An All Electronic, Adaptive, Focusing Schlieren System for Flight Research

Visualization of turbulence and shock phenomena by schlieren imaging has led to important discoveries in aerodynamics, and there has been much interest in applying schlieren methods for aircraft in flight. The goal of this project is to develop the next generation of Schlieren for Aircraft in Flight (SAF) systems. SAF is a technique for obtaining schlieren images of aircraft as they fly past the edge of the sun. In its original form, images were recorded with a time delay and integration (TDI) camera using slit masks that conformed to the edge of the sun. Problems arise if the cutoff mask is not precisely aligned with edge of the sun, or if the TDI camera is not aligned and synchronized with the aircraft flight path. These problems can be solved using the synthetic TDI method, where the aircraft transit of the sun is recorded on high-speed video, and then the TDI process is carried out computationally using programmable masks. Synthetic, TDI-based SAF systems are less sensitive to movement of the observation platform, and can be used with non-cooperative targets whose flight paths and velocities are not known in advance.