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https://www.readbyqxmd.com/read/28726938/design-and-characterization-of-a-plasmonic-doppler-grating-for-azimuthal-angle-resolved-surface-plasmon-resonances
#1
Kel-Meng See, Fan-Cheng Lin, Jer-Shing Huang
We present a two-dimensional plasmonic Doppler grating (PDG) for broadband and azimuthal angle-resolved nanophotonic applications. The PDG consists of a set of non-concentric circular rings mimicking the wavefronts of a moving point source that exhibits the Doppler effect and thereby offers a continuous azimuthal angle-dependent lattice momentum for photon-plasmon coupling. The center and span of the working frequency window are fully designable for optimal performance in specific applications. We detail the design, fabrication and optical characterization of the PDG...
July 20, 2017: Nanoscale
https://www.readbyqxmd.com/read/28717573/in-vivo-digital-wavefront-sensing-using-swept-source-oct
#2
Abhishek Kumar, Lara M Wurster, Matthias Salas, Laurin Ginner, Wolfgang Drexler, Rainer A Leitgeb
Sub-aperture based digital adaptive optics is demonstrated in a fiber based point scanning optical coherence tomography system using a 1060 nm swept source laser. To detect optical aberrations in-vivo, a small lateral field of view of ~[Formula: see text] is scanned on the sample at a high volume rate of 17 Hz (~1.3 kHz B-scan rate) to avoid any significant lateral and axial motion of the sample, and is used as a "guide star" for the sub-aperture based DAO. The proof of principle is demonstrated using a micro-beads phantom sample, wherein a significant root mean square wavefront error (RMS WFE) of 1...
July 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/28713849/glare-suppression-by-coherence-gated-negation
#3
Edward Haojiang Zhou, Atsushi Shibukawa, Joshua Brake, Haowen Ruan, Changhuei Yang
Imaging of a weak target hidden behind a scattering medium can be significantly confounded by glare. We report a method, termed coherence gated negation (CGN), that uses destructive optical interference to suppress glare and allow improved imaging of a weak target. As a demonstration, we show that by permuting through a set range of amplitude and phase values for a reference beam interfering with the optical field from the glare and target reflection, we can suppress glare by an order of magnitude, even when the optical wavefront is highly disordered...
October 2016: Optica
https://www.readbyqxmd.com/read/28708166/low-photon-count-based-digital-holography-for-quadratic-phase-cryptography
#4
Inbarasan Muniraj, Changliang Guo, Ra'ed Malallah, James P Ryle, John J Healy, Byung-Geun Lee, John T Sheridan
Recently, the vulnerability of the linear canonical transform-based double random phase encryption system to attack has been demonstrated. To alleviate this, we present for the first time, to the best of our knowledge, a method for securing a two-dimensional scene using a quadratic phase encoding system operating in the photon-counted imaging (PCI) regime. Position-phase-shifting digital holography is applied to record the photon-limited encrypted complex samples. The reconstruction of the complex wavefront involves four sparse (undersampled) dataset intensity measurements (interferograms) at two different positions...
July 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28708155/adaptive-aberration-correction-of-a-5%C3%A2-%C3%A2-j-6-6%C3%A2-%C3%A2-ns-200%C3%A2-%C3%A2-hz-solid-state-nd-yag-laser
#5
Xin Yu, Lizhi Dong, Boheng Lai, Ping Yang, Shanqiu Chen, Wenjin Liu, Shuai Wang, Guomao Tang, Jisi Qiu, Zhijun Kang, Yueliang Liu, Hao Liu, Yong Liu, Zhongwei Fan, Bing Xu
In this Letter, we present an adaptive aberration correction system to simultaneously compensate for aberrations and reshaping the beams. A low-order aberration corrector is adapted. In this corrector, four lenses are mounted on a motorized rail, whose positions can be obtained using a ray tracing method based on the beam parameters detected by a wavefront sensor. After automatic correction, the PV value of the wavefront is reduced from 26.47 to 1.91 μm, and the beam quality β is improved from 18.42 to 2...
July 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28701800/design-transform-and-control-of-optical-field-in-discrete-optical-system-an-example
#6
Hongchang Deng, Yonggui Yuan, Libo Yuan
A discrete optical system can broaden the spatial distribution of the input light through optical coupling in array waveguides, just like diffraction in continuous media. Here, we theoretically demonstrate several kinds of control methods of optical field propagation in a discrete optical system, which is composed of an Airy fiber with two perpendicular arrayed cores. A brief transform mechanism between Gaussian and Airy beam propagation in such a fiber is presented. The wavefront of the output beam from the Airy fiber is actually dependent on the phased arrayed modulation of coupling array cores...
July 12, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28695661/relationships-between-gastric-slow-wave-frequency-velocity-and-extracellular-amplitude-studied-by-a-joint-experimental-theoretical-approach
#7
T H-H Wang, P Du, T R Angeli, N Paskaranandavadivel, J C Erickson, T L Abell, L K Cheng, G O'Grady
BACKGROUND: Gastric slow wave dysrhythmias are accompanied by deviations in frequency, velocity, and extracellular amplitude, but the inherent association between these parameters in normal activity still requires clarification. This study quantified these associations using a joint experimental-theoretical approach. METHODS: Gastric pacing was conducted in pigs with simultaneous high-resolution slow wave mapping (32-256 electrodes; 4-7.6 mm spacing). Relationships between period, velocity, and amplitude were quantified and correlated for each wavefront...
July 11, 2017: Neurogastroenterology and Motility: the Official Journal of the European Gastrointestinal Motility Society
https://www.readbyqxmd.com/read/28681436/human-eyes-do-not-need-monochromatic-aberrations-for-dynamic-accommodation
#8
Paula Bernal-Molina, Iván Marín-Franch, Antonio J Del Águila-Carrasco, Jose J Esteve-Taboada, Norberto López-Gil, Philip B Kruger, Robert Montés-Micó
PURPOSE: To determine if human accommodation uses the eye's own monochromatic aberrations to track dynamic accommodative stimuli. METHODS: Wavefront aberrations were measured while subjects monocularly viewed a monochromatic Maltese cross moving sinusoidally around 2D of accommodative demand with 1D amplitude at 0.2 Hz. The amplitude and phase (delay) of the accommodation response were compared to the actual vergence of the stimulus to obtain gain and temporal phase, calculated from wavefront aberrations recorded over time during experimental trials...
July 5, 2017: Ophthalmic & Physiological Optics: the Journal of the British College of Ophthalmic Opticians (Optometrists)
https://www.readbyqxmd.com/read/28673750/quality-of-vision-in-eyes-with-epiphora-undergoing-lacrimal-passage-intubation
#9
Shizuka Koh, Yasushi Inoue, Shintaro Ochi, Yoshihiro Takai, Naoyuki Maeda, Kohji Nishida
PURPOSE: To investigate visual function and optical quality in eyes with epiphora undergoing lacrimal passage intubation. DESIGN: Prospective case series. METHODS: Thirty-four eyes of 30 patients with lacrimal passage obstruction were enrolled. Before and 1 month after lacrimal passage intubation, functional visual acuity (FVA), higher-order aberrations (HOAs), lower tear meniscus and tear clearance were assessed. An FVA measurement system was used to examine changes in continuous visual acuity (VA) over time, and visual function parameters such as FVA, visual maintenance ratio, and blink frequency were obtained...
June 30, 2017: American Journal of Ophthalmology
https://www.readbyqxmd.com/read/28671940/expanding-signaling-molecule-wavefront-model-of-cell-polarization-in-the-drosophila-wing-primordium
#10
Juliana C Wortman, Marcos Nahmad, Peng Cheng Zhang, Arthur D Lander, Clare C Yu
In developing tissues, cell polarization and proliferation are regulated by morphogens and signaling pathways. Cells throughout the Drosophila wing primordium typically show subcellular localization of the unconventional myosin Dachs on the distal side of cells (nearest the center of the disc). Dachs localization depends on the spatial distribution of bonds between the protocadherins Fat (Ft) and Dachsous (Ds), which form heterodimers between adjacent cells; and the Golgi kinase Four-jointed (Fj), which affects the binding affinities of Ft and Ds...
July 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28670607/sub-nyquist-sampling-boosts-targeted-light-transport-through-opaque-scattering-media
#11
Yuecheng Shen, Yan Liu, Cheng Ma, Lihong V Wang
Optical time-reversal techniques are being actively developed to focus light through or inside opaque scattering media. When applied to biological tissue, these techniques promise to revolutionize biophotonics by enabling deep-tissue non-invasive optical imaging, optogenetics, optical tweezing, and phototherapy. In all previous optical time-reversal experiments, the scattered light field was well-sampled during wavefront measurement and wavefront reconstruction, following the Nyquist sampling criterion. Here, we overturn this conventional practice by demonstrating that even when the scattered field is under-sampled, light can still be focused through or inside scattering media...
January 20, 2017: Optica
https://www.readbyqxmd.com/read/28667966/three-dimensional-characterization-of-tightly-focused-fields-for-various-polarization-incident-beams
#12
Yanan Cai, Yansheng Liang, Ming Lei, Shaohui Yan, Zhaojun Wang, Xianghua Yu, Manman Li, Dan Dan, Jia Qian, Baoli Yao
Tightly focused vectorial optical beams have found extensive applications in variety of technical fields like single-molecule detection, optical tweezers, and super-resolution optical microscopy. Such applications require an accurate measurement and manipulation of focal optical fields. We have developed a compact instrument (with dimensions of 35 × 35 × 30 cm(3)) to rapidly measure the intensity distribution in three dimensions of the focused fields of vectorial beams and any other incident beams. This instrument employs a fluorescent nanoparticle as a probe to scan the focal region to obtain a high spatial resolution of intensity distribution...
June 2017: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28663890/review-of-adaptive-optics-oct-ao-oct-principles-and-applications-for-retinal-imaging-invited
#13
REVIEW
Michael Pircher, Robert J Zawadzki
In vivo imaging of the human retina with a resolution that allows visualization of cellular structures has proven to be essential to broaden our knowledge about the physiology of this precious and very complex neural tissue that enables the first steps in vision. Many pathologic changes originate from functional and structural alterations on a cellular scale, long before any degradation in vision can be noted. Therefore, it is important to investigate these tissues with a sufficient level of detail in order to better understand associated disease development or the effects of therapeutic intervention...
May 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/28660306/shear-wave-velocity-measurement-of-upper-trapezius-muscle-by-color-doppler-shear-wave-imaging
#14
Atsushi Yamamoto, Yoshiki Yamakoshi, Takashi Ohsawa, Hitoshi Shitara, Tsuyoshi Ichinose, Hiroyuki Shiozawa, Tsuyoshi Sasaki, Noritaka Hamano, Yasushi Yuminaka, Kenji Takagishi
PURPOSE: Skeletal muscle stiffness is thought to be the result of increased tissue hardness, but measurement accuracy has been dependent on operator technique. We have proposed a novel shear wave real-time imaging method (color Doppler shear wave imaging: CD SWI) with continuous shear waves excited from the tissue surface by a mechanical vibrator. METHODS: Using the method, shear wave velocity was measured for the upper trapezius muscle. Adaptive shear wave velocity measurement by means of quality estimation of shear wave wavefront was adopted...
June 28, 2017: Journal of Medical Ultrasonics
https://www.readbyqxmd.com/read/28642460/standing-wave-effect-and-fractal-structure-in-dislocation-evolution
#15
P Li, Z F Zhang
Theoretical model required for the evolution of regular dislocation pattern should simultaneously take into account both static distribution and dynamic evolution of dislocation pattern. In principle, there exists a stable uniformly moving dislocation with both core and far field advancing at the same constant velocity, which suggests the existence of the traveling waves representing moving dislocation. Therefore, one new term "dislocation wave" is defined by simultaneously consisting of both an elastic wave and a dislocation in each wavefront...
June 22, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28640145/comparison-of-implantable-collamer-lens-visian-icl-v4-and-icl-v4c-for-high-myopia-a-cohort-study
#16
COMPARATIVE STUDY
Ying Tian, Hai-Bo Jiang, Jian Jiang, Dan Wen, Xiao-Bo Xia, Wei-Tao Song
The aim of this study was to investigate the visual quality of the 2 kinds of intraocular lens: Visian implantable collamer lens (ICL) V4 and Visian ICL V4c implantations for high myopia.Twenty cases (20 eyes) with high myopia who received Visian ICL V4 implantation and 18 cases (18 eyes) with high myopia who received Visian ICL V4c implantation in our hospital from April 1, 2014 to November 31, 2016 were enrolled. In 1-month follow-up, near vision, best corrected distant visual acuity (BCVA), uncorrected distant visual acuity (UDVA), and wavefront aberrations were measured, and compensation factor was calculated...
June 2017: Medicine (Baltimore)
https://www.readbyqxmd.com/read/28631305/two-years-results-of-small-incision-lenticule-extraction-and-wavefront-guided-laser-in%C3%A2-situ-keratomileusis-for-myopia
#17
Hidenaga Kobashi, Kazutaka Kamiya, Akihito Igarashi, Masahide Takahashi, Kimiya Shimizu
PURPOSE: To compare the 2-years visual and refractive outcomes between small-incision lenticule extraction (SMILE) and wavefront-guided laser in situ keratomileusis (LASIK) in eyes with myopia and myopic astigmatism. METHODS: Our retrospective case-control study examined 30 eyes of 30 patients with the manifest refraction spherical equivalent (MRSE) of -3.71 ± 1.83 dioptres (D) who underwent SMILE and 30 eyes of 30 patients with MRSE of -3.81 ± 1.40 D who underwent wavefront-guided LASIK...
June 20, 2017: Acta Ophthalmologica
https://www.readbyqxmd.com/read/28615923/changes-in-meibomian-gland-morphology-and-ocular-higher-order-aberrations-in-eyes-with-chalazion
#18
Shima Fukuoka, Reiko Arita, Rika Shirakawa, Naoyuki Morishige
PURPOSE: To examine the changes in meibomian gland morphology and ocular higher-order aberrations (HOAs) in eyes with chalazion and its excision. METHODS: Seven male patients with previous history of chalazion excision and seven control male subjects were enrolled. Changes in meibomian gland morphology (meiboscores, gland dropout, and shortening) were evaluated by using meibography equipped in a wavefront analyzer KR-1W and in a slit-lamp device BG-4M. Ocular HOAs were measured sequentially with KR-1W...
2017: Clinical Ophthalmology
https://www.readbyqxmd.com/read/28613179/unsupervised-learning-of-spike-pattern-for-seizure-detection-and-wavefront-estimation-of-high-resolution-micro-electrocorticographic-%C3%AE-ecog-data
#19
Yilin Song, Yao Wang, Jonathan Viventi
For the past few years, we have developed flexible, active, multiplexed recording devices for high resolution recording over large, clinically relevant areas in the brain. While this technology has enabled a much higher-resolution view of the electrical activity of the brain, the analytical methods to process, categorize and respond to the huge volumes of seizure data produced by these devices have not yet been developed. In this work we proposed an unsupervised learning framework for spike analysis, which by itself reveals spike pattern...
June 9, 2017: IEEE Transactions on Nanobioscience
https://www.readbyqxmd.com/read/28597602/multifunctional-hyperbolic-nanogroove-metasurface-for-submolecular-detection
#20
Li Jiang, Shuwen Zeng, Zhengji Xu, Qingling Ouyang, Dao-Hua Zhang, Peter Han Joo Chong, Philippe Coquet, Sailing He, Ken-Tye Yong
Metasurface serves as a promising plasmonic sensing platform for engineering the enhanced light-matter interactions. Here, a hyperbolic metasurface with the nanogroove structure in the subwavelength scale is designed. This metasurface is able to modify the wavefront and wavelength of surface plasmon wave with the variation of the nanogroove width or periodicity. At the specific optical frequency, surface plasmon polaritons are tightly confined and propagated with a diffraction-free feature due to the epsilon-near-zero effect...
June 8, 2017: Small
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