Method to Achieve High Frame Rates in a Scanning Fiber Endoscope

Abstract

A new and miniature imaging device is being developed to allow flexible endoscopy in regions of the body that are difficult to reach. The scanning fiber endoscope employs a single scanning optical fiber to illuminate a target area, while backscattered light is detected one pixel at a time to build a complete image. During each imaging cycle the fiber is driven outward in a spiral pattern from its resting state at the image center to the outer fringe of the image. At this point, the fiber is quickly driven back to its initial position before acquiring a subsequent frame. This work shortens the time between successive images to achieve higher overall frame rates by applying a carefully timed input, which counteracts the tip motion of the scanning fiber, quickly forcing the scanning fiber to the image center. This input is called motion braking and is a square wave function dependent upon the damped natural frequency of the scanning fiber and the instantaneous tip displacement and velocity. Imaging efficiency of the scanning fiber endoscope was increased from 75–89% with this implementation.