Date of Award


Document Type


Degree Name

Master of Science in Engineering (MSE)


Electrical and Computer Engineering

Committee Chair

Robert Lindquist

Committee Member

Laurie Joiner


Refractive index, Optical measurements, Refractometers


Documentation for optical polymer refractive indices tend to be listed for one wavelength, λd = 587.56 nm, out to only 2 decimal places. Optical glass catalogues generally list index values to 5 decimal places for 10-15 different wavelengths. This thesis describes a new approach to an old method to determine the indices of polymer samples at λHeNe = 632.8 nm (HeNe). It begins by introducing methods for measuring refractive index and their limitations. The property of Snell’s Law is then presented and it is shown how, with specific interferometer equipment, to determine the refractive index of a window. The method is analyzed to relate the material’s index, mechanical thickness, and focal shift according to the behavior of real rays. This behavior (spherical aberration) is analyzed and equations are derived to accommodate it. Experimental results are shown for calibration parts. Finally, a brief error analysis is presented.



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