A simple method for determining focal distances using Talbot self-images

Oliver Spires, Jose Sasian, Sukmock Lee

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


We present a simple method to determine the focal distances of lenses with the Talbot self-images. This method uses only one grating, and a priori knowledge of the period of the grating is replaced with a linear relation between the (de)magnified periods of the Talbot images and the lens-to-grating distance. A thick lens whose effective focal length is 500 mm was used to validate the method, and the focal distance of the converging beam was determined with the difference of 0.15% for the nominal focal distance of 521.9 mm. The determined period of the grating with the difference of 0.2% also supports the validation.

Original languageEnglish (US)
Pages (from-to)638-642
Number of pages5
JournalJournal of the Optical Society of Korea
Issue number6
StatePublished - Dec 2015


  • Focal distances
  • Gratings
  • Talbot self-imaging

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics


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