Thermal lens spectrometry using Gaussian and Laguerre Gaussian modes of excitation

Doctoral Thesis / Dissertation from the year 2022 in the subject Physics - Other, grade: PhD, , language: English, abstract: Imagine peering into the heart of matter, not with brute force, but with the gentle touch of light itself - this is the realm of thermal lens spectrometry, and this research unveils a groundbreaking advancement. This study revolutionizes the landscape of optical sensing by introducing a novel thermal lens (TL) spectrometry model that harnesses the unique properties of Laguerre-Gaussian (LG) modes of excitation. Departing from conventional methods reliant on Gaussian beams, this thesis meticulously develops and validates a sophisticated model, revealing the enhanced sensitivity and accuracy achievable with LG modes. Prepare to delve into a comprehensive exploration that meticulously compares LG and Gaussian excitation techniques, dissecting the intricate refractive index and temperature gradient profiles they produce. The research culminates in the development and rigorous validation of a modified dual-beam Z-scan model, experimentally verified using distilled water, solidifying its practical applicability. This investigation meticulously details the experimental setup and methodology employed, providing a transparent and reproducible framework for future studies in laser spectroscopy. Explore the depths of thermal diffusivity, absorption coefficient analysis, and the intricacies of optical sensing as this research redefines the boundaries of what's possible in non-destructive material characterization. Discover how manipulating the very shape of light unlocks unprecedented precision in thermal lens spectrometry, paving the way for advancements in diverse fields ranging from environmental monitoring to biomedical diagnostics. This work is essential reading for researchers and practitioners seeking to push the limits of detection and unlock new insights into the fundamental properties of matter through the power of light. The detailed analysis of Z-scan techniques further refines our understanding of thermal lens phenomena, offering a more accurate and reliable tool for scientists and engineers alike. This study not only presents a novel model but also provides a comprehensive guide to its implementation and application, making it an invaluable resource for anyone working in the field of laser-based analytical techniques.