DASH Interferometer for High-Precision Tropospheric Wind Profiling
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Solution Overview
Problem
Current space-based systems lack the capability to achieve global tropospheric vertical wind profiles using a Doppler Asymmetric Spatial Heterodyne Spectroscopy (DASH) interferometer as a direct detection system for Doppler wind Light Detection and Ranging (LIDAR) instruments, and there is a need for high-precision tropospheric wind observations.
Innovation Solution
A Doppler Asymmetric Spatial Heterodyne Spectroscopy (DASH) interferometer is integrated into a Doppler wind LIDAR system as a direct detection apparatus, featuring a front-end with a laser and telescope for emitting and collecting backscattered light, and a back-end with a DASH interferometer, readout electronics, and an instrument control module. This system superimposes interference fringes onto the backscattered light, images them on an array detector, and determines the Doppler shift by measuring phase points over a large path difference interval using stationary optical components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Doppler wind LIDAR system uses a direct detection system with a DASH interferometer, then measurement precision of tropospheric wind profiles is improved, but device complexity increases
Solution Approach 1:
The system divides the detection process into distinct functional modules: a DASH interferometer for spectral analysis, an array detector for simultaneous multi-point measurement, and separate optical paths for reference and sample beams. This segmentation allows each component to be optimized independently while maintaining overall measurement precision.
Solution Approach 2:
The patent transitions from traditional single-point spectral measurement to two-dimensional spectral-spatial mapping using the array detector. Each detector element captures interference patterns at different optical path differences simultaneously, enabling parallel measurement of multiple phase points and improving precision without proportionally increasing complexity.
2Measurement precision
If the system uses a large path difference interval for Doppler shift determination, then measurement precision is improved, but the size of the interferometer increases
Solution Approach 1:
The DASH (Doppler Asymmetric Spatial Heterodyne) interferometer employs asymmetric optical path configurations where one arm has a significantly longer path difference than the other. This asymmetry is deliberately designed to maximize the spectral resolution for Doppler shift measurement while keeping the physical footprint compact through folded optical paths and strategic placement of retroreflectors.
Solution Approach 2:
The system uses movable retroreflectors or adjustable optical elements that can dynamically change the optical path difference during operation. This allows the path difference interval to be adjusted based on measurement requirements, enabling high precision measurements when needed while reducing the physical size when maximum precision is not required.
3Reliability
If the system integrates multiple stationary optical components for DASH interferometry, then reliability is improved, but ease of operation decreases
Solution Approach 1:
The patent combines multiple optical functions into integrated components: beam splitting and recombination occur in a single interferometer assembly, the array detector simultaneously performs spectral analysis and spatial mapping, and the optical paths are folded back on themselves to minimize alignment requirements. This merging reduces the number of separate adjustments needed while maintaining reliability.
Solution Approach 2:
The DASH interferometer design includes self-aligning features where the asymmetric optical paths and fixed geometric relationships between components automatically maintain proper alignment. The system requires minimal manual adjustment after installation, as the stationary components are designed to maintain their relative positions and orientations without continuous intervention.
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 system enables the determination of global tropospheric vertical wind profiles with high precision, providing accurate atmospheric wind data for improved weather forecasting, hurricane warnings, and operational asset deployment, while being robust and suitable for space-based, airborne, or ground-based platforms.
Implementation Method 1
a laser 112 which can be a monochromatic laser that illuminates the atmosphere 102
Implementation Method 2
a telescope 114, which collects backscattered laser light return signal(s) 130 backscattered by the atmosphere 102
Implementation Method 3
superimposing, by the DASH interferometer, a plurality of interference fringes of wavenumber dependent spatial frequencies onto the backscattered light return signal
Implementation Method 4
measuring a plurality of phase points of a heterodyned interferogram over a large path difference interval simultaneously... determining a Doppler shift of the backscattered light return signal
Data Source
AI summary
Obtaining global tropospheric vertical wind profiles by directly detecting atmospheric winds using space borne, airborne and/or ground station platforms is accomplished by a DASH interferometer in the back-end of a Doppler wind LIDAR. In the front-end of the Doppler wind LIDAR, a laser illuminates an atmosphere and a telescope collects backscattered laser light return signals from the laser illuminated atmosphere. The DASH interferometer processes return signals from the atmosphere, forming an interferogram and determines from the interferogram a Doppler shift of the return signals, which is equivalent to determining the line of sight wind speed of the Doppler wind LIDAR observation, by measuring the frequency shift caused by winds. From this determination, global and/or non-global atmospheric wind profile data are transmitted over a communications network in either real-time and/or non-real-time, to facilitate weather forecasting, weather modeling, weather avoidance navigation, atmospheric research, hurricane warnings, operations systems selections and deployment of operational assets.