Quartz Resonator Assembly Using Selective Laser Etching
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Solution Overview
Problem
Conventional quartz resonators and vibrating beam accelerometers face accuracy and precision issues due to thermally induced strains caused by differential coefficients of thermal expansion between materials used in their components, and wet-etching processes result in asperities and stress risers that reduce the quality factor and survivability of the resonators.
Innovation Solution
Selective laser etching is used to form quartz resonators and vibrating beam accelerometers from a single crystalline quartz substrate, eliminating asperities and stress risers, and allowing for components with matched coefficients of thermal expansion, thereby improving motion sensing accuracy and robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wet-etching process is used to form quartz resonators, then manufacturing simplicity is maintained, but asperities and stress risers are created that reduce quality factor and survivability
Solution Approach 1:
The patent replaces the chemical wet-etching process with a laser-based processing method. The laser selectively removes material through ablation rather than chemical dissolution, eliminating the formation of asperities and stress risers that occur with wet-etching. This substitution of mechanical/photonic processing for chemical processing resolves the contradiction by maintaining manufacturing capability while dramatically improving resonator quality and survivability.
Solution Approach 2:
The patent changes the fundamental processing parameter from chemical etching to laser ablation. By using controlled laser energy input and selective scanning patterns, the process achieves clean material removal without the mechanical or chemical damage that reduces quality factor. This parameter change enables both ease of manufacture and high reliability simultaneously.
2Adaptability or versatility
If multiple materials are used in resonator components, then functional requirements are met, but differential thermal expansion causes thermally induced strains that reduce accuracy
Solution Approach 1:
The patent applies homogeneity by forming all resonator components from a single monolithic quartz substrate. The laser processing method enables direct fabrication of complex three-dimensional structures including resonators, proof mass, and support elements from the same material without requiring material joints or interfaces. This eliminates differential thermal expansion effects entirely, resolving the contradiction between functional versatility and measurement precision.
Solution Approach 2:
The patent uses a composite approach in reverse - instead of combining multiple materials, it uses a single homogeneous material (quartz) for all components. The laser processing enables this single-material construction to achieve the functional requirements that would traditionally require multiple materials, thereby eliminating thermal expansion mismatches while maintaining all necessary functions.
3Manufacturing precision
If laser etching is used to form resonators, then manufacturing precision and quality factor are improved, but process complexity increases
Solution Approach 1:
The laser processing system performs multiple functions within a single integrated process: it defines resonator geometry, creates proof mass structures, forms support elements, and establishes precise boundary conditions all in one step. This multi-functionality resolves the contradiction by achieving high manufacturing precision without proportionally increasing process complexity, as the same laser system accomplishes what would traditionally require multiple specialized manufacturing steps.
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 selective laser etching process enhances the accuracy and stability of the resonators by maintaining symmetric boundary conditions, improving coupling between tines, and increasing the quality factor, while reducing the risk of frequency instability and enhancing survivability under dynamic loading.
Implementation Method 1
selective laser etching is used to form quartz resonators and vibrating beam accelerometers from a single crystalline quartz substrate, eliminating asperities and stress risers
Data Source
Figure 1A~1B
Figure 2~3
Figure 4
AI summary
An example proof mass assembly includes a proof mass; a proof mass support; a flexure connecting the proof mass to the proof mass support, wherein the proof mass is configured to rotate relative to the proof mass support via the flexure; a first resonator connected to a first major surface of the proof mass and a first maj or surface of the proof mass support; and a second resonator connected to a second major surface of the proof mass and a second major surface of the proof mass support, wherein at least one of the proof mass, the proof mass support, the flexure, the first resonator, or the second resonator is formed by selective laser etching.