Microlenses with annular amplitude and phase masks

We present theoretical and experimental investigations of microlenses with both amplitude and phase masks. The light field in the focal region has been measured with a high resolution Mach-Zehnder interferometer with z-scan. The experimental results show good agreement with simulation. We show that we can obtain effects as diverse as squeezing or expansion in longitudinal and lateral directions, focal point splitting and focal shift. These effects may be of interest for applications such as Shack-Hartmann wavefront sensing, integral imaging, optical tweezers and confocal microscopy.