Feature Of The Week 10/13/13: Tsinghua University Demonstrates a Tiny OCT Endoscopic Probe Using a Hollow Ultrasonic Motor
Optical coherence tomography (OCT) is an emerging modality for obtaining cross-sectional images. Due to limitation of the light penetration, small and high resolution probes for endoscopic OCT have been regarded as powerful tools in examining internal organs. Among them, circumferential probes are utilized extensively for imaging within hollow tissues, such as arteries, esophagus, and colon. In recent years, distal scanning is of high interest, as the whole fiber remains stationary in this case. The twisting and nonuniformity in the conventional proximal scanning are avoided. However, some problems emerge such as the wire-shadow effect and the relative large size of the probe tip due to the existence of driving unit.
Professor Ping Xue, PhD Student Tianyuan Chen, Ning Zhang and others from Tsinghua University in China, have made some very impressive hollow ultrasonic motor scanner designs. The endoscopic probe for optical coherence tomography is equipped with a miniaturized hollow ultrasonic motor that rotates the objective lens and provides an internal channel for the fiber to pass through, enabling 360 deg unobstructed circumferential scanning. This probe has an outer diameter of 1.5 mm, which is ultra-small for motorized probes with an unobstructed view in distal scanning endoscopic OCT. Instead of a mirror or prism, a customized aspheric right-angle lens is utilized, leading to an enlargement of the numerical aperture and thus high transverse resolution. Spectral-domain OCT imaging of bio-tissue and a phantom is demonstrated with resolution of 7.5 μm(axial) × 6.6 μm(lateral) and sensitivity of 96 dB. This design is very promising in the future development of endoscopic OCT for clinical applications.
For more information see recent Article. Courtesy of Ping Xue from Tsinghua University.