We consider the coherent superposition of unfocused wave fronts for lensless focusing of electromagnetic waves with subwavelength resolution. Near the focal point, intensity distributions generated using the approach approximate those generated using lenses. Far from the focal point, discretization of spatial frequencies results in a trade-off between the number of wave fronts and the accuracy ...

We present a technique for rapid capture of high quality bidirectional reflection distribution functions(BRDFs) of surface points. Our method represents the BRDF at each point by a generalized microfacet model with tabulated normal distribution function (NDF) and assumes that the BRDF is symmetrical. A compact and light-weight reflectometry apparatus is developed for capturing reflectance data ...

Reflection energy from a linear reflector comes from an integrant over an aperture often described by the Fresnel zone. Within the Fresnel zone, the diffraction energy constructively builds the reflection energy. This paper uses diffraction theory to explain the reflector edge effect on amplitude and the amplitude variation within the Fresnel zone. Thus, discuss the Fresnel zone effect for AVO ...

Photovoltaic (PV) devices are spectrally selective, and their performance is influenced by unavoidable spectral variations. In addition, multijunction-based concentrating photovoltaic (CPV) devices show a strong spectral dependence due to the series connection of various junctions with different absorption bands, and also due to the use of concentrator optics. In this work, the accuracy of a ne...

The fresnel lens can be used in a wide variety of applications. The basic principles of the fresnel lens are reviewed and some practical examples are described. There are definite advantages and tradeoffs that should be considered when deciding if a fresnel lens is the appropriate component to use in a design. Some basic optimization rules are presented which may facilitate a first order design...

Telecentric optical computed tomography (optical-CT) is a state-of-the-art method for visualizing and quantifying 3-dimensional dose distributions in radiochromic dosimeters. In this work a prototype telecentric system (DFOS-Duke Fresnel Optical-CT Scanner) is evaluated which incorporates two substantial design changes: the use of Fresnel lenses (reducing lens costs from $10-30K t0 $1-3K) and t...

purpose : to compare visual quality in patients receiving alcon acrysof restor multifocal versus acrysof sa60at monofocal intraocular lenses (iol) methods : in this interventional study, patients with senile cataract undergoing surgery were enrolled. the age of the patients ranged between 40 and 85 years, and their potential preoperative vision was 20/30 or better. in all patients phacoemulsifi...

Solar-powered desalination holds the potential to meet rising water needs. Most of global methods require a lot electrical energy that mostly comes from non-renewable resources, including coal, natural gas, and oil. Carbon emissions these sources cause breathing problems ozone depletion. An empirical study is performed evaluate optically active process. The suggested mechanism moves light funne...