Chapter 22, Problem 52AP

Endoscopes are medical instruments used to examine the gastrointestinal tract and other cavities inside the body. The light required for examination is conducted from an outside source along a long, flexible bundle of optical fibers to the tip, where it exits and illuminates the internal cavity. A lens on the lip collects an image of the lighted cavity and another fiber bundle conducts the image back along the endoscope to an eyepiece for viewing (Fig. P22.52). If each fiber in the bundle has diameter d = 1.00 × 10^–4 m and refractive index n = 1.40, find the smallest outside radius R permitted for a bend in the fiber if no light is to escape.

Figure P22.52