The Tropospheric Wind Lidar Technology Experiment TWiLiTE, a NASA IIP Technology Development and Dem

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The Tropospheric Wind Lidar Technology Experiment
(TWiLiTE), a NASA IIP Technology Development and
Demonstration
Project B. Gentry, R. Atlas, G. Schwemmer, M.
McGill, M. Hardesty, A. Brewer, T. Wilkerson, J.
Marzouk, S. Lindemann
Working Group on Space Based Lidar Winds June 28
- 30, 2005 Welches, OR
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• High altitude airborne direct detection scanning
  Doppler lidar
• Serves as a system level demonstration and as a
  technology testbed
• Leverages technology investment from multiple
  SBIRs, ESTO, IPO and internal funding
• Consistent with the roadmap and planning
  activities for direct detection and hybrid
  Doppler lidar implementations

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Approach
SBIR

• Leverages significant technology investments and
  instrument development heritage
• SBIRESTOIPOIRAD
• Laser LiteCycles, Fibertek
• Data System ASRC
• HOE Ralcon
• FP etalon MAC
• Fielded Systems
• GLOW, CPL, HARLIE

IRD
IPO
TWiLiTE
HARLIE
CPL
GLOW
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Proposed TWiLiTE Measurement Requirements
Assumes scanner average angular velocity of 12
deg/sec
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TWiLiTE Direct Detection Wind Lidar Key
Technologies
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Laser (LiteCycles)

• Leverages funding from SBIR ESTO
• 15 W optical power in uv (15 mJ _at_ 1000 pps)
• All solid state diode pumped NdYAG laser
• Stable, single frequency operation
• High conversion efficiency to 3rd harmonic (355
  nm)
• Engineered and packaged for aircraft operation
• Heritage Cloud Physics Lidar

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High Brightness Laser (Fibertek)

• Leverages funding from SBIR ESTO
• 2.5 W optical power (50 mJ_at_ 50pps)
• All solid state conduction cooled design
• Stable, single frequency operation
• High conversion efficiency to 3rd harmonic (355
  nm)

Amplifers
Harmonic generators
Seeded Oscillator

• HB Laser on vibration test fixture
• Seeding is stable for 0.5 g bench accelerations
  at frequencies up to 200 Hz

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HOE Telescope/Scanner
The SDL design features a central port for laser
transmission and fiber coupled receiver output.

• HARLIE heritage
• Utah State University/Space Dynamics Lab compact
  folded design
• UV HOE success gt50 efficiency lt200 µrad spot

Recent laboratory measurements (left) verify
performance of 40 cm diam., 355 nm HOEs.
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HOE/Scanner Heritage/Contributors

• 3.5M in NASA Investments since 1990
• PHASERS lidar (532 nm) 1994-present
• HARLIE airborne lidar (1064 nm) 1998-present
  extensive field use
• UV HOEs (355 nm) 2000-present
• 2 NASA patents, 3 USU patents
• Contributors Thomas Wilkerson (SDL/USU),
  Richard Rallison (Ralcon), David Guerra (St.
  Anselm)

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Advanced Molecular Doppler Receiver

• IRAD receiver summary
• Reduce volume of Zephyr Double Edge receiver
  design by gt85
• Increase throughput by 1.8x
• Dynamic range of each channel increased by 2
  orders of magnitude
• Utilizes Michigan Aerospace etalon technology.
• Robust mechanical design suitable for airborne
  or spaceborne applications

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Michigan Aerospace Corporation Advanced Etalon
Technology

• SBIR Phase II awarded in Dec 2004
• Objectives
• Develop lightweight, thermally stable etalon
  design using SiC
• Flight qualify the etalon
• Develop a digital version of the etalon controller

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System Block Diagram
Power Dist/Sw
MOLECULAR DE DOPPLER RECEIVER
INS/GPS Data
PRESSURE VESSEL
ETALON
ETALON SPACING/PARALLELISM
Etalon Control
ANALOG/PHOTON COUNTS, SYS DATA
Data Acq.
SIGNAL FIBER
Bm Exp
AUTO FOV TO COMP
SYNC
Timing/Control
Computer
PRESSURE VESSEL
HOE Scanner/ Telescope
Laser Cooling
Laser
Laser Power
RECEIVER TEMP CONTROL
INS/GPS
AUTO TIP/TILT ADJ
Scanner Ctrl
PRESSURE VESSEL
Window
Det. Box Temp
PRESSURE VESSEL
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Design Concept Mechanical
Doppler Receiver
HOE Telescope/ Scanner
Data System Flight Electronics
Laser
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TWiLiTE Schedule

• Anticipate September 2005 start
• Initial Test Flights in 2008