Varifocal MEMS mirrors for high-speed axial focus scanning: a review.

Recent advances brought the performance of MEMS-based varifocal mirrors to levels comparable to conventional ultra-high-speed focusing devices. Varifocal mirrors are becoming capable of high axial resolution exceeding 300 resolvable planes, can achieve microsecond response times, continuous operation above several hundred kHz, and can be designed to combine focusing with lateral steering in a single-chip device. This survey summarizes the past 50 years of scientific progress in varifocal MEMS mirrors, providing the most comprehensive study in this field to date.

Spatial and directional contrast dependence in Lissajous-scanning projection systems.

Scanning-based image formation fundamentally differs from its classical lens-based counterpart. Therefore, established classical performance evaluation methods fail to determine the theoretical limitations of scanning-based optical systems. We developed a simulation framework and a novel performance evaluation process to evaluate the achievable contrast in scanning systems.

Aperture-coded confocal profilometry.

This Letter introduces a novel principle to the confocal profilometry for simultaneous measurement of surface position and tilt. The principle relies on an angle-dependent coding of the illumination of the surface-under-test, achieved by dividing the pupil into several subapertures. The reflected light is decoded to perform an angle-resolved analysis by measuring the intensity contributions of each individual subaperture.