Algorithm improvement for the surface morphology diagnostics based on the Gram-Schmidt orthonormalization and the least square ellipse fitting under the EAST-like vibrational environments

• DOI: 10.1016/j.nme.2023.101397
• Publication Date: 2023-02-28T16:50:03Z
• Authors: Yuanbo Li; Xiaoqian Cui; Chunlei Feng; Hongbei Wang; Hongbin Ding
• Keywords: Ellipse; Square (algebra)

To realize in situ surface morphology diagnosis of Plasma-Facing Materials (PFMs) the Experimental Advanced Superconducting Tokamak (EAST), a diagnostic system which is called DUT-SIEP (Speckle Interferometry Experiment Platform Dalian University Technology) development. Mimicking actual vibrational conditions EAST, Dual-wavelength Phase-Shifting (DPSI) should be sensitive to environment and would reduce accuracy measurements. Therefore, an approach combining Gram–Schmidt orthonormalization Least-Square Ellipse Fitting (GS-LSEF) was proposed replace conventional phase extraction process improve measurement EAST-like vibration conditions. The new only requires two interferograms at each wavelength while method needs three least for wavelength. This significantly reduces errors acquisition processes. performed correct shift determine elliptic coefficients. In Fitting, coefficients are used compensate from disturbed background intensity. can efficiency avoid infinite loops caused by numeric divergent. verified laser ablation on tungsten (W) material simulating erosion-processes EAST. Results show that has improved approximately twofold comparing with those convenient Four-step phase-shifting approaches due reducing noise superposition problems