A theoretical ray model was developed for energy distribution of IR radiation, transmitted through hollow straight and bent fibers. The theoretical results were compared with the experimental data obtained from measurements of our plastic hollow fibers. A satisfactory agreement between the experimental and theoretical data was achieved. Application of the plastic hollow fibers in surgery (on certain organic tissues) is described.
"Plastic Hollow Tubes As Waveguides For IR Radiation", Proc. SPIE 0906, Optical Fibers in Medicine III, (21 June 1988); doi: 10.1117/12.945276; https://doi.org/10.1117/12.945276