Constructing method of light field distribution on exit pupil of confocal microscope system

Abstract

The present invention provides a method for constructing the light field distribution of the exit pupil plane of a confocal microscope system. By using geometric optics and reasonable mathematical approximation to analyze the information of the confocal microscope system parameters facing any two-dimensional tilt angle, the light field distribution of the exit pupil plane of the objective lens of the confocal microscope system is constructed, which not only avoids the complexity of the construction method based on diffraction theory and the huge amount of calculation when simulating the distribution, but also avoids the large error caused by approximating the reflected light as a circle in the construction method based on geometric optics, which cannot truly reflect the actual distribution. The method for constructing the light field distribution of the exit pupil plane of the confocal microscope system provided by the present invention takes into account the physical phenomena under actual conditions, and constructs the light field distribution of the exit pupil plane of the objective lens of the confocal microscope system that is more in line with the actual situation.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical detection, and in particular relates to a method for constructing light field distribution on an exit pupil surface of a confocal microscope system. Background Art

[0002] With the development of many modern scientific fields such as microelectronics manufacturing, industrial precision measurement, metallurgy materials, and biomedicine, the requirements for ultra-precision measurement of discontinuous surface profiles and three-dimensional microstructures are constantly increasing. However, due to the limitations of the diffraction limit of ordinary optical microscopes, it is difficult to meet the requirements of high-resolution measurement.

[0003] In the prior art, confocal microscopes or differential confocal microscope structures are commonly used to measure the surface to be measured. The confocal microscope adopts a conjugate structure of point detection and point illumination, and the two are conjugate pairs relative to the focal plane of the objective lens. During the scanning process of the microscope objective lens, only the light on the focal plane can pass through the detection pinhole. The light from the area outside the focal plane is defocused at the detection pinhole plane and cannot pass through the small hole. Changing the numerical aperture of the scanning objective lens and changing the wavelength of the light source can improve the measurement accuracy, but the improvement effect is limited. The differential confocal microscope structure can effectively reduce common mode noise and improve system accuracy. The differential confocal microscope uses the slope of the axial response curve to measure the surface profile, achieving a higher axial resolution.

[0004] However, when measuring surfaces using either a confocal microscope or a differential confocal microscope, if the optical axis is not perpendicular to the surface being measured, the system's sensitivity, resolution, and accuracy will be affected. If perpendicularity cannot be guaranteed, a maximum allowable angle within the lower accuracy limit should be set in advance to ensure that system accuracy is not affected by surface tilt.

[0005] There are two existing models for light field distribution in the exit pupil plane of microscope objectives used to measure inclined surfaces. The first, based on diffraction theory, is complex and computationally intensive to simulate. The second, based on geometric optics, is simpler and easier to implement, but it approximates the reflected light as a circle, leading to significant errors and failing to accurately reflect the actual distribution. Furthermore, it fails to account for ambient noise and speckle caused by the roughness of the surface being measured. Summary of the Invention

[0006] The purpose of the present invention is to overcome the defects of the prior art and to propose a method for constructing light field distribution on the exit pupil surface of a confocal microscope system.

[0007] To achieve the above objectives, the present invention adopts the following specific technical solutions:

[0008] The present invention provides a method for constructing a light field distribution on an exit pupil surface of a confocal microscope system, comprising the following steps:

[0009] The laser beam emitted by the laser light source in the confocal microscope system is incident on the point to be measured on the side surface through the objective lens and the aperture, and after being reflected by the point to be measured, a light field of the reflected beam is formed on the pupil plane of the objective lens;

[0010] Taking the point to be measured on the side surface as the origin, establish a spatial rectangular coordinate system O-xyz and obtain the normal vector of the point to be measured;

[0011] An arbitrary point on the normal vector of the point to be measured is taken as the first point, and the angle between the normal vector and the Z-axis direction of the coordinate axis is the first angle θ; the projection point of the first point on the xOy plane is taken as the second point, the origin and the second point form a first vector, and the angle between the first vector and the Y-axis direction of the coordinate axis on the xOy plane is the second angle φ; the angle between the central axis of the incident light beam incident on the point to be measured and the central axis of the reflected light beam after reflection from the point to be measured is the third angle α; the angle of the fourth angle θ0 is half of the third angle; the intersection point of the central axis of the incident light beam and the pupil plane is the third point; the intersection point of the central axis of the reflected light beam and the pupil plane is the fourth point; an arbitrary point on the aperture is taken as the fifth point; the projection point of the fifth point on the plane formed by the central axis of the incident light beam and the central axis of the reflected light beam is the sixth point, and the projection point of the sixth point on the line connecting the point to be measured and the fourth point is the seventh point; the light intensity of the reflected light beam decays to 1 / e of the central light intensity 2 The boundary lines of the radius at are respectively the first boundary line and the second boundary line; the sixth point and the seventh point form a second vector, and the point where the second vector intersects with the plane where the point to be measured and the second boundary line are located is the eighth point;

[0012] When θ=θ0 and φ=0, the light field in the plane formed by the fifth point, the sixth point, and the seventh point is the light intensity centered on the light intensity of the seventh point, and the light field is expressed as follows:

[0013]

[0014]

[0015] Where r represents the light intensity of the light beam emitted by the laser light source in the confocal microscope system, which decays to the central light intensity 1 / e 2 I0 represents the light intensity at the center of the light beam; |GL| represents the distance between the seventh point and the eighth point when θ=θ0, φ=0; I G represents the light intensity of the seventh point; x0 and y0 represent the abscissa and ordinate of the fifth point when θ=θ0 and φ=0, respectively;

[0016] The light intensity at the fifth point is expressed as formula (3):

[0017]

[0018]

[0019] Wherein, |AG| represents the distance between the fifth point and the seventh point when θ=θ0 and φ=0;

[0020] When θ=θ0, φ=φ0, the light intensity at the fifth point is expressed as formula (5):

[0021]

[0022] Wherein, φ0 represents an angle value that is not zero; x1 and y1 represent the abscissa and ordinate of the fifth point when θ=θ0 and φ=φ0, respectively;

[0023]

[0024]

[0025] |G1L1| represents the distance between the seventh point and the eighth point when θ=θ0, φ=φ0; |A1G1| represents the distance between the fifth point and the seventh point when θ=θ0, φ=φ0;

[0026] According to the light intensity obtained at the fifth point, information on the light field distribution on the exit pupil surface of the confocal microscope system is obtained.

[0027] Furthermore, after obtaining the light field distribution on the exit pupil plane of the confocal microscope system, the following steps are also included:

[0028] By adding at least one randomly distributed speckle signal to the exit pupil light field of the confocal microscope system, the obtained information of the exit pupil light field distribution of the confocal microscope system is optimized. The light intensity of the fifth point after optimization is expressed as formula (8):

[0029]

[0030] Among them, x2 and y2 respectively represent the horizontal and vertical coordinates of the fifth point after optimization when θ=θ0, φ=φ0; pixel_size represents the sampling interval of the image; P k represents the center position of the kth speckle k=1,2,…;dis(P k , B(x1,y1)) represents the center position P of the kth speckle k , the distance to the fifth point after optimization.

[0031] Furthermore, the amount of speckle added is: 10×(r / pixel_size) 2 .

[0032] Furthermore, the added speckle is a Gaussian distribution speckle.

[0033] The present invention can achieve the following technical effects:

[0034] The present invention analyzes the light path transmission of the confocal microscope system, thereby avoiding the complexity of the construction method based on diffraction theory and the huge amount of calculation when simulating the distribution, and also avoiding the situation in which the construction method based on geometric optics approximates the reflected light as a circle, causing large errors and failing to truly reflect the actual distribution. The method for constructing the exit pupil plane light field distribution of the confocal microscope system provided by the present invention takes into account the physical phenomena under actual conditions, and constructs the exit pupil plane light field distribution of the objective lens of the confocal microscope system that is more in line with the actual situation, so as to facilitate the analysis and processing of subsequent data. Under the premise of ensuring resolution and accuracy, even if the object to be measured has an arbitrary two-dimensional angle tilt, the exit pupil plane light field distribution of the objective lens of the confocal microscope system can be constructed, so that the exit pupil plane light field of the objective lens of the constructed confocal microscope system is closer to the actual system output response. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a schematic structural diagram of a confocal microscope system according to an embodiment of the present invention;

[0036] Figure 2 is a flow chart of a method for constructing light field distribution on the exit pupil plane of a confocal microscope system according to an embodiment of the present invention;

[0037] Figure 3 2. It is a schematic diagram of the principle of two-dimensional tilt angle measurement in the method for constructing light field distribution on the exit pupil plane of a confocal microscope system according to an embodiment of the present invention;

[0038] Figure 4 2 is a schematic diagram of the principle of a method for constructing light field distribution on the exit pupil plane of a confocal microscope system according to an embodiment of the present invention;

[0039] Figure 5 is a schematic diagram of a pupil plane light field distribution simulation constructed according to a method for constructing a confocal microscope system exit pupil plane light field distribution according to an embodiment of the present invention;

[0040] Figure 6 (a) and 6(b) are schematic diagrams comparing pupil plane light field distributions after adding speckles, constructed by the method for constructing exit pupil plane light field distribution of a confocal microscope system according to an embodiment of the present invention.

[0041] Reference numerals include:

[0042] 1. Laser light source, 2. Collimating lens, 3. Beam splitter, 4. Objective lens, 5. Object to be measured, 6. Focusing lens, 7. Pinhole, 8. Photodetector. DETAILED DESCRIPTION

[0043] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, identical modules are denoted by identical reference numerals. In the case of identical reference numerals, their names and functions are also identical. Therefore, their detailed description will not be repeated.

[0044] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0045] Figure 1 FIG. 4 shows a schematic structural diagram of a confocal microscope system according to an embodiment of the present invention. Figure 2 A flow chart of a method for constructing light field distribution on the exit pupil plane of a confocal microscope system according to an embodiment of the present invention is shown. Figure 3 A schematic diagram showing the principle of two-dimensional tilt angle measurement in the method for constructing light field distribution on the exit pupil plane of a confocal microscope system according to an embodiment of the present invention is shown. Figure 4 A schematic diagram showing the principle of a method for constructing light field distribution on the exit pupil plane of a confocal microscope system according to an embodiment of the present invention. Figure 5 A schematic diagram of a pupil plane light field distribution simulation constructed by the method for constructing a confocal microscope system exit pupil plane light field distribution according to an embodiment of the present invention is shown. Figure 6 (a) and 6(b) are schematic diagrams showing comparisons of pupil plane light field distributions after adding speckles, constructed by the method for constructing exit pupil plane light field distribution of a confocal microscope system according to an embodiment of the present invention.

[0046] The following combination Figure 1 The specific working mode of the confocal measurement system according to the embodiment of the present invention is described in detail:

[0047] The technical solution provided by the embodiment of the present invention can be applied to a confocal microscope system of any structure. The solution of the embodiment of the present invention is described in detail below in conjunction with the confocal microscope system in the prior art. Figure 1 As shown, the confocal microscope system is only for illustration, and the specific implementation is not limited thereto.

[0048] The laser beam emitted by the laser light source 1 in the confocal microscope system passes through the collimating lens 2, beam splitter 3, objective lens 4 and diaphragm in sequence and is incident on the point to be measured on the side surface to be measured. After being focused at the point to be measured, the beam is reflected by the point to be measured. After reflection, the beam is split by the diaphragm, objective lens 4 and beam splitter 3 in sequence. The reflected beam after splitting passes through the focusing lens 6 and pinhole 7 in sequence and is received by the photodetector 8. The diaphragm is not in the Figure 1When the surface of the object 5 to be measured is tilted and located at the focal length of the objective lens 4, a light field of the reflected light beam is formed on the pupil plane of the objective lens 4. The method for constructing the light field distribution on the exit pupil plane of the confocal microscope system provided in the embodiment of the present invention is designed to construct the light field distribution of the reflected light beam on the pupil plane of the objective lens 4.

[0049] The embodiment of the present invention provides a method for constructing the light field distribution of the exit pupil of a confocal microscope system, such as Figure 2 As shown, the specific steps include:

[0050] like Figure 3 and Figure 4 As shown, Figure 4 With the pupil plane as the boundary, the area above the pupil plane is the top view, and the area below the pupil plane is the front view. With the point to be measured on the side surface as the origin O, establish a spatial rectangular coordinate system O-xyz and obtain the normal vector of the point to be measured. Take any point on the normal vector of the point to be measured as the first point N, that is, the normal vector of the point to be measured is Normal vector The angle with the coordinate axis Z is the first angle θ, that is, and The angle between the directions is θ. The projection point of the first point N on the xOy plane is the second point M. The origin O and the second point M form a first vector. The first vector and The angle between the laser beam and the point to be measured is the second angle φ. and the central axis of the reflected light beam after being reflected from the point to be measured The angle between the first and second angles is the third angle α. The fourth angle θ0 is half of the third angle α. The central axis of the incident light beam The intersection point with the pupil plane is the third point O'; the central axis of the reflected light beam The intersection point with the pupil plane is the fourth point F. Any point on the aperture is taken as the fifth point A; the fifth point A is projected onto the central axis of the incident light beam. The projection point on is the sixth point A0, and the seventh point G is the sixth point A0 on Projection on. and Intersect at the eighth point L. and The light intensity of the reflected beam decays to 1 / e of the central light intensity 2 The distance from point O to point O' is the focal length f of the objective lens 4.

[0051] When θ=θ0, φ=0, the light field in the plane formed by point A, point A0 and point G conforms to the light intensity I at point G. GThe light field is the light field with the central light intensity, and the light field is expressed as formula (1) and formula (2):

[0052]

[0053]

[0054] Where r represents the light intensity of the light beam emitted by the laser light source 1 in the confocal microscope system, which decays to the central light intensity 1 / e 2 I0 represents the light intensity at the center of the beam; |GL| represents the distance from point G to point L when θ=θ0, φ=0, and is 1 / e 2 Gaussian distribution of radius, I G represents the light intensity of the seventh point; x0 and y0 represent the abscissa and ordinate of the fifth point A when θ=θ0 and φ=0, respectively;

[0055] The light intensity at the fifth point A is expressed as formula (3):

[0056]

[0057]

[0058] Wherein, |AG| represents the distance between the fifth point and the seventh point when θ=θ0 and φ=0;

[0059] When θ = θ0 and φ = φ0, it is equivalent to rotating the light spot in the pupil plane counterclockwise around point O by an angle of φ0 when θ = θ0 and φ = 0. That is, after point A(x0, y0) rotates counterclockwise around point O' by an angle of φ0, it is obtained as A1(x1, y1). The positions of A(x0, y0) and point A1(x1, y1) have the following relationship, which can be expressed as formula (5):

[0060]

[0061] Arranging formula (5), we can get formula (6):

[0062]

[0063] Substituting formula (6) into formula (1), we can obtain that when θ = θ0, φ = φ0, the light intensity at the fifth point A is expressed as formula (7):

[0064]

[0065] Wherein, φ0 represents an angle value that is not zero; x1 and y1 represent the abscissa and ordinate of the fifth point when θ=θ0 and φ=φ0, respectively;

[0066]

[0067] |G1L1| represents the distance between point G and point L when θ=θ0, φ=φ0; |A1G1| represents the distance between point A1 and point G1 when θ=θ0, φ=φ0.

[0068] The technical solution provided in the embodiment of the present invention is Figure 4 It can be seen that the plane formed by points A, A0, and G and the exit pupil plane overlap with each other, and the light intensities of the two planes at the overlap are consistent. In the embodiment of the present invention, point A is any point arbitrarily selected from the overlap, that is, point A can represent any point on the exit pupil plane. According to the above formula, the light intensity of the fifth point A at any tilt angle can be obtained, and then the information of the light field distribution on the exit pupil plane of the confocal microscope system can be obtained.

[0069] In the embodiment of the present invention, the confocal microscope system takes the following parameters as an example: the incident light beam 1 / e 2 The radius r is 3 mm, the aperture radius is 4 mm, the focal length f of the objective lens 4 is 9 mm, and the technical solution provided by the embodiment of the present invention is used to simulate the distribution of the reflected light field on the pupil surface. The simulation results are as follows: when θ = 11.3°, φ = 225°; when θ = 8°, φ = 270°; when θ = 11.3°, φ = 315°; when θ = 8°, φ = 180°; when θ = 0°, φ = 0°; when θ = 8°, φ = 0°; when θ = 11.3°, φ = 135°; when θ = 8°, φ = 90°; and when θ = 11.3°, φ = 45°. Figure 5 shown.

[0070] The embodiment of the present invention analyzes the light path transmission of the confocal microscopy system, thereby avoiding the complexity of the construction method based on diffraction theory and the huge amount of calculation when simulating distribution, and also avoiding the situation in which the construction method based on geometric optics approximates the reflected light as a circle, causing large errors and failing to truly reflect the actual distribution. The method for constructing the exit pupil plane light field distribution of the confocal microscopy system provided by the embodiment of the present invention takes into account the physical phenomena under actual conditions and constructs the exit pupil plane light field distribution of the objective lens 4 of the confocal microscopy system that is more in line with the actual situation, so as to facilitate the analysis and processing of subsequent data. Under the premise of ensuring resolution and accuracy, even if the object to be measured 5 has an arbitrary two-dimensional angle tilt, the exit pupil plane light field distribution of the objective lens 4 of the confocal microscopy system can be constructed, so that the exit pupil plane light field of the objective lens 4 of the constructed confocal microscopy system is closer to the actual system output response.

[0071] The embodiment of the present invention further provides a preferred method, which further includes the following steps after obtaining the light field distribution of the exit pupil plane of the confocal microscope system:

[0072] By adding at least one randomly distributed speckle signal to the exit pupil light field of the confocal microscope system, the obtained information of the exit pupil light field distribution of the confocal microscope system is optimized. The light intensity of the fifth point after optimization is expressed as formula (8):

[0073]

[0074] Where x2 and y2 represent the horizontal and vertical coordinates of the fifth point A2 after optimization when θ=θ0 and φ=φ0 respectively; pixel_size represents the sampling interval of the image; P k represents the center position of the kth speckle k=1, 2, ...; dis(P k , B(x1, y1)) represents the center position P of the kth speckle k , the distance to the optimized fifth point A2.

[0075] The embodiment of the present invention also provides a preferred method, the amount of speckle added is: 10×(r / pixel_size) 2 .

[0076] The embodiment of the present invention further provides a preferred manner, wherein the added speckle is Gaussian distributed speckle.

[0077] In the embodiment of the present invention, the confocal microscope system takes the following parameters as an example: the incident light beam 1 / e 2 The radius r is 3 mm, the aperture radius is 4 mm, the focal length f of the objective lens 4 is 9 mm, the tilt angle θ of the object 5 is 7°, φ is -45°, and the pixel_size is 7 μm. The light field distribution reflected from the pupil surface is constructed using the technical solution provided in the embodiment of the present invention. The comparison diagram of the constructed image and the experimental collected image is as follows: Figure 6 As shown, Figure 6 (a) is a rendering of the effect of the technical solution of the present invention. Figure 6 (b) is the experimental collection picture.

[0078] The technical solution provided by the embodiment of the present invention takes into account the ambient noise and the speckle phenomenon caused by the roughness of the measured surface, and by adding randomly generated speckles, more accurately constructs the distribution of the pupil plane reflected light field when two-dimensional tilt occurs.

[0079] The technical solution provided by the embodiment of the present invention constructs the light field distribution reflected from the pupil surface, and by analyzing the light field distribution, the energy loss of the reflected light beam can be calculated. The confocal microscope system takes the following parameters as an example: the incident light beam 1 / e 2 The radius r is 3 mm, the aperture radius is 4 mm, and the focal length f of the objective lens 4 is 9 mm. When the object 5 is tilted at an angle of θ = 0° and φ = 0°, the energy of the reflected light beam entering the aperture of the confocal microscope system is recorded as P0. The analysis results are shown in Table 1.

[0080] Table 1 Spot energy in pupil plane when tilted

[0081] θ Light spot energy in pupil plane 0° <![CDATA[100%×P0]]> 5.84° <![CDATA[90%×P0]]> 7.73° <![CDATA[80%×P0]]> 9.16° <![CDATA[70%×P0]]> 10.39° <![CDATA[60%×P0]]> 11.56° <![CDATA[50%×P0]]> 12.74° <![CDATA[40%×P0]]> 13.99° <![CDATA[30%×P0]]> 15.45° <![CDATA[20%×P0]]> 17.46° <![CDATA[10%×P0]]>

[0082] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0083] Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art may make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

[0084] The above specific embodiments of the present invention do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A method for constructing light field distribution on the exit pupil surface of a confocal microscope system, characterized in that: The following steps are involved: The laser beam emitted by the laser light source in the confocal microscope system is incident on the to-be-measured point of the to-be-measured object through the objective lens and the aperture, and after being reflected by the to-be-measured point, a light field of the reflected beam is formed on the pupil plane of the objective lens; Taking the point to be measured on the object to be measured as the origin, establish a spatial rectangular coordinate system O-xyz, and obtain the normal vector of the point to be measured; Any point on the normal vector of the point to be measured is taken as the first point, and the angle between the normal vector and the Z-axis direction of the coordinate axis is the first angle θ; the projection point of the first point on the xOy plane is taken as the second point, the origin and the second point form a first vector, and the angle between the first vector and the Y-axis direction of the coordinate axis on the xOy plane is the second angle φ; the angle between the central axis of the incident light beam incident on the point to be measured and the central axis of the reflected light beam after the point to be measured is the third angle α; the angle of the fourth angle θ0 is half of the third angle; the intersection point of the central axis of the incident light beam and the pupil plane is the third point; the intersection point of the central axis of the reflected light beam and the pupil plane is the fourth point; any point on the aperture is taken as the fifth point; the projection point of the fifth point on the plane formed by the central axis of the incident light beam and the central axis of the reflected light beam is the sixth point, and the projection point of the sixth point on the line connecting the point to be measured and the fourth point is the seventh point; the light intensity of the reflected light beam decays to 1 / e of the central light intensity 2 The boundary lines of the radius at are respectively the first boundary line and the second boundary line; the sixth point and the seventh point form a second vector, and the point where the second vector intersects with the plane where the point to be measured and the second boundary line are located is the eighth point; When θ=θ0, φ=0, the light field in the plane formed by the fifth point, the sixth point and the seventh point is the light intensity centered on the light intensity of the seventh point, and the light field is expressed as the following formula: Where r represents the light intensity of the light beam emitted by the laser light source in the confocal microscope system attenuated to the central light intensity 1 / e 2 I0 represents the light intensity at the center of the light beam; |GL| represents the distance between the seventh point and the eighth point when θ=θ0, φ=0; I G represents the light intensity of the seventh point; x0, y0 respectively represent the abscissa and ordinate of the fifth point when θ=θ0, φ=0; f represents the focal length of the objective lens; The light intensity at the fifth point is expressed as formula (3): Wherein, |AG| represents the distance between the fifth point and the seventh point when θ=θ0, φ=0; When θ=θ0, φ=φ0, the light intensity at the fifth point is expressed as formula (5): Wherein, φ0 represents an angle value that is not zero; x1 and y1 represent the abscissa and ordinate of the fifth point when θ=θ0, φ=φ0, respectively; |G1L1| represents the distance between the seventh point and the eighth point when θ=θ0, φ=φ0; |A1G1| represents the distance between the fifth point and the seventh point when θ=θ0, φ=φ0; According to the light intensity obtained at the fifth point, the information of light field distribution on the exit pupil surface of the confocal microscope system is obtained.

2. The construction method according to claim 1, characterized in that: After obtaining the light field distribution of the exit pupil of the confocal microscope system, the following steps are also included: By adding at least one randomly distributed speckle signal to the light field on the exit pupil of the confocal microscope system, the information on the light field distribution on the exit pupil of the confocal microscope system is optimized. The light intensity of the fifth point after optimization is expressed as formula (8): Where x2 and y2 represent the horizontal and vertical coordinates of the fifth point after optimization when θ=θ0, φ=φ0 respectively; pixel_size represents the sampling interval of the image; P k represents the center position of the kth speckle k=1,2,…;dis(P k , A2(x2,y2)) represents the center position P of the kth speckle k , the distance to the fifth point after optimization.

3. The construction method according to claim 2, characterized in that: The number of speckles added is: 10×(r / pixel_size) 2 .

4. The construction method according to claim 2, characterized in that: The added speckle is Gaussian distribution speckle.

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