Single-Wavelength LIDAR for Cloud Droplet Size Estimation
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Solution Overview
Problem
Current systems for measuring super-cooled water droplet sizes in cloud atmospheres require complex dual-laser LIDAR systems, which are cumbersome and not easily adaptable for real-time monitoring of effective water particle sizes, posing risks for aircraft due to unpredictable ice accretion and aerodynamic alterations.
Innovation Solution
A system utilizing a single monochromatic laser to generate a pulse of light, detect backscattered signals, and calculate an optical extinction coefficient and backscatter coefficient to estimate the effective size of water particles based on a LIDAR ratio, providing a simpler and more efficient method for determining water droplet sizes in cloud atmospheres.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dual-laser LIDAR system is used to measure water droplet sizes, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent changes the measurement parameter from requiring two different wavelengths to using a single wavelength with polarization analysis. By measuring the polarization state of backscattered light at one wavelength, the system can distinguish droplet sizes without needing dual-laser complexity
Solution Approach 2:
The patent replaces the mechanical/optical complexity of dual-laser systems with an electromagnetic field-based solution using polarization detection. Instead of using two physical lasers with different wavelengths, the system uses polarization state analysis of light scattered by droplets to determine size information
2Measurement precision
If a dual-laser LIDAR system is used to measure water droplet sizes, then measurement capability is improved, but ease of operation deteriorates
Solution Approach 1:
The system uses the natural polarization properties of light scattered by water droplets without requiring complex active control. The polarization state of backscattered light inherently contains size information, allowing the system to automatically determine droplet characteristics through passive detection
Solution Approach 2:
The patent shifts from measuring intensity differences at two wavelengths to measuring polarization state at a single wavelength. This parameter change simplifies real-time operation because polarization detection can be performed continuously with a single laser source
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 allows for real-time estimation of water droplet sizes, enabling pilots to anticipate and mitigate ice accretion risks without the complexity of dual-laser systems, thereby enhancing aircraft safety and control during flight through cloud conditions.
Implementation Method 1
a laser configured to generate a pulse of light of a wavelength and to direct the pulse of light into the cloud atmosphere
Implementation Method 2
an optical detector configured to detect a portion of the pulse of light backscattered by the water particles in the cloud atmosphere
Data Source
AI summary
Apparatus and associated methods relate to determining sizes of water particles in a cloud atmosphere based on a detected portion of signals generated from a single monochromatic source and backscattered by water particles in a cloud atmosphere. A backscatter coefficient and an optical extinction coefficient are calculated, based on the detected portion of signals generated from the monochromatic source and backscattered by water particles in the cloud atmosphere. A LIDAR ratio—a ratio of the optical extinction coefficient to the backscatter coefficient, is calculated. Sizes of water particles in the cloud atmosphere are estimated based on the LIDAR ratio. An output signal indicative of the estimated sizes of water particles in the cloud atmosphere is generated. Estimating sizes of water particles using signals from a single monochromatic source advantageously can alert a pilot of an aircraft of cloud conditions, without requiring multi-chromatic sources.