Physical Optic Analysis of Image Quality in Schlieren Photography

This paper will consider the schlieren system as a problem in physical optics. On the basis of such considerations the effect of aperture, focal length, light-source size, and knife-edge position on the quality of schlieren photographs will be discussed. First, the mathematical analysis of the subject will be briefly presented. On the basis of this analysis the schlieren system will be considered using a point source. The case of finite- source size then will be discussed. A brief discussion of the effect of astigmatism on the focal length of the system also will be presented.