Model-based optimization of laser excitation and detection improves spectral contrast in noninvasive diffuse Raman spectroscopy

Max Dooley, Thomas Paterson, Louise Dexter, Pavel Matousek, Hamid Dehghani, Ioan Notingher*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Spatially offset Raman spectroscopy (SORS) is a powerful technique for subsurface molecular analysis of optically turbid samples. Numerical modeling of light propagation has been used to investigate opportunities for improving spectral contrast and signal to noise ratio when imaging regions of interest located 0–4.5 mm below the surface in polymer bulk material. Two- and three-dimensional modeling results demonstrate that when analyzing a certain region of interest (ROI) of finite lateral dimensions below the sample surface, offsetting both the laser source and detector in opposite directions from the central point of the ROI can increase the spectral contrast as compared to conventional SORS approach where the detector or the laser source is maintained at the central point (centered SORS). The outlined modeling results have been validated experimentally using a bulk polymer sample with a trans-stilbene ROI (cylinder) below the sample surface. The results show that modeling of the spatial configurations of laser excitation and detection points can be used to optimize the instrument configuration to achieve significant improvements (up to 2.25-fold) in performance over the conventional centered SORS. Such optimal solutions can then be implemented, for example, using robust fiber optic probes, moveable optics, or flexible spatial light modulator instruments for specific applications.

Original languageEnglish
Pages (from-to)801-811
JournalApplied Spectroscopy
Issue number7
Early online date26 Jan 2022
Publication statusE-pub ahead of print - 26 Jan 2022

Bibliographical note

Funding Information:
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the Engineering and Physical Sciences Research Council [grant number EP/L025620/1].

Publisher Copyright:
© The Author(s) 2022.


  • computational modeling
  • diffuse Raman
  • Raman spectroscopy
  • SORS
  • spatially offset Raman spectroscopy

ASJC Scopus subject areas

  • Instrumentation
  • Spectroscopy


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