Design and Validation of a Multimodal Diffuse Reflectance and Spatially Offset Raman Spectroscopy System for In Vivo Applications.

We report on the development of a multimodal spectroscopy system, combining diffuse reflectance spectroscopy (DRS) and spatially offset Raman spectroscopy (SORS). A fiber optic probe was designed with spatially offset source-detector fibers to collect subsurface measurements for each modality, as well as ball lens-coupled fibers for superficial measurements. The system acquires DRS, zero-offset Raman spectroscopy (RS) and SORS with good signal-to-noise ratio. Measurements on chicken breast tissue demonstrate that both DRS and RS can acquire spectra from similar depths within tissue. Measurements acquired from the skin of a human volunteer demonstrate distinct Raman peaks at 937 and 1755 cm that were unique to the zero-offset ball lens configuration and 718 and 1089 cm for the spatially offset setting. We also identified Raman peaks corresponding to melanin that were prominent in the superficial measurements obtained with the ball lens-coupled fibers but not in the spatially offset fibers.