of gravity of the light spot.

[0059] Step (2.4) and similarly step 2.2: when the gap only changes displacement along the Z direction, the light spot signal is received at the receiving end, and the change in the light spot displacement in the Z direction can be calculated based on the change in the center of gravity of the light spot.

[0060] Step (2.5): The actual movement of the gap occurs simultaneously in multiple directions. The change in the centroid displacement of the light spot in the three directions calculated at the receiving end according to steps (2.2)-(2.4) is the change in the gap displacement.

[0061] Reference Figure 4 The diagram illustrates the system structure. A photoelectric device 3, which can be a CCD or PSD, is arranged at the receiving end of the receiving device B. When the transmitting device A moves in tandem with the gap, the CCD receiving sections of the receiving device B in the X, Y, and Z directions generate new light beam projection spots, triggering the core circuitry to identify the light spots, calculate changes, and use an algorithm to calculate the displacement changes in the three directions. The data is then reported via the communication module, thus completing the function of this invention.

[0062] The displacement change is obtained using a spot centroid algorithm or a data fitting method. Specifically, the spot centroid algorithm calculates the center position of the spot at a given moment based on a weighted average of pixel grayscale values, as shown in the following formula:

[0063] x_c=ΣΣ(x_ij*I_ij) / ΣΣ(I_ij)

[0064] y_c=ΣΣ(y_ij*I_ij) / ΣΣ(I_ij)

[0065] Where x_c and y_c are the coordinates of the light spot center; I_ij is the gray value of pixel (i,j) after background subtraction, and x_ij and y_ij are the pixel coordinates in the horizontal and vertical directions, respectively; subtracting the light spot center coordinates obtained at different times gives the change in displacement.

[0066] The data fitting method described above is specifically as follows:

[0067] Assuming the light spot intensity distribution conforms to a two-dimensional Gaussian model, a light spot region is selected, and the Levenberg-Marquardt method is used to fit the pixel coordinates and gray values. The center of the light spot is obtained through fitting, as shown in the following formula:

[0068]

[0069] Where I(x,y) represents the light intensity at the selected spot area coordinates, A is the peak amplitude of the spot, B is the background gray level, (X0,y0) is the coordinate of the spot center, and σx and σy are the standard deviations in the x and y directions, representing the width of the spot; subtracting the spot center coordinates obtained at different times gives the displacement change.

Claims

1. A laser-based high-precision three-dimensional seam measurement method with a large range, characterized in that, Includes the following steps: Step 1: At both ends of the crack in the structure to be tested, a transmitting device (A) and a corresponding receiving device (B) are respectively arranged. The transmitting device (A) emits a laser beam signal to the receiving device (B), and the receiving device (B) collects and processes the image spot signal. Step 2: Establish a three-dimensional rectangular coordinate system based on the plane where the crack is located. One coordinate axis is parallel to the expected lateral expansion direction of the crack, another coordinate axis is parallel to the expected longitudinal expansion direction of the crack, and the third coordinate axis is perpendicular to the depth direction of the crack surface. The position coordinates of the centroid of the initial laser beam signal in the three directions in the three-dimensional coordinate system are determined. During measurement, when the change in the position of the beam spot is detected, the main control circuit in the receiving device (B) runs to calculate the change data of the beam spot position, and finally calculates the displacement of the beam spot in the lateral, longitudinal, and vertical directions, that is, the displacement of the crack. Step 3: Combine the displacement of the light spots in the horizontal, vertical and longitudinal directions with the measurement time information to generate crack data for a certain time period and archive it. The transmitting device (A) is fixed on one side of the gap being measured. A laser transmitting head (2) is installed on the protruding end (1) of the transmitting device (A). The laser transmitting head (2) is arranged in the X, Y and Z directions respectively. There are at least two transmitting heads in each direction, or the light path emitted by the laser transmitting head (2) is divided into two or more paths to form a symmetrical double light knife or multiple light knife. The receiving device (B) is a cubic opaque box fixed on the other side of the slit being measured. The protruding end (1) of the transmitting device (A) extends into the receiving device (B). Two photoelectric devices (3) are arranged in the X, Y, and Z directions on the inner wall of the receiving device (B) to receive the laser beam signal emitted by the transmitting device (A). The X, Y, and Z direction images received by the photoelectric devices (3) are used to obtain the center of gravity data and displacement data of the light spot by running the light spot centroid algorithm or data fitting method through the main control circuit in the receiving device B.

2. The laser large-range high-precision three-dimensional seam measurement method according to claim 1, characterized in that, The aforementioned optoelectronic device (3) is a CCD or PSD.

3. The laser large-range high-precision three-dimensional seam measurement method according to claim 1, characterized in that, The laser beam signal emitted by the transmitting device (A) is generated by modulating the laser beam into a linear light source, with at least two transmitting heads in each direction, or by dividing the emission optical path into two or more paths to form a symmetrical dual-beam or multi-beam beam. In the dual-beam beam, each set of beams consists of two parallel lasers, forming the shape required for measurement.

4. The laser large-range high-precision three-dimensional seam measurement method according to claim 3, characterized in that, Error compensation for measurement is achieved by using the symmetrical double light knife: when the rotation of the protruding end (1) of the transmitting device (A) causes an error, by using the symmetrical double light knife and the corresponding photoelectric device (3) arrangement, the rotation of the transmitting end causes the laser image data received by the corresponding double photoelectric device (3) in the receiving device (B) to increase and decrease, thereby realizing data compensation and correction and eliminating the influence of the rotation of the protruding end (1) of the transmitting device (A) on the measurement results.

5. The laser large-range high-precision three-dimensional seam measurement method according to claim 1, characterized in that, The displacement in step 2 is measured in the following specific process: Step (2.1): The protruding end (1) of the transmitting device (A) is equipped with a laser emitting head (2) in the X, Y, and Z directions as the light source end. The laser light sources emitted in the X, Y, and Z directions correspond to the photoelectric devices (3) in the three directions of the inner wall of the receiving device (B), or the dual-light knife or multi-light knife divided into two or more paths correspond to the photoelectric devices (3) in the three directions of the inner wall of the receiving device (B). Step (2.2): When the gap to be measured changes displacement only along the X direction, the transmitting device (A) fixed on one side changes displacement. After it emits laser, the spot signal received by the receiving device (B) at the receiving end also changes. Based on the change of the center of gravity of the spot, the change of the spot displacement in the X direction can be calculated. Step (2.3) and similarly step (2.2) are as follows: when the gap only changes displacement along the Y direction, the light spot signal is received at the receiving end, and the change in the light spot displacement in the Y direction can be calculated based on the change in the center of gravity of the light spot. Step (2.4) and similarly step (2.2) are as follows: after the gap changes displacement only along the Z direction, the light spot signal is received at the receiving end, and the change in the light spot displacement in the Z direction can be calculated based on the change in the center of gravity of the light spot. Step (2.5): The actual movement of the gap occurs simultaneously in multiple directions. The change in the centroid displacement of the light spot in the three directions calculated at the receiving end according to steps (2.2)-(2.4) is the change in the crack displacement.

6. The laser large-range high-precision three-dimensional seam measurement method according to claim 5, characterized in that, The displacement change is obtained using a spot centroid algorithm. Specifically, this algorithm calculates the center position of the spot at a given moment based on a weighted average of pixel grayscale values, using the following formula: x_c = ΣΣ(x_ij * I_ij) / ΣΣ(I_ij) y_c = ΣΣ(y_ij * I_ij) / ΣΣ(I_ij) Where x_c and y_c are the coordinates of the light spot center; I_ij is the gray value of pixel (i,j) after background subtraction, and x_ij and y_ij are the pixel coordinates in the horizontal and vertical directions, respectively; subtracting the light spot center coordinates obtained at different times gives the change in displacement.

7. The laser large-range high-precision three-dimensional seam measurement method according to claim 5, characterized in that, The displacement change was obtained using a data fitting method, which specifically includes: Assuming the light spot intensity distribution conforms to a two-dimensional Gaussian model, a light spot region is selected, and the Levenberg-Marquardt method is used to fit the pixel coordinates and gray values. The center of the light spot is obtained through fitting, as shown in the following formula: Where I(x,y) represents the light intensity at the selected light spot coordinates, A is the peak amplitude of the light spot, and B is the background gray level. X (0, Y0) are the coordinates of the center of the light spot to be found, σ x σ y The standard deviation in the x and y directions represents the width of the light spot; subtracting the coordinates of the light spot center at different times gives the change in displacement.

8. A measuring device for implementing the laser large-range high-precision triaxial seam measurement method according to any one of claims 1-7, characterized in that, The measuring device includes a transmitting device (A) and a receiving device (B); The emitting device (A) is fixed on one side of the gap being measured. The protruding end (1) of the emitting device (A) is equipped with a laser emitting head (2). The laser emitting head (2) is arranged in the X, Y and Z directions respectively. There are at least two emitting heads in each direction, or the light path emitted by the laser emitting head (2) is divided into two or more paths to form a symmetrical double light knife or multi-light knife. The receiving device (B) is a cubic opaque box fixed on the other side of the slit being measured. The protruding end (1) of the transmitting device (A) extends into the receiving device (B). Two photoelectric devices (3) are arranged in the X, Y, and Z directions on the inner wall of the receiving device (B) to receive the laser beam signal emitted by the transmitting device (A). The X, Y, and Z direction images received by the photoelectric devices (3) are used to obtain the center of gravity data and displacement data of the spot using the spot centroid algorithm or the data fitting method.

Images