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https://www.readbyqxmd.com/read/29328266/nonlinear-refractive-index-measurements-using-time-resolved-digital-holography
#1
Balys Momgaudis, Stephane Guizard, Allan Bilde, Andrius Melninkaitis
In this Letter, a novel method to evaluate nonlinear refractive index using time-resolved digital holographic microscopy is introduced. To demonstrate the viability of the method, cross-correlative nonlinear refractive index values for sapphire are measured experimentally: 2.75·10-20  m2/W at 1030 nm and 4.10·10-20    m2/W 515 nm wavelengths. The obtained results for sapphire are compared to those available in literature obtained by other methods.
January 15, 2018: Optics Letters
https://www.readbyqxmd.com/read/29328151/characterization-of-the-reference-wave-in-a-compact-digital-holographic-camera
#2
I S Park, R J C Middleton, C R Coggrave, P D Ruiz, J M Coupland
A hologram is a recording of the interference between an unknown object wave and a coherent reference wave. Providing the object and reference waves are sufficiently separated in some region of space and the reference beam is known, a high-fidelity reconstruction of the object wave is possible. In traditional optical holography, high-quality reconstruction is achieved by careful reillumination of the holographic plate with the exact same reference wave that was used at the recording stage. To reconstruct high-quality digital holograms the exact parameters of the reference wave must be known mathematically...
January 1, 2018: Applied Optics
https://www.readbyqxmd.com/read/29328150/phase-retrieval-based-on-transport-of-intensity-and-digital-holography
#3
Wen-Jing Zhou, Xiaofei Guan, Fanfan Liu, YingJie Yu, Hongbo Zhang, Ting-Chung Poon, Partha P Banerjee
We propose a technique in which intensity images are reconstructed from a digital hologram to provide inputs for the transport-of-intensity equation for unwrapped phase recovery. By doing this, we avoid shifting of the sample or the camera in the experiment, a method commonly employed while using the method of transport-of-intensity equation for phase retrieval. Computer simulations as well as experimental results have been demonstrated to verify the effectiveness of the proposed idea. The underlying numerical technique can also be viewed as an alternative to existing phase-unwrapping algorithms...
January 1, 2018: Applied Optics
https://www.readbyqxmd.com/read/29328142/full-field-of-view-digital-lens-free-holography-for-weak-scattering-objects-based-on-grating-modulation
#4
Wenhui Zhang, Liangcai Cao, Guofan Jin, David Brady
Grating-based single-shot digital lens-free holography with spatial spectral multiplexing is proposed to realize full field-of-view (FOV) imaging for weak-scattering objects. Multiple object waves are generated by a one-dimensional grating that is placed in near contact with the object to avoid the cross talk among different diffraction orders during reconstruction. A multiplexed off-axis hologram is created by interference between the object waves and reference wave and captured by an image sensor in one shot...
January 1, 2018: Applied Optics
https://www.readbyqxmd.com/read/29328140/full-color-digitized-holography-for-large-scale-holographic-3d-imaging-of-physical-and-nonphysical-objects
#5
Kyoji Matsushima, Noriaki Sonobe
Digitized holography techniques are used to reconstruct three-dimensional (3D) images of physical objects using large-scale computer-generated holograms (CGHs). The object field is captured at three wavelengths over a wide area at high densities. Synthetic aperture techniques using single sensors are used for image capture in phase-shifting digital holography. The captured object field is incorporated into a virtual 3D scene that includes nonphysical objects, e.g., polygon-meshed CG models. The synthetic object field is optically reconstructed as a large-scale full-color CGH using red-green-blue color filters...
January 1, 2018: Applied Optics
https://www.readbyqxmd.com/read/29328139/holographic-display-methods-for-volume-data-polygon-based-and-mip-based-methods
#6
Zixiang Lu, Yuji Sakamoto
Volume data are widely used in many areas, especially in biomedical science and geology. However, current visualization technologies of volume data cannot satisfy the visual requirements of humans. In this study, we propose two holographic display methods for volume data. The first method is polygon-based, and the other is maximum intensity projection (MIP)-based. Both methods are able to generate computer generated holograms of volume data. The polygon-based method can obtain various and colorful holograms, while the MIP-based method can be quickly calculated...
January 1, 2018: Applied Optics
https://www.readbyqxmd.com/read/29328129/complex-object-wave-extraction-using-time-multiplexing-in-off-axis-digital-holography
#7
Erkhembaatar Dashdavaa, Munkh-Uchral Erdenebat, Chang-Won Shin, Nam Kim
In this paper, we present an algorithm for complex object wave extraction in off-axis digital holography using a time-multiplexing and frequency spectrum-shifting technique. The proposed approach utilizes the digital time-multiplexing technique, in which two 90-deg-rotated off-axis holograms are recorded in sequence, and corresponding spectra are subtracted in the computed Fourier domain to eliminate the DC term. Then, the two subtracted holograms are digitally multiplexed into one complex hologram in the same plane, and by shifting the spatial frequency spectra of the subtracted hologram in the spatial frequency domain, one of the two cross-correlations can be obtained in the center...
January 1, 2018: Applied Optics
https://www.readbyqxmd.com/read/29328115/digital-holography-and-3d-imaging-introduction-to-the-joint-feature-issue-in-applied-optics-and-journal-of-the-optical-society-of-america-a
#8
Hoonjong Kang, Byoungho Lee, Tomasz Kozacki, Pascal Picart, Guohai Situ
The OSA Topical Meeting on Digital Holography and 3D Imaging (DH) was held 29 May to 1 June 2017 in Jeju Island, South Korea. Feature issues based on the DH meeting series have been released by Applied Optics (AO) since 2007. This year, AO and the Journal of the Optical Society of America A (JOSA A) jointly decided to have one such feature issue in each journal. This feature issue includes 33 papers in AO and 9 in JOSA A and covers a large range of topics, reflecting the rapidly expanding techniques and applications of digital holography and 3D imaging...
January 1, 2018: Applied Optics
https://www.readbyqxmd.com/read/29328098/demonstration-of-single-shot-digital-holography-using-a-bayesian-framework
#9
Casey J Pellizzari, Matthias T Banet, Mark F Spencer, Charles A Bouman
In this paper, we present experimental results for image reconstruction, with isoplanatic phase-error correction, from single-shot digital holography data. We demonstrate the utility of using a model-based iterative reconstruction (MBIR) algorithm to jointly compute the maximum a posteriori estimates of the phase errors and the real-valued object reflectance function. Specifically, we show that the MBIR algorithm is robust to noise and phase errors over a range of conditions.
January 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
https://www.readbyqxmd.com/read/29328085/reference-free-metric-for-quantitative-noise-appraisal-in-holographic-phase-measurements
#10
Silvio Montrésor, Pascal Picart, Mayssa Karray
This paper presents a reference-free metric for quantitative appraisal of de-noising algorithms for phase measurements in digital holography. In the literature, quality metrics are not self-contained because they require a noise-free reference phase fringe pattern in order to be computed. In practical situations, no exact phase is available to evaluate the quality of processing. In order to bypass such limitations, one needs a metric directly capable of providing information on how efficient the filtering is, without any help from any reference measurements and by only considering the measured available phase data...
January 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
https://www.readbyqxmd.com/read/29328075/digital-holography-and-3d-imaging-introduction-to-the-joint-feature-issue-in-applied-optics-and-journal-of-the-optical-society-of-america-a
#11
Hoonjong Kang, Byoungho Lee, Tomasz Kozacki, Pascal Picart, Guohai Situ
The OSA Topical Meeting on Digital Holography and 3D Imaging (DH) was held 29 May to 1 June 2017 on Jeju Island, South Korea. Feature issues based on the DH meeting series have been released by Applied Optics (AO) since 2007. This year, AO and the Journal of the Optical Society of America A (JOSA A) jointly decided to have one such feature issue in each journal. This feature issue includes 33 papers in AO and 9 in JOSA A and covers a large range of topics, reflecting the rapidly expanding techniques and applications of digital holography and 3D imaging...
January 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
https://www.readbyqxmd.com/read/29306810/development-of-a-high-brightness-ultrafast-transmission-electron-microscope-based-on-a-laser-driven-cold-field-emission-source
#12
F Houdellier, G M Caruso, S Weber, M Kociak, A Arbouet
We report on the development of an ultrafast Transmission Electron Microscope based on a cold field emission source which can operate in either DC or ultrafast mode. Electron emission from a tungsten nanotip is triggered by femtosecond laser pulses which are tightly focused by optical components integrated inside a cold field emission source close to the cathode. The properties of the electron probe (brightness, angular current density, stability) are quantitatively determined. The measured brightness is the largest reported so far for UTEMs...
December 27, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/29249832/high-speed-single-shot-optical-focusing-through-dynamic-scattering-media-with-full-phase-wavefront-shaping
#13
Ashton S Hemphill, Yuecheng Shen, Yan Liu, Lihong V Wang
In biological applications, optical focusing is limited by the diffusion of light, which prevents focusing at depths greater than ∼1 mm in soft tissue. Wavefront shaping extends the depth by compensating for phase distortions induced by scattering and thus allows for focusing light through biological tissue beyond the optical diffusion limit by using constructive interference. However, due to physiological motion, light scattering in tissue is deterministic only within a brief speckle correlation time. In in vivo tissue, this speckle correlation time is on the order of milliseconds, and so the wavefront must be optimized within this brief period...
November 27, 2017: Applied Physics Letters
https://www.readbyqxmd.com/read/29240142/dual-wavelength-digital-holography-with-a-low-coherence-light-source-based-on-a-quantum-dot-film
#14
Jae-Yong Lee, Sungbin Jeon, Jin-Sang Lim, Se-Hwan Jang, No-Cheol Park, Young-Joo Kim
This Letter proposes a dual-wavelength, low-coherence digital holography system with a single light source, which utilizes a quantum dot (QD) film as a wavelength converter. By changing the size of the QDs, the proposed method easily yields higher and more uniform illumination of any target wavelength, compared with bandpass-filtered light-emitting diodes. Fabrication parameters of the QD film for better conversion efficiency are discussed. Using this light source with the dual-wavelength reconstruction method extends the efficiency and range of nanoscale three-dimensional height measurements...
December 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/29240102/on-the-unreasonable-effectiveness-of-transport-of-intensity-imaging-and-optical-deconvolution
#15
Timur E Gureyev, Yakov I Nesterets, Alexander Kozlov, David M Paganin, Harry M Quiney
The effectiveness of reconstructive imaging using the homogeneous transport of intensity equation may be regarded as "unreasonable," because it has been shown to significantly increase signal-to-noise ratio while preserving spatial resolution, compared to equivalent conventional absorption-based imaging techniques at the same photon fluence. We reconcile this surprising behavior by analyzing the propagation of noise in typical in-line holography experiments. This analysis indicates that novel imaging techniques may be designed that produce high signal-to-noise images at low radiation doses without sacrificing spatial resolution...
December 1, 2017: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
https://www.readbyqxmd.com/read/29223803/fine-electron-biprism-on-a-si-on-insulator-chip-for-off-axis-electron-holography
#16
Martial Duchamp, Olivier Girard, Giulio Pozzi, Helmut Soltner, Florian Winkler, Rolf Speen, Rafal E Dunin-Borkowski, David Cooper
Off-axis electron holography allows both the amplitude and the phase shift of an electron wavefield propagating through a specimen in a transmission electron microscope to be recovered. The technique requires the use of an electron biprism to deflect an object wave and a reference wave to form an interference pattern. Here, we introduce an approach based on semiconductor processing technology to fabricate fine electron biprisms with rectangular cross-sections. By performing electrostatic calculations and preliminary experiments, we demonstrate that such biprisms promise improved performance for electron holography experiments...
November 22, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/29219557/intertwined-order-and-holography-the-case-of-parity-breaking-pair-density-waves
#17
Rong-Gen Cai, Li Li, Yong-Qiang Wang, Jan Zaanen
We present a minimal bottom-up extension of the Chern-Simons bulk action for holographic translational symmetry breaking that naturally gives rise to pair density waves. We construct stationary inhomogeneous black hole solutions in which both the U(1) symmetry and spatially translational symmetry are spontaneously broken at a finite temperature and charge density. This novel solution provides a dual description of a superconducting phase intertwined with charge, current, and parity orders.
November 3, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/29219505/direct-imaging-of-a-zero-field-target-skyrmion-and-its-polarity-switch-in-a-chiral-magnetic-nanodisk
#18
Fengshan Zheng, Hang Li, Shasha Wang, Dongsheng Song, Chiming Jin, Wenshen Wei, András Kovács, Jiadong Zang, Mingliang Tian, Yuheng Zhang, Haifeng Du, Rafal E Dunin-Borkowski
A target Skyrmion is a flux-closed spin texture that has twofold degeneracy and is promising as a binary state in next generation universal memories. Although its formation in nanopatterned chiral magnets has been predicted, its observation has remained challenging. Here, we use off-axis electron holography to record images of target Skyrmions in a 160-nm-diameter nanodisk of the chiral magnet FeGe. We compare experimental measurements with numerical simulations, demonstrate switching between two stable degenerate target Skyrmion ground states that have opposite polarities and rotation senses, and discuss the observed switching mechanism...
November 10, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/29216154/calibrated-phase-shifting-digital-holography-based-on-a-dual-camera-system
#19
Peng Xia, Qinghua Wang, Shien Ri, Hiroshi Tsuda
A calibrated phase-shifting digital holography system based on the sampling Moiré technique is proposed. Two synchronized cameras are used in this system. One is to record the conventional holograms that include the object information, and the other is to record the interference fringes to analyze phase-shifting errors. An algorithm for improving the quality of the reconstructed images is proposed. In this Letter, the effectiveness of the proposed system and algorithm is demonstrated in four-step phase-shifting digital holography...
December 1, 2017: Optics Letters
https://www.readbyqxmd.com/read/29209064/magnetic-field-observations-in-cofeb-ta-layers-with-0-67-nm-resolution-by-electron-holography
#20
Toshiaki Tanigaki, Tetsuya Akashi, Akira Sugawara, Katsuya Miura, Jun Hayakawa, Kodai Niitsu, Takeshi Sato, Xiuzhen Yu, Yasuhide Tomioka, Ken Harada, Daisuke Shindo, Yoshinori Tokura, Hiroyuki Shinada
Nanometre-scale magnetic field distributions in materials such as those at oxide interfaces, in thin layers of spintronics devices, and at boundaries in magnets have become important research targets in materials science and applied physics. Electron holography has advantages in nanometric magnetic field observations, and the realization of aberration correctors has improved its spatial resolution. Here we show the subnanometre magnetic field observations inside a sample at 0.67-nm resolution achieved by an aberration-corrected 1...
December 5, 2017: Scientific Reports
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