Noninvasive detection of inhomogeneities in turbid media with time-resolved log-slope analysis

Siew Kan Wan, Zhixiong Guo, Sunil Kumar, Janice Aber, Bruce A. Garetz

Research output: Contribution to journalArticlepeer-review


Detecting foreign objects embedded in turbid media using noninvasive optical tomography techniques is of great importance in many practical applications, such as in biomedical imaging and diagnosis, safety inspection on aircrafts and submarines, and LIDAR techniques. In this paper we develop a novel optical tomography approach based on slope analysis of time-resolved back-scattered signals collected at the medium boundaries where the light source is an ultrafast, short-pulse laser. As the optical field induced by the laser-pulse propagates, the detected temporal signals are influenced by the optical properties of the medium traversed. The detected temporal signatures therefore contain information that can indicate the presence of an inhomogeneity as well as its size and location relative to the laser source and detection systems. The log-slope analysis of the time-resolved back-scattered intensity is shown to be an effective method for extracting the information contained in the signal. The technique is validated by experimental results and by Monte Carlo simulations.

Original languageEnglish (US)
Pages (from-to)493-500
Number of pages8
JournalJournal of Quantitative Spectroscopy and Radiative Transfer
Issue number4
StatePublished - Apr 1 2004


  • Log-slope
  • Noninvasive detection
  • Optical tomography
  • Transient radiation transfer
  • Turbid medium
  • Ultrafast laser

ASJC Scopus subject areas

  • Radiation
  • Atomic and Molecular Physics, and Optics
  • Spectroscopy


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