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Airborne LIDAR Ocean Temperature Measurement

Description:

RT&L FOCUS AREA(S): General Warfighting Requirements

TECHNOLOGY AREA(S): Battlespace Environments; Information Systems; Sensors

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with section 3.5 of the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws.

OBJECTIVE: Develop and demonstrate an airborne capability to measure with fidelity the temperature of the ocean across the upper part of the water column, where it is most variable - and therefore produces the greatest effects upon acoustic propagation. Fidelity will necessarily vary as a function of platform altitude, platform velocity, and atmospheric properties. Validate an understanding of the limits of performance and a hierarchical understanding of the underlying causes of limited performance.

DESCRIPTION: Active optical (LIDAR) techniques exist to measure sound speed in liquids remotely by spectrally resolving the Brillouin component of the backscatter. In contrast to Raman LIDAR techniques, which require assumptions about salinity to derive sound speed, Brillouin LIDAR techniques are capable of inferring sound speed directly. However, demonstrations of the Brillouin technique have so far been confined to the laboratory, and are not routinely employed in the field, nor do commercial sensors exist.

Any approach offered shall, at a minimum, enable the measurement of sound speed profiles in seawater remotely, along a line of sight, day and night, with an accuracy of at least 1.5 m/s, and an along-beam resolution of 5 m or better, to a total range in mesotrophic waters of at least 40 m. The approach must not depend on assumptions about salinity or temperature of the water, nor the amount of suspended particulates, and must be fieldable and hands-free.

This effort is focused on exploring novel techniques that exploit the Brillouin scatter process to directly measure sound speed in water. Any approach must show early promise for enabling routine operational measurements from seagoing and/or airborne vessels, and must not depend on regular human intervention to operate correctly. Candidate techniques include, but are not limited to, use of stable optical filters, spectrometers, or combinations thereof, to spectrally resolve Brillouin backscatter.

Work produced in Phase II may become classified. Note: The prospective contractor(s) must be U.S. owned and operated with no foreign influence as defined by DoD 5220.22-M, National Industrial Security Program Operating Manual, unless acceptable mitigating procedures can and have been implemented and approved by the Defense Counterintelligence Security Agency (DCSA). The selected contractor and/or subcontractor must be able to acquire and maintain a secret level facility and Personnel Security Clearances, in order to perform on advanced phases of this project as set forth by DCSA and ONR in order to gain access to classified information pertaining to the national defense of the United States and its allies; this will be an inherent requirement. The selected company will be required to safeguard classified material IAW DoD 5220.22-M during the advanced phases of this contract.

PHASE I: Define and develop a concept to obtain profiles of sound speed through seawater that is compatible with deployment on seagoing vessels. The concept shall include a high level description of the hardware and associated algorithms, description of a water tank demonstration, and corresponding performance simulations. All assumptions made for the performance modeling shall be clearly stated. Develop a Phase II plan.

PHASE II: Produce a laboratory water tank demonstration based on the Phase I work. The prototype shall demonstrate the form and function of the critical sensor elements as accurately as possible. The prototype shall be capable of validating key sensor performance parameters; laboratory validations shall be conducted and documented by the awardee using the prototype hardware. Sensor shall be delivered to the Government for testing.

It is probable that the work under this effort will be classified under Phase II (see Description section for details).

PHASE III DUAL USE APPLICATIONS: Interface with stakeholders in both ocean modelling and tactical communities to identify platform (ship, submersible, etc.) and performance needs, then scale and engineer the system appropriately to those needs.

REFERENCES:

  1. Hostetler, Chris A., Behrenfeld, Michael J., Hu, Yongxiang, Hair, Johnathan W. and Schulien, Jennifer A. "Spaceborne LIDAR in the study of marine systems." Annual review of marine science 10, 2018, pp. 121-147. https://www.annualreviews.org/doi/pdf/10.1146/annurev-marine-121916-063335  
  2. Englert, Christoph R., Harlander, John M., Brown, Charles M., Marr, Kenneth D., Miller, Ian J., Stump, J. Eloise and Hancock, Jed et al. "Michelson interferometer for global high-resolution thermospheric imaging (MIGHTI): instrument design and calibration." Space science reviews 212, no. 1-2, 2017, pp, 553-584. https://ui.adsabs.harvard.edu/abs/2017SSRv..212..553E/abstrac t
  3. Mountain, Raymond D. "Spectral distribution of scattered light in a simple fluid." Reviews of Modern Physics 38, no. 1, 1966, p. 205. https://doi.org/10.1103/RevModPhys.38.205  
  4. Englert, Christoph R., Babcock, David D. and Harlander, John M. "Doppler asymmetric spatial heterodyne spectroscopy (DASH): concept and experimental demonstration." Applied Optics, Volume 46, Issue 29, 2007, pp. 7297-7307. https://www.osapublishing.org/ao/abstract.cfm?uri=ao-46-29-7297  
  5. Joelson, Brad D., and Kattawar, George W. "Multiple scattering effects on the remote sensing of the speed of sound in the ocean by Brillouin scattering." Applied Optics, Volume 35, Issue 15, 1996, pp. 7297-7307. https://www.osapublishing.org/ao/abstract.cfm?uri=ao-46-29-7297
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