Bi-axial Laser Anemometry Probe for Aircraft Speed Vector Measurement
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Solution Overview
Problem
Current single-axis laser anemometry probes are inadequate for directly measuring the norm of the relative speed vector of an aircraft with respect to the air due to varying local angles of incidence and sideslip, and combining two probes increases cost and risk of failure.
Innovation Solution
A bi-axis laser anemometry probe design that splits the laser beam into two signals for separate amplification and detection paths, using polarization maintaining couplers and balanced detectors to measure relative speed in two directions without duplicating costly components, and employing integrated optical technology for production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two single-axis laser anemometry probes are combined to measure the relative speed vector, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines two single-axis laser anemometry probes into a single bi-axis probe by merging their optical paths. The laser source is split into two beams that travel along different axes, and the backscattered signals from both axes are combined and detected by a single balanced detector, reducing the number of independent probe units needed.
Solution Approach 2:
The bi-axis probe design allows a single device to perform measurements in two different directions simultaneously. The shared optical components (laser source, balanced detector, polarization maintaining coupler) serve multiple functions for both measurement axes, making the probe more versatile while reducing overall complexity.
2Measurement precision
If two single-axis laser anemometry probes are combined to measure the relative speed vector, then measurement precision is improved, but reliability deteriorates due to increased risk of breakdowns
Solution Approach 1:
By merging the optical paths of two probes into one bi-axis probe, the invention reduces the total number of independent components that could fail. Critical components such as the laser source and balanced detector are shared between both measurement axes, so a failure in one axis does not necessarily cause the entire system to fail.
3Measurement precision
If two single-axis laser anemometry probes are combined to measure the relative speed vector, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The bi-axis probe design merges expensive components such as the laser source and balanced detector into shared resources for both measurement axes. This eliminates the need to purchase and install two separate laser sources and two separate detectors, significantly reducing the overall manufacturing cost while maintaining the capability to measure velocity vectors in two directions.
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
Enables accurate determination of the aircraft's relative speed vector at reduced cost and lower risk of failure, while avoiding the duplication of expensive components and improving signal processing efficiency.
Implementation Method 1
a laser source supplying a linearly polarized reference wave
Implementation Method 2
measuring the frequency shift, representative of the relative speed relative to the air, between a laser beam emitted into the atmosphere and the beam backscattered by the natural aerosols of the air
Implementation Method 3
a polarization matching element disposed upstream of the polarization maintaining coupler to ensure that the backscattered signal and the reference wave have the same polarization
Implementation Method 4
optical homodyne detection of frequency shift by Doppler effect
Data Source
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AI summary
The probe has a signal separator (SEP3) separating a signal from a laser source (SL) into signals respectively transmitted to an amplifier (AMP2) and to a polarization maintained coupler (CPLMP). A backscattered beam separator (SFRD2) transmits the signal from the amplifier to a transmitter/receiver device (DERF2). Return pathways (VR1, VR2) respectively transmit a signal backscattered from another backscattered beam separator (SFRD1) at an input of another signal separator (SEP1) and the signal backscattered from the former beam separator at the input of the former signal separator. An independent claim is also included for a method for etching a biaxial laser anemometry probe on a glass plate.