Atomic force microscope coupled to a reflection and transmission light path

Abstract

The application provides an atomic force microscope coupling reflection and transmission light paths, comprising a cavity, a probe, a refrigeration system and an optical system, the cavity is provided with a vacuum cavity for accommodating a sample and the probe, the probe is used for detecting the surface of the sample; the refrigeration system is used for refrigerating the sample and the probe; the optical system comprises a pair of window assemblies and a pair of objective lenses, the window assembly comprises a hollow shell and a light-transmitting cover plate used for sealing the second end of the hollow shell, the second end of the hollow shell extends into the cavity, the two light-transmitting cover plates are symmetrically arranged in parallel, the sample and the probe are located between the two light-transmitting cover plates; the pair of objective lenses are arranged in the pair of hollow shells respectively, the two objective lenses are symmetrically arranged in parallel, and the sample can be perpendicular to the axis of the objective lens. The traditional objective lens is coupled with the probe of the ultrahigh vacuum ultralow temperature atomic force microscope, and laser can be vertically incident while meeting the detection conditions of the reflection light path and the transmission light path.

Description

Technical Field

[0001] This invention relates to the field of optical detection technology, and more particularly to an atomic force microscope that couples reflection and transmission optical paths. Background Technology

[0002] Atomic force microscopy (AFM) is a commonly used instrument for surface probing. It uses nanoscale probes to detect the surface properties of samples, offering capabilities such as high-resolution imaging at the nanoscale / subnanometer level, precise detection of intermolecular forces, measurement of frictional forces and energy dissipation, and molecular / atomic manipulation. It has wide applications in tribology, physics, biology, chemistry, materials science, and mechanics. Ultra-high vacuum environments shield surfaces from contamination by various gas molecules, ensuring the detection of the most fundamental physicochemical properties of the sample surface. Ultra-low temperatures reduce the thermal activity of the sample surface, drastically decreasing thermal fluctuations and freezing many excited states in low-dimensional and nanoscale systems, making quantum properties more pronounced and potentially leading to anomalous physical properties such as superconductivity and superfluidity. Therefore, ultra-high vacuum and ultra-low temperature environments significantly enhance the detection capabilities of atomic force microscopy.

[0003] Optical methods are commonly used to detect the properties of matter. Common optical detection techniques include Raman spectroscopy, coherent anti-Stokes Raman spectroscopy, fluorescence lifetime imaging, and transient absorption spectroscopy. These techniques can detect information such as the electronic behavior, phonon behavior, composition, and stress distribution of a sample. The optical paths used in these detection techniques are generally reflective or transmissive, with the detection terminal being an optical objective lens. Typically, to achieve a higher signal-to-noise ratio and higher imaging resolution, the optical objectives used in these optical paths have high magnification and large numerical apertures, resulting in short working distances and large sizes.

[0004] Designing an ultra-high vacuum, ultra-low temperature atomic force microscope (UHF / UHT) coupled with optical methods can simultaneously detect the mechanical and optical information of a sample, aiding in the investigation of the origin of matter. However, optical objectives cannot be used in a vacuum environment, and they are bulky. Furthermore, the probe-sample vicinity of an UHF / UHT is highly enclosed, making it difficult to control the distance between the optical objective and the sample within the working distance. Therefore, it is challenging to achieve coupling between either reflected or transmitted light paths and an UHF / UHT. Summary of the Invention

[0005] This invention provides an atomic force microscope that couples reflection and transmission optical paths, thereby overcoming the shortcomings of existing technologies where it is difficult to couple reflection and transmission optical paths with ultra-high vacuum and ultra-low temperature atomic force microscopes.

[0006] This invention provides an atomic force microscope that couples reflection and transmission optical paths, comprising:

[0007] The cavity includes a vacuum chamber for containing the sample.

[0008] A probe, located inside the vacuum chamber, is used to probe the sample surface;

[0009] A refrigeration system is used to create a low-temperature environment inside the vacuum chamber;

[0010] The optical system includes a pair of window assemblies and a pair of objective lenses, wherein,

[0011] The viewing window assembly includes a hollow shell and a light-transmitting cover plate for closing the second end of the hollow shell. The second end of the hollow shell extends into the cavity. The two light-transmitting cover plates are arranged in parallel and symmetrically. The sample and the probe are located between the two light-transmitting cover plates.

[0012] The pair of objectives are respectively disposed in the pair of hollow housings, and the two objectives are arranged in parallel and symmetrically, and the sample can be perpendicular to the axis of the objectives.

[0013] An atomic force microscope with coupled reflection and transmission optical paths according to the present invention further includes a moving device for adjusting the relative position of the sample and the probe, the moving device being located within the vacuum cavity.

[0014] An atomic force microscope with coupled reflection and transmission optical paths according to the present invention further includes a vibration damping module disposed in the vacuum cavity, the moving device being disposed on the vibration damping module, and the vibration damping module being connected to the cooling system or the cavity.

[0015] According to an atomic force microscope with coupled reflection and transmission optical paths provided by the present invention, the moving device includes:

[0016] A coarse adjustment module is mounted on the vibration damping module. The coarse adjustment module is used for coarse adjustment to bring the sample closer to the probe.

[0017] A fine-tuning module is used to fine-tune the sample to contact or approach the probe. The fine-tuning module is disposed on the coarse-tuning module, and the sample is disposed on the fine-tuning module; or, the fine-tuning module is disposed on the vibration damping module, and the probe is disposed on the fine-tuning module.

[0018] According to an atomic force microscope that couples reflection and transmission optical paths provided by the present invention, the cooling system includes:

[0019] The first cold screen is located within the cavity;

[0020] The second cold screen is located inside the first cold screen, the sample and the probe are located inside the second cold screen, and the second ends of the two hollow shells pass through the first cold screen and the second cold screen and are close to the probe;

[0021] A liquid nitrogen Dewar, used to hold liquid nitrogen, and the first cold shield is connected to the liquid nitrogen Dewar;

[0022] A liquid helium dewar is used to hold liquid helium, and the second cold screen is connected to the liquid helium dewar.

[0023] An atomic force microscope with coupled reflection and transmission optical paths according to the present invention further includes a three-dimensional displacement stage for driving the objective lens to move within the hollow housing.

[0024] According to an atomic force microscope that couples reflection and transmission optical paths provided by the present invention, the vibration reduction module includes:

[0025] A spring vibration damper, the first end of which is connected to the refrigeration system;

[0026] An eddy current damping vibration reduction module is provided, wherein the eddy current damping vibration reduction module is connected to the second end of the spring vibration damping frame, and the moving device is mounted on the eddy current damping vibration reduction module.

[0027] According to the present invention, an atomic force microscope with coupled reflection and transmission optical paths is provided, wherein the coarse motion module is a three-dimensional piezoelectric scanning stage and the fine motion module is a piezoelectric scanning tube.

[0028] According to an atomic force microscope with coupled reflection and transmission optical paths provided by the present invention, the coarse motion module or the fine motion module is provided with a sample holder for fixing the sample; the fine motion module or the vibration damping module is provided with a probe holder for fixing the probe; and both the sample holder and the probe holder are provided with through holes for the optical path to pass through.

[0029] According to an atomic force microscope with coupled reflection and transmission optical paths provided by the present invention, the three-dimensional displacement stage is connected to the objective lens via an objective lens holder.

[0030] The atomic force microscope (AFM) with coupled reflection and transmission optical paths provided by this invention can place samples in an ultra-high vacuum and ultra-low temperature environment through a cooling system and vacuum chamber, which greatly enhances the detection capability of this AFM. While meeting the requirements of ultra-high vacuum and ultra-low temperature experimental environments, it not only provides sufficient space for the introduction of optical objectives, but also places the probe and sample perpendicular to the axis of the objective, resulting in a compact structure that meets the working distance requirements of the objective. The horizontally symmetrical window assembly solves the compatibility problem between the objective and the vacuum environment. The hollow shell of the window assembly is filled with an atmospheric environment, ensuring the working conditions of the objective under atmospheric conditions. A light-transmitting cover is set at the end of the hollow shell near the sample, allowing the laser to pass through. The horizontally opposed placement of the window assembly ensures the vertical incidence of the laser and the simultaneous realization of the reflection and transmission optical paths, and allows coupling of any optical path with the ultra-high vacuum and ultra-low temperature AFM, successfully solving the coupling problem between optical detection methods and atomic force microscopy. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0032] Figure 1 This is a cross-sectional view of the atomic force microscope with coupled reflection and transmission optical paths provided by the present invention;

[0033] Figure 2 This is a three-dimensional view of the atomic force microscope with coupled reflection and transmission optical paths provided by the present invention;

[0034] Figure 3 This is a front view of the atomic force microscope with coupled reflection and transmission optical paths provided by the present invention;

[0035] Figure 4 This is a bottom view of the atomic force microscope with coupled reflection and transmission optical paths provided by the present invention;

[0036] Figure 5 This is one of the partial views of the atomic force microscope with coupled reflection and transmission optical paths provided by the present invention;

[0037] Figure 6 This is a second partial view of the atomic force microscope with coupled reflection and transmission optical paths provided by the present invention;

[0038] Figure 7 This is a third partial view of the atomic force microscope with coupled reflection and transmission optical paths provided by the present invention.

[0039] Figure label:

[0040] 1: Cavity; 2: Liquid helium Dewar; 3: Second cold shield; 4: First cold shield; 5: Concave flange; 6: Hollow shell; 7: Transparent cover plate; 8: First objective lens; 9: Second objective lens; 10: Objective lens holder; 11: Coarse motion module; 12: Fine motion module; 13: Holder; 14: Sample holder; 15: Probe holder; 16: Holder tube; 17: Upper base; 18: Lower base plate; 19: Spring; 20: Hook weight; 21: Electromagnetic eddy current damping grid; 22: Moving device support; 23: Three-dimensional displacement stage; 24: Laser; 25: Photodetector; 26: CCD camera; 27: First lens; 28: Second lens; 29: Through hole; 30: Excitation ceramic; 31: Liquid nitrogen Dewar. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0042] The following is combined Figures 1 to 7 An atomic force microscope describing the coupled reflection and transmission optical paths of the present invention.

[0043] like Figure 1 As shown, the present invention provides an atomic force microscope with coupled reflection and transmission optical paths, including a cavity 1, a probe, a cooling system and an optical system.

[0044] The cavity 1 includes a vacuum chamber, which houses the sample and probe. The vacuum environment within the chamber shields the sample surface from contamination by various gas molecules in the air, ensuring the detection of the sample's most fundamental physicochemical properties. The probe is used to probe the sample surface, obtaining information such as material mechanical properties or surface morphology.

[0045] Here, the atomic force microscope can operate in contact, non-contact, or tapping modes. In contact mode, the probe can contact the sample, ensuring the probe tip remains in close contact with the sample surface throughout the entire scanning imaging process. In non-contact mode, the probe can oscillate at a distance of 5-10 nm above the sample surface. In this mode, the interaction between the sample and the tip is controlled by van der Waals forces, typically 10-12 N. The sample is not damaged, and the tip is not contaminated, making it particularly suitable for studying the surfaces of delicate objects. In tapping mode, the probe oscillates above the sample surface at its resonant frequency, with the tip only periodically and briefly contacting / tapping the sample surface. Both tapping and non-contact modes require probe vibration; therefore, an excitation ceramic 30 is needed to excite the probe vibration. The excitation ceramic 30 can be mounted on the probe holder 15.

[0046] The cooling system can be set inside cavity 1. The cooling system is used to create a low-temperature environment inside the vacuum cavity, so that the sample and probe are in an ultra-low temperature environment, thereby reducing the thermal activity of the sample surface, causing the thermal fluctuation of the sample to drop sharply, freezing many excited states of low-dimensional and nano-scale systems, making quantum properties more obvious, and realizing anomalous physical properties such as superconductivity and superfluidity.

[0047] The optical system includes a pair of window assemblies and a pair of objective lenses. The window assembly includes a hollow housing 6 and a light-transmitting cover plate 7. The light-transmitting cover plate 7 is disposed at the second end of the hollow housing 6 and can close the second end of the hollow housing 6. The second end of the hollow housing 6 extends into the cavity 1. The two light-transmitting cover plates 7 of the two window assemblies are arranged in parallel and symmetrically. The sample and the probe are located between the two light-transmitting cover plates 7. In this way, the light path transmitted through the light-transmitting cover plate 7 can illuminate the sample and the probe.

[0048] It should be noted that because the light-transmitting cover 7 seals the second end of the hollow shell 6, the hollow shell 6 is not connected to the vacuum chamber, and the vacuum environment of the vacuum chamber is not affected, thus placing the sample in an ultra-high vacuum environment. Here, the second end of the hollow shell 6 is the end located inside the cavity 1.

[0049] Two objective lenses are respectively housed within two hollow housings 6. Specifically, the two objective lenses can be positioned close to the light-transmitting cover plate 7 to facilitate the reception or transmission of light. The two objective lenses are arranged in parallel and symmetrically, and the sample can be perpendicular to the axis of the objective lens. This ensures that the laser can be incident perpendicularly on the sample regardless of which objective lens it enters, thereby improving the reliability of the detected optical information.

[0050] Here, the sample and probe are located within the working distance of the objective lens, meaning the distance between the sample / probe and the objective lens is less than the working distance of the objective lens. This ensures that the light incident through the objective lens can illuminate the sample, and that the light reflected or transmitted from the sample can reach the objective lens. The working distance of the objective lens refers to the distance from the bottom of the front lens of the objective lens to the top of the coverslip of the specimen when the observed specimen is clearest.

[0051] Furthermore, one of the two objectives can collect the reflected light from the sample, while the other can collect the transmitted light. Specifically, the two objectives can be a first objective 8 and a second objective 9, with the sample positioned closer to the first objective 8 and the probe positioned closer to the second objective 9. A laser beam is irradiated onto the sample through the first objective 8, which collects the laser signal reflected back from the sample, while the second objective 9 collects the laser signal transmitted through the sample.

[0052] This configuration, through the cooling system and vacuum chamber, allows the sample to be placed in an ultra-high vacuum and ultra-low temperature environment, greatly enhancing the detection capability of this atomic force microscope. While meeting the requirements of ultra-high vacuum and ultra-low temperature experimental environments, it not only provides sufficient space for the introduction of optical objectives, but also ensures that the probe and sample are placed perpendicular to the objective axis, resulting in a compact structure that meets the objective's working distance requirements. The horizontally symmetrical window assembly solves the compatibility issue between the objective and the vacuum environment. The hollow shell 6 of the window assembly is filled with an atmospheric environment, guaranteeing the objective's working conditions under atmospheric conditions. A light-transmitting cover 7 is located at the end of the hollow shell 6 closest to the sample, allowing laser light to pass through. The horizontally opposed placement of the window assembly ensures the vertical incidence of the laser and the simultaneous realization of reflected and transmitted light paths, allowing coupling of either optical path with the ultra-high vacuum and ultra-low temperature atomic force microscope, successfully solving the coupling problem between optical detection methods and atomic force microscopy.

[0053] In an optional embodiment of the present invention, the atomic force microscope with coupled reflection and transmission optical paths further includes a moving device for adjusting the relative position of the sample and the probe so that the probe can contact or approach the sample for detection.

[0054] Furthermore, the moving device can be located inside the vacuum chamber, which facilitates the adjustment of the relative positions of the sample and the probe while ensuring the vacuum of the vacuum chamber.

[0055] In an optional embodiment of the present invention, the atomic force microscope with coupled reflection and transmission optical paths further includes a vibration reduction module. The moving device is disposed on the vibration reduction module to reduce the vibration of the sample and probe, thereby avoiding the influence of external forces on the accuracy of sample detection.

[0056] Here, the vibration damping module is connected to the refrigeration system or cavity 1.

[0057] Specifically, the vibration damping module includes a spring damping frame and an eddy current damping module. The first end of the spring damping frame is connected to the cooling system, and the eddy current damping module is connected to the second end of the spring damping frame. A moving device is mounted on the eddy current damping module. Thus, the dual damping effect of the spring damping frame and the eddy current damping module improves the vibration reduction effect on the sample and probe.

[0058] In an optional embodiment, the spring damping frame and the eddy current damping module are connected to the refrigeration system through an external frame. The external frame includes an upper base 17, four support pipes 16, and a lower base plate 18. The upper base 17 can be fixedly connected to the refrigeration system. The top ends of the four support pipes 16 are all fixedly connected to the upper base 17, and the lower base plate 18 is connected to the bottom end of the support pipes 16.

[0059] Furthermore, the spring damping frame includes four springs 19, which are respectively installed inside four support pipes 16. The top of the springs 19 is suspended inside the support pipes 16 by hooks and weights 20, and the bottom of the springs 19 is connected to the eddy current damping module. The eddy current damping module includes a moving device support 22 and an electromagnetic eddy current damping grid 21. The electromagnetic eddy current damping grid 21 is installed between the lower base plate 18 and the moving device support 22, and the moving device is installed on the moving device support 22.

[0060] Here, four support pipes 16 are arranged around the outside of the mobile device, and both the upper base 17 and the lower base plate 18 are circular structures with the same diameter. The mobile device support 22 can be a copper disk structure fixed on the electromagnetic eddy current damping grid 21.

[0061] In an optional embodiment of the present invention, the moving device includes a coarse motion module 11 and a fine motion module 12.

[0062] The coarse adjustment module 11 is mounted on the vibration damping module. Specifically, the coarse adjustment module 11 can be mounted on the moving device support 22. The coarse adjustment module 11 is used for coarse adjustment to bring the sample closer to the probe so that the probe can detect the sample.

[0063] The precision adjustment module 12 is used to adjust the precise position of the sample or probe and make the sample contact the probe, thereby enabling the probe to detect the sample.

[0064] In one embodiment, the fine motion module 12 is disposed on the coarse motion module 11, and the sample is disposed on the fine motion module 12 so that the fine motion module 12 can drive the sample to contact or approach the probe, and the probe is connected to the vibration damping module through the bracket 13.

[0065] In another embodiment, the fine motion module 12 can be disposed on the vibration damping module. Specifically, the fine motion module 12 can be disposed on the moving device support 22, and the probe is disposed on the fine motion module 12 so that the fine motion module 12 can drive the probe to contact or approach the sample.

[0066] In an optional embodiment, a sample holder 14 may be provided on the coarse motion module 11 or the fine motion module 12 for fixing the sample; a probe holder 15 may be provided on the fine motion module 12 or the vibration damping module for fixing the probe. Here, the sample holder 14 may be provided on the fine motion module 12, the fine motion module 12 may be provided on the coarse motion module 11, and the probe is connected to the vibration damping module through the probe holder 15.

[0067] Furthermore, in order to ensure that the light path incident on the objective lens illuminates the sample and probe, through holes 29 are provided on both the sample holder 14 and the probe holder 15, so that the light path can pass through the through holes 29 to illuminate the sample and probe, or to allow the reflected and transmitted light path to be conducted to the objective lens.

[0068] In an optional embodiment, the coarse motion module 11 can be a three-dimensional piezoelectric scanning stage with a large step size, used to drive the sample to quickly approach the probe. Here, the three-dimensional piezoelectric scanning stage is driven by piezoelectric ceramics and achieves three-dimensional linear motion in the XYZ directions based on a high-precision frictionless flexible hinge parallel guide structure. The specific structure of the three-dimensional piezoelectric scanning stage is not limited, as long as it can achieve three-dimensional linear motion in the XYZ directions.

[0069] In an optional embodiment, the fine-motion module 12 can be a piezoelectric scanning tube, which is used to perform scanning imaging in the XYZ directions after the sample reaches the designated position under the action of the coarse-motion module 11, thereby adjusting the precise position of the sample and the probe.

[0070] In an optional embodiment of the present invention, the refrigeration system includes a first cold shield 4, a second cold shield 3, a liquid nitrogen Dewar 31, and a liquid helium Dewar 2. The first cold shield 4 and the second cold shield 3 are used to shield thermal radiation. The first cold shield 4 is connected to the liquid nitrogen Dewar 31, so that the temperature of the first cold shield 4 can reach 77K (i.e., liquid nitrogen temperature) through the liquid nitrogen Dewar 31. The second cold shield 3 is connected to the liquid helium Dewar 2, so that the temperature of the second cold shield 3 can reach 4K (i.e., liquid helium temperature) through the liquid helium Dewar 2.

[0071] Furthermore, the first cold screen 4 is located inside the cavity 1, the second cold screen 3 is located inside the first cold screen 4, and both the sample and the probe are located inside the second cold screen 3. This configuration ensures that the sample and probe are in an ultra-low temperature environment while reducing the use of liquid helium, thereby lowering costs.

[0072] Here, both the liquid helium dewar 2 and the liquid nitrogen dewar 31 are connected to the cavity 1 via sealing flanges to ensure the airtightness of the vacuum cavity.

[0073] In some embodiments, the liquid helium Dewar 2 can be disposed inside the liquid nitrogen Dewar 31, that is, the liquid helium Dewar 2 and the liquid nitrogen Dewar 31 can be a single Dewar, which includes an inner tank containing liquid helium and an outer tank containing liquid nitrogen, with the inner tank located inside the outer tank. This facilitates reducing the space occupied by the refrigeration system.

[0074] In this embodiment, the second end of the hollow shell 6 passes through the first cold screen 4 and the second cold screen 3 and approaches the probe, so that the objective lens can approach the sample located between the two hollow shells 6, thereby enabling the sample to be within the working distance of the objective lens and realizing the coupling between the objective lens and the vacuum environment.

[0075] In an optional embodiment of the present invention, the atomic force microscope with coupled reflection and transmission optical paths further includes a three-dimensional displacement stage 23 for driving the objective lens to move within the hollow housing 6. The three-dimensional displacement stage 23 allows adjustment of the objective lens's orientation, thereby adjusting the laser incident angle or position and facilitating the reception of reflected and transmitted optical paths, thus improving detection accuracy.

[0076] Specifically, the three-dimensional translation stage 23 is connected to the objective lens via the objective lens holder 10, and the objective lens holder 10 is located inside the hollow shell 6, so that the three-dimensional translation stage 23 can adjust the position and orientation of the objective lens.

[0077] In this embodiment, the objective lens is positioned at the front end of the objective lens holder 10 (i.e., the end of the objective lens holder 10 closest to the light-transmitting cover plate 7). The objective lens holder 10 has an internal hollow structure, allowing laser light to irradiate the sample through the objective lens holder 10 and the objective lens. A three-dimensional displacement stage 23 can be positioned at the bottom end of the objective lens holder 10, used to move the objective lens horizontally and vertically, adjusting the horizontal position and focal length of the objective lens to compensate for errors during assembly.

[0078] In an optional embodiment, the three-dimensional displacement stage 23 includes a base, a displacement platform, and a support plate. The displacement platform is connected to the base and includes an X-direction displacement mechanism, a Y-direction displacement mechanism, and a Z-direction displacement mechanism, so that the displacement platform can achieve translation with three degrees of freedom.

[0079] Here, the X-direction displacement mechanism, Y-direction displacement mechanism, and Z-direction displacement mechanism can be driven by a drive device such as a cylinder, electric push rod, or lead screw mechanism.

[0080] In an optional embodiment, this atomic force microscope with coupled reflection and transmission optical paths further includes two concave flanges 5. The two concave flanges 5 are symmetrically arranged and connected to the cavity 1 by a metal seal. The two viewing window assemblies extend into the cavity 1 through the two concave flanges 5 and approach the sample and probe at close range.

[0081] In this embodiment, the hollow housing 6 of the viewing window assembly can be made of stainless steel, and the light-transmitting cover 7 can be made of high-transmittance glass, allowing laser light to pass through. Furthermore, the cavity 1 can also be made of stainless steel. Specifically, the hollow housing 6 and the cavity 1 can be made of 316 stainless steel.

[0082] In an optional embodiment of the invention, the objective lens is detachably disposed within the hollow housing 6 so as to facilitate replacement of the objective lens as needed, i.e., the first objective lens 8 and the second objective lens 9 can be replaced with any type of optical objective lens.

[0083] In an optional embodiment of the invention, the optical system further includes a position detection device for connecting the first objective lens 8 or the second objective lens 9.

[0084] Here, the position detection device can be connected to the second objective lens 9. Specifically, the position detection device includes a CCD camera 26, a laser 24, a photodetector 25, a first lens 27 and a second lens 28 disposed within the objective lens holder 10. The laser 24 is disposed outside the objective lens holder 10 and is used to emit laser light. The laser emitted by the laser 24 can pass through the first lens 27 and be perpendicularly incident on the second objective lens 9. This laser light then illuminates the probe through the second objective lens 9. The CCD camera 26 is disposed at the end of the objective lens holder 10 away from the second objective lens 9. The CCD camera 26 is used to receive a portion of the light signal reflected by the probe to achieve imaging of the probe. The second lens 28 is disposed close to the second objective lens 9 to reflect the light signal reflected back from the probe into the photodetector 25, so that the photodetector 25 receives the light signal and detects the deformation of the probe.

[0085] This atomic force microscope with coupled reflection and transmission optical paths may also include an external optical path device. The external optical path device may be set at the end of the objective lens holder 10 away from the light-transmitting cover plate 7, and the objective lens and the external optical path device may be arbitrarily matched according to functional requirements.

[0086] For example, a Raman optical detection system emits a laser beam, which is focused onto the sample by the first objective lens 8. The first objective lens 8 collects the light signal reflected from the sample and transmits this signal back to the Raman optical detection system for analysis to obtain the Raman signal of the sample. A laser beam is emitted from laser 24, passes through the first lens 27 and the second objective lens 9, and illuminates the probe. After reflection from the probe, part of the laser beam passes through the second lens 28 and illuminates the photodetector 25, while part of the laser beam illuminates the CCD camera 26. The laser beam illuminating the photodetector 25 is used to detect the probe deformation during atomic force microscopy scanning and obtain mechanical information; the laser beam illuminating the CCD camera 26 enables imaging of the probe. Therefore, Raman optical detection and ultra-high vacuum ultra-low temperature atomic force microscopy detection are coupled.

[0087] In existing technologies, there are several methods for coupling the optical path with an atomic force microscope:

[0088] 1) Under atmospheric conditions, the laser and the atomic force microscope probe are coupled by tilting the objective lens (at an angle of 45° with the sample surface);

[0089] 2) In an ultra-high vacuum environment, a thin optical fiber is inserted near the sample to achieve coupling;

[0090] 3) In an ultra-high vacuum environment, a specially designed lens is placed in a vacuum to replace the traditional optical objective lens to achieve coupling.

[0091] However, existing methods for coupling the optical path with an atomic force microscope have the following drawbacks: for example:

[0092] In Method 1), the tilted placement of the objective lens results in an elliptical light spot illuminating the sample. The spatial distribution of the light spot energy no longer conforms to a conventional Gaussian distribution, reducing the reliability of the detected optical information. Furthermore, for detecting electron spin, non-perpendicularly incident laser light is difficult to detect electron spin states; therefore, this coupling method limits the applicability of optical detection.

[0093] Method 2) Although lasers can be introduced onto the sample surface, the spot shape and optical signal collection capabilities provided by optical fibers are far less than those of traditional optical objectives, resulting in a very poor signal-to-noise ratio.

[0094] While the specially designed lens used in method 3) solves the problem that traditional objectives cannot be used in a vacuum, its image quality and signal-to-noise ratio are weaker than those of traditional optical objectives. Furthermore, the above three methods only support reflective optical paths, collecting only reflected light information and not supporting transmission optical paths.

[0095] Compared with the above-mentioned methods of coupling optical paths to atomic force microscopes, the atomic force microscope provided by this invention uses general optical objectives, which are more versatile; the optical objectives operate in an atmospheric environment, making them easy to replace; the optical objectives can be commercially available, providing stronger imaging and signal collection capabilities; the symmetrically arranged window assembly can meet the requirements of both reflected and transmitted optical paths; and the objective holder 10 is a universal optical interface, which theoretically allows any optical detection method to be coupled to the atomic force microscope, giving it wide applicability.

[0096] The device embodiments described above are merely illustrative, and some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An atomic force microscope that couples reflection and transmission optical paths, characterized in that, include: The cavity includes a vacuum chamber for containing the sample. A probe, located inside the vacuum chamber, is used to probe the sample surface; A refrigeration system is used to create a low-temperature environment inside the vacuum chamber; The optical system includes a pair of window assemblies and a pair of objective lenses, wherein, The viewing window assembly includes a hollow shell and a light-transmitting cover plate for closing the second end of the hollow shell. The second end of the hollow shell extends into the cavity. The two light-transmitting cover plates are arranged in parallel and symmetrically. The sample and the probe are located between the two light-transmitting cover plates. The pair of objectives are detachably disposed within the pair of hollow housings, the two objectives are arranged in parallel and symmetrically, and the sample is perpendicular to the axis of the objectives; A moving device for adjusting the relative position of the sample and the probe, the moving device being located inside the vacuum chamber; The vibration damping module is installed inside the vacuum chamber, the moving device is installed on the vibration damping module, and the vibration damping module is connected to the refrigeration system or the chamber. The refrigeration system includes: The first cold screen is located within the cavity; The second cold screen is located inside the first cold screen, the sample and the probe are located inside the second cold screen, and the second ends of the two hollow shells pass through the first cold screen and the second cold screen and are close to the probe; A liquid nitrogen Dewar, used to hold liquid nitrogen, and the first cold shield is connected to the liquid nitrogen Dewar; A liquid helium dewar, used to hold liquid helium, and the second cold screen is connected to the liquid helium dewar; The vibration damping module includes: A spring vibration damper, the first end of which is connected to the refrigeration system; An eddy current damping vibration reduction module is provided, wherein the eddy current damping vibration reduction module is connected to the second end of the spring vibration damping frame, and the moving device is mounted on the eddy current damping vibration reduction module.

2. The atomic force microscope with coupled reflection and transmission optical paths according to claim 1, characterized in that, The mobile device includes: A coarse adjustment module is mounted on the vibration damping module. The coarse adjustment module is used for coarse adjustment to bring the sample closer to the probe. A fine-tuning module is used to fine-tune the sample to contact or approach the probe. The fine-tuning module is disposed on the coarse-tuning module and is used to fix the sample; or, the fine-tuning module is disposed on the vibration damping module and the probe is disposed on the fine-tuning module.

3. The atomic force microscope with coupled reflection and transmission optical paths according to claim 1, characterized in that, It also includes a three-dimensional displacement stage for driving the objective lens to move within the hollow housing.

4. The atomic force microscope with coupled reflection and transmission optical paths according to claim 2, characterized in that, The coarse motion module is a three-dimensional piezoelectric scanning stage, and the fine motion module is a piezoelectric scanning tube.

5. The atomic force microscope with coupled reflection and transmission optical paths according to claim 2, characterized in that, The coarse motion module or the fine motion module is provided with a sample holder for fixing the sample; the fine motion module or the vibration damping module is provided with a probe holder for fixing the probe; and both the sample holder and the probe holder are provided with through holes for the optical path to pass through.

6. The atomic force microscope with coupled reflection and transmission optical paths according to claim 3, characterized in that, The three-dimensional displacement stage is connected to the objective lens via an objective lens holder.

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