Phase retrieval applied to coherent Fourier scatterometry using the extended ptychographic iterative engine

P Dwivedi,S F Pereira,J E H Cardoso Sakamoto

doi:10.1364/osac.2.001590

Abstract

We have demonstrated that the extended ptychographic iterative engine (ePIE) algorithm can be applied to retrieve the phase information of the vectorial scattered field of a subwavelength object with the amplitude of the scattered field as input. We applied this technique combined with coherent Fourier scatterometry to determine the phase of the scattered field of a subwavelength grating, illuminated by a focused laser beam.

Highlights

In this paper, we combine Coherent Fourier Scatterometry (CFS) with ptychography to determine the amplitude and phase of the scattered field from a subwavelength object using only far field intensity measurements
The paper is organized as follows: in Section 1 we introduce the general ptychography method (Ptychography Iterative engine, ptychography iterative engine (PIE)) and the extended Ptygrography Iterative Engine, with the latter being the method that we have used to reconstruct the phase and amplitude of the scattered field
We start by explaining how the ptychographic iterative Engine (PIE) works followed by the extended PIE (e-PIE)

Summary

Introduction

We combine CFS with ptychography to determine the amplitude and phase of the scattered field from a subwavelength object using only far field intensity measurements. The paper is organized as follows: in Section 1 we introduce the general ptychography method (Ptychography Iterative engine, PIE) and the extended Ptygrography Iterative Engine (ePIE), with the latter being the method that we have used to reconstruct the phase and amplitude of the scattered field. Hoppe reconstructed an object using two far-field intensity measurements corresponding to two different illumination settings. The far-field intensity pattern is recorded and using these measurements, the object’s complex-valued transmission function is computed iteratively. We start by explaining how the ptychographic iterative Engine (PIE) works followed by the extended PIE (e-PIE). The latter is the method we have used for the reconstruction.

Methods

Results

Conclusion