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Femtosecond laser

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https://www.readbyqxmd.com/read/29776767/-visual-outcomes-5-years-after-small-incision-lenticule-extraction-smile-surgery-on-spherocylindrical-myopia-eyes-from-616-eyes
#1
J Burazovitch, H Ferguene, D Naguszewski
OBJECTIVE: Determine if the visual criteria of the technique of surgery refractive by Femtosecond Laser-assisted duckweed Extraction - Small Lenticule Extraction (FLEx-Smile® ), realized in the laser femtosecond VisuMax® (Carl Zeiss Meditec, Jena, Germany), are stable, secure, effective and predictable in the long term, to the nearsighted and astigmatic. MODEL OF THE STUDY: Retrospective study, monocentric with data collected between March 2012 and March 2017...
May 15, 2018: Journal Français D'ophtalmologie
https://www.readbyqxmd.com/read/29776312/on-the-prospects-of-using-high-intensity-thz-pulses-to-induce-ultrafast-temperature-jumps-in-liquid-water
#2
Pankaj Kr Mishra, Vincent Bettaque, Oriol Vendrell, Robin Santra, Ralph Welsch
Ultrashort, high-intensity THz pulses, e.g., created at free-electron laser facilities, allow for direct investigation as well as the driving of intermolecular modes in liquids like water and thus will deepen our understanding of the hydrogen bonding network. In this work, the temperature-jump (T-jump) of water induced by THz radiation is simulated for ten different THz frequencies in the range from 3 to 30 THz and five different pulse intensities in the range from 1 × 1011 to 5 × 1012 W/cm2 employing both ab initio molecular dynamics (AIMD) and force field molecular dynamics (FFMD) approaches...
May 18, 2018: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/29773458/outcomes-of-conventional-phacoemulsification-versus-femtosecond-laser-assisted-cataract-surgery-in-eyes-with-fuchs-endothelial-corneal-dystrophy
#3
Dagny C Zhu, Parth Shah, William J Feuer, Wei Shi, Ellen H Koo
PURPOSE: To compare the outcomes in eyes with Fuchs endothelial corneal dystrophy after standard phacoemulsification with those of femtosecond laser-assisted cataract surgery. SETTING: Bascom Palmer Eye Institute, Miami, Florida, USA. DESIGN: Retrospective case series. METHODS: Charts from patients diagnosed with Fuchs endothelial corneal dystrophy who had phacoemulsification cataract surgery at Bascom Palmer Eye Institute between January 1, 2014, and January 1, 2017, were reviewed...
May 15, 2018: Journal of Cataract and Refractive Surgery
https://www.readbyqxmd.com/read/29772169/multiphoton-up-conversion-emission-from-diamond-single-crystals
#4
Yunfeng Wang, Wenfei Zhang, Chao-Nan Lin, Pengpeng Ren, Ying-Jie Lu, Chongxin Shan, Siu Fung Yu
Room-temperature up-conversion emission up to eight-photon absorption is demonstrated from diamond single crystals under femtosecond laser excitation for the first time. The low concentration of defects and impurities is attributed to the support of free excitons emission at 235 nm. Nonlinear optical properties are also investigated by using an open aperture Z-scan technique. The corresponding three-, five- and eight-photon absorption coefficients of the diamonds are found to be 1.8×10-2 cm3/GW2, 5×10-9 cm7/GW4 and 1...
May 17, 2018: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29772050/combined-femtosecond-laser-assisted-cataract-surgery-and-small-gauge-pars-plana-vitrectomy-using-different-devices-a-new-trend-for-vitreoretinal-surgery
#5
Bruno de Queiroz Alves, Oswaldo Ferreira Moura Brasil, Cristiano Toesca Espinhosa, Ricardo Miguel Japiassu, Mariana Batista Gonçalves, Otaviano Magalhães Júnior, André Maia, Emmerson Badaró, Paula Serraino, Arturo Alezzandrinni, Mauricio Maia
BACKGROUND AND OBJECTIVE: To report the efficacy, safety, and benefits of femtosecond laser-assisted cataract surgery (FLACS) combined with sutureless 23-gauge pars plana vitrectomy (PPV). PATIENTS AND METHODS: This multicenter, retrospective study evaluated patient records and videos of 43 cases with retinal pathologies and cataract who underwent the combined procedure. RESULTS: In 44.2% and 55.8% of cases, respectively, the LenSx Laser (femtosecond machine; Alcon, Fort Worth, TX) and the Constellation (vitreous cutter; Alcon, Fort Worth, TX), and the Victus (femtosecond machine; Bausch + Lomb, Rochester, NY) and Stellaris PC (vitreous cutter; Bausch + Lomb, Rochester, NY) were used...
May 1, 2018: Ophthalmic Surgery, Lasers & Imaging Retina
https://www.readbyqxmd.com/read/29771882/-morphological-changes-of-cornea-in-children-with-hyperopia-in-the-immediate-and-remote-postoperative-period-after-laser-keratomieleusis-according-to-confocal-microscopy-data
#6
I L Kulikova, N P Pashtaev, O V Shlenskaya
Studying morphological changes of cornea in the remote postoperative period is becoming increasingly relevant with refractive surgeries being adapted for children. PURPOSE: comparative analysis of keratocyte density and hystomorphologic changes of cornea after laser in situ keratomieleusis (LASIK) and femtosecond laser-assisted LASIK (FS-LASIK) in children with hyperopia. MATERIAL AND METHODS: 109 patients aged 6-17 years in 2 groups were examined with 'Confoscan-4' confocal microscope...
2018: Vestnik Oftalmologii
https://www.readbyqxmd.com/read/29769600/x-ray-based-virtual-histology-allows-guided-sectioning-of-heavy-ion-stained-murine-lungs-for-histological-analysis
#7
Jonas Albers, M Andrea Markus, Frauke Alves, Christian Dullin
Examination of histological or immunohistochemically stained 2D sections of embedded tissue is one of the most frequently used tools in biomedical research and clinical routine. Since to date, targeted sectioning of specific regions of interest (ROI) in the sample is not possible, we aimed at developing a guided sectioning approach based on x-ray 3D virtual histology for heavy ion stained murine lung samples. For this purpose, we increased the contrast to noise ratio of a standard benchtop microCT by 5-10-fold using free-propagation phase contrast imaging and thus substantially improved image quality...
May 16, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29769544/towards-a-petawatt-class-few-cycle-infrared-laser-system-via-dual-chirped-optical-parametric-amplification
#8
Yuxi Fu, Katsumi Midorikawa, Eiji J Takahashi
Expansion of the wavelength range for an ultrafast laser is an important ingredient for extending its range of applications. Conventionally, optical parametric amplification (OPA) has been employed to expand the laser wavelength to the infrared (IR) region. However, the achievable pulse energy and peak power have been limited to the mJ and the GW level, respectively. A major difficulty in the further energy scaling of OPA results from a lack of suitable large nonlinear crystals. Here, we circumvent this difficulty by employing a dual-chirped optical parametric amplification (DC-OPA) scheme...
May 16, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29767210/low-threshold-lasing-from-colloidal-cdse-cdsete-core-alloyed-crown-type-ii-heteronanoplatelets
#9
Yuan Gao, Mingjie Li, Savas Delikanli, Haiyang Zheng, Baiquan Liu, Cuong Dang, Tze Chien Sum, Hilmi Volkan Demir
Colloidal type-II heterostructures are believed to be a promising solution-processed gain medium given their spatially separated electrons and holes for the suppression of Auger recombination and their wider emission tuning range from the visible to near-infrared region. Amplified spontaneous emission (ASE) was achieved from colloidal type-II core/shell nanocrystals several years ago. However, due to the limited charge-transfer (CT) interfacial states and minimal overlap of electron and hole wave functions, the ASE threshold has still been very high...
May 16, 2018: Nanoscale
https://www.readbyqxmd.com/read/29762581/dielectric-mirror-less-femtosecond-optical-parametric-oscillator-with-ultrabroad-band-tunability
#10
Jintao Fan, Chenglin Gu, Jun Zhao, Ruoyu Liao, Yuxi Chu, Lu Chai, Chingyue Wang, Minglie Hu
We demonstrate a high average power, widely tunable, dielectric-mirror-less optical parametric oscillator (OPO) based on MgO:PPLN (MgO-doped periodically poled lithium niobate), which is synchronously pumped by a 1040 nm femtosecond fiber laser. The OPO does not require any dielectric coating mirrors. By exploiting the four-prism sequence system, combined with the gold mirrors, the oscillating laser pulses could span the spectral regions in both the signal and idler, and the output pulses of OPO can be tuned across 1367-1914 nm in the signal, and 2152-4480 nm in the idler as well...
May 15, 2018: Optics Letters
https://www.readbyqxmd.com/read/29762544/femtosecond-laser-texturing-of-surfaces-for-tribological-applications
#11
Jörn Bonse, Sabrina V Kirner, Michael Griepentrog, Dirk Spaltmann, Jörg Krüger
Laser texturing is an emerging technology for generating surface functionalities on basis of optical, mechanical, or chemical properties. Taking benefit of laser sources with ultrashort (fs) pulse durations features outstanding precision of machining and negligible rims or burrs surrounding the laser-irradiation zone. Consequently, additional mechanical or chemical post-processing steps are usually not required for fs-laser surface texturing (fs-LST). This work aimed to provide a bridge between research in the field of tribology and laser materials processing...
May 15, 2018: Materials
https://www.readbyqxmd.com/read/29760991/compact-fiber-based-multi-photon-endoscope-working-at-1700-nm
#12
Farhad Akhoundi, Yukun Qin, N Peyghambarian, Jennifer K Barton, Khanh Kieu
We present the design, implementation and performance analysis of a compact multi-photon endoscope based on a piezo electric scanning tube. A miniature objective lens with a long working distance and a high numerical aperture (≈ 0.5) is designed to provide a diffraction limited spot size. Furthermore, a 1700 nm wavelength femtosecond fiber laser is used as an excitation source to overcome the scattering of biological tissues and reduce water absorption. Therefore, the novel optical system along with the unique wavelength allows us to increase the imaging depth...
May 1, 2018: Biomedical Optics Express
https://www.readbyqxmd.com/read/29760050/ultrafast-nonthermal-heating-of-water-initiated-by-an-x-ray-free-electron-laser
#13
Kenneth R Beyerlein, H Olof Jönsson, Roberto Alonso-Mori, Andrew Aquila, Saša Bajt, Anton Barty, Richard Bean, Jason E Koglin, Marc Messerschmidt, Davide Ragazzon, Dimosthenis Sokaras, Garth J Williams, Stefan Hau-Riege, Sébastien Boutet, Henry N Chapman, Nicuşor Tîmneanu, Carl Caleman
The bright ultrafast pulses of X-ray Free-Electron Lasers allow investigation into the structure of matter under extreme conditions. We have used single pulses to ionize and probe water as it undergoes a phase transition from liquid to plasma. We report changes in the structure of liquid water on a femtosecond time scale when irradiated by single 6.86 keV X-ray pulses of more than 106 J/cm2 These observations are supported by simulations based on molecular dynamics and plasma dynamics of a water system that is rapidly ionized and driven out of equilibrium...
May 14, 2018: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29759685/evaluation-of-the-small-aperture-intracorneal-inlay-three-year-results-from-the-cohort-of-the-u-s-food-and-drug-administration-clinical-trial
#14
John A Vukich, Daniel S Durrie, Jay S Pepose, Vance Thompson, Corina van de Pol, Ling Lin
PURPOSE: To evaluate the safety and effectiveness of the Kamra small-aperture intracorneal inlay. SETTING: Centers in North America, Europe, Asia, and Australia. DESIGN: Prospective clinical trial. METHODS: Patients with emmetropic presbyopia had intracorneal implantation of the inlay in the nondominant eye. RESULTS: The study comprised 507 patients with emmetropic presbyopia who were aged 45 to 60 years old...
May 11, 2018: Journal of Cataract and Refractive Surgery
https://www.readbyqxmd.com/read/29758641/evaluation-of-temperature-history-of-a-spherical-nanosystem-irradiated-with-various-short-pulse-laser-sources
#15
Arnab Lahiri, Pranab K Mondal
Spatiotemporal thermal response and characteristics of net entropy production rate of a gold nanosphere (radius: 50-200 nm), subjected to a short-pulse, femtosecond laser is reported. In order to correctly illustrate the temperature history of laser-metal interaction(s) at picoseconds transient with a comprehensive single temperature definition in macroscale and to further understand how the thermophysical response of the single-phase lag (SPL) and dual-phase lag (DPL) frameworks (with various lag-ratios') differs, governing energy equations derived from these benchmark non-Fourier frameworks are numerically solved and thermodynamic assessment under both the classical irreversible thermodynamics (CIT) as well as extended irreversible thermodynamics (EIT) frameworks is subsequently carried out...
April 2018: Physical Review. E
https://www.readbyqxmd.com/read/29757850/corneal-irregular-astigmatism-and-curvature-changes-after-small-incision-lenticule-extraction-three-year-follow-up
#16
Haris Sideroudi, Apostolos Lazaridis, Anke Messerschmidt-Roth, Georgios Labiris, Vassilios Kozobolis, Walter Sekundo
PURPOSE: To evaluate the long-term changes in anterior and posterior corneal irregular astigmatism and curvatures after small incision lenticule extraction (SMILE). METHODS: Fifty eyes of 28 patients underwent SMILE for myopic astigmatism. All procedures were performed using the VisuMax® femtosecond laser. A Scheimpflug camera was used for preoperative and 3-year postoperative tomography. Anterior and posterior corneal Fourier parameters (spherical component, regular astigmatism, asymmetry, and irregularity) and curvature data were evaluated and compared within 2 subgroups according to the magnitude of the refractive correction (low myopia group: spherical equivalent (SEQ) ≥ -6 D; high myopia group: (SEQ) < -6 D)...
April 27, 2018: Cornea
https://www.readbyqxmd.com/read/29757240/multifunctional-hierarchical-surface-structures-by-femtosecond-laser-processing
#17
Clemens Kunz, Frank A Müller, Stephan Gräf
Hierarchical surface structures were fabricated on fused silica by using a fs-laser with a pulse duration &tau; = 300 fs and a wavelength &lambda; = 512 nm. The resulting surface structures were characterized by scanning electron microscopy, atomic force microscopy and white light interference microscopy. The optical properties were analyzed by transmittance measurements using an integrating sphere and the wettability was evaluated by measuring the water contact angle &theta; . The silanization of structured fused silica surfaces with trichloro(1H,1H,2H,2H-perfluorooctyl)silane allows to switch the wettability from superhydrophilic ( &theta; = 0&deg;) to superhydrophobic behavior with &theta; exceeding 150&deg;...
May 12, 2018: Materials
https://www.readbyqxmd.com/read/29756040/experimental-two-dimensional-quantum-walk-on-a-photonic-chip
#18
Hao Tang, Xiao-Feng Lin, Zhen Feng, Jing-Yuan Chen, Jun Gao, Ke Sun, Chao-Yue Wang, Peng-Cheng Lai, Xiao-Yun Xu, Yao Wang, Lu-Feng Qiao, Ai-Lin Yang, Xian-Min Jin
Quantum walks, in virtue of the coherent superposition and quantum interference, have exponential superiority over their classical counterpart in applications of quantum searching and quantum simulation. The quantum-enhanced power is highly related to the state space of quantum walks, which can be expanded by enlarging the photon number and/or the dimensions of the evolution network, but the former is considerably challenging due to probabilistic generation of single photons and multiplicative loss. We demonstrate a two-dimensional continuous-time quantum walk by using the external geometry of photonic waveguide arrays, rather than the inner degree of freedoms of photons...
May 2018: Science Advances
https://www.readbyqxmd.com/read/29749417/ultrafast-saturable-absorption-in-tis-2-induced-by-non-equilibrium-electrons-and-the-generation-of-a-femtosecond-mode-locked-laser
#19
Xiangling Tian, Rongfei Wei, Meng Liu, Chunhui Zhu, Zhichao Luo, Fengqiu Wang, Jianrong Qiu
Non-equilibrium electrons induced by ultrafast laser excitation in a correlated electron material can disturb the Fermi energy as well as optical nonlinearity. Here, non-equilibrium electrons translate a semiconductor TiS2 material into a plasma to generate broad band nonlinear optical saturable absorption with a sub-picosecond recovery time of ∼768 fs (corresponding to modulation frequencies over 1.3 THz) and a modulation response up to ∼145%. Based on this optical nonlinear modulator, a stable femtosecond mode-locked pulse with a pulse duration of ∼402 fs and a pulse train with a period of ∼175...
May 11, 2018: Nanoscale
https://www.readbyqxmd.com/read/29748674/laser-induced-formation-of-bismuth-nanoparticles
#20
Marcelo Assis, Eloísa Cordoncillo, Rafael Torres-Mendieta, Héctor Beltrán-Mir, Gladys Mínguez-Vega, Amanda Fernandes Gouveia, Edson Leite, Juan Andrés, Elson Longo
In the current communication, the synthesis of metallic Bi nanoparticles with coexisting crystallographic structures (rhombohedral, monoclinic, and cubic) obtained via direct femtosecond laser irradiation of NaBiO3 is demonstrated for the first time. By exploring the use of high laser power values, it is revealed that the promoted laser-mediated reactions lead to the synthesis of coexisting phases in metal nanoparticles, which may be a widely occurring phenomenon in other materials under femtosecond laser irradiation, and a fundamental concern for laser-based nanofabrication...
May 11, 2018: Physical Chemistry Chemical Physics: PCCP
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