Ultra-High Speed Photography of Picosecond Light Pulses

Abstract

The electronically switched Kerr cell has for many years been used as a shutter in ultra-high-speed photographic systems and is capable of framing times as fast as 1 ns. A new type of optically driven Kerr cell is more than 100 times faster; it has been used to photograph laser pulses in flight. Pulses of 0.53-μm (green) light 6 ps in duration, which were derived by second harmonic generation from a mode-locked Nd: glass laser, were passed through a cell containing a colloidal dispersion. The dispersion, which is an efficient scatterer, thus rendered the light pulses visible. They were then photographed from the side by a camera positioned behind a shutter of 10-ps framing time. The shutter is similar in configuration to the conventional Kerr cell, but differs in that no electrodes are used and the medium is CS <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> rather than nitrobenzene. Peak transmission of the shutter is dependent upon the power density of the 1.06-μm pulses, and in this case is typically 5–10%.