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https://www.readbyqxmd.com/read/28295088/reduction-of-speckle-noise-in-holographic-images-using-spatial-jittering-in-numerical-reconstructions
#1
Mohamed Haouat, Jorge Garcia-Sucerquia, Abdelhamid Kellou, Pascal Picart
This Letter presents an easy, fast, and efficient single-shot method to reduce speckle noise in digital Fresnel holography. In this method, several images from a single hologram are reconstructed by introducing spatial displacements in the Fresnel kernel. Spatial jitters produce images with different speckle positions. Averaging the set of numerically produced images leads to a strong reduction of speckle noise in both amplitude and phase difference images. The experimental results show the suitability of the proposed approach and confirm its applicability to digital holographic interferometry...
March 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28269466/heart-activity-monitoring-using-3d-hologram-based-on-smartphone
#2
Tharoeun Thap, Heewon Chung, Jinseok Lee
In this paper, we used smartphone to obtained pulsatile signal from a fingertip by illuminating the skin tissue using flashlight and with an on-board camera to record the change of the light intensity reflected from the tissue. The pulsatile signal is produced by analyzing average green component values of the frames taken by the camera and the heart rate is estimated in real time by detecting the pulse peaks. Based on each instant obtained heartbeat, we design a heart animation that beats according to each interval of the heartbeat...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28261546/prospects-for-atomic-resolution-in-line-holography-for-a-3d-determination-of-atomic-structures-from-single-projections
#3
REVIEW
F-R Chen, C Kisielowski, D Van Dyck
It is now established that the 3D structure of homogeneous nanocrystals can be recovered from in-line hologram of single projections. The method builds on a quantitative contrast interpretation of electron exit wave functions. Since simulated exit wave functions of single and bilayers of graphene reveal the atomic structure of carbon-based materials with sufficient resolution, we explore theoretically how the approach can be expanded beyond periodic carbon-based materials to include non-periodic molecular structures...
2017: Advanced Structural and Chemical Imaging
https://www.readbyqxmd.com/read/28252935/high-numerical-aperture-hexagonal-stacked-ring-based-bidirectional-flexible-polymer-microlens-array
#4
Rajib Ahmed, Ali K Yetisen, Haider Butt
Flexible imprinted photonic nanostructures that are able to diffract/focus narrow-band light have potential applications in optical lenses, filters, tunable lasers, displays, and biosensing. Nanophotonic structures through holography and roll-to-roll printing may reduce fabrication complexities and expenses and enable mass production. Here, 3D photonic nanostructures of a stacked ring array were imprinted on acrylate polymer (AP) over poly(ethylene terephthalate) (PET) substrate through holography and lift-off processes to create a microlens array (MLA)...
March 28, 2017: ACS Nano
https://www.readbyqxmd.com/read/28248354/measuring-extinction-with-digital-holography-nonspherical-particles-and-experimental-validation
#5
Matthew J Berg, Nava R Subedi, Peter A Anderson
Through simulations and experiment, this Letter shows how a particle's extinction cross section can be extracted from a digital hologram. Spherical and nonspherical particles are considered covering a range of cross-sectional values of nearly five orders of magnitude. The extracted cross sections are typically less than 10% in error from the true values. It is also shown that holograms encompassing a sufficiently large angular range of scattered light yield an estimate for the absorption cross section.
March 1, 2017: Optics Letters
https://www.readbyqxmd.com/read/28248352/time-multiplexed-structured-illumination-using-a-dmd-for-optical-diffraction-tomography
#6
KyeoReh Lee, Kyoohyun Kim, Geon Kim, Seungwoo Shin, YongKeun Park
We present a time-multiplexing structured illumination control technique for optical diffraction tomography (ODT). Instead of tilting the angle of illumination, time-multiplexed sinusoidal illumination is exploited using a digital micromirror device (DMD). The present method effectively eliminates unwanted diffracted beams from binary DMD patterns, which deteriorates the image quality of the ODT in the previous binary Lee hologram method. We experimentally show the feasibility and advantage of the present method by reconstructing three-dimensional refractive index distributions of various samples and comparing with a conventional Lee hologram method...
March 1, 2017: Optics Letters
https://www.readbyqxmd.com/read/28248338/spectrum-and-space-resolved-4d-imaging-by-coded-aperture-correlation-holography-coach-with-diffractive-objective-lens
#7
A Vijayakumar, Joseph Rosen
In this Letter, we present an advanced optical configuration of coded aperture correlation holography (COACH) with a diffractive objective lens. Four-dimensional imaging of objects at the three spatial dimensions and with an additional spectral dimension is demonstrated. A hologram of three-dimensional objects illuminated by different wavelengths was recorded by the interference of light diffracted from the objects with the light diffracted from the same objects, but through a random-like coded phase mask (CPM)...
March 1, 2017: Optics Letters
https://www.readbyqxmd.com/read/28241646/compact-lensless-phase-imager
#8
Manon Rostykus, Ferréol Soulez, Michael Unser, Christophe Moser
Lensless quantitative phase imaging is of high interest for obtaining a large field of view (FOV), typically the size of the camera chip, to observe biological cell material with high contrast. It has the potential to be widely spread due to its inherent simplicity. However, the tradeoff is the added complexity due to the illumination. Current illumination systems are several centimeters away from the sample, use mechanics to obtain super resolution (i.e., smaller than the detector pixel size) or different illumination directions, and block the view to the sample...
February 20, 2017: Optics Express
https://www.readbyqxmd.com/read/28241561/characteristics-of-complex-light-modulation-through-an-amplitude-phase-double-layer-spatial-light-modulator
#9
Sungjae Park, Jinyoung Roh, Soobin Kim, Juseong Park, Hoon Kang, Joonku Hahn, Youngjin Jeon, Shinwoong Park, Hwi Kim
The complex modulation characteristics of a light field through an amplitude-phase double-layer spatial light modulator are analyzed based on the wave-optic numerical model, and the structural conditions for the optimal double-layer complex modulation structure are investigated. The relationships of interlayer distance, pixel size, and complex light modulation performance are analyzed. The main finding of this study is that the optimal interlayer distance for the double-layer structure can be found at the Talbot effect condition...
February 20, 2017: Optics Express
https://www.readbyqxmd.com/read/28237614/3d-shaping-of-electron-beams-using-amplitude-masks
#10
Roy Shiloh, Ady Arie
Shaping the electron wavefunction in three dimensions may prove to be an indispensable tool for research involving atomic-sized particle trapping, manipulation, and synthesis. We utilize computer-generated holograms to sculpt electron wavefunctions in a standard transmission electron microscope in 3D, and demonstrate the formation of electron beams exhibiting high intensity along specific trajectories as well as shaping the beam into a 3D lattice of hot-spots. The concepts presented here are similar to those used in light optics for trapping and tweezing of particles, but at atomic scale resolutions...
February 20, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/28236742/spatial-coherence-of-electron-beams-from-field-emitters-and-its-effect-on-the-resolution-of-imaged-objects
#11
Tatiana Latychevskaia
Sub-nanometer and nanometer-sized tips provide high coherence electron sources. Conventionally, the effective source size is estimated from the extent of the experimental biprism interference pattern created on the detector by applying the van Cittert Zernike theorem. Previously reported experimental intensity distributions on the detector exhibit Gaussian distribution and our simulations show that this is an indication that such electron sources must be at least partially coherent. This, in turn means that strictly speaking the Van Cittert Zernike theorem cannot be applied, since it assumes an incoherent source...
November 25, 2016: Ultramicroscopy
https://www.readbyqxmd.com/read/28227716/heart-activity-monitoring-using-3d-hologram-based-on-smartphone
#12
Tharoeun Thap, Heewon Chung, Jinseok Lee, Tharoeun Thap, Heewon Chung, Jinseok Lee, Tharoeun Thap, Jinseok Lee, Heewon Chung
In this paper, we used smartphone to obtained pulsatile signal from a fingertip by illuminating the skin tissue using flashlight and with an on-board camera to record the change of the light intensity reflected from the tissue. The pulsatile signal is produced by analyzing average green component values of the frames taken by the camera and the heart rate is estimated in real time by detecting the pulse peaks. Based on each instant obtained heartbeat, we design a heart animation that beats according to each interval of the heartbeat...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28198854/two-photon-polymerization-of-microstructures-by-a-non-diffraction-multifoci-pattern-generated-from-a-superposed-bessel-beam
#13
Liang Yang, Dongdong Qian, Chen Xin, Zhijiang Hu, Shengyun Ji, Dong Wu, Yanlei Hu, Jiawen Li, Wenhao Huang, Jiaru Chu
In this Letter, superposed Bessel beams (SBBs) are realized by alternatively imprinting holograms of opposite-order Bessel beams along the radial direction on a spatial light modulator. The propagation invariance and non-rotation properties of SBBs are theoretically predicted and experimentally demonstrated. The focusing property of SBBs with a high numerical aperture (NA) objective is investigated with the Debye vectorial diffraction theory. Near the focal plane, a circularly distributed multiple foci pattern is achieved...
February 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28198842/refractive-index-and-gain-grating-in-nd-yvo-sub-4-sub-application-to-speckle-vibrometry-and-photoacoustic-detection
#14
Baptiste Jayet, Jean-Pierre Huignard, Francois Ramaz
Probing local displacements on a scattering surface can be achieved using an adaptive interferometer. The photorefractive-crystal-based interferometer is popular, but alternatives exist such as an adaptive gain interferometer. Such setups take advantage of the nonlinear phenomena in laser media. Because of the gain saturation, it is possible to write a gain hologram and a refractive index hologram to achieve an adaptive interferometer with a linear response. In addition, laser-media-based setups have a fast response time (≤100  μs), which makes them interesting for applications such as detection of photoacoustic waves in living biological samples...
February 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28181514/new-2d-diffraction-model-and-its-applications-to-terahertz-parallel-plate-waveguide-power-splitters
#15
Fan Zhang, Kaijun Song, Yong Fan
A two-dimensional (2D) diffraction model for the calculation of the diffraction field in 2D space and its applications to terahertz parallel-plate waveguide power splitters are proposed in this paper. Compared with the Huygens-Fresnel principle in three-dimensional (3D) space, the proposed model provides an approximate analytical expression to calculate the diffraction field in 2D space. The diffraction filed is regarded as the superposition integral in 2D space. The calculated results obtained from the proposed diffraction model agree well with the ones by software HFSS based on the element method (FEM)...
February 9, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28158100/image-multiplexing-and-encryption-using-the-nonnegative-matrix-factorization-method-adopting-digital-holography
#16
Hsuan T Chang, J-W Shui, K-P Lin
In this paper, a joint multiple-image encryption and multiplexing system, which utilizes both the nonnegative matrix factorization (NMF) scheme and digital holography, is proposed. A number of images are transformed into noise-like digital holograms, which are then decomposed into a defined number of basis images and a corresponding weighting matrix using the NMF scheme. The determined basis images are similar to the digital holograms and appear as noise-like patterns, which are then stored as encrypted data and serve as the lock in an encryption system...
February 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28158083/holographic-microinformation-hiding
#17
Tomoyoshi Shimobaba, Yutaka Endo, Ryuji Hirayama, Daisuke Hiyama, Yuki Nagahama, Satoki Hasegawa, Marie Sano, Takayuki Takahashi, Takashi Kakue, Minoru Oikawa, Tomoyoshi Ito
We propose a holographic microinformation hiding scheme in which the embedding information to be embedded is small and imperceptible to the human eyes. This scheme converts the embedding information into a complex amplitude via scaled diffraction. The complex amplitude of the reduced embedding information is added to the complex amplitude of the host image, followed by conversion to a hologram. The reduced embedded information is inconspicuous from the hologram during the reconstruction process; however, the reduction leads to the degradation of the embedded image quality...
February 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/28158016/digital-super-resolution-holographic-data-storage-based-on-hermitian-symmetry-for-achieving-high-areal-density
#18
Teruyoshi Nobukawa, Takanori Nomura
Digital super-resolution holographic data storage based on Hermitian symmetry is proposed to store digital data in a tiny area of a medium. In general, reducing a recording area with an aperture leads to the improvement in the storage capacity of holographic data storage. Conventional holographic data storage systems however have a limitation in reducing a recording area. This limitation is called a Nyquist size. Unlike the conventional systems, our proposed system can overcome the limitation with the help of a digital holographic technique and digital signal processing...
January 23, 2017: Optics Express
https://www.readbyqxmd.com/read/28157974/photonic-jet-reconstruction-for-particle-refractive-index-measurement-by-digital-in-line-holography
#19
Matthias P L Sentis, Fabrice R A Onofri, Fabrice Lamadie
A new and computationally efficient approach is proposed for determining the refractive index of spherical and transparent particles, in addition to their size and 3D position, using digital in-line holography. The method is based on the localization of the maximum intensity position of the photonic jet with respect to the particle center retrieved from the back propagation of recorded holograms. Rigorous electromagnetic calculations and experimental results demonstrate that for liquid-liquid systems and droplets with a radius > 30µm, a refractive index measurement with a resolution inferior to 4 × 10<sup>-3</sup> is achievable, revealing a significant potential for the use of this method to investigate multiphase flows...
January 23, 2017: Optics Express
https://www.readbyqxmd.com/read/28146507/high-resolution-parallel-phase-shifting-digital-holography-using-a-low-resolution-phase-shifting-array-device-based-on-image-inpainting
#20
Shuming Jiao, Wenbin Zou
Parallel phase-shifting digital holography can record high-quality holograms efficiently from fast-moving objects in a dynamic scene. However, a phase-shifting array device with a cell size identical to image sensors is required, which imposes difficulty in practice. This Letter proposes a novel scheme to employ a low-resolution phase-shifting array device to achieve high-resolution parallel phase-shifting digital holography, based on image inpainting performed on incomplete holograms. The experimental results validate the effectiveness of the proposed scheme...
February 1, 2017: Optics Letters
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