These fibers are ribbon shaped in cross-section as can be seen by the broad, uniform central retardation color
shown by most of the fibers. The fiber at the extreme left is bilobate in cross-section as can be seen by the double bump in the interference
pattern formed where it crosses the horizontal fiber. The flattened fibers are about seven micrometers thick and are showing third and forth
Transmitted Crossed Circular Polarized Light
Nomex is an meta-Aramid fiber. It is known for its high temperature stability and is used as a heat-protection clothing fiber.
Significance in the Environment:
Nomex has refractive indices o about 1.67 perpendicular and 1.89 parallel, giving a birefringence of 0.22. Only Kevlar has a higher
birefringence among the synthetic fibers.
Gorski, Azriel and Walter C. McCrone, "Birefringence of fibers", THE MICROSCOPE, vol. 46, no. 1, pp. 3-16