Chemical Laser Interactions with Human Tissues

Abstract

Controlled chemical laser ablation of human tissues may offer a means to perform precise microsurgical procedures such as laser keratomileusis1 and laser angioplasty. Some of the potential advantages of chemical lasers for these applications have been identified previously. Repeti­tively pulsed (rp) hydrogen fluoride (HF) chemical laser interactions with human corneal and cardiovascular tissues have been studied to understand tissue ablation phenomenology, effects and mechanisms under well character­ized laser irradiation conditions. RP HF chemical laser experiments have been performed at two wavelengths ( λ = 2.78 µm and 2.91 µm) over a radiant exposure/fluence range of 0.05 to 10 J/cm2 to determine ablation efficien­cies and effective enthalpies of ablation (Q*) as a function of wavelength and radiant exposure/fluence. The experimental results have been analyzed to consider the physical and chemical processes associated with thermo-chemical ablation of human tissues by pulsed mid-infrared lasers. The present chapter summarizes the nature of pulsed HF chemical lasers and their match to tissue ablation requirements, presents quantitative tissue ablation results obtained using an rp HF chemical laser operating in the λ= 2.7 – 3.0 Jim wavelength region, and discuss tissue ablation mechanisms.