A high-resolution two-dimensional imaging velocimeter

Abstract

Velocityinterferometers are typically used to measurevelocities of surfaces at a single point or along an imaged line as a function of time. We describe an optical arrangement that enables high-resolution measurements of the two-dimensional velocity field across a shock front or shocked interface. The technique is employed to measure microscopic fluctuations in shock fronts that have passed through materials being considered as ablators for indirect-drive inertial confinement fusion. With picosecond time resolution the instrument captures velocity modes with wavelengths as short as 2.5 μ m at a resolution of ∼ 10 m / s rms on velocity fields averaging many km/s over an 800 μ m field of view.