Improved Large-Field Focusing Schlieren System

Abstract

System used to examine complicated two- and three-dimensional flows. High-brightness large-field focusing schlieren system incorporates Fresnel lens instead of glass diffuser. In system with large field of view, image may also be very large. Relay optical subsystem minifies large image while retaining all of light. Facilities candidates for use of focusing schlieren include low-speed wind and water tunnels. Heated or cooled flow tracers or injected low- or high-density tracers used to make flows visible for photographic recording.