High spatial resolution schlieren photography.

Some geometrical optical considerations for attaining spatial resolution of about 100 microM in a photographic schlieren experiment are presented. The topics of astigmatism, coma, and spherical aberration are considered briefly. Special emphasis is directed to diffraction effects in a single-mirror schlieren instrument. A method for estimating the size of limiting apertures in the knife-edge plane to allow a particular spatial resolution, compromised vs photographic sensitivity, is reported. A sample application for photographing the schlieren effects in a small spark discharge is included.