Free-space micro-graphics with electrically driven levitated light scatterers.

The levitation of optical scatterers provides a new means to develop free-space volumetric displays. The principle is to illuminate a levitating particle displaced at high velocity in three dimensions (3D) to create images based on the persistence of vision (POV). Light scattered by the particle can be observed all around the volumetric display and, therefore, provides a true 3D image that does not rely on interference effects and remains insensitive to the angle of observation. The challenge is to control with high accuracy and at high speed the trajectory of the particle in 3D. Here we use electrically driven planar Paul traps (PPTs) to control the trajectory of electrically charged particles. A single gold particle colloid is manipulated in 3D through AC and DC electrical voltages applied to a PPT. The electric voltages can be modulated at high frequencies (150 kHz) and allow for a high-speed displacement of particles without moving any other system component. The optical scattering of the particle in levitation yields free-space images that are imaged with conventional optics. The trajectory of the particle is entirely encoded in the electric voltage and driven through stationary planar electrodes. We show in this Letter the proof-of-concept for the generation of 3D free-space graphics with a single electrically scanned particle.