Development of a Compact, Pulsed, 2-Micron, Coherent-Detection, Doppler Wind Lidar Transceiver

Michael J. Kavaya, Upendra N. Singh, Grady J. Koch, Jirong Yu, Bo C. TrieuNASA Langley Research Center, Hampton, Virginia 23681 USA

Mulugeta PetrosScience and Technology Corporation

Paul J. PetzarNational Institute of Aerospace

Coherent Laser Radar ConferenceToulouse, France

June 23, 2009

Acknowledgments

Grady J. Koch NASA LaRC Co-I, overall lidar system lead, field demonstration, receiver

Jirong Yu NASA LaRC Co-I, pulsed transmitter laser lead

Bo C. Trieu NASA LaRC Co-I, mechanical and thermal engineering

Jeffrey Y. Beyon NASA LaRC Data acquisition HW & SW

Upendra N. Singh NASA LaRC Co-I, pulsed transmitter laser

Carl S. Mills/Paul J. Petzar NASA LaRC/NIA Electronic design & fabrication

G. David Emmitt SWA Airborne Doppler lidar, pointing knowledge

Michael J. Kavaya NASA LaRC Principal Investigator

Garfield A. Creary NASA LaRC Project manager

John Cox SSAI Management consultant

Ramesh K. Kakar/George J. Komar/Janice L. Buckner

NASA ESD/ESTO Guidance & Funding

3

2007

Global Winds9 Societal Benefits

Extreme Weather Warnings

Human Health

Earthquake Early Warning

Improved Weather Prediction #1Sea-Level Rise

Climate Prediction

Freshwater Availability

Ecosystem Services

Air Quality

NRC Decadal Survey

Motivation for 2-Micron Laser/Lidar Development

NRC Recommended “3-D Winds” Mission

Multiple Aspects of 2-Micron Laser/Lidar Advancement at NASA/LaRC

• Laser Physics

• Material Physics

• Laser Architecture

• Pump Laser Diodes

• Pulse Energy

• Pulse Repetition Frequency

• Pulse Length

• Pulse Spectral Width

• Beam Quality

• Electrical Efficiency

• Conductive Cooling

• Compact Packaging

• Lidar Telescope

• Lidar Scanner

• Data Acquisition

• Data Processing

• Ground Demonstration

• Intercomparison

• Airborne Demonstration

• Autonomous Operation

• Laser Lifetime

• Space Qualifiable Brassboard

• Space Qualification

futurepast

Doppler Aerosol WiNd lidar (DAWN)

Compact Engineered Coherent Doppler Lidar Transceiver

Lidar System

Propagation Path (Atmosphere)

Computer, Data Acquisition, and Signal Processing

(including software)

Laser & Optics Scanner Telescope

Target(Atmospheric

Aerosols)

Pulsed Transmitter Laser(includes CW injection laser)

Detector/Receiver(may include 2nd CW LO laser)

Polarizing Beam

Splitter

λ/4Plate

Transceiver

Electronics(Power Supplies,

Controllers)Laser Chillers

DAWN Results

Previous implementation90 mJ per pulse

Completed DAWN packageSmall, Robust, 250 mJ per pulse

DAWN Transceiver (Transmitter + Receiver)250 mJ/pulse, 10 pulses/sec.

5.9” x 11.6” x 26.5”, 75 lbs.; 15 x 29 x 67 cm, 34 kg

(no telescope or scanner)

5.9” x 11.6” x 26.5”

• Smaller

• More energy

• More robust

Commercial Doppler Lidar

2 microns, 2 mJ, 500 Hz, 10 cm telescope111 x 85 x 102 H inches, > $1 M

LaRC DAWN

2 microns, 250 mJ, 5 Hz, 15 cm telescopeTransceiver: 6 x 12 x 27 inches, 75 lbs

DAWN vs. COTS UnitWind figure of merit = E x √PRF x D2

Energy gain = x125Energy-PRF gain = x13Energy-PRF-diameter gain = x26Either x26 in aerosol backscatter sensitivity or x5 in range

DAWN Transceiver vs. Commercial Doppler Lidar

DAWN Wind Measurement Performance

0

1000

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5000

6000

7000

0 5 10 15 20

altit

ude

(m)

wind speed (m/s)

VALIDAR (3-minute integration)sonde

• sonde of February 24, 2009 at 17:59 local

0

1000

2000

3000

4000

5000

6000

7000

270 280 290 300 310 320 330 340

altit

ude

(m)

wind direction (degrees)

VALIDAR (3-minute integration)sonde

• root-mean-square of difference between two sensors for all points shown = 5.78 deg

• root-mean-square of difference between two sensors for all points shown = 1.06 m/s

0

1000

2000

3000

4000

5000

6000

7000

-4 -3 -2 -1 0 1 2

alti

tude

(m)

sonde speed - VALIDAR speed (m/s)

0

1000

2000

3000

4000

5000

6000

7000

-20 -15 -10 -5 0 5 10 15 20

alti

tude

(m)

sonde direction - VALIDAR direction (degrees)

Error Tree

Lidar+Sonde

+Location ∆+Time ∆

+M Volume ∆+M Time Int. ∆

=Total Error

Current Work in Progress

• DAWN-AIR1: Utilize DAWN Transceiver to develop a complete

Doppler lidar system for the DC-8 airplane

• No flights included

• DAWN-AIR2: Utilize DAWN-AIR1 hardware and convert to

operation on the higher altitude WB-57 airplane

• Upgrade hardware to autonomous operation

• Demonstration flights

• Fly with NASA GSFC direct detection Doppler wind lidar system

DAWN-AIR1 Approach

DAWN Transceiver (Transmitter + Receiver)250 mJ/pulse, 10 pulses/sec.

5.9” x 11.6” x 26.5”, 75 lbs.; 15 x 29 x 67 cm, 34 kg(no telescope or scanner)

1. Add telescope and scanner to DAWN

2. Ruggedize electronics for DC-8

Lidar System

Propagation Path (Atmosphere)

Computer, Data Acquisition, and Signal Processing

(including software)

Laser & Optics Scanner Telescope

Target(Atmospheric

Aerosols)

Pulsed Transmitter Laser(includes CW injection laser)

Detector/Receiver(may include 2nd CW LO laser)

Polarizing Beam

Splitter

λ/4Plate

Transceiver

Electronics(Power Supplies,

Controllers)Laser Chillers

DAWN-AIR 1Artist Concept

• 30 deg nadir angle

• Any azimuth angle

DAWN-AIR1

As shown with both the 30deg and 45deg cone

Lidar Sealed EnclosureContains:

DAWN TransceiverTelescopeScanner & Wedge

Vibration Isolation

DAWN-AIR2 Approach

Lidar System

Propagation Path (Atmosphere)

Computer, Data Acquisition, and Signal Processing

(including software)

Laser & Optics Scanner Telescope

Target(Atmospheric

Aerosols)

Pulsed Transmitter Laser(includes CW injection laser)

Detector/Receiver(may include 2nd CW LO laser)

Polarizing Beam

Splitter

λ/4Plate

Transceiver

Electronics(Power Supplies,

Controllers)Laser Chillers

• 2 3-ft pallets

• 45 deg nadir angle

• Any azimuth angle

Conclusions

• Working with NASA LaRC developed 2-micron laser technology that has

demonstrated 1.2 J pulse energy

• Compact, engineered transceiver at 250 mJ, 5 Hz has successfully proven wind

measurement and robustness

• Now developing lidar systems using this transceiver for DC-8 and WB-57

aircraft

• Have proposed to fly in NASA SMD ESD hurricane Genesis and Rapid

Intensification Program (GRIP) in summer 2010

• Desire to continue technology advancement for 3-D Winds space mission