Open modular scanning probe microscope control system

Abstract

The present invention provides an open modular scanning probe microscope control system, comprising: an analog signal conditioning and interface module, connected to the position detector of the scanning probe microscope probe, and receiving the force sensor signal collected by the position detector; a lock-in amplifier module, connected to the analog signal conditioning and interface module, receiving the force sensor signal, and determining the amplitude, phase, X component and Y component based on the received force sensor signal; a Z-axis control module, connected to both the analog signal conditioning and interface module and the lock-in amplifier module, receiving the force sensor signal, as well as receiving the amplitude and phase, and generating a Z-axis control signal for driving the piezoelectric scanning stage to move in the Z direction; an XY-axis scanning control and imaging signal acquisition module, connected to both the lock-in amplifier module and the Z-axis control module, receiving the amplitude, phase or X component, Y component and the Z-axis control signal, and generating an XY control signal for driving the piezoelectric scanning stage to move in the X direction and the Y direction.

Description

Technical Field

[0001] The present invention relates to the field of microscopy imaging technology, and in particular to an open modular scanning probe microscope control system. Background Art

[0002] A scanning probe microscope (SPM) is an important imaging and characterization analysis tool in nanotechnology. It can be used to measure the surface topography of a sample micro-region and related properties such as the electrical and magnetic properties of the sample surface, and is widely applied in various frontier fields of scientific research. The SPM is suitable for different working environments, and its advantage is extremely high spatial resolution, which can even reach the atomic level under some conditions. The precision electronics control system of the SPM provides guarantee for realizing its high-precision and high-speed scanning. Taking the atomic force microscope (AFM), which is widely used in the SPM, as an example: A laser beam is irradiated on the end of the micro-cantilever of the AFM probe, and the deflection of the cantilever, that is, the bending degree of the cantilever, is amplified by the optical lever principle; then the position-sensitive detector receives the reflected light spot and converts its position offset into an electrical signal; taking this electrical signal as the feedback control quantity of the SPM control system and maintaining its constancy through the piezoelectric ceramic servo system, that is, maintaining the distance from the sample surface to the tip at the end of the cantilever as a constant quantity, so that the topography information of the sample surface can be obtained by reading the displacement of the piezoelectric ceramic for imaging.

[0003] However, the currently commonly used scanning probe microscope control system is an electronics control system based on a single master chip, centralized, and integrated design. The performance parameters such as the control precision, sampling rate, and response time of this kind of electronics control system are greatly limited by the hardware used, which is not conducive to the further improvement of performance and function expansion; on the other hand, the architecture of this kind of system determines that it is impossible to use general high-performance modular hardware to achieve rapid iterative updates of system research and development. In addition, various potential abnormal states are often difficult to detect during the debugging of the electronics control system with a single master chip, centralized, and integrated design, which will bring obstacles to the actual research and development and application of the system. Therefore, how to facilitate the improvement of the performance of the scanning probe microscope control system and how to facilitate the rapid expansion of the functions of the scanning probe microscope control system are technical problems to be solved urgently. Summary of the Invention

[0004] In view of this, the present invention provides an open modular scanning probe microscope control system to solve one or more problems existing in the prior art.

[0005] According to one aspect of the present invention, the present invention discloses an open modular scanning probe microscope control system, the system includes:

[0006] An analog signal conditioning and interface module, which is used to connect to a position detector of a scanning probe microscope probe, and the analog signal conditioning and interface module receives a force sensor signal collected by the position detector;

[0007] A lock-in amplifier module, which is connected to the analog signal conditioning and interface module. The lock-in amplifier module receives the force sensor signal output by the analog signal conditioning and interface module, and determines the amplitude, phase, X component, and Y component of the force sensor signal based on the received force sensor signal;

[0008] A Z-axis control module, which is connected to both the analog signal conditioning and interface module and the lock-in amplifier module. The Z-axis control module receives the force sensor signal output by the analog signal conditioning and interface module, as well as the amplitude and phase output by the lock-in amplifier module, and generates a Z-axis control signal for driving the piezoelectric scanning stage to move in the Z direction;

[0009] An XY-axis scanning control and imaging signal acquisition module, which is connected to both the lock-in amplifier module and the Z-axis control module. The XY-axis scanning control and imaging signal acquisition module receives the amplitude, phase, or X component, Y component output by the lock-in amplifier module, as well as the Z-axis control signal output by the Z-axis control module, and generates an XY control signal for driving the piezoelectric scanning stage to move in the X direction and the Y direction.

[0010] In some embodiments of the present invention, the force sensor signal is an optical signal or an electrical signal. When the force sensor signal is an optical signal, the force sensor signal includes a light spot horizontal signal and a light spot vertical signal; and / or

[0011] The XY-axis scanning control and imaging signal acquisition module generates a lift control signal for controlling the probe to lift.

[0012] In some embodiments of the present invention, the control system further includes a host computer, and the host computer is connected to the analog signal conditioning and interface module, the lock-in amplifier module, the Z-axis control module, and the XY-axis scanning control and imaging signal acquisition module; and / or

[0013] The Z-axis control module acquires the lift control signal and the sampling clock of the XY-axis scanning control and imaging signal acquisition module.

[0014] In some embodiments of the present invention, the Z-axis control signal is a first Z-axis control signal, a second Z-axis control signal, or a third Z-axis control signal;

[0015] The first Z-axis control signal is a signal generated by the Z-axis control module based on the received light spot horizontal signal, light spot vertical signal, amplitude, and phase;

[0016] The second Z-axis control signal is the signal sent by the host computer to the Z-axis control module;

[0017] The third Z-axis control signal is the signal generated by the Z-axis control module based on the obtained lift control signal and the sampling clock.

[0018] In some embodiments of the present invention, the Z-axis control module compares the received light spot vertical signal or amplitude with a preset value, and generates a motor control signal based on the comparison result.

[0019] In some embodiments of the present invention, the control system further includes a motor control module, the motor control module is connected to the Z-axis control module, and the motor control module is used to control the working state of the probe motor based on the received motor control signal.

[0020] In some embodiments of the present invention, the analog signal conditioning and interface module includes a divider, a voltage conditioning unit, a single-chip microcomputer, and a display device. The input end of the divider is connected to the position detector, the output end of the divider is connected to both the input ends of the lock-in amplifier module and the voltage conditioning unit, the output end of the voltage conditioning unit is connected to the input end of the single-chip microcomputer, and the output end of the single-chip microcomputer is connected to the display device.

[0021] In some embodiments of the present invention, the lock-in amplifier module includes an OE1300 series modular lock-in amplifier.

[0022] In some embodiments of the present invention, the Z-axis control module includes a first multiplexer, an FPGA sub-module, and a second multiplexer. The input end of the first multiplexer is connected to both the analog signal conditioning and interface module and the lock-in amplifier module. The output end of the first multiplexer is connected to the input end of the FPGA sub-module. The output end of the FPGA sub-module is connected to the input end of the second multiplexer. The output end of the second multiplexer is connected to the XY-axis scanning control and imaging signal acquisition module.

[0023] In some embodiments of the present invention, the analog signal conditioning and interface module, the lock-in amplifier module, the Z-axis control module, and the XY-axis scanning control and imaging signal acquisition module are all provided with independent main control chips.

[0024] The open modular scanning probe microscope control system consists of an analog signal conditioning and interface module, a lock-in amplifier module, a Z-axis control module, and an XY-axis scanning control and imaging signal acquisition module that can be used independently. The Z-axis control module receives the spot horizontal signal, spot vertical signal, amplitude and phase signals, and generates a Z-axis control signal for driving the piezoelectric scanning stage to move in the Z direction. The XY-axis scanning control and imaging signal acquisition module generates XY control signals for driving the piezoelectric scanning stage to move in the X and Y directions. The open modular scanning probe microscope control system uses multiple independent modules to complete the control of the scanning probe microscope, making it easy to detect abnormal states of each module. Furthermore, it is convenient to improve the control accuracy, sampling rate, and shorten the response time of the microscope control system, thereby facilitating the improvement of the performance of the microscope control system and the realization of the function expansion of the microscope control system.

[0025] Additional advantages, objects, and features of the present invention will be partially described below and will become partially apparent to those of ordinary skill in the art after studying the following text, or may be learned from the practice of the present invention. The objects and other advantages of the present invention can be realized and obtained by the structures specifically pointed out in the written description, claims, and drawings.

[0026] Those skilled in the art will understand that the objects and advantages that can be achieved by the present invention are not limited to the above specifically described, and the above and other objects that the present invention can achieve will be more clearly understood according to the following detailed description. Brief Description of the Drawings

[0027] The drawings described herein are used to provide a further understanding of the present invention, form a part of this application, and do not limit the present invention. The components in the drawings are not drawn to scale, but are only for showing the principles of the present invention. For the convenience of showing and describing some parts of the present invention, the corresponding parts in the drawings may be enlarged, that is, may become larger relative to other components in the exemplary device actually manufactured according to the present invention. In the drawings:

[0028] Figure 1 It is a schematic diagram of the architecture of the open modular scanning probe microscope control system according to an embodiment of the present invention.

[0029] Figure 2 It is a schematic diagram of the architecture of the analog signal conditioning and interface module according to an embodiment of the present invention.

[0030] Figure 3 It is a schematic diagram of the architecture of the lock-in amplifier module according to an embodiment of the present invention.

[0031] Figure 4 It is a schematic diagram of the architecture of the XY-axis scanning control and imaging signal acquisition module according to an embodiment of the present invention.

[0032] Figure 5 This is a schematic diagram of the architecture of the Z-axis control module according to an embodiment of the present invention.

[0033] Figure 6 This is a schematic diagram of the architecture of the motor control module according to an embodiment of the present invention.

[0034] Figure 7 This is a schematic diagram of the application of the open modular scanning probe microscope control system according to an embodiment of the present invention in a light-lever atomic force microscope.

[0035] Figure 8 This is a schematic diagram of the application of the open modular scanning probe microscope control system according to an embodiment of the present invention in a quartz tuning fork atomic force microscope. Detailed implementation manners

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer and more understandable, the following further describes the embodiments of the present invention in detail with reference to the accompanying drawings. Herein, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but do not limit the present invention.

[0037] Herein, it should be noted that, in order to avoid obscuring the present invention due to unnecessary details, only the structures and / or processing steps closely related to the solution of the present invention are shown in the drawings, while other details less related to the present invention are omitted.

[0038] It should be emphasized that the terms "include / comprise / have" when used herein refer to the presence of features, elements, steps, or components, but do not exclude the presence or addition of one or more other features, elements, steps, or components.

[0039] Aiming at the problems of limited performance improvement and limited function expansion existing in the scanning probe microscope control system based on a single master chip, centralized, and integrated design in the prior art, the present invention provides an open modular scanning probe microscope control system. This open modular scanning probe microscope control system provides guarantees for performance improvement and function expansion, and is also conducive to realizing the rapid iterative update of the microscope control system.

[0040] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, the same reference numerals represent the same or similar components, or the same or similar steps.

[0041] Figure 1 This is a schematic diagram of the architecture of the open modular scanning probe microscope control system according to an embodiment of the present invention. Refer to Figure 1, the control system at least includes an analog signal conditioning and interface module 301, a lock-in amplifier module 302, a Z-axis control module 304, and an XY-axis scanning control and imaging signal acquisition module 303. Among them, the analog signal conditioning and interface module 301 is used to connect to the position detector of the scanning probe microscope probe, and the analog signal conditioning and interface module 301 receives the force sensor signal collected by the position detector. Specifically, the force sensor signal can be an optical signal or an electrical signal. When the force sensor signal is an optical signal, the force sensor signal includes a light spot horizontal signal and a light spot vertical signal, that is, the analog signal conditioning and interface module 301 determines the light spot horizontal signal and the light spot vertical signal based on the received optical signal. Exemplarily, when the scanning probe microscope probe is a cantilever probe, the position detector is specifically a quadrant light spot position detector. At this time, the force sensor signal is an optical signal, and this type of scanning probe microscope can work in a dynamic mode or a static mode; when the scanning probe microscope probe is a quartz tuning fork probe, the position detector is specifically a piezoelectric sensitive device, and at this time the force sensor signal is an electrical signal.

[0042] The lock-in amplifier module 302 is connected to the analog signal conditioning and interface module 301. The lock-in amplifier module 302 receives the force sensor signal output by the analog signal conditioning and interface module 301 and determines the amplitude, phase, X component, and Y component of the force sensor signal. Specifically, when the force sensor signal is an optical signal, the lock-in amplifier module 302 receives the light spot vertical signal output by the analog signal conditioning and interface module 301 and determines the amplitude, phase, X component, and Y component of the light spot vertical signal; when the force sensor signal is an electrical signal, the lock-in amplifier module 302 receives the amplified tuning fork AC signal output by the analog signal conditioning and interface module 301 and determines the amplitude, phase, X component, and Y component of the tuning fork AC signal. The Z-axis control module 304 is connected to both the analog signal conditioning and interface module 301 and the lock-in amplifier module 302. The Z-axis control module 304 receives the force sensor signal sent by the analog signal conditioning and interface module 301, as well as the amplitude and phase output by the lock-in amplifier module 302, and generates a Z-axis control signal for driving the piezoelectric scanning stage to move in the Z direction.

[0043] The XY-axis scanning control and imaging signal acquisition module 303 is connected to both the lock-in amplifier module 302 and the Z-axis control module 304. The XY-axis scanning control and imaging signal acquisition module 303 receives the amplitude, phase, or X component, Y component output by the lock-in amplifier module 302, and the XY-axis scanning control and imaging signal acquisition module 303 receives the Z-axis control signal output by the Z-axis control module 304, and generates an XY control signal for driving the piezoelectric scanning stage to move in the X direction and the Y direction.

[0044] Furthermore, the control system further includes a host computer 100, which is connected to the analog signal conditioning and interface module 301, the lock-in amplifier module 302, the Z-axis control module 304, and the XY-axis scanning control and imaging signal acquisition module 303. The host computer 100 can send a second Z-axis control signal for driving the piezoelectric scanning stage to move in the Z direction to the Z-axis control module 304. Specifically, the host computer 100 is provided with a host computer software program 101. At this time, the analog signal conditioning and interface module 301, the lock-in amplifier module 302, the Z-axis control module 304, and the XY-axis scanning control and imaging signal acquisition module 303 are components of the lower computer 300, and the host computer 100 and the lower computer 300 are communicatively connected through the communication bus 200. For this control system, real-time tasks are executed by each sub-module, and each sub-module exchanges information with the host computer 100 through the communication bus 200, while non-real-time tasks are coordinated by the central processing unit of the host computer 100 to run each sub-module; and the mechanical dimensions of each sub-module follow the 19-inch 3U chassis standard, which is convenient for encapsulation in an integrated chassis.

[0045] In one embodiment, furthermore, the control system further includes a motor control module 305, which is connected to the Z-axis control module 304. The motor control module 305 is used to control the working state of the probe motor based on the received motor control signal, specifically to control the automatic stop of the probe motor. The motor control module 305 is also one of the modules of the lower computer 300. At this time, the lower computer 300 is composed of multiple sub-modules such as the analog signal conditioning and interface module 301, the lock-in amplifier module 302, the XY-axis scanning control and imaging signal acquisition module 303, the Z-axis control module 304, and the motor control module 305.

[0046] Among them, the analog signal conditioning and interface module 301, the lock-in amplifier module 302, the Z-axis control module 304, the XY-axis scanning control and imaging signal acquisition module 303, and the motor control module 305 are also each provided with an independent main control chip. The main control chip is a field programmable gate array control chip, a digital signal processing chip, or a high-performance micro control unit, etc.

[0047] Specifically, the analog signal conditioning and interface module 301 is mainly used to process the signals detected by the position detector, such as including real-time calculations of the voltage magnitude, polarity, and parameter conversion of the analog signal, etc. Refer to Figure 2, the analog signal conditioning and interface module 301 may specifically include a divider (the first divider 301-1 and the second divider 301-2), a voltage conditioning unit 301-3, a single-chip microcomputer 301-4, and a display device. The input end of the divider is connected to the output end of the position detector. The output end of the divider is connected to both the phase-locked amplification module 302 and the input end of the voltage conditioning unit. The output end of the voltage conditioning unit 301-3 is connected to the input end of the single-chip microcomputer 301-4, and the output end of the single-chip microcomputer 301-4 is connected to the display device. Among them, the display device is used to display the signals determined by this module in real time, such as the spot horizontal signal and the spot vertical signal, etc. In addition, the analog signal conditioning and interface module 301 is also provided with an output unit 301-6, and the output unit 301-6 can output the normalized spot horizontal signal, spot vertical signal, and total light intensity signal to the subsequent stage. In an embodiment, taking the application of this scanning probe microscope control system to a lever-type AFM as an example, this lever-type AFM uses a four-quadrant position-sensitive detector PDQ80A. The output signals of the 4 photodiodes of the four-quadrant position-sensitive detector are Q1, Q2, Q3, and Q4 respectively. At this time, the spot horizontal signal is (Q2 + Q3 - Q1 - Q4), the spot vertical signal is (Q1 + Q2 - Q3 - Q4), and the total light intensity signal is (Q1 + Q2 + Q3 + Q4); among them, the light intensity normalization operation refers to dividing the spot horizontal signal and the spot vertical signal by the total light intensity signal through the divider respectively. Specifically, the analog signal conditioning and interface module 301 builds an analog division circuit with the AD734 divider as the core to achieve light intensity normalization; reference Figure 2 , the input of the first divider 301-1 is the spot vertical signal and the total light intensity signal, and the output is the normalized spot vertical signal; the input of the second divider 301-2 is the spot horizontal signal and the total light intensity signal, and the output is the normalized spot horizontal signal; the analog signal conditioning and interface module 301 further outputs the total light intensity signal, the normalized spot vertical signal, and the spot horizontal signal through the output unit 301-6. In addition, the total light intensity signal, the normalized spot vertical signal, and the spot horizontal signal are further input into the voltage conditioning unit 301-3. The voltage conditioning unit 301-3 uses an OP27 operational amplifier to build a proportional and offset operation circuit. The voltage conditioning unit 301-3 preprocesses the voltage range of the signals it receives, that is, adjusts the change range of the analog signal to the input range of the digital-to-analog converter. In this embodiment, the voltage range is adjusted to 0V to 3.3V. The single-chip microcomputer 301-4 is connected to the output end of the voltage conditioning unit 301-3, that is, the single-chip microcomputer 301-4 receives the preprocessed spot horizontal signal, spot vertical signal, and total light intensity signal output by the voltage conditioning unit 301-3, and graphically displays the above-mentioned received signals through the display device. In this embodiment, the display device may specifically be a display screen 301-5.

[0048] When the cantilever probe works in the static mode, the lock-in amplifier module 302 receives the vertical light spot signal input by the signal channel, and demodulates the AC information carried by the vertical light spot signal to obtain the amplitude R, the phase θ, the X component R X and the Y component R Y . In addition, the lock-in amplifier module 302 can also generate an AC excitation signal and output it through the reference channel. The Figure 3 lock-in amplifier module 302 can include one or more channels with the same function to meet different application requirements. Exemplarily, in the AFM system, the reference channel of the lock-in amplifier module 302 outputs an AC excitation signal with a specific frequency and voltage as a waveform generator to cause the microcantilever to vibrate. At the same time, the position detector detects the optical signal of the position change. After being processed by the analog signal conditioning and interface module 301, the normalized vertical light spot signal is sent to the lock-in amplifier module 302 to demodulate the amplitude R and the phase θ of the vibration, or the rectangular coordinate system components R X and R Y . Further, the amplitude R, the phase θ, the X component R X and the Y component R Y demodulated by the lock-in amplifier module 302 are sent to the XY-axis scanning control and imaging signal acquisition module 303 as imaging signals, and the demodulated amplitude R and phase θ are sent to the Z-axis control module 304 as feedback signals. Exemplarily, the lock-in amplifier module 302 includes the OE1300 series modular lock-in amplifier, and in some embodiments, the redundant lock-in amplifier module 302 can be functionally expanded according to actual needs in other electrical and magnetic modes.

[0049] The XY-axis scanning control and imaging signal acquisition module 303 generates XY control signals for driving the piezoelectric scanning stage to move in the X and Y directions, so as to complete the scanning on the XY plane and the acquisition of synchronous multi-channel imaging signals. This module is based on the instructions and data sent by the host computer 100 received, and generates a scanning waveform, that is, an XY control signal, through hardware timing. The output end of the XY-axis scanning control and imaging signal acquisition module 303 is connected to the control system of the piezoelectric scanning stage, that is, the XY control signal output by the XY-axis scanning control and imaging signal acquisition module 303 is sent to the control system of the piezoelectric scanning stage, thereby realizing the quantitative movement of the piezoelectric scanning stage in the X and Y axis directions. The inputs of the XY-axis scanning control and imaging signal acquisition module 303 include the Z-direction control signal output by the Z-axis control module 304, and the amplitude, phase, or X component and Y component output by the lock-in amplifier module 302. In addition, in order to better detect the scanning waveform, this module also collects the output voltage as the position monitoring signals X' and Y'; and in order to facilitate the expansion of functions, this module correspondingly also has redundant acquisition channels, and the redundant acquisition channels can be used as auxiliary channels for imaging. In addition, the XY-axis scanning control and imaging signal acquisition module 303 can also generate a scanning synchronization signal and a lifting control signal for controlling the probe to lift.

[0050] Exemplarily, referring to Figure 4 , the XY-axis scanning control and imaging signal acquisition module 303 can adopt a USB5515 data acquisition card, which uses a high-performance FPGA sub-module as the main control chip and has 16 channels of 18-bit 1M single-ended analog inputs and two channels of 16-bit 2M analog outputs. In a specific scanning process, according to the maximum scanning range of the piezoelectric scanning stage and the upper and lower voltage limits of its corresponding scanning range, parameters such as the size of the scanning range, the position of the center point of the scanning area, the image resolution, the line scanning frequency, and the deflection angle of the scanning area are set, and further the scanning waveform data in the XY plane is obtained. The host computer 100 sends this scanning waveform data to the main control chip of the XY-axis scanning control and imaging signal acquisition module 303 through the communication bus 200.

[0051] In a specific embodiment, taking the static mode of the optical lever type AFM probe as an example: the XY scanning waveform can cover the entire scanning area. During imaging, the piezoelectric scanning stage moves point by point on the XY plane and records the voltage in the Z direction of the piezoelectric scanning stage at each point (synchronized with the scanning waveform) during the scanning process and the optical signal output by the probe position detector, and respectively performs real-time imaging on the software interface in the topography channel, the probe deflection channel, and the lateral force channel. Taking the dynamic mode of the optical lever type AFM probe as an example: by recording the voltage in the Z direction of the piezoelectric scanning stage at each point during the scanning process, and the amplitude R and phase θ signals output by the lock-in amplifier module 302, respectively perform real-time imaging on the software interface in the topography channel, the amplitude channel, and the phase channel.

[0052] Further, the Z-axis control module 304 obtains the lift control signal sent by the XY-axis scanning control and imaging signal acquisition module 303 and the sampling clock of the XY-axis scanning control and imaging signal acquisition module 303, and generates a third Z-axis control signal for driving the piezoelectric scanning stage to move in the Z direction based on the obtained lift control signal and sampling clock.

[0053] Reference Figure 5 , the Z-axis control module 304 may include a first multiplexer 304-1, an FPGA sub-module, and a second multiplexer 304-2. The input end of the first multiplexer 304-1 is connected to both the analog signal conditioning and interface module 301 and the lock-in amplifier module 302. The output end of the first multiplexer 304-1 is connected to the input end of the FPGA sub-module. The output end of the FPGA sub-module is connected to the input end of the second multiplexer 304-2. The output end of the second multiplexer 304-2 is connected to the XY-axis scanning control and imaging signal acquisition module 303.

[0054] The Z-axis control module 304 is mainly used to control the movement of the piezoelectric scanning stage in the Z-axis direction. This module can select input signals through the first multiplexer 304-1. For example, in the AFM static mode, the first multiplexer 304-1 is selected to connect the light spot vertical signal, and in the AFM dynamic mode, the first multiplexer 304-1 is selected to connect the amplitude R output by the lock-in amplifier. Among them, the first multiplexer 304-1 can be a multiplexer switch circuit composed of SW06 chips. The FPGA sub-module specifically includes a digital PID and comparator unit, a Z data buffer unit, and an output filtering unit. The FPGA sub-module of this module calculates in real time the control signal for controlling the movement of the piezoelectric scanning stage in the Z direction through a proportional-integral-derivative (PID) control mechanism according to the input signal. Similarly, this module also provides redundant multi-channel digital PID loops for easy function expansion.

[0055] In the above embodiments, the core part of the Z-axis control module 304 is a digital PID controller developed based on FPGA. When setting feedback control parameters such as P ratio, I integral, and D derivative for the Z-axis control module 304, since the derivative link is prone to amplifying system noise and reducing the system signal-to-noise ratio, proportional and integral regulation, i.e., PI control, is preferentially adopted in the digital PID control algorithm used by the Z-axis control module 304. At the same time, a voltage comparator is also provided in the FPGA digital PID controller of this module to enable the stepper motor to send a stop signal to prevent needle collision. The voltage comparator is used to compare the magnitude between the input signal and the set point, that is, the Z-axis control module 304 compares the received light spot vertical signal or amplitude with the preset value, and generates a motor control signal based on the comparison result. This motor control signal is specifically the automatic stop signal of the motor.

[0056] In addition, the host computer 100 can also directly send movement data to the Z-axis control module 304 and load it into the data buffer area, so as to control the movement of the piezoelectric scanning stage in the Z direction based on the scanning curve signal sent by the host computer 100 cached in this data buffer area. In addition to the above, as can be seen from Figure 5 the Z-axis control module 304 can also further receive the probe lift signal and sampling clock sent by the XY-axis scanning control and imaging signal acquisition module 303, and complete data calculation in combination with the height data in the data buffer area to determine the lift height, and synchronously execute the Z-direction movement. In this embodiment, when the probe lift signal arrives, the output of the Z-axis control module 304 is switched to the Z control signal corresponding to the lift height through the second multiplexer, and the piezoelectric scanning stage is directly driven to move in the Z direction with this data to provide the function of lift-mode imaging. It can be understood that in this embodiment, the Z-direction control signal is the first Z-direction control signal, the second Z-direction control signal, or the third Z-direction control signal, that is, the Z-axis control module 304 selects the first Z-direction control signal, the second Z-direction control signal, or the third Z-direction control signal according to the second multiplexer, where the first Z-direction control signal is the signal generated by the Z-axis control module 304 based on the received light spot horizontal signal, light spot vertical signal, amplitude, and phase.

[0057] The motor control module 305 is mainly used to control the stepper motor driving the probe, so as to realize the coarse adjustment functions such as continuous or single-step rising, falling, and stopping of the probe, or the function of automatically approaching the sample by the probe; the motor control module 305 supports the synchronous control of multiple motors. The output signal of the motor control module 305 is sent to the driving motor of the probe head, and this motor driving module can also receive the stop signal output by the Z-axis control module 304. Refer to Figure 6, in this embodiment, the motor control module 305 uses a Pico single-chip microcomputer as the main control, which contains two parallel threads. Thread 1 executes the serial port listening task, and thread 2 receives the parking signal sent from the Z-axis control module and determines whether to execute the stepping task based on this. If the parking signal is valid, it controls the motor to stop rotating immediately. In addition, based on the software interaction, commands can be sent to the motor control module 305 through the motor control sub-software. For example, in the software, continuous needle insertion or continuous needle withdrawal tasks can be executed through the "up" and "down" buttons, single-step needle insertion or single-step needle withdrawal tasks can be executed through the "single step forward" and "single step backward" buttons, automatic needle insertion tasks can be executed through the "automatic needle insertion" button, and all tasks of the motor can be immediately stopped through the "stop" button; the motor running speed can also be fine-tuned through the "speed +" and "speed -" in the software.

[0058] For each independent module in the above-mentioned lower computer 300, except for the analog signal conditioning and interface module 301, each module can be equipped with software control and data acquisition programs for the graphical user interface to facilitate human-computer interaction. Specifically, the software of the lock-in amplifier module 302 includes programs such as frequency scanning, drive frequency setting, and elastic constant measurement. The software of the XY-axis control and imaging signal acquisition module includes programs for setting parameters such as the scanning area, range, scanning time / speed, sampling rate, and number of sampling points; this software program can also collect data from multi-channel scans and create a color scale for real-time display; in addition, this software program can automatically save the imaging data and be compatible with common image post-processing software. The software of the Z-axis control module 304 can select the working mode of the SPM system by switching the multiplexer, and can set parameters such as the limit point, P ratio, I integral, D derivative of the Z-axis control module 304, as well as the amplitude limit value of the output signal; in addition, the software program of the Z-axis control module 304 supports the setting of the lift height in the lift mode. The motor control software includes serial communication functions and can realize coarse adjustment functions such as automatic approach, continuous or single-step up, down, and stop of the motor.

[0059] The open modular scanning probe microscope control system disclosed in the above embodiment can cover SPM imaging tasks including static mode, dynamic mode, force curve, and probe lift mode, etc., and it also has strong adaptability to the probe. Figure 7Schematic diagram of the application of the open modular scanning probe microscope control system according to an embodiment of the present invention in a light-lever atomic force microscope. In this embodiment, the analog signal conditioning and interface module 301 mainly processes the analog signals from the quadrant photodetector. The lock-in amplifier module 302 mainly provides the AC excitation signal and processes the AC part of the analog signals from the quadrant photodetector. The XY-axis scanning control and imaging signal acquisition module 303 mainly performs the acquisition of scanning and imaging signals. The Z-axis control module 304 mainly processes the mode switching and feedback control. The motor control module 305 is mainly responsible for implementing the coarse approach function. Figure 8 Schematic diagram of the application of the open modular scanning probe microscope control system according to an embodiment of the present invention in a quartz tuning fork atomic force microscope. In this embodiment, the application mode of the open modular scanning probe microscope control system is Figure 7 substantially similar to the application mode of the control system in the light-lever atomic force microscope shown.

[0060] It can be found from the above embodiments that the open modular scanning probe microscope control system disclosed by the present invention is composed of multiple independent sub-modules, and each sub-module includes an independent main control chip. This control system has good adaptability to the probe microscope, and different parameters can be configured for each module according to actual needs. The open modular scanning probe microscope control system uses multiple independent sub-modules to complete the control of the scanning probe microscope, and it is easy to detect the abnormal states of each module. Furthermore, it is convenient to improve the control accuracy, sampling rate, and shorten the response time of the microscope control system, thereby facilitating the improvement of the performance of the microscope control system and the realization of the function expansion of the microscope control system.

[0061] Those of ordinary skill in the art should understand that the various exemplary components, systems, and methods described in connection with the embodiments disclosed herein can be implemented in hardware, software, or a combination of both. Specifically, whether to implement in hardware or software depends on the specific application and design constraints of the technical solution. A person skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present invention. When implemented in hardware, it can be, for example, an electronic circuit, an application-specific integrated circuit (ASIC), appropriate firmware, a plug-in, a functional card, and so on. When implemented in software, the elements of the present invention are programs or code segments used to perform the required tasks. The program or code segment can be stored in a machine-readable medium or transmitted over a transmission medium or communication link via a data signal carried in a carrier wave. A "machine-readable medium" can include any medium that can store or transmit information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical discs, hard disks, fiber optic media, radio frequency (RF) links, and so on. The code segment can be downloaded via a computer network such as the Internet, an intranet, and so on.

[0062] It should also be noted that the exemplary embodiments mentioned in the present invention describe some methods or systems based on a series of steps or devices. However, the present invention is not limited to the order of the above steps, that is, the steps can be executed in the order mentioned in the embodiments, can be different from the order in the embodiments, or several steps can be executed simultaneously.

[0063] In the present invention, the features described and / or illustrated for one embodiment can be used in the same or similar manner in one or more other embodiments, and / or combined with the features of other embodiments or replace the features of other embodiments.

[0064] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, various changes and modifications can be made to the embodiments of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An open modular scanning probe microscope control system, characterized in that, The control system includes: An analog signal conditioning and interface module, which is used to connect with the position detector of the scanning probe microscope probe. The analog signal conditioning and interface module receives the force sensor signal collected by the position detector. A lock-in amplifier module, which is connected to the analog signal conditioning and interface module. The lock-in amplifier module receives the force sensor signal output by the analog signal conditioning and interface module, and determines the amplitude, phase, X component, and Y component of the force sensor signal based on the received force sensor signal. A Z-axis control module, which is connected to both the analog signal conditioning and interface module and the lock-in amplifier module. The Z-axis control module receives the force sensor signal output by the analog signal conditioning and interface module, as well as the amplitude and phase output by the lock-in amplifier module, and generates a Z-axis control signal for driving the piezoelectric scanning stage to move in the Z direction. An XY-axis scanning control and imaging signal acquisition module, which is connected to both the lock-in amplifier module and the Z-axis control module. The XY-axis scanning control and imaging signal acquisition module receives the amplitude, phase, or X component, Y component output by the lock-in amplifier module, as well as the Z-axis control signal output by the Z-axis control module, and generates an XY control signal for driving the piezoelectric scanning stage to move in the X direction and Y direction. The force sensor signal is an optical signal or an electrical signal. When the force sensor signal is an optical signal, the force sensor signal includes a light spot horizontal signal and a light spot vertical signal; and / or The XY-axis scanning control and imaging signal acquisition module generates a lift control signal for controlling the probe to lift. The analog signal conditioning and interface module includes a divider, a voltage conditioning unit, a single-chip microcomputer, and a display device. The input end of the divider is connected to the position detector, the output end of the divider is connected to both the input ends of the lock-in amplifier module and the voltage conditioning unit, the output end of the voltage conditioning unit is connected to the input end of the single-chip microcomputer, and the output end of the single-chip microcomputer is connected to the display device.

2. The open modular scanning probe microscope control system according to claim 1, characterized in that, The control system further includes a host computer, which is connected to the analog signal conditioning and interface module, the lock-in amplifier module, the Z-axis control module, and the XY-axis scanning control and imaging signal acquisition module; and / or The Z-axis control module obtains the lift control signal and the sampling clock of the XY-axis scanning control and imaging signal acquisition module.

3. The open modular scanning probe microscope control system according to claim 2, wherein The Z-axis control signal is a first Z-axis control signal, a second Z-axis control signal, or a third Z-axis control signal; The first Z-axis control signal is a signal generated by the Z-axis control module based on the received light spot horizontal signal, light spot vertical signal, amplitude, and phase. The second Z-axis control signal is a signal sent by the host computer to the Z-axis control module. The third Z-axis control signal is a signal generated by the Z-axis control module based on the obtained lift control signal and sampling clock.

4. The open modular scanning probe microscope control system according to claim 2, wherein The Z-axis control module compares the received light spot vertical signal or amplitude with a preset value, and generates a motor control signal based on the comparison result.

5. The open modular scanning probe microscope control system according to claim 4, wherein The control system further includes a motor control module, which is connected to the Z-axis control module and is configured to control the working state of the probe motor based on the received motor control signal.

6. The open modular scanning probe microscope control system according to claim 1, characterized in that, The lock-in amplifier module includes an OE1300 series modular lock-in amplifier.

7. The open modular scanning probe microscope control system according to claim 3, wherein The Z-axis control module includes a first multiplexer, an FPGA sub-module, and a second multiplexer. The input end of the first multiplexer is connected to both the analog signal conditioning and interface module and the lock-in amplifier module. The output end of the first multiplexer is connected to the input end of the FPGA sub-module. The output end of the FPGA sub-module is connected to the input end of the second multiplexer. The output end of the second multiplexer is connected to the XY-axis scanning control and imaging signal acquisition module.

8. The open modular scanning probe microscope control system according to any one of claims 1 to 7, characterized in that The analog signal conditioning and interface module, the lock-in amplifier module, the Z-axis control module, and the XY-axis scanning control and imaging signal acquisition module are all provided with independent main control chips.

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