MEMS Gyroscope Laser Vibrometer Stray Reflection Control
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Solution Overview
Problem
Existing micro-scale gyroscopes face challenges with stability, form factor, and performance due to parasitic capacitance, noise, and stray reflections, making them unsuitable for applications requiring low cost, small size, and high precision.
Innovation Solution
A micro-scale gyroscope integrating a dielectric resonator with on-chip laser vibrometers and a laser beam power dump to eliminate stray reflections, utilizing precise lithography for alignment and miniaturization, achieving navigation-grade performance with reduced bias drift and compact volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrical amplifiers are used to detect gyroscope motion, then current signals can be amplified, but parasitic capacitance and amplifier noise significantly degrade measurement precision
Solution Approach 1:
The patent replaces electrical amplification and detection systems with an optical detection system. A laser vibrometer measures the motion of the dielectric resonator directly through optical means, eliminating the need for electrical amplifiers and associated parasitic capacitance. This substitution of electrical systems with optical systems resolves the measurement precision problem by removing the primary sources of electrical noise and capacitance interference.
Solution Approach 2:
The patent introduces an optical intermediary (laser vibrometer) between the moving dielectric resonator and the detection system. Instead of directly measuring electrical currents from the resonator motion, the system uses laser light to detect motion through Doppler shift or phase modulation, serving as an intermediary that converts mechanical motion into optical signals that can be measured without electrical parasitics.
2Measurement precision
If table-top laser vibrometers are used for testing, then optical measurement precision is achieved, but the device volume becomes too large for portable applications
Solution Approach 1:
The patent merges multiple previously separate components into a single integrated chip-scale device. The dielectric resonator, laser vibrometer, and laser dump are combined on a single substrate, creating a compact integrated system. This merging allows the gyroscope to achieve navigation-grade performance in a miniaturized form factor suitable for portable applications, resolving the volume contradiction.
Solution Approach 2:
The patent employs a nested structure where the laser vibrometer and laser dump are positioned on opposite sides of the dielectric resonator in a compact arrangement. The components are nested within a small vertical space, with the resonator suspended between the two optical components. This nesting approach maximizes space utilization and enables miniaturization while maintaining the functional separation needed for precise optical measurement.
3Ease of operation
If conventional laser vibrometer configurations are used, then measurement capability is achieved, but stray reflections degrade performance
Solution Approach 1:
The patent extracts and removes stray reflections from the optical path by positioning a dedicated laser dump component. The laser dump is specifically designed to absorb or redirect stray light that would otherwise reflect off the dielectric resonator or other components and interfere with the measurement. This extraction of harmful stray reflections from the system resolves the performance degradation issue while maintaining measurement capability.
Solution Approach 2:
The patent converts the potentially harmful stray reflections into a controlled element by using the laser dump to deliberately absorb them. Instead of trying to prevent stray reflections from occurring, the system anticipates their presence and provides a designated absorption path, turning a harmful unavoidable phenomenon into a manageable aspect of the optical design. This approach maintains measurement capability while eliminating performance degradation from stray light.
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 stable, compact gyroscope with navigation-grade performance and reduced bias drift, effectively addressing the limitations of existing technologies by eliminating stray reflections and optimizing alignment and integration of components.
Implementation Method 1
The principle of operation of a laser Doppler vibrometer, as described by G. A. Massey in 'An Optical Heterodyne Ultrasonic Image Converter'
Implementation Method 2
a laser dump for redirecting or absorbing light received at the laser dump from the laser vibrometer
Data Source
AI summary
A gyroscope including a dielectric resonator, a laser vibrometer on a first side of the dielectric resonator, and a laser dump for redirecting or absorbing light received at the laser dump from the laser vibrometer, the laser dump on a second side of the dielectric resonator. A first distance between the dielectric resonator and the laser vibrometer ranges from 10 nm to 20 μm, and a second distance between the dielectric resonator and the laser dump ranges from 10 nm to 20 μm.