Light–Tissue Interactions

Methods of noninvasive optical diagnosis and spectroscopy of tissues involve two radiation regimes: continuous wave (CW) and time-resolved regimes.1-7 Time-resolved interactions are realized when tissue is exposed to short laser pulses and the subsequent scattered broadened pulses are recorded (time-domain method) or by irradiation with modulated light where the depth of modulation of the scattered light intensity and the corresponding phase shi in the modulation frequencies are recorded (frequency-domain or phase method). e time-resolved regimes are based on the excitation of the photon-density wave spectrum in a strongly scattering medium, which can be described in the framework of the nonstationary radiation transfer theory (RTT). e CW regime is described by the stationary RTT.