Effects of Atmospheric Turbulence on Optical Instrumentation

The results of research on optical turbulence at White Sands Missile Range are presented. It has been shown that elevating camera stations 33 feet above ground level can yield nearly a threefold increase in optical resolution during periods of atmospheric turbulence. Early research postulated the existence of thermal-induced air lenses as the cause of optical-turbulence effects. Recent research has shown that air lenses can account for most of the observed effects. The ``prism´´ concept of turbulence appears to be unnecessary for explaining turbulence-induced image motion. The dependence of the optical effects of turbulence upon exposure time and aperture size are discussed qualitatively. The source of optical turbulence in the atmosphere and a method of measuring the turbulence-generating potential of various terrain surfaces are described on the basis of micrometeorology. This research has been limited to an investigation of optical turbulence during the period from sunrise to sunset. However, many of the results apply to the nighttime turbulence encountered by astronomers.