Figure 1. Photonic cross communication patterns as a function of shell thickness.

The top row shows each droplet/shell in transmission without analyser (a–d), while photos (e–h) show the corresponding reflection images between crossed polarisers. In a/e the sphere is a droplet, in the other cases it is a shell, with thickness 40 μm (b,f), 15 μm (c,g) and 5 μm (d,h), respectively. The scale bar is 100 μm. Schematic drawings at the bottom illustrate to what extent internal reflections occur at a cholesteric helix inclined at 45° to the incidence direction, explaining why the pattern becomes less diffuse as the thickness decreases.