3D Gradient-Index Reconstruction of a GRIN Lens by combining the Transport-of-Intensity Equation and the Filtered Back-Projection Algorithm

The Transport-of-Intensity Equation (TIE) method and the Filtered-Back Projection algorithm are combined to obtain the refractive index profile of a GRID lens of 1.8mm in diameter. The proposed technique does not need phase unwrapping to retrieve the phase information of a thick sample.