A method for measuring the complex refractive index of a turbid medium

Zhi Cheng Jian, Jiun You Lin, Po Jen Hsieh, Huei Wen Chen, Der Chin Su

Research output: Contribution to journalConference article

Abstract

Based on the heterodyne interferometry and Fresnel equations, an alternative method for measuring the complex refractive index of a turbid medium. A light beam is incident on the boundary between a right-angle prism and a turbid medium. The phase difference between s- and p- polarizations of the reflected light occurs. The phase difference depends on then incident angle and the complex refractive index of a turbid medium; their relation can be derived from Fresnel equations. The phase difference can be measured accurately with the heterodyne interferometry. Because there are two unknown parameters to be estimated, at least the phase differences under two different conditions should be measured. Then, these measured data are substituted into the derived relation, and a set simultaneous equation is obtained. If the simultaneous equation is solved, the complex refractive index can be estimated. Because the reflected light from the boundary is measured, the scattering noises coming from the turbidity of the tested medium can be greatly reduced. In addition, this method has some merits such as simple optical setup, high sensitivity, high stability, and suitability for a little amount of the tested medium in its native state (without dilution).

Original languageEnglish
Article number140
Pages (from-to)1036-1043
Number of pages8
JournalProceedings of SPIE - The International Society for Optical Engineering
Volume5856 PART II
DOIs
Publication statusPublished - 2005 Dec 19
EventOptical Measurement Systems for Industrial Inspection IV - Munich, Germany
Duration: 2005 Jun 132005 Jun 17

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All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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