Setting Up Your Own Simple Schlieren and Shadowgraph System

In some sense this is a stand-alone Chapter. It describes a modest schlieren system that should be within the financial and technical means of just about anyone who has read this far. Variations of this optical system were built as science-fair projects by several generations (see Stong [344,385,386,532]), and that is, in fact, how your author got his humble start in schlieren imaging at age 16 [385,532]. The optical setup suffices for both schlieren and shadowgraphy, the latter by either direct parallel-light or in the “focused” shadowgraph mode. It deliberately evokes Scientific American magazine's Amateur Scientist section in its heyday, when C. L. Stong’s text and Roger Hayward's splendid artwork helped convince amateurs that it was both fascinating and fun to build the simple — and sometimes not-so-simple — apparatus described there. The same schlieren system is now used as a learning tool by students of the Penn State Gas Dynamics Laboratory. So, despite the science-fair flavor, professionals who are new to schlieren and shadowgraph techniques can equally benefit from this exercise.