Optical Element Assembly With Magnetic Weight Compensation
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Solution Overview
Problem
Existing microlithographic projection exposure apparatuses face challenges with high parasitic moments and forces transmitted to mirrors due to the coupling of Lorentz actuators and weight compensating devices, leading to optical system deformations and performance impairments, especially with increasing demands on resolution and contrast.
Innovation Solution
An assembly in the microlithographic projection exposure apparatus that includes a weight compensating device with a passive magnetic circuit and an active component, coupled to the optical element via a pin, and Lorentz actuators fixed directly to the optical element, reducing parasitic forces and moments by using an 'active' configuration to transmit forces directly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If Lorentz actuators and weight compensating device are coupled to manipulate optical elements, then the optical element can be positioned and stabilized, but high parasitic moments and forces are transmitted to the mirror causing deformations
Solution Approach 1:
The patent introduces an intermediary elastic element (flexure) between the weight compensating device and the optical element. This flexure acts as a mediator that transmits only the necessary compensating forces while blocking the transmission of parasitic moments and forces from the Lorentz actuators to the mirror, thus protecting the optical element from harmful mechanical stresses while still allowing for position and orientation control
2Force
If mechanical connections are used to couple actuators to optical elements, then force transmission is achieved, but deformations of the optical element occur
Solution Approach 1:
The patent replaces rigid mechanical connections with an elastic flexure system. This substitution allows force transmission through the flexure while its elastic properties enable it to accommodate misalignments and block parasitic moments, preventing the transmission of forces that would cause deformations to the optical element while maintaining the necessary mechanical coupling
3Use of energy by moving object
If weight compensating device is designed with active component, then energy consumption is reduced, but device complexity increases
Solution Approach 1:
The patent implements a weight compensating device that uses magnetic fields to generate forces counteracting the gravitational force on the optical element. By balancing the weight magnetically, the system reduces or eliminates the need for continuous active energy input to maintain position, thereby reducing energy consumption while the device structure remains relatively simple
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 significantly reduces parasitic forces and moments transmitted to the optical element, minimizing deformations and enhancing the optical system's performance by allowing precise force transmission and reducing the need for mechanical connections that cause deformations.
Implementation Method 1
a passive magnetic circuit for generating a magnetic field, which causes a force for at least partial compensation of the weight acting on the optical element
Implementation Method 2
a passive magnetic circuit for generating a magnetic field, which causes a force for at least partial compensation of the weight acting on the optical element
Implementation Method 3
an active component for generating an actively controllable force transmitted to the optical element
Implementation Method 4
at least three Lorentz actuators each designed for exerting a controllable force on the optical element
Data Source
AI summary
An assembly, such as in a microlithographic projection exposure apparatus having: an optical element; and at least one weight compensating device with a passive magnetic circuit for generating a magnetic field, which causes a force for at least partial compensation of the weight acting on the optical element, and an active component for generating an actively controllable force transmitted to the optical element. The at least one weight compensating device is coupled to the optical element via a pin mounted in an articulated manner, and at least three Lorentz actuators each designed for exerting a controllable force on the optical element, wherein at least one of these Lorentz actuators is fixed directly to the optical element.