Surface roughness and tolerances in model scattering experiments

A problem of importance in model scattering work is the extent to which requirements on tolerance and surface finish can be relaxed before affecting the accuracy of measured scattering data. The consequences of minor shape perturbations are examined by considering several different types of scattering contribution, and a brief discussion of roughness is presented. The results are translated into criteria on tolerance and surface finish and it is concluded that accuracies of
10^{-3}
of a wavelength should be sufficient for all practical purposes. Some experimental data on spheres and cone-spheres of varying degrees of roughness are presented for comparison.