Analysis of beam steering with decentered microlens arrays

Abstract

A cascade of microlens arrays that are decentered with respect to each other is one potential method for beam steering; the magnitude of the steering depends on the amount of decenter. A simple, heuristic geometric analysis is presented that suggests that the output of the arrays is analogous to a blazed grating. The periodic nature of the exiting wavefront restricts allowed steering angles to values determined by the element-to-element spacing of the microlens arrays. The efficiency of steering into a desired mode of the grating is determined both by the amount of decenter of the microlens arrays and the fill factor at the output of the arrays. It is shown that maximum fill factor is desired, which can be achieved through the addition of a microlens array that acts like a field lens. Assumptions are identified under which the grating nature of the output can be predicted using Fresnel diffraction theory. Future work in the area of microlens beam steering is suggested.