Anti-crosstalk multi-axis nanoscale displacement table and control method and application thereof

Abstract

The invention belongs to the technical field of precise instruments, and particularly relates to an anti-crosstalk multi-axis nanoscale displacement table and a control method and application thereof. The displacement table comprises an objective table, a base, a bottom cover plate and four groups of piezoelectric ceramic actuators symmetrically distributed at four corners of the base; and each group of actuators is integrated with a four-connecting-rod five-hinge shell and a piezoelectric ceramic driving unit, and is connected with the objective table through a limiting flexible hinge. The output displacement of the four groups of actuators is cooperatively controlled, so that differential deformation of the limiting flexible hinge is generated, and the objective table is driven to realize Z-direction translation and deflection composite motion around the X / Y axis. The three sets of capacitive displacement sensors monitor pose changes in real time, and nanoscale positioning is achieved in combination with a closed-loop control algorithm. The design significantly reduces multi-axis motion crosstalk, is suitable for precise collimation and focusing of an optical system, and has the advantages of high positioning precision and fast dynamic response.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical system precision collimation and focusing technology, in particular to an anti-crosstalk multi-axis nanometer displacement stage and its control method and application. BACKGROUND

[0002] In the fields of optical precision collimation, semiconductor wafer detection, and quantum state manipulation, the precision requirements for the compound motion of the displacement stage Z translation (vertical degree of freedom) and X / Y axis yaw (rotational degree of freedom) have broken through the nanometer level (≤1 nm). However, the current multi-axis displacement stage faces three major technical bottlenecks: uncontrollable motion crosstalk, accumulated bending moment of rigid structure, and insufficient dynamic response bandwidth. The central driver configuration is usually adopted for parallel piezoelectric platforms, which induces parasitic yaw around the X / Y axis when the Z displacement occurs, leading to the drift of the optical system focal point and seriously degrading the beam collimation precision. The cascade mechanical architecture is relied on for serial platforms, which causes nonlinear angular errors due to the interlayer bending moment transmission during yaw motion, resulting in misalignment of the objective lens positioning. Although the flexible hinge platform can suppress mechanical coupling, the low stiffness guide shell limits the resonant frequency, making it difficult to meet the millisecond-level dynamic focusing requirements of high-speed atomic force microscopes and other applications.

[0003] Prior Art 1: Invention name: A large load piezoelectric yaw stage, publication number: CN 119467978 A, this technical solution realizes θ X, θ Y two-axis deflection and Z-axis linear motion by arranging 2 amplification piezoelectric drivers in the X-axis direction, 2 amplification piezoelectric drivers in the Y-axis direction, and 4 amplification piezoelectric drivers in the Z-axis direction, totaling 8 drivers, which has the same target as the present application in terms of motion degrees of freedom (3 degrees of freedom). However, there are significant differences between the displacement stage of the present application and the implementation of this technology. In terms of structure and quantity, the amplification piezoelectric drivers, flexible hinges, and displacement sensors of this technology are fundamentally different from the design of the present application in terms of specific structure and quantity configuration. In terms of driving scheme, this technology uses up to 8 piezoelectric drivers to achieve three degrees of freedom motion, and the driving architecture is relatively complex. In terms of sensor system control, it uses more strain sensors, which increases the complexity of the sensor system and further requires higher processing capacity and precision of the control system.

[0004] Therefore, there is an urgent need for a nanometer displacement stage that can eliminate crosstalk from the mechanical structure level and achieve truly independent and high-precision control of Z translation and yaw degrees of freedom. SUMMARY

[0005] To overcome the shortcomings of the prior art, the present application provides an anti-crosstalk multi-axis nanometer displacement stage and its control method and application, which can realize the compound motion of the displacement stage Z translation (vertical degree of freedom) and X / Y axis yaw (rotational degree of freedom), and has the advantages of anti-crosstalk, high positioning precision, and high dynamic response.

[0006] The technical solution of the present invention is as follows:

[0007] On the one hand, the present invention provides an anti-crosstalk multi-axis nanoscale displacement stage, characterized in that it includes:

[0008] The base has an "I" shaped cross-section, forming an independent upper cavity and lower cavity;

[0009] A stage is used to support loads.

[0010] Four sets of “L”-shaped limiting flexible hinges are symmetrically arranged in the upper cavity of the base. The two ends of each set of the limiting flexible hinges are fixedly connected to the base, and the middle part is fixedly connected to the platform, thereby connecting the platform to the base in a flexible support manner.

[0011] Four sets of drive components are circumferentially symmetrically arranged in the lower cavity of the base. Each set of drive components includes a piezoelectric ceramic actuator. The piezoelectric ceramic actuator integrates a four-bar five-hinge housing for displacement amplification and a piezoelectric ceramic drive unit. Each piezoelectric ceramic actuator has a guide rod at its output end. The guide rod passes upward through the base, the partition between the lower cavity and the upper cavity, and the guide hole on the corresponding limiting flexible hinge. Its end makes point contact with the bottom surface of the stage, thereby constructing a force transmission path from the drive components to the stage.

[0012] The displacement sensing system includes three sensor target plates fixed to the bottom surface of the stage and three sensor probes fixed to the upper cavity of the base and arranged opposite to the sensor target plates.

[0013] Furthermore, the four-bar five-hinge housing applies and maintains axial preload on the piezoelectric ceramic drive unit through its own controllable elastic deformation.

[0014] Furthermore, the four-link five-hinge housing includes five flexible hinges with unequal thicknesses: the first hinge has a thickness of 0.2mm, the second hinge has a thickness of 0.3mm, the third hinge has a thickness of 0.4mm, the fourth hinge has a thickness of 0.3mm, and the fifth hinge has a thickness of 0.4mm, in order to optimize the displacement amplification ratio and structural stiffness.

[0015] Furthermore, the “L”-shaped limiting flexible hinge has a limiting hole in the middle, and its thinnest part is 0.2mm thick. In this way, while providing the required flexibility, the limiting hole and the guide rod cooperate to achieve lateral constraint on the movement of the guide rod.

[0016] Further, a pre-tightening force adjusting mechanism is arranged between the end of the guide rod and the object table, for applying and adjusting the pre-tightening force at the point contact.

[0017] Further, the sensor probe in the displacement sensing system is a capacitive displacement sensor.

[0018] Secondly, the application also provides a method for controlling the anti-crosstalk multi-axis nanometer displacement table, which comprises:

[0019] The Z-direction displacement of three non-collinear measuring points on the object table is measured in real time by the three sensor probes;

[0020] Based on the three-point positioning principle, the translation amount of the object table in the Z direction and the deflection angles around the X and Y axes are calculated according to the Z-direction displacement of the three non-collinear measuring points;

[0021] A closed-loop control algorithm is adopted, and the output of the four groups of piezoelectric ceramic actuators is independently or cooperatively controlled according to the deviation of the calculated translation amount and deflection angle from the target value;

[0022] When the object table is controlled to translate in the Z direction, the same driving signal is applied to the four groups of actuators, so that the guide rod synchronously pushes the object table, and at this time, the cooperation of the guide hole of the limiting flexible hinge and the guide rod suppresses the parasitic deflection around the X and Y axes; when the object table is controlled to deflect around the X or Y axis, different driving signals are applied to at least one group of actuators than the other groups of actuators, so that the limiting flexible hinge produces cooperative and non-uniform elastic deformation, thereby driving the object table to deflect while suppressing the parasitic translation in the Z direction.

[0023] Further, the closed-loop control algorithm is a PID control algorithm, and the Z-direction displacement closed-loop control resolution of the displacement table reaches 0.8 nm, and the closed-loop control resolution of the deflection angle around the X and Y axes reaches 0.05 μrad.

[0024] Further, when the deflection around the X axis is controlled, the first driving voltage is applied to the two groups of actuators located on the same side of the X axis, and the second driving voltage different from the first driving voltage is applied to the two groups of actuators located on the other side of the X axis.

[0025] Thirdly, the application provides an application of the anti-crosstalk multi-axis nanometer displacement table in the optical system precision collimation and focusing, semiconductor wafer detection, atomic force microscope or quantum bit manipulation system.

[0026] Compared with the prior art, the application has the beneficial effects that:

[0027] 1) Piezoelectric ceramic actuator includes four-bar five-hinged shell and piezoelectric ceramic drive unit. Among them, the four-bar five-hinged shell is fixedly connected with the piezoelectric ceramic drive unit through interference fit, when different voltages are applied to the piezoelectric ceramic drive unit, the piezoelectric ceramic generates nanoscale deformation along its long axis direction, and exerts a pushing force on the four-bar five-hinged shell. The pushing force drives the connecting rod to rotate around the hinge, and causes different degrees of elastic deformation of each hinge; at the same time, it pushes the guide rod to produce upward displacement. Thus, the small displacement of the end face of the piezoelectric ceramic drive unit is converted and amplified into the vertical upward displacement of the guide rod.

[0028] 2) Anti-crosstalk multi-axis nanoscale displacement stage effectively eliminates motion crosstalk through unique mechanical structure limiting and differential deformation design of limiting flexible hinge. Its four-bar five-hinged shell is integrated with guide rod design. The guide rod successively passes through the corresponding mounting holes on the base and the limiting flexible hinge, and the end forms a point contact with the object table and applies a pre-tightening force through a pre-tightening screw. This combination of rigid mechanical limiting and differential deformation of flexible hinge design realizes the motion decoupling of three degrees of freedom of Z-direction translation and rotation around X / Y-axis, and significantly suppresses the crosstalk between multi-axis motion. When the object table needs to perform Z-direction translation, the piezoelectric ceramic actuator converts and amplifies the elongation displacement of the end face of the piezoelectric ceramic drive unit into the displacement output of the guide rod along the Z-axis direction (upward). In this process, the precise through holes on the base and the limiting flexible hinge effectively limit the parasitic yaw (crosstalk) around the X / Y-axis direction. When the rotation around the X / Y-axis is needed, four groups of piezoelectric ceramic actuators use asymmetric (differential) driving voltage input. Correspondingly, the limiting flexible hinge produces a coordinated, non-uniform elastic deformation. This coordinated deformation mechanism can effectively suppress the Z-direction parasitic translation (crosstalk) generated during the yaw motion.

[0029] 3) Anti-crosstalk multi-axis nanoscale displacement stage is configured with three groups of displacement sensor probes, which are symmetrically arranged at the three corner positions of the object table. Its control principle is based on three-point positioning method, when driving the object table to perform Z-direction translation, three groups of sensor probes synchronously measure the Z-direction displacement of the corresponding measuring points in real time. The control system accurately adjusts the actuator output according to the three-point displacement data through closed-loop control algorithm (such as PID), to ensure the high precision of the overall Z-direction displacement of the object table plane. When driving the object table to perform yaw motion around the X-axis or Y-axis, three groups of sensor probes also synchronously measure the Z-direction displacement of the corresponding measuring points in real time. The control system calculates the current tilt plane of the object table (i.e. the yaw angle around the X / Y-axis) according to the displacement difference of the three measuring points. Based on the tilt angle information calculated, the closed-loop control system accurately adjusts the differential driving amount of each group of actuators, to ensure the control precision of the yaw angle around the X-axis and Y-axis. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 This is an exploded view of the anti-crosstalk multi-axis nanoscale displacement stage in an embodiment of the present invention.

[0031] Figure 2 This is an isometric side view of the anti-crosstalk multi-axis nanoscale displacement stage in an embodiment of the present invention.

[0032] Figure 3 This is a cross-sectional view of the anti-crosstalk multi-axis nanoscale displacement stage in an embodiment of the present invention.

[0033] Figure 4 This is a top view of the anti-crosstalk multi-axis nanoscale displacement stage hidden behind the stage in an embodiment of the present invention.

[0034] Figure 5 This is a schematic diagram of the limiting flexible hinge structure in an embodiment of the present invention.

[0035] Figure 6 This is a cross-sectional view of the piezoelectric ceramic actuator in an embodiment of the present invention.

[0036] Figure 7 This is an isometric side view of the piezoelectric ceramic actuator in an embodiment of the present invention.

[0037] Figure 8 This is a front view of the piezoelectric ceramic actuator in an embodiment of the present invention.

[0038] Figure 9 This is a schematic diagram illustrating the working principle of the piezoelectric ceramic actuator in an embodiment of the present invention.

[0039] Figure 10 This is a schematic diagram of the deformation of the ceramic after the piezoelectric ceramic actuator elongates when a voltage is applied in an embodiment of the present invention.

[0040] Numbered in the diagram: 1. Stage; 2-1. First sensor target plate; 2-2. Second sensor target plate; 2-3. Third sensor target plate; 3-1. First limiting flexible hinge; 3-2. Second limiting flexible hinge; 3-3. Third limiting flexible hinge; 3-4. Fourth limiting flexible hinge; 4-1. First sensor probe; 4-2. Second sensor probe; 4-3. Third sensor probe; 5. Base; 6-1. First piezoelectric ceramic actuator; 6-2. Second piezoelectric ceramic actuator; 6-3. Third piezoelectric ceramic actuator; 6-4. Fourth piezoelectric ceramic actuator; 7. Bottom cover plate; 8. Four-bar five-hinge housing; 9. Piezoelectric ceramic drive unit. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0042] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0043] like Figure 1 As shown, the present invention provides an exploded view of an anti-crosstalk multi-axis nanostage, including a stage 1, a first sensor target plate 2-1, a second sensor target plate 2-2, a third sensor target plate 2-3, a first limiting flexible hinge 3-1, a second limiting flexible hinge 3-2, a third limiting flexible hinge 3-3, a fourth limiting flexible hinge 3-4, a first sensor probe 4-1, a second sensor probe 4-2, a third sensor probe 4-3, a base 5, a first piezoelectric ceramic actuator 6-1, a second piezoelectric ceramic actuator 6-2, a third piezoelectric ceramic actuator 6-3, a fourth piezoelectric ceramic actuator 6-4, a bottom cover plate 7, a four-bar five-hinge housing 8, and a piezoelectric ceramic drive unit 9.

[0044] like Figure 2 As shown in the isometric view of the anti-crosstalk multi-axis nanoscale displacement stage provided by the present invention, the stage 1 is flexibly connected to the base 5 through flexible hinges 3-1, 3-2, 3-3, and 3-4 symmetrically distributed at the four corners of the upper cavity of the base 5. The Z-axis translational motion of this displacement stage is defined as linear motion along the positive Z-axis (upward) perpendicular to the initial plane of the stage 1. The yaw motion around the X-axis or Y-axis is defined as the angular displacement motion of the stage 1 around the virtual rotation axis of the X-axis or Y-axis located near the central plane of the stage 1, as illustrated in the diagram. Figure 2 As shown.

[0045] like Figure 3 and Figure 4 As shown in the schematic diagram, the cross-sectional structure of the anti-crosstalk multi-axis nanoscale displacement stage of the present invention is as follows: a sensor target plate, a limiting flexible hinge, and a sensor probe are disposed in the upper cavity of the base 5. The sensor target plate is fixedly installed on the bottom surface of the stage 1 (connected by screws). The sensor probe is fixedly installed on the inner wall of the upper cavity of the base 5 (connected by screws). Figure 5 The diagram shows the structural features of the limiting flexible hinge, which is L-shaped overall. A functional limiting hole is designed at the bend (middle) of the L-shape. Threaded holes are provided on both sides of the middle limiting hole for connection and fixation to the platform 1 using screws. Threaded holes are also provided at both ends for connection and fixation to the base 5 using screws.

[0046] The detailed structure of the piezoelectric ceramic actuator is as follows: Figure 6 , Figure 7 , Figure 8As shown, its core components are a four-bar, five-hinge housing 8 and a piezoelectric ceramic drive unit 9, which are rigidly connected and fixed through an interference fit. During assembly, a preload is generated by the controllable elastic deformation of the four-bar, five-hinge housing 8, which applies and maintains a reliable preload on the piezoelectric ceramic drive unit 9. Figure 8 As shown, the four-link, five-hinge housing 8 specifically includes four rigid links and five flexible hinges, wherein the thickness of hinge one is 0.2mm, the thickness of hinge two is 0.3mm, the thickness of hinge three is 0.4mm, the thickness of hinge four is 0.3mm, and the thickness of hinge five is 0.4mm; a guide rod structure is integrated on the four links.

[0047] A schematic diagram of the working principle of a piezoelectric ceramic actuator is shown below. Figure 9 As shown, the deformation of its piezoelectric ceramic drive unit 9 under the action of driving force is illustrated in the figure. Figure 10 As shown. When a specific voltage is applied to the piezoelectric ceramic drive unit 9, the end face of the piezoelectric ceramic drive unit 9 applies a horizontal rightward thrust to the connecting rod 2. Because there is a fixed distance between the center of hinge two and the center of hinge one. This horizontal thrust A counterclockwise torque is generated on link two about hinge one. Under this torque, link two rotates counterclockwise around hinge one, and hinges one, two, three, four, and five undergo coordinated but non-uniform elastic deformation. This motion ultimately drives link four to produce a vertically upward displacement. Output. Thus, the minute input displacement of the piezoelectric ceramic drive unit 9 end face... This is converted and amplified into the vertical upward displacement of the four ends of the connecting rod (guide rod). The output magnification ratio is determined by the mechanism design parameters of the four-bar five-hinge housing 8.

[0048] The working process of the anti-crosstalk multi-axis nanoscale displacement stage provided by this invention is as follows:

[0049] The displacement stage load with the lens is integrated into the precision collimation and focusing system of the optical system. When the system requires the lens to achieve Z-axis displacement... At that time, the host computer sends a Z-axis translation command to the displacement stage controller. The controller uses a kinematic algorithm to calculate the driving voltage values ​​of the four piezoelectric ceramic actuators 6-1, 6-2, 6-3, and 6-4. .Voltage Synchronously applied to the actuator, driving the piezoelectric ceramic to generate thrust. The actuator drives the stage 1 to move along the Z-axis. Three sets of sensor probes 4-1, 4-2, and 4-3 measure the displacement of the three points of the stage in real time. The displacement deviation is fed back to the controller, and the PID closed-loop system dynamically corrects the error until the target displacement is achieved. The stage reaches the target position, achieving nanometer-level Z-axis positioning.

[0050] When the system requires the lens to achieve a deflection angle around the X-axis At that time, the host computer sends a yaw command around the X-axis. The controller calculates the asymmetric drive voltage, and the drive voltages for actuators 6-1 and 6-4 are calculated. Actuator 6-2, 6-3 drive voltage ( ),Voltage , The force is applied to the corresponding actuators. Actuators 6-1, 6-4 and 6-2, 6-3 generate differentiated thrusts, causing the limiting flexible hinges 3-1, 3-4 and 3-2, 3-3 to undergo coordinated non-uniform elastic deformation. The stage 1 then produces a yaw motion around the X-axis. Simultaneously, sensors measure the displacement of the three points in real time and report the angular deviation. The PID system dynamically adjusts the drive voltage until the yaw angle is reached. The target is met, achieving micro-radian level yaw positioning around the X-axis. The yaw control logic around the Y-axis is consistent with that of the X-axis, achieving precise angle adjustment around the Y-axis through asymmetric drive of the actuator.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An anti-crosstalk multi-axis nanometric displacement stage, characterized in that, include: The base (5) has an "I" shaped cross-section, forming an independent upper cavity and lower cavity; The stage (1) is used to support the load; Four sets of "L"-shaped limiting flexible hinges (3-1, 3-2, 3-3, 3-4) are circumferentially symmetrically arranged in the upper cavity of the base (5). The two ends of each set of limiting flexible hinges are fixedly connected to the base (5), and the middle part is fixedly connected to the platform (1), thereby connecting the platform (1) to the base (5) in a flexible support manner. Four sets of drive components are symmetrically arranged in the lower cavity of the base (5). Each set of drive components includes a piezoelectric ceramic actuator (6-1, 6-2, 6-3, 6-4). The piezoelectric ceramic actuator integrates a four-bar five-hinge housing (8) for displacement amplification and a piezoelectric ceramic drive unit (9). Each piezoelectric ceramic actuator (6-1, 6-2, 6-3, 6-4) has a guide rod at its output end. The guide rod passes upward through the base (5), the partition between the lower cavity and the upper cavity, and the guide hole on the corresponding limiting flexible hinge. Its end makes point contact with the bottom surface of the stage (1) to construct a force transmission path from the drive components to the stage (1). The displacement sensing system includes three sensor target plates (2-1, 2-2, 2-3) fixed to the bottom surface of the stage (1) and three sensor probes (4-1, 4-2, 4-3) fixed to the upper cavity of the base (5) and arranged opposite to the sensor target plates.

2. The cross-talk resistant multi-axis nanometric displacement stage according to claim 1, wherein, The four-bar five-hinge housing (8) applies and maintains axial preload on the piezoelectric ceramic drive unit (9) through its own controllable elastic deformation.

3. The cross-talk resistant multi-shaft nanometric displacement stage according to claim 1 or 2, wherein, The four-link five-hinge housing (8) includes five flexible hinges with unequal thicknesses: the first hinge has a thickness of 0.2 mm, the second hinge has a thickness of 0.3 mm, the third hinge has a thickness of 0.4 mm, the fourth hinge has a thickness of 0.3 mm, and the fifth hinge has a thickness of 0.4 mm, in order to optimize the displacement amplification ratio and structural stiffness.

4. The cross-talk resistant multi-shaft nanometric displacement stage of claim 1, wherein, The "L"-shaped limiting flexible hinge (3-1, 3-2, 3-3, 3-4) has a limiting hole in the middle, and its thinnest part is 0.2mm thick. In this way, while providing the required flexibility, the limiting hole and the guide rod cooperate to achieve lateral constraint on the movement of the guide rod.

5. The cross-talk resistant multi-shaft nanometer displacement stage of claim 1, wherein, A preload adjustment mechanism is provided between the end of the guide rod and the platform (1) for applying and adjusting the preload at the point of contact.

6. The cross-talk resistant multi-shaft nanometric displacement stage of claim 1, wherein, The sensor probes (4-1, 4-2, 4-3) in the displacement sensing system are capacitive displacement sensors.

7. A method for controlling the cross-talk resistant multi-axis nanometric displacement stage according to any one of claims 1-6, characterized in that, include: The Z-direction displacement of three non-collinear measuring points on the stage (1) is measured in real time using the three sensor probes (4-1, 4-2, 4-3). Based on the three-point positioning principle, the translation of the stage (1) in the Z direction and the yaw angle around the X and Y axes are calculated according to the Z-direction displacement of the three non-collinear measuring points. A closed-loop control algorithm is adopted to independently or cooperatively control the output of the piezoelectric ceramic actuators (6-1, 6-2, 6-3, 6-4) according to the deviation of the calculated translation and yaw angle from the target value; When the stage (1) is controlled to move in the Z direction, the same driving signal is applied to the four groups of actuators, so that the guide rods synchronously push the stage (1), and at this time, the cooperation of the guide holes of the limiting flexible hinges and the guide rods suppresses the parasitic yaw around the X and Y axes; when the stage (1) is controlled to move around the X or Y axis, different driving signals are applied to at least one group of actuators than the other groups of actuators, so that the limiting flexible hinges (3-1, 3-2, 3-3, 3-4) produce cooperative and non-uniform elastic deformation, thereby driving the stage (1) to deflect while suppressing the parasitic translation in the Z direction.

8. The method for controlling the cross-talk resistant multi-axis nanometric displacement stage according to claim 7, wherein, The closed-loop control algorithm is a PID control algorithm, and the Z-direction displacement closed-loop control resolution of the displacement stage reaches 0.8 nm, and the closed-loop control resolution of the yaw angle around the X and Y axes reaches 0.05 μrad.

9. The method for controlling the cross-talk resistant multi-axis nanometric displacement stage according to claim 7, wherein, When the X-axis yaw control is performed, the first driving voltage is applied to the two groups of actuators (6-1, 6-4) located on the same side of the X axis, and the second driving voltage different from the first driving voltage is applied to the two groups of actuators (6-2, 6-3) located on the other side of the X axis.

10. The application of the anti-crosstalk multi-axis nanometer displacement stage according to any one of claims 1-6 in optical system precision collimation and focusing, semiconductor wafer detection, atomic force microscope or quantum bit manipulation system.

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