Optical Ferrule Fiber Layout for Precise Interferometric Fluid-Flow Sensing
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Solution Overview
Problem
Optical sensors face challenges such as low signal-to-noise ratio, ghost reflections, and measurement accuracy due to stray light folding, which affect the precision of optical axis finding and interference pattern scaling in optical interferometers.
Innovation Solution
The design of a ferrule layout with multiple smaller optical fibers arranged to avoid central symmetry, positioning them to direct unwanted reflections away from active measurement areas, thereby preventing biased measurements from ghost reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple optical channels are used to obtain directional measurement information, then measurement completeness is improved, but laser power and detection SNR are reduced
Solution Approach 1:
The patent divides the optical detection system into multiple independent optical channels (at least four channels equidistantly populated around the boundary), each capable of detecting interference patterns separately. This segmentation allows the system to obtain directional measurement information from multiple angles while maintaining adequate signal strength in each individual channel, thus balancing measurement completeness with detection SNR.
2Volume of moving object
If optical components are closely packed to reduce system size, then device compactness is improved, but ghost reflections and stray light increase
Solution Approach 1:
The patent positions the optical components asymmetrically within the ferrule, specifically placing at least four optical channels equidistantly around the boundary in a non-symmetric arrangement. This asymmetric positioning disrupts the geometric conditions required for ghost reflections and stray light to form coherent interference patterns, thereby reducing harmful reflections while maintaining a compact system volume.
Solution Approach 2:
The patent converts the potentially harmful effect of multiple optical surfaces into a beneficial feature by strategically positioning the optical channels around the boundary. The multiple reflections that would normally create ghost images are instead distributed across different angular positions, allowing the system to use the reflections for enhanced directional measurement while minimizing their harmful interference through proper geometric arrangement.
3Measurement precision
If optical fibers are positioned to maximize channel coverage, then measurement accuracy is improved, but susceptibility to ghost reflections increases
Solution Approach 1:
The patent transitions from a single-dimensional linear arrangement of optical channels to a two-dimensional circular arrangement around the boundary of the ferrule. By positioning at least four optical channels equidistantly around the perimeter in different angular positions, the system achieves comprehensive spatial coverage for accurate directional measurements while the circular geometry naturally distributes and dilutes ghost reflection effects across multiple dimensions, reducing their impact on measurement accuracy.
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 reduces systematic errors and enhances measurement precision by eliminating the impact of ghost reflections on optical center finding and phase measurement in optical interferometers.
Implementation Method 1
The LiDAR system can use an optical interferometer configured to form and project an optical interference pattern on an optical detector. The interference pattern can be used to derive the one or more state variables of the vehicle.
Implementation Method 2
Another optical sensing technique focuses on measurements of flight control parameters or air data, and are intended to replace or complement a traditional pitot-static system, where pitot probes may malfunction due to icing conditions, physical blockage, or even damage. In contrast, this optical sensing technique measures air data optically using a scattered light, which wavelength changes as a result of Doppler shift, and the difference between the scattered light and a reference light is detected by interferometry.
Data Source
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AI summary
A method comprises identifying an optical axis with central symmetry in a central channel of a ferrule for an optical system; aligning outer surfaces of an etalon such that a normal of the surfaces are parallel; selecting a sensitivity axis in the central channel; selecting a boundary for the central channel that encompasses at least two fringes during operation of the optical system; defining a minimal radius of a fiber to fit N channels, which are equidistantly populated around the boundary such that N is at least four; selecting fibers in which each fiber substantially has the minimal radius to fit N channels; placing half of the fibers in the central channel such that there are gaps between the fibers; and rotating the fibers around the optical axis such that one fiber is next to the sensitivity axis, or one fiber has a center that intersects the sensitivity axis.