Multiple beam steering using dynamic zone plates on a micromirror array

Abstract

Three dimensional laser beam steering of focal position has been demonstrated using a single optical device – a DMD micro-mirror array. Laser beam focus position is controlled using dynamically adjustable zone plates. These zone plates take the form of elliptical Fresnel zone plates or other variations such as binary Gabor zone plates. Active beam pointing and control can be realised without the need for a pair of galvanometer mirrors and a focusing lens. Focussing efficiencies into an off-axis diffraction order of a few percent are typically seen and continuity between neighbouring orders increase the effective field of regard. Writing multiple zone plate patterns to the DMD enables multiple focussed spots to be generated and controlled independently.