Title: Probe-beam diffraction in a pulsed top-hat beam thermal lens with a mode-mismatched configuration
Abstract: The Fresnel diffraction integral is used directly to describe the thermal lens (TL) effect with a mode-mismatched collinear configuration. The TL amplitudes obtained with Gaussian, Airy, and top-hat beam excitations are computed and compared. Numerical results for beam geometries optimized for both near- and far-field detection schemes are presented, and the analytical results developed by Bialkowski and Chartier [Appl. Opt.36, 6711 (1997)] for a Gaussian beam TL effect are summarized in simplified form. Both the numerical and the analytical results demonstrate that, under a beam geometry optimized for either near- or far-field detection, the Gaussian beam TL experiment has approximately the same maximum signal amplitude as does the photothermal-interference scheme. A comparison between the optimum near- and far-field detection beam geometries indicates that a practical mode-mismatched TL instrument should be based on the far-field detection geometry. The computation results further demonstrate that the optimum beam geometry and the TL amplitude depend largely on the excitation-beam profile. The top-hat beam TL experiment is approximately twice as sensitive as the Gaussian beam TL scheme.
Publication Year: 1999
Publication Date: 1999-08-20
Language: en
Type: article
Indexed In: ['crossref', 'pubmed']
Access and Citation
Cited By Count: 25
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