Feature Of The Week 4/22/12: Novel MEMs-Driven OCT Endoscopic Imaging Probe Investigated by Singapore Researchers
Optical coherence tomography (OCT) has demonstrated its potential as a powerful imaging technology due to its cellular or even subcellular resolution (1-10 μm), which is considered suitable for early detection and diagnosis of cancer. For some clinic applications, for example, intravascular or gastrointestinal investigation, full circumferential scanning (FCS) is highly desired. Early research efforts on FCS such as spinning the entire catheter with build-in cables and fibers were capable of scanning at limited speeds with nonlinear motion due to the long cable rotation. Commercially-available micromotors have also been employed to spin mirrors or prisms to achieve FCS. In recent years, MEMS technology has demonstrated strong potential in biomedical imaging applications due to its outstanding advantages of, for instance, small size, fast scanning speed and convenience of batch fabrication.
A novel MEMS micro-scanner that is capable of circumferential scanning for optical coherence tomography (OCT) applications is proposed. The proposed configuration utilizes multiple parallel incident light beams to drastically reduce the required mechanical rotation angle to achieve 360-degree circumferential scanning with only minimal increase in package size. This compact MEMS platform is placed at the distal side of the endoscopic probe and orientated perpendicularly to the incident light beams (as shown in page 4 of the slides). A micro-pyramidal polygon reflector with four highly reflective facets is mounted on top of MEMS chevron-beam microactuators to redirect the focused light. A four-pieces-in-one fiber-pigtailed GRIN lens bundle is utilized to direct the focusing incident light beams to the slanted facets of the micro-reflector. Once the micro-reflector is driven to rotate, a circumferential light scan will be realized. A circumferential tissue image may be reconstructed by recording the data from the four fiber optic “channels” sequentially or simultaneously. The proposed configuration not only provides a way to achieve compact and miniature circumferential scanning probes, but also helps to reduce deformation that may be induced by residual stresses in traditional thin MEMS micromirrors as a solid reflector block is used here as the light reflector.
For more information see recent Article. Courtesy Guangya Zhou from the National University of Singapore.