Computational ghost imaging and ghost diffraction in turbulent ocean

Abstract Computational ghost imaging (CGI) is an indirect single-pixel imaging method that can retrieve an image of an object in a hostile environment by using a correlation of intensity fluctuations. Based on the theory of ghost imaging (GI) and using the spatial power spectrum of the refractive index of ocean water, we develop a unified imaging formula for the CGI and computational ghost diffraction (CGD) operating through oceanic turbulence, and numerically analyse how the image quality can be affected by oceanic turbulence including the rate of dissipation of turbulent kinetic energy per unit mass of fluid, the rate of dissipation of mean-square temperature, and the relative strength of temperature salinity fluctuations, as well as the propagation distance. To quantitatively evaluate the quality of the retrieved images, the relative mean square error is employed in the CGI system. Our results show that the quality of the CGI scheme operating through oceanic turbulence is closely related to the propagation distance. When the propagation distance is fixed to be relatively small, we can effectively obtain a sharp image in the case of strong turbulence, and the turbulence influence can be neglected. Meanwhile the turbulence effects become more serious in the CGI system with increasing propagation distance. Besides, we find the CGI system is more robust against oceanic turbulence than the CGD system.