Validation of airborne 1 Validation of airborne 1.5 μm all-fiber coherent lidar measurement of wind profiles Jiqiao Liu, Xiaopeng Zhu, Xin Zhang, Xiaolei Zhu, Weibiao Chen , Shanghai Institute of Optics & Fine Mechanics (SIOM), Chinese Academy of Sciences

Outline Motivation Airborne coherent lidar development Experiment results Summary

1. Motivation In lower atmospheric troposphere, coherent Doppler lidar shows more advantages: High accuracy High spatial and temporal resolution High sensitivity and insensitive to solar background A compact coherent lidar is required to measure wind profiles to almost 3 km altitude. The lidar can meet airborne platform condition. All-fiber pulsed coherent lidar is the best choice!

2. Airborne coherent lidar development 1.5 µm Fiber laser is selected high efficiency robust and low weight fiber components and detector maturity Parameter value Wavelength 1540nm PRF 10 kHz Pulse energy ≥400μJ Pulse width 400-500ns Aperture Ф100mm Scanner 20°off-axis IF 160MHz AD 1G/s ,10bit Resolution 30m/60m Lidar consists of three parts: High Power fiber laser Telescope and scanner Detector Electronics and Power supply Power supply≤600W

Wind vector measurement LOS wind profile Scanning Multiple LOS VAD combined Wind vector （Horizontal wind speed, direction and vertical wind speed）

Coherent wind lidar on airborne platform VAD scanning: 8 azimuth LOS within 15s LOS wind speed of VAD scanning 100mm Lens scanner 20° deflection angle Position ,attitude and velocity are measured from GPS/INS

Airborne wind speeds retrieval LOS wind speeds correction in airborne platform Wind speeds vector retrieval-nonlinear fit equation

1.5μm all-fiber single frequency laser configuration Seeder laser+modulater+MOPA(amplifier)

1.5μm all-fiber single frequency laser source High energy source of 500 μJ ＞500μJ 470ns OSNR>30dB M2:1.10/1.17

Developed airborne coherent Doppler lidar 2017,1.5μm, 35kg （Airborne prototype II） 2015,1.5μm, 45kg （Airborne prototype I） UAV platform Harsh environment endurance : Wide operation temperature range: -40℃-+55℃ Shock: 20g (@10ms)/ Sine vibration: 2g

3. Experiment results Airborne campaign I in Weihai, Shandong (2015) Airborne campaign II in Huayin, Shanxi (2017) (UAV platform)

Airborne campaign in Weihai, Shandong Wind lidar GPS/INS Jan.7-19, 2015 Successful validation for Airborne coherent wind lidar

Airborne campaign in Weihai, Shandong Flight track Altitude:2km Ground validation instruments：Balloon +Ground-based wind lidar

Airborne campaign in Weihai, Shandong Horizontal wind speeds Ocean Land/Ocean Horizontal wind directions

Airborne campaign in Weihai, Shandong Wind speeds comparison -Airborne wind lidar、Balloon and Ground based wind lidar Airborne VS Balloon Airborne VS Balloon Airborne VS Ground Airborne VS Ground

Airborne campaign in Huayin, Shanxi Preliminary experiment on Mar.29, 2017 UAV Flight altitude:3~4km Close to Huashan Mountain Ground Validation instruments GPS Balloon Ground-based wind lidar (Airborne prototype I) Flight trace Ground wind Lidar Mountain height >1600m GPS balloon & Drift path Mountain height >1700m

UAV platform altitude and attitude during flight Flight altitude Pitch cruise Climb Climb Yaw Roll

Airborne campaign in Huayin, Shanxi Horizontal wind speeds Horizontal wind directions

Airborne campaign in Huayin, Shanxi Vertical wind speeds Relative signal amplitude -Jan.19,2015 Range corrected signal Cloud

Airborne campaign in Huayin, Shanxi Wind speeds and directions comparisons - Airborne wind lidar、Balloon and Ground based wind lidar 1700m~3700m Airborne VS Balloon Airborne VS Balloon Balloon VS Ground Balloon VS Ground

Summary The compact airborne coherent wind lidar prototypes with high pulse energy are developed. Airborne campaign experiments are implemented successfully to validate the performance. Further UAV experiments are scheduled in 2018. The airborne wind lidar could also be acted as validation instrument in China for ALADIN wind lidar in future.

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