Anisotropic focusing by a mesoscopic (Mie size parameter of about 18) acoustic cubic lens based on V-shaped plate structures has been simulated numerically and confirmed experimentally. It shown for the first time that this with an edge dimension three wavelengths ensures wave in air into diffraction-limited region. In inverse geometry structure, completely reflects incident wave.

In extra-capsular extraction of cataract in which the central portion of the anterior capsule is removed, or in injury of the lens, or in discission operations in which the anterior capsule is torn and the central portion of the lens substance is penetrated and becomes absorbed, a greater part of the capsule sac remains intact. According to Wessely (1910), when the central part of the anterior ...

The redshifts of lens galaxies in known gravitational lens systems probe the volume distribution of lensing mass. Following earlier work by Kochanek, we re-derive the lens redshift probability distribution, allowing for mass and number density evolution of the lensing galaxies, and apply this test to a much enlarged sample of lens systems. From a literature survey of all known lenses, we have s...

We report redshifts in two gravitational lens systems, MG 0414+0534 and MG 0751+2716. The lens galaxy in MG 0414+0534 lies at zl = 0.9584± 0.0002. The luminosity and extreme red color of the lens are then typical of a passively evolving, early-type, ∼ 2L∗ galaxy. The galaxy cannot have a significant global mean extinction without being anomalously luminous. The lens galaxy in MG 0751+2716 has a...

It is generally assumed that correcting chromatic aberrations in imaging requires optical elements. Here, we show by allowing the phase image plane to be a free parameter, it possible correct variation of focal length over an extremely large bandwidth, from visible (Vis) longwave infrared (LWIR) wavelengths using single diffractive surface, i.e., flat lens. Specifically, designed, fabricated an...

Null lenses are designed for testing the oblate elliptical surface that is the third mirror of the off-axis three-mirror anastigmatic camera used for remote sensing. Modifying the conventional autostigmatic and autocollimation types of null lenses yields a mixed-type design that has a small annular flat mirror and high sensitivity. Detailed analyses of the sensitivity of the mixed-type null len...

We review the intensively discussed ideas about wave propagation and refraction in media where both electric permittivity and magnetic permeability are negative. The criticism against negative refraction as violating the causality principle is considered. Starting from the initial wave equations, refraction of beams at the boundary of a left-handed medium is analyzed. The physics of a perfect l...

Calculations are described of the elastic stress, strain, and surface displacement for a high-pressure optical window consisting of a transparent cylinder which is supported on a flat seat with an axial hole (Poulter window). Under pressure the window is compressed, and its outside surface bulges through the hole in the support. The net optical effect is to create a weak positive lens and to in...

A multiple-beam interferometer that permits evaluation of autostigmatic systems is described. A small reference sphere is compared with a spherical wavefront in a manner analogous to the comparison of a plane wavefront with the reference flat in a Fizeau interferometer. To prevent walk-off of the fringes, a field lens is used at the center of curvature of the reference sphere. The instrument de...

Potentialities of 2.5D dielectric photonic crystals for subwavelength imaging or invisibility cloaking operation at optical wavelengths are studied numerically and experimentally. First, a negative refraction based flat lens is designed, fabricated and characterized. Using scanning near-field optical microscopy, subwavelength imaging (0.8λ) for a deduced refractive index of −1 is obtained at 1....