The effect of thin turbulent shear layers on the optical quality of imaging systems

A modified C141 transport was outfitted with a 91.5-cm reflector telescope designed to view objects radiating outside the visible window in the infrared range from 1 micron to 1000 microns. The telescope is situated in a cavity which is operated open port. Spoilers were designed which reduce turbulence-induced excitation of the cavity. The aircraft was designed to operate at altitudes up to 15 km to significantly reduce the effect of the H2O and CO2. Furthermore, the optically degrading influence of the large-scale atmospheric turbulence on land-based telescopes is replaced by the effect of the turbulent shear layer resulting from the spoiler upstream of the cavity. A mathematical model was established to describe the effect of turbulent shear layers on imaging systems and to examine the parameters of interest relevant to potential wind-tunnel experimentation.