Implementation of spatial shift estimation approach for 3D profilometry based on digital fringe projection

Fringe Pattern Profilometry (FPP) based on Digital Fringe Projection (DFP) is a promising optical noncontact three-dimension (3D) profile measurement technologies due to its accuracy and flexibility. Popular FPP approaches retrieve the 3D profile information using the detection of phase difference, called the Phase Difference Estimation (PDE). Recently, a new kind of FPP approach, referred to as Spatial Shift Estimation (SSE) is introduced, which retrieves the 3D profile information using the detection of spatial shift instead of phase different. Compared with PDE approaches, SSE approaches are advantageous in that the projected fringe patterns do not need to be sinusoidal, and thus accurate reconstruction can be obtained even when nonlinear distortions exist on the fringe patterns. However, efficient implementation of SSE approaches is still an issue. This thesis work aims to implement the SSE approach for 3D profile measurement based on digital fringe projection. Firstly, a DFP system is designed and adopted in our laboratory, which is utilized as an experiment platform for the work presented in this thesis. SSE approaches are implemented on the system. Some problems associated with the implementation are studied and solved, including elimination of noise and distortion in the fringe patterns. Furthermore, an improved Inverse Function based Shift Estimation (IFSE) method is proposed to improve the performance of SSE approaches. Secondly, shift unwrapping problem associated with SSE is investigated. Through reviewing the phase unwrapping problem in PDE based FPP, we indicate that a similar shift unwrapping problem also exists in SSE approaches. A method for solving the problem has been proposed and the experiment results are presented to demonstrate the effectiveness of the proposed method. Finally, the research is carried out to improve the efficiency of SSE approaches. SSE approaches have the advantages that the projected fringe patterns are no longer required to be sinusoidal nor periodic. Therefore, we can choose a fringe pattern which has strong counter-interference capability against the noise and nonlinear distortion with simple implementation. Based on analysis of the limitations of traditional sinusoidal fringe, we propose to use sawtooth fringe pattern. Theoretical analysis has been given to evaluate the complexity of the proposed sawtooth fringe pattern based algorithms, and practical experiment are performed at last to prove the efficiency of this proposed fringe pattern

Gapless topological Fulde-Ferrell superfluidity induced by in-plane Zeeman field

Topological superfluids are recently discovered quantum matters that host topologically protected gapless edge states known as Majorana fermions - exotic quantum particles that act as their own anti-particles and obey non-Abelian statistics. Their realizations are believed to lie at the heart of future technologies such as fault-tolerant quantum computation. To date, the most efficient scheme to create topological superfluids and Majorana fermions is based on the Sau-Lutchyn-Tewari-Das Sarma model with a Rashba-type spin-orbit coupling on the }\textbf{\textit{x-y}}\textbf{ plane and a large out-of-plane (perpendicular) Zeeman field along the }\textbf{\textit{z}}\textbf{-direction. Here we propose an alternative setup, where the topological superfluid phase is driven by applying an in-plane Zeeman field. This scheme offers a number of new features, notably Cooper pairings at finite centre-of-mass momentum (i.e., Fulde-Ferrell pairing) and gapless excitations in the bulk. As a result, a novel gapless topological quantum matter with inhomogeneous pairing order parameter appears. It features unidirected Majorana surface states at boundaries, which propagate in the same direction and connect two Weyl nodes in the bulk. We demonstrate the emergence of such an exotic topological matter and the associated Majorana fermions in spin-orbit coupled atomic Fermi gases and determine its parameter space. The implementation of our scheme in semiconductor/superconductor heterostructures is briefly discussed.Comment: 8 pages, 5 figure

Physiological Electrical Signals Promote Chain Migration of Neuroblasts by Up-Regulating P2Y1 Purinergic Receptors and Enhancing Cell Adhesion

Acknowledgments This work was supported by a grant from NHS Grampian. Open Access This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are creditedPeer reviewedPublisher PD

Physiological extracellular electrical signals guide and orient the polarity of gut epithelial cells

Funding This work was supported by University of Aberdeen, Friends of ANCHOR and Action Medical Research GN2199.Peer reviewedPublisher PD

Spatial shift unwrapping for digital fringe profilometry based on spatial shift estimation

An approach is presented to solve the problem of spatial shift wrapping associated with spatial shift estimation-based fringe pattern profilometry (FPP). This problem arises as the result of fringe reuses (that is, use of fringes with periodic light intensity variance), and the spatial shift can only be identified without ambiguity within the range of a fringe width. It is demonstrated that the problem is similar to the phase unwrapping problem associated with the phase-detection-based FPP, and the proposed method is inspired by the existing ideas of using multiple images with different wavelengths proposed for phase unwrapping. The effectiveness of the proposed method is verified by comparing experimental results against several objects, with the last object consisting of more complex surface features. We conclude by showing that our method is successful in reconstructing the fine details of the more complex object

Polarizing intestinal epithelial cells electrically through Ror2

© 2014. Published by The Company of Biologists Ltd.Peer reviewedPublisher PD