Multi-Fiber Optical Ice Detection With Wall-Echo Exclusion
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Solution Overview
Problem
Existing wind tunnel systems face challenges in accurately measuring cloud parameters due to spatial overlap between the projection and detection fields of view, which are limited by physical barriers, leading to inaccurate results from strong laser echoes generated by the tunnel walls.
Innovation Solution
A system and method utilizing a single collimation lens to span the projection and detection fields of view, combined with off-set light detectors to avoid spatial overlap with tunnel walls, allowing for accurate characterization of cloud parameters by reducing or eliminating strong laser echoes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the detection field of view is extended to increase sampling range in wind tunnel, then more cloud parameters can be measured, but wall structures enter the detection field causing strong laser echoes and saturation
Solution Approach 1:
The patent applies asymmetry by using multiple detectors positioned at different offset angles relative to the laser projection axis. This asymmetric arrangement creates different detection geometries where the intersection of the laser field and detection fields varies by detector, allowing some detectors to avoid wall structure echoes while maintaining extended sampling range.
Solution Approach 2:
The patent transitions from a single-axis detection approach to a multi-dimensional detection scheme by arranging detectors at various angular offsets from the projection axis. This dimensional change in detector configuration allows the system to sample cloud parameters over an extended range while excluding wall structures from the detection field through geometric separation.
2Measurement precision
If multiple detectors are used to extend detection coverage, then more cloud parameters can be characterized, but spatial overlap with wall structures increases causing measurement inaccuracies
Solution Approach 1:
The patent segments the detection function by using multiple detectors, each with a specific offset angle from the projection axis. Each detector segment covers a particular angular range, and by combining measurements from multiple segmented detectors, the system achieves comprehensive cloud parameter characterization while managing spatial overlap through geometric distribution.
3Measurement precision
If the laser pulse energy is increased to improve signal detection, then backscatter detection sensitivity increases, but saturation from wall echoes worsens
Solution Approach 1:
The patent applies local quality by having each detector optimized for a specific angular offset from the projection axis. Each detector's field of view is tailored to its position, creating localized detection zones that avoid wall structure interference. This allows the system to use sufficient laser pulse energy for sensitive backscatter detection while each detector locally excludes wall echoes through its specific angular configuration.
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 precise measurement of cloud parameters by minimizing interference from tunnel walls, providing reliable data for cloud characterization, including particle size and water content, even in small wind tunnel volumes.
Implementation Method 1
measures the backscatter as a function of the time-of-flight of a pulse to generate backscatter signals. Backscatter provides an estimate of a characteristic droplet or ice crystal size and the liquid and/or ice water content of the clouds
Implementation Method 2
A single collimation lens is utilized in conjunction with multiple detectors arranged at multiple increasing off-set angles from a projection axis of the laser
Implementation Method 3
optionally using polarized light to discern non-spherical particles
Data Source
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AI summary
A system (10) for determining parameters of a cloud atmosphere within a wind tunnel. The system includes: a light projector configured to project a pulse of light energy into a projection field of view (20); at least one light detector having a detection field of view (22,24) that forms a range-limited intersection with the projection field of view, the range-limited intersection having a maximum sampling range so as to exclude wall structures of the wind tunnel, wherein the at least one light detector is configured to detect a backscattered portion of the projected pulse of light energy backscattered from within the range-limited intersection; and a cloud parameter calculator configured to determine parameters of the cloud atmosphere based on the backscattered portions detected.