Barton, Sinead (2019) Methods for Improving Signal to Noise Ratio in Raman Spectra. PhD thesis, National University of Ireland Maynooth.
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Abstract
Raman microspectroscopy is an optoelectronic technique based on the inelastic scattering of light. This
technique has been demonstrated to have potential to identify different materials based on subtle differences
in the Raman spectral profile using various multivariate statistical classification tools. However,
Raman scattering is an inherently weak process. Low photon counts coupled with non-ideal collection efficiencies
means that Raman spectroscopy is vulnerable to noise. This makes system optimisations, as well
as efficient and reliable noise removal, a necessity in sensitive applications such as chemical classification
or diagnostics. Provided in this thesis are software and experimental methodologies to evaluate system
performance, predict system performance under various conditions, and to identify the optimal system
configuration/set-up in order to achieve the highest possible signal to noise ratio. Modelling methodologies
presented in this thesis allow the user to systematically evaluate minimum acquisition times, optimise
camera read-out modes, and predict system behaviour with alternative optical elements in order to maximise
signal to noise ratio. The denosing algorithms presented in this thesis have been shown to provide
superior signal to noise ratio when compared with their traditional counterparts. When compared with the
double acquisition method, the proposed cosmic ray removal algorithm resulted in a 10% improvement. An
algorithm that enhances Savitzky-Golay smoothing with maximum likelihood estimation produced spectra
with up to double the signal to noise ratio when compared to the raw spectra and consistently outperformed
the algorithms it was compared to. The use of reflective substrates is also investigated and was shown to
approximately triple the collected Raman scatter when compared with transparent substrates. By utilising
the methodologies detailed in this thesis it is possible to improve the efficiency of the Raman system in
question.
Item Type: | Thesis (PhD) |
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Keywords: | Methods; Improving Signal to Noise Ratio; Raman Spectra; |
Academic Unit: | Faculty of Science and Engineering > Electronic Engineering |
Item ID: | 10862 |
Depositing User: | IR eTheses |
Date Deposited: | 10 Jun 2019 13:40 |
URI: | https://mu.eprints-hosting.org/id/eprint/10862 |
Use Licence: | This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here |
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