Supporting NOAA and NASA high-performance space-based DWL measurement objectives with a minimum cost, mass, power, and risk approach employing Optical Autocovariance Wind Lidar (OAWL) Christian J. Grund, Mike Lieber, Bob Pierce, Michelle Stephens, Amnon Talmor, and Carl Weimer Ball Aerospace & Technologies Corp (BATC) February 6, 2008

Page_2 BATC Objectives and Rationales  OAWL, OA-HSRL ─To offer broadened trade space for wind and aerosol profiling technologies addressing NOAA and NASA goals as outlined in the NRC Decadal Survey (3D-winds, ACE, and GACM missions) ─OA approach saves mass, cost, volume, complexity, number of lasers, technical risk (e.g. can reuse CALIPSO/MOLA/GLAS telescope design), and mission performance risk (in conjunction with an etalon receiver)  Why is Ball investing in new receiver technology? ─We believe this is an enabling approach to achieve a space mission ─Target NASA missions start in 2012 (aerosols), but the decisions for the final 3D-wind technology will probably occur in 2010 time frame. Time is now to demonstrate viability of alternatives. ─Belief: Cost, weight, power, complexity, and performance issues of current baseline need addressing. ─Community vetting and acceptance: OAWL is new, but other technologies have year history internal investment  Built proof of concept OAWL system and demonstrated atmospheric wind References:Grund, ” Lidar Wind Profiling from Geostationary Orbit using Imaging Optical Autocovariance Interferometry”, WG on space-based lidar winds 7/2007, Snowmass, CO Grund, et al, “Optical Autocovariance Wind Lidar and Performance from LEO”, 7/2007 Coherent Laser Radar Conference, Snowmass, CO internal investment  Designed and modeled an achromatic, field-widened, high-resolution interferometer (1m OPD), suitable for autonomous aircraft operation - successfully completed ─Prove OA HSRL with Proof of Concept (POC) hardware, in progress  Built comprehensive space-based OAWL radiometric performance modeling capability 2008 internal investment  Fabrication of the robust, multi-wavelength OA receiver design OAWL: Optical Autocovariance Wind Lidar - Doppler wind profiles OA-HSRL: Optical Autocovariance-High Spectral Resolution Lidar - Calibrated Aerosol Profiles

Page_3 OAWL Combines/Augments the Best Traits of Both Coherent and Incoherent Lidar Methods Yes Yes (UV laser) Yes (Simple ROIC) Maybe / Yes Maybe Yes (UV laser) Yes (Difficult ROIC) No Some No (IR laser) N/A Multi-mission Compatibilities HSRL (calibrated aerosols/clouds) DIAL (chemical species) Raman (Chemical species, T, P) Photon counting potential ( GEO?? ) Yes Maybe Yes Yes (integrated with etalons) Yes / Yes Yes No Maybe Yes No Yes No Phenomenology Measure Aerosol Measure Molecular Independent of Aer / Mol mixing ratio Full precision 0-20 km profile Yes 4 (time independent) Yes ~4 / 15 CCD accum. Yes No,Maybe No 1 No Receiver Does not need a stable reference laser Detector elements per profile Single multi-speckle averaging/shot Eliminates orbital velocity correction hardware Single/hopping OK Yes Single, -stable No Single/stable No Transmitter Laser Mode Free of absolute optical frequency lock Direct Detection OAWL Direct Detection Etalons (edge/image) Coherent Detection Challenges Green=positive, Red=negative, yellow=qualified Ball Aerospace & Technologies

2007 Phase 3: Design a Robust, Field-widened, Achromatic Receiver Suitable for Airborne Testing

Page_5 Proof of Concept (POC) OAWL System Demonstrated 1 m/s Precision in Atmospheric Tests Ball Aerospace & Technologies patents pending Demonstrated: ~1m/s precision with 0.3 s averaging and 3m range resolution in atmospheric tests at 60 m, agreeing with model predictions POC Limitations: Rooftop range safety limited to 100m Low power COTS laser limits range 50% light measured by 3 detectors: simple for POC, but not efficient Hard to calibrate due to specific 0- phase sampling implementation Red: OAWL (L); Anemometer-OA cross correlation (R) White: sonic anemometer (L); anemometer autocorrelation (R) Blue: cross correlation for pure Gaussian noise distributions Brassboard system: 3 parallel interferometer architecture:

Overview of Previous Work

Page_7 New OAWL Design Uses Polarization Phase Delays and Multiplexing to Implement 4-Phase-Delay Interferometers with the Same Optical Path Mach-Zehnder-like interferometer allows 100% light detection on 4 detectors Cat’s-eyes field-widen and preserve interference parity allowing wide alignment tolerance, practical simple telescope optics (ALADIN needs ~5  R alignment, Coherent requires  telescope and <3.8  R  alignment (3dB loss)) Receiver is achromatic, allowing simultaneous multi- operations (multi-mission capable: Winds + HSRL(aerosols) + DIAL(chemistry)) Very forgiving of telescope wavefront distortion saving cost, mass, enabling HOE optics for high resolution aerosol measurement 2 inputs allowing easy calibration Ball Aerospace & Technologies patents pending

Page_8 Solid Model of Receiver (detector module covers removed) - All aluminum construction minimizes  T, cost - Athermal interferometer design - Factory-set operational alignment for autonomous aircraft operation - ≈100% opt. eff. to detector - multi- winds, plusHSRL and depolarization for aerosol characterization and ice/water cloud discrimination Detectors: 1 532nm depolarization 1 355nm depolarization 4 532nm winds/HSRL 4 355nm winds/HSRL 10 Total CDR complete Dec. ‘07 Ball Aerospace & Technologies

Page_9 NASTRAN FEA Evaluation Suggests Interferometer is Robust to WB-57 Vibe Environment

Page_10 EOSyM Representation of the OA Receiver System  Coupled disturbance/ structure/ optics model built up inside EOSyM (End-to-end Optical System Model) environment.  Time simulation and frequency domain cross-checking for vibration results.  Seismic mass input of disturbances in 3 directions.  Structure outputs 6 optics displacements in 6 DOF to optical model.  Optical model ray trace and sensitivity matrices. Fringes & phase noise Ball Aerospace & Technologies

Page_11 Integrated Model Process Developed at BATC  Goals: ─ <6 nm (0.11 rad phase error) vibration induced noise), 12 nm accep. ─ <5% visibility reduction due to thermoelastic distortions.  Main system modeling outputs ─ Fringe visibility ─ Phase noise Code V SolidWorks NASTRAN Aircraft PSD 6 References: M. Lieber, C. Weimer, M. Stephens, R. Demara, “Development of a validated end-to-end model for space-based lidar systems”, in SPIE vol 6681, U.N.Singh, Lidar Remote Sensing for Environmental Monitoring VIII, Aug M. Lieber, C. Randall, L. Ayari, N. Schneider, T. Holden, S. Osterman, L. Arboneaux, "System verification of the JMEX mission residual motion requirements with integrated modeling", SPIE 5899, Aug M. Lieber, C. Noecker, S. Kilston, “Integrated system modeling for evaluating the coronagraph approach to planet detection”, SPIE V4860, Aug 2002 Ball Aerospace & Technologies

Page_12 Example Effect of Vibration and Thermoelastic Structural Distortion  Single pixel detection measures sum of the pupil field intensity (proportional to visibility). Full transmission, in phase Zero transmission, out of phase  E=1  E=0  E=0.72  E=0.28 Visibility constant, but phase varies Visibility degraded (integral over pupil) + Piston due to Doppler signal and vibration Tilts due to Thermoelastic distortion and misalignment Ball Aerospace & Technologies

Page_13 Visibility and Phase Noise  Visibility loss means decrease in aerosol velocity measurement optical efficiency, and HSRL aerosol/molecular signal separation.  Phase noise emulates wind-induced phase shift of return signal; unimportant to HSRL Pre-flight calibration goal I max (envelope) = Visibility = Contrast Change due to thermoelastic distortion Change of phase error due to structural vibration during time-of-flight  Flight operating point (slowly drifting) Long period Short period Ball Aerospace & Technologies

Page_14 Integrated Model – Design Iteration: Vibration-Induced Phase Noise Convergence on Specification Log OPD (nm) 1900 nm, initial hard mount 40/ 20 nm, 20 Hz isolators added, WC/ nom 8.5/ 6 nm, redesigned structure, WC/ nom WC = Worst case Requirement: <1m/s/shot/100  s Random dynamic error with WB-57 excitation Final design Prediction Feb : 6nm RMS jitter, exceeding spec and meeting goal, suggests performance dominated by SNR not environment Thermal results: model verifies design is athermal wrt average temperature Ball Aerospace & Technologies

Page_15 In Progress and Proposed Efforts to Raise TRL to 5, Internally Funded Objective: Fabricate OA Receiver Suitable for aircraft flight testing In-Progress Status:  Optical design PDR - complete Sep  Receiver CDR - complete Dec  Receiver design /performance modeled - completeJan  Major components to fabrication – in progressFeb  System Assembled/ preliminary testing - plannedAug Proposals submitted:  NASA ROSES Instrument Incubator Program: ─ PI Grund (Ball), OA winds. Raise TRL for winds from WB-57, complete OA as a system, flight plan to pass over many wind profiler network sites, potential ground lidar near Boulder, land and ocean ─ PI Hostetler (NASA LaRC), OA HSRL. Alternative interferometer approach for multi-wavelength HSRL, data collected could be processed for winds, no special corroborative winds in current plan LOOKING FOR OTHER INTERESTS and POSSIBILITIES Ball Aerospace & Technologies

Page_16 FUTURE CRAD-Proposed Implementation for WB-57 6’ Pallet (WB-57 form factor) Pallet Cover Custom Pallet- Mounting Frame Telescope Custom Window IRAD-Built Receiver Laser Source Ball Aerospace & Technologies

Practical OA performance from Space

Page_18 Comprehensive LEO Performance Model Implemented for Realistic Components LEO Model Parameters: Wavelength 355 nm Pulse Energy 550 mJ Pulse rate 50 Hz Receiver diameter 1m (single beam) LOS angle with vertical 45 0 Vector crossing angle 90 0 Horizontal resolution* 70 km (500 shots) System transmission 0.35 Alignment error 5  R average (NOTE: ~50  R allowed) Background bandwidth 35 pm Orbit altitude 400 km Vertical resolution 0-2 km, 250m 2-12 km, 500m km, 1 km Phenomenology CALIPSO model Validated CALIPSO Backscatter model used. Model calculations validated against short range POC measurements. Ball Aerospace & Technologies

Page_19 OAWL Daytime Space-based Performance OPD 1m, optimized for aerosols Waveform signal processing and 4-channel architecture implemented “Objective” Margin “Thres/Demo” Margin Cloud free LOS Ball Aerospace & Technologies

Page_20 Evaluating Cloud Impacts on OA Wind Accuracy: 1 st Cut  No biases due to aerosol to molecular backscatter mixing ratio  clouds induce no velocity biases  Sliding range gate feasible  independence from range-backscatter weighting errors  Every shot 0-referenced  no dependence on changes in laser spectrum over shot averaging time  Gradual degradation as signals decrease due to opaque cloud fraction or translucent cloud OD: If OD margin = OD cloud that degrades velocity precision to the available margin then, for OAWL: ─ OD margin for “objective” performance is ~0.46 ─ OD margin for “demo/target” performance is ~0.81 Conclusions: for the OA model assumptions, if the LOS cloud attenuation over profile integration time averages to:  OD<0.46, then objective requirements are still met 100% in the PBL  OD<0.81, then demo/threshold requirements are still met 100% in the PBL  For OD>0.81, performance degrades slowly with effective cloud OD as per above equation Running an OSSE would be a good next step to include global statistics. Where N is the number of shots in the profile average, OD cloud is the optical depth of the cloud in each shot above the altitude of interest, and V  is the cloud free velocity error. (might apply to all direct detection lidars if SNR behaves) Ball Aerospace & Technologies

Integrated Direct Detection (IDD) Lidar for Aerosol and Molecular Backscatter Winds

Page_22 Aerosol Winds  Lower atmosphere profile A Single-laser All Direct Detection Solution : Couple OAWL and Etalon receivers Integrated Direct Detection (IDD) wind lidar approach:  OAWL uses most of the aerosol component, rejects molecular.  OAWL HSRL retrieval determines residual aerosol/molecular mixing ratio  Etalon backend processes molecular backscatter winds, corrected by HSRL  Result: ─ single-laser transmitter, single wavelength system ─ single simple, low power and mass signal processor ─ full atmospheric profile using aerosol and molecular backscatter signals Ball Aerospace patents pending Telescope UV Laser Combined Signal Processing HSRL  Aer/mol mixing ratio OAWL Aerosol Receiver Etalon Molecular Receiver Molecular Winds  Upper atmosphere profile Full Atmospheric Profile Data Ball Aerospace & Technologies

Page_23 IDD Receiver vs. ALADIN ALADIN Approach: Common Rec/Trans Telescope 355nm Laser Shutter Fizeau Fringe-Imaging Aerosol Receiver Double-Edge Etalon Molecular Receiver CCD Accumulation Profiling Detectors Proposed OAWL/Etalon IDD Approach: Very small FOV and high receiver / transmitter alignment tolerance are driven by Fizeau resolution and background light accumulation in detectors. High wavefront quality needed to support small FOV. Precludes HOE scanner/telescope. QE advantage but signal accumulation precludes per-shot corrections; frequency stability of laser must extend over shot accumulation time. Receiver Telescope 355nm Laser Field-widened OAWL Aerosol Receiver Double-Edge Etalon Molecular Receiver Per-shot profiling Detectors Field-widening supports: CALIPSO quality telescope HOE scanner/telescope Wide rec/trans. alignment tolerance Shot-resolved detectors support: Simplified laser minimized background light photon-counting, sliding range gate software-only LOS velocity correction detector system redundancy Ball Aerospace & Technologies

Preliminary Mission Technology Assessment

Page_25 Assumptions: Telescope and Scanner WAG’s: Seeking opportunities to work with others on refinements Perhaps publicizing ISAL’s would be useful Ball Aerospace & Technologies Note: Entries in red are chosen for optimal architecture comparisons

Page_26 Assumptions: Laser WAG’s: Seeking opportunities to work with others on refinements Perhaps publicizing ISAL’s would be helpful * Laser performance based on Azita Valinia “Discussion of DWL Airborne Campaigns” on the LWG site Ball Aerospace & Technologies Note: Entries in red are chosen for optimal architecture comparisons

Page_27 Assumptions: Receiver and Misc, Overall Risks WAG’s: Seeking opportunities to work with others on refinements Perhaps publicizing ISAL’s would be useful *presumes OA receiver under construction performs as expected Ball Aerospace & Technologies Notes: Entries in red are chosen for optimal architecture comparisons.

Page_28 Assumptions: Optimal Architecture Comparisons Note: 2 complete transmitters assumed, no receiver redundancy Possibly unnecessary Hybrid Injection Laser Transmiter Laser (2  m) Injection Laser Transmiter Laser (355 nm) Double-edge Etalon receiver 4 Fixed-pointing Telescopes 0.5m, 0.25 waves Coherent receiverT/R Commutator 355nm / 2  m Beam Combiner Integrated DD (IDD) Injection Laser Transmitter Laser (355 nm) Double-edge Etalon receiver 1 HOE Telescope/Scanner 1m, 355nm, 2 waves OAWL receiver Fringe Imaging DD Injection Laser Transmitter Laser (355 nm) Fringe-Imaging Etalon receiver 1 HOE Telescope/Scanner 1m, 355nm, 2 waves Ball Aerospace & Technologies

Page_29 Mass, Power, Risk, Relative Cost Comparison OAWL risk reducers vs. Fringe Imaging: 4 Separate detectors  redundancy (2 min) IDD: separate aerosol and molecular receivers immune to loss of laser frequency control shot-shot correction immune to spectral shape high sensitivity to aerosol when present without needing correction OAWL risk reducers vs. Coherent: Laser technology readiness (schedule, cost) Immunity to loss of laser frequency control Large optics quality requirements (cost, mass) No hardware correction for spacecraft LOS V required Can use HOE telescope/scanner (cost, mass, ~power) Can also provide multi- HSRL (mission cost or technology development cost share?) Ball Aerospace & Technologies **assumes fully redundant lasers

Conclusions and Plans

Page_31 Conclusions: OAWL Progress and Plans OAWL has achieved TRL 3 with a proof of concept brassboard system that demonstrated atmospheric wind measurements to ~1 m/s, consistent with expectation. A comprehensive model predicting space-based OAWL winds and HSRL performance with realistic components has been built and validated by POC measurements and CALIPSO data. The space-based model predicts cloudy and cloud free OAWL performance competitive with the coherent detection component of the hybrid without requiring a separate laser and system. A robust, achromatic, field-widened OAWL receiver has been designed and evaluated using Ball’s end-to-end integrated modeling capabilities. The integrated model predicts performance exceeding requirements for aircraft testing in the WB-57 A 355nm/532nm operable, ruggedized, field-widened OAWL receiver suitable for flexible lidar system integration and high altitude aircraft testing is under construction (planned completion ~Sept. ’08) – we are actively seeking partnerships and funding opportunities to rapidly advance the technology to TRL 5-6. IIP proposals submitted for integration and airborne testing and validation of a full OAWL lidar and separately, for an OA-HSRL demonstration (winds testing not supported at this time). If successful, the proposed efforts will bring OA to TRL-5, and support shake and bake receiver testing as well. OAWL winds from GEO developments will continue in 2008 with realistic scenario modeling including full geometry. Ball Aerospace & Technologies

Page_32 Conclusions: Space-based Lidar Winds Architecture Given: A clear-air profiling capability is a necessity for meeting 3D-winds availability, requiring:  Rayleigh molecular backscatter measurement with a short wavelength laser  a powerful laser transmitter operating in the visible to near UV at a minimum 3D-winds precision in the lower atmosphere requires aerosol backscatter measurement Then: An OAWL and double-edge Integrated Direct Detection (IDD) wind lidar architecture can meet or exceed hybrid performance with a single laser transmitter while reducing mission cost by ~50%, mass by ~67%, and power by ~22%, and at reduced schedule, cost, and performance risks. An OA receiver is potentially suitable for multiple missions specified in the Decadal Survey, offering multiple cost sharing opportunities Ball Aerospace & Technologies