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Identify and Exploit Attributes of a Light Detection and Ranging (LIDAR) Signal to Improve Sea Mine Detection and Identification with a Low False Alarm Rate

Description:

 
 

TECHNOLOGY AREA(S): Battlespace, Electronics, Sensors

ACQUISITION PROGRAM: PMS 495, Mine Warfare Office, Airborne Laser Mine Detection System (ALMDS)

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 5.4.c.(8) of the solicitation. 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: Identify and exploit attributes of a LIDAR signal in hardware and/or software to demonstrate improved detection and identification of sea mine-like objects with a low false alarm rate for future Navy use.

DESCRIPTION: Organic mine countermeasures (MCM) gives naval and marine units the ability to detect, characterize, and neutralize mines using their own assets. The US Navy and Marines fill gaps in MCM capabilities with electro-optic sensor systems. Airborne and underwater MCM sensors are vital to enabling operational maneuverability from the ship to the objective. To meet Naval MCM requirements, a “system-of-systems” approach has been adopted which consists of minehunting, minesweeping, and mine neutralization systems. These weapon systems are primarily deployed and operated from MH-60S helicopter platforms equipped with Airborne Mine Countermeasures (AMCM).

Minehunting is the preferred method of locating and neutralizing sea mines. One such system, which helps to fill a significant capability gap in complete coverage of the upper water volume and complements other MCM systems, is the Navy’s Airborne Laser Mine Detection System (ALMDS).

The ALMDS is a helicopter-deployed system utilizing a streak tube imaging LIDAR system to rapidly detect, classify, and localize floating and near-surface moored sea mines. The ALMDS uses pulsed laser light and streak tube receivers in a push broom mode for high coverage rate. The transmitted laser light passes through the atmosphere, the ruffled air-water interface, through the seawater and returns along the similar path to the airborne receivers imposing an environmentally induced high “clutter” throughout the area of interest, which limits system performance (ref. 1). A variety of image processing techniques are utilized to optimize the probability of detection (Pd) and the probability of classification (Pc) as well as reduce the false alarm rate (FAR).

As with all airborne laser interrogation systems flying over water, the optical return from the surface of the air-water interface is relatively large and the return from within the water column decreases exponentially with depth. The ruffled sea surface redirects (scatters) the transmitted laser light, reducing penetration and scatters the light returned from any submerged object, blurring the image. The turbidity of the water column attenuates and further scatters the transmitted light and blurs the return image (ref. 1). The electro-optic receivers (cameras) sometimes enhance the scatter glow and produce halos around bright spots and in high frame rate systems have image ghosts that further reduce image quality that hinders identifying a submerged object.

The Navy needs to be able to clearly detect and identify sea mines deployed from the surface to as deep as possible with ALMDS while sustaining a high area search rate and maintaining a low false alarm rate. The traditional methods for optimizing current airborne LIDAR system’s capability of imaging through the air-water interface and through the water column is to create the best image possible and use a variety of image processing techniques to identify targets of interest within the return image (ref. 3). The current more mature LIDAR imaging systems use electro-optic techniques such as short laser pulses, polarization, specialized scanners, narrow field of view, range-gated receivers, and streak tube receivers to enhance the system’s ability to provide better images for processing.

This topic is seeking novel and innovative techniques to exploit the laser signal for fusion with image processing techniques to: better detect, recognize, and identify mine-like targets; reduce the false alarm rate; and to quantify results. A variety of technologies and techniques may address this issue. These may include, but are not limited to: 3D imaging, narrow band laser filters, time delay integrate (TDI), polarization (ref. 2), coherent detection (ref. 3), speckle imaging, modulated laser beams (ref. 4), non-imaging techniques, and possibly other means of discriminating the ballistic photons returned to the receiver such as time discrimination (ref. 5). Conceptual proposals should include discussions on any developmental history, technical risks, maturity levels, challenges, and applicable mitigation alternatives. In addition, the proposal should state the expected performance improvement by the proposed method of exploiting aspects of the laser signal and clearly define how the proposer intends to demonstrate and measure the improved performance. (For a simple example: We will use our LIDAR imaging system and standard software as a base line of capability in a standardized laboratory target setup. We will then use technique ‘xyz’ by modifying the laser transceiver and the software accordingly and compare results.

The intended product for Phase I will be a technical report describing innovative technology concepts and novel techniques utilizing the laser signal of an airborne LIDAR system to enhance the future naval system’s capability of detecting and identifying in-water objects and reduce the false alarm rate without sacrificing sustained area coverage rate. These novel concepts must support operations in the natural at-sea environment. Emphasis should be upon the technological feasibility to meet the Navy’s needs that include, but are not limited to, an enhanced airborne active electro-optic system with increased capabilities of detecting and identifying in-water objects, reducing the false alarm rate and possibly increasing depth penetration without sacrificing sustained area coverage rate. The desired threshold improvement of a combined increased Pd/Pc and reduced FAR is 10%. This improvement, in consultation with the Government, may be demonstrated with most any mature system, a laboratory controlled experiment, possibly a mature model or some combination thereof. A clear description of the metric used to measure performance must be included.

This topic’s intent is to provide significant increase in the ability to locate and identify mines as well as reduce false alarms using novel and innovative techniques exploiting attributes of the LIDAR signal to modify the ALMDS system. Implementing these SBIR developed and demonstrated techniques is a cost effective way to increase capability with a shorter development time. In operational mode, increased Pd/Pc and decreased FAR reduce secondary interrogation and mitigation, reducing time lines for mine countermeasures resulting in significant operational cost savings. The ability to increase Pd/Pc and/or lower FAR has the real potential to save ships and lives when hostile actions require ship presence.

PHASE I: The company will identify laser attributes for exploitation to better detect, recognize, and identify sea mine-like objects and reduce the false alarm rate while sustaining area coverage rate other than by image processing techniques alone. Determine the technical feasibility of the concept to meet Navy needs and establish if the concept can be practicably developed into a useful product for the Navy. Select experimental data to predict performance, mathematical calculations and/or modeling may be utilized to demonstrate proof of concept. The Phase I Option, if awarded, should include the initial layout and capabilities description to build the prototype in Phase II.

PHASE II: Based on the results of Phase I and Phase II Statement of Work (SOW), the small business will develop a prototype for evaluation. The Phase II SOW will cover the experimental test bed, which is the configuration of technologies and test equipment necessary to collect pertinent data, and prototype hardware and/or software for testing, and data collection for evaluation and may be used for algorithm and model development. The small business, in consultation with the Government, will define metrics for increased performance (Pd/Pc and decreased FAR) and quantify system performance improvement. The company, in consultation with the Government, will demonstrate increased performance using developed prototype hardware and/or software. The company will perform detailed analysis to ensure any materials used are appropriate for Navy applications. The company will deliver a final report documenting all findings, detailed descriptions of any hardware or software developed under this effort and recommendations for transition to Navy use.

PHASE III DUAL USE APPLICATIONS: The company will apply the knowledge gained in Phase II to build an advanced test bed which will include a configuration of technologies including the developed hardware and software prototypes to demonstrate and characterize the performance in an operationally relevant environment as defined by Navy requirements. Based on demonstrated results, the intent is the insertion of these developments into the Airborne Laser Mine Detection System. If so, it is expected that the company would support the transition of the developed technology for Navy use. Private Sector Commercial Potential: The technology and techniques developed will have direct applicability to other Government and private airborne LIDAR ocean sensing systems as well as laser interrogation systems operating through the air.

REFERENCES:

  • Josset, et al, “Lidar equation for ocean surface and subsurface,” Optics Express, Vol. 18, Issue 20, pp. 20862-20875 (2010), http://dx.doi.org/10.1364/OE.18.020862.
  • Churnside, “Polarization effects on oceanographic LIDAR,” N21 January 2008 / Vol. 16, No. 2 / OPTICS EXPRESS 1196OAA Earth System Research Laboratory.
  • Christie Kvasnik, “Contrast enhancement of underwater images with coherent optical image processors,” 10 February 1996 @ Vol. 35, No. 5 @ APPLIED OPTICS.
  • Pellen, et al, “Radio frequency modulation on an optical carrier for target detection enhancement in seawater,” Journal of Physics D: Applied Physics, 34(7):1122, 2001.
  • S. Farsiu, J. Christofferson, B. Eriksson, P. Milanfar, B. Friedlander, A. Shakouri, R. Nowak, "Statistical detection and imaging of objects hidden in turbid media using ballistic photons," Applied Optics, vol. 46, no. 23, pp. 5805–5822, Aug. 2007.

KEYWORDS: Airborne LIDAR (Light Detection and Ranging) imaging through the air-water interface; mine detection; sea mine detection; LIDAR signal processing; frequency modulated laser imaging; Streak Tube Imaging; coherent imaging

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