27 January 2018 Surface topography measurement of plasma-facing materials by dual-wavelength phase-shifting speckle interferometry technique
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Abstract
A dual-wavelength phase-shifting speckle interferometry approach has been proposed to diagnose the topography of plasma-facing materials (PFMs) in tokamak. The conventional speckle interferometric surface measurement, which uses single-wavelength, can offer excellent vertical resolution, but limitation in measuring large height step and phase ambiguity would occur during their application. To solve the problem, a dual-wavelength method was developed. Experiments were conducted on molybdenum (Mo) sample, which is related to PFMs of experimental advanced superconducting tokamak (EAST), and a laser ablation method was adopted to simulate the erosion happed on PFMs. The laser ablation craters were measured by both single-wavelength and dual-wavelength phase-shifting speckle interferometry, and a multistep phase-shifting method has been investigated for their effectiveness on reducing noise in calculating the phase map. This work demonstrates the superiority of the dual-wavelength speckle interferometry and the feasibility of applying the measurement system in topographic measurement of PFMs in EAST.
© 2018 Society of Photo-Optical Instrumentation Engineers (SPIE)
Xiaoqian Cui, Xiaoqian Cui, Hongbei Wang, Hongbei Wang, Mengge Zhao, Mengge Zhao, Yuanbo Li, Yuanbo Li, Hongbin Ding, Hongbin Ding, } "Surface topography measurement of plasma-facing materials by dual-wavelength phase-shifting speckle interferometry technique," Optical Engineering 57(1), 014109 (27 January 2018). https://doi.org/10.1117/1.OE.57.1.014109 . Submission: Received: 5 September 2017; Accepted: 27 December 2017
Received: 5 September 2017; Accepted: 27 December 2017; Published: 27 January 2018
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