Figure 1

Schematic of a light droplet illumination in contrast with a standard Gaussian configuration (a). A Gaussian beam can illuminate a single voxel at different depths in a sample volume through lenses of different focal lengths. In turn, light droplets are periodic structures which enable a localised illumination along the whole optical axis. Optical setup diagram (b). A binary mask (c) displaying two concentric annuli of different diameters is generated on the SLM. This operates in amplitude mode through a λ/2 plate and a crossed analyser (A). The resulting field distribution gives rise to two co-propagating Bessel beams of different k-vectors (d). The beams are recorded through a 20x objective lens and a CCD camera. Transverse intensity distributions at three different positions along a period of Λ _z  = 4 mm (e).