Surface profile measurement method, device and equipment, storage medium and product

Abstract

The invention discloses a surface profile measurement method, device and equipment, a storage medium and a product, and relates to the technical field of optical surface measurement, and the surface profile measurement method comprises the steps: enabling a target light beam to irradiate a dispersion confocal lens, and enabling the dispersion confocal lens to separate the light of different wavelengths in the target light beam; controlling the two-axis motion platform to drive a to-be-measured surface to move to different preset sampling points, and acquiring reflection signals obtained by irradiating the to-be-measured surface by the light point by point; determining a target signal with the strongest signal in the reflected signals, and determining the distance between the to-be-measured surface and the dispersion confocal lens based on the wavelength corresponding to the target signal; and based on the distance, determining the point cloud of the to-be-measured surface, fitting the point cloud of the to-be-measured surface to obtain the surface type of the fitted plane, and performing surface type measurement on the fitted plane to obtain a measurement result. According to the invention, an operator does not need to have a high technical level, and the use difficulty is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical surface measurement, and particularly to a surface profile measurement method, device, equipment, storage medium and product. BACKGROUND

[0002] In the related art, optical surface measurement technologies such as interferometry, optical profilometry, confocal microscopy and laser speckle method, although play an important role in different application scenarios, but the above methods are complex to operate, and require operators to have high technical level, which increases the difficulty of use. SUMMARY

[0003] The main purpose of the present application is to provide a surface profile measurement method, device, equipment, storage medium and product, which aims to solve the technical problems of related art that the operation is complex, the operator needs to have high technical level, and the difficulty of use is increased.

[0004] To achieve the above purpose, the present application provides a surface profile measurement method, which comprises:

[0005] At different preset sampling points, the reflection signal obtained by point-by-point collection of light irradiation on the measured surface is collected, wherein the light irradiated on the measured surface is obtained by separating different wavelengths of light in the target light beam through a dispersion ranging lens;

[0006] Determine the target signal with the strongest signal in the reflection signal, and determine the distance between the measured surface and the dispersion confocal lens based on the wavelength corresponding to the target signal;

[0007] Based on the distance, determine the measured surface point cloud, fit the measured surface point cloud, obtain the fitted plane profile, and perform surface profile measurement on the fitted plane to obtain the measurement result.

[0008] In an embodiment, the step of determining the measured surface point cloud based on the distance, fitting the measured surface point cloud, and obtaining the fitted plane comprises:

[0009] Based on the distance and the coordinates of the preset sampling point corresponding to the distance, determine the measured point point cloud corresponding to the sampling point;

[0010] Remove outliers in the measured point point cloud, perform coordinate normalization processing on the measured point point cloud after removing the outliers, and fit the normalized measured point point cloud to obtain the fitted plane profile;

[0011] Based on the full-field error map, error elimination is performed on the fitted plane profile to obtain the eliminated plane profile.

[0012] In an embodiment, the step of performing error elimination on the fitted plane surface based on the full-field error map to obtain an error-eliminated plane surface further comprises:

[0013] performing node division on the sample surface to obtain a high-density grid, and performing point-by-point scanning on the nodes in the high-density grid to obtain actual coordinates of each node;

[0014] calculating errors of different dimensions based on the actual coordinates and theoretical coordinates of the nodes, wherein the errors include perpendicularity errors and motion platform errors;

[0015] constructing a full-field error map based on the errors, wherein the full-field error map represents a mapping relationship between the coordinates of the preset sampling points on the two-axis motion platform and the errors.

[0016] In an embodiment, the motion platform errors include straightness errors, flatness errors, and Abbe errors, and the step of calculating errors of different dimensions based on the actual coordinates and theoretical coordinates of the nodes comprises:

[0017] determining a perpendicularity error based on a non-perpendicular angle between an axis of a probe of the two-axis motion platform and a plane biaxial;

[0018] calculating a distance offset of the two-axis motion platform when moving on different axes based on the actual coordinates and theoretical coordinates of the nodes to obtain a straightness error;

[0019] calculating a distance offset based on the actual coordinates and theoretical coordinates of the nodes to obtain a flatness error;

[0020] determining an Abbe error based on the non-perpendicular angle and an offset distance between the axis and the plane biaxial.

[0021] In an embodiment, the step of removing outliers from the to-be-tested point cloud, performing coordinate normalization on the to-be-tested point cloud after the removal of the outliers, and fitting the to-be-tested point cloud after the normalization to obtain a fitted plane surface comprises:

[0022] acquiring distances of a preset number of adjacent point clouds for each to-be-tested point cloud;

[0023] calculating a mean value and a standard deviation of the distances;

[0024] determining outliers in the to-be-tested point cloud based on the mean value and the standard deviation, and removing the outliers in the to-be-tested point cloud;

[0025] The outlying points are removed from the point cloud of the to-be-tested points, and the point cloud of the to-be-tested points after the outlying points are removed is subjected to coordinate normalization processing, and the normalized point cloud of the to-be-tested points is fitted to obtain a fitted plane surface type.

[0026] In an embodiment, the step of removing the outlying points from the point cloud of the to-be-tested points, and the point cloud of the to-be-tested points after the outlying points are removed is subjected to coordinate normalization processing, and the normalized point cloud of the to-be-tested points is fitted to obtain a fitted plane surface type comprises:

[0027] The point cloud of the to-be-tested points is translated and rotated until the center of mass of the point cloud of the to-be-tested points is located at the origin of the reference coordinate system;

[0028] Based on the center of mass, the point cloud of the to-be-tested points is mapped in the reference coordinate system to obtain the normalized point cloud of the to-be-tested points;

[0029] Based on the target error surface model, the point cloud of the to-be-tested points is fitted to obtain a fitted plane surface type.

[0030] In addition, to achieve the above object, the present application also provides a surface surface type measuring device, which comprises:

[0031] The separation module is configured to irradiate a target light beam to a dispersive range-finding lens, and separate light rays of different wavelengths in the target light beam through the dispersive range-finding lens.

[0032] The acquisition module is configured to control the two-axis motion platform to move the to-be-tested surface to different preset sampling points, and acquire reflection signals obtained by irradiating the to-be-tested surface with the light rays point by point.

[0033] The determination module is configured to determine a target signal with the strongest signal in the reflection signals, and determine a distance between the to-be-tested surface and the dispersive range-finding lens based on a wavelength corresponding to the target signal.

[0034] The fitting module is configured to determine a to-be-tested surface point cloud based on the distance, fit the to-be-tested surface point cloud, obtain a fitted plane surface type, and measure the surface surface type of the fitted plane to obtain a measurement result.

[0035] In addition, to achieve the above object, the present application also provides a surface surface type measuring device, which comprises a memory, a processor, and a computer program stored on the memory and executable on the processor, the computer program being configured to implement the steps of the surface surface type measuring method as described above.

[0036] In addition, to achieve the above object, the present application also provides a storage medium, which is a computer readable storage medium, and the storage medium stores a computer program, and the computer program is executed by a processor to implement the steps of the surface surface type measuring method as described above.

[0037] In addition, to achieve the above object, the application further provides a computer program product, which comprises a computer program, and the computer program, when executed by a processor, implements the steps of the surface profile measurement method as described above.

[0038] The one or more technical solutions provided in the application have at least the following technical effects:

[0039] Compared with related art, although optical surface measurement technologies such as interferometry, optical profilometry, confocal microscopy and laser speckle method play an important role in different application scenarios, the above methods are complex to operate, and require operators to have a high technical level, thereby increasing the difficulty of use. The application irradiates a target beam to a dispersive range-finding lens, separates light rays of different wavelengths in the target beam through the dispersive range-finding lens, controls a two-axis motion platform to move a surface to be measured to different preset sampling points, and collects reflection signals obtained by the light rays irradiating the surface to be measured point by point, determines a target signal with the strongest signal in the reflection signals, determines the distance between the surface to be measured and the dispersive range-finding lens based on the wavelength corresponding to the target signal, determines the point cloud of the surface to be measured based on the distance, fits the point cloud of the surface to be measured, obtains a fitted plane profile, and performs surface profile measurement on the fitted plane to obtain a measurement result. The application separates light rays of different wavelengths in the target beam through the dispersive range-finding lens, and after obtaining the reflection signals reflected by the light rays, the distance of the surface to be measured can be determined by determining the wavelength corresponding to the longest signal, and then the point cloud of the surface to be measured is determined, and the point cloud of the surface to be measured is fitted automatically. After fitting, the surface profile measurement can be performed on the fitted plane to obtain a measurement result, which is relatively simple to operate and does not require operators to have a high technical level, thereby reducing the difficulty of use. BRIEF DESCRIPTION OF DRAWINGS

[0040] The accompanying drawings, which are incorporated into and form part of the specification, illustrate embodiments consistent with the application and, together with the specification, serve to explain the principles of the application.

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, for those skilled in the art, other drawings can also be obtained based on these drawings without creative labor.

[0042] Figure 1 A flowchart is provided for the surface profile measurement method embodiment one of the application;

[0043] Figure 2Structure diagram of surface profile measurement device for surface profile measurement method of the present application;

[0044] Figure 3 Flow chart of surface profile measurement for surface profile measurement method of the present application;

[0045] Figure 4 Surface profile diagram without error elimination for surface profile measurement method of the present application;

[0046] Figure 5 Surface profile diagram after error elimination for surface profile measurement method of the present application;

[0047] Figure 6 Flow chart provided by embodiment two of surface profile measurement method of the present application;

[0048] Figure 7 Fitted plane diagram for surface profile measurement method of the present application;

[0049] Figure 8 Module structure diagram of surface profile measurement device of the present application;

[0050] Figure 9 Device structure diagram of hardware running environment involved by surface profile measurement method in the present application.

[0051] The object, function features and advantages of the present application will be further explained with reference to the accompanying drawings in combination with embodiments. DETAILED DESCRIPTION

[0052] It should be understood that the specific embodiments described herein are only used to explain the technical solutions of the present application, and are not used to limit the present application.

[0053] In order to better understand the technical solutions of the present application, the following will be described in detail in combination with the drawings in the specification and specific embodiments.

[0054] The main solution of the present application embodiment is: irradiating a target light beam to a dispersion rangefinder, separating light rays of different wavelengths in the target light beam through the dispersion rangefinder; controlling a two-axis motion platform to move a surface to be measured to different preset sampling points, and collecting reflection signals obtained by the light rays irradiating the surface to be measured point by point; determining a target signal with the strongest signal in the reflection signals, determining the distance between the surface to be measured and the dispersion rangefinder based on the wavelength corresponding to the target signal; determining the surface to be measured point cloud based on the distance, fitting the surface to be measured point cloud to obtain a fitted plane profile, and measuring the surface profile of the fitted plane to obtain a measurement result.

[0055] In the related art, optical surface measurement technologies such as interferometry, optical profilometry, confocal microscopy and laser speckle method, although play an important role in different application scenarios, but the above methods are complex in operation, and require operators to have high technical level, increasing the difficulty of use.

[0056] The present application separates the light rays of different wavelengths in the target light beam through the dispersion ranging lens, and after obtaining the reflection signal reflected by the light rays, the distance of the measured surface can be determined by determining the wavelength corresponding to the longest signal, and then the point cloud of the measured surface is determined, and the point cloud of the measured surface is automatically fitted, and after fitting, the surface of the fitted plane is measured to obtain the measurement result, which is relatively simple in operation and does not require operators to have high technical level, reducing the difficulty of use.

[0057] It should be noted that the execution subject of the present embodiment can be a computing service device with data processing, network communication and program running functions, such as a tablet computer, a personal computer, a mobile phone, etc., or an electronic device capable of realizing the above functions, a surface profile measurement device, etc. The surface profile measurement device is taken as an example to describe the present embodiment and the following embodiments.

[0058] Based on this, the present application provides a surface profile measurement method, which is described with reference to Figure 1 , Figure 1 The flowchart of the first embodiment of the surface profile measurement method of the present application is shown in the figure.

[0059] In the present embodiment, the surface profile measurement method comprises steps S10-S40:

[0060] Step S10, at different preset sampling points, the reflection signal obtained by irradiating the light on the measured surface is collected point by point, wherein the light irradiated on the measured surface is obtained by separating the light rays of different wavelengths in the target light beam through the dispersion ranging lens;

[0061] It should be noted that the execution subject of the present embodiment is a surface profile measurement device, which is described with reference to Figure 2 , Figure 2 The structure diagram of the surface profile measurement device is provided, Figure 2 1 is a marble platform, 2 is an XY motion platform, 3 is a Z-axis motion platform, 4 is a dispersion ranging lens, 5 is a connecting tool, and 6 is a sensor. The surface profile measurement device is provided with a measuring head, which comprises a dispersion ranging lens and a sensor.

[0062] Additionally, it should be noted that the surface topography measuring device irradiates a target light beam (usually a broadband light source or a white light interference light source) to the dispersive range-finding lens at the beginning of measurement. The dispersive range-finding lens contains a dispersive element (such as a prism or a diffraction grating) inside, which can separate light rays of different wavelengths in the target light beam at certain angles or positions.

[0063] It can be understood that the surface topography measuring device can set the scanning path and the distribution of sampling points according to the measurement requirements. The spacing between the sampling points can be adjusted according to the accuracy requirements (for example, 0.1mm~1mm). The surface topography measuring device accurately aligns the current measurement point of the dispersive range-finding lens with the center of the measurement light path of the optical probe by controlling the two-axis motion platform (XY motion platform). At each sampling point position, the probe emits light rays of different wavelengths after separation to irradiate the surface of the measurement point. The reflected light signal is returned to the local area through the sensor.

[0064] Further, the surface topography measuring device can use a high-precision surface measurement strategy based on curvature distribution analysis. The scanning area is set as a two-dimensional plane grid (5x5), and each point is a sampling point. For each point, a three-point curvature method is used to calculate the local curvature. The local curvature values of all points are mapped into a two-dimensional curvature distribution map, and adaptive path planning is performed according to the curvature distribution map.

[0065] Specifically, the step distance dynamic adjustment strategy of adaptive path planning:

[0066] Flat area: the step distance is expanded to 150% of the reference value;

[0067] Medium curvature area: keep the reference step distance;

[0068] High curvature area: the step distance is reduced to 30% of the reference value.

[0069] Further, the path planning algorithm (improved TSP)

[0070] a. Sub-region division

[0071] Use clustering algorithms (such as K-means) to divide points with similar curvatures into several sub-regions.

[0072] b. Path planning in sub-regions

[0073] Use a serpentine scanning path inside each sub-region to improve scanning efficiency.

[0074] c. Inter-regional path optimization

[0075] Use an improved Traveling Salesman Problem (TSP) algorithm to optimize the movement path between sub-regions to minimize the empty travel.

[0076] Further, the surface profile measuring device obtains the access sequence and path coordinates of all sampling points according to the output path sequence, for the motion controller to execute.

[0077] In step S20, a target signal with the strongest signal in the reflected signal is determined, and a distance between the measured surface and the chromatic confocal lens is determined based on a wavelength corresponding to the target signal.

[0078] It should be noted that at each sampling point, the sensor receives reflected light from the measured surface, and the surface profile measuring device analyzes the received spectral signal to find the wavelength corresponding to the maximum light intensity. Since the broadband light source is decomposed into light beams of different wavelengths by a dispersive element (such as a prism or a diffraction grating) and forms multiple focal points distributed along the Z-axis direction in space. Each wavelength corresponds to a specific focal plane. When these light rays illuminate the measured surface, only one wavelength will illuminate the measured point on the measured surface, so the target signal with the strongest signal is the signal corresponding to the light illuminating the measured surface. The surface profile measuring device pre-establishes a mapping function between wavelength and focal length through experiment or theoretical modeling, so the vertical distance between the measured point and the lens can be determined according to the wavelength corresponding to the strongest signal.

[0079] In step S30, based on the distance, a measured surface point cloud is determined, the measured surface point cloud is fitted to obtain a fitted plane profile, and the fitted plane is measured to obtain a measurement result.

[0080] It can be understood that the surface profile measuring device constructs a three-dimensional point cloud set (i.e., a measured surface point cloud) based on the distance values measured at each sampling point in combination with the spatial coordinates (xi, yi) provided by the XY motion platform, and geometrically fits the point cloud data to obtain a fitted plane profile. Further, the planeness and roughness of the measured plane can be calculated according to the plane profile, for reference Figure 3 , Figure 3 A whole flowchart of surface profile measurement is provided.

[0081] In a feasible implementation, step S30 can include the following steps:

[0082] Based on the distance and the coordinates of the preset sampling point corresponding to the distance, a measured point point cloud corresponding to the sampling point is determined.

[0083] It should be noted that the surface profile measuring device constructs a corresponding three-dimensional space point based on the two-dimensional coordinates corresponding to each sampling point and the distance corresponding to the sampling point, and determines the measured point point cloud of the entire measured plane based on the space point corresponding to each sampling point.

[0084] Remove outliers in the point cloud of the to-be-tested point, perform coordinate normalization processing on the point cloud after removing the outliers, and perform fitting on the normalized point cloud to obtain a fitted plane surface type;

[0085] It can be understood that the surface profile measuring device first removes outliers in the point cloud of the to-be-tested point to eliminate the influence of abnormal data on subsequent modeling; then performs coordinate normalization processing on the point cloud after removing the outliers, and finally performs geometric fitting on the normalized point cloud to obtain a fitted plane surface type.

[0086] Based on the full-field error map, the fitted plane surface type is error-eliminated to obtain the error-eliminated plane surface type.

[0087] It should be noted that the full-field error map is constructed based on the error of each measurement point to the fitted plane. The surface profile measuring device subtracts the full-field error map from the fitted plane surface type to obtain an accurate error-eliminated plane surface type.

[0088] Specifically, referring to Figure 4 , Figure 4 The surface profile map without error elimination is provided, and after error elimination is performed on the point cloud in Figure 2 , the surface profile map after error elimination can be obtained Figure 5 , Figure 5 The surface profile map after error elimination is provided.

[0089] In a possible implementation, the step of error-eliminating the fitted plane surface type based on the full-field error map to obtain the error-eliminated plane surface type includes the following steps:

[0090] Divide the sample surface into nodes to obtain a high-density grid, and perform point-by-point scanning on the nodes in the high-density grid to obtain actual coordinates of each node;

[0091] It can be understood that the surface profile measuring device pre-sets the range of the scanning area and sets the scanning step distance to 10 pm to achieve a micron-level spatial sampling density. The XY two-axis motion platform is moved according to the set step distance, and the probe is used to scan the reference surface row by row and column by column. After each movement, the actual coordinates of the point are obtained by triggering measurement once at the current position.

[0092] Based on the actual coordinates and the theoretical coordinates of the nodes, errors in different dimensions are calculated, wherein the errors include perpendicularity errors and motion platform errors;

[0093] It should be noted that the theoretical coordinates are ideal positions of the nodes determined by the grid division rule. The surface profile measuring device can comprehensively calculate the errors in different dimensions by measuring the difference between the actual value and the theoretical value.

[0094] Further, although the surface profile measuring device provides high resolution for three-dimensional reconstruction by combining a precision motion platform with a dispersion confocal distance measuring technology, the measurement accuracy is affected by the coupling of multiple source errors, including but not limited to mechanical assembly deviation, calibration error of the dispersion optical system, and environmental disturbance (such as temperature drift or vibration).

[0095] Based on the error, a full-field error map is constructed, wherein the full-field error map represents the mapping relationship between the coordinates of the preset sampling points on the two-axis motion platform and the error.

[0096] It can be understood that after the surface profile measuring device performs high-density grid scanning on the sample surface, the deviation of each node can be calculated, and based on the two-dimensional coordinates of each node and the error value corresponding to the node, a full-field error map can be established to measure the full-field error.

[0097] In a feasible implementation, based on the actual coordinates and the theoretical coordinates of the nodes, the step of calculating errors of different dimensions includes:

[0098] Based on the non-orthogonal angle between the axis and the plane of the two-axis motion platform, the perpendicularity error is determined.

[0099] It should be noted that the measurement axis of the probe head (i.e. the optical axis or the probe axis) should be ideally perpendicular to the XY plane, constituting the Z axis. The surface profile measuring device calculates the angle deviation (i.e. the non-orthogonal angle) θ z between the axis of the probe head and the XY plane, to obtain the perpendicularity error α xy .

[0100] E vertical (x, y) = xgtanθ x +ygtanθ y

[0101] Specifically, the linear drift of the measurement value with position caused by the above factors can be represented as:

[0102] Based on the actual coordinates and the theoretical coordinates of the nodes, the distance offset of the two-axis motion platform when moving in different axes is calculated to obtain the straightness error.

[0103] It can be understood that since there is a non-orthogonal angle α xy between the two axes of the motion platform, the surface profile measuring device defines an ideal reference straight line for each scanning path (such as the X-axis direction), and calculates the shortest distance offset of each sampling point to the ideal reference straight line as the straightness deviation of the point, wherein the straightness deviation includes the error of the X-axis and the error of the Y-axis.

[0104] Further, the positioning error of the motion platform can be decomposed into the straightness error of the XY axis and the perpendicularity error (non-orthogonal angle of the two axes), and the relationship between the actual coordinates and the theoretical coordinates under the comprehensive influence of the straightness error and the perpendicularity error can be expressed as:

[0105] x' = x + Δx(x, y) + y tan α xy

[0106] y' = y + Δy(x, y)

[0107] The error can be mapped by calibration (known feature point spacing), and after mapping, the polynomial compensation function is fitted as follows:

[0108]

[0109] Wherein, the compensation function is also applicable to the Y axis, and the coefficients a ij By least square method, the real-time compensation of the motion trajectory is finally realized.

[0110] The distance offset is calculated by the actual coordinates and the theoretical coordinates of the nodes, and the flatness error is obtained.

[0111] It should be noted that the surface profile measuring device determines the deviation of the device on the Z axis by the difference between the actual coordinates and the theoretical coordinates, and obtains the flatness error.

[0112] Specifically, in order to eliminate the inaccuracy of measurement caused by error, the surface profile measuring device will first calibrate the error on the Z axis, and use optical-grade flat crystal as ideal plane, which can be theoretically expressed as z ref (x, y) = 0, but due to the deviation, the measured value is different from the theoretical value, referring to Figure 4 , Figure 4 The measured surface profile of the reference surface is provided, and the measured coordinates of each point The ideal coordinates should be (x i , y i , 0), and the flatness error can be expressed as:

[0113]

[0114] Based on the offset distance between the non-orthogonal angle and the axis and the offset distance between the axis and the plane biaxial, the Abbe error is determined.

[0115] It can be understood that the measurement point of the probe of the surface profile measuring device is usually not located at the center of rotation of the motion shaft or the center line of the guide rail, and there is an offset distance representing the lateral deviation between the measurement point of the probe and the motion shaft, so the measurement error caused by the offset and non-perpendicularity between the probe axis and the motion shaft is calculated, that is, the Abbe error is obtained.

[0116] Specifically, the straightness error Δz of the guide rail x (x), Δz y (y) flatness error Δz flat (x,y) and Abbe error, the error can be expressed as:

[0117]

[0118] In this embodiment, by combining the motion platform, the hardware structure is essentially simplified, the self-diagnosis error compensation system greatly reduces the need for manual calibration, and the manufacturing and maintenance costs are reduced from the source

[0119] Based on the first embodiment of the present application, the same or similar contents as the above embodiment one can refer to the above introduction, and the following will not be repeated. On this basis, please refer to Figure 6 , remove the outliers in the point cloud of the to-be-measured point, perform coordinate normalization processing on the to-be-measured point cloud after removing the outliers, and perform fitting on the normalized to-be-measured point cloud to obtain the fitted plane surface type. The surface surface type measurement method further includes steps S01-S04:

[0120] Step S01, obtaining the distance of a predetermined number of adjacent point clouds for each of the to-be-measured point clouds;

[0121] It should be noted that the predetermined number can be set to 15. The surface surface type measurement device calculates the distance distribution of each point and its nearest 15 points.

[0122] Step S02, calculating the mean and standard deviation of the distance;

[0123] It can be understood that the surface surface type measurement device calculates the neighborhood distance mean and standard deviation corresponding to each point.

[0124] Step S03, determining the outliers in the to-be-measured point cloud based on the mean and the standard deviation, and removing the outliers in the to-be-measured point cloud;

[0125] It should be noted that if the surface surface type measurement device determines that the Z value of a point deviates from the neighborhood mean by more than three times the standard deviation, it is determined as a noise point, i.e. an outlier, and is removed.

[0126] Step S04, performing coordinate normalization processing on the to-be-measured point cloud after removing the outliers, and performing fitting on the normalized to-be-measured point cloud to obtain the fitted plane surface type.

[0127] It is understandable that the surface profile measurement device performs coordinate normalization on the point cloud after removing outliers to improve numerical stability; then the least squares method is used to perform plane fitting on the normalized point cloud to obtain the optimal fitting plane, referring to Figure 7 , Figure 7 A schematic diagram of the fitted plane is provided.

[0128] In a feasible implementation, step S04 includes the following steps:

[0129] Translate and rotate the point cloud of the test point until the center of mass of the point cloud of the test point is located at the origin of the reference coordinate system;

[0130] It should be noted that the surface profile measurement device performs translation and rotation operations on the point cloud of the measured point so that its center of mass is aligned with the origin of the reference coordinate system and its main direction is adjusted to be consistent with the reference coordinate axis.

[0131] Based on the centroid, mapping the point cloud of the point to be measured into the reference coordinate system to obtain a normalized point cloud of the point to be measured;

[0132] It can be understood that the surface profile measuring device maps the point cloud to be measured to a unified reference coordinate system based on the centroid information of the point cloud, completes the translation and optional direction alignment operations of the point cloud, and thus obtains normalized point cloud data.

[0133] Based on the target error surface model, the point cloud of the point to be measured is fitted to obtain a fitted plane surface shape.

[0134] It should be noted that the surface profile measuring device performs least square fitting on the normalized point cloud of the test points according to a preset target error surface model (such as an ideal plane, a polynomial surface, etc.) to obtain the optimal matching geometric model.

[0135] Specifically, for free-form surfaces, the surface profile measurement device uses a non-uniform rational B-spline (NURBS) model to establish a parametric surface. By discretizing the parameter domain, the measurement points are mapped to the (U, V) space, and the inverse algorithm is used to optimize the control point coordinates and weight factors. The surface equation can be expressed as:

[0136]

[0137] Among them, P ij is the control point, w ij is the weight, N j,q (v) is the p-order B-spline basis function. In order to verify the measurement accuracy, another optical-grade flat crystal was selected as the measured surface.

[0138] In this embodiment, outliers are removed by neighborhood statistics filtering, effectively eliminating abnormal data caused by environmental interference, sensor noise or false triggering in the measurement process, and significantly improving the robustness of subsequent modeling and fitting.

[0139] It should be noted that the above examples are only for understanding the present application and do not constitute a limitation on the surface profile measurement method of the present application. More forms of simple transformation based on this technical concept are within the protection scope of the present application.

[0140] The present application also provides a surface profile measurement device, please refer to Figure 8 , the surface profile measurement device comprises:

[0141] The acquisition module 10 is configured to collect reflection signals obtained by irradiating light on a to-be-measured surface point by point at different preset sampling points, wherein the light irradiated on the to-be-measured surface is obtained by separating different wavelengths of light in a target light beam through a dispersion rangefinder lens.

[0142] The determination module 20 is configured to determine a target signal with the strongest signal in the reflection signal, and determine the distance between the to-be-measured surface and the dispersion rangefinder lens based on the wavelength corresponding to the target signal.

[0143] The fitting module 30 is configured to determine a to-be-measured surface point cloud based on the distance, fit the to-be-measured surface point cloud, obtain a fitted planar surface profile, and perform surface profile measurement on the fitted planar surface to obtain a measurement result.

[0144] Optionally, the fitting module comprises:

[0145] The error elimination sub-module is configured to determine a to-be-measured point cloud corresponding to the sampling point based on the distance and the coordinates of the preset sampling point corresponding to the distance, remove outliers in the to-be-measured point cloud, perform coordinate normalization processing on the to-be-measured point cloud after removing the outliers, fit the normalized to-be-measured point cloud, obtain a fitted planar surface profile, perform error elimination on the fitted planar surface profile based on a full-field error map, and obtain the planar surface profile after elimination.

[0146] The normalization sub-module is configured to obtain a preset number of adjacent point clouds of each to-be-measured point cloud, calculate the mean and standard deviation of the distances, determine outliers in the to-be-measured point cloud based on the mean and the standard deviation, remove the outliers in the to-be-measured point cloud, perform coordinate normalization processing on the to-be-measured point cloud after removing the outliers, fit the normalized to-be-measured point cloud, and obtain a fitted planar surface profile.

[0147] Optionally, the normalization sub-module comprises:

[0148] mapping unit is configured to translate and rotate the point cloud of the to-be-tested point until a centroid of the point cloud of the to-be-tested point is located at an origin of a reference coordinate system, map the point cloud of the to-be-tested point in the reference coordinate system based on the centroid to obtain a normalized point cloud of the to-be-tested point, and fit the point cloud of the to-be-tested point based on the target error surface model to obtain a fitted plane surface.

[0149] Optionally, the error elimination sub-module comprises:

[0150] The construction unit is configured to divide nodes on a sample surface to obtain a high-density grid, perform point-by-point scanning on the nodes in the high-density grid to obtain actual coordinates of each node, and calculate errors of different dimensions based on the actual coordinates and theoretical coordinates of the nodes, wherein the errors comprise perpendicularity errors and motion platform errors, and construct a full-field error map based on the errors, wherein the full-field error map represents a mapping relationship between coordinates of the preset sampling points on a two-axis motion platform and the errors.

[0151] Optionally, the construction unit comprises:

[0152] The error calculation sub-unit is configured to determine a perpendicularity error based on a non-perpendicular angle between an axis of a probe of the two-axis motion platform and a plane double axis, calculate a distance offset amount of the two-axis motion platform when moving in different axes based on the actual coordinates and the theoretical coordinates of the nodes to obtain a straightness error, calculate a distance offset amount based on the actual coordinates and the theoretical coordinates of the nodes to obtain a flatness error, and determine an Abbe error based on the non-perpendicular angle and an offset distance between the axis and the plane double axis.

[0153] The surface profile measurement device provided in the present application adopts the surface profile measurement method in the above embodiments, and can solve the technical problem of surface profile measurement. Compared with the prior art, the surface profile measurement device provided in the present application has the same beneficial effects as the surface profile measurement method provided in the above embodiments, and other technical features in the surface profile measurement device are the same as the features disclosed in the above embodiments, which will not be repeated here.

[0154] The present application provides a surface profile measurement device, which comprises at least one processor and a memory in communication connection with the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the surface profile measurement method in the above embodiment one.

[0155] Reference will be made to the following Figure 9, which shows a schematic structural diagram of a surface profile measurement device suitable for implementing an embodiment of the present application. The surface profile measurement device in the embodiment of the present application may include, but is not limited to, mobile terminals such as mobile phones, laptop computers, tablet computers, digital broadcast receivers, PDAs (Personal Digital Assistants), PMPs (Portable Media Players), and in-vehicle terminals (e.g., in-vehicle navigation terminals), as well as fixed terminals such as digital TVs and desktop computers. Figure 9 The surface profile measurement device shown is merely an example and should not limit the functions and scope of use of the embodiments of the present application.

[0156] like Figure 9 As shown, the surface profile measurement device may include a processing device 1001 (e.g., a central processing unit, a graphics processing unit, etc.), which can perform various appropriate actions and processes based on programs stored in a read-only memory (ROM) 1002 or programs loaded from a storage device 1003 into a random access memory (RAM) 1004. RAM 1004 also stores various programs and data required for the operation of the surface profile measurement device. Processing device 1001, ROM 1002, and RAM 1004 are interconnected via a bus 1005. An input / output (I / O) interface 1006 is also connected to the bus. Typically, the following systems can be connected to I / O interface 1006: input devices 1007 including, for example, a touch screen, touchpad, keyboard, mouse, image sensor, microphone, accelerometer, gyroscope, etc.; output devices 1008 including, for example, a liquid crystal display (LCD), speaker, vibrator, etc.; storage device 1003 including, for example, a magnetic tape, hard disk, etc.; and communication device 1009. The communication device 1009 can allow the surface profile measurement device to communicate wirelessly or wired with other devices to exchange data. Although the figure shows a surface profile measurement device with various systems, it should be understood that it is not required to implement or have all the systems shown. More or fewer systems can be implemented or provided instead.

[0157] In particular, according to the embodiments disclosed in the present application, the process described above with reference to the flowchart can be implemented as a computer software program. For example, the embodiments disclosed in the present application include a computer program product comprising a computer program carried on a computer readable medium, the computer program containing program codes for executing the method shown in the flowchart. In such embodiments, the computer program can be downloaded and installed from a network through a communication device, or installed from the storage device 1003, or installed from the ROM 1002. When the computer program is executed by the processing device 1001, the above-mentioned functions defined in the method of the embodiments disclosed in the present application are executed.

[0158] The surface topography measuring device provided by the present application adopts the surface topography measuring method in the above-mentioned embodiments, and can solve the technical problem of surface topography measurement. Compared with the prior art, the surface topography measuring device provided by the present application has the same beneficial effects as the surface topography measuring method provided by the above-mentioned embodiments, and other technical features in the surface topography measuring device are the same as the features disclosed in the previous embodiment method, which will not be repeated here.

[0159] It should be understood that various parts of the present application can be realized by hardware, software, firmware or a combination thereof. In the description of the above-mentioned embodiments, specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0160] The above is merely specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

[0161] The present application provides a computer readable storage medium having stored thereon computer readable program instructions (i.e. computer program) for executing the surface topography measuring method in the above-mentioned embodiments.

[0162] The computer readable storage medium provided in the application may, for example, be a U disk, but is not limited to an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, system, or device, or any combination of the above. More specific examples of the computer readable storage medium may include, but are not limited to, an electrical connection with one or more conductive wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In the present embodiment, the computer readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, system, or device. The program code contained on the computer readable storage medium can be transmitted by any suitable medium, including but not limited to an electrical wire, an optical cable, an RF (Radio Frequency), and the like, or any suitable combination of the above.

[0163] The above computer readable storage medium can be included in a surface profile measuring device, or can exist separately without being assembled into a surface profile measuring device.

[0164] The above computer readable storage medium carries one or more programs, when the one or more programs are executed by the surface profile measuring device, the surface profile measuring device is caused to: irradiate a target light beam to a dispersive confocal lens, separate light rays of different wavelengths in the target light beam through the dispersive confocal lens; control a two-axis motion platform to move a surface to be measured to different preset sampling points, and collect reflection signals obtained by the light rays irradiating the surface to be measured point by point; determine a target signal with the strongest signal in the reflection signals, determine a distance between the surface to be measured and the dispersive confocal lens based on a wavelength corresponding to the target signal; based on the distance, determine a point cloud of the surface to be measured, fit the point cloud of the surface to be measured, obtain a fitted plane profile, and measure the fitted plane to obtain a measurement result.

[0165] Computer program code for carrying out operations of the present application can be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C++ or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code can execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection can be made to an external computer (for example, through the Internet using an Internet Service Provider).

[0166] The flow diagrams and the block diagrams in the drawings are illustrations of architectures, functionalities, and operations of possible implementations of systems, methods, and computer program products according to various embodiments of the present application. In this regard, each block in the flow diagrams or block diagrams can represent a module, a segment, or a portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that in some alternative implementations, the functions noted in the blocks can occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently or the blocks may

[0167] The modules involved in the embodiments of the present application can be implemented in the form of software or in the form of hardware. In some cases, the name of the module does not constitute a limitation on the module itself.

[0168] The readable storage medium provided by the present application is a computer readable storage medium, which stores computer readable program instructions (i.e. computer programs) for executing the surface profile measurement method described above, and can solve the technical problem of surface profile measurement. Compared with the prior art, the computer readable storage medium provided by the present application has the same beneficial effects as the surface profile measurement method provided by the above-mentioned embodiments, which will not be described here.

[0169] The application also provides a computer program product comprising a computer program which, when executed by a processor, implements the steps of the surface topography measurement method as described above.

[0170] The computer program product provided by the application can solve the technical problem of surface topography measurement. Compared with the prior art, the beneficial effects of the computer program product provided by the application are the same as those of the surface topography measurement method provided by the above-mentioned embodiments, and are not described here.

[0171] The above only describes some embodiments of the application, and does not limit the patent scope of the application. Any equivalent structural transformation made by using the content of the specification and drawings, or direct / indirect application in other related technical fields under the technical concept of the application is included in the patent protection scope of the application.

Claims

1. A surface profile measurement method, characterized in that: The surface profile measurement method comprises: At different preset sampling points, the reflection signals obtained by irradiating the surface to be measured with light are collected point by point, wherein the light irradiating the surface to be measured is obtained by separating light of different wavelengths in the target light beam through a dispersion ranging lens; Determining a target signal having the strongest signal among the reflected signals, and determining a distance between the surface to be measured and the dispersion ranging lens based on a wavelength corresponding to the target signal; Based on the distance, a point cloud of the surface to be measured is determined, the point cloud of the surface to be measured is fitted to obtain a fitted plane shape, and a surface shape measurement is performed on the fitted plane to obtain a measurement result.

2. The surface profile measurement method according to claim 1, wherein: The steps of determining a point cloud of a surface to be measured based on the distance, fitting the point cloud of the surface to be measured, and obtaining a fitted plane surface shape include: Determine a point cloud of a point to be measured corresponding to the sampling point based on the distance and the coordinates of the preset sampling point corresponding to the distance; removing outliers from the point cloud of the test points, performing coordinate normalization processing on the point cloud of the test points after removing the outliers, and fitting the normalized point cloud of the test points to obtain a fitted plane surface shape; Based on the full-field error map, errors are eliminated on the fitted plane surface shape to obtain the eliminated plane surface shape.

3. The surface profile measurement method according to claim 2, wherein: The step of performing error elimination on the fitted planar surface shape based on the full-field error map to obtain the eliminated planar surface shape includes: Dividing the sample surface into nodes to obtain a high-density grid, scanning the nodes in the high-density grid point by point to obtain the actual coordinates of each node; Calculating errors in different dimensions based on the actual coordinates and the theoretical coordinates of the nodes, wherein the errors include verticality errors and motion platform errors; Based on the error, a full-field error map is constructed, wherein the full-field error map represents a mapping relationship between the coordinates of the preset sampling point on the two-axis motion platform and the error.

4. The surface profile measurement method according to claim 3, wherein: The motion platform error includes a straightness error, a flatness error, and an Abbe error. The step of calculating errors of different dimensions based on the actual coordinates and the theoretical coordinates of the nodes includes: determining a perpendicularity error based on a non-orthogonal angle between an axis of a probe of the two-axis motion platform and two axes of a plane; Based on the actual coordinates and the theoretical coordinates of the nodes, the distance offset of the two-axis motion platform when different axes move is calculated to obtain the straightness error; Calculate the distance offset between the actual coordinates and the theoretical coordinates of the node to obtain the flatness error; An Abbe error is determined based on the non-orthogonal angle and the offset distance between the axis and the planar biaxial axis.

5. The surface profile measurement method according to claim 4, wherein: The steps of removing outliers from the point cloud of the test points, normalizing the coordinates of the point cloud of the test points after removing the outliers, fitting the normalized point cloud of the test points, and obtaining a fitted plane surface shape include: Obtaining distances to a preset number of adjacent point clouds for each point cloud to be measured; Calculate the mean and standard deviation of the distance; Determining outliers in the point cloud of the test points based on the mean and the standard deviation, and removing the outliers in the point cloud of the test points; The coordinates of the point cloud of the test points after the outliers are removed are normalized, and the normalized point cloud of the test points is fitted to obtain a fitted plane surface shape.

6. The surface profile measurement method according to claim 5, wherein: The steps of normalizing the coordinates of the point cloud of the test points after removing the outliers, fitting the normalized point cloud of the test points, and obtaining the fitted plane surface shape include: Translate and rotate the point cloud of the test point until the center of mass of the point cloud of the test point is located at the origin of the reference coordinate system; Based on the centroid, mapping the point cloud of the point to be measured into the reference coordinate system to obtain a normalized point cloud of the point to be measured; Based on the target error surface model, the point cloud of the point to be measured is fitted to obtain a fitted plane surface shape.

7. A surface profile measuring device, characterized in that: The device comprises: An acquisition module is used to collect reflection signals obtained by irradiating the surface to be measured with light at different preset sampling points, wherein the light irradiating the surface to be measured is obtained by separating light of different wavelengths in the target light beam through a dispersion ranging lens; a determination module, configured to determine a target signal having the strongest signal among the reflected signals, and determine a distance between the surface to be measured and the dispersion ranging lens based on a wavelength corresponding to the target signal; The fitting module is used to determine the point cloud of the surface to be measured based on the distance, fit the point cloud of the surface to be measured to obtain the surface shape of the fitted plane, and measure the surface shape of the fitted plane to obtain a measurement result.

8. A surface profile measuring device, characterized in that: The device comprises: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program is configured to implement the steps of the surface profile measurement method according to any one of claims 1 to 6.

9. A storage medium, characterized in that: The storage medium is a computer-readable storage medium, and a computer program is stored on the storage medium. When the computer program is executed by a processor, the steps of the surface profile measurement method according to any one of claims 1 to 6 are implemented.

10. A computer program product, characterized in that The computer program product comprises a computer program, and when the computer program is executed by a processor, the steps of the surface profile measurement method according to any one of claims 1 to 6 are implemented.

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