Date of Award

Spring 6-2018

Document Type


Degree Name

Master of Science (MS)


Forensic Science



First Advisor

John Reffner

Second Reader

Nicholas D.K. Petraco

Third Advisor

Craig Huemmer


Using the basic fundamentals of polarized light microscopy, a new and improved method for identifying synthetic fibers is presented in this thesis. Using the equation of an ellipse in spherical coordinates, an EXCEL™ (Microsoft Inc., Seattle, WA) spreadsheet was developed that generated tables of data that provide a foundation for a new and more efficient method in fiber analysis. Intermediate refractive index values for each subclass of textile fibers were calculated based on the fiber's principal refractive index values. The angles of refractive index matching to known refractive index fluids vary from 0 to 90 degrees upon rotation of the fiber in plain polarized light. Calculated angles were derived from the ellipse equation using spherical polar coordinates. If the mounting medium has an intermediate refractive index between the two principal refractive indices, there is a unique angle of rotation where the refractive index of the mounting medium will equal the refractive index of the fiber. Experimental validation was executed using a polarized light microscope. Examples are presented that demonstrate the utility of the combination of EXCEL™ and polarized light microscopy for improving the efficiency of forensic fiber identification.



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