Cranz-Schardin camera with a large working distance for the observation of small scale high-speed flows

The Cranz-Schardin camera utilizes a Q-switched Nd:YAG laser and four single CCD cameras. Light pulse energy in the range of 25 mJ and pulse duration of about 5 ns is provided by the laser. The laser light is converted to incoherent light by Rhodamine-B fluorescence dye in a cuvette. The laser beam coherence is intentionally broken in order to avoid speckle. Four light fibers collect the fluorescence light and are used for illumination. Different light fiber lengths enable a delay of illumination between consecutive images. The chosen interframe time is 25 ns, corresponding to 40 x 106 frames per second. Exemplarily, the camera is applied to observe the bow shock in front of a water jet, propagating in air at supersonic speed. The initial phase of the formation of a jet structure is recorded. (C) 2011 American Institute of Physics. [doi:10.1063/1.3624692]