performance testing of a risk reduction space winds lidar laser transmitter floyd hovis, fibertek,...
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FIBERTEK, INC.
Performance Testing of a Risk Reduction Space Winds Lidar Laser Transmitter
Floyd Hovis, Fibertek, Inc.
Jinxue Wang, Raytheon Space and Airborne Systems
February 8, 2006
FIBERTEK, INC. Approach to Developing Space-Qualified 355 nm Lasers
Develop a robust, single frequency 355 nm laser for airborne and space-based direct detection wind lidar systems
–All solid-state, diode pumped–Robust packaging–Tolerant of moderate vibration levels during operation–Space-qualifiable design
Incorporate first generation laser transmitters into ground-based and airborne field systems to demonstrate and evaluate designs
–Goddard Lidar Observatory for Winds (GLOW)–Balloon based Doppler wind lidar being developed by Michigan Aerospace and
the University of New Hampshire for NOAA
Develop scaling to higher powers and pulse energies–Raytheon funded Space Winds Lidar Risk Reduction Laser Transmitter–Air Force SBIR to develop a 500 mJ, 100 Hz 1064 nm pump source
Iterate designs for improved compatibility with a space-based mission–Lighter and smaller–Radiation hardened electronics
FIBERTEK, INC. Status of Related Laser Development Programs
Customer Application Required 1 m Performance Program Status
Univ. of NH Doppler Wind Lidar 150 mJ at 50 Hz Delivery complete
NASA Langley Ozone DIAL 1000 mJ/pulse at 50 Hz Delivery complete
Raytheon Doppler Wind Lidar 1000 mJ at 50 Hz Delivery complete
Air Force Remote Imaging Lidar 500 mJ at 100 Hz Testing in progress
NASA Langley Phase II SBIR Seed & Metrology Laser 50 mW single frequency Prototype demonstrated
NASA Langley High Spectral Res. Lidar IIP 200 mJ at 200 Hz Final build in progress
NASA Langley Mars exploration 40 mJ at 20 Hz Delivery complete
Navy SBIR Rangefinder/Designator 300 mJ at 25 Hz Final build in progress
NASA GSFC Doppler Wind Lidar IIP 100 mJ at 200 Hz Final build in progress
Single frequency pump head & resonator technology will support a significant number of next generation lidar applications
Single frequency laser development has a broad support base
FIBERTEK, INC.
Summary of Technical Approach
An all solid-state diode-pumped laser transmitter featuring:
Injection seeded ring laser Improves emission brightness (M2)
Diode-pumped zigzag slab amplifiers Robust and efficient design for use in space
Advanced E-O phase modulator material Allows high frequency cavity modulation for improved stability injection seeding
Alignment insensitive / boresight Stable and reliable operation over stable 1.0 m cavity and optical bench environment
Conduction cooled Eliminates circulating liquids w/in cavity
High efficiency third harmonic generation Reduces on orbit power requirements
Space-qualifiable electrical design Reduces cost and schedule risk for a future space-based mission
FIBERTEK, INC. Raytheon 1 J Risk Reduction Laser Optical Layout
Final System Optical Configuration
Both the original NASA Ozone amplifiers and the power amplifier have been shown to be capable of 100 Hz operation
Power amplifier
Expansiontelescope
Amplifier #2
Amplifier #1
LBO doubler
355 nm output
LBO tripler
Fiber port
Ring Resonator
Fiber-coupled 1 m seed laser
Optical isolator
FIBERTEK, INC. Raytheon 1 J Risk Reduction Laser Optical Layout
Final System Optical Configuration
Both the original NASA Ozone amplifiers and the power amplifier have been shown to be capable of 100 Hz operation
Ring oscillator
Amp #2
Power amp
Amp #1
FIBERTEK, INC.Solid Model of Integrated LaserTop View - Electrical Connection End
Laser Optics Module (LOM)
Laser Electronics Unit
(LEU)
LEU cooling plates
LOM/LEU electrical interconnections
28 VDC terminals
FIBERTEK, INC. Solid Model of Integrated LaserTop View - Optical Output End
Laser Optics Module (LOM)
Laser Electronics Unit
(LEU)
LEU cooling plates
Output windows
FIBERTEK, INC. Solid Model of Integrated LaserBottom View
Laser Optics Module (LOM)
Laser Electronics Unit
(LEU)
LOM cooling plates
Mounting foot
Mounting foot
Mounting foot
FIBERTEK, INC. Acceptance Testing of Space Winds Lidar Laser Transmitter Is Complete
Final acceptance testing was completed in November 2006
Space-Winds Lidar Laser Transmitter
Design uses all three amplifiers
Autonomous operation controlled through RS232 serial interface
Nominal 28 VDC primary power
Space-qualifiable electrical design
Thermal control through conductive cooling to liquid cooled plates bolted to bottom of laser module
355 nm single frequency output of over 460 mJ/pulse @ 50 Hz (23 W)
Delivered system will undergo extended life testing at Raytheon
Laser module
Electronics module
FIBERTEK, INC. Acceptance Testing1064 nm Power & Energy Test Results
50 Hz operation
Final 1064 nm power - 44.4 W (888 mJ/pulse)
Input electrical power - 684W
Wall plug efficiency - 6.5%
77% of final power is reached in 1 min
99% of final power is reached in 2 minutes
Short term (20 s) shot to shot energy stability is 0.8% (3)
Long term (30 min) energy stability is 3.7% (3)
Pulse width - 14 ns
1064 nm power vs. time after Armed to High Power transition
Time (minutes)
0 10 20 30 40 50 60
1064 nm output power (W)
0
10
20
30
40
50
FIBERTEK, INC.Acceptance Testing
355 nm Power & Energy Test Results
50 Hz operation
Final 355 nm power - 23.9 W (478 mJ/pulse)
Input electrical power - 684W
355 nm conversion efficiency - 53.8%
Wall plug efficiency - 3.5%
74% of final power is reached in 1 min
93% of final power is reached in 2 minutes
Short term (20 s) shot to shot energy stability is 3.5% (3)
Long term (30 min) energy stability is 4.3% (3)
Pulse width - 14 ns
355 nm power vs. time after Armed to High Power transition
Time (minutes)
0 10 20 30 40 50 60
355 nm output power (W)
0
5
10
15
20
25
30
FIBERTEK, INC.
Acceptance Testing 1064 nm M2
Near field profile Beam quality data
M2x = 2.2
M2y = 2.3
FIBERTEK, INC.
Acceptance Testing 355 nm M2
Near field profile Beam quality data
M2x = 4.0
M2y =5.7
FIBERTEK, INC. Acceptance Testing Pointing Stability
1064 nm data 355 nm data
1064 nm pointing stability < 64 µrad (<5% of raw beam divergence) 355 nm pointing stability < 71 µrad (<10% of raw beam divergence)
X position (µm)
3150 3200 3250 3300 3350 3400 3450
Y position (µm)
3350
3400
3450
3500
3550
3600
3650
Circle containing 90% of centroid values
X position (µm)
3400 3420 3440 3460 3480 3500 3520 3540 3560 3580 3600
Y position (µm)
3100
3150
3200
3250
3300
Circle containing 90% of centroid values
FIBERTEK, INC. Acceptance Testing 1064 nm Frequency Stability
Frequency drift is < 1 MHz/min and appears to bedominated by seed laser frequency drift
1064 nm relative frequency drift
Time (minutes)
0 20 40 60 80 100
Relative frequency (MHz)
0
10
20
30
40
FIBERTEK, INC.
Acknowledgements
BalloonWinds laser transmitter was funded by NOAA BalloonWinds
Program through UNH and MAC
Space Doppler Winds LIDAR risk-reduction laser transmitter was funded by
Raytheon Internal Research and Development (IRAD)
NASA support through the SBIR and Advanced Technology Initiative
programs
Air Force SBIR funding for 100 Hz laser development
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