A Kerr-Cell Camera with Synchronized Light Source for Millimicrosecond Reflected Light Photography

Abstract

Certain events which can be studied photographically have associated with them a high degree of self-luminosity. To study the surface phenomena of these events, a high resolution, 50-mμsec Kerr cell camera and synchronized light source have been developed. A three-polarizer Kerr cell, having an optical transmission ratio of better than 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> :1, is employed to prevent undesired exposure of the film due to the relatively long duration light from the self-luminosity which would bleed through a standard two-polarizer cell when closed. The cell is activated by means of a transmission line pulse generator capable of producing a 60,000-v square-wave pulse. — The light source consists of three commercial xenon filled flash-tubes which are energized by means of a hydrogen thyratron pulser. A transmission line network is incorporated into the flashtube pulser to produce a high-voltage synchronizing pulse when the flashtubes are ignited. This pulse is applied, via a length of delay cable, to the trigger electrode, of the spark-gap switch which activates the Kerr cell shutter. Synchronization is accomplished with an accuracy of 5 μsec. The camera has been used to photograph the early stages of electrically exploded metal foils, and hypervelocity impacts in a ballistics range.