Reducing the diffraction artifacts while implementing a phase function on a spatial light modulator.

Spatial light modulators are often used to implement phase modulation. Since they are pixelated, the phase function is usually approximated by a regularly sampled piecewise constant function, and the periodicity of the pixel sampling generates annoying diffraction peaks. We theoretically investigate two pixelation techniques: the isophase method and a new nonperiodic method derived from the Voronoi tessellation technique.

Minimization of diffraction peaks of spatial light modulators using Voronoi diagrams.

It is possible to reduce the diffraction peaks of a Spatial Light Modulator (SLM) by breaking the periodicity of the pixels shape. We propose a theoretical investigation of a SLM that would be based on a Voronoi diagram, obtained by deforming a regular grid, and show that for a specific deformation parameter the diffraction peaks disappear and are replaced with a speckle-like diffraction halo. We also develop a simple model to determine the shape and the level of this halo.