Masters Theses

Date of Award

12-1989

Degree Type

Thesis

Degree Name

Master of Science

Major

Electrical Engineering

Major Professor

T.V. Blalock

Committee Members

R. Bodenheimer, J. Rochelle

Abstract

An exact solution of Maxwell's equations for the diffraction created by a non-conducting cylinder in a propagating plane wave at normal incidence is presented, The exact solution contains a series of Bessel functions with argument ka ( where k is the wave number and a is the radius of the cylinder ). In previous work, this solution was not suited for numerical calculation for large values of ka because of the slow convergence of the series. An algorithm has been developed which will allow computation of this exact solution even for large values of ka. This theoretical work is presented as an aid in the design of instruments intended to measure properties of airborne particles based on their optical response.

The algorithm has been applied to the case of glass fibers whose diameters range from approximately one-half to twenty micrometers. The design goal was to develop an optical sensor using near infrared radiation that would have a linear response as a function of diameter over the range of interest. Theoretical calculations showed that the total power scattered by the fiber into a specific region would have the desired relationship with diameter. An optical sensor was built based upon the design indicated and tested to verify the response. A very high correlation was found to exist between the diameter as predicted by the sensor and the diameter measured microscopically.

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