Stereoscopic camera setup. Due to spatial restrictions, the cameras are aligned non-orthogonal. The field of view in this lens configuration is . In this setup, gravity points to the negative z-direction.
(a) Image at showing all particles of an 2D laser sheath. Thewave crests of the downward propagating wave can be identified. The vertical slice indicates the image region that is used to produce a space-time diagram for density analysis. (b) Image at shows only the fluorescent particles. No separation or special arrangement of the marker particles is observed. For clarity, the image has been processed for enhanced visibility of the particles.
Comparison of the oscillation amplitudes IW retrieved from the image intensity modulation (black line) and the single particle oscillation amplitude zp of the tracer particles (triangles). The straight gray line is a linear fit to the zp -data.
(a) Space-time diagram of the density wave measurement. The phase velocity equals the slope of the wave crest. (b) Space-time diagram of the single particle measurement. The propagation of the phase of maximum vertical excursion is used to determine the phase velocity. (c) Phase velocities computed via space-time diagram for the density analysis as well as the single particle analysis.
Plot of reconstructed trajectories that are longer than . The x- y-projection at the bottom shows a significant particle movement that accompanies the major z-plane oscillation.
Velocity distribution of all reconstructed trajectories. While the z-movement reflects a damped oscillation, the x- and y-components show probably a relatively high impact of inter-dust collisions that would lead to a Maxwell-distribution.
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