Scanning mirror for optical coherence tomography using an electrostatic MEMS actuator

This paper describes a compact micromirror device for use in the scanning arm of an optical coherence tomography (OCT) system using an electrostatic micromachine (MEMS) actuator. Optical deflections of these MEMS mirror devices range from 18 degrees at low frequencies to more than 140 degrees near the resonant frequencies of the structures (30-60 Hz). These devices consist of gold plated silicon mirrors resting on polyimide tables that tilt on 3 μm thick torsion hinges when pulled on by the micromachine (MEMS) actuator, the integrated force array (IFA). The IFA is a thin (2.2 μm) polyimide membrane consisting of hundreds of thousands of micron scale deformable capacitors, and contracts with strains up to 20% and forces up to 13 dynes. The support structures, hinges, and actuators are fabricated from polyimide on silicon wafers using photolithography, leading to the possibility for integrated fabrication of the devices resulting in highly repeatable and inexpensive scanning arms. These devices were inserted into the scanning arm of a high speed OCT imaging system to acquire in vitro images of porcine eye and colon tissue and in vivo images of human skin at frame rates from 4-8 Hz.

Duke Scholars

Author Stephen William Smith Biomedical Engineering