Alberto Cordero-Dávila

Bio: Alberto Cordero-Dávila is an academic researcher from Benemérita Universidad Autónoma de Puebla. The author has contributed to research in topics: Ronchi test & Conic section. The author has an hindex of 11, co-authored 52 publications receiving 401 citations.

Ronchi and Hartman tests: a null Hartman test

Abstract: From a study about the relations between the Ronchi and Hartmann tests; a null Hartmann test is proposed.

Dragging force and astigmatic surface in commercial polishing machines

Abstract: It is well known that astigmatic surfaces are obtained when surfaces are polished in commercial polishing machines, which are designed to produce surfaces of revolution. The authors of this paper do not know an explanation for this result. In order to understand why the wear is a function of the angular position on the glass, we measured the dragging force applied from a rotating glass to a small fixed tool of Teflon®. These experiments were done for several tool radial positions by using a table travel X-Y. With the aid of a force sensor dragging force as a function of the time was measured. We found that dragging force is a periodic function with fundamental frequency equal to the angular velocity of the glass, indicating that there is more wear on one glass angular position than another. We also found that this result is independent of the radial position of the tool. We used a polisher concentration of 20 degrees Baume which is recommended by the supplier. And the amount of polisher per time and area units, dragged by the tool, remained constant for each one of the radial positions of the tool.

Experimental results and wear predictions with free-pinned petal tools

Abstract: The wear produced by free-pinned tools is difficult calculate, since their angular movement is not entirely predictable. First, we analyze the wear produced with free-pinned ring tools using both simulations and experiments. We conclude that the wear of an incomplete ring is directly proportional to its angular size, independently from the mean radius of the ring. Second, we present an algorithm for the calculation of the wear produced by free-pinned petal tools, since they can be considered as a linear combination of incomplete free-pinned ring tools. Finally, we apply this result to the enhancement of a defective flat surface and to aspherate a concave spherical surface.

Model for frictional forces to reproduce the dragging forces in the polishing process

Abstract: Dragging forces exerted on a fixed Teflon tool, for several relative velocities of the tool center and polisher densities were measured. Therefore a model for frictional forces that reproduces the dragging forces results is described

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

Abstract: 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.

Abrasive fine-finishing technology

Abstract: 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

Null-screen testing of fast convex aspheric surfaces.

Abstract: 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

Parametric modeling of edge effects for polishing tool influence functions.

Abstract: 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.