TECHNOLOGY AREA(S): Sensors

ACQUISITION PROGRAM: NAVSEA 073, Advanced Undersea Technology, submarine ISR buoy development project, PMS435

OBJECTIVE: Leverage recent advances in the maturity, availability, and sensitivity of optical scanning technologies to embed a high fidelity, real-time temperature measurement capability into tow cables for legacy and for new towed sensors and arrays, and towed communication devices whose cables span the upper part of the water column.

DESCRIPTION: Currently, ships and submarines use predictive models in combination with continuous monitoring of seawater injection temperature (i.e., at a single depth) supplemented by intermittent bathythermograph measurements whose fidelity can be influenced by things like uncertain effects of currents spanning the water column.� A high fidelity, real-time, in-situ measurement of temperature can be made across the part of the water column spanned by a cable already in the water.� Compact electro-optical measurement capabilities exist that can be adapted to make the objective feasible.� Unique challenges exist for various combinations of platform, operational speed, and sensor array and communication devices.� In addition, for example, easily modified optical slip rings do not exist for all candidate applications.� Each potential application and technology approach offers unique opportunities to incorporate engineering sensors with which to better account for hydrodynamic effects upon the shape of tow cable and therefore to better associate a temperature along the cable to a specific depth in the ocean.

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 Security Service (DSS).� 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 DSS and NAVSEA 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: Design a temperature measurement capability expected to be both compatible with legacy submarine and surface ship sensor and communications systems employing a tow cable, appropriate to, compatible with, and sized according to the specific system to which the technology may be integrated, that spans the application dependent portion of the water column from the ocean surface to the towed device, up from a submarine or down from a surface ship platform.� Identify the suite of legacy candidate sensor and communication systems and the unique integration issues for each.� Analyze and demonstrate that the required measurement fidelity can be achieved (<5� Celsius error along any 0.5-meter segment of the tow cable) with measurements that can be updated once each second.� It is anticipated that in any Phase II OR Phase III application, a model will be developed to correlate a point to a length along the temperature sensing fiber to a specific ocean depth.� Identify steps that will be taken in Phase II to meet the overall device specifications within a specific application context including what attributes should be included within any new context to improve either affordability, measurement fidelity, or reliability.� The Phase I effort should include prototype plans to be developed during Phase II.

PHASE II: Based upon the Phase I design, deliver a prototype tow cable temperature measurement system suitable to some specific application context and demonstrate that it delivers the required measurement accuracy.� It is expected that, if possible, the application context selected would be one for which there is a transition program sponsor prepared to invest in a Phase III effort.� The threshold performance objective for a Phase II application should be +/- 0.5� Celsius accuracy when measured over a 1-meter span of depth.� It should therefore be anticipated that classified information regarding the specific system application contexts will have to be revealed to the selected contractor/university team.� It is probable that the work under this effort will be classified under Phase II (see Description section for details).� The level of classification will depend specifically upon the classification guidance appropriate to the system to which the temperature measurement capability is integrated as part of a Phase II effort.

PHASE III DUAL USE APPLICATIONS: Ruggedize and mature the temperature measurement and intelligence, surveillance, and reconnaissance (ISR) buoy capability for a specific application context of interest to a Navy acquisition sponsor.� Consider methods to further improve affordability, measurement fidelity, and/or reliability.� In addition, develop an ISR and communications (COMMS) buoy system containing various payloads such as COMMS, Automatic Identification Systems, Electronic Surveillance Measures, and Early Warning receivers, that allow for pay out and retrieval of cable and buoy system.� The core of the instrumented cable must contain the necessary fiber, in appropriate modes, to allow two-way communications.� The technology also has transition potential to the commercial fishing industry as well as to oceanographic and meteorological research applications.

REFERENCES:

1. Hoffman, Lars, et al., �Applications of Fiber Optic Temperature Measurements,� Proc. Estonian Acad. Sci. Eng., 2007, 13, 4, 363�378, http://www.iiit.kit.edu/publ/eng-2007-4-9.pdf

2. Liu, Deming, et al., �Temperature Performance of Raman Scattering in a Data Fiber and its Application in a Distributed Temperature Fiber-optic Sensor,� Proc. Optical Sensing, Imaging and Manipulation for Biological and Biomedical Applications, Taipei, Taiwan, July 2000, https://link.springer.com/article/10.1007/s12200-009-0023-y

KEYWORDS: Raman Scattering; Temperature; Fiber Optic; Sensing; Hydrodynamics; Acoustic Propagation