The piecewise homogeneity approximation is used to investigate the
optical response of chiral sculptured thin films with perturbations
in the angle of rise. Changes in the reflectances and transmittances of normally incident, circularly polarized light are calculated for
both sinusoidal and step perturbations for a range of wavelengths, using experimentally determined material parameters. The feasibility of using a single manufacturing process to fabricate a normal dielectric mirror as well as a selective circular Bragg effect mirror is demonstrated.