Atomic force microscope system

Abstract

The invention provides an atomic force microscopy system, and relates to the field of optical detection. According to the atomic force microscopy system provided by the invention, the focusing lens structure and the reflective surface of the cantilever form an inclined invariant retroreflection system, and different-angle reflected light beams reflected by the cantilevers with different inclined angles are adjusted into light beams which are staggered in space and are in the same direction. Therefore, when the reflected light beam is detected, the related sensor can be arranged based on the modulated direction of the reflected light beam, so that the related sensor can receive the light beam reflected by the cantilever at a stable angle, and the detection difficulty of the sensor is reduced. Besides, in order to prevent multiple reflections of the result light beam between the reflection interface and the light reflection surface from influencing the detection result of the position sensitive detector on the result light beam, the atomic force microscopic system provided by the invention is also provided with an anti-interference structure, and the anti-interference structure introduces additional deflection for the result light beam, so that the detection result of the result light beam is more accurate. And the detection precision of the position sensitive detector on the result light beam is ensured.

Description

Technical Field

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

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

[0003] An atomic force microscope has a cantilever with one end fixed and a probe at the other end. When there is a force between the probe tip and the object being measured, the cantilever will deflect slightly. By detecting these deflections, an image of the surface topography of the 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 that needs to be solved urgently by those skilled in the art. Summary of the invention

[0005] In view of this, an embodiment of the present application provides an atomic force microscopy system, which uses 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 includes 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 force between the probe of the cantilever and the measured object. When the cantilever is at different tilt angles, the angles of the reflected light beams reflected from the reflective surface by the initial light beam are different. 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 at different angles to result light beams that are staggered in space and along the same direction, wherein the propagation direction of the result light beam is parallel to 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 used to introduce the result light beam into the position-sensitive detector along the optical path of the result light beam. The anti-interference structure is arranged to be tilted on the optical path of the result light beam, and is used to transmit the result light beam.

[0007] Based on the embodiment of the present application, an atomic force microscope system is provided, which forms a tilt-invariant retroreflection system by focusing the lens structure and the reflective surface of the cantilever, and adjusts the reflected light beams of different angles reflected by the cantilever with different tilt angles to light beams that are staggered in space and along the same direction. Therefore, when detecting the reflected light beam, the relevant sensor can be set based on the direction of the modulated reflected light beam, so that the relevant sensor can receive the light beam reflected by the cantilever at a stable angle, reducing the detection difficulty of the sensor. In addition, in order to avoid the multiple reflections of the result light beam between the reflective interface and the reflective surface affecting the detection result of the result light beam by the position-sensitive detector, an anti-interference structure is also provided in the atomic force microscope system provided by the present application, and the anti-interference structure introduces additional deflection to the result light beam to ensure the detection accuracy of the result light beam by the position-sensitive detector. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

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

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

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

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

[0013] Figure 5 Schematic diagram of the internal optical path of a wedge provided in some embodiments of the present application.

[0014] Figure 6 Schematic diagram of the internal optical path of a wedge provided in some embodiments of the present application.

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

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

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

[0018] Among them, 110, atomic force microscope; 111, micro cantilever; 112, probe; 113, laser; 114, detector; 120, measurement object; 200, atomic force microscope 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, reflection interface; 420, reflective surface. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0020] Application Overview:

[0021] In AFM, the angular changes (bending and twisting) of the cantilever can be detected by many different techniques, such as piezoresistance, piezoelectricity, and optical beam deflection (OBD).

[0022] Considering the fast response speed and low cost of beam deflection, beam deflection is a more commonly used detection method in cantilever detection.

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

[0024] like Figure 1 As shown, the atomic force microscope 110 may include a micro cantilever 111 and a probe 112 disposed at one end of the micro cantilever 111. The probe 112 may drive the micro cantilever 111 to change its tilt angle based on the force between the probe 112 and the measurement object 120. The force between the probe 112 and the measurement object 120 may be set according to the actual scene. For example, the force between the probe 112 and the measurement object 120 may be atomic force, charge force, pressure, etc.

[0025] In some embodiments, the optical deflection detection system can detect the morphological change of the micro cantilever 111 by the reflection of the light beam on the micro cantilever 111. The back side of the micro cantilever 111 (the surface away from the measurement object 120) can be coated with a reflective coating to reflect the irradiated light beam.

[0026] The aforementioned atomic force microscope 110 may also include an optical deflection detection system to detect the deflection of the micro cantilever 111. Specifically, the atomic force microscope 110 may also include a laser 113 and a detector 114. Among them, the laser 113 can be used as a light source of the optical deflection detection system to emit a light beam to the back of the micro cantilever 111. After the light beam is emitted from the laser 113, it is reflected by the back of the micro cantilever 111 and enters the detector 114. The detector 114 (such as a position sensitive sensor) can be used to detect the position of its reflected light beam when it enters the detector 114, and determine the morphological change of the micro cantilever 111 corresponding to the current light beam reflection position through a pre-calibrated corresponding relationship. Combined with the corresponding relationship between the morphological change of the micro cantilever 111 and the measurement object 120, the surface structure of the measurement object 120 is determined to achieve the measurement of the surface of the measurement object 120 at that location.

[0027] In addition, the atomic force microscope 110 may further include a frame for fixing the end of the micro cantilever 111 away from the probe 112 and a moving stage on the frame, so as to scan the surface of the measurement object 120 .

[0028] However, in the aforementioned scenario, considering that the deflection of the microscopic cantilever 111 is small, the initial deflection of the light beam reflected by the microscopic cantilever 111 is small, and the aforementioned detector 114 often needs to detect the light beam at a longer distance to increase the discrimination of the light beam. However, this setting will cause the light beam to be distributed at more angles in space, and it is difficult for the detector 114 to detect the light beam reflected at various deflection angles over a large range.

[0029] Based on the above technical problems, the present application provides an atomic force microscope system and a focusing lens structure thereof. Through a specially configured focusing lens structure, the focusing lens structure and the cantilever in the atomic force microscope system form a tilt-invariant retroreflection system.

[0030] In the tilt-invariant retroreflective system, the focusing lens structure can adjust the reflected light beams at different angles reflected by the cantilever at different tilt angles into light beams that are staggered in space and along the same direction. Therefore, when detecting the reflected light beam, the relevant sensor can be set based on the direction of the modulated reflected light beam, so that the relevant sensor can receive the light beam reflected by the cantilever at a stable angle, which reduces the detection difficulty of the sensor and simplifies the modulation optical path of the reflected light beam.

[0031] In addition, the focusing lens structure can correct the direction of the light beam while diverging each light beam to increase the difference in space between light beams at different angles. No additional amplification structure / optical design is required, further simplifying the detection optical path of the cantilever.

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

[0033] The following will be combined Figure 2 to Figure 8 The present application provides an atomic force microscope system and a focusing lens structure thereof for further explanation.

[0034] Exemplary Atomic Force Microscopy System:

[0035] To further illustrate the atomic force microscopy system provided by the present application, the present application provides a structural schematic diagram of an atomic force microscopy system ( Figure 2 ).

[0036] like Figure 2 As shown, the atomic force microscope system 200 provided in the present application may include a light source 210, a cantilever 220, a focusing lens structure 230, and a position sensitive detector 240. The light source 210 releases an initial light beam which is focused on the reflective surface of the cantilever 220 by the focusing lens structure 230, and is reflected by the reflective surface of the cantilever 220, and enters the position sensitive detector 240 through the focusing lens structure 230.

[0037] The light source 210 may be an optical device that can release a light beam that meets the measurement requirements. The light source 210 may be an optical device that can directly release a light beam such as a laser. The light source 210 may also be an optical device that can transmit a light beam, such as an optical fiber. In the atomic force microscope system 200, the initial light beam released 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 light beam when releasing the initial light beam. For example, when the initial light beam is released through optical fiber coupling, the interface of the optical fiber releasing the initial light beam is generally perpendicular to the propagation direction of the initial light beam. For another example, when the initial light beam is modulated by an optical device such as a collimator module, the release interface of the initial light beam is generally also perpendicular to the propagation direction of the initial light beam.

[0039] The cantilever 220 is the main measurement structure of the atomic force microscope system 200. Generally, one end of the cantilever is fixed on the translation stage, and the other end is provided with a probe. Thus, the cantilever is driven by the force between the probe of the cantilever and the measurement object to change its shape (generally manifested as a tilt angle).

[0040] Considering the optical measurement of the deformation of the cantilever 220, the surface of the cantilever 220 away from the measurement object (i.e., the side facing the light source) is coated with a reflective material to form a reflective surface, thereby reflecting the initial light beam released by the light source 210. The initial light beam reflected by the reflective surface can be recorded as a reflected light beam.

[0041] Based on the aforementioned change in the shape of the cantilever 220, the reflection position and reflection angle of the initial light beam on the reflective surface may also change, resulting in different reflection angles of the reflected light beam. Correspondingly, when detecting the reflection of the reflected light beam, the deformation of the cantilever can be reversely calculated based on the pre-calibrated bending conditions of the cantilever under different conditions, thereby further determining the surface condition of the measured object. The specific calculation process can be referred to the relevant technology.

[0042] The focusing lens structure 230 may be a combination of optical elements (such as lenses) that can converge the aforementioned initial light beam to the reflective surface of the cantilever 220. In addition, the focusing lens structure 230 may also be designed based on the aforementioned reflected light beams at different angles, thereby forming a tilt-invariant retroreflective system with the cantilever 220. The tilt-invariant retroreflective system is a special retroreflective system that can maintain retroreflective properties at different tilt angles, that is, light is reflected back to its source without being affected by the tilt angle.

[0043] Specifically, the reflective surface of the cantilever 220 can be used as a reflector of the tilt-invariant retroreflective system, and the focusing lens structure 230 is used to ensure its tilt-invariant retroreflective characteristics. That is, the focusing lens structure 230 can adjust the reflected light beams at different angles into light beams that are staggered in space and along the same direction (referred to as result light beams).

[0044] The direction of the light beam transmitted through the focusing lens structure 230 may be opposite to the incident direction of the light beam when entering the focusing lens structure 230. That is, the propagation direction of the result light beam from the focusing lens structure 230 is opposite to the direction of the initial light beam.

[0045] That is, based on the focusing lens structure 230, the reflected light beams with different angles can be converted into parallel light beams staggered in the same direction, thereby converting the angle characteristics of the reflected light beams into the position characteristics of the result light beams. Therefore, in subsequent detection, based on the corresponding relationship between the position information of the result light beam and the reflection angle of the reflected light beam before modulation, the shape of the cantilever can be determined based on the position information of the detected light beam.

[0046] In some embodiments, the focusing lens structure 230 can be set based on the above requirements. For example, the reflected light beam reflected by the cantilever 220 in different forms can be determined first, and then the optical design can be performed based on the reflected light beam, so as to determine the combination of optical elements that can achieve the above modulation effect. For example, the focusing lens structure 230 can be presented as an optical element such as a lens group, an aspherical lens, a microlens array, etc.

[0047] Considering that the aforementioned initial light beam is reflected at the reflecting surface, the initial light beam and the reflected light beam can be located on both sides of the reflecting place, so that there is an obvious partition between the initial light beam and the result light beam, so that the relevant elements can be arranged accordingly.

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

[0049] That is, when the above-mentioned result light beam enters the position sensitive detector 240, the position information of its light spot can be determined, so as to determine the shape of the cantilever based on the above-mentioned corresponding relationship, determine the force between the probe and the measurement object, and then determine the surface shape of the measurement object.

[0050] The position sensitive detector 240 may be designed along the optical path of the result light beam and perpendicular to the propagation direction of the result light beam to collect the result light beam.

[0051] In practical applications, considering the scalability of the optical path and space limitations, 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 provided upstream of the position sensitive detector 240 in the optical path of the result light beam, so that after the result light beam is emitted from the focusing lens structure 230, it first passes through the detector beam splitter 250 and is split by the detector beam splitter 250 into the position sensitive detector 240.

[0052] Based on the detector beam splitter, the atomic force microscopy system provided by the present application has a certain degree of scalability, so that other sensors can be incorporated to detect more information of the result beam. For example, an interferometer can be additionally arranged downstream of the detector beam splitter 250, and the initial beam can be split at this time, so that the interferometer is arranged downstream of the initial beam splitting and the result beam splitting to simultaneously receive the result beam and the initial beam, and use the initial beam as a reference beam of the result beam to determine more spatial information of the cantilever 220.

[0053] In the aforementioned atomic force microscope 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 light beams at different angles reflected by the cantilever at different tilt angles into light beams that are staggered in space and along the same direction. The exit direction of the light beam from the focusing lens structure is parallel to and opposite to the incident direction of the light beam entering the focusing lens structure.

[0054] Therefore, when detecting the reflected light beam, the relevant sensor can be set based on the direction of the reflected light beam after modulation, so that the result light beam emitted from different positions in the vertical direction of the propagation direction of the result light beam will not diverge in space. Therefore, the sensor is set based on this direction. The relevant sensor can receive the light beam reflected by the cantilever at a stable angle (that is, the direction of the light beam is perpendicular to its collection surface), which reduces the detection difficulty of the sensor and simplifies the modulation optical path of the reflected light beam.

[0055] In particular, the focusing lens structure can diverge each light beam while correcting the direction of the light beam, thereby increasing the difference in space between light beams at different angles, simplifying the optical path of the atomic force microscope system, and further simplifying the detection optical path of the cantilever. Among them, the modulated optical path of the reflected light beam generally includes an amplification structure for the reflected light beam (such as an optical lever), and this type of structure can be omitted in the present application. In addition, as mentioned above, in order to obtain a larger deflection of the reflected light beam, the distance between the sensor and the reflective plane is generally larger. Based on the above design, the above distance requirement can be removed.

[0056] To further illustrate the design requirements of the focusing lens structure, the present application also provides a light path schematic diagram 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 area 231 and an exit area 232. The incident area 231 is used to focus the initial light beam, and the exit area 232 is used to refract the reflected light beam to form a result light 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 the optical axis.

[0058] The incident area 231 is arranged on the outgoing light path of the light source 210, that is, the initial light beam released by the light source 210 along the outgoing light path will be focused onto the reflective surface through the incident area 231. The focusing effect of the incident area 231 on the initial light beam can be determined according to actual operation requirements. For example, the initial light beams captured in parallel by the incident area 231 at different positions can be focused to a focal point, and in application, the focal point can be set on the reflective surface of the cantilever 220, so that the initial light beams at different positions can be reflected at the aforementioned reflective surface.

[0059] The exit area 232 is arranged on the exit light path of the reflective surface, that is, the reflected light beam reflected by the reflective surface is emitted through the exit area 232, thereby forming a result light beam.

[0060] The exit region 232 has two functions: the exit region 232 can diverge the reflected light beam so that it is staggered in space; and the exit region 232 can also adjust the propagation direction of the reflected light beam to a specified direction. After the above two processes, a result light beam is formed.

[0061] For example only, Figure 3 In the figure, the incident light (thick dashed line) in the initial direction will be emitted from the emission area 232 in a direction parallel to and opposite to the incident light after being reflected by the cantilever 220 in two different deflection states.

[0062] It should be noted that Figure 3 The rotation of the cantilever 220 is only a schematic representation. In actual measurement, the end of the cantilever 220 away from the probe is often fixed, and its deflection generally presents a bending or twisting state.

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

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

[0065] In some embodiments, the exit region 232 can be implemented based on an aspheric lens. In this case, the diverging component 2321 can be the side of the aspheric lens facing the reflective surface, and the correction component 2322 can be the side of the aspheric lens away from the reflective surface. In the component design, simulation can be performed based on cantilevers at different angles to design the surface structure of the aspheric lens, thereby realizing the aforementioned functions.

[0066] In some embodiments, the diverging component 2321 and the correcting component 2322 may 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 cantilevers at different angles to achieve the aforementioned functions.

[0067] Considering the above design will focus on the partition of the lens structure 230, the position sensitive detector 240 can be set on the outgoing light path of the outgoing area to collect the result light beam. The position sensitive detector 240 can be directly connected to the light path or can 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 associated with the incident region 231 , so that the incident direction of the light beam in the focusing lens structure 230 is parallel to and opposite to the exit direction.

[0069] Parallel light interference and its anti-interference structure:

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

[0071] When the result light beam passes through the reflection interface and enters the corresponding optical device, even if the reflection interface is coated with an anti-reflective film, the result light beam will be reflected at the incident interface of the optical device (referred to as the reflection interface), thereby forming a reflected light beam of the result light beam and propagating in the opposite direction along the optical path of the result light beam to reach the exit position of the initial light beam. Similar to the reflection of the result light beam at the reflection interface mentioned above, a reflection interface will also be formed at the exit position of the initial light beam, and the reflected light beam of the result light beam will be doubly reflected at the reflection interface at the initial light beam along the optical path of the initial light beam. The focusing lens and the cantilever form a tilt-invariant retroreflector. Due to its tilt-invariant retroreflector effect, the original light beam and the doubly reflected light beam are nearly ideally parallel. Since the further reflection on the reflection interface is also the same, multi-beam interference is formed, which affects the measurement of the result light beam by the position-sensitive detector.

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

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

[0074] In particular, in order to draw out the multiple reflected light beams, the present application sets the reflective interface 410 at an angle, while in practice it is generally perpendicular to the initial light beam. In addition, in order to show the process of the multiple reflected light beams being split by the detector beam splitter to the position sensitive detector, 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 the position sensitive detector 240 are merely illustrative of their functions. In an 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 light beam L0 can be emitted from the reflective interface 410, and reaches the reflective surface 420 (actually the initial light beam here) through the focusing lens structure 230, and is reflected to the focusing lens structure 230 (actually the reflected light beam here) by the reflective surface 420, and is emitted from the focusing lens structure 230 to reach the reflective interface 410.

[0076] For the once reflected light beam L1 , after being reflected by the reflective interface 410 , it reaches the reflective surface 420 via the focusing lens structure 230 , is reflected on the reflective surface 420 , and then reaches the reflective interface 410 again via the focusing lens structure 230 .

[0077] After the primary reflected light beam L1 reaches the reflective interface 410, part of the light beam will be reflected by the reflective interface 410 to form a secondary reflected light beam L2. The transmission path of the secondary reflected light beam L2 is similar to the transmission path of the aforementioned result light beam L0.

[0078] like Figure 4 As shown, in Figure 4 In the partial enlarged diagram of FIG. 4 , considering the retroreflector effect, in the two partial enlarged diagrams, the angle α between the primary reflected light beam L1 and the normal line of the reflective interface 410 (i.e., the dotted horizontal pattern line in the diagram, and the dotted horizontal pattern lines in the subsequent figures all reflect the optical axis / normal line) is the same. Considering that the primary reflected light beam L1 is formed by the reflection of the result light beam L0 on the reflective interface 410, the secondary reflected light L2 formed by the reflection of the primary reflected light beam L1 is theoretically nearly parallel to the result light 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 light beam L2 is nearly parallel to the result light beam L0 , thereby forming multi-beam interference in the position sensitive detector 240 .

[0080] It should be noted that it is not only the aforementioned secondary reflected beam L2 that interferes with the result beam L0. Generally speaking, even-numbered reflections between two interfaces will interfere with the result beam L0. However, considering the energy loss, the interference of the secondary reflected beam L2 is the strongest, and this beam is only taken as an example here.

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

[0082] Therefore, in order to avoid the multiple reflections of the result light beam between the reflective interface and the reflective surface affecting the detection results of the result light beam by the position-sensitive detector, an anti-interference structure is also provided in the atomic force microscopy system provided in the present application. The anti-interference structure introduces additional deflection to the result light beam, thereby increasing the angle between the light beams and ensuring the detection accuracy of the result light beam by the position-sensitive detector.

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

[0084] As mentioned above, adding deflection to a light beam is generally done through a transmission element. Among them, the more commonly used transmission element is a parallel lens (also called a parallel transmission sheet, etc.). A parallel lens generally has two parallel surfaces. When a light beam obliquely enters one of the surfaces, it will be refracted by the parallel lens and emitted from the other surface.

[0085] The present application further found that even if the parallel lens refracts the outgoing light beam, multiple reflections will be formed inside the parallel lens. When the parallel lens is used as an anti-interference structure, a parallel beam of the result light beam will still be introduced, thereby interfering with the detection of the result light beam by the position sensitive detector.

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

[0087] like Figure 5 As shown in FIG. 1 , when the parallel lens refracts, the incident light passes through the parallel lens to form transmitted light. However, even if the parallel lens is coated with an anti-reflection coating, the light beam will be reflected by the parallel surface, thereby performing multiple reflections between the two parallel surfaces, thereby forming multiple parallel reflected lights and multiple parallel transmitted lights.

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

[0089] Based on the above situation, the present application creatively discovered that the parallelism of reflected light and transmitted light in a parallel lens is actually formed because the refraction law and reflection law of light beams at different positions of the parallel lens are consistent. If the internal light reflection angles at different positions in the element are different or the light refraction angles of the light emitted from the element are different, the parallelism of reflected light and transmitted light can be destroyed.

[0090] Therefore, in order to avoid additional introduction of parallel light beams into the result light beam, the internal light reflection angles at different positions in the anti-interference structure are different and / or the light refraction angles at different positions in the anti-interference structure are different.

[0091] Based on the properties of the aforementioned anti-interference structure, the optical elements with different internal light reflection angles at different positions in the anti-interference structure can be realized by non-parallel lenses (lenses without two parallel surfaces, such as wedge lenses, triangular lenses, circular lenses, concave lenses, etc.). The different light refraction angles at different positions in the anti-interference structure can be realized by optical elements such as gradient refractive index lenses (GRIN lenses, the internal refractive index gradually changes along the radial or axial direction).

[0092] In some embodiments, considering that the anti-interference structure introduces additional deflection to the result light beam, the anti-interference structure should be arranged upstream of the device that forms the reflective interface in the optical path of the result light beam. For example, the anti-interference structure can be arranged upstream of the detector beam splitter so that the result light beam introduces additional deflection to the result light beam before entering the detector beam splitter, thereby ensuring that the side of the detector beam splitter facing the cantilever does not form a multiple reflection beam parallel to the result light beam.

[0093] To further illustrate that different internal light reflection angles at different positions in the anti-interference structure and / or different light refraction angles at different positions in the anti-interference structure eliminate the parallel relationship between the incident light and the outgoing light, the present application also provides a schematic diagram of the internal light path of a wedge-shaped piece ( Figure 6 ).

[0094] The wedge is similar to a parallel lens and also has two surfaces arranged opposite to each other, but the difference is that the two surfaces are not parallel and there is a wedge angle δ between them. The two sides of the wedge are generally perpendicular to one surface, and the other surface is regarded as having the wedge angle δ. It can also be understood that the wedge can be presented as a right-angled trapezoid, and the hypotenuse of the right-angled trapezoid has the wedge angle δ. The surface with the wedge angle δ is recorded as a wedge surface in this application, and the opposite surface of the wedge surface is recorded as a horizontal surface.

[0095] like Figure 6As shown in the figure, when the incident light passes through the wedge, part of the light beam is reflected on the wedge surface for the first time, and part of the light beam is refracted into the interior of the wedge, and then reaches the wedge surface again after being reflected by the horizontal surface. Since there is an angle δ between the wedge surface and the horizontal surface, the light beam initially reflected on the upper surface of the wedge and the transmitted light beam generated by multiple reflections inside are no longer parallel to each other, thereby avoiding the problem of multi-beam interference, and thus ensuring the detection accuracy of the result light beam by the position sensitive detector.

[0096] It should be noted that the above Figure 5 , Figure 6 It is only a schematic diagram of the light beam to reflect the internal light propagation of different transmission structures, and cannot accurately reflect the optical path structure. The reflection and refraction of the light in the figure are only for illustration and are not numerically accurate.

[0097] In some embodiments, it is considered that the reflected light of the incident interface of the optical element cannot be eliminated, and the light incident side of the aforementioned anti-interference structure forms a non-90° inclination angle with the result light beam. The present application creatively reuses the light incident side, and based on the reflection and transmission of the result light beam by the light incident side, the light incident side is multiplexed as a detector beam splitter. That is, the light incident side is coated with a transmissive-reflective film and is multiplexed as a detector beam splitter; wherein the result light beam is split by transmitting in the light incident part and reflecting in part. The transmissive-reflective film can be an optical coating that splits a light beam into a transmissive part and a reflective part based on a preset setting, and is generally presented as a semi-transmissive and semi-reflective film, and the specific transmissive-reflective ratio can be adjusted according to needs and the actual coating material used.

[0098] To further illustrate the arrangement of the anti-interference structure in the atomic force microscope system, this application takes a wedge-shaped piece as an example to illustrate an atomic force microscope system based on the anti-interference structure and multiplexing the anti-interference structure as a detector beam splitter ( Figure 7 ).

[0099] Figure 7 The atomic force microscope system 200 shown is Figure 2 The atomic force microscope system 200 shown is similar. Figure 2 The atomic force microscope system 200 shown, Figure 7 The atomic force microscope system 200 shown is not provided with a detector beam splitter 250 , but is provided with an anti-interference structure 260 .

[0100] like Figure 7As shown, the anti-interference structure 260 can be presented as a wedge-shaped piece, and one of its wedge-shaped surface and horizontal surface can be used as a detector beam splitter by coating a transmissive reflective film on the light incident side. When the result light beam reaches the light incident side of the anti-interference structure 260, it will be split into a partial light beam passing through the light incident side and a partial light beam reflected by the light incident side. Among them, the partial light beam reflected by the light incident side can enter the position sensitive detector 240, and the partial light beam passing through the light incident side will be used for subsequent measurement.

[0101] Based on the adjustment of the anti-interference structure 260, the angle between the light beams becomes larger (greater than the angle between the light beams that can form interference), thereby avoiding the generation of interference. In addition, the focusing positions of the light beams on the back of the cantilever 220 are staggered from each other. Among them, 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 result light 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 light 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 sensitive detector 240 (the incident surface) and the result light beam is 90°.

[0103] In practical applications, other optical devices may be set in the subsequent optical path of the result beam, and some optical devices may have certain requirements for the result beam. For example, when the interferometer receives the light beam, the detected light beam needs to be parallel to and coincide with its reference beam, but after the result beam is deflected as mentioned above, it is difficult to be parallel to and coincide with the original reference beam, and adjustment is required.

[0104] Therefore, in order to prevent the deflection of the result beam by the anti-interference structure 260 from affecting subsequent detection (such as interferometer), a compensation element can be provided in the atomic force microscope system. The compensation element can be used to compensate for the deflection of the result beam by the anti-interference structure 260.

[0105] In actual implementation, the compensation for the deflection of the result beam may include two methods: ① removing the deflection of the result beam; ② performing the same deflection of the result beam on other beams related to the result beam (such as the parameter beam of the result beam).

[0106] Among them, considering the reflection of the result light beam by the reflection interface, when removing the deflection of the result light beam based on the compensation structure, it is generally necessary to ensure that the subsequent optical path no longer has a reflection interface perpendicular to the result light beam, otherwise multiple reflected lights will appear.

[0107] In some embodiments, to further illustrate the role of the compensation element, the present application also provides an atomic force microscopy system 200 based on the compensation element. Figure 8 As shown, an interference sensor 280 is further arranged in the subsequent optical path of the result light beam in the atomic force microscope system 200. The initial light beam can be used as a reference light of the result light beam and enter the interference sensor 280 in a form of horizontal overlap with the result light beam.

[0108] In order to ensure that the initial light beam and the result light beam enter the interference sensor 280 in a horizontally overlapping form, the atomic force microscope system 200 can also be provided with a plurality of modulation devices (not shown in the figure). Considering that the modulation device may form a reflection surface perpendicular to the propagation direction of the result light beam before deflection, Figure 8 In the embodiment, the compensation element 270 can be arranged in the optical path between the initial light beam and the interference sensor 280, so as to add the same deflection to the initial light beam as the result light beam to ensure that the two light beams are parallel and coincident.

[0109] In some embodiments, for the aforementioned anti-interference structure 260 constructed based on a wedge-shaped piece, the compensation element 270 can be implemented by a wedge-shaped compensation piece having the same shape as the substrate and the wedge-shaped piece of the anti-interference structure 260. That is, the compensation element 270 can be produced based on the same material and the same preparation process as the wedge-shaped piece of the anti-interference structure 260, and the difference lies in the different coatings of the two. Among them, the compensation element 270 is often plated with an anti-reflection coating.

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

[0111] Preferably, the horizontal surface of the anti-interference structure 260 may be arranged toward the focusing lens structure 230 and coated with a transmissive reflective film to be reused as a detector beam splitter.

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

[0113] Therefore, based on the above settings, the interference effect of multiple light beams on the result light beam can be eliminated. Based on the setting of the above anti-interference structure, the present application also conducted a simulation test, and the test results are as follows: Figure 8 .

[0114] Fig.9A , Fig. 9B The simulation results of two atomic force microscope systems with or without wedges can be reflected in the figure. Fig.9A These are the detection results of the position sensitive detector of the atomic force microscope system without a wedge. Fig. 9B Results of the position sensitive detector test for the atomic force microscope system with the wedge set up.

[0115] in, Fig.9A and Fig. 9B The detection result specifically reflects the lateral distribution of coherent irradiance on a cross section in the position sensitive sensor. Fig.9A and Fig. 9B The horizontal axis (X-Koordinate in mm) reflects the position of the result beam in the position sensitive sensor, and the unit is millimeter (mm). The vertical axis (Koherente in Watt / cm 2 ): Indicates the coherent radiation intensity, the unit is Watt per square centimeter (Watt / cm 2 ).

[0116] like Fig.9A As shown in Figure 1, the average peak-to-valley difference of the coherent irradiance collected in the position sensitive detector of the atomic force microscope system without a wedge is about 0.05 W / cm2, and there is obvious multi-beam interference fluctuation. Fig. 9B As shown, the simulation results of the wedge-based atomic force microscope system show that there is no fluctuation in the simulation results of the coherent irradiance in the position sensitive detector of the atomic force microscope system using a wedge with a wedge angle of 0.5°, which can significantly reduce the influence of multi-beam interference and ensure measurement accuracy.

[0117] All the above optional technical solutions can be arbitrarily combined to form optional embodiments of the present application, and will not be described one by one here.

[0118] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example 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 performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

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

[0120] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

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

[0122] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0123] If the functions are implemented in the form of 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 the present application can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium, including several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program check codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[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 cannot be understood as indicating or implying relative importance. In addition, in the description of this application, unless otherwise specified, the meaning of "plurality" is two or more.

[0125] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. An atomic force microscope system, characterized in that: include: a light source, for emitting an initial light beam; A cantilever having a reflective surface, wherein the cantilever is configured to change a tilt angle based on a force between a probe of the cantilever and a measurement object; when the cantilever is at different tilt angles, the angle of the reflected light beam reflected from the reflective surface by the initial light beam is different; A focusing lens structure, disposed between the cantilever and the light source, for guiding the initial light beam to the reflective surface, and adjusting the reflected light beams at different angles into result light beams that are staggered in space and along the same direction, wherein the propagation direction of the result light beam is parallel to and opposite to the propagation direction of the initial light beam; A position sensitive detector, used to detect position information of the result light beam, wherein the position information reflects a change in the tilt angle of the cantilever; a detector beam splitter, disposed upstream of the position sensitive detector along the optical path of the result light beam, for introducing the result light beam into the position sensitive detector; and The anti-interference structure is arranged obliquely on the optical path of the result light beam and is used for transmitting the result light beam.

2. The atomic force microscope system according to claim 1, characterized in that: The internal light reflection angles at different positions in the anti-interference structure are different and / or the light refraction angles at different positions in the anti-interference structure are different.

3. The atomic force microscope system according to claim 2, characterized in that: The anti-interference structure is provided with a transmissive reflective film on the light incident side of the focusing lens structure and is reused as the detector beam splitter; wherein the result light beam is split by partially transmitting and partially reflecting on the light incident side.

4. The atomic force microscope system according to claim 3, characterized in that: The angle between the incident side of the light and the result light beam is 45°, and the angle between the position sensitive detector and the result light beam is 90°; The resulting light beam is reflected from the light incident side and enters the position sensitive detector.

5. The atomic force microscope system according to claim 2, characterized in that: The atomic force microscopy system further comprises a compensation element for compensating for the deflection of the result light beam caused by the anti-interference structure.

6. The atomic force microscope system according to claim 1, characterized in that: The anti-interference structure is configured as a wedge, wherein the wedge has opposing wedge surfaces and a horizontal surface, the wedge surface has a wedge angle relative to the horizontal surface, and the resultant light beam is transmitted through the wedge and refracted by the wedge.

7. The atomic force microscope system according to claim 6, characterized in that: The horizontal surface of the anti-interference structure is arranged toward the focusing lens structure and is coated with a transmissive reflective film so as to be reused as the detector beam splitter.

8. The atomic force microscope system according to claim 6, characterized in that: The atomic force microscope system comprises a wedge-shaped compensation plate having a shape consistent with that of the wedge and the substrate, and is used to compensate for the deflection of the result light beam caused by the wedge.

9. The atomic force microscope system according to claim 8, characterized in that: The atomic force microscopy system further comprises an interference sensor for simultaneously detecting the initial light beam and the result light beam, wherein the wedge-shaped compensation plate is arranged in the optical path between the initial light beam and the interference sensor, and is used to make the initial light beam passing through the wedge-shaped compensation plate parallel to the result light beam entering the interference sensor; The included angle between the wedge-shaped compensation plate and the initial light beam is consistent with the included angle between the anti-interference structure and the result light beam.

10. The atomic force microscope system according to claim 1, characterized in that: The focusing lens structure includes an incident area and an exit area; The incident area is arranged on the outgoing light path of the light source, and is used to focus the initial light beam onto the reflective surface; The exit area is arranged on the exit light path of the reflective surface, and is used to diverge the reflected light beam and adjust the propagation direction of the reflected light beam to the target direction, thereby forming the result light beam; The position sensitive detector is arranged on the outgoing light path of the outgoing region to collect the result light beam.

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