A fast-Fourier-transform method of topography and interferometry is proposed. By computer processing of a noncontour type of fringe pattern, automatic discrimination is achieved between elevation and depression of the object or wave-front form, which has not been possible by the fringe-contour-generation techniques. The method has advantages over moire topography and conventional fringe-contour interferometry in both accuracy and sensitivity. Unlike fringe-scanning techniques, the method is easy to apply because it uses no moving components.

Fourier-transform method of fringe-pattern analysis for computer-based topography and interferometry

Abrasive fine-finishing technology is often applied as a final finishing process, and the selection of the right technology is crucial to obtaining the desired performance of functions such as fatigue life. This paper begins with classifications of the technology along with fundamentals and brief histories of the individual methods. The material removal mechanisms, specific energies, and finishing characteristics of the various technologies are summarized giving assessments of the surfaces created by them. Guidelines developed for selecting the appropriate methods, and case studies illustrate the effectiveness of various methods. This paper ends with a discussion of the future prospects of the technology. (C) 2016

Abrasive fine-finishing technology

A method for null-testing fast convex aspheric optical surfaces is presented The method consists of using a cylindrical screen with a set of lines drawn on it in such a way that its image, which is formed by reflection on a perfect surface, yields a perfect square grid Departures from this geometry are due to imperfections of the surface, allowing one to know if the surface is close to the design shape Tests conducted with a full hemisphere and with the parabolic surface of a lens show the feasibility of the method Numerical simulations show that it is possible to detect surface departures as small as 5 microm

Null-screen testing of fast convex aspheric surfaces.

High Energy Fluid Jet Machining (HEFJet-Mach): From scientific and technological advances to niche industrial applications

Computer controlled polishing requires accurate knowledge of the tool influence function (TIF) for the polishing tool (i.e. lap). While a linear Preston's model for material removal allows the TIF to be determined for most cases, nonlinear removal behavior as the tool runs over the edge of the part introduces a difficulty in modeling the edge TIF. We provide a new parametric model that fits 5 parameters to measured data to accurately predict the edge TIF for cases of a polishing tool that is either spinning or orbiting over the edge of the workpiece.

/pdf/parametric-modeling-of-edge-effects-for-polishing-tool-2vtbcbyogp.pdf

Parametric modeling of edge effects for polishing tool influence functions.

In this paper, it is proven that for any optical system with a circular exit pupil and wavefronts affected by any aberrations, the borders of all leaving rays are caustic surfaces and/or marginal rays. Several examples are shown for wavefronts affected by linear combinations of Zernike aberrations.

Borders of spot diagrams are always caustic surfaces and/or marginal rays

Assuming that the measured coordinates of the fringes of an interferogram have random errors and that they are considered Gaussian, the system of normal equations that is obtained on application of the least-squares method is converted into a nonlinear set of equations. We present an algorithm to estimate the coefficients of the nonlinear system by applying the Newton–Raphson method and starting the iteration from the standard classic solution. This algorithm is applied to a pattern of straight and equally spaced fringes, obtaining not only the right coefficients but also the adequate election of the terms to be included in the model, to show the contrast with the results of the classic method.

Polynomial Fitting of Interferograms with Gaussian Errors on Fringe Coordinates. III. Nonlinear Solution.

In order to verity our computer simulations, we made and tested the behavior of a segmented spherical corrector ring for our scaled telescope (1/14.16). We increased the stop diameter from 12 cm (170 cm) to 15.53 cm (220 cm). And we have obtained the results that we had calculated, this means that the spot size can be kept with the aid of the spherical corrector rings even when the stop diameter is increased.

Segmented spherical corrector rings. 2: Experimental results

La source est un laser He−Ne et le reseau a 1200 sillons/mm et un angle de blaze de Littrow de 26°45'

Alberto Cordero-Dávila

Papers

Borders of spot diagrams are always caustic surfaces and/or marginal rays

Polynomial Fitting of Interferograms with Gaussian Errors on Fringe Coordinates. III. Nonlinear Solution.

Segmented spherical corrector rings. 2: Experimental results

Measurement of coating thickness with a multiple-beam grating interferometer

Fast and exact diffraction integral calculus: A comparison with fresnel approximation