Remote wind sensing with a CW diode laser lidar beyond the coherence regime

Area of Science:

• Atmospheric physics
• Optical engineering
• Remote sensing technology

Background:

• Coherent continuous-wave (CW) lidar systems are crucial for atmospheric wind speed measurement.
• The operational range of these lidar systems is typically limited by the coherence length of the light source.
• Extending the measurement range beyond the coherence regime presents a significant challenge in lidar technology.

Purpose of the Study:

• To experimentally demonstrate a coherent CW lidar system capable of wind speed measurement beyond the coherence regime.
• To provide practical design guidelines for developing wind lidar systems that operate at extended probing distances.
• To validate the performance of such a system through field measurements and comparisons.

Main Methods:

• Utilized two lidar systems with identical optical designs but differing laser linewidths for side-by-side field measurements.
• Operated one lidar system within its coherence regime and the other beyond its coherence range (at least 2.4 times).
• Conducted measurements at a probing distance of 85 meters with a sampling rate of 2 Hz.

Main Results:

• Achieved a high radial wind speed correlation (r²=0.965) between the two lidar systems.
• Successfully demonstrated wind speed measurement capabilities beyond the conventional coherence limits of the light source.
• Validated the feasibility of operating coherent CW lidar at extended ranges.

Conclusions:

• Coherent CW lidar can effectively measure wind speed beyond the coherence regime of the light source.
• The experimental results provide a foundation for designing robust, long-range wind lidar systems.
• This research offers practical insights for overcoming coherence limitations in atmospheric remote sensing.