Laser experiment platform for in-situ photostimulation two-dimensional material of AFM (atomic force microscopy) and measurement method

Abstract

The invention relates to a laser experiment platform for an in-situ photostimulation two-dimensional material of an AFM and a measurement method, and the platform comprises a clamping mechanism which is used for clamping, positioning and clamping laser generators with different radiuses; the lens element is used for amplifying or reducing the light source by adjusting the distance between the two lens frames so as to adjust the size of a light spot; the reflecting element is positioned below the sample mounting position of the platform supporting element and is used for reflecting the light beam transmitted by the lens element to irradiate to the bottom of the sample and applying in-situ light stimulation to the sample in the AFM characterization process; the platform supporting element comprises a height adjusting type objective table and a shading box, the shading box is inserted into the height adjusting type objective table, the lens element is installed in a shading box body, and a lens can move front and back in a non-perforated area of the shading box body under the action of the operating rod. In-situ light stimulation in the AFM characterization process is achieved, and the device can adapt to laser generators of various sizes; the device is small in size, and the problem of insufficient space in the AFM characterization process is solved.

Description

Technical Field

[0001] This invention relates to the field of micro-nano measurement technology, specifically to a laser experimental platform and measurement method for in-situ light-stimulated two-dimensional materials for AFM. Background Technology

[0002] The discovery of graphene sparked a surge of research into 2D materials, but its zero band gap severely limits its applications in certain fields. 2D transition metal sulfides (TMDCs), represented by MoS2, possess unique band structures, semiconductor or superconducting properties, and excellent mechanical properties, making them promising candidates for applications in nanoelectronics and optoelectronics. This has attracted considerable interest from researchers and made them a hot topic in the field of low-dimensional functional materials research in recent years. Light, as a clean, safe, and controllable stimulus response signal, offers advantages such as non-contact operation, high sensitivity, and remote, precise manipulation. In recent years, the study of the photostimulation response of the interfacial properties of two-dimensional nanomaterials has been a key focus for researchers. How to combine experimental equipment, such as scanning electron microscopy (SEM) and atomic force microscopy (AFM), to more accurately obtain the photostimulation response characteristics of materials has become a pressing issue.

[0003] In their 2020 patent, "An Optical / Mechanical / Electrical Coupling Test Device and Test Method Based on an In-situ Mechanical Testing System for Scanning Electron Microscopy," Zheng Xuejun et al. proposed an in-situ optical, electrical, and mechanical coupling test device and method for scanning electron microscopes. This device introduces a light source into a vacuum chamber via optical fiber, focusing it on the tip of a probe. It allows for quantitative measurement of the influence of changes in force, electrical, and displacement parameters on the properties of nanomaterials at the same location under different wavelengths of laser light, achieving in-situ measurement of force, optical, and electrical coupling. This expands the functionality of the in-situ sample holder in scanning electron microscopes, truly reflecting the optical, mechanical, and electrical coupling properties of micro- and nano-sized semiconductor materials. However, the light source introduced through optical fiber has the following problems: 1. It is difficult to adjust the position and size of the incident light spot when the light source is introduced into the vacuum chamber through optical fiber. For samples with micro- and nano-sized dimensions, this method is defective in terms of accurately applying stimulation; 2. For AFM, insufficient space for oblique upward incident light will cause the incident light spot to be elliptical, which will affect the light power density and stimulation efficiency; 3. This design focuses the incident light source on the probe tip, while the AFM characterization process is carried out by collecting the laser reflected by the probe cantilever. Therefore, this design may affect the accuracy of the AFM characterization process.

[0004] In his 2025 publication, "Design of a Projection and Scanning Common-Path Emission Optical System Based on Liquid Lenses" (Infrared and Laser Engineering, 2025, 54(3):290-299), Xing Yulei designed a projection and scanning common-path emission optical system based on liquid lenses, aiming to solve the problems of complex calibration and large size of traditional discrete scanning and projection equipment. The system uses liquid lenses to replace the traditional mechanical structure, and achieves variable magnification beam expansion and dynamic focusing by adjusting the focal length of two liquid lenses, combining miniaturization and high precision. The system consists of a two-stage beam expansion structure: the first stage is a variable magnification beam expansion subsystem, which achieves beam expansion magnification adjustment through a combination of liquid lenses and compensation lenses; the second stage is a fixed magnification beam expansion subsystem, which further enhances the overall beam expansion capability. However, this design still has the following problems when applied to the AFM characterization process: 1. During the AFM characterization process, the sample moves with the stage, and the liquid lens may cause instability of the incident light source during this high-frequency vibration; 2. The AFM characterization process is extremely sensitive to temperature and humidity, and the use of liquid lenses poses a risk of leakage, affecting the AFM equipment and the characterization process; 3. As mentioned above regarding the vibration process, the scattering of the incident light source may also pose a hazard to the experimental personnel. Although liquid lenses are difficult to apply to the in-situ light-stimulated characterization process of AFM, their beam expansion and contraction principle still has reference value.

[0005] Existing in-situ optical equipment has a complex structure, which may affect the AFM characterization process or pose safety risks to the equipment and personnel, making it unsuitable for in-situ optical stimulation of two-dimensional materials during AFM characterization. This invention provides a novel laser platform with a small and simple laser clamping mechanism capable of holding various types of lasers. Combined with a Galilean lens module and control system, it can magnify or reduce the light source and illuminate a designated location. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, the purpose of this invention is to provide a laser experimental platform and measurement method for in-situ optical stimulation of two-dimensional materials for AFM. To address the problem of insufficient space for direct in-situ optical stimulation of the sample using an external light source during AFM characterization, this invention innovatively proposes a stimulation light source incident from the bottom of the sample.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a laser experimental platform for in-situ optical stimulation of two-dimensional materials for AFM, the experimental platform comprising: Clamping mechanism 1 is used to clamp and position laser generators of different radii; Lens element 2 is used to magnify or reduce the size of the light source by adjusting the distance between the two lens frames, so as to adjust the size of the light spot; Platform support element 3 is used to provide a suitable placement position for two-dimensional material samples for testing; The reflective element 4 is located below the sample mounting position of the platform support element. It is used to reflect the light beam transmitted by the lens element to illuminate the bottom of the sample and apply in-situ light stimulation to the sample during the AFM characterization process. The platform support components include: an adjustable stage 12 and a light-shielding box 5, the light-shielding box being inserted into the adjustable stage. The light shield box includes a flat rectangular light shield body and a connecting cylinder 17 for cooperating with the AFM worktable. An opening is provided on one side of the light shield box body as a light source inlet end 18. A number of symmetrical through holes are provided on the side wall of the light shield box body at the light source inlet end for fixing the clamps to the light shield box by clamping screws 9. The connecting cylinder 17 is connected to the bottom of the closed side of the light shield box body. The connecting cylinder 17 communicates with the interior of the light shield box body. An installation opening 15 is provided on the upper surface of the light shield box body above the connecting cylinder. An observation opening 16 is provided on the side of the light shield box body. An operating rod slide rail 24 is provided on the side of the light shield box body between the light source inlet end and the observation opening. The lens element 2 is installed inside the main body of the light shield 5, and can move the lens back and forth in the unopened area of ​​the main body of the light shield under the action of the operating lever. The reflective element includes several piezoelectric ceramic modules, a piezoelectric ceramic base plate 14, and a reflector platform 13. The piezoelectric ceramic base plate is fixed inside the connecting cylinder, and the piezoelectric ceramic modules are vertically installed on the upper surface of the piezoelectric ceramic base plate. All the piezoelectric ceramic modules together support the reflector platform. By controlling the voltage signal of each piezoelectric ceramic module, its length is adjusted to change the angle of the reflector platform 13, thereby controlling the position of the light source illuminating the sample.

[0008] Furthermore, the clamping mechanism 1 includes: a jaw 8, a clamping screw 9, an adjusting stud 10, and an M3 nut 11; the laser generator is clamped between two jaws, which are arranged opposite each other, and a V-groove is provided on the opposite side of the two jaws for clamping the laser generator. The two V-grooves clamp the front end of the laser generator. The rear end of each jaw is provided with upper and lower extension sections, and each extension section is provided with multiple through holes, and at least one through hole is a threaded through hole. The non-threaded through hole fixes the jaw to the front end of the light shield box 5 through the clamping screw 9 and the nut. The threaded through hole can adjust the distance between the two jaws by installing the adjusting screw 10 to accommodate laser generators of different sizes, and at the same time can adjust the center line of the laser generator and the lens element to coincide.

[0009] Furthermore, the clamping screw 9 is a stud with threads at both ends and a smooth middle section. During installation, the clamping claw is first placed into one side of the through hole of the light shield box, and then the clamping screw 9 is inserted into the hole through both sides symmetrically, and the M3 nut 11 is installed.

[0010] Furthermore, the lens element 2 includes a lens slide rail 6 and two lens frames 7 of the same specifications; the lens frames 7 can slide back and forth relative to the lens slide rail 6, and lenses are installed in the lens frames. The center height of the lenses in the two lens frames is the same. The distance between the two lenses can be adjusted by the lens slide rail, or lenses of the same size but different magnifications can be inserted into the lens frames. The magnification of the light source can be adjusted by adjusting the lens frames 7. Each lens frame is square in shape. A lens groove 19 for mounting the lens is set at the center of the square structure along the vertical direction. Symmetrical ears 21 are set on both sides of the square structure of the lens frame. The ears are used to slide and install the lens with the lens slide rail 6. One of the ears is equipped with an operating rod 23. The length of the operating rod can extend out of the operating rod slide rail 24 on the side of the light shield box. It cooperates with the operating rod slide rail on the side of the light shield box to adjust the distance between the lenses in real time.

[0011] Furthermore, the lens element 2 includes a beam expanding lens group and a beam contracting lens group. The beam from the beam expanding lens group is transmitted from the left to the right, and the light spot becomes larger, with a magnification of 1 to 2.5 times the radius of the laser generator's emission source. The beam from the beam contracting lens group is transmitted from the left to the right, and the light spot becomes smaller, with a magnification of 0.4 to 1 times the radius of the laser generator's emission source. When the two lenses in the beam expanding and contracting lens groups are attached together, the emitted light spot is the same as the laser generator's emission source, i.e., 1x zoom, with the side closer to the laser generator being the left.

[0012] Furthermore, when the distance between the two lenses is 50 mm, the radius of curvature of the left concave lens in the beam expanding lens group is 19.980 mm, and the radius of curvature of the right convex lens is 47.240 mm; the radius of curvature of the left convex lens in the beam contracting lens group is 50.328 mm, and the radius of curvature of the right concave lens is 23.068 mm.

[0013] Furthermore, the height-adjustable stage 4 is raised by 20 mm from the height of a general stage, so that a light-shielding box can be accommodated at the bottom.

[0014] Secondly, the present invention provides a method for measuring two-dimensional materials stimulated in situ by light for AFM. The method uses the laser experimental platform to perform in-situ light measurement, and the specific process is as follows: The first step is to determine the parameters of the selected lens, select the magnification to adjust the size of the light spot, slide the two lens frames 7 into the lens slide rail 6 and adjust the distance. The second step is to install the lens slide rail into the light shield box, place the clamp 8 at the light source inlet end 18 of the light shield box 5, and fix the clamp to the front of the light shield box. Then, install the emitting end of the laser generator between the two clamps. The third step is to screw the adjusting screw 10 into the threaded through hole of the two jaws, adjust the distance between the studs and fix the laser generator in place with the jaws, adjust the laser generator's emitting end axis to be installed at the same height as the center of the two lenses, and start the measurement. The fourth step is to control the voltage signal of each piezoelectric ceramic, change the length of multiple piezoelectric ceramic modules, and control the angle of the reflector platform 13 by adjusting the distance from each contact point of the reflector platform and the piezoelectric ceramic module to the piezoelectric ceramic base plate, so as to control the irradiation area.

[0015] The method uses four piezoelectric ceramic modules, which have the same amount of expansion and contraction with voltage changes. The piezoelectric ceramic modules can deform when the voltage changes, and the relationship between deformation and voltage is obtained. The four piezoelectric ceramic modules are controlled by a microcontroller to change to different lengths to obtain the desired angle of the reflector platform.

[0016] In the initial state, the reflector platform 13 is at a 45° angle, and the heights of each piezoelectric ceramic module are as follows: the front piezoelectric ceramic module is 14.14 mm high, the rear piezoelectric ceramic module is 26.14 mm high, and the two side piezoelectric ceramic modules are 20.14 mm high. The line connecting the front and rear piezoelectric ceramic modules coincides with the central axis of the light-shielding box.

[0017] Compared with the prior art, the beneficial effects of the present invention include: This invention utilizes a dedicated kit to achieve in-situ light stimulation during AFM characterization, making it compatible with laser generators of various sizes. The device is compact, solving the space constraints in AFM characterization. Operation is simple; after turning on the laser generator, only the distance between lenses and the angle of the reflector need to be adjusted. Maintenance costs are low, as each component is independently designed and replaceable. Manufacturing costs are low, allowing the use of various materials while maintaining strength. Personnel safety is ensured through a light-shielding box and clamping mechanism to guarantee the direction of the incident laser. The piezoelectric ceramic module can adjust the reflected light to a predetermined position, adjust the reflector angle, control the incident area, and recalibrate initial system errors.

[0018] This invention solves the problem of the inability to apply light from the bottom in the initial state of the device. It uses a Galilean lens module—composed of two lens frames—and optimizes the curvature to ensure that the two lenses output parallel light (not necessarily focused). The size of the light source can be controlled simply by changing the types of the beam expander and reducer lenses and adjusting the distance between them. Furthermore, the spot size can be adjusted in place during the experiment using the lens frame operating lever to match experimental requirements. While ensuring parallel beam propagation, it achieves arbitrary magnification or reduction, resulting in more uniform illumination of the sample. Attached Figure Description

[0019] Figure 1This is a schematic diagram of the overall structure of the laser experimental platform for in-situ photostimulation of two-dimensional materials for AFM according to the present invention; Figure 2 This is a schematic diagram of the components in the overall structure of the laser experimental platform for in-situ optical stimulation of two-dimensional materials for AFM according to the present invention; Figure 3 This is a half-section view of the laser experimental platform for in-situ photostimulation of two-dimensional materials for AFM according to the present invention. Figure 4 This is a schematic diagram of the three-dimensional structure of the light-shielding box of an embodiment of the laser experimental platform for in-situ photostimulation of two-dimensional materials for AFM according to the present invention; Figure 5 This is a schematic diagram of the gripper structure of one embodiment of the laser experimental platform for in-situ optical stimulation of two-dimensional materials for AFM according to the present invention; Figure 6 This is a schematic diagram of the height-adjustable stage of an embodiment of the laser experimental platform for in-situ optical stimulation of two-dimensional materials for AFM according to the present invention; Figure 7 This is a schematic diagram of the lens frame structure of one embodiment of the laser experimental platform for in-situ optical stimulation of two-dimensional materials for AFM according to the present invention; Figure 8 This is a schematic diagram of the lens slide rail structure of one embodiment of the laser experimental platform for in-situ optical stimulation of two-dimensional materials for AFM according to the present invention; Figure 9 This is a schematic diagram of the piezoelectric adjustable lens of one embodiment of the laser experimental platform for in-situ optical stimulation of two-dimensional materials for AFM according to the present invention; Figure 10 This is a three-dimensional structural schematic diagram of the clamping screw 9 of an embodiment of the laser experimental platform for in-situ photostimulation of two-dimensional materials for AFM according to the present invention; Figure 11 This is a schematic diagram of the adjusting screw 10 of an embodiment of the laser experimental platform for in-situ photostimulation of two-dimensional materials for AFM according to the present invention; Figure 12 This is a schematic diagram of the adjusting screw and Galilean beam expander in the laser experimental platform for in-situ optical stimulation of two-dimensional materials for AFM, as described in this invention. Figure 13 This is a schematic diagram of the adjusting screw and Galilean beam shrinking mirror in the laser experimental platform for in-situ optical stimulation of two-dimensional materials for AFM, as described in this invention. Reference numerals: 1 Clamping mechanism, 2 Lens element, 3 Platform support element, 4 Reflecting element, 5 Light shield, 6 Lens slide rail, 7 Lens frame, 8 Gripper, 9 Clamping screw, 10 Adjusting screw, 11 M3 nut, 12 Height-adjustable stage, 13 Reflector platform, 14 Piezoelectric ceramic base plate, 15 Mounting opening, 16 Observation opening, 17 Connecting cylinder, 18 Light source inlet, 19 Lens groove, 20 Arc, 21 Ear, 22 Groove, 23 Operating lever, 24 Operating lever slide rail. Detailed Implementation

[0020] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings, but this is not intended to limit the scope of protection of this application.

[0021] For ease of description, the laser experimental platform for in-situ optical stimulation of two-dimensional materials for AFM of the present invention will be referred to as the laser platform.

[0022] Example 1 The laser platform of this invention, as shown Figure 1 As shown, the system includes: a clamping mechanism 1, a lens element 2, a platform support element 3, and a reflecting element 4. The clamping mechanism adjusts the clamping distance via an adjusting screw 10 to clamp and position laser generators of different radii. The lens element 2 adjusts the distance between two lens frames on the lens slide rail 6 (manual adjustment of the distance between the two lens frames allows for adjustment of the spot size), enabling magnification and reduction of the light spot. The platform support element places the two-dimensional material sample in a suitable position. The reflecting element reflects the light beam passing through the lens element to the bottom of the sample, applying in-situ light stimulation to the sample during AFM characterization. The clamping mechanism 1, lens element 2, platform support element 3, and reflecting element 4 together form an overall coordinate system, improving measurement accuracy.

[0023] Platform support components 3, such as Figure 2 As shown, it includes: an adjustable stage 12 and a light-shielding box 5. The light-shielding box is inserted into the adjustable stage, and the two parts, when assembled, form a basic coordinate system, which provides a positioning reference for other parts.

[0024] The clamping mechanism is as follows Figure 2 As shown, it includes: gripper 8, clamping screw 9, adjusting screw 10, and M3 nut 11. These parts are installed on the light-shielding box 5, and the laser generator is held by the gripper 8.

[0025] like Figure 5The diagram shows the structure of a single gripper 8. A laser generator is held between two grippers, which are positioned opposite each other. V-grooves are provided on opposite sides of the grippers to hold the laser generator. The two V-grooves hold the front end of the laser generator. Each gripper has an upper and lower extension section at its rear end. Each extension section has multiple through holes, and at least one of the through holes is a threaded through hole. The non-threaded through holes are used to fix the grippers to the front end of the light shield box 5 by using a gripping screw 9 and an M3 nut 11. The threaded through holes can be adjusted by installing an adjusting screw 10 to adjust the distance between the two grippers to accommodate laser generators of different sizes, and can also be adjusted to ensure that the center line of the laser generator coincides with that of the lens element.

[0026] Clamping screw 9 Figure 10 As shown, both sides have M3 nominal threads with a depth of 15 mm, used to connect the light shield and the gripper.

[0027] Adjusting screw 10 Figure 11 As shown, the two ends are set with symmetrical depths and left and right spiral threads, similar to the principle of a compass, and the jaws can be adjusted in a 1:1 ratio.

[0028] The light-shielding box 5, as shown Figure 4 As shown, the device includes a flat, rectangular light-shielding body and a connecting cylinder 17 for mates with an AFM worktable. An opening on one side of the light-shielding body serves as a light source inlet 18. Symmetrical pairs of through holes are provided on the side wall of the light-shielding body at the light source inlet for mounting clamping screws 9. The connecting cylinder 17 is connected to the bottom of the closed side of the light-shielding body, communicating with the interior of the light-shielding body. An installation opening 15 is provided on the upper surface of the light-shielding body above the connecting cylinder. An observation opening 16 is provided on the side of the light-shielding body. An operating lever slide rail 24 is provided on the side of the light-shielding body between the light source inlet and the observation opening.

[0029] In this embodiment, the connecting cylinder 17 has a depth of 13 mm and a diameter of 38 mm. Its lower part mates with the central circular groove of the AFM worktable to determine the overall position of the laser experimental platform. A reflective element 4 is placed inside the connecting cylinder, and its installation height is sufficient to reflect the beam transmitted by the lens element. An observation opening 16 is provided on the side of the light-shielding box for placing signal lines and observing the internal structure. An installation opening 15 is used to place and fix the reflective element inside the connecting cylinder, ensuring the reflective element remains at a suitable height above the upper surface of the connecting cylinder. An operating rod slide rail 24 is provided on the side, with a soft light-shielding curtain installed inside, allowing the operating rod to extend from the light-shielding box and move freely. The light-shielding curtain closes after the operating rod has passed through, preventing light leakage and facilitating adjustment of the lens distance.

[0030] The rest of the main body of the light-shielding box is used to block light and protect personnel safety. The bottom end of the connecting cylinder is fitted with the piezoelectric ceramic base plate 14. The piezoelectric ceramic base plate 14 is placed at the bottom of the connecting cylinder and fixed by the connector.

[0031] The platform support element 3 is assembled with the light-shielding box 5. The platform support element 3 is located above the opening side of the light-shielding box 5, and a light-transmitting hole is provided on the platform support element 3. The test sample is installed at the position of the light-transmitting hole. The lens element 2 is installed inside the main body of the light-shielding box 5. Under the action of the operating rod, the lens can be moved back and forth in the unopened area of ​​the main body of the light-shielding box. The lens can be replaced and the distance between the lenses can be adjusted as needed, so that the laser held by the clamping mechanism 1 can accurately introduce the laser source at the bottom of the sample. The clamping mechanism 1 is installed on the light source inlet end 18 of the light-shielding box 5.

[0032] Lens element 2, such as Figure 3 As shown, it includes: two identical lens frames 7 and a lens slide rail 6. The lens frames 7 can slide back and forth relative to the lens slide rail 6. Lenses are installed inside the lens frames. The center height of the lenses (lenses) in the two lens frames is the same. The distance between the two lenses can be adjusted by the lens slide rail. Different lenses can also be inserted into the lens frames.

[0033] In this invention, the side where the laser generator is located is defined as the front, and the side where the reflective element is located is defined as the rear.

[0034] The lens frame 7 is as follows Figure 7 As shown, there are two lens frames 7, each holding two lenses. Each lens frame is square in shape, with a lens groove 19 for mounting the lens located at the center of the square structure along the vertical direction. Symmetrical ears 21 are provided on both sides of the square structure of the lens frame. The ears are used to slide and mount the lens with the lens slide rail 6. One ear is provided with an operating rod 23, the length of which can extend out of the operating rod slide rail 24 on the side of the light shield box, and cooperate with the operating rod slide rail on the side of the light shield box to adjust the distance between the lenses in real time.

[0035] In this embodiment, the length of the operating rod is 30 mm, the overall size of the square structure of the lens frame is 15.5 × 15.5 mm, the cross-sectional area of ​​the lens is 10 × 10 mm, the maximum thickness of the lens that can be used is 2 mm, and a 10 mm diameter arc 20 is provided in the lens slot 19 to fix a 10 mm lens. The arc in the two lens slots can limit the lens and ensure that the center height of the lens is the same. In use, the lens is first installed into the lens frame, and the lens frame is slid into the lens slide rail 6. The distance between the two lens frames is adjusted. Then the incident height of the laser generator is adjusted to be the same as the center height of the lens, and the laser generator is clamped and fixed.

[0036] The lens slide rail 6 is as follows Figure 8As shown, the lens includes an insertion base plate, two tracks on the insertion base plate, and a groove 22 extending along the length with an opening at the front end above the tracks. The groove is through-hole on both sides. The other side of the insertion base plate is "n"-shaped, which avoids the location of the connecting cylinder 17 when inserted into the light-shielding box. The overall dimensions of the lens slide rail are 115 × 60 × 16.6 mm. The groove 22 can be installed in the light-shielding box 5 after being fitted with the lug 21 on the lens frame 7. The magnification of the lens can be adjusted by adjusting the distance between the two lens frames using the operating lever 23.

[0037] The height-adjustable stage is raised by 20 mm from the standard stage, allowing the light-shielding box 5 to be placed and inserted on the side with the installation opening. Inserting the light-shielding box into the stage ensures imaging quality, protects experimental safety, and limits the movement of various structures.

[0038] Reflective element 4, for example Figure 9 As shown, it includes: a piezoelectric ceramic base plate 14, piezoelectric ceramic modules, and a reflector platform 13. Four piezoelectric ceramic modules are vertically mounted on the piezoelectric ceramic base plate, and the reflector platform 13 is rotatably connected to the four piezoelectric ceramic modules through ball joints, allowing the reflector platform 13 to rotate freely in space.

[0039] The piezoelectric ceramic base plate 14 is as follows Figure 9 As shown, a 40 mm diameter reflector platform 13 is supported by four piezoelectric ceramic modules of varying heights. The back of the reflector platform is rotatably mounted to the piezoelectric ceramic modules. A control program controls the voltage signals of each piezoelectric ceramic module, adjusting their length to change the angle of the reflector platform 13, thereby controlling the position of the light source illuminating the sample. In the initial state, with the light-shielding box clamping part as the front view, the height of the front piezoelectric ceramic module is 14.14 mm, the rear piezoelectric ceramic module is 26.14 mm, and the height of the two side piezoelectric ceramic modules is 20.14 mm, resulting in an initial angle of 45° for the reflector platform. The incident laser from the reflected laser generator is directed to irradiate the bottom of the sample perpendicularly.

[0040] The reflector platform 13 is as follows Figure 9 As shown, the default installation angle is 45° to the horizontal, which allows the parallel light source to be reflected upwards and vertically illuminate the sample. The reflector diameter is 20 mm, ensuring that the entire light source is utilized.

[0041] The process of using the aforementioned laser platform for in-situ optical stimulation of two-dimensional materials is as follows: The first step is to determine the parameters of the selected lens, select the magnification to adjust the size of the light spot, slide two lens frames 7 into the lens slide rail 6, use the groove 22 to cooperate with the lens frame ear 21 for installation, and adjust the distance. The second step is to install the lens slide rail into the light shield box, place the clamp 8 at the light source inlet end 18 of the light shield box 5, and fix the clamp to the front of the light shield box by the clamping screw 9 and M3 nut 11. Then, install the emitting end of the laser generator between the two clamps. The third step is to screw the adjusting screw 10 into the threaded through hole of the two jaws, adjust the distance between the studs and fix the laser generator in place with the jaws, adjust the laser generator's emitting end axis to be installed at the same height as the center of the two lenses, and start the measurement. The fourth step involves using a control program to control the voltage signals of each piezoelectric ceramic module, thereby changing the length of the four piezoelectric ceramic modules. The angle of the reflector platform 13 is controlled by adjusting the distance between the contact points of the reflector platform 13 and each piezoelectric ceramic module and the piezoelectric ceramic base plate 14, thus controlling the irradiation area. Initially, the reflector platform 13 should be at a 45° angle, with the following heights for each piezoelectric ceramic module: 14.14 mm for the front module, 26.14 mm for the rear module, and 20.14 mm for both side modules. The line connecting the front and rear piezoelectric ceramic modules should coincide with the central axis of the light-shielding box.

[0042] The four piezoelectric ceramic modules have the same amount of expansion and contraction with voltage changes. The piezoelectric ceramic modules can deform when the voltage changes, and the relationship between deformation and voltage is obtained. The microcontroller controls the four piezoelectric ceramic modules to change to different lengths to obtain the desired reflector platform angle.

[0043] The advantages of this invention are: compared to other laser platform equipment, this equipment has a more compact structure, occupies less space, has lower manufacturing costs, ensures personnel safety, has low energy consumption, and possesses a complete coordinate system. It achieves stepless magnification or reduction of the light source from 0 to 2.5 times simply by adjusting the relative distance between two lenses. The light source enters and exits in parallel, ensuring the integrity of the light source and improving the accuracy of laser source introduction and calibration efficiency.

[0044] Example 2 The reflective element used in this embodiment consists of a piezoelectric ceramic driven by an STM32F103C8T6 and an OPA454 amplifier circuit, and a spherical reflector. Its control program and core can be replaced without departing from the spirit of this invention. This embodiment uses a dedicated kit to achieve in-situ light stimulation during the AFM characterization process of the Oxford Instruments MFP-3D model. Various laser sizes can be adapted by adjusting the sliding position of the grippers on the clamping screw, and the laser generator is centered and clamped by adjusting the screw. The laser platform of this invention has a small device size, occupying only 167 mm (distance from the rear end of the adjustable stage to the front end of the laser generator) × 80 mm (total length of the clamping screw) × 22 mm (height from the bottom of the light-shielding box to the adjustable stage).

[0045] The gripper 8 is made of 6061-T4 aluminum. The clamping screw 9 has a total length of 80 mm, a thread depth of 15 mm on each side, and an outer diameter that matches the diameter of the through hole on the light shield box 5.

[0046] The lens slide rail 6 is 115 mm long, 50 mm wide, and 16.5 mm high. The cross-section of the central lens frame adjustment area is 15.5 x 15.5 mm, and the length of the adjustable operating lever slide rail is 60 mm.

[0047] The effective light source passage area of ​​the lens frame 7 is 10 x 10 mm, the lens thickness is 2 mm, and the bottom of the lens frame 7 has a rounded corner with a diameter of 10 mm, so that the lens can be positioned inside the lens frame 7.

[0048] The adjustable platform has 6 support columns with a diameter of 2 mm, and the center distance between the two pairs of support columns on both sides is 62 mm. Subtracting the radius, the adjustable platform 12 can be installed in conjunction with the light shielding box 5.

[0049] Four stacked piezoelectric ceramic modules with a diameter of 2 mm are installed on the piezoelectric ceramic base plate. The piezoelectric ceramic base plate has a diameter of 40 mm (which can be adjusted by itself) and is used in conjunction with the connecting cylinder. In this embodiment, the length of the groove on the lens frame operating rod is not less than 50 mm. Figure 12 Figures 1 and 13 are schematic diagrams of laser beam expansion and contraction when the distance between the two lenses is 50 mm. Figure 12 The left concave lens has a radius of curvature of 19.980 mm, and the right convex lens has a radius of curvature of 47.240 mm. They are a beam expander lens group, which transmits the beam from the left to the right, making the light spot larger. The magnification is 1 to 2.5 times the radius of the laser generator's emission source. Figure 13 The left convex lens has a radius of curvature of 50.328 mm, and the right concave lens has a radius of curvature of 23.068 mm. This is a beam-contracting lens group, where the beam is transmitted from left to right, resulting in a smaller spot size and a magnification of 0.4 to 1 times that of the laser generator's emission source. When the two lenses in the beam-expanding and beam-contracting lens groups are placed together (i.e., the distance between them is 0), the emitted light spot is the same as that of the laser generator's emission source (i.e., 1x zoom). By changing the beam-expanding and beam-contracting lens groups and adjusting the distance between the lenses within the groups, magnification or reduction by any factor from 0.4 to 2.5 can be achieved, allowing the light to be more evenly distributed on the sample.

[0050] The above-described embodiments are for illustrative purposes. Based on the above description, those skilled in the art can make various changes and modifications without departing from the inventive concept.

[0051] The technical scope of this invention is not limited to the contents of the specification; its scope of protection must be determined according to the claims.

[0052] Any aspects not covered in this invention are applicable to existing technologies.

Claims

1. A laser experimental platform for in-situ optical stimulation of two-dimensional materials for AFM, characterized in that, The experimental platform includes: Clamping mechanism, used to clamp and position laser generators of different radii; A lens element is used to magnify or reduce the size of the light source by adjusting the distance between two lens frames, thereby adjusting the size of the light spot; Platform support elements are used to provide a suitable placement position for two-dimensional material samples for testing; The reflective element, located below the sample mounting position of the platform support element, is used to reflect the light beam transmitted by the lens element to illuminate the bottom of the sample, and to apply in-situ light stimulation to the sample during the AFM characterization process. The platform support components include: an adjustable stage and a light-shielding box, with the light-shielding box inserted into the adjustable stage. The light-shielding box includes a flat rectangular light-shielding body and a connecting cylinder for cooperating with the AFM worktable. An opening is provided on one side of the light-shielding box body as a light source inlet. A number of symmetrical through holes are provided on the side wall of the light-shielding box body at the light source inlet, for fixing the clamps to the light-shielding box by clamping screws. The connecting cylinder is connected to the bottom of the closed side of the light-shielding box body and communicates with the interior of the light-shielding box body. An installation opening is provided on the upper surface of the light-shielding box body above the connecting cylinder. An observation opening is provided on the side of the light-shielding box body. An operating rod slide rail is provided on the side of the light-shielding box body between the light source inlet and the observation opening. The lens element is installed inside the main body of the light shield, and can be moved back and forth within the unopened area of ​​the main body of the light shield by the action of the operating lever. The reflective element includes several piezoelectric ceramic modules, a piezoelectric ceramic base plate, and a reflector platform. The piezoelectric ceramic base plate is fixed inside the connecting cylinder, and the piezoelectric ceramic modules are vertically installed on the upper surface of the piezoelectric ceramic base plate. All the piezoelectric ceramic modules together support the reflector platform. By controlling the voltage signal of each piezoelectric ceramic module, its length can be adjusted to change the angle of the reflector platform, thereby controlling the position of the light source illuminating the sample.

2. The laser experimental platform for in-situ optical stimulation of two-dimensional materials for AFM according to claim 1, characterized in that, The clamping mechanism includes: jaws, clamping screws, adjusting studs, and nuts; a laser generator is clamped between two jaws, which are arranged opposite each other. V-grooves are provided on opposite sides of the two jaws to clamp the laser generator. The two V-grooves clamp the front end of the laser generator. Each jaw has upper and lower extension sections at its rear end. Each extension section has multiple through holes, and at least one through hole is a threaded through hole. The non-threaded through holes fix the jaws to the front end of the light shield box by clamping screws and nuts. The threaded through holes can adjust the distance between the two jaws by installing adjusting screws to accommodate laser generators of different sizes, and can also adjust the alignment of the center line of the laser generator with the center line of the lens element.

3. The laser experimental platform for in-situ optical stimulation of two-dimensional materials for AFM according to claim 1, characterized in that, The clamping screw is a stud with threads at both ends and a smooth middle section. During installation, first place the clamping jaws into one side of the through hole of the light shield box, then insert the clamping screw into the hole through both sides symmetrically, and install the M3 nut.

4. The laser experimental platform for in-situ optical stimulation of two-dimensional materials for AFM according to claim 1, characterized in that, The lens element includes a lens slide rail and two identical lens frames. The lens frames can slide back and forth relative to the lens slide rail. Lenses are installed inside the lens frames. The center height of the lenses in the two lens frames is the same. The distance between the two lenses can be adjusted by the lens slide rail. Alternatively, lenses of the same size but different magnifications can be inserted into the lens frames. The magnification of the light source can be adjusted by adjusting the lens frames. Each lens frame is square in shape. A lens groove for mounting the lens is set in the center of the square structure along the vertical direction. Symmetrical ears are set on both sides of the square structure of the lens frame. The ears are used to slide and install the lens with the lens slide rail. One of the ears is equipped with an operating rod. The length of the operating rod can extend out of the operating rod slide rail on the side of the light shield box and cooperate with the operating rod slide rail on the side of the light shield box to adjust the distance between the lenses in real time.

5. The laser experimental platform for in-situ optical stimulation of two-dimensional materials for AFM according to claim 1, characterized in that, The lens element includes a beam expander lens group and a beam reducer lens group. The beam from the beam expander lens group is transmitted from left to right, and the light spot becomes larger, with a magnification of 1 to 2.5 times the radius of the laser generator's emission source. The beam from the beam reducer lens group is transmitted from left to right, and the light spot becomes smaller, with a magnification of 0.4 to 1 times the radius of the laser generator's emission source. When the two lenses in the beam expander and reducer lens groups are attached together, the emitted light spot is the same as the laser generator's emission source, i.e., 1x zoom, with the side closer to the laser generator being left.

6. The laser experimental platform for in-situ optical stimulation of two-dimensional materials for AFM according to claim 5, characterized in that, When the distance between the two lenses is 50 mm, the radius of curvature of the left concave lens in the beam expander lens group is 19.980 mm, and the radius of curvature of the right convex lens is 47.240 mm; the radius of curvature of the left convex lens in the beam shrinker lens group is 50.328 mm, and the radius of curvature of the right concave lens is 23.068 mm.

7. The laser experimental platform for in-situ optical stimulation of two-dimensional materials for AFM according to claim 1, characterized in that, The height-adjustable stage is raised by 20 mm from the height of a regular stage, allowing a light-shielding box to be accommodated at the bottom.

8. A method for measuring in-situ photostimulated two-dimensional materials for AFM, characterized in that, The measurement method employs in-situ optical measurement using any of the laser experimental platforms described in claims 1-7. The specific process is as follows: The first step is to determine the parameters of the selected lens, select the magnification to adjust the size of the light spot, slide the two lens frames into the lens slide rail and adjust the distance accordingly; The second step is to install the lens slide rail into the light shield box, place the clamp at the light source inlet end of the light shield box, and fix the clamp to the front of the light shield box. Then, install the emitting end of the laser generator between the two clamps. The third step is to adjust the distance between the studs by screwing the screw into the threaded holes of the two grippers and fix the laser generator in place with the grippers. Then, adjust the laser generator's emitting end axis to be installed at the same height as the centers of the two lenses and begin the measurement. The fourth step is to control the voltage signal of each piezoelectric ceramic, change the length of multiple piezoelectric ceramic modules, and control the angle of the reflector platform by adjusting the distance from each contact point of the reflector platform and the piezoelectric ceramic module to the piezoelectric ceramic base plate, so as to control the irradiation area.

9. The method according to claim 8, characterized in that, The method uses four piezoelectric ceramic modules, which have the same amount of expansion and contraction with voltage changes. The piezoelectric ceramic modules can deform when the voltage changes, and the relationship between deformation and voltage is obtained. The four piezoelectric ceramic modules are controlled by a microcontroller to change to different lengths to obtain the desired angle of the reflector platform.

10. The method according to claim 9, characterized in that, In the initial state, the reflector platform is at a 45° angle, and the heights of each piezoelectric ceramic module are as follows: the front piezoelectric ceramic module is 14.14 mm high, the rear piezoelectric ceramic module is 26.14 mm high, and the two side piezoelectric ceramic modules are 20.14 mm high. The line connecting the front and rear piezoelectric ceramic modules coincides with the central axis of the light-shielding box.

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