For analyzing diffraction gratings, a new method is developed based on dividing one period of the grating into homogeneous subdomains and computing the Neumann-to-Dirichlet (NtD) maps for these subdomains by boundary integral equations. For a subdomain, the NtD operator maps the normal derivative of the wave field to the wave field on its boundary. The integral operators used in this method are...

The propagation and transmission of Bessel beams through nano-layered structures has been discussed recently. Within this framework we recognize the formation of unguided diffraction-free waves with the spot size approaching and occasionally surpassing the limit of a wavelength when a Bessel beam of any order n is launched onto a thin material slab with grazing incidence. On the basis of the pl...

X-ray diffraction from crystal surfaces at grazing angles gives rise to X-ray standing waves above and below the surface. Expressions are derived for the fluorescence observed from atoms located on or in a crystal as a result of excitation by the grazing-angle X-ray standing waves. In addition to the dependence of the fluorescence on the position of the atom with regard to the crystal plane tha...

Objective: To calculate wave response in an offshore or coastal harbor of arbitrary shape, this research develops a two-dimensional linear, inviscid, dispersive, hybrid finite element harbor resonance model using conservation of energy approach. Based on the mild-slope wave equation, the numerical model includes wave refraction, diffraction, and reflection. The model also incorporates the effec...

Talbot and Talbot-Lau effects are frequently used in lensless imaging applications with light, ultrasound, x-rays, atoms and molecules--generally in situations where refractive optical elements are non-existent or not suitable. We here show an experimental visualization of the intriguing wave patterns that are associated with near-field interferometry behind a single periodic diffraction gratin...

A deterministic model for spherical wave propagation in microcellular urban environment is presented. This methodis based on ray tracing and uniform theory of diffraction. The various ray contributions includes the diffraction from corner of obstacle, reflection from ground and direct wave. According to the height of transmitting station, different ray paths will be presented in the received si...

Recently, we have proposed a coherent diffractive imaging using a noniterative phase retrieval method with the filter of an aperture array. The first (to our knowledge) experimental demonstration of this coherent imaging is presented here, in which a complex-valued object illuminated by a diode laser is reconstructed from the isolated diffraction intensities of the object's wave field, transmit...

The diffraction of an inhomogeneous plane wave by an impedance wedge embedded in a lossy medium is analyzed. The rigorous integral representation for the field is asymptotically evaluated in the context of the uniform geometrical theory of diffraction (UTD) so that the asymptotic expressions obtained can be employed in a ray analysis of the scattering from more complex edge geometries located i...

In this paper we derive an expression for the point source Green's function for the reduced wave equation, valid in an angular sector whose angle is equal to a rational multiple of 77. This Green's function can be used to find new expressions for the field produced by the diffraction of a spherical wave by a wedge whose angle can be expressed as a rational multiple of n. The expressions obtaine...

n January 1986 a review article on T phase-locked arrays of diode lasers was published in this magazine. Now, more than a decade later, major breakthroughs have occurred, both in theory and experiment, that have allowed phase-locked arrays to meet their promise of reliable, highcontinuous-wave (CW) power (= 0.5W) operation in diffraction-limited beams as well as multiwatt (5-10 W) near-diffract...