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https://www.readbyqxmd.com/read/29609357/implementation-of-a-violet-scheimpflug-lidar-system-for-atmospheric-aerosol-studies
#1
Liang Mei, Zheng Kong, Peng Guan
A violet Scheimpflug lidar system employing a 1-W 407-nm multimode laser diode is developed for remote sensing of atmospheric aerosols. The laser beam of the laser diode that is transmitted into atmosphere has been investigated in detail and a cylindrical lens pair is designed to improve the geometrical transmission efficiency. A measurement scheme with automatic exposure as well as a generalized signal processing method are established to optimize the signal-to-noise ratio of lidar signals. The performance of the violet Scheimpflug lidar system has been evaluated during a six-day continuous measurement campaign on a near horizontal path...
March 19, 2018: Optics Express
https://www.readbyqxmd.com/read/29609345/time-resolved-fabry-perot-measurements-of-cavity-temperature-in-pulsed-qcls
#2
S Gundogdu, H S Pisheh, A Demir, M Gunoven, A Aydinli, C Sirtori
Temperature rise during operation is a central concern of semiconductor lasers and especially difficult to measure during a pulsed operation. We present a technique for in situ time-resolved temperature measurement of quantum cascade lasers operating in a pulsed mode at ~9.25 μm emission wavelength. Using a step-scan approach with 5 ns resolution, we measure the temporal evolution of the spectral density, observing longitudinal Fabry-Perot modes that correspond to different transverse modes. Considering the multiple thin layers that make up the active layer and the associated Kapitza resistance, thermal properties of QCLs are significantly different than bulk-like laser diodes where this approach was successfully used...
March 19, 2018: Optics Express
https://www.readbyqxmd.com/read/29550021/ethical-and-legal-ramifications-of-using-diode-lasers-for-nonsurgical-periodontal-therapy
#3
Robert A Convissar
BACKGROUND: Lasers are promoted as viable adjunctive treatment methods for nonsurgical periodontal pocket reduction; however, the literature supporting this use is lacking. Multiple meta-analyses found no benefit to laser use for this procedure. The American Dental Association issued clinical practice guidelines about laser use in periodontal pockets, concluding that diode, neodymium:yttrium-aluminum-garnet, and erbium lasers have no benefit as adjunctive therapies to scaling and root planing...
March 13, 2018: Journal of the American Dental Association
https://www.readbyqxmd.com/read/29529762/narrow-linewidth-quasi-continuous-wave-ase-source-based-on-a-multiple-pass-nd-yag-zigzag-slab-amplifier-configuration
#4
Xiaoming Chen, Yanhua Lu, Hao Hu, Lixin Tong, Lei Zhang, Yi Yu, Juntao Wang, Huaijin Ren, Liu Xu
We present investigations into a narrow-linewidth, quasi-continuous-wave pulsed all-solid-state amplified spontaneous emission (ASE) source by use of a novel multiple-pass zigzag slab amplifier. The SE fluorescence emitted from a Nd:YAG slab active medium acts as the seed and is amplified back and forth 8 times through the same slab. Thanks to the angular multiplexing nature of the zigzag slab, high-intensity 1064-nm ASE output can be produced without unwanted self-lasing in this configuration. Experimentally, the output energy, optical conversion efficiency, pulse dynamics, spectral property, and beam quality of the ASE source are studied when the Nd:YAG slab end-pumped by two high-brightness laser diode arrays...
March 5, 2018: Optics Express
https://www.readbyqxmd.com/read/29483499/multiple-field-interstitial-photodynamic-therapy-of-subcutaneously-transplanted-cholangiocellular-carcinoma-rs-1-in-rats
#5
D A Tzerkovsky
The aim of present study was to investigate an antitumor efficacy of multiple-field interstitial photodynamic therapy (iPDT) in vivo. MATERIALS AND METHODS: The study was performed on 15 white random-bred rats with subcutaneously transplanted cholangiocellular carcinoma RS-1. Chlorine-based photosensitizer (PS) Ce6CPPPS was administered via single injection at a dose of 2.5 mg/kg into the animal's caudal vein. Photoirradiation (PI) of tumors was carried out 3 h after PS administration using 7 optical fibers SMA-905 with diode laser with 660 ± 5 nm wavelength at exposure doses of 150 and 300 J/cm² with 0...
July 2017: Experimental Oncology
https://www.readbyqxmd.com/read/29476546/a-randomized-split-scalp-study-comparing-calcipotriol-assisted-mal-pdt-with-conventional-mal-pdt-for-the-treatment-of-actinic-keratosis
#6
L Torezan, B Grinblat, M Haedersdal, N Valente, C Festa-Neto, R M Szeimies
BACKGROUND: Topical photodynamic therapy (PDT) is an approved treatment for actinic keratosis (AK). To enhance the efficacy of PDT for AKs, physical (ablative lasers and microneedling) and chemical (pro-differentiating drugs) pretreatments have been suggested. OBJECTIVES: To compare the efficacy and safety of the combination of topical calcipotriol (CAL) before methylaminolevulinate (MAL)-PDT for AKs of the scalp versus conventional MAL-PDT in a randomized controlled-clinical trial...
February 24, 2018: British Journal of Dermatology
https://www.readbyqxmd.com/read/29469836/rapid-super-resolution-confocal-microscopy-through-virtual-structured-detection-based-on-serial-scanning-in-array
#7
Limin Zou, He Ni, Qingyuan Guo, Qing Yan, Xuemei Ding
To improve the imaging speed of a confocal microscope with virtual structured detection, we have designed an optical system with rigid coordination control of the CCD, galvanometer scanner, and laser diode. In this system, the width of the coherent transfer function expands, which enhances the lateral resolution by a factor of 1.4. Also, the temporal image sequence is transformed to a spatial one so that multiple images can be acquired during a single exposure period of the CCD. This method increases the system imaging speed 25-fold at least, and an even higher speed can be achieved by further increasing the number of spots recorded during a single exposure period...
February 20, 2018: Applied Optics
https://www.readbyqxmd.com/read/29425175/laser-based-monitoring-of-ch%C3%A2-co%C3%A2-nh%C3%A2-and-h%C3%A2-s-in-animal-farming-system-characterization-and-initial-demonstration
#8
Dorota Stachowiak, Piotr Jaworski, Paweł Krzaczek, Grzegorz Maj, Michał Nikodem
In this paper, we present a system for sequential detection of multiple gases using laser-based wavelength modulation spectroscopy (WMS) method combined with a Herriot-type multi-pass cell. Concentration of hydrogen sulfide (H₂S), methane (CH₄), carbon dioxide (CO₂), and ammonia (NH₃) are retrieved using three distributed feedback laser diodes operating at 1574.5 nm (H₂S and CO₂), 1651 nm (CH₄), and 1531 nm (NH₃). Careful adjustment of system parameters allows for H₂S sensing at single parts-per-million by volume (ppmv) level with strongly reduced interference from adjacent CO₂ transitions even at atmospheric pressure...
February 9, 2018: Sensors
https://www.readbyqxmd.com/read/29399308/comparison-of-tooth-color-change-after-bleaching-with-conventional-and-different-light-activated-methods
#9
Sima Shahabi, Hadi Assadian, Alireza Mahmoudi Nahavandi, Hanieh Nokhbatolfoghahaei
Introduction: The demand for esthetic dental treatments is increasing in recent years mainly due to improved oral hygiene and better maintenance of oral health and teeth in older individuals. Bleaching of discolored anterior teeth is the most popular among esthetic dental treatments. Even individuals with sound teeth and adequate esthetics seek to have whiter teeth in the anterior region. The aim of this study was to evaluate tooth color changes following conventional in-office bleaching techniques compared to light-activated methods using different light sources...
2018: Journal of Lasers in Medical Sciences
https://www.readbyqxmd.com/read/29380865/nasopharyngeal-sialoceles-in-11-brachycephalic-dogs
#10
Davide De Lorenzi, Diana Bertoncello, Chiara Mantovani, Enrico Bottero
OBJECTIVE: To report clinical features, diagnosis, surgical treatment, and outcomes of brachycephalic dogs with nasopharyngeal sialoceles (NPS). STUDY DESIGN: Retrospective case series. ANIMALS: Eleven brachycephalic dogs with NPS. METHODS: Diagnosis of NPS was based on identification of cystic nasopharyngeal masses containing saliva-like mucoid material on retroflexed endoscopy. Biopsies were obtained to support the diagnosis...
January 30, 2018: Veterinary Surgery: VS
https://www.readbyqxmd.com/read/29297558/an-evaluation-of-the-light-output-from-22-contemporary-light-curing-units
#11
Carlos José Soares, Monise de Paula Rodrigues, Laís Rani Sales Oliveira, Stella Sueli Lourenço Braga, Luciana Mendes Barcelos, Gisele Rodrigues da Silva, Marcelo Giannini, Richard Bengt Price
This study measured the radiant power (mW), irradiance (mW/cm2) and emission spectra (mW/cm2/nm) of 22 new, or almost new, light curing units (LCUs): - Alt Lux II, BioLux Standard, Bluephase G2, Curing Light XL 3000, Demetron LC, DX Turbo LED 1200, EC450, EC500, Emitter C, Emitter D, KON-LUX, LED 3M ESPE, Led Lux II, Optilight Color, Optilight Max, Optilux 501, Poly Wireless, Radii cal, Radii plus, TL-01, VALO Cordless. These LCUs were either monowave or multiple peak light emitting diode (LED) units or quartz-tungsten-halogen LCUs used in anterior and posterior teeth...
May 2017: Brazilian Dental Journal
https://www.readbyqxmd.com/read/29221053/ultra-high-speed-plif-imaging-for-simultaneous-visualization-of-multiple-species-in-turbulent-flames
#12
Zhenkan Wang, Panagiota Stamatoglou, Zheming Li, Marcus Aldén, Mattias Richter
In order to obtain more detailed characteristics and information in highly turbulent flames, for a better understanding of the transient behavior of eddies in such flames, a measurement technique with sufficient temporal resolution is requested. However, the probing of species distributions relevant in combustion (e.g. OH, CH2 O) with ultra-high-speed laser diagnostics still remains a challenge. Nd:YAG clusters commercially available can generate only 4-8 pulses, although with high laser energy. Systems based on a diode-pumped solid-state Nd:YAG laser combined with a dye laser produce only about 100 μJ pulse energy at ultra-high repetition rates (≥50 kHz)...
November 27, 2017: Optics Express
https://www.readbyqxmd.com/read/29131193/frequency-and-timing-stability-of-an-airborne-injection-seeded-nd-yag-laser-system-for-direct-detection-wind-lidar
#13
Christian Lemmerz, Oliver Lux, Oliver Reitebuch, Benjamin Witschas, Christian Wührer
We report on the design and performance of the laser deployed in the airborne demonstrator Doppler wind lidar for the Aeolus mission of the European Space Agency (ESA). The all-solid-state, diode-pumped and frequency-tripled Nd:YAG laser is realized as a master oscillator power amplifier (MOPA) system, generating 60 mJ of single-frequency pulses at 355 nm wavelength, 50 Hz repetition rate and 20 ns pulse duration. For the measurement of the Doppler frequency shift over several accumulated laser shots, the frequency stability of the laser is of crucial importance...
November 10, 2017: Applied Optics
https://www.readbyqxmd.com/read/29105645/understanding-gan-ingan-core-shell-growth-towards-high-quality-factor-whispering-gallery-modes-from-non-polar-ingan-quantum-wells-on-gan-rods
#14
C Tessarek, S Rechberger, C Dieker, M Heilmann, E Spiecker, S Christiansen
GaN microrods are used as a basis for subsequent InGaN quantum well (QW) and quantum dot deposition by metal-organic vapor phase epitaxy. The coverage of the shell along the sidewall of rods is dependent on the rod growth time and a complete coverage is obtained for shorter rod growth times. Transmission electron microscopy measurements are performed to reveal the structural properties of the InGaN layer on the sidewall facet and on the top facet. The presence of layers in the microrod and on the microrod surface will be discussed with respect to GaN and InGaN growth...
November 6, 2017: Nanotechnology
https://www.readbyqxmd.com/read/29091666/high-depth-resolution-range-imaging-with-multiple-wavelength-superheterodyne-interferometry-using-1550-nm-lasers
#15
Fengqiang Li, Joshua Yablon, Andreas Velten, Mohit Gupta, Oliver Cossairt
Lasers and laser diodes are widely used as illumination sources for optical imaging techniques. Time-of-flight (ToF) cameras with laser diodes and range imaging based on optical interferometry systems using lasers are among these techniques, with various applications in fields such as metrology and machine vision. ToF cameras can have imaging ranges of several meters, but offer only centimeter-level depth resolution. On the other hand, range imaging based on optical interferometry has depth resolution on the micrometer and even nanometer scale, but offers very limited (sub-millimeter) imaging ranges...
November 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/29077539/oxygen-enriched-photosensitizer-medium-with-red-blood-cells-to-study-tissue-interaction-of-photosensitization-reaction
#16
Risa Hamada, Emiyu Ogawa, Tsunenori Arai
BACKGROUND: It has been reported that the oxygen pressure of a photosensitizer medium decreases during an irradiation leading to decrease in the efficacy of the photosensitization reaction against the target cell in vitro. OBJECTIVE: The aim of this study was to obtain solutions with high dissolved oxygen levels in cultivated wells with perceiving oxygen environment and photosensitizer bleaching for photosensitization reaction studies. MATERIALS AND METHODS: We used a 10-mm-wide optical cell cuvette with a 1-mm optical path length as the well...
October 27, 2017: Photomedicine and Laser Surgery
https://www.readbyqxmd.com/read/29071034/alterations-in-auditory-electrophysiological-responses-associated-with-temporary-suppression-of-tinnitus-induced-by-low-level-laser-therapy-a-before-after-case-series
#17
Katayoon Montazeri, Saeid Mahmoudian, Zahra Razaghi, Mohammad Farhadi
Introduction: Tinnitus is the phantom auditory perception of sound in the absence of an external or internal acoustic stimulus. The treatment is difficult due to multiple etiologies and great psychological influence. The purpose of this study was to determine alterations in auditory physiological and electrophysiological responses associated with temporary suppression of tinnitus induced by low-level laser (LLL) irradiation. Methods: This study was conducted on 20 subjects with subjective tinnitus. All subjects signed the informed consent form and satisfied all the study eligibility criteria...
2017: Journal of Lasers in Medical Sciences
https://www.readbyqxmd.com/read/29071032/comparative-effectiveness-of-low-level-laser-therapy-and-transcutaneous-electric-nerve-stimulation-on-temporomandibular-joint-disorders
#18
Massoud Seifi, Asghar Ebadifar, Sattar Kabiri, Mohammad Reza Badiee, Zahra Abdolazimi, Parisa Amdjadi
Introduction: Temporomandibular joint disorders (TMDs) are the most common source of pain on the face. There are multiple etiologies, and several types of treatment have been reported. The use of non-invasive and reversible therapies in the treatment of such problems is recommended. The present study evaluated the effect of low-level laser (LLL) therapy and transcutaneous electric nerve stimulation (TENS) on TMDs. Methods: In this single-blind study, 40 patients with temporomandibular disorders were randomly divided into four groups: TENS (TENSTem dental), LLL (diode 810 nm CW), shamTENS, and sham-LLL...
2017: Journal of Lasers in Medical Sciences
https://www.readbyqxmd.com/read/29048054/coherent-laser-phase-retrieval-in-the-presence-of-measurement-imperfections-and-incoherent-light
#19
Anders K Hansen
Phase retrieval is a powerful numerical method that can be used to determine the wavefront of laser beams based only on intensity measurements, without the use of expensive, low-resolution specialized wavefront sensors such as Shack-Hartmann sensors. However, phase retrieval techniques generally suffer from poor convergence and fidelity when the input measurements contain electronic or optical noise and/or an incoherent intensity contribution overlapped with the otherwise spatially coherent laser beam. Here, we present an implementation of a modified version of the standard multiple-plane Gerchberg-Saxton algorithm and demonstrate that it is highly successful at extracting the intensity profile and wavefront of the spatially coherent part of the light from various lasers, including tapered laser diodes, at a very high fidelity despite the presence of incoherent light and noise...
September 10, 2017: Applied Optics
https://www.readbyqxmd.com/read/29041690/critical-side-channel-effects-in-random-bit-generation-with-multiple-semiconductor-lasers-in-a-polarization-based-quantum-key-distribution-system
#20
Heasin Ko, Byung-Seok Choi, Joong-Seon Choe, Kap-Joong Kim, Jong-Hoi Kim, Chun Ju Youn
Most polarization-based BB84 quantum key distribution (QKD) systems utilize multiple lasers to generate one of four polarization quantum states randomly. However, random bit generation with multiple lasers can potentially open critical side channels that significantly endangers the security of QKD systems. In this paper, we show unnoticed side channels of temporal disparity and intensity fluctuation, which possibly exist in the operation of multiple semiconductor laser diodes. Experimental results show that the side channels can enormously degrade security performance of QKD systems...
August 21, 2017: Optics Express
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