“…Incorporation of correlated lattice distortions into a model of polycrystalline fibers, and calculation of associated diffraction patterns, is the subject of this paper. Two models of lattices with correlated distortions are the paracrystal (Hosemann & Bagchi, 1962) and the perturbed lattice (Welberry, Miller & Carroll, 1980;Welberry & Carroll, 1982, 1983. In the paracrystal model, a distorted lattice is generated by replacing vectors that form the edges of the unit cell of a periodic lattice with vectors that vary in both length and direction.…”