Two ways are described in which dispersion can be used to improve the information transfer through fiber bundles. First, the use of dispersion at the entrance and exit ends of a fiber-optics image-transmitting bundle produces an image with resolution improved by about a factor of two. The individual fiber elements are not seen in the image. Second, it is possible to reduce drastically the number of fibers in the bundle and still transmit a complete image. One way is to arrange a number of rows of fibers parallel to each other but spaced a distance apart. The dispersion is perpendicular to the rows. Each row of fibers carries a chromatic image of the object. At the exit end the different chromatic images from the various rows of fibers are recombined by a dispersion system similar to that at the entrance end. Thus, each image point is reconstructed by a plurality of wavelengths. The image can therefore contain color as well as intensity information. The improvement of information transfer per fiber depends on the number of rows and on the ratio of dispersion distance to fiber diameter. It is shown that with a ratio of 100, a 20-row fiberscope can transfer the same effective information as a conventional fiberscope containing 660 rows. The relationship between dispersion and achromatic field is discussed and a comparison is given of prism and grating dispersion systems.
CHARLES J. KOESTER, "Wavelength Multiplexing in Fiber Optics," J. Opt. Soc. Am. 58, 63-67 (1968)