Chip-Scale Optomechanical Gravimeter Using Thin-Film Membranes
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Solution Overview
Problem
Current gravimeters face challenges in portability and environmental deployment due to the need for significant environmental isolation and high power consumption, while achieving high sensitivity and precision in measuring gravitational forces.
Innovation Solution
A chip-scale high-performance gravimeter utilizing cavity optomechanics with photonic crystal-based slot-cavities and coherent laser sources for low noise levels, enabling compact and array-scalable optical readout with sensitivity up to 5×10−17 m/Hz1/2, suitable for detecting small changes in gravitational fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If laser interferometers are used for precision metrology, then measurement precision is improved, but environmental isolation requirements increase
Solution Approach 1:
The patent replaces traditional mechanical spring-based gravimeters with an optomechanical system using a suspended mirror and laser interferometry. This substitution enables higher measurement precision (1-10 μGal accuracy) while reducing the need for complex mechanical isolation structures, as the optical system can be contained in a more compact enclosure.
Solution Approach 2:
The patent employs temperature stabilization and vibration isolation techniques that actively control environmental parameters. By monitoring and adjusting temperature and vibration levels, the system maintains measurement precision without requiring complete environmental isolation, thus reducing the complexity of the isolation structure.
2Measurement precision
If superconducting gravimeters are used, then measurement precision and stability are improved, but power consumption increases
Solution Approach 1:
The patent uses conventional materials (aluminum or silicon nitride membranes, standard superconductors) instead of requiring expensive, complex cryogenic infrastructure. The system achieves superconducting functionality at more accessible temperature ranges, reducing the power consumption associated with extreme cryogenic cooling while maintaining measurement precision.
Solution Approach 2:
The patent operates the superconducting gravimeter at elevated temperatures compared to traditional 4.2K systems, using materials that maintain superconducting properties at higher temperatures. This parameter change significantly reduces the power consumption of the cooling system while preserving the low noise and high stability characteristics of superconducting measurements.
3Device complexity
If bulk spring-type gravimeters are used, then device complexity is reduced, but measurement precision decreases
Solution Approach 1:
The patent transitions from bulk three-dimensional spring structures to two-dimensional thin-film membrane structures. This dimensional reduction enables simpler fabrication using standard semiconductor techniques while achieving higher measurement precision through reduced mass and improved optical access. The thin-film suspended mirror structure maintains mechanical simplicity while enhancing measurement capability.
Solution Approach 2:
The patent employs thin-film membranes (aluminum or silicon nitride) as the gravimetric sensing element. These thin films provide sufficient mechanical support while minimizing mass, thereby improving sensitivity to gravitational forces. The flexible thin-film structure can be fabricated using standard thin-film deposition techniques, maintaining device simplicity while achieving high measurement precision.
4Weight of moving object
If chip-scale gravimeters are used, then portability is improved, but measurement precision decreases
Solution Approach 1:
The patent scales down from bulk three-dimensional structures to two-dimensional thin-film chip-scale structures. This dimensional reduction dramatically decreases the mass and size of the gravimeter, enabling portability. The thin-film suspended mirror structure maintains the optomechanical coupling necessary for high-precision measurements even at chip scale, thus preserving measurement accuracy while achieving compact form factor.
Solution Approach 2:
The patent replaces bulk mechanical structures with optomechanical systems using thin-film membranes and laser interferometry. This substitution enables precise gravitational measurements in a compact chip-scale format, as the optical detection system can achieve high sensitivity with minimal mass. The suspended mirror structure provides the necessary mechanical freedom for gravitational sensing while maintaining a small footprint suitable for portable applications.
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 provides a portable and sensitive gravimeter capable of measuring small changes in gravitational fields with 10 μGal/Hz1/2 noise levels, suitable for various applications including oil exploration, geophysics research, and national security, while reducing power consumption and environmental isolation requirements.
Implementation Method 1
A chip-scale high-performance gravimeter utilizing cavity optomechanics with photonic crystal-based slot-cavities and coherent laser sources
Implementation Method 2
at least one optomechanical oscillator where the at least one optomechanical oscillator is structured to deform under the gravitational force
Implementation Method 3
photonic crystal-based slot-cavities
Implementation Method 4
at least one photonic crystal having at least one cavity coupling optical and mechanical degrees of freedom of the oscillator
Implementation Method 5
coherent laser sources for low noise levels
Data Source
AI summary
An method and apparatus for measuring gravitational force are described where at least one first radiation can be provided to at least one optomechanical oscillator, the at least one optomechanical oscillator being structured to deform under the gravitational force to cause a shift in resonance associated with the at least one optomechanical oscillator. In addition, at least one second radiation is received from the at least one optomechanical oscillator, wherein the at least one second radiation is associated with the shift in the resonance, and the shift in the resonance can be determined based on the first and second radiations.