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

Abstract

The application belongs to the technical field of precision instruments, and particularly relates to an anti-crosstalk multi-axis nanometer displacement stage and a control method and application thereof. The displacement stage comprises a stage, a base, a bottom cover plate, and four groups of piezoelectric ceramic actuators symmetrically distributed at four corners of the base; each group of actuators is integrated with a four-bar five-hinge shell and a piezoelectric ceramic driving unit, and is connected with the stage through a limiting flexible hinge. The output displacements of the four groups of actuators are cooperatively controlled, so that the limiting flexible hinge generates differential deformation, and the stage is driven to realize Z-direction translation and composite motion of yaw around the X / Y axes. Three groups of capacitive displacement sensors monitor the position and pose changes in real time, and nanometer positioning is realized 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] This invention relates to the field of precision collimation and focusing technology for optical systems, and in particular to an anti-crosstalk multi-axis nanoscale displacement stage and its control method and application. Background Technology

[0002] In cutting-edge fields such as optical precision collimation, semiconductor wafer inspection, and quantum state manipulation, the required precision for the combined motion of Z-axis translation (vertical degree of freedom) and X / Y-axis yaw (rotational degree of freedom) of a displacement stage has broken through the nanometer level (≤1 nm). However, current multi-axis displacement stages face three major technical bottlenecks: uncontrollable motion crosstalk, accumulated bending moments in rigid structures, and insufficient dynamic response bandwidth. Parallel piezoelectric stages typically employ a central actuator configuration, and their Z-axis displacement induces parasitic yaw around the X / Y axes, causing focus drift in the optical system and severely degrading beam collimation accuracy. Series stages rely on cascaded mechanical structures, and the interlayer bending moment transmission during yaw motion causes nonlinear angular errors, resulting in inaccurate objective positioning. While flexible hinge stages can suppress mechanical coupling, the low-rigidity guide shell limits the resonant frequency, making it difficult to meet the millisecond-level dynamic focusing requirements of applications such as high-speed atomic force microscopes.

[0003] Prior Art 1: Invention titled "A Large-Load Piezoelectric Oscillating Stage," Publication No.: CN 119467978 A. This technical solution achieves θX and θY axis deflection and Z-axis linear motion by arranging two amplified piezoelectric actuators in the X-axis direction, two amplified piezoelectric actuators in the Y-axis direction, and four amplified piezoelectric actuators in the Z-axis direction, totaling eight actuators. Its motion degrees of freedom (3 degrees of freedom) are consistent with the objective of this invention. However, its implementation method differs significantly from the displacement stage of this invention. In terms of structure and quantity, the amplified piezoelectric actuators, flexible hinges, and displacement sensors in this technology are fundamentally different from the design of this invention in terms of specific structural forms and quantity configurations. In terms of the driving scheme, this technology uses as many as eight piezoelectric actuators to achieve three degrees of freedom of motion, resulting in a relatively complex driving architecture. In terms of sensing system control, it uses more strain sensors, leading to increased complexity of the sensing system and thus higher requirements for the processing power and accuracy of the control system.

[0004] Therefore, there is an urgent need for a nanoscale displacement stage that eliminates crosstalk at the mechanical structure level to achieve truly independent and high-precision control of the Z-axis translation and yaw degrees of freedom. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, this invention provides an anti-crosstalk multi-axis nanoscale displacement stage and its control method and application, which can realize the composite motion of Z-axis translation (vertical degree of freedom) and X / Y-axis yaw (rotational degree of freedom) of the displacement stage, and has the advantages of anti-crosstalk, high positioning accuracy 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] Furthermore, a preload adjustment mechanism is provided between the end of the guide rod and the platform to apply and adjust the preload at the point of contact.

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

[0018] Second, the present invention also provides a method for controlling the above-mentioned anti-crosstalk multi-axis nanoscale displacement stage, characterized in that it includes:

[0019] The Z-direction displacement of three non-collinear measuring points on the platform is measured in real time using the three sensor probes.

[0020] Based on the three-point positioning principle, the translation of the stage 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.

[0021] A closed-loop control algorithm is adopted to independently or collaboratively control the output of the four sets of piezoelectric ceramic actuators based on the deviation between the calculated translation and yaw angles and the target values.

[0022] Specifically, when the stage is controlled to translate in the Z direction, the same driving signal is applied to the four sets of actuators, causing the guide rod to push the stage synchronously. At this time, the cooperation between the guide hole of the limiting flexible hinge and the guide rod suppresses parasitic yaw around the X and Y axes. When the stage is controlled to yaw around the X or Y axis, a different driving signal is applied to at least one set of actuators than to the other set of actuators, causing the limiting flexible hinge to produce coordinated, non-uniform elastic deformation, thereby driving the stage to deflect and suppressing parasitic translation in the Z direction.

[0023] Furthermore, the closed-loop control algorithm is a PID control algorithm, and the Z-axis displacement closed-loop control resolution achieved by the displacement stage reaches 0.8 nm, while the closed-loop control resolution of the yaw angle around the X and Y axes reaches 0.05 μrad.

[0024] Furthermore, when performing yaw control around the X-axis, a first driving voltage is applied to two sets of actuators located on the same side of the X-axis, and a second driving voltage different from the first driving voltage is applied to two sets of actuators located on the other side of the X-axis.

[0025] Third, the present invention provides an application of the anti-crosstalk multi-axis nanoscale displacement stage as described above in optical system precision collimation and focusing, semiconductor wafer inspection, atomic force microscope or quantum bit manipulation system.

[0026] Compared with the prior art, the beneficial effects of this invention are as follows:

[0027] 1) The piezoelectric ceramic actuator comprises a four-bar, five-hinge housing and a piezoelectric ceramic drive unit. The four-bar, five-hinge housing and the piezoelectric ceramic drive unit are fixedly connected by an interference fit. When different voltages are applied to the piezoelectric ceramic drive unit, the piezoelectric ceramic undergoes nanoscale deformation along its long axis, applying a thrust to the four-bar, five-hinge housing. This thrust drives the second link to rotate around the first hinge, causing varying degrees of elastic deformation in each hinge; simultaneously, it pushes the guide rod to produce an upward displacement. Thus, the minute displacement of the piezoelectric ceramic drive unit's end face is converted and amplified into a vertically upward displacement of the guide rod.

[0028] 2) The anti-crosstalk multi-axis nanoscale displacement stage effectively eliminates motion crosstalk through a unique mechanical structure limiting and differentiated deformation design of the limiting flexible hinge. Its four-bar, five-hinge housing integrates a guide rod design. This guide rod passes sequentially through corresponding mounting holes on the base and the limiting flexible hinge, forming point contact with the stage at its end, and is preloaded by a preload screw. This design, combining rigid mechanical limiting and differentiated deformation of the flexible hinge, achieves motion decoupling of the three degrees of freedom: Z-axis translation and X / Y-axis deflection, significantly suppressing crosstalk between multi-axis motions. When the stage needs to translate in the Z-axis, the piezoelectric ceramic actuator converts and amplifies the elongation displacement of the piezoelectric ceramic drive unit end face into a displacement output of the guide rod along the Z-axis (upward). During this process, the constraint effect of the precision through holes on the base and the limiting flexible hinge effectively limits the parasitic yaw (crosstalk) generated around the X / Y axes. When yaw motion around the X / Y axes is required, the four sets of piezoelectric ceramic actuators employ asymmetrical (differentiated) drive voltage inputs. Correspondingly, the limiting flexible hinges generate coordinated, non-uniform elastic deformation. This coordinated deformation mechanism effectively suppresses parasitic Z-axis translation (crosstalk) generated during yaw motion.

[0029] 3) The anti-crosstalk multi-axis nanoscale displacement stage is equipped with three sets of displacement sensor probes, symmetrically arranged at the three corners of the stage along the circumference. Its control principle is based on the three-point positioning method. When the stage is driven to perform Z-axis translational motion, the three sets of sensor probes synchronously measure the Z-axis displacement of their corresponding measuring points in real time. Based on the three-point displacement data, the control system precisely adjusts the actuator output through a closed-loop control algorithm (such as PID) to ensure high accuracy of the overall Z-axis displacement of the stage plane. When the stage is driven to perform yaw motion around the X-axis or Y-axis, the three sets of sensor probes also synchronously measure the Z-axis displacement of their corresponding measuring points in real time. Based on the difference in displacement at the three measuring points, the control system calculates the current tilt plane of the stage (i.e., the yaw angle around the X / Y axis). Based on this calculated tilt angle information, the closed-loop control system precisely adjusts the differentiated drive quantities of each set of actuators, thereby ensuring the control accuracy of the yaw angle around the X and Y axes. Attached Figure Description

[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. A crosstalk-resistant multi-axis nanoscale 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. 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.

2. The anti-crosstalk multi-axis nanoscale displacement stage according to claim 1, characterized in that, 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 anti-crosstalk multi-axis nanoscale displacement stage according to claim 1, characterized in that, 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.

4. The anti-crosstalk multi-axis nanoscale displacement stage according to claim 1, characterized in that, 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.

5. The anti-crosstalk multi-axis nanoscale displacement stage according to claim 1, characterized in that, The sensor probes (4-1, 4-2, 4-3) in the displacement sensing system are capacitive displacement sensors.

6. A method for controlling an anti-crosstalk multi-axis nanoscale displacement stage as described in any one of claims 1-5, 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 collaboratively control the output of the piezoelectric ceramic actuators (6-1, 6-2, 6-3, 6-4) based on the deviation between the calculated translation and yaw angles and the target values. When the stage (1) is controlled to translate in the Z direction, the same driving signal is applied to the four sets of actuators, so that the guide rod pushes the stage (1) synchronously. At this time, the cooperation between the guide hole of the limiting flexible hinge and the guide rod suppresses the parasitic yaw around the X-axis and Y-axis. When the stage (1) is controlled to yaw around the X-axis or Y-axis, a different driving signal is applied to at least one set of actuators, so that the limiting flexible hinge (3-1, 3-2, 3-3, 3-4) produces a coordinated, non-uniform elastic deformation, thereby driving the stage (1) to deflect, while suppressing the parasitic translation in the Z direction.

7. The method for controlling the anti-crosstalk multi-axis nanoscale displacement stage according to claim 6, characterized in that, The closed-loop control algorithm is a PID control algorithm. The Z-axis displacement closed-loop control resolution achieved by 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.

8. The method for controlling the anti-crosstalk multi-axis nanoscale displacement stage according to claim 6, characterized in that, When performing yaw control around the X-axis, a first driving voltage is applied to two sets of actuators (6-1, 6-4) located on the same side of the X-axis, and a second driving voltage different from the first driving voltage is applied to two sets of actuators (6-2, 6-3) located on the other side of the X-axis.

9. The application of an anti-crosstalk multi-axis nanoscale displacement stage as described in any one of claims 1-5 in precision collimation and focusing of optical systems, semiconductor wafer inspection, atomic force microscopes, or quantum bit manipulation systems.

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