Fiber optics for free electron laser medical applications

Summary form only given. Free electron lasers (FEL) are interesting tools for tissue ablation research. A variety of fiber optics are available for delivery of mid-infrared laser energy. These include fluoride glasses, chalcogenide glasses, single-crystal sapphire and various hollow waveguide structures. Unfortunately, many infrared transmitting materials are easily damaged by high energy laser pulses. The high peak-power pulses offered by the FEL are particularly damaging to these fibers. By taking advantage of the tunability of the FEL, we were able to investigate the laser damage mechanisms of certain infrared fiber optics and engineer more durable fibers. Studies of the ablation properties of hard and soft tissues were conducted with the FEL and various infrared transmitting fiber optics. The FEL was tuned near the 3 μm fundamental absorption band of tissue to determine the optimal wavelength for ablation. Radiation at 3 μm is more difficult to deliver because of problems with the fiber optics, but offers the highest absorption in tissue. Wavelengths near 3 μm are easier to deliver through fibers, and may offer more bulk removal of tissue. Experiments were performed on human temporal bones, human teeth, rabbit eyes, and rat spinal cords