Apparatus and method for selective laser-induced heating of biological

Abstract

The invention features a probe for selectively delivering laser radiation to a first tissue having a first index of refraction relative to a second tissue having a second index of refraction less than the first index. The probe includes a laser transmitting medium having an optical axis and a tissue-contacting surface. In some embodiments, the optical axis contacts the tissue-contacting surface at an angle that is less than the critical angle for an interface between the tissue-contacting surface and the first tissue and greater than or equal to the critical angle for an interface between the tissue-contacting surface and the second tissue, wherein during operation the probe directs the laser radiation along the optical axis to the tissue-contacting surface. In other embodiments, the optical axis forms an angle with the tissue-contacting surface, and during operation the probe directs the laser radiation along the optical axis to the tissue-contacting surface, transmits a first amount of laser energy through the tissue-contacting surface when contacting the first tissue, and transmits a second amount of laser energy through the tissue-contacting surface when contacting the second tissue, wherein the angle is selected such that the first amount of laser energy is at least twice the second amount of laser energy. The invention also features related methods for selectively delivering laser radiation to tissue based on refractive index.