Schlieren Method Some History Robert Hooke Discovered Schlieren

Schlieren Method: Some History • Robert Hooke • Discovered “Schlieren Method” 1665 • Used two candles and a convex lens • Low quality instruments OK! • August Toepler • Used conventional Schlieren System • Trying to find impurities in lenses • More complicated system, better equipment Although Schlieren looks and sounds like a German name, it is not the name of a scientist. The Schlieren method originated in Schlieren, Switzerland, and it has become an adjective describing the method itself.

Schlieren Method: How It Works • Produces image of an object • Deflection of light by refractive index gradient • Converging Lens • Knife Edge Blocks unwanted light • Lens places image on screen Simple Schlieren Setup

Schlieren Optics • Point source of light illuminates an object or image. • Image is focused on a knife edge. • When index of refraction of the medium surrounding the object or image changes – Image focal point will be perturbed – Diffracted rays will interfere Perturbed focal point

References • http: //en. wikipedia. org/wiki/Schlieren • http: //www. abb. com/global/ • http: //www. lav. ethz. ch/research/projects/actual_projects/Experiment als/EHCCI/index • http: //www. rit. edu/~andpph/photofile-b/usch • Hect, Eugene and Alfred Zajac. Optics. 3 rd ed. New York: Addison Wesley Publishing Company, 1997. • C: Documents and SettingsAdvanced. Lab-IIOpticsNewport. Optics2004 S-Newport-Burns-etal. ppt