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Fused-like angles:replacement for roll-pitch-yaw angles for a six-degree-of-freedom grating interferometer

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Frontiers of Information Technology & Electronic Engineering 2021年第12期22卷 1677-1684页

作者： Di CHANG Pengcheng HU Jiubin TAN Center of Ultra-precision Optoelectronic Instrument Engineering Harbin Institute of TechnologyHarbin 150080China Key Lab of Ultra-precision Intelligent Instrumentation(Harbin Institute of Technology) Ministry of Industry and Information TechnologyHarbin 150080China

Representation of orientation is important in a six-degree-of-freedom grating interferometer but only a few studies have focused on this topic.Roll-pitch-yaw angles,widely used in aviation,navigation,and robotics,are now being brought to the field of multi-degree-of-freedom interferometric measurement.However,the roll-pitch-yaw angles are not the exact definitions the metrologists expected in interferometry,because they require a certain sequential order of rotations and may cause errors in describing complicated rotations.The errors increase as the tip and tilt angles of the grating increase.Therefore,a replacement based on fused angles in robotics is proposed and named“fused-like angles.”The fused-like angles are error-free,so they are more in line with the definitions in grating interferometry and more suitable for six-degree-of-freedom measurements.Fused-like angles have already been used in research on the kinematic model and decoupling algorithm of the six-degree-of-freedom grating interferometer.

关键词： Fused-like angles grating interferometer Six-degree-of-freedom measurement Representation of orientation

Analysis of period and visibility of dual phase grating interferometer

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Chinese Physics B 2022年第5期31卷 749-755页

作者：杨君黄建衡雷耀虎郑景标单雨征郭大育郭金川 Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province College of Physics and Optoelectronic EngineeringShenzhen UniversityShenzhen 518060China

Dual phase grating interferometer may simultaneously achieve large field of view and high x-ray dose efficiency.Here,we develop a simple theoretical method to better understand the imaging process of the dual phase grating interferometer.The derivation process of fringe period and the optimal visibility conditions of the dual phase grating interferometer are given in detail.Then,we theoretically prove that the fringe period and optimal visibility conditions of the dual phase grating interferometer include that of the Talbot interferometer.By comparing our experimental results with those of other researchers,we find that when the positions of phase gratings are far away from the positions where the fringe visibility is optimal,the fringe period of the dualπ-phase grating interferometer is twice the theoretical results under the illumination of polychromatic x-ray.This conclusion may explain the contradictory research results of dual phase grating interferometer among different researchers.

关键词： phase contrast grating interferometer fringe period fringe visibility

Quantitative coherence analysis of dual phase grating x-ray interferometry with source grating

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Chinese Physics B 2021年第2期30卷 595-600页

作者：王志立周瑞成赵立明任坤徐文刘波陈恒 School of Electronic Science&Applied Physics Hefei University of TechnologyHefei 230009China

Dual phase grating x-ray interferometry is compatible with common imaging detectors,and abandons the use of an absorption analyzer grating to reduce the radiation dose.When using x-ray tubes,an absorbing source grating must be introduced into the dual phase grating interferometer.In order to attain a high fringe visibility,in this work we conduct a quantitative coherence analysis of dual phase grating interferometry to find how the source grating affects the fringe visibility.Theoretical analysis shows that with the generalized Lau condition satisfied,the fringe visibility is influenced by the duty cycle of the source grating and the transmission through the grating bar.And the influence of the source grating profile on the fringe visibility is independent of the phase grating type.Numerical results illustrate that the maximum achievable fringe visibility decreases significantly with increasing transmission in the grating bar.Under a given transmission,one can always find an optimal duty cycle to maximize the fringe visibility.These results can be used as general guidelines for designing and optimizing dual phase grating x-ray interferometers for potential applications.

关键词： x-ray imaging phase contrast grating interferometer fringe visibility

Comparative analysis of phase extraction methods based on phase-stepping and shifting curve in grating interferometry

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Chinese Physics B 2010年第4期19卷 173-179页

作者：刘小松李恩荣朱佩平刘宜晋张凯王志立洪友丽张慧滔袁清习黄万霞吴自玉 Institute of High Energy Physics Chinese Academy of Sciences Department of Physics University of Science and Technology of China School of Mathematical Sciences Capital Normal University National Synchrotron Radiation Laboratory University of Science and Technology of China

Two phase extraction methods which are based separately on phase-stepping and shifting curve are mainly used in phase-sensitive imaging in gating interferometry to determine the x-ray phase shift induced by an object in the beam. In this paper, the authors perform a full comparative analysis and present the main virtues and limitations of these two methods according to the theoretical analysis of the grating interferometry.

关键词： x-ray phase sensitive imaging grating interferometer phase-stepping shifting curve