This project aims at the development of a novel two-dimensional optical scanner to enable endoscopic forward-looking 3D Optical Coherence Tomography. Endoscopic OCT (EOCT) provides the potential for minimally invasive diagnostics by """"""""optical biopsy"""""""" consisting of tomographic sub-surface imaging in situ in a variety of tissues. Catheter-based EOCT is performed by delivering the light beam through a catheter placed inside an endoscope. Catheter OCT probes have been developed using a side-looking geometry, which is appropriate for imaging narrow-lumen vessels. A forward-looking probe would greatly enhance the ability of imaging mucosa of large or hollow organs such as stomach, colon, and bladder, but the implementation is complicated by the catheter size constraints. Approaches to achieve forwardlooking EOCT have been reported and typically offer uni-dimensional scanning due to the difficulty of inserting a two-dimensional optical scanner within the small catheter diameter (2.9 mm). Given a catheter-integrated, two-dimensional optical scanner, high resolution 3D EOCT imaging can be obtained using longitudinal dimension scanning with the reference beam located outside the endoscope. This imaging approach will allow accurate non-invasive diagnoses of cancers and other pathologies limited in depth of penetration to epithelial or near sub-epithelial layers. ? The novel design for the two-dimensional optical scanner proposed here is based on microfabricated cantilevers. Static deflection and resonance frequency calculations indicate that, for a reasonable set of parameters, the proposed scheme provides a size and power consumption advantage over the competing approaches and excellent scanning range and speed performance. This project is focused on the microfabrication and characterization of a two-dimensional scanner optimized for catheter OCT imaging. The microfabrication processing steps will be designed to include a range of parameters selected based on the calculated effects of actuator geometry and film thicknesses on scanning performance. The mechanical and optical properties of the devices will be characterized with a suite of available measurement tools. A detailed optical simulation of the EOCT system will be performed based on actual performance of the optical scanner. Optimized devices will be integrated with suitable optical components and incorporated into a high-speed Fourier-Domain OCT scanner to assess image quality. ? ? ? ?
| Gilchrist, Kristin H; Dausch, David E; Grego, Sonia (2012) Electromechanical performance of piezoelectric scanning mirrors for medical endoscopy. Sens Actuators A Phys 178:193-201 |
