A three-axis closed-loop controlled AFM scanning head and atomic force microscope

Abstract

The present invention belongs to the technical field of needle-tip scanning atomic force microscope, and specifically provides an AFM scanning head and an atomic force microscope with three-axis closed-loop control, wherein the AFM scanning head comprises a housing, a laser light source module, an XYZ three-axis piezoelectric ceramic tube scanning module, a four-quadrant receiving signal module and an XYZ three-axis sensor closed-loop detection module, wherein the laser light source module, the XYZ three-axis piezoelectric ceramic tube scanning module, the four-quadrant receiving signal module and the XYZ three-axis sensor closed-loop detection module are all correspondingly located inside the housing; the XYZ three-axis sensor closed-loop detection module is correspondingly installed on the XYZ three-axis piezoelectric ceramic tube scanning module, and the XYZ three-axis sensor closed-loop detection module is correspondingly connected to a control system; when working, the XYZ three-axis sensor closed-loop detection module is used to detect the displacement during scanning, and the displacement is fed back to the control system, and after being processed and compared by the control system, compensation is performed according to the comparison result. The present invention can effectively improve the accuracy and response speed during detection, and has strong practicality.

Description

Technical Field

[0001] The invention relates to the technical field of needle-tip scanning atomic force microscopes, in particular to a three-axis closed-loop controlled AFM scanning head and an atomic force microscope. Background Art

[0002] Atomic force microscopy (AFM) is a new instrument with high atomic resolution. It studies the surface structure and properties of materials by detecting the extremely weak atomic interaction force between the surface of the sample to be tested and a miniature force-sensitive element. Fix one end of a micro-cantilever that is extremely sensitive to weak forces, and bring the tiny needle tip at the other end close to the sample. At this time, it will interact with the sample, and the force will cause the micro-cantilever to deform or change its motion state. When in use, laser detection is generally used to obtain information about the sample surface. The laser beam hits the back of the probe cantilever and then reflects to the position detector. During the scanning process, due to the interaction force between the sample and the probe tip, the probe cantilever will bend and fluctuate with the sample surface morphology, and the reflected light beam will also shift accordingly. By detecting the change in the position of the light spot on the position detector, information about the surface morphology of the sample to be tested can be obtained.

[0003] At present, atomic force microscopes (AFM) have been widely used in various fields such as research experiments in nano-related disciplines, and have become a basic tool for nanoscience research. With the help of this microscope, people can not only observe the nano-level fine morphology of the surface of materials and biological samples, but also study the mechanical properties of these samples. Existing atomic force microscopes (AFM) usually install a piezoelectric ceramic tube scanner in the scanning head to realize the scanning function. Due to the characteristics of the piezoelectric ceramic tube itself, it will produce a small micro-deviation when powered on, thereby driving the probe to swing to complete the scanning process. However, when using existing atomic force microscopes, most of them start scanning after the system sets a scanning amount in advance until the scanning ends. It is impossible to monitor the scanning process in real time during operation, so it cannot accurately obtain its actual scanning amount, and cannot effectively guarantee the detection accuracy of the atomic force microscope during actual scanning, resulting in a certain deviation in its detection results.

[0004] It should be noted that the above contents belong to the technical cognition scope of the inventor. Since the technical contents in this field are vast and too complicated, the above contents of this application do not necessarily constitute prior art. Summary of the invention

[0005] The present invention provides a three-axis closed-loop controlled AFM scanning head to solve the technical problems raised in the above background technology.

[0006] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a three-axis closed-loop controlled AFM scanning head, comprising a shell, a laser light source module, an XYZ three-axis piezoelectric ceramic tube scanning module, a four-quadrant receiving signal module and an XYZ three-axis sensor closed-loop detection module, wherein the laser light source module, the XYZ three-axis piezoelectric ceramic tube scanning module, the four-quadrant receiving signal module and the XYZ three-axis sensor closed-loop detection module are all correspondingly located inside the shell; the XYZ three-axis sensor closed-loop detection module is correspondingly installed on the XYZ three-axis piezoelectric ceramic tube scanning module, and the XYZ three-axis sensor closed-loop detection module is correspondingly connected to a control system; when working, the XYZ three-axis sensor closed-loop detection module is used to detect the displacement during scanning and feed it back to the control system, and after being processed by the control system and compared with the initial input displacement, compensation is performed according to the comparison result.

[0007] Preferably, the XYZ three-axis piezoelectric ceramic tube scanning module includes an XY-axis piezoelectric ceramic tube scanner and a Z-axis piezoelectric ceramic tube scanner, the XY-axis piezoelectric ceramic tube scanner is correspondingly installed on the scanner fixing plate, and the scanner fixing plate is correspondingly installed and fixed in the shell; an insulating connecting sleeve is correspondingly installed at the bottom of the XY-axis piezoelectric ceramic tube scanner, and the Z-axis piezoelectric ceramic tube scanner is correspondingly installed on the insulating connecting sleeve; a probe frame connecting sleeve is correspondingly installed at the bottom of the Z-axis piezoelectric ceramic tube scanner, a probe frame base is correspondingly installed on the probe frame connecting sleeve, and a focusing lens is correspondingly installed at the central position of the probe frame connecting sleeve; a probe fixing seat is correspondingly installed on the probe frame base, and a micro-cantilever probe is correspondingly installed on the probe fixing seat, and a fixed point on the back side of the tip of the micro-cantilever probe is correspondingly located at the focus of the focusing lens.

[0008] Preferably, the XYZ three-axis sensor closed-loop detection module includes an X-axis sensor, a Y-axis sensor and a Z-axis sensor, and a sensor fixing bracket is correspondingly installed and fixed on the scanner fixing disk, one electrode plate of the X-axis sensor and one electrode plate of the Y-axis sensor are correspondingly fixed on the insulating connecting sleeve, the other electrode plate of the X-axis sensor and the other electrode plate of the Y-axis sensor are correspondingly fixed on the sensor fixing bracket, and the X-axis sensor and the Y-axis sensor are vertically distributed at 90°; one electrode plate of the Z-axis sensor is correspondingly fixed on the probe frame connecting sleeve, and the other electrode plate of the Z-axis sensor is correspondingly fixed on the sensor fixing bracket.

[0009] Preferably, the X-axis sensor, the Y-axis sensor and the Z-axis sensor are all flat-plate capacitive position sensors.

[0010] Preferably, an imaging lens is correspondingly mounted on the housing, and the imaging lens is correspondingly located on the reflected light path of a fixed point on the back side of the micro-cantilever probe.

[0011] Preferably, the four-quadrant signal receiving module includes a four-quadrant receiver, which is correspondingly mounted on a fixed plate and is correspondingly located on the image focal plane of the imaging lens; the fixed plate is correspondingly mounted on an XY two-dimensional adjustment platform II and can be positionally adjusted in both the X-axis and Y-axis directions.

[0012] Preferably, the laser light source module is located directly above the XYZ three-axis piezoelectric ceramic tube scanning module, and the laser light source module is correspondingly installed on the XY two-dimensional adjustment platform I and can be adjusted in position in the X-axis and Y-axis directions; a collimating lens is correspondingly installed at the bottom of the laser light source module.

[0013] An atomic force microscope of the present invention comprises the above-mentioned three-axis closed-loop controlled AFM scanning head, wherein the AFM scanning head is mounted on one end of a cantilever beam of the atomic force microscope.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] The present invention designs an AFM scanning head with three-axis closed-loop control. A laser light source module, an XYZ three-axis piezoelectric ceramic tube scanning module, a four-quadrant receiving signal module and an XYZ three-axis sensor closed-loop detection module can be correspondingly arranged in the scanning head shell. Three flat-plate capacitive position sensors are used to realize the displacement of the atomic force microscope in three directions of X-axis, Y-axis and Z-axis during the scanning process and feed it back to the control system in real time. The control system analyzes and compares the displacement and performs compensation according to the comparison result, thereby effectively improving the detection accuracy and response speed during detection, better ensuring the accuracy of the final detection result, and the overall design is reasonable and ingenious with strong practicality.

[0016] It should be noted that the structures not introduced in the present invention are the same as the prior art or can be implemented by using the prior art, and are not described in detail here because they do not involve the design points and improvement directions of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the internal structure of the AFM scanning head with three-axis closed-loop control of the present invention;

[0018] Figure 2 It is a schematic diagram of the internal optical path of the AFM scanning head of the three-axis closed-loop control of the present invention;

[0019] Figure 3 It is a schematic diagram of the installation position of the XYZ three-axis sensor in the three-axis closed-loop controlled AFM scanning head of the present invention;

[0020] Figure 4 It is a schematic diagram of the appearance structure of the three-axis closed-loop controlled AFM scanning head of the present invention;

[0021] Figure 5 It is a schematic diagram of the workflow of the XYZ three-axis sensor closed-loop detection of the AFM scanning head with three-axis closed-loop control of the present invention;

[0022] Figure 6 It is a schematic diagram of the working principle of the XYZ three-axis sensor of the AFM scanning head with three-axis closed-loop control of the present invention;

[0023] Figure 7 It is a compensation schematic diagram of the working principle of the XYZ three-axis sensor closed-loop detection of the AFM scanning head with three-axis closed-loop control of the present invention.

[0024] Reference numerals:

[0025] 1. Laser light source module; 2. XY two-dimensional adjustment platform I; 3. Collimating lens; 4. Scanner fixing plate; 5. XY axis piezoelectric ceramic tube scanner; 6. Insulating connecting sleeve; 7. Z axis piezoelectric ceramic tube scanner; 8. Probe holder connecting sleeve; 9. Probe holder base; 10. Probe fixing seat; 11. Micro cantilever probe; 12. Sensor fixing bracket; 13. X axis sensor; 14. Y axis sensor; 15. Z axis sensor; 16. Imaging lens; 17. XY two-dimensional adjustment platform II; 18. Fixing plate; 19. Four-quadrant receiver; 20. Focusing lens; 21. Shell. DETAILED DESCRIPTION

[0026] To facilitate understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. Several embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0027] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "page", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicating orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0028] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0029] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed", "provided with", "provided on" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] Embodiment 1:

[0031] See also Figure 1-7 The present embodiment is a three-axis closed-loop controlled AFM scanning head, comprising a housing 21, a laser light source module 1, an XYZ three-axis piezoelectric ceramic tube scanning module, a four-quadrant receiving signal module and an XYZ three-axis sensor closed-loop detection module, such as Figure 4 As shown, the laser light source module 1, the XYZ three-axis piezoelectric ceramic tube scanning module, the four-quadrant receiving signal module and the XYZ three-axis sensor closed-loop detection module are correspondingly located inside the housing 21. The XYZ three-axis sensor closed-loop detection module is correspondingly installed on the XYZ three-axis piezoelectric ceramic tube scanning module, and the XYZ three-axis sensor closed-loop detection module is correspondingly connected to the control system. When working, the XYZ three-axis sensor closed-loop detection module is used to detect the displacement of the XYZ three-axis piezoelectric ceramic tube scanning module when scanning in the three directions of the X-axis, Y-axis and Z-axis, and feed it back to the control system. After the control system processes and compares the displacement with the initial input displacement, compensation is performed according to the comparison result.

[0032] Specifically, the laser light source module 1, the XYZ three-axis piezoelectric ceramic tube scanning module, the four-quadrant signal receiving module and the XYZ three-axis sensor closed-loop detection module are all independent and separate modules, which are easy to install, adjust and replace, and during the scanning process, other modules do not move with the XYZ three-axis piezoelectric ceramic tube scanning module.

[0033] like Figure 1As shown, the laser light source module 1 is located directly above the XYZ three-axis piezoelectric ceramic tube scanning module. The laser light source module 1 is correspondingly mounted on the XY two-dimensional adjustment platform Ⅰ2 and can be adjusted in position in the X-axis and Y-axis directions. Then, the laser light source module 1 can be freely adjusted in position in the X-axis and Y-axis directions as needed through the XY two-dimensional adjustment platform Ⅰ2. A collimating lens 3 is correspondingly mounted at the bottom of the laser light source module 1, and the laser light source module 1 can be used to provide a laser light source.

[0034] like Figure 1 and Figure 2 As shown, the XYZ three-axis piezoelectric ceramic tube scanning module includes an XY-axis piezoelectric ceramic tube scanner 5 and a Z-axis piezoelectric ceramic tube scanner 7. The XY-axis piezoelectric ceramic tube scanner 5 is correspondingly mounted on the scanner fixing plate 4, and the scanner fixing plate 4 is correspondingly mounted and fixed in the housing 21. The XY-axis piezoelectric ceramic tube scanner 5 and the Z-axis piezoelectric ceramic tube scanner 7 are coaxially mounted in an upper and lower separated manner. An insulating connecting sleeve 6 is correspondingly mounted at the bottom of the XY-axis piezoelectric ceramic tube scanner 5, and the Z-axis piezoelectric ceramic tube scanner 7 is correspondingly mounted on the insulating connecting sleeve 6. A probe frame connecting sleeve 8 is correspondingly mounted at the bottom of the Z-axis piezoelectric ceramic tube scanner 7, a probe frame base 9 is correspondingly mounted on the probe frame connecting sleeve 8, and a focusing lens 20 is correspondingly mounted at the central position of the probe frame connecting sleeve 8. The probe holder base 9 is correspondingly provided with a probe fixing seat 10, and the probe fixing seat 10 is correspondingly provided with a micro-cantilever probe 11, and a fixed point on the back of the tip of the micro-cantilever probe 11 is correspondingly located at the focus of the focusing lens 20. The housing 21 is also correspondingly provided with an imaging lens 16, and the imaging lens 16 is correspondingly located on the reflected light path of a fixed point on the back of the micro-cantilever probe 11. Light-transmitting holes may be provided at corresponding positions on both sides of the probe holder connecting sleeve 8, so that the reflected light path on the back of the tip of the micro-cantilever probe 11 can pass through the imaging lens 16 smoothly.

[0035] The XY axis piezoelectric ceramic tube scanner 5, insulating connecting sleeve 6, Z axis piezoelectric ceramic tube scanner 7, probe frame connecting sleeve 8, focusing lens 20, probe frame base 9, probe fixing seat 10, and micro cantilever probe 11 are an integral structure after installation, so the focusing lens 20 will also move with the XY axis piezoelectric ceramic tube scanner 5 and the Z axis piezoelectric ceramic tube scanner 7. Even if the XY axis piezoelectric ceramic tube scanner 5 and the Z axis piezoelectric ceramic tube scanner 7 are shifted when powered on during the scanning process, a fixed point on the back of the tip of the micro cantilever probe 11 will always be located at the focus of the focusing lens 20, that is, the spot position remains unchanged. The loads of the XY axis piezoelectric ceramic tube scanner 5 and the Z axis piezoelectric ceramic tube scanner 7 are only the insulating connecting sleeve 6, the probe frame connecting sleeve 8, the focusing lens 20, the probe frame base 9, the probe fixing seat 10, and the micro cantilever probe 11. The overall weight is light and the load is small, and the influence on the resonance frequency of the Z axis piezoelectric ceramic tube scanner 7 can be ignored.

[0036] The four-quadrant receiving signal module includes a four-quadrant receiver 19, such as Figure 1 and Figure 2 As shown, the four-quadrant receiver 19 is correspondingly mounted on the L-shaped fixed plate 18, and the four-quadrant receiver 19 is correspondingly located on the image focal plane of the imaging lens 16. The fixed plate 18 is correspondingly mounted on the XY two-dimensional adjustment platform II 17 and can be adjusted in position in the X-axis and Y-axis directions, and then the four-quadrant receiver 19 can be freely adjusted in position in the X-axis and Y-axis directions as needed through the XY two-dimensional adjustment platform II 17.

[0037] The XY two-dimensional adjustment platform I2 and the XY two-dimensional adjustment platform II17 are both installed on the housing 21. The structural principles of the two XY two-dimensional adjustment platforms are basically the same, that is, the XY two-dimensional adjustment platform includes a rectangular installation frame, a fixed seat is installed in the rectangular installation frame, a slide seat I that can slide horizontally is installed on the top of the fixed seat, and the horizontal side of the slide seat I can be connected to the fixed seat by a spring; a slide seat II that can slide longitudinally is installed on the top of the slide seat I, and the longitudinal side of the slide seat II can also be connected to the slide seat I by a spring. Two adjusting screws are respectively threaded through the adjacent side walls of the rectangular installation frame, and the outer ends of the two adjusting screws are respectively provided with knobs, and the inner ends of the two adjusting screws are respectively against the horizontal side of the slide seat I and the longitudinal side of the slide seat II. The fixed plate 18 is installed on the slide seat II of the XY two-dimensional adjustment platform II17, and the four-quadrant receiver 19 is installed on one side of the L-shaped fixed plate 18. The fixed seat and the middle part of the slide seat I of the XY two-dimensional adjustment platform I2 are both provided with large-sized through holes. The laser light source module 1 is installed in the middle part of the slide seat II of the XY two-dimensional adjustment platform I2, and passes through the through holes of the slide seat I and the fixed seat below. By turning the two knobs of the two XY two-dimensional adjustment platforms respectively, the laser light source module 1 and the four-quadrant receiver 19 can be adjusted in one direction in the X-axis or Y-axis direction; the laser light source module 1 and the four-quadrant receiver 19 can be adjusted and reset in the reverse direction by using springs. It is worth noting that the design and use of the XY two-dimensional adjustment platform I2 and the XY two-dimensional adjustment platform II17 are already very common in the prior art, and the existing XY two-dimensional adjustment platform can be directly used. Its specific implementation structure is not limited to the one described above, as long as the position adjustment of the laser light source module 1 and the four-quadrant receiver 19 in the X-axis and Y-axis directions can be achieved.

[0038] like Figure 1 and Figure 3As shown, the XYZ three-axis sensor closed-loop detection module includes an X-axis sensor 13, a Y-axis sensor 14 and a Z-axis sensor 15, and the X-axis sensor 13, the Y-axis sensor 14 and the Z-axis sensor 15 are all flat-plate capacitive position sensors. A sensor fixing bracket 12 is correspondingly installed and fixed on the scanner fixing disk 4, and one electrode plate of the X-axis sensor 13 and one electrode plate of the Y-axis sensor 14 are correspondingly fixed on the insulating connecting sleeve 6, and the other electrode plate of the X-axis sensor 13 and the other electrode plate of the Y-axis sensor 14 are correspondingly fixed on the sensor fixing bracket 12, and the X-axis sensor 13 and the Y-axis sensor 14 are vertically distributed at 90°. One electrode plate of the Z-axis sensor 15 is correspondingly fixed on the probe frame connecting sleeve 8, and the other electrode plate of the Z-axis sensor 15 is correspondingly fixed on the sensor fixing bracket 12. That is, the change in the distance between the two plates is used to detect and calculate the displacement of the XY-axis piezoelectric ceramic tube scanner 5 and the Z-axis piezoelectric ceramic tube scanner 7 during scanning, and the obtained displacement is fed back to the control system, which then compares the displacement with the initial input displacement and then performs compensation based on the comparison result.

[0039] When working, the laser light source module 1 emits a laser beam, which enters the XYZ three-axis piezoelectric ceramic tube scanning module through the collimating lens 3, and then passes through the scanner fixing plate 4, the XY axis piezoelectric ceramic tube scanner 5, the insulating connecting sleeve 6, the Z axis piezoelectric ceramic tube scanner 7, the probe frame connecting sleeve 8 and the focusing lens 20 installed in the probe frame connecting sleeve 8, and then the light spot hits a fixed point on the back of the micro-cantilever probe 11 needle tip, and then the laser beam is reflected by the micro-cantilever probe 11 needle tip and passes through the imaging lens 16 and finally falls on the four-quadrant receiver 19. During the scanning process, the tip of the micro-cantilever probe 11 will fluctuate with the surface of the scanned sample, thereby driving the fluctuation of the laser beam on the reflection path, so that the light spot position finally falls on the four-quadrant receiver 19 is different, and the morphology of the sample surface is reflected after data processing. At the same time, during the scanning process, the XY axis piezoelectric ceramic tube scanner 5 makes periodic motion within a certain range in the X-axis and Y-axis directions, and the Z axis piezoelectric ceramic tube scanner 7 makes periodic motion within a certain range in the Z-axis direction. As the XY axis piezoelectric ceramic tube scanner 5 and the Z axis piezoelectric ceramic tube scanner 7 move, the X axis sensor 13 and one electrode plate of the Y axis sensor 14 fixed on the insulating connecting sleeve 6 and one electrode plate of the Z axis sensor 15 fixed on the probe holder connecting sleeve 8 will also be driven to move. As one electrode plate of the X axis sensor 13, the Y axis sensor 14 and the Z axis sensor 15 moves relative to the other electrode plate of the sensor, that is, the distance between the two electrodes is compressed, the sensor feeds back the distance change data between the two electrodes to the control system. After analysis and processing by the control system, the real-time scanning displacement of the XYZ three-axis piezoelectric ceramic tube scanning module in the three directions of the X axis, Y axis and Z axis can be obtained, and then this displacement is compared with the initial set displacement, and compensation is performed based on the comparison result.

[0040] For example, take the X-axis change as an example. Figure 5-7 As shown:

[0041] The scanning head is set to scan a distance S in the X-axis direction. During the scanning process, when the scanning head scans to a certain point, the corresponding X-axis sensor 13 electrode plate changes from the origin position O to the position X1, and the distance change is L2. The sensor feeds back the distance change L2 to the control system. After data processing by the control system, it is calculated that the scanning distance S1 corresponding to the distance change between the electrodes of the X-axis sensor 13 is L2. Then the control system compares the calculated scanning distance S1 with the initially set scanning distance S. When the S1 value does not reach S, the scanning head is moved to the X-axis direction. Continue scanning forward in the X-axis direction until the position of one electrode plate of the X-axis sensor 13 changes from position X1 to position X2. At this time, the distance change from position X1 to position X2 is △L, and the total distance change is L2+△L. At this time, the sensor feeds back the distance change L2+△L to the control system. After the control system processes the data again, it is calculated that the distance change between the electrodes of the X-axis sensor 13 is L2+△L, and the corresponding scanning distance of the scanning head in the X-axis direction is S1+△S. Multiple cycles are performed until S=S1+△S, and a complete scanning operation of the scanning head in the X-axis direction with a scanning distance of S is completed.

[0042] Embodiment 2:

[0043] An atomic force microscope of this embodiment includes the three-axis closed-loop controlled AFM scanning head described in Embodiment 1, and the AFM scanning head is installed at one end of the cantilever beam of the atomic force microscope to work.

[0044] The above-described embodiments only express a certain implementation mode of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the patent scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims.

Claims

1. A three-axis closed-loop controlled AFM scanning head, comprising a housing (21) and a laser light source module (1), characterized in that: It also includes an XYZ three-axis piezoelectric ceramic tube scanning module, a four-quadrant receiving signal module and an XYZ three-axis sensor closed-loop detection module. The laser light source module (1), the XYZ three-axis piezoelectric ceramic tube scanning module, the four-quadrant receiving signal module and the XYZ three-axis sensor closed-loop detection module are all correspondingly located inside the housing (21); the XYZ three-axis sensor closed-loop detection module is correspondingly mounted on the XYZ three-axis piezoelectric ceramic tube scanning module, and the XYZ three-axis sensor closed-loop detection module is correspondingly connected to the control system; when working, the XYZ three-axis sensor closed-loop detection module is used to detect the displacement during scanning and feed it back to the control system. After being processed by the control system and compared with the initial input displacement, compensation is performed according to the comparison result; The XYZ three-axis piezoelectric ceramic tube scanning module comprises an XY axis piezoelectric ceramic tube scanner (5) and a Z axis piezoelectric ceramic tube scanner (7); the XY axis piezoelectric ceramic tube scanner (5) is correspondingly mounted on a scanner fixing plate (4); the scanner fixing plate (4) is correspondingly mounted and fixed in a housing (21); an insulating connecting sleeve (6) is correspondingly mounted on the bottom of the XY axis piezoelectric ceramic tube scanner (5); the Z axis piezoelectric ceramic tube scanner (7) is correspondingly mounted on the insulating connecting sleeve (6); the Z axis piezoelectric ceramic tube scanner (5) is correspondingly mounted on the insulating connecting sleeve (6); A probe frame connecting sleeve (8) is correspondingly installed at the bottom of the electric ceramic tube scanner (7), a probe frame base (9) is correspondingly installed on the probe frame connecting sleeve (8), and a focusing lens (20) is correspondingly installed at the central position of the probe frame connecting sleeve (8); a probe fixing seat (10) is correspondingly installed on the probe frame base (9), a micro-cantilever probe (11) is correspondingly installed on the probe fixing seat (10), and a fixed point on the back of the needle tip of the micro-cantilever probe (11) is correspondingly located at the focus of the focusing lens (20); The XYZ three-axis sensor closed-loop detection module comprises an X-axis sensor (13), a Y-axis sensor (14) and a Z-axis sensor (15); a sensor fixing bracket (12) is correspondingly mounted and fixed on the scanner fixing plate (4); one electrode plate of the X-axis sensor (13) and one electrode plate of the Y-axis sensor (14) are correspondingly fixed on the insulating connecting sleeve (6); another electrode plate of the X-axis sensor (13) and another electrode plate of the Y-axis sensor (14) are correspondingly fixed on the sensor fixing bracket (12); and the X-axis sensor (13) and the Y-axis sensor (14) are vertically distributed at 90 degrees; one electrode plate of the Z-axis sensor (15) is correspondingly fixed on the probe frame connecting sleeve (8), and another electrode plate of the Z-axis sensor (15) is correspondingly fixed on the sensor fixing bracket (12).

2. The three-axis closed-loop controlled AFM scanning head according to claim 1, characterized in that: The X-axis sensor (13), the Y-axis sensor (14) and the Z-axis sensor (15) are all flat-plate capacitive position sensors.

3. The three-axis closed-loop controlled AFM scanning head according to claim 1, characterized in that: An imaging lens (16) is also correspondingly mounted on the housing (21), and the imaging lens (16) is correspondingly located on a reflection light path at a fixed point on the back side of the micro-cantilever probe (11).

4. The three-axis closed-loop controlled AFM scanning head according to claim 3, characterized in that: The four-quadrant signal receiving module comprises a four-quadrant receiver (19), the four-quadrant receiver (19) is correspondingly mounted on a fixed plate (18), and the four-quadrant receiver (19) is correspondingly located on the image focal plane of the imaging lens (16); the fixed plate (18) is correspondingly mounted on an XY two-dimensional adjustment platform II (17) and can be positionally adjusted in both the X-axis and Y-axis directions.

5. The three-axis closed-loop controlled AFM scanning head according to claim 4, characterized in that: The laser light source module (1) is located directly above the XYZ three-axis piezoelectric ceramic tube scanning module. The laser light source module (1) is installed on the XY two-dimensional adjustment platform I (2) and can be adjusted in position in the X-axis and Y-axis directions. A collimating lens (3) is installed at the bottom of the laser light source module (1).

6. An atomic force microscope, characterized in that: A three-axis closed-loop controlled AFM scanning head comprising any one of claims 1 to 5, wherein the AFM scanning head is mounted on one end of a cantilever beam of an atomic force microscope.

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