All-Fiber Airborne Coherent Doppler Lidar to Measure Wind Profiles

Abstract

An all-fiber airborne pulsed coherent Doppler lidar (CDL) prototype at 1.54μm is developed to measure wind profiles in the lower troposphere layer. The all-fiber single frequency pulsed laser is operated with pulse energy of 300μJ, pulse width of 400ns and pulse repetition rate of 10kHz. To the best of our knowledge, it is the highest pulse energy of all-fiber eye-safe single frequency laser that is used in airborne coherent wind lidar. The telescope optical diameter of monostatic lidar is 100 mm. Velocity-Azimuth-Display (VAD) scanning is implemented with 20 degrees elevation angle in 8 different azimuths. Real-time signal processing board is developed to acquire and process the heterodyne mixing signal with 10000 pulses spectra accumulated every second. Wind profiles are obtained every 20 seconds. Several experiments are implemented to evaluate the performance of the lidar. We have carried out airborne wind lidar experiments successfully, and the wind profiles are compared with aerological theodolite and ground based wind lidar. Wind speed standard error of less than 0.4m/s is shown between airborne wind lidar and balloon aerological theodolite.

Performance validation on an all-fiber 1.54-μm pulsed coherent Doppler lidar for wind-profile measurement

“…The central wavelength was 1540 nm. 17 The optical antenna system is mainly composed of a fiber optical circulator, a coaxial telescope, and a scanner. The fiber circulator is applied to insulate transmitting laser beam and backscattered signal from aerosols.…”

“…Recently, all-fiber 1.5-μm pulsed CDL has attracted much attention due to its eye safety, compactness, flexible deployment, and mature fiber components from telecommunication industry. 17 The performance of CDL has been proved by intercomparison experiments with reliable wind measurement instruments in the past dozen years. The first high pulse energy CDL (∼100 mJ at 2-μm wavelength) was developed by NASA Langley Research Center; it was used as a calibration and validation lidar (so-called "Validar"), 18 and the intercomparison results with ground-based wind-observing lidar facility were so encouraging.…”

Fiber Lidar for Control of the Ecological State of the Atmosphere

“…Fiber lasers are produced by a number of companies, are structurally simple, and possess increased operational stability and reliability [17][18][19][20][21][22]. The beam divergence of these lasers is close to that of Gaussian beams.…”

Field Performance of All-Fiber Pulsed Coherent Doppler Lidar

“…1.5 μm all-fiber pulsed CDL has attracted much attentions due to its eye safety, compact size, flexible deployment and mature fiber components technology from telecommunication industry. [1] Mitsubishi Electric Corporation has developed an airborne 1.5 μm pulsed CDL which can detect as far as 9.3 km with changeable range resolution of 30, 75 and 150 m. [2] Leosphere displays a long range lidar (Windcube 200S) which can measure 3D wind profiles up to 7 km with 70 m range resolution, 0.5 m/s velocity resolution and 1 s time resolution. [3] Prasad et al have presented a 1.54 μm all-fiber pulsed CDL which can measure wind velocity greater than 120 m/s over ranges greater than 10 km and its range resolution is less than 15 m. [4] Wu et al have designed a 1.5 μm pulsed CDL with high updating rate of 4 Hz and variable physical spatial resolution from 15-60 m. [5] In this study, an all-fiber single mode laser with pulse energy of 300 μJ, pulse width of 400 ns and repetition rate of 10 kHz is used to measure wind velocity in range of 0.1-5 km.…”