A Galvo Mirror Streak Camera for Imaging High-Speed Rocket Sleds

We propose to develop a high-speed digital streak camera to record high-resolution focused schlieren images of rocket sleds and their test articles. Streak images will be recorded by using a Galvo motor to rotate a relay mirror that sweeps an image of the entrance slit across the face of a large format CCD camera. The Galvo mirror system can be triggered externally by the rocket sled as it travels down the track. This gives it an advantage over other rotating systems such as those with spinning polygonal mirrors. In addition, the number of lines exposed simultaneously can be controlled by adjusting the entrance slit, which is a necessary feature for focusing schlieren using the scanning method. In Phase 1, we developed an optical model of the system, tested the speed and linearity of Galvo motors, and built a breadboard system, which we used to capture an image of moving objects. In Phase 2, we will seek to improve the optical model and build a full-scale prototype using commercially available lenses, sensors, and Galvo motors. The proposed camera will be especially suited for scanning focusing schlieren, a technique for visualizing shock waves by observing distortions in light-dark edges in the background.