Researchers developed a method to accurately measure the temperature of manmade fibers during exposure to laser radiation. An experiment exposed vacuum annealed polycaproamide (PCA) fibers to a LNGN-701 carbon dioxide laser that was tuned to a vavelength of 10.6 microns. The PCA fibers had a linear density of 190 tex, a breading stress in excess of 1.0 gigapascal, a breaking elongation of 15.6 percent, and an initial modulus of 10.0 gigapascals. The PCA fibers moved at variable speeds along the axis of the goniometer of a DRON-2 X-ray diffractometer that was equipped with a specially designed winding module. Results indicated that increases in temperature were not only governed by the energy flux density of the laser beam, but also by the winding speed. Interplanar distances within the molecular structure of the PCA fibers reached a maximum as the energy flux density of the laser beam increased, and thereafter remained constant. The researchers concluded that manmade fiber manufacturers could optimize specific fiber treatment processes--solvent removal, dehydration, diffusion of impurities, or recrystallization--by adjusting the winding speed during laser irradiation. 12 refs.