larc wind observations with the validar doppler lidar grady j. koch 1, jeffrey y. beyon 2, bruce w....

LaRC

Wind Observations with the VALIDAR Doppler Lidar

Grady J. Koch1, Jeffrey Y. Beyon2, Bruce W. Barnes1, and Michael J. Kavaya1

1NASA Langley Research Center, Hampton, VA USA

2California State University—Los Angeles, Department of

Electrical and Computer Engineering, Los Angeles, CA USA

LaRCObjectives

• System testbed for advanced high-energy lasers and opticalcomponents for future airborne and spaceborne Doppler lidars.

• Serve as ground-based test bed validation source for future airborne and spaceborne lidar measurements

• Test advanced receiver and processing components.

LaRCLidar Specifications

•Laser material: Ho:Tm:LuLiF•Pulse energy = 95 mJ•Pulse width = 180 ns•Pulse repetition rate = 5 Hz•Spectrum = single frequency•Wavelength = 2053.5 nm•Telescope aperture = 6 inches•Detector: InGaAs heterodyne•Digitization rate up to 2 Gs/s at 8 bits (500 Ms/s typical)•Beam scanning: hemispherical coverage

LaRCCoherent Lidar Design

telescopeλ/4

dual-balancedInGaAsphotodiodes

50/50 Coupler

Atmospheric Return

Outgoing pulse

Local Oscillatoracousto-opticmodulator

isolator

isolatorisolator

resonancedetector

Q-switch

Ho:Tm:YLFPZT

λ/2

λ/2

λ/2

λ/2

telescopeλ/4

dual-balancedInGaAsphotodiodes

50/50 Coupler

Atmospheric Return

Outgoing pulse

Local Oscillator

Atmospheric Return

Outgoing pulse

Local Oscillatoracousto-opticmodulator

isolator

isolatorisolator

resonancedetector

Q-switch

Ho:Tm:YLFPZT

λ/2

λ/2

λ/2

λ/2

cw laser

pulsed laser

LaRCVertical Wind Measurement—Clouds and Downdrafts

LaRCVertical Wind Measurement—Thunderstorm

LaRCHorizontal Wind Measurement—Nocturnal Jet

LaRC

Horizontal Wind Measurement—Cirrus in Jet Stream

LaRCFuture Work

•Incorporate higher energy lasers (600 mJ laserdemonstrated).

•Improve receiver efficiency.

•Implement advanced signal processing.

•Develop flight-hardened version.