Si, Chen (2011) The quantitative analysis of optical phase measurement and its application to the determination of corneal birefringence. PhD thesis, University of Warwick.

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Abstract

In this thesis, a phase sensitive interferometer is successfully implemented to perform birefringent object surface-profile measurement, based on a polarisation adjustment approach. Using monochromatic light, a novel polarization interferometric method is developed, incorporating the birefringence technique and a waveplate. In our experiments, a birefringent wedge is designed for generating carrier fringes in the polariscope. Retardance is calculated from phase shifting using a phase matching technique. The accuracy of the method has been demonstrated to have an error of less than 0.02 radians. The accuracy and resolution quantitative analysis presented in this thesis can be used to determine accurately the phase-shifting interferometry for high-precision surface profile and bio-structure, such as fibre and collagen measurements with low cost. FFT technique and phase-stepping methods are described to determine birefringence within the cornea. The distribution of human corneal lamellar collagen is determined through a microscopic technique using the combination of a circular polariser and a quarter-wave retarder. A quantitative measure of corneal birefringence is achieved by phase unwrapping. The experimental findings of elliptic and hyperbolic populations of collagen fibrils may explain the optical phenomena of central corneal retardation with biaxial-like behaviour in more peripheral areas. A low cost, simple, and direct approach has been developed to make the required microscopic measurement. The traditional transmission system is improved by applying a reflection system with an LED light source and is suitable for the analysis of the birefringent cornea structures in vivo. A further instrument based upon a synthetic aperture approach has been created with the purpose of measuring the three dimensional birefringence structure of the cornea. The concept of the instrument is a combination of the parallax between individual lenses and the numerically generated planes of focus to visualise the phase structure.

Item Type:	Thesis or Dissertation (PhD)
Subjects:	Q Science > QC Physics Q Science > QM Human anatomy
Library of Congress Subject Headings (LCSH):	Interferometers, Refraction, Double, Cornea -- Analysis, Biological interfaces
Date:	February 2011
Institution:	University of Warwick
Theses Department:	School of Engineering
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Bryanston-Cross, P.
Extent:	xxv, 294 leaves : ill., charts
Language:	eng
URI:	http://wrap.warwick.ac.uk/id/eprint/38442

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