Transmitted 20 Degrees Off Crossed Linear Polarized Light
Cotton comes from the fiber on the outside of the seeds of a number of species of the genus Gossypium. Gossypium hirsutum
is the most common commercial type of cotton. Other common commercial cotton species include arboreum, barbadense, and
herbaceum. There are also a number of hybrids used commercially.
Significance in the Environment:
This is a common clothing fiber.
Cotton has a refractive index along its length of about 1.56 to 1.59 and perpendicular to its length of about 1.52 to 1.54.
It has a birefringence of up to 0.05 and a positive sign of elongation. Cotton is typically a twisted ribbon in appearance
under the microscope but the frequency of the twists varies with maturity of the fibers, they species of fiber, and chemical
processing of the fiber (Mercerization). Mature cotton fiber of the species hirsutum has no extinction position. This
property varies in other species.
DuPont Company Techinical Bulletin X-156: IDENTIFICATION OF FIBERS IN TEXTILE MATERIALS, December 1961.