A modified Hartmann test for testing aspherical convex surfaces of F/# 1 is analyzed. We present the main differences of this test in comparison to the usual Hartmann test. Theoretical results show that the transverse aberrations yielded by a testing surface have to be measured with respect to its mean sphere. A method to determine the mean sphere is also presented. Experimental results show th...

We present a robust, dense, and accurate Shack-Hartmann spot dislocation map determination method based on a regularized optical flow algorithm that does not require obtaining the spot centroids. The method is capable to measure in presence of strong noise, background illumination and spot modulating signals, which are typical limiting factors of traditional centroid detection algorithms. Moreo...

Most Shack-Hartmann based aberrometers use infrared light, for the comfort of the patients. A large amount of the light that is scattered from the retinal layers is recorded by the detector as background, from which it is not trivial to estimate the centroid of the Shack-Hartmann spot. For a centroiding algorithm, background light can lead to a systematic bias of the centroid positions towards ...

In this paper, we present a numerical study of turbulent natural-convection in square cavity differentially heated and filled with nanofluid subjected to an inclined magnetic field. The standard k-? model was used as the turbulence model. transport equations were discretized by finite volume method using SIMPLE algorithm. influence Rayleigh number, Hartmann orientation angle applied field, type...

Thermal transport characteristics of Casson nanofluid through a porous microtube is analyzed under the effect streaming potential and constant pressure gradient with electrokinetic associated applied magnetic field. An analytical solution velocity temperature distribution Casson-nano fluid related to combining effects electromagnetohydrodynamics forces have been obtained. The significant influe...

The aim of this paper is to investigate the effect of the variable thermal conductivity and the inclined uniform magnetic field on the plane Poiseuille flow of viscous incompressible electrically conducting fluid between two porous plates Joule heating in the presence of a constant pressure gradient through non-uniform plate temperature. It is assumed that the fluid injection occurs at lower pl...

A least-squares procedure to find the tilts, curvature, astigmatism, coma, and triangular astigmatism by means of measurements of the transverse aberrations using a Hartmann or Shack-Hartmann test is described. The sampling points are distributed in a ring centered on the pupil of the optical system. The properties and characteristics of rings with three, four, five, six, or more sampling point...

A variety of approaches to wavefront sensing and reconstruction are surveyed as they are used in adaptive optics and related applications. These include the Gerchberg-Saxton algorithm; shearing interferometry; and Shack-Hartmann, curvature, and pyramid wavefront sensing. Emphasis is placed on the relevant optics and mathematics, which are developed in some detail for Shack-Hartmann and curvatur...

In this study, Entropy generation in MHD convective flow past a flat porous oscillating plate with suction or injection are presented for an unsteady, one-dimensional of viscous incompressible fluid. The importance is noticed industrial and scientific fields including heat transfer thermal systems which includes dissipation, chemical reaction, mass transfer, electrical conduction etc. role para...