Effects of temperature gradient and beam path height from heat source on phase structure and mutual coherence functions of a light beam propagating through convective air turbulence

Abstract

In this paper, we investigate the effects of different values of temperature gradient (TG) and the distance of a plane wave path from a flat heat source generating an anisotropic and non-Kolmogorov convective air turbulence medium on the phase structure function (PSF) and mutual coherence function (MCF) of the light beam propagating through the medium. The non-Kolmogorov and anisotropic convective air turbulence is created using an electrical heater with a surface size of 50 cm × 100 cm. The heater temperature is changeable from room temperature to 100 °C. The laser beam with a diameter of 20 cm passes through the turbulent medium at different distances from the heater surface. At the end of the path, the wavefront of the light beam is reconstructed using a two-channel moiré wavefront sensor. Then, the PSF and MCF are calculated, and the effects of different TGs and the different beam path heights from the heater are studied. Results show that with increasing the TG and decreasing the beam path distance from the heat source, the turbulence intensity and PSF increase, while the MCF decreases.