Development of calibration for quantitative streak schlieren

Individually, streak imaging has a well documented history of allowing visualization of very high speed phenomena, and schlieren allows for precise, quantifiable imaging of refractive disturbances within a flow. Here, a combined approach referred to as streak schlieren is implemented by visualizing refractions along a single row of pixels coincident with a background light cutoff and subsequent images are compiled into a single output. The output image appears similar to traditional schlieren taken as a single exposure. This setup is relatively simple and only requires a high speed camera and a light source with a light-to-dark edge called a cutoff which is advantageous for large-scale field experiments. Previous implementations of this technique have provided high quality imagery, but quantification of the magnitude of light refraction has not been done. This work aims to quantify a calibration by mapping pixel intensity through known refraction angles created by a simple lens. This intensity-to-refraction relationship is then applied to experimentally recorded streak schlieren images of supersonic projectiles. Ultimately, the quantified refraction is related to air density through the Gladstone-Dale Law.