Leaf-spring Optical Seismometer for Low-noise Seismic Detection
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Solution Overview
Problem
Conventional seismometers face challenges in harsh environments such as high-temperature boreholes and are limited by electronic noise and susceptibility to damage from lightning, which affects signal quality and longevity.
Innovation Solution
The development of an optical seismometer that uses an interferometric system with optical fibers to measure seismic data without electronic components, allowing for operation in harsh environments and eliminating noise from electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional electronic components are used in seismometers, then signal processing capability is improved, but electronic noise and susceptibility to lightning damage increase
Solution Approach 1:
The patent replaces electronic sensing components with a mechanical-optical sensing system. A mass suspended by a spring mechanically responds to seismic vibrations, and this mechanical displacement is optically measured using an interferometer with retroreflectors and laser light, eliminating electronic components from the sensing mechanism and thus removing electronic noise and lightning susceptibility.
Solution Approach 2:
The patent introduces optical fields as an intermediary between the mechanical seismic motion and the measurement system. The interferometer uses laser light to optically couple the mechanical displacement of the mass to the measurement detectors, serving as a noise-free mediator that transfers information without the harmful effects of electronic components.
2Measurement precision
If optical interferometer system is implemented, then measurement resolution and dynamic range are improved, but device complexity increases
Solution Approach 1:
The patent divides the optical measurement function into separate modular components: a laser light source, beam splitter, retroreflectors attached to the mass and frame, and photodetectors. This segmentation allows each component to be optimized independently and simplifies alignment and maintenance while achieving high measurement precision through the combined interferometric system.
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 optical seismometer achieves high resolution and wide dynamic range, capable of resolving seismic signals with low noise levels and operating effectively in extreme conditions without the need for force feedback or electronic components, comparable to observatory-grade instruments.
Implementation Method 1
an optical interferometer... to produce an optical interference signal indicating a motion of the mass
Implementation Method 2
a first retroreflector attached to the mass to reflect the first beam back to the beam splitter, and a second retroreflector attached to the frame to reflect the second beam back to the beam splitter
Data Source
AI summary
Methods, structures, devices and systems are disclosed for implementing optical seismometers that detect seismic information based on optical interferometry. In one aspect, a device includes a first retroreflector attached to a mass of a seismometer, a second retroreflector attached to a member of a frame of the seismometer, the frame structured to suspend the mass, and optical components attached to the member of the frame and configured with the first and second retroreflectors to form an interferometer, in which a change in position of the mass is identified by detecting by a change in an optical path of a light beam generated by a light energy source transmitted to the interferometer.