title: Frequency offset Raman spectroscopy (FORS) for depth probing of diffusive media.
abstract: We present a new technique, frequency offset Raman spectroscopy (FORS), to probe Raman spectra of diffusive media in depth. The proposed methodology obtains depth sensitivity exploiting changes in optical properties (absorption and scattering) with excitation wavelengths. The approach was demonstrated experimentally on a two-layer tissue phantom and compared with the already consolidated spatially offset Raman spectroscopy (SORS) technique. FORS attains a similar enhancement of signal from deep layers as SORS, namely 2.81 against 2.62, while the combined hybrid FORS-SORS approach leads to a markedly higher 6.0 enhancement. Differences and analogies between FORS and SORS are discussed, suggesting FORS as an additional or complementary approach for probing heterogeneous media such as biological tissues in depth.
authors.forename: Sanathana Konugolu Venkata
authors.initials: SK
authors.lastname: Sekar
authors.forename: Sara
authors.initials: S
authors.lastname: Mosca
authors.forename: Andrea
authors.initials: A
authors.lastname: Farina
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Martelli
authors.forename: Paola
authors.initials: P
authors.lastname: Taroni
authors.forename: Gianluca
authors.initials: G
authors.lastname: Valentini
authors.forename: Rinaldo
authors.initials: R
authors.lastname: Cubeddu
authors.forename: Antonio
authors.initials: A
authors.lastname: Pifferi