A New Optical Surface Measurement Method with Iterative Sparsity-Constrained Threshold Phase Retrieval Algorithm

Guo Li,Dahua Gao,Yang Liu,Guangming Shi,Yi Niu

doi:10.1155/2014/548395

Abstract

Due to its low complexity and acceptable accuracy, phase retrieval technique has been proposed as an alternative to solve the classic optical surface measurement task. However, to capture the overall wave field, phase retrieval based optical surface measurement (PROSM) system has to moderate the CCD position during the multiple-sampling procedure. The mechanical modules of CCD movement may bring about unexpectable deviation to the final results. To overcome this drawback, we propose a new PROSM method based on spatial light modulator (SLM). The mechanical CCD movement can be replaced by an electrical moderation of SLM patterns; thus the deviation can be significantly suppressed in the new PROSM method. In addition, to further improve the performance, we propose a new iterative threshold phase retrieval algorithm with sparsity-constraint to effectively reconstruct the phase of wave field. Experimental results show that the new method provides a more simple and robust solution for the optical surface measurement than the traditional techniques and achieves higher accuracy.

Highlights

The accuracy of optical surface is critical to the imaging system such as medical imaging, space telescope, and microscopic imaging
We propose a novel electrical phase retrieval based optical surface measurement (PROSM) solution based on spatial light modulator (SLM)
We proposed a new optical surface measurement solution with iterative sparsity constrained threshold phase retrieval algorithm

Summary

Introduction

The accuracy of optical surface is critical to the imaging system such as medical imaging, space telescope, and microscopic imaging. The work principle of PROSM is to reconstruct the phase information of the wave filed from the intensity measurements This procedure is mathematically a typical inverse problem. The author assumes that there exists a basis consisting of a small number of items where the phase of the wave field can be represented exactly or approximately with high accuracy Based on this assumption, the author proposes a 4f-setup based optical system that the phase can be retrieved effectively via a 4f Sparse Phase Amplitude Reconstruction (4f-SPAR) algorithm. Almost all the optical surfaces are smooth, and it can be assumed that the phase signals are sparse in frequency domain Relying on this assumption, we propose a novel iterative threshold phase retrieval algorithm with sparsityconstraint (ITPRS) to further improve the phase retrieval performance.

The System for Optical Surface Measurement

Experimental Results

Conclusions