Characterization of single cotton fibers using a laser diffraction system

The fineness and maturity of a cotton fiber is determined by its cross-sectional perimeter and area. However, measuring fiber cross-sectional perimeter and area is an extremely tedious and challenging task. This paper presents an alternative approach to measure fiber longitudinal width using Fraunhofer diffraction patterns, which can be used to estimate fiber fineness and maturity. We designed a laser diffraction system, developed a software program to denoise and process diffraction patterns, and tested the system on a uniform iron wire and individual cotton fibers from ten bales. The width of the iron wire measured by our system was 25.43 μm (0.1% different from the nominal value) with a 0.01 μm standard error of the mean. Cotton fiber width measured by the laser diffraction system could differentiate among ten cotton bales, which was in accordance with their relative differences in fineness. Linear regression analyses revealed that strong linear relationships exist between the fiber width and cross-sectional perimeter and area (r 2 = 0.81 and 0.77, respectively), as well as between the fiber width and fineness and micronaire (r 2 = 0.79 and 0.73, respectively) (n = 10, p = 0.01). This simple, replicable, and relatively inexpensive optical system could be used for single fiber longitudinal profile characterization and cotton fineness and maturity estimation.