An optical measurement system and method are provided. Pump sample light and probe sample light are delivered through into an anatomical structure of a user. The anatomical structure has molecules having a resonant vibrational frequency equal to the difference between a first optical frequency of the pump sample light and a second optical frequency of the probe sample light, whereby a portion of the probe sample light is inelastically scattered by the molecules as signal light encoded with a physiological event occurring in the molecules, and whereby sample light comprising the signal light exits the anatomical structure. Signal light in the exiting sample light is detected, and an electrical signal representative of the signal light is outputted. The electrical signal is analyzed, and based on this analysis, the presence and the depth of the physiological event in the anatomical structure is determined.
Detection of fast-neural signal using depth-resolved spectroscopy via intensity modulated interferometry having tunable pump laser