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4 results on '"Lei Qiao"'

1. Passive ranging and a three-dimensional imaging system through wavefront coding

Author

Lei Qiao, Xing-Xu Zhang, Ting-Yu Zhao, and Rong-Sheng Qiu

Subjects
Physics, business.industry, General Physics and Astronomy, Ranging, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, 010309 optics, Optics, Three dimensional imaging, 0103 physical sciences, 0210 nano-technology, business, Wavefront coding
Published
2018

3. Fluctuating specific heat in two-band superconductors

Author

Lei Qiao, Cheng Chi, and Jiangfan Wang

Subjects
Physics, Superconductivity, Specific heat, Condensed matter physics, Coupling strength, General Physics and Astronomy, Thermal fluctuations, Perturbation (astronomy), 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Homogeneous magnetic field, Gaussian approximation, Two band, Condensed Matter::Superconductivity, 0103 physical sciences, 010306 general physics, 0210 nano-technology
Abstract

Theory of thermal fluctuations in two-band superconductors under an essentially homogeneous magnetic field is developed within the framework of the two-band Ginzburg–Landau theory. The fluctuating specific heat is calculated by using the optimized self-consistent perturbation approach and the results are applied to analyze the thermodynamic data of the iron-based superconductors Ba1−x K x Fe2As2 with x ~ 0.4, which have been suggested to have a two-band structure by recent experiments. We estimate the fluctuation strength in this material and find that the specific heat is described well with the Ginzburg number Gi = 410−4. The influence of interband coupling strength is investigated and the result of the two-band Gaussian approximation approach is compared.

Published
2017

4. Passive ranging and a three-dimensional imaging system through wavefront coding.

Author

Xing-Xu Zhang, Lei Qiao, Ting-Yu Zhao, and Rong-Sheng Qiu

Subjects
*THREE-dimensional imaging, *WAVEFRONTS (Optics), *IMAGE compression, *PHASE coding, *LIQUID crystals, *LIGHT modulators
Abstract

A single-image passive ranging and three-dimensional (3D) imaging system with chiral phase encoding was proposed in 2011 [Opt. Lett.36, 115 (2011)]. A new theoretical analysis of the system in space domain is presented in this paper. We deduce the analytic relationships between the object distance and the point spread function, and between the object distance and the encoded image, respectively. Both the point spread function and the processed spectrum of the encoded image have two spots, which will rotate with the variation of the object distance. Then the depth map is extracted from the encoded image and it can be used to set up 3D images. The theoretical analysis is verified by a wavefront coding system with a chiral phase which is generated by a phase-only liquid-crystal spatial light modulator. The phase generated by the liquid-crystal spatial light modulator is more flexible than the fixed phase mask and can be adjusted in real time. It is especially suitable for observing the object with a large depth of field. [ABSTRACT FROM AUTHOR]

Published
2018
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