Figure 1
From: Conical Refraction Bottle Beams for Entrapment of Absorbing Droplets

Generation of optical bottle beams by conical refraction: (a) Circular split-up of different polarisation angles of a circularly polarised beam, (b) opening the top and (c) bottom of the bottle beam by changing the polarisation state of the incident light field (indicated by white arrows). The diameter of the CR ring needs to be adapted to the droplet size (compare Fig. 3).