title: Physical optics solution for the scattering of a partially-coherent wave from a statistically rough material surface.
abstract: The scattering of a partially-coherent wave from a statistically rough material surface is investigated via derivation of the scattered field cross-spectral density function. Two forms of the cross-spectral density are derived using the physical optics approximation. The first is applicable to smooth-to-moderately rough surfaces and is a complicated expression of source and surface parameters. Physical insight is gleaned from its analytical form and presented in this work. The second form of the cross-spectral density function is applicable to very rough surfaces and is remarkably physical. Its form is discussed at length and closed-form expressions are derived for the angular spectral degree of coherence and spectral density radii. Furthermore, it is found that, under certain circumstances, the cross-spectral density function maintains a Gaussian Schell-model form. This is consistent with published results applicable only in the paraxial regime. Lastly, the closed-form cross-spectral density functions derived here are rigorously validated with scatterometer measurements and full-wave electromagnetic and physical optics simulations. Good agreement is noted between the analytical predictions and the measured and simulated results.
authors.affiliation: Air Force Institute of Technology, 2950 Hobson Way, Dayton, OH 45433, USA. milo.hyde@afit.edu
authors.forename: Milo W
authors.initials: MW
authors.lastname: Hyde
authors.forename: Santasri
authors.initials: S
authors.lastname: Basu
authors.forename: Mark F
authors.initials: MF
authors.lastname: Spencer
authors.forename: Salvatore J
authors.initials: SJ
authors.lastname: Cusumano
authors.forename: Steven T
authors.initials: ST
authors.lastname: Fiorino
mesh_terms: D003198:Computer Simulation; D008027:Light; D008420:Manufactured Materials; D008962:Models, Theoretical; D010783:Photometry / Q000379:methods*; D017785:Photons; D012542:Scattering, Radiation; D013499:Surface Properties