A differential confocal axial effective measurement region determination device, method and system

Abstract

This invention discloses a device, method, and system for determining the effective measurement area of ​​differential confocal axial measurement, relating to the field of confocal microscopy. The method includes: acquiring a surface image of the sample under test and a preset axial measurement range; extracting a standard measurement grayscale interval of the differential image according to the preset axial measurement range, and determining a first measurable grayscale interval of the pre-focus image and a second measurable grayscale interval of the post-focus image; removing image regions outside the standard measurement grayscale intervals in the differential image; performing an intersection operation on the first and second measurable grayscale intervals; filtering out invalid measurement regions in the removed differential image based on the intersection grayscale intervals, and using the effective measurement area in the removed differential image as the effective measurement area of ​​the differential confocal axial measurement method. The method of this invention can predict the effective measurement area of ​​the differential confocal axial measurement method, improving the data accuracy of the differential confocal axial measurement method in actual measurement processes.

Description

Technical Field

[0001] This invention relates to the field of confocal microscopy, and in particular to a device, method and system for determining the effective axial measurement area of ​​differential confocal microscopy. Background Technology

[0002] Since its inception in the last century, confocal microscopy has been widely applied in aerospace, biomedicine, and semiconductor chip industries due to its unique high contrast, high resolution, and excellent tomographic capabilities. However, traditional confocal microscopy is limited by the spatial conjugate relationship of its two pinholes. In two-dimensional imaging, it requires point-by-point scanning laterally. In three-dimensional measurement, it requires layer-by-layer scanning. Furthermore, its axial measurement accuracy is limited by the accuracy of the axial scanning step and peak extraction algorithm. To improve its axial measurement efficiency and accuracy, many scholars have proposed differential confocal axial measurement methods. However, these are all limited by their axial offset distance, thus restricting their axial measurement range. Moreover, due to the one-sidedness of the confocal axial light intensity response curve, there is a problem of axial position misjudgment in the axial differential measurement curve. Simultaneously, in micro / nano microscopy, it is often difficult to know the surface height information of the sample beforehand. Therefore, to ensure the data authenticity of the differential confocal measurement method in the actual measurement process, it is necessary to pre-determine the effective measurement area within its field of view. Thus, a method for pre-determining the effective measurement area within its field of view is urgently needed. Summary of the Invention

[0003] The purpose of this invention is to provide a device, method, and system for determining the effective measurement area of ​​a differential confocal axial measurement method.

[0004] To achieve the above objectives, the present invention provides the following solution:

[0005] A differential confocal axial effective measurement area determination device includes: an illumination unit, a collimating lens, a digital micromirror device, a beam splitter, a tube mirror, an objective lens, a carrier module, a focusing lens, a camera, and a host computer;

[0006] The illumination unit generates point illumination light; the point illumination light is incident on the collimating lens to generate a parallel beam; the parallel beam is incident on the digital micromirror device to generate a parallel light array, and is reflected to the beam-splitting lens; the parallel light array is reflected by the beam-splitting lens, and sequentially passes through the tube mirror and the objective lens to illuminate the sample on the sample carrier module, and is reflected back to the objective lens, the tube mirror and the beam-splitting lens, and transmitted through the beam-splitting lens to the focusing lens, and then converged by the focusing lens to the camera;

[0007] The camera is connected to the host computer, and the camera is used to acquire surface images of the sample under test and transmit the surface images to the host computer;

[0008] The host computer is used to extract the effective measurement area of ​​the differential confocal axial measurement method based on the surface image.

[0009] Optionally, the loading module is a three-dimensional motion loading stage.

[0010] A method for determining the effective axial measurement region of a differential confocal lens, wherein the method is applied to the aforementioned device for determining the effective axial measurement region of a differential confocal lens, and the method includes:

[0011] Acquire a surface image of the sample under test and a preset axial measurement range; the surface image includes a pre-focus image and a post-focus image;

[0012] Based on the preset axial measurement range, using the formula Extract the standard measurement grayscale range of the differential image; where I represents the grayscale value and u represents the axial position; the differential image is a grayscale difference image obtained by subtracting the grayscale value of the back-focus image from the grayscale value of the foreground image;

[0013] The image regions outside the standard measurement grayscale range in the differential image are removed to obtain the removed differential image; the removed differential image includes valid measurement regions and invalid measurement regions;

[0014] Based on the preset axial measurement range, the first measurable grayscale range of the pre-focus image and the second measurable grayscale range of the post-focus image are determined;

[0015] The intersection of the first measurable grayscale range and the second measurable grayscale range is obtained by performing an intersection operation.

[0016] Based on the intersection grayscale range, invalid measurement regions in the eliminated differential image are removed, and the valid measurement regions in the eliminated differential image are taken as the valid measurement regions of the differential confocal axial measurement method.

[0017] Optionally, the preset axial measurement range is determined according to the magnification of the objective lens.

[0018] Optionally, based on the preset axial measurement range, a first measurable grayscale range for the pre-focus image and a second measurable grayscale range for the post-focus image are determined, specifically including:

[0019] Extract the grayscale values ​​of the foreground image and the background image;

[0020] Based on the grayscale value and corresponding axial position of the front-focus image, plot the front-focus grayscale value-axial position curve;

[0021] Based on the grayscale value and corresponding axial position of the back-focused image, draw the back-focused grayscale value-axial position curve;

[0022] Based on the preset axial measurement range and the focal gray value-axial position curve, the first measurable gray range of the focal image is determined;

[0023] Based on the preset axial measurement range and the back-focus grayscale value-axial position curve, the second measurable grayscale range of the back-focus image is determined.

[0024] A differential confocal axial effective measurement area determination system includes:

[0025] The data acquisition module is used to acquire surface images of the sample under test and a preset axial measurement range; the surface images include pre-focus images and post-focus images;

[0026] The standard measurement grayscale range determination module is used to determine the grayscale range based on the preset axial measurement range using a formula. Extract the standard measurement grayscale range of the differential image; where I represents the grayscale value and u represents the axial position; the differential image is a grayscale difference image obtained by subtracting the grayscale value of the back-focus image from the grayscale value of the foreground image;

[0027] The first rejection module is used to reject image regions outside the standard measurement grayscale range in the differential image to obtain a rejected differential image; the rejected differential image includes valid measurement regions and invalid measurement regions;

[0028] Based on the preset axial measurement range, the first measurable grayscale range of the pre-focus image and the second measurable grayscale range of the post-focus image are determined;

[0029] The intersection operation module is used to perform an intersection operation on the first measurable grayscale range and the second measurable grayscale range to obtain the intersection grayscale range.

[0030] The second rejection module is used to reject invalid measurement areas in the rejected differential image based on the intersection grayscale range, and to take the valid measurement areas in the rejected differential image as the valid measurement areas of the differential confocal axial measurement method.

[0031] An electronic device includes a memory and a processor, wherein the memory stores a computer program, and the processor runs the computer program to enable the electronic device to perform the above-described differential confocal axial effective measurement area determination method.

[0032] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method for determining the effective measurement region of the differential confocal axis.

[0033] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0034] The differential confocal axial effective measurement area determination device, method, and system provided by this invention acquires a surface image of the sample under test and a preset axial measurement range; extracts a standard measurement grayscale interval from the differential image based on the preset axial measurement range, and determines a first measurable grayscale interval for the pre-focus image and a second measurable grayscale interval for the post-focus image; removes image areas outside the standard measurement grayscale intervals from the differential image; and filters out invalid measurement areas in the removed differential image based on the intersection of the first and second measurable grayscale intervals, using the effective measurement area in the removed differential image as the effective measurement area of ​​the differential confocal axial measurement method. The method of this invention can predict the effective measurement area of ​​the differential confocal axial measurement method, improving the data accuracy of the differential confocal axial measurement method in actual measurement processes. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 A schematic diagram of the differential confocal axial effective measurement area determination device provided by the present invention;

[0037] Figure 2 The flowchart of the differential confocal axial effective measurement area determination method provided by the present invention is as follows:

[0038] Figure 3 The confocal axial light intensity response curve provided by this invention;

[0039] Figure 4 The differential confocal axial light intensity response curve provided by this invention;

[0040] Figure 5 A schematic diagram of the dual-camera structure of the differential confocal axial effective measurement area determination system provided by the present invention;

[0041] Figure 6 The differential confocal axial effective measurement area determination system provided by the present invention uses a three-camera structure.

[0042] Symbol explanation:

[0043] 1. Illumination unit; 2. Collimating lens; 3. Digital micromirror device; 4. Beam splitter lens; 5. Tube lens; 6. Objective lens; 7. Object carrier module; 8. Focusing lens; 9. Camera; 10. Host computer; 11. Second beam splitter lens; 12. Second focusing lens; 13. Second camera; 14. Third beam splitter lens; 15. Third focusing lens; 16. Third camera. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] The purpose of this invention is to provide a device, method, and system for determining the effective measurement area of ​​a differential confocal axial measurement method.

[0046] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0047] Example 1

[0048] like Figure 1 As shown, the differential confocal axial effective measurement area determination device provided by the present invention includes: an illumination unit 1, a collimating lens 2, a digital micromirror device 3, a beam splitter lens 4, a tube lens 5, an objective lens 6, a loading module 7, a focusing lens 8, a camera 9, and a host computer 10.

[0049] The illumination unit 1 generates point illumination light; the point illumination light is incident on the collimating lens 2 to generate a parallel beam; the parallel beam is incident on the digital micromirror device 3 to generate a parallel light array, and is reflected to the beam splitter lens 4; the parallel light array is reflected by the beam splitter lens 4, and sequentially passes through the tube mirror 5 and the objective lens 6 to illuminate the sample on the sample carrier module 7, and is reflected back to the objective lens 6, the tube mirror 5 and the beam splitter lens 4, and is transmitted through the beam splitter lens 4 to the focusing lens 8, and is converged by the focusing lens 8 to the camera 9.

[0050] In practical applications, the lighting unit includes a point light source to generate point illumination. The point illumination can be monochromatic light, polychromatic light, visible light, or invisible light.

[0051] The point illumination light is directed toward the collimating lens 2 and the digital micromirror device 3, which are on the same line, to generate a parallel light array.

[0052] The point illumination light passes sequentially through the collimating lens 2 and reaches the digital micromirror device 3. The resulting parallel light array is then reflected by the beam splitter 4, tube lens 5, and objective lens 6, illuminating the object carrier module 7. After being reflected by the object carrier module 7, the light passes through the beam splitter 4 again and is converged by the focusing lens 8 to the camera 9. The object carrier module 7, objective lens 6, tube lens 5, beam splitter 4, focusing lens 8, and camera 9 are parallel to each other and coaxially arranged.

[0053] The beam-splitting lens 4 can be a semi-transparent, semi-reflective lens, or a combination of a polarizer and a polarization beam splitter.

[0054] The loading module 7 is a three-dimensional motion loading stage, used to drive the sample under test to move in a two-dimensional plane or move in a three-dimensional space.

[0055] The camera 9 is connected to the host computer 10. The camera 9 is used to acquire surface images of the sample under test and transmit the surface images to the host computer 10. This invention can also use dual cameras and triple cameras, but this affects the image acquisition steps during the axial scanning process. Dual cameras can simultaneously acquire two images (pre-focus and post-focus), eliminating the need to control the stage to move axially separately to acquire pre-focus or post-focus images, thus improving the accuracy of acquiring pre-focus or post-focus images. Figure 5 As shown, the dual-camera system adds a second beam-splitting lens 11, a second focusing lens 12, and a second camera 13 to the single-camera system. The second beam-splitting lens 11 is positioned on the transmission path of the beam-splitting lens 4, the second focusing lens 12 is positioned on the reflection path of the second beam-splitting lens 11, and the second camera 13 is positioned on the output path of the second focusing lens 12. The second camera 13 is used to acquire the focal front image of the sample under test. The same principle applies to the three-camera system. Figure 6 As shown, the third beam splitter 14 is disposed between the beam splitter 4 and the second beam splitter 11, the third focusing lens 15 is disposed on the reflected light path of the third beam splitter 14, and the third camera 16 is disposed on the emitted light path of the third focusing lens 15.

[0056] The host computer 10 is used to extract the effective measurement area of ​​the differential confocal axial measurement method based on the surface image.

[0057] Example 2

[0058] To achieve the corresponding functions and technical effects of Embodiment 1, a method for determining the effective measurement area of ​​the differential confocal axis is provided below. This method is applied to the device for determining the effective measurement area of ​​the differential confocal axis in Embodiment 1. Figure 2As shown, the method for determining the effective measurement area of ​​the differential confocal axis includes:

[0059] Step 201: Acquire a surface image of the sample under test and a preset axial measurement range; the surface image includes a pre-focus image and a post-focus image. The preset axial measurement range is determined according to the magnification of the objective lens.

[0060] In practical applications, the host computer acquires the surface image of the sample being tested captured by the camera, and analyzes the acquired surface image to determine the effective axial measurement area.

[0061] The process of acquiring surface information (surface image) of the object under test is as follows:

[0062] The point illumination emits a single beam of light, which passes through a collimating lens to reach the digital micromirror device (DMM). The DMM modulates the single beam of light into a parallel light array. The parallel light array is then fed back through a beam splitter lens, a tube lens, and then converged by the objective lens onto the surface of the sample under test. After being reflected by the surface of the sample, the light passes through the objective lens, tube lens, beam splitter lens, and is then converged by the focusing lens into the camera. The stage (object carrier module) moves the object up and down along the axial direction to acquire surface images at different axial positions.

[0063] Step 202: Based on the preset axial measurement range, use the formula Extract the standard measurement grayscale range of the differential image. Here, I represents the grayscale value, and u represents the axial position; the differential image is the grayscale difference image obtained by subtracting the grayscale value of the back-focus image from the grayscale value of the foreground image.

[0064] Step 203: Remove image regions outside the standard measurement grayscale range from the differential image to obtain the removed differential image; the removed differential image includes valid measurement regions and invalid measurement regions. In practical applications, the functional relationship between the axial position of the linear measurement segment in curve I(z) and the grayscale value is used, i.e. The differential image can be processed for the first effective measurement region determination, removing images that exceed the measurable grayscale range [I(z max ),I(z min Image area outside of )]

[0065] Step 204: Determine the first measurable grayscale range of the pre-focus image and the second measurable grayscale range of the post-focus image based on the preset axial measurement range.

[0066] As an optional implementation, step 204 specifically includes:

[0067] Extract the grayscale values ​​of the foreground image and the background image. In practical applications, the grayscale values ​​contained in the three acquired foreground / background and differential images each contain information about their axial positions.

[0068] Based on the grayscale value of the foreground image and its corresponding axial position, a grayscale value-axial position curve is plotted.

[0069] Based on the grayscale value of the back-focused image and the corresponding axial position, a grayscale value-axial position curve is plotted.

[0070] Based on the preset axial measurement range and the focal gray value-axial position curve, the first measurable gray range of the focal image is determined.

[0071] Based on the preset axial measurement range and the back-focus grayscale value-axial position curve, the second measurable grayscale range of the back-focus image is determined.

[0072] In practical applications, the axial positioning relationship between the pre-focus / back focus curves and the differential measurement curves can determine the grayscale range that can be accurately reproduced in the pre-focus / back focus intensity response curves. However, due to the one-sided symmetry of the confocal axial intensity response curves, there will be two solutions with different axial positions for the accurately reproduced grayscale values. Only one of these two solutions belongs to the truly measurable axial position.

[0073] Step 205: Perform an intersection operation on the first measurable grayscale range and the second measurable grayscale range to obtain the intersection grayscale range.

[0074] Step 206: Eliminate invalid measurement regions in the eliminated differential image based on the intersection grayscale range, and take the valid measurement regions in the eliminated differential image as the valid measurement regions of the differential confocal axial measurement method.

[0075] In practical applications, by establishing the correspondence between the reproducible grayscale ranges before and after focus and their axial positions, it can be determined that the actual measurable axial position before focus is the same as the actual measurable axial position after focus. Thus, the effective measurement area can be determined by intersecting the measurable grayscale ranges in the images before and after focus.

[0076] The host computer processes the surface image based on the following principle:

[0077] The principle of the differential confocal axial measurement method is based on the subtraction of two axially offset light intensity response curves. Therefore, due to the unilateral nature of the differential confocal axial light intensity response curve, light intensity values ​​other than the peak value will correspond to two different axial positions. For example... Figure 3 Z1 and Z2 are shown. Figure 3Midpoints P1' and P1" correspond to the gray values ​​of the pre-focus and post-focus axial light intensity response curves at Z1, respectively, and points P2' and P2" correspond to the gray values ​​of the pre-focus and post-focus axial light intensity response curves at Z2, respectively. Let the axial measurement range of the differential measurement curve (preset axial measurement range) be [z...]. min ,z max When Z1 is at the minimum value of the differential confocal axial measurement range (I(Z1)=I(u)), max This allows us to obtain the maximum reproducible grayscale value I(z) in the front-focus axial light intensity response curve. min When Z1 is at its maximum value within the differential confocal axial measurement range, the minimum grayscale value I(z) that can be accurately reproduced in the front-focus axial light intensity response curve can be obtained. max Since the axial offset between the pre-focus and post-focus curves and the reference focal plane is equal, the grayscale range that the post-focus axial light intensity response curve can accurately reproduce is consistent with that of the pre-focus axial light intensity response curve, both being [I(z...]. max ),I(z min )).

[0078] Based on the one-sided characteristics of the confocal axial light intensity response curve, it can be concluded that there are two intervals in the differential confocal axial light intensity response curve that are identical to the true reproduced grayscale range, such as... Figure 4 As shown. Figure 4 The medium-dark gray area represents the true measurement area (effective measurement area), while the light gray area represents the spurious measurement area (invalid measurement area). Therefore, let the maximum value of the front-focus axial light intensity response curve be related to I(z). min ) and I(z max The distances between z1 and z2 are given, and it can be concluded that there are two axial range solutions in the front focal axial light intensity response curve, [-z d -z2,-z d -z1] and [-z d +z1,-z d +z2]. Because the pre-focus / post-focus curves are symmetrical with respect to the reference plane, there are also two different solutions in the post-focus axial intensity response curve, [+z d -z2,+z d -z1] and [+z d +z1,+z d +z2]. From the axial positional relationship, we can obtain that, [-z d +z1,-z d +z2] and [+z d -z2,+z d -z1] represents the same axial interval. Therefore, by using the correspondence between the gray values ​​and axial positions in the differential measurement curve, the measurable gray value intervals in the fore-focus and post-focus areas are determined. Then, by performing the intersection operation of the fore-focus and post-focus image regions, the determination and separation of the effective measurement area of ​​the differential confocal axis are realized.

[0079] Existing differential confocal 3D measurement methods mostly focus on improving the measurement efficiency and accuracy of a single measurement range, lacking the ability to determine the validity of axial measurement data. This invention combines differential confocal axial measurement with differential tomography, proposing a system and method for determining the effective measurement area of ​​differential confocal axial measurement. By establishing the correspondence between the axial-grayscale values ​​of the differential confocal axial measurement curve and the pre-focus / post-focus axial response curve, the effective extraction of the differential confocal axial measurement area is achieved, ensuring the data authenticity of the differential confocal measurement method in actual measurement processes.

[0080] Example 3

[0081] In order to implement the method corresponding to Embodiment 1 above and achieve the corresponding functions and technical effects, a differential confocal axial effective measurement area determination system is provided below, including:

[0082] The data acquisition module is used to acquire surface images of the sample under test and a preset axial measurement range; the surface images include pre-focus images and post-focus images.

[0083] The standard measurement grayscale range determination module is used to determine the grayscale range based on the preset axial measurement range using a formula. Extract the standard measurement grayscale range of the differential image; where I represents the grayscale value and u represents the axial position; the differential image is a grayscale difference image obtained by subtracting the grayscale value of the back-focus image from the grayscale value of the foreground image.

[0084] The first rejection module is used to reject image regions outside the standard measurement grayscale range in the differential image to obtain a rejected differential image; the rejected differential image includes valid measurement regions and invalid measurement regions.

[0085] Based on the preset axial measurement range, the first measurable grayscale range of the pre-focus image and the second measurable grayscale range of the post-focus image are determined.

[0086] The intersection operation module is used to perform an intersection operation on the first measurable grayscale range and the second measurable grayscale range to obtain the intersection grayscale range.

[0087] The second rejection module is used to reject invalid measurement areas in the rejected differential image based on the intersection grayscale range, and to take the valid measurement areas in the rejected differential image as the valid measurement areas of the differential confocal axial measurement method.

[0088] Example 4

[0089] This embodiment provides an electronic device, including: a memory and a processor. The memory is used to store a computer program, and the processor runs the computer program to enable the electronic device to execute the differential confocal axial effective measurement area determination method of Embodiment 2.

[0090] Example 5

[0091] This embodiment provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the differential confocal axial effective measurement area determination method of Embodiment 2.

[0092] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to the method section.

[0093] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for determining the effective measurement area of ​​differential confocal axis, characterized in that, The differential confocal axial effective measurement area determination method is applied to the differential confocal axial effective measurement area determination device, and the differential confocal axial effective measurement area determination method includes: Acquire a surface image of the sample under test and a preset axial measurement range; the surface image includes a pre-focus image and a post-focus image; Based on the preset axial measurement range, using the formula Extract the standard measurement grayscale range of the differential image; where I represents the grayscale value and u represents the axial position; the differential image is a grayscale difference image obtained by subtracting the grayscale value of the back-focus image from the grayscale value of the foreground image; The image regions outside the standard measurement grayscale range in the differential image are removed to obtain the removed differential image; the removed differential image includes valid measurement regions and invalid measurement regions; Based on the preset axial measurement range, the first measurable grayscale range of the pre-focus image and the second measurable grayscale range of the post-focus image are determined; Based on the preset axial measurement range, the first measurable grayscale range of the pre-focus image and the second measurable grayscale range of the post-focus image are determined, specifically including: Extract the grayscale values ​​of the foreground image and the background image; Based on the grayscale value and corresponding axial position of the front-focus image, plot the front-focus grayscale value-axial position curve; Based on the grayscale value and corresponding axial position of the back-focused image, draw the back-focused grayscale value-axial position curve; Based on the preset axial measurement range and the focal gray value-axial position curve, the first measurable gray range of the focal image is determined; Based on the preset axial measurement range and the post-focus grayscale value-axial position curve, the second measurable grayscale range of the post-focus image is determined; The intersection of the first measurable grayscale range and the second measurable grayscale range is obtained by performing an intersection operation. Based on the intersection grayscale range, invalid measurement regions in the eliminated differential image are removed, and the valid measurement regions in the eliminated differential image are taken as the valid measurement regions of the differential confocal axial measurement method.

2. The method for determining the effective measurement area of ​​differential confocal axis according to claim 1, characterized in that, The differential confocal axial effective measurement area determination device includes: an illumination unit, a collimating lens, a digital micromirror device, a beam splitter, a tube mirror, an objective lens, a carrier module, a focusing lens, a camera, and a host computer; The illumination unit generates point illumination light; the point illumination light is incident on the collimating lens to generate a parallel beam; the parallel beam is incident on the digital micromirror device to generate a parallel light array, and is reflected to the beam-splitting lens; the parallel light array is reflected by the beam-splitting lens, and sequentially passes through the tube mirror and the objective lens to illuminate the sample on the sample carrier module, and is reflected back to the objective lens, the tube mirror and the beam-splitting lens, and transmitted through the beam-splitting lens to the focusing lens, and then converged by the focusing lens to the camera; The camera is connected to the host computer, and the camera is used to acquire surface images of the sample under test and transmit the surface images to the host computer; The host computer is used to extract the effective measurement area of ​​the differential confocal axial measurement method based on the surface image.

3. The method for determining the effective measurement area of ​​differential confocal axis according to claim 2, characterized in that, The loading module is a three-dimensional motion loading platform.

4. The method for determining the effective measurement area of ​​differential confocal axis according to claim 1, characterized in that, The preset axial measurement range is determined according to the magnification of the objective lens.

5. A differential confocal axial effective measurement area determination system, characterized in that, include: The data acquisition module is used to acquire surface images of the sample under test and a preset axial measurement range; the surface images include pre-focus images and post-focus images; The standard measurement grayscale range determination module is used to determine the grayscale range based on the preset axial measurement range using a formula. Extract the standard measurement grayscale range of the differential image; where I represents the grayscale value and u represents the axial position; the differential image is a grayscale difference image obtained by subtracting the grayscale value of the back-focus image from the grayscale value of the foreground image; The first rejection module is used to reject image regions outside the standard measurement grayscale range in the differential image to obtain a rejected differential image; the rejected differential image includes valid measurement regions and invalid measurement regions; Based on the preset axial measurement range, the first measurable grayscale range of the pre-focus image and the second measurable grayscale range of the post-focus image are determined; Based on the preset axial measurement range, the first measurable grayscale range of the pre-focus image and the second measurable grayscale range of the post-focus image are determined, specifically including: Extract the grayscale values ​​of the foreground image and the background image; Based on the grayscale value and corresponding axial position of the front-focus image, plot the front-focus grayscale value-axial position curve; Based on the grayscale value and corresponding axial position of the back-focused image, draw the back-focused grayscale value-axial position curve; Based on the preset axial measurement range and the focal gray value-axial position curve, the first measurable gray range of the focal image is determined; Based on the preset axial measurement range and the post-focus grayscale value-axial position curve, the second measurable grayscale range of the post-focus image is determined; The intersection operation module is used to perform an intersection operation on the first measurable grayscale range and the second measurable grayscale range to obtain the intersection grayscale range. The second rejection module is used to reject invalid measurement areas in the rejected differential image based on the intersection grayscale range, and to take the valid measurement areas in the rejected differential image as the valid measurement areas of the differential confocal axial measurement method.

6. An electronic device, characterized in that, include: A memory and a processor, wherein the memory is used to store a computer program, and the processor runs the computer program to cause the electronic device to perform the differential confocal axial effective measurement area determination method according to any one of claims 1-4.

7. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the differential confocal axial effective measurement region determination method according to any one of claims 1-4.

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