Patent ID: 8422822
Filing Date: 2013-04-16
Classification: G01B,G01M,G01N

Abstract:
1. A deflectometry method for the optical inspection of a phase and amplitude object placed in an optical path between a single grating and an imaging system, at a distance h of the grating, wherein the grating forms a contrast-based periodic pattern with the spatial frequencies μ 0 , v 0 in, respectively, orthogonal axes x,y in an image plane, and the imaging system comprises an objective and an imaging sensor comprising a plurality of photosensitive elements, wherein this method comprises the step of: capturing through the objective, with the imaging sensor, a first image of said pattern distorted by the phase and amplitude object; and is characterised in that said spatial frequencies μ calculating a Fourier transform of said first image in a spatial frequency domain; selecting at least one first— or higher-order spectrum of said Fourier transform and shifting it in said frequency domain so as to substantially place it at a central frequency of said Fourier transform; and carrying out a reverse Fourier transform of said at least one shifted first- or higher-order spectrum of said Fourier transform so as to obtain a complex function g(x,y)=I(x,y)e