Schematics of the dusty plasma experiment. 1: Powered electrode, 2: illuminating laser (200 mW @ 532 nm), 3: grounded electrode, 4: Lytro camera, 5: dust particle cluster, 6: f = 174 mm convex lens to shorten the working distance.
Schematics of the optical configuration of the light field camera (not to scale). 1: World plane, 2: objective lens, 3: micro-lens array, 4: CMOS sensor array, W: working distance, F: distance between the objective lens and the image plane. Light rays from different world plane points fall on different micro-lenses (rays with solid vs. dashed lines), while rays originating from the same points of the world plane and passing the objective lens at different points (e.g., the rays shown by solid lines) fall on different sensor pixels behind a given micro-lens.
Largely magnified piece of the (inverted and enhanced contrast) raw image showing a slightly defocused particle. The triangular lattice structure of the micro lens array is apparent also in the background.
Inverted and enhanced contrast images computed for α = 0.987, 1.0, and 1.013 (from top to bottom) from a single exposure. The α refocusing parameter is directly proportional to the depth coordinate.
Sub-aperture (enhanced field of depth) image.
Examples of B i (α) brightness functions for four representative particles.
Top view of the dust particle cloud projected from the full 3D coordinate set.
Overlay of the sub-aperture image, apparent (x, y) coordinates (blue crosses), and the tilted 3D particle coordinate projections (red crosses).
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