An optical source sweeps a source light over an optical wavelength range. An interferometer splits the source light into sample light and reference light, delivers the sample light into an anatomical structure, such that the sample light is scattered by the anatomical structure, resulting in physiological-encoded signal light that exits the anatomical structure, and combines the signal light and the reference light into an interference light pattern having an array of spatial components and a plurality of oscillation frequency components. An optical detector array detects intensity values of the array of spatial components. A processor derives an array of intensity values of each oscillation frequency component from the detected spatial component intensity value array, reduces each derived oscillation frequency component intensity value array to a single frequency component intensity value, and determines a depth of a physiological event in the anatomical structure based on the reduced frequency component intensity values.
