The effect of turbulent medium on image resolution

The degrading effect that a laser beam may be subjected to as it propagates through a turbulent medium was investigated. To accomplish this, the line spread function (LSF) was measured. A computer program was utilized to perform a Fourier transform on the LSF to give the modulation transfer function (MTF) of turbulence. The measurement of the LSF was accomplished by sweeping the focal spot on a coherent light source across a slit that was narrower than the focal spot. The detected intensity of the light, as it traverses the slit, yielded an integrated slice of the Airy disk, the LSF of the beam. A measure of beam degradation was made by comparing the undistorted LSF to the distorted LSF. Beam quality was then expressed using various methods. The LSF was used to find the MTF of the turbulent medium. The MTF is utilized to analyze the effect that the turbulent medium has on resolution. Analytical work has also been done to compare experimental results with theory.<>