A study on the limits of imaging capability due to water scattering effects in underwater ghost imaging

Abstract

Underwater ghost imaging is an effective method of underwater detection. In this research, theoretical and experimental investigations were conducted on underwater ghost imaging, combining the underwater optical field transmission model with the inherent optical parameters of a water body. In addition, the Wells model and the approximate Sahu-Shanmugam(S-S) scattering phase function were used to create a model for underwater optical transmission. The second-order Glauber function of the optical field was then employed to analyze the scattering field degradation during the transmission process. The simulation and experimental results verified that the proposed underwater model could better reveal the degrading effect of a water body on ghost imaging. A further series of experiments comparing underwater ghost imaging at different detection distances was also conducted. Cooperative targets were imaged up to 65.2 m (9.3 attenuation lengths (ALs), attenuation coefficient c = 0.1426 m-1, and scattering coefficient b = 0.052 m-1) and non-cooperative targets up to 41.2 m (6.4 ALs, c = 0.1569 m-1, and b = 0.081 m-1). From equating the experimental maximum imaged AL for cooperative targets with Jerlov-I water (c = 0.048 m-1 and b = 0.002 m-1), the system has the maximum imaging distance of 193.7 m.