Endoscopic optical coherence tomography with new MEMS mirror - Electronics Letters

Introduction: Optical coherence tomography (OCT) is a new optical imaging technique that can provide cross-sectional images of biological tissue, highly desirable for imaging diagnosis of superficial lesions [1]. OCT can delineate tissue micro morphology, holding the potential for non-invasive optical biopsy [1, 2]. In recent years, the development of real-time, high-performance, reliable and low-cost OCT catheters and endoscopes has attracted more attention for future clinical applications [1, 2]. To miniaturise lateral scanning probes to fit into slender endoscopes, various attempts of transverse laser scanning techniques have been employed including a rotary fibreoptic joint connected to a 90 deflecting micro prism or a small galvanometric plate swinging the distal fibre tip [1, 2]. The rotary fibre joint is more suitable to image the circumference of intraluminal tracts and the galvo swinger has a limited range (<2 mm) for transverse scanning [1, 2]. Microelectromechanical systems (MEMS) have found enormous applications in biomedical areas because of their small sizes, low consuming energy, nominal forces and flexibility. A recent report of endoscopic OCT (EOCT) utilising a MEMS mirror for endoscopic laser scanning has been proposed by the authors, showing great promise [3]. However, buckling of the employed bimorph mesh structure causes a 10 discontinuity in the angular actuation curve, severely limiting the usable range of the transverse laser scanning. In this Letter, we present an improved EOCT using a modified single-crystalline silicon (SCS) micromirror which completely eliminates buckling and allows transverse scanning over 37 . Preliminary results based on animal studies are presented.