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Light field

About: Light field is a research topic. Over the lifetime, 5357 publications have been published within this topic receiving 87424 citations.


Papers
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Journal ArticleDOI
TL;DR: In this article, the authors theoretically investigate the damping and trapping forces in a three-dimensional magneto-optical trap (MOT), by numerically solving the optical Bloch equations.
Abstract: We theoretically investigate the damping and trapping forces in a three-dimensional magneto-optical trap (MOT), by numerically solving the optical Bloch equations. We focus on the case where there are dark states because the atom is driven on a ???type-II" system where the angular momentum of the excited state, F', is less than or equal to that of the ground state, F. For these systems we find that the force in a three-dimensional light field has very different behaviour to its one-dimensional counterpart. This differs from the more commonly used ???type-I" systems (F' = F +1) where the 1D and 3D behaviours are similar. Unlike type-I systems where, for red-detuned light, both Doppler and sub-Doppler forces damp the atomic motion towards zero velocity, in type-II systems in 3D, the Doppler force and polarization gradient force have opposite signs. As a result, the atom is driven towards a non-zero equilibrium velocity, v???, where the two forces cancel. We find that v????? scales linearly with the intensity of the light and is fairly insensitive to the detuning from resonance. We also discover a new magneto-optical force that alters the normal MOT force at low magnetic fields and whose influence is greatest in the type-II systems. We discuss the implications of these findings for the laser cooling and magneto-optical trapping of molecules where type-II transitions are unavoidable in realising closed optical cycling transitions.

41 citations

Proceedings ArticleDOI
01 Nov 2016
TL;DR: A novel hybrid scan order to rearrange subaperture images into an image sequence is proposed and verified its importance to coding performance of light field image format.
Abstract: A Light field image contains shear amount of data as it keeps the full spatio-angular information of the real scene. In this paper we propose a light field image coding scheme based on the latest JEM coding technologies. We propose a novel hybrid scan order to rearrange subaperture images into an image sequence and verify its importance to coding performance of light field image format. The experiment on EPFL light field image dataset demonstrates that our scheme achieves 7.06 dB gain compared with directly encoding the image by the JPEG standard. With the QP set to 50, our scheme achieves an average compression ratio of 7107, and still provides larger PSNRs and better viewing experience than JPEG at a compression ratio of 100.

41 citations

Journal ArticleDOI
Kazu Mishiba1
TL;DR: A fast depth estimation method based on multi-view stereo matching for light field images based on an approximate solver based on a fast-weighted median filter that achieves competitive accuracy with the shortest computational time of all methods.
Abstract: Fast depth estimation for light field images is an important task for multiple applications such as image-based rendering and refocusing. Most previous approaches to light field depth estimation involve high computational costs. Therefore, in this study, we propose a fast depth estimation method based on multi-view stereo matching for light field images. Similar to other conventional methods, our method consists of initial depth estimation and refinement. For the initial estimation, we use a one-bit feature for each pixel and calculate matching costs by summing all combinations of viewpoints with a fast algorithm. To reduce computational time, we introduce an offline viewpoint selection strategy and cost volume interpolation. Our refinement process solves the minimization problem in which the objective function consists of $\ell _{1}$ data and smoothness terms. Although this problem can be solved via a graph cuts algorithm, it is computationally expensive; therefore, we propose an approximate solver based on a fast-weighted median filter. Experiments on synthetic and real-world data show that our method achieves competitive accuracy with the shortest computational time of all methods.

41 citations

Patent
02 Sep 2010
TL;DR: In this paper, the illumination source has a LED light source (2) generating a first divergent light field (6), which is processed by a first optical element (10), in particular a first lens element, to generate a second divergent view (19) whose divergence can be varied.
Abstract: The illumination source has a LED light source (2) generating a first divergent light field (6). The light from the LED light source (2) is processed by a first optical element (10), in particular a first lens element, to generate a second divergent light field (19). The first divergent light field (19) is processed by a second optical element (20) having a variable lens variable focus in order to generate a third light field (35) whose divergence can be varied.

41 citations

Journal ArticleDOI
TL;DR: In this paper, the polarization states of high-order harmonics emitted from solids are not only determined by crystal symmetries, but can be dynamically controlled, as a consequence of the intertwined interband and intraband electronic dynamics, responsible for the harmonic generation.
Abstract: Attosecond metrology sensitive to sub-optical-cycle electronic and structural dynamics is opening up new avenues for ultrafast spectroscopy of condensed matter. Using intense lightwaves to precisely control the extremely fast carrier dynamics in crystals holds great promise for next-generation electronics and devices operating at petahertz bandwidth. The carrier dynamics can produce high-order harmonics of the driving light field extending up into the extreme-ultraviolet region. Here, we introduce polarization-state-resolved high-harmonic spectroscopy of solids, which provides deeper insights into both electronic and structural dynamics occuring within a single cycle of light. Performing high-harmonic generation measurements from silicon and quartz samples, we demonstrate that the polarization states of high-order harmonics emitted from solids are not only determined by crystal symmetries, but can be dynamically controlled, as a consequence of the intertwined interband and intraband electronic dynamics, responsible for the harmonic generation. We exploit this symmetry-dynamics duality to efficiently generate circularly polarized harmonics from elliptically polarized driver pulses. Our experimental results are supported by ab-initio simulations, providing clear evidence for the microscopic origin of the phenomenon. This spectroscopy technique might find important applications in future studies of novel quantum materials such as strongly correlated materials. Compact sources of bright circularly polarized harmonics in the extreme-ultraviolet regime will advance our tools for the spectroscopy of chiral systems, magnetic materials, and 2D materials with valley selectivity.

41 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023135
2022375
2021274
2020493
2019555
2018503