Transparent Piezo Actuator with Integrated Optical Sensor
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Solution Overview
Problem
Conventional piezo actuators in lithographic apparatuses face inaccuracies due to hysteresis and require separate position sensors, leading to complex systems and positioning errors from resonance modes.
Innovation Solution
An actuator system comprising a transparent piezo electric material and an integrated optical position sensor that transmits an optical beam through the piezo actuator to directly measure the actuator contact surface, allowing for accurate and compact positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate position sensor is added for each actuator, then position measurement capability is improved, but device complexity increases
Solution Approach 1:
The patent merges the position sensor and actuator into a single integrated device. The sensor is positioned within the actuator structure itself, allowing position measurement without requiring separate external sensors. This integration directly reduces device complexity while maintaining measurement capability.
2Ease of operation
If the position sensor measures position at a different part of the object than where the actuator exerts force, then measurement is simplified, but positioning accuracy deteriorates due to resonance modes and deformations
Solution Approach 1:
The patent uses the transparent piezoelectric material itself as an intermediary medium. The optical beam passes through this material to reach the measurement point at the actuator contact surface. This intermediary approach allows the sensor to measure position exactly where the actuator applies force, eliminating errors from structural deformations while keeping the measurement system integrated and simple.
3Speed
If conventional piezo electric material is used, then actuator performance is improved with high resolution and fast response, but measurement accuracy deteriorates due to hysteresis effects
Solution Approach 1:
The patent implements self-service by using the actuator's own transparent piezoelectric material as the measurement medium. The optical beam passes through this material to directly measure the contact surface position, allowing the system to self-monitor its own deformation without external sensors. This eliminates hysteresis errors in measurement while preserving the fast response characteristics of the piezoelectric material.
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 configuration provides accurate and compact positioning with reduced hysteresis, enabling precise object placement and minimizing system complexity by integrating the sensor with the actuator.
Implementation Method 1
A piezo actuator relies on a piezo electric effect, whereby an electrical voltage applied to the piezo electric material of the piezo actuator provides for a deformation of the piezo electric material.
Implementation Method 2
the optical position sensor is configured to transmit an optical beam through the transparent piezo electric material to the actuator contact surface
Data Source
AI summary
An actuator system configured to position an object, the actuator system includes a piezo actuator having an actuator contact surface. The piezo actuator is configured to exert a force via the actuator contact surface onto the object. The piezo actuator includes a transparent piezo material. The actuator system further has an optical position sensor configured to measure a position of the actuator contact surface. The optical position sensor is configured to transmit an optical beam through the transparent piezo material to the actuator contact surface. The optical position sensor may form an interferometer.