Light modulation for improved photoacoustic feedback on light-induced treatments and procedures

A method for acquiring information from a biological medium interacting with a light beam, the method comprising:

• a) imposing an intensity modulation on the light beam, the intensity modulation comprising a plurality of modulation frequencies;
• b) monitoring a photoacoustic feedback signal resulting from the interaction of the light beam with the biological medium, the monitoring comprising:
• i. obtaining a photoacoustic feedback signal component related to each of the modulation frequencies;
• and
• comparing the photoacoustic feedback signal components.

A system for performing and monitoring, in real-time, a procedure on a biological medium, the system comprising:

• a light source generating a light beam according to optical parameters selected to perform the procedure through interaction of the light beam with the biological medium;
• a modulation controlling device coupled to the light source and configured to impose an intensity modulation on the light beam at a feedback modulation frequency;
• a modulation frequency selector operable to select the feedback modulation frequency based on a photoacoustic frequency response characterizing the biological medium upon interacting with modulated light;
• and
• an acoustic transducer coupled to the biological medium and configured to monitor a photoacoustic feedback signal from the biological medium in real-time during the procedure.