High-resolution three-dimensional measurement system and method based on structured light and differential confocal technology

Abstract

The invention discloses a high-resolution three-dimensional measurement system and method based on structured light and a differential confocal technology, and belongs to the technical field of high-precision three-dimensional detection. The implementation method comprises the steps that 1, the light intensity of emergent laser is adjusted, an upper computer controls a controllable diaphragm to be closed, and a light beam does not enter a structured light illumination super-resolution imaging module; 2, opening a controllable diaphragm, enabling a light beam to enter a laser differential confocal scanning axial focus fixing module to realize axial nanoscale focus fixing of a focal plane, and obtaining height information of a sample; 3, enabling the light beam to enter a super-resolution imaging module to obtain a super-resolution light slice image with the defocused background removed, and achieving super-resolution imaging; and 4, designing a proper axial fixed-focus scanning track according to the characteristics of the sample, driving the XYZ displacement table to be matched with the PZT to realize axial fixed-focus scanning, and performing three-dimensional reconstruction according to the super-resolution image and the axial fixed-focus data to obtain the three-dimensional shape distribution of the sample. Compared with the prior art, the problem of high-efficiency morphology measurement of nanoscale three-dimensional resolution is solved.

Description

Technical Field

[0001] The invention relates to a high-resolution three-dimensional measurement system and method based on structured light and differential confocal technology, and belongs to the technical field of high-resolution three-dimensional shape measurement. Background Art

[0002] High-precision and fast three-dimensional surface morphology measurement plays an extremely important role in the fields of micro-electromechanical, optics, and microelectronics. The use of optical methods to image three-dimensional objects has the advantages of non-contact, fast, and high precision. They have been successfully applied to mechanical parts inspection, animal and plant fossil restoration, human body measurement, biomedical imaging, and other fields. With the development of industries such as machinery, electronics, optics, and materials, the requirements for surface geometry detection are becoming higher and higher. For example, the etching depth of grooves and the line width of exposure in the semiconductor manufacturing industry are all in the nanometer level. Usually, optical measurement merges the target and the background together and is recorded simultaneously by the human eye or camera equipment. This process compresses the target and the background into a two-dimensional intensity image, making it impossible to distinguish the two directly, and even affecting the resolution of the target. Naturally, in order for an optical microscope to obtain the ability of three-dimensional imaging, it is necessary to distinguish the target and background information, prevent the background light from participating, and form a high-resolution optical sectioning (optical sectioning) that only the target light contributes.

[0003] Structured light super-resolution imaging technology is widely used in three-dimensional surface imaging and surface measurement because it can achieve super-resolution imaging and has the advantages of fast imaging speed. However, this technology has the disadvantage of low axial (z) measurement accuracy. Laser scanning differential confocal microscopy measurement method has an axial measurement accuracy of nanometers, but the signal is acquired at a defocused position, the lateral (xy) resolution is low, and the measurement speed is slow because the laser scans point by point. High-efficiency three-dimensional morphology measurement method with nanometer resolution is still a problem that needs to be solved by current technology.

[0004] Therefore, how to achieve high-efficiency morphology measurement with nanoscale three-dimensional resolution has become an urgent problem to be solved. Summary of the invention

[0005] The purpose of the present invention is to solve the problem of high-efficiency morphology measurement with nanometer-level three-dimensional resolution, and to provide a high-efficiency and high-resolution three-dimensional measurement system and method based on structured light and differential confocal information fusion technology.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] The invention discloses a high-resolution three-dimensional measurement system based on structured light and differential confocal technology, comprising a laser, an attenuation plate, a beam splitter plate, a laser differential confocal scanning axial fixed focus module, and a structured light super-resolution imaging module.

[0008] The laser differential confocal scanning axial focusing module includes a first controllable aperture, a first reflector, a first beam expander, a first beam splitter prism, a second beam splitter prism, a PZT, an objective lens, a sample, an XYZ translation stage, a third beam splitter prism, a first lens, a first pinhole, a first detector, a fourth beam splitter prism, a second lens, a second pinhole, a second detector, a third lens, a third pinhole, and a third detector. The laser differential confocal scanning axial focusing module is used to solve the problem of insufficient axial precision in high-resolution three-dimensional measurement.

[0009] The first beam splitter prism and the fourth beam splitter prism are both 5:5 beam splitter prisms; the second beam splitter prism and the third beam splitter prism are 7:3 beam splitter prisms;

[0010] The structured light super-resolution imaging module includes a second controllable aperture, a second beam expander, a second reflector, a fifth beam splitter prism, a DMD, a fourth lens, a half-reflective half-mirror, a third reflector, a fifth lens, and a CCD. The structured light super-resolution imaging module is used to solve the problem of insufficient lateral accuracy of high-resolution three-dimensional measurement.

[0011] The fifth beam splitter prism is a 5:5 beam splitter prism;

[0012] The optical path is as follows: the laser emits a laser, the laser intensity is adjusted by attenuation through the attenuation plate, and the light beam is divided into reflected light and transmitted light through the beam splitter plate.

[0013] The reflected light enters the laser differential confocal scanning axial focusing module, and the first controllable aperture controls the on-off of the light beam, and expands the light beam through the first reflector, the first beam expander, transmits the light through the first beam splitter prism, reflects the light through the second beam splitter prism, and focuses the light beam on the sample after passing through the PZT and the objective lens. The PZT, the XYZ translation stage, the objective lens, and the sample cooperate to realize the laser differential focusing. The reflected and scattered light on the surface of the sample is collected by the objective lens and returns to the original path. After being reflected by the second beam splitter prism and the first beam splitter prism, the light beam is divided into two beams by the third beam splitter prism at a ratio of 7:3. 30% of the reflected light enters the first detector after passing through the first lens and the first pinhole, and 70% of the transmitted light is divided into two beams after semi-reflective and semi-transmissive beam splitting by the fourth beam splitter prism. The reflected light enters the second detector through the second lens and the second pinhole, and the transmitted light enters the third detector through the third lens and the third pinhole. The first detector is used to obtain the confocal signal u D The second detector is used to obtain the back focus signal +u D The third detector is used to obtain the front focus signal -u D .

[0014] The transmitted light enters the super-resolution imaging module, and the second controllable aperture controls the on-off of the light beam. The light beam is expanded by the second beam expander, reflected by the second reflector and the fifth beam splitter prism and enters the DMD micromirror area. The DMD is controlled by the host computer to perform spatial light modulation on the incident light to obtain the required structured light. The modulated structured light is emitted into the fifth beam splitter prism and transmitted out. The transmitted light is reflected by the fourth lens and the half-reflecting half-mirror, and then transmitted through the second beam splitter prism to converge on the front focal plane of the objective lens and then diverge into the pupil of the objective lens, forming structured light wide-field illumination on the rear focal plane of the objective lens. The super-resolution image of the sample surface is collected by the objective lens, and the image information is transmitted to the CCD through PZT, the second beam splitter prism, the half-reflecting half-mirror, the third reflector, and the fifth lens.

[0015] The high-resolution three-dimensional measurement method based on structured light and differential confocal technology for the above system includes the following steps:

[0016] Step 1: The laser output light is adjusted through the attenuation plate to adjust the output laser light intensity, and the host computer controls the controllable aperture to close, so that the light beam does not enter the structured light illumination super-resolution imaging module;

[0017] Step 2: The controllable aperture is opened, and the light beam enters the laser differential confocal scanning axial fixed focus module. After the incident light is focused on the sample by the objective lens, the detector obtains the sample before focus u- D After the focus u+ D The light intensity signal at the position is obtained by subtracting the pre-focus and post-focus signals to obtain a differential confocal signal, whose zero point position is the focal plane position, so as to achieve nanometer-level focusing on the focal plane axis and obtain the sample height information;

[0018] Step 3: The controllable aperture is closed, and the light beam does not enter the laser differential confocal scanning axial fixed focus module. The controllable aperture is opened, and the light beam enters the super-resolution imaging module. The incident light is modulated by the DMD to obtain a specific structured light field. The modulated spatial structured light field is projected onto the sample surface to excite the sample. The CCD is used to collect the light field signal with the structured light field distribution. Finally, the image is reconstructed according to the algorithm, and a super-resolution light slice image with the out-of-focus background removed can be obtained to achieve super-resolution imaging.

[0019] Step 4: Design a suitable axial fixed-focus scanning trajectory according to the sample characteristics, drive the XYZ translation stage and PZT to achieve axial fixed-focus scanning, and perform three-dimensional reconstruction based on the super-resolution image and axial fixed-focus data to obtain the three-dimensional morphological distribution of the sample.

[0020] Beneficial effects:

[0021] Compared with the prior art, it has the following beneficial effects:

[0022] 1. Structured light illumination can achieve super-resolution imaging and improve the lateral resolution of the 3D reconstruction system. It also has the advantages of fast imaging speed, high efficiency and low phototoxicity.

[0023] 2. The differential confocal axial focusing method takes advantage of the high sensitivity of differential confocal, which can achieve high-precision focusing and realize nanometer-level axial resolution of the 3D reconstruction system;

[0024] 3. The laser differential confocal scanning and focusing method has the advantages of fast data processing speed and high signal-to-noise ratio, which further improves the quality of three-dimensional shape measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic diagram of the device of the present invention;

[0026] Figure 2 is the differential confocal response curve;

[0027] Figure 3 This is the interface diagram of the system axial resolution 5nm test results;

[0028] Figure 4 This is a schematic diagram of the frequency expansion of structured light super-resolution;

[0029] Figure 5 Schematic diagram of high-precision three-dimensional morphological parameter measurement using structured light.

[0030] Among them, 1-laser, 2-attenuation plate, 3-beam splitter plate, 4-first controllable aperture, 5-first reflector, 6-first beam expander, 7-first beam splitter prism, 8-second beam splitter prism, 9-PZT, 10-objective lens, 11-sample, 12-XYZ translation stage, 13-third beam splitter prism, 14-first lens, 15-first pinhole, 16-first detector, 17-fourth beam splitter prism, 18-second lens, 19-second pinhole, 20-second detector, 21-third lens, 22-third pinhole, 23-third detector, 24-second controllable aperture, 25-second beam expander, 26-second reflector, 27-fifth beam splitter prism, 28-DMD, 29-fourth lens, 30-semi-reflective and semi-transparent mirror, 31-third reflector, 32-fifth lens, 33-CCD. DETAILED DESCRIPTION

[0031] In order to better illustrate the purpose and advantages of the present invention, the invention is further described below in conjunction with the accompanying drawings and embodiments. It should be noted that the implementation of the present invention is not limited to the following embodiments, and any form of modification or change made to the present invention will fall within the protection scope of the present invention.

[0032] Example

[0033] This embodiment is an illustration of the high-efficiency morphology measurement of a sample with nanometer-level three-dimensional resolution by integrating the stripe structured light illumination super-resolution imaging method with the laser differential confocal focusing technology.

[0034] like Figure 1 As shown, the high-resolution three-dimensional measurement system based on structured light and differential confocal technology disclosed in the present invention includes a laser 1, an attenuation plate 2, a beam splitter plate 3, a laser differential confocal point scanning axial fixed focus module, and a structured light illumination super-resolution imaging module.

[0035] The laser differential confocal scanning axial focusing module comprises a first controllable aperture 4, a first reflector 5, a first beam expander 6, a first beam splitter prism 7, a second beam splitter prism 8, a PZT 9, an objective lens 10, a sample 11, an XYZ translation stage 12, a third beam splitter prism 13, a first lens 14, a first pinhole 15, a first detector 16, a fourth beam splitter prism 17, a second lens 18, a second pinhole 19, a second detector 20, a third lens 21, a third pinhole 22, and a third detector 23. The laser differential confocal scanning axial focusing module is used to solve the problem of insufficient axial precision in high-resolution three-dimensional measurement.

[0036] The first beam splitter prism 7 and the fourth beam splitter prism 17 are both 5:5 beam splitter prisms; the second beam splitter prism 8 and the third beam splitter prism 13 are 7:3 beam splitter prisms;

[0037] The structured light illumination super-resolution imaging module includes a second controllable aperture 24, a second beam expander 25, a second reflector 26, a fifth beam splitter prism 27, a DMD 28, a fourth lens 29, a half-reflecting half-mirror 30, a third reflector 31, a fifth lens 32, and a CCD 33. The structured light illumination super-resolution imaging module is used to solve the problem of insufficient lateral accuracy of high-resolution three-dimensional measurement.

[0038] The fifth beam splitter prism 27 is a 5:5 beam splitter prism;

[0039] In the embodiment, the design of the super-resolution imaging module in the system is mainly applied to the DMD-modulated structured light illumination super-resolution imaging method, and appropriate changes need to be made when other super-resolution imaging technologies are used.

[0040] The optical path is as follows: laser 1 emits laser light, the laser intensity is adjusted by attenuation plate 2, and the light beam is divided into reflected light and transmitted light by beam splitting plate 3.

[0041] The reflected light enters the laser differential confocal scanning axial focusing module, and the first controllable aperture 4 controls the on-off of the light beam, and expands the light beam through the first reflector 5, the first beam expander 6, transmits the light through the first beam splitter prism 7, reflects the light through the second beam splitter prism 8, and focuses the light beam on the sample 11 after the PZT 9 and the objective lens 10. The PZT 9 and the XYZ translation stage 12 move the objective lens and the sample to achieve laser differential focusing. The reflected and scattered light on the surface of the sample is collected by the objective lens 10 and returns to the original path after being reflected by the second beam splitter prism 8 and the first beam splitter prism 10. After being reflected by the prism 7, the light beam is split into two beams by the third beam splitter prism 13 at a ratio of 7:3. 30% of the reflected light enters the first detector 16 after passing through the first lens 14 and the first pinhole 15, and 70% of the transmitted light is split into two beams after being semi-reflected and semi-transmitted by the fourth beam splitter prism 17. The reflected light enters the second detector 20 through the second lens 18 and the second pinhole 19, and the transmitted light enters the third detector 23 through the third lens 21 and the third pinhole 22. The first detector 16 is used to obtain the confocal signal u D The second detector 20 is used to obtain the back focus signal +u D The third detector 23 is used to obtain the front focus signal -u D .

[0042] The transmitted light enters the structured light illumination super-resolution imaging module, and the second controllable aperture 24 controls the on-off of the light beam. The light beam is expanded by the second beam expander 25, and reflected by the second reflector 26 and the fifth beam splitter prism 27 and enters the micromirror area of ​​DMD28. DMD28 is controlled by the host computer to perform spatial light modulation on the incident light to obtain the required structured light. The modulated structured light is emitted into the fifth beam splitter prism 27 and the transmitted light is emitted. The transmitted light is reflected by the fourth lens 29 and the half-reflecting half-mirror 30, and then transmitted through the second beam splitter prism 8 and converged on the front focal plane of the objective lens 10, and then diverged and entered the pupil of the objective lens 10, forming structured light wide-field illumination at the rear focal plane of the objective lens 10. The structured light illumination image of the sample surface is collected by the objective lens 10, and the image information is transmitted to CCD33 through PZT9, the second beam splitter prism 8, the half-reflecting half-mirror 30, the third reflector 31, and the fifth lens 32.

[0043] The high-efficiency and high-resolution three-dimensional measurement method based on structured light and differential confocal technology for the above system includes the following steps:

[0044] Step 1: The laser output light is adjusted through the attenuation plate to adjust the output laser light intensity, and the host computer controls the controllable aperture to close, so that the light beam does not enter the structured light illumination super-resolution imaging module;

[0045] In the embodiment, a 532nm continuous laser is selected as a common light source for the structured light illumination and laser differential confocal module. The laser emits light, and the output light intensity is adjusted by an attenuator. Then, the light is split by a spectroscopic plate. The transmitted light enters the structured light illumination super-resolution imaging module, and is controlled on and off by a controllable aperture 24. The reflected light enters the laser differential confocal axial fixed-focus scanning module, and is controlled on and off by a controllable aperture 4. Such a design can reduce the number of lasers, and the method of controlling the on and off of the aperture can reduce the damage caused by switching the laser.

[0046] Step 2: The controllable aperture is opened, and the light beam enters the laser differential confocal scanning axial fixed focus module. After the incident light is focused on the sample by the objective lens, the detector obtains the sample at the front focus u -D After the focus +D The light intensity signal at the position is obtained by subtracting the pre-focus and post-focus signals to obtain a differential confocal signal, whose zero point position is the focal plane position, so as to achieve nanometer-level focusing on the focal plane axis and obtain the sample height information;

[0047] In the embodiment, the controllable aperture 24 is closed, the controllable aperture 4 is opened, and the light beam enters the laser differential confocal scanning axial fixed focus module. The laser beam is reflected by the reflector 5, expanded by the beam expander 6, transmitted by the beam splitter prism 7, and reflected by the beam splitter prism 8, and then focused by the objective lens near the sample surface. The reflected and scattered signals on the sample surface are collected by the objective lens, reflected by the beam splitter prism 8 and the beam splitter prism 7 in the original light path to the beam splitter prism 17 for splitting. The reflected light enters the rear focus detector 20 through the lens 18 and the pinhole 19, and the transmitted light enters the front focus detector 23 through the lens 21 and the pinhole 22. The objective lens driver PZT drives the objective lens to perform scanning motion along the Z direction, and the light intensity signal is measured by recording the front focus and the back focus photoelectric detectors. The corresponding axial response curve can be obtained through the light intensity-displacement correspondence relationship, and the differential confocal axial response curve can be obtained by subtracting the front focus and the back focus signals, such as Figure 2 (a) is the differential confocal simulation curve and the system axial measurement curve Figure 2 (b) is the differential confocal axial response curve obtained by the system. The zero point position of the differential confocal is the focal plane position, which can achieve absolute tracking and focusing. The test result interface of the built system with an axial resolution of 5nm is shown in the figure. Figure 3 As shown, it is demonstrated that the system can achieve an axial resolution of 5 nm.

[0048] Benefiting from the precise focusing characteristics of the differential confocal optical path, this method not only improves the lateral resolution of the system and increases the axial resolution to the nanometer level, but also realizes focus tracking and anti-drift detection of large-scale samples under far-field conditions, thereby achieving high spatial resolution and high-efficiency super-resolution three-dimensional imaging.

[0049] Step 3: The controllable aperture is closed, and the light beam does not enter the laser differential confocal scanning axial fixed focus module. The controllable aperture is opened, and the light beam enters the structured light illumination super-resolution imaging module. The incident light is modulated by the DMD to obtain a specific structured light field. The modulated spatial structured light field is projected onto the sample surface to stimulate the sample. The CCD is used to collect the light field signal with the structured light field distribution. Finally, the image is reconstructed according to the algorithm, and a super-resolution light slice image with the out-of-focus background removed can be obtained, realizing structured light illumination super-resolution imaging.

[0050] In the embodiment, the controllable aperture 4 is closed and the controllable aperture 24 is opened, and the light beam enters the structured light illumination super-resolution imaging module. The transmitted light is expanded by the beam expander 25, reflected by the reflector 26 and the beam splitter prism 27, and enters the DMD photosensitive surface for spatial light modulation. In this embodiment, high spatial frequency sinusoidal stripe structured light is selected for illumination. The modulated stripes are projected by the DMD, transmitted by the beam splitter prism 27, converged by the lens 29, reflected by the beam splitter plate, transmitted by the beam splitter prism 8, and converged by the objective lens on the sample surface to realize structured light wide-field illumination. The high spatial frequency structured light and the sample form a low frequency image based on the moiré fringe principle. The image is collected by the objective lens, transmitted by the beam splitter prism 8 and the beam splitter plate, reflected by the reflector 31, and converged by the lens 32. It is collected and processed by the CCD33. In this embodiment, the structured light used is a spatial stripe light field, which moves at equal intervals of 2π / 3 in a direction perpendicular to itself within one cycle to achieve a three-step phase shift. The phase-shifted spatial stripe light field is projected onto the sample surface in turn to stimulate the sample. The CCD is used to collect nine light field signals with stripe light field distributions in different phases and stripe directions. Finally, the image is reconstructed according to the algorithm to obtain a super-resolution light slice image with the out-of-focus background removed, thereby achieving isotropic structured light super-resolution imaging. The principle of structured light super-resolution frequency expansion is as follows: Figure 4 shown.

[0051] Step 4: Design a suitable axial fixed-focus scanning trajectory according to the sample characteristics, drive the XYZ translation stage and PZT to achieve axial fixed-focus scanning, and perform three-dimensional reconstruction based on the super-resolution image and axial fixed-focus data to obtain the three-dimensional morphological distribution of the sample.

[0052] In the embodiment, a suitable reference plane is selected, and suitable axial and lateral stepping intervals and scanning ranges are set. The XYZ stage is driven to first perform lateral stepping, and then the PZT is driven to perform axial fixed focus scanning. After the focus is fixed, super-resolution imaging is performed, data is recorded, and the cycle is continued. After that, data processing is performed, and three-dimensional reconstruction is performed according to the focus position data of differential confocal. Figure 5 The schematic diagram of high-precision three-dimensional morphological parameter measurement using structured light is shown.

[0053] The specific description above further illustrates the purpose, technical solutions and beneficial effects of the invention in detail. It should be understood that the above is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. High-resolution 3D measurement system based on structured light and differential confocal technology, characterized by: It comprises a laser (1), an attenuation plate (2), a beam splitter plate (3), a laser differential confocal scanning axial focus module, and a structured light illumination super-resolution imaging module; The laser differential confocal scanning axial focusing module comprises a first controllable aperture (4), a first reflecting mirror (5), a first beam expander (6), a first beam splitter prism (7), a second beam splitter prism (8), a PZT (9), an objective lens (10), a sample (11), an XYZ translation stage (12), a third beam splitter prism (13), a first lens (14), a first pinhole (15), a first detector (16), a fourth beam splitter prism (17), a second lens (18), a second pinhole (19), a second detector (20), a third lens (21), a third pinhole (22), and a third detector (23); the laser differential confocal scanning axial focusing module is used to solve the problem of insufficient axial precision in high-resolution three-dimensional measurement; The first beam splitter prism (7) and the fourth beam splitter prism (17) are both 5:5 beam splitter prisms; the second beam splitter prism (8) and the third beam splitter prism (13) are 7:3 beam splitter prisms; The structured light illumination super-resolution imaging module comprises a second controllable aperture (24), a second beam expander (25), a second reflector (26), a fifth beam splitter prism (27), a DMD (28), a fourth lens (29), a half-reflective half-mirror (30), a third reflector (31), a fifth lens (32), and a CCD (33); the structured light illumination super-resolution imaging module is used to solve the problem of insufficient lateral accuracy of high-resolution three-dimensional measurement; The fifth beam splitter prism (27) is a 5:5 beam splitter prism; The optical path is as follows: a laser (1) emits laser light, the laser intensity is adjusted by an attenuation plate (2), and the light beam is divided into reflected light and transmitted light by a beam splitting plate (3); The reflected light enters the laser differential confocal scanning axial focusing module, and the first controllable aperture (4) controls the on and off of the light beam, and the light beam is expanded through the first reflector (5), the first beam expander (6), the first beam splitter prism (7), the second beam splitter prism (8), the PZT (9) and the objective lens (10), and then the light beam is focused on the sample (11). The PZT (9), the XYZ displacement stage (12) move the objective lens and the sample to achieve laser differential focusing. The reflected and scattered light on the surface of the sample is collected by the objective lens (10) and returns to the original path, is reflected by the second beam splitter prism (8), and the first beam splitter prism (10). After being reflected by a mirror (7), the light beam is split into two beams by a third beam splitter prism (13) at a ratio of 7:3, 30% of the reflected light enters a first detector (16) after passing through a first lens (14) and a first pinhole (15), and 70% of the transmitted light is split into two beams by a fourth beam splitter prism (17) for semi-reflective and semi-transmissive beam splitting, the reflected light enters a second detector (20) through a second lens (18) and a second pinhole (19), and the transmitted light enters a third detector (23) through a third lens (21) and a third pinhole (22); the first detector (16) is used to obtain a confocal signal u D The second detector (20) is used to obtain the back focus signal +u D The third detector (23) is used to obtain the front focus signal -u D ; The transmitted light enters the structured light illumination super-resolution imaging module, and the second controllable aperture (24) controls the on-off of the light beam. The light beam is expanded by the second beam expander (25), and is reflected by the second reflector (26) and the fifth beam splitter prism (27) and enters the micro-mirror area of ​​the DMD (28). The DMD (28) is controlled by the host computer to perform spatial light modulation on the incident light to obtain the required structured light. The modulated structured light is emitted into the fifth beam splitter prism (27) and transmitted. The transmitted light is transmitted through the fourth lens (29). ), after being reflected by the half-reflecting half-mirror (30), the light is transmitted through the second beam splitter prism (8) and converged on the front focal plane of the objective lens (10), and then diverges and enters the pupil of the objective lens (10), forming structured light wide-field illumination on the rear focal plane of the objective lens (10). The structured light illumination image on the surface of the sample is collected by the objective lens (10), and the image information is transmitted through the PZT (9), the second beam splitter prism (8), the half-reflecting half-mirror (30), the third reflector (31), and the fifth lens (32) to the CCD (33).

2. A high-resolution three-dimensional measurement method based on structured light and differential confocal technology for the above system, comprising the following steps: Step 1: The laser output light is adjusted through the attenuation plate to adjust the output laser light intensity, and the host computer controls the controllable aperture to close, so that the light beam does not enter the structured light illumination super-resolution imaging module; Step 2: The controllable aperture is opened, and the light beam enters the laser differential confocal scanning axial fixed focus module. After the incident light is focused on the sample by the objective lens, the detector obtains the sample before focus u- D After the focus u+ D The light intensity signal at the position is obtained by subtracting the pre-focus and post-focus signals to obtain a differential confocal signal, whose zero point position is the focal plane position, so as to achieve nanometer-level focusing on the focal plane axis and obtain the sample height information; Step 3: The controllable aperture is closed, and the light beam does not enter the laser differential confocal scanning axial fixed focus module. The controllable aperture is opened, and the light beam enters the super-resolution imaging module. The incident light is modulated by the DMD to obtain a specific structured light field. The modulated spatial structured light field is projected onto the sample surface to excite the sample. The CCD is used to collect the light field signal with the structured light field distribution. Finally, the image is reconstructed according to the algorithm, and a super-resolution light slice image with the out-of-focus background removed can be obtained to achieve super-resolution imaging. Step 4: Design a suitable axial fixed-focus scanning trajectory according to the sample characteristics, drive the XYZ translation stage and PZT to achieve axial fixed-focus scanning, and perform three-dimensional reconstruction based on the super-resolution image and axial fixed-focus data to obtain the three-dimensional morphological distribution of the sample.

Images