We present a semiclassical perturbation method for the description of atomic diffraction by a weakly modulated potential. It proceeds in a way similar to the treatment of light diffraction by a thin phase grating, and consists in calculating the atomic wavefunction by mean~ of action integrals along the classical trajectories of the atoms in the absence of the modulated part of the potential. T...

Accurate and efficient prediction of the sound field in shadow zones behind obstacles is a challenging task but essential to produce urban noise maps. A simplified method is presented to predict sound levels at shielded urban locations, including multi-edge diffraction over successive buildings and multiple reflections between parallel façades. The model is essentially based on Pierce's diffrac...

The first and second Rayleigh-Sommerfeld diffraction theories, together with the Kirchhoff diffraction theory, are widely used in the formulation of optical diffraction problems [ 1 ]. They arise in the context of the half-space boundary-value problem of scalar wave theory; all sources of the optical field are assumed to be located in the Z~< 0 half-space, and the Z > 0 half-space is taken to b...

In many ocean regions the archipelagoes or even isolated islands provide shelter and this effect has an influence on the wave climate for coasts or ocean areas located in the shadow zones. Incident waves from the deep ocean are blocked by the island boundaries and are refracted over the island shoals. The wave energy is partially dissipated in surf zones or reflected back to the deep ocean. How...

Several semianalytical approaches are now available for describing diffraction of a plane wave by the 2D (two dimensional) traction free isotropic elastic wedge. In this paper we follow Budaev and Bogy who reformulated the original diffraction problem as a singular integral one. This comprises two algebraic and two singular integral equations. Each integral equation involves two unknowns, a fun...

We have demonstrated a novel diffraction grating for atoms. Acollimated beam of sodium atoms with a de Broglie wavelength of 17picometers was diffracted by transmission through an array of slitswith a spatial period of 0.2 μm formed in a gold membrane. This isthe first reported diffraction of atoms by a fabricated periodicstructure. Our transmission diffraction grating for a...

We report on the observation of emerging beam resonances, well known as Rayleigh-Wood anomalies and threshold resonances in photon and electron diffraction, respectively, in an atom-optical diffraction experiment. Diffraction of He atom beams reflected from a blazed ruled grating at grazing incidence has been investigated. The total reflectivity of the grating as well as the intensities of the ...

In this paper, radio wave propagation over irregular terrain is investigated in 200–600MHz (VHF/UHF band). Measured results are compared with different path loss models such as Fresnel knife edge diffraction and uniform theory of diffraction (UTD). It is shown that, for low antenna heights, using a combination of the two-ray path loss model and knife-edge diffraction, great improvement in path ...

A crucial issue in coherent x-ray diffraction imaging experiments is how to increase the signal-to-noise ratio when measuring relatively weak diffraction intensities from a nonperiodic object. A novel crystal guard aperture is described that makes use of a pair of multiple-bounce crystal optics to eliminate unwanted parasitic scattering background. This background is often produced by upstream ...