Spatially multiplexed multi-input-multi-output optical imaging system in a turbid, turbulent atmosphere

Abstract

Active optical imaging is preferred over radio frequency counterparts due to its higher resolution, faster area search rate, and relatively easier learning and interpretation of the image by a human observer. However, in imaging through atmosphere, one should consider dispersive effects of multiple scatterings and turbulence-induced wave perturbations, which give rise to intensity fluctuations and wavefront distortions. All these phenomena broaden and distort the spatial impulse response known as the point spread function (PSF). In this paper, a spatially multiplexed multi-input-multi-output imaging system design, inspired by multispot diffuse indoor communications configuration first introduced by Yun and Kavehrad [IEEE International Conference Selected Topics in Wireless Communications (IEEE, 1992), pp 262-265], is presented. At the transmitter, a computer-generated holographic beam splitter is used to generate arrays of beamlets, providing a faster area search rate and a uniformly distributed illumination over the entire target area. Then, at the receiver, an array of photodetectors is used to collect the reflected rays. While a Monte Carlo ray-tracing algorithm developed at Pennsylvania State University, Center for Information and Communications Research (CICTR), is used to model imaging in multiple-scattering turbid media, phase screens are employed to simulate turbulence-induced wavefront distortions. Hence, a comprehensive framework is exploited that takes into account possible sources of degradation. Using this framework, system performance is analyzed under different meteorological conditions. Restoration techniques such as adaptive-optics corrections, blind deconvolution, and time gating are used to improve the contrast and enhance the sharpness and resolution of the images.

Comparative analysis of Bessel higher-order cosh- and sinh-Gaussian beams spreading through oceanic turbulence

“…There has long been a great deal of theoretical and practical interest in the propagation of laser beams over atmospheric turbulence (Hajjarian et al, 2010;Gbur et al, 2014;Benzehoua et al, 2023b;Chib et al, 2020;Nossir et al, 2021Nossir et al, , 2023a. Due to the intricacy of oceanic turbulence, laser beam propagation through it is comparatively less studied than that via atmospheric turbulence.…”

Axial intensity of Bessel higher-order cosh-Gaussian beam propagating in a turbulent atmosphere

“…In the past few years, the fascinating properties of various kinds of laser beams propagating in turbulent atmosphere have received substantial interest (Nossir et al 2012, Chib et al 2023, Boufalah et al 2018, Shishter 2023, Saad et al 2017, Gbur 2014, Zhou 2011, 2009, Yaalou et al 2019, Ez-Zariy et al 2016and Zhong et al 2011). This attraction is due to their interesting applications in many areas of science and practical engineering including free-space optical communications (Navidpour et al 2007), remote sensing (Andrews and Phillips 1998), laser radar systems (Cai et al 2008), optical imaging (Hajjarian et al 2010), lattice spectroscopy (Han 2008) and so on. The turbulent atmosphere is considered as an inhomogeneous medium where small changes in the temperature occur thus causing the fluctuations in the refractive index, which induces beam dispersion, loss of spatial coherence and random fluctuations in light intensity and phase (Andrews and Phillips 1998).…”

Comparative analysis of some laser beams spreading through oceanic turbulence

“…There has long been a great deal of theoretical and practical interest in the propagation of laser beams over atmospheric turbulence (Hajjarian et al, 2010;Gbur et al, 2014;Benzehoua et al, 2023b;Chib et al, 2020;Nossir et al, 2021Nossir et al, , 2023a. Due to the intricacy of oceanic turbulence, laser beam propagation through it is comparatively less studied than that via atmospheric turbulence.…”