Design and construction of an evanescent optical wave device for the recanalization of vessels

Removing atherosclerotic material without transecting the vessel wall is a common problem for vascular surgeons and interventional cardiologists. The goal of this project is to design and construct a device that uses evanescent optical waves for precise, controlled laser ablation. For laser light incident at an angle to an optic–tissue interface greater than or equal to the critical angle, an evanescent optical wave is launched into the tissue. With evanescent optical waves, there is no free-beam propagation and the laser energy can be confined to a layer less than one wavelength thick at the optic–tissue interface. Several device designs have been proposed and constructed. The Duke University Mark III Infrared Free-Electron Laser is used to study energy deposition and ablation mechanisms at sapphire–tissue and zinc sulfide–tissue interfaces. Ablation experiments on human low-density lipoprotein and aorta tissue are presented.