Hollow waveguides as delivery systems

Nathan I. Croitoru

doi:10.1117/12.197521

22 December 1994 Hollow waveguides as delivery systems

Nathan I. Croitoru

Proceedings Volume 2328, Biomedical Optoelectronic Devices and Systems II; (1994) https://doi.org/10.1117/12.197521
Event: International Symposium on Biomedical Optics Europe '94, 1994, Lille, France

Abstract

Thetheoretical basis ofpropagation ofradiation through hollow waveguides was developed by Marcatili and Schmeltzer [1] an was shown that a metallic mirror with a dielectric overlayer works as guiding elements for the transmitted radiation. This idea was employed for the new type ofwaveguides which are developed for mid and far infrared (IR) transmission and applications as delivery systems mainly in medicine. The need for new fibers or waveguides appeared as a consequence of the difficulties to extend the application of regular fibers made of quartz or glass to the transmission of radiation with wavelengths larger than 2.5 tm. This is due to the very large absorption ofthese materials at mid and far IR wavelenghts. Investigations made to make fibers for use in medicine employing other materials which have low absorption in mid and long IR [25] have encountered several difficulties (poisonous, brittle, transmission depending on irradiation). The hollow waveguides are able to overcome these difficulties and to give several advantages. The first advantage is based on the fact that the guiding materials (metallic mirror and dielectric overlayer) can be deposited on the internal wall of a cylindrical tube made from any material. This enables to overcome the difficulty of non suitable materials since for a given application can be selected the corresponding suitable material and use it as a cylindrical substrate for the guiding layers. E.g., these waveguides can be made very flexible for any used ID in medicine (0.5- 4.0 mm). For this purpose is used a tube of plastic material (Teflon) [6,7]. Radius of bending of less than 3 cm and angle of bending of 1800was already achieved. High power delivery is possible for the case when the substrate tube is made of a metal (Ag). Power of the order of many kW were delivered [8] but the minimum bending radius is only about 20 cm. A third important advantage is the possibility to use the bore of the hollow waveguide for gas flow directly through the guide for cooling the operation site or for supply with liquid medicines. The last but not the least advantage is the possibility to produce very cheap waveguides made of Teflon since the method of preparation and the cost of matenals are very low.

Citation Download Citation

Nathan I. Croitoru "Hollow waveguides as delivery systems", Proc. SPIE 2328, Biomedical Optoelectronic Devices and Systems II, (22 December 1994); https://doi.org/10.1117/12.197521

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