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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.
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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
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
Approach SBIR • Leverages significant technology investments and instrument development heritage • SBIR+ESTO+IPO+IRAD • Laser – LiteCycles, Fibertek • Data System – ASRC • HOE – Ralcon • FP etalon – MAC • Fielded Systems • GLOW, CPL, HARLIE IR&D IPO TWiLiTE HARLIE CPL GLOW
Proposed TWiLiTE Measurement Requirements * Assumes scanner average angular velocity of 12 deg/sec
Laser (LiteCycles) • Leverages funding from SBIR + ESTO • 15 W optical power in uv (15 mJ @ 1000 pps) • All solid state diode pumped Nd:YAG laser • Stable, single frequency operation • High conversion efficiency to 3rd harmonic (355 nm) • Engineered and packaged for aircraft operation • Heritage: Cloud Physics Lidar
High Brightness Laser (Fibertek) • Leverages funding from SBIR + ESTO • 2.5 W optical power (50 mJ@ 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
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 – >50% efficiency; <200 µrad spot Recent laboratory measurements (left) verify performance of 40 cm diam., 355 nm HOEs.
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)
Advanced Molecular Doppler Receiver • IRAD receiver summary • Reduce volume of Zephyr Double Edge receiver design by >85% • 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
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
A/D SIGNAL FIBER WATER POWER 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
Design Concept Mechanical HOE Telescope/ Scanner Doppler Receiver Data System+ Flight Electronics Laser
TWiLiTE Schedule • Anticipate September 2005 start • Initial Test Flights in 2008