A rectangular wide spot shaping imaging system and centroid positioning method

Abstract

The present invention relates to the field of laser ranging technology, and in particular to a rectangular wide spot shaping imaging system and a centroid positioning method, comprising a laser diode light source, a Powell prism, a cylindrical lens, an aperture diaphragm arranged in sequence along an incident light path, and a filter, a receiving lens group and an image acquisition unit arranged in sequence along a reflected light path, wherein: the cylindrical lens comprises two industrial-grade cylindrical lenses, which are orthogonally installed in the incident light path in sequence, the cylindrical lens in the X direction is used to collimate the X-direction laser, and the cylindrical lens in the Y direction is used to compress the linear laser generated by the Powell prism, thereby generating a rectangular collimated light spot; the receiving lens group is a three-piece lens, which is placed according to the Schaber condition, and the parameters are obtained according to the optimization of the optical path structure. The beneficial effect of the present invention is that the rectangular wide spot shaping imaging system provided realizes the measurement of the pothole surface by the sensor, and provides a fast and effective wide spot center extraction algorithm, which improves the measurement speed and accuracy of the sensor.

Description

Technical Field

[0001] The invention relates to the technical field of laser ranging, and in particular to a rectangular wide spot shaping imaging system and a centroid positioning method. Background Art

[0002] Precision displacement measurement is an important part of the measurement field. With the continuous development of science and technology and industrial manufacturing, various high-tech technologies such as intelligent driving and remote sensing detection have put forward higher and higher requirements for precision displacement measurement. Laser displacement sensors based on laser triangulation have been widely used in different fields due to their significant advantages such as low cost, non-contact and high precision, and have become the main equipment for modern measurement.

[0003] Laser displacement sensor is a high-precision distance measurement sensor based on the principle of triangulation imaging. In practical applications, for objects with irregular surfaces, too small an output spot will change the propagation direction of the light, resulting in multiple scattering, which greatly limits the accuracy and stability of the laser displacement sensor. This problem can be effectively solved by increasing the size of the spot. However, the uniformity of the spot will decrease as the spot size increases, and existing methods rarely take both into account at the same time. In order to enable the sensor to measure the pothole surface and ensure the measurement accuracy, it is urgent to study a method to achieve a large-size uniform spot to expand the practical range of the sensor.

[0004] The algorithm for locating the centroid of the light spot on the imaging device will also greatly affect the measurement speed and accuracy of the sensor. The position of the main light spot for calculating the intensity of the light spot is usually calculated based on the amplitude of each pixel of the CCD, mainly including the grayscale centroid method and the Gaussian fitting method. The principles of the two methods are based on the premise that the image point light spot is Gaussian, but according to the geometric imaging law of the laser triangulation method, the image point light spot has a certain degree of deviation and becomes elliptical. Due to the different surface characteristics of the object being measured, there is a speckle effect or a modulation effect on the surface of the object being measured. Once these signals are used as valid data in the calculation of Gaussian function fitting, large errors will be generated. Therefore, it is necessary to propose a fast and effective light spot center extraction algorithm for the designed rectangular wide spot image to improve the measurement speed and accuracy of the sensor.

[0005] Therefore, technicians in this field are committed to developing a wide spot shaping imaging system to enable the sensor to measure the pothole surface, and provide a fast and effective wide spot center extraction algorithm to improve the measurement speed and accuracy of the sensor. Summary of the invention

[0006] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is that the existing laser displacement sensor has low adaptability to pothole-prone surfaces and the accuracy of the spot centroid positioning algorithm of the wide spot system is low.

[0007] To achieve the above-mentioned purpose, the present invention provides a rectangular wide spot shaping imaging system for realizing laser light source shaping, comprising a laser diode light source, a Powell prism, a cylindrical lens, and an aperture stop arranged in sequence along an incident light path, and a filter, a receiving lens group, and an image acquisition unit arranged in sequence along a reflected light path, wherein:

[0008] The cylindrical lens comprises two industrial-grade cylindrical lenses, which are orthogonally installed in the incident light path in sequence. The cylindrical lens in the X direction is used to collimate the X-direction laser, and the cylindrical lens in the Y direction is used to compress the linear laser generated by the Powell prism, thereby generating a rectangular collimated light spot.

[0009] The receiving lens group is a three-piece lens, which is placed to meet the Schaffner condition, and the parameters are obtained according to the optimization of the optical path structure, and is used to clearly image the light spot on the surface of the object to be measured onto the image acquisition unit.

[0010] Preferably, the laser diode light source is an industrial-grade laser diode, with a half divergence angle of 4.5° in the X direction, a half divergence angle of 14° in the Y direction, and an emitted light beam wavelength of 650nm.

[0011] Preferably, the Powell prism is an optical scribing prism, which uniformizes the Gaussian distributed laser beam into a straight line with good stability.

[0012] Preferably, the aperture stop is circular and is used to filter out peripheral stray light after shaping.

[0013] Preferably, the filter is a narrow-band optical filter with a central wavelength of 650 nm.

[0014] Preferably, the image acquisition unit is a high-performance imaging unit including but not limited to CCD and CMOS, which is used to acquire the position of the image point and transmit the data to the control device for processing to achieve precise positioning.

[0015] The present invention also provides a method for locating the centroid of a rectangular wide spot shaping imaging system, the method comprising the following steps:

[0016] Step 1) reading the wide spot amplitude data collected by the image acquisition unit to obtain the distribution I(x) of the wide spot on the receiving element, and using a local weighted smoothing method to filter the spot amplitude on the receiving element to remove gross errors of the waveform data;

[0017] Step 2) Taking the pixel position corresponding to the maximum amplitude of the wide spot as the starting point, take the points on the left and right sides of the starting point in turn and make tangents to the wide spot amplitude distribution waveform respectively, record the intersection position of each group of tangents, the distribution of the intersection points is close to a straight line, reflecting the skewness trend of the spot imaging process, and the arithmetic average result of the intersection point cluster is the actual wide spot centroid position.

[0018] Preferably, step 1 comprises the following steps:

[0019] The distribution I(x) is plotted as a light spot amplitude distribution diagram, wherein the horizontal axis is the pixel position of each point of the light spot on the receiving element, and the vertical axis is the light intensity amplitude of the light spot;

[0020] Perform local weighted sliding filtering on each pixel on the waveform, take a certain proportion of local data for calculation, and the sliding window size Size is related to the effective waveform width and is in a certain proportion P;

[0021] The Gaussian function is used as the weight function of the local weighted sliding filter. The distance between each pixel point and the center point in the sliding window is used to calculate the weight of the point through the Gaussian function, as shown in the following formula:

[0022]

[0023] Among them, d represents the distance between each pixel in the sliding window and the center point, and its range is σ represents the variance of pixel coordinate distribution, which is related to the sliding window size Size and becomes a fixed value according to the window size;

[0024] After the weights G(d) of all points in the window are obtained, the weights are normalized to obtain G′(d). The filtered spot amplitude I′(x) is calculated by weighted average, as shown in the following formula:

[0025]

[0026] Preferably, the sliding window size Size=0.125*width, where width represents the effective waveform width of the spot distribution, that is, the number of pixels between the start and end points of the waveform greater than half the amplitude, and the sliding window size Size is an integer, and an odd number is preferred;

[0027] Preferably, step 2 comprises: first, determining the pixel position where the tip of the light intensity amplitude of the light spot is located, as the starting point x0 of the centroid algorithm, taking the vertical line where the position is located as the rough symmetry axis of the light spot waveform distribution, and the remaining pixel points are arranged symmetrically on the left and right; second, starting from the starting point, taking two points symmetrically on the left and right, recorded as (x -2 ,y -2 ), (x -1 ,y -1 ), (x1, y1), (x2, y2) are drawn through two adjacent points and regarded as the tangent of the spot amplitude distribution waveform. The right tangent of the first set of symmetrical points is expressed as:

[0028]

[0029] The left tangent line of the first set of symmetric points is expressed as:

[0030]

[0031] The left and right tangents point to the axis of symmetry and intersect at one point. Record the position of the intersection point p1:

[0032]

[0033] Repeat the above steps and take (x -n ,y -n ), (x n ,y n ) until the slope of the tangent is 0, and the intersection point set of each group of tangents is obtained P = {p i |i=1,2,…,n}.

[0034] The beneficial effects of the present invention are:

[0035] 1. The collimated light beam of the present invention outputs a long rectangular light spot, and the light spot intensity is approximately uniformly distributed within the rectangular range. The short side length of the rectangular light spot is similar to the diameter of an ordinary Gaussian beam, which is used for precise positioning. The long side direction is parallel to the image acquisition unit, which is used to suppress multiple irregular scattering caused by the uneven surface of the object to be measured;

[0036] 2. The fast and effective wide spot center extraction algorithm provided by the present invention has a simple structure, can quickly extract the spot centroid position, and effectively filter out the influence of noise, has extremely high surface adaptability, and improves the measurement speed and accuracy of the sensor.

[0037] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the composition of a rectangular wide spot shaping imaging system of a laser displacement sensor in a preferred embodiment of the present invention;

[0039] Figure 2 It is a side view of a rectangular wide spot shaping imaging system of a laser displacement sensor in a preferred embodiment of the present invention;

[0040] Figure 3 is a schematic diagram of a collimated optical path based on ZEMAX simulation in a preferred embodiment of the present invention;

[0041] Figure 4 It is a rectangular spot pattern obtained on the surface of the object to be measured in a preferred embodiment of the present invention;

[0042] Figure 5is a cross-sectional view of a rectangular spot pattern obtained on the surface of the object to be measured in a preferred embodiment of the present invention;

[0043] Figure 6 It is a rectangular light spot imaging diagram obtained on the image acquisition unit in a preferred embodiment of the present invention;

[0044] Figure 7 In a preferred embodiment of the present invention, different light spot imaging images are obtained by the image acquisition unit as the position of the surface of the object to be measured changes;

[0045] Figure 8 is a waveform distribution diagram of the light spot on the receiving element in a preferred embodiment of the present invention;

[0046] Fig. 9 It is a distribution diagram of light spot waveform after local weighted filtering based on Gaussian weight in a preferred embodiment of the present invention;

[0047] Fig.10 is a flow chart of an algorithm for wide spot positioning proposed in a preferred embodiment of the present invention;

[0048] Fig.11 is a distribution diagram of the intersection point results in the spot centroid positioning algorithm in a preferred embodiment of the present invention;

[0049] In the figure, 1. laser diode light source, 2. Powell prism, 3. cylindrical lens, 4. aperture stop, 5. filter, 6. receiving lens group, 7. image acquisition unit, 8. object surface to be measured. DETAILED DESCRIPTION

[0050] The following describes several preferred embodiments of the present invention with reference to the drawings in the specification, so that the technical content is clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the protection scope of the present invention is not limited to the embodiments mentioned in the text.

[0051] In the drawings, components with the same structure are indicated by the same numerical reference numerals, and components with similar structures or functions are indicated by similar numerical reference numerals. The size and thickness of each component shown in the drawings are arbitrarily shown, and the present invention does not limit the size and thickness of each component. In order to make the illustration clearer, the thickness of the components is appropriately exaggerated in some places in the drawings.

[0052] like Figure 1 and Figure 2As shown, a preferred embodiment of the present invention provides a rectangular wide spot shaping imaging system for realizing laser light source shaping in a laser displacement sensor, comprising a laser diode light source 1, a Powell prism 2, a cylindrical lens 3, and an aperture diaphragm 4 arranged in sequence along an incident light path, and a filter 5, a receiving lens group 6 and an image acquisition unit 7 arranged in sequence along a reflected light path. The light emitted from the laser diode light source 1 reaches a surface of an object to be measured 8 after passing through the Powell prism 2, the cylindrical lens 3, and the aperture diaphragm 4, and the reflected light reaches the image acquisition unit 7 along the filter 5 and the receiving lens group 6.

[0053] The laser diode light source 1 is an industrial-grade diode light source, with a half divergence angle of 4.5° in the X direction and a half divergence angle of 14° in the Y direction, and an emitted light beam with a wavelength of 650 nm, and is a low-cost light source.

[0054] The Powell prism 2 is an optical scribing prism, which can make the Gaussian-distributed laser beam uniformly formed into a straight line with good stability.

[0055] The cylindrical lenses 3 are industrial-grade cylindrical lenses, and there are two of them, which are orthogonally installed in the optical path. The cylindrical lens in the X direction is used to collimate the X-direction laser, and the cylindrical lens in the Y direction is used to compress the linear laser generated by the Powell prism, thereby generating a rectangular collimated light spot.

[0056] The emitting laser used by the conventional laser displacement sensor is a circular Gaussian spot with a diameter of several tens of microns, while the rectangular wide spot shaping imaging system for realizing laser light source shaping described in the present invention outputs a long rectangular spot. The short side length of the rectangular spot is similar to the diameter of an ordinary Gaussian beam, which is used for precise positioning. The long side direction is parallel to the image acquisition unit 7, and when imaging on the image acquisition unit 7, it has an effect similar to averaging, thereby suppressing the multiple irregular scattering caused by the uneven surface of the object 8 to be measured.

[0057] The lens parameters of the cylindrical lens 3 are obtained by a combined operation of an orthogonal descent method and a damped least squares method. The algorithm is a conventional algorithm in the prior art and will not be described in detail here.

[0058] The laser diode 1 and the cylindrical lens 3 are both small in size, and the cylindrical lens 3 is smaller than 10 mm, which greatly reduces the installation volume, thereby reducing the overall size of the rectangular wide spot shaping imaging system.

[0059] The aperture stop 4 is a circular aperture stop, which is used to filter out peripheral stray light after shaping and improve the quality of light beam shaping.

[0060] The filter 5 is a narrow-band optical filter, the central wavelength of which is also 650 nm, and is used to filter out stray light and improve imaging quality and measurement accuracy.

[0061] The receiving lens group 6 is a three-piece lens, the parameters of which are optimized according to the optical path structure, and is used to clearly image the light spot on the surface of the object to be measured onto the image acquisition unit, and its placement meets the Schaffner condition.

[0062] The image acquisition unit 7 is a high-performance imaging unit, such as CCD, CMOS, etc., which is used to acquire the position of the image point and transmit the data to the control device for processing to achieve precise positioning. The control device includes but is not limited to FPGA.

[0063] The object surface 8 to be measured is a surface to be measured for distance, and the surface may have concave and convex areas, which may affect the measurement of ordinary laser displacement sensors.

[0064] For the object surface 8 to be measured at different positions within the measuring range, the rectangular wide light spot can show excellent adaptability and imaging accuracy, thereby ensuring the imaging stability of the rectangular wide light spot shaping imaging system within the measuring range.

[0065] In a preferred embodiment of the present invention, the divergent light beam generated by the laser diode light source 1 enters the Powell prism 2, and its Y-direction light beam is shaped into a divergent line laser, and the X-direction light beam does not change; the divergent light beam in the Y direction is compressed by the cylindrical lens in that direction, and its line length is compressed to the required value; the X-direction light beam is collimated by the cylindrical lens in another direction, and the X-direction spot diameter becomes 50μm, and a uniform rectangular spot with an RMS size of 50μm*600μm is obtained; the overall structure of the collimation system is a schematic diagram of the collimation light path based on ZEMAX simulation as shown in Figure 3 As shown, the spot image obtained on the object surface 8 is as follows: Figure 4 As shown, it is a rectangular spot with uniform intensity distribution. The cross-sectional waveforms in the X and Y directions are shown in Figure 5 As shown, it is approximately flat-topped.

[0066] The rectangular light spot can cover the small concave and convex areas on the surface of the object to be measured 8, and suppress the multiple reflection phenomenon in the pothole area; the collimated light hits the object to be measured 8 and causes diffuse reflection. After a part of the scattered light passes through the filter 5 and the receiving lens group 6, it is collected by the receiving lens group 6, and the image of the rectangular light spot is obtained on the image acquisition unit 7. When the object to be measured 8 is at zero position, the corresponding image obtained on the image acquisition unit 7 is as shown in FIG. Figure 6 As shown, as the position of the object surface 8 to be measured changes, the position of the light spot on the corresponding image acquisition unit 7 will also change accordingly. Figure 7The figure shows the spot pattern obtained on the corresponding image acquisition unit 7 when the surface of the object to be measured undergoes a certain displacement along the direction of the incident light beam. The 5 sub-figures in the figure respectively show the spot patterns obtained by the image acquisition unit 7 when the surface of the object to be measured is at the positions of z=0mm, z=-1mm, z=-2mm, z=1mm, and z=2mm. The spot imaging is received by the image acquisition unit 7 and then transmitted to a processing device such as FPGA. The processing device obtains the precise positioning center position based on the center positioning algorithm, and calculates the actual displacement of the corresponding surface of the object to be measured 8 according to the optical imaging relationship, thereby realizing precise displacement measurement.

[0067] like Fig.10 As shown, a method for locating the centroid of a rectangular wide spot shaping imaging system for realizing laser light source shaping provided by the present invention is provided.

[0068] The Gaussian weight function is used to perform local weighted filtering on the one-dimensional spot data, and the spot waveform distribution is fully utilized to locate the spot centroid. The waveform data on the left and right sides of the tip of the light intensity waveform are read in turn, and the tangents of each point on both sides of the waveform are calculated. Each group of tangents has an intersection point. The intersection points that meet the threshold interval are arithmetic averaged, and the result is regarded as the spot centroid position.

[0069] A preferred embodiment of the present invention is:

[0070] Taking the measurement of the measured object scene at 5mm as an example, read the spot amplitude data to obtain the distribution I(x) of the spot on the receiving element, and draw a spot amplitude distribution diagram, where the horizontal axis is the pixel position of each point of the spot on the receiving element, and the vertical axis is the light intensity amplitude of the spot, see Figure 8 .

[0071] For each pixel on the waveform, local weighted sliding filtering is performed, and a certain proportion of local data is taken for calculation. The sliding window size Size is not a fixed value. It is related to the effective waveform width and is in a certain proportion P, as shown in the following formula:

[0072] Size=0.125*width

[0073] In this example, the waveform width width is 35 pixels. Usually, Size is rounded to an integer, and an odd number is preferred, Size = 0.125*35 = 4.375. According to the filtering requirement, an odd number is rounded, so the sliding window size is set to 5 pixels.

[0074] The Gaussian function is used as the weight function of the local weighted sliding filter, and the distance from the center pixel of the sliding window is used to calculate the weight of the point through the Gaussian function, as shown in the following formula:

[0075]

[0076] Where d represents the displacement of each pixel point in the sliding window from the center point, and its range is [-2, 2]; σ represents the standard deviation of the pixel coordinate distribution, which is related to the sliding window size and becomes a constant according to the window size. The sliding window of 9 pixels corresponds to σ = 1.58.

[0077] The distribution of weights is high in the middle and low around, and the farther away from the center, the smaller the influence on the center point and the smaller the weight. After the weight G(x) of all points in the window is calculated, the weight is normalized to obtain G′(x). The weights at each position in the window are 0.07, 0.24, 0.36, 0.24, and 0.07 respectively.

[0078] The filtered spot amplitude I′(x) is calculated by weighted averaging, as shown in the following formula:

[0079]

[0080] The spot waveform after local weighted filtering is smoother. On the basis of retaining the basic shape of the 8 spots on the measured surface, the random errors caused by particles are eliminated. Fig. 9 , which will be used for subsequent centroid positioning.

[0081] Determine the pixel position where the tip of the light intensity amplitude waveform of the light spot is located as the starting point x0 of the centroid algorithm. In this example, x0=144. The vertical line at this position is used as the rough symmetry axis of the light spot waveform distribution, and the remaining pixel points are arranged symmetrically on its left and right.

[0082] Starting from the starting point, take two points symmetrically on each side. The first group is recorded as (142,430.8), (143,427.3), (145,426.3), (146,427.9). Draw straight lines through two adjacent points, which are regarded as tangents of the spot amplitude distribution waveform:

[0083]

[0084] The left and right tangents point to the axis of symmetry and intersect at one point. Record the position of the intersection point p1. Repeat the above steps and take (x -n ,y -n ), (x n ,y n ) until the slope of the tangent line is 0, and the set of intersection points P = {p i |i=1,2,…,n}.

[0085] In this example, the pixel positions of the intersections are 144.84, 145.02, 145.05, 145.30, 145.29, 145.28, 145.46, 145.55, 144.92, 145.33, 145.12, 144.66, 145.25, etc., and their distribution is as follows: Fig.11 , after arithmetic average calculation, the energy center of the light spot is finally at the position x=144.474.

[0086] The light spot centroid positioning algorithm proposed in the present invention restores the change of light intensity at each point through the tangent method, and finally traces the modulation relationship by summarizing the position information of the intersection points to obtain the precise position of the light spot centroid within the pixel. The light spot extraction algorithm has a simple structure, can quickly extract the light spot centroid position, and effectively filter out the influence of noise, and has extremely high surface adaptability.

[0087] By using the above algorithm to locate the centroid of the light spot, the waveform data can be fully utilized to restore the corresponding light spot energy center according to its amplitude distribution characteristics.

[0088] The preferred specific embodiments of the present invention are described in detail above. It should be understood that ordinary technicians in the field can make many modifications and changes based on the concept of the present invention without creative work. Therefore, all technical solutions that can be obtained by technicians in the technical field based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for locating the centroid of a rectangular wide spot shaping imaging system, using a rectangular wide spot shaping imaging system, characterized in that: The system comprises a laser diode light source, a Powell prism, a cylindrical lens, and an aperture stop which are sequentially arranged along an incident light path, and a filter, a receiving lens group, and an image acquisition unit which are sequentially arranged along a reflected light path, wherein: The cylindrical lens comprises two industrial-grade cylindrical lenses, which are orthogonally installed in the incident light path in sequence. The cylindrical lens in the X direction is used to collimate the X-direction laser, and the cylindrical lens in the Y direction is used to compress the linear laser generated by the Powell prism, thereby generating a rectangular collimated light spot. The receiving lens group is a three-piece lens, which is placed to meet the Schaber condition, and the parameters are obtained according to the optimization of the optical path structure, and is used to clearly image the light spot on the surface of the object to be measured onto the image acquisition unit; The method for locating the centroid of the rectangular wide spot shaping imaging system comprises the following steps: Step 1, read the wide spot amplitude data collected by the image acquisition unit to obtain the distribution I(x) of the wide spot on the receiving element, and use the local weighted sliding filtering method with Gaussian function to calculate the weight to filter the spot amplitude on the receiving element. When filtering, set a sliding window, first use the Gaussian function to calculate the weight function, then normalize the weights of all points calculated in the window, and finally use the weighted average method to calculate the filtered spot amplitude I′(x) to eliminate the gross error of the waveform data; Step 2: Taking the pixel position corresponding to the maximum amplitude of the wide spot as the starting point, take the points on the left and right sides of the starting point in turn and make tangents to the wide spot amplitude distribution waveform respectively until the slope of the tangent is 0, and record the intersection position of each group of tangents. The distribution of the intersection points is close to a straight line, which reflects the skewness trend of the spot imaging process. The arithmetic average result of the intersection cluster is the actual centroid position of the wide spot.

2. The centroid positioning method of the rectangular wide spot shaping imaging system according to claim 1, characterized in that: The laser diode light source is an industrial-grade laser diode, with a half divergence angle of 4.5° in the X direction, a half divergence angle of 14° in the Y direction, and an emission light beam wavelength of 650nm.

3. The centroid positioning method of the rectangular wide spot shaping imaging system according to claim 1, characterized in that: The Powell prism is an optical scribing prism that evens out a Gaussian-distributed laser beam into a straight line with good stability.

4. The method for locating the centroid of a rectangular wide spot shaping imaging system according to claim 1, characterized in that: The aperture stop is circular and is used to filter out peripheral stray light after shaping.

5. The method for locating the centroid of a rectangular wide spot shaping imaging system according to claim 1, characterized in that: The filter is a narrow-band optical filter with a central wavelength of 650nm.

6. The method for locating the centroid of a rectangular wide spot shaping imaging system according to claim 1, characterized in that: The image acquisition unit includes but is not limited to a CCD or CMOS high-performance imaging unit, which is used to acquire the position of image points and transmit the data to a control device for processing to achieve precise positioning.

7. The method for locating the centroid of a rectangular wide spot shaping imaging system according to claim 1, characterized in that: The step 1 comprises the following steps: The distribution I(x) is plotted as a light spot amplitude distribution diagram, wherein the horizontal axis is the pixel position of each point of the light spot on the receiving element, and the vertical axis is the light intensity amplitude of the light spot; Perform local weighted sliding filtering on each pixel on the waveform, take a certain proportion of local data for calculation, and the sliding window size Size is related to the effective waveform width and is in a certain proportion P; The Gaussian function is used as the weight function of the local weighted sliding filter, and the distance from the center pixel of the sliding window is used to calculate the weight of the point through the Gaussian function, as shown in the following formula: Among them, d represents the distance between each pixel in the sliding window and the center point, and its range is σ represents the variance of pixel coordinate distribution, which is related to the sliding window size Size and becomes a fixed value according to the window size; After the weights G(d) of all points in the window are obtained, the weights are normalized to obtain G′(d). The filtered spot amplitude I′(x) is calculated by weighted average, as shown in the following formula:

8. The method for locating the centroid of a rectangular wide spot shaping imaging system according to claim 7, characterized in that: The sliding window size Size is as follows: Size=0.125*width Wherein, width represents the effective waveform width of the spot distribution, that is, the number of pixels between the start and end points of the waveform greater than half of the amplitude, and the sliding window size Size is an integer, and odd numbers are preferred.

9. The method for locating the centroid of a rectangular wide spot shaping imaging system according to claim 1, characterized in that: The step 2 comprises: Determine the pixel position where the tip of the light intensity amplitude of the light spot is located, and use it as the starting point x0 of the centroid algorithm. Use the vertical line at this position as the rough symmetry axis of the light spot waveform distribution, and the remaining pixels are arranged symmetrically on its left and right. Starting from the starting point, take two points symmetrically on each side and record them as (x -2 ,y -2 ),(x -1 ,y -1 ), (x1, y1), (x2, y2) draw a straight line through two adjacent points, which is regarded as the tangent line of the spot amplitude distribution waveform: The right tangent line of the first set of symmetric points is expressed as: The left tangent line of the first set of symmetric points is expressed as: The left and right tangents point to the axis of symmetry and intersect at one point. Record the position of the intersection point p1: Repeat the above steps and take (x -n ,y -n ),(x n ,y n ) until the slope of the tangent is 0, and the intersection point set of each group of tangents is obtained P = {p i |i=1,2,…,n}.

Images