Scanning and Tunable Micro-Optics for Endoscopic Optical Coherence Tomography

The design, fabrication, and integration of micro-optical components for beam focus and steering are demonstrated in an endoscopic optical coherence tomography (OCT) system. The relevant components, a membrane-based microfluidic tunable microlens and an electrostatic 2-D scanning micromirror, are fabricated using silicon and polymer-based microelectromechanical system technologies. All components are assembled inside a 4.5 μm diameter probe. The design of the optical system, including substantiation of the need for focal length tunability, is presented, along with performance data of an OCT system using these components. A lateral resolution of about 13 μm is achieved, an improvement over fixed-focal length probes. Due to the miniaturization of the measurement head achievable using this optical microsystem, use in conventional endoscopes is possible.