Vertical comb-drive microscanner with 4x4 array of micromirrors for phase-shifting Mirau microinterferometry

Abstract

In this paper, we present construction, fabrication and characterization of an electrostatic MOEMS vertical microscanner for generation of an optical phase shift in array-type interferometric microsystems. The microscanner employs asymmetric comb-drives for a vertical displacement of a large 4x4 array of reference micromirrors and for in-situ position sensing. The device is designed to be fully compatible with Mirau configuration and with vertical integration strategy. This enables further integration of the device within an "active" multi-channel Mirau micro-interferometer and implementation of the phase shifting interferometry (PSI) technique for imaging applications. The combination of micro-interferometer and PSI is particularly interesting in the swept-source optical coherence tomography, since it allows not only strong size reduction of a system but also improvement of its performance (sensitivity, removal of the image artefacts). The technology of device is based on double-side DRIE of SOI wafer and vapor HF releasing of the suspended platform. In the static mode, the device provides vertical displacement of micromirrors up to 2.8µm (0 -40V), whereas at resonance (fo=500 Hz), it reaches 0.7 µm for only 1VDC+1VAC. In both operation modes, the measured displacement is much more than required for PSI implementation (352nm peak-to-peak). The presented device is a key component of array-type Mirau micro-interferometer that enables the construction of portable, low-cost interferometric systems, e.g. for in vivo medical diagnostics.

Micro Aspheric Convex Lenses Fabricated by Precise Scraping

“…Microlenses have also developed more specific and novel applications. The microlenses are important components used in Mirau interferometers [ 10 ], scanners [ 11 , 12 ], integrated photonic platform [ 13 ], vertical-cavity surface-emitting laser beam shaping [ 14 ], telecommunications [ 15 ], data storage [ 16 ], biodetection [ 17 ], etc. Due to their important role in MOEMSs, microlenses have recently been more widely discussed.…”

Microlens Array Fabrication by Using a Microshaper

“…Moreover, recent developments show microlenses have more specific and novel applications. The micro lenses can be used in Mirau interferometers [9], imaging scanners [10], integrated photonic platform [11], vertical cavity surface emitting lasers beam shaping [12], etc. Apparently, microlenses play more important role in MOEMSs.…”