A laser spot image processing method, an automatic focusing method and a medium

Abstract

The application provides a laser spot image processing method, an automatic focusing method and a medium. The processing method comprises the following steps: acquiring a plurality of laser spot images corresponding to different laser energies; dividing the laser spot images based on the reflectivity of a surface area of a to-be-measured object and / or pixel values of the laser spot images, acquiring first data satisfying a first condition and second data not satisfying the first condition; screening a first pixel range and a second pixel range satisfying imaging requirements based on the first data and the second data; the imaging requirements are that there are laser spots in the laser spot images corresponding to the first data and there are laser spots in the laser spot images corresponding to the second data; and taking a laser energy range corresponding to the first pixel range and the second pixel range as an effective exposure condition. Based on the effective exposure condition, first effective data and second effective data are determined, and a fusion method is used to solve the problem that the same laser energy cannot accurately obtain a laser spot image of a region with large reflectivity difference.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of image processing, in particular to a laser spot image processing method, an automatic focusing method and a medium. BACKGROUND

[0002] Optical microscopes magnify the image of the surface of the object to be measured by means of lens imaging. In order to obtain a meaningful image, the microscope objective must be precisely focused on the sample surface, and the depth of field of a high-power microscope objective is generally only a few microns. The operator of the microscope objective often needs to spend a lot of time manually adjusting the distance between the objective and the object to be measured to achieve focusing. Microscopic automatic focusing technology calculates the current defocus amount of the objective through a feedback signal and converts it into a motor movement signal, and through the motor movement of the objective, the focusing process is automated.

[0003] According to the type of feedback signal, microscopic automatic focusing technology can be divided into image-based automatic focusing technology and laser-based automatic focusing technology. Image-based automatic focusing technology uses an image sharpness evaluation function to determine the current defocus amount with a quantitative sharpness value. The judgment result of this technology depends on the state of the collected image and is easily affected by the lighting environment. Moreover, the focusing speed is slow and the focusing range is small.

[0004] Laser-based automatic focusing technology adds a laser signal to the ordinary microscope. The defocus amount of the object to be measured is obtained by calculating the shape of the laser spot (including the centroid, radius, and curvature, etc.), and the moving direction and distance of the objective are controlled according to the defocus amount, so that the distance between the microscope objective and the surface of the object to be measured is within the depth of field of the objective, thereby achieving automatic focusing of the microscope objective. Therefore, this technology has a larger focusing range and faster focusing speed, and is widely used in industrial detection fields.

[0005] Generally, for various reflectivity conditions, the exposure strategy of the laser (such as adjusting the exposure time, exposure distance, laser energy, etc.) can be adjusted appropriately according to the reflectivity to make the spot image clearer and improve the processing efficiency during the detection and focusing process of the object to be measured. For example, Chinese patent CN119291910A adjusts the laser power, camera exposure time and gain setting, and sets the minimum threshold estimate of the line spot width to accurately control the scanning step and pause length of the focusing motor, thereby achieving fast and stable focusing effect.

[0006] If the surface of the object to be measured has multiple reflectivities, and the reflectivity difference is large, adjusting the exposure strategy of the laser (such as adjusting the exposure time, exposure distance, laser energy, etc.) in the microscopic automatic focusing system cannot achieve accurate focusing of the surface of the object to be measured.

[0007] As in the high exposure strategy (such as increasing laser energy, increasing exposure time), the low reflectivity area corresponds to the laser spot image with clear spots, but the high reflectivity area corresponds to the laser spot image with overexposure; on the contrary, in the low exposure strategy (such as reducing laser energy, reducing exposure time), the high reflectivity area corresponds to the laser spot image with clear spots, but the low reflectivity area corresponds to the laser spot image without clear spots, and effective data cannot be obtained for related calculations.

[0008] Therefore, for the surface of the object to be measured with multiple reflectivity regions, only by adjusting the exposure strategy, there is no way to lock the focus, or there is an unstable focus, so that the defocus amount calculation of the surface of the object to be measured is not accurate, and the focusing demand of the surface of the object to be measured with multiple refractive indices cannot be met.

[0009] Chinese patent CN105578009A discloses a laser spot imaging device, which proposes a method for calculating the center of the laser spot image in the CCD line array photosensitive device under overexposure in laser triangulation, so that the laser scanning vision system can obtain high-precision measurement results in a large dynamic range. The patent relates to the principle of laser triangulation, which is different from the imaging principle of the present scheme, and the technical means used in the scheme are also different from the present scheme.

[0010] Chinese patent CN116088130A discloses a line laser focusing method and device, optical equipment and storage medium. The patent determines the first focusing operation of the focusing lens corresponding to the zoom position according to the spot image, and then performs segmented detection on the line laser according to the spot image to determine the focusing area of the line laser on the surface of the object to be measured, so as to control the focusing lens to perform the second focusing operation on the object to be measured, and realize accurate determination of the focusing point of different objects to be measured. The technical means of the patent is different from the present application.

[0011] Journal paper "Laser automatic focusing method based on light field calculation and image processing algorithm" (doi: 10.3788 / gzxb20245311.1132002), which proposes a method for determining the focusing position based on the relationship between the spot diameter size and the collection position, and solves the problem of quantitatively finding the focal position in femtosecond laser three-dimensional machining by combining light field distribution calculation. The technical means of the paper is different from the present application. SUMMARY

[0012] The present application proposes a laser spot image processing method, an automatic focusing method and a medium, which at least solves one of the above technical problems.

[0013] To achieve the above-mentioned purpose, the present application proposes the following technical scheme:

[0014] A processing method of a laser spot image, comprising:

[0015] Obtaining a plurality of laser spot images corresponding to different laser energies; the laser spot images are formed by reflection of a surface of a to-be-measured object, and the surface of the to-be-measured object has at least two regions with different reflectivities;

[0016] Based on the reflectivity of the regions of the surface of the to-be-measured object and / or pixel values of the laser spot images, the laser spot images are divided to obtain first data satisfying a first condition and second data not satisfying the first condition;

[0017] The first condition is that the reflectivity is greater than a set value and / or the pixel value is greater than a division threshold;

[0018] Based on the first data and the second data, a first pixel range and a second pixel range satisfying an imaging requirement are screened; the imaging requirement is that there is a spot in the laser spot image corresponding to the first data and there is a spot in the laser spot image corresponding to the second data;

[0019] A laser energy range corresponding to the first pixel range and the second pixel range is taken as an effective exposure condition.

[0020] Further, the method further comprises:

[0021] Based on the first pixel range, a pixel value not greater than a first effective threshold is assigned as a fixed value to form first effective data;

[0022] Based on the second pixel range, a pixel value not less than a second effective threshold is assigned as a fixed value to form second effective data;

[0023] A maximum value of the first effective data and the second effective data in any pixel point is taken as a pixel value of the pixel point to obtain effective data;

[0024] The second effective threshold is less than the first effective threshold, and the fixed value is less than a current pixel value.

[0025] Further, the method further comprises:

[0026] Fusion of a pixel value corresponding to any laser energy value in a first energy range of any pixel point in the first data and a pixel value corresponding to any laser energy value in a second energy range of the pixel point is performed to obtain first fusion data;

[0027] Fusion of a pixel value corresponding to any laser energy value in the first energy range of any pixel point in the second data and a pixel value corresponding to any laser energy value in the second energy range of the pixel point is performed to obtain second fusion data;

[0028] The first fusion data and the second fusion data are used to calculate effective data;

[0029] The first data and the second data have the same laser energy value in the first energy range and the same laser energy value in the second energy range. The laser energy range corresponding to the first pixel range is the first energy range, and the laser energy range corresponding to the second pixel range is the second energy range.

[0030] Further, the difference between the minimum value of the reflectivity corresponding to the first data and the maximum value of the reflectivity corresponding to the second data is greater than a reflectivity threshold value, and / or the difference between the minimum value of the pixel value in the first data and the maximum value of the pixel value in the second data is greater than a pixel threshold value.

[0031] Further, the pixel range meeting the imaging requirement comprises:

[0032] The first pixel range is the intersection of the pixel range in which the pixel value in the first data is less than a first threshold value and the pixel range in which the pixel value in the second data is greater than a second threshold value and less than the first threshold value.

[0033] The second pixel range is the intersection of the pixel range in which the pixel value in the second data is greater than the second threshold value and less than the first threshold value and the pixel range in which the pixel value in the first data is not less than the first threshold value.

[0034] The first threshold value is used to screen the overexposed image data, and the second threshold value is less than the first threshold value.

[0035] Further, the effective exposure condition comprises the first energy range corresponding to the first pixel range and the second energy range corresponding to the second pixel range, and the minimum value of the laser energy in the second energy range is greater than the maximum value of the laser energy in the first energy range.

[0036] Further, the second threshold value is the pixel value corresponding to the second data when the first data is equal to the laser energy value corresponding to the first threshold value for the first time.

[0037] Further, the method further comprises:

[0038] The laser energy-pixel value curves corresponding to the first data and the second data are fitted respectively, the pixel range meeting the imaging requirement is determined according to the first threshold value and the second threshold value, and the first energy range and the second energy range are screened as the effective exposure condition based on the response relationship between the reflectivity and the light intensity. The application also provides an automatic focusing method, comprising:

[0039] Based on the same inventive concept, the application also provides an automatic focusing method, comprising:

[0040] The effective data is obtained by using the processing method described above.

[0041] The spot centroid of the effective data is calculated to obtain the defocus amount of the surface of the object to be measured, and automatic focusing is realized.

[0042] In another aspect, the present application also provides a computer readable storage medium storing a computer program, wherein the computer program, when executed by a processor, causes the processor to perform the method described above.

[0043] The present application has the following advantages:

[0044] The present embodiment utilizes the sensitive difference of different reflectivity regions on the surface of the object to be measured to the light intensity, and proposes to divide the high reflectivity and low reflectivity based on the acquired laser spot image and / or pixel value to obtain the first data and the second data.

[0045] Since there are at least two regions with different reflectivity on the surface of the object to be measured, the microscopic automatic focusing system cannot achieve accurate focusing. Therefore, to achieve the focusing control of the surface of the object to be measured, the effective exposure conditions corresponding to different reflectivity regions should be analyzed, that is, under the effective exposure condition corresponding to any reflectivity, the spot in the spot image reflected by the reflectivity region is clear. In this way, accurate focusing of any reflectivity region can be achieved, or based on the exposure parameter analysis of the above appropriate conditions, the balance condition is further obtained to achieve accurate focusing of the surface of the object to be measured.

[0046] In order to further exclude the image data in the first data and the second data that does not meet the imaging requirements, the present embodiment analyzes the pixel change process to screen the pixel range that meets the imaging requirements in the first data and the second data.

[0047] Based on the difference in sensitivity of different reflectivity to light and the change process of pixel value in the laser spot image, the present embodiment analyzes the overexposed image data in the first data and the second data to determine the pixel range that meets the imaging requirements.

[0048] Due to the sensitive difference of different reflectivity regions to light intensity, under the effective exposure condition of the spot image reflected by the high reflectivity region, the spot image reflected by the low reflectivity region may have no spot (there may be pixel data but no spot, not no pixel data) or weak spot; similarly, under the effective exposure condition of the spot image reflected by the low reflectivity region, the spot image reflected by the high reflectivity region is overexposed.

[0049] In the present embodiment, based on the analysis of the existence of the spot in the spot image reflected by the low and high reflectivity regions, the pixel value is taken as the screening condition to obtain the effective exposure condition corresponding to the existence of the spot in the spot image reflected by the low and high reflectivity regions.

[0050] The embodiment filters laser energy meeting the high reflectivity area requirement and laser energy meeting the low reflectivity area requirement from the above energy ranges according to the first energy range and the second energy range, performs exposure adjustment according to the laser energy meeting the high reflectivity area requirement and the laser energy meeting the low reflectivity area requirement, determines the first effective data and the second effective data, obtains the light spot image of the surface of the object under test under at least two reflectivities based on the pixel values in the high reflectivity area and the low reflectivity area in the first effective data and the second effective data by using a fusion method, and solves the problem that the same laser energy cannot accurately obtain the light spot image of the area with large reflectivity difference and avoids the problem that the surface of the object under test is overexposed or underexposed.

[0051] The embodiment filters the pixel values corresponding to the laser energy values in the first energy range and the pixel values corresponding to the laser energy values in the second energy range in the first data according to the characteristics of the first data and the second data, performs fusion calculation, so as to obtain the first fusion data corresponding to the high reflectivity area; similarly, the second data is filtered, so as to calculate the second fusion data corresponding to the low reflectivity area; finally, the effective data is obtained by using the first fusion data and the second fusion data, the problem that the same laser energy cannot accurately obtain the light spot image of the area with large reflectivity difference is solved, and the problem that the surface of the object under test is overexposed or underexposed is avoided. BRIEF DESCRIPTION OF DRAWINGS

[0052] Figure 1 is the optical schematic diagram of the laser-based microscopic automatic focusing technology;

[0053] Figure 2 is the flowchart of the processing method of the laser light spot image in the embodiment of the present application;

[0054] Figure 3 is the schematic diagram of the laser energy-pixel value curve in the embodiment of the present application;

[0055] Figure 4 is the flowchart of the method for obtaining the effective data in the embodiment of the present application;

[0056] Figure 5 is the flowchart of the method for obtaining the effective data in the embodiment of the present application;

[0057] Figure 6 is the flowchart of the automatic focusing method in the embodiment of the present application. DETAILED DESCRIPTION

[0058] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments of the present application.

[0059] As Figure 1As shown, the optical principle of laser-based microscopic autofocus technology is as follows:

[0060] Laser unit 1 emits a parallel laser beam, which is modulated by cylindrical lens 2 into an asymmetric beam that diverges in the curvature direction and is collimated in the non-curvature direction. The asymmetric beam loses half its energy after passing through baffle 3 and propagates only on one side of the optical axis. After being reflected by mirror 4, first beam splitter 5, and second beam splitter 6, it enters microscope objective 7, where it is focused onto the surface of the object under test 8.

[0061] The laser beam reflected from the surface of the object under test 8 passes through the microscope objective 7, the second beam splitter 6, and the first beam splitter 5, and is then focused by the focusing lens 9 onto the surface of the first sensor, forming a laser spot. The first sensor acquires an image of the laser spot reflected from the surface of the object under test (same as "spot image"). The first sensor is a black and white sensor, and the laser spot image is a grayscale image, where the pixel value is equal to the grayscale value.

[0062] The image processing unit calculates the defocus amount based on the shape of the laser spot in the light spot image, and converts the defocus amount into a control signal for the drive unit, so that the drive unit drives the microscope objective 7 to move and achieve autofocus.

[0063] The illumination source 10, together with the third beam splitter 11, the second beam splitter 6, and the microscope objective 7, forms a coaxial illumination optical path. The tube mirror 12, the second sensor, and the microscope objective 7 form an imaging optical path. The second sensor is used to acquire the surface image of the object under test 8 after focusing.

[0064] Preferably, the laser unit 1 can be a line laser or a point laser. If it is a point laser, a collimating lens is also required to ensure that the laser unit emits a parallel laser beam in order to obtain a parallel beam.

[0065] Preferably, the drive unit can be a motor or other drive device to achieve precise movement control of the microscope objective 7.

[0066] Based on the above-mentioned microscopic autofocus system, the first sensor acquires the light spot image reflected from the surface of the object to be tested, and the pixel value of each pixel in the light spot image represents the average brightness information of each pixel.

[0067] like Figure 2 As shown, in order to achieve focusing control on the surface of a test object with multiple reflectivity regions, and to enable the second sensor to acquire images with high-quality visual effects, this application proposes a laser spot image processing method, including:

[0068] Acquire several laser spot images corresponding to different laser energies; the laser spot images are formed by reflection from the surface of the object under test, and there are at least two regions with different reflectivities on the surface of the object under test.

[0069] The surface of the object to be measured has at least two regions with different reflectivity, and the difference in reflectivity is large, so that only the exposure strategy (such as adjusting one or more of the exposure time, exposure distance, and laser energy) cannot achieve automatic focusing of the surface of the object to be measured.

[0070] The surface of the object to be measured may have defects, resulting in different reflectivity of different regions of the surface.

[0071] The surface of the object to be measured can be composed of materials with different reflectivity, such as semiconductor wafers; or optical films, special coatings, due to their material properties, the surface may have multiple different reflectivity regions; or setting optical films, special coatings with different thicknesses, etc., will also cause the surface to be measured to have multiple different reflectivity regions.

[0072] In order to obtain laser spot images of different laser energies, an initial energy value can be set, and the laser energy is increased by a certain amount to obtain several laser spot images under a plurality of exposure conditions corresponding to the laser energy as a variable.

[0073] Among the laser spot images corresponding to the initial energy value, the laser spot image corresponding to the low reflectivity region may have pixel data but no spot, or no pixel data; the laser spot image corresponding to the high reflectivity region has a spot.

[0074] Laser is the light of atomic stimulated radiation. The principle of laser formation is that the electron in the atom absorbs energy and jumps from low energy level to high energy level, and when it falls from high energy level to low energy level, the released energy is emitted in the form of photons. Therefore, the induced (excited) photon beam (laser) has highly consistent optical characteristics of photons, and has the characteristics of monochromaticity, good directionality, and higher brightness compared to ordinary light sources.

[0075] Due to the strong directionality and high brightness of laser compared to ordinary light sources, and according to actual measurement experience, the adjustment of exposure distance and exposure time in the exposure strategy of laser has no obvious improvement effect on imaging.

[0076] Therefore, the present application selects to analyze the influence of laser energy on laser spot image formation to obtain effective exposure conditions corresponding to different reflectivity regions to realize automatic focusing control.

[0077] Based on the reflectivity of the surface region of the object to be measured and / or the pixel value of the laser spot image, the laser spot image is divided to obtain first data satisfying a first condition and second data not satisfying the first condition.

[0078] The first condition is that the reflectivity is greater than a set value and / or the pixel value is greater than a division threshold.

[0079] Preferably, the reflectivity of the surface of the object to be measured can be measured and calculated by a laser energy detector or the like device.

[0080] Or the material of the surface of the object to be measured is known to correspond to the reflectivity.

[0081] The set value is set according to the plurality of reflectivities of the surface of the object to be measured, which can be the median of the plurality of reflectivities, or the average of any two reflectivities, or other calculation methods.

[0082] If the reflectivity of the surface of the object to be measured is known, it is divided into high reflectivity (reflectivity greater than the set value) and low reflectivity (reflectivity not greater than the set value) according to the set value, so as to facilitate the later calculation. Among them, high reflectivity and low reflectivity are relative concepts, which are only used to describe the size relationship of the known reflectivity.

[0083] The image data of the laser spot image corresponding to the high reflectivity area is taken as the first data; and the image data of the laser spot image corresponding to the low reflectivity area is taken as the second data.

[0084] Preferably, only part of the reflectivity greater than the set value can be selected to select the image data of the laser spot image corresponding to the part of the reflectivity area as the first data; and similarly, part of the reflectivity less than the set value can be selected to determine the second data.

[0085] For the application scenario that there are two or more reflectivity regions on the surface of the object to be measured, in order to facilitate subsequent calculation, the plurality of reflectivity regions corresponding to the laser spot image are divided into first data and second data according to the size of the reflectivity in the embodiment. In order to ensure that the image processing method proposed in the embodiment is accurate and effective, it is limited in the embodiment that there must be a certain difference between any reflectivity corresponding to the first data and any reflectivity corresponding to the second data, so as to ensure that there is a difference between the pixel values of the first data and the second data, which can effectively distinguish the high reflectivity region and the low reflectivity region.

[0086] In order to ensure that the processing method proposed in the embodiment is effective, the embodiment adds the following limitation conditions:

[0087] The difference between the minimum value of the reflectivity corresponding to the first data and the maximum value of the reflectivity corresponding to the second data is greater than the reflectivity threshold value; and / or the difference between the minimum value of the pixel value in the first data and the maximum value of the pixel value in the second data is greater than the pixel threshold value.

[0088] If the reflectivity is known, the difference between the minimum value of the reflectivity corresponding to the first data and the maximum value of the reflectivity corresponding to the second data is greater than the reflectivity threshold value, so as to be suitable for the processing method proposed in the embodiment.

[0089] Among them, the reflectivity threshold value is an empirical value; which is set according to the actual application requirement.

[0090] In addition, due to the difference in the received laser energy between the low reflectivity area and the high reflectivity area of the surface of the object to be measured, the light intensity reflected to the first sensor surface is also different, that is, the pixel values of different reflectivity areas in the light spot image collected by the first sensor are different.

[0091] If the pixel value of the laser light spot image is used as the screening condition of the first data and the second data, the first condition is that the pixel value is greater than the division threshold.

[0092] If the reflectivity is known, the first data and the second data can be further limited by pixel value on the basis of reflectivity screening.

[0093] Preferably, based on the acquired laser light spot image, the pixel value is used as the screening condition to determine the first data and the second data, specifically including: setting a division threshold, and using the pixel points with a pixel value greater than the division threshold in the laser light spot image as the first data; otherwise, as the second data.

[0094] The division threshold is used to distinguish the laser light spot image corresponding to the high reflectivity area and the low reflectivity area of the laser light spot image reflected by the surface of the object to be measured. The specific value of the division threshold can be set according to the actual situation, and the application does not limit the specific value.

[0095] Preferably, the division threshold can be the average of the pixel values of the light spot images corresponding to the high reflectivity area and the low reflectivity area.

[0096] Preferably, based on the acquired laser light spot image, the pixel value is used as the screening condition to determine the first data and the second data, further including:

[0097] If the reflectivity of the surface of the object to be measured is unknown, the laser light spot image reflected by the surface of the object to be measured can be divided into several regions of equal size, a division threshold is set, and the pixel values of each region are compared with the size of the division threshold one by one. If the number of pixel points with a pixel value greater than the division threshold in the current region exceeds 50% of the total number of pixel points in the current region, the image data corresponding to the current region is selected as the first data; or only the image data corresponding to the pixel points with a pixel value greater than the division threshold in the current region is selected as the first data (i.e. both the number and the pixel value meet the two conditions).

[0098] Among them, the size of the several regions divided by the laser light spot image is smaller than the size of any reflectivity area, so as to ensure that the pixel value screening of each reflectivity area can apply the above screening condition.

[0099] In addition, the number limit condition 50% is only an example, and other values can be set according to the specific distribution of the pixel value in the current laser light spot image.

[0100] The screening method of the first data and the second data can be one of the above or any combination thereof, or other methods, according to actual application requirements.

[0101] Preferably, only part of the image data meeting the conditions can be selected to form the first data and the second data, respectively.

[0102] In the determination method of the first data and the second data, the difference between the minimum value of the pixel value in the first data and the maximum value of the pixel value in the second data is greater than a pixel threshold value, so as to be suitable for the processing method proposed in the embodiment.

[0103] The pixel threshold value is an empirical value and is set according to actual application requirements.

[0104] Since there are at least two regions with different reflectivities on the surface of the object to be measured, the microscopic automatic focusing system cannot achieve accurate focusing. Therefore, in order to achieve focusing control on the surface of the object to be measured, the effective exposure conditions corresponding to different reflectivity regions should be analyzed, that is, under the effective exposure condition corresponding to any reflectivity, the light spot in the light spot image reflected by the reflectivity region is clear. In this way, accurate focusing of any reflectivity region can be achieved, or based on the exposure parameter analysis under the above appropriate conditions, a balanced condition can be obtained to achieve accurate focusing on the surface of the object to be measured.

[0105] Based on the first data and the second data, the first pixel range and the second pixel range meeting the imaging requirements are screened; the imaging requirements are that there are light spots in the laser light spot image corresponding to the first data and in the laser light spot image corresponding to the second data.

[0106] The pixel ranges in the first data and the second data meeting the imaging requirements are screened respectively, and the laser energy range corresponding to the pixel range meeting the imaging requirements is taken as the effective exposure condition. The imaging requirements are that there are light spots in the laser light spot image corresponding to the first data and in the laser light spot image corresponding to the second data.

[0107] The laser energy range corresponding to the first and second pixel ranges is taken as the effective exposure condition.

[0108] In the laser light spot image, the pixel value increases with the increase of the laser energy.

[0109] Since the photosensitivity of the high-reflectivity region is high, with the increase of the laser energy, the pixel value of the laser light spot image corresponding to the region rises rapidly, and it is easy to reach the pixel upper limit (for example, the pixel upper limit is 255 for an 8-bit image), so the light spot image of the region is overexposed; the light spot image corresponding to the increased laser energy is also overexposed, and neither of them meets the imaging requirements.

[0110] The pixel upper limit is the maximum value of the image data value range. Taking 8-bit image data as an example, the value range is [0, 255], and the maximum value of the 8-bit image data value range is 255, that is, the pixel upper limit is 255.

[0111] Due to the low photosensitivity of the low reflectivity area, with the increase of the laser energy, the pixel value of the laser spot image corresponding to the area rises slowly, and in a certain energy range of the laser spot image, the pixel value may not change or the spot may not appear all the time. Therefore, the laser spot image in the energy range does not meet the imaging requirement.

[0112] Therefore, under the same laser energy, the spot image reflected by the surface of the high reflectivity area and the spot image reflected by the surface of the low reflectivity area may present different visual effects. In order to obtain the spot in the spot image reflected by the surface of the high reflectivity area and the spot in the spot image reflected by the surface of the low reflectivity area, it is necessary to obtain the effective exposure condition for the spot in the spot image reflected by the surface of the high reflectivity area and the effective exposure condition for the spot in the spot image reflected by the surface of the low reflectivity area.

[0113] Due to the difference in sensitivity of different reflectivity areas to light intensity, under the effective exposure condition for the spot in the spot image reflected by the surface of the high reflectivity area, there may be no spot (there may be pixel data but no spot, not no pixel data) or weak spot in the spot image reflected by the surface of the low reflectivity area. Similarly, under the effective exposure condition for the spot in the spot image reflected by the surface of the low reflectivity area, the spot image reflected by the surface of the high reflectivity area may be overexposed or underexposed.

[0114] Based on the analysis of the existence of the spot in the spot image reflected by the surface of the low reflectivity area and the high reflectivity area, the pixel value is taken as the screening condition to obtain the effective exposure condition corresponding to the existence of the spot in the spot image reflected by the surface of the low reflectivity area and the high reflectivity area.

[0115] The pixel range meeting the imaging requirement in the first data and the second data is screened respectively, and the effective exposure condition meeting the imaging requirement is screened based on the laser energy range corresponding to the first data and the second data.

[0116] The imaging requirement is that there is a spot in the laser spot image corresponding to the first data and there is a spot in the laser spot image corresponding to the second data.

[0117] In order to further exclude the image data in the first data and the second data that does not meet the imaging requirement, the embodiment screens the pixel range of the first data and the second data meeting the imaging requirement by analyzing the pixel change process.

[0118] Based on the difference in sensitivity of different reflectivities to light and the change process of pixel values in the laser spot image, the embodiment determines the pixel range meeting the imaging requirement by analyzing the overexposed image data in the first data and the second data.

[0119] The pixel range meeting the imaging requirement includes a first pixel range and a second pixel range. The first pixel range corresponds to a first energy range, and the second pixel range corresponds to a second energy range.

[0120] The embodiment sets a first threshold value for screening the overexposed image data. Taking 8-bit image data as an example, the first threshold value can be 255, 250, or any other value, which is set according to actual requirements.

[0121] According to the analysis process of the pixel range meeting the imaging requirement in the first data and the second data, and in combination with the light sensitivity of different reflectivities, the effective exposure condition meeting the imaging requirement can be determined.

[0122] The effective exposure condition includes the first energy range corresponding to the first pixel range and the second energy range corresponding to the second pixel range. The minimum value of the laser energy in the second energy range is greater than the maximum value of the laser energy in the first energy range.

[0123] In the laser spot image meeting the imaging requirement corresponding to the first energy range, the laser spot image corresponding to the high-reflectivity region on the surface of the object to be measured exists. The overexposed data in the first data is preferentially excluded, that is, the pixel range with a pixel value less than the first threshold value in the first data exists in the image data.

[0124] In order to further determine the energy range in which the high-reflectivity region exists, according to the difference in sensitivity of different reflectivity regions to light intensity, in the energy range in which the high-reflectivity region exists, the low-reflectivity region can have no spot (may have pixel data but no spot, not no pixel data) or weak spot. In summary, in the energy range in which the high-reflectivity region exists, the energy range corresponding to the low-reflectivity region which can have no spot (may have pixel data but no spot, not no pixel data) or weak spot needs to be screened out as the first energy range.

[0125] Since the pixel value corresponding to the low-reflectivity region which can have no spot (may have pixel data but no spot, not no pixel data) or weak spot cannot be accurately obtained, the energy range corresponding thereto cannot be obtained. The embodiment considers that the low-reflectivity region needs to reach a certain exposure condition of laser energy to form a laser spot image. Therefore, in the energy range in which the high-reflectivity region exists, the energy range corresponding to the low-reflectivity region which does not form a laser spot image is excluded, and the first energy range can be obtained.

[0126] The low reflectivity region does not form a laser spot image, and the pixel value of the second data is zero. That is, in the energy range corresponding to the laser spot in the high reflectivity region, the energy range corresponding to the second data being zero is excluded to obtain the first energy range.

[0127] In the embodiment, the pixel value corresponding to the high reflectivity region is less than the first threshold value, and the corresponding energy range has been divided into the first energy range. Therefore, when the pixel value of the first data is equal to the energy value corresponding to the first threshold value, the pixel value of the second data is used as the second threshold value to divide the laser energy corresponding to the pixel value in the second data into the first energy range or the second energy range.

[0128] At this time, it can be concluded that the pixel range (i.e., the first pixel range) in the first data that meets the imaging requirements is the intersection of the pixel range in the first data whose pixel value is less than the first threshold value and the pixel range in the second data whose pixel value is greater than the second threshold value and less than the first threshold value. The laser energy range corresponding to the first pixel range is the first laser energy range.

[0129] The second threshold value is the pixel value of the second data corresponding to the laser energy value when the first data is equal to the first threshold value for the first time. Based on the second threshold value corresponding to the laser energy value of the second data, the laser energy range corresponding to the second data is divided into the first energy range or the second energy range.

[0130] In addition, since it is not clear whether there is a weak spot or no spot in the laser spot image formed by the low reflectivity region, in view of the second threshold value, the laser energy range corresponding to the pixel range less than the second threshold value in the second data has been divided into the first energy range.

[0131] The pixel range in the second data whose pixel value is greater than zero and less than the second threshold value is invalid data of the second data, i.e., the second invalid data. The first threshold value is greater than the second threshold value.

[0132] Therefore, the second data can be roughly divided by the second threshold value. The second data less than the second threshold value is roughly identified as the laser spot image corresponding to the low reflectivity region having pixel data but no spot (not no pixel data); the second data greater than the second threshold value is roughly identified as the laser spot image corresponding to the low reflectivity region having a spot.

[0133] In the second energy range corresponding to the laser spot image that meets the imaging requirements, the laser spot image corresponding to the low reflectivity region on the surface of the object to be measured has a spot, i.e., the image data corresponding to the second pixel range has a spot.

[0134] Similarly, in order to further determine the energy range corresponding to the presence of light spots in low reflectivity regions, based on the differences in sensitivity to light intensity among different reflectivity regions, high reflectivity regions may be overexposed within the energy range corresponding to the presence of light spots in low reflectivity regions. In summary, within the energy range corresponding to the presence of light spots in low reflectivity regions, it is necessary to select the energy range corresponding to the potential overexposure in high reflectivity regions as the second energy range.

[0135] The energy range that may be overexposed in high reflectivity areas corresponds to the laser energy range where the pixel value in the first data is not less than the first threshold.

[0136] At this point, the pixel range in the second data that meets the imaging requirements (i.e., the second pixel range) can be determined as the intersection of the pixel range in the second data whose pixel value is greater than the second threshold and less than the first threshold, and the pixel range in the first data whose pixel value is not less than the first threshold. Therefore, the laser energy range corresponding to the second pixel range is the second laser energy range.

[0137] Furthermore, this application does not limit the specific method of analyzing the pixel range and effective exposure conditions that meet the imaging requirements.

[0138] Based on the first and second data obtained by the above method, an array of pixel-energy values ​​is constructed. According to the first and second thresholds, the array that meets the conditions is selected, and then the pixel range and effective exposure conditions that meet the imaging requirements are determined.

[0139] Preferably, pixel value-energy value curves can be fitted to the first data and the second data respectively, so as to screen the pixel range and effective exposure conditions that meet the imaging requirements in a more intuitive way.

[0140] This embodiment uses curve fitting as an example to illustrate the analysis process of exposure conditions, as detailed below:

[0141] In this embodiment, starting from an initial energy value, multiple laser energy values ​​are set with equal increases. At each laser energy value, a microscopic autofocus system is used to enable the first sensor to acquire several laser spot images corresponding to the multiple laser energy values.

[0142] Based on the division threshold, the pixel values ​​of several laser spot images are compared one by one. Pixels with pixel values ​​greater than the division threshold are formed into the first data, and pixels with pixel values ​​less than the division threshold are formed into the second data.

[0143] like Figure 3 As shown, the laser energy-pixel value curves corresponding to the first and second data are fitted respectively. The pixel range that meets the imaging requirements is determined by the first and second thresholds. Based on the response relationship between reflectivity and light intensity, the first energy range and the second energy range are selected as effective exposure conditions.

[0144] Based on the pixel value and the corresponding laser energy value in the first data, the first laser energy-pixel value curve is fitted as f(i,j)=P0+a×ln(LE), which is used to represent the change relationship between the pixel value and the laser energy value in the laser spot image corresponding to the high reflectivity area.

[0145] In the formula, f(i,j) represents the pixel value of the pixel point (i,j); P0 is the minimum value of the pixel value in the first data; the first fitting coefficient a is obtained by fitting the pixel value and the corresponding laser energy value in the first data obtained by experiment; and LE is the laser energy value.

[0146] Based on the pixel value and the corresponding laser energy value in the second data, the second laser energy-pixel value curve is fitted as f(i,j)=P0+b×ln(LE), which is used to represent the change relationship between the pixel value and the laser energy value in the laser spot image corresponding to the low reflectivity area.

[0147] In the formula, f(i,j) represents the pixel value of the pixel point (i,j); the second fitting coefficient b is obtained by fitting the pixel value and the corresponding laser energy value in the second data obtained by experiment; LE is the laser energy value; and K is the minimum laser energy value corresponding to the minimum pixel value (greater than zero) in the second data.

[0148] Through the above fitting process, the curve graphs corresponding to the first data and the second data are obtained, which reflect the change process of the pixel value and the laser energy of different reflectivity areas in a more intuitive form, and embody the difference in the light intensity sensitivity of the first data and the second data.

[0149] Based on the above laser spot image processing method, the first energy range and the second energy range can be obtained, and according to the reflectivity of the surface of the current object to be measured, the applicable laser energy range can be determined, which is convenient for focus control of the surface of the single reflectivity object to be measured to obtain an image meeting the imaging requirements.

[0150] Or based on the obtained laser energy range, the corresponding laser spot image in the range is obtained to calculate the focus image of the surface of the object to be measured with multiple reflectivity areas, to calculate the effective data of the current laser spot image, and then calculate the defocus amount to realize automatic control.

[0151] As shown in Figure 4 Based on the above effective exposure condition acquisition process, the embodiment further screens the effective pixel ranges corresponding to the high reflectivity area and the low reflectivity area respectively to obtain the effective data of the laser spot image reflected by the surface of the object to be measured.

[0152] ​Based on the first pixel range, pixel values not greater than the first effective threshold are assigned a fixed value to form first effective data; based on the second pixel range, pixel values not less than the second effective threshold are assigned a fixed value to form second effective data; the maximum value of the first effective data and the second effective data in any pixel point is taken as the pixel value of the pixel point to obtain effective data.

[0153] The second effective threshold is less than the first effective threshold, and the fixed value is less than the current pixel value.

[0154] The first effective threshold is the maximum value of the pixel value in the second data corresponding to the first energy range; and the second effective threshold is the minimum value of the pixel value in the first data corresponding to the second energy range.

[0155] The embodiment is based on the above laser spot image processing method, and the first energy range and the second energy range are taken as examples to illustrate the automatic focusing process.

[0156] The above laser spot image processing method can obtain:

[0157] The pixel range (i.e. the first pixel range) in the first data that meets the imaging requirement is the intersection of the pixel range in the first data with a pixel value less than the first threshold and the pixel range in the second data with a pixel value greater than the second threshold and less than the first threshold.

[0158] The laser energy range corresponding to the first pixel range is the first laser energy range.

[0159] The pixel range (i.e. the second pixel range) in the second data that meets the imaging requirement is the intersection of the pixel range in the second data with a pixel value greater than the second threshold and less than the first threshold and the pixel range in the first data with a pixel value not less than the first threshold.

[0160] The laser energy range corresponding to the second pixel range is the second laser energy range.

[0161] The first threshold is used to screen the overexposed image data.

[0162] The second threshold is the pixel value corresponding to the second data under the laser energy value corresponding to the first time when the first data is equal to the first threshold. The first threshold is greater than the second threshold.

[0163] As can be seen from the above, the laser spot image (the first pixel range) corresponding to the first energy range simultaneously contains the first data and the second data. The laser spot image (the second pixel range) corresponding to the second energy range also simultaneously contains the first data and the second data.

[0164] To further obtain the effective image of the surface of the to-be-tested object, the first effective threshold is set in the embodiment to further exclude the pixel value range with poor performance in the first pixel range.

[0165] The first effective threshold is set according to the actual application scenario, and the embodiment does not limit the specific value.

[0166] The filtering condition is that the pixel value not greater than the first effective threshold Y1 is assigned to a fixed value h, the first effective threshold Y1 is the maximum value of the pixel value in the second data corresponding to the first energy range, and the fixed value is less than the current pixel value.

[0167] The first effective data formed after the assignment

[0168] Similarly, the second effective threshold is set in the embodiment to further remove the overexposed data of the first data in the second pixel range, so as to obtain the effective image of the surface of the to-be-tested object.

[0169] The second effective threshold is set according to the actual application scenario, and the embodiment does not limit the specific value.

[0170] In addition, to further exclude the pixel value range with poor performance in the second pixel range, only the pixel range with the pixel value of (255-Y2) to Y2 is filtered, and the original pixel value is retained.

[0171] The filtering condition is that the pixel value not less than the second effective threshold Y2 is assigned to a fixed value h, the second effective threshold is the minimum value of the pixel value in the first data corresponding to the second energy range, the fixed value is less than the current pixel value, and the second effective threshold is less than the first effective threshold.

[0172] The second effective data formed after the assignment

[0173] Based on the first effective data and the second effective data, the maximum value of the first effective data and the second effective data in any pixel point is taken as the pixel value of the pixel point, and the effective data C(i,j) is finally obtained.

[0174] C(i,j)=max(C1(i,j),C2(i,j))

[0175] The embodiment excludes the pixel value range with poor performance in the first pixel range according to the characteristics of the first data and the second data in the first pixel range and the second pixel range, forms the first effective data in the form of screening assignment, and at the same time, excludes the overexposure data corresponding to the high reflectivity area and the pixel value range with poor performance of part of pixels in the second pixel range, obtains the second effective data in the form of screening assignment, and fuses the first effective data and the second effective data to obtain the effective data, thereby solving the problem that the same laser energy cannot accurately obtain the spot image of the area with large reflectivity difference and avoiding the problem of overexposure or underexposure on the surface of the measured object.

[0176] As shown in Figure 5 , in addition to the above-mentioned calculation method of screening assignment, the pixel value corresponding to any laser energy value in the first energy range of any pixel point in the first data can be fused with the pixel value corresponding to any laser energy value in the second energy range of the pixel point to obtain the first fusion data; the pixel value corresponding to any laser energy value in the first energy range of any pixel point in the second data can be fused with the pixel value corresponding to any laser energy value in the second energy range of the pixel point to obtain the second fusion data; and the effective data is calculated based on the first fusion data and the second fusion data.

[0177] The laser energy value in the first energy range selected by the first data and the second data is the same, and the laser energy value in the second energy range selected by the first data and the second data is the same.

[0178] In the embodiment, the image data (the first data) corresponding to the high reflectivity area is fused, that is, the pixel point (i, j) is selected from the first data, the pixel value f(i, j) R1 corresponding to the laser energy value R1 in the first energy range of the pixel point is fused with the pixel value f(i, j) R2 corresponding to the laser energy value R2 in the second energy range of the pixel point to obtain the first fusion data F1(i, j).

[0179] In order to further obtain the effective image of the surface of the measured object, before the fusion calculation, the image data that may be overexposed is excluded from the pixel value corresponding to any laser energy value in the first energy range of any pixel point in the first data and the pixel value corresponding to any laser energy value in the second energy range of the pixel point to obtain the fusion data of the effective image.

[0180] The screening condition is that the fusion coefficient of the pixel value not greater than the first effective threshold Y1 in the image data corresponding to the first energy range in the first data is ; otherwise, the fusion coefficient of the pixel value greater than the first effective threshold Y1 is .

[0181] The first effective threshold is set according to an actual application scenario, and the embodiment does not limit a specific value.

[0182] Taking 8-bit image data as an example, the specific calculation manner of the first fusion data F1(i,j) is as follows:

[0183]

[0184] In the formula, the subscript R1 represents any laser energy value in the first energy range; R2 represents any laser energy value in the second energy range; f(i,j) is a pixel value of a pixel point (i,j) in a laser spot image, f(i,j) R1 is a pixel value of the pixel point (i,j) corresponding to R1, and f(i,j) R2 is a pixel value of the pixel point (i,j) corresponding to R1 in the laser spot image.

[0185] Similarly, image data (second data) corresponding to a low reflectivity area is fused, that is, a pixel point (i,j) is selected from the second data, a pixel value f(i,j) R1 of the pixel point corresponding to R1 in the first energy range is fused with a pixel value f(i,j) R2 of the pixel point corresponding to R2 in the second energy range to obtain second fusion data.

[0186] The energy value of the first energy range selected by the high reflectivity area and the low reflectivity area is R1, and the energy value of the second energy range is R2.

[0187] Similarly, for the second data, before the pixel value corresponding to any laser energy value in the first energy range of any pixel point is fused with the pixel value corresponding to any laser energy value in the second energy range of the pixel point, image data with an unobvious change in the pixel value or not showing a light spot is excluded to obtain fusion data of an effective image.

[0188] The screening condition is that, in the corresponding image data of the second pixel range in the second data, a fusion coefficient corresponding to a pixel value not less than the second effective threshold Y2 is ; otherwise, a fusion coefficient corresponding to a pixel value less than the first effective threshold Y1 is .

[0189] The second effective threshold is set according to an actual application scenario, and the embodiment does not limit a specific value.

[0190] Taking 8-bit image data as an example, the specific calculation manner of the second fusion data F2(i,j) is as follows:

[0191]

[0192] In the formula, the subscript R1 represents any laser energy value in the first energy range; R2 represents any laser energy value in the second energy range; f(i,j) is the pixel value of the pixel point (i,j) in the laser spot image, f(i,j) R1 is the pixel value of the pixel point (i,j) corresponding to R1, f(i,j) R2 is the pixel value of the pixel point (i,j) in the laser spot image corresponding to R1.

[0193] By analyzing the pixel range in the laser spot image corresponding to the first energy range and the second energy range respectively meeting the imaging requirements, the laser spot image corresponding to the high reflectivity region is fused and calculated to obtain the first fusion data, and the laser spot image corresponding to the low reflectivity region is fused and calculated to obtain the second fusion data.

[0194] Based on the first fusion data and the second fusion data, the effective data F(i,j)=F1(i,j)+F2(i,j) is finally obtained.

[0195] According to the characteristics of the first data and the second data, the pixel values corresponding to the laser energy values in the first energy range and the pixel values corresponding to the laser energy values in the second energy range in the first data are screened and fused and calculated to obtain the first fusion data corresponding to the high reflectivity region; similarly, the second data is screened to calculate the second fusion data corresponding to the low reflectivity region; and the first fusion data and the second fusion data are used to finally obtain the effective data, which solves the problem that the same laser energy cannot accurately obtain the spot image of the region with large reflectivity difference, and avoids the problem of overexposure or underexposure on the surface of the measured object.

[0196] As shown in Figure 6 Based on the above processing method, the application further provides an automatic focusing method, which comprises:

[0197] The effective data is obtained by using the above processing method.

[0198] Based on the effective data, the spot centroid of the effective data is calculated to obtain the defocus amount of the surface of the measured object, and automatic focusing is realized.

[0199] The centroid of the effective data is used as the centroid of the surface of the measured object to calculate the defocus amount of the surface of the measured object, which can accurately focus the surface of the measured object. The overexposure of the high reflectivity region and the underexposure of the low reflectivity region are effectively excluded, and the defocus amount calculation under different reflectivity regions is met.

[0200] Or the centroid of the low reflectivity region is calculated based on the first effective data, and the centroid of the high reflectivity region is calculated based on the second effective data, and the defocus amounts corresponding thereto are obtained respectively to realize the automatic focusing of the low reflectivity region or the high reflectivity region.

[0201] Based on the same inventive concept, the application also proposes a computer readable storage medium comprising a computer program, which, when executed by a processor, implements the method as described above.

[0202] The technical features of the above embodiments can be combined in any manner. To make the description concise, all possible combinations of the technical features in the above embodiments are not described, however, as long as the combinations of the technical features do not exist in contradiction, they shall be considered within the scope of the present disclosure.

[0203] The above embodiments are only used to illustrate the technical solutions of the present application, rather than limit the present application; even though the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still make modifications to the technical solutions recorded in the foregoing embodiments, or make equivalent replacements to some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method of processing a laser spot image, characterized by, The method comprises the following steps: acquiring a plurality of laser spot images under a plurality of exposure conditions corresponding to laser energy variables; the laser spot images are formed by reflection of a surface of a to-be-tested object, and the surface of the to-be-tested object has at least two regions with different reflectivities; taking image data of the laser spot image corresponding to the region with a reflectivity greater than a set value as first data, and taking image data of the laser spot image corresponding to the region with a reflectivity not greater than the set value as second data; and / or taking a pixel point with a pixel value greater than a division threshold in the laser spot image as the first data, and taking a pixel point with a pixel value not greater than the division threshold in the laser spot image as the second data; based on the first data and the second data, screening a first pixel range and a second pixel range that meet imaging requirements; the first pixel range is an intersection of a pixel range with a pixel value less than a first threshold in the first data and a pixel range with a pixel value greater than a second threshold and less than the first threshold in the second data; the second pixel range is an intersection of a pixel range with a pixel value greater than the second threshold and less than the first threshold in the second data and a pixel range with a pixel value not less than the first threshold in the first data; the first threshold is used for screening overexposed image data, and the second threshold is less than the first threshold; taking a laser energy range corresponding to the first pixel range and the second pixel range as an effective exposure condition.

2. The treatment method according to claim 1, characterized in that, The method further comprises the following steps: based on the first pixel range, assigning a pixel value not greater than a first effective threshold to a fixed value to form first effective data; based on the second pixel range, assigning a pixel value not less than a second effective threshold to a fixed value to form second effective data; taking a maximum value of the first effective data and the second effective data in any pixel point as a pixel value of the pixel point to obtain effective data; wherein the second effective threshold is less than the first effective threshold, and the fixed value is less than a current pixel value.

3. The treatment method of claim 1, wherein The method further comprises the following steps: fusing a pixel value corresponding to any laser energy value in a first energy range of any pixel point in the first data with a pixel value corresponding to any laser energy value in a second energy range of the pixel point to obtain first fused data; fusing a pixel value corresponding to any laser energy value in the first energy range of any pixel point in the second data with a pixel value corresponding to any laser energy value in the second energy range of the pixel point to obtain second fused data; calculating effective data based on the first fused data and the second fused data; wherein the first data and the second data have the same laser energy value in the first energy range and the same laser energy value in the second energy range; the laser energy range corresponding to the first pixel range is the first energy range, and the laser energy range corresponding to the second pixel range is the second energy range.

4. The treatment method according to claim 2 or 3, characterized in that, The method further comprises the following steps: a difference between a minimum value of the reflectivity corresponding to the first data and a maximum value of the reflectivity corresponding to the second data is greater than a reflectivity threshold; and / or a difference between a minimum value of the pixel value in the first data and a maximum value of the pixel value in the second data is greater than a pixel threshold.

5. The treatment method according to claim 2 or 3, characterized in that, The effective exposure condition comprises a first energy range corresponding to the first pixel range and a second energy range corresponding to the second pixel range; a minimum value of the laser energy in the second energy range is greater than a maximum value of the laser energy in the first energy range.

6. The treatment method according to claim 2 or 3, characterized in that, The second threshold value is a pixel value corresponding to the second data when the first data is equal to a laser energy value corresponding to the first threshold value for the first time.

7. The treatment method according to claim 2 or 3, characterized in that, Further comprising: Fitting laser energy-pixel value curves corresponding to the first data and the second data respectively, determining a pixel range meeting imaging requirements based on the first threshold value and the second threshold value, and screening the first energy range and the second energy range as effective exposure conditions based on a response relationship between reflectivity and light intensity.

8. An autofocusing method characterized by, Comprising: Obtaining effective data by using the processing method according to any one of claims 2-7; Calculating a light spot centroid of the effective data to obtain a defocus amount of the surface of the object to be measured, and realizing automatic focusing.

9. A computer readable storage medium comprising a computer program, characterized in that, The computer program, when executed by a processor, implements the processing method according to any one of claims 1-7 and / or the automatic focusing method according to claim 8.

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