The Kranz – Chardin method (a high-frequency spark chamber of the Kranz – Chardin method) is a method of high-speed filming of fast-moving processes. It is named after the creators of the method and equipment - German ballistics Karl Kranz and Hubert Shardin . Created in 1929 by Krantz and Shardin, a high-frequency spark camera ( German: Funkenzeitlupenkamera ) made it possible to obtain 24 images at a shooting frequency of up to 5 MHz.
With the help of this specialized camera, clear optical images were obtained for the first time on a stationary photographic plate when the event was illuminated by separate spark discharges distributed in space. Thus, for the first time it became possible to observe dynamic processes, for example, studying the trajectory of a bullet’s flight, processes of penetrating armor, detonation of explosives and the destruction of brittle materials, the beginning of a systematic instrumental study of which was laid by the Air Force Technical Academy in the late 1930s [1] [ 2] . A high-frequency spark chamber is still used today.
Content
Principle of Operation
The camera consists, on the one hand, of a spark head with 24 spark gaps, generating 24 discharges and serving as a pulsed light source, and, on the other hand, of a camera with 24 lenses (twenty-four cameras per exposure). The spark head and camera are located opposite each other. The light beam from the spark discharge is directed to the lens, with the help of which, after falling onto the object, it is focused exactly into the camera.
The generation of spark discharges that follow very quickly occurs with a time shift, with each discharge providing one picture. Thus, a series of 24 shots is obtained. A very short exposure time and precise adjustment of the intervals between spark discharges make it possible to obtain extremely sharp images at a shooting frequency of up to 5 MHz (5 million frames per second). So in one of the experiments conducted by the Institute of Ballistics in 1939, the processes of detonation development were studied when the charge of tetrile undermining two grams. The process was recorded using a Kranz-Shardin spark chamber with a frequency of 220 thousand frames / s.
On the whole, the creation of such a tool for registering fast-moving processes laid the foundation for the study of a number of dynamic processes directly related to ballistics and having military applications, which, ultimately, led to the creation of promising weapons models.
Cameras of this type are currently used. The advantage of cameras of this type is the high resolution of optical recording on a photographic plate (10 GB as of the end of the 2000s), along with a relatively high shooting frequency of several MHz.
See also
Kerr cell high speed camera
Notes
- ↑ Hubert Schardin, Der Verfahren der Funkenkinematographie , In: Beitrage zur Ballistik und Technische Physik . Leipzig 1938, S. 139
- ↑ Richard Emil Kutterer: Ballistik , Braunschweig: F. Vieweg, 1959, S. 90-123
Links
- Joachim Holzfuss: Analoge und Digitale Hochgeschwindigkeitskinematographie . PDF Online
- H. Maecker: Über die Bewegung gestoßener Körper . In: Naturwissenschaften . Band 40, Nr. 20, Springer, Berlin / Heidelberg 1953, S. 521522; DOI : 10.1007 / BF00628920
- Historische Aufnahmen mit dem Cranz-Schardin-Verfahren (link not available)
- Beitrag bei www.filmarchive
- Prinzip der Funkenzeitlupe mit Abbildung (Universität Würzburg)
Literature
- Joachim Holzfuss: Analoge und Digitale Hochgeschwindigkeitskinematographie . PDF Online
- H. Maecker: Über die Bewegung gestoßener Körper . In: Naturwissenschaften . Band 40, Nr. 20, Springer, Berlin / Heidelberg 1953, S. 521522; DOI : 10.1007 / BF00628920