Investigating the effect of heat disturbance on the spatiotemporal distribution of the atmospheric coherence length based on moiré deflectometry

The atmospheric coherence length is a key parameter for quantifying the intensity of atmospheric motion, and understanding its variation characteristics is of considerable practical importance. In this paper, phase-based moiré deflectometry is employed to investigate the influence of heat disturbance on the temporal and spatial distributions of the atmospheric coherence length. First, the theoretical relationship among phase, deflection angle, and atmospheric coherence length is refined. Next, numerical simulations indicate that the average relative error of the theoretical model is 2.8% in both the temporal and spatial distributions, which validates the feasibility and reliability of our proposed approach. Then, two sets of experiments are implemented without and with heat disturbance, respectively. Each set lasts for one hour, during which 3600 frames of moiré fringes are acquired. Finally, the temporal and spatial distributions of atmospheric coherence length are characterized by the optimized theoretical model. The comparison of results reveals that the atmospheric coherence length exhibits a strong negative correlation with temperature fluctuation, decreasing by 95.2% as the temperature rises by 42.8°C. In a word, our work further extends the application of moiré deflectometry and provides some valuable insights for future atmospheric turbulence research.