title: Noninvasive subsurface analysis using multiple miniaturized Raman probes, part I: basic study of thin-layered transparent models of biomedical tissues.
abstract: This study describes a basic theory for reconstructing pure Raman signals of materials composing a multilayer sample from Raman spectra obtained using two types of miniaturized Raman probes. An illustrative example is demonstrated using a multilayer system of samples composed of the transparent plastics polymethylmethacrylate (PMMA) and polyethylene (PE) as a model of thin-layered biomedical tissues. When the same region of an object is measured using Raman probes with different focal properties, the Raman spectra provide different depth profile information depending on the level of light penetration. Thus, a detailed comparison of the spectra can provide an interesting opportunity to probe the differences between the layers. A simple analytic form is presented for reconstructing the pure Raman spectra of the embedded layer. The method applies an understanding of the Raman sampling volume in layered transparent materials to the interpretation of Raman spectra experimentally measured by multiple probes. The basic theory described here is necessary for the expansion of the technique to turbid media, such as biological samples, where light-scattering effects must be considered. The potential applications of the proposed method include material and catalyst subsurface probing through different embedded materials, such as assessment of silicon wafers, effective noninvasive screening for catalyst synthesis, and biomedical tissue research.
authors.affiliation: School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo, Japan.
authors.forename: Yuko S
authors.initials: YS
authors.lastname: Yamamoto
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Shinzawa
authors.forename: Yuji
authors.initials: Y
authors.lastname: Matsuura
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Ozaki
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Sato
mesh_terms: D003952:Diagnostic Imaging; D008027:Light; D008954:Models, Biological; D020959:Polyethylene / Q000737:chemistry; D019904:Polymethyl Methacrylate / Q000737:chemistry; D012542:Scattering, Radiation; D012815:Signal Processing, Computer-Assisted; D013059:Spectrum Analysis, Raman / Q000295:instrumentation* / Q000379:methods*
chemical_list: D020959:Polyethylene; D019904:Polymethyl Methacrylate