In an image transmitting assembly of small diameter fibers, a marked deterioration in image contrast and resolution may occur when there is substantial light leakage between neighboring fibers at the region of the line contact. Expressions have been derived for the magnitude of flux leakage between neighboring fibers due to frustrated total reflections and thereby the point-spread function for an uninsulated fiber assembly is computed. Further, the static and dynamic point-spread functions of fiber bundles have been measured experimentally and the lower limit in fiber diameter for an image transmitting assembly of uninsulated fibers is derived.
N. S. KAPANY, "Fiber Optics. V. Light Leakage due to Frustrated Total Reflection," J. Opt. Soc. Am. 49, 770-777 (1959)