A simplified discussion of the fundamental principles underlying the schlieren method is presented, and the design and construction of the schlieren apparatus built in connection with this investigation is described. This equipment utilizes a B-H6 mercury-vapor lamp as the source and employs two first-surface parabolic mirrors with a parallel light path between them.
Keagy, Walter R., H. H. Ellis, and W. T. Reid, Schlieren Techniques for the Quantitative Study of Gas Mixing. Santa Monica, CA: RAND Corporation, 1949. https://www.rand.org/pubs/reports/R164.html.
Keagy, Walter R., H. H. Ellis, and W. T. Reid, Schlieren Techniques for the Quantitative Study of Gas Mixing, RAND Corporation, R-164, 1949. As of December 7, 2023: https://www.rand.org/pubs/reports/R164.html