Optical Sensor Mount Thermal Stability via Magnetic Constraints
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Solution Overview
Problem
Existing optical sensor mounts face challenges in maintaining thermal stability and preventing distortions due to differential thermal expansion between components with varying coefficients of thermal expansion, often resulting in unpredictable behavior and deviations from ideal performance due to friction at interfaces.
Innovation Solution
The solution involves a mechanical reference frame with constraints that have different stiffnesses, allowing a designated point to remain stationary during thermal expansion by controlling the location and stiffness of the thermal center, which is achieved by manipulating the stiffness of constraints composed of compliant members and adjusting their geometry to accommodate thermal changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If sliding contacts are used to accommodate relative dimensional changes between bodies, then thermal expansion is accommodated, but friction causes unpredictable behavior and deviations from ideal performance
Solution Approach 1:
The patent replaces sliding mechanical contacts with a magnetic field-based constraint system. The magnetic constraints provide the necessary force to accommodate thermal expansion without physical sliding contact, thereby eliminating friction and achieving predictable, reliable behavior while maintaining adaptability to thermal changes.
Solution Approach 2:
The patent changes the physical state of the constraint mechanism from mechanical sliding to magnetic field interaction. By using magnetic fields instead of sliding contacts, the system achieves frictionless operation while maintaining the ability to accommodate dimensional changes due to thermal expansion.
2Adaptability or versatility
If friction is eliminated in sliding direction to achieve ideal performance, then thermal expansion accommodation is optimized, but stiffness becomes essentially zero for larger motions
Solution Approach 1:
The patent replaces the sliding mechanical system with a magnetic constraint system that provides continuous, frictionless forces. The magnetic field generates restoring forces proportional to displacement, providing both the compliance needed for thermal expansion accommodation and the stiffness required for larger motions, eliminating the trade-off present in sliding contact systems.
3Manufacturing precision
If compliant elements are used to provide high-stiffness in constraint direction, then positioning precision is improved, but compliance in remaining directions is reduced
Solution Approach 1:
The patent replaces mechanical compliant elements with a magnetic field-based constraint system. The magnetic field provides anisotropic stiffness characteristics, offering high stiffness in the constraint direction for positioning precision while maintaining appropriate compliance in other directions through field configuration, without the mechanical coupling limitations of physical compliant elements.
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 effectively maintains thermal stability and prevents distortions by ensuring the thermal center remains stationary, even in the presence of thermal expansion, thereby enhancing the precision and reliability of optical sensor mounts, particularly in lithography tools and other precision instruments.
Implementation Method 1
during thermal expansion of the rigid object over a range of temperatures
Data Source
Figure 1
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Figure 4A~4B
AI summary
Disclosed is an apparatus including a mechanical reference frame and a rigid object mechanically coupled to the reference frame by two or more constraints. The stiffnesses of at least two of the constraints are different from one another, and the relative locations and stiffnesses of the constraints cause a designated point on the rigid object to remain stationary with respect to the reference frame during thermal expansion of the rigid object over a range of temperatures.