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Advances in Condensed Matter Physics
Volume 2018, Article ID 2545923, 6 pages
https://doi.org/10.1155/2018/2545923
Research Article

Characteristics of Local Modulation Beam Propagating through Spatial Filter System

1Shanghai Institute of Optics and Fine Mechanics, Key Laboratory of High Power Laser and Physics, Chinese Academy of Sciences, Shanghai 201800, China
2National Laboratory on High Power Laser and Physics, Shanghai 201800, China
3University of Chinese Academy of Sciences, Beijing 100049, China

Correspondence should be addressed to Jianqiang Zhu; nc.ca.cnchs.liam@uhzqj

Received 5 February 2017; Revised 22 March 2017; Accepted 13 April 2017; Published 1 January 2018

Academic Editor: Jörg Fink

Copyright © 2018 Kewei You et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

As local defects may significantly harm beam quality and affect safe operation, a systematic analysis of the ability of a spatial filter to alleviate these adverse effects is required. Thus, the evolutional characteristics of a beam modulated by a local defect propagating through a spatial filter system at an image reply plane and a downstream plane are analyzed in detail. Modulation stripes appear at the image reply plane; these are caused by the pinhole cutoff effect. The modulation degree increases with increasing defect size. The maximum intensification factor can reach 3.2 under certain conditions. Thus, the defect size should be restricted to a reasonable size for safe operation with a specified pinhole size. Moreover, a maximal value appears at the downstream plane, and the intensity enhances with increasing defect size. To ensure beam quality, the maximum allowable defect size and angle of the spatial filter should meet special constraints. The maximum allowable defect size is calculated based on practical configuration parameters.