Yoshihide Okagami

Erbium:YAG laser lithotripsy by use of a flexible hollow waveguide with an end-scaling cap.

An Er:YAG laser light delivery system composed of a polymer-coated silver hollow waveguide and a quartz sealing cap has been developed for calculus fragmentation. Sealing caps with various distal-end geometries were fabricated, and the focusing effects of these caps for Er:YAG laser light were measured both in air and in water. Owing to the high power capability of the quartz a beam of sealing caps, Er:YAG laser light with an output energy of 200 mJ and a repetition rate of 10 Hz was successfully transmitted in saline solution by use of the system. Calculus fragmentation experiments conducted in vitro showed that the delivery system is suitable for medical applications in lithotripsy. We also found that the cap with a focusing effect is more effective in cutting calculi. The deterioration of the sealing caps after calculus fragmentation is also discussed.

Infrared medical laser system with hollow optical fibers

Medical IR laser systems involving a beam delivery cable based on holow optical fibers are introduced. Two types of the systems are developed to cover a wide range of medical applications: one with a CO2 laser which is mainly for soft tissue ablation and another wiht an Er:YAG laser for ablation of hard tissue in dental applications. The both systems which have been recently commercialized newly adopted a hollow glass fiber having inner metal and polymer films. Because of the high mechancial and chemical stability, flexibility, and the low production cost of the fibers, a reliable and easy-to-handle medical laser systems are launched at low cost. The components of the systems including the beam delivery cable and distal tips specialized for various medical applications are described in detail.

Calculi fragmentation of Er:YAG laser light through a sealed flexible hollow fiber delivery system

Calculi fragmentation experiments were conducted in vitro by using Er:YAG laser light. The laser light delivery system was composed of a cyclic olefin polymer (COP)-coated silver (Ag) hollow fiber and a quartz cap to seal the output end of the hollow fiber. Sealing-caps wiht various distal end goemetries were fabricated and the focusing effects for Er:YAG laser light were measured both in air and in water. Fragmentation characteristics of the sealing-caps were investigated. The deterioration of sealing-caps after calculus fragmentation was also experimentally discussed.

Hollow bent output devices in CO 2 laser light delivery system

In order to change the output direction of laser light in a small operation space, two types of hollow bent output devices are proposed for medical laser light delivery system. One is the hollow fiber insert-type, which is of the bending radius of 40 mm. The other type, based on a fixed- bent pyrex glass tube, is of the minimum bending radius of 2 mm. Both types of devices are inner-coated with a silver layer and a cyclic olefin polymer (COP) layer. Loss properties for CO2 laser light are clarified for the insert-type devices, called laryngo-tip. And the transmission properties for pilot beams are experimentally discussed. For the fixed-bent tips, the losses are around 0.7 dB, which are almost independent on the bending angles and radii. Transmissions of the tips remain undamaged after 1-hour-delivery of 5 W output CO2 laser light.