title: Fully automated time domain spectrometer for the absorption and scattering characterization of diffusive media.
abstract: We describe a system for absorption and scattering spectroscopy of diffusive media based on time-resolved reflectance and transmittance measurements. The system is operated with mode-locked lasers tunable in the 550-1050 nm spectral range and on a detection chain based on time-correlated single-photon counting. All measurement procedures such as laser tuning and optimization, signal conditioning, data acquisition, and analysis are completely automated, permitting spectral measurements over the whole range in a few minutes. The criticalities of the system are discussed together with the strategies to compensate them. The Medphot protocol devised for the characterization of photon migration instruments was applied to assess the system performances in terms of accuracy, linearity, noise, stability, and reproducibility. Finally, an example of application of the instrument to the spectroscopy of powders is presented.
authors.affiliation: ULTRAS-CNR-INFM and IFN-CNR, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milan, Italy. antonio.pifferi@polimi.it
authors.forename: Antonio
authors.initials: A
authors.lastname: Pifferi
authors.forename: Alessandro
authors.initials: A
authors.lastname: Torricelli
authors.forename: Paola
authors.initials: P
authors.lastname: Taroni
authors.forename: Daniela
authors.initials: D
authors.lastname: Comelli
authors.forename: Andrea
authors.initials: A
authors.lastname: Bassi
authors.forename: Rinaldo
authors.initials: R
authors.lastname: Cubeddu
mesh_terms: D000042:Absorption; D004058:Diffusion; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008027:Light; D009391:Nephelometry and Turbidimetry / Q000295:instrumentation* / Q000379:methods; D010783:Photometry / Q000295:instrumentation* / Q000379:methods; D017785:Photons; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity; D013057:Spectrum Analysis / Q000295:instrumentation* / Q000379:methods