Study of Monitoring Parameters for Coherent Beam Combination through Fourier-domain Analysis of the Speckle Image

Jaedeok Park, Yunjin Choe, Dong-Il Yeom

doi:10.3807/KJOP.2020.31.6.268

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Study of Monitoring Parameters for Coherent Beam Combination through Fourier-domain Analysis of the Speckle Image 스펙클 이미지의 푸리에 공간 분석을 통한 결맞음 빔결합 상태 모니터링 변수 도출

25 December 2020. pp. 268-273

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Abstract

레이저 빔이 산란 매질에서 반사될 때 발생하는 스펙클 패턴을 모니터링함으로써 산란 매질에 입사하는 레이저 빔들의 결맞는 (coherent) 결합 상태를 분석하고자 하였다. 이를 위하여 가간섭성이 높은 3개의 시준 레이저 광원을 자유공간에서 렌즈를 이용하여 무작위 표면특성을 가진 산란목표물(scattering target)에 집속한 후, 되돌아오는 빔의 스펙클 패턴을 푸리에 영역에서 살펴보았다. 목표물에 입사하는 단일 레이저 빔의 크기변화 및 3개 결맞는 레이저 빔 간의 공간적인 빔결합 정도에 따라 스펙클 패턴의 평균적인 크기가 변하게 되는데, 이를 푸리에 영역에서 분석함으로써 결맞음 빔결합의 효율을 판별할 수 있는 단일 모니터링 변수를 도출할 수 있었다.

키워드

광섬유 레이저

레이저 빔 결합

광 결맞음 효과

스펙클

We analyze the characteristics of the coherent beam combination of lasers by monitoring the speckle pattern of the beam reflected from a scattering medium. Three collimated laser sources with high coherence are focused on a scattering target using a lens, and we then examine the speckle pattern of the returned beam in the Fourier domain. We observe that the size of the speckle pattern changes, depending on the focused-beam size or degree of spatial overlap of the three beams. Furthermore, through Fourier-domain analysis of the speckle pattern we obtain the monitoring variable to qualify the efficiency of the coherent beam combination.

Keywords

Fiber lasers

Laser beam combination

Coherence optical effects

Speckle effect

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Information

Publisher :Optical Society of Korea
Publisher(Ko) :한국광학회
Journal Title :Korean Journal of Optics and Photonics
Journal Title(Ko) :한국광학회지
Volume : 31
No :6
Pages :268-273
Received Date :2020. 10. 13
Revised Date :2020. 11. 02
Accepted Date : 2020. 11. 04
DOI :https://doi.org/10.3807/KJOP.2020.31.6.268

Korean Journal of Optics and Photonics ISSN:1225-6285(Print) 2287-321X(Online) 한국광학회지

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