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Turbulent effects are very complicated and still not entirely understood. Light waves from an astronomical object are distorted as they pass through the atmosphere. The refractive index fluctuations in the turbulent atmosphere induce an optical path difference (OPD) between different parts of the wavefront, distorted wavefronts produce low-quality images and degrade the image beyond the diffraction limit. In this paper the image degradation due to 2-D Gaussian atmospheric turbulence is considered in terms of the point spread function (PSF), and Strehl ratio as an image quality criteria for imaging systems with different apertures using the pupil function teqneque. A general expression for the degraded PSF in the case of circular and square apertures (with half diagonal..., and 1) diffraction limited and defocused optical system is considered. Based on the derived formula, the effect of the Gaussian atmospheric turbulence on circular and square pupils has been studied with details. Numerical results show that the performance of optical systems with square aperture is more efficient at high levels of atmospheric turbulence than the other apertures. [ABSTRACT FROM AUTHOR]

None of optical devices is perfect. Each lens has some errors, e.g. tilt, coma, spherical or chromatic aberration. The more lenses are in the optical device the more errors can reveal. All these imperfection accumulates and multiplies during the path through the optical device. It is necessary to know how the light passes through and interacts with each optical element. There are some possibilities of simulation of these defects. One of these methods is ENZ (Extended Nijboer-Zernike) theory which can be set up for different light condition and different aberration. There is also possibility to measure this property. As will be shown in this article I made this experiment using microscope and microscopic objects as an example of optical device with more lenses and optical elements. Measurements in combination with image analysis (entropy calculation) and 3D reconstruction give us overview of distortions which undergoes the original image. Results of both methods simulation and measurements can be used for improving of the original image. If we know how the image is distorted the knowledge of PSF (Point Spread Function) can help us to remove this distortion and obtain better image. This can be done using deconvolution function and the known PSF as a kernel for this function. Using simulations and PSF measurements can also help to improve resolution of the image and reveal more details. This can be helpful in many different fields, for example in biology, astronomy or in analysis of satellites or aerial photos. [ABSTRACT FROM AUTHOR]

A 2.5 kW peak, CPV demonstrator and testing facility has been deployed in Ottawa, Canada's northern climate (45.45°N, 75.62°W). In order to analyze the most important influences on overall system performance, the demonstrator was fully instrumented and a versatile system model was developed. Three inputs are currently evaluated in the model: spectral variation throughout the day, an optical transfer function (OTF) of the concentrating optics and the solar cell external quantum efficiency (EQE). The model has shown that the introduction of an OTF that absorbs/scatters light across the spectrum and cuts off wavelengths below 400 nm shifts the entire system efficiency curve down and its peaks to lower air mass (AM) values. [ABSTRACT FROM AUTHOR]

We present an optical configuration for phase retrieval from a sequence of intensity measurements. The setup is based on a 4f-configuration with a phase modulating spatial light modulator (SLM) located in the Fourier domain. The SLM is used to modulate the incoming light with the transfer function of propagation, thus a sequence of propagated representations of the subjected wave field can be captured across a common sensor plane. The main advantage of this technique is the greatly reduced measurement time, since no mechanical adjustment of the camera sensor is required throughout the measurement process. The treatise is focused on the analysis of the wave field in the sensor domain. From the discussion a set of parameters is derived in order to minimize disturbing effects arising from the discrete nature of the SLM. Finally, the big potential of this approach is demonstrated by means of experimental investigations with regard to wave field sensing. [ABSTRACT FROM AUTHOR]

We present a novel approach to investigate the shape of a diffusely reflecting technical object. It is based on a combination of a multiple-illumination contouring procedure and phase retrieval from a set of intensity measurements. Special consideration is given to the design of the experimental configuration for phase retrieval and the iterative algorithm to extract the 3D phase map. It is mainly based on a phase-only spatial light modulator (SLM) in the Fourier domain of a 4f-imaging system. The SLM is used to modulate the light incident in the Fourier plane with the transfer function of propagation. Thus, a set of consecutive intensity measurements of the wave field scattered by the investigated object in various propagation states can be realized in a common recording plane. In contrast to already existing methods, no mechanical adjustment is required during the recording process and thus the measuring time is considerably reduced. The method is applied to investigate the shape of micro-objects obtained from a metalforming process. Finally, the experimental results are compared to those provided by a standard interferometric contouring procedure. [ABSTRACT FROM AUTHOR]

This paper describes an automatic methodology for optimizing sample point selection for using in the framework of model order reduction (MOR). The procedure, based on the maximization of the dimension of the subspace spanned by the samples, iteratively selects new samples in an efficient and automatic fashion, without computing the new vectors and with no prior assumptions on the system behavior. The scheme is general, and valid for single and multiple dimensions, with applicability on rational nominal MOR approaches, and on multi-dimensional sampling based parametric MOR methodologies. The paper also presents an integrated algorithm for multi-point MOR, with automatic sample and order selection based on the transfer function error estimation. Results on a variety of industrial examples demonstrate the accuracy and robustness of the technique. [ABSTRACT FROM AUTHOR]

Task of this work is theoretical and experimental investigation of the optical properties and optical transitions in BiSel crystals in antiferroelectric phase (T = 295K). In the current paper we have calculated (DFT) and measured (optical reflectance ellipsometry) the dielectrics constants spectra of BiSel crystals. The theoretical and experimental imaginary dielectric constants were compared. Experimental spectra of the constants were analyzed considering that spectra structure consists of four Laurence lines sum. The Laurence line parameters are obtained by minimization using the mean-square method of the difference between the calculated and measured spectra of the dielectric constants. [ABSTRACT FROM AUTHOR]

In this paper, we propose an efficient direct method that estimates pure translation motion parameters in dynamic scenes. We develop an algorithm that computes, directly, phase information in Fourier domain. The computations are locally performed and limited to small patches of the image. The local measurement of motion parameters are then combined in a more global interpretation by using parametric images. We demonstrate the performance of our algorithm on synthetic and real image sequences and compare our results with those of two other algorithms based on the Hough transform and the inverse Fourier transform. [ABSTRACT FROM AUTHOR]

Integral Imaging is a very promising technique in three-dimensional imaging, however it still suffers from some limitations. One of them is the impossibility of imaging objects with large depth. In this paper we present how to increase the depth of focus of this kind of systems. To this aim we use an asymmetric phase mask. We present numerical simulations that show the feasibility of our proposal. [ABSTRACT FROM AUTHOR]

We present a method for analyzing spatially resolved fields in multilayer meta-materials by combining plane-wave decomposition with multilayer matrix theory and we show that optical effects like sub-lambda imaging by a planar lens layer are treated accurately for finite diameter beams and can be interpreted by Fourier optical system analysis. [ABSTRACT FROM AUTHOR]

The ambiguity function and the Wigner distribution function have both been applied in the optical area for many years. Later, the fractional Fourier transform has also been used. The connection between the ambiguity function and the defocused optical transfer function has also been described. Here we consider the connections with the generalized optical transfer function, first proposed in 1965, which is a two (three) dimensional optical transfer function for the two (three) dimensional case. The two dimensional form can be used as the basis for phase retrieval algorithms, but is also valid in the non-paraxial domain. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The performance of the conventional low-energy CD-SEM is limited by the aberrations inherent in the probe forming lens. Multi-pole correctors are now available which can reduce or eliminate these aberrations. An SEM equipped with such a corrector offers higher spatial resolution and more probe current from a given electron source, and other aspects of the optical performance are also improved, but the much higher numerical aperture associated with an aberration corrected lens results in a reduction in imaging depth of field. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

The electronic and optical transfer properties of Benzene, Benzoic Acid (BA), Nitrobenzene (NB) and Para Nitro Benzoic Acid (PNBA) at ground and first excited state has been investigated by the Density functional theory (DFT)and Time Dependent Density Functional Theory (TDDFT) using SVWN functional/3-21G basis set respectively. Possible intra-molecular charge transfer and n to π* transitions in the ground and the first excitation states have been predicted by the molecular orbitals and the Natural Bond Orbital (NBO) analysis. The simulated absorption spectra have been generated and the result compared with existing experimental results. [ABSTRACT FROM AUTHOR]

Redundancy is an important property of Cantor diffractals. It allows for a faithful reconstruction of the Cantor grating by an inverse Fourier transformation of any of the secondary bands which occur in the diffraction pattern. Experimental verification of our observation using SLM are presented. [ABSTRACT FROM AUTHOR]