Coherent beam combination far-field measuring method based on amplitude modulation and deep learning

Renqi Liu; Chun Peng; Xiaoyan Liang; Ruxin Li

doi:10.3788/COL202018.041402

Journals >Chinese Optics Letters >Volume 18 >Issue 4 >Page 041402 > Article

Chinese Optics Letters
Vol. 18, Issue 4, 041402 (2020)

Coherent beam combination far-field measuring method based on amplitude modulation and deep learning

Renqi Liu^1、2, Chun Peng¹, Xiaoyan Liang^1、3、*, and Ruxin Li^1、3、**

Author Affiliations

¹State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China

²Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China

³School of Physical Science and Technology, ShanghaiTech University, Shanghai 200031, China

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DOI: 10.3788/COL202018.041402 Cite this Article Set citation alerts

Renqi Liu, Chun Peng, Xiaoyan Liang, Ruxin Li. Coherent beam combination far-field measuring method based on amplitude modulation and deep learning[J]. Chinese Optics Letters, 2020, 18(4): 041402 Copy Citation Text

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Abstract

A deep convolutional neural network is employed to simultaneously measure the beam-pointing and phase difference of sub-beams from a single far-field interference fringe for coherent beam combining systems. The amplitudes of sub-beams in the measurement path are modulated in order to prevent measuring mistakes caused by the symmetry of beam-pointing. This method is able to measure beam-pointing and phase difference with an RMS accuracy of about 0.2 μrad and λ/250, respectively, in a two-beam coherent beam combining system.

Keywords

coherent beam combining deep learning pattern recognition

E_{n} (x, y) = A_{n} (x, y) \exp [j k (x \cos α_{n} + y \cos β_{n}) + j φ_{n} (x, y) + j ϕ_{n}],

(1)

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A_{n} (x, y) = A_{n} \exp [- \frac{{(x - x_{n})}^{2} + {(y - y_{n})}^{2}}{{(D / 2)}^{2}}] .

(2)

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I_{Σ} (u, v) \propto {| \sum_{n} \iint E_{n} (x, y) \exp [- j k (x u + y v) / f] d x d y |}^{2} .

(3)

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S R = \frac{{I_{Σ}}^{peak} (u, v)}{\sum_{n} {I_{n}}^{peak} (u, v)},

(4)

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L = {‖ Θ_{CNN} - Θ_{label} ‖}^{2} + γ^{2} {‖ Φ_{CNN} - Φ_{label} ‖}^{2},

(5)

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Renqi Liu, Chun Peng, Xiaoyan Liang, Ruxin Li. Coherent beam combination far-field measuring method based on amplitude modulation and deep learning[J]. Chinese Optics Letters, 2020, 18(4): 041402

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