Date of Award
Master of Science (MS)
Nicholas D.K. Petraco
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.
Kaplan, Samuel F., "An Improved Method for the Analysis of Fiber Evidence Using Polarized Light Microscopy" (2018). CUNY Academic Works.