Evaluation of thermal lens fringes using Hilbert and Fourier transform methods


Sarac Z. , Birkok H. G. , Taskin H., Ozturk E.

IET SCIENCE MEASUREMENT & TECHNOLOGY, vol.5, no.3, pp.81-87, 2011 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 5 Issue: 3
  • Publication Date: 2011
  • Doi Number: 10.1049/iet-smt.2010.0045
  • Title of Journal : IET SCIENCE MEASUREMENT & TECHNOLOGY
  • Page Numbers: pp.81-87

Abstract

This study presents the analysis of thermal lens fringes obtained by heating the Nile-blue/ethanol solution with a He-Cd laser in aMichelson interferometer by utilising the Hilbert transform method (HTM) and the Fourier transform method (FTM) with a Gaussian filter. HTM and FTM are used for obtaining local phase and refractive index change maps of the interferograms. The results reveal that HTM creates harmonics in the frequency spectrum; hence, the signal cannot be filtered very accurately, whereas FTM with a Gaussian filter can create a smooth filtering effect.