Selective tissue targeting by difference frequency of two wavelengths

Abstract

A method and apparatus for treating tissue directs first and second wavelengths of energy, e.g., laser or ultrasonic signal energy, into an overlap region of tissue such that the first and second wavelengths mix in situ to form a third wavelength. The third wavelength effectively couples energy into the tissue to treat tissue in said overlap region, producing local heating or cavitation. Wavelengths may be selected such that overlying tissue is unharmed, and the two wavelengths may be applied along different paths and cross in the overlap region. Absorbers or dyes may be used to tailor absorbance of the third wavelength. When using ultrasonic energy, signals of several megahertz may be so mixed to provide a lower frequency treatment signal such as a 200 kHz treatment signal or a subharmonic. Laser signals may be mixed to form a treatment signal in the infrared.

Dependencies are inferred from the claim text.