Technology Readiness Levels of Coherent Doppler Wind Lidar for Earth Orbit

1
Technology Readiness Levels of Coherent Doppler
Wind Lidar for Earth Orbit

• by
• M. J. Kavaya, F. Amzajerdian, J. Yu, G. J. Koch,
  U. N. Singh
• NASA Langley Research Center
• to
• Working Group on Space-Based Lidar Winds
• 28 June 1 July, 2005
• Welches, Oregon

2
Notional Tropospheric Winds Mission Vertical
Profiles of Horizontal Vector Wind

• 833 km sun-syn. polar orbit, on NPOESS S/C for
  reduced NASA cost
• Step-stare conical scan, 30 deg. nadir angle, 4
  az., for 2 vector wind lines (4 shown in figure)
• LaRC unique high-energy 2-micron pulsed laser, 10
  Hz pulse rate
• 0.25 J pulse energy (1.5 J demod at LaRC).
  Derated to extend lifetime conserve power
• 120 shots per LOS wind profile (12 sec, 78 km)
  for better sensitivity
• 20 cm optics to minimize mass, volume, alignment
  risk

3
Doppler Wind Lidar Measurement Geometry
t6.6 ms, 49 m, 6.8 mrad for return light (t100
ms, 744 m, 103 mrad for second shot)
t 106 s
7.4 km/s
90 fore/aft angle in horiz. plane
984 km
30
FORE
AFT
833 km
17 m (86)
180 ns (27 m) FWHM (76)
45
34.4
120 shots 12 s 78 km
492 km
348 km
1/10 s 658 m
348 km
4
Notional Mission Figures of Merit
2.053 mm fundamental laser wavelength 2.053 mm
transmitted laser wavelength
0.2 m physical optical diameter 0.03 m2
physical optical area 0.008 J m2 fund. l
optical EAP 0.08 W m2 fund. l optical PAP 3.9
W m2 laser electrical PAP 3.9 W m2
laser orbit ave elect PAP
0.25 J fundamental laser pulse energy 0.25
J transmitted laser pulse energy
10 Hz laser pulse rep freq, PRF 2.5 W
fundamental optical power N/A fund to trans
conversion efficiency 2.5 W transmitted optical
power
30 J trans opt energy/LOS wind profile 0.9 J m2
trans EAP/LOS wind profile 12 s
time interval/ LOS wind profile
2 laser fundamental l WPE 125 W laser
electrical power when on 100 laser pulsing duty
cycle N/A laser power when not pulsing 125
W laser orbit average electrical power
60 J trans opt energy/horiz wind profile 1.9 J
m2 trans EAP/horiz wind profile 118
s time interval/horiz wind profile
350 km horizontal resolution (repeat
dis) 2 vector wind profiles/horiz res. 53 s time
interval/horiz res. 3250 attempted vector wind
profiles/day (1700 radiosondes/day) (1
hour3600s radiosonde time/vector profile)
5
Notional Tropospheric Winds Mission Vertical
Profiles of Horizontal Vector Wind
Courtesy David Emmitt

• Coherent detection yields 1-2 m/s HLOS wind
  accuracy (RMSE)
• Earth has 5668 target areas (300 x 300 km)
• 14.2 orbits per day per S/C
• 52 of target volumes viewed by single S/C in one
  day, geometry factor (blue area)
• Lidar success percent 50 near surface, less
  with increasing altitude (gray area)
• Enhanced aerosol model, 2 vector wind lines,
  vertical resolution as shown
• Repeat every 53 sec 350 km horizontal
  resolution

3250 attempted vector profiles/day (1700
radiosondes/day) Successful profiles equals
radiosonde network near surface, but different
global distribution Each profile covers 118s, 2
x 12 s x 80 km x 25 m
6
Requirements vs. Predicted Performance
Requirements Threshold
Requirements - Objective
Background Aerosol
Enhanced Aerosol
7
What Are Technology Readiness Levels (TRLs)?
8
TRL Pros and Cons

• Used by everyone in human quest to express the
  complex in overly simplistic terms
• Many common circumstances have no guiding TRL
  rules for consistency
• e.g., if you take a lidar system and fly it
  successfully on an airplane, are you only up to
  TRL 4?
• e.g., if you successfully space qualify a lidar
  system with thermal/vacuum, vibration, EMI, etc.,
  are you up to TRL 8?
• e.g., if a side-pumped laser flew successfully in
  space, but now you want to propose an end-pumped
  version, what is the TRL? (same for bandwidth,
  beam quality, stability, cooling technique, etc.)
• e.g., if a laser flew successfully in space for a
  1-year mission, but now you want to proposed a
  3-year mission, what is the TRL?
• e.g., if another agency/country/group of people
  has a successful space mission, can you take
  credit for TRL 9 with no guaranteed mechanism to
  transfer the knowledge to your mission team?

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Space Coherent Doppler Lidar TRL Levels
Technology TRL Now TRL After IIP Completion Comments
Pulsed 2 Micron Laser 3-4 4 except lifetime 3
Pulsed Laser Energy PRF 0.25J, 10 Hz 4 Same Demonstrated 1 J (1.5 J double pulse) 10 Hz1
Pulsed Laser Efficiency 2 WPE 4 Same Efficiency demonstrated except for space environment. CALIPSO demos power supply effciency
Pulsed Laser Beam Quality ?? 4 Same Beam quality of 1.2 demonstrated in earlier version of laser
Pulsed Laser Packaging compact, rugged 3 4 Technology compatible with compact, rugged packaging
Pulsed Laser Conductively Cooled 4 Same Laser Risk Reduction Program is working on this technology
Pulsed Laser Pump Laser Diodes 3 5 Laser Risk Reduction Program is working on this technology2, not IIP
Pulsed Laser Lifetime 3 years 3 4 Laser Risk Reduction Program is working on this issue, not IIP
CW Tunable LO Laser, Crystal Laser 5-6 Same (JPL working on semiconductor version)
CW LO Laser Power 25 mW 5-6 Same 100, 250, 850 mW delivered by CTI.3 Space tests during SPARCLE
CW LO Laser Tuning Range 6 GHz 5-6 Same Demonstrated 12.5 GHz by CTI (3/00) demonstrated offset locking to 10 GHz3
CW LO Laser Linewidth 0.1 MHz 5-6 Same CTI demonstrated lt 15 kHz over 4 ms3
Simultaneous
Simultaneous
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Space Coherent Doppler Lidar TRL Levels
Technology TRL Now TRL After IIP Completion Comments
Detector, 2-Micron, Room Temperature 5 Same
Detector Quantum Efficiency at IF Frequency 80 5 Same Demonstrated 80 in VALIDAR3
Detector Bandwidth 500 MHz 5 Same Demonstrated 1 GHz in VALIDAR4, 2.4 GHz by UAH
Detector Active Area 75 micron dia. 5 Same Demonstrated 75 microns diameter in VALIDAR4
Telescope 4 Same
Telescope Diameter 20 cm 4 Same 23 cm telescope fabricated during SPARCLE, delivered 11/96
Telescope Wavefront Quality l/18, RMS, 2 micron, double pass 4 Same Demonstrated during SPARCLE
Telescope Volume 30 x 34 x 27 cm3 4 Same Demonstrated during SPARCLE
Scanner, Conical, Step-Stare 2-7 Same
Scanner Wedge 20 cm 4 Same Fabricated during SPARCLE, 28 cm, 30 deg, 11.5 lbs
Scanner Motor 20 cm 4 Same Fabricated during SPARCLE by BEI, 23 cm, 36 lbs, available for space?
Simultaneous
Simultaneous
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Space Coherent Doppler Lidar TRL Levels
Technology TRL Now TRL After IIP Completion Comments
Momentum Compensation of Step-Stare Scanner 2-7 Same Addressed briefly by IMDC, 2/02. Previous space missions?
Pointing 2-7 Same
1. Pre-Shot Pointing Control 2 degrees 7 Same Put Doppler shift within LO tuning range. (GLAS 145 microradians)
2. Pre-Shot Nadir Azimuth Pointing Knowedge Error 0.2 degrees 2-7 Same Depends on azimuth angle and allowed receiver capture bandwidth. Previous space missions?
3. Transmitter/Receiver Misalignment, for 7 ms after each shot 8 microradians (2 microradians/ms) 3? Same Yields budgeted average SNR loss of 3 dB, combination of instrument and spacecraft. Design - SPARCLE
4. Pointing Stability During Shot Accumulation 0.2 degrees/12 sec ( 0.03 deg/sec) 7 Same Yields budgeted 0.3 m/s contribution to error. Depends on azimuth angle. Depends on horiz. wind magnitude/dir. (Hubble 0.05 microrad/24 hrs)
5. Final Nadir Azimuth Pointing Angle Knowledge Error 65 microradians 5 Same Yields 0.3 m/s contribution to error. Depends on azimuth angles. GLAS demonstration dedicated spacecraft. Ground return demod by SWA/LAHDSSA using TODWL - must scan to work. (GLAS 7 microradians)
Lidar Autonomous Operation 2-5 Same CTI has coherent Doppler lidars operating autonomously at 2 airports. NASA does not have this capability
Pre-Launch Lidar Photon Sensitivity Validation 3 Same A method was formulated during SPARCLE, but not implemented
Applies to both coherent and direct detection
Doppler wind lidar
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Space Coherent Doppler Lidar TRL Levels
Technology TRL Now TRL After IIP Completion Comments
Compensation Optics for Nadir Angle Tipping During Round Trip Time of Light Optional? 2 2 7 microrad. tipping for 833 km orbit. Static compensation? Slaved to scanner position?
Array Heterodyne Detector for Alignment Maintenance. Optional? 2 Same Some work done by Rod Frehlich at Univ. of CO.
Lidar Survives Radiation Environment 2 Same Medium effort under LRRP
Lidar Survives Contamination 2 Same Medium effort under LRRP
Optional Balanced heterodyne receiver 5 Same Demonstrated in VALIDAR
Optional Integrated monolithic heterodyne receiver 3 Same Low funded effort under LRRP at LaRC
Optional Multiwavelength lidar scanner 1.5 m direct, 0.2 m coherent HOE SHADOE 3 2 Same Same Geary Schwemmer, GSFC
Optional Semiconductor Version Of Tunable LO Laser 3 Same Being developed at JPL, Kamjou Mansour
Space Integrated GPS/INS (SIGI). Optional? 8 Same Purchased during SPARCLE, available for use
Optional Ground and Airborne Measurement Validation Fleet ? Same May roughly prove orbiting sensor works, but will not prove velocity error or spatial resolution is satisfactory.
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Conclusions

• TRLs dont cover all circumstances
• TRLs are often used in an overly simplistic way
• It is helpful to do a comprehensive TRL analysis
• The TRL scores will vary with who is assumed to
  implement the mission
• The gap to close for the notional mission is
  narrowing
• Are there any suggested changes to the TRLs
  shown here?

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Back Up Charts
15
Current Wind Observations
23.4 km

• Global averages
• If 2 measurements in a box, pick best one
• Emphasis on wind profiles vs. height

Courtesy Dr. G. David Emmitt
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Supporting References

1. S. Chen, J. Yu, M. Petros, Y. Bai, B. C. Trieu,
   M. J. Kavaya, and U. N. Singh, One-Joule
   Double-pulsed HoTmLuLF Master-Oscillator-Power-A
   mplifier (MOPA), Advanced Solid State Photonics
   20th Anniversary Topical Meeting in Vienna,
   Austria (Feb. 6-9, 2005)
2. F. Amzajerdian, B. L. Meadows, U. N. Singh, M. J.
   Kavaya, N. R. Baker, and R. S. Baggott,
   Advancement of High Power Quasi-CW Laser Diode
   Arrays For Space-based Laser Instruments, Proc.
   SPIE 5659, p. N/A, Fourth International
   Asia-Pacific Environmental Remote Sensing
   Symposium, Conference on Lidar Remote Sensing for
   Industry and Environmental Monitoring AE102,
   Honolulu, HI (8-12 Nov 2004)
3. C. P. Hale, J. W. Hobbs, and P. Gatt, Broadly
   Tunable Master/Local Oscillator Lasers for
   Advanced Laser Radar Applications, paper
   5086-25, SPIE AeroSense 2003, Orlando, FL (21-25
   April 2003)
4. G. J. Koch, M. Petros, B. W. Barnes, J. Y Beyon,
   F. Amzajerdian, J. Yu, M. J. Kavaya, and U. N.
   Singh, Validar a testbed for advanced 2-micron
   Doppler lidar, Proc. SPIE 5412, Laser Radar
   Technology and Applications IX (12-16 April 2004)