Evaluation of thermal lens fringes using Hilbert and Fourier transform methods

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

IET SCIENCE MEASUREMENT & TECHNOLOGY, cilt.5, ss.81-87, 2011

  • Cilt numarası: 5 Konu: 3
  • Basım Tarihi: 2011
  • Doi Numarası: 10.1049/iet-smt.2010.0045
  • Dergi Adı: IET SCIENCE MEASUREMENT & TECHNOLOGY
  • Sayfa Sayısı: ss.81-87

Özet

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.