Piezoelectric Sample Positioning Without Sensors
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Solution Overview
Problem
High-resolution charged particle beam microscopes face challenges in achieving accurate positional displacement of samples due to creep phenomena in piezoelectric elements, which can be exacerbated by temperature changes and the difficulty in arranging position detection elements near the sample.
Innovation Solution
A method involving a series of controlled movements using a piezoelectric element, including an initial movement towards a target position, a movement away from the target, and a subsequent return to the target position, to reduce creep displacement without the need for additional sensors, thereby maintaining positional accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If feedback control using a position detection element is implemented, then positional accuracy is improved, but structural complexity increases and temperature-induced drift occurs
Solution Approach 1:
The invention extracts and eliminates the position detection element from the system. By using a control method that does not require sensors, the patent removes the source of temperature-induced drift and structural complexity while maintaining positional accuracy through iterative piezoelectric element control
Solution Approach 2:
The system uses the piezoelectric element itself to achieve positioning without external detection elements. The piezoelectric element serves both as the actuator and the reference for control, eliminating the need for separate position detection mechanisms
2Measurement precision
If a position detection element is arranged near the sample using an additional mechanism, then measurement capability is improved, but temperature expansion and contraction cause position drift
Solution Approach 1:
The invention removes the position detection element from the system entirely. By eliminating the additional mechanism and its associated temperature sensitivity, the patent achieves position stability while maintaining measurement capability through sensorless control of the piezoelectric element
Solution Approach 2:
The control device acts as an intermediary that compensates for piezoelectric element characteristics without requiring physical proximity to the sample. Through computational control strategies, the system achieves accurate positioning without temperature-sensitive mechanical structures
3Measurement precision
If overvoltage is applied to suppress creep phenomenon, then positional accuracy is improved, but the piezoelectric element cannot be deformed to near maximum/minimum voltages
Solution Approach 1:
The invention applies periodic voltage adjustments to the piezoelectric element, including reverse polarity applications, to suppress creep phenomenon. This periodic control strategy enables full voltage range utilization while maintaining positional accuracy through dynamic compensation
Solution Approach 2:
The control device dynamically changes voltage parameters including polarity and magnitude to suppress creep and achieve accurate positioning. By varying voltage characteristics rather than applying constant overvoltage, the system maintains both accuracy and full adaptability across the voltage range
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for high-accuracy sample positioning by minimizing creep displacement and avoiding positional drift caused by sensor deformation, even when the piezoelectric element is deformed to near maximum/minimum voltages.
Implementation Method 1
a piezoelectric element that is connected to the sample holder and moves the sample
Data Source
AI summary
A scanning/transmission electron microscope 1 moves a sample 59 using an X-piezoelectric element 54, a Y-piezoelectric element 55, and a Z-piezoelectric element 65. A method for controlling the position of the sample 59 includes a first movement step of moving the sample 59 toward a target position, a second movement step of moving the sample 59 away from the target position, after the first movement step, and a third movement step of moving the sample 59 toward the target position, after the second movement step.