Error evaluation in reverse engineering of aspherical lenses

Abstract

This work presents a methodology to evaluate the reconstruction of the Computer-Aided Design (CAD) model in reverse engineering of an aspherical lens. A glass made lens is used as reference part for the measurements. The reconstruction of the CAD model is explained and the analysis of the deviations between data points measured on the lens surface and theoretical CAD model is presented. The theoretical model was developed through the measurement of data points on the profile of the part using a Coordinate Measuring Machine (CMM) Cantilever type having a probing uncertainty of 3.2 μm. A 10th order stepwise polynomial regression model was fitted to the data profile with Matlab software and the parameters K and R of the lens were determined by analyzing the aspherical theoretical equations. The uncertainty of these parameters was determined using GUM Supplement 1, Monte Carlo simulation. An additional analysis was carried out to compare the measured points against the CAD model generated with aspherical profile in Catia software.