Optical Element Alignment with Gravity-Compensated Shaft Actuation
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Solution Overview
Problem
Existing actuator devices for aligning optical elements in projection exposure apparatuses face limitations in efficiency and dynamics due to restricted deflection forces, heat dissipation issues, and the need for high precision, which are exacerbated by the restoring forces caused by gravity and joint stiffness.
Innovation Solution
An actuator device with a shaft suspended by a joint at one end and fixed to an optical element at the other, utilizing an actuator unit and a compensation device that applies a deflection force and a compensation force respectively, where the compensation force increases with deflection to counteract restoring forces, potentially using a magnet or spring arrangement to achieve negative stiffness and reduce energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the deflection force of the actuator is increased to overcome joint stiffness and gravity, then the alignment capability is improved, but the dynamics and response speed deteriorate
Solution Approach 1:
The patent applies a compensation force that counteracts the restoring force caused by gravity and joint stiffness. This compensation force is generated by a magnetic field that creates an opposing force to balance the weight of the optical element, allowing the actuator to operate with reduced force requirements and improved dynamics.
2Manufacturing precision
If the actuator works against joint stiffness and gravity to maintain alignment, then positioning accuracy is improved, but energy consumption increases due to constant energy flow
Solution Approach 1:
The compensation force counterbalances the gravitational restoring force, eliminating the need for continuous energy input to maintain position. The magnetic field generates a force that offsets the weight-induced restoring force, allowing static alignment to be maintained without constant energy consumption.
Solution Approach 2:
The actuator operates in a periodic manner, applying deflection forces only when alignment changes are needed, rather than continuously working against gravity. The compensation force handles the static load, enabling the actuator to enter low-power states during stable alignment.
3Force
If the maximum deflection force is increased to improve alignment capability, then positioning range is improved, but heat generation increases due to difficult thermal dissipation
Solution Approach 1:
By introducing a compensation force that counteracts gravity, the required deflection force from the actuator is reduced. This lower force requirement directly reduces the power consumption and heat generation of the actuator, addressing the thermal dissipation problem while maintaining adequate positioning capability.
4Length of moving object
If the actuator stroke is increased to improve alignment range, then positioning range is improved, but dynamics deteriorate due to rapid control requirements
Solution Approach 1:
The compensation force handles the static gravitational load, allowing the actuator to focus on dynamic adjustments. This separation of static and dynamic functions enables the actuator to achieve both adequate stroke range and rapid response, as it doesn't need to overcome gravity during dynamic movements.
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 enhances the dynamics and efficiency of the actuator device, reduces the required deflection force, and minimizes heat output, allowing for improved alignment and positioning of optical elements with reduced energy consumption and increased compactness.
Implementation Method 1
a linearly movable actuation unit, a translator, in the form of a magnet being able to be moved by electromagnetic interaction with a coil which is statically mounted on a stator
Implementation Method 2
a restoring force acting on the shaft in the direction of the middle position caused by the weight of the optical element
Data Source
AI summary
An actuator device aligns an optical element of a projection exposure apparatus. The actuator device includes a shaft. The first end portion of the shaft is deflectably suspended from a base point of a supporting structure by way of a joint. The second end portion of the shaft is fixed on the optical element. At least one actuator unit has a translator fixed on the shaft and a stator mechanically connected to the supporting structure to apply a deflection force to the shaft to radially deflect the shaft from a middle position. A compensation device is set up to apply to the shaft, independently of the deflection force, a compensation force which increases in accordance with the deflection of the shaft from the middle position and which counteracts a restoring force acting on the shaft in the direction of the middle position caused by the weight of the optical element