Time-Multiplexed Lidar Air-Data Optical Channels
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Solution Overview
Problem
Lidar sensors used in aircraft for air data measurement face systematic bias due to imperfections in the production of ferrules and differences in optical path lengths, leading to inaccurate environmental parameter readings.
Innovation Solution
The implementation of a system that utilizes time multiplexing of optical channels, where a switch configures the output of reference and backscattered signals to a common optical path, allowing for the determination and compensation of systematic bias.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple optical fibers are used in parallel to transport reference and backscattered signals, then signal transmission capability is improved, but systematic bias increases due to manufacturing imperfections and optical path length differences
Solution Approach 1:
The patent combines multiple optical channels into a single common optical path by time-multiplexing reference and backscattered signals through the same optical fiber, eliminating systematic bias caused by manufacturing imperfections and optical path length differences between separate fibers
Solution Approach 2:
The patent uses periodic switching to alternately transmit reference signals and backscattered signals through the same optical channel, enabling the system to maintain signal transmission capability while compensating for systematic bias through temporal separation of signal types
2Loss of information
If separate optical paths are used for reference and backscattered signals, then signal isolation is improved, but systematic bias cannot be compensated
Solution Approach 1:
The patent merges separate optical paths for reference and backscattered signals into a single common optical path, enabling both signals to experience identical manufacturing imperfections and optical path length conditions, thus allowing systematic bias compensation
Solution Approach 2:
The patent implements periodic switching to alternate between transmitting reference signals and backscattered signals through the same optical channel, maintaining effective signal isolation through temporal separation while enabling systematic bias compensation through spatial merging
3Ease of manufacture
If ferrule production imperfections are present, then manufacturing ease is improved, but optical path length differences cause systematic bias
Solution Approach 1:
The patent combines multiple optical channels into a single common optical path, making the system insensitive to ferrule production imperfections and optical path length differences that would otherwise cause systematic bias
Solution Approach 2:
The patent changes the system from using multiple simultaneous optical paths to a single time-multiplexed optical path, transforming the parameter of optical path configuration to eliminate sensitivity to manufacturing tolerances
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 improves the accuracy and reliability of air data sensor measurements by compensating for systematic bias, thereby reducing the risk of faulty data during aircraft maneuvering.
Implementation Method 1
receive backscattered optical signals from each of the plurality of directions
Data Source
AI summary
Various embodiments describe time-multiplexing of optical channels in an air data sensor. At least one switch outputs a reference optical signal, and each of a plurality of backscattered optical signals to at least one common optical path at a time. Alternatively stated, the at least one common optical path is configured to receive the reference optical signal and at least one of the backscattered optical signals in sequence. In doing so, the extent of systematic bias present in the at least one common optical path can be compensated for and even reduced during sensor operation.