In-line type micropulse lidar with an annular beam: experiment

Area of Science:

• Atmospheric Science
• Optical Remote Sensing
• Cloud Physics

Background:

• Accurate measurement of low-altitude clouds is crucial for weather forecasting and climate modeling.
• Traditional lidar systems face challenges in near-range measurements and depolarization detection of ice crystals.
• Developing compact and efficient lidar technology is essential for enhanced atmospheric observation.

Purpose of the Study:

• To develop and validate an in-line type compact micropulse lidar (MPL) system for low-altitude cloud characterization.
• To enable precise near-range measurements with a narrow field of view.
• To achieve accurate depolarization measurements of ice crystals in low-altitude clouds.

Main Methods:

• Integration of an optical circulator and axicon prisms to create an annular beam for the MPL.
• Utilizing avalanche photodiode detectors operated in analog mode for sensitive echo detection.
• Verification of lidar performance through mountain echo measurements at various distances.

Main Results:

• The in-line MPL demonstrated effective near-range measurement capabilities with a 0.1 mrad field of view.
• The system successfully performed depolarization measurements of orthogonally polarized echoes from low-altitude ice clouds.
• Insertion loss of the lidar optics was measured at 3 dB, indicating efficient light transmission.

Conclusions:

• The developed in-line compact MPL is a viable tool for detailed low-altitude cloud analysis.
• The system's ability to measure depolarization provides insights into cloud particle properties, particularly ice crystals.
• This technology advances the potential for improved atmospheric remote sensing and cloud research.