European Biophysics Journal

, Volume 20, Issue 2, pp 87–99

Optical diffraction by well-ordered muscle fibres

  • R. A. Thornhill
  • N. Thomas
  • N. Berovic
Article

DOI: 10.1007/BF00186257

Cite this article as:
Thornhill, R.A., Thomas, N. & Berovic, N. Eur Biophys J (1991) 20: 87. doi:10.1007/BF00186257

Abstract

We have studied the diffraction of a focussed laser beam by single fibres of glycerinated rabbit psoas muscle as a function of the angle of incidence. Diffraction efficiencies as high as 34% were observed at the firs-order Bragg angle, indicative of well-ordered striated fibres with a strong periodic modulation of the refractive index. A theory is presented to account for our observations based upon the coupled-wave model developed by Kogelnik (1967) and Magnusson and Gaylord (1977) for the description of thick phase gratings in holography. We have solved the coupled-wave equations on a computer using a realistic index modulation taken from the measurements of Huxley and Hanson (1957). Comparison of theory with experiment shows that coupled-wave effects are indeed present in well-ordered muscle fibres, and the observed diffraction efficiency is in quite good agreement with what would be expected theoretically. Most importantly, the computer model allows us to calculate the diffraction efficiency for curved striations, which are observed for real muscle fibres under a microscope. The sensitivity of the diffraction efficiency to curvature of the striations may have implications for the interpretation of other optical experiments on muscle. We also consider the effects on our measurements of the focussing lens and refraction by the cylindrical fibre.

Key words

MuscleDiffractionStriationsRefractive index

Copyright information

© Springer-Verlag 1991

Authors and Affiliations

  • R. A. Thornhill
    • 1
  • N. Thomas
    • 2
  • N. Berovic
    • 2
  1. 1.School of Biological SciencesBirmingham UniversityBirminghamUnited Kingdom
  2. 2.Biophysics Group, School of Physics and Space ResearchBirmingham UniversityBirminghamUnited Kingdom