Active Camouflage of Underwater Assets (ACUA)

Abstract

LONG-TERM GOALSThe long-term goals of this research are to develop the control methodology for active cloaking of underwater assets and the initial hardware concepts to test the proposed cloaking approach. This work is a natural extension of ONR Project N00014-02-1-0211 (Optical Variability and Bottom Classification in Turbid Waters: HyMOM Predictions of the Light Field in Ports and Beneath Ship Hulls) where the perceptibility of underwater assets was modeled. OBJECTIVESThe initial objective of this work is to extend the existing 3-D Hybrid Marine Optical Model (HyMOM) (Reinersman and Carder 2004;Carder et al, 2005; Carder and Reinersman, 2007) to determine the three-dimensional light structure of representative marine environments in order to calculate the character of the radiance field needed to remove asset contrast with the background. A secondary objective is to develop a practical method to provide the additional radiance necessary to accomplish this task and to make the asset "self-aware" of its background contrast. Only in this manner will the asset be able to change radiance fields with environmental conditions. APPROACHOur approach rests on the foundation of our knowledge of how light interacts with water and the bottom and how it is spectrally and spatially transformed before it can become water-leaving radiance L u . The mechanism for actively controlling submarine "cloaking" will be to use our 3-D Hybrid Marine Optical Model (HyMOM) to understand the spatial structure (e.g. Q factor, etc.) of various natural waters and a measurement methodology to control the brightness of light sources strategically placed to minimize contrast. The importance of this predictive knowledge is significant since L u is the background from which a submerged object needs to be distinguished by an in-water or air-borne sensor, and the amount of infilling of upwelling radiance occluded by a submersible (e.g. AUV; SEAL Delivery Vehicle) will need to be added to that fraction of down-welling irradiance reflected up from the vehicle. Armed with that predictive knowledge, we propose to demonstrate that hybrid, electrooptic "chromaphotophores", that is, spectral-photophores can be utilized to provide active cloaking, and that the asset can be made "self aware" of its contrast relative to the background. HyMOM will be 1