An Improved Schlieren Apparatus Employing Multiple Slit‐Gratings

In the schlieren apparatus described in the following, the conventional knife‐edge elements are replaced by multiple slit‐gratings. The main advantage gained by this design is the fact that larger‐sized working fields can be achieved with an objective lens of given aperture. Also, in some cases, greater intensity of image illumination is obtained, and usually the over‐all length of the system is reduced.