Signal processing-enhanced laser-based infrared spectroscopy

Student thesis: Doctoral Thesis

Abstract

In this dissertation, a portfolio of three projects is presented where intracavity embodiment of optical parametric oscillators (OPO) and various signal processing tools applied to the data they produced are the common factors in all the work done during this programme. Two demonstrated projects were based on a study of new potential applications for commercialised OPO based imaging system, while in the last one the unmatched characteristics of such a system were exploited, in order to develop new embodiment of a spectroscopic technique.The INHERIt project explored the use of hyperspectral imaging technologies, combined with advanced signal processing techniques, for the purpose of automatically recognising counterfeit paintings. Various challenges associated with laser based imaging are discussed as well as hardware based solutions to resolve some of these issues are proposed. The application of classification techniques was demonstrated based on the data acquired from both bespoke and actual forged paintings.The Rosdam project aimed to evaluate two types of hyperspectral imaging systems, as well as their capability and applicability for the detection of oil spillages in ice-affected waters. This work lead to the conclusion that the employed technology was not suitable for oil under ice detection. The undertaken experimental approach is explained, the treatment of oil and ice is discussed and the findings and lessons learned during this work are presented.The IC-OPO-PAS project aimed to develop an optical molecular gas sensor exhibiting high levels of selectivity and sensitivity. The outstanding sensitivity demonstrated by this technology is rooted in a novel combination of photoacoustic spectroscopy (PAS) operated within the cavity of a continuous-wave, Intracavity OPO. In this work detection at the level of single parts-per-billion (ppb) is shown and a discussion on how this technology could be readily refined to potentially demonstrate a sensitivity of 10's parts-per-quadrillion (ppq) is presented.This thesis revealed a successful combination of seemingly two independent fields of science which, when utilised together, can provide superior results. Moreover, it demonstrated the need for broadly tuneable laser sources operating in infrared spectral region. Overall conclusions are given in this portfolio of presented above projects and possible future research opportunities are discussed in the context of the results obtained over the course of this programme.
Date of Award1 Dec 2017
LanguageEnglish
Awarding Institution
  • University Of Strathclyde
SponsorsUniversity of Strathclyde
SupervisorStephen Marshall (Supervisor)

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