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Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 19, Iss. 20 — Sep. 26, 2011
  • pp: 19182–19189

Image contrast immersion method for measuring refractive index applied to spider silks

Douglas J. Little and D. M. Kane  »View Author Affiliations

Optics Express, Vol. 19, Issue 20, pp. 19182-19189 (2011)

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A technique for measuring the refractive index of micron sized fibers using a series of immersion index matching oils, and image contrast measurements is proposed and demonstrated. It has been applied to radial silks of the orb web weaving spider Plebs eburnus. These have widths of ~1-2 microns. Values about 1.5500 are obtained, with birefringence values between 0.0000 and 0.0133 for individual silks. An uncertainty in the range ± 5 × 10−4 to ± 2 × 10−3 is achieved for these challenging samples. This accuracy is about a twenty times improvement on previously reported measurements for spider silks using other techniques. The technique is used to obtain measurements of the refractive index of spider silks as a function of wavelength, for the first time. An Abbe number for the radial silks of Plebs eburnus of ~32 is found.

© 2011 OSA

OCIS Codes
(120.5710) Instrumentation, measurement, and metrology : Refraction
(260.1440) Physical optics : Birefringence
(290.3030) Scattering : Index measurements
(160.1435) Materials : Biomaterials

ToC Category:
Instrumentation, Measurement, and Metrology

Original Manuscript: July 14, 2011
Revised Manuscript: August 25, 2011
Manuscript Accepted: September 2, 2011
Published: September 19, 2011

Douglas J. Little and D. M. Kane, "Image contrast immersion method for measuring refractive index applied to spider silks," Opt. Express 19, 19182-19189 (2011)

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