Local light-transmitting elements, methods and devices for calculating the center of light spots, and methods and systems for calculating light pressure arms.

Abstract

The application belongs to the technical field of image processing and optical analysis, and particularly relates to a local light-transmitting element, a light spot center calculation method and device, and a light pressure arm calculation method and device. The light spot center calculation method and the light pressure arm calculation method disclosed in the application calculate the light spot center by projecting light to a first image collected after a local light-transmitting element with 2N light-transmitting slits arranged in a radial direction is collected. The center of the local light-transmitting element is designed to coincide with the center of a pattern formed by the light-transmitting slits, and the center of the local light-transmitting element can also be calculated by a slit light spot formed by the light-transmitting slits. The light spot center and the local light-transmitting element center are simultaneously calculated from one image, and the center of the laser light spot and the center of the local light-transmitting element can be further tracked in real time to adjust the laser emission parameters, so that the laser can accurately hit the target center, thereby providing technical support for laser alignment, laser tracking and other applications.

Description

Technical Field

[0001] This application belongs to the field of image processing and optical analysis technology, specifically relating to a local light-transmitting element, a method and device for calculating the center of a light spot, and a method and system for calculating an optical pressure arm. Background Technology

[0002] In the mid-19th century, Maxwell theoretically predicted the existence of light pressure. In the early 20th century, Lebedev first experimentally measured the value of light pressure, sparking the scientific concept of light pressure-driven space travel. In 2010, the Japan Aerospace Exploration Agency (JAXA) successfully launched the IKAROS laser sail into space and successfully completed various experiments, further stimulating research enthusiasm for laser sail spacecraft. In 2016, Hawking proposed the "Breakthrough Starshot" project, aiming to use the enormous light pressure generated by a ground-based laser array to accelerate a laser sail to 20% of the speed of light for interstellar travel, targeting the vast universe to explore extraterrestrial civilizations, search for habitable planets, and find scarce metal resources on Earth. In 2019, a research team at Rensselaer Polytechnic Institute in the United States designed a prototype of such a laser sail.

[0003] In contrast, my country is still in the initial stage of overall design for thin-film structure spacecraft such as laser sails, which are designed for deep space exploration. Key technologies require sufficient guidance and support from theoretical analysis, numerical calculations, and physical or semi-physical simulation experiments. In the process of accelerating a laser sail using optical pressure, the center of the laser needs to be perfectly aligned with the center of the laser sail to obtain maximum optical pressure. This requires precise measurement of the optical pressure arm, with a measurement error of less than 50 μm. Currently, there is limited research on the measurement of the optical pressure arm, mainly focusing on:

[0004] 1. In December 2019, Grover Swartzlander of the Institute of Optics at the Rochester Institute of Technology in New York developed a laser sail consisting of two diffraction gratings placed side by side. Each grating is composed of neatly arranged liquid crystals that deflect light at a specific angle, generating a thrust that moves the sail backward and sideways. The grating on the left side of the laser sail can deflect the beam to the right of the laser beam, and vice versa. If the position of the laser sail shifts, the laser beam, after falling on either side of the sail, will push the sail back to its original position, causing the laser to fall back to the center of the sail. Through experimental testing, sufficient positioning and methods to avoid interference were found, successfully detecting the thrust generated by the laser sail that returns it to the center of the laser beam, aligning it with the laser beam. This research result is crucial for ensuring that the laser beam consistently illuminates the laser sail stably. This scheme essentially uses hardware structure to avoid measuring the optical pressure arm.

[0005] 2. In Lebedev's optical pressure measurement experiment, the laser directly irradiated one end of the torsion balance's small wing. When calculating the optical pressure, the lever arm of the torsion balance was directly used as the optical pressure arm for calculation, without considering whether the laser center was aligned with the center of the small wing, and therefore the measurement of the optical pressure arm was not considered.

[0006] Therefore, it is essential to invent a high-precision method for calculating optical pressure arms. Summary of the Invention

[0007] This application provides a method and apparatus for calculating the center of a light spot, which can solve the technical problem that it is difficult to calculate the center of a light spot when incident light needs to be reflected to generate light pressure.

[0008] This application also provides a method and system for calculating optical pressure arm, which can solve the technical problem that it is difficult to calculate the optical pressure arm when incident light needs to be reflected to generate optical pressure.

[0009] This application also provides a partially transparent element, which can be used as a target for light pressure to solve the technical problem of not being able to calculate the light pressure arm.

[0010] On the one hand, embodiments of this application provide a method for calculating the center of a light spot, including the following steps.

[0011] The first image is acquired after the emitted light shines on a local light-transmitting element with 2N radially and uniformly arranged light-transmitting slits.

[0012] By fitting the slit light spots formed by each light-transmitting slit in the first image to a first line segment, a second image with 2N first line segments is obtained.

[0013] The first line segments with the same slope on the second image are fitted into a first curve with the distance from each point on the first line segment to a specific point as the x-axis value and the gray level value of each point on the first line segment as the y-axis value.

[0014] Multiple sampling points are obtained by sampling the first curve. If the gray value of a point in the second image corresponding to the multiple sampling points is zero, the ordinate value of the corresponding sampling point is assigned to the corresponding point in the second image with a gray value of zero, thus obtaining a third image with N second line segments.

[0015] Surface fitting is performed on points with non-zero gray values ​​in the third image.

[0016] Calculate the center point O1 of the fitted surface.

[0017] This center point is the center of the light spot.

[0018] According to an embodiment of the first aspect of this application, the proximal endpoints of the 2N light-transmitting slits are concyclic.

[0019] and / or

[0020] The distal endpoints of 2N light-transmitting slits are concyclic.

[0021] According to any of the foregoing embodiments of the first aspect of this application, before the step of "fitting the slit light spots formed by each light-transmitting slit on the first image into a first line segment to obtain a second image with an even number of first line segments", the following step is further included:

[0022] Denoise and / or smooth the first image to obtain a new first image.

[0023] According to any of the foregoing embodiments of the first aspect of this application, the step "fitting the first line segments with the same slope on the second image into a first curve with the distance from each point on the first line segment to a specific point as the abscissa and the grayscale value of each point on the first line segment as the ordinate" includes

[0024] Group the first line segments with the same slope among the 2N first line segments on the second image into one group.

[0025] The origin is defined as the leftmost non-zero gray value point of each group of the first line segment. The distances from the origin to the remaining points on each group of the first line segment are used as the x-axis values. The gray value of each point on the second image corresponding to each point on each group of the first line segment is used as the y-axis value.

[0026] The nonlinear least squares method is used to perform quadratic curve fitting on each group of first line segments to obtain N first curves.

[0027] According to any of the foregoing embodiments of the first aspect of this application, the step "sampling the first curve to obtain multiple sampling points, and if the gray value of a point in the second image corresponding to the multiple sampling points is zero, then assigning the ordinate value of the corresponding sampling point to the point in the second image with the corresponding gray value of zero to obtain the third image" includes...

[0028] M data points are obtained by sampling every m data points on the first curve.

[0029] Search for the gray value at point P in the second image corresponding to each data point one by one.

[0030] If the gray value of point P in the second image is zero, then the ordinate value of the data point corresponding to point P is assigned to point P as the gray value of point P, thus obtaining the third image.

[0031] According to any of the foregoing embodiments of the first aspect of this application, after the step of "calculating the center point of the fitted surface", a further step is included.

[0032] Take one point on each of the second line segments, where the grayscale gradient value is the same at each point, and find the center O2 of the circle containing each point.

[0033] The new center point is obtained by averaging the coordinates of the center point O1 and the circle center O2.

[0034] According to any of the foregoing embodiments of the first aspect of this application, after the step of "calculating the center point of the fitted surface", a further step is included.

[0035] Take H points on each of the second line segments to form H circles with equal grayscale gradient values. Calculate the average of the center coordinates of each circle to obtain the center O2.

[0036] The new center point is obtained by averaging the coordinates of the center point O1 and the circle center O2.

[0037] According to any of the foregoing embodiments of the first aspect of this application, the step "taking H points on each of the second line segments to form H circles with equal grayscale gradient values, and calculating the average coordinates of the center of each circle to obtain the center O2" includes

[0038] Select a second line segment,

[0039] Calculate the grayscale gradient values ​​at each point on the selected second line segment.

[0040] Select H points with different grayscale gradient values.

[0041] On each of the remaining second line segments, search for H points that have the same gray-level gradient values ​​as the selected H different gray-level gradient values.

[0042] Connect the points with the same gray-level gradient value on each of the second line segments to form H circles with equal gray-level gradient values.

[0043] Find the average of the center coordinates of the H circles to obtain the center O2.

[0044] Secondly, embodiments of this application provide a method for calculating an optical pressure arm, which calculates the center of the optical spot using the aforementioned method for calculating the center of the optical spot, wherein...

[0045] The center of the locally light-transmitting element coincides with the center of the pattern formed by the 2N light-transmitting slits.

[0046] The optical pressure arm calculation method provided in this application embodiment further includes steps.

[0047] The center of the local light-transmitting element is calculated using either the first or second image.

[0048] Calculate the distance between the center of the local light-transmitting element and the center of the light spot.

[0049] The optical pressure arm is calculated based on the conversion relationship between the pixels in the third image and the actual physical size.

[0050] According to the foregoing embodiments of the second aspect of this application, the step of "calculating the center of the local light-transmitting element through the first image or the second image" includes...

[0051] Take the proximal endpoints of each of the first line segments on the second image.

[0052] Fitting to 2N proximal endpoints,

[0053] Find the center of the fitted curve, which is the center of the local light-transmitting element.

[0054] According to any of the foregoing embodiments of the second aspect of this application, the proximal endpoints of the light-transmitting slits are concyclic, and the local light-transmitting element further has a circular light-transmitting slit connecting the proximal ends of the light-transmitting slits.

[0055] The step "Calculate the center of the local light-transmitting element using the first or second image" includes...

[0056] The circular slit light spot formed by the light passing through the circular slit in the first image is fitted into a circle.

[0057] Find the center of the circle; this center is the center of the local light-transmitting element.

[0058] According to any of the foregoing embodiments of the second aspect of this application, the proximal endpoints of the light-transmitting slits are concyclic, and the local light-transmitting element further has a circular light-transmitting slit connecting the proximal ends of the light-transmitting slits.

[0059] The step "Calculate the center of the local light-transmitting element using the first or second image" includes...

[0060] Detect the circular slit light spot formed by the light passing through the circular slit in the first image to obtain the sub-pixel circular outline.

[0061] Find the center of the circular outline; this center is the center of the local light-transmitting element.

[0062] Thirdly, embodiments of this application provide a spot center calculation device, the device comprising:

[0063] The image acquisition module is used to acquire the first image after the emitted light shines on a local light-transmitting element having 2N radially and uniformly arranged light-transmitting slits.

[0064] The first image processing module is used to fit the slit light spots formed by each light-transmitting slit in the first image into a first line segment, so as to obtain a second image with 2N first line segments.

[0065] The curve fitting module is used to fit the first line segments with the same slope on the second image into a first curve with the distance from each point on the first line segment to a specific point as the x-axis value and the gray level value of each point on the first line segment as the y-axis value.

[0066] The second image processing module is used to sample the first curve to obtain multiple sampling points, and to determine whether the gray value of the point in the second image corresponding to the multiple sampling points is zero. If it is zero, the ordinate value of the corresponding sampling point is assigned to the point in the second image with a gray value of zero, thereby obtaining a third image with N second line segments.

[0067] The spot center calculation module is used to take points with non-zero gray values ​​in the third image, perform surface fitting, and calculate the center point O1 of the fitted surface. This center point is the spot center.

[0068] Fourthly, embodiments of this application provide an optical pressure arm calculation system, which includes...

[0069] As mentioned above, the light spot center calculation device, in which

[0070] The center of the locally light-transmitting element coincides with the center of the pattern formed by the 2N light-transmitting slits.

[0071] The system also includes

[0072] The component center calculation module is used to calculate the center of a locally light-transmitting component using either the first or second image.

[0073] The optical pressure arm calculation module is used to calculate the distance between the center of the local light-transmitting element and the center of the light spot, and to calculate the optical pressure arm based on the conversion relationship between the pixels in the third image and the actual physical size.

[0074] Fourthly, embodiments of this application provide a partially transparent element, including...

[0075] The component body has an incident surface that includes a light-transmitting area that allows light to pass through and an opaque area that prevents light from passing through. The light-transmitting area includes an even number of radially arranged and uniformly spaced light-transmitting slits.

[0076] According to an embodiment of the fourth aspect of this application, the area of ​​the light-transmitting region is less than or equal to one-thousandth of the area of ​​the incident surface of the element body.

[0077] or

[0078] The width of the light-transmitting slit is greater than or equal to twice the wavelength of the selected incident light.

[0079] According to any of the foregoing embodiments of the fourth aspect of this application, the element body is a sheet-like structure, and the surface of the sheet has a centrally symmetrical structure.

[0080] and / or

[0081] The pattern structure formed by the light-transmitting slits is a centrally symmetrical structure.

[0082] The light spot center calculation method and apparatus of this application can calculate the light spot center by irradiating the emitted light onto an image formed by a local light-transmitting element having 2N radially uniformly arranged light-transmitting slits. This can be done with almost no impact on the light pressure generation effect.

[0083] The optical pressure arm calculation method and apparatus of this application design coincides with the center of the local light-transmitting element and the center of the pattern on the local light-transmitting element, thereby realizing the simultaneous calculation of the center of the light spot and the center of the local light-transmitting element from an image. Furthermore, it can track the center of the laser spot and the center of the local light-transmitting element in real time to adjust the laser emission parameters so that the laser can accurately hit the center of the target, providing technical support for laser alignment, laser tracking and other applications.

[0084] The local light-transmitting element in this application embodiment, by setting an even number of light-transmitting slits, can form an image with symmetrical light spots after being irradiated by incident light, thereby enabling the calculation of the center of the light spot without affecting the light pressure generation effect. Attached Figure Description

[0085] Figure 1 This is a schematic diagram of the planar structure of a partially light-transmitting element provided in one embodiment of this application;

[0086] Figure 2 This is a flowchart of a spot center calculation method provided in another embodiment of this application;

[0087] Figure 3 This is a schematic diagram of the first image provided in another aspect of the embodiment of this application;

[0088] Figure 4 This is a schematic diagram of the second image provided in another aspect of the embodiment of this application;

[0089] Figure 5 This is a schematic diagram of a first curve provided in another aspect of this application;

[0090] Figure 6 This is a schematic diagram of a third image provided in another aspect of the embodiment of this application;

[0091] Figure 7 This is a schematic diagram of a fitted surface provided in another embodiment of this application;

[0092] Figure 8 This is a flowchart of a spot center calculation method provided in another embodiment of this application;

[0093] Figure 9 This is a schematic diagram of the second image provided in another aspect of the embodiment of this application;

[0094] Figure 10 This is a data graph provided in another embodiment of this application before fitting the first line segment;

[0095] Figure 11 This is a flowchart of a spot center calculation method provided in another embodiment of this application;

[0096] Figure 12 This is a flowchart of a spot center calculation method provided in another embodiment of this application;

[0097] Figure 13 This is a flowchart of a spot center calculation method provided in another embodiment of this application;

[0098] Figure 14 This is a flowchart of a spot center calculation method provided in another embodiment of this application;

[0099] Figure 15 This is a flowchart of a method for calculating an optical pressure arm provided in another embodiment of this application;

[0100] Figure 16 This is a schematic diagram of the planar structure of a partially light-transmitting element provided in one embodiment of this application;

[0101] Figure 17 This is a schematic diagram of the structure of a spot center computing device provided in another embodiment of this application;

[0102] Figure 18 This is a schematic diagram of the structure of the optical pressure arm calculation system provided in another embodiment of this application. Detailed Implementation

[0103] The features and exemplary embodiments of various aspects of this application will be described in detail below. To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain this application and not to limit it. For those skilled in the art, this application can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this application by illustrating examples.

[0104] In scenarios where emitted light (e.g., laser) is needed to generate light pressure to exert force on a target object, it is often desirable that all beams projected onto the target object are completely reflected, and that the beam is projected to the center of the target object to generate the maximum force. However, if the beam is completely reflected, it is impossible to detect whether the center of the light spot hits the center of the target object, and therefore it is impossible to adjust the light emitter to ensure that the beam hits the center of the target object.

[0105] Based on this, the applicant of this application has creatively designed a locally transparent element with a special structure.

[0106] Please see Figure 1 One embodiment of this application provides a partially light-transmitting element comprising an element body 1, which has an incident surface 11 and an exit surface. The incident surface 11 of the element body 1 includes a light-transmitting region that allows light to pass through and an opaque region that prevents light from passing through. The light-transmitting region includes an even number (2N, where N is a positive integer) of radially arranged and uniformly spaced light-transmitting slits 12. After incident light illuminates the incident surface 11 of the element body 1, the light illuminating the light-transmitting slits 12 passes through the element body 1 and can be captured by a camera, forming a first image with a light spot having a shape similar to the light-transmitting slits 12. The center of the light spot can be calculated from this first image.

[0107] Please continue reading. Figure 1 Each light-transmitting slit 12 can be a straight line, and the width of the line is greater than or equal to twice the wavelength of the incident light illuminating the selected local light-transmitting element. Preferably, the width of the light-transmitting slit 12 is 5, 6, 7, 8, 9, 10, or 11 times the wavelength of the incident light. This width of the light-transmitting slit 12 can achieve a better Gaussian distribution of the emitted light spot.

[0108] In order to minimize the light pressure loss caused by incident light hitting the local light-transmitting element, the area of ​​the light-transmitting region formed by all the light-transmitting slits 12 is less than or equal to one-thousandth of the surface area of ​​the entire local light-transmitting element. This design will hardly cause any light pressure loss.

[0109] Please continue reading. Figure 1 In order to calculate the center of the light spot more accurately, the pattern formed by all the light-transmitting slits 12 is a centrally symmetrical pattern. This arrangement of the light-transmitting slits 12 can make the consistency between the light spots formed by each light-transmitting slit 12 higher, thereby making the calculated center of the light spot more accurate.

[0110] To simultaneously calculate the center of the light spot and the center of the target object (the locally transparent element), the element body 1 is a thin sheet structure with a centrally symmetrical surface (such as a square). The pattern structure formed by the light-transmitting slits 12 is also centrally symmetrical, and the center of symmetry of the element body 1 coincides with the center of symmetry of the pattern formed by the light-transmitting slits 12. Thus, the center of the light spot and the center of the locally transparent element can be calculated simultaneously using the first image captured by the camera, thereby determining whether the incident light hits the center of the locally transparent element precisely.

[0111] Of course, in order to calculate the center of the light spot and the center of the light pressure at the same time, when designing the local light-transmitting element, it is sufficient to ensure that the center of the local light-transmitting element coincides with the center of the pattern formed by the light-transmitting slit 12.

[0112] Please see Figure 2 The method for calculating the center of a light spot provided in another embodiment of the application includes the following steps.

[0113] S1. Acquire the first image after the emitted light shines on a local light-transmitting element having 2N radially uniformly arranged light-transmitting slits 12;

[0114] After incident light shines on the partial light-transmitting element, a portion of the light that hits the light-transmitting slit 12 penetrates the partial light-transmitting element and can be captured by the camera to form a first image, such as... Figure 3 As shown, the first image has 2N slits in a roughly straight line; 2N indicates that the number of light-transmitting slits 12 is even.

[0115] S2. Fit the slit light spots formed by each light-transmitting slit 12 in the first image into a first line segment to obtain a second image with 2N first line segments;

[0116] The second image obtained by fitting the slit spot into 2N first line segments using a fitting method is shown below. Figure 4 As shown, the point on the first line segment carries two pieces of information: one is the position information (i.e., coordinate value) on the second image, and the other is the gray value of the image at that point. The purpose of this processing is to facilitate subsequent data processing of the slit spot.

[0117] S3. Fit the first line segment with the same slope on the second image into a first curve with the distance from each point on the first line segment to a specific point as the x-axis value and the gray value of each point on the first line segment as the y-axis value.

[0118] After being fitted into the first line segment, each slit spot corresponds to a slope in the first line segment. Since the 2N light-transmitting slits 12 are arranged radially and uniformly, the slopes of two opposite first line segments should be the same. By fitting the data on these two opposite first line segments, N first curves can be obtained, such as... Figure 5 As shown, the first curve is generally a Gaussian distribution curve, and the vertical axis value of the first curve is the gray value.

[0119] S4. Sample the first curve to obtain multiple sampling points. If the gray value of the point in the second image corresponding to the multiple sampling points is zero, then assign the ordinate value of the corresponding sampling point to the point in the second image with the corresponding gray value of zero to obtain a third image with N second line segments.

[0120] Each point D on the first curve i It carries two pieces of information: the distance to a specific point, and the point D itself. i The grayscale value of point D i The distance information between a point and a specific point can be converted into positional information (i.e., coordinate values) on the second image. Therefore, each point on the first curve corresponds to a point on the second image.

[0121] Since there are no light spots (i.e., grayscale values ​​are zero) on the line connecting the two opposite first line segments before fitting, the first curve obtained through fitting is a continuous curve. By assigning grayscale values ​​to the points on the line connecting the two opposite first line segments in this step, the blocked light spot information can be recovered, thus obtaining the following... Figure 6 The third image shown;

[0122] S5. Take the points in the third image with non-zero gray values ​​and perform surface fitting, and calculate the center point O1 of the fitted surface;

[0123] After surface fitting, the following can be obtained: Figure 7 The results shown in the figure are as follows: the X and Y axes represent the horizontal and vertical coordinates, and the Z axis represents the grayscale value. It can be seen that... Figure 7 The surface shown is a Gaussian surface, which recovers the spot information of the incident light without obstruction. By calculating the coordinates of the center point O1 of the fitted surface, the center of the spot can be obtained, that is, this center point is the center of the spot.

[0124] In one embodiment, such as Figure 8 As shown, step S3 includes:

[0125] S31. Divide the first line segments with the same slope among the 2N first line segments on the second image into a group;

[0126] In this step, select the first line segment with the same slope to form a group, and you can get N groups;

[0127] S32. Take the leftmost non-zero gray value point of each group of first line segments as the origin, the distance of each other point on each group of first line segments to the origin as the x-coordinate value, and the gray value on the second image corresponding to each point on each group of first line segments as the y-coordinate value. Use the nonlinear least squares method to perform quadratic curve fitting on each group of first line segments to obtain N first curves.

[0128] like Figure 9 As shown, point U is the leftmost non-zero gray value point of the first line segment in this group. In the newly established coordinate system, point U is the origin, the horizontal axis is the distance from point U to the first line segment in this group and the points on the lines connecting the first line segments in this group, and the vertical axis is the corresponding image gray value of each point; the data before fitting is shown in the figure. Figure 10 As shown, the first curve obtained after fitting is as follows: Figure 5 As shown, the missing data between the two opposing first line segments has been recovered. Since point U has corresponding position information (i.e., coordinate values) in the second image, every point on the first curve also has corresponding position information (i.e., coordinate values) in the second image. Through this correspondence, the grayscale values ​​recovered through curve fitting can be assigned to the corresponding points in the second image. For example, as... Figure 4 As shown, in the second image, the gray value of point E on the line connecting the two opposite first line segments is zero. Therefore, the gray value of the point corresponding to point E on the first curve is assigned to point E, so that the gray value data on the line connecting the two opposite first line segments is restored.

[0129] In this embodiment, the leftmost non-zero gray value point of each group of first line segments is taken as a specific point. In other embodiments, the rightmost non-zero gray value point of each group of first line segments can be taken as a specific point, or a point outside the first line segment can be taken as a specific point, as long as a new coordinate system can be established and each point in the newly established coordinate system can correspond to the second image.

[0130] In one embodiment, such as Figure 11 As shown, step S4 includes:

[0131] S41. Sample the data points on the first curve every m data points to obtain M data points;

[0132] like Figure 5 As shown, the first curve obtained by fitting is a continuous and smooth curve. Taking some points on the first curve for image restoration can reduce the amount of computation.

[0133] S42. Search for the gray value at point P corresponding to each data point in the second image one by one, and determine whether the gray value at point P corresponding to each data point in the second image is zero.

[0134] Each point on the first curve has a corresponding point on the second image. This step can be used to determine whether the gray value of the corresponding point on the second image is zero, thereby finding the target point to be recovered.

[0135] S43. If the gray value of the corresponding point P in the second image is zero, then the ordinate value of the data point corresponding to point P is assigned to point P as the gray value of point P, thereby obtaining the third image.

[0136] The reason why the gray value of point P in the second image is zero is that the incident light is blocked by the local light-transmitting element and no light spot is formed. Through this step, the light spot can be recovered, which is equivalent to connecting the two opposite first line segments to form the second line segment, and thus calculating the center of the light spot.

[0137] In some embodiments, such as Figure 12 As shown, after the step "calculate the center point of the fitted surface", there is also a step...

[0138] S61. Take a point on each of the second line segments. The gray gradient value of each point is the same. Find the center O2 of the circle where each point is located.

[0139] The method to obtain the gray gradient value of a point W1 on the second line segment can be as follows: On the second line segment, take two points W2 and W3 with the same distance to the left and right of point W1, and calculate the difference in gray values ​​between points W2 and W3. This difference in gray values ​​is the gray gradient value of point W1.

[0140] This step is equivalent to finding the center O2 of the circle through the second line break. Since the gray value of the light spot formed by the incident light gradually changes from the center of the light spot to the radial direction, pixels with the same gray gradient value can form a circle. This step is to find the center of the circle formed by the points with the same gray value. This center can also be the center of the light spot.

[0141] S71. Average the coordinates of the center point O1 and the center O2 to obtain a new center point.

[0142] The new spot center can be obtained by averaging the spot centers obtained by the two methods, which can improve the accuracy of spot center determination.

[0143] Of course, the center of the light spot can also be determined in another way to further improve the accuracy of the light spot center determination. In some embodiments, such as... Figure 13 As shown, after the step "calculate the center point of the fitted surface", there is also a step...

[0144] S62. Take H points on each of the second line segments to form H circles with equal gray-level gradient values. Calculate the average coordinates of the centers of each circle to obtain the center O2.

[0145] In this step, instead of taking a single circle with equal grayscale value, we take H circles with equal grayscale gradient values; by finding the centers of multiple circles, we can improve the accuracy of the center finding.

[0146] S72. Average the coordinates of the center point O1 and the center O2 to obtain a new center point.

[0147] In some embodiments, such as Figure 14 As shown, step S62 includes:

[0148] S621. Select a second line segment; that is, you can first select any second line segment.

[0149] S622. Calculate the grayscale gradient value of each point on the selected second line segment;

[0150] S623. Select H points with different grayscale gradient values;

[0151] S624. On each of the remaining second line segments, search for H points that are the same as the selected H different gray-level gradient values; that is, select H points on each of the remaining second line segments, and the gray-level gradient values ​​of these H points are the same as the gray-level gradient values ​​of the H points selected on the first selected second line segment.

[0152] S625. Connect the points with the same gray-level gradient value on each of the second line segments to form H circles with the same gray-level gradient value; H circles with the same gray-level gradient value can be obtained by connecting the points with the same gray-level gradient value, or by performing curve fitting on the points with the same gray-level gradient value.

[0153] S626. Find the average of the center coordinates of H circles to obtain the center O2.

[0154] The center O2 obtained in this way has higher accuracy.

[0155] In some embodiments, the method further includes the following step before step S2:

[0156] S11. Denoise and / or smooth the first image to obtain a new first image. Denoising and smoothing can reduce the impact of noise.

[0157] In some embodiments, the proximal endpoints of an even number of light-transmitting slits 12 are concentrically circular. This type of light-transmitting slit 12 results in a more uniform shape of the slit spot, which can reduce the error in calculating the center of the spot.

[0158] In some embodiments, the distal endpoints of an even number of light-transmitting slits 12 are concentrically circular. Similarly, the shape of the slit spot formed by this type of light-transmitting slit 12 is more uniform, which can reduce the error in calculating the center of the spot.

[0159] In some embodiments, the proximal endpoints of an even number of light-transmitting slits 12 are concentric, and the distal endpoints of an even number of light-transmitting slits 12 are concentric. This type of light-transmitting slit 12 results in a more uniform shape of the slit spot, which can further reduce the error in calculating the center of the spot.

[0160] Please see Figure 15 The light pressure arm calculation method provided in another aspect of this application calculates the light spot center using the light spot center calculation method of any of the above embodiments, wherein the center of the local light-transmitting element coincides with the center of the pattern formed by 2N light-transmitting slits 12;

[0161] The calculation method for optical pressure arms also includes the following steps:

[0162] STP1: Calculate the center of the local light-transmitting element using the first image or the second image; since the center of the local light-transmitting element coincides with the center of the pattern formed by the light-transmitting slit 12, the center of the local light-transmitting element can be calculated using the light spot formed by the light-transmitting slit 12.

[0163] STP2: Calculate the distance between the center of the local light-transmitting element and the center of the light spot; After calculating the distance between the center of the local light-transmitting element and the center of the light spot, it can be determined whether the incident light hits the center of the local light-transmitting element.

[0164] STP3: Calculate the optical pressure arm based on the conversion relationship between the pixels in the third image and the actual physical size.

[0165] Since there is a corresponding relationship between the distance between two points on the image captured by the camera and the actual size of the object, the direction and distance of the incident light deviating from the center of the local light-transmitting element can be calculated by conversion. This deviation is the light pressure arm.

[0166] According to another aspect of the foregoing embodiments of this application, step STP1 includes:

[0167] STP11, take the proximal endpoints of each first line segment on the second image; on the local light-transmitting element, design the light-transmitting slit 12 so that the proximal endpoints of the light-transmitting slit 12 are concentric, then the proximal endpoints of the first line segments on the second image are also concentric.

[0168] STP12: Fit the data to 2N proximal endpoints; a continuous circle can be obtained through fitting.

[0169] STP13. Find the center of the fitted curve. This center is the center of the local light-transmitting element.

[0170] According to any of the foregoing embodiments of another aspect of this application, such as Figure 16As shown, the proximal endpoints of the light-transmitting slit 12 are concentric, and the local light-transmitting element also has a circular light-transmitting slit 13 connecting the proximal end of the light-transmitting slit 12.

[0171] Step STP1 includes:

[0172] STP14: Fit the circular slit light spot formed by the circular light-transmitting slit 13 in the first image into a circle.

[0173] STP15. Find the center of the circle. This center is the center of the local light-transmitting element.

[0174] According to any of the foregoing embodiments of another aspect of this application, the proximal endpoints of the light-transmitting slit 12 are concentrically circular, and the local light-transmitting element also has a circular light-transmitting slit 13 connecting the proximal ends of the light-transmitting slit 12.

[0175] Step STP1 includes:

[0176] STP16: Detect the circular slit light spot formed by the circular light-transmitting slit 13 on the first image to obtain the sub-pixel circular outline;

[0177] STP17: Find the center of the circular outline. This center is the center of the local light-transmitting element.

[0178] All three methods described above can determine the center of a local light-transmitting element.

[0179] Please see Figure 17 Another embodiment of this application provides a spot center calculation device including:

[0180] The image acquisition module is used to acquire the first image after the emitted light illuminates a local light-transmitting element having 2N radially and uniformly arranged light-transmitting slits 12.

[0181] The first image processing module is used to fit the slit light spots formed by each light-transmitting slit 12 in the first image into a first line segment, so as to obtain a second image with 2N first line segments.

[0182] The curve fitting module is used to fit the first line segments with the same slope on the second image into a first curve with the distance from each point on the first line segment to a specific point as the x-axis value and the gray level value of each point on the first line segment as the y-axis value.

[0183] The second image processing module is used to sample the first curve to obtain multiple sampling points, and to determine whether the gray value of the point in the second image corresponding to the multiple sampling points is zero. If it is zero, the ordinate value of the corresponding sampling point is assigned to the point in the second image with a gray value of zero, thereby obtaining a third image with N second line segments.

[0184] The spot center calculation module is used to take points with non-zero gray values ​​in the third image, perform surface fitting, and calculate the center point O1 of the fitted surface. This center point is the spot center.

[0185] Please see Figure 18 Another embodiment of this application provides an optical pressure arm calculation system including:

[0186] As provided in the foregoing embodiments, the spot center calculation device, wherein

[0187] The center of the locally light-transmitting element coincides with the center of the pattern formed by the 2N light-transmitting slits 12.

[0188] The system also includes:

[0189] The component center calculation module is used to calculate the center of a locally light-transmitting component using either the first or second image.

[0190] The optical pressure arm calculation module is used to calculate the distance between the center of the local light-transmitting element and the center of the light spot, and to calculate the optical pressure arm based on the conversion relationship between the pixels in the third image and the actual physical size.

Claims

1. A method for calculating the center of a light spot, characterized in that: The method comprises the following steps acquiring a first image collected after emitting light irradiates a local light-transmitting element having 2N light-transmitting slits arranged radially and uniformly, fitting a slit light spot formed by each of the light-transmitting slits on the first image into a first line segment to obtain a second image having 2N first line segments, selecting a specific point, which is a point outside the first line segment, and establishing a coordinate system with the specific point as the origin, so that each point in the coordinate system can correspond to a point on the second image; fitting the first line segments with the same slope on the second image into a first curve with the distance between each point on the first line segment and the specific point as the horizontal coordinate value and the gray value of each point on the first line segment as the vertical coordinate value, sampling the first curve to obtain a plurality of sampling points, and if the gray value of a point in the second image corresponding to the sampling point is zero, assigning the vertical coordinate value of the corresponding sampling point to the point in the second image with the zero gray value to obtain a third image having N second line segments, performing surface fitting on the points with non-zero gray values in the third image, calculating the center point O1 of the fitted surface, and the center point is the light spot center.

2. The light spot center calculation method according to claim 1, wherein: the proximal end points of the 2N light-transmitting slits are on a circle, and / or the distal end points of the 2N light-transmitting slits are on a circle.

3. The light spot center calculation method according to claim 1, wherein: before the step of fitting the slit light spot formed by each of the light-transmitting slits on the first image into a first line segment to obtain a second image having an even number of first line segments, the method further comprises the step of: performing denoising and / or smoothing on the first image to obtain a new first image.

4. The light spot center calculation method according to claim 1, wherein: the step of fitting the first line segments with the same slope on the second image into a first curve with the distance between each point on the first line segment and the specific point as the horizontal coordinate value and the gray value of each point on the first line segment as the vertical coordinate value comprises grouping the first line segments with the same slope among the 2N first line segments on the second image into a group, taking the leftmost point with a non-zero gray value of each group of first line segments as the origin, taking the distance between each point on each group of first line segments and the origin as the horizontal coordinate value, and taking the gray value of each point on each group of first line segments on the second image as the vertical coordinate value, performing quadratic curve fitting on each group of first line segments by using a nonlinear least squares method to obtain N first curves.

5. The light spot center calculation method according to claim 1, wherein: the step of sampling the first curve to obtain a plurality of sampling points and assigning the vertical coordinate value of the corresponding sampling point to the point in the second image with the zero gray value to obtain a third image comprises sampling every m data points on the first curve to obtain M data points, searching the gray value of the point P in the second image corresponding to each data point one by one, and If the gray value at the corresponding point P in the second image is zero, the vertical coordinate value of the data point corresponding to point P is assigned to point P as the gray value of point P, thereby obtaining a third image.

6. The method of claim 1, wherein: after the step of "calculating the center point of the fitting surface", further comprising steps of taking a point on each of the second line segments, each point having the same gray gradient value, and calculating the center O2 of the circle on which the points lie, averaging the coordinates of the center point O1 and the center O2 to obtain a new center point.

7. The method of claim 1, wherein: after the step of "calculating the center point of the fitting surface", further comprising steps of taking H points on each of the second line segments to form H circles with the same gray gradient value, and averaging the center coordinates of the circles to obtain the center O2, averaging the coordinates of the center point O1 and the center O2 to obtain a new center point.

8. The method of claim 7, wherein: the step of "taking H points on each of the second line segments to form H circles with the same gray gradient value, and averaging the center coordinates of the circles to obtain the center O2" comprises selecting one of the second line segments, calculating the gray gradient values of the points on the selected second line segment, selecting H points with different gray gradient values, searching for H points on each of the remaining second line segments that have the same gray gradient values as the selected H points, respectively, connecting the points on each of the second line segments that have the same gray gradient value to form H circles with the same gray gradient value, averaging the center coordinates of the H circles to obtain the center O2.

9. A method of computing a light pressure arm, characterized by: calculating the center of a light spot using the method of any one of claims 1 to 8, wherein the center of the local light transmission element coincides with the center of a pattern formed by 2N light transmission slits, the light pressure arm calculation method further comprises steps of calculating the center of the local light transmission element from the first or second image, calculating the distance between the center of the local light transmission element and the center of the light spot, calculating the light pressure arm according to a conversion relationship between the pixels in the third image and actual physical dimensions.

10. The light pressure arm calculation method of claim 9, wherein: the step of "calculating the center of the local light transmission element from the first or second image" comprises taking the near-center end points of each first line segment on the second image, fitting 2N near-center end points, calculating the center of the fitting curve, which is the center of the local light transmission element.

11. The light pressure arm calculation method of claim 9, wherein: the near-center end points of the light transmission slits are concentric, and the local light transmission element further has a circular light transmission slit connecting the near-center ends of the light transmission slits, the step of "calculating the center of the local light transmission element from the first or second image" comprises fitting the circular slit light spots formed by the circular light transmission slits on the first image into a circle, calculating the center of the circle, which is the center of the local light transmission element.

12. The light pressure arm calculation method of claim 9, wherein: end points of the proximal ends of the light-transmitting slits are co-circular, and the local light-transmitting element further has a circular light-transmitting slit connecting the proximal ends of the light-transmitting slits, the step of "calculating the center of the local light-transmitting element through the first image or the second image" comprises detecting a circular-slit light spot formed through the circular light-transmitting slit on the first image to obtain a sub-pixel circular contour, calculating the center of the circular contour, which is the center of the local light-transmitting element.

13. A light spot center calculation device characterized by comprising: The device comprises an image acquisition module configured to acquire a first image collected after emitting light irradiates a local light-transmitting element having 2N light-transmitting slits arranged radially and uniformly, a first image processing module configured to fit a slit light spot formed through each of the light-transmitting slits on the first image into a first line segment to obtain a second image having 2N first line segments, a curve fitting module configured to fit a first curve, the fitting step being as follows: selecting a specific point, the specific point being a point outside the first line segment, establishing a coordinate system with the specific point as the origin, each point in the coordinate system being able to correspond to a point on the second image; fitting the first line segments on the second image having the same slope into a first curve with the distance from each point on the first line segment to the specific point as the horizontal coordinate value and the gray value of each point on the first line segment as the vertical coordinate value, a second image processing module configured to sample the first curve to obtain a plurality of sampling points and determine whether the gray value of a point in the second image corresponding to the plurality of sampling points is zero, if the gray value is zero, assigning the vertical coordinate value of the corresponding sampling point to the point in the second image with the zero gray value to obtain a third image having N second line segments, a light spot center calculation module configured to perform surface fitting on the points in the third image with non-zero gray values and calculate the center point O1 of the fitted surface, the center point being the light spot center.

14. A light pressure arm computing system, characterized by: comprise The light spot center calculation device of claim 13, wherein the center of the local light-transmitting element coincides with the center of the pattern formed by the 2N light-transmitting slits, the system further comprises an element center calculation module configured to calculate the center of the local light-transmitting element through the second image, a light pressure arm calculation module configured to calculate the distance between the center of the local light-transmitting element and the light spot center and calculate the light pressure arm according to the conversion relationship between the pixels in the third image and the actual physical size.

Images