Three-dimensional reconstruction of refractive index inhomogeneities in optical phase elements

In this paper the quantitative approach to 3D reconstruction of refractive index inhomogeneity of static phase object is presented. The method combines multidirectional phase shifting interferometry technique with tomographic reconstruction. It is aimed on testing of optical material and elements with both symmetric and non-symmetric refractive index distributions. The optimisation of the parameters used in filtered backprojection reconstruction algorithm is performed in order to maximise the overall accuracy of measurement. Experiments are performed to verify the methodology and parameters obtained from optimisation procedure. The results prove high performance of the proposed measuring procedure. (C) 2002 Elsevier Science Ltd. All rights reserved.