Technology Readiness Levels of Coherent Doppler Wind Lidar for Earth Orbit

Coherent DWL TRL Levels - 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. SinghNASA Langley Research Center

to

Working Group on Space-Based Lidar Winds28 June – 1 July, 2005

Welches, Oregon


Notional Tropospheric Winds MissionVertical 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 demo’d 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


Doppler Wind Lidar Measurement Geometry

7.4 km/s

833 km

984 km

492 km

348 km

348 km

30

34.445

180 ns (27 m) FWHM (76%)

17 m (86%)

1/10 s = 658 m

t+6.6 ms, 49 m, 6.8 rad for return light(t+100 ms, 744 m, 103 rad for second shot) t + 106 s

120 shots = 12 s = 78 km

90° fore/aft anglein horiz. plane

FOREAFT


Notional Mission Figures of Merit

2.053 m fundamental laser wavelength2.053 m transmitted laser wavelength

0.2 m physical optical diameter0.03 m2 physical optical area0.008 J m2 fund. optical EAP0.08 W m2 fund. optical PAP3.9 W m2 laser electrical PAP3.9 W m2 laser orbit ave elect PAP

10 Hz laser pulse rep freq, PRF2.5 W fundamental optical powerN/A fund to trans conversion efficiency~2.5 W transmitted optical power

0.25 J fundamental laser pulse energy~0.25 J transmitted laser pulse energy

2% laser fundamental WPE125 W laser electrical power when on

100% laser pulsing duty cycleN/A laser power when not pulsing125 W laser orbit average electrical power

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 hour=3600s radiosonde time/vector profile)

30 J trans opt energy/LOS wind profile0.9 J m2 trans EAP/LOS wind profile12 s time interval/ LOS wind profile

60 J trans opt energy/horiz wind profile1.9 J m2 trans EAP/horiz wind profile118 s time interval/horiz wind profile


Notional Tropospheric Winds MissionVertical Profiles of Horizontal Vector Wind

• 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 distributionEach profile covers ~ 118s, 2 x {12 s x 80 km x 25 m}

Courtesy: David Emmitt:


Requirements vs. Predicted PerformanceA

ltitu

de

2

20 km

0100%0

~12

50%

< 2 m/s, 0.5 km

< 3 m/s, 1 km

< 3 m/s, N/A km

Percentage of 300 x 300 km boxes, 24 hr period

Requirements – Threshold

< 1 m/s, 0.25 km

< 2 m/s, 0.5 km

< 2 m/s, 2 km

2

20 km

0

~12

30 km

100%50%0

Requirements - Objective

Background Aerosol Enhanced Aerosol


What Are Technology Readiness Levels (TRLs)?


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?


Space Coherent Doppler Lidar: TRL LevelsTechnology TRL Now TRL After IIP

CompletionComments

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 demo’s 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 < 15 kHz over 4 ms3

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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: /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?

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Space Coherent Doppler Lidar: TRL LevelsTechnology TRL Now TRL After IIP

CompletionComments

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 demo’d 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


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

SHADOE3

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.


Conclusions

• TRL’s don’t cover all circumstances• TRL’s 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 TRL’s

shown here?


Back Up Charts


Current Wind Observations

Courtesy Dr. G. David Emmitt

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

~23.4 km


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 Ho:Tm:LuLF Master-Oscillator-Power-Amplifier (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)

Technology Readiness Levels of Coherent Doppler Wind Lidar for Earth Orbit

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