An apparatus includes first and second light sources for respectively generating broadband and monochromatic lights, a beamsplitter optically coupled to the first light source for splitting the broadband light into a reference light and a sample light, a reference arm optically coupled to the beamsplitter for receiving the reference light and returning the received reference light into the beamsplitter, a sample arm optically coupled to the beamsplitter and the second light source for combining the sample and monochromatic lights, delivering the combined light to the target of interest, collecting a backscattering light and a Raman scattering light generated from interaction of the combined light with the target of interest, returning the backscattering light into the beamsplitter so as to generate an interference signal between the returned backscattering light and the returned reference light in the beamsplitter, and directing the Raman scattering light in an output optical path.