The aero-optic effect is a major topic of interest due to its relevance in various applications, which involve interactions between propagated laser beams and an inhomogeneous medium (such as the variable-density flow fields, which form within compressible boundary and free shear layers). By creating aero-optical aberrations, this phenomena results in significant reduction of optical system performance and yield lower peak energy of the light intensity and wider energy distribution around the central spot of the beam. The broad range of industrial applications, where such an effect is observed, includes missiles with optical seekers, airborne telescopes, airborne free-space communication systems, and high-powered lasers on combat air vehicles.
In the present research, quantitative and qualitative methods are devised in order to characterize the aero-optic effect in the mixing layers of a compressible free jet. Towards visualization of the mixing layer between the ambient and the free jet, two optical measurement techniques (Shadowgraph and Schlieren) are used in a qualitative manner. The intensity of the laser, along with its distribution, is evaluated and the deviations of the initially collimated beam are analysed. Enhanced understanding of the laser beam distortions associated with a compressible jet contributes to the pool of efforts towards developing an optimal technique which can form an undistorted wave front.