1. Field of the Invention:
The invention generally relates to Schlieren photography and more particularly to a system and method for obtaining wide screen Schlieren photographs.
2. Description of the Prior Art
As discussed by Ralph A. Burton, Journal of the Optical Society of America, Volume 39, No. 11, November 1949, Schlieren systems of the conventional type generally possess the following limitations:
(1) the area of field is limited to the area of the lens or mirror used to focus the light, PA1 (2) any striation between the light source and the knife edge employed appears on the screen along with those being studied, and PA1 (3) the light source must approximate a point source.
Consequently, as also pointed out by Burton, a large lens, especially free from striations and correspondingly expensive, is required for large areas of field, and the choice of light source is sharply restricted.
The author of the paper aforementioned, in an effort to overcome the noted limitations without sacrificing sensitivity, such as occurs in the use of shadowgraphic methods, proposes the use of a method wherein a negative grid is rididly mounted in a camera for photographing striations illuminated by light propagated through a positive grid.
While such a method may satisfy the requirements of experimental work, it readily should be apparent that such a method and/or the system employed in performing the method, simply does not lend itself to practical application because of the requirements that a specialized camera be constructed to include therein a negative grid.
It should therefore be apparent that there currently exists a need for a practical and economic system through a use of which it is possible to obtain a wide screen Schlieren photograph of fields of view substantially unlimited in size employing simple and economic photographic equipment and techniques. Therefore, it is the general purpose of the instant invention to provide an improved system and method for obtaining wide screen Schlieren photographs without sacrificing desired resolution.