Hot spot detection in a focused 10.6μm laser beam using silver halide films

Abstract
A simple new photographic technique is used to measure intensity distribution in the focal spot of a CO2 laser used for laser-matter interaction studies. Little-known properties of silver halide films exposed to intense electric fields at frequencies well below the visible are used to reveal inhomogeneities in the incident infrared beam that are important in the interpretation of nonlinear effects such as filamentation in the laser-produced plasma.