An atomic force microscopy system

Abstract

This application provides an atomic force microscopy system, relating to the field of optical detection. In the atomic force microscopy system provided by this application, the focusing lens structure and the reflective surface of the cantilever constitute a tilt-invariant retroreflection system, adjusting the reflected beams from the cantilever at different tilt angles to be spatially staggered but along the same direction. Therefore, when detecting this reflected beam, the relevant sensors can be set based on the modulated direction of the reflected beam, enabling the sensors to receive the beam reflected from the cantilever at a stable angle, reducing the detection difficulty for the sensors. Furthermore, to avoid multiple reflections of the resulting beam between the reflective interface and the reflective surface affecting the detection results of the position-sensitive detector, the atomic force microscopy system provided by this application also includes an anti-interference structure. This anti-interference structure introduces additional deflection into the resulting beam, ensuring the detection accuracy of the position-sensitive detector.

Description

TECHNICAL FIELD

[0001] The present application relates to optical detection, in particular to an atomic force microscopy system. BACKGROUND

[0002] Atomic force microscope (AFM) is a kind of high-resolution scanning probe microscope, which can detect the surface structure and properties of the measured sample at atomic and nanometer scale.

[0003] The atomic force microscope has a cantilever, one end of which is fixed, and the other end has a probe. When there is an interaction force between the probe tip and the measurement object, the cantilever will deflect slightly. By detecting these deflection amounts, the image of the surface topography of the measurement object can be obtained.

[0004] Considering that the deflection of the cantilever is very slight, how to effectively detect the deflection of the cantilever is a technical problem to be solved by those skilled in the art. SUMMARY

[0005] Therefore, the embodiments of the present application provide an atomic force microscopy system, which adopts an optical detection method to determine the deflection of the cantilever based on the change of the reflected light beam on the surface of the cantilever.

[0006] The present application provides an atomic force microscopy system, which comprises a light source, a cantilever, a focusing lens structure, a position sensitive detector, a detector beam splitter and an anti-interference structure. The light source is used to emit an initial light beam. The cantilever has a reflective surface, and the cantilever is configured to change the tilt angle based on the interaction force between the probe of the cantilever and the measurement object. When the cantilever is at different tilt angles, the reflected light beam reflected from the reflective surface has different angles. The focusing lens structure is arranged between the cantilever and the light source, and is used to guide the initial light beam to the reflective surface and adjust the reflected light beams with different angles into result light beams which are spatially staggered and along the same direction, wherein the propagation direction of the result light beam is parallel and opposite to the propagation direction of the initial light beam. The position sensitive detector is used to detect the position information of the result light beam, and the position information reflects the change of the tilt angle of the cantilever. The detector beam splitter is arranged along the light path of the result light beam, and is used to introduce the result light beam into the position sensitive detector. The anti-interference structure is arranged obliquely on the light path of the result light beam, and is used to transmit the result light beam.

[0007] This application provides an atomic force microscopy system that uses a focusing lens structure and the reflective surface of a cantilever to form a tilt-invariant retroreflection system. This system adjusts reflected beams from cantilevered arms at different tilt angles to be spatially staggered but along the same direction. Therefore, when detecting the reflected beam, the relevant sensors can be set based on the modulated direction of the reflected beam, enabling them to receive the beam reflected from the cantilever at a stable angle, reducing the detection difficulty for the sensors. Furthermore, to avoid multiple reflections of the resulting beam between the reflective interface and the reflective surface affecting the detection results of the position-sensitive detector, the atomic force microscopy system provided in this application also includes an anti-interference structure. This structure introduces additional deflection into the resulting beam, ensuring the detection accuracy of the position-sensitive detector. Attached Figure Description

[0008] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1 This is a schematic diagram illustrating the application scenarios of the atomic force microscope provided in some embodiments of this application.

[0010] Figure 2 This is a schematic diagram of the structure of an atomic force microscopy system provided in some embodiments of this application.

[0011] Figure 3 This is a schematic diagram of the optical path of a focusing lens structure provided in some embodiments of this application.

[0012] Figure 4 This is a schematic diagram of the optical path of a multi-reflected beam provided in some embodiments of this application.

[0013] Figure 5 This is a schematic diagram of the internal optical path of a wedge-shaped sheet provided in some embodiments of this application.

[0014] Figure 6 This is a schematic diagram of the internal optical path of a wedge-shaped sheet provided in some embodiments of this application.

[0015] Figure 7 This is a schematic diagram of the structure of an atomic force microscopy system based on an anti-interference structure provided in some embodiments of this application.

[0016] Figure 8 This is a schematic diagram of the structure of an atomic force microscopy system based on a compensation element provided in some embodiments of this application.

[0017] Figure 9A , Figure 9B This is a schematic diagram of the detection results of the position-sensitive detectors of two atomic force microscopy systems provided in some embodiments of this application.

[0018] Among them, 110, atomic force microscope; 111, microscopic cantilever; 112, probe; 113, laser; 114, detector; 120, object to be measured; 200, atomic force microscopy system; 210, light source; 220, cantilever; 230, focusing lens structure; 231, incident area; 232, exit area; 2321, divergence component; 2322, correction component; 240, position-sensitive detector; 250, detector beam splitter; 260, anti-interference structure; 270, compensation element; 280, interference sensor; 410, reflective interface; 420, reflective surface. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0020] SUMMARY

[0021] In atomic force microscopy, changes in the angle of the cantilever (bending and twisting) can be detected using a number of different techniques, such as piezoelectricity, piezoelectricity, and optical beam deflection (OBD).

[0022] Given that beam deflection has a fast response speed and low cost, it is a commonly used detection method in cantilever inspection.

[0023] To further illustrate the atomic force microscope based on beam deflection, this application also provides a schematic diagram of an application scenario for the atomic force microscope. Figure 1 ).

[0024] like Figure 1 As shown, the atomic force microscope 110 may include a microcantilever 111 and a probe 112 disposed at one end of the microcantilever 111. The probe 112 can drive the microcantilever 111 to change its tilt angle based on the force between itself and the object being measured 120. The force between the probe 112 and the object being measured 120 can be set according to the actual scenario. For example, the force between the probe 112 and the object being measured 120 can be atomic force, electric force, pressure, etc.

[0025] In some embodiments, the optical deflection detection system can detect morphological changes of the microcantilever 111 by reflecting a light beam onto the microcantilever 111. The back surface of the microcantilever 111 (the surface away from the object being measured 120) can be coated with a reflective coating to reflect the irradiated light beam.

[0026] The aforementioned atomic force microscope 110 may further include an optical deflection detection system to detect the deflection of the microcantilever 111. Specifically, the atomic force microscope 110 may also include a laser 113 and a detector 114. The laser 113 can be used as the light source for the optical deflection detection system, emitting a beam of light towards the back surface of the microcantilever 111. After being emitted from the laser 113, the beam of light is reflected by the back surface of the microcantilever 111 and enters the detector 114. The detector 114 (such as a position-sensitive sensor) can be used to detect the position of the reflected beam when it enters the detector 114. Through a pre-calibrated correspondence, the morphological change of the microcantilever 111 corresponding to the current beam reflection position is determined. Combined with the correspondence between the morphological change of the microcantilever 111 and the measurement object 120, the surface structure of the measurement object 120 is determined, thereby achieving the measurement of the surface of the measurement object 120 at that location.

[0027] In addition, the atomic force microscope 110 may also include a frame for fixing the end of the microcantilever 111 away from the probe 112 and a stage on the frame, thereby enabling scanning of the surface of the object 120 being measured.

[0028] However, in the aforementioned scenario, considering the small deflection of the microscopic cantilever 111, the initial deflection of the beam reflected by the microscopic cantilever 111 is small. Therefore, the aforementioned detector 114 often needs to detect the beam at a relatively long distance to increase the beam's distinguishability. But this setup results in the beam having many angles of spatial distribution, making it difficult for the detector 114 to detect the beam reflected at various deflection angles over a wide range.

[0029] To address the aforementioned technical issues, this application provides an atomic force microscopy system and its focusing lens structure. Through a specially designed focusing lens structure, the focusing lens structure and the cantilever form a tilt-invariant retroreflection system within the atomic force microscopy system.

[0030] In this tilt-invariant retroreflection system, the focusing lens structure can adjust the reflected beams from cantilever arms at different tilt angles into spatially staggered beams that are aligned in the same direction. Therefore, when detecting the reflected beam, the relevant sensors can be set based on the modulated direction of the reflected beam, enabling them to receive the beam reflected from the cantilever arms at a stable angle. This reduces the detection difficulty for the sensors and simplifies the modulation optical path of the reflected beam.

[0031] Furthermore, the focusing lens structure can correct the direction of the beam while diverging the various beams, thereby increasing the spatial difference between beams at different angles. This eliminates the need for additional magnification structures / optical designs, further simplifying the detection optical path of the cantilever.

[0032] The aforementioned atomic force microscopy system can be understood as a combination of sensing elements (such as the microscopic cantilever 111 and probe 112) and its optical deflection detection system (such as the laser 113 and detector 114). It should be noted that the optical components of this system are often specially designed based on the cantilever, and the cantilever and its measuring optics are generally combined into a single system. However, in practical applications, due to special needs, the two can exist independently, but the cantilever and its optical detection devices based on the design concept of this application are also within the scope of protection of this application.

[0033] The following will combine Figures 2-8 This application provides a further description of an atomic force microscopy system and its focusing lens structure.

[0034] Exemplary Atomic Force Microscopy System

[0035] To further illustrate the atomic force microscopy system provided in this application, a schematic diagram of the structure of an atomic force microscopy system is provided ( Figure 2 ).

[0036] like Figure 2 As shown, the atomic force microscopy system 200 provided in this application may include a light source 210, a cantilever 220, a focusing lens structure 230, and a position-sensitive detector 240. The initial light beam emitted by the light source 210 is focused by the focusing lens structure 230 onto the reflective surface of the cantilever 220, reflected by the reflective surface of the cantilever 220, and then enters the position-sensitive detector 240 through the focusing lens structure 230.

[0037] The light source 210 can be an optical device capable of emitting a light beam that meets the measurement requirements. The light source 210 can be an optical device that directly emits a light beam from a laser. The light source 210 can also be an optical device such as an optical fiber that can transmit the light beam. In the atomic force microscopy system 200, the initial light beam emitted by the light source 210 is generally required to be a laser with high monochromaticity, high stability, and low divergence.

[0038] In practical applications, the light source 210 often needs to pass through an optical interface perpendicular to the propagation direction of the initial beam when emitting the initial beam. For example, when emitting the initial beam through fiber coupling, the interface through which the fiber emits the initial beam is generally perpendicular to the propagation direction of the initial beam. Similarly, when the initial beam is modulated by optical devices such as a collimation module, the interface through which the initial beam is emitted is also generally perpendicular to the propagation direction of the initial beam.

[0039] The cantilever 220 is the main measurement structure of the atomic force microscopy system 200. It is generally fixed at one end to the displacement stage and has a probe at the other end. The probe is driven by the force between the probe and the object being measured, thus changing its shape (generally manifested as a tilt angle).

[0040] Considering the optical measurement of the deformation of the cantilever 220, a reflective material is coated on the surface of the cantilever 220 away from the object being measured (i.e., the side facing the light source) to form a reflective surface. This reflects the initial light beam emitted by the aforementioned light source 210. The initial light beam reflected by the reflective surface can be referred to as the reflected beam.

[0041] Based on the aforementioned morphological changes of the cantilever 220, the reflection position and angle of the initial beam on the reflective surface can also change, resulting in different reflection angles of the reflected beam. Correspondingly, when detecting the reflection of the reflected beam, the deformation of the cantilever can be inferred from the pre-calibrated bending conditions of the cantilever under different conditions, thereby further determining the surface condition of the measured object. For specific calculation processes, please refer to relevant technologies.

[0042] The focusing lens structure 230 can be a combination of optical elements (such as lenses) that can converge the initial light beam onto the reflective surface of the cantilever 220. Furthermore, the focusing lens structure 230 can be designed based on the reflected light beams at different angles, thus forming a tilt-invariant retroreflection system with the cantilever 220. This tilt-invariant retroreflection system is a special type of retroreflection system that maintains its retroreflection characteristics at different tilt angles; that is, the light is reflected back to its source regardless of the tilt angle.

[0043] Specifically, the reflective surface of the cantilever 220 can serve as a reflector for a tilt-invariant retroreflection system, while the focusing lens structure 230 is used to ensure its tilt-invariant retroreflection characteristics. That is, the focusing lens structure 230 can adjust reflected beams at different angles into beams that are spatially offset and in the same direction (denoted as the result beam).

[0044] The direction of the light beam emitted through the focusing lens structure 230 can be opposite to the incident direction when the light beam enters the focusing lens structure 230. That is, the propagation direction of the aforementioned result light beam from the focusing lens structure 230 is the opposite direction of the aforementioned initial light beam.

[0045] That is, based on the focusing lens structure 230, reflected beams with different angles can be converted into parallel beams offset along the same direction, thereby converting the angular characteristics of the reflected beams into the positional characteristics of the resulting beam. Therefore, in subsequent detection, based on the correspondence between the positional information of the resulting beam and the reflection angle of the pre-modulated reflected beam, the shape of the cantilever can be determined based on the detected beam's positional information.

[0046] In some embodiments, the focusing lens structure 230 can be configured based on the aforementioned requirements. For example, the reflected beams from the cantilever 220 in different configurations can be determined first, and then optical design can be performed based on these reflected beams to determine the combination of optical elements that can achieve the aforementioned modulation effect. For example, the focusing lens structure 230 can be an optical element such as a lens group, an aspherical lens, or a microlens array.

[0047] Considering that the initial beam is reflected at the reflecting surface, the initial beam and the reflected beam can be located on opposite sides of the reflection point, so that there is a clear partition between the initial beam and the result beam, so that the relevant components can be set accordingly.

[0048] The position-sensitive detector 240 can be a sensor used to detect the position information of the light beam. The position-sensitive detector 240 is typically configured as a four-quadrant photodetector. A four-quadrant detector is a semiconductor device based on the lateral photoelectric effect, capable of detecting the position of the incident light spot in two-dimensional space.

[0049] That is, when the aforementioned beam enters the position-sensitive detector 240, the position information of its spot can be determined, thereby determining the shape of the cantilever based on the aforementioned correspondence, determining the force between the probe and the object being measured, and then determining the surface morphology of the object being measured.

[0050] The position-sensitive detector 240 can be designed along the optical path of the result beam and perpendicular to the propagation direction of the result beam to acquire the result beam.

[0051] In practical applications, considering the scalability of the optical path and space constraints, a detector beam splitter 250 is often provided between the focusing lens structure 230 and the position-sensitive detector 240. Thus, the detector beam splitter 250 is positioned upstream of the position-sensitive detector 240 in the optical path of the resulting beam, so that after the resulting beam is emitted from the focusing lens structure 230, it first passes through the detector beam splitter 250 and is then split by the detector beam splitter 250 into the position-sensitive detector 240.

[0052] Based on this detector beam splitter, the atomic force microscopy system provided in this application has a certain degree of scalability, allowing the integration of other sensors to detect more information about the resulting beam. For example, an interferometer can be additionally installed downstream of the detector beam splitter 250. In this case, the initial beam can be split, allowing the interferometer to be positioned downstream of both the initial and resulting beam splits, so that it can simultaneously receive both the resulting and initial beams and use the initial beam as a reference beam for the resulting beam, thereby determining more spatial information about the cantilever 220.

[0053] In the aforementioned atomic force microscopy system 200, the focusing lens structure and the cantilever constitute a tilt-invariant retroreflection system. In this system, the focusing lens structure can adjust the reflected beams from the cantilever at different tilt angles into spatially staggered beams that travel in the same direction. Specifically, the exit direction of the beam from the focusing lens structure is parallel to and opposite to the incident direction of the beam entering the focusing lens structure.

[0054] Therefore, when detecting the reflected beam, the relevant sensors can be set based on the modulated direction of the reflected beam, so that the resulting beam emitted from different positions in the direction perpendicular to the propagation direction of the resulting beam will not diverge in space. Thus, setting the sensor based on this direction allows the relevant sensors to receive the beam reflected from the cantilever at a stable angle (i.e., the beam direction is perpendicular to its acquisition surface), reducing the detection difficulty of the sensor and simplifying the modulation optical path of the reflected beam.

[0055] In particular, the focusing lens structure can correct the direction of the beam while diverging the various beams, thereby increasing the spatial difference between beams at different angles, simplifying the optical path of the atomic force microscopy system, and further simplifying the detection optical path of the cantilever. The modulation optical path of the reflected beam typically includes a magnification structure (such as an optical lever), but this application can omit such a structure. Furthermore, as mentioned above, to obtain a large deflection of the reflected beam, the sensor distance is generally large relative to the reflective plane. Based on the aforementioned design, the aforementioned distance requirement can be eliminated.

[0056] To further illustrate the design requirements of the focusing lens structure, this application also provides a schematic diagram of the optical path of the focusing lens structure. Figure 3 ).

[0057] like Figure 3 As shown, based on the different functions of the two sides of the focusing lens structure 230, the focusing lens structure 230 includes an incident region 231 and an exit region 232. The incident region 231 is used to focus the initial beam, and the exit region 232 is used to refract and reflect the beam to form the result beam. Figure 3 The dotted horizontal dashed line reflects the optical axis of the focusing lens structure 230, which can be divided into two sides based on this optical axis.

[0058] The incident region 231 is located on the outgoing light path of the light source 210, meaning that the initial light beam emitted by the light source 210 along the outgoing light path will be focused onto the reflective surface via the incident region 231. The focusing effect of the incident region 231 on the initial light beam can be determined according to actual operational requirements. For example, initial light beams incident parallel to each other at different positions can be focused onto a focal point. In application, this focal point can be located on the reflective surface of the cantilever 220 so that initial light beams at different positions can be reflected at the aforementioned reflective surface.

[0059] The emission area 232 is set in the emission light path of the reflective surface, that is, the reflected light beam reflected by the reflective surface is emitted through the emission area 232 to form the result light beam.

[0060] The emission region 232 has two functions: it can diverge the reflected light beam to offset it in space; and it can adjust the propagation direction of the reflected light beam to a specified direction. After the above two processes, the resulting light beam is formed.

[0061] As an example only, Figure 3 In the middle, the incident light rays in the initial direction (thick dashed line) will be reflected by the cantilever 220 with two different deflection states and will be emitted from the exit region 232 in a direction parallel to and opposite to the incident light rays.

[0062] It should be noted that, Figure 3 The rotation of the cantilever 220 is only for illustration. In actual measurement, the end of the cantilever 220 away from the probe is often fixed, and its deflection will generally be in the form of bending or twisting.

[0063] In some embodiments, the exit region 232 can be implemented by at least one lens. The two functions mentioned above can be implemented by corresponding components. That is, the exit region 232 of the aforementioned focusing lens structure 230 may include a divergence component 2321 and a correction component 2322.

[0064] The diverging component 2321 is positioned towards the reflective surface and can be used to refract reflected beams at different angles to different positions of the correction component. The correction component 2322 is used to adjust the propagation angle of the reflected beam to a specified direction to form the resulting beam.

[0065] In some embodiments, the emission region 232 can be implemented based on an aspherical lens. In this case, the aforementioned divergence component 2321 can be the side of the aspherical lens facing the reflective surface, and the correction component 2322 can be the side of the aspherical lens away from the reflective surface. In component design, simulations can be performed based on cantilever at different angles to design the surface structure of the aspherical lens, thereby achieving the aforementioned functions.

[0066] In some embodiments, the aforementioned divergence component 2321 and correction component 2322 can also be implemented based on one or more optical elements (such as lenses, lens arrays, etc.). The design process generally also requires simulation design based on cantilever at different angles to achieve the aforementioned functions.

[0067] Considering the aforementioned design that divides the focusing lens structure 230 into sections, the aforementioned position-sensitive detector 240 can be placed on the outgoing optical path of the outgoing region to collect the resulting beam. The position-sensitive detector 240 can be directly connected to the optical path or perform beam splitting detection.

[0068] It should be noted that the optical design of the exit region 232 in the focusing lens structure 230 is generally related to the incident region 231, so that the incident direction and the exit direction of the light beam in the focusing lens structure 230 are parallel and opposite.

[0069] Parallel light interference and its countermeasures

[0070] Based on the aforementioned atomic force microscopy system, the propagation direction of the resulting beam emitted from the focusing lens structure is parallel to and opposite to that of the initial beam.

[0071] When the resulting beam enters the corresponding optical device through the reflecting interface, even if the reflecting interface is coated with an anti-reflective film, the resulting beam will still be reflected at the incident interface of the optical device (denoted as the reflecting interface), thus forming a reflected beam of the resulting beam that propagates in the opposite direction along the optical path of the resulting beam and reaches the exit position of the initial beam. Similar to the reflection of the resulting beam at the reflecting interface, a reflecting interface is also formed at the exit position of the initial beam, and the reflected beam of the resulting beam is double-reflected along the optical path of the initial beam at the reflecting interface. The focusing lens and the cantilever form a tilt-invariant retroreflector. Due to its tilt-invariant retroreflector effect, the original beam and the double-reflected beam are nearly ideally parallel. Since further reflections at the reflecting interface are also similar, multi-beam interference is formed, affecting the position-sensitive detector's measurement of the resulting beam.

[0072] It should be noted that, considering the subsequent content involves the deflection of the resulting beam, the aforementioned reflective interface can be understood as an optical element interface that is perpendicular to the propagation direction of the initial beam or perpendicular to the theoretical propagation direction of the resulting beam (i.e., the propagation direction in the theoretical case without deflection) in the optical path of the resulting beam.

[0073] To further illustrate this point, this application also provides a schematic diagram of the optical path of multiple beams. Figure 4 ).in, Figure 4 The optical path diagram shown can be a schematic diagram of the optical path between the reflective interface 410 and the reflective surface 420 of the cantilever.

[0074] Specifically, to depict the multiple reflected beams, this application sets the reflective interface 410 at an angle, whereas in practice it is generally perpendicular to the initial beam. Furthermore, to illustrate the process of the multiple reflected beams being split by the detector beam splitter to the position-sensitive detector, in Figure 4 The detector beam splitter 250 and the position-sensitive detector 240 are shown between the reflective interface 410 and the reflective surface 420 of the cantilever. It should be noted that... Figure 4The detector beam splitter 250 and position-sensitive detector 240 in the diagram are only schematic representations of their functions. In the actual optical path, the side of the detector beam splitter 250 facing the reflective surface 420 may also serve as the aforementioned reflective interface 410.

[0075] like Figure 4 As shown, the resulting beam L0 can be emitted from the reflecting interface 410, and reaches the reflecting surface 420 (which is actually the initial beam) through the focusing lens structure 230. It is reflected by the reflecting surface 420 to the focusing lens structure 230 (which is actually the reflected beam), and then emitted from the focusing lens structure 230 to the reflecting interface 410.

[0076] For a primary reflected beam L1, after it is reflected by the reflecting interface 410, it reaches the reflecting surface 420 through the focusing lens structure 230, is reflected on the reflecting surface 420, and then reaches the reflecting interface 410 again through the focusing lens structure 230.

[0077] After the primary reflected beam L1 reaches the reflecting interface 410, part of the beam will be reflected by the reflecting interface 410 to form a secondary reflected beam L2. The transmission path of the secondary reflected beam L2 is similar to that of the previously mentioned beam L0.

[0078] like Figure 4 As shown, in Figure 4 In the magnified partial views, considering the retroreflector effect, the angle α between the primary reflected beam L1 and the normal of the reflective interface 410 (i.e., the dotted horizontal lines in the figures; in subsequent figures, the dotted horizontal lines all reflect the optical axis / normal) is the same in both magnified partial views. Considering that the primary reflected beam L1 is formed by the reflection of the result beam L0 at the reflective interface 410, the secondary reflected beam L2 formed by reflecting the primary reflected beam L1 is theoretically nearly parallel to the result beam L0.

[0079] Therefore, based on the tilt-invariant retroreflection system formed by the focusing lens structure 230 and the cantilever 220, the propagation direction of the secondary reflected beam L2 is almost parallel to that of the result beam L0, thereby forming multi-beam interference in the position-sensitive detector 240.

[0080] It should be noted that not only the aforementioned secondary reflection beam L2 interferes with the resulting beam L0, but generally, even-numbered reflections between two interfaces will interfere with the resulting beam L0. However, considering energy loss, the interference of the secondary reflection beam L2 is the strongest, and this beam is used as an example here.

[0081] To overcome this interference, the parallel relationship between the resulting beam and the multiple reflected beams can be broken. Therefore, the atomic force microscopy system 200 can also include an anti-interference structure. The deflection effect of the anti-interference structure on the beam causes the angle between the beams to increase (greater than the angle between beams that can form interference), thereby avoiding the generation of interference.

[0082] Therefore, in order to avoid the result beam being affected by multiple reflections between the reflective interface and the reflective surface, which would affect the detection result of the position-sensitive detector, the atomic force microscopy system provided in this application is also equipped with an anti-interference structure. The anti-interference structure introduces additional deflection into the result beam, thereby increasing the angle between the beams and ensuring the detection accuracy of the position-sensitive detector.

[0083] In some embodiments, the anti-interference structure is generally implemented based on a transmission element, which is tilted within the resulting beam. When the resulting beam L0 enters the anti-interference structure, the angle between the resulting beam L0 and the anti-interference structure is different from the angle between the primary reflected beam L1 and the resulting beam L0 and the anti-interference structure when the primary reflected beam L1 is reflected back and enters the anti-interference structure. This results in different refraction angles of the anti-interference structure for the resulting beam L0 and the primary reflected beam L1, thereby introducing additional deflection into the resulting beam L0, which can break the parallel relationship between the resulting beam L0 and the multiple reflected beams.

[0084] As mentioned earlier, beam deflection is generally achieved through a transmission element. Among these, a commonly used transmission element is a parallel lens (also known as a parallel transmission plate). A parallel lens typically has two parallel surfaces. When a beam of light enters one of the surfaces at an angle, it is refracted by the parallel lens and exits from the other surface.

[0085] This application further discovers that even though the parallel lens refracts the emitted light beam, multiple reflections also occur within the parallel lens itself. When the parallel lens is used as an anti-interference structure, a parallel beam of the resulting light beam is still introduced, thereby interfering with the position-sensitive detector's detection of the resulting light beam.

[0086] To further illustrate the multiple reflections of a parallel lens, this application also provides a schematic diagram of the optical path of a parallel lens when transmitting a beam. Figure 5 ).

[0087] like Figure 5 As shown, when a parallel lens refracts light, the incident light passes through the lens to form transmitted light. However, even if the parallel lens is coated with an anti-reflection coating, the light beam will be reflected on its parallel surfaces, resulting in multiple reflections between the two parallel surfaces, thus forming multiple parallel reflected beams and multiple parallel transmitted beams.

[0088] When the parallel lens is set as an anti-interference structure, the aforementioned parallel reflected light and parallel transmitted light often act as interference beams in the result beam, thereby interfering with the detection results of the result beam.

[0089] Based on the foregoing, this application creatively discovers that the parallelism between reflected and transmitted light in a parallel lens is actually due to the consistency between the refraction and reflection laws of the light beams at different positions within the parallel lens. If the internal light rays at different positions within the element have different reflection angles or the light rays exiting the element have different refraction angles, the parallelism between reflected and transmitted light can be disrupted.

[0090] Therefore, in order to avoid introducing parallel beams into the resulting beam, the internal light reflection angles at different locations within the anti-interference structure are different and / or the light refraction angles at different locations within the anti-interference structure are different.

[0091] Based on the aforementioned properties of the anti-interference structure, optical elements with different internal light reflection angles at different locations within the anti-interference structure can be achieved using non-parallel lenses (lenses without two parallel surfaces, such as wedge lenses, triangular lenses, circular lenses, concave lenses, etc.). Conversely, different light refraction angles at different locations within the anti-interference structure can be achieved using optical elements such as graded-index lenses (GRIN lenses, where the internal refractive index gradually changes radially or axially).

[0092] In some embodiments, considering that the anti-interference structure introduces additional deflection into the resulting beam, the anti-interference structure should be positioned upstream of the device that forms the reflective interface in the optical path of the resulting beam. For example, the anti-interference structure can be positioned upstream of the detector beam splitter to introduce additional deflection into the resulting beam before it enters the detector beam splitter, thereby ensuring that the side of the detector beam splitter facing the cantilever does not form multiple reflected beams parallel to the resulting beam.

[0093] To further illustrate how the different internal light reflection angles at different locations within the anti-interference structure and / or the different light refraction angles at different locations within the anti-interference structure affect the elimination of the parallel relationship between incident and outgoing light, this application also provides a schematic diagram of the internal optical path of a wedge-shaped plate. Figure 6 ).

[0094] Similar to a parallel lens, a wedge-shaped plate also has two opposing surfaces, but the difference lies in the fact that the two surfaces are not parallel and instead have a wedge angle δ. Generally, the two sides of the wedge-shaped plate are perpendicular to one surface, while the other surface is considered to specifically possess the wedge angle δ. Alternatively, the wedge-shaped plate can be understood as a right trapezoid, with the hypotenuse of the trapezoid possessing the wedge angle δ. The surface with the wedge angle δ is referred to in this application as the wedge-shaped surface, and the opposite surface of the wedge-shaped surface is referred to as the horizontal surface.

[0095] like Figure 6As shown, when the incident light passes through the wedge, part of the beam is reflected for the first time on the wedge surface, and part of the beam is refracted and enters the interior of the wedge. When it is reflected again by the horizontal surface and reaches the wedge surface, the angle δ between the wedge surface and the horizontal surface causes the beam initially reflected from the upper surface of the wedge and the transmitted beam generated by multiple internal reflections to no longer be parallel to each other. This avoids the problem of multi-beam interference and ensures the detection accuracy of the position-sensitive detector for the result beam.

[0096] It should be noted that the aforementioned Figure 5 , Figure 6 This is merely a schematic diagram of the light beam to illustrate the internal light propagation of different transmission structures, and does not accurately represent the optical path structure. The reflection and refraction of light in the diagram are for illustrative purposes only and are not numerically precise.

[0097] In some embodiments, considering that reflected light from the incident interface of the optical element cannot be eliminated, and that the light incident side of the aforementioned anti-interference structure forms a non-90° tilt angle with the resulting beam, this application creatively reuses this light incident side as a detector beam splitter based on the reflection and transmission of the resulting beam by the light incident side. That is, the light incident side is coated with a transmission-reflection film and reused as a detector beam splitter; wherein the resulting beam is split by transmission and partial reflection at the light incident portion. The transmission-reflection film can be an optical coating that splits the beam into a transmission portion and a reflection portion based on a preset setting, generally exhibiting a semi-transmissive and semi-reflective film, and the specific transmission-reflection ratio can be adjusted according to needs and the actual coating material used.

[0098] To further illustrate the placement of the anti-interference structure in an atomic force microscopy system, this application uses a wedge as an example to describe an atomic force microscopy system based on the anti-interference structure, where the anti-interference structure is multiplexed as a detector beam splitter. Figure 7 ).

[0099] Figure 7 The atomic force microscopy system 200 shown is Figure 2 The atomic force microscopy system shown is similar to the 200. It differs from... Figure 2 The atomic force microscopy system 200 shown is... Figure 7 The atomic force microscopy system 200 shown does not have a detector beam splitter 250, but has an anti-interference structure 260.

[0100] like Figure 7As shown, the anti-interference structure 260 can be shaped like a wedge, with one of its wedge-shaped surface and horizontal surface serving as a beam splitter for the detector, where a transmission-reflection film can be deposited on the light incident side. When the resulting light beam reaches the light incident side of the anti-interference structure 260, it is split into a portion of the beam that passes through the light incident side and a portion of the beam that is reflected by the light incident side. The portion of the beam reflected by the light incident side can enter the position-sensitive detector 240, while the portion of the beam that passes through the light incident side is used for subsequent measurements.

[0101] Based on the aforementioned adjustment of the anti-interference structure 260, the angle between the beams after adjustment becomes larger (greater than the angle between beams that can form interference), thereby avoiding the generation of interference. Furthermore, the focusing positions of the light rays on the back of the cantilever 220 are staggered. The reflective interface 410 can be the incident surface of an optical device downstream of the anti-interference structure 260 in the optical path of the resulting beam (such as the incident surface of a beam splitter).

[0102] In some embodiments, to facilitate the setting of the position-sensitive detector 240, the angle between the light incident side and the result beam can be 45°. In this case, the position-sensitive detector 240 can be set horizontally toward the light incident side so that the angle between the incident surface of the sensitive detector 240 and the result beam is 90°.

[0103] In practical applications, other optical devices may be installed in the subsequent optical path of the resulting beam, and some of these devices may have certain requirements for the resulting beam. For example, when the interferometer receives the beam, the beam to be detected needs to be parallel and coincident with its reference beam. However, after the aforementioned deflection, the resulting beam is difficult to make parallel and coincident with the original reference beam, and adjustments are required.

[0104] Therefore, to avoid the deflection of the result beam by the aforementioned anti-interference structure 260 affecting subsequent detection (such as interferometry), a compensation element can also be provided in the atomic force microscope system. This compensation element can be used to compensate for the deflection of the result beam by the anti-interference structure 260.

[0105] In practical implementation, compensation for the deflection of the resulting beam can include two methods: ① removing the deflection of the resulting beam. ② applying the same deflection to other beams related to the resulting beam (such as the parametric beam of the resulting beam).

[0106] In particular, considering the reflection of the result beam by the reflective interface, when removing the deflection of the result beam based on the compensation structure, it is generally necessary to ensure that the subsequent optical path does not have a reflective interface perpendicular to the result beam, otherwise multiple reflections will occur.

[0107] In some embodiments, to further illustrate the role of the compensation element, this application also provides an atomic force microscopy system 200 based on the compensation element. For example...Figure 8 As shown, within the atomic force microscopy system 200, an interference sensor 280 is also provided in the subsequent optical path of the result beam. The initial beam can serve as a reference beam for the result beam and enters the interference sensor 280 in a horizontally overlapping manner.

[0108] To ensure that the initial beam and the resulting beam enter the interferometer sensor 280 in a horizontally coincident manner, the atomic force microscopy system 200 can also be equipped with multiple modulation devices (not shown in the figure). Considering that the modulation devices may form a reflecting surface perpendicular to the propagation direction of the resulting beam before deflection, Figure 8 In this process, the compensation element 270 can be placed in the optical path between the initial beam and the interference sensor 280, thereby adding the same deflection to the initial beam as to the result beam, so as to ensure that the two beams are parallel and coincident.

[0109] In some embodiments, for the aforementioned anti-interference structure 260 constructed based on a wedge, the compensation element 270 can be implemented using a wedge-shaped compensation piece with the same shape as the substrate and the wedge of the anti-interference structure 260. That is, the compensation element 270 can be generated from the same material and using the same manufacturing process as the wedge of the anti-interference structure 260, the difference being that their coatings are different. The compensation element 270 is often coated with an anti-reflective coating.

[0110] Therefore, the compensation element 270 can be set in the optical path of the initial beam based on the setting of the anti-interference structure 260 in the result beam (such as the same angle between the light and the device), so that the compensation element 270 adds the same deflection to the initial beam as the result beam.

[0111] Preferably, the horizontal surface of the anti-interference structure 260 can be oriented toward the focusing lens structure 230 and coated with a transmission and reflection film to be reused as a detector beam splitter.

[0112] At this time, the horizontal surface of the compensation element 270 is also set towards the initial beam, and the angle between the horizontal surface of the compensation element 270 and the initial beam should be consistent with the angle between the anti-interference structure 260 and the result beam, so that the result beam and the initial beam form the same deflection, and the split result beam and the initial beam coincide again before entering the interference sensor 280.

[0113] Therefore, based on the aforementioned setup, the interference of multiple beams on the resulting beam can be eliminated. Based on the aforementioned anti-interference structure setup, this application also conducted simulation tests, and the test results are as follows: Figure 8 .

[0114] Figure 9A , Figure 9B This can reflect the simulation results of two atomic force microscopy systems, one with and one without wedges, through optical design programs.Figure 9A The results of the position-sensitive detector in an atomic force microscopy system without a wedge are shown. Figure 9B The detection results of the position-sensitive detector of the atomic force microscopy system with wedge-shaped plates.

[0115] in, Figure 9A and Figure 9B The detection results specifically reflect the lateral distribution of coherent irradiance on a cross section of the position-sensitive sensor. Figure 9A and Figure 9B The x-coordinate (X-Coordinate in mm) reflects the position of the resulting beam within the position-sensitive sensor, in millimeters (mm). The y-coordinate (X-Coordinate in mm) reflects the position of the beam within the position-sensitive sensor. in Watt / cm 2 ): Represents coherent irradiation intensity, measured in watts per square centimeter (Watt / cm²). 2 ).

[0116] like Figure 9A As shown, the average peak-to-valley difference of coherent irradiance acquired by the position-sensitive detector of an atomic force microscope system without a wedge is approximately 0.05 W / cm², exhibiting significant multi-beam interference fluctuations. However, as... Figure 9B As shown, simulation results of the atomic force microscope system based on wedges demonstrate that the simulation results of coherent irradiance in the position-sensitive detector of the atomic force microscope system using wedges with a wedge angle of 0.5° no longer exhibit fluctuations, which can significantly reduce the influence of multi-beam interference and ensure measurement accuracy.

[0117] All of the above-mentioned optional technical solutions can be combined in any way to form optional embodiments of this application, and will not be described in detail here.

[0118] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0119] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0120] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0121] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0122] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0123] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program verification codes, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0124] It should be noted that in the description of this application, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0125] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications or equivalent substitutions made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An atomic force microscopy system, characterized by, The system comprises: a light source for emitting an initial light beam; a cantilever having a reflecting surface, the cantilever being configured to change a tilt angle based on an interaction force between a probe of the cantilever and a measurement object; the reflected light beam reflected from the reflecting surface has different angles when the cantilever is at different tilt angles; a focusing lens structure arranged between the cantilever and the light source for directing the initial light beam to the reflecting surface and adjusting the reflected light beams of different angles into result light beams that are spatially staggered and in the same direction, wherein the propagation direction of the result light beams is parallel and opposite to the propagation direction of the initial light beam; a position sensitive detector for detecting position information of the result light beams, the position information reflecting the change of the tilt angle of the cantilever; a detector beam splitter arranged upstream of the position sensitive detector along the light path of the result light beams for introducing the result light beams into the position sensitive detector; an anti-interference structure arranged obliquely on the light path of the result light beams for transmitting the result light beams, wherein the anti-interference structure is configured as a wedge-shaped sheet having opposite wedge-shaped surfaces and a horizontal surface, the wedge-shaped surfaces having a wedge angle relative to the horizontal surface, and the result light beams are refracted by the wedge-shaped sheet; an interference sensor for simultaneously detecting the initial light beam and the result light beam; and a wedge-shaped compensation sheet for compensating the deflection of the result light beams by the wedge-shaped sheet, wherein the wedge-shaped compensation sheet and the wedge-shaped sheet have the same shape as the substrate and the included angle of the initial light beam is consistent with the included angle of the anti-interference structure and the result light beam.

2. The atomic force microscopy system of claim 1, wherein, The internal light reflection angles of different positions in the anti-interference structure are different and / or the light refraction angles of different positions in the anti-interference structure are different.

3. The atomic force microscopy system of claim 2, wherein, The anti-interference structure is provided with a transmission reflection film on the light incident side facing the focusing lens structure and is multiplexed as the detector beam splitter; wherein the result light beams are partially transmitted and partially reflected at the light incident side to be split.

4. The atomic force microscopy system of claim 3, wherein, The included angle between the light incident side and the result light beams is 45°, and the included angle between the position sensitive detector and the result light beams is 90°. The result light beams are reflected by the light incident side to enter the position sensitive detector.

5. The atomic force microscopy system of claim 2, wherein, The atomic force microscopy system further comprises a compensation element for compensating the deflection of the result light beams by the anti-interference structure.

6. The atomic force microscopy system of claim 1, wherein, The horizontal surface of the anti-interference structure is arranged towards the focusing lens structure and is provided with a transmission reflection film to be multiplexed as the detector beam splitter.

7. The atomic force microscopy system of claim 1, wherein, The focusing lens structure comprises an incident region and an exit region; The incident region is arranged on the exit light path of the light source for focusing the initial light beam to the reflecting surface; The exit region is arranged on the exit light path of the reflecting surface for diverging the reflected light beam and adjusting the propagation direction of the reflected light beam to a target direction to form the result light beam; The position sensitive detector is arranged on the exit light path of the exit region to collect the result light beam.

Images