Research on the effect of thermal disturbance on temporal and spatial distributions of refractive index structure constant by moiré deflection tomography

Changes in environmental conditions will directly influence the intensity of turbulent motion, and a random variation of the refractive index ensues. In this paper, a phase-based moiré deflection tomography is used to explore the effect of thermal disturbance on the spatial and temporal distributions of the refractive index structure constant, which is achieved after passing parallel beams through the indoor convective air turbulence. Initially, experiments are conducted for 60 min under two conditions: with and without the thermal flow field. In each set, 3600 frames of moiré fringes are successfully captured. And then, the temporal and spatial distributions of the refractive index structure constant are obtained. Subsequently, its regularities of distribution are analyzed in combination with the reconstructed temperature of the thermal flow field. Finally, the finding reveals a strong positive correlation between the refractive index structure constant and temperature fluctuations, in particular, the pronounced influence of thermal disturbance leads to a rapid exponential rise in its values. In a word, the related results could provide valuable insights for studying atmospheric optical communication and laser detection.