Precise, controlled laser delivery with evanescent optical waves

Precise laser surgery is possible with laser pulses at wavelengths that are strongly absorbed at the surface of tissue. However, pulses at these wavel engths (far UV, far infrared) are not compatible with fiber-optic transmiss ion, making endoscopic surgical procedures inside the body difficult. We us e evanescent optical waves to demonstrate an alternative for confining ener gy near the tissue surface. Precise, superficial tissue ablation is achieve d with evanescent waves generated at a sapphire-tissue interface by a free- electron laser, where the ablation depth may be varied. A new class of prec ise, controlled laser surgical tools may be achieved in this novel approach for use in endoscopic procedures. Electromagnetic theory governing evanesc ent-wave tissue ablation is presented. (C) 1999 Optical Society of America.