Optical Element Holding Apparatus for Vibration Control
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Solution Overview
Problem
Conventional exposure apparatuses face issues with positional accuracy due to low-frequency vibration disturbances and heat generation from actuators supporting mirror gravity, and require complex systems with numerous sensors for local mirror surface corrections.
Innovation Solution
An optical element holding apparatus featuring force generating actuators for deformation, displacement causing actuators for precise positioning, and measuring devices to adjust the optical element's position, utilizing piezoelectric elements or parallel link mechanisms for high rigidity and robustness, and non-contact force actuators to absorb high-frequency vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If force actuators with lower rigidity are used to deform the mirror and correct position, then the mirror can be deformed and positioned, but large positional deviation occurs under low-frequency vibration disturbances
Solution Approach 1:
The actuator system is segmented into two distinct types: force generating actuators for deformation and displacement causing actuators for positioning. This segmentation allows each actuator type to be optimized for its specific function, with displacement causing actuators having higher rigidity to maintain positional accuracy under vibration disturbances.
Solution Approach 2:
The patent changes the rigidity parameter of the actuators by selecting displacement causing actuators with higher rigidity for positioning functions. This parameter change enables the system to maintain positional accuracy while still achieving the required deformation capabilities through the coordinated action of both actuator types.
2Reliability
If force actuators are used to support the gravity of the mirror, then the mirror can be held in position, but great amount of heat is generated in the actuators
Solution Approach 1:
The patent replaces traditional mechanical force actuators with piezoelectric actuators for supporting mirror gravity. This substitution eliminates the heat generation problem associated with conventional force actuators while maintaining the ability to hold the mirror in position through precise piezoelectric actuation.
Solution Approach 2:
The patent changes the material and operating parameters of the actuators by using piezoelectric materials that can support mirror gravity without generating significant heat. This parameter change in the actuator material properties resolves the heat generation issue while maintaining position holding capability.
3Manufacturing precision
If numerous position sensors and actuators are used to correct local mirror surface imperfections, then local deformations can be corrected, but the system arrangement becomes complicated and cost increases
Solution Approach 1:
The patent makes the displacement causing actuators multi-functional by enabling them to perform both rigid-body positioning and local surface deformation correction. This universality eliminates the need for separate local position control loops with dedicated sensors and actuators, thereby reducing system complexity while maintaining local correction capability.
Solution Approach 2:
The patent merges the functions of rigid-body positioning and local surface correction into a single integrated control system using the displacement causing actuators. This combining of functions reduces the number of separate components needed, simplifying the system arrangement and reducing cost.
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
The solution enables accurate deformation and positioning of optical elements with reduced positional deviations and simplified, cost-effective systems, capable of handling lower-frequency vibrations and high-frequency disturbances, while minimizing heat generation and system complexity.
Implementation Method 1
utilizing piezoelectric elements or parallel link mechanisms for high rigidity and robustness
Implementation Method 2
non-contact force actuators to absorb high-frequency vibrations
Data Source
AI summary
At least one exemplary embodiment is directed to an optical element holding apparatus including a force generating actuator configured to deform the optical element, a measuring device configured to measure a position of the optical element, and a displacement causing actuator configured to position the optical element based on the measured position.