Intense Excitation Source of Blue-Green Laser.

DTIC Science & Technology

1985-10-15

plasma focus (DPF) can produce intense uv photons (200-300nm) which match the absorption spectra of both near uv and blue green dye lasers (300-400nm...existing blue green dye laser. On the other hand the dense- plasma focus (DPF) with new optical coupling has been designed and constructed. For the...optimization of the DPF device as the uv pumping light source, the velocity of current sheath and the formation of plasma focus have been measured as

Advanced excimer laser technologies enable green semiconductor manufacturing

NASA Astrophysics Data System (ADS)

Fukuda, Hitomi; Yoo, Youngsun; Minegishi, Yuji; Hisanaga, Naoto; Enami, Tatsuo

2014-03-01

"Green" has fast become an important and pervasive topic throughout many industries worldwide. Many companies, especially in the manufacturing industries, have taken steps to integrate green initiatives into their high-level corporate strategies. Governments have also been active in implementing various initiatives designed to increase corporate responsibility and accountability towards environmental issues. In the semiconductor manufacturing industry, there are growing concerns over future environmental impact as enormous fabs expand and new generation of equipments become larger and more powerful. To address these concerns, Gigaphoton has implemented various green initiatives for many years under the EcoPhoton™ program. The objective of this program is to drive innovations in technology and services that enable manufacturers to significantly reduce both the financial and environmental "green cost" of laser operations in high-volume manufacturing environment (HVM) - primarily focusing on electricity, gas and heat management costs. One example of such innovation is Gigaphoton's Injection-Lock system, which reduces electricity and gas utilization costs of the laser by up to 50%. Furthermore, to support the industry's transition from 300mm to the next generation 450mm wafers, technologies are being developed to create lasers that offer double the output power from 60W to 120W, but reducing electricity and gas consumption by another 50%. This means that the efficiency of lasers can be improve by up to 4 times in 450mm wafer production environments. Other future innovations include the introduction of totally Heliumfree Excimer lasers that utilize Nitrogen gas as its replacement for optical module purging. This paper discusses these and other innovations by Gigaphoton to enable green manufacturing.

Laser diode and pumped Cr:Yag passively Q-switched yellow-green laser at 543 nm

NASA Astrophysics Data System (ADS)

Yao, Y.; Ling, Zhao; Li, B.; Qu, D. P.; Zhou, K.; Zhang, Y. B.; Zhao, Y.; Zheng, Q.

2013-03-01

Efficient and compact yellow green pulsed laser output at 543 nm is generated by frequency doubling of a passively Q-switched end diode-pumped Nd:YVO4 laser at 1086 nm under the condition of sup-pressing the higher gain transition near 1064 nm. With 15 W of diode pump power and the frequency doubling crystal LBO, as high as 1.58 W output power at 543 nm is achieved. The optical to optical conversion efficiency from the corresponding Q-switched fundamental output to the yellow green output is 49%. The peak power of the Q-switched yellow green pulse laser is up to 30 kW with 5 ns pulse duration. The output power stability over 8 hours is better than 2.56% at the maximum output power. To the best of our knowledge, this is the highest watt-level laser at 543 nm generated by frequency doubling of a passively Q-switched end diode pumped Nd:YVO4 laser at 1086 nm.

A linearly-polarized Nd:YVO4/KTP microchip green laser.

PubMed

Jung, C; Yu, B-A; Kim, I-S; Lee, Y L; Yu, N E; Ko, D-K

2009-10-26

We described the principle and the fabrication of a Nd:YVO(4)/KTP microchip for the linearly-polarized green laser and verified its availability by manufacturing and characterizing the green laser using the microchip. Under the driving condition having the modulation frequency of 60 Hz and the duty ratio of 25%, the laser showed the stable linear polarization, the maximum average power of 37 mW, yielding the high electrical-to-optical efficiency of 10.9%.

Compact intra-cavity frequency doubled line beam green laser by a laser diode array pumped

NASA Astrophysics Data System (ADS)

Yan, Boxia; Qi, Yan; Wang, Yanwei

2016-10-01

Compact, high power, and low-cost green laser light sources are needed in projection-related applications such as digital cinema, rear-projection television, simulators, and command and control stations. We report a LD array directly pumped intracavity SHG Nd:YVO4/PPMgLN laser without lens or waveguide in this letter. A compact 3.12 W green laser was demonstrated by intra-cavity frequency doubled using a PPMgLN bulk crystal by a 19-emitter LD array pumped(single bar), the conversion efficiency from input LD array was 9.2%. A line-beam output suitable for laser projectors was generated, which has the potential to be scalable to small volumes and low costs for laser projection displays.

Power blue and green laser diodes and their applications

NASA Astrophysics Data System (ADS)

Hager, Thomas; Strauß, Uwe; Eichler, Christoph; Vierheilig, Clemens; Tautz, Sönke; Brüderl, Georg; Stojetz, Bernhard; Wurm, Teresa; Avramescu, Adrian; Somers, André; Ristic, Jelena; Gerhard, Sven; Lell, Alfred; Morgott, Stefan; Mehl, Oliver

2013-03-01

InGaN based green laser diodes with output powers up to 50mW are now well established for variety of applications ranging from leveling to special lighting effects and mobile projection of 12lm brightness. In future the highest market potential for visible single mode profile lasers might be laser projection of 20lm. Therefore direct green single-mode laser diodes with higher power are required. We found that self heating was the limiting factor for higher current operation. We present power-current characteristics of improved R and D samples with up to 200mW in cw-operation. An optical output power of 100mW is reached at 215mA, a current level which is suitable for long term operation. Blue InGaN laser diodes are also the ideal source for phosphor based generation of green light sources of high luminance. We present a light engine based on LARP (Laser Activated Remote Phosphor) which can be used in business projectors of several thousand lumens on screen. We discuss the advantages of a laser based systems in comparison with LED light engines. LARP requires highly efficient blue power laser diodes with output power above 1W. Future market penetration of LARP will require lower costs. Therefore we studied new designs for higher powers levels. R and D chips with power-current characteristics up to 4W in continuous wave operation on C-mount at 25°C are presented.

Laser-Induced Fluorescence in Gaseous [I[subscript]2] Excited with a Green Laser Pointer

ERIC Educational Resources Information Center

Tellinghuisen, Joel

2007-01-01

A green laser pointer could be used in a flashy demonstration of laser-induced fluorescence in the gas phase by directing the beam of the laser through a cell containing [I[subscript]2] at its room temperature vapor pressure. The experiment could be used to provide valuable insight into the requirements for laser-induced fluorescence (LIF) and the…

[Development of a High Power Green Laser Therapeutic Equipment for Hyperplasia of Prostate].

PubMed

Liang, Jie; Kang, Hongxiang; Shen, Benjian; Zhao, Lusheng; Wu, Xinshe; Chen, Peng; Chang, Aihong; Guo Hua; Guo, Jiayu

2015-09-01

The basic theory of high power green laser equipment for prostate hyperplasia therapy and the components of the system developed are introduced. Considering the requirements of the clinical therapy, the working process of the high power green laser apparatus are designed and the laser with stable output at 120 W is achieved. The controlling hardware and application software are developed, and the safety step is designed. The high power green laser apparatus manufactured with characteristics of stable output, multifunctional and friendly interface provides a choices of prostate hyperplasia therapy for using nationalization instrument.

Spectral cola or how to turn green laser light red

NASA Astrophysics Data System (ADS)

Forró, Csaba; Mettan, Xavier; Humair, Thibaud

2014-11-01

A green laser pointer shone through a glass of cola will appear red when looking from above the glass. Lowering the laser so that it is deeper in the cola, the colour will vary from orange to deep red. Fluorescence and absorption spectra were recorded consistent with the reddening of the laser. The depth dependence of the colour of the immersed laser is attributed to a more significant absorption of the short wavelengths by the cola, making the laser look redder as it is lowered deeper into the cola. To confirm this hypothesis, we simulated the fluorescence spectrum we would get at various depths by applying the Lambert law on our measured fluorescence spectrum. These spectra were then converted into red, green and blue (RGB) values. These values were compared to those measured on images of the immersed laser beam at corresponding depths.

Process Studies on Laser Welding of Copper with Brilliant Green and Infrared Lasers

NASA Astrophysics Data System (ADS)

Engler, Sebastian; Ramsayer, Reiner; Poprawe, Reinhart

Copper materials are classified as difficult to weld with state-of-the-art lasers. High thermal conductivity in combination with low absorption at room temperature require high intensities for reaching a deep penetration welding process. The low absorption also causes high sensitivity to variations in surface conditions. Green laser radiation shows a considerable higher absorption at room temperature. This reduces the threshold intensity for deep penetration welding significantly. The influence of the green wavelength on energy coupling during heat conduction welding and deep penetration welding as well as the influence on the weld shape has been investigated.

Inhibited-coupling HC-PCF based beam-delivery-system for high power green industrial lasers

NASA Astrophysics Data System (ADS)

Chafer, M.; Gorse, A.; Beaudou, B.; Lekiefs, Q.; Maurel, M.; Debord, B.; Gérôme, F.; Benabid, F.

2018-02-01

We report on an ultra-low loss Hollow-Core Photonic Crystal Fiber (HC-PCF) beam delivery system (GLO-GreenBDS) for high power ultra-short pulse lasers operating in the green spectral range (including 515 nm and 532 nm). The GLOBDS- Green combines ease-of-use, high laser-coupling efficiency, robustness and industrial compatible cabling. It comprises a pre-aligned laser-injection head, a sheath-cable protected HC-PCF and a modular fiber-output head. It enables fiber-core gas loading and evacuation in a hermetic fashion. A 5 m long GLO-BDS were demonstrated for a green short pulse laser with a transmission coefficient larger than 80%, and a laser output profile close to single-mode (M2 <1.3).

PicoGreen dye as an active medium for plastic lasers

NASA Astrophysics Data System (ADS)

Pradeep, C.; Vallabhan, C. P. G.; Radhakrishnan, P.; Nampoori, V. P. N.

2015-08-01

Deoxyribonucleic acid lipid complex thin films are used as a host material for laser dyes. We tested PicoGreen dye, which is commonly used for the quantification of single and double stranded DNA, for its applicability as lasing medium. PicoGreen dye exhibits enhanced fluorescence on intercalation with DNA. This enormous fluorescence emission is amplified in a planar microcavity to achieve yellow lasing. Here the role of DNA is not only a host medium, but also as a fluorescence dequencher. With the obtained results we have ample reasons to propose PicoGreen dye as a lasing medium, which can lead to the development of DNA based bio-lasers.

Green high-power tunable external-cavity GaN diode laser at 515  nm.

PubMed

Chi, Mingjun; Jensen, Ole Bjarlin; Petersen, Paul Michael

2016-09-15

A 480 mW green tunable diode laser system is demonstrated for the first time to our knowledge. The laser system is based on a GaN broad-area diode laser and Littrow external-cavity feedback. The green laser system is operated in two modes by switching the polarization direction of the laser beam incident on the grating. When the laser beam is p-polarized, an output power of 50 mW with a tunable range of 9.2 nm is achieved. When the laser beam is s-polarized, an output power of 480 mW with a tunable range of 2.1 nm is obtained. This constitutes the highest output power from a tunable green diode laser system.

Probing longitudinal modes evolution of a InGaN green laser diode

NASA Astrophysics Data System (ADS)

Chen, Yi-Hsi; Lin, Wei-Chen; Chen, Hong-Zui; Shy, Jow-Tsong; Chui, Hsiang-Chen

2018-06-01

This study aims to investigate the longitudinal mode evolution of a InGaN green laser diode. A spectrometer with a 3-pm resolution was employed to obtain the emission spectra of a green laser diode, at a wavelength of around 520 nm, as a function of applied current and temperature. The spectral behavior of the laser modes with applied current was investigated. Right above the lasing threshold, the green diode laser emitted single longitudinal mode output. With increasing applied current, the number of the longitudinal modes increased. Up to ten lasing modes oscillated within the entire gain profile when the applied currents were tuned to 2.2Ith. Subsequently, a multi-Lorentzian profile model was adopted to analyze the spectra and observe how the modes evolved with temperature and applied current.

Relative efficacy of the argon green, argon blue-green, and krypton red lasers for 10-0 nylon subconjunctival laser suture lysis.

PubMed

Mudgil, A V; To, K W; Balachandran, R M; Janigian, R H; Tsiaras, W G

1999-01-01

To determine the optimal wavelength for subconjunctival laser suture lysis. 130 black monofilament 10-0 nylon sutures were sewn subconjunctivally into the bare sclera of enucleated rabbit globes. The lowest energy levels facilitating laser suture lysis were determined for the argon green (514.5 NM), argon blue-green (488.0 NM, 514.5 NM), and krypton red (647.1 NM) wavelengths. In addition, absorption spectroscopy was performed on the suture material and conjunctiva using the Perkin Elmer W/VIS Lambda 2 spectrometer. Krypton red produced the fewest buttonhole defects, and it was also the most efficient energy source for suture lysis (P = 0.0001) under nontenectomized conjunctiva. Absorbance spectra studies revealed peak absorbance at 628 NM for the 10-0 nylon suture material. Based on animal and absorption spectroscopy studies, krypton red may be a safer and more efficient wavelength for subconjunctival laser suture lysis.

First demonstration of green and amber LED-pumped Nd:YAG laser

NASA Astrophysics Data System (ADS)

Tarkashvand, M.; Farahbod, A. H.; Hashemizadeh, S. A.

2018-05-01

For the first time, to the best of our knowledge, a green (520 nm) and amber (592 nm) light emitting diode-pumped Nd:YAG laser is reported. The laser oscillator is a stable semi-planar resonator with a total length of 140 mm. The green (amber) light emitting diode-pumped laser produced a 107 (52) µJ laser energy, at 2.6 (0.7) J electrical pump energy. The oscillator operated at a low repetition rate (about 0.1 Hz) in free-running mode, where the laser spikes were initiated about 210–280 µs after the leading edge of the pump pulse. Moreover, the transverse mode profiles of the resonator, pump absorption efficiency, and optical gain have been studied in some detail.

Compact 151 W green laser with U-type resonator for prostate surgery

NASA Astrophysics Data System (ADS)

Bazyar, Hossein; Aghaie, Mohammad; Daemi, Mohammad Hossein; Bagherzadeh, Seyed Morteza

2013-04-01

We analyzed, designed and fabricated a U-type resonator for intra-cavity frequency doubling of a diode-side-pumped Q-switched Nd:YAG rod laser with high power and high stability for surgery of prostatic tissue. The resonator stability conditions were analyzed graphically in the various configurations for a U-type resonator. We obtained green light at 532 nm using a single KTP crystal, with average output power of 151 W at 10 kHz repetition rate, and with 113 ns pulse duration at 810 W input pump power. We achieved 1064-532 nm conversion efficiency of 75.8%, and pump-to-green optical-optical efficiency of 18.6%. The green power fluctuation was ±1.0% and pointing stability was better than 4 μrad. The green laser output was coupled to a side-firing medical fiber to transfer the laser beam to the prostatic tissue.

Blue, green, orange, and red upconversion laser

DOEpatents

Xie, Ping; Gosnell, Timothy R.

1998-01-01

A laser for outputting visible light at the wavelengths of blue, green, orange and red light. This is accomplished through the doping of a substrate, such as an optical fiber or waveguide, with Pr.sup.3+ ions and Yb.sup.3+ ions. A light pump such as a diode laser is used to excite these ions into energy states which will produce lasing at the desired wavelengths. Tuning elements such as prisms and gratings can be employed to select desired wavelengths for output.

Highly efficient 400  W near-fundamental-mode green thin-disk laser.

PubMed

Piehler, Stefan; Dietrich, Tom; Rumpel, Martin; Graf, Thomas; Ahmed, Marwan Abdou

2016-01-01

We report on the efficient generation of continuous-wave, high-brightness green laser radiation. Green lasers are particularly interesting for reliable and reproducible deep-penetration welding of copper or for pumping Ti:Sa oscillators. By intracavity second-harmonic generation in a thin-disk laser resonator designed for fundamental-mode operation, an output power of up to 403 W is demonstrated at a wavelength of 515 nm with almost diffraction-limited beam quality. The unprecedented optical efficiency of 40.7% of green output power with respect to the pump power of the thin-disk laser is enabled by the intracavity use of a highly efficient grating waveguide mirror, which combines the functions of wavelength stabilization and spectral narrowing, as well as polarization selection in a single element.

GreenLight HPS laser 120-W versus diode laser 200-W vaporization of the prostate: comparative clinical experience.

PubMed

Chiang, Po Hui; Chen, Chien Hsu; Kang, Chih Hsiung; Chuang, Yao Chi

2010-09-01

We present our clinical experiences of two recently introduced vaporization laser systems: the GreenLight High Performance System (HPS) laser (532 nm, 120 W) and the Diolas LFD diode laser (980 nm, 200 W). Two laser systems were evaluated to compare their clinical results for the treatment of benign prostatic hyperplasia (BPH). Patients were treated using either the GreenLight HPS laser (n = 84) or the diode laser (n = 55) in a prospective randomized study. The data of International Prostate Symptom Score (IPSS), maximum flow rate (Q(max)), post-void residual urine (PVR), and quality of life score (Qols) were recorded at baseline, 1-, 6-, and 12-month follow-ups. The prostate volume and prostate-specific antigen (PSA) level were assessed at baseline and 6-month follow-up. All complications were also recorded. There was a statistically significant difference in IPSS, Q(max), PVR, and QoLs in each laser group at the 1-, 6-, and 12-month follow-ups compared with baseline. There was no statistical significant difference in any of these parameters at any follow-up interval between each group. The diode laser demonstrates superior hemostatic properties compared with the GreenLight HPS laser. Postoperative incontinence and postoperative irritative symptoms are more pronounced (P < 0.05) after diode laser prostatectomy. Higher incidence of dysuria with sloughing tissues and epididymitis (P < 0.05) is noted after diode laser prostatectomy. Other complications were comparable for both procedures. Although both lasers can improve subjective and objective parameters of BPH, both can produce undesired effects. The search for the ideal vaporization laser to treat BPH still continues. 2010 Wiley-Liss, Inc.

Blue, green, orange, and red upconversion laser

DOEpatents

Xie, P.; Gosnell, T.R.

1998-09-08

A laser is disclosed for outputting visible light at the wavelengths of blue, green, orange and red light. This is accomplished through the doping of a substrate, such as an optical fiber or waveguide, with Pr{sup 3+} ions and Yb{sup 3+} ions. A light pump such as a diode laser is used to excite these ions into energy states which will produce lasing at the desired wavelengths. Tuning elements such as prisms and gratings can be employed to select desired wavelengths for output. 11 figs.

Hole transport in c-plane InGaN-based green laser diodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Yang; Liu, Jianping, E-mail: jpliu2010@sinano.ac.cn; Tian, Aiqin

2016-08-29

Hole transport in c-plane InGaN-based green laser diodes (LDs) has been investigated by both simulations and experiments. It is found that holes can overflow from the green double quantum wells (DQWs) at high current density, which reduces carrier injection efficiency of c-plane InGaN-based green LDs. A heavily silicon-doped layer right below the green DQWs can effectively suppress hole overflow from the green DQWs.

80-W green KTP laser used in photoselective laser vaporization of the prostrate by frequency doubling of Yb 3+ -doped large-mode area fiber laser

NASA Astrophysics Data System (ADS)

Xia, Hongxing; Li, Zhengjia

2007-05-01

Photoselective laser vaporization of the prostate (PVP) is the most promising method for the treatment of benign prostatic hyperplasia (BPH), but KTP lasers used in PVP with lamp-pumped are low efficient .To increase the efficiency , we develop a 80-W, 400kHz, linearly polarized green laser based on a frequency-doubled fiber laser. A polarization-maintaining large-mode area (LMA) fiber amplifier generate polarized 1064nm fundamental wave by amplifying the seed signal from a composite Cr 4+:YAG-Nd 3+:YAG crystal fiber laser. The fundamental wave is injected into a KTP crystal with confined temperature management to achieve second harmonic generation (SHG). The overall electrical efficiency to the green portion of the spectrum is 10%.80-W maintenance-free long-lifetime KTP laser obtained can well satisfy the need of PVP.

Iodine-stabilized single-frequency green InGaN diode laser.

PubMed

Chen, Yi-Hsi; Lin, Wei-Chen; Shy, Jow-Tsong; Chui, Hsiang-Chen

2018-01-01

A 520-nm InGaN diode laser can emit a milliwatt-level, single-frequency laser beam when the applied current slightly exceeds the lasing threshold. The laser frequency was less sensitive to diode temperature and could be finely tuned by adjusting the applied current. Laser frequency was stabilized onto a hyperfine component in an iodine transition through the saturated absorption spectroscopy. The uncertainty of frequency stabilization was approximately 8×10 -9 at a 10-s integration time. This compact laser system can replace the conventional green diode-pumped solid-state laser and applied as a frequency reference. A single longitudinal mode operational region with diode temperature, current, and output power was investigated.

The effect of red, green and blue lasers on healing of oral wounds in diabetic rats.

PubMed

Fekrazad, Reza; Mirmoezzi, Amir; Kalhori, Katayoun Am; Arany, Praveen

2015-07-01

Many studies have demonstrated that low-level laser therapy (LLLT) can improve wound healing in non-diabetic and diabetic animals. We compared the effects of red, green, and blue lasers in terms of accelerating oral wound healing in diabetic rats. Diabetes was successfully induced in 32 male Wistar rats using intraperitoneal injection of Streptozotocin (150 mg/kg). After intraperitoneal injection of the anesthetic agent, a full-thickness oral wound (10 mm × 2 mm) was created aseptically with a scalpel on hard palate of the diabetic rats. The study was performed using red (630 nm), green (532 nm), and blue (425 nm) lasers and a control group. We used an energy density of 2J/cm2 and a treatment schedule of 3 times/week for 10 days. The area of wounds was measured and recorded on a chart for all rats. On the 10th day, the samples were then sacrificed and a full-thickness sample of wound area was prepared for pathological study. We observed a significant difference (p<0.001) in the mean slope values of wound healing between treatment and control groups. Moreover, the mean slope of wound healing differed significantly between red laser and two other lasers - blue and green (p<0.001). The mean slopes of wound healing were not significantly different between blue laser and green laser (p=0.777). The results of the present study provide evidence that wound healing is slower in control rats compared to the treatment groups. Moreover, the findings suggest that wound healing occurs faster with red laser compared to blue and green lasers. Copyright © 2015 Elsevier B.V. All rights reserved.

Indocyanine green-laser thermolysis of acne vulgaris

NASA Astrophysics Data System (ADS)

Genina, Elina A.; Bashkatov, Alexey N.; Simonenko, Georgy V.; Tuchin, Valery V.; Yaroslavsky, Ilya V.; Altshuler, Gregory B.

2005-08-01

The near-infrared (NIR) laser radiation due to its high penetration depth is widely used in phototherapy and photothermolysis. In application to skin appendages a high selectivity of laser treatment is needed to prevent light action on surrounding tissues. Indocyanine Green (ICG) dye may provide a high selectivity of treatment due to effective ICG uploading by a target and its narrow band of considerable absorption just at the wavelength of the NIR diode laser. The goal of this study is to demonstrate the efficacy of the NIR diode laser photothermolysis in combination with topical application of ICG suggested for treatment of acne vulgaris. Two volunteers with back-located acne were enrolled. Skin sites of subjects were stained by ICG and irradiated by NIR laser-diode light (803 or 809 nm). The individual acne lesions were photothermally treated at 18 W/cm2 (803 nm, 0.5 sec) without skin surface cooling or at 200 W/cm2 (809 nm, 0.5 sec) with cooling. The results of the observations during a month after the treatment have shown that ICG stained acne inflammatory elements were destructed for light exposures of 0.5 sec.

Gender Differences in Laser Acupuncture—Results of a Crossover Study with Green and Yellow Laser at the Ear Point Shenmen

PubMed Central

Litscher, Daniela; Wang, Junying; Li, Guangzong; Bosch, Peggy; Wang, Lu

2018-01-01

Background: One of the most commonly used auricular acupuncture points selected for different pain treatment regimens is Shenmen. This point on the ear has been recognized as having a wide number of applications, as found by scientific investigation. Methods: Within this crossover study, the ear acupoint Shenmen was stimulated with two different kinds of laser (green, 532 nm and yellow, 589 nm) in 22 healthy volunteers (13 female, 9 male; mean age ± SD = 25.3 ± 4.1 years; range 21–36 years). Both green and yellow lasers were used for 15 min in the same volunteers in two different sessions. Results: The most prominent finding was that systolic blood pressure decreased significantly (p = 0.048) after yellow laser stimulation. Heart rate also decreased significantly (p < 0.001), whereas heart rate variability ratio low frequency (LF)/high frequency (HF) (p < 0.001) increased. The effects were significantly more pronounced in females than in males. In addition, the temperature was measured, and temperature increases were demonstrated at different locations on the ear using imaging methods. Conclusions: This study shows evidence of the effect of auricular laser acupuncture. However, a comparison with other publications was impossible because this is the first study using green and yellow laser stimulation on the ear. PMID:29543742

Periodically poled self-frequency-doubling green laser fabricated from Nd:Mg:LiNbO₃ single crystal.

PubMed

Wang, Dong Zhou; Sun, De Hui; Kang, Xue Liang; Sang, Yuan Hua; Yan, Bo Xia; Liu, Hong; Bi, Yong

2015-07-13

Although a breakthrough in the fabrication of green laser diodes has occurred, the high costs associated with the difficulty of manufacture still present a great obstacle for its practical application. Another approach for producing a green laser, by combining a laser device and a nonlinear crystal, entails the fabrication of complex structures and exhibits unstable performance due to interface contact defects, thus limiting its application. In this work, we report the fabrication by domain engineering of high quality periodically poled LiNbO₃, co-doped with Nd³⁺ and Mg²⁺, which combines a laser medium and a high efficiency second harmonic conversion crystal into a single system that is designed to overcome the above problems. An 80 mW self-frequency doubling green laser was constructed for the first time from a periodically poled Nd:Mg:LiNbO₃ crystal of 16 mm in length. This crystal can be used for developing compact, stable, highly efficient mini-solid-state-lasers, which promise to have many applications in portable laser-based spectroscopy, photo-communications, terahertz wave generation, and laser displays.

Molecular Iodine Fluorescence Using a Green Helium-Neon Laser

ERIC Educational Resources Information Center

Williamson, J. Charles

2011-01-01

Excitation of molecular iodine vapor with a green (543.4 nm) helium-neon laser produces a fluorescence spectrum that is well suited for the upper-level undergraduate physical chemistry laboratory. Application of standard evaluation techniques to the spectrum yields ground electronic-state molecular parameters in good agreement with literature…

Green and Fast Laser Fusion Technique for Bulk Silicate Rock Analysis by Laser Ablation-Inductively Coupled Plasma Mass Spectrometry.

PubMed

Zhang, Chenxi; Hu, Zhaochu; Zhang, Wen; Liu, Yongsheng; Zong, Keqing; Li, Ming; Chen, Haihong; Hu, Shenghong

2016-10-18

Sample preparation of whole-rock powders is the major limitation for their accurate and precise elemental analysis by laser ablation inductively-coupled plasma mass spectrometry (ICPMS). In this study, a green, efficient, and simplified fusion technique using a high energy infrared laser was developed for major and trace elemental analysis. Fusion takes only tens of milliseconds for each sample. Compared to the pressed pellet sample preparation, the analytical precision of the developed laser fusion technique is higher by an order of magnitude for most elements in granodiorite GSP-2. Analytical results obtained for five USGS reference materials (ranging from mafic to intermediate to felsic) using the laser fusion technique generally agree with recommended values with discrepancies of less than 10% for most elements. However, high losses (20-70%) of highly volatile elements (Zn and Pb) and the transition metal Cu are observed. The achieved precision is within 5% for major elements and within 15% for most trace elements. Direct laser fusion of rock powders is a green and notably simple method to obtain homogeneous samples, which will significantly accelerate the application of laser ablation ICPMS for whole-rock sample analysis.

Green laser pointers for visual astronomy: how much power is enough?

PubMed

Bará, Salvador; Robles, Marisol; Tejelo, Isabel; Marzoa, Ramón I; González, Héctor

2010-02-01

Green laser pointers with output powers in the tens to hundreds of milliwatt (mW) range, clearly exceeding the limiting 5 mW of American National Standards Institute class 3a (International Electrotechnical Commission class 3R), are now easily available in the global market. They are increasingly being used in public sky observations and other nighttime outreach activities by educators and science communicators in countries where their use is not well regulated, despite the fact that such high power levels may represent a potential threat to visual health. The purpose of this study was to determine the output power reasonably required to perform satisfactorily this kind of activities. Twenty-three observers were asked to vary continuously the output power of a green laser source (wavelength 532 nm) until clearly seeing the laser beam propagating skyward through the atmosphere in a heavily light-polluted urban setting. Measurements were conducted with observers of a wide range of ages (9 to 56 years), refractions (spherical equivalents -8.50 to +1.50 diopters), and previous expertise in using lasers as pointing devices outdoors (from no experience to professional astronomers). Two measurement runs were made in different nights under different meteorological conditions. The output power chosen by observers in the first run (11 observers) averaged to 1.84 mW (+/-0.68 mW, 1 SD). The second run (17 observers) averaged to 2.91 mW (+/-1.54 mW). The global average was 2.38 mW (+/-1.30 mW). Only one observer scored 5.6 mW, just above the class 3a limit. The power chosen by the remaining 22 observers ranged from 1.37 to 3.53 mW. Green laser pointers with output powers below 5 mW (laser classes American National Standards Institute 3a or International Electrotechnical Commission 3R) appear to be sufficient for use in educational nighttime outdoors activities, providing enough bright beams at reasonable safety levels.

GreenLight laser vs diode laser vaporization of the prostate: 3-year results of a prospective nonrandomized study.

PubMed

Guo, Sanwei; Müller, Georg; Bonkat, Gernot; Püschel, Heike; Gasser, Thomas; Bachmann, Alexander; Rieken, Malte

2015-04-01

Laser vaporization of the prostate is one of the alternatives to transurethral resection of the prostate. Short-term studies report a comparable outcome after laser vaporization with the 532 nm 120-W GreenLight high-performance system (HPS) laser and the 980 nm 200 W high-intensity diode (diode) laser. In this study, we analyzed the intermediate-term results of both techniques. From January 2007 to January 2008, 112 consecutive patients with symptomatic benign prostate enlargement were nonrandomly assigned to treatment with the GreenLight laser or the diode laser. Perioperative parameters, postoperative functional outcome, complications, and the reoperation rate at 3 years were analyzed. Improvement of voiding symptoms (International Prostate Symptom Score, quality-of-life) and micturition parameters (maximum flow rate, postvoid residual volume) showed no significant difference between the HPS group and the diode group. A significantly higher reoperation rate was observed in the diode group in comparison to the HPS group (37.5% vs 8.9%, p=0.0003) due to obstructive necrotic tissue (16.1% vs 0%, p=0.0018), bladder neck stricture (16.1% vs 1.8%, p=0.008), and persisting or recurrent adenoma (5.4% vs 7.1%, p=0.70), respectively. Both lasers lead to comparable improvement of voiding parameters and micturition symptoms. Treatment with the 200 W diode laser led to a significantly higher reoperation rate, which might be attributed to a higher degree of coagulation necrosis. Thus, a careful clinical application of this diode laser type is warranted.

Photochemical gas lasers and hybrid (solid/gas) blue-green femtosecond systems

NASA Astrophysics Data System (ADS)

Mikheev, L. D.; Tcheremiskine, V. I.; Uteza, O. P.; Sentis, M. L.

2012-01-01

The review summarizes milestones and major breakthrough results obtained in the course of the development of a photochemical method applied to optical excitation of gas lasers on electronic molecular transitions by radiation from such unconventional pump sources as high-temperature electrical discharges and strong shock waves in gas. It also describes principles and techniques applied in hybrid (solid/gas) high-intensity laser systems emitting in the blue-green spectral region, and discusses wavelength scaling of laser-matter interaction by the example of laser wake-field acceleration (LWFA), high-order harmonic generation (HHG) and “water window” soft X-ray lasers. One of the most significant results of the photochemical method development consists in emerging broad bandwidth lasers (XeF(C-A), Xe2Cl, and Kr2F) operating in the blue-green spectral range, which have potential for amplification of ultra-short (down to 10 fs) optical pulses towards the Petawatt peak power level. The main goal of this review is to argue that the active media of these lasers may provide a basis for the development of fs systems generating super-intense ultrashort laser pulses in the visible spectral range. Some specific hybrid schemes, comprising solid state front-ends and photodissociation XeF(C-A) power boosting amplifiers, are described. They are now under development at the Lasers Plasmas and Photonic Processes (LP3) Laboratory (Marseille, France), the P.N. Lebedev Physical Institute (Moscow, Russia) and the Institute of High-Current Electronics (Tomsk, Russia) with the aim of conducting proof-of-principle experiments. Some consequences of the visible-wavelength laser field interaction with matter are also surveyed to demonstrate advantages of short driver wavelength in the considered examples. One of the most important consequences is the possibility of coherent soft X-ray generation within the “water window” spectral range with the use of short wavelength driver pulses to

Compact high-power red-green-blue laser light source generation from a single lithium tantalate with cascaded domain modulation.

PubMed

Xu, P; Zhao, L N; Lv, X J; Lu, J; Yuan, Y; Zhao, G; Zhu, S N

2009-06-08

1W quasi-white-light source has been generated from a single lithium tantalate with cascaded domain modulation. The quasi-white-light is combined by proper proportion of the red, green and blue laser light. The red and the blue result from a compact self-sum frequency optical parametric oscillation when pumped by a single green laser. The efficiency of quasi-white-light from the green pump reaches 27%. This compact design can be employed not only as a stable and powerful RGB light source but also an effective blue laser generator.

Phototoxic effect of conjugates of plasmon-resonance nanoparticles with indocyanine green dye on Staphylococcus aureus induced by IR laser radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tuchina, E S; Tuchin, Valerii V; Khlebtsov, B N

2011-04-30

The effect of IR laser radiation ({lambda} = 805 - 808 nm) on the bacteria of the strain Staphylococcus aureus 209 P, incubated in indocyanine green solutions, is studied, as well as that of colloid gold nanoshells, nanocages and their conjugates with indocyanine green. It is found that the S. aureus 209 P cells are equally subjected to the IR laser radiation ({lambda} = 805 nm) after preliminary sensitisation with indocyanine green and gold nanoparticles separately and with conjugates of nanoparticles and indocyanine green. The enhancement of photodynamic and photothermal effects by 5 % is observed after 30 min ofmore » laser illumination ({lambda} = 808 nm) of bacteria, treated with conjugates of indocyanine green and nanocages. (optical technologies in biophysics and medicine)« less

Sensitive detection of malachite green and crystal violet by nonlinear laser wave mixing and capillary electrophoresis.

PubMed

Maxwell, Eric J; Tong, William G

2016-05-01

An ultrasensitive label-free antibody-free detection method for malachite green and crystal violet is presented using nonlinear laser wave-mixing spectroscopy and capillary zone electrophoresis. Wave-mixing spectroscopy provides a sensitive absorption-based detection method for trace analytes. This is accomplished by forming dynamic gratings within a sample cell, which diffracts light to create a coherent laser-like signal beam with high optical efficiency and high signal-to-noise ratio. A cubic dependence on laser power and square dependence on analyte concentration make wave mixing sensitive enough to detect molecules in their native form without the use of fluorescent labels for signal enhancement. A 532 nm laser and a 635 nm laser were used for malachite green and crystal violet sample excitation. The use of two lasers of different wavelengths allows the method to simultaneously detect both analytes. Selectivity is obtained through the capillary zone electrophoresis separation, which results in characteristic migration times. Measurement in capillary zone electrophoresis resulted in a limit of detection of 6.9 × 10(-10)M (2.5 × 10(-19) mol) for crystal violet and 8.3 × 10(-11)M (3.0 × 10(-20) mol) for malachite green at S/N of 2. Copyright © 2016. Published by Elsevier B.V.

A CW green laser emission by self-sum-frequency-mixing in Nd:GdCOB crystal

NASA Astrophysics Data System (ADS)

Shao, Y.; Jin, H. J.; Lin, J.; Zhang, D.; Tao, Z. H.; Zhang, T. Y.; Li, Y. L.; Ruan, Q. R.

2011-10-01

A compact and efficient green laser light at 538 nm produced by self-sum-frequency-mixing of both fundamental infrared laser waves (1061 and 1091 nm) in Nd:GdCa4O(BO3)3 (Nd:GdCOB) crystal is demonstrated. With 18.2 W of diode pump power, a maximum output power of 1.73 W in the green spectral range at 538 nm has been achieved, corresponding to an optical-to-optical conversion efficiency of 9.5%; the output power stability over 30 min is better than 3%. To the best of our knowledge, this is first work on self-sum-frequency-mixing of a diode pumped Nd:GdCOB laser.

Laser ultrasonics for bulk-density distribution measurement on green ceramic tiles

NASA Astrophysics Data System (ADS)

Revel, G. M.; Cavuto, A.; Pandarese, G.

2016-10-01

In this paper a Laser Ultrasonics (LUT) system is developed and applied to measure bulk density distribution of green ceramic tiles, which are porous materials with low heat conductivity. Bulk density of green ceramic bodies is a fundamental parameter to be kept under control in the industrial production of ceramic tiles. The LUT system proposed is based on a Nd:YAG pulsed laser for excitation and an air-coupled electro-capacitive transducer for detection. The paper reports experimental apparent bulk-density measurements on white ceramic bodies after a calibration procedures. The performances observed are better than those previously achieved by authors using air-coupled ultrasonic probes for both emission and detection, allowing to reduce average uncertainty down to about ±6 kg/m3 (±0.3%), thanks to the increase in excitation efficiency and lateral resolution, while maintaining potential flexibility for on-line application. The laser ultrasonic procedure proposed is available for both on-line and off-line application. In this last case it is possible to obtain bulk density maps with high spatial resolution by a 2D scan without interrupting the production process.

High-power CW and long-pulse lasers in the green wavelength regime for copper welding

NASA Astrophysics Data System (ADS)

Pricking, Sebastian; Huber, Rudolf; Klausmann, Konrad; Kaiser, Elke; Stolzenburg, Christian; Killi, Alexander

2016-03-01

We report on industrial high-power lasers in the green wavelength regime. By means of a thin disk oscillator and a resonator-internal nonlinear crystal for second harmonic generation we are able to extract up to 8 kW pulse power in the few-millisecond range at a wavelength of 515 nm with a duty cycle of 10%. Careful shaping and stabilization of the polarization and spectral properties leads to a high optical-to-optical efficiency larger than 55%. The beam parameter product is designed and measured to be below 5 mm·mrad which allows the transport by a fiber with a 100 μm core diameter. The fiber and beam guidance optics are adapted to the green wavelength, enabling low transmission losses and stable operation. Application tests show that this laser is perfectly suited for copper welding due to the superior absorption of the green wavelength compared to IR, which allows us to produce weld spots with an unprecedented reproducibility in diameter and welding depth. With an optimized set of parameters we could achieve a splatter-free welding process of copper, which is crucial for welding electronic components. Furthermore, the surface condition does not influence the welding process when the green wavelength is used, which allows to skip any expensive preprocessing steps like tin-coating. With minor changes we could operate the laser in cw mode and achieved up to 1.7 kW of cw power at 515 nm with a beam parameter product of 2.5 mm·mrad. These parameters make the laser perfectly suitable for additional applications such as selective laser melting of copper.

A comparison of free autologous breast reconstruction with and without the use of laser-assisted indocyanine green angiography: a cost-effectiveness analysis.

PubMed

Chatterjee, Abhishek; Krishnan, Naveen M; Van Vliet, Michael M; Powell, Stephen G; Rosen, Joseph M; Ridgway, Emily B

2013-05-01

Laser-assisted indocyanine green angiography is a U.S. Food and Drug Administration-approved technology used to assess tissue viability and perfusion. Its use in plastic and reconstructive surgery to assess flap perfusion in autologous breast reconstruction is relatively new. There have been no previous studies evaluating the cost-effectiveness of this new technology compared with the current practice of clinical judgment in evaluating tissue perfusion and viability in free autologous breast reconstruction in patients who have undergone mastectomy. A comprehensive literature review was performed to identify the complication rate of the most common complications with and without laser-assisted indocyanine green angiography in free autologous breast reconstruction after mastectomy. These probabilities were combined with Medicare Current Procedural Terminology provider reimbursement codes (cost) and utility estimates for common complications from a survey of 10 plastic surgeons to fit into a decision model to evaluate the cost-effectiveness of laser-assisted indocyanine green angiography. The decision model revealed a baseline cost difference of $773.66 and a 0.22 difference in the quality-adjusted life-years, yielding an incremental cost-utility ratio of $3516.64 per quality-adjusted life year favoring laser-assisted indocyanine green angiography. Sensitivity analysis showed that using laser-assisted indocyanine green angiography was more cost-effective when the complication rate without using laser-assisted indocyanine green angiography (clinical judgment alone) was 4 percent or higher. The authors' study demonstrates that laser-assisted indocyanine green angiography is a cost-effective technology under the most stringent acceptable thresholds when used in immediate free autologous breast reconstruction.

High energy, high average power solid state green or UV laser

DOEpatents

Hackel, Lloyd A.; Norton, Mary; Dane, C. Brent

2004-03-02

A system for producing a green or UV output beam for illuminating a large area with relatively high beam fluence. A Nd:glass laser produces a near-infrared output by means of an oscillator that generates a high quality but low power output and then multi-pass through and amplification in a zig-zag slab amplifier and wavefront correction in a phase conjugator at the midway point of the multi-pass amplification. The green or UV output is generated by means of conversion crystals that follow final propagation through the zig-zag slab amplifier.

Recognition of spectral identifier from green coffee beans of arabica and robusta varieties using laser-induced breakdown spectroscopy

NASA Astrophysics Data System (ADS)

Anggraeni, Karina; Nasution, Aulia; Suyanto, Hery

2016-11-01

Coffee is one of the world's commodity that is cultivated in more than 50 countries. Production of coffee in Indonesia is positioned of fourth rank in the world, after Brazil, Vietnam, and Colombia. There are two varieties of coffee grown in Indonesia, i.e. the arabica and robusta. The chemical compositions between arabica and robusta are different each other. A trained coffee tester can distinguish these differences from its taste, but it is very subjective. Laser-Induced Breakdown Spectroscopy (LIBS) is a spectroscopic technique based on the analysis of micro-plasma induced on the surface sample after being shot with a laser pulse. In this study, elemental spectra acquired using Laser-Induced Breakdown Spectroscopy (LIBS) technique were analysed to differentate between green coffee beans of arabica and robusta, which are collected from plantations in Malang, Bondowoso, Prigen, and Pasuruan. Results show that optimum conditions for acquiring spectra from green coffee beans using LIBS are at 120 mJ of laser energy and 1,0 μs of delay time. Green coffee beans of arabica and robusta contain some elements such as Ca, W, Sr, Mg, Be, Na, H, N, K, Rb, and O. Discriminant analysis method was then applied to distinguish the green beans of arabica and robusta coffee. Element identifiers of green coffee beans are Ca, W, Mg, Be, Na, and Sr. The abundant element in green coffee beans is Calcium (Ca), and depth-profile testing shows that Ca is homogeneous inside the beans.

Diode-pumped solid state green laser for ophthalmologic application

NASA Astrophysics Data System (ADS)

Eno, Taizo; Goto, Yoshiaki; Momiuchi, Masayuki

2002-10-01

We have developed diode pumped solid state green laser suitable for ophthalmologic applications. Beam parameters were designed by considering the coagulation system. We have lowered the beam quality to multi transverse and longitudinal mode on purpose to improve the speckle noise of the slit lamp output beam. The beam profile shows homogeneous intensity and it is very useful for ophthalmologic application. End pumping and short cavity configuration made it possible.

Laser-assisted indocyanine green angiography: a critical appraisal.

PubMed

Wu, Cindy; Kim, Sendia; Halvorson, Eric G

2013-05-01

Laser-assisted indocyanine green angiography (ICG-A) has been promoted to assess perfusion of random skin, pedicled, and free flaps. Few studies address its potential limitations. Thirty-seven patients who underwent reconstructive procedures with ICG-A were studied retrospectively to determine the correlation between clinical findings and ICG-A. Indocyanine green angiography underestimated perfusion when areas of less than or equal to 25% uptake were not debrided and remained perfused. Indocyanine green angiography overestimated perfusion when areas with greater than 25% uptake developed necrosis. Of 14 random skin flaps, ICG-A underestimated perfusion in 14% and overestimated in 14%. In 16 patients undergoing perforator flap breast reconstruction, ICG-A correlated with computed tomographic angiogram (CTA) in 85%. Indocyanine green angiography underestimated perfusion in 7% and overestimated in 7%. In 8/11 patients undergoing fasciocutaneous flaps, ICG-A aided in donor site selection. In 3/6 ALT flaps, a better unilateral blush was found that correlated with Doppler. In all 3, a dominant perforator was found. In 11 patients, there was a 9% underestimation of flap perfusion. In 3 pedicled flaps, there was a 66% underestimation and 33% overestimation of perfusion. Indocyanine green angiography often confirmed our clinical/radiologic findings in abdominal perforator and fasciocutaneous flaps. It tended to underestimate perfusion in pedicle and skin flaps. When clinical examination was obvious, ICG-A rendered clear-cut findings. When clinical examination was equivocal, ICG-A tended to provide ambiguous findings, demonstrating that a distinct cutoff point does not exists for every patient or flap. Indocyanine green angiography is a promising but expensive technology that would benefit from standardization. Further research is needed before ICG-A can become a reliable tool for surgeons.

LASER BIOLOGY: Visualisation of the distributions of melanin and indocyanine green in biological tissues

NASA Astrophysics Data System (ADS)

Genina, E. A.; Fedosov, I. V.; Bashkatov, A. N.; Zimnyakov, D. A.; Altshuler, G. B.; Tuchin, V. V.

2008-03-01

A double-wavelength laser scanning microphotometer with the high spectral and spatial resolutions is developed for studying the distribution of endogenic and exogenic dyes in biological tissues. Samples of hair and skin biopsy with hair follicles stained with indocyanine green are studied. The spatial distribution of indocyanine green and melanin in the biological tissue is determined from the measured optical transmittance.

Diode pumped Yb:CN laser at 1082 nm and intracavity doubling to the green spectral range

NASA Astrophysics Data System (ADS)

Liu, B.; Li, Y. L.; Jiang, H. L.

2011-08-01

A diode pumped Yb:CaNb2O6 (Yb:CN) laser at 1082 nm with a maximum output of 1.35 W at 13.3 W pump power has been demonstrated. The slope efficiency was 12.4%. Moreover, intracavity second-harmonic generation (SHG) has also been achieved with a maximum green power of 374 mW by using a LiB3O5 (LBO) nonlinear crystal. To the best of our knowledge, this is the first report on continuous wave (CW) green generation by intracavity frequency doubling Yb:CN laser.

Optimization of diode-pumped doubly QML laser with neodymium-doped vanadate crystals at 1.34 μm

NASA Astrophysics Data System (ADS)

Zhang, Gang; Jiao, Zhiyong

2018-05-01

We present a theoretical model for a diode-pumped, 1.34 μm V3+:YAG laser that is equipped with an acoustic-optic modulator. The model includes the loss introduced by the acoustic-optic modulator combined with the physical properties of the laser resonator, the neodymium-doped vanadate crystals and the output coupler. The parameters are adjusted within a reasonable range to optimize the pulse output characteristics. A typical Q-switched and mode-locked Nd:Lu0.15Y0.85VO4 laser at 1.34 μm with acoustic-optic modulator and V3+:YAG is set up, and the experimental output characteristics are consistent with the theoretical simulation results.

Usage of GreenLight HPS 180-W laser vaporisation for treatment of benign prostatic hyperplasia.

PubMed

Jovanović, M; Džamić, Z; Aćimović, M; Kajmaković, B; Pejčić, T

2014-01-01

Laser therapy has gained increasing acceptance as a relatively less invasive treatment for lower urinary tract symptoms (LUTS) due to benign prostatic hyperplasia (BPH). From the early procedure of interstitial laser coagulation through to the use of holmium laser enucleation of the prostate, there has been an expanding body of evidence on the efficacy of such procedures. One of the newer lasers is the Green Light HPS 180 W laser. Studies with this GreenLight laser (GLL) (American Medical Systems, Inc, Minnetonka, MN, USA) showing results as good as those of transurethral resection of the prostate (TURP). In this paper, the efficacy of the new GLL 180-W versus the gold standard TURP in patients with LUTS due to BPH was tested in a prospective clinical trial. To compare results of Green light laser (GLL) evaporisation of the prostatae and transurethral resection of the prostate (TURP) for treatment of BPH. MATERIJALS AND METHODS: A total of 62 patients with BPH were randomly assigned to two equal groups: TURP or GLL. Both groups were compared regarding all relevant preoperative, operative, and postoperative parameters. Functional results in terms of improvement of International Prostate Symptom Score (IPSS), maximum flow rate (Qmax), and postvoid residual (PVR) urine were assessed at 1, 3, 6 and 12 mo. A total of 62 patients completed 12 mo of follow-up in the TURP and GLL groups, respectively. Baseline characteristics were comparable. Mean operative time was significantly shorter for TURP. Compared to preoperative values, there was significant reduction in hemoglobin levels at the end of TURP only. A significant difference in favor of GLL was achieved regarding the duration of catheterization and hospital stay. In the GLL, no major intraoperative complications were recorded and none of the patients required blood transfusion. Among TURP patients, 6 required transfusion, 1 developed TUR syndrome, and capsule perforation was observed in 5 patients. There was dramatic

Frequency-doubled green picosecond laser based on K3B6O10Br nonlinear optical crystal

NASA Astrophysics Data System (ADS)

Meng, Luping; Zhang, Ling; Hou, Zhanyu; Wang, Lirong; Xu, Hui; Shi, Meng; Wang, Lingwu; Yang, Yingying; Qi, Yaoyao; He, Chaojian; Yu, Haijuan; Lin, Xuechun; Su, Fufang; Xia, Mingjun; Li, Rukang

2018-05-01

We report a frequency-doubled green picosecond (ps) laser based on K3B6O10Br (KBB) nonlinear optical crystal with cutting angle of θ = 34.7° and φ = 30°. Through intracavity frequency doubling using a type I phase-matched KBB crystal with dimensions of 4 mm × 4 mm × 13.2 mm, the average output power of 185.00 mW green ps laser was obtained with a repetition rate of 80 MHz and pulse width of 25.0 ps. In addition, we present external frequency doubling using KBB crystal. The average output power of 3.00 W green ps laser was generated with a repetition rate of 10 kHz and pulse width of 38.1 ps, which corresponds to a pulse energy of 0.30 mJ and a peak power 7.89 MW, respectively. The experimental results show that KBB crystal is a promising nonlinear optical material.

Experimental Results for Temporally Overlapping Pulses from Quantel EverGreen 200 Laser

NASA Technical Reports Server (NTRS)

Watkins, A. Neal

2013-01-01

This report will detail the experimental results and observations obtained while investigating the feasibility of temporally overlapping the two laser pulses from a Quantel EverGreen 200 Laser. This laser was specifically designed for Particle Imaging Velocimetry (PIV) applications and operate by emitting two 532 nm laser pulses that are seperated by an adjustable finite time (typically on the order of ten to hundreds of microseconds). However, the use of this model laser has found recent application for Pressure Sensitive Paint (PSP) testing, especially for rotorcraft research. For this testing, it is desired to only use one laser pulse. While this is easily done by only firing one of the laser heads, more excitation energy could conceivably be had if both laser heads are fired with zero pulse separation. In addition, recently large field-of-view PIV measurements have become possible and need ever increasing laser power to illuminate the larger areas. For this work, two different methods of timing the laser are investigated using both a traditional power meter to monitor laser power as well as a fast photodiode to determine pulse separation. The results are presented here as well as some simple implications for PIV experiments using these methods.

Does age affect the efficacy and safety of GreenLight HPS™ laser photoselective vaporization prostatectomy?

PubMed

Gu, Xiao; Strom, Kurt; Spaliviero, Massimiliano; Wong, Carson

2012-03-01

To evaluate the efficacy and safety of GreenLight HPS(™) (High Performance System) laser photoselective vaporization prostatectomy (PVP) for the treatment of benign prostatic hyperplasia (BPH) in patients of different age groups. 164 consecutive patients were stratified into two groups: age <70 (group I, n = 93) and age ≥70 (group II, n = 71) years. Transurethral PVP was performed using a GreenLight HPS™ side-firing laser system. Voiding parameters were measured preoperatively and at 1 and 4 weeks and 3, 6, 12, 18, 24 and 36 months postoperatively. Among the preoperative parameters evaluated, there were significant differences (p < 0.05) in prostate volume (I: 58.7; II: 73.6 mL) and serum prostate-specific antigen (I: 1.9; II: 2.9 ng/mL), while American Urological Association Symptom Score (AUASS), Quality of Life (QoL), maximum flow rate (Qmax), Sexual Health Inventory for Men (SHIM) and post void residual (PVR) were similar (p > 0.05) between groups. No significant differences in laser utilization, energy usage and operating time were noted. Clinical outcomes (AUASS, QoL, Qmax, PVR) showed immediate and stable improvement from baseline (p < 0.05) within each group, but no significant differences between the two groups were observed during the follow-up period. The incidence of adverse events was low and similar in both groups. The results suggest that age has little effect on the efficacy and safety of GreenLight HPS™ laser PVP.

Stimulation of the cochlea using green laser light

NASA Astrophysics Data System (ADS)

Wenzel, G. I.; Balster, S.; Lim, H. H.; Zhang, K.; Reich, U.; Lubatschowski, H.; Ertmer, W.; Lenarz, T.; Reuter, G.

2009-02-01

The success of conventional hearing aids and electrical cochlear implants have generally been limited to hearing in quiet situations, in part due to a lack of localized (i.e., frequency specificity) sensorineural activation and subsequent impaired speech discrimination in noise. Laser light is a source of energy that can be focused in a controlled manner and may provide more localized activation of the inner ear, the cochlea. Compound action potentials have been elicited using 2.12 µm laser pulses through activation of auditory nerve fibers (Izzo et al. 2006). Laser stimulation (813 nm) of the cochlea has shown to induce basilar membrane motion and cochlear microphonic potentials (Fridberger et al. 2006). We sought to assess if visible light (green, 532 nm, 10 ns pulses) could be used to consistently activate the cochlea. The laser parameters were selected based on our initial attempt to induce an optoacoustic effect as the energy transfer mechanism to the cochlea. Click evoked auditory brainstem responses (AABRs) were recorded preoperatively in ketamine-anesthetized guinea pigs to confirm normal hearing. The bulla and then the cochlea were exposed. Optically evoked ABRs (OABR) were recorded in response to laser stimulation with a 50 µm optical fiber (532 nm, 10 ns pulses, 500 repetitions, 10 pulses/s; Nd:YAG laser) at the round window (RW) directed towards the basilar membrane (BM). OABRs similar in morphology to acoustically evoked ABRs, except for shorter latencies, were obtained for stimulation through the RW with energy levels between 1.7-30 µJ/pulse. The OABRs increased with increasing energy level reaching a saturation level around 13-15 µJ/pulse. Furthermore the responses remained consistent across stimulation over time, including stimulation at 13 µJ/pulse for over 30 minutes, indicating minimal or no damage within the cochlea with this type of laser stimulation. Overall we have demonstrated that laser light stimulation with 532 nm has

Broadband integrated mid infrared light sources as enabling technology for point of care mid-infrared spectroscopy

DTIC Science & Technology

2017-08-20

liquid crystal cell was successfully employed as an active q-switching element in the same type of chip lasers. The short laser pulses that were...switched mode-locked (QML) operation of those chip lasers. Further, a novel nematic liquid crystal cell was successfully employed as an active q... gas spectroscopy and environmental monitoring, areas that hold immense significance and importance. However, laser source development at these

Continuous-wave Nd:YVO4/KTiOPO4 green laser at 542 nm under diode pumping into the emitting level

NASA Astrophysics Data System (ADS)

Liu, J. H.

2012-10-01

We report a green laser at 542 nm generation by intracavity frequency doubling of a continuous wave (CW) laser operation of a 1086 nm Nd:YVO4 laser under 880 nm diode pumping into the emitting level 4 F 3/2. A KTiOPO4 (KTP) crystal, cut for critical type I phase matching at room temperature is used for second harmonic generation of the laser. At an incident pump power of 14.5 W, as high as 1.33 W of CW output power at 542 nm is achieved. The optical-to-optical conversion efficiency is up to 9.2%, and the fluctuation of the green output power was better than 3.8% in the given 30 min.

Study of the blue-green laser scattering from the rough sea surface with foams by the improved two-scale method

NASA Astrophysics Data System (ADS)

Li, Xiangzhen; Qi, Xiao; Han, Xiang'e.

2015-10-01

The characteristics of laser scattering from sea surface have a great influence on application performance, from submarine communication, laser detection to laser diffusion communication. Foams will appear when the wind speed exceeds a certain value, so the foam can be seen everywhere in the upper layer of the ocean. Aiming at the volume-surface composite model of rough sea surface with foam layer driven by wind, and the similarities and differences of scattering characteristics between blue-green laser and microwave, an improved two-scale method for blue-green laser to calculate the scattering coefficient is presented in this paper. Based on the improved two-scale rough surface scattering theory, MIE theory and VRT( vector radiative transfer ) theory, the relations between the foam coverage of the sea surface and wind speed and air-sea temperature difference are analyzed. Aiming at the Gauss sea surface in blue-green laser, the dependence of back- and bistatie-scattering coefficient on the incident and azimuth angle, the coverage of foams, as well as the wind speed are discussed in detail. The results of numerical simulations are compared and analyzed in this paper. It can be concluded that the foam layer has a considerable effect on the laser scattering with the increase of wind speed, especially for a large incident angle. Theoretical analysis and numerical simulations show that the improved two-scale method is reasonable and efficient.

A Novel Approach for the Treatment of Radiation-Induced Hemorrhagic Cystitis with the GreenLight™ XPS Laser

PubMed Central

Martinez, Daniel Roberto; Ercole, Cesar E; Lopez, Juan Gabriel; Parker, Justin; Hall, Mary K

2015-01-01

ABSTRACT Introduction: The treatment of pelvic malignancies with radiotherapy can develop severe sequelae, especially radiation-induced hemorrhagic cystitis. It is a progressive disease that can lead to the need for blood transfusion, hospitalizations, and surgical interventions. This tends to affect the quality of life of these patients, and management can at times be difficult. We have evaluated the GreenLight Xcelerated Performance System (XPS) with TruCoag, although primarily used for management of benign prostatic hypertrophy (BPH), for the treatment of radiation-induced hemorrhagic cystitis. Materials and Methods: After International Review Board (IRB) approval, a retrospective chart review was performed in addition to a literature search. A series of four male patients, mean age of 81 years, with radiation-induced hemorrhagic cystitis secondary to radiotherapy for pelvic malignancies (3 prostate cancer, 1 rectal cancer) were successfully treated with the GreenLight laser after unsuccessful treatment with current therapies described in the literature. Results: All four patients treated with the GreenLight laser had resolution of their hematuria after one treatment and were discharge from the hospital with clear urine. Conclusion: The GreenLight XPS laser shows promising results for the treatment of patients with radiation-induced hemorrhagic cystitis, and deserves further evaluation and validation, especially since there is limited data available in the literature regarding the use of this technology for the treatment of this devastating condition. PMID:26200555

The mechanism of tissue welding using a green laser: revisited

NASA Astrophysics Data System (ADS)

Richter, C.-P.; Bellam, R.; Hezarkhani, E.; Fiebig, T.

2017-02-01

A "green" laser (e.g. Nd:YAG, λ = 532 nm) together with the red dye Rose Bengal (RB) have been used for photochemical tissue bonding (PTB). It has been reported that irradiation of RB with light at 532 nm produces free radicals. For tissue bonding with a Nd:YAG laser it has been proposed that the free radicals than crosslink the tissue collagen and lead to the closing of the surgical incisions. RB is also a red solution and it is possible that RB absorbs the photons delivered from the laser and converts them into heat with a measurable local temperature increase. It is possible that the mechanism for PTB is not only caused by free radical formation but also by a temperature increase in the tissue. In the present study we measured the local tissue temperature with a micro thermometer during irradiation with a Nd:YAG laser before and after RB was applied. For the present laser settings "tissue painting" with RB lead to a temperature increase resulting in tissue coagulation and charring. PTB was also studied for RB with a free radical scavenger, vitamin C. No significant difference in bonding strength was found for RB alone and for RB together with a free radical scavenger. In case no RB was applied no tissue bonding occurred. Bonding strength was quantified using the leakage seal test

Green-diode-pumped femtosecond Ti:Sapphire laser with up to 450 mW average power.

PubMed

Gürel, K; Wittwer, V J; Hoffmann, M; Saraceno, C J; Hakobyan, S; Resan, B; Rohrbacher, A; Weingarten, K; Schilt, S; Südmeyer, T

2015-11-16

We investigate power-scaling of green-diode-pumped Ti:Sapphire lasers in continuous-wave (CW) and mode-locked operation. In a first configuration with a total pump power of up to 2 W incident onto the crystal, we achieved a CW power of up to 440 mW and self-starting mode-locking with up to 200 mW average power in 68-fs pulses using semiconductor saturable absorber mirror (SESAM) as saturable absorber. In a second configuration with up to 3 W of pump power incident onto the crystal, we achieved up to 650 mW in CW operation and up to 450 mW in 58-fs pulses using Kerr-lens mode-locking (KLM). The shortest pulse duration was 39 fs, which was achieved at 350 mW average power using KLM. The mode-locked laser generates a pulse train at repetition rates around 400 MHz. No complex cooling system is required: neither the SESAM nor the Ti:Sapphire crystal is actively cooled, only air cooling is applied to the pump diodes using a small fan. Because of mass production for laser displays, we expect that prices for green laser diodes will become very favorable in the near future, opening the door for low-cost Ti:Sapphire lasers. This will be highly attractive for potential mass applications such as biomedical imaging and sensing.

Single-Spot Yellow Laser Versus Conventional Green Laser on Panretinal Photocoagulation: Patient Pain Scores and Preferences.

PubMed

González-Saldivar, Gerardo; Rojas-Juárez, Sergio; Espinosa-Soto, Itzel; Sánchez-Ramos, Jorge; Jaurieta-Hinojosa, Noel; Ramírez-Estudillo, Abel

2017-11-01

Panretinal photocoagulation (PRP) is the mainstay therapy for proliferative diabetic retinopathy. Pain during and after its application is a complication that affects patients' therapeutic adherence. This study aimed to compare pain perception and patient preference for the 577-nm yellow laser (YL-577) (LIGHTL as 577; LIGHTMED, San Clemente, CA) and the conventional 532-nm green laser (GL-532) (Purepoint Laser; Alcon, Fort Worth, TX) with PRP. A total of 92 patient eyes with proliferative diabetic retinopathy treated with PRP were randomly assigned to receive both GL-532 and YL-577 (184 eyes) - one on each eye, with the order of application randomized, as well. Afterward, verbal rapid answer and visual analogue scale (VAS) scores for pain perception and patient preference were evaluated. VAS score was 7 ± 2 for the GL-532 group compared to 5 ± 3 in the YL-577 group (P = .001). Overall, 75% of the patients preferred YL-577 therapy if they were to receive a second PRP session. The use of YL-577 as an alternative approach for PRP reduces pain perception and is preferred by patients. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:902-905.]. Copyright 2017, SLACK Incorporated.

Luminescent properties of Tb3+- doped TeO2-WO3-GeO2 glasses for green laser applications

NASA Astrophysics Data System (ADS)

Subrahmanyam, T.; Rama Gopal, K.; Padma Suvarna, R.; Jamalaiah, B. C.; Vijaya Kumar, M. V.

2018-06-01

Different concentrations of Tb3+ -doped oxyfluoro tellurite (TWGTb) glasses were prepared by conventional melt quenching technique and characterized for green laser applications. The Judd-Ofelt theory was applied to evaluate various spectroscopic and radiative parameters. The TWGTb glasses exhibit 5D3 → 7F5-3 and 5D4 → 7F6-0 transitions when excited at 316 nm radiation. The variation of intensity of 5D4 → 7F5 (Green) and 5D3 → 7F4 (Blue) transitions and the green to blue (IG/IB) intensity ratios were studied as a function of Tb3+ ions concentration. The laser characteristic parameters such as effective bandwidth (Δλeff), stimulated emission cross-section (σe), gain bandwidth (σe × Δλeff) and optical gain (σe × τR) were determined using the three phenomenological Judd-Ofelt intensity parameters. The fluorescence decay profiles of 5D4 metastable level exhibit single-exponential nature for all the samples. Based on the experimental results we suggest that the 1.0 mol% of Tb3+ -doped TWGTb glass could be a suitable laser host material to emit intense green luminescence at 545 nm.

A high-finesse Fabry-Perot cavity with a frequency-doubled green laser for precision Compton polarimetry at Jefferson Lab

DOE PAGES

Rakhman, A.; Hafez, Mohamed A.; Nanda, Sirish K.; ...

2016-03-31

Here, a high-finesse Fabry-Perot cavity with a frequency-doubled continuous wave green laser (532 nm) has been built and installed in Hall A of Jefferson Lab for high precision Compton polarimetry. The infrared (1064 nm) beam from a ytterbium-doped fiber amplifier seeded by a Nd:YAG nonplanar ring oscillator laser is frequency doubled in a single-pass periodically poled MgO:LiNbO 3 crystal. The maximum achieved green power at 5 W infrared pump power is 1.74 W with a total conversion efficiency of 34.8%. The green beam is injected into the optical resonant cavity and enhanced up to 3.7 kW with a corresponding enhancementmore » of 3800. The polarization transfer function has been measured in order to determine the intra-cavity circular laser polarization within a measurement uncertainty of 0.7%. The PREx experiment at Jefferson Lab used this system for the first time and achieved 1.0% precision in polarization measurements of an electron beam with energy and current of 1.0 GeV and 50 μA.« less

Tracheal anastomosis using indocyanine green dye enhanced fibrinogen with a near-infrared diode laser

NASA Astrophysics Data System (ADS)

Auteri, Joseph S.; Jeevanandam, Valluvan; Oz, Mehmet C.; Libutti, Steven K.; Kirby, Thomas J.; Smith, Craig R.; Treat, Michael R.

1990-06-01

A major obstacle to lung transplantation and combined heart- lung transplantation is dehiscence of the tracheobronchial anastomosis. We explored the possibility of laser welded anastomoses in canine tracheas in vivo. Laser anastomoses were performed on three-quarter circumferential anterior tracheotomies. A continous wave diode laser (808 +1 nm) at a power density of 9.6 watts/cm was used. Human fibrinogen was mixed with indocyanine green dye (ICG, max absorbance 805 nm) and applied to the anastomosis site prior to laser exposure. Animals were sacrificed at 0, 21 and 28 days post-operatively. At sacrifice weld bursting pressures were measured by raising intratracheal pressure using forced ventilation via an endotracheal tube. Sutured and laser welded anastomoses had similar bursting pressures, and exhibited satisfactory histologic evidence of healing. However, compared to polypropylene sutured controls, the laser welded anastomoses exhibited less peritracheal inflammatory reaction and showed visibly smoother luminal surfaces at 21 and 28 days post- operatively. Tracheal anastomosis using ICG dye enhanced fibrinogen combined with the near-infrared diode laser is a promising extension of the technology of laser tissue fusion and deserves further study.

Learning Qualitative Differential Equation models: a survey of algorithms and applications.

PubMed

Pang, Wei; Coghill, George M

2010-03-01

Over the last two decades, qualitative reasoning (QR) has become an important domain in Artificial Intelligence. QDE (Qualitative Differential Equation) model learning (QML), as a branch of QR, has also received an increasing amount of attention; many systems have been proposed to solve various significant problems in this field. QML has been applied to a wide range of fields, including physics, biology and medical science. In this paper, we first identify the scope of this review by distinguishing QML from other QML systems, and then review all the noteworthy QML systems within this scope. The applications of QML in several application domains are also introduced briefly. Finally, the future directions of QML are explored from different perspectives.

Learning Qualitative Differential Equation models: a survey of algorithms and applications

PubMed Central

PANG, WEI; COGHILL, GEORGE M.

2013-01-01

Over the last two decades, qualitative reasoning (QR) has become an important domain in Artificial Intelligence. QDE (Qualitative Differential Equation) model learning (QML), as a branch of QR, has also received an increasing amount of attention; many systems have been proposed to solve various significant problems in this field. QML has been applied to a wide range of fields, including physics, biology and medical science. In this paper, we first identify the scope of this review by distinguishing QML from other QML systems, and then review all the noteworthy QML systems within this scope. The applications of QML in several application domains are also introduced briefly. Finally, the future directions of QML are explored from different perspectives. PMID:23704803

Blue-green diode-pumped solid state laser system for transcutaneous bilirubinometry in neonatal jaundice

NASA Astrophysics Data System (ADS)

Hamza, Mostafa; El-Ahl, Mohammad H. S.; Hamza, Ahmad M.

2001-01-01

The authors introduce the design of a blue-green diode- pumped solid-state laser system for transcutaneous measurement of serum bilirubin level in jaundiced new born infant. The system follows the principles of optical bilirubinometry. The choice of wavelengths provides correction for the presence of hemoglobin. The new design is more compact and less expensive.

Generation of 3.5 W of diffraction-limited green light from SHG of a single tapered diode laser in a cascade of nonlinear crystals

NASA Astrophysics Data System (ADS)

Hansen, Anders K.; Jensen, Ole B.; Sumpf, Bernd; Erbert, Götz; Unterhuber, Angelika; Drexler, Wolfgang; Andersen, Peter E.; Petersen, Paul Michael

2014-02-01

Many applications, e.g., within biomedicine stand to benefit greatly from the development of diode laser-based multi- Watt efficient compact green laser sources. The low power of existing diode lasers in the green area (about 100 mW) means that the most promising approach remains nonlinear frequency conversion of infrared tapered diode lasers. Here, we describe the generation of 3.5 W of diffraction-limited green light from SHG of a single tapered diode laser, itself yielding 10 W at 1063 nm. This SHG is performed in single pass through a cascade of two PPMgO:LN crystals with re-focusing and dispersion compensating optics between the two nonlinear crystals. In the low-power limit, such a cascade of two crystals has the theoretical potential for generation of four times as much power as a single crystal without adding significantly to the complexity of the system. The experimentally achieved power of 3.5 W corresponds to a power enhancement greater than 2 compared to SHG in each of the crystals individually and is the highest visible output power generated by frequency conversion of a single diode laser. Such laser sources provide the necessary pump power for biophotonics applications, such as optical coherence tomography or multimodal imaging devices, e.g., FTCARS-OCT, based on a strongly pumped ultrafast Ti:Sapphire laser.

Nonequilibrium Green's functions theory for the alpha factor of quantum cascade lasers (Conference Presentation)

NASA Astrophysics Data System (ADS)

Pereira, Mauro F.; Winge, David O.; Wacker, Andreas; Jumpertz, Louise; Michel, Florian; Pawlus, Robert; Elsaesser, Wolfgang E.; Schires, Kevin; Carras, Mathieu; Grillot, Frédéric

2016-10-01

The linewidth of a conventional laser is due to fluctuations in the laser field due to spontaneous emission and described by the Schalow-Townes formula. In addition to that, in a semiconductor laser there is a contribution arising from fluctuations in the refractive index induced by carrier density fluctuations. The later are quantitatively described by the linewidth enhancement or alpha factor [C. H. Henry, IEEE J. Quantum Electron. 18 (2), 259 (1982), W. W. Chow, S. W. Koch and M. Sargent III, Semiconductor-Laser Physics, Springer-Verlag (1994), M.F. Pereira Jr et al, J. Opt. Soc. Am. B10, 765 (1993). In this paper we investigate the alpha factor of quantum cascade lasers under actual operating conditions using the Nonequilibrium Greens Functions approach [A. Wacker et a, IEEE Journal of Sel. Top. in Quantum Electron.,19 1200611, (2013), T. Schmielau and M.F. Pereira, Appl. Phys. Lett. 95 231111, (2009)]. The simulations are compared with recent results obtained with different optical feedback techniques [L. Jumpertz et al, AIP ADVANCES 6, 015212 (2016)].

Characterization of skin tissue soldering using diode laser and indocyanine green: in vitro studies.

PubMed

Khosroshahi, M E; Nourbakhsh, M S; Saremi, S; Tabatabaee, F

2010-03-01

Laser tissue soldering based on protein as biological glues and other compounds can provide greater bond strength and less collateral damage. Endogenous and exogenous materials such as indocyanine green (ICG) are often added to solders to enhance light absorption. The purpose of this in vitro study was to examine the impact of different parameters of laser soldering on the thermo-physical properties of the skin. A mixture of albumin solder and ICG was prepared, and then the coated samples were irradiated by an 810 nm diode laser under different conditions. The temperature rise, number of scans (N(s)), and scan velocity (V(s)) were investigated in this study. The results showed that, at each laser irradiance (I), the tensile strength (sigma) of incisions repaired in static mode was higher than in dynamic mode and that the sigma increased with both increasing N(s) and increasing I. It is therefore important to consider the trade off between scan velocity and surface temperature for achieving an optimum operating condition.

Power-Scalable Blue-Green Bessel Beams

DTIC Science & Technology

2016-02-23

19b. TELEPHONE NUMBER (Include area code) 02/23/2016 Final Technical JAN 2011 - DEC 2013 Power-Scalable Blue -Green Bessel Beams Siddharth Ramachandran...fiber lasers, non-traditional emission wavelengths, high-power blue -green tunabel lasers U U U SAR 11 Siddharth Ramachandran 617-353-9811 1 Power...Scalable Blue -Green Bessel Beams Siddharth Ramachandran Photonics Center, Boston University, 8 Saint Mary’s Street, Boston, MA 02215 phone: (617) 353

Holographic recording in a doubly doped lithium niobate crystal with two wavelengths: a blue laser diode and a green laser

NASA Astrophysics Data System (ADS)

Komori, Yuichi; Ishii, Yukihiro

2010-08-01

A doubly-doped LiNbO3 (LN) crystal has been well used as a nonvolatile two-wavelength recording material. By using two levels of the crystal, two-kind holograms can be recorded on one crystal; a hologram is recorded with a 405-nm blue laser diode (LD) for a deep Mn level, and another hologram is with a 532-nm green laser for a shallow Fe level. The recording capacity doubles. A 780-nm LD is non-volatile reconstructing source since the LD line is insensitive to both levels. Multiplexed reconstructed images are demonstrated by using a sharp angular selectivity of a volume LN crystal keeping Bragg condition with spherical reconstructions.

Two-photon excitation of 2,5-diphenyloxazole using a low power green solid state laser

NASA Astrophysics Data System (ADS)

Luchowski, Rafal

2011-01-01

This Letter concerns two-photon excitation of 2,5-diphenyloxazole (PPO) upon illumination from a pulsed 532 nm solid state laser, with an average power of 30 mW, and a repetition rate of 20 MHz. A very agreeable emission spectrum position and shape has been achieved for PPO receiving one- and two-photon excitation, which suggests that the same excited state is involved for both excitation modes. Also, a perfect quadratic dependence of laser power in the emission intensity function has been recorded. We tested the application of a small solid state green laser to two-photon induced time-resolved fluorescence, revealing the emission anisotropy of PPO to be considerably higher for two-photon than for one-photon excitation.

Outcome of solid-state 532 nm green laser in high-risk retinopathy of prematurity at a tertiary care centre in India.

PubMed

Chhabra, Kanika; Kaur, Prempal; Singh, Karamjit; Aggarwal, Anand; Chalia, Dharamvir

2018-02-01

The purpose of this study was to analyse the outcome of solid-state green laser in high-risk retinopathy of prematurity (ROP) at a tertiary centre in India. Fifty-nine eyes of 30 infants with high-risk ROP were recruited in this prospective, interventional study. High-risk ROP included prethreshold type 1 ROP and APROP. Laser photocoagulation was performed with 532 nm solid-state green laser (Novus Spectra, Lumenis, GmbH, Germany). Of the 30 infants, 18 were males (60%) and 12 were females (40%). The mean birth weight was 1102.83 ± 196.27 g. The mean gestational age was 29.5 ± 1.47 weeks. Zone 1 disease was present in 10 eyes (16.95%) and zone 2 disease in 49 (83.05%) eyes. Out of 57 eyes with prethreshold type 1 ROP, 39 eyes (68.42%) had stage 2 and 18 eyes (31.58%) had stage 3. The postconceptional age at the time of treatment was 36.03 ± 2.32 weeks. The infants received mean 2710.24 ± 747.97 laser spots. Fifty (84.8%) eyes underwent laser in a single sitting and 9 eyes (15.2%) required 2 laser sittings. Mean time for regression of ROP was 5.8 ± 3.8 weeks (range 3-11 weeks). Total ROP regression was seen in 55 eyes (93.22%). Despite laser treatment, 4 (6.78%) eyes of three infants had unfavourable outcome. One infant developed intra-procedural bradycardia. Vitreous haemorrhage was seen in five eyes (8.4%). Solid-state 532 nm green laser is a safe and effective treatment for high-risk retinopathy of prematurity.

Green-synthetized silver nanoparticles for Nanoparticle-Enhanced Laser Induced Breakdown Spectroscopy (NELIBS) using a mobile instrument

NASA Astrophysics Data System (ADS)

Poggialini, F.; Campanella, B.; Giannarelli, S.; Grifoni, E.; Legnaioli, S.; Lorenzetti, G.; Pagnotta, S.; Safi, A.; Palleschi, V.

2018-03-01

When compared to other analytical techniques, LIBS shows relatively low precision and, generally, high Limits of Detection (LODs). Until recently, the attempts in improving the LIBS performances have been based on the use of more stable/powerful lasers, high sensitivity detectors or controlled environmental parameters. This can hinder the competitiveness of LIBS by increasing the instrumental setup cost and the difficulty of operation. Sample treatment has proved to be a viable and simple way to increase the LIBS signal; in particular, the Nanoparticle-Enhanced Laser Induced Breakdown Spectroscopy (NELIBS) methodology uses a deposition of metal nanoparticles on the sample to greatly increase the emission of the LIBS plasma. In this work, we used a simple, fast, "green" and low-cost method to synthetize silver nanoparticles by using coffee extract as reducing agents for a silver nitrate solution. This allowed us to obtain nanoparticles of about 25 nm in diameter. We then explored the application of such nanoparticles to the NELIBS analysis of metallic samples with a mobile LIBS instrument. By adjusting the laser parameters and optimizing the sample preparation procedure, we obtained a NELIBS signal that is 4 times the LIBS one. This showed the potential of green-synthetized nanoparticle for NELIBS applications and suggests the possibility of an in-situ application of the technique.

Laser-initiated decomposition products of indocyanine green (ICG) and carbon black sensitized biological tissues

NASA Astrophysics Data System (ADS)

Kokosa, John M.; Przyjazny, Andrzej; Bartels, Kenneth E.; Motamedi, Massoud; Hayes, Donald J.; Wallace, David B.; Frederickson, Christopher J.

1997-05-01

Organic dyes have found increasing use a s sensitizers in laser surgical procedures, due to their high optical absorbances. Little is known, however, about the nature of the degradation products formed when these dyes are irradiated with a laser. Previous work in our laboratories has shown that irradiation of polymeric and biological tissues with CO2 and Nd:YAG lasers produces a host of volatile and semivolatile by-products, some of which are known to be potential carcinogens. This work focuses on the identification of the chemical by-products formed by diode laser and Nd:YAG laser irradiation of indocyanine green (ICG) and carbon black based ink sensitized tissues, including bone, tendon and sheep's teeth. Samples were mounted in a 0.5-L Pyrex sample chamber equipped with quartz optical windows, charcoal filtered air inlet and an outlet attached to an appropriate sample trap and a constant flow pump. By-products were analyzed by GC/MS and HPLC. Volatiles identified included benzene and formaldehyde. Semi-volatiles included traces of polycyclic aromatics, arising from the biological matrix and inks, as well as fragments of ICG and the carbon ink components. The significance of these results will be discussed, including the necessity of using appropriate evacuation devices when utilizing lasers for surgical procedures.

Elemental detection of arabica and robusta green bean coffee using laser-induced plasma spectroscopy

NASA Astrophysics Data System (ADS)

Abdulmadjid, Syahrun Nur; Meilina, Hesti; Hedwig, Rinda; Kurniawan, Koo Hendrik

2017-01-01

The elemental detection of green bean of arabica and robusta coffee from Gayo Highland, Aceh-Indonesia, has been identified by using fundamental Nd-YAG Laser at 10 Torr of surrounding air gas pressure for distinguishing the characteristics of both coffees. As the preliminary study, we have detected the elements of K 766.49 nm, Na 588.9 nm, Ca 393.3 nm, CN band at 388.3 nm, N 337.13 nm and C 247.8 nm of both coffees. It is noticed that the order of elements concentration from highest to lowest are Ca>K>CN> Na>N> C for arabica and K>Ca>CN >Na>C>N for robusta. The emission intensity of K 766.49 nm is almost same for both of coffee. However, the emission intensity of Na 588.9 nm is lower in Arabica coffee. To distinguish the Arabica coffee and Robusta Coffee, we take the ratio intensity of K/C, Na/C, CN/C, and Ca/C. It is found that the ratio intensities of CN/C and Ca/C in arabica bean are significantly different with robusta bean. That ratio intensities can be used as a marker to discriminate kind of coffee. We also noted that the arabica green bean is 1.3 harder than robusta green bean. These findings prove that the technique of laser-induced plasma spectroscopy can be used to make rapid identification of elements in coffee and can potentially be applied to measure the concentration of blended coffee for the purpose of authentication.

Thermal and infrared-diode laser effects on indocyanine-green-treated corneal collagen

NASA Astrophysics Data System (ADS)

Timberlake, George T.; Patmore, Ann; Shallal, Assaad; McHugh, Dominic; Marshall, John

1993-07-01

It has been suggested that laser welds of collagenous tissues form by interdigitation and chemical bonding of thermally 'unraveled' collagen fibrils. We investigated this proposal by attempting to weld highly collagenous, avascular corneal tissue with an infrared (IR) diode laser as follows. First, the temperature at which corneal collagen shrinks and collagen fibrils 'split' into subfibrillary components was determined. Second, since use of a near-IR laser wavelength necessitated addition of an absorbing dye (indocyanine green (ICG) to the cornea, we measured absorption spectra of ICG-treated tissue to ensure that peak ICG absorbance did not change markedly when ICG was present in the cornea. Third, using gel electrophoresis of thermally altered corneal collagen, we searched for covalently crosslinked compounds predicted by the proposed welding mechanism. Finally, we attempted to weld partial thickness corneal incisions infused with ICG. Principal experimental findings were as follows: (1) Human corneal (type I) collagen splits into subfibrillary components at approximately 63 degree(s)C, the same temperature that produces collagen shrinkage. (2) Peak ICG absorption does not change significantly in corneal stroma or with laser heating. (3) No evidence was found for the formation of novel compounds or the loss of proteins as a result of tissue heating. All tissue treated with ICG, however, exhibited a novel 244 kD protein band indicating chemical activity between collagen and corneal stromal components. (4) Laser welding corneal incisions was unsuccessful possibly due to shrinkage of the sides of the incision, lack of incision compression during heating, or a less than optimal combination of ICG concentration and radiant exposure. In summary, these experiments demonstrate the biochemical and morphological complexity of ICG-enhanced IR laser-tissue welding and the need for further investigation of laser welding mechanisms.

Learning curves and perioperative outcomes after endoscopic enucleation of the prostate: a comparison between GreenLight 532-nm and holmium lasers.

PubMed

Peyronnet, Benoit; Robert, Grégoire; Comat, Vincent; Rouprêt, Morgan; Gomez-Sancha, Fernando; Cornu, Jean-Nicolas; Misrai, Vincent

2017-06-01

To compare the learning curves, perioperative and early functional outcomes after HoLEP and GreenLEP. Data from the first 100 consecutive cases treated by GreenLEP and HoLEP by two surgeons were prospectively collected from dedicated databases and analysed retrospectively. En-bloc GreenLEP and two-lobar HoLEP enucleations were conducted using the GreenLight HPS™ 2090 laser and Lumenis™ holmium laser. Patients' characteristics, perioperative outcomes and functional outcomes after 1, 3 and 6 months were compared between groups. Total energy delivered and operative times were significantly shorter for GreenLEP (58 vs. 110 kJ, p < 0.0001; 60 vs. 90 min, p < 0.0001). Operative time reached a plateau after 30 procedures in each group. Length of catheterization and hospital stay were significantly shorter in the HoLEP group (2 vs. 1 day, p < 0.0001; 2 vs. 1 day, p < 0.0001). Postoperative complications were comparable between GreenLEP and HoLEP (19 vs. 25 %; p = 0.13). There was a greater increase of Q max at 3 months and a greater IPSS decrease at 1 month for GreenLEP, whereas decreases in IPSS and IPSS-Q8 at 6 months were greater for HoLEP. Transient stress urinary incontinence was comparable between both groups (6 vs. 9 % at 3 months; p = 0.42). Pentafecta was achieved in four consecutive patients after the 18th and the 40th procedure in the GreenLEP and HoLEP group, respectively. Learning curves ranged from 14 to 30 cases for GreenLEP and 22 to 40 cases for HoLEP. Learning curves of GreenLEP and HoLEP provided roughly similar peri-operative and short-term functional outcomes.

Whom should we SPY? A cost analysis of laser-assisted indocyanine green angiography in prevention of mastectomy skin flap necrosis during prosthesis-based breast reconstruction.

PubMed

Kanuri, Arjun; Liu, Allen S; Guo, Lifei

2014-04-01

Skin flap necrosis is the most common complication following prosthesis-based breast reconstruction. Many studies have reported on the efficacy of laser-assisted indocyanine green angiography (SPY Elite System) in detecting flap necrosis. A cost-effectiveness analysis of laser-assisted indocyanine green angiography is lacking. The authors performed a retrospective review of all consecutive immediate postmastectomy prosthesis-based reconstructions at the Brigham and Women's Hospital over a 7-year 10-month period. The rate of mastectomy skin flap necrosis and related implant loss was determined for the entire cohort and for the subgroups of patients at increased risk for developing this complication: smokers, obese patients, and patients with large breasts. Cost of treating implant loss and skin flap necrosis was calculated based on the average treatment courses and costs at the authors' institution. The cost of the SPY was obtained from LifeCell Corp. From January of 2004 through October of 2011, 79 of 710 prosthesis-based breast reconstructions (11.1 percent) developed mastectomy skin flap necrosis requiring excision and reclosure. Performing laser-assisted indocyanine green angiography on the entire cohort would result in an additional cost of $1537.30 per case of flap necrosis prevented. If laser-assisted indocyanine green angiography was performed on only these high-risk subgroups, the cost savings per case of flap necrosis prevented is $2098.80 for smokers, $5162.30 for patients with a body mass index greater than 30, and $1892.70 for patients with mastectomy weight greater than 800 g. Laser-assisted indocyanine green angiography is not cost-effective as a preventative measure for flap necrosis if used indiscriminately on all patients undergoing prosthesis-based breast reconstructions, but it is cost-effective for high-risk patients, such as smokers, obese patients, and patients with large breasts.

Optically pumped quantum-dot Cd(Zn)Se/ZnSe laser and microchip converter for yellow-green spectral region

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lutsenko, E V; Voinilovich, A G; Rzheutskii, N V

2013-05-31

The room temperature laser generation in the yellow-green ({lambda} = 558.5-566.7 nm) spectral range has been demonstrated under optical pumping by a pulsed nitrogen laser of Cd(Zn)Se/ZnSe quantum dot heterostructures. The maximum achieved laser wavelength was as high as {lambda} = 566.7 nm at a laser cavity length of 945 {mu}m. High values of both the output pulsed power (up to 50 W) and the external differential quantum efficiency ({approx}60%) were obtained at a cavity length of 435 {mu}m. Both a high quality of the laser heterostructure and a low lasing threshold ({approx}2 kW cm{sup -2}) make it possible tomore » use a pulsed InGaN laser diode as a pump source. A laser microchip converter based on this heterostructure has demonstrated a maximum output pulse power of {approx}90 mW at {lambda} = 560 nm. The microchip converter was placed in a standard TO-18 (5.6 mm in diameter) laser diode package. (semiconductor lasers. physics and technology)« less

Transscleral thermotherapy with laser-induced and conductive heating in hamster Greene melanoma.

PubMed

Rem, Alex I; Oosterhuis, Jendo A; Keunen, Jan E E; Journée-De Korver, Hanneke G

2004-10-01

The purpose of this study was to investigate the cytotoxic effect of heat as induced by transscleral thermotherapy (TSTT), which may be of interest in the treatment of patients with choroidal melanoma. The aim of TSTT is to heat both the sclera and the tumor up to a cytotoxic temperature of about 60 degrees C. TSTT was performed in hamsters with subcutaneously implanted Greene melanoma covered by a specimen of human donor sclera of thickness 0.5, 0.7 or 0.9 mm. A newly developed applicator, which combines conductive episcleral heating at 60 degrees C with laser-induced heating, was used at laser powers ranging from 500 to 1500 mW delivered by an 810 nm diode laser, beam diameter 3 mm, and exposure time 1 min. Temperatures were measured at the scleral surface and at the sclera-tumor interface. The extent of tumor necrosis was examined by light microscopy and the sclera was examined by polarized light microscopy. Maximal depth of tumor necrosis without scleral damage was 4.4 (SD 1.5) mm. The temperature at the scleral surface after TSTT was 58.8 (SD 2.4) degrees C. The temperature at the sclera-tumor interface ranged from 56.4 (SD 3.7) degrees C at 500 mW to 65.3 (SD 4.4) degrees C at 1250 mW laser power. Structural changes to the scleral collagen started to develop at 1250 mW. TSTT with combined laser-induced and conductive heating caused cytotoxic temperatures in the tumor and the sclera, which were well tolerated by the scleral collagen.

Passively Q-switched, intracavity frequency-doubled YVO{sub 4}/Nd : YVO{sub 4}/KTP green laser with a GaAs saturable absorber

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shang Gao

2015-11-30

A diode-pumped, passively Q-switched, intracavity frequency-doubled YVO{sub 4}/Nd : YVO{sub 4}/KTP green laser is realised using a GaAs saturable absorber. Two pieces of GaAs wafers are employed in the experiment. In using a 400-μm-thick GaAs wafer and an incident pump power of 10.5 W, the maximum output power of the passively Q-switched green laser is 362 mW at a pulse repetition rate of 84 kHz and a pulse duration of 2.5 ns. When use is made of a 700-mm-thick GaAs wafer, the minimum pulse duration is 1.5 ns at a repetition rate of 67 kHz, pulse energy of 4.18 μJmore » and peak power of 2.8 kW. (control of laser radiation parameters)« less

Photothermal and photochemical effects of laser light absorption by indocyanine green (ICG)

NASA Astrophysics Data System (ADS)

Yaseen, Mohammad A.; Diagaradjane, Parmeswaran; Pikkula, Brian M.; Yu, Jie; Wong, Michael S.; Anvari, Bahman

2005-04-01

Indocyanine Green (ICG) is clinically used as a fluorescent dye for imaging purposes. Its rapid circulation kinetics and minimal toxicity has prompted investigation into ICG's utility as a photosentitizer for therapeutic applications. Traditionally, optically mediated tumor therapy has focused on photodynamic therapy, which employs a photochemical mechanism resulting from the absorption of low intensity CW laser light by localized photosensitizers such as Photofrin II, Benzoporphyrin Derivative (BPD), ICG. Treatment of cutaneous vascular malformations such as port-wine stains, on the other hand, is based on a photothermal mechanism resulting from the absorption of high intensity pulsed laser light by hemoglobin. In this study, we compared the effectiveness of combining photochemical and photothermal mechanisms during application of ICG in conjunction with laser irradiation with the intention that the combined approach may lead to a reduction in the threshold dose of pulsed laser light required to treat hypervascular malformations. The blood vessels in rabbit ears were used as an in vivo model for targeted vasculature. Irradiation of the ears with IR light (λ=785 nm, Δτ = 3 min, Io = 120 mW) was used to elicit photochemical damage, while photothermal damage was brought about using pulses from a ruby laser (λ=694 nm, τ = 3 ms) with different fluences. For the combined modality, photochemical damage was induced first and followed by photothermal irradiation. This modality was compared with photothermal irradiation alone. The effectiveness of each irradiation scheme was assessed using histopathological analysis. We present preliminary data that suggests that pretreatment with photodynamic therapy before photothermal coagulation results in more severe vascular damage with lower photothermal fluence levels. The results of this study provide the foundation work for further exploration of the therapeutic potentials of photochemical and photothermal effects during

Enhanced laser tissue soldering using indocyanine green chromophore and gold nanoshells combination.

PubMed

Khosroshahi, Mohammad E; Nourbakhsh, Mohammad S

2011-08-01

Gold nanoshells (GNs) are new materials that have an optical response dictated by the plasmon resonance. The wavelength at which the resonance occurs depends on the core and shell sizes. The purposes of this study were to use the combination of indocyanine green (ICG) and different concentration of gold nanoshells for skin tissue soldering and also to examine the effect of laser soldering parameters on the properties of repaired skin. Two mixtures of albumin solder and different combinations of ICG and gold nanoshells were prepared. A full thickness incision of 2 × 20 mm(2) was made on the surface and after addition of mixtures it was irradiated by an 810 nm diode laser at different power densities. The changes of tensile strength (σ(t)) due to temperature rise, number of scan (Ns), and scan velocity (Vs) were investigated. The results showed at constant laser power density (I), σ(t) of repaired incisions increases by increasing the concentration of gold nanoshells in solder, Ns, and decreasing Vs. It was demonstrated that laser soldering using combination of ICG + GNs could be practical provided the optothermal properties of the tissue are carefully optimized. Also, the tensile strength of soldered skin is higher than skins that soldered with only ICG or GNs. In our case, this corresponds to σ(t) = 1800 g cm(-2) at I ∼ 47 Wcm(-2), T ∼ 85 [ordinal indicator, masculine]C, Ns = 10, and Vs = 0.3 mms(-1).

Compact Blue-Green Lasers: Summaries of Papers Presented at the Topical Meeting Held in Sante Fe, New Mexico on 20-21 February 1992. Volume 6. Technical Digest Series

DTIC Science & Technology

1992-02-21

Contents: Applications, IR Pumped Visible Lasers, Blue-Green Diode Emitters, Materials, Poster Session, Frequency Conversion in Bulk Devices, Gas Lasers, and Frequency Conversion in Guided-Wave Devices.

Efficient and compact Q-switched green laser using graphene oxide as saturable absorber

NASA Astrophysics Data System (ADS)

Chang, Jianhua; Li, Hanhan; Yang, Zhenbo; Yan, Na

2018-01-01

A new type of graphene oxide (GO) is successfully prepared using an improved modified Hummers method. The Raman shift, X-ray diffraction (XRD), and scanning electron microscope (SEM) measurement techniques are used to characterize the GO. An efficient and compact Q-switched green laser based on Nd:YVO4/PPLN is demonstrated with a few-layered GO as the saturable absorber. Our experimental results show that such a few-layered GO saturable absorber allows for the generation of a stable Q-switched laser pulse centered at 532.1 nm with a 3 dB spectral bandwidth of 2.78 nm, a repetition rate of 71.4 kHz, and a pulse duration of 98 ns. The maximum average output power of 536 mW is obtained at the absorbed pump power of 5.16 W, corresponding to an optical conversion efficiency of 10.3%.

Red krypton and blue-green argon panretinal laser photocoagulation for proliferative diabetic retinopathy: a laboratory and clinical comparison.

PubMed

Blankenship, G W

1986-01-01

The effects of PRP with red krypton laser are essentially identical to those produced with blue-green argon laser. Burns of the rabbit retina produced with these two different lasers are almost the same. In a prospective and randomized clinical trial of proliferative diabetic retinopathy treatment there was no significant difference between PRP using these two different lasers. The characteristic changes of rabbit fundi 3, 7, and 30 days after PRP with red krypton laser were almost the same as those following blue-green argon laser. Both types of treatment frequently produced small vitreous hemorrhages and exudative retinal detachments, but choroidal thickening occurred more frequently with argon treatment. These changes were transient and had resolved within 30 days of treatment. The microscopic changes consisted of pigment epithelial disruption with pigment migration into the retina, heat coagulation of the photoreceptors, disruption of the outer and inner nuclear layers with atrophy of the nuclei, and temporary swelling of the nerve fiber layer. The untreated retina and choroid between burns was not involved and appeared normal at each period. Thirty days after treatment, the scarring produced by these two types of burns was identical. Seventy-one eyes with proliferative diabetic retinopathy having three or four retinopathy risk factors were treated with panretinal laser photocoagulation, and followed in a prospective study for 6 months. Thirty-six eyes were randomly selected for blue-green argon treatment, and 35 were randomly selected for red krypton treatment. The incidence of undesired side effects during the first 2 weeks following treatment was almost identical between the two groups. However, by 1 month the majority of eyes in both groups had visual acuities equal to or better than the pretreatment acuities and complete regression of NVD. Six months after treatment, the majority of eyes in both groups continued to have visual acuities equal to or better

High-power green and blue electron-beam pumped surface-emitting lasers using dielectric and epitaxial distributed Bragg reflectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klein, T., E-mail: tklein@ifp.uni-bremen.de; Klembt, S.; Institut Néel, Université Grenoble Alpes and CNRS, B.P. 166, 38042 Grenoble

2015-03-21

ZnSe-based electron-beam pumped vertical-cavity surface-emitting lasers for the green (λ = 530 nm) and blue (λ = 462 nm) spectral region have been realized. Structures with and without epitaxial bottom distributed Bragg reflector have been fabricated and characterized. The samples consist of an active region containing 20 quantum wells with a cavity length varying between an optical thickness of 10 λ to 20 λ. The active material is ZnCdSSe in case of the green devices and ZnSe for the blue ones. Room temperature single mode lasing for structures with and without epitaxial bottom mirror with a maximum output power up to 5.9 W (green) and 3.3 W (blue)more » is achieved, respectively.« less

Morphology alterations of skin and subcutaneous fat at NIR laser irradiation combined with delivery of encapsulated indocyanine green

NASA Astrophysics Data System (ADS)

Yanina, Irina Yu.; Navolokin, Nikita A.; Svenskaya, Yulia I.; Bucharskaya, Alla B.; Maslyakova, Galina N.; Gorin, Dmitry A.; Sukhorukov, Gleb B.; Tuchin, Valery V.

2017-05-01

The goal of this study is to quantify the impact of the in vivo photochemical treatment of rats with obesity using indocyanine green (ICG) dissolved in saline or dispersed in an encapsulated form at NIR laser irradiation, which was monitored by tissue sampling and histochemistry. The subcutaneous injection of the ICG solution or ICG encapsulated into polyelectrolyte microcapsules, followed by diode laser irradiation (808 nm, 8 W/cm2, 1 min), resulted in substantial differences in lipolysis of subcutaneous fat. Most of the morphology alterations occurred in response to the laser irradiation if a free-ICG solution had been injected. In such conditions, membrane disruption, stretching, and even delamination in some cases were observed for a number of cells. The encapsulated ICG aroused similar morphology changes but with weakly expressed adipocyte destruction under the laser irradiation. The Cochran Q test rendered the difference between the treatment alternatives statistically significant. By this means, laser treatment using the encapsulated form of ICG seems more promising and could be used for safe layerwise laser treatment of obesity and cellulite.

Morphology alterations of skin and subcutaneous fat at NIR laser irradiation combined with delivery of encapsulated indocyanine green.

PubMed

Yanina, Irina Yu; Navolokin, Nikita A; Svenskaya, Yulia I; Bucharskaya, Alla B; Maslyakova, Galina N; Gorin, Dmitry A; Sukhorukov, Gleb B; Tuchin, Valery V

2017-05-01

The goal of this study is to quantify the impact of the in vivo photochemical treatment of rats with obesity using indocyanine green (ICG) dissolved in saline or dispersed in an encapsulated form at NIR laser irradiation, which was monitored by tissue sampling and histochemistry. The subcutaneous injection of the ICG solution or ICG encapsulated into polyelectrolyte microcapsules, followed by diode laser irradiation (808 nm, 8 ?? W / cm 2 , 1 min), resulted in substantial differences in lipolysis of subcutaneous fat. Most of the morphology alterations occurred in response to the laser irradiation if a free-ICG solution had been injected. In such conditions, membrane disruption, stretching, and even delamination in some cases were observed for a number of cells. The encapsulated ICG aroused similar morphology changes but with weakly expressed adipocyte destruction under the laser irradiation. The Cochran Q test rendered the difference between the treatment alternatives statistically significant. By this means, laser treatment using the encapsulated form of ICG seems more promising and could be used for safe layerwise laser treatment of obesity and cellulite.

Continuous-wave yellow-green laser at 0.56  μm based on frequency doubling of a diode-end-pumped ceramic Nd:YAG laser.

PubMed

Yao, Wenming; Gao, Jing; Zhang, Long; Li, Jiang; Tian, Yubing; Ma, Yufei; Wu, Xiaodong; Ma, Gangfei; Yang, Jianming; Pan, Yubai; Dai, Xianjin

2015-06-20

We present what is, to the best of our knowledge, the first report on yellow-green laser generation based on the frequency doubling of the 1.1 μm transitions in Nd:YAG ceramics. By employing an 885 nm diode laser as the end-pumping source and a lithium triborate crystal as the frequency doubler, the highest continuous wave output powers of 1.4, 0.5, and 1.1 W at 556, 558, and 561 nm are achieved, respectively. These result in optical-to-optical efficiencies of 6.9%, 2.5%, and 5.4% with respect to the absorbed pump power, respectively.

New alternatives for laser vaporization of the prostate: experimental evaluation of a 980-, 1,318- and 1,470-nm diode laser device.

PubMed

Wezel, Felix; Wendt-Nordahl, Gunnar; Huck, Nina; Bach, Thorsten; Weiss, Christel; Michel, Maurice Stephan; Häcker, Axel

2010-04-01

Several diode laser systems were introduced in recent years for the minimal-invasive surgical therapy of benign prostate enlargement. We investigated the ablation capacities, hemostatic properties and extend of tissue necrosis of different diode lasers at wavelengths of 980, 1,318 and 1,470 nm and compared the results to the 120 W GreenLight HPS laser. The laser devices were evaluated in an ex vivo model using isolated porcine kidneys. The weight difference of the porcine kidneys after 10 min of laser vaporization defined the amount of ablated tissue. Blood loss was measured in blood-perfused kidneys following laser vaporization. Histological examination was performed to assess the tissue effects. The side-firing 980 and 1,470 nm diode lasers displayed similar ablative capacities compared to the GreenLight HPS laser (n.s.). The 1,318-nm laser, equipped with a bare-ended fiber, reached a higher ablation rate compared to the other laser devices (each P < 0.05). A calculated 'output power efficiency per watt' revealed that the 1,318-nm laser with a bare-ended fiber reached the highest rate compared to the side-firing devices (each P < 0.0001). All three diode lasers showed superior hemostatic properties compared to the GreenLight HPS laser (each P < 0.01). The extend of morphological tissue necrosis was 4.62 mm (1,318 nm), 1.30 mm (1,470 nm), 4.18 mm (980 nm) and 0.84 mm (GreenLight HPS laser), respectively. The diode lasers offered similar ablative capacities and improved hemostatic properties compared to the 120 W GreenLight HPS laser in this experimental ex vivo setting. The higher tissue penetration of the diode lasers compared to the GreenLight HPS laser may explain improved hemostasis.

Portable hyperspectral imager with continuous wave green laser for identification and detection of untreated latent fingerprints on walls.

PubMed

Nakamura, Atsushi; Okuda, Hidekazu; Nagaoka, Takashi; Akiba, Norimitsu; Kurosawa, Kenji; Kuroki, Kenro; Ichikawa, Fumihiko; Torao, Akira; Sota, Takayuki

2015-09-01

Untreated latent fingerprints are known to exhibit fluorescence under UV laser excitation. Previously, the hyperspectral imager (HSI) has been primarily evaluated in terms of its potential to enhance the sensitivity of latent fingerprint detection following treatment by conventional chemical methods in the forensic science field. In this study however, the potential usability of the HSI for the visualization and detection of untreated latent fingerprints by measuring their inherent fluorescence under continuous wave (CW) visible laser excitation was examined. Its potential to undertake spectral separation of overlapped fingerprints was also evaluated. The excitation wavelength dependence of fluorescent images was examined using an untreated palm print on a steel based wall, and it was found that green laser excitation is superior to blue and yellow lasers' excitation for the production of high contrast fluorescence images. In addition, a spectral separation method for overlapped fingerprints/palm prints on a plaster wall was proposed using new images converted by the division and subtraction of two single wavelength images constructed based on measured hyperspectral data (HSD). In practical tests, the relative isolation of two overlapped fingerprints/palm prints was successful in twelve out of seventeen cases. Only one fingerprint/palm print was extracted for an additional three cases. These results revealed that the feasibility of overlapped fingerprint/palm print spectral separation depends on the difference in the temporal degeneration of each fluorescence spectrum. The present results demonstrate that a combination of a portable HSI and CW green laser has considerable potential for the identification and detection of untreated latent fingerprints/palm prints on the walls under study, while the use of HSD makes it practically possible for doubly overlapped fingerprints/palm prints to be separated spectrally. Copyright © 2015 Elsevier Ireland Ltd. All rights

Differential tissue expression of enhanced green fluorescent protein in 'green mice'.

PubMed

Ma, De-Fu; Tezuka, Hideo; Kondo, Tetsuo; Sudo, Katsuko; Niu, Dong-Feng; Nakazawa, Tadao; Kawasaki, Tomonori; Yamane, Tetsu; Nakamura, Nobuki; Katoh, Ryohei

2010-06-01

In order to clarify tissue expression of enhanced green fluorescent protein (EGFP) in 'green mice' from a transgenic line having an EGFP cDNA under the control of a chicken beta-actin promoter and cytomegalovirus enhancer, we studied the expression of EGFP in various organs and tissues from these 'green mice' by immunohistochemistry with anti- EGFP antibody in conjunction with direct observation for EGFP fluorescence using confocal laser scanning microscopy. On immunohistochemical examination and on direct observation by confocal laser scanning microscopy, the level of EGFP expression varied among organs and tissues. EGFP expression was diffusely and strongly observed in the skin, pituitary, thyroid gland, parathyroid gland, heart, gall bladder, pancreas, adrenals and urinary bladder. There was only sporadic and weak expression of EGFP in the epithelium of the trachea, bronchus of the lung, stratified squamous epithelium and gastric glands of the stomach, hepatic bile ducts of the liver, glomeruli and renal tubules of the kidney and endo-metrial glands of the uterus. Furthermore, EGFP was only demonstrated within the goblet and paneth cells in the colon and small intestine, the tall columnar cells in the ductus epididymis, and the leydig cells in the testis. In conclusion, our results show that EGFP is differentially expressed in organs and tissues of 'green mice', which indicates that 'green mice' may prove useful for research involving transplantation and tissue clonality.

[KTP (green light) laser for the treatment of benign prostatic hyperplasia. Preliminary evaluation].

PubMed

Coz, Fernando; Domenech, Alfredo

2007-09-01

Photoselective vaporization of benign prostatic hyperplasia (BPH) is a minimally invasive technique, consisting of vaporization of prostatic tissue by KTP green light laser with a power of 80 W. The purpose of this study was to describe our experience with this technique. KTP laser photoselective vaporization was performed in 18 patients, with lower obstructive uropathy secondary to benign prostatic hyperplasia at Santiago Military hospital from December 2005. Preoperative characteristics, postoperative results and complications were recorded. Mean prostatic volume was 55 cc (range: 24 to 78). Mean operating time was 83 minutes (range: 40 to 120). In sixteen patients, the Foley catheter was removed before 24 hours. The mean preoperative AUA score was 22 and decreased to 11.4 after 30 days. The mean maximum preoperative urine flow rate was 9 ml/s and increased to 18.2; 22.1; 22.5; 25.3 and 27.2 ml/s on days 1, 7, 14, 21 and 30, respectively. Only minor complications were observed: delayed removal of the Foley catheter (11.1%), dysuria (16.6%) and late haematuria (11.1%). KTP laser photoselective vaporization of BPH is a safe technique, that is easy to learn, with good short-term functional results, associated with low complication rate.

Non-equilibrium Green's function calculation for GaN-based terahertz-quantum cascade laser structures

NASA Astrophysics Data System (ADS)

Yasuda, H.; Kubis, T.; Hosako, I.; Hirakawa, K.

2012-04-01

We theoretically investigated GaN-based resonant phonon terahertz-quantum cascade laser (QCL) structures for possible high-temperature operation by using the non-equilibrium Green's function method. It was found that the GaN-based THz-QCL structures do not necessarily have a gain sufficient for lasing, even though the thermal backfilling and the thermally activated phonon scattering are effectively suppressed. The main reason for this is the broadening of the subband levels caused by a very strong interaction between electrons and longitudinal optical (LO) phonons in GaN.

Vaporization and recondensation dynamics of indocyanine green-loaded perfluoropentane droplets irradiated by a short pulse laser

NASA Astrophysics Data System (ADS)

Yu, Jaesok; Chen, Xucai; Villanueva, Flordeliza S.; Kim, Kang

2016-12-01

Phase-transition droplets have been proposed as promising contrast agents for ultrasound and photoacoustic imaging. Short pulse laser activated perfluorocarbon-based droplets, especially when in a medium with a temperature below their boiling point, undergo phase changes of vaporization and recondensation in response to pulsed laser irradiation. Here, we report and discuss the vaporization and recondensation dynamics of perfluoropentane droplets containing indocyanine green in response to a short pulsed laser with optical and acoustic measurements. To investigate the effect of temperature on the vaporization process, an imaging chamber was mounted on a temperature-controlled water reservoir and then the vaporization event was recorded at 5 million frames per second via a high-speed camera. The high-speed movies show that most of the droplets within the laser beam area expanded rapidly as soon as they were exposed to the laser pulse and immediately recondensed within 1-2 μs. The vaporization/recondensation process was consistently reproduced in six consecutive laser pulses to the same area. As the temperature of the media was increased above the boiling point of the perfluoropentane, the droplets were less likely to recondense and remained in a gas phase after the first vaporization. These observations will help to clarify the underlying processes and eventually guide the design of repeatable phase-transition droplets as a photoacoustic imaging contrast agent.

Lif and Raman Spectroscopy in Undergraduate Labs Using Green Diode-Pumped Solid-State Lasers

NASA Astrophysics Data System (ADS)

Gray, Jeffrey A.

2015-06-01

Electronic spectroscopy of molecular iodine vapor has long been studied in undergraduate physical chemistry teaching laboratories, but the effectiveness of emission work has typically been limited by availability of instrumentation. This talk shows how to make inexpensive green diode-pumped solid-state (DPSS) lasers easily tunable for efficient, selective excitation of I2. Miniature fiber-optic spectrometers then enable rotationally resolved fluorescence spectroscopy up to v" = 42 near 900 nm with acquisition times of less than one minute. DPSS lasers are also versatile excitation sources for vibrational Raman spectroscopy, which is another common exercise that has been limited by lack of proper instrumentation in the teaching laboratory. This talk shows how to construct a simple accessory for commercial fluorimeters to record vibrational Raman spectra and depolarization ratios for CCl4 and C2Cl4 as part of a lab exercise featuring molecular symmetry.

Preliminary study of laser welding for aortic dissection in a porcine model using a diode laser with indocyanine green.

PubMed

Fujita, Masanori; Morimoto, Yuji; Ohmori, Sayaka; Usami, Noriko; Arai, Tsunenori; Maehara, Tadaaki; Kikuchi, Makoto

2003-01-01

The objective of this study was to determine whether a dissected aorta could be welded by a diode laser with a solder using an in vitro porcine aortic dissection model. Porcine aortic strips were dissected into two flaps and the dissected faces were immersed in a solution of indocyanine green. The two flaps were pressed at 0.2 kg/cm2 with contact between the two immersed faces. The pressed flaps were irradiated with a diode laser (810 nm) at intensities of 170-425 W/cm2 for 8 seconds. The welded flaps were studied by light microscopy and the adhesive strengths were measured. The irradiated flaps were successfully welded. The breaking stress, the maximum stress recorded in a stress-strain curve, increased with increase in irradiation intensity up to 396 W/cm2 (2.7 x 10(2) mmHg) and decreased when the intensity reached 425 W/cm2. In the specimen irradiated at 396 W/cm2, the welded faces showed continuous fusion of elastin layers, while some voids were seen between the welded faces in the specimen irradiated at 425 W/cm2. The dissected porcine aortas were successfully welded using a laser with solder. The results suggest that the welded aorta can bear physiological blood pressure. Copyright 2003 Wiley-Liss, Inc.

Experimental diode laser-assisted microvascular anastomosis.

PubMed

Reali, U M; Gelli, R; Giannotti, V; Gori, F; Pratesi, R; Pini, R

1993-05-01

An experimental study to evaluate a diode-laser approach to microvascular end-to-end anastomoses is reported. Studies were carried out on the femoral arteries and veins of Wistar rats, and effective welding of vessel tissue was obtained at low laser power, by enhancing laser absorption with indocyanine green (Cardio-green) solution. The histologic and surgical effects of this laser technique were examined and compared with those of conventional microvascular sutured anastomoses.

Properties of Au/Copper oxide nanocomposite prepared by green laser irradiation of the mixture of individual suspensions

NASA Astrophysics Data System (ADS)

Aazadfar, Parvaneh; Solati, Elmira; Dorranian, Davoud

2018-04-01

The fundamental wavelength of a Q-switched pulsed Nd:YAG laser was employed to produce Au and copper oxide nanoparticles via pulsed laser ablation method in water. Different volumetric ratio of nanoparticles were mixed and irradiated by the second harmonic pulses of the Nd:YAG laser to prepare Au/Copper oxide nanocomposite. The experimental investigation was dedicated to study the properties of Au/Copper oxide nanocomposite as a function of volumetric ratio of Au nanoparticles and copper oxide nanoparticles. Nanocomposites of Au and copper oxide were found almost spherical in shape. Adhesion of spherical nanostructure in Au/Copper oxide nanocomposites was decreased with increasing the concentration of Au nanoparticles. Crystalline phase of the Au/Copper oxide nanocomposites differs with the change in the volumetric ratio of Au and copper oxide nanoparticles. The intensity of surface plasmon resonance of Au nanoparticles was decreased after irradiation. Au/Copper oxide nanocomposites suspensions have emissions in the visible range. Results reveal that green laser irradiation of nanoparticle suspensions is an appropriate method to synthesize Au based nanocomposites with controlled composition and size.

Enhanced green fluorescent protein in optofluidic Fabry-Perot microcavity to detect laser induced temperature changes in a bacterial culture

NASA Astrophysics Data System (ADS)

Lahoz, F.; Martín, I. R.; Walo, D.; Freire, R.; Gil-Rostra, J.; Yubero, F.; Gonzalez-Elipe, A. R.

2017-09-01

Thermal therapy using laser sources can be used in combination with other cancer therapies to eliminate tumors. However, high precision temperature control is required to avoid damage in healthy surrounding tissues. Therefore, in order to detect laser induced temperature changes, we have used the fluorescence signal of the enhanced Green Fluorescent Protein (eGFP) over-expressed in an E. coli bacterial culture. For that purpose, the bacteria expressing eGFP are injected in a Fabry-Perot (FP) optofluidic planar microcavity. In order to locally heat the bacterial culture, external infrared or ultraviolet lasers were used. Shifts in the wavelengths of the resonant FP modes are used to determine the temperature increase as a function of the heating laser pump power. Laser induced local temperature increments up to 6-7 °C were measured. These results show a relatively easy way to measure laser induced local temperature changes using a FP microcavity and using eGFP as a molecular probe instead of external nanoparticles, which could damage/alter the cell. Therefore, we believe that this approach can be of interest for the study of thermal effects in laser induced thermal therapies.

Vaporize, anatomically vaporize or enucleate the prostate? The flexible use of the GreenLight laser.

PubMed

Cindolo, Luca; Ruggera, Lorenzo; Destefanis, Paolo; Dadone, Claudio; Ferrari, Giovanni

2017-03-01

GreenLight laser has gained increasing acceptance as a less invasive treatment for lower urinary tract symptoms due to benign prostatic hyperplasia (BPH/LUTS). Three surgical options were developed: standard photovaporization (PVP), anatomical PVP and GreenLight enucleation of prostate (GreenLEP); however, literature lacks a direct comparison among the procedures. Aim of the present study is to compare the three techniques in a multicentre series of patients. Data were collected from consecutive patients with indication to surgical management of BPH/LUTS in five institutions. Patients underwent standard PVP, anatomical PVP or GreenLEP according to surgeon preferences. Standard parameters associated with transurethral prostate surgery were documented prior surgery and during the follow-up. Patients' perception of improvement was measured using a single-item scale. Early (within first 30 post-operative days) and delayed post-operative complications were recorded. Descriptive statistics, univariate and multivariate analysis were used. We evaluate 367 consecutive patients (mean age 69.1 years). Median prostate size and PSA were 68 ml (IQR 50-90) and 2.8 ng/ml (IQR 1.7-4.3), respectively. The median operative time and applied energy were 60 min (IQR 45-75) and 250 kJ (IQR 160-364). Catheterization time and median post-operative stay were 1 and 2 days. No patient was transfused. The overall median Q max values increased for 8-19 ml/s (p < 0.05), median International Prostate Symptoms Score decreased from 24 to 7 (p < 0.05). A total of 7.4% urinary retention, 33.4% bothersome storage symptoms, 2.5% short-term stress incontinence were recorded. Three heart attacks, one pulmonary embolism and one death occurred. Prostate volume was a predictive factor for post-operative storage symptoms (p = 0.049). Nine percentage of patients experienced long-term complications (4, 0.9 and 0.9% of urethral stricture, bladder neck contracture and prostatic fossa sclerosis

Indocyanine green-augmented diode laser therapy of telangiectatic leg veins: a randomized controlled proof-of-concept trial.

PubMed

Klein, Annette; Bäumler, Wolfgang; Koller, Michael; Shafirstein, Gal; Kohl, Elisabeth A; Landthaler, Michael; Babilas, Philipp

2012-07-01

Telangiectatic leg veins, which affect about 40-50% of adults, represent a frequent cosmetic rather than a medical problem. Besides sclerotherapy, various laser devices are common treatment options. However, complete clearance rates can only be achieved in a small number of patients. In this proof-of-concept study, the safety and efficacy of indocyanine green (ICG)-augmented diode laser therapy (808 nm) was evaluated for the treatment of telangiectatic leg veins. ICG (2 mg/kg body weight) was intravenously administered in 15 female patients (skin type II to III) with telangiectatic leg veins (measuring between 0.25 and 3 mm in diameter). Immediately after ICG injection, diode laser pulses with different radiant exposures (50-110 J/cm(2)) were applied as one single treatment. Safety and efficacy were assessed 1 and 3 months after treatment by a blinded investigator and the patient. Treatments with the pulsed dye laser (PDL) and the diode laser without ICG served as reference therapies. The safety of ICG application and diode laser treatment was excellent in all patients with no persisting side effects. Vessel clearance was dose-dependent. Diode laser treatment at radiant exposures between 100 and 110 J/cm(2) resulted in good vessel clearance, which even improved to excellent after the application of double pulses. Diode laser therapy without ICG and PDL treatment induced poor to moderate clearance of telangiectatic leg veins. ICG-augmented diode laser therapy has proved to be a safe and effective treatment option for telangiectatic leg veins. Copyright © 2012 Wiley Periodicals, Inc.

Green laser light activates the inner ear

NASA Astrophysics Data System (ADS)

Wenzel, Gentiana I.; Balster, Sven; Zhang, Kaiyin; Lim, Hubert H.; Reich, Uta; Massow, Ole; Lubatschowski, Holger; Ertmer, Wolfgang; Lenarz, Thomas; Reuter, Guenter

2009-07-01

The hearing performance with conventional hearing aids and cochlear implants is dramatically reduced in noisy environments and for sounds more complex than speech (e. g. music), partially due to the lack of localized sensorineural activation across different frequency regions with these devices. Laser light can be focused in a controlled manner and may provide more localized activation of the inner ear, the cochlea. We sought to assess whether visible light with parameters that could induce an optoacoustic effect (532 nm, 10-ns pulses) would activate the cochlea. Auditory brainstem responses (ABRs) were recorded preoperatively in anesthetized guinea pigs to confirm normal hearing. After opening the bulla, a 50-μm core-diameter optical fiber was positioned in the round window niche and directed toward the basilar membrane. Optically induced ABRs (OABRs), similar in shape to those of acoustic stimulation, were elicited with single pulses. The OABR peaks increased with energy level (0.6 to 23 μJ/pulse) and remained consistent even after 30 minutes of continuous stimulation at 13 μJ, indicating minimal or no stimulation-induced damage within the cochlea. Our findings demonstrate that visible light can effectively and reliably activate the cochlea without any apparent damage. Further studies are in progress to investigate the frequency-specific nature and mechanism of green light cochlear activation.

Miniature solid-state lasers for pointing, illumination, and warning devices

NASA Astrophysics Data System (ADS)

Brown, D. C.; Singley, J. M.; Yager, E.; Kowalewski, K.; Lotito, B.; Guelzow, J.; Hildreth, J.; Kuper, J. W.

2008-04-01

In this paper we review the current status of and progress towards higher power and more wavelength diverse diode-pumped solid-state miniature lasers. Snake Creek Lasers now offers unprecedented continuous wave (CW) output power from 9.0 mm and 5.6 mm TO type packages, including the smallest green laser in the world, the MicroGreen TM laser, and the highest density green laser in the world, the MiniGreen TM laser. In addition we offer an infrared laser, the MiniIR TM, operating at 1064 nm, and have just introduced a blue Mini laser operating at 473 nm in a 9.0 mm package. Recently we demonstrated over 1 W of output power at 1064 nm from a 12 mm TO type package, and green output power from 300-500 mW from the same 12 mm package. In addition, the company is developing a number of other innovative new miniature CW solid-state lasers operating at 750 nm, 820 nm, 458 nm, and an eye-safe Q-switched laser operating at 1550 nm. We also review recently demonstrated combining volume Bragg grating (VBG) technology has been combined with automatic power control (APC) to produce high power MiniGreen TM lasers whose output is constant to +/- 10 % over a wide temperature range, without the use of a thermoelectric cooler (TEC). This technology is expected to find widespread application in military and commercial applications where wide temperature operation is particularly important. It has immediate applications in laser pointers, illuminators, and laser flashlights, and displays.

Detection of Minerals in Green Leafy Vegetables Using Laser Induced Breakdown Spectroscopy

NASA Astrophysics Data System (ADS)

Shukla, P.; Kumar, R.; Raib, A. Kumar

2016-11-01

The distribution of minerals in different green leafy vegetables, such as spinach, chenopodium, chickpea, mustard, and fenugreek, was calculated using laser induced breakdown spectroscopy (LIBS). LIBS can provide an easy, reliable, efficient, low-cost, and in situ chemical analysis with a reasonable precision. In situ LIBS spectra in the range 200-500 nm were carried out using fresh leaves and leaves in the pellet form. As the spectra suggest, magnesium and calcium are present in each vegetable; however, the amount of them varies. It is observed that the amount of iron is maximal in spinach. The nutrition value of the plants was analyzed, and it was revealed that they are low in calories and fat and high in protein, fiber, iron, calcium, and phytochemicals.

New technique for laryngotracheal mucosa transplantation. 'Stamp' welding using indocyanine green dye and albumin interaction with diode laser.

PubMed

Wang, Z; Pankratov, M M; Gleich, L L; Rebeiz, E E; Shapshay, S M

1995-07-01

To investigate (1) the possibility of survival of free mucosa "stamp" grafts fixed in the airway with a new technique using indocyanine green-dyed albumin solder activated with a diode laser and (2) the degree of improvement of wound healing in the airway by applying modified microskin transplantation techniques from burn surgery to cover a relatively large wound with a few small pieces of mucosa anchored in place with the previously mentioned technique. Three (one control and two experimental) rectangular (10 x 8 mm) wounds in tracheal mucosa were produced in four experimental animals (dogs) using a carbon dioxide laser. The control wound was left uncovered. In the first experimental wound, a mucosal flap was raised and then fixed in place by a trapdoor flap method. In the second experimental wound, two small (each 2 x 3 mm) autogenous mucosa grafts were anchored onto the surface with indocyanine green-dyed albumin activated with an 810-nm diode laser. Histomorphologically, the postoperative results from three wounds were compared. The experimental wounds were completely covered by regenerated squamous cells in 1 week and by ciliated epithelium in 2 weeks after the operation despite the discrepancy in size of the graft to wound area (1:6.7) covered with the stamp mucosa. No thermal damage from the diode laser was noted in the second experimental wounds. In the control wounds, no coverage was observed at 1 week, and only squamous cells were noted 2 weeks postoperatively. All the wounds had normal ciliated epithelium coverage at 4 weeks. Transplanted stamp grafts provided similar or better healing than trapdoor flap transplants. This new technique made endoscopic mucosal grafting possible and offers a potential breakthrough in the management of laryngotracheal stenosis.

Comparative analysis of quantum cascade laser modeling based on density matrices and non-equilibrium Green's functions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lindskog, M., E-mail: martin.lindskog@teorfys.lu.se; Wacker, A.; Wolf, J. M.

2014-09-08

We study the operation of an 8.5 μm quantum cascade laser based on GaInAs/AlInAs lattice matched to InP using three different simulation models based on density matrix (DM) and non-equilibrium Green's function (NEGF) formulations. The latter advanced scheme serves as a validation for the simpler DM schemes and, at the same time, provides additional insight, such as the temperatures of the sub-band carrier distributions. We find that for the particular quantum cascade laser studied here, the behavior is well described by simple quantum mechanical estimates based on Fermi's golden rule. As a consequence, the DM model, which includes second order currents,more » agrees well with the NEGF results. Both these simulations are in accordance with previously reported data and a second regrown device.« less

Red-green-blue (RGB) light generator using tapered fiber pumped with a frequency-doubled Yb-fiber laser.

PubMed

Rusu, M; Kivistö, Samuli; Gawith, C; Okhotnikov, O

2005-10-17

We report on successful realization of a picosecond visible-continuum source embedding a single mode fiber taper. The output of ytterbium mode-locked fiber laser was frequency doubled in a periodically-polled lithium niobate (PPLN) crystal to produce green pump light. Spectral brightness of the white light generated in the tapered fiber was improved by limiting the broadening just to the visible wavelengths. The influence of taper parameters, particularly the dispersion, on white light spectrum has been studied.

Red-green-blue (RGB) light generator using tapered fiber pumped with a frequency-doubled Yb-fiber laser

NASA Astrophysics Data System (ADS)

Rusu, M.; Kivistö, Samuli; Gawith, C. B. E.; Okhotnikov, O. G.

2005-10-01

We report on successful realization of a picosecond visible-continuum source embedding a single mode fiber taper. The output of ytterbium mode-locked fiber laser was frequency doubled in a periodically-polled lithium niobate (PPLN) crystal to produce green pump light. Spectral brightness of the white light generated in the tapered fiber was improved by limiting the broadening just to the visible wavelengths. The influence of taper parameters, particularly the dispersion, on white light spectrum has been studied.

Potential Elevation Biases for Laser Altimeters from Subsurface Scattered Photons: Laboratory and Model Exploration of Green Light Scattering in Snow

NASA Astrophysics Data System (ADS)

Greeley, A.; Neumann, T.; Markus, T.; Kurtz, N. T.; Cook, W. B.

2015-12-01

Existing visible light laser altimeters such as MABEL (Multiple Altimeter Beam Experimental Lidar) - a single photon counting simulator for ATLAS (Advanced Topographic Laser Altimeter System) on NASA's upcoming ICESat-2 mission - and ATM (Airborne Topographic Mapper) on NASA's Operation IceBridge mission provide scientists a view of Earth's ice sheets, glaciers, and sea ice with unprecedented detail. Precise calibration of these instruments is needed to understand rapidly changing parameters like sea ice freeboard and to measure optical properties of surfaces like snow covered ice sheets using subsurface scattered photons. Photons travelling into snow, ice, or water before scattering back to the altimeter receiving system (subsurface photons) travel farther and longer than photons scattering off the surface only, causing a bias in the measured elevation. We seek to identify subsurface photons in a laboratory setting using a flight-tested laser altimeter (MABEL) and to quantify their effect on surface elevation estimates for laser altimeter systems. We also compare these estimates with previous laboratory measurements of green laser light transmission through snow, as well as Monte Carlo simulations of backscattered photons from snow.

Antibacterial photodynamic therapy with 808-nm laser and indocyanine green on abrasion wound models

NASA Astrophysics Data System (ADS)

Topaloglu, Nermin; Güney, Melike; Yuksel, Sahru; Gülsoy, Murat

2015-02-01

Infections with pathogens could cause serious health problems, such as septicemia and subsequent death. Some of these deaths are caused by nosocomial, chronic, or burn-related wound infections. Photodynamic therapy (PDT) can be useful for the treatment of these infections. Our aim was to investigate the antibacterial effect of indocyanine green (ICG) and 808-nm laser on a rat abrasion wound model infected with the multidrug resistant Staphylococcus aureus strain. Abrasion wounds were infected with a multidrug resistant clinical isolate of S. aureus. ICG concentrations of 500, 1000, and 2000 μg/ml were applied with a 450 J/cm2 energy dose. Temperature change was monitored by a thermocouple system. The remaining bacterial burden was determined by the serial dilution method after each application. Wounds were observed for 11 days posttreatment. The recovery process was assessed macroscopically. Tissue samples were also examined histologically by hematoxylin-eosin staining. Around a 90% reduction in bacterial burden was observed after PDT applications. In positive control groups (ICG-only and laser-only groups), there was no significant reduction. The applied energy dose did not cause any thermal damage to the target tissue or host environment. Results showed that ICG together with a 808-nm laser might be a promising antibacterial method to eliminate infections in animals and accelerate the wound-healing process.

Lunar laser ranging in infrared at the Grasse laser station

NASA Astrophysics Data System (ADS)

Courde, C.; Torre, J. M.; Samain, E.; Martinot-Lagarde, G.; Aimar, M.; Albanese, D.; Exertier, P.; Fienga, A.; Mariey, H.; Metris, G.; Viot, H.; Viswanathan, V.

2017-06-01

For many years, lunar laser ranging (LLR) observations using a green wavelength have suffered an inhomogeneity problem both temporally and spatially. This paper reports on the implementation of a new infrared detection at the Grasse LLR station and describes how infrared telemetry improves this situation. Our first results show that infrared detection permits us to densify the observations and allows measurements during the new and the full Moon periods. The link budget improvement leads to homogeneous telemetric measurements on each lunar retro-reflector. Finally, a surprising result is obtained on the Lunokhod 2 array which attains the same efficiency as Lunokhod 1 with an infrared laser link, although those two targets exhibit a differential efficiency of six with a green laser link.

Direct synthesis of graphitic mesoporous carbon from green phenolic resins exposed to subsequent UV and IR laser irradiations

PubMed Central

Sopronyi, Mihai; Sima, Felix; Vaulot, Cyril; Delmotte, Luc; Bahouka, Armel; Matei Ghimbeu, Camelia

2016-01-01

The design of mesoporous carbon materials with controlled textural and structural features by rapid, cost-effective and eco-friendly means is highly demanded for many fields of applications. We report herein on the fast and tailored synthesis of mesoporous carbon by UV and IR laser assisted irradiations of a solution consisting of green phenolic resins and surfactant agent. By tailoring the UV laser parameters such as energy, pulse repetition rate or exposure time carbon materials with different pore size, architecture and wall thickness were obtained. By increasing irradiation dose, the mesopore size diminishes in the favor of wall thickness while the morphology shifts from worm-like to an ordered hexagonal one. This was related to the intensification of phenolic resin cross-linking which induces the reduction of H-bonding with the template as highlighted by 13C and 1H NMR. In addition, mesoporous carbon with graphitic structure was obtained by IR laser irradiation at room temperature and in very short time periods compared to the classical long thermal treatment at very high temperatures. Therefore, the carbon texture and structure can be tuned only by playing with laser parameters, without extra chemicals, as usually required. PMID:28000781

RGB and white-emitting organic lasers on flexible glass.

PubMed

Foucher, C; Guilhabert, B; Kanibolotsky, A L; Skabara, P J; Laurand, N; Dawson, M D

2016-02-08

Two formats of multiwavelength red, green and blue (RGB) laser on mechanically-flexible glass are demonstrated. In both cases, three all-organic, vertically-emitting distributed feedback (DFB) lasers are assembled onto a common ultra-thin glass membrane substrate and fully encapsulated by a thin polymer overlayer and an additional 50 µm-thick glass membrane in order to improve the performance. The first device format has the three DFB lasers sitting next to each other on the glass substrate. The DFB lasers are simultaneously excited by a single overlapping optical pump, emitting spatially separated red, green and blue laser output with individual thresholds of, respectively, 28 µJ/cm(2), 11 µJ/cm(2) and 32 µJ/cm(2) (for 5 ns pump pulses). The second device format has the three DFB lasers, respectively the red, green and blue laser, vertically stacked onto the flexible glass. This device format emits a white laser output for an optical pump fluence above 42 µJ/cm(2).

Large laser projection displays utilizing all-solid-state RGB lasers

NASA Astrophysics Data System (ADS)

Xu, Zuyan; Bi, Yong

2005-01-01

RGB lasers projection displays have the advantages of producing large color triangle, high color saturation and high image resolution. In this report, with more than 4W white light synthesized by red (671nm), green (532nm) and blue (473nm) lasers, a RGB laser projection display system based on diode pumped solid-state lasers is developed and the performance of brilliant and vivid DVD dynamitic pictures on 60 inch screen is demonstrated.

Comparative study between thulium laser (Tm: YAG) 150W and greenlight laser (LBO:ND-YAG) 120W for the treatment of benign prostatic hyperpplasia: Short-term efficacy and security.

PubMed

Palmero-Martí, J L; Panach-Navarrete, J; Valls-González, L; Ganau-Ituren, A; Miralles-Aguado, J; Benedicto-Redón, A

2017-04-01

To compare the results of efficacy and safety of Thulium laser 150W against Greenlight laser 120W in the treatment of short term benign prostatic hyperplasia (12 months after surgery). This is a retrospective observational study where men who underwent the surgical technique of prostate vaporization over a period of four years in our center are included. The homogeneity of the sample was checked, and postoperative complications (acute urinary retention, reentry, need for transfusion), failures per year of surgery (reoperation, peak flow <15ml/sec, no improvement in comparing the I-PSS), and decreased PSA were compared a year after surgery. A bivariate analysis using Chi-square and t-Student was carried out. 116 patients were treated with thulium and 118 with green laser. The sample was homogeneous for preoperative variables (P>.05). No differences in complications were observed: in urine acute retention, 4.3% with thulium and 6.8% with green laser (P=.41); in readmissions, 2.6% with thulium and 1.7% with green laser (P=.68); in need for transfusion, 2.6% with thulium and 0% with green laser (P=.12). No differences were observed in the percentage of patients reoperation (1.7% in the group of thulium, 5.1% in the green laser, P=.28); or in individuals with Qmáx less than 15ml/sec (6.9% with thulium, 6.77% with green laser, P=.75), or in the absence of improvement in the IPSS (5, 2% with thulium, 3.4% with green laser, P=.65). There was also no difference in the levels of PSA in ng/mL a year after surgery: with thulium 2.78±2.09 and with green laser 1.83±1.48 (P=.75). Prostate vaporization with thulium laser 150W is comparable to that made with green laser 120W for the treatment of lower urinary tract symptoms caused by BPH, being both effective and safe techniques to 12 months after surgery. Future prospective randomized studies are needed to confirm this conclusion on both techniques. Copyright © 2016 AEU. Publicado por Elsevier España, S.L.U. All rights

Quality of marital life in Korean patients with spondyloarthropathy.

PubMed

Yim, S Y; Lee, I Y; Lee, J H; Jun, J B; Kim, T H; Bae, S C; Yoo, D H

2003-09-01

The objectives of this study were to assess the quality of marital life (QML) in patients with spondyloarthropathy (SpA) in Korea and to identify possible gender differences in QML in patients with SpA. This was a case-control study at the outpatient unit of a tertiary care medical centre. Subjects were the patient group, composed of 47 married patients with SpA, and a comparison group composed of 47 healthy married adults with similar demographic characteristics. QML was measured using the Marital Satisfaction Inventory, Revised. As a result, QML was similar for both the male patients and the healthy men. However, the female patients had higher scores on the global distress scale (59.8 +/- 6.3 vs. 53.8 +/- 5.6, P=0.021) and the aggression scale (50.5 +/- 7.9 vs. 44.3 +/- 5.4, P=0.016) than the female comparison group. At the same time, the female patients demonstrated higher scores on the global distress scale (59.8 +/- 6.3 vs. 54.7 +/- 7.2, P=0.035) than the male patients. In conclusion, QML in Korean males with SpA was not greatly different from that of the male comparison group. However, QML in the female patients was characterised by higher global distress and a higher probability of aggression from their partner, but no significant sexual dissatisfaction.

Laser And Nonlinear Optical Materials For Laser Remote Sensing

NASA Technical Reports Server (NTRS)

Barnes, Norman P.

2005-01-01

NASA remote sensing missions involving laser systems and their economic impact are outlined. Potential remote sensing missions include: green house gasses, tropospheric winds, ozone, water vapor, and ice cap thickness. Systems to perform these measurements use lanthanide series lasers and nonlinear devices including second harmonic generators and parametric oscillators. Demands these missions place on the laser and nonlinear optical materials are discussed from a materials point of view. Methods of designing new laser and nonlinear optical materials to meet these demands are presented.

5-nJ Femtosecond Ti3+:sapphire laser pumped with a single 1 W green diode

NASA Astrophysics Data System (ADS)

Muti, Abdullah; Kocabas, Askin; Sennaroglu, Alphan

2018-05-01

We report a Kerr-lens mode-locked, extended-cavity femtosecond Ti3+:sapphire laser directly pumped at 520 nm with a 1 W AlInGaN green diode. To obtain energy scaling, the short x-cavity was extended with a q-preserving multi-pass cavity to reduce the pulse repetition rate to 5.78 MHz. With 880 mW of incident pump power, we obtained as high as 90 mW of continuous-wave output power from the short cavity by using a 3% output coupler. In the Kerr-lens mode-locked regime, the extended cavity produced nearly transform-limited 95 fs pulses at 776 nm. The resulting energy and peak power of the pulses were 5.1 nJ and 53 kW, respectively. To our knowledge, this represents the highest pulse energy directly obtained to date from a mode-locked, single-diode-pumped Ti3+:sapphire laser.

Indocyanine green-augmented diode laser therapy vs. long-pulsed Nd:YAG (1064 nm) laser treatment of telangiectatic leg veins: a randomized controlled trial.

PubMed

Klein, A; Buschmann, M; Babilas, P; Landthaler, M; Bäumler, W

2013-08-01

Telangiectatic leg veins (TLV) represent a common cosmetic problem. Near infrared lasers have been widely used in treatment because of their deeper penetration into the dermis, but with varying degrees of success, particularly because of different vessel diameters. Indocyanine green (ICG)-augmented diode laser treatment (ICG+DL) may present an alternative treatment option. This trial evaluates the efficacy of ICG+DL in the treatment of TLV and compares the safety and efficacy of therapy with the standard treatment, the long-pulsed neodymium-doped yttrium aluminium garnet (Nd:YAG) laser. In a prospective randomized controlled clinical trial, 29 study participants with TLV were treated with a Nd:YAG laser (λem = 1064 nm, 160-240 J cm(-2) , 65-ms pulse duration, 5-mm spot size) and ICG+DL (λem = 810 nm, 60-110 J cm(-2) , 48-87-ms pulse duration, 6-mm spot size; total ICG dose 4 mg kg(-1) ) in a side-by-side comparison in one single treatment setting that included histological examination in four participants. Two blinded investigators and the participants assessed clearance rate, cosmetic appearance and adverse events up to 3 months after treatment. According to both the investigators' and participants' assessment, clearance rates were significantly better after ICG+DL therapy than after Nd:YAG laser treatment (P < 0·05). On a 10-point scale indicating pain during treatment, participants rated ICG+DL therapy to be more painful (6·1 ± 2·0) than Nd:YAG laser (5·4 ± 2·0). ICG+DL therapy represents a new and promising treatment modality for TLV, with high clearance rates and a very good cosmetic outcome after one single treatment session. © 2013 British Association of Dermatologists.

Visualisation of the distributions of melanin and indocyanine green in biological tissues

DOE Office of Scientific and Technical Information (OSTI.GOV)

Genina, E A; Fedosov, I V; Bashkatov, A N

2008-03-31

A double-wavelength laser scanning microphotometer with the high spectral and spatial resolutions is developed for studying the distribution of endogenic and exogenic dyes in biological tissues. Samples of hair and skin biopsy with hair follicles stained with indocyanine green are studied. The spatial distribution of indocyanine green and melanin in the biological tissue is determined from the measured optical transmittance. (laser biology)

Intracavity KTP optical parametric oscillator driven by a KLM Nd:GGG laser with a single AO modulator

NASA Astrophysics Data System (ADS)

Chu, Hongwei; Zhao, Shengzhi; Yang, Kejian; Zhao, Jia; Li, Yufei; Li, Tao; Li, Guiqiu; Li, Dechun; Qiao, Wenchao

2015-05-01

An intracavity KTiOPO4 (KTP) optical parametric oscillator (OPO) pumped by a Kerr lens mode-locking (KLM) Nd:GGG laser near 1062 nm with a single AO modulator was realized for the first time. The mode-locking pulses of the signal wave were obtained with a short duration of subnanosecond and a repetition rate of several kilohertz (kHz). Under a diode pump power of 8.25 W, a maximum output power of 104 mW at signal wavelength near 1569 nm was obtained at a repetition rate of 2 kHz. The highest pulse energy and peak power were estimated to be 80 μJ and 102 kW at a repetition rate of 1 kHz, respectively. The shortest pulse duration was measured to be 749 ps. By considering the Gaussian spatial distribution of the photon density and the Kerr-lens effect in the gain medium, a set of the coupled rate equations for QML intracavity optical parametric oscillator are given and the numerical simulations are basically fitted with the experimental results.

Lasers '92; Proceedings of the International Conference on Lasers and Applications, 15th, Houston, TX, Dec. 7-10, 1992

NASA Technical Reports Server (NTRS)

Wang, Charles P. (Editor)

1993-01-01

Papers from the conference are presented, and the topics covered include the following: x-ray lasers, excimer lasers, chemical lasers, high power lasers, blue-green lasers, dye lasers, solid state lasers, semiconductor lasers, gas and discharge lasers, carbon dioxide lasers, ultrafast phenomena, nonlinear optics, quantum optics, dynamic gratings and wave mixing, laser radar, lasers in medicine, optical filters and laser communication, optical techniques and instruments, laser material interaction, and industrial and manufacturing applications.

A Treatment of Amblyopia Using Laser Diodes

NASA Astrophysics Data System (ADS)

Wang, Di; Wang, Yi-Ding; Liu, Bing-Chun

2000-04-01

We propose the treatment of amblyopia using yellow-green laser diodes. There are amblyopia children in excess of fifty million in the world. Because the causative agent of amblyopia hasn't been well understood,only roughly considered to be concerned with visual sense cell, optic nerve network and function of nerve center, no appropriate treatment is found up to date. The vision of person is determined by the center hollow region of retina, where there are three kinds of cone cell. The corresponding peak wavelength in absorption spectrum locates 447nm (blue light), 532nm (green light) and 565nm (yellow light), respectively. When stimulated by white light, excited degree of three kinds of cone cell are identical,or yellow-green light, to which person eye is most sensitive, will significantly takes effects. Therefore the yellow-green laser diode is suitable for treating amblyopia. The weak laser, namely laser power less than mW order of magnitude, shows curative by stimulating bion tissue. When stimulating light power density is less than 0.001W/cm, the compounding speed of nucleic acid DNA is significantly increased. The growth rate of cell, activity of enzyme, content of hemoglobin and the growth of blood vessel, are all increased. However, it's key to control the dose of light. When the dose transcend some value, a inhibition will occur. The little dose of weak laser treatment can be accumulated with a parabolic characteristics, that is the weak laser generate bion response stengthening gradually versus time. Then it will weaken gradually after the peak. When the treatment duration is longer than a certain time, a inhibition also takes place. A suggested theraphy is characterized by little dose and short treatment course. In a conclusion, the yellow-green laser diode should be used for the treatment of amblyopia. The little dose and short treatment couse are to be adopted. Key words:treatment amblyopia laser diode

Efficient yellow-green light generation at 561 nm by frequency-doubling of a QD-FBG laser diode in a PPLN waveguide.

PubMed

Fedorova, Ksenia A; Sokolovskii, Grigorii S; Khomylev, Maksim; Livshits, Daniil A; Rafailov, Edik U

2014-12-01

A compact high-power yellow-green continuous wave (CW) laser source based on second-harmonic generation (SHG) in a 5% MgO doped periodically poled congruent lithium niobate (PPLN) waveguide crystal pumped by a quantum-dot fiber Bragg grating (QD-FBG) laser diode is demonstrated. A frequency-doubled power of 90.11 mW at the wavelength of 560.68 nm with a conversion efficiency of 52.4% is reported. To the best of our knowledge, this represents the highest output power and conversion efficiency achieved to date in this spectral region from a diode-pumped PPLN waveguide crystal, which could prove extremely valuable for the deployment of such a source in a wide range of biomedical applications.

MgO:PPLN frequency doubling optical chips for green light generation: from lab research to mass production

NASA Astrophysics Data System (ADS)

Xu, Chang-Qing; Gan, Yi; Sun, Jian

2012-03-01

Laser displays require red, green and blue (RGB) laser sources each with a low-cost, a high wall-plug efficiency, and a small size. However, semiconductor chips that directly emit green light with sufficient power and efficiency are not currently available on the market. A practical solution to the "green" bottleneck is to employ diode pumped solid state laser (DPSSL) technology, in which a frequency doubling crystal is used. In this paper, recent progress of MgO doped periodically poled lithium niobate (MgO:PPLN) frequency doubling optical chips will be presented. It is shown that MgO:PPLN can satisfy all of the requirements for laser displays and is ready for mass production.

All solid-state high power visible laser

NASA Technical Reports Server (NTRS)

Grossman, William M.

1993-01-01

The overall objective of this Phase 2 effort was to develop and deliver to NASA a high repetition rate laser-diode-pumped solid-state pulsed laser system with output in the green portion of the spectrum. The laser is for use in data communications, and high efficiency, short pulses, and low timing jitter are important features. A short-pulse 1 micron laser oscillator, a new multi-pass amplifier to boost the infrared power, and a frequency doubler to take the amplified infrared pulsed laser light into the green. This produced 1.5 W of light in the visible at a pulse repetition rate of 20 kHz in the laboratory. The pulses have a full-width at half maximum of near 1 ns. The results of this program are being commercialized.

Comparison of the photothermal effects of 808nm gold nanorod and indocyanine green solutions using an 805nm diode laser

NASA Astrophysics Data System (ADS)

Hasanjee, Aamr M.; Zhou, Feifan; West, Connor; Silk, Kegan; Doughty, Austin; Bahavar, Cody F.; Chen, Wei R.

2016-03-01

Non-invasive laser immunotherapy (NLIT) is a treatment method for metastatic cancer which combines noninvasive laser irradiation with immunologically modified nanostructures to ablate a primary tumor and induce a systemic anti-tumor response. To further expand the development of NLIT, two different photosensitizing agents were compared: gold nanorods (GNR) with an optical absorption peak of 808 nm and indocyanine green (ICG) with an optical absorption peak of ~800 nm. Various concentrations of GNR and ICG solutions were irradiated at different power densities using an 805 nm diode laser, and the temperature of the solutions was monitored during irradiation using a thermal camera. For comparison, dye balls made up of a 1:1 volume ratio of gel solution to GNR or ICG solution were placed in phantom gels and were then irradiated using the 805 nm diode laser to imitate the effect of laser irradiation on in vivo tumors. Non-invasive laser irradiation of GNR solution for 2 minutes resulted in a maximum increase in temperature by 31.8 °C. Additionally, similar irradiation of GNR solution dye ball within phantom gel for 10 minutes resulted in a maximum temperature increase of 8.2 °C. Comparatively, non-invasive laser irradiation of ICG solution for 2 minutes resulted in a maximum increase in temperature by 28.0 °C. Similar irradiation of ICG solution dye ball within phantom gel for 10 minutes yielded a maximum temperature increase of only 3.4 °C. Qualitatively, these studies showed that GNR solutions are more effective photosensitizing agents than ICG solution.

Solid-state YVO4/Nd:YVO4/KTP green laser system for the generation of subnanosecond pulses with adjustable kilohertz repetition rate.

PubMed

Zhang, Haijuan; Zhao, Shengzhi; Yang, Kejian; Li, Guiqiu; Li, Dechun; Zhao, Jia; Wang, Yonggang

2013-09-20

A solid-state green laser generating subnanosecond pulses with adjustable kilohertz repetition rate is presented. This pulse laser system is composed of a Q-switched and mode-locked YVO(4)/Nd:YVO(4)/KTP laser simultaneously modulated by an electro-optic (EO) modulator and a central semiconductor saturable absorption mirror. Because the repetition rate of the Q-switched envelope in this laser depends on the modulation frequency of the EO modulator, so long as the pulsewidth of the Q-switched envelope is shorter than the cavity roundtrip transmit time, i.e., the time interval of two neighboring mode-locking pulses, only one mode-locking pulse exists underneath a Q-switched envelope, resulting in the generation of subnanosecond pulses with kilohertz repetition rate. The experimental results show that the pulsewidth of subnanosecond pulses decreases with increasing pump power and the shortest pulse generated at 1 kHz was 450 ps with pulse energy as high as 252 μJ, corresponding to a peak power of 560 kW. In addition, this laser was confirmed to have high stability, and the pulse repetition rate could be freely adjusted from 1 to 4 kHz.

Airborne Laser Systems Testing and Analysis (essals et analyse des systemes laser embarques)

DTIC Science & Technology

2010-04-01

of Surface/ Paints Reflection Properties (PILASTER targets); • PILASTER Sensors Testing and Calibration; • LOAS Laser System Testing; and • Test...PILASTER targets candidate paints and materials), a Laser Scatter-meter (LSM) was built. To briefly summarise the fundamental concepts involved...Green Painted Target. 7.6.3 Laser Beam Misalignment with Respect to the Beam-Expander Support For measuring the beam misalignment, the beam expander

Gigabit-per-second white light-based visible light communication using near-ultraviolet laser diode and red-, green-, and blue-emitting phosphors.

PubMed

Lee, Changmin; Shen, Chao; Cozzan, Clayton; Farrell, Robert M; Speck, James S; Nakamura, Shuji; Ooi, Boon S; DenBaars, Steven P

2017-07-24

Data communication based on white light generated using a near-ultraviolet (NUV) laser diode (LD) pumping red-, green-, and blue-emitting (RGB) phosphors was demonstrated for the first time. A III-nitride laser diode (LD) on a semipolar (2021¯)  substrate emitting at 410 nm was used for the transmitter. The measured modulation bandwidth of the LD was 1 GHz, which was limited by the avalanche photodetector. The emission from the NUV LD and the RGB phosphor combination measured a color rendering index (CRI) of 79 and correlated color temperature (CCT) of 4050 K, indicating promise of this approach for creating high quality white lighting. Using this configuration, data was successfully transmitted at a rate of more than 1 Gbps. This NUV laser-based system is expected to have lower background noise from sunlight at the LD emission wavelength than a system that uses a blue LD due to the rapid fall off in intensity of the solar spectrum in the NUV spectral region.

Color vision deficits and laser eyewear protection for soft tissue laser applications.

PubMed

Teichman, J M; Vassar, G J; Yates, J T; Angle, B N; Johnson, A J; Dirks, M S; Thompson, I M

1999-03-01

Laser safety considerations require urologists to wear laser eye protection. Laser eye protection devices block transmittance of specific light wavelengths and may distort color perception. We tested whether urologists risk color confusion when wearing laser eye protection devices for laser soft tissue applications. Subjects were tested with the Farnsworth-Munsell 100-Hue Test without (controls) and with laser eye protection devices for carbon dioxide, potassium titanyl phosphate (KTP), neodymium (Nd):YAG and holmium:YAG lasers. Color deficits were characterized by error scores, polar graphs, confusion angles, confusion index, scatter index and color axes. Laser eye protection device spectral transmittance was tested with spectrophotometry. Mean total error scores plus or minus standard deviation were 13+/-5 for controls, and 44+/-31 for carbon dioxide, 273+/-26 for KTP, 22+/-6 for Nd:YAG and 14+/-8 for holmium:YAG devices (p <0.001). The KTP laser eye protection polar graphs, and confusion and scatter indexes revealed moderate blue-yellow and red-green color confusion. Color axes indicated no significant deficits for controls, or carbon dioxide, Nd:YAG or holmium:YAG laser eye protection in any subject compared to blue-yellow color vision deficits in 8 of 8 tested with KTP laser eye protection (p <0.001). Spectrophotometry demonstrated that light was blocked with laser eye protection devices for carbon dioxide less than 380, holmium:YAG greater than 850, Nd:YAG less than 350 and greater than 950, and KTP less than 550 and greater than 750 nm. The laser eye protection device for KTP causes significant blue-yellow and red-green color confusion. Laser eye protection devices for carbon dioxide, holmium:YAG and Nd:YAG cause no significant color confusion compared to controls. The differences are explained by laser eye protection spectrophotometry characteristics and visual physiology.

Diode-pumped Nd:GAGG-LBO laser at 531 nm

NASA Astrophysics Data System (ADS)

Zou, J.; Chu, H.; Wang, L. R.

2012-03-01

We report a green laser at 531 nm generation by intracavity frequency doubling of a continuous wave (cw) laser operation of a 1062 nm Nd:GAGG laser under in-band diode pumping at 808 nm. A LiB3O5 (LBO) crystal, cut for critical type I phase matching at room temperature is used for second harmonic generation of the laser. At an incident pump power of 18.5 W, as high as 933 mW of cw output power at 531 nm is achieved. The fluctuation of the green output power was better than 3.5% in the given 4 h.

Laser-assisted indocyanine green dye angiography accurately predicts the split-thickness graft timing of integra artificial dermis.

PubMed

Fourman, Mitchell S; Phillips, Brett T; Fritz, Jason R; Conkling, Nicole; McClain, Steve A; Simon, Marcia; Dagum, Alexander B

2014-08-01

The use of an artificial dermal substitute such as Integra-a bilaminate combination of thin silicone and cross-linked bovine tendon collagen and chondroitin-6-sulfate-has become a popular method to address large surface area wounds or smaller, complex wounds devoid of a vascular bed. The incorporation of Integra depends on a vascular wound bed or periphery and can take 4 weeks or longer to occur. If the Integra has not fully incorporated at the time of placement of the split-thickness graft, complete graft loss may result. The availability of a minimally invasive method to assess the incorporation of Integra would be of great value. Two 5 × 10-cm paraspinal full-thickness wounds were created on 3 female swine. Wounds were randomly assigned full-thickness skin graft or Integra (Plainsboro, NJ) treatment. Both types of grafts were placed after the application of fibrin glue (Tisseel, Deerfield, Ill) to the wound bed. Laser Doppler imaging (LDI) (Moor), indocyanine green dye (ICG) angiography (LifeCell SPY), and clinical scoring were performed weekly for a period of 8 weeks after grafting. At 4 weeks, the silicone layer of the Integra was removed, and a culture of autologous keratinocytes was applied. A 4-mm punch biopsy sample of each graft was taken 1, 2, 4, 6, 7, and 8 weeks postoperatively for histologic analysis. Both ICG angiography and LDI perfusion measurements noted an increase in perfusion at the Integra graft site that peaked 3 weeks after grafting, corresponding with the start of neovascularization and the optimal time for the application of a split-thickness skin graft. indocyanine green dye angiography measurements exhibit greater reproducibility between animals at late time points as compared with LDI. This decrease in LDI precision is directly related to increases in scar tissue thickness of greater than 5 mm as determined via histologic analysis and corresponds with the accepted maximum penetration depth of the LDI laser. Indocyanine green dye

Investigation on laser-assisted tissue repair with NIR millisecond-long light pulses and Indocyanine Green-biopolymeric patches

NASA Astrophysics Data System (ADS)

Matteini, Paolo; Banchelli, Martina; Cottat, Maximilien; Osticioli, Iacopo; de Angelis, Marella; Rossi, Francesca; Pini, Roberto

2016-03-01

In previous works a minimally invasive laser-assisted technique for vascular repair was presented. The technique rests on the photothermal adhesion of a biocompatible and bioresorbable patch containing Indocyanine Green that is brought into contact with the site to be repaired. Afterward the use of NIR millisecond-long light pulses generates a strong welding effect between the patch and the underlying tissue and in turn the repair of the wound. This technique was shown to be effective in animal model and provides several advantages over conventional suturing methods. Here we investigate and discuss the optical stability of the ICG-biopolymeric patches and the photothermal effects induced to the irradiated tissue.

Resonant photoacoustic detection of NO2 traces with a Q-switched green laser

NASA Astrophysics Data System (ADS)

Slezak, Verónica; Codnia, Jorge; Peuriot, Alejandro L.; Santiago, Guillermo

2003-01-01

Resonant photoacoustic detection of NO2 traces by means of a high repetition pulsed green laser is presented. The resonator is a cylindrical Pyrex glass cell with a measured Q factor 380 for the first radial mode in air at atmospheric pressure. The system is calibrated with known mixtures in dry air and a minimum detectable volume concentration of 50 parts in 109 is obtained (S/N=1). Its sensitivity allows one to detect and quantify NO2 traces in the exhaust gases of cars. Previously, the analysis of gas adsorption and desorption on the walls and of changes in the sample composition is carried out in order to minimize errors in the determination of NO2 content upon application of the extractive method. The efficiency of catalytic converters of several models of automobiles is studied and the NO2 concentration in samples from exhausts of different types of engine (gasoline, diesel, and methane gas) at idling operation are measured.

Lithium-aluminum-zinc phosphate glasses activated with Tb3+ and Tb3+/Eu3+ for green laser medium, reddish-orange and white phosphor applications

NASA Astrophysics Data System (ADS)

Francisco-Rodriguez, H. I.; Lira, A.; Soriano-Romero, O.; Meza-Rocha, A. N.; Bordignon, S.; Speghini, A.; Lozada-Morales, R.; Caldiño, U.

2018-05-01

A spectroscopic analysis of Tb3+ and Tb3+/Eu3+ doped lithium-aluminum-zinc phosphate glasses is performed through their absorbance and photoluminescence spectra, and decay time profiles. Laser parameter values (stimulated emission cross section, effective bandwidth, gain bandwidth and optical gain) were obtained for the terbium 5D4 → 7F5 green emission from the Tb3+ singly-doped glass (LAZT) excited at 350 nm to judge the suitability of the glass phosphor for fiber lasers. A quantum yield of (47.68 ± 0.49)% was measured for the 5D4 level luminescence. Upon 350 nm excitation the LAZT glass phosphor emits green light with a color purity of 65.6% and chromaticity coordinates (0.285, 0.585) very close to those (0.29, 0.60) of European Broadcasting Union illuminant green. The Tb3+/Eu3+codoped glass emission color can be tuned from reddish-orange of 1865 K upon 318 nm excitation to warm white of 3599 K and neutral white of 4049 K upon 359 and 340 nm excitations, respectively. Upon Tb3+ excitation at 340 nm Eu3+ is sensitized by Tb3+ through a non-radiative energy transfer with an efficiency of 0.23-0.26. An electric dipole-dipole interaction might be the dominant mechanism in the Tb3+ to Eu3+ energy transfer taking place into Tb3+ - Eu3+ clusters.

Assessment of damage in 'green' composites

NASA Astrophysics Data System (ADS)

Malinowski, Paweł H.; Ostachowicz, Wiesław M.; Touchard, Fabienne; Boustie, Michel; Chocinski-Arnault, Laurence; Pascual Gonzalez, Pedro; Berthe, Laurent; de Vasconcellos, Davi; Sorrentino, Luigi

2017-04-01

The behaviour of eco-composites, when subjected to laser or mechanical impact loadings, is not well known yet. A research was proposed looking at the behaviour of `green' and synthetic composites under impact loading. The study was focused on composites reinforced with short, medium and long fibres. Short fibre composites were made of spruce fibres and ABS. The fibres were used both as received and after a thermal treatment. Another set of samples was made of 60 mm-long flax fibres. Two types of thermoplastic polymers were used as matrices: polypropylene and polylactide. Also a woven eco-composite was investigated. It was made of plain woven hemp fabric impregnated with epoxy resin. A fully synthetic woven composite, used as reference laminate for comparison with `green' composites, was prepared by using a plain weave woven glass fabric impregnated with epoxy resin. Mechanical impacts were performed by means of a falling dart impact testing machine. The specimens were tested at different impact energy levels (from 1J to 5J) by keeping constant the mass of the impactor and varying the drop height. Laser impact tests were performed by means of a high power laser shock facility. All the samples were tested at six different laser shock intensities, keeping constant the shock diameter and the pulse duration. Six assessment techniques were employed in order to analyse and compare impact damages: eye observation, back face relief, terahertz spectroscopy, laser vibrometry, X-ray micro-tomography and microscopic observations. Different damage detection thresholds for each material and technique were obtained.

Controllable red, green, blue (RGB) and bright white upconversion luminescence of Lu2O3:Yb3+/Er3+/Tm3+ nanocrystals through single laser excitation at 980 nm.

PubMed

Yang, Jun; Zhang, Cuimiao; Peng, Chong; Li, Chunxia; Wang, Lili; Chai, Ruitao; Lin, Jun

2009-01-01

Light fantastic! Lu(2)O(3):Yb(3+)/Er(3+)/Tm(3+) nanocrystals with controllable red, green, blue (RGB) and bright white upconversion luminescence by a single laser excitation of 980 nm have been successfully synthesized (see picture). Due to abundant UC PL colors, it can potentially be used as fluorophores in the field of color displays, back light, UC lasers, photonics, and biomedicine.Lu(2)O(3):Yb(3+)/Er(3+)/Tm(3+) nanocrystals have been successfully synthesized by a solvothermal process followed by a subsequent heat treatment at 800 degrees C. Powder X-ray diffraction, transmission electron microscopy, upconversion photoluminescence spectra, and kinetic decay were used to characterize the samples. Under single-wavelength diode laser excitation of 980 nm, the bright blue emissions of Lu(2)O(3):Yb(3+), Tm(3+) nanocrystals near 477 and 490 nm were observed due to the (1)G(4)-->(3)H(6) transition of Tm(3+). The bright green UC emissions of Lu(2)O(3):Er(3+) nanocrystals appeared near 540 and 565 nm were observed and assigned to the (2)H(11/2)-->(4)I(15/2) and (4)S(3/2)-->(4)I(15/2) transitions, respectively, of Er(3+). The ratio of the intensity of green luminescence to that of red luminescence decreases with an increase of concentration of Yb(3+) in Lu(2)O(3):Er(3+) nanocrystals. In sufficient quantities of Yb(3+) with resprct to Er(3+), the bright red UC emission of Lu(2)O(3):Yb(3+)/Er(3+) centered at 662 nm was predominant, due to the (4)F(9/2)-->(4)I(15/2) transition of Er(3+). Based on the generation of red, green, and blue emissions in the different doped Lu(2)O(3):RE(3+) nanocrystals, it is possible to produce the luminescence with a wide spectrum of colors, including white, by the appropriate doping of Yb(3+), Tm(3+), and Er(3+) in the present Lu(2)O(3) nanocrystals. Namely, Lu(2)O(3):3 %Yb(3+)/0.2 %Tm(3+)/0.4 %Er(3+) nanocrystals show suitable intensities of blue, green, and red (RGB) emission, resulting in the production of perfect and bright white light

Laser discrimination by stimulated emission of a phosphor

NASA Technical Reports Server (NTRS)

Mathur, V. K.; Chakrabarti, K.

1991-01-01

A method for discriminating sources of UV, near infrared, and far infrared laser radiation was discovered. This technology is based on the use of a single magnesium sulfide phosphor doubly doped with rare earth ions, which is thermally/optically stimulated to generate colors correlatable to the incident laser radiation. The phosphor, after initial charging by visible light, exhibits green stimulated luminescence when exposed to a near infrared source (Nd: YAG laser). On exposure to far infrared sources (CO2 laser) the phosphor emission changes to orange color. A UV laser produces both an orange red as well as green color. A device using this phosphor is useful for detecting the laser and for discriminating between the near infrared, far infrared, and UV lasers. The technology is also capable of infrared laser diode beam profiling since the radiation source leaves an imprint on the phosphor that can be photographed. Continued development of the technology offers potential for discrimination between even smaller bandwidths within the infrared spectrum, a possible aid to communication or wavemixing devices that need to rapidly identify and process optical signals.

Submarine laser communications

NASA Astrophysics Data System (ADS)

McConathy, D. R.

The Department of the Navy and the Defense Advanced Research Projects Agency (DARPA) are sponsoring a joint study to investigate the use of blue-green laser technology to comunicate with submarines at operating depths. Two approaches are under investigation - one in which the laser itself is space-based, and the other in which the laser is ground-based with its beam redirected to the earth's surface by an orbiting mirror. This paper discusses these two approaches, and presents a brief history of activities which led to the current studies.

Feasibility and clinical utility of ultra-widefield indocyanine green angiography.

PubMed

Klufas, Michael A; Yannuzzi, Nicolas A; Pang, Claudine E; Srinivas, Sowmya; Sadda, Srinivas R; Freund, K Bailey; Kiss, Szilárd

2015-03-01

To evaluate the feasibility and clinical utility of a novel noncontact scanning laser ophthalmoscope-based ultra-widefield indocyanine green angiographic system. Ultra-widefield indocyanine green angiographic images were captured using a modified Optos P200Tx that produced high-resolution images of the choroidal vasculature with up to a 200° field. Ultra-widefield indocyanine green angiography was performed on patients with a variety of retinal conditions to assess utility of this imaging technique for diagnostic purposes and disease treatment monitoring. Ultra-widefield indocyanine green angiography was performed on 138 eyes of 69 patients. Mean age was 58 ± 16.9 years (range, 24-85 years). The most common ocular pathologies imaged included central serous chorioretinopathy (24 eyes), uveitis (various subtypes, 16 eyes), age-related macular degeneration (12 eyes), and polypoidal choroidal vasculopathy (4 eyes). In all eyes evaluated with ultra-widefield indocyanine green angiography, high-resolution images of choroidal and retinal circulation were obtained with sufficient detail out to 200° of the fundus. In this series of 138 eyes, scanning laser ophthalmoscope-based ultra-widefield indocyanine green angiography was clinically practical and provided detailed images of both the central and peripheral choroidal circulation. Future studies are needed to refine the clinical value of this imaging modality and the significance of peripheral choroidal vascular changes in the diagnosis, monitoring, and treatment of ocular diseases.

Color speckle in laser displays

NASA Astrophysics Data System (ADS)

Kuroda, Kazuo

2015-07-01

At the beginning of this century, lighting technology has been shifted from discharge lamps, fluorescent lamps and electric bulbs to solid-state lighting. Current solid-state lighting is based on the light emitting diodes (LED) technology, but the laser lighting technology is developing rapidly, such as, laser cinema projectors, laser TVs, laser head-up displays, laser head mounted displays, and laser headlamps for motor vehicles. One of the main issues of laser displays is the reduction of speckle noise1). For the monochromatic laser light, speckle is random interference pattern on the image plane (retina for human observer). For laser displays, RGB (red-green-blue) lasers form speckle patterns independently, which results in random distribution of chromaticity, called color speckle2).

OPO-based compact laser projection display

NASA Astrophysics Data System (ADS)

Lee, Dicky; Moulton, Peter F.; Bergstedt, Robert; Flint, Graham W.

2001-09-01

In this paper we discuss our red, green, and blue (RGB) optical parametric oscillator (OPO) based laser projection display. The complete project display consists of two subsystems, the RGB-OPO laser head and the light modulation unit. The RGB lights from rack-mounted laser head are fibers coupled to the projection unit for independent placement. The light source consists of a diode-pumped pump laser and a LBO-based OPO. Based on our Nd:YLF gain module design, the pump laser is frequency doubled to serve as the pump source for the OPO. The unconverted pump power is recycled as the green light for projection. The singly resonant, non- critically phase-matched (NCPM) OPO has, to date, generated 13 W of 898-nm signal power and an estimated 9.3 W of intra- cavity idler power at 1256 nm. With approximately 76% of pump depletion, the power of the residual green light for projection is about 5.8 W. We have extra-cavity doubled the signal to produce approximately 3.5 W of 449-nm blue light and intra-cavity doubled the idler to produce approximately 6 W of 628-nm red light. The OPO-based RGB source generates about 4000 lumens of D65-balanced white light. The overall electrical power on a commercially available JVC's three- panel D-ILA (reflective LCD) projector with the arc-lamp removed and extensive modifications. The projector has a native resolution of 1365 x 1024 and the expected on screen lumens from our laser display is about 1200 lumens.

Cracking the perfusion code?: Laser-assisted Indocyanine Green angiography and combined laser Doppler spectrophotometry for intraoperative evaluation of tissue perfusion in autologous breast reconstruction with DIEP or ms-TRAM flaps.

PubMed

Ludolph, Ingo; Arkudas, Andreas; Schmitz, Marweh; Boos, Anja M; Taeger, Christian D; Rother, Ulrich; Horch, Raymund E; Beier, Justus P

2016-10-01

The aim of this prospective study was to assess the correlation of flap perfusion analysis based on laser-assisted Indocyanine Green (ICG) angiography with combined laser Doppler spectrophotometry in autologous breast reconstruction using free DIEP/ms-TRAM flaps. Between February 2014 and July 2015, 35 free DIEP/ms-TRAM flaps were included in this study. Besides the clinical evaluation of flaps, intraoperative perfusion dynamics were assessed by means of laser-assisted ICG angiography and post-capillary oxygen saturation and relative haemoglobin content (rHb) using combined laser Doppler spectrophotometry. Correlation of the aforementioned parameters was analysed, as well as the impact on flap design and postoperative complications. Flap survival rate was 100%. There were no partial flap losses. In three cases, flap design was based on the angiography, contrary to clinical evaluation and spectrophotometry. The final decision on the inclusion of flap areas was based on the angiographic perfusion pattern. Angiography and spectrophotometry showed a correlation in most of the cases regarding tissue perfusion, post-capillary oxygen saturation and relative haemoglobin content. Laser-assisted ICG angiography is a useful tool for intraoperative evaluation of flap perfusion in autologous breast reconstruction with DIEP/ms-TRAM flaps, especially in decision making in cases where flap perfusion is not clearly assessable by clinical signs and exact determination of well-perfused flap margins is difficult to obtain. It provides an objective real-time analysis of flap perfusion, with high sensitivity for the detection of poorly perfused flap areas. Concerning the topographical mapping of well-perfused flap areas, laser-assisted angiography is superior to combined laser Doppler spectrophotometry. Copyright © 2016 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Towards green loyalty: the influences of green perceived risk, green image, green trust and green satisfaction

NASA Astrophysics Data System (ADS)

Chrisjatmiko, K.

2018-01-01

The paper aims to present a comprehensive framework for the influences of green perceived risk, green image, green trust and green satisfaction to green loyalty. The paper also seeks to account explicitly for the differences in green perceived risk, green image, green trust, green satisfaction and green loyalty found among green products customers. Data were obtained from 155 green products customers. Structural equation modeling was used in order to test the proposed hypotheses. The findings show that green image, green trust and green satisfaction has positive effects to green loyalty. But green perceived risk has negative effects to green image, green trust and green satisfaction. However, green perceived risk, green image, green trust and green satisfaction also seems to be a good device to gain green products customers from competitors. The contributions of the paper are, firstly, a more complete framework of the influences of green perceived risk, green image, green trust and green satisfaction to green loyalty analyses simultaneously. Secondly, the study allows a direct comparison of the difference in green perceived risk, green image, green trust, green satisfaction and green loyalty between green products customers.

Continuously tunable solution-processed organic semiconductor DFB lasers pumped by laser diode.

PubMed

Klinkhammer, Sönke; Liu, Xin; Huska, Klaus; Shen, Yuxin; Vanderheiden, Sylvia; Valouch, Sebastian; Vannahme, Christoph; Bräse, Stefan; Mappes, Timo; Lemmer, Uli

2012-03-12

The fabrication and characterization of continuously tunable, solution-processed distributed feedback (DFB) lasers in the visible regime is reported. Continuous thin film thickness gradients were achieved by means of horizontal dipping of several conjugated polymer and blended small molecule solutions on cm-scale surface gratings of different periods. We report optically pumped continuously tunable laser emission of 13 nm in the blue, 16 nm in the green and 19 nm in the red spectral region on a single chip respectively. Tuning behavior can be described with the Bragg-equation and the measured thickness profile. The laser threshold is low enough that inexpensive laser diodes can be used as pump sources.

Design of three-well indirect pumping terahertz quantum cascade lasers for high optical gain based on nonequilibrium Green's function analysis

NASA Astrophysics Data System (ADS)

Liu, Tao; Kubis, Tillmann; Jie Wang, Qi; Klimeck, Gerhard

2012-03-01

The nonequilibrium Green's function approach is applied to the design of three-well indirect pumping terahertz (THz) quantum cascade lasers (QCLs) based on a resonant phonon depopulation scheme. The effects of the anticrossing of the injector states and the dipole matrix element of the laser levels on the optical gain of THz QCLs are studied. The results show that a design that results in a more pronounced anticrossing of the injector states will achieve a higher optical gain in the indirect pumping scheme compared to the traditional resonant-tunneling injection scheme. This offers in general a more efficient coherent resonant-tunneling transport of electrons in the indirect pumping scheme. It is also shown that, for operating temperatures below 200 K and low lasing frequencies, larger dipole matrix elements, i.e., vertical optical transitions, offer a higher optical gain. In contrast, in the case of high lasing frequencies, smaller dipole matrix elements, i.e., diagonal optical transitions are better for achieving a higher optical gain.

Spectral identifiers from roasting process of Arabica and Robusta green beans using Laser-Induced Breakdown Spectroscopy (LIBS)

NASA Astrophysics Data System (ADS)

Wirani, Ayu Puspa; Nasution, Aulia; Suyanto, Hery

2016-11-01

Coffee (Coffea spp.) is one of the most widely consumed beverages in the world. World coffee consumption is around 70% comes from Arabica, 26% from Robusta , and the rest 4% from other varieties. Coffee beverages characteristics are related to chemical compositions of its roasted beans. Usually testing of coffee quality is subjectively tasted by an experienced coffee tester. An objective quantitative technique to analyze the chemical contents of coffee beans using LIBS will be reported in this paper. Optimum experimental conditions was using of 120 mJ of laser energy and delay time 1 μs. Elements contained in coffee beans are Ca, W, Sr, Mg, Na, H, K, O, Rb, and Be. The Calcium (Ca) is the main element in the coffee beans. Roasting process will cause the emission intensity of Ca decreased by 42.45%. In addition, discriminant analysis was used to distinguish the arabica and robusta variants, either in its green and roasted coffee beans. Observed identifier elements are Ca, W, Sr, and Mg. Overall chemical composition of roasted coffee beans are affected by many factors, such as the composition of the soil, the location, the weather in the neighborhood of its plantation, and the post-harvesting process of the green coffee beans (drying, storage, fermentation, and roasting methods used).

Study of the field-sequential modulation of Nd:YVO4/MgO:PPLN based intra-cavity frequency doubling green laser

NASA Astrophysics Data System (ADS)

Zhang, Bin; Gan, Yi; Xu, Chang-Qing

2018-06-01

The field sequential modulation of a Nd:YVO4/MgO:PPLN intra-cavity, frequency doubling green laser was studied. The modulation frequency was set at 1 kHz and the duty cycle was changed from 20% to CW operation. It was shown that the quasi-phase matched (QPM) temperature decreases with an increase of the modulation duty cycle, and in turn causing the peak efficiency to rise. It was found that the temperature change in MgO:PPLN and the thermal lens effect in Nd:YVO4 crystal were the respective origins of these observed experimental phenomena.

Presidential Green Chemistry Challenge: 2008 Greener Synthetic Pathways Award

EPA Pesticide Factsheets

Presidential Green Chemistry Challenge 2008 award winner, Battelle, developed a biobased soy toner for laser printers and copiers. The technology saves energy and improves de-inking, allowing more paper fiber to be recycled.

Efficient generation of 509 nm light by sum-frequency mixing between two tapered diode lasers

NASA Astrophysics Data System (ADS)

Tawfieq, Mahmoud; Jensen, Ole Bjarlin; Hansen, Anders Kragh; Sumpf, Bernd; Paschke, Katrin; Andersen, Peter E.

2015-03-01

We demonstrate a concept for visible laser sources based on sum-frequency generation of beam combined tapered diode lasers. In this specific case, a 1.7 W sum-frequency generated green laser at 509 nm is obtained, by frequency adding of 6.17 W from a 978 nm tapered diode laser with 8.06 W from a 1063 nm tapered diode laser, inside a periodically poled MgO doped lithium niobate crystal. This corresponds to an optical to optical conversion efficiency of 12.1%. As an example of potential applications, the generated nearly diffraction-limited green light is used for pumping a Ti:sapphire laser, thus demonstrating good beam quality and power stability. The maximum output powers achieved when pumping the Ti:sapphire laser are 226 mW (CW) and 185 mW (mode-locked) at 1.7 W green pump power. The optical spectrum emitted by the mode-locked Ti:sapphire laser shows a spectral width of about 54 nm (FWHM), indicating less than 20 fs pulse width.

A Plasma Ultraviolet Source for Short Wavelength Lasers.

DTIC Science & Technology

1986-03-10

A high power blue-green laser was pumped with an array of the dense plasma focus . As the result of optimizing the operating conditions of the dense... plasma focus and laser system, the maximum untuned laser output exceeded 2.lmJ corresponding to the energy density 3J/cu cm which is much higher than

Dual-wavelength green laser with a 4.5 THz frequency difference based on self-frequency- doubling in Nd3+ -doped aperiodically poled lithium niobate.

PubMed

Maestre, H; Torregrosa, A J; Fernández-Pousa, C R; Rico, M L; Capmany, J

2008-05-01

We report a dual-wavelength continuous-wave laser at 542.4 and 546.8 nm based on an Nd(3+)-doped aperiodically poled lithium niobate crystal. Two fundamental infrared (IR) wavelengths at 1084.8 and 1093.6 nm are simultaneously oscillated and self-frequency-doubled to green. The aperiodic domain distribution patterned in the crystal allows for quasi-phase matched self-frequency-doubling of both IR fundamentals while avoiding their sum-frequency mixing.

Study of diffusion of indocyanine green as a photodynamic dye into skin using backscattering spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Genina, E A; Bashkatov, A N; Tuchin, V V

One of the lines of development of modern medicine is theranostics consisting in simultaneous diagnosis and laser treatment with the use of multifunctional agents such as fluorescent indocyanine green that has photodynamic and photothermal properties. Diffusion of indocyanine green dissolved in water and aqueous solutions of alcohols (glycerol, propylene glycol and ethanol) into the dermis is studied by using backscattering spectroscopy. The coefficients of the dye diffusion into the dermis are obtained for the first time by using these solvents. (laser biophotonics)

Prussian blue/serum albumin/indocyanine green as a multifunctional nanotheranostic agent for bimodal imaging guided laser mediated combinatorial phototherapy.

PubMed

Sahu, Abhishek; Lee, Jong Hyun; Lee, Hye Gyeong; Jeong, Yong Yeon; Tae, Giyoong

2016-08-28

Developing novel nanotheranostic agent using only clinically approved materials is highly desirable and challenging. In this study, we combined three clinically approved materials, Prussian blue (PB), serum albumin (BSA), and indocyanine green (ICG), by a simple and biocompatible method to prepare a multifunctional theranostic PB-BSA-ICG nanoparticle. The multifunctional nanoparticle system could provide dual mode magnetic resonance (MR) and near infrared (NIR) fluorescence imaging as well as combined photothermal and photodynamic (PTT-PDT) therapy in response to a single NIR laser. This nanoparticle showed an excellent stability in physiological solutions and could suppress the photo-instability of ICG. In the absence of light, the nanoparticles showed no cytotoxicity, but significant cell death was induced through combined PTT-PDT effect after irradiation with NIR laser light. A high tumor accumulation and minimal nonspecific uptake by other major organs of PB-BSA-ICG nanoparticle were observed in vivo, analyzed by T1-weighted MR and NIR fluorescence bimodal imaging in tumor xenograft mice after intravenous injection. The nanoparticles efficiently suppressed the tumor growth through combinatorial phototherapy with no tumor recurrence upon a single NIR laser irradiation. These results demonstrated that PB-BSA-ICG is potentially an interesting nanotheranostic agent for imaging guided cancer therapy by overcoming the limitations of each technology and enhancing the therapeutic efficiency as well as reducing side effects. Copyright © 2016 Elsevier B.V. All rights reserved.

Prototype laser-diode-pumped solid state laser transmitters

NASA Technical Reports Server (NTRS)

Kane, Thomas J.; Cheng, Emily A. P.; Wallace, Richard W.

1989-01-01

Monolithic, diode-pumped Nd:YAG ring lasers can provide diffraction-limited, single-frequency, narrow-linewidth, tunable output which is adequate for use as a local oscillator in a coherent communication system. A laser was built which had a linewidth of about 2 kHz, a power of 5 milliwatts, and which was tunable over a range of 30 MHz in a few microseconds. This laser was phase-locked to a second, similar laser. This demonstrates that the powerful technique of heterodyne detection is possible with a diode-pumped laser used as the local oscillator. Laser diode pumping of monolithic Nd:YAG rings can lead to output powers of hundreds of milliwatts from a single laser. A laser was built with a single-mode output of 310 mW. Several lasers can be chained together to sum their power, while maintaining diffraction-limited, single frequency operation. This technique was demonstrated with two lasers, with a total output of 340 mW, and is expected to be practical for up to about ten lasers. Thus with lasers of 310 mW, output of up to 3 W is possible. The chaining technique, if properly engineered, results in redundancy. The technique of resonant external modulation and doubling is designed to efficiently convert the continuous wave, infrared output of our lasers into low duty-cycle pulsed green output. This technique was verified through both computer modeling and experimentation. Further work would be necessary to develop a deliverable system using this technique.

Solvent-free fluidic organic dye lasers.

PubMed

Choi, Eun Young; Mager, Loic; Cham, Tran Thi; Dorkenoo, Kokou D; Fort, Alain; Wu, Jeong Weon; Barsella, Alberto; Ribierre, Jean-Charles

2013-05-06

We report on the demonstration of liquid organic dye lasers based on 9-(2-ethylhexyl)carbazole (EHCz), so-called liquid carbazole, doped with green- and red-emitting laser dyes. Both waveguide and Fabry-Perot type microcavity fluidic organic dye lasers were prepared by capillary action under solvent-free conditions. Cascade Förster-type energy transfer processes from liquid carbazole to laser dyes were employed to achieve color-variable amplified spontaneous emission and lasing. Overall, this study provides the first step towards the development of solvent-free fluidic organic semiconducting lasers and demonstrates a new kind of optoelectronic applications for liquid organic semiconductors.

Government-Imposed Barriers to the Use of Commercial Integrated Circuits in Military Systems.

DTIC Science & Technology

1996-02-01

Advanced Planning Briefing for Industry (undated). The FY94/FY95 research agenda of the Microprocessor Technology Utiliza- tion Program includes... planning and re- sults. As a model of how a private institute might operate, we suggest (without implying partiality) the Semiconductor Research...or incorporate lessons learned). Those IC suppliers passing the audit are listed on the QML. Products from QML-listed suppliers can be used with

Frequency doubled high-power disk lasers in pulsed and continuous-wave operation

NASA Astrophysics Data System (ADS)

Weiler, Sascha; Hangst, Alexander; Stolzenburg, Christian; Zawischa, Ivo; Sutter, Dirk; Killi, Alexander; Kalfhues, Steffen; Kriegshaeuser, Uwe; Holzer, Marco; Havrilla, David

2012-03-01

The disk laser with multi-kW output power in infrared cw operation is widely used in today's manufacturing, primarily in the automotive industry. The disk technology combines high power (average and/or peak power), excellent beam quality, high efficiency and high reliability with low investment and operating costs. Additionally, the disk laser is ideally suited for frequency conversion due to its polarized output with negligible depolarization losses. Laser light in the green spectral range (~515 nm) can be created with a nonlinear crystal. Pulsed disk lasers with green output of well above 50 W (extracavity doubling) in the ps regime and several hundreds of Watts in the ns regime with intracavity doubling are already commercially available whereas intracavity doubled disk lasers in continuous wave operation with greater than 250 W output are in test phase. In both operating modes (pulsed and cw) the frequency doubled disk laser offers advantages in existing and new applications. Copper welding for example is said to show much higher process reliability with green laser light due to its higher absorption in comparison to the infrared. This improvement has the potential to be very beneficial for the automotive industry's move to electrical vehicles which requires reliable high-volume welding of copper as a major task for electro motors, batteries, etc.

Comparison of Indocyanine Green Angiography and Laser Speckle Contrast Imaging for the Assessment of Vasculature Perfusion

PubMed Central

Towle, Erica L.; Richards, Lisa M.; Kazmi, S. M. Shams; Fox, Douglas J.; Dunn, Andrew K.

2013-01-01

BACKGROUND Assessment of the vasculature is critical for overall success in cranial vascular neurological surgery procedures. Although several methods of monitoring cortical perfusion intraoperatively are available, not all are appropriate or convenient in a surgical environment. Recently, 2 optical methods of care have emerged that are able to obtain high spatial resolution images with easily implemented instrumentation: indocyanine green (ICG) angiography and laser speckle contrast imaging (LSCI). OBJECTIVE To evaluate the usefulness of ICG and LSCI in measuring vessel perfusion. METHODS An experimental setup was developed that simultaneously collects measurements of ICG fluorescence and LSCI in a rodent model. A 785-nm laser diode was used for both excitation of the ICG dye and the LSCI illumination. A photothrombotic clot model was used to occlude specific vessels within the field of view to enable comparison of the 2 methods for monitoring vessel perfusion. RESULTS The induced blood flow change demonstrated that ICG is an excellent method for visualizing the volume and type of vessel at a single point in time; however, it is not always an accurate representation of blood flow. In contrast, LSCI provides a continuous and accurate measurement of blood flow changes without the need of an external contrast agent. CONCLUSION These 2 methods should be used together to obtain a complete understanding of tissue perfusion. PMID:22843129

The use of picosecond lasers beyond tattoos.

PubMed

Forbat, E; Al-Niaimi, F

2016-10-01

Picosecond lasers are a novel laser with the ability to create a pulse of less than one nanosecond. They have been available in the clinical context since 2012. Dermatologists are now using picosecond lasers regularly for the treatment of blue and green pigment tattoo removal. This article reviews the use of picosecond lasers beyond tattoo removal. The overall consensus for the use of picosecond lasers beyond tattoo treatment is positive. With examples of this in the treatment of nevus of Ota, minocycline-induced pigmentation, acne scarring, and rhytides.

Extending green technology innovations to enable greener fabs

NASA Astrophysics Data System (ADS)

Takahisa, Kenji; Yoo, Young Sun; Fukuda, Hitomi; Minegishi, Yuji; Enami, Tatsuo

2015-03-01

Semiconductor manufacturing industry has growing concerns over future environmental impacts as fabs expand and new generations of equipment become more powerful. Especially rare gases supply and price are one of prime concerns for operation of high volume manufacturing (HVM) fabs. Over the past year it has come to our attention that Helium and Neon gas supplies could be unstable and become a threat to HVM fabs. To address these concerns, Gigaphoton has implemented various green technologies under its EcoPhoton program. One of the initiatives is GigaTwin deep ultraviolet (DUV) lithography laser design which enables highly efficient and stable operation. Under this design laser systems run with 50% less electric energy and gas consumption compared to conventional laser designs. In 2014 we have developed two technologies to further reduce electric energy and gas efficiency. The electric energy reduction technology is called eGRYCOS (enhanced Gigaphoton Recycled Chamber Operation System), and it reduces electric energy by 15% without compromising any of laser performances. eGRYCOS system has a sophisticated gas flow design so that we can reduce cross-flow-fan rotation speed. The gas reduction technology is called eTGM (enhanced Total gas Manager) and it improves gas management system optimizing the gas injection and exhaust amount based on laser performances, resulting in 50% gas savings. The next steps in our roadmap technologies are indicated and we call for potential partners to work with us based on OPEN INNOVATION concept to successfully develop faster and better solutions in all possible areas where green innovation may exist.

Lasers' spectral and temporal profile can affect visual glare disability.

PubMed

Beer, Jeremy M A; Freeman, David A

2012-12-01

Experiments measured the effects of laser glare on visual orientation and motion perception. Laser stimuli were varied according to spectral composition and temporal presentation as subjects identified targets' tilt (Experiment 1) and movement (Experiment 2). The objective was to determine whether the glare parameters would alter visual disruption. Three spectral profiles (monochromatic Green vs. polychromatic White vs. alternating Red-Green) were used to produce a ring of laser glare surrounding a target. Two experiments were performed to measure the minimum contrast required to report target orientation or motion direction. The temporal glare profile was also varied: the ring was illuminated either continuously or discontinuously. Time-averaged luminance of the glare stimuli was matched across all conditions. In both experiments, threshold (deltaL) values were approximately 0.15 log units higher in monochromatic Green than in polychromatic White conditions. In Experiment 2 (motion identification), thresholds were approximately 0.17 log units higher in rapidly flashing (6, 10, or 14 Hz) than in continuous exposure conditions. Monochromatic extended-source laser glare disrupted orientation and motion identification more than polychromatic glare. In the motion task, pulse trains faster than 6 Hz (but below flicker fusion) elevated thresholds more than continuous glare with the same time-averaged luminance. Under these conditions, alternating the wavelength of monochromatic glare over time did not aggravate disability relative to green-only glare. Repetitively flashing monochromatic laser glare induced occasional episodes of impaired motion identification, perhaps resulting from cognitive interference. Interference speckle might play a role in aggravating monochromatic glare effects.

Optical ridge waveguides in Er3+/Yb3+ co-doped phosphate glass produced by ion irradiation combined with femtosecond laser ablation for guided-wave green and red upconversion emissions

NASA Astrophysics Data System (ADS)

Chen, Chen; He, Ruiyun; Tan, Yang; Wang, Biao; Akhmadaliev, Shavkat; Zhou, Shengqiang; de Aldana, Javier R. Vázquez; Hu, Lili; Chen, Feng

2016-01-01

This work reports on the fabrication of ridge waveguides in Er3+/Yb3+ co-doped phosphate glass by the combination of femtosecond laser ablation and following swift carbon ion irradiation. The guiding properties of waveguides have been investigated at 633 and 1064 nm through end face coupling arrangement. The refractive index profile on the cross section of the waveguide has been constructed. The propagation losses can be reduced considerably after annealing treatment. Under the optical pump laser at 980 nm, the upconversion emission of both green and red fluorescence has been realized through the ridge waveguide structures.

Red, green, and blue lasing enabled by single-exciton gain in colloidal quantum dot films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nurmikko, Arto V.; Dang, Cuong

The methods and materials described herein contemplate the use films of colloidal quantum dots as a gain medium in a vertical-cavity surface-emitting laser. The present disclosure demonstrates a laser with single-exciton gain in the red, green, and blue wavelengths. Leveraging this nanocomposite gain, the results realize a significant step toward full-color single-material lasers.

Speckle reduction methods in laser-based picture projectors

NASA Astrophysics Data System (ADS)

Akram, M. Nadeem; Chen, Xuyuan

2016-02-01

Laser sources have been promised for many years to be better light sources as compared to traditional lamps or light-emitting diodes (LEDs) for projectors, which enable projectors having wide colour gamut for vivid image, super brightness and high contrast for the best picture quality, long lifetime for maintain free operation, mercury free, and low power consumption for green environment. A major technology obstacle in using lasers for projection has been the speckle noise caused by to the coherent nature of the lasers. For speckle reduction, current state of the art solutions apply moving parts with large physical space demand. Solutions beyond the state of the art need to be developed such as integrated optical components, hybrid MOEMS devices, and active phase modulators for compact speckle reduction. In this article, major methods reported in the literature for the speckle reduction in laser projectors are presented and explained. With the advancement in semiconductor lasers with largely reduced cost for the red, green and the blue primary colours, and the developed methods for their speckle reduction, it is hoped that the lasers will be widely utilized in different projector applications in the near future.

Comparison of cap lamp and laser illumination for detecting visual escape cues in smoke

PubMed Central

Lutz, T.J.; Sammarco, J.J.; Srednicki, J.R.; Gallagher, S.

2015-01-01

The Illuminating Engineering Society of North America reports that an underground mine is the most difficult environment to illuminate (Rea, 2000). Researchers at the U.S. National Institute for Occupational Safety and Health (NIOSH) Office of Mine Safety and Health Research (OMSHR) are conducting ongoing studies designed to explore different lighting technologies for improving mine safety. Underground miners use different visual cues to escape from a smoke-filled environment. Primary and secondary escapeways are marked with reflective ceiling tags of various colors. Miners also look for mine rail tracks. The main objective of this paper is to compare different lighting types and ceiling tag colors to differentiate what works best in a smoke-filled environment. Various cap lamps (LED and incandescent) and lasers (red, blue, green) were compared to see which options resulted in the longest detection distances for red, green and blue reflective markers and a section of mine rail track. All targets advanced toward the human subject inside of a smoke-filled room to simulate the subject walking in a mine environment. Detection distances were recorded and analyzed to find the best cap lamp, laser color and target color in a smoke environment. Results show that cap lamp, laser color and target color do make a difference in detection distances and are perceived differently based on subject age. Cap lamps were superior to lasers in all circumstances of ceiling tag detection, with the exception of the green laser. The incandescent cap lamp worked best in the simulated smoke compared to the LED cap lamps. The green laser was the best color for detecting the tags and track compared to the red and blue lasers. The green tags were the easiest color to detect on the ceiling. On average, the track was easier for the subjects to detect than the ceiling tags. PMID:26236146

Comparison of cap lamp and laser illumination for detecting visual escape cues in smoke.

PubMed

Lutz, T J; Sammarco, J J; Srednicki, J R; Gallagher, S

The Illuminating Engineering Society of North America reports that an underground mine is the most difficult environment to illuminate (Rea, 2000). Researchers at the U.S. National Institute for Occupational Safety and Health (NIOSH) Office of Mine Safety and Health Research (OMSHR) are conducting ongoing studies designed to explore different lighting technologies for improving mine safety. Underground miners use different visual cues to escape from a smoke-filled environment. Primary and secondary escapeways are marked with reflective ceiling tags of various colors. Miners also look for mine rail tracks. The main objective of this paper is to compare different lighting types and ceiling tag colors to differentiate what works best in a smoke-filled environment. Various cap lamps (LED and incandescent) and lasers (red, blue, green) were compared to see which options resulted in the longest detection distances for red, green and blue reflective markers and a section of mine rail track. All targets advanced toward the human subject inside of a smoke-filled room to simulate the subject walking in a mine environment. Detection distances were recorded and analyzed to find the best cap lamp, laser color and target color in a smoke environment. Results show that cap lamp, laser color and target color do make a difference in detection distances and are perceived differently based on subject age. Cap lamps were superior to lasers in all circumstances of ceiling tag detection, with the exception of the green laser. The incandescent cap lamp worked best in the simulated smoke compared to the LED cap lamps. The green laser was the best color for detecting the tags and track compared to the red and blue lasers. The green tags were the easiest color to detect on the ceiling. On average, the track was easier for the subjects to detect than the ceiling tags.

Turnable Blue-Green LIDAR Transmitter Demonstration: Injection Laser Technology

DTIC Science & Technology

1990-08-30

5-1 5.2 Baseline Requirements ............................................. 5-1 5.3 Optical Parametric Oscillator Using Beta Barium Borate... optical parametric oscillators , and organic dye lasers. Tunable solid state lasers such as Ti: sapphire operate in the infrared and would have to be...The same is true of I frequency mixing schemes. Optical parametric oscillators (OPOs) are attractive because of their extremely wide potential tuning

Fundamental Study of Nuclear Pumped Laser Plasmas.

DTIC Science & Technology

1980-12-23

PUMPED DYE LASER PMT PUMPING/ GAS HAND- LING SYSTEM ANODE SIGNAL TO SCREEN ROOM FIGURE 13 EXPERIMENTAL APPARATUS FROM ANODE OF PMT SCREEN ROOM...and G.A. Zdasiuk, " Laser Induced Collisional and Radiative Energy Transfer’, Proceedings of Laser Spectroscopy IV, June 1979. W. R. Green, M.D. Wright...AD-A130 988 FUNDAMENTAL STUDY 0F NUCLEAR PUMPED LASER PLASMAS(U) 1/ MIAMI UNIV OXFORD UHDi EPT OF PHYSIS Cs W DOWNES ET AL 23 DEC AS OASGAS 7A C OSAN

The ArF laser for the next-generation multiple-patterning immersion lithography supporting green operations

NASA Astrophysics Data System (ADS)

Ishida, Keisuke; Ohta, Takeshi; Miyamoto, Hirotaka; Kumazaki, Takahito; Tsushima, Hiroaki; Kurosu, Akihiko; Matsunaga, Takashi; Mizoguchi, Hakaru

2016-03-01

Multiple patterning ArF immersion lithography has been expected as the promising technology to satisfy tighter leading edge device requirements. One of the most important features of the next generation lasers will be the ability to support green operations while further improving cost of ownership and performance. Especially, the dependence on rare gases, such as Neon and Helium, is becoming a critical issue for high volume manufacturing process. The new ArF excimer laser, GT64A has been developed to cope with the reduction of operational costs, the prevention against rare resource shortage and the improvement of device yield in multiple-patterning lithography. GT64A has advantages in efficiency and stability based on the field-proven injection-lock twin-chamber platform (GigaTwin platform). By the combination of GigaTwin platform and the advanced gas control algorithm, the consumption of rare gases such as Neon is reduced to a half. And newly designed Line Narrowing Module can realize completely Helium free operation. For the device yield improvement, spectral bandwidth stability is important to increase image contrast and contribute to the further reduction of CD variation. The new spectral bandwidth control algorithm and high response actuator has been developed to compensate the offset due to thermal change during the interval such as the period of wafer exchange operation. And REDeeM Cloud™, new monitoring system for managing light source performance and operations, is on-board and provides detailed light source information such as wavelength, energy, E95, etc.

A novel vaporization-enucleation technique for benign prostate hyperplasia using 120-W HPS GreenLight™ laser: Seoul technique II in comparison with vaporization and previously reported modified vaporization-resection technique.

PubMed

Yoo, Sangjun; Park, Juhyun; Cho, Sung Yong; Cho, Min Chul; Jeong, Hyeon; Son, Hwancheol

2017-12-01

We developed a novel vaporization-enucleation technique (Seoul II), which consists of vaporization-enucleation of the prostate using 120-W HPS GreenLight laser, and enucleated prostate resection using bipolar devices for tissue removal. We compared the outcomes of the Seoul II with vaporization and a previously reported modified vaporization-resection technique (Seoul I). Among patients with benign prostate hyperplasia who underwent transurethral surgery using GreenLight laser at our institute, 347 patients with prostate volume ≥ 40 ml were included. The impact of surgical techniques on efficacy and postoperative functional outcomes was compared. No difference was found in baseline characteristics, although the prostate volume was marginally greater in Seoul II (p = 0.051). Prostate volume reduction per operation time (p < 0.001) and lasing time (p = 0.016) were greater in Seoul II. At postoperative 12 months, the International Prostate Symptom Score (I-PSS) was lower (p = 0.011), and the decrement in I-PSS was greater in Seoul II (p = 0.001) than other techniques. In multivariate analysis, postoperative 12-month I-PSS for Seoul II was significantly superior to vaporization (p < 0.001), although it was similar to Seoul I. The maintenance of immediate postoperative I-PSS decrement, until postoperative 12 months was superior in Seoul II compared with vaporization (p = 0.014) and Seoul I (p = 0.048). Seoul II showed improved efficacy and voiding functional maintenance over postoperative 12 months in patients with prostate volume ≥ 40 ml compared with vaporization and Seoul I. This technique could be easily accepted by clinicians who are familiar with GreenLight lasers and add flexibility to surgery without additional equipment.

A switchable digital microfluidic droplet dye-laser.

PubMed

Kuehne, Alexander J C; Gather, Malte C; Eydelnant, Irwin A; Yun, Seok-Hyun; Weitz, David A; Wheeler, Aaron R

2011-11-07

Digital microfluidic devices allow the manipulation of droplets between two parallel electrodes. These electrodes can act as mirrors generating a micro-cavity, which can be exploited for a droplet dye-laser. Three representative laser-dyes with emission wavelengths spanning the whole visible spectrum are chosen to show the applicability of this concept. Sub-microlitre droplets of laser-dye solution are moved in and out of a lasing site on-chip to down-convert the UV-excitation light into blue, green and red laser-pulses. This journal is © The Royal Society of Chemistry 2011

Integrated RGB laser light module for autostereoscopic outdoor displays

NASA Astrophysics Data System (ADS)

Reitterer, Jörg; Fidler, Franz; Hambeck, Christian; Saint Julien-Wallsee, Ferdinand; Najda, Stephen; Perlin, Piotr; Stanczyk, Szymon; Czernecki, Robert; McDougall, Stewart D.; Meredith, Wyn; Vickers, Garrie; Landles, Kennedy; Schmid, Ulrich

2015-02-01

We have developed highly compact RGB laser light modules to be used as light sources in multi-view autostereoscopic outdoor displays and projection devices. Each light module consists of an AlGaInP red laser diode, a GaInN blue laser diode, a GaInN green laser diode, as well as a common cylindrical microlens. The plano-convex microlens is a so-called "fast axis collimator", which is widely used for collimating light beams emitted from high-power laser diode bars, and has been optimized for polychromatic RGB laser diodes. The three light beams emitted from the red, green, and blue laser diodes are collimated in only one transverse direction, the so-called "fast axis", and in the orthogonal direction, the so-called "slow axis", the beams pass the microlens uncollimated. In the far field of the integrated RGB light module this produces Gaussian beams with a large ellipticity which are required, e.g., for the application in autostereoscopic outdoor displays. For this application only very low optical output powers of a few milliwatts per laser diode are required and therefore we have developed tailored low-power laser diode chips with short cavity lengths of 250 μm for red and 300 μm for blue. Our RGB laser light module including the three laser diode chips, associated monitor photodiodes, the common microlens, as well as the hermetically sealed package has a total volume of only 0.45 cm³, which to our knowledge is the smallest RGB laser light source to date.

High power green lasers for gamma source

NASA Astrophysics Data System (ADS)

Durand, Magali; Sevillano, Pierre; Alexaline, Olivier; Sangla, Damien; Casanova, Alexis; Aubourg, Adrien; Saci, Abdelhak; Courjaud, Antoine

2018-02-01

A high intensity Gamma source is required for Nuclear Spectroscopy, it will be delivered by the interaction between accelerated electron and intense laser beams. Those two interactions lasers are based on a multi-stage amplification scheme that ended with a second harmonics generation to deliver 200 mJ, 5 ps pulses at 515 nm and 100 Hz. A t-Pulse oscillator with slow and fast feedback loop implemented inside the oscillator cavity allows the possibility of synchronization to an optical reference. A temporal jitter of 120 fs rms is achieved, integrated from 10 Hz to 10 MHz. Then a regenerative amplifier, based on Yb:YAG technology, pumped by fiber-coupled QCW laser diodes, delivers pulses up to 30 mJ. The 1 nm bandwidth was compressed to 1.5 ps with a good spatial quality: M2 of 1.1. This amplifier is integrated in a compact sealed housing (750 x 500 x 150 mm), which allows a pulse-pulse stability of 0.1 % rms, and a long-term stability of 1,9 % over 100 hours (with +/-1°C environment). The main amplification stage uses a cryocooled Yb:YAG crystal in an active mirror configuration. The crystal is cooled at 130 K via a compact and low-vibration cryocooler, avoiding any additional phase noise contribution, 340 mJ in a six pass scheme was achieved, with 0.9 of Strehl ratio. The trade off to the gain of a cryogenic amplifier is the bandwidth reduction, however the 1030 nm pulse was compressed to 4.4 ps. As for the regenerative amplifier a long-term stability of 1.9 % over 30 hours was achieved in an environment with +/-1°C temperature fluctuations The compression and Second Harmonics Generation Stages have allowed the conversion of 150 mJ of uncompressed infrared beam into 60 mJ at 515 nm.

Co-extruded mechanically tunable multilayer elastomer laser

NASA Astrophysics Data System (ADS)

Crescimanno, Michael; Mao, Guilin; Andrews, James; Singer, Kenneth; Baer, Eric; Hiltner, Anne; Song, Hyunmin; Shakya, Bijayandra

2011-04-01

We have fabricated and studied mechanically tunable elastomer dye lasers constructed in large area sheets by a single-step layer-multiplying co-extrusion process. The laser films consist of a central dye-doped (Rhodamine-6G) elastomer layer between two 128-layer distributed Bragg reflector (DBR) films comprised of alternating elastomer layers with different refractive indices. The central gain layer is formed by folding the coextruded DBR film to enclose a dye-doped skin layer. By mechanically stretching the elastomer laser film from 0% to 19%, a tunable miniature laser source was obtained with ˜50 nm continuous tunability from red to green.

Application of albumin protein and indocyanine green chromophore for tissue soldering by using an IR diode laser: ex vivo and in vivo studies.

PubMed

Khosroshahi, M E; Nourbakhsh, M S; Saremi, S; Hooshyar, A; Rabbani, Sh; Tabatabai, F; Anvari, M Sotudeh

2010-12-01

We sought to examine the impact of different parameters of laser soldering on the thermophysical properties of the skin and to optimize these parameters for sealing a full-thickness incision in the rat skin under closed feedback control under in vivo conditions. Laser tissue soldering based on protein as biologic glues and other compounds can provide greater bond strength and less collateral damage. Endogenous and exogenous materials such as indocyanine green (ICG) are often added to solders to enhance light absorption. In ex vivo study, the temperature increase, number of scan (Ns), and scan velocity (Vs) were investigated. In ex vivo studies, four skin incisions were made over rat dorsa and were closed by using two different methods: (a) wound closure by suture and (b) closure by using an automated temperature-controlled system. An automated soldering system was developed based on a diode laser, IR detector, photodiode, digital thermocouple, and camera. The true temperature of heated tissue was determined by using a calibration software method. The results showed that at each laser irradiance (I), the tensile strength (σ) of incisions repaired in the static mode is higher than in the dynamic mode. It must also be noted that the tensile strength of the repaired skin wound was increased by increasing the irradiance in both static and dynamic modes. However, in parallel, an increase in the corresponding temperature was observed. The tensile strength was measured for sutured and laser-soldered tissue after 2 to 10 postoperative days. Histopathologic studies showed a better healing and less inflammatory reactions than with those caused by standard sutures after day 7. It is demonstrated that automated laser soldering technique can be practical provided the optothermal properties of tissue is carefully optimized.

Alchemical and structural distribution based representation for universal quantum machine learning

NASA Astrophysics Data System (ADS)

Faber, Felix A.; Christensen, Anders S.; Huang, Bing; von Lilienfeld, O. Anatole

2018-06-01

We introduce a representation of any atom in any chemical environment for the automatized generation of universal kernel ridge regression-based quantum machine learning (QML) models of electronic properties, trained throughout chemical compound space. The representation is based on Gaussian distribution functions, scaled by power laws and explicitly accounting for structural as well as elemental degrees of freedom. The elemental components help us to lower the QML model's learning curve, and, through interpolation across the periodic table, even enable "alchemical extrapolation" to covalent bonding between elements not part of training. This point is demonstrated for the prediction of covalent binding in single, double, and triple bonds among main-group elements as well as for atomization energies in organic molecules. We present numerical evidence that resulting QML energy models, after training on a few thousand random training instances, reach chemical accuracy for out-of-sample compounds. Compound datasets studied include thousands of structurally and compositionally diverse organic molecules, non-covalently bonded protein side-chains, (H2O)40-clusters, and crystalline solids. Learning curves for QML models also indicate competitive predictive power for various other electronic ground state properties of organic molecules, calculated with hybrid density functional theory, including polarizability, heat-capacity, HOMO-LUMO eigenvalues and gap, zero point vibrational energy, dipole moment, and highest vibrational fundamental frequency.

Non-equilibrium Green's function calculation of AlGaAs-well-based and GaSb-based terahertz quantum cascade laser structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yasuda, H., E-mail: yasuda@nict.go.jp; Hosako, I.

2015-03-16

We investigate the performance of terahertz quantum cascade lasers (THz-QCLs) based on Al{sub x}Ga{sub 1−x}As/Al{sub y}Ga{sub 1−y}As and GaSb/AlGaSb material systems to realize higher-temperature operation. Calculations with the non-equilibrium Green's function method reveal that the AlGaAs-well-based THz-QCLs do not show improved performance, mainly because of alloy scattering in the ternary compound semiconductor. The GaSb-based THz-QCLs offer clear advantages over GaAs-based THz-QCLs. Weaker longitudinal optical phonon–electron interaction in GaSb produces higher peaks in the spectral functions of the lasing levels, which enables more electrons to be accumulated in the upper lasing level.

Laser-Bioplasma Interaction: The Blood Type Transmutation Induced by Multiple Ultrashort Wavelength Laser Beams

NASA Astrophysics Data System (ADS)

Stefan, V. Alexander

2015-11-01

The interaction of ultrashort wavelength multi laser beams with the flowing blood thin films leads to the transmutation of the blood types A, B, and AB into O type. This is a novel mechanism of importance for the transfusion medicine. Laser radiation is in resonance with the eigen-frequency modes of the antigen proteins and forces the proteins to parametrically oscillate until they get kicked out from the surface. The stripping away of antigens is done by the scanning-multiple-lasers of a high repetition rate in the blue-purple frequency domain. The guiding-lasers are in the red-green frequency domain. The laser force, (parametric interaction with the antigen eigen-oscillation), upon the antigen protein molecule must exceed its weight. The scanning laser beam is partially reflected as long as the antigen(s) is not eliminated. The process of the protein detachment can last a few minutes. Supported by Nikola Tesla Labs., Stefan University.

Second-harmonic generation of a dual-frequency laser in a MgO:PPLN crystal.

PubMed

Kang, Ying; Yang, Suhui; Brunel, Marc; Cheng, Lijun; Zhao, Changming; Zhang, Haiyang

2017-04-10

A dual-frequency CW laser at a wavelength of 1.064 μm is frequency doubled in a MgO:PPLN nonlinear crystal. The fundamental dual-frequency laser has a tunable beat note from 125 MHz to 175 MHz. A laser-diode pumped fiber amplifier is used to amplify the dual-frequency fundamental output to a maximum power of 50 W before frequency doubling. The maximum output power of the green light is 1.75 W when the input fundamental power is 12 W, corresponding to a frequency doubling efficiency of 14.6%. After frequency doubling, green light with modulation frequencies in two bands from 125 MHz to 175 MHz and from 250 MHz to 350 MHz is achieved simultaneously. The relative intensities of the beat notes at the two bands can be adjusted by changing the relative intensities at different frequencies of the fundamental light. The spectral width and frequency stabilities of the beat notes in fundamental wave and green light are also measured, respectively. The modulated green light has potential applications in underwater ranging, communication, and imaging.

Single transverse mode protein laser

NASA Astrophysics Data System (ADS)

Dogru, Itir Bakis; Min, Kyungtaek; Umar, Muhammad; Bahmani Jalali, Houman; Begar, Efe; Conkar, Deniz; Firat Karalar, Elif Nur; Kim, Sunghwan; Nizamoglu, Sedat

2017-12-01

Here, we report a single transverse mode distributed feedback (DFB) protein laser. The gain medium that is composed of enhanced green fluorescent protein in a silk fibroin matrix yields a waveguiding gain layer on a DFB resonator. The thin TiO2 layer on the quartz grating improves optical feedback due to the increased effective refractive index. The protein laser shows a single transverse mode lasing at the wavelength of 520 nm with the threshold level of 92.1 μJ/ mm2.

Binding of indocyanine green in polycaprolactone fibers using blend electrospinning for in vivo laser-assisted vascular anastomosis.

PubMed

Schönfeld, Annemarie; Kabra, Zacharia Mbäıdjol; Constantinescu, Mihai; Bosshardt, Dieter; Stoffel, Michael H; Peters, Kirsten; Frenz, Martin

2017-12-01

The clinical application of laser-assisted vascular anastomosis is afflicted by unreliable and low bonding strengths as well as tedious handling during microvascular surgery. The challenge to be met arises from the flow-off of the chromophore during soldering that changes the absorption and stains the surrounding tissue, leading to an uncontrollable thermal damage zone. In this study, we investigated the feasibility to produce an indocyanine green (ICG)-loaded patch by electrospinning and tested its applicability to both in vitro and in vivo microvascular laser soldering. A blend of polycaprolactone and ICG was electrospun to produce a pliable patch. Prior to soldering, the patch was soaked in 40% wt. bovine serum albumin solution. The solder patch was wrapped in vitro around blood vessel stumps of rabbit aortas. An intraluminal balloon catheter enabled an easy alignment and held the setup in place. The soldering energy was delivered via a diffusor fiber from the vessel lumen using a diode laser at 810 nm. During the procedure, the surface temperature was observed with an infrared camera. Afterward, samples were embedded in methylmethacrylate and epon to study thermal damage. The quality of the fusion was assessed by measuring the tensile strength. After in vitro tests with rabbit aortas, eight large white pigs were subjected to an acute in vivo experiment, and the artery of the latissimus dorsi flap was anastomosed to the distal femoral artery. The ICG-loaded patch, produced by electrospinning, has a thickness of 279 ± 62 μm, a fiber diameter of 1.20 ± 0.19 μm, and an attenuation coefficient of 1,119 ± 183 cm -1 at a wavelength of 790 nm. The patch was pliable and easy to handle during surgery. No leakage of the chromophore was observed. Thermal damage was restricted to the Tunica adventitia and Tunica media and the area of the vessel wall that was covered with the patch. Six pigs were successfully treated, without any bleeding and with

High laser efficiency and photostability of pyrromethene dyes mediated by nonpolar solvent.

PubMed

Gupta, Monika; Kamble, Priyadarshini; Rath, M C; Naik, D B; Ray, Alok K

2015-08-10

Many pyrromethene (PM) dyes have been shown to outperform established rhodamine dyes in terms of laser efficiency in the green-yellow spectral region, but their rapid photochemical degradation in commonly used ethanol or methanol solvents continues to limit its use in high average power liquid dye lasers. A comparative study on narrowband laser efficiency and photostability of commercially available PM567 and PM597 dyes, using nonpolar n-heptane and 1,4-dioxane and polar ethanol solvents, was carried out by a constructed pulsed dye laser, pumped by the second harmonic (532 nm) radiation of a Q-switched Nd:YAG laser. Interestingly, both nonpolar solvents showed a significantly higher laser photostability (∼100 times) as well as peak efficiency (∼5%) of these PM dyes in comparison to ethanol. The different photostability of the PM dyes was rationalized by determining their triplet-state spectra and capability to generate reactive singlet oxygen (O₂1) by energy transfer to dissolved oxygen in these solvents using pulse radiolysis. Heptane is identified as a promising solvent for these PM dyes for use in high average power dye lasers, pumped by copper vapor lasers or diode-pumped solid-state green lasers.

Temperature and Snowfall in Western Queen Maud Land Increasing Faster Than Climate Model Projections

NASA Astrophysics Data System (ADS)

Medley, B.; McConnell, J. R.; Neumann, T. A.; Reijmer, C. H.; Chellman, N.; Sigl, M.; Kipfstuhl, S.

2018-02-01

East Antarctic Ice Sheet (EAIS) mass balance is largely driven by snowfall. Recently, increased snowfall in Queen Maud Land led to years of EAIS mass gain. It is difficult to determine whether these years of enhanced snowfall are anomalous or part of a longer-term trend, reducing our ability to assess the mitigating impact of snowfall on sea level rise. We determine that the recent snowfall increases in western Queen Maud Land (QML) are part of a long-term trend (+5.2 ± 3.7% decade-1) and are unprecedented over the past two millennia. Warming between 1998 and 2016 is significant and rapid (+1.1 ± 0.7°C decade-1). Using these observations, we determine that the current accumulation and temperature increases in QML from an ensemble of global climate simulations are too low, which suggests that projections of the QML contribution to sea level rise are potentially overestimated with a reduced mitigating impact of enhanced snowfall in a warming world.

Temperature and Snowfall in Western Queen Maud Land Increasing Faster than Climate Model Projections

NASA Technical Reports Server (NTRS)

Medley, B.; McConnell, J. R.; Neumann, T. A.; Reijmer, C. H.; Chellman, N.; Sigl, M.; Kipfstuhl, S.

2017-01-01

East Antarctic Ice Sheet (EAIS) mass balance is largely driven by snowfall. Recently, increased snowfall in Queen Maud Land led to years of EAIS mass gain. It is difficult to determine whether these years of enhanced snowfall are anomalous or part of a longer-term trend, reducing our ability to assess the mitigating impact of snowfall on sea level rise. We determine that the recent snowfall increases in western Queen Maud Land (QML) are part of a long-term trend (+5.2 +/- 3.7% decade(exp -1)) and are unprecedented over the past two millennia. Warming between 1998 and 2016 is significant and rapid (+1.1 +/- 0.7 C decade(exp -1)). Using these observations, we determine that the current accumulation and temperature increases in QML from an ensemble of global climate simulations are too low, which suggests that projections of the QML contribution to sea level rise are potentially overestimated with a reduced mitigating impact of enhanced snowfall in a warming world.

Applications of spaceborne laser ranger on EOS

NASA Technical Reports Server (NTRS)

Degnan, John J.; Cohen, Steven C.

1988-01-01

An account is given of the design concept and potential applications in science and engineering of the spaceborne laser ranging and altimeter apparatus employed by the Geodynamics Laser Ranging System; this is scheduled for 1997 launch as part of the multiple-satellite Earth Observing System. In the retrograding mode for geodynamics, the system will use a Nd:YAG laser's green and UV output for distance determination to ground retroreflectors. Engineering applications encompass land management and long-term ground stability studies relevant to nuclear power plant, pipeline, and aqueduct locations.

Stem Cell Physics. Laser Manipulation of Blood Types: Laser-Stripping-Away of Red Blood Cell Surface Antigens

NASA Astrophysics Data System (ADS)

Stefan, V. Alexander

2014-03-01

A novel mechanism of importance for the transfusion medicine[2] is proposed. The interaction of ultrashort wavelength multilaser beams with the flowing blood thin films can lead to a conversion of blood types A, B, and AB into O type.[3] The stripping away of antigens is done by the scanning-multiple-lasers of a high repetition rate in the blue-purple frequency domain. The guiding-lasers are in the red-green frequency domain. The laser force, (parametric interaction with the antigen eigen-oscillation),[4] upon the antigen protein molecule must exceed its weight. Supported by Nikola Tesla Labs, La Jolla, CA.

Fiber-laser-based, green-pumped, picosecond optical parametric oscillator using fan-out grating PPKTP.

PubMed

Chaitanya Kumar, S; Parsa, S; Ebrahim-Zadeh, M

2016-01-01

We report a stable, Yb-fiber-laser-based, green-pumped, picosecond optical parametric oscillator (OPO) for the near-infrared based on periodically poled potassium titanyl phosphate (PPKTP) nonlinear crystal, using fan-out grating design and operating near room temperature. The OPO is continuously tunable across 726-955 nm in the signal and 1201-1998 nm in the idler, resulting in a total signal plus idler wavelength coverage of 1026 nm by grating tuning at a fixed temperature. The device generates up to 580 mW of average power in the signal at 765 nm and 300 mW in the idler at 1338 nm, with an overall extraction efficiency of up to 52% and a pump depletion >76%. The extracted signal at 765 nm and idler at 1746 nm exhibit excellent passive power stability better than 0.5% and 0.8% rms, respectively, over 1 h with good beam quality in TEM₀₀ mode profile. The output signal pulses have a Gaussian temporal duration of 13.2 ps, with a FWHM spectral bandwidth of 3.4 nm at 79.5 MHz repetition rate. Power scaling limitations of the OPO due to the material properties of PPKTP are studied.

Green frequency-doubled laser-beam propagation in high-temperature hohlraum plasmas.

PubMed

Niemann, C; Berger, R L; Divol, L; Froula, D H; Jones, O; Kirkwood, R K; Meezan, N; Moody, J D; Ross, J; Sorce, C; Suter, L J; Glenzer, S H

2008-02-01

We demonstrate propagation and small backscatter losses of a frequency-doubled (2omega) laser beam interacting with inertial confinement fusion hohlraum plasmas. The electron temperature of 3.3 keV, approximately a factor of 2 higher than achieved in previous experiments with open geometry targets, approaches plasma conditions of high-fusion yield hohlraums. In this new temperature regime, we measure 2omega laser-beam transmission approaching 80% with simultaneous backscattering losses of less than 10%. These findings suggest that good laser coupling into fusion hohlraums using 2omega light is possible.

Compact diode laser source for multiphoton biological imaging

PubMed Central

Niederriter, Robert D.; Ozbay, Baris N.; Futia, Gregory L.; Gibson, Emily A.; Gopinath, Juliet T.

2016-01-01

We demonstrate a compact, pulsed diode laser source suitable for multiphoton microscopy of biological samples. The center wavelength is 976 nm, near the peak of the two-photon cross section of common fluorescent markers such as genetically encoded green and yellow fluorescent proteins. The laser repetition rate is electrically tunable between 66.67 kHz and 10 MHz, with 2.3 ps pulse duration and peak powers >1 kW. The laser components are fiber-coupled and scalable to a compact package. We demonstrate >600 μm depth penetration in brain tissue, limited by laser power. PMID:28101420

Controlling a microdisk laser by local refractive index perturbation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liew, Seng Fatt; Redding, Brandon; Cao, Hui, E-mail: hui.cao@yale.edu

2016-02-01

We demonstrate a simple yet effective approach of controlling lasing in a semiconductor microdisk by photo-thermal effect. A continuous wave green laser beam, focused onto the microdisk perimeter, can enhance or suppress lasing in different cavity modes, depending on the position of the focused beam. Its main effect is a local modification of the refractive index of the disk, which results in an increase in the power slope of some lasing modes and a decrease of others. The boundary roughness breaks the rotational symmetry of a circular disk, allowing the lasing process to be tuned by varying the green beammore » position. Using the same approach, we can also fine tune the relative intensity of a quasi-degenerate pair of lasing modes. Such post-fabrication control, enabled by an additional laser beam, is flexible and reversible, thus enhancing the functionality of semiconductor microdisk lasers.« less

Concepts and performance of solid state RGB laser sources for large-frame laser projection displays

NASA Astrophysics Data System (ADS)

Nebel, Achim; Wallenstein, Richard E.

2000-04-01

We report on concepts and the performance of diode pumped solid state laser systems which generate simultaneously red (R), green (G) and blue (B) laser light with output powers of up to 7.1 W at 629 nm, 6.9 W at 532 nm and 5.0 W at 446 nm. The superposition of this RGB radiation provides white light with a power of 19 W. In respect to the diode pump power of 110 W the RGB output corresponds to an optical efficiency of 17%.

Analysis of the optical characteristics of adipose tissue in vitro sensitized by indocyanine green and exposed to IR-laser irradiation

NASA Astrophysics Data System (ADS)

Yanina, I. Yu.; Doubrovski, V. A.; Tuchin, V. V.

2015-03-01

The effect of IR-laser irradiation on adipose tissue sensitized by indocyanine green is studied in vitro. Experiments and statistical analysis are used to show that wavelength-selective irradiation leads to an increase in the homogeneity of optical images of adipose cells with time. The transmission coefficient that is averaged over the image area weakly depends on the observation time. An increase in the homogeneity of images is interpreted as a result of immersion of optical inhomogeneities of tissue owing to the intracellular liquid that is released through the photochemically induced pores in cellular membranes. An increase in the optical homogeneity of the medium is compensated for by a decrease in the transmission coefficient of the sensitizer, which is manifested as a weak time dependence of the image-averaged transmittance of tissue.

Design and fabrication of dichroic mirrors for color separation and recombination of the Kr-Ar laser (white laser)

NASA Astrophysics Data System (ADS)

Park, Jungho; Park, Youngjun; Hwang, Young M.

1997-10-01

Cut-off filters reject all the radiation below and transmit all the above a certain wavelength and vice versa. In this paper, we will study the design and fabrication of a short wave pass or a long wave pass dichroic mirrors for color separation and recombination from the R.G.B. color beam source. In the laser display system, color separation and recombination is very important. We designed the coating layers so that the best performance may be obtained from a 45 degree incident s-polarized light. The following fabrication specification is satisfied in our color separation/recombination of the Kr-Ar laser source. The first dichroic mirror for the blue color separation, maximized on reflectance and transmittance as R > 99% in the blue regions (400 approximately 490 nm) and T > 90% in the green and red region (510 approximately 700 nm). The second dichroic mirror for the color recombination maximized the reflectance and transmittance as R > 99% in the range of 510 approximately 700 nm and T > 90% in the blue color region. In the third dichroic mirror for which it used the color separation and recombination of the green and red simultaneously, maximized the reflectance and transmittance as R > 99% in the green region (510 approximately 560 nm) and T > 90% in the red region. These fabricated mirrors were applied in our laser display projection system. We obtained an excellent result.

Practical internal combustion engine laser spark plug development

NASA Astrophysics Data System (ADS)

Myers, Michael J.; Myers, John D.; Guo, Baoping; Yang, Chengxin; Hardy, Christopher R.

2007-09-01

Fundamental studies on laser ignition have been performed by the US Department of Energy under ARES (Advanced Reciprocating Engines Systems) and by the California Energy Commission under ARICE (Advanced Reciprocating Internal Combustion Engine). These and other works have reported considerable increases in fuel efficiencies along with substantial reductions in green-house gas emissions when employing laser spark ignition. Practical commercial applications of this technology require low cost high peak power lasers. The lasers must be small, rugged and able to provide stable laser beam output operation under adverse mechanical and environmental conditions. New DPSS (Diode Pumped Solid State) lasers appear to meet these requirements. In this work we provide an evaluation of HESP (High Efficiency Side Pumped) DPSS laser design and performance with regard to its application as a practical laser spark plug for use in internal combustion engines.

Laser tissue welding in ophthalmic surgery.

PubMed

Rossi, Francesca; Matteini, Paolo; Ratto, Fulvio; Menabuoni, Luca; Lenzetti, Ivo; Pini, Roberto

2008-09-01

Laser welding of ocular tissues is an alternative technique or adjunct to conventional suturing in ophthalmic surgery. It is based on the photothermal interaction of laser light with the main components of the extracellular matrix of connective tissues. The advantages of the welding procedure with respect to standard suturing and stapling are reduced operation times, lesser inflammation, faster healing and increased ability to induce tissue regeneration. The procedure we set up is based on the use of an infrared diode laser in association with the topical application of the chromophore Indocyanine Green. Laser light may be delivered either continuously or in pulses, thus identifying two different techniques that have been applied clinically in various types of transplants of the cornea.

A Plasma Ultraviolet Source for Short Wavelength Lasers.

DTIC Science & Technology

1988-04-15

plasma focus (DPF) device was evaluated for the feasibility of blue-green and near ultraviolet laser pumping. As the result of optimizing the operating conditions of DPF and laser system, the maximum untuned laser output exceeded 4.0mJ corresponding to the energy density 8.3J/liter which is much higher than the typical flashlamp dye laser. The spectral irradiance of DPF at the absorption bands for LD390 and LD490 were 5.5W/sq cm-nm, 0.3W.sq cm-nm, respectively. Due to the lower pump power of DPF at 355nm than the threshold of LD390, the laser pumping of LD390 dye was not

Solid state laser technology - A NASA perspective

NASA Technical Reports Server (NTRS)

Allario, F.

1985-01-01

NASA's program for developing solid-state laser technology and applying it to the Space Shuttle and Space Platform is discussed. Solid-state lasers are required to fulfill the Earth Observation System's requirements. The role of the Office of Aeronautics and Space Technology in developing a NASA tunable solid-state laser program is described. The major goals of the program involve developing a solid-state pump laser in the green, using AlGaAs array technology, pumping a Nd:YAG/SLAB crystal or glass, and fabricating a lidar system, with either a CO2 laser at 10.6 microns or a Nd:YAG laser at 1.06 microns, to measure tropospheric winds to an accuracy of + or - 1 m/s and a vertical resolution of 1 km. The procedures to be followed in order to visualize this technology plan include: (1) material development and characterization, (2) laser development, and (3) implementation of the lasers.

Review of Laser Ablation Process for Single Wall Carbon Nanotube Production

NASA Technical Reports Server (NTRS)

Arepalli, Sivaram

2003-01-01

Different types of lasers are now routinely used to prepare single wall carbon nanotubes (SWCNTs). The original method developed by researchers at Rice University utilized a "double pulse laser oven" process. A graphite target containing about 1 atomic percent of metal catalysts is ablated inside a 1473K oven using laser pulses (10 ns pulse width) in slow flowing argon. Two YAG lasers with a green pulse (532 nm) followed by an IR pulse (1064 nm) with a 50 ns delay are used for ablation. This set up produced single wall carbon nanotube material with about 70% purity having a diameter distribution peaked around 1.4 nm. The impurities consist of fullerenes, metal catalyst clusters (10 to 100 nm diameter) and amorphous carbon. The rate of production with the initial set up was about 60 mg per hour with 10Hz laser systems. Several researchers have used variations of the lasers to improve the rate, consistency and study effects of different process parameters on the quality and quantity of SWCNTs. These variations include one to three YAG laser systems (Green, Green and IR), different pulse widths (nano to microseconds as well as continuous) and different laser wavelengths (Alexandrite, CO, CO2, free electron lasers in the near to far infrared). It is noted that yield from the single laser (Green or IR) systems is only a fraction of the two laser systems. The yield seemed to scale up with the repetition rate of the laser systems (10 to 60 Hz) and depended on the beam uniformity and quality of the laser pulses. The shift to longer wavelength lasers (free electron, CO and CO2) did not improve the quality, but increased the rate of production because these lasers are either continuous (CW) or high repetition rate pulses (kHz to MHz). The average power and the peak power of the lasers seem to influence the yields. Very high peak powers (MegaWatts per square centimeter) are noted to increase ablation of bigger particles with reduced yields of SWCNTs. Increased average powers

Efficacy of corneal eye shields in protecting patients' eyes from laser irradiation.

PubMed

Russell, S W; Dinehart, S M; Davis, I; Flock, S T

1996-07-01

The continuing development of new types and applications of lasers has appeared to surpass the development of specific eye protection for these lasers. There are a variety of eye shields on the market, but few are specifically designed for laser protection. Our purpose was to test a variety of eye shields by two parameters, light transmission and temperature rise, and to determine from these measurements the most protective shield for patients. We tested four plastic shields, one metal shield, and two sets of tanning goggles for temperature rise and light transmission when irradiated with a beam from a flashlamp-pumped, pulsed-dye laser. The temperature rise at the surface of the shield opposite the laser impacts was no more than 0.2 degree C in any case. White light was transmitted at significant levels through several of the shields, but yellow light transmittance was noted only through the green eye shield. Our measurements indicate that all except the green shield appeared safe from transmission of the 585-nm radiant energy. However, the optimal laser eye shield, in our opinion, would be a composite of several different shields' characteristics.

Visible light surface emitting semiconductor laser

DOEpatents

Olbright, Gregory R.; Jewell, Jack L.

1993-01-01

A vertical-cavity surface-emitting laser is disclosed comprising a laser cavity sandwiched between two distributed Bragg reflectors. The laser cavity comprises a pair of spacer layers surrounding one or more active, optically emitting quantum-well layers having a bandgap in the visible which serve as the active optically emitting material of the device. The thickness of the laser cavity is m .lambda./2n.sub.eff where m is an integer, .lambda. is the free-space wavelength of the laser radiation and n.sub.eff is the effective index of refraction of the cavity. Electrical pumping of the laser is achieved by heavily doping the bottom mirror and substrate to one conductivity-type and heavily doping regions of the upper mirror with the opposite conductivity type to form a diode structure and applying a suitable voltage to the diode structure. Specific embodiments of the invention for generating red, green, and blue radiation are described.

GaN-based photon-recycling green light-emitting diodes with vertical-conduction structure.

PubMed

Sheu, Jinn-Kong; Chen, Fu-Bang; Yen, Wei-Yu; Wang, Yen-Chin; Liu, Chun-Nan; Yeh, Yu-Hsiang; Lee, Ming-Lun

2015-04-06

A p-i-n structure with near-UV(n-UV) emitting InGaN/GaN multiple quantum well(MQW) structure stacked on a green unipolar InGaN/GaN MQW was epitaxially grown at the same sapphire substrate. Photon recycling green light-emitting diodes(LEDs) with vertical-conduction feature on silicon substrates were then fabricated by wafer bonding and laser lift-off techniques. The green InGaN/GaN QWs were pumped with n-UV light to reemit low-energy photons when the LEDs were electrically driven with a forward current. Efficiency droop is potentially insignificant compared with the direct green LEDs due to the increase of effective volume of active layer in the optically pumped green LEDs, i.e., light emitting no longer limited in the QWs nearest to the p-type region to cause severe Auger recombination and carrier overflow losses.

Greens of the European Green Capitals

NASA Astrophysics Data System (ADS)

Cömertler, Seval

2017-10-01

Well established and maintained green areas have a key role on reaching the high quality of life and sustainability in urban environments. Therefore, green areas must be carefully accounted and evaluated in the urban planning affairs. In this context, the European Green Capitals, which attach a great importance to the green areas, have a great potential to act as a role model for both small and big cities in all around the world. These leading cities (chronologically, Stockholm, Hamburg, Vitoria-Gasteiz, Nantes, Copenhagen, Bristol, Ljubljana, Essen and Nijmegen) are inspiring for the other cities which seek to achieve more sustainable and environmentally friendly places through green areas. From this point of view, the aim of this paper was to investigate the green areas of the European Green Capitals. The paper covered whole European Green Capitals, and the application form of each Green Capital was used as a primary data source. Consequently, the paper put forwarded that the European Green Capitals have considerably large amount and high proportion of green areas. Further, these cities provide an excellent access to the public green areas. As a result of abundant provision and proper distribution, the almost all citizens in most of the Green Capitals live within a distance of 300 meters to a green area. For further researches, the paper suggested that these green capitals should be investigated in terms of their efforts, measures, goals and plans, policies and implications to administer, to protect, to enhance and to expand the green areas.

Full color laser projection display using Kr-Ar laser (white laser) beam-scanning technology

NASA Astrophysics Data System (ADS)

Kim, Yonghoon; Lee, Hang W.; Cha, Seungnam; Lee, Jin-Ho; Park, Youngjun; Park, Jungho; Hong, Sung S.; Hwang, Young M.

1997-07-01

Full color laser projection display is realized on the large screen using a krypton-argon laser (white laser) as a light source, and acousto-optic devices as light modulators. The main wavelengths of red, green and blue color are 647, 515, and 488 nm separated by dichroic mirrors which are designed to obtain the best performance for the s-polarized beam with the 45 degree incident angle. The separated beams are modulated by three acousto-optic modulators driven by rf drivers which has energy level of 1 watt at 144 MHz and recombined by dichroic mirrors again. Acousto-optic modulators (AOM) are fabricated to satisfy high diffraction efficiency over 80% and fast rising time less than 50 ns at the video bandwidth of 5 MHz. The recombined three beams (RGB) are scanned by polygonal mirrors for horizontal lines and a galvanometer for vertical lines. The photodiode detection for monitoring of rotary polygonal mirrors is adopted in this system for the compensation of the tolerance in the mechanical scanning to prevent the image joggling in the horizontal direction. The laser projection display system described in this paper is expected to apply HDTV from the exploitation of the acousto- optic modulator with the video bandwidth of 30 MHz.

Nanowire lasers as intracellular probes.

PubMed

Wu, Xiaoqin; Chen, Qiushu; Xu, Peizhen; Chen, Yu-Cheng; Wu, Biming; Coleman, Rhima M; Tong, Limin; Fan, Xudong

2018-05-24

We investigate a cadmium sulfide (CdS) nanowire (NW) laser that is spontaneously internalized into a single cell to serve as a stand-alone intracellular probe. By pumping with nano-joule light pulses, green laser emission (500-520 nm) can be observed inside cells with a peak linewidth as narrow as 0.5 nm. Due to the sub-micron diameter (∼200 nm), the NW has an appreciable fraction of the evanescent field outside, facilitating a sensitive detection of cellular environmental changes. By monitoring the lasing peak wavelength shift in response to the intracellular refractive index change, our NW laser probe shows a sensitivity of 55 nm per RIU (refractive index units) and a figure of merit of approximately 98.

Infrared-laser-based fundus angiography

NASA Astrophysics Data System (ADS)

Klingbeil, Ulrich; Canter, Joseph M.; Lesiecki, Michael L.; Reichel, Elias

1994-06-01

Infrared fundus angiography, using the fluorescent dye indocyanine green (ICG), has shown great potential in delineating choroidal neovascularization (CNV) otherwise not detectable. A digital retinal imaging system containing a diode laser for illumination has been developed and optimized to perform high sensitivity ICG angiography. The system requires less power and generates less pseudo-fluorescence background than nonlaser devices. During clinical evaluation at three retinal centers more than 200 patients, the majority of which had age-related macular degeneration, were analyzed. Laser based ICG angiography was successful in outlining many of the ill-defined or obscure CNV as defined by fluorescein angiography. The procedure was not as successful with classic CNV. ICG angiograms were used to prepare and guide laser treatment.

Health-friendly high-quality white light using violet-green-red laser and InGaN nanowires-based true yellow nanowires light-emitting diodes

NASA Astrophysics Data System (ADS)

Janjua, Bilal; Ng, Tien K.; Zhao, Chao; Anjum, Dalaver H.; Prabaswara, Aditya; Consiglio, Giuseppe Bernardo; Shen, Chao; Ooi, Boon S.

2017-02-01

White light based on blue laser - YAG: Ce3+ phosphor has the advantage of implementing solid-state lighting and optical wireless communications combined-functionalities in a single lamp. However, the blue light was found to disrupt melatonin production, and therefore the human circadian rhythm in general; while the yellow phosphor is susceptible to degradation by laser irradiation and also lack tunability in color rendering index (CRI). In this investigation, by using a violet laser, which has 50% less impact on circadian response, as compared to blue light, and an InGaN-quantum-disks nanowires-based light-emitting diode (NWs-LED), we address both issues simultaneously. The white light is therefore generated using violet-green-red lasers, in conjunction with a yellow NWs-LED realized using molecular beam epitaxy technique, on titanium-coated silicon substrates. Unlike the conventional quantum-well-based LED, the NWs-LED showed efficiency-droop free behavior up to 9.8 A/cm2 with peak output power of 400 μW. A low turn-on voltage of 2.1 V was attributed to the formation of conducting titanium nitride layer at NWs nucleation site and improved fabrication process in the presence of relatively uniform height distribution. The 3D quantum confinement and the reduced band bending improve carriers-wavefunctions overlap, resulting in an IQE of 39 %. By changing the relative intensities of the individual color components, CRI of >85 was achieved with tunable correlated color temperature (CCT), thus covering the desired room lighting conditions. Our architecture provides important considerations in designing smart solid-state lighting while addressing the harmful effect of blue light.

Pulsed laser-induced damage of metals at 492 nm.

PubMed

Marrs, C D; Faith, W N; Dancy, J H; Porteus, J O

1982-11-15

A triaxial flashlamp-pumped dye laser has been used to perform laser damage testing of metal surfaces in the blue-green spectral region. Using LD490 laser dye, the laser produces 0.18-J, 0.5-microsec pulses at 492 nm. The spatial profile of the focused beam is measured in orthogonal directions in the plane of the sample surface. The orthogonal profiles are flat-topped Gaussians with 1/e(2) widths of 270 microm. Multithreshold laser damage test results are presented for polished Mo, diamond-turned high-purity Al alloy, diamond-turned bulk Cu, and diamond-turned electrodeposits of Ag and Au on Cu. Comparisons are made between calculated and experimentally measured slip and melt thresholds.

Intracavity frequency doubling of a continuous-wave, diode-laser-pumped neodymium lanthanum scandium borate laser.

PubMed

Meyn, J P; Huber, G

1994-09-15

Neodymium-doped lanthanum scandium borate [Nd:LaSc(3)(BO(3))(4)] is a new material for efficient and compact diode-pumped solid-state lasers. A simple plane-plane 3-mm-long resonator is formed by a coated Nd(10%):LaSc(3)(BO(3))(4) crystal and a coated potassium titanyl phosphate (KTP) crystal. The second-harmonic output power at 531 nm is 522 mW at 2.05-W incident pump power of the diode laser. The corresponding optical efficiency is 25%, and the conversion efficiency from the fundamental to the second harmonic is 55%. The wellknown chaotic power fluctuations of intracavity frequency-doubled lasers (green problem) are avoided by use of a short KTP crystal, between 0.5 and 2 mm in length.

Green, yellow and bright red (In,Ga,Al)P-GaP diode lasers grown on high-index GaAs substrates

NASA Astrophysics Data System (ADS)

Ledentsov, N. N.; Shchukin, V. A.; Shernyakov, Yu. M.; Kulagina, M. M.; Payusov, A. S.; Gordeev, N. Yu.; Maximov, M. V.; Cherkashin, N. A.

2017-02-01

Low threshold current density (<400 A/cm2) injection lasing in (AlxGa1-x)0.5In0.5P-GaAs-based diodes down to the green spectral range (<570 nm) is obtained. The epitaxial structures are grown on high-index (611)A and (211)A GaAs substrates by metal-organic vapor phase epitaxy and contain tensile-strained GaP-enriched insertions aimed at preventing escape of the injected nonequilibrium electrons from the active region. Extended waveguide concept results in a vertical beam divergence with a full width at half maximum of 15o for (611)A substrates. The lasing at 569 nm is realized at 85 K. In the orange-red laser diode structure low threshold current density (200 A/cm2) in the orange spectral range (598 nm) is realized at 85 K. The latter devices demonstrate room temperature lasing at 628 nm at 2 kA/cm2 and a total power above 3W. The red laser diodes grown on (211)A substrates demonstrate vertically multimode lasing far field pattern indicating a lower optical confinement factor for the fundamental mode as compared to the devices grown on (611)A. However the temperature stability of the threshold current and the wavelength stability are significantly higher for (211)A-grown structures in agreement with the conduction band modeling data.

Progress and prospects of GaN-based VCSEL from near UV to green emission

NASA Astrophysics Data System (ADS)

Yu, Hsin-chieh; Zheng, Zhi-wei; Mei, Yang; Xu, Rong-bin; Liu, Jian-ping; Yang, Hui; Zhang, Bao-ping; Lu, Tien-chang; Kuo, Hao-chung

2018-01-01

GaN is a great material for making optoelectronic devices in the blue, blue-violet and green bands. Vertical-cavity surface-emitting lasers (VCSELs) have many advantages including small footprint, circular symmetry of output beam, two-dimensional scalability and/or addressability, surface-mount packaging, good price-performance ratio, and simple optics/alignment for output coupling. In this paper, we would like to (1) Review the design and fabrication of GaN-based VCSELs including some technology challenges, (2) Discuss the design and metalorganic chemical vapor deposition (MOCVD) growth of electrically pumped blue VCSELs and (3) Demonstrate world first green VCSEL using quantum dots (QDs) active region to overcome the 'green gap'.

Comparing quantitative values of two generations of laser-assisted indocyanine green dye angiography systems: can we predict necrosis?

PubMed

Phillips, Brett T; Fourman, Mitchell S; Rivara, Andrew; Dagum, Alexander B; Huston, Tara L; Ganz, Jason C; Bui, Duc T; Khan, Sami U

2014-01-01

Several devices exist today to assist the intraoperative determination of skin flap perfusion. Laser-Assisted Indocyanine Green Dye Angiography (LAICGA) has been shown to accurately predict mastectomy skin flap necrosis using quantitative perfusion values. The laser properties of the latest LAICGA device (SPY Elite) differ significantly from its predecessor system (SPY 2001), preventing direct translation of previous published data. The purpose of this study was to establish a mathematical relationship of perfusion values between these 2 devices. Breast reconstruction patients were prospectively enrolled into a clinical trial where skin flap evaluation and excision was based on quantitative SPY Q values previously established in the literature. Initial study patients underwent mastectomy skin flap evaluation using both SPY systems simultaneously. Absolute perfusion unit (APU) values at identical locations on the breast were then compared graphically. 210 data points were identified on the same patients (n = 4) using both SPY systems. A linear relationship (y = 2.9883x + 12.726) was identified with a high level or correlation (R(2) = 0.744). Previously published values using SPY 2001 (APU 3.7) provided a value of 23.8 APU on the SPY Elite. In addition, postoperative necrosis in these patients correlated to regions of skin identified with the SPY Elite with APU less than 23.8. Intraoperative comparison of LAICGA systems has provided direct correlation of perfusion values predictive of necrosis that were previously established in the literature. An APU value of 3.7 from the SPY 2001 correlates to a SPY Elite APU value of 23.8.

Comparing Quantitative Values of Two Generations of Laser-Assisted Indocyanine Green Dye Angiography Systems: Can We Predict Necrosis?

PubMed Central

Fourman, Mitchell S.; Rivara, Andrew; Dagum, Alexander B.; Huston, Tara L.; Ganz, Jason C.; Bui, Duc T.; Khan, Sami U.

2014-01-01

Objective: Several devices exist today to assist the intraoperative determination of skin flap perfusion. Laser-Assisted Indocyanine Green Dye Angiography (LAICGA) has been shown to accurately predict mastectomy skin flap necrosis using quantitative perfusion values. The laser properties of the latest LAICGA device (SPY Elite) differ significantly from its predecessor system (SPY 2001), preventing direct translation of previous published data. The purpose of this study was to establish a mathematical relationship of perfusion values between these 2 devices. Methods: Breast reconstruction patients were prospectively enrolled into a clinical trial where skin flap evaluation and excision was based on quantitative SPY Q values previously established in the literature. Initial study patients underwent mastectomy skin flap evaluation using both SPY systems simultaneously. Absolute perfusion unit (APU) values at identical locations on the breast were then compared graphically. Results: 210 data points were identified on the same patients (n = 4) using both SPY systems. A linear relationship (y = 2.9883x + 12.726) was identified with a high level or correlation (R2 = 0.744). Previously published values using SPY 2001 (APU 3.7) provided a value of 23.8 APU on the SPY Elite. In addition, postoperative necrosis in these patients correlated to regions of skin identified with the SPY Elite with APU less than 23.8. Conclusion: Intraoperative comparison of LAICGA systems has provided direct correlation of perfusion values predictive of necrosis that were previously established in the literature. An APU value of 3.7 from the SPY 2001 correlates to a SPY Elite APU value of 23.8. PMID:25525483

Laser processing of thin films for industrial packaging

NASA Astrophysics Data System (ADS)

Sozzi, Michele; Lutey, Adrian H. A.; Cucinotta, Annamaria; Selleri, Stefano; Molari, Pier Gabriele

2014-05-01

Single layer thin-film materials such as aluminum, polyethylene, polypropylene, and their multi-layer combinations such as aluminum-paper have been exposed to different laser radiation. A wide number of samples have been processed with 10 - 12.5 ns IR and Green, and 500 - 800 ps IR laser radiation at different translating speeds ranging from 50 mm/s to 1 m/s. High quality incisions have been obtained for all tested materials within the experimental conditions. The presented results provide the necessary parameters for an efficient cut and processing of the tested materials, for the employment of pulsed laser sources in the packaging industry, allowing the laser to prevail in lieu of more costly and energy intensive methods.

Best laser for prostatectomy in the year 2013.

PubMed

Maheshwari, Pankaj N; Joshi, Nitin; Maheshwari, Reeta P

2013-07-01

Lasers have come a long way in the management of benign prostatic hyperplasia. Over last nearly two decades, various different lasers have been utilized for prostatectomy. Neodymium: yttrium-aluminum-garnet laser that started this journey, is no longer used for prostatectomy. Holmium laser can achieve transurethral enucleation of the prostatic adenoma producing a fossa that can be compared with the fossa after Freyer's prostatectomy. Green light laser has a short learning curve, is nearly blood-less with good immediate results. Thulium laser is a faster cutting laser while diode laser is a portable laser device. Often laser prostatectomy is considered as a replacement for the standard transurethral resection of prostate (TURP). To be comparable, laser should reduce or avoid the immediate and long-term complications of TURP, especially bleeding and need for blood transfusion. It should also be safe in the ever increasing patient population on antiplatelet and anticoagulant drugs. We need to take stock of the situation and identify, which among the present day lasers has stood the test of time. A review of the literature was performed to see if any of these lasers could be called the "best laser for prostatectomy in 2013."

System Testing and Performance Characterization of the LITE Laser Transmitter Module at NASA

NASA Technical Reports Server (NTRS)

Cimolino, Marc C.; Petros, Mulugeta

1992-01-01

The Laser Transmitter Module (LTM) is a three-color Q-switched flashlamp pumped Nd:YAG laser. The original design concept was to package commercially available optics and flashlamp electronics for spaceflight with a power consumption goal of 2200 W and a weight goal of 600 lbs. The optical output was to exceed 200 mJ of IR, 400 mJ of green, and 150 mJ of UV per pulse at 10 Hz. The new space qualified laser exceeds the optical output requirements by 188 percent, 50 percent, and 13 percent in the UR, green, and UV respectively. This output needs only 1500 W at a weight of only 500 lbs. The LTM was delivered to the NASA Langley Research Center in December 1991. Optical characterization is now being completed.

Thermal and molecular investigation of laser tissue welding

NASA Astrophysics Data System (ADS)

Small, Ward, IV

between collagen molecules (crosslinks) were formed in tissue when exposed to the commonly used absorbing chromophore indocyanine green (ICG) prior to laser irradiation, which restored the crosslink concentrations to their native levels. Crosslinks were either created or destroyed during exposure to green laser light without any extrinsic materials or chromophores, which may impact the acute and long-term strength and stability of laser welded tissues. Infrared spectroscopy revealed changes in collagen conformation (molecular structure) induced by laser heating as a function of temperature, elucidating the dynamics of the denaturation process.

The ARGOS laser system: green light for ground layer adaptive optics at the LBT

NASA Astrophysics Data System (ADS)

Raab, Walfried; Rabien, Sebastian; Gässler, Wolfgang; Esposito, Simone; Barl, Lothar; Borelli, Jose; Daysenroth, Matthias; Gemperlein, Hans; Kulas, Martin; Ziegleder, Julian

2014-07-01

We report on the development of the laser system of ARGOS, the multiple laser guide star adaptive optics system for the Large Binocular Telescope (LBT). The system uses a total of six high powered, pulsed Nd:YAG lasers frequency-doubled to a wavelength of 532 nm to generate a set of three guide stars above each of the LBT telescopes. The position of each of the LGS constellations on sky as well as the relative position of the individual laser guide stars within this constellation is controlled by a set of steerable mirrors and a fast tip-tilt mirror within the laser system. The entire opto-mechanical system is housed in two hermetically sealed and thermally controlled enclosures on the SX and DX side of the LBT telescope. The laser beams are propagated through two refractive launch telescopes which focus the beams at an altitude of 12 km, creating a constellation of laser guide stars around a 4 arcminute diameter circle by means of Rayleigh scattering. In addition to the GLAO Rayleigh beacon system, ARGOS has also been designed for a possible future upgrade with a hybrid sodium laser - Rayleigh beacon combination, enabling diffraction limited operation. The ARGOS laser system was successfully installed at the LBT in April 2013. Extensive functional tests have been carried out and have verified the operation of the systems according to specifications. The alignment of the laser system with respect to the launch telescope was carried out during two more runs in June and October 2013, followed by the first propagation of laser light on sky in November 2013.

Effects of Laser Physical Parameters on Lesion Size in Retinal Photocoagulation Surgery: Clinical OCT and Experimental Study

PubMed Central

Soleimani, A.; Rasta, S.H.; Banaei, T.; Asgharsharghi Bonab, A.

2017-01-01

Introduction: The aim of the present study was to determine burn intensity in retinal laser photocoagulation based on laser parameters; wavelength, power, beam size and pulse duration, using Optical Coherence Tomography (OCT), fundus camera, physical eye model and computer simulation in a clinical study. Materials and Methods: Participants were 10 adult patients between 50-80 years with proliferative diabetic retinopathy. A multicolor-photo coagulator with 532 nm green and 672 nm red for retina photocoagulation in diabetic retinopathy was used to investigate the participants. Lesion size was measured for spot sizes 50 and 100 μm, with 100 and 150 mW laser power, and pulse duration 50 and 100 ms by OCT. Artificial eye and Zemax-optical design software were used with the same laser parameters. Results: Appearance of OCT and fundus images showed direct relationship between retina burn size and lesion intensity with exposure time and power and also reverse relationship with laser spot size. Compared to red wavelength, burn size and lesion intensity increased in green wavelength. On the other hand, results from physical eye model were the same as clinical examination shown. Laser spot size in retina with Zemax simulation demonstrated that red wavelength was greater than green one. Conclusion: This study showed shorter pulses provide decrease in duration of laser surgery with significantly reduced pain. Results and calculations described in this article can help clinicians adjusting the required total coagulated area, the number of lesions and pattern density. PMID:29445713

Effects of Laser Physical Parameters on Lesion Size in Retinal Photocoagulation Surgery: Clinical OCT and Experimental Study.

PubMed

Soleimani, A; Rasta, S H; Banaei, T; Asgharsharghi Bonab, A

2017-12-01

The aim of the present study was to determine burn intensity in retinal laser photocoagulation based on laser parameters; wavelength, power, beam size and pulse duration, using Optical Coherence Tomography (OCT), fundus camera, physical eye model and computer simulation in a clinical study. Participants were 10 adult patients between 50-80 years with proliferative diabetic retinopathy. A multicolor-photo coagulator with 532 nm green and 672 nm red for retina photocoagulation in diabetic retinopathy was used to investigate the participants. Lesion size was measured for spot sizes 50 and 100 μm, with 100 and 150 mW laser power, and pulse duration 50 and 100 ms by OCT. Artificial eye and Zemax-optical design software were used with the same laser parameters. Appearance of OCT and fundus images showed direct relationship between retina burn size and lesion intensity with exposure time and power and also reverse relationship with laser spot size. Compared to red wavelength, burn size and lesion intensity increased in green wavelength. On the other hand, results from physical eye model were the same as clinical examination shown. Laser spot size in retina with Zemax simulation demonstrated that red wavelength was greater than green one. This study showed shorter pulses provide decrease in duration of laser surgery with significantly reduced pain. Results and calculations described in this article can help clinicians adjusting the required total coagulated area, the number of lesions and pattern density.

Laser at 532 nm by intracavity frequency-doubling in BBO

NASA Astrophysics Data System (ADS)

Yuan, Xiandan; Wang, Jinsong; Chen, Yongqi; Wu, Yulong; Qi, Yunfei; Sun, Meijiao; Wang, Qi

2017-06-01

A simple and compact linear resonator green laser at 532 nm is generated by intracavity frequency-doubling of a diode-side-pumped acousto-optically (AO) Q-switched Nd:YAG laser at 1064 nm. Two acousto-optic Q-switches were placed orthogonally with each other to improve the hold-off capacity. As high as 214 W of continuous-wave (CW) and 154 W of quasi-continuous-wave (QCW) output power at 1064 nm were obtained when the pumping power was 1598 W. The type I phase-matched BBO crystal was used as the nonlinear medium in the second harmonic generation. A green laser with an average output power of 37 W was obtained at a repetition rate of 20 kHz and a pulse width of 54 ns, which corresponds to pulse energy of 1.85 mJ per pulse and a peak power 34.26 kW, respectively. Project supported by the Beijing Engineering Technology Research Center of All-Solid-State Lasers Advanced Manufacturing, the National High Technology Research and Development Program of China (No. 2014AA032607), and the National Natural Science Foundation of China (Nos. 61404135, 61405186, 61308032, 61308033).

Study of nonlinear refraction of organic dye by Z-scan technique using He-Ne laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Medhekar, S.; Kumar, R.; Mukherjee, S.

2013-02-05

Laser induced third-order nonlinear optical responses of Brilliant Green solution has been investigated by utilizing single beam Z-scan technique with a continuous-wave He-Ne laser radiation at 632.8 nm. It was observed that the material exhibits self-defocusing type optical nonlinearity. The measurements of nonlinear refraction were carried out at different dye concentrations and found that the increase in solution concentration leads to the linear increase of the nonlinear refractive index. The experimental results confirm great potential of the Brilliant Green for the application in nonlinear optical devices.

Growth and laser properties of Yb : Ca 4YO(BO 3) 3 crystal

NASA Astrophysics Data System (ADS)

Zhang, Huaijin; Meng, Xianlin; Zhu, Li; Wang, Pu; Liu, Xuesong; Cheng, Ruiping; Dawes, Judith; Dekker, Peter; Zhang, Shaojun; Sun, Lianke

1999-04-01

Yb : Ca 4YO(BO 3) 3 (Yb : YCOB) crystal has been grown by the Czochralski method. The absorption and fluorescence spectra have been measured. The green luminescence is also observed. The output laser at 1032 nm has been demonstrated pumped by laser diode (LD) at 976.4 nm.

Underwater probing with laser radar

NASA Technical Reports Server (NTRS)

Carswell, A. I.; Sizgoric, S.

1975-01-01

Recent advances in laser and electro optics technology have greatly enhanced the feasibility of active optical probing techniques aimed at the remote sensing of water parameters. This paper describes a LIDAR (laser radar) that has been designed and constructed for underwater probing. The influence of the optical properties of water on the general design parameters of a LIDAR system is considered. Discussion of the specific details in the choice of the constructed LIDAR is given. This system utilizes a cavity dumped argon ion laser transmitter capable of 50 watt peak powers, 10 nanosecond pulses and megahertz pulse repetition rates at 10 different wavelengths in the blue green region of the spectrum. The performance of the system, in proving various types of water, is demonstrated by summarizing the results of initial laboratory and field experiments.

Dose-dependent photochemical/photothermal toxicity of indocyanine green-based therapy on three different cancer cell lines.

PubMed

Ruhi, Mustafa Kemal; Ak, Ayşe; Gülsoy, Murat

2018-03-01

The Food and Drug Administration-approved Indocyanine Green can be used as a photosensitizer to kill cancer cells selectively. Although indocyanine green is advantageous as a photosensitizer in terms of strong absorption in the near-infrared region, indocyanine green-based cancer treatment is still not approved as a clinical method. Some reasons for this are aggregation at high concentrations, rapid clearance of the photosensitizer from the body, low singlet oxygen quantum yield, and the uncertainty concerning its action mechanism. This in vitro study focuses on two of these points: "what is the cell inhibition mechanism of indocyanine green-based therapy?" and "how the dose-dependent aggregation problem of indocyanine green alters its cell inhibition efficiency?" The following experiments were conducted to provide insight into these points. Nontoxic doses of indocyanine green and near-infrared laser were determined. The aggregation behavior of indocyanine green was verified through experiments. The singlet oxygen quantum yield of indocyanine green at different concentrations were calculated. Various indocyanine green and energy densities of near-infrared light were applied to prostate cancer, neuroblastoma, and colon cancer cells. An MTT assay was performed at the end of the first, second, and third days following the treatments to determine the cell viability. Temperature changes in the medium during laser exposure were recorded. ROS generation following the treatment was verified by using a Total Reactive Oxygen Species detection kit. An apoptosis detection test was performed to establish the cell death mechanism and, finally, the cellular uptakes of the three different cells were measured. According to the results, indocyanine green-based therapy causes cell viability decrease for three cancer cell lines by means of excessive reactive oxygen species production. Different cells have different sensitivities to the therapy possibly because of the differentiation

Prevention of pharyngocutaneous fistulas by means of laser-weld techniques.

PubMed

Shohet, J A; Reinisch, L; Ossoff, R H

1995-07-01

Although much has been written on methods of dealing with pharyngocutaneous fistulas once they have formed, there are few reports of methods of preventing fistula formation from occurring. We examined the use of laser-weld techniques with the neodymium:yttrium aluminum garnet (Nd:YAG) and diode lasers to seal pharyngotomy closures. Laser-weld techniques have been used successfully in many other tissues, but reports documenting use in the upper aerodigestive tract are minimal. Indocyanine-green dye-enhanced collagen and fibrinogen were studied as laser solder materials for the diode laser. Twenty-nine experimental animals were studied. Neither the Nd:YAG nor the diode laser was successful in preventing fistula formation. Tensiometric studies documented significant strength of the laser welds ex vivo, but this finding was not clinically significant.

Intense green emission from Tb3+- doped Teo2-Wo3-Geo2 glasses

NASA Astrophysics Data System (ADS)

Subrahmanyam, Tallam; Gopal, Kotalo Rama; Suvarna, Reniguntla Padma; Jamalaiah, Bungala Chinna

2018-04-01

Tb3+ -doped oxyfluoro tellurite (TWGTb) glasses were prepared by conventional melt quenching technique. The Judd-Ofelt theory has been applied to evaluate the Ωλ (λ=2,4,6) intensity parameters. The TWGTb glasses exhibit 5D3 → 7F5-3 and 5D4 → 7F6-0 transitions when excited at 316 nm wavelength. The variation of intensity of 5D4 → 7F5 (Green) and 5D3 → 7F4 (Blue) transitions and the green to blue (IG/IB) intensity ratios were studied as a function of Tb3+ ions concentration. The laser characteristic parameters such as effective bandwidth (Δλeff), stimulated emission cross-section (σe), gain bandwidth (σe×Δλeff) and optical gain (σe×τR) were determined using the emission spectra and radiative parameters. The luminescence decay profiles exhibit single-exponential nature for all the samples. Based on the experimental results we suggest that the 1.0 mol% of Tb3+-doped TWGTb glass could be the suitable laser host materials to emit intense green luminescence at 545 nm.

Near-infrared lasers and self-frequency-doubling in Nd:YCOB cladding waveguides.

PubMed

Ren, Yingying; Chen, Feng; Vázquez de Aldana, Javier R

2013-05-06

A design of cladding waveguides in Nd:YCOB nonlinear crystals is demonstrated in this work. Compact Fabry-Perot oscillation cavities are employed for waveguide laser generation at 1062 nm and self-frequency-doubling at 531 nm, under optical pump at 810 nm. The waveguide laser shows slope efficiency as high as 55% at 1062 nm. The SFD green waveguide laser emits at 531 nm with a maximum power of 100 μW.

Changes in type I collagen following laser welding.

PubMed

Bass, L S; Moazami, N; Pocsidio, J; Oz, M C; LoGerfo, P; Treat, M R

1992-01-01

Selection of ideal laser parameters for tissue welding is inhibited by poor understanding of the mechanism. We investigated structural changes in collagen molecules extracted from rat tail tendon (> 90% type I collagen) after tissue welding using an 808 nm diode laser and indocyanine green dye applied to the weld site. Mobility patterns on SDS-PAGE were identical in the lasered and untreated tendon extracts with urea or acetic acid. Pepsin incubation after acetic acid extraction revealed a reduction of collagen alpha and beta bands in lasered compared with untreated specimens. Circular dichroism studies of rat tail tendon showed absence of helical structure in collagen from lasered tendon. No evidence for covalent bonding was present in laser-treated tissues. Collagen molecules are denatured by the laser wavelength and parameters used in this study. No significant amount of helical structure is regenerated on cooling. We conclude that non-covalent interactions between denatured collagen molecules may be responsible for the creation of tissue welding.

Diffraction-limited 577 nm true-yellow laser by frequency doubling of a tapered diode laser

NASA Astrophysics Data System (ADS)

Christensen, Mathias; Vilera, Mariafernanda; Noordegraaf, Danny; Hansen, Anders K.; Buß, Thomas; Jensen, Ole B.; Skovgaard, Peter M. W.

2018-02-01

A wide range of laser medical treatments are based on coagulation of blood by absorption of the laser radiation. It has, therefore, always been a goal of these treatments to maximize the ratio of absorption in the blood to that in the surrounding tissue. For this purpose lasers at 577 nm are ideal since this wavelength is at the peak of the absorption in oxygenated hemoglobin. Furthermore, 577 nm has a lower absorption in melanin when compared to green wavelengths (515 - 532 nm), giving it an advantage when treating at greater penetration depth. Here we present a laser system based on frequency doubling of an 1154 nm Distributed Bragg Reflector (DBR) tapered diode laser, emitting 1.1 W of single frequency and diffraction limited yellow light at 577 nm, corresponding to a conversion efficiency of 30.5%. The frequency doubling is performed in a single pass configuration using a cascade of two bulk non-linear crystals. The system is power stabilized over 10 hours with a standard deviation of 0.13% and the relative intensity noise is measured to be 0.064 % rms.

High-energy long duration frequency-doubled Nd:YAG laser and application to venous occlusion

NASA Astrophysics Data System (ADS)

Zhang, Laiming; Yang, Guilong; Li, Dianjun; Lu, Qipeng; Gu, Huadong; Zhu, Linlin; Zhao, Zhenwu; Li, Xin; Tang, Yuguo; Guo, Jin

2005-01-01

Laser treatment represents an attractive option to other methods of vessel diseases especially varicose veins. A long pulse (30~50ms) 532nm laser (Fig.1) is used in our experiments with the pulse duration matching the thermal relaxation time of the vessels and the green laser matching the absorption spectrum peak of the blood. Laser irradiates nude vein vessels directly or exterior skin to finish operation faster and to acquire the practical data for upper enteron varicose vein treatment in several animal experiments performed in vivo. The 5J-energy pulse allows us to finely occlude rabbit or dog"s vein vessels up to 2 mm in diameter when irradiating them off external skin (Fig.2). Blood vessels are occluded at once and later biopsy specimens show the immediate and long-term lasting occlusion effect. While irradiating vessels directly (Fig.3), the vessels are usually irradiated to perforate, detailed causes are still under investigation. Animal experiments show long pulse green laser therapy is a safe and effective solution to the vein"s occlusion, which promises such laser with high energy of each pulse and 30~50 ms duration is an ideal candidate for vessel diseases treatment.

Feasibility of airborne detection of laser-induced fluorescence emissions from green terrestrial plants

NASA Technical Reports Server (NTRS)

Hoge, F. E.; Swift, R. N.; Yungel, J. K.

1983-01-01

The present investigation provides a demonstration of the feasibility of the airborne detection of the laser-induced fluorescence spectral emissions from living terrestrial grasses, shrubs, and trees using existing levels of lidar technology. Airborne studies were performed to ascertain system requirements necessary to detect laser-induced fluorescence from living terrestrial plants, to assess the practical acquisition of useful single-shot laser-induced fluorescence (LIF) waveforms over vegetative canopies, and to determine the comparative suitability of laser system, airborne platform, and terrestrial environmental parameters. The field experiment was conducted on May 3, 1982, over the northern portion of Wallops Island, VA. Attention is given to airborne lidar results and the description of laboratory investigations.

Generation of 180 W average green power from a frequency-doubled picosecond rod fiber amplifier

DOE PAGES

Zhao, Zhi; Sheehy, Brian; Minty, Michiko

2017-03-29

Here, we report on the generation of 180 W average green power from a frequency-doubled picosecond rod fiber amplifier. In an Yb-doped fiber master-oscillator-power-amplifier system, 2.3-ps 704 MHz pulses are first amplified in small-core fibers and then in large-mode-area rod fibers to produce 270 W average infrared power with a high polarization extinction ratio and diffraction-limited beam quality. By carrying out frequency doubling in a lithium triborate (LBO) crystal, 180 W average green power is generated. To the best of our knowledge, this is the highest average green power achieved in fiber-based laser systems.

GreenLITE: a new laser-based tool for near-real-time monitoring and mapping of CO2 and CH4 concentrations on scales from 0.04-25 km2

NASA Astrophysics Data System (ADS)

Dobler, Jeremy T.; Pernini, Timothy G.; Blume, Nathan; Zaccheo, T. Scott; Braun, Michael

2017-08-01

In 2013, Harris and Atmospheric and Environmental Research developed the greenhouse gas laser imaging tomography experiment (GreenLITE™) under a cooperative agreement with the National Energy Technology Laboratory of the Department of Energy. The system uses a pair of high-precision, intensity-modulated, continuous-wave (IMCW) transceivers and a series of retroreflectors to generate overlapping atmospheric density measurements from absorption of a particular greenhouse gas (e.g. CO2 or CH4), to provide an estimate of the two-dimensional spatial distribution of the gas within the area of interest. The system can take measurements over areas ranging from approximately 0.04 square kilometers (km2) to 25 km2 ( 200 meters (m) × 200 m, up to 5 km × 5 km). Multiple GreenLITE™ CO2 demonstrations have been carried out to date, including a full year, November 04, 2015 through November 14, 2016, deployment over a 25 km2 area of downtown Paris, France. In late 2016, the GreenLITE™ system was converted to provide similar measurements for CH4. Recent experiments showed that GreenLITE™ CH4 concentration readings correlated with an insitu instrument, calibrated with World Meteorological Organization traceable gas purchased from the NOAA Earth Systems Research Laboratory, to within approximately 0.5% of CH4 background or 10-15 parts per billion. Several experiments are planned in 2017 to further evaluate the accuracy of the CH4 and CO2 retrieved concentration values compared to the calibrated in situ instrument and to demonstrate the feasibility of GreenLITE™ for environmental and safety monitoring of CO2 and CH4 in industrial applications.

A simplified scheme for generating narrow-band mid-ultraviolet laser radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Almog, G.; Ludwig-Maximilians-Universität, Geschwister-Scholl-Platz 1, 80539 München; Scholz, M., E-mail: Matthias.Scholz@toptica.com

2015-03-15

We report on the development and characterization of continuous, narrow-band, and tunable laser systems that use direct second-harmonic generation from blue and green diode lasers with an output power level of up to 11.1 mW in the mid-ultraviolet. One of our laser systems was tuned to the mercury 6{sup 1}S{sub 0} → 6{sup 3}P{sub 1} intercombination line at 253.7 nm. We could perform Doppler-free saturation spectroscopy on this line and were able to lock our laser to the transition frequency on long time scales.

Best laser for prostatectomy in the year 2013

PubMed Central

Maheshwari, Pankaj N; Joshi, Nitin; Maheshwari, Reeta P

2013-01-01

Lasers have come a long way in the management of benign prostatic hyperplasia. Over last nearly two decades, various different lasers have been utilized for prostatectomy. Neodymium: yttrium-aluminum-garnet laser that started this journey, is no longer used for prostatectomy. Holmium laser can achieve transurethral enucleation of the prostatic adenoma producing a fossa that can be compared with the fossa after Freyer's prostatectomy. Green light laser has a short learning curve, is nearly blood-less with good immediate results. Thulium laser is a faster cutting laser while diode laser is a portable laser device. Often laser prostatectomy is considered as a replacement for the standard transurethral resection of prostate (TURP). To be comparable, laser should reduce or avoid the immediate and long-term complications of TURP, especially bleeding and need for blood transfusion. It should also be safe in the ever increasing patient population on antiplatelet and anticoagulant drugs. We need to take stock of the situation and identify, which among the present day lasers has stood the test of time. A review of the literature was performed to see if any of these lasers could be called the “best laser for prostatectomy in 2013.” PMID:24082446

Laser re-manufacturing of failure 18Cr2Ni4WA gear in low-speed heavy-load mining machine transmission

NASA Astrophysics Data System (ADS)

Chi, X. F.

2017-10-01

This article investigated laser re-manufacturing technology application in mining industry. The research focused on green re-manufacturing of failure spur. Leave the main gear body stay intact after the dirty, rust, fatigue and injured part were removed completely before the green re-manufacturing procedure begin. The optimized laser operating parameters paved the road for excellent mechanical properties and comparatively neat shape which often means less post processing. The laser re-manufactured gear surface was systematically examined, including microstructure observation, and dry wear test at room temperature. The test results were compared with new gear surface and used but not broken gear surface. Finally, it proved that the green re-manufactured gear surface displayed best comprehensive mechanical properties, followed the new gear surface. The resistance of dry wear properties of used but not broken gear surface was the worst.

An Open-path Laser Transmissometer for Atmospheric Extinction Measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chandran, P. M. Satheesh; Krishnakumar, C. P.; Varma, Ravi

2011-10-20

A transmissometer is an optical instrument which measures transmitted intensity of monochromatic light over a fixed pathlength. Prototype of a simple laser transmissometer has been developed for transmission (or extinction) measurements through suspended absorbers and scatterers in the atmosphere over tens of meters. Instrument consists of a continuous green diode pumped solid state laser, transmission optics, photodiode detectors and A/D data acquisition components. A modulated laser beam is transmitted and subsequently reflected and returned to the unit by a retroreflecting mirror assembly placed several tens of meters away. Results from an open-path field measurement of the instrument are described.

Lethal photosensitization of wound-associated microbes using indocyanine green and near-infrared light.

PubMed

Omar, Ghada S; Wilson, Michael; Nair, Sean P

2008-07-01

The increase in resistance to antibiotics among disease-causing bacteria necessitates the development of alternative antimicrobial approaches such as the use of light-activated antimicrobial agents (LAAAs). Light of an appropriate wavelength activates the LAAA to produce cytotoxic species which can then cause bacterial cell death via loss of membrane integrity, lipid peroxidation, the inactivation of essential enzymes, and/or exertion of mutagenic effects due to DNA modification. In this study, the effect of the LAAA indocyanine green excited with high or low intensity light (808 nm) from a near-infrared laser (NIR) on the viability of Staphylococcus aureus, Streptococcus pyogenes and Pseudomonas aeruginosa was investigated. All species were susceptible to killing by the LAAA, the bactericidal effect being dependent on both the concentration of indocyanine green and the light dose. Indocyanine green photosensitization using both high (1.37 W cm(-2)) and low (0.048 W cm(-2)) intensity NIR laser light was able to achieve reductions of 5.6 log10 (>99.99%) and 6.8 log10 (>99.99%) in the viable counts of Staph. aureus and Strep. pyogenes (using starting concentrations of 106-107 CFU ml(-1)). Kills of 99.99% were obtained for P. aeruginosa (initial concentration 108-109 CFU ml(-1)) photosensitized by the high intensity light (1.37 W cm(-2)); while a kill of 80% was achieved using low intensity irradiation (0.07 W cm(-2)). The effects of L-tryptophan (a singlet oxygen scavenger) and deuterium oxide (as an enhancer of the life span of singlet oxygen) on the survival of Staph. aureus was also studied. L-tryptophan reduced the proportion of Staph. aureus killed; whereas deuterium oxide increased the proportion killed suggesting that singlet oxygen was involved in the killing of the bacteria. These findings imply that indocyanine green in combination with light from a near-infrared laser may be an effective means of eradicating bacteria from wounds and burns.

Ripeness detection simulation of oil palm fruit bunches using laser-based imaging system

NASA Astrophysics Data System (ADS)

Shiddiq, Minarni; Fitmawati, Anjasmara, Ridho; Sari, Nurmaya; Hefniati

2017-01-01

Ripeness is one of important factors for quality sorting of harvested oil palm fresh fruit bunches (FFB). Traditional ripeness classifications using FFB color and number of fruit loose for harvesting have some disadvantages especially for high oil palm trees. A laser based imaging system is proposed to substitute the traditional method. In this study, ripeness detection simulation of oil palm FFBs was performed. The system composed of two diode lasers with 532 nm and 680 nm in wavelengths and a CMOS camera which was set on a rotating plate for easy adjustment of laser beam hitting FFB. The FFB samples were placed on an aluminum platform with 4 height variations, 1.5 m, 2 m, 2.5 m, and 3 m. The relations of reflectance intensities represented by Red Green Blue (RGB) values of the FFB images to the height variations and ripeness levels of FFBs with and without laser beam were analyzed. The samples were from Tenera variety with 4 ripeness levels called F0, F1, F3, and F4. The results showed that the red component of RGB values were dominant for FFBs without laser and with red laser. The average RGB values are higher for F3 (ripe) level and F4 (overripe). Imaging with green laser showed consistency. Imaging methods using laser was able to differentiate ripeness levels of oil palm fresh fruit bunch, it could be applied for future remote detection of oil palm FFB ripeness.

ZnCdMgSe as a Materials Platform for Advanced Photonic Devices: Broadband Quantum Cascade Detectors and Green Semiconductor Disk Lasers

NASA Astrophysics Data System (ADS)

De Jesus, Joel

The ZnCdMgSe family of II-VI materials has unique and promising characteristics that may be useful in practical applications. For example they can be grown lattice matched to InP substrates with lattice matched bandgaps that span from 2.1 to 3.5 eV, they can be successfully doped n-type, have a large conduction band offset (CBO) with no intervalley scattering present when strained, they have lower average phonon energies, and the InP lattice constant lies in the middle of the ZnSe and CdSe binaries compounds giving room to experiment with tensile and compressive stress. However they have not been studied in detail for use in practical devices. Here we have identified two types of devices that are being currently developed that benefit from the ZnCdMgSe-based material properties. These are the intersubband (ISB) quantum cascade (QC) detectors and optically pumped semiconductor lasers that emit in the visible range. The paucity for semiconductor lasers operating in the green-orange portion of the visible spectrum can be easily overcome with the ZnCdMgSe materials system developed in our research. The non-strain limited, large CBO available allows to expand the operating wavelength of ISB devices providing shorter and longer wavelengths than the currently commercially available devices. This property can also be exploited to develop broadband room temperature operation ISB detectors. The work presented here focused first on using the ZnCdMgSe-based material properties and parameter to understand and predict the interband and intersubband transitions of its heterostructures. We did this by studying an active region of a QC device by contactless electroreflectance, photoluminescence, FTIR transmittance and correlating the measurements to the quantum well structure by transfer matrix modeling. Then we worked on optimizing the ZnCdMgSe material heterostructures quality by studying the effects of growth interruptions on their optical and optoelectronic properties of

Carrier envelope offset frequency detection and stabilization of a diode-pumped mode-locked Ti:sapphire laser.

PubMed

Gürel, Kutan; Wittwer, Valentin J; Hakobyan, Sargis; Schilt, Stéphane; Südmeyer, Thomas

2017-03-15

We demonstrate the first diode-pumped Ti:sapphire laser frequency comb. It is pumped by two green laser diodes with a total pump power of 3 W. The Ti:sapphire laser generates 250 mW of average output power in 61-fs pulses at a repetition rate of 216 MHz. We generated an octave-spanning supercontinuum spectrum in a photonic-crystal fiber and detected the carrier envelope offset (CEO) frequency in a standard f-to-2f interferometer setup. We stabilized the CEO-frequency through direct current modulation of one of the green pump diodes with a feedback bandwidth of 55 kHz limited by the pump diode driver used in this experiment. We achieved a reduction of the CEO phase noise power spectral density by 140 dB at 1 Hz offset frequency. An advantage of diode pumping is the ability for high-bandwidth modulation of the pump power via direct current modulation. After this experiment, we studied the modulation capabilities and noise properties of green pump laser diodes with improved driver electronics. The current-to-output-power modulation transfer function shows a bandwidth larger than 1 MHz, which should be sufficient to fully exploit the modulation bandwidth of the Ti:sapphire gain for CEO stabilization in future experiments.

Q-switched all-solid-state lasers and application in processing of thin-film solar cell

NASA Astrophysics Data System (ADS)

Liu, Liangqing; Wang, Feng

2009-08-01

Societal pressure to renewable clean energy is increasing which is expected to be used as part of an overall strategy to address global warming and oil crisis. Photovoltaic energy conversion devices are on a rapidly accelerating growth path driven by government, of which the costs and prices lower continuously. The next generation thin-film devices are considered to be more efficiency and greatly reduced silicon consumption, resulting in dramatically lower per unit fabrication costs. A key aspect of these devices is patterning large panels to create a monolithic array of series-interconnected cells to form a low current, high voltage module. This patterning is accomplished in three critical scribing processes called P1, P2, and P3. All-solid-state Q-switched lasers are the technology of choice for these processes, due to their advantages of compact configuration, high peak-value power, high repeat rate, excellent beam quality and stability, delivering the desired combination of high throughput and narrow, clean scribes. The end pumped all-solid-state lasers could achieve 1064nm IR resources with pulse width of nanoseconds adopting acoustic-optics Q-switch, shorter than 20ns. The repeat rate is up to 100kHz and the beam quality is close to diffraction limit. Based on this, 532nm green lasers, 355nm UV lasers and 266nm DUV lasers could be carried out through nonlinear frequency conversion. Different wave length lasers are chose to process selective materials. For example, 8-15 W IR lasers are used to scribe the TCO film (P1); 1-5 W green lasers are suitable for scribing the active semiconductor layers (P2) and the back contact layers (P3). Our company, Wuhan Lingyun Photo-electronic System Co. Ltd, has developed 20W IR and 5W green end-pumped Q-switched all-solid-state lasers for thin-film solar industry. Operating in high repeat rates, the speed of processing is up to 2.0 m/s.

Comparative study of the bactericidal effects of indocyanine green- and methyl aminolevulinate-based photodynamic therapy on Propionibacterium acnes as a new treatment for acne.

PubMed

Choi, Seung-Hwan; Seo, Jeong-Wan; Kim, Ki-Ho

2018-05-03

Acne vulgaris is one of the most common dermatological problems, and its therapeutic options include topical and systemic retinoids and antibiotics. However, increase in problems associated with acne treatment, such as side-effects from conventional agents and bacterial resistance to antibiotics, has led to greater use of photodynamic therapy. The purpose of this study was to compare the bactericidal effects of indocyanine green- and methyl aminolevulinate-based photodynamic therapy on Propionibacterium acnes. P. acnes were cultured under anaerobic conditions; then they were divided into three groups (control, treated with indocyanine green and treated with methyl aminolevulinate) and illuminated with different lights (630-nm light-emitting diode, 805-nm diode laser and 830-nm light-emitting diode). The bactericidal effects were evaluated by comparing each group's colony-forming units. The cultured P. acnes were killed with an 805-nm diode laser and 830-nm light-emitting diode in the indocyanine green group. No bactericidal effects of methyl aminolevulinate-based photodynamic therapy were identified. The clinical efficacy of indocyanine green-based photodynamic therapy in 21 patients was retrospectively analyzed. The Korean Acne Grading System was used to evaluate treatment efficacy, which was significantly decreased after treatment. The difference in the efficacy of the 805-nm diode laser and 830-nm light-emitting diode was not statistically significant. Although the methyl aminolevulinate-based photodynamic therapy showed no bactericidal effect, the indocyanine green-based photodynamic therapy has bactericidal effect and clinical efficacy. © 2018 Japanese Dermatological Association.

Proceedings of the Fourth Laser Hydrography Symposium at Defence Research Centre and Royal Australian Navy Hydrographic Office

NASA Astrophysics Data System (ADS)

Penny, M. F.; Phillips, D. M.

1981-03-01

At this Symposium, research on laser hydrography and related development programs currently in progress in the United States of America, Canada, and Australia, were reported. The depth sounding systems described include the US Airborne Oceanographic Lidar and Hydrographic Airborne Laser Sounder, the Canadian Profiling Lidar Bathymeter, and the Australian Laser Airborne Depth Sounder. Other papers presented research on blue-green lasers, theoretical modelling, position fixing, and data processing.

Orange fiber laser for ophthalmology

NASA Astrophysics Data System (ADS)

Adachi, M.; Kojima, K.; Hayashi, K.

2007-02-01

For the light source of photocoagulators for ophthalmology, orange laser is more suitable than green laser because of low scattering loss by the crystalline lens, and low absorption by xanthophylls in the retina. We developed two orange fiber lasers (580 nm and 590 nm) to investigate the effect depending on the difference in the range of orange. The 580nm laser is composed of a 1160 nm fiber laser and a Periodically Polled Lithium Niobate (PPLN) crystal for second harmonic generation. The 1160 nm fiber laser beam is focused into the MgO-doped PPLN crystal whose length is 30 mm with 3-pass configuration. Continuous-wave 1.3 W output power of 580 nm was obtained with 5.8 W input power of 1160nm for the first time. The conversion efficiency was 22%. The band width of the second harmonic was 0.006 nm (FWHM). The 590 nm laser is almost the same as 580 nm laser source. In this case we used a Raman shift fiber to generate 1180 nm, and the output power of 590 nm was 1.4 W. We developed an evaluation model of photocoagulator system using these two laser sources. A 700 mW coagulation output power was obtained with this orange fiber laser photocoagulator system. This is enough power for the eye surgery. We have the prospect of the maintenance-free, long-life system that is completely air-cooled. We are planning to evaluate this photocoagulator system in order to investigate the difference between the two wavelengths at the field test.

Laser-induced fusion of human embryonic stem cells with optical tweezers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen Shuxun; Wang Xiaolin; Sun Dong

2013-07-15

We report a study on the laser-induced fusion of human embryonic stem cells (hESCs) at the single-cell level. Cells were manipulated by optical tweezers and fused under irradiation with pulsed UV laser at 355 nm. Successful fusion was indicated by green fluorescence protein transfer. The influence of laser pulse energy on the fusion efficiency was investigated. The fused products were viable as gauged by live cell staining. Successful fusion of hESCs with somatic cells was also demonstrated. The reported fusion outcome may facilitate studies of cell differentiation, maturation, and reprogramming.

Indocyanine green laser angiography improves deep inferior epigastric perforator flap outcomes following abdominal suction lipectomy.

PubMed

Casey, William J; Connolly, Katharine A; Nanda, Alisha; Rebecca, Alanna M; Perdikis, Galen; Smith, Anthony A

2015-03-01

The reliability of deep inferior epigastric artery perforator (DIEP) flap reconstruction following abdominal liposuction is controversial. The authors' early cases were technically successful; however, they experienced high partial flap loss and fat necrosis rates. The authors sought to compare DIEP flap outcomes in the setting of prior liposuction after the use of intraoperative indocyanine green angiography compared to when flaps were assessed on clinical grounds alone. A retrospective review of a consecutive series of DIEP flaps following liposuction at a single institution was performed, comparing those evaluated on clinical grounds alone and those in which indocyanine green angiography was used intraoperatively. Outcomes measured included anastomotic complications, total flap loss, partial flap loss, fat necrosis, and postoperative abdominal wounds. Thirteen DIEP flaps following prior liposuction were performed on 11 patients from July of 2003 through January of 2014. All patients had preoperative imaging with duplex ultrasound or computed tomographic angiography to analyze perforator suitability before surgical exploration. Seven flaps were evaluated intraoperatively on clinical grounds alone. Six flaps were assessed and modified based on indocyanine green angiography. All flaps were successful; however, partial flap loss and fat necrosis rates dropped from 71.4 percent to 0 percent when indocyanine green angiography was used intraoperatively (p = 0.02). Indocyanine green angiography is an excellent vascular imaging modality for intraoperative use to assess flap perfusion, and improves outcomes in DIEP flaps when harvested after prior abdominal suction lipectomy.

Photoselective laser ablation of the prostate: a review of the current 2015 tissue ablation options.

PubMed

Tholomier, Côme; Valdivieso, Roger; Hueber, Pierre-Alain; Zorn, Kevin C

2015-10-01

Transurethral resection of the prostate (TURP) is still considered the gold standard to treat benign prostatic hyperplasia (BPH). However, photoselective vaporization of the prostate (PVP) has gained widespread acceptance as an alternative option requiring preoperative patient selection. Four laser systems are currently in use: holmium, thulium, diode and GreenLight. The goal of this article is to review the physics and the basics behind laser prostatectomies, as well as to present the most current literature concerning the results, advantages, disadvantages and international recommendations for each vaporization procedure. Holmium laser ablation of the prostate (HoLAP) and GreenLight photoselective vaporization of the prostate are an alternative to TURP for small to medium-sized prostates, providing equivalent efficacy and safety. GreenLight is also safe and effective in large-sized prostates and especially beneficial in anti-coagulated individuals compared to TURP. Thulium vaporization of the prostate (ThuVAP) and diode vaporization both require additional randomized trials and long term studies before conclusion is made, despite promising initial results. Diode vaporization provides the best hemostasis overall, but at the cost of increased complication and re-treatment rate, and thus is not recommended except in severely anti-coagulated patients. Laser vaporization is a safe and effective alternative to TURP in the treatment of benign prostatic hyperplasia (BPH) for carefully selected patients. However, further research is still needed to assess the durability of each technology.

Selective Destruction of Protein Function by Chromophore-Assisted Laser Inactivation

NASA Astrophysics Data System (ADS)

Jay, Daniel G.

1988-08-01

Chromophore-assisted laser inactivation of protein function has been achieved. After a protein binds a specific ligand or antibody conjugated with malachite green (C.I. 42000), it is selectively inactivated by laser irradiation at a wavelength of light absorbed by the dye but not significantly absorbed by cellular components. Ligand-bound proteins in solution and on the surfaces of cells can be denatured without other proteins in the same samples being affected. Chromophore-assisted laser inactivation can be used to study cell surface phenomena by inactivating the functions of single proteins on living cells, a molecular extension of cellular laser ablation. It has an advantage over genetics and the use of specific inhibitors in that the protein function of a single cell within the organism can be inactivated by focusing the laser beam.

Comparative in vitro study of tissue welding using a 808 nm diode laser and a Ho:YAG laser.

PubMed

Ott, B; Züger, B J; Erni, D; Banic, A; Schaffner, T; Weber, H P; Frenz, M

2001-01-01

In vitro porcine arteries and veins have been welded end-to-end using either a 808 nm diode laser combined with an indocyanine green enhanced albumin solder, or with a continuous-wave (cw) Ho:YAG laser without biological solder. The vascular stumps were approached to each other over a coronary dilatation catheter in order to obtain a precise alignment and good coaptation. Standard histology revealed for both welding techniques lateral tissue damage between 2 and 3 mm caused by laser-induced heat. Good solder attachment to the tissue was observed by the use of a scanning electron microscope. The vessels soldered with the 808 nm diode laser using albumin solder showed considerably higher tensile strength (1 N compared to 0.3 N) than vessels welded exclusively by Ho:YAG laser radiation. In contrast, leaking pressure (350 +/- 200 mmHg) and bursting pressure (457 +/- 200 mmHg) were found to be independent of the welding technique used. This study demonstrates that fast (total welding time about 2-5 min), stable and tight microvascular anastomosis can be achieved with the use of a dye-enhanced albumin laser soldering technique and an ancillary coronary dilatation catheter.

Laser characteristics at 1535 nm and thermal effects of an Er:Yb phosphate glass microchip pumped by Ti:sapphire laser

NASA Astrophysics Data System (ADS)

Cai, Zhiping; Chardon, Alain; Xu, Huiying; Féron, Patrice; Michel Stéphan, Guy

2002-03-01

An Er:Yb codoped phosphate glass microchip laser has been studied under pumping with a Ti:sapphire laser ranging from 945 to 990 nm. The characteristics (threshold, slope efficiency) are first described for an optimized laser. The gain spectrum is calculated for the transition 4I13/2→ 4I15/2 around 1535 nm from fundamental spectroscopic data and from experimental results. Red-shift effect on the frequency of a single mode is experimentally observed when the pump power is increased, originating from thermal effects. Temperature inside the microchip cavity and thermal expansion coefficient were determined by employing the intensity ratio of two green upconversion emission line centered at 530 and 554 nm, respectively, which quantitatively explain this red shift.

Comparison of Laser Doppler and Laser-Assisted Indocyanine Green Angiography Prediction of Flap Survival in a Novel Modification of the McFarlane Flap.

PubMed

Fourman, Mitchell Stephen; Gersch, Robert P; Phillips, Brett T; Nasser, Ahmed; Rivara, Andrew; Verma, Richa; Dagum, Alexander B; Rosengart, Todd K; Bui, Duc T

2015-07-01

The McFarlane rat ischemic dorsal skin flap model has been commonly used for clinical vector studies, as well as the testing of noninvasive diagnostics. However, variability of this model secondary to flap contact with the wound bed has led many to question its validity. Here we present a novel modification to the McFarlane skin flap using sterile silicone. We also use this model to test the prognostic efficacy of laser-assisted indocyanine green (ICG) angiography and laser Doppler imaging (LDI). A 3 × 9-cm dorsal skin flap with a cranially based pedicle was created, centered 1 cm distal to the scapulae. The flap was undermined, and in one of the 2 groups, a sterile silicone sheet was placed onto the wound bed. All flaps were then reapproximated with sutures 1-cm intervals. Clinical assessment and perfusion imaging was performed immediately postoperative, and at 24, 48, and 72 hours postsurgery. Postoperative day 7 clinical assessment was obtained before euthanasia. A comparative study using silicone blocked versus unblocked models (n = 6 per group) showed that, clinically, both models had equivalent flap survival [8.5 (0.913) vs 9.5 (1.01) cm]. However, a statistically significant increase in perfusion in the mid-third of unblocked models was observed on POD3 [20.28% (2.7%) vs blocked 13.45% (2.5%), P < 0.05], with a similar increase in the distal third on POD7 [18.73% (2.064%) vs 10.91% (4.19%), P < 0.05]. A prognostic study comparing LDI and ICG angiography prediction of POD7 survival at early time points (n = 10) found that LDI underpredicted flap survival at early time points [84.2% (12.03%) on POD0, 87.35% (16.11%) on POD1]. In contrast, ICG was more proficient [100.1% (10.1%) on POD0]. We present a modification of the McFarlane skin flap model that results in similar clinical results, but with a noted reduction in perfusion inconsistencies noted in unblocked models. The ICG angiography is superior to LDI in predicting POD7 flap necrosis within the first 48

3 μm CW lasers for myringotomy and microsurgery.

PubMed

Linden, Kurt J; Pfeffer, Christian P; Sousa, John Gary; D'Alleva, Nicholas; Aslani, Arash; Gorski, Grzegorz; Kenna, Margaret; Poe, Dennis S

2013-03-08

This paper describes the development and implementation of 3 μm lasers for myringotomy and microsurgery. Two different lasers were investigated. The first, an Er-doped, CW zirconate glass fiber laser optically pumped by a 970 nm diode laser, emitted > 1 W of CW power at 2.76 μm with concomitant green incoherent emission that served as a convenient visible illumination beam. The second, a 1 W CW Er:YAG solid-state laser also optically pumped by a 970 nm diode laser, emitted > 1 W of CW power at 2.94 μm, coincident with the strongest infrared water absorption peak. Running CW, both lasers are expected to avoid the loud acoustical shocks associated with pulsed lasers. Myringotomies were carried out with the Er:YAG laser on anaesthetized guinea pigs and the effects of the laser were documented. Laser ablated samples of tympanic membrane, soft tissue and bone were histologically examined. Histology results indicated that the CW Er:YAG laser is a potential candidate for a new myringotomy tool and possibly for otologic microsurgery, but deliverable power levels need to be increased to the 2 W (or higher) level. This work was funded under NIH SBIR Grant No. 5R44DC004899.

3-μm CW lasers for myringotomy and microsurgery

NASA Astrophysics Data System (ADS)

Linden, Kurt J.; Pfeffer, Christian P.; Sousa, John Gary; D'Alleva, Nicholas; Aslani, Arash; Gorski, Grzegorz; Kenna, Margaret; Poe, Dennis S.

2013-03-01

This paper describes the development and implementation of 3 μm lasers for myringotomy and microsurgery. Two different lasers were investigated. The first, an Er-doped, CW zirconate glass fiber laser optically pumped by a 970 nm diode laser, emitted > 1 W of CW power at 2.76 μm with concomitant green incoherent emission that served as a convenient visible illumination beam. The second, a 1 W CW Er:YAG solid-state laser also optically pumped by a 970 nm diode laser, emitted > 1 W of CW power at 2.94 μm, coincident with the strongest infrared water absorption peak. Running CW, both lasers are expected to avoid the loud acoustical shocks associated with pulsed lasers. Myringotomies were carried out with the Er:YAG laser on anaesthetized guinea pigs and the effects of the laser were documented. Laser ablated samples of tympanic membrane, soft tissue and bone were histologically examined. Histology results indicated that the CW Er:YAG laser is a potential candidate for a new myringotomy tool and possibly for otologic microsurgery, but deliverable power levels need to be increased to the 2 W (or higher) level. This work was funded under NIH SBIR Grant No. 5R44DC004899.

3 μm CW lasers for myringotomy and microsurgery

PubMed Central

Linden, Kurt J.; Pfeffer, Christian P.; Sousa, John Gary; D’Alleva, Nicholas; Aslani, Arash; Gorski, Grzegorz; Kenna, Margaret; Poe, Dennis S.

2013-01-01

This paper describes the development and implementation of 3 μm lasers for myringotomy and microsurgery. Two different lasers were investigated. The first, an Er-doped, CW zirconate glass fiber laser optically pumped by a 970 nm diode laser, emitted > 1 W of CW power at 2.76 μm with concomitant green incoherent emission that served as a convenient visible illumination beam. The second, a 1 W CW Er:YAG solid-state laser also optically pumped by a 970 nm diode laser, emitted > 1 W of CW power at 2.94 μm, coincident with the strongest infrared water absorption peak. Running CW, both lasers are expected to avoid the loud acoustical shocks associated with pulsed lasers. Myringotomies were carried out with the Er:YAG laser on anaesthetized guinea pigs and the effects of the laser were documented. Laser ablated samples of tympanic membrane, soft tissue and bone were histologically examined. Histology results indicated that the CW Er:YAG laser is a potential candidate for a new myringotomy tool and possibly for otologic microsurgery, but deliverable power levels need to be increased to the 2 W (or higher) level. This work was funded under NIH SBIR Grant No. 5R44DC004899. PMID:24382990

Laser dazzling impacts on car driver performance

NASA Astrophysics Data System (ADS)

Steinvall, Ove; Sandberg, Stig; Hörberg, Ulf; Persson, Rolf; Berglund, Folke; Karslsson, Kjell; Öhgren, Johan; Yu, Zhaohua; Söderberg, Per

2013-10-01

A growing problem for the Police and Security Forces has been to prevent potentially hostile individuals to pass a checkpoint, without using lethatl violence. Therefore the question has been if there is a laser or any other strong light source that could be used as a warning and dazzling device, without lethal or long term effects. To investigate the possibilities a field trial has been performed at a motor-racing track. A green CW laser with an irradiance on the eye of maximum 0.5 MPE, as defined by ICNIRP [1] and the ANZI standard [2], was used as a dazzle source. Ten drivers have been driving with dipped headlights through a course of three lines with orange cones. In every line there has been only one gate wide enough to pass without hitting the cones. The time through the course, the choice of gates and the number of cones hit have been measured. For every second trial drive through the track, the driver was exposed to the laser dazzler. The background illuminances ranged from a thousand lux in daylight to about ten millilux in darkness. The protective effect of the sun-visor of the car was investigated. The drives visual system was carefully examined before and after experimental driving and a few weeks after the experimental driving to verify that no pathological effects, that could potentially be induced by the laser exposure, pre-existed or occurred after the laser exposure. An analysis of variance for a within subjects design has been used for evaluation. It was found that green laser light can have an obvious warning effect in daylight. Dazzling does reduce the drivers ability to make judgments and manouver the car in twilight and darkness. A sun-visor can reduce the glare and give the driver an improved control, but that perception can be unjustified. No damage to the visual system was observed.

Quasi-dynamical analysis and real-time tissue temperature monitoring during laser vaporization

NASA Astrophysics Data System (ADS)

Wang, Hui; Ray, Aditi; Jebens, Dave; Chia, Ray; Hasenberg, Tom

2014-03-01

Vaporization and coagulation are two fundamental processes that can be performed during laser-tissue ablation. We demonstrated a method allowing quasi-dynamically observing of the cross-sectional images of tissue response during ablation. The results showed that coagulation depth is relatively constant during vaporization, which supports the excellent hemostasis of green laser benign prostate hyperplasia (BPH) treatment. We also verified a new technology for real-time, in situ tissue temperature monitoring, which may be promising for in vivo tissue vaporization degree feedback during laser ablation to improve the vaporization efficiency and avoid complications.

Impact of Infrared Lunar Laser Ranging on Lunar Dynamics

NASA Astrophysics Data System (ADS)

Viswanathan, Vishnu; Fienga, Agnès; Manche, Hervé; Gastineau, Mickael; Courde, Clément; Torre, Jean-Marie; Exertier, Pierre; Laskar, Jacques; LLR Observers : Astrogeo-OCA, Apache Point, McDonald Laser Ranging Station, Haleakala Observatory, Matera Laser Ranging Observatory

2016-10-01

Since 2015, in addition to the traditional green (532nm), infrared (1064nm) has been the preferred wavelength for lunar laser ranging at the Calern lunar laser ranging (LLR) site in France. Due to the better atmospheric transmission of IR with respect to Green, nearly 3 times the number of normal points have been obtained in IR than in Green [ C.Courde et al 2016 ]. In our study, in addition to the historical data obtained from various other LLR sites, we include the recent IR normal points obtained from Calern over the 1 year time span (2015-2016), constituting about 4.2% of data spread over 46 years of LLR. Near even distribution of data provided by IR on both the spatial and temporal domain, helps us to improve constraints on the internal structure of the Moon modeled within the planetary ephemeris : INPOP [ Fienga et al 2015 ]. IERS recommended models have been used in the data reduction software GINS (GRGS,CNES) [ V.Viswanathan et al 2015 ]. Constraints provided by GRAIL, on the Lunar gravitational potential and Love numbers have been taken into account in the least-square fit procedure. New estimates on the dynamical parameters of the lunar core will be presented.

The generation of a continuous-wave Nd:YVO4/LBO laser at 543 nm by direct in-band diode pumping at 888 nm

NASA Astrophysics Data System (ADS)

Fu, S. C.; Wang, X.; Chu, H.

2013-02-01

We report the generation of a green laser at 543 nm by intracavity frequency doubling of the continuous-wave (cw) laser operation of a 1086 nm Nd:YVO4 laser under 888 nm diode pumping into the emitting level 4F3/2. An LiB3O5 (LBO) crystal, cut for critical type I phase matching at room temperature, is used for the laser second-harmonic generation. At an incident pump power of 17.8 W, as high as 4.53 W cw output power at 543 nm is achieved. The optical-to-optical conversion efficiency is up to 25.4%, and the fluctuation of the green output power is better than 2.3% in a 30 min period.

Eradication of C. albicans and T. rubrum with photoactivated indocyanine green, Citrus aurantifolia essential oil and fluconazole.

PubMed

Fekrazad, Reza; Poorsattar Bejeh Mir, Arash; Ghasemi Barghi, Vadood; Shams-Ghahfarokhi, Masoomeh

2015-06-01

We aimed to evaluate the efficacy of alternative therapies rather than the current antifungal conventional therapy and with assessing the hypothesis of photoactivation of citrus essential oil, fluconazole and Indocyanine green to treat two common mucocutaneous fungal infections. Suspensions of Candida albicans and Tricophyton rubrum containing 10(6)cells/ml was prepared. Equal samples were treated with infrared (IR) laser irradiation (810 nm, 55 J/cm(2)) in the presence of Indocyanine green (Emundo, 1 mg/ml) (IRLE), photoactivated Citrus aurantifolia essential oil (EO) with sequential exposure to natural and tungsten lights (CE), control non-activated essential oil (CC), laser alone (IRL), indocyanine green alone (E) and neither of treatments as the control group (C). Additional fluconazole (FL, 25.6 μg/ml) and IR activated fluconazole (IRLFL) groups were designed for T. rubrum fungi. Inoculums were serially diluted to 10(-2) and 10(-4) and streaked on Sabouraud dextrose agar plates. Final outcomes were assessed as the percent of reduction. Cell reduction rates (%) in C. albicans groups were 99.99 (CE), 91.67 (IRLE), 86.67 (CC), 72.37 (E) and 67.27 (RL). Whereas, a 99.99 (CE), 89.99 (CC), 74.5 (IRLE), 64.5 (E), 38.5 (IRLF), 37.5 (RL), and 31 (FL) percent eradication was achieved in T. rubrum groups. Photoactivation of Citrus EO increased the killing capability by 10-13%. A modest 7.5% augmented effect was observed with IR activation of Fluconazole. Both Citrus EO and photothermal-photodynamic therapy with ICG and IR diode laser exhibited remarkable lethal effect on fungal cells. Candida viable cells are more susceptible to laser only and ICG only treatments than Tricophyton cells. Copyright © 2015 Elsevier B.V. All rights reserved.

Laser-diode pumped self-mode-locked praseodymium visible lasers with multi-gigahertz repetition rate.

PubMed

Zhang, Yuxia; Yu, Haohai; Zhang, Huaijin; Di Lieto, Alberto; Tonelli, Mauro; Wang, Jiyang

2016-06-15

We demonstrate efficient laser-diode pumped multi-gigahertz (GHz) self-mode-locked praseodymium (Pr³⁺) visible lasers with broadband spectra from green to deep red for the first time to our knowledge. With a Pr³⁺-doped GdLiF₄ crystal, stable self-mode-locked visible pulsed lasers at the wavelengths of 522 nm, 607 nm, 639 nm, and 720 nm have been obtained with the repetition rates of 2.8 GHz, 3.1 GHz, 3.1 GHz, and 3.0 GHz, respectively. The maximum output power was 612 mW with the slope efficiency of 46.9% at 639 nm. The mode-locking mechanism was theoretically analyzed. The stable second-harmonic mode-locking with doubled repetition frequency was also realized based on the Fabry-Perot effect formed in the laser cavity. In addition, we find that the polarization directions were turned with lasing wavelengths. This work may provide a new way for generating efficient ultrafast pulses with high- and changeable-repetition rates in the visible range.

Photodynamic inactivation of Staphylococcus aureus and Escherichia coli biofilms by malachite green and phenothiazine dyes: an in vitro study.

PubMed

Vilela, Simone Furgeri Godinho; Junqueira, Juliana Campos; Barbosa, Junia Oliveira; Majewski, Marta; Munin, Egberto; Jorge, Antonio Olavo Cardoso

2012-06-01

The organization of biofilms in the oral cavity gives them added resistance to antimicrobial agents. The action of phenothiazinic photosensitizers on oral biofilms has already been reported. However, the action of the malachite green photosensitizer upon biofilm-organized microorganisms has not been described. The objective of the present work was to compare the action of malachite green with the phenothiazinic photosensitizers (methylene blue and toluidine blue) on Staphylococcus aureus and Escherichia coli biofilms. The biofilms were grown on sample pieces of acrylic resin and subjected to photodynamic therapy using a 660-nm diode laser and photosensitizer concentrations ranging from 37.5 to 3000 μM. After photodynamic therapy, cells from the biofilms were dispersed in a homogenizer and cultured in Brain Heart Infusion broth for quantification of colony-forming units per experimental protocol. For each tested microorganism, two control groups were maintained: one exposed to the laser radiation without the photosensitizer (L+PS-) and other treated with the photosensitizer without exposure to the red laser light (L-PS+). The results were subjected to descriptive statistical analysis. The best results for S. aureus and E. coli biofilms were obtained with photosensitizer concentrations of approximately 300 μM methylene blue, with microbial reductions of 0.8-1.0 log(10); 150 μM toluidine blue, with microbial reductions of 0.9-1.0 log(10); and 3000 μM malachite green, with microbial reductions of 1.6-4.0 log(10). Greater microbial reduction was achieved with the malachite green photosensitizer when used at higher concentrations than those employed for the phenothiazinic dyes. Copyright © 2011 Elsevier Ltd. All rights reserved.

Influence of ablation wavelength and time on optical properties of laser ablated carbon dots

NASA Astrophysics Data System (ADS)

Isnaeni, Hanna, M. Yusrul; Pambudi, A. A.; Murdaka, F. H.

2017-01-01

Carbon dots, which are unique and applicable materials, have been produced using many techniques. In this work, we have fabricated carbon dots made of coconut fiber using laser ablation technique. The purpose of this work is to evaluate two ablation parameters, which are ablation wavelength and ablation time. We used pulsed laser from Nd:YAG laser with emit wavelength at 355 nm, 532 nm and 1064 nm. We varied ablation time one hour and two hours. Photoluminescence and time-resolved photoluminescence setup were used to study the optical properties of fabricated carbon dots. In general, fabricated carbon dots emit bluish green color emission upon excitation by blue laser. We found that carbon dots fabricated using 1064 nm laser produced the highest carbon dots emission among other samples. The peak wavelength of carbon dots emission is between 495 nm until 505 nm, which gives bluish green color emission. Two hours fabricated carbon dots gave four times higher emission than one hour fabricated carbon dot. More emission intensity of carbon dots means more carbon dots nanoparticles were fabricated during laser ablation process. In addition, we also measured electron dynamics of carbon dots using time-resolved photoluminescence. We found that sample with higher emission has longer electron decay time. Our finding gives optimum condition of carbon dots fabrication from coconut fiber using laser ablation technique. Moreover, fabricated carbon dots are non-toxic nanoparticles that can be applied for health, bio-tagging and medical applications.

High contrast laser marking of alumina

NASA Astrophysics Data System (ADS)

Penide, J.; Quintero, F.; Riveiro, A.; Fernández, A.; del Val, J.; Comesaña, R.; Lusquiños, F.; Pou, J.

2015-05-01

Alumina serves as raw material for a broad range of advanced ceramic products. These elements should usually be identified by some characters or symbols printed directly on them. In this sense, laser marking is an efficient, reliable and widely implemented process in industry. However, laser marking of alumina still leads to poor results since the process is not able to produce a dark mark, yielding bad contrast. In this paper, we present an experimental study on the process of marking alumina by three different lasers working in two wavelengths: 1064 nm (Near-infrared) and 532 nm (visible, green radiation). A colorimetric analysis has been carried out in order to compare the resulting marks and its contrast. The most suitable laser operating conditions were also defined and are reported here. Moreover, the physical process of marking by NIR lasers is discussed in detail. Field Emission Scanning Electron Microscopy, High Resolution Transmission Electron Microscopy and X-ray Photoelectron Spectroscopy were also employed to analyze the results. Finally, we propose an explanation for the differences of the coloration induced under different atmospheres and laser parameters. We concluded that the atmosphere is the key parameter, being the inert one the best choice to produce the darkest marks.

Laser tissue welding mediated with a protein solder

NASA Astrophysics Data System (ADS)

Small, Ward, IV; Heredia, Nicholas J.; Celliers, Peter M.; Da Silva, Luiz B.; Eder, David C.; Glinsky, Michael E.; London, Richard A.; Maitland, Duncan J.; Matthews, Dennis L.; Soltz, Barbara A.

1996-05-01

A study of laser tissue welding mediated with an indocyanine green dye-enhanced protein solder was performed. Freshly obtained sections of porcine artery were used for the experiments. Sample arterial wall thickness ranged from two to three millimeters. Incisions approximately four millimeters in length were treated using an 805 nanometer continuous- wave diode laser coupled to a one millimeter diameter fiber. Controlled parameters included the power delivered by the laser, the duration of the welding process, and the concentration of dye in the solder. A two-color infrared detection system was constructed to monitor the surface temperatures achieved at the weld site. Burst pressure measurements were made to quantify the strengths of the welds immediately following completion of the welding procedure.

An "All-laser" Endothelial Transplant.

PubMed

Rossi, Francesca; Canovetti, Annalisa; Malandrini, Alex; Lenzetti, Ivo; Pini, Roberto; Menabuoni, Luca

2015-07-06

The "all laser" assisted endothelial keratoplasty is a procedure that is performed with a femtosecond laser used to cut the donor tissue at an intended depth, and a near infrared diode laser to weld the corneal tissue. The proposed technique enables to reach the three main goals in endothelial keratoplasty: a precise control in the thickness of the donor tissue; its easy insertion in the recipient bed and a reduced risk of donor lenticule dislocation. The donor cornea thickness is measured in the surgery room with optical coherence tomography (OCT), in order to correctly design the donor tissue dimensions. A femtosecond laser is used to cut the donor cornea. The recipient eye is prepared by manual stripping of the descemetic membrane. The donor endothelium is inserted into a Busin-injector, the peripheral inner side is stained with a proper chromophore (a water solution of Indocyanine Green) and then it is pulled in the anterior chamber. The transplanted tissue is placed in the final and correct location and then diode laser welding is induced from outside the eyeball. The procedure has been performed on more than 15 patients evidencing an improvement in surgery performances, with a good recovery of visual acuity and a reduced donor lenticule dislocation event.

Laser processing of ceramics for microelectronics manufacturing

NASA Astrophysics Data System (ADS)

Sposili, Robert S.; Bovatsek, James; Patel, Rajesh

2017-03-01

Ceramic materials are used extensively in the microelectronics, semiconductor, and LED lighting industries because of their electrically insulating and thermally conductive properties, as well as for their high-temperature-service capabilities. However, their brittleness presents significant challenges for conventional machining processes. In this paper we report on a series of experiments that demonstrate and characterize the efficacy of pulsed nanosecond UV and green lasers in machining ceramics commonly used in microelectronics manufacturing, such as aluminum oxide (alumina) and aluminum nitride. With a series of laser pocket milling experiments, fundamental volume ablation rate and ablation efficiency data were generated. In addition, techniques for various industrial machining processes, such as shallow scribing and deep scribing, were developed and demonstrated. We demonstrate that lasers with higher average powers offer higher processing rates with the one exception of deep scribes in aluminum nitride, where a lower average power but higher pulse energy source outperformed a higher average power laser.

Azacoumarin dye lasers

DOEpatents

Hammond, Peter R.; Atkins, Ronald L.; Henry, Ronald A.; Fletcher, Aaron N.

1978-01-01

A dye laser comprising a laser dye solution of a compound having the general structure: ##STR1## wherein at least one of the 5, 6 and 8 ring positions is occupied by a nitrogen atom in lieu of the corresponding CR group and X is OH, alkoxy, or amino including amino substituted by at least one of the following: alkyl, aryl, acyl, aracyl, a group which taken together with the nitrogen atom of the amino group forms a heterocyclic ring, or part of one or two 5 or 6 membered aliphatic heterocyclic rings attached to ring A at positions 6 or 8 or both depending on where the N in ring A is located. R.sub.3, R.sub.4, R.sub.5, R.sub.6 and R.sub.8 are hydrogen or other groups as defined below. The compounds lase in the blue-green to near ultraviolet region.

Fungal Microbiomes Associated with Green and Non-Green Building Materials

PubMed Central

Coombs, Kanistha; Vesper, Stephen; Green, Brett J.; Yermakov, Mikhail; Reponen, Tiina

2018-01-01

Water-damaged buildings can lead to fungal growth and occupant health problems. Green building materials, derived from renewable sources, are increasingly utilized in construction and renovations. However, the question as to what fungi will grow on these green compared to non-green materials, after they get wet, has not been adequately studied. By determining what fungi grow on each type of material, the potential health risks can be more adequately assessed. In this study, we inoculated green and non-green pieces of ceiling tile, composite board, drywall, and flooring with indoor dust containing a complex mixture of naturally occurring fungi. The materials were saturated with water and incubated for two months in a controlled environment. The resulting fungal microbiomes were evaluated using ITS amplicon sequencing. Overall, the richness and diversity of the mycobiomes on each pair of green and non-green pieces were not significantly different. However, different genera dominated on each type of material. For example, Aspergillus spp. had the highest relative abundance on green and non-green ceiling tiles and green composite boards, but Peniophora spp. dominated the non-green composite board. In contrast, Penicillium spp. dominated green and non-green flooring samples. Green gypsum board was dominated by Phialophora spp. and Stachybotrys spp., but non-green gypsum board by Myrothecium spp. These data suggest that water-damaged green and non-green building materials can result in mycobiomes that are dominated by fungal genera whose member species pose different potentials for health risks. PMID:29681691

Fungal Microbiomes Associated with Green and Non-Green Building Materials.

PubMed

Coombs, Kanistha; Vesper, Stephen; Green, Brett J; Yermakov, Mikhail; Reponen, Tiina

2017-01-01

Water-damaged buildings can lead to fungal growth and occupant health problems. Green building materials, derived from renewable sources, are increasingly utilized in construction and renovations. However, the question as to what fungi will grow on these green compared to non-green materials, after they get wet, has not been adequately studied. By determining what fungi grow on each type of material, the potential health risks can be more adequately assessed. In this study, we inoculated green and non-green pieces of ceiling tile, composite board, drywall, and flooring with indoor dust containing a complex mixture of naturally occurring fungi. The materials were saturated with water and incubated for two months in a controlled environment. The resulting fungal microbiomes were evaluated using ITS amplicon sequencing. Overall, the richness and diversity of the mycobiomes on each pair of green and non-green pieces were not significantly different. However, different genera dominated on each type of material. For example, Aspergillus spp. had the highest relative abundance on green and non-green ceiling tiles and green composite boards, but Peniophora spp. dominated the non-green composite board. In contrast, Penicillium spp. dominated green and non-green flooring samples. Green gypsum board was dominated by Phialophora spp. and Stachybotrys spp., but non-green gypsum board by Myrothecium spp. These data suggest that water-damaged green and non-green building materials can result in mycobiomes that are dominated by fungal genera whose member species pose different potentials for health risks.

Laser Digital Cinema

NASA Astrophysics Data System (ADS)

Takeuchi, Eric B.; Flint, Graham W.; Bergstedt, Robert; Solone, Paul J.; Lee, Dicky; Moulton, Peter F.

2001-03-01

Electronic cinema projectors are being developed that use a digital micromirror device (DMDTM) to produce the image. Photera Technologies has developed a new architecture that produces truly digital imagery using discrete pulse trains of red, green, and blue light in combination with a DMDTM where in the number of pulses that are delivered to the screen during a given frame can be defined in a purely digital fashion. To achieve this, a pulsed RGB laser technology pioneered by Q-Peak is combined with a novel projection architecture that we refer to as Laser Digital CameraTM. This architecture provides imagery wherein, during the time interval of each frame, individual pixels on the screen receive between zero and 255 discrete pulses of each color; a circumstance which yields 24-bit color. Greater color depth, or increased frame rate is achievable by increasing the pulse rate of the laser. Additionally, in the context of multi-screen theaters, a similar architecture permits our synchronously pulsed RGB source to simultaneously power three screens in a color sequential manner; thereby providing an efficient use of photons, together with the simplifications which derive from using a single DMDTM chip in each projector.

Uptake of indocyanine green by hamster sebaceous glands

NASA Astrophysics Data System (ADS)

McMillan, Kathleen; Lo, Kai-Ming; Wang, Zhi

2001-05-01

Photothermal injury to the sebaceous glands is a potential curative treatment for the common skin disease acne vulgaris. Accumulation of the exogenous chromophore indocyanine green in the sebaceous glands may be accomplished using an emulsion or liposomal formulation applied to the skin surface. An emulsion containing 0.09% by weight indocyanine green (ICG) was applied to the epidermis of hamster ears ex vivo and the flank organ in vivo. Fluorescence microscopy demonstrated selective accumulation of ICG in the underlying sebaceous glands. The concentration of ICG that may be expected to accumulate in sebaceous glands of humans was then estimated on the basis of the gland size and orifice area, for the case of topical application of a more concentrated 1% ICG liposomal formulation. Monte Carlo modeling and heat transfer calculations showed that the sebaceous glands containing the exogenous chromophore may be selectively damaged by pulsed 810 nm laser radiation in conjunction with cryogen spray cooling.

Laser microprocessing and nanoengineering of large-area functional micro/nanostructures

NASA Astrophysics Data System (ADS)

Tang, M.; Xie, X. Z.; Yang, J.; Chen, Z. C.; Xu, L.; Choo, Y. S.; Hong, M. H.

2011-12-01

Laser microprocessing and nanoengineering are of great interest to both scientists and engineers, since the inspired properties of functional micro/nanostructures over large areas can lead to numerous unique applications. Currently laser processing systems combined with high speed automation ensure the focused laser beam to process various materials at a high throughput and a high accuracy over large working areas. UV lasers are widely used in both laser microprocessing and nanoengineering. However by improving the processing methods, green pulsed laser is capable of replacing UV lasers to make high aspect ratio micro-grooves on fragile and transparent sapphire substrates. Laser micro-texturing can also tune the wetting property of metal surfaces from hydrophilic to super-hydrophobic at a contact angle of 161° without chemical coating. Laser microlens array (MLA) can split a laser beam into multiple laser beams and reduce the laser spot size down to sub-microns. It can be applied to fabricate split ring resonator (SRR) meta-materials for THz sensing, surface plasmonic resonance (SPR) structures for NIR and molding tools for soft lithography. Furthermore, laser interference lithography combined with thermal annealing can obtain a large area of sub-50nm nano-dot clusters used for SPR applications.

Use of a capillary electrophoresis instrument with laser-induced fluorescence detection for DNA quantitation. Comparison of YO-PRO-1 and PicoGreen assays.

PubMed

Guillo, Christelle; Ferrance, Jerome P; Landers, James P

2006-04-28

Highly selective and sensitive assays are required for detection and quantitation of the small masses of DNA typically encountered in clinical and forensic settings. High detection sensitivity is achieved using fluorescent labeling dyes and detection techniques such as spectrofluorometers, microplate readers and cytometers. This work describes the use of a laser-induced fluorescence (LIF) detector in conjunction with a commercial capillary electrophoresis instrument for DNA quantitation. PicoGreen and YO-PRO-1, two fluorescent DNA labeling dyes, were used to assess the potential of the system for routine DNA analysis. Linearity, reproducibility, sensitivity, limits of detection and quantitation, and sample stability were examined for the two assays. The LIF detector response was found to be linear (R2 > 0.999) and reproducible (RSD < 9%) in both cases. The PicoGreen assay displayed lower limits of detection and quantitation (20 pg and 60 pg, respectively) than the YO-PRO-1 assay (60 pg and 260 pg, respectively). Although a small variation in fluorescence was observed for the DNA/dye complexes over time, quantitation was not significantly affected and the solutions were found to be relatively stable for 80 min. The advantages of the technique include a 4- to 40-fold reduction in the volume of sample required compared to traditional assays, a 2- to 20-fold reduction in the volume of reagents consumed, fast and automated analysis, and low cost (no specific instrumentation required).

Patent blue V and indocyanine green for fluorescence microimaging of human peritoneal carcinomatosis using probe-based confocal laser endomicroscopy.

PubMed

Abbaci, Muriel; Dartigues, Peggy; De Leeuw, Frederic; Soufan, Ranya; Fabre, Monique; Laplace-Builhé, Corinne

2016-12-01

Peritoneal carcinomatosis is a metastatic stage aggravating abdominal and pelvic cancer dissemination. The preoperative evaluation of lesions remains difficult today. Probe-based confocal laser endomicroscopy (pCLE) provides dynamic images of tissue architecture and cellular details. This technology allows in vivo histological interpretation of tissue. The main limitation of pCLE for adoption in the clinic is the unavailability of fluorescent contrast agents. The aim of our study was to evaluate the staining performance of indocyanine green and patent blue V for histological diagnosis of pCLE images of pathological and non-pathological peritoneal tissue. We performed a correlative study with the histological gold standard on ex vivo human specimens from 25 patients operated for peritoneal carcinomatosis; 70 specimens were stained by topical application with ICG or patent blue V and then imaged with a probe-based confocal laser endomicroscope. A total of 350 pCLE images and 70 corresponding histological sections were randomly and blindly interpreted by two pathologists (PT1 and PT2). The images were first classified into two categories, tumoral versus non-tumoral, and a refined histological diagnosis was then given. All presented images were interpreted by PT1 (who received prior training on PCLE image reading) and PT2 (no training). 100 % sensitivity for PT1 and PT2 was noticed with tissues stained with ICG to differentiate tumoral and non-tumoral tissue. Global scores were always better for PT1 (major concordance between 86 and 94 %) than for PT2 (major concordance between 77 and 89 %) independently of the fluorescent dye when histological diagnosis was done on pCLE images. In conclusion, the pair ICG-pCLE offers the best combination for a non-trained pathologist for the interpretation of pCLE images from peritoneum.

Laser-activated protein solder for peripheral nerve repair

NASA Astrophysics Data System (ADS)

Trickett, Rodney I.; Lauto, Antonio; Dawes, Judith M.; Owen, Earl R.

1995-05-01

A 100 micrometers core optical fiber-coupled 75 mW diode laser operating at a wavelength of 800 nm has been used in conjunction with a protein solder to stripe weld severed rat tibial nerves, reducing the long operating time required for microsurgical nerve repair. Welding is produced by selective laser denaturation of the albumin based solder which contains the dye indocyanine green. Operating time for laser soldering was 10 +/- 5 min. (n equals 20) compared to 23 +/- 9 min. (n equals 10) for microsuturing. The laser solder technique resulted in patent welds with a tensile strength of 15 +/- 5 g, while microsutured nerves had a tensile strength of 40 +/- 10 g. Histopathology of the laser soldered nerves, conducted immediately after surgery, displayed solder adhesion to the outer membrane with minimal damage to the inner axons of the nerves. An in vivo study is under way comparing laser solder repaired tibial nerves to conventional microsuture repair. At the time of submission 15 laser soldered nerves and 7 sutured nerves were characterized at 3 months and showed successful regeneration with compound muscle action potentials of 27 +/- 8 mV and 29 +/- 8 mW respectively. A faster, less damaging and long lasting laser based anastomotic technique is presented.

Laser color recording unit

NASA Astrophysics Data System (ADS)

Jung, E.

1984-05-01

A color recording unit was designed for output and control of digitized picture data within computer controlled reproduction and picture processing systems. In order to get a color proof picture of high quality similar to a color print, together with reduced time and material consumption, a photographic color film material was exposed pixelwise by modulated laser beams of three wavelengths for red, green and blue light. Components of different manufacturers for lasers, acousto-optic modulators and polygon mirrors were tested, also different recording methods as (continuous tone mode or screened mode and with a drum or flatbed recording principle). Besides the application for the graphic arts - the proof recorder CPR 403 with continuous tone color recording with a drum scanner - such a color hardcopy peripheral unit with large picture formats and high resolution can be used in medicine, communication, and satellite picture processing.

Laser-activated solid protein bands for peripheral nerve repair: an vivo study.

PubMed

Lauto, A; Trickett, R; Malik, R; Dawes, J M; Owen, E R

1997-01-01

Severed tibial nerves in rats were repaired using a novel technique, utilizing a semiconductor diode-laser-activated protein solder applied longitudinally across the join. Welding was produced by selective laser denaturation of solid solder bands containing the dye indocyanine green. An in vivo study, using 48 adult male Wistar rats, compared conventional microsuture-repaired tibial nerves with laser solder-repaired nerves. Nerve repairs were characterised immediately after surgery and after 3 months. Successful regeneration with average compound muscle action potentials of 2.5 +/- 0.5 mV and 2.7 +/- 0.3 mV (mean and standard deviation) was demonstrated for the laser-soldered nerves and the sutured nerves, respectively. Histopathology confirmed comparable regeneration of axons in laser- and suture-operated nerves. The laser-based nerve repair technique was easier and faster than microsuture repair, minimising manipulation damage to the nerve.

The KTP-(greenlight-) laser--principles and experiences.

PubMed

Bachmann, Alexander; Ruszat, Robin

2007-01-01

The most recent advance in laser technology for transurethral prostatectomy is represented by the KTP laser. A potassium-titanyl-phosphate-(KTP-) crystal doubles the frequency of pulsed Neodymium: Yttrium-Aluminum-Garnet (Nd:YAG) laser energy to a 532 nm wavelength, which is in the green electromagnetic spectrum (Greenlight-laser) and is selectively absorbed by hemoglobin and not at all by water. Reducing the wavelength leads to a completely different interaction between laser beam and prostatic tissue. In contrast to the early clinical experiences with the Nd:YAG lasers in which vaporization was observed as a side-effect during the procedure, the new KTP laser offers an immediate and efficient vaporization, leading to real tissue ablation. Because of the instant and nearly complete absorption in blood, the depth in vascularized tissue such as prostate is only 0.8 mm. The superficial coagulation prevents the large tissue necrosis that is seen with the Nd:YAG laser, leading to long lasting irritative symptoms due to sloughing of necrotic tissue. Initial experiences, made with a 60W KTP system, demonstrated that the procedure was as effective as conventional transurethral resection of the prostate (TURP) with a lower intraoperative complication rate. In order to speed up vaporization of the prostate laser power has been increased to 80W. The 80W KTP laser combines the tissue debulking properties of TURP and the favourable safety profile of laser surgery. With the new 120W High Performance System, introduced in 2006, vaporization will become more powerful and faster. Initial reports are awaited.

Fluorescence measurement of diode (805 nm) laser-induced release of 5,6-CF from DSPC liposomes for monitoring of temperature: an in vivo study in rat liver using indocyanine green potentiation

NASA Astrophysics Data System (ADS)

Mordon, Serge R.; Desmettre, Thomas; Devoisselle, Jean-Marie; Soulie-Begu, Sylvie

1995-05-01

This in-vivo study examines the validity of fluorescence measurement of laser-induced release of temperature sensitive liposome-encapsulated dye for monitoring of temperature and prediction of tissue thermal damage. It is performed in rat liver after i.v. injection of liposomes loaded with a fluorescent dye and i.v. injection of Indocyanine Green (ICG) for diode laser potentiation. Temperature sensitive liposomes (DSPC: Di- Stearoyl-Phosphatidyl-Choline) are loaded with 5,6-Carboxyfluorescein (5,6-CF). These liposomes (1.5 ml solution) and ICG (1.5 ml solution-5 mg/kg) are injected to adult male wistar rats. Two hours later, the liver is exposed and irradiated with a 0.8 W diode laser using pulses lasting from 1 s to 6 s (fluence ranging from 16 to 98 J/cm+2)). Simultaneously, the fluorescence emission is measured with a fluorescent imaging system. Results show that the fluorescence intensity increases linearly form 18 J/cm2 up to 75 J/cm2. These fluences correspond to surface temperatures between 42°C to 64°C. The measurements appear to be highly reproducible. In this temperature range, the accuracy is +/- 3°C. The maximum intensity is observed immediately after the laser is switched off and a decrease of the fluorescence intensity is observed (27% in 20 minutes) due to the 5.6-CF clearance. However, the ratio (IF/Ibck) remains almost stable over this period of time and the determination of the temperature is still possible with a good accuracy even 20 minutes after laser irradiation. In conclusion, temperature monitoring by using fluorescence measurement of laser-induced release of liposome-encapsulated dye is clearly demonstrated. This procedure could conceivably prove useful for controlling the thermal coagulation of biological tissues.

Green thunderstorms

NASA Astrophysics Data System (ADS)

Gallagher, Frank Woolsey, III

Many people around the world have observed green light apparently emanating from severe thunderstorms, but until recently there has been no scientific study of the phenomenon. Green thunderstorms have been observed from time to time in association with deep convection or severe weather events. Some skeptics who have not personally observed a green thunderstorm suggest that they are some kind of illusion. The existence of green thunderstorms has been objectively demonstrated by recording spectra of light from thunderstorms using a handheld spectrophotometer. During the spring and summer of 1995 and the spring of 1996 numerous storms were observed and spectra of the light emanating from these storms were recorded. Observations were made both at the ground and aboard research aircraft. Furthermore, time series of spectra were recorded as the observed color of some storms changed from dark blue to a bluish-green. Several hypotheses have been advanced to explain the occurrence of green light in connection with severe storms. Fankhauser gave some observational support to the belief that green light from thunderstorms is possible and believed that the source of the light is from the blue sky penetrating thin regions in the clouds. Fraser believes that light from the setting sun, in combination with the process of scattering by atmospheric molecules, creates the green light associated with severe weather and the thunderstorm acts only as a black backdrop. Unfortunately, no cloud illuminated by the sun is black and the green airlight produced by the Fraser theory is in reality overwhelmed by light reflected by the cloud. Often the unusual coloration has been attributed to hail or to reflection of light from foliage on the ground. The quantitative measurements made during the observation period fail to support these assumptions. We have observed thunderstorms to be green over ground that was not green and we have observed blue thunderstorms over ground that was green

Investigation on RGB laser source applied to dynamic photoelastic experiment

NASA Astrophysics Data System (ADS)

Li, Songgang; Yang, Guobiao; Zeng, Weiming

2014-06-01

When the elastomer sustains the shock load or the blast load, its internal stress state of every point will change rapidly over time. Dynamic photoelasticity method is an experimental stress analysis method, which researches the dynamic stress and the stress wave propagation. Light source is one of very important device in dynamic photoelastic experiment system, and the RGB laser light source applied in dynamic photoelastic experiment system is innovative and evolutive to the system. RGB laser is synthesized by red laser, green laser and blue laser, either as a single wavelength laser light source, also as synthesized white laser light source. RGB laser as a light source for dynamic photoelastic experiment system, the colored isochromatic can be captured in dynamic photoelastic experiment, and even the black zero-level stripe can be collected, and the isoclinics can also be collected, which conducively analysis and study of transient stress and stress wave propagation. RGB laser is highly stable and continuous output, and its power can be adjusted. The three wavelengths laser can be synthesized by different power ratio. RGB laser light source used in dynamic photoelastic experiment has overcome a number of deficiencies and shortcomings of other light sources, and simplifies dynamic photoelastic experiment, which has achieved good results.

Laser-assisted fibrinogen bonding of umbilical vein grafts.

PubMed

Oz, M C; Williams, M R; Souza, J E; Dardik, H; Treat, M R; Bass, L S; Nowygrod, R

1993-06-01

Despite success with autologous tissue welding, laser welding of synthetic vascular prostheses has not been possible. The graft material appears inert and fails to allow the collagen breakdown and electrostatic bonding that results in tissue welding. To develop a laser welding system for graft material, we repaired glutaraldehyde-tanned human umbilical cord vein graft incisions using laser-assisted fibrinogen bonding (LAFB) technology. Modified umbilical vein graft was incised transversely (1.2 cm). Incisions were repaired using sutures, laser energy alone, or LAFB. For LAFB, indocyanine green dye was mixed with human fibrinogen and the compound applied with forceps onto the weld site prior to exposure to 808 nm diode laser energy (power density 4.8 W/cm 2). Bursting pressures for sutured repairs (126.6 +/- 23.4 mm Hg) were similar to LAFB anastomoses (111.6 +/- 55.0 mm Hg). No evidence of collateral thermal injury to the graft material was noted. In vivo evaluation of umbilical graft bonding with canine arteries demonstrates that LAFB can reliably reinforce sutured anastomoses. The described system for bonding graft material with laser exposed fibrinogen may allow creation or reinforcement of vascular anastomoses in procedures where use of autologous tissue is not feasible.

ARGOS - the Laser Star Adaptive Optics for LBT

NASA Astrophysics Data System (ADS)

Rabien, S.; Barl, L.; Beckmann, U.; Blümchen, T.; Bonaglia, M.; Borelli, J. L.; Brynnel, J.; Busoni, L.; Carbonaro, L.; Conot, C.; Davies, R.; Deysenroth, M.; Durney, O.; Elberich, M.; Esposito, S.; Gasho, V.; Gässler, W.; Gemperlein, H.; Genzel, R.; Green, R.; Haug, M.; Lloyd Hart, M.; Hubbard, P.; Kanneganti, S.; Kulas, M.; Noenickx, J.; Peter, D.; Quirrenbach, A.; Rademacher, M.; Rix, H. W.; Salinari, P.; Schwab, C.; Storm, J.; Strüder, L.; Thiel, M.; Weigelt, G.; Ziegleder, J.; Orban de Xivry, G.

2011-09-01

We will present the design and status of ARGOS - the Laser Guide Star adaptive optics facility for the Large Binocular Telescope. By projecting a constellation of multiple laser guide stars above each of the 8.4m primary mirrors of the LBT, ARGOS in its ground layer mode will enable a wide field adaptive optics correction for multi object spectroscopy. ARGOS implements high power pulsed green lasers and makes use of Rayleigh scattering for the guide star creation. The geometric relations of this setup in guide star height vs. primary diameter are quite comparable to an ELT with sodium guide stars. The use of LBT's adaptive secondary mirror, gated wavefront sensors, a prime focus calibration system and the laser constellation shows several aspects that may be used as pathfinding technology for the planned ELTs. In already planned upgrade steps with a hybrid Sodium-Rayleigh combination ARGOS will enable MCAO and MOAO implementations at LBT allowing unique astronomical observations.

Tunable Molecular Lasers.

DTIC Science & Technology

1986-09-01

689 (1983). ~~ +. 10. H . Helvajian and C. Wittig, "Vibration quenching of HgBrx 2 E 1 2 ) " Appl. Phys. Lett. 38, 731-733 (1981). 11. N. H . Cheung...aSE (the UV- band stimulated-emission cross section) - 5 X 10- 16 cm 2 and 5 -0 h =uv 5.8 X I0- 19 J. Therefore the stimulated-emission rate 0 at 342...nm is aSEIuv( h ) - ’ - 1.7 X 109 sec - ’ for an intensity - 4 - of 2 MW cm- 2 (no injected green-laser energy). Next, quenching of the 12 D’ state is

Micro-Welding of Copper Plate by Frequency Doubled Diode Pumped Pulsed Nd:YAG Laser

NASA Astrophysics Data System (ADS)

Nakashiba, Shin-Ichi; Okamoto, Yasuhiro; Sakagawa, Tomokazu; Takai, Sunao; Okada, Akira

A pulsed laser of 532 nm wavelength with ms range pulse duration was newly developed by second harmonic generation of diode pumped pulsed Nd:YAG laser. High electro-optical conversion efficiency more than 13% could be achieved, and 1.5 kW peak power green laser pulse was put in optical fiber of 100 μm in diameter. In micro- welding of 1.0 mm thickness copper plate, a keyhole welding was successfully performed by 1.0 kW peak power at spot diameter less than 200 μm. The frequency doubled pulsed laser improved the processing efficiency of copper welding, and narrow and deep weld bead was stably obtained.

Photoacoustic Tomography of Human Hepatic Malignancies Using Intraoperative Indocyanine Green Fluorescence Imaging

PubMed Central

Miyata, Akinori; Ishizawa, Takeaki; Kamiya, Mako; Shimizu, Atsushi; Kaneko, Junichi; Ijichi, Hideaki; Shibahara, Junji; Fukayama, Masashi; Midorikawa, Yutaka; Urano, Yasuteru; Kokudo, Norihiro

2014-01-01

Recently, fluorescence imaging following the preoperative intravenous injection of indocyanine green has been used in clinical settings to identify hepatic malignancies during surgery. The aim of this study was to evaluate the ability of photoacoustic tomography using indocyanine green as a contrast agent to produce representative fluorescence images of hepatic tumors by visualizing the spatial distribution of indocyanine green on ultrasonographic images. Indocyanine green (0.5 mg/kg, intravenous) was preoperatively administered to 9 patients undergoing hepatectomy. Intraoperatively, photoacoustic tomography was performed on the surface of the resected hepatic specimens (n = 10) under excitation with an 800 nm pulse laser. In 4 hepatocellular carcinoma nodules, photoacoustic imaging identified indocyanine green accumulation in the cancerous tissue. In contrast, in one hepatocellular carcinoma nodule and five adenocarcinoma foci (one intrahepatic cholangiocarcinoma and 4 colorectal liver metastases), photoacoustic imaging delineated indocyanine green accumulation not in the cancerous tissue but rather in the peri-cancerous hepatic parenchyma. Although photoacoustic tomography enabled to visualize spatial distribution of ICG on ultrasonographic images, which was consistent with fluorescence images on cut surfaces of the resected specimens, photoacoustic signals of ICG-containing tissues decreased approximately by 40% even at 4 mm depth from liver surfaces. Photoacoustic tomography using indocyanine green also failed to identify any hepatocellular carcinoma nodules from the body surface of model mice with non-alcoholic steatohepatitis. In conclusion, photoacoustic tomography has a potential to enhance cancer detectability and differential diagnosis by ultrasonographic examinations and intraoperative fluorescence imaging through visualization of stasis of bile-excreting imaging agents in and/or around hepatic tumors. However, further technical advances are needed

Photoacoustic tomography of human hepatic malignancies using intraoperative indocyanine green fluorescence imaging.

PubMed

Miyata, Akinori; Ishizawa, Takeaki; Kamiya, Mako; Shimizu, Atsushi; Kaneko, Junichi; Ijichi, Hideaki; Shibahara, Junji; Fukayama, Masashi; Midorikawa, Yutaka; Urano, Yasuteru; Kokudo, Norihiro

2014-01-01

Recently, fluorescence imaging following the preoperative intravenous injection of indocyanine green has been used in clinical settings to identify hepatic malignancies during surgery. The aim of this study was to evaluate the ability of photoacoustic tomography using indocyanine green as a contrast agent to produce representative fluorescence images of hepatic tumors by visualizing the spatial distribution of indocyanine green on ultrasonographic images. Indocyanine green (0.5 mg/kg, intravenous) was preoperatively administered to 9 patients undergoing hepatectomy. Intraoperatively, photoacoustic tomography was performed on the surface of the resected hepatic specimens (n = 10) under excitation with an 800 nm pulse laser. In 4 hepatocellular carcinoma nodules, photoacoustic imaging identified indocyanine green accumulation in the cancerous tissue. In contrast, in one hepatocellular carcinoma nodule and five adenocarcinoma foci (one intrahepatic cholangiocarcinoma and 4 colorectal liver metastases), photoacoustic imaging delineated indocyanine green accumulation not in the cancerous tissue but rather in the peri-cancerous hepatic parenchyma. Although photoacoustic tomography enabled to visualize spatial distribution of ICG on ultrasonographic images, which was consistent with fluorescence images on cut surfaces of the resected specimens, photoacoustic signals of ICG-containing tissues decreased approximately by 40% even at 4 mm depth from liver surfaces. Photoacoustic tomography using indocyanine green also failed to identify any hepatocellular carcinoma nodules from the body surface of model mice with non-alcoholic steatohepatitis. In conclusion, photoacoustic tomography has a potential to enhance cancer detectability and differential diagnosis by ultrasonographic examinations and intraoperative fluorescence imaging through visualization of stasis of bile-excreting imaging agents in and/or around hepatic tumors. However, further technical advances are needed

Design of 20 W fiber-coupled green laser diode by Zemax

NASA Astrophysics Data System (ADS)

Qi, Yunfei; Zhao, Pengfei; Wu, Yulong; Chen, Yongqi; Zou, Yonggang

2017-09-01

We represent a design of a 20 W, fiber-coupled diode laser module based on 26 single emitters at 520 nm. The module can produce more than 20 W output power from a standard fiber with core diameter of 400 μm and numerical aperture (NA) of 0.22. To achieve a 20 W laser beam, the spatial beam combination and polarization beam combination by polarization beam splitter are used to combine output of 26 single emitters into a single beam, and then an aspheric lens is used to couple the combined beam into an optical fiber. The simulation shows that the total coupling efficiency is more than 95%. Project supported by the National Key R& D Program of China (No. 2016YFB0402105), the Key Deployment Program of the Chinese Academy of Sciences (No. KGZD-SW-T01-2), and the National Natural Science Foundation of China (No. 61404135).

Laser induced mortality of Anopheles stephensi mosquitoes

NASA Astrophysics Data System (ADS)

Keller, Matthew D.; Leahy, David J.; Norton, Bryan J.; Johanson, Threeric; Mullen, Emma R.; Marvit, Maclen; Makagon, Arty

2016-02-01

Small, flying insects continue to pose great risks to both human health and agricultural production throughout the world, so there remains a compelling need to develop new vector and pest control approaches. Here, we examined the use of short (<25 ms) laser pulses to kill or disable anesthetized female Anopheles stephensi mosquitoes, which were chosen as a representative species. The mortality of mosquitoes exposed to laser pulses of various wavelength, power, pulse duration, and spot size combinations was assessed 24 hours after exposure. For otherwise comparable conditions, green and far-infrared wavelengths were found to be more effective than near- and mid-infrared wavelengths. Pulses with larger laser spot sizes required lower lethal energy densities, or fluence, but more pulse energy than for smaller spot sizes with greater fluence. Pulse duration had to be reduced by several orders of magnitude to significantly lower the lethal pulse energy or fluence required. These results identified the most promising candidates for the lethal laser component in a system being designed to identify, track, and shoot down flying insects in the wild.

Polarimetric, Two-Color, Photon-Counting Laser Altimeter Measurements of Forest Canopy Structure

NASA Technical Reports Server (NTRS)

Harding, David J.; Dabney, Philip W.; Valett, Susan

2011-01-01

Laser altimeter measurements of forest stands with distinct structures and compositions have been acquired at 532 nm (green) and 1064 nm (near-infrared) wavelengths and parallel and perpendicular polarization states using the Slope Imaging Multi-polarization Photon Counting Lidar (SIMPL). The micropulse, single photon ranging measurement approach employed by SIMPL provides canopy structure measurements with high vertical and spatial resolution. Using a height distribution analysis method adapted from conventional, 1064 nm, full-waveform lidar remote sensing, the sensitivity of two parameters commonly used for above-ground biomass estimation are compared as a function of wavelength. The results for the height of median energy (HOME) and canopy cover are for the most part very similar, indicating biomass estimations using lidars operating at green and near-infrared wavelengths will yield comparable estimates. The expected detection of increasing depolarization with depth into the canopies due to volume multiple-scattering was not observed, possibly due to the small laser footprint and the small detector field of view used in the SIMPL instrument. The results of this work provide pathfinder information for NASA's ICESat-2 mission that will employ a 532 nm, micropulse, photon counting laser altimeter.

Nanoimprinted polymer lasers with threshold below 100 W/cm2 using mixed-order distributed feedback resonators.

PubMed

Wang, Yue; Tsiminis, Georgios; Kanibolotsky, Alexander L; Skabara, Peter J; Samuel, Ifor D W; Turnbull, Graham A

2013-06-17

Organic semiconductor lasers were fabricated by UV-nanoimprint lithography with thresholds as low as 57 W/cm(2) under 4 ns pulsed operation. The nanoimprinted lasers employed mixed-order distributed feedback resonators, with second-order gratings surrounded by first-order gratings, combined with a light-emitting conjugated polymer. They were pumped by InGaN LEDs to produce green-emitting lasers, with thresholds of 208 W/cm(2) (102 nJ/pulse). These hybrid lasers incorporate a scalable UV-nanoimprint lithography process, compatible with high-performance LEDs, therefore we have demonstrated a coherent, compact, low-cost light source.

Investigating the effects of laser beams (532 and 660 nm) in annihilation of pistachio mould fungus using spectrophotometry analysis

NASA Astrophysics Data System (ADS)

Saghafi, S.; Penjweini, R.; Becker, K.; Kratky, K. W.; Dodt, H.-U.

2010-09-01

When moulds are illuminated by visible electromagnetic-EM radiations, several effects on nucleus materials and nucleotides can be detected. These effects have a significant influence on mould generation or destruction. This paper presents the effects and implications of a red diode laser beam (660 nm), a second-harmonics of a Nd:YAG laser emitting green beam (532 nm), or the combination of both, on the eradication of Pistachio mould fungus. Incident doses (ID) of both beams are kept identical throughout the experiment. The absorption spectrums of irradiated mouldy samples and the bright-greenish-yellow-fluorescence (BGYF) of fungus occurring in mould texture due to electronic excitation are investigated. We found that a combination of a green and a red laser beam with an ID of 0.5 J/cm2 provides the optimal effects on Pistachio mould fungus eradication.

Vertical cavity surface emitting lasers from all-inorganic perovskite quantum dots

NASA Astrophysics Data System (ADS)

Sun, Handong; Wang, Yue; Li, Xiaoming; Zeng, Haibo

We report the breakthrough in realizing the challenging while practically desirable vertical cavity surface emitting lasers (VCSELs) based on the CsPbX3 inorganic perovskite nanocrystals (IPNCs). These laser devices feature record low threshold (9 µJ/cm2), unidirectional output (beam divergence of 3.6º) and superb stability. We show that both single-mode and multimode lasing operation are achievable in the device. In contrast to traditional metal chacogenide colloidal quantum dots based lasers where the pump thresholds for the green and blue wavelengths are typically much higher than that of the red, these CsPbX3 IPNC-VCSEL devices are able to lase with comparable thresholds across the whole visible spectral range, which is appealing for achieving single source-pumped full-color lasers. We further reveal that these lasers can operate in quasi-steady state regime, which is very practical and cost-effective. Given the facile solution processibility, our CsPbX3 IPNC-VCSEL devices may hold great potential in developing low-cost yet high-performance lasers, promising in revolutionizing the vacuum-based epitaxial semiconductor lasers.

Intracavity doubling of cw LD pumped Nd:S-FAP laser with KTP

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang Shaojun; Sun Lianke; Wang Qingpu

In this paper the lasing performance of a intracavity doubling of CW diode-laser end-pumped Nd{sup 3+}:Sr{sub 5}(PO{sub 4}){sub 3}F, Nd:S-FAP, laser with KTP crystal was reported. The authors measured the single output performance of the green laser: the pumping threshold was 8mW; when the pumping light of 210mW was absorbed, the maximum single output at 529.7nm was 4.4mW (TEM{sub 00} mode), corresponding to a total conversion efficiency 2.1%. The comparison between experimental results and theoretical calculation was also discussed in this paper.

In vitro effectiveness of antimicrobial photodynamic therapy (APDT) using a 660 nm laser and malachite green dye in Staphylococcus aureus biofilms arranged on compact and cancellous bone specimens.

PubMed

Rosa, Luciano Pereira; da Silva, Francine Cristina; Nader, Sumaia Alves; Meira, Giselle Andrade; Viana, Magda Souza

2014-11-01

The aim of this study was to evaluate the in vitro effectiveness of antimicrobial photodynamic therapy (APDT) using a 660 nm visible laser combined with malachite green (MG) dye in the inactivation of Staphylococcus aureus (ATCC 25923) biofilms formed within compact and cancellous bone specimens. Specimens of 80 compact bones and 80 cancellous bones were contaminated with a standard suspension of S. aureus and incubated for 14 days at 37 °C to allow for the formation of biofilms. The specimens were divided into the following groups (n = 10) according to the treatment conditions: PS-L - (control - no treatment), PS+L - (only MG for 5 min), PS-L + 90 (only laser irradiation for 90 s), PS-L + 180 (only laser irradiation for 180 s), PS-L + 300 (only laser irradiation for 300 s), APDT90 (APDT for 90 s), APDT180 (APDT for 180 s), and APDT300 (APDT for 300 s). The findings were statistically analyzed using an ANOVA 5%. All of the experimental groups were significantly different from the control group for both the compact and cancellous bone specimens. The compact bone specimens that received APDT treatment (for either 90, 180, or 300 s) showed reductions in the log10 CFU/ml of S. aureus by a magnitude of 4 log10. Cancellous bone specimens treated with 300 s of APDT showed the highest efficacy, and these specimens had a reduction in S. aureus CFU/ml by a factor of 3 log10. APDT treatment using these proposed parameters in combination with MG was effective at inactivating S. aureus biofilms in compact and cancellous bone specimens.

Choroidal circulation impairment during the anterior recurrence of Vogt-Koyanagi-Harada disease confirmed with indocyanine green angiography and laser speckle flowgraphy.

PubMed

Takemoto, Yuko; Namba, Kenichi; Mizuuchi, Kazuomi; Iwata, Daiju; Uno, Tomoe; Ohno, Shigeaki; Hirooka, Kiriko; Hashimoto, Yuki; Saito, Wataru; Sugiyama, Kazuhisa; Ishida, Susumu

2016-11-01

To assess choroidal inflammation-related circulatory changes associated with the anterior recurrence of Vogt-Koyanagi-Harada (VKH) disease, using indocyanine green angiography (ICGA) and laser speckle flowgraphy (LSFG). This retrospective case series included 17 eyes of 11 patients with VKH disease showing recurrent inflammatory findings in the anterior, but not posterior, segment (i.e. anterior recurrence). Indocyanine green angiography (ICGA) and LSFG were performed at the time of recurrence and one month after the initiation of corticosteroid therapy. The number and total area of hypofluorescent dark dots (HDDs) on ICGA were independently counted by three physicians and measured with ImageJ, respectively. Mean blur rate (MBR), a quantitative index of relative blood flow velocity, was calculated via the LSFG Analyzer software. Hypofluorescent dark dots (HDDs) were identified on ICGA in 13 of 17 eyes (76%) with the anterior recurrence of VKH disease. The number and total area of HDDs significantly decreased from 203 ± 101 dots to 59 ± 51 dots and from 48 789 ± 24 251 pixels to 15 664 ± 13 254 pixels, respectively. The change ratio of MBR significantly increased by 17.9 ± 16.3% after the treatment. Importantly, there was no significant association between the change ratios of HDDs and MBR. These findings on LSFG and ICGA clearly demonstrated subclinical involvement as well as post-treatment improvement of choroidal circulation impairment due to granulomatous inflammation in eyes with the anterior recurrence of VKH disease. The present data suggest the validity of using these two examinations, capable of detecting different circulatory changes, in the management of recurrent VKH disease. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Laser Spot Welding of Copper-aluminum Joints Using a Pulsed Dual Wavelength Laser at 532 and 1064 nm

NASA Astrophysics Data System (ADS)

Stritt, Peter; Hagenlocher, Christian; Kizler, Christine; Weber, Rudolf; Rüttimann, Christoph; Graf, Thomas

A modulated pulsed laser source emitting green and infrared laser light is used to join the dissimilar metals copper and aluminum. The resultant dynamic welding process is analyzed using the back reflected laser light and high speed video observations of the interaction zone. Different pulse shapes are applied to influence the melt pool dynamics and thereby the forming grain structure and intermetallic phases. The results of high-speed images and back-reflections prove that a modulation of the pulse shape is transferred to oscillations of the melt pool at the applied frequency. The outcome of the melt pool oscillation is shown by the metallurgically prepared cross-section, which indicates different solidification lines and grain shapes. An energy-dispersivex-ray analysis shows the mixture and the resultant distribution of the two metals, copper and aluminum, within the spot weld. It can be seen that the mixture is homogenized the observed melt pool oscillations.

(In,Ga,Al)P-GaP laser diodes grown on high-index GaAs surfaces emitting in the green, yellow and bright red spectral range

NASA Astrophysics Data System (ADS)

Ledentsov, N. N.; Shchukin, V. A.; Shernyakov, Yu M.; Kulagina, M. M.; Payusov, A. S.; Gordeev, N. Yu; Maximov, M. V.; Cherkashin, N. A.

2017-02-01

We report on low threshold current density (<400 A cm-2) injection lasing in (Al x Ga1-x )0.5In0.5P-GaAs-based diodes down to the green spectral range (<570 nm). The epitaxial structures are grown on high-index (611)A and (211)A GaAs substrates by metal-organic vapor phase epitaxy and contain tensile-strained GaP-enriched insertions aimed at reflection of the injected nonequilibrium electrons preventing their escape from the active region. Extended waveguide concept results in a vertical beam divergence with a full width at half maximum of 15° for (611)A substrates. The lasing at the wavelength of 569 nm is realized at 85 K. In an orange-red laser diode structure low threshold current density (190 A cm-2) in the orange spectral range (598 nm) is realized at 85 K. The latter devices demonstrated room temperature lasing at 628 nm at ˜2 kA cm-2 and a total power above 3 W. The red laser diodes grown on (211)A substrates demonstrated a far field characteristic for vertically multimode lasing indicating a lower optical confinement factor for the fundamental mode as compared to the devices grown on (611)A. However, as expected from previous research, the temperature stability of the threshold current and the wavelength stability were significantly higher for (211)A-grown structures.

High energy 523 nm ND:YLF pulsed slab laser with novel pump beam waveguide design

NASA Astrophysics Data System (ADS)

Yang, Qi; Zhu, Xiaolei; Ma, Jian; Lu, Tingting; Ma, Xiuhua; Chen, Weibiao

2015-11-01

A laser diode pumped Nd:YLF master oscillator power amplifier (MOPA) green laser system with high pulse energy and high stable output is demonstrated. At a repetition rate of 50 Hz, 840 mJ pulse energy, 9.1 ns pulse width of 1047 nm infrared laser emitting is obtained from the MOPA system. The corresponding peak power is 93 MW. Extra-cavity frequency doubling with a LiB3O5 crystal, pulse energy of 520 mJ at 523 nm wavelength is achieved. The frequency conversion efficiency reaches up to 62%. The output pulse energy instability of the laser system is less than 0.6% for one hour.

Laser-driven polyplanar optic display

NASA Astrophysics Data System (ADS)

Veligdan, James T.; Beiser, Leo; Biscardi, Cyrus; Brewster, Calvin; DeSanto, Leonard

1998-05-01

The Polyplanar Optical Display (POD) is a unique display screen which can be used with any projection source. This display screen is 2 inches thick and has a matte-black face which allows for high contrast images. The prototype being developed is a form, fit and functional replacement display for the B-52 aircraft which uses a monochrome ten-inch display. The new display uses a 200 milliwatt green solid- state laser (532 nm) as its optical source. In order to produce real-time video, the laser light is being modulated by a Digital Light Processing (DLPTM) chip manufactured by Texas Instruments, Inc. A variable astigmatic focusing system is used to produce a stigmatic image on the viewing face of the POD. In addition to the optical design, we discuss the DLPTM chip, the opto-mechanical design and viewing angle characteristics.

Thermal damage control of dye-assisted laser tissue welding: effect of dye concentration

NASA Astrophysics Data System (ADS)

Xie, Hua; Buckley, Lisa A.; Prahl, Scott A.; Shaffer, Brian S.; Gregory, Kenton W.

2001-05-01

Successful laser-assisted tissue welding was implemented to provide proper weld strength with minimized tissue thermal injury. We investigated and compared the weld strengths and morphologic changes in porcine small intestinal submucose (SIS) and porcine ureteral tissues with various concentration of indocyanine green (ICG) and with a solid albumin sheet. The study showed that the tissues were welded at lower ICG concentration (0.05 mM) with minimized tissue thermal damage using an 800-nm wavelength diode laser.

19 CFR 351.522 - Green light and green box subsidies.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 19 Customs Duties 3 2010-04-01 2010-04-01 false Green light and green box subsidies. 351.522... COUNTERVAILING DUTIES Identification and Measurement of Countervailable Subsidies § 351.522 Green light and green... domestic support measures that are provided to certain agricultural products (i.e., products listed in...

Growth and Evaluation of Nonlinear Optical Crystals for Laser Applications: Lithium Borate, Barium Borate and Silver Gallium Selenide.

DTIC Science & Technology

1994-12-08

communication 2. S. A. Kutovi, V. V. Laptev and S. Yu. Matsnev, " Lanthanum scandoborate as a new highly efficient active medium of solid state lasers," Sov. J...34Noncritical detection of tunable C02 laser radiation into green by upconversion in silver thio- gallate ," Applied Physics B53, 19 (1991). 3. N.-H

The Laser MicroJet (LMJ): a multi-solution technology for high quality micro-machining

NASA Astrophysics Data System (ADS)

Mai, Tuan Anh; Richerzhagen, Bernold; Snowdon, Paul C.; Wood, David; Maropoulos, Paul G.

2007-02-01

The field of laser micromachining is highly diverse. There are many different types of lasers available in the market. Due to their differences in irradiating wavelength, output power and pulse characteristic they can be selected for different applications depending on material and feature size [1]. The main issues by using these lasers are heat damages, contamination and low ablation rates. This report examines on the application of the Laser MicroJet(R) (LMJ), a unique combination of a laser beam with a hair-thin water jet as a universal tool for micro-machining of MEMS substrates, as well as ferrous and non-ferrous materials. The materials include gallium arsenide (GaAs) & silicon wafers, steel, tantalum and alumina ceramic. A Nd:YAG laser operating at 1064 nm (infra red) and frequency doubled 532 nm (green) were employed for the micro-machining of these materials.

High-power direct green laser oscillation of 598 mW in Pr(3+)-doped waterproof fluoroaluminate glass fiber excited by two-polarization-combined GaN laser diodes.

PubMed

Nakanishi, Jun; Horiuchi, Yuya; Yamada, Tsuyoshi; Ishii, Osamu; Yamazaki, Masaaki; Yoshida, Minoru; Fujimoto, Yasushi

2011-05-15

We demonstrated a high-power and highly efficient Pr-doped waterproof fluoride glass fiber laser at 522.2 nm excited by two-polarization-combined GaN laser diodes and achieved a subwatt output power of 598 mW and slope efficiency of 43.0%. This system will enable us to make a vivid laser display, a photocoagulation laser for eye surgery, a color confocal scanning laser microscope, and an effective laser for material processing. Direct visible ultrashort pulse generation is also expected. © 2011 Optical Society of America

A compact frequency stabilized telecom laser diode for space applications

NASA Astrophysics Data System (ADS)

Philippe, C.; Holleville, D.; Le Targat, R.; Wolf, P.; Leveque, T.; Le Goff, R.; Martaud, E.; Acef, O.

2017-09-01

We report on a Telecom laser diode (LD) frequency stabilization to a narrow iodine hyperfine line in the green range, after frequency tripling process using fibered nonlinear waveguide PPLN crystals. We have generated up to 300 mW optical power in the green range ( 514 nm) from 800 mW of infrared power ( 1542 nm), corresponding to a nonlinear conversion efficiency h = P3?/P? 36%. Less than 10 mW of the generated green power are used for Doppler-free spectroscopy of 127I2 molecular iodine, and -therefore- for the frequency stabilization purpose. The frequency tripling optical setup is very compact (< 5 l), fully fibered, and could operate over the full C-band of the Telecom range (1530 nm - 1565 nm). Several thousands of hyperfine iodine lines may thus be interrogated in the 510 nm - 521 nm range. We build up an optical bench used at first in free space configuration, using the well-known modulation transfer spectroscopy technique (MTS), in order to test the potential of this new frequency standard based on the couple "1.5 ?m laser / iodine molecule". We have already demonstrated a preliminary frequency stability of 4.8 x 10-14 ? -1/2 with a minimum value of 6 x 10-15 reached after 50 s of integration time, conferred to a laser diode operating at 1542.1 nm. We focus now our efforts to expand the frequency stability to a longer integration time in order to meet requirements of many space experiments, such earth gravity missions, inters satellites links or space to ground communications. Furthermore, we investigate the potential of a new approach based on frequency modulation technique (FM), associated to a 3rd harmonic detection of iodine lines to increase the compactness of the optical setup.

Laser-induced Greenish-Blue Photoluminescence of Mesoporous Silicon Nanowires

PubMed Central

Choi, Yan-Ru; Zheng, Minrui; Bai, Fan; Liu, Junjun; Tok, Eng-Soon; Huang, Zhifeng; Sow, Chorng-Haur

2014-01-01

Solid silicon nanowires and their luminescent properties have been widely studied, but lesser is known about the optical properties of mesoporous silicon nanowires (mp-SiNWs). In this work, we present a facile method to generate greenish-blue photoluminescence (GB-PL) by fast scanning a focused green laser beam (wavelength of 532 nm) on a close-packed array of mp-SiNWs to carry out photo-induced chemical modification. The threshold of laser power is 5 mW to excite the GB-PL, whose intensity increases with laser power in the range of 5–105 mW. The quenching of GB-PL comes to occur beyond 105 mW. The in-vacuum annealing effectively excites the GB-PL in the pristine mp-SiNWs and enhances the GB-PL of the laser-modified mp-SiNWs. A complex model of the laser-induced surface modification is proposed to account for the laser-power and post-annealing effect. Moreover, the fast scanning of focused laser beam enables us to locally tailor mp-SiNWs en route to a wide variety of micropatterns with different optical functionality, and we demonstrate the feasibility in the application of creating hidden images. PMID:24820533

Evaluation of Analysis Conditions for Laser-Pulsed Atom Probe Tomography: Example of Cemented Tungsten Carbide.

PubMed

Peng, Zirong; Choi, Pyuck-Pa; Gault, Baptiste; Raabe, Dierk

2017-04-01

Cemented tungsten carbide has been analyzed using laser-pulsed atom probe tomography (APT). The influence of experimental parameters, including laser pulse energy, pulse repetition rate, and specimen base temperature, on the acquired data were evaluated from different aspects, such as mass spectrum, chemical composition, noise-to-signal ratio, and multiple events. Within all the applied analysis conditions, only 1 MHz pulse repetition rate led to a strong detector saturation effect, resulting in a largely biased chemical composition. A comparative study of the laser energy settings showed that an ~12 times higher energy was required for the less focused green laser of the LEAPTM 3000X HR system to achieve a similar evaporation field as the finer spot ultraviolet laser of the LEAPTM 5000 XS system.

Green Thunderstorms Observed.

NASA Astrophysics Data System (ADS)

Gallagher, Frank W., III; Beasley, William H.; Bohren, Craig F.

1996-12-01

Green thunderstorms have been observed from time to time in association with deep convection or severe weather events. Often the green coloration has been attributed to hail or to reflections of light from green foliage on the ground. Some skeptics who have not personally observed a green thunderstorm do not believe that green thunderstorms exist. They suggest that the green storms may be fabrications by excited observers. The authors have demonstrated the existence of green thunderstorms objectively using a spectrophotometer. During the spring and summer of 1995 the authors observed numerous storms and recorded hundreds of spectra of the light emanating corn these storms. It was found that the subjective judgment of colors can vary somewhat between observers, but the variation is usually in the shade of green. The authors recorded spectra of green and nongreen thunderstorms and recorded spectral measurements as a storm changed its appearance from dark blue to a bluish green. The change in color is gradual when observed from a stationary position. Also, as the light from a storm becomes greener, the luminance decreases. The authors also observed and recorded the spectrum of a thunderstorm during a period of several hours as they flew in an aircraft close to a supercell that appeared somewhat green. The authors' observations refute the ground reflection hypothesis and raise questions about explanations that require the presence of hail.

Physics of light and lasers.

PubMed

Absten, G T

1991-09-01

Because most laser procedures use the heating effect of the light and given the number of parameters that may be varied--such as power density, power, pulsing, and heating of fiber tips and probes--significant overlap in applications of the various lasers can result. This is readily apparent in the conflicting claims of laser manufacturers seen in promotional materials. Despite this, each type has its strengths. The CO2 laser is a specialty instrument, particularly for microscopic applications in neurosurgery, otolaryngology, and gynecology. Its hemostasis and vaporizing abilities allow its use in dermatology and in general surgery for tumor resection and hemostasis. In gynecology it seems best for colposcopy (cervical and vaginal) and, through a micromanipulator, for laparotomy. The beam is focused and delivered by handpieces and micromanipulators on microscopes. Through the laparoscope, it requires the use of a special laser coupler on a special laser laparoscope to allow for line-of-sight delivery of the beam through the operating channel. Waveguide delivery systems have been introduced for CO2 laser laparoscopy using standard laparoscopes. These function as hollow, slender tubes through which the beam is transmitted by means of hundreds of glancing internal reflections in the tube, which emits the beam at its tip. This eliminates many of the alignment problems of coupler cube-type systems and allows the beam to be delivered close to the target. The Nd:YAG laser is the primary endoscopic instrument in pulmonology, gastroenterology, and urology. The use of contact tips, though not a panacea, increases its applications, particularly in general surgery. Its primary use in gynecology is for endometrial ablation with bare fibers for deep coagulation. Its use for laparoscopy with contact probes or sculpted fibers is quickly growing. Green light lasers (argon and KTP) are color-selective photocoagulators and may be used to cut tissue. They are fiberoptically delivered

A New Green Titania with Enhanced NIR Absorption for Mitochondria-Targeted Cancer Therapy.

PubMed

Mou, Juan; Lin, Tianquan; Huang, Fuqiang; Shi, Jianlin; Chen, Hangrong

2017-01-01

A new kind of green titania ( G -TiO 2- x ) with obvious green color was facilely synthesized from black titania ( B -TiO 2- x ) through subsequently strong ultrasonication. Comparatively, this stable G -TiO 2- x shows much enhanced near infrared (NIR) absorption, especially around 920 nm, which can be ascribed to the obvious change of TiO 2- x lattice order owing to the effect of ultrasonication. This feature enables G -TiO 2- x to be stimulated with 980 nm laser in the combined photodynamic therapy (PDT) and photothermal therapy (PTT), which is greatly beneficial for improving tissue penetration depth. Furthermore, since mitochondria are preferred subcellular organelles for PDT/PTT, G -TiO 2- x was further designed to conjugate with triphenylphosphonium (TPP) ligand for mitochondria-targeted PDT/PTT to obtain precise cancer treatment. Attributing to the high mitochondria-targeting efficiency and simultaneously synergistic PDT/PTT, high phototherapeutic efficacy and safety with a much lower laser power density (980 nm, 0.72 W cm -2 ) and low materials dosage were achieved both in vitro and in vivo . In addition, negligible toxicity was found, indicating high biocompatibility. This novel G -TiO 2- x could provide new strategies for future precise minimal/non-invasive tumor treatment.

A New Green Titania with Enhanced NIR Absorption for Mitochondria-Targeted Cancer Therapy

PubMed Central

Mou, Juan; Lin, Tianquan; Huang, Fuqiang; Shi, Jianlin; Chen, Hangrong

2017-01-01

A new kind of green titania (G-TiO2-x) with obvious green color was facilely synthesized from black titania (B-TiO2-x) through subsequently strong ultrasonication. Comparatively, this stable G-TiO2-x shows much enhanced near infrared (NIR) absorption, especially around 920 nm, which can be ascribed to the obvious change of TiO2-x lattice order owing to the effect of ultrasonication. This feature enables G-TiO2-x to be stimulated with 980 nm laser in the combined photodynamic therapy (PDT) and photothermal therapy (PTT), which is greatly beneficial for improving tissue penetration depth. Furthermore, since mitochondria are preferred subcellular organelles for PDT/PTT, G-TiO2-x was further designed to conjugate with triphenylphosphonium (TPP) ligand for mitochondria-targeted PDT/PTT to obtain precise cancer treatment. Attributing to the high mitochondria-targeting efficiency and simultaneously synergistic PDT/PTT, high phototherapeutic efficacy and safety with a much lower laser power density (980 nm, 0.72 W cm-2) and low materials dosage were achieved both in vitro and in vivo. In addition, negligible toxicity was found, indicating high biocompatibility. This novel G-TiO2-x could provide new strategies for future precise minimal/non-invasive tumor treatment. PMID:28529636

The use of conduction model in laser weld profile computation

NASA Astrophysics Data System (ADS)

Grabas, Bogusław

2007-02-01

Profiles of joints resulting from deep penetration laser beam welding of a flat workpiece of carbon steel were computed. A semi-analytical conduction model solved with Green's function method was used in computations. In the model, the moving heat source was attenuated exponentially in accordance with Beer-Lambert law. Computational results were compared with those in the experiment.

Direct heating of a laser-imploded core using ultraintense laser LFEX

NASA Astrophysics Data System (ADS)

Kitagawa, Y.; Mori, Y.; Ishii, K.; Hanayama, R.; Nishimura, Y.; Okihara, S.; Nakayama, S.; Sekine, T.; Takagi, M.; Watari, T.; Satoh, N.; Kawashima, T.; Komeda, O.; Hioki, T.; Motohiro, T.; Azuma, H.; Sunahara, A.; Sentoku, Y.; Arikawa, Y.; Abe, Y.; Miura, E.; Ozaki, T.

2017-07-01

A CD shell was preimploded by two counter-propagating green beams from the GEKKO laser system GXII (based at the Institute of Laser Engineering, Osaka University), forming a dense core. The core was predominantly heated by energetic ions driven by the laser for fast-ignition-fusion experiment, an extremely energetic ultrashort pulse laser, that is illuminated perpendicularly to the GXII axis. Consequently, we observed the D(d, n)3 He-reacted neutrons (DD beam-fusion neutrons) at a yield of 5× {{10}8} n/4π sr. The beam-fusion neutrons verified that the ions directly collided with the core plasma. Whereas the hot electrons heated the whole core volume, the energetic ions deposited their energies locally in the core. As evidenced in the spectrum, the process simultaneously excited thermal neutrons with a yield of 6× {{10}7} n/4π sr, raising the local core temperature from 0.8 to 1.8 keV. The shell-implosion dynamics (including the beam fusion and thermal fusion initiated by fast deuterons and carbon ions) can be explained by the one-dimensional hydrocode STAR 1D. Meanwhile, the core heating due to resistive processes driven by hot electrons, and also the generation of fast ions were well-predicted by the two-dimensional collisional particle-in-cell code. Together with hot electrons, the ion contribution to fast ignition is indispensable for realizing high-gain fusion. By virtue of its core heating and ignition, the proposed scheme can potentially achieve high-gain fusion.

A novel mobile dual-wavelength laser altimetry system for improved site-specific Nitrogen fertilizer applications

NASA Astrophysics Data System (ADS)

Eitel, J.; Magney, T. S.; Vierling, L. A.; Brown, T. T.; Huggins, D. R.

2012-12-01

Reducing fertilizer inputs while maintaining yield would increase farmer's profits and similarly lessen the adverse environmental effects of production agriculture. The development of technologies that allow precise, site-specific application of Nitrogen (N) fertilizer has thus been an important research goal over the past decades. Remote sensing of foliar crop properties and function with tractor-mountable optical sensors has thought to be useful to optimize N fertilizer applications. However, on-the-go sensing of foliar crop properties and function has proven difficult, particularly during early crop growth stages when fertilizer decisions are often made. This difficulty arises from the fact that the spectral signal measured by on-the-go sensors is dominated by soil reflectance during early crop growth stages. Here, we present the basic principles behind a novel, dual-wavelength, tractor mountable laser altimetry system that measures the laser return intensity of the reflected green and red laser light. The green (532 nm) and the red (660 nm) wavelength combination allows calculation of a modified Photochemical Reflectance Index (mPRI) that have shown to be sensitive to both crop function and foliar chemistry. The small field of view of the laser points (diameter: 4 mm) combined with its high sampling rate (1000 points sec-1) allows vegetation returns to be isolated from ground returns by using simple thresholds. First tests relating foliar N of winter wheat (Triticum aestivum L.) with laser derived mPRI are promising (r2 = 0.72). Further research is needed to test the relationship between laser derived spectral indices and crop function.

An Intense Excitation Source for High Power (Blue-Green) Laser.

DTIC Science & Technology

1983-11-22

mild and forms plasma rings near the edges of the center holes as indicated by the circular line in Figure 1. For dye laser pumping, the high pressure... ring formation, and the heavy gas plasmas produce more high-intensity light pulses than light gas. It is also possible to adjust the diameter of plasma ...sheets into the center hole; 5. the formation of plasma rings ; 6. the expansion and radiative cooling of the plasma which results in 7. the intense

Noncontact microsurgery of cell membranes using femtosecond laser pulses for optoinjection of specified substances into cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Il'ina, I V; Ovchinnikov, A V; Chefonov, O V

IR femtosecond laser pulses were used for microsurgery of a cell membrane aimed at local and short-duration change in its permeability and injection of specified extracellular substances into the cells. The possibility of noncontact laser delivery of the propidium iodide fluorescent dye and the pEGFP plasmid, encoding the green fluorescent protein, into the cells with preservation of the cell viability was demonstrated. (extreme light fields and their applications)

Laser-activated protein bands for peripheral nerve repair

NASA Astrophysics Data System (ADS)

Lauto, Antonio; Trickett, Rodney I.; Malik, Richard; Dawes, Judith M.; Owen, Earl R.

1996-01-01

A 100 micrometer core optical fiber-coupled 75 mW diode laser operating at a wavelength of 800 nm has been used in conjunction with a protein solder to stripe weld severed rat tibial nerves, reducing the long operating time required for microsurgical nerve repair. Welding is produced by selective laser denaturation of the protein based solder which contains the dye indocyanine green. Operating time for laser soldering was 10 plus or minus 5 min. (n equals 24) compared to 23 plus or minus 9 min (n equals 13) for microsuturing. The laser solder technique resulted in patent welds with a tensile strength of 15 plus or minus 5 g, while microsutured nerves had a tensile strength of 40 plus or minus 10 g. Histopathology of the laser soldered nerves, conducted immediately after surgery, displayed solder adhesion to the outer membrane with minimal damage to the inner axons of the nerves. An in vivo study, with a total of fifty-seven adult male wistar rats, compared laser solder repaired tibial nerves to conventional microsuture repair. Twenty-four laser soldered nerves and thirteen sutured nerves were characterized at three months and showed successful regeneration with average compound muscle action potentials (CMAP) of 2.4 plus or minus 0.7 mV and 2.7 plus or minus 0.8 mV respectively. Histopathology of the in vivo study, confirmed the comparable regeneration of axons in laser and suture operated nerves. A faster, less damaging and long lasting laser based anastomotic technique is presented.

Alternative wavelengths for sutureless laser microvascular anastomosis: a preliminary study on acute samples.

PubMed

Bass, L S; Oz, M C; Libutti, S K; Treat, M R

1992-06-01

Attempts to improve the speed and patency of microvascular anastomosis with laser-assisted techniques have provided a modest reduction in operative time and comparable success rates. Using sutureless microvascular anastomoses, 30 end-to-end anastomoses were created in the rat carotid artery using the gallium-aluminum-arsenide diode laser (808 nm). Indocyanine green and fibrinogen were applied to enhance tissue absorption of the laser energy and strengthen the bond created. These were compared with previously reported welds using the THC:YAG laser (2150 nm). Mean welding times were 140 and 288 s, and mean bursting pressures immediately after welding were 515 and 400 mmHg for the diode and THC:YAG laser groups, respectively. Histologically, both lateral and vertical spread of thermal damage was limited. Since both lasers create welds of adequate initial strength without stay sutures and are faster and easier to use than existing systems, evaluation of long-term patency would be worthwhile.

Laser-driven polyplanar optic display

DOE Office of Scientific and Technical Information (OSTI.GOV)

Veligdan, J.T.; Biscardi, C.; Brewster, C.

1998-01-01

The Polyplanar Optical Display (POD) is a unique display screen which can be used with any projection source. This display screen is 2 inches thick and has a matte-black face which allows for high contrast images. The prototype being developed is a form, fit and functional replacement display for the B-52 aircraft which uses a monochrome ten-inch display. The new display uses a 200 milliwatt green solid-state laser (532 nm) as its optical source. In order to produce real-time video, the laser light is being modulated by a Digital Light Processing (DLP) chip manufactured by Texas Instruments, Inc. A variablemore » astigmatic focusing system is used to produce a stigmatic image on the viewing face of the POD. In addition to the optical design, the authors discuss the DLP chip, the optomechanical design and viewing angle characteristics.« less

Simultaneous three wavelength imaging with a scanning laser ophthalmoscope.

PubMed

Reinholz, F; Ashman, R A; Eikelboom, R H

1999-11-01

Various imaging properties of scanning laser ophthalmoscopes (SLO) such as contrast or depth discrimination, are superior to those of the traditional photographic fundus camera. However, most SLO are monochromatic whereas photographic systems produce colour images, which inherently contain information over a broad wavelength range. An SLO system has been modified to allow simultaneous three channel imaging. Laser light sources in the visible and infrared spectrum were concurrently launched into the system. Using different wavelength triads, digital fundus images were acquired at high frame rates. Favourable wavelengths combinations were established and high contrast, true (red, green, blue) or false (red, green, infrared) colour images of the retina were recorded. The monochromatic frames which form the colour image exhibit improved distinctness of different retinal structures such as the nerve fibre layer, the blood vessels, and the choroid. A multi-channel SLO combines the advantageous imaging properties of a tunable, monochrome SLO with the benefits and convenience of colour ophthalmoscopy. The options to modify parameters such as wavelength, intensity, gain, beam profile, aperture sizes, independently for every channel assign a high degree of versatility to the system. Copyright 1999 Wiley-Liss, Inc.

Green Power Partnership 100 Green Power Users

EPA Pesticide Factsheets

EPA's Green Power Partnership is a voluntary program designed to reduce the environmental impact of electricity generation by promoting renewable energy. Partners on this list use green power to meet 100 of their U.S. organization-wide electricity use.

Effects of optical dopants and laser wavelength on atom probe tomography analyses of borosilicate glasses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Xiaonan; Schreiber, Daniel K.; Neeway, James J.

Atom probe tomography (APT) is a novel analytical microscopy method that provides three dimensional elemental mapping with sub-nanometer spatial resolution and has only recently been applied to insulating glass and ceramic samples. In this paper, we have studied the influence of the optical absorption in glass samples on APT characterization by introducing different transition metal optical dopants to a model borosilicate nuclear waste glass (international simple glass). A systematic comparison is presented of the glass optical properties and the resulting APT data quality in terms of compositional accuracy and the mass spectra quality for two APT systems: one with amore » green laser (532 nm, LEAP 3000X HR) and one with a UV laser (355 nm, LEAP 4000X HR). These data were also compared to the study of a more complex borosilicate glass (SON68). The results show that the analysis data quality such as compositional accuracy and total ions collected, was clearly linked to optical absorption when using a green laser, while for the UV laser optical doping aided in improving data yield but did not have a significant effect on compositional accuracy. Comparisons of data between the LEAP systems suggest that the smaller laser spot size of the LEAP 4000X HR played a more critical role for optimum performance than the optical dopants themselves. The smaller spot size resulted in more accurate composition measurements due to a reduced background level independent of the material’s optical properties.« less

Transcutaneous laser treatment of leg veins.

PubMed

Meesters, Arne A; Pitassi, Luiza H U; Campos, Valeria; Wolkerstorfer, Albert; Dierickx, Christine C

2014-03-01

properties of the target structure, (2) pulse stacking and multiple pass laser treatment, (3) combination of laser therapy with sclerotherapy or radiofrequency, and (4) indocyanin green enhanced laser therapy. Future studies will have to confirm the role of these developments in the treatment of leg veins. The literature still lacks double-blind controlled clinical trials comparing the different laser modalities with each other and with sclerotherapy. Such trials should be the focus of future research.

Green Chemistry Metrics with Special Reference to Green Analytical Chemistry.

PubMed

Tobiszewski, Marek; Marć, Mariusz; Gałuszka, Agnieszka; Namieśnik, Jacek

2015-06-12

The concept of green chemistry is widely recognized in chemical laboratories. To properly measure an environmental impact of chemical processes, dedicated assessment tools are required. This paper summarizes the current state of knowledge in the field of development of green chemistry and green analytical chemistry metrics. The diverse methods used for evaluation of the greenness of organic synthesis, such as eco-footprint, E-Factor, EATOS, and Eco-Scale are described. Both the well-established and recently developed green analytical chemistry metrics, including NEMI labeling and analytical Eco-scale, are presented. Additionally, this paper focuses on the possibility of the use of multivariate statistics in evaluation of environmental impact of analytical procedures. All the above metrics are compared and discussed in terms of their advantages and disadvantages. The current needs and future perspectives in green chemistry metrics are also discussed.

Spectroscopic properties and amplified spontaneous emission of fluorescein laser dye in ionic liquids as green media

NASA Astrophysics Data System (ADS)

AL-Aqmar, Dalal M.; Abdelkader, H. I.; Abou Kana, Maram T. H.

2015-09-01

The use of ionic liquids (ILs) as milieu materials for laser dyes is a promising field and quite competitive with volatile organic solvents and solid state-dye laser systems. This paper investigates some photo-physical parameters of fluorescein dye incorporated into ionic liquids; 1-Butyl-3-methylimidazolium chloride (BMIM Cl), 1-Butyl-3-methylimidazolium tetrachloroaluminate (BMIM AlCl4) and 1-Butyl-3-methylimidazolium tetrafluoroborate (BMIM BF4) as promising host matrix in addition to ethanol as reference. These parameters are: absorption and emission cross-sections, fluorescence lifetime and quantum yield, in addition to the transition dipole moment, the attenuation length and oscillator strength were also investigated. Lasing characteristics such as amplified spontaneous emission (ASE), the gain, and the photostability of fluorescein laser dye dissolved in different host materials were assessed. The composition and properties of the matrix of ILs were found that it has great interest in optimizing the laser performance and photostability of the investigated laser dye. Under transverse pumping of fluorescein dye by blue laser diode (450 nm) of (400 mW), the initial ASE for dye dissolved in BMIM AlCl4 and ethanol were decreased to 39% and 36% respectively as time progressed 132 min. Relatively high efficiency and high fluorescence quantum yield (11.8% and 0.82% respectively) were obtained with good photostability in case of fluorescein in BMIM BF4 that was decreased to ∼56% of the initial ASE after continuously pumping with 400 mW for 132 min.

Sub-micrometric surface texturing of AZ31 Mg-alloy through two-beam direct laser interference patterning with a ns-pulsed green fiber laser

NASA Astrophysics Data System (ADS)

Furlan, Valentina; Biondi, Marco; Demir, Ali Gökhan; Pariani, Giorgio; Previtali, Barbara; Bianco, Andrea

2017-11-01

Two-beam direct laser interference patterning (DLIP) is the method that employs two beams and provides control over the pattern geometry by regulating the angle between the beams and the wavelength of the beam. Despite the simplistic optical arrangement required for the method, the feasibility of sub-micrometric patterning of a surface depends on the correct manipulation of the process parameters, especially in the case of metallic materials. Magnesium alloys, from this point of view, exhibit further difficulty in processability due to low melting point and high reactivity. With biocompatibility and biodegradability features, Mg-alloy implants can take further advantage of surface structuring for tailoring the biological behaviour. In this work, a two-beam DLIP setup has been developed employing an industrial grade nanosecond-pulsed fiber laser emitting at 532 nm. The high repetition rate and ramped pulse profile provided by the laser were exploited for a more flexible control over the energy content deposited over the heat-sensitive Mg-alloy. The paper describes the strategies developed for controlling ramped laser emission at 20 kHz repetition rate. The process feasibility window was assessed within a large range of parameters. Within the feasibility window, a complete experimental plan was applied to investigate the effect of main laser process parameters on the pattern dimensions. Periodic surface structures with good definition down to 580 nm ± 20 nm spacing were successfully produced.

Bathymetry from fusion of airborne hyperspectral and laser data

NASA Astrophysics Data System (ADS)

Kappus, Mary E.; Davis, Curtiss O.; Rhea, W. Joseph

1998-10-01

Airborne hyperspectral and nadir-viewing laser data can be combined to ascertain shallow water bathymetry. The combination emphasizes the advances and overcomes the disadvantages of each method used alone. For laser systems, both the hardware and software for obtaining off-nadir measurement are complicated and expensive, while for the nadir view the conversion of laser pulse travel time to depth is straightforward. The hyperspectral systems can easily collect data in a full swath, but interpretation for water depth requires careful calibration and correction for transmittance through the atmosphere and water. Relative depths are apparent in displays of several subsets of hyperspectral data, for example, single blue-green wavelengths, endmembers that represent the pure water component of the data, or ratios of deep to shallow water endmembers. A relationship between one of these values and the depth measured by the aligned nadir laser can be determined, and then applied to the rest of the swath to obtain depth in physical units for the entire area covered. We demonstrate this technique using bathymetric charts as a proxy for laser data, and hyperspectral data taken by AVIRIS over Lake Tahoe and Key West.

Influence of laser radiation on the growth and development of seeds of agricultural plants

NASA Astrophysics Data System (ADS)

Grishkanich, Alexander; Zhevlakov, Alexander; Polyakov, Vadim; Kascheev, Sergey; Sidorov, Igor; Ruzankina, Julia; Yakovlev, Alexey; Mak, Andrey

2016-04-01

The experimental results presented in this study focused on the study of biological processes caused by exposure to the coating layers of the laser green light seed (λ = 532 nm) range for the larch, violet (λ = 405 nm) and red (λ = 640 nm) for spruce. Spend a series of experiments to study the dependence of crop seed quality (spruce and larch from the pine family) from exposure to laser radiation under different conditions. In all the analyzed groups studied seed germination and growth of seedlings exposed to laser exposure, compared with the control group. The results showed that the higher percentage of germination than seeds of the control group.

Stable room-temperature LiF:F2+* tunable color-center laser for the 830-1060-nm spectral range pumped by second-harmonic radiation from a neodymium laser

NASA Astrophysics Data System (ADS)

Ter-Mikirtychev, V. V.

1995-09-01

Simultaneous photostability and thermostability of a room-temperature LiF:F2+ * tunable color-center laser, with an operating range over 830-1060 nm, pumped by second-harmonic radiation of a YAG:Nd3+ laser with a 532-nm wavelength has been achieved. The main lasing characteristics of the obtained LiF:F2+* laser have been measured. Twenty-five percent real efficiency in a nonselective resonator cavity and 15% real efficiency in a selective resonator cavity have been obtained. The stable LiF:F2 +* laser operates at a 1-100-Hz pulse-repetition rate with a 15-ns pulse duration, a 1-1.5-cm-1 narrow-band oscillation bandwidth, and divergency of better than 6 \\times 10-4. Doubling the fundamental frequencies of F2+ * oscillation made it possible to obtain stable blue-green tunable radiation over the 415-530-nm range.

A standardized model for predicting flap failure using indocyanine green dye

NASA Astrophysics Data System (ADS)

Zimmermann, Terence M.; Moore, Lindsay S.; Warram, Jason M.; Greene, Benjamin J.; Nakhmani, Arie; Korb, Melissa L.; Rosenthal, Eben L.

2016-03-01

Techniques that provide a non-invasive method for evaluation of intraoperative skin flap perfusion are currently available but underutilized. We hypothesize that intraoperative vascular imaging can be used to reliably assess skin flap perfusion and elucidate areas of future necrosis by means of a standardized critical perfusion threshold. Five animal groups (negative controls, n=4; positive controls, n=5; chemotherapy group, n=5; radiation group, n=5; chemoradiation group, n=5) underwent pre-flap treatments two weeks prior to undergoing random pattern dorsal fasciocutaneous flaps with a length to width ratio of 2:1 (3 x 1.5 cm). Flap perfusion was assessed via laser-assisted indocyanine green dye angiography and compared to standard clinical assessment for predictive accuracy of flap necrosis. For estimating flap-failure, clinical prediction achieved a sensitivity of 79.3% and a specificity of 90.5%. When average flap perfusion was more than three standard deviations below the average flap perfusion for the negative control group at the time of the flap procedure (144.3+/-17.05 absolute perfusion units), laser-assisted indocyanine green dye angiography achieved a sensitivity of 81.1% and a specificity of 97.3%. When absolute perfusion units were seven standard deviations below the average flap perfusion for the negative control group, specificity of necrosis prediction was 100%. Quantitative absolute perfusion units can improve specificity for intraoperative prediction of viable tissue. Using this strategy, a positive predictive threshold of flap failure can be standardized for clinical use.

Decon Green (trademark)

DTIC Science & Technology

2004-11-17

Bacillus stearothermophilus spores, a species considered extremely resistant to peroxide sterilants . As seen for Decon GreenTM Classic, New Decon...Additional data is given for Bacillus anthracis and Bacillus stearothermophilus demonstrating that Decon GreenTM is also effective against bio...GreenTM retains excellent bio decon efficacy. TABLE 4. Decontamination of Bacillus stearothermophilus by New Decon GreenTM Challenge CFU Recovered

Microscopic analysis of structural changes in diode-laser-welded corneal stroma

NASA Astrophysics Data System (ADS)

Matteini, Paolo; Rossi, Francesca; Menabuoni, Luca; Pini, Roberto

2007-02-01

Diode laser welding of the cornea is a technique used to provide immediate sealing of corneal wounds: the cut is stained with a water solution of Indocyanine Green and is then irradiated with an 810 nm laser at low power densities (12-16 W/cm2), which induces a localized heating of the stroma in the range 55-66 °C range. In this study, we present a microscopic analysis aimed at evaluating the structural modifications induced in the stromal collagen of pig eyes during the laser welding of corneal wounds. Cornea samples obtained from twenty freshly-enucleated eyes were cut with a pre-calibrated knife and subjected to the laser welding procedure. Histological slices of the laser-welded stroma were examined by means of optical and transmission electron microscopy. These analyses indicated that bridges of lamellar structures crossed the wound edges with no presence of a coagulation effect. After laser welding, collagen fibrils appeared differently oriented among themselves in comparison with those of the control samples, but with similar mean fibril diameters. The laser-induced effect appeared to be confined to the ICG stained area of the cut walls, and no heat damage was observed at the operative power levels of laser corneal welding.

Electrophoretic mobility patterns of collagen following laser welding

NASA Astrophysics Data System (ADS)

Bass, Lawrence S.; Moazami, Nader; Pocsidio, Joanne O.; Oz, Mehmet C.; LoGerfo, Paul; Treat, Michael R.

1991-06-01

Clinical application of laser vascular anastomosis in inhibited by a lack of understanding of its mechanism. Whether tissue fusion results from covalent or non-covalent bonding of collagen and other structural proteins is unknown. We compared electrophoretic mobility of collagen in laser treated and untreated specimens of rat tail tendon (>90% type I collagen) and rabbit aorta. Welding was performed, using tissue shrinkage as the clinical endpoint, using the 808 nm diode laser (power density 14 watts/cm2) and topical indocyanine green dye (max absorption 805 nm). Collagen was extracted with 8 M urea (denaturing), 0.5 M acetic acid (non-denaturing) and acetic acid/pepsin (cleaves non- helical protein). Mobility patterns on gel electrophoresis (SDS-PAGE) after urea or acetic acid extraction were identical in the lasered and control tendon and vessel (confirmed by optical densitometry), revealing no evidence of formation of novel covalent bonds. Alpha and beta band intensity was diminished in pepsin incubated lasered specimens compared with controls (optical density ratio 0.00 +/- 9 tendon, 0.65 +/- 0.12 aorta), indicating the presence of denatured collagen. With the laser parameters used, collagen is denatured without formation of covalent bonds, suggesting that non-covalent interaction between denatured collagen molecules may be responsible for the weld. Based on this mechanism, welding parameters can be chosen which produce collagen denaturation without cell death.

ARGOS: the laser guide star system for the LBT

NASA Astrophysics Data System (ADS)

Rabien, S.; Ageorges, N.; Barl, L.; Beckmann, U.; Blümchen, T.; Bonaglia, M.; Borelli, J. L.; Brynnel, J.; Busoni, L.; Carbonaro, L.; Davies, R.; Deysenroth, M.; Durney, O.; Elberich, M.; Esposito, S.; Gasho, V.; Gässler, W.; Gemperlein, H.; Genzel, R.; Green, R.; Haug, M.; Hart, M. L.; Hubbard, P.; Kanneganti, S.; Masciadri, E.; Noenickx, J.; Orban de Xivry, G.; Peter, D.; Quirrenbach, A.; Rademacher, M.; Rix, H. W.; Salinari, P.; Schwab, C.; Storm, J.; Strüder, L.; Thiel, M.; Weigelt, G.; Ziegleder, J.

2010-07-01

ARGOS is the Laser Guide Star adaptive optics system for the Large Binocular Telescope. Aiming for a wide field adaptive optics correction, ARGOS will equip both sides of LBT with a multi laser beacon system and corresponding wavefront sensors, driving LBT's adaptive secondary mirrors. Utilizing high power pulsed green lasers the artificial beacons are generated via Rayleigh scattering in earth's atmosphere. ARGOS will project a set of three guide stars above each of LBT's mirrors in a wide constellation. The returning scattered light, sensitive particular to the turbulence close to ground, is detected in a gated wavefront sensor system. Measuring and correcting the ground layers of the optical distortions enables ARGOS to achieve a correction over a very wide field of view. Taking advantage of this wide field correction, the science that can be done with the multi object spectrographs LUCIFER will be boosted by higher spatial resolution and strongly enhanced flux for spectroscopy. Apart from the wide field correction ARGOS delivers in its ground layer mode, we foresee a diffraction limited operation with a hybrid Sodium laser Rayleigh beacon combination.

Dye-enhanced laser welding for skin closure.

PubMed

DeCoste, S D; Farinelli, W; Flotte, T; Anderson, R R

1992-01-01

The use of a laser to weld tissue in combination with a topical photosensitizing dye permits selective delivery of energy to the target tissue. A combination of indocyanine green (IG), absorption peak 780 nm, and the near-infrared (IR) alexandrite laser was studied with albino guinea pig skin. IG was shown to bind to the outer 25 microns of guinea pig dermis and appeared to be bound to collagen. The optical transmittance of full-thickness guinea pig skin in the near IR was 40% indicating that the alexandrite laser should provide adequate tissue penetration. Laser "welding" of skin in vivo was achieved at various concentrations of IG from 0.03 to 3 mg/cc using the alexandrite at 780 nm, 250-microseconds pulse duration, 8 Hz, and a 4-mm spot size. A spectrum of welds was obtained from 1- to 20-W/cm2 average irradiance. Weak welds occurred with no thermal damage obtained at lower irradiances: stronger welds with thermal damage confined to the weld site occurred at higher irradiances. At still higher irradiances, local vaporization occurred with failure to "weld." Thus, there was an optimal range of irradiances for "welding," which varied inversely with dye concentration. Histology confirmed the thermal damage results that were evident clinically. IG dye-enhanced laser welding is possible in skin and with further optimization may have practical application.

Investigation of the summation of copper-vapour laser frequencies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karpukhin, Vyacheslav T; Konev, Yu B; Malikov, Mikhail M

1998-09-30

An investigation was made of the conversion of the copper-vapour laser radiation ( {lambda}{sub 1} = 0.51 {mu}m and {lambda}{sub 2} = 0.578 {mu}m) into UV radiation at the sum frequency ({lambda}{sub 3} = 0.271 {mu}m) in a DKDP crystal. The operation of this frequency converter was compared for two magnifications of the laser cavity: M = 5 and 200. The best results were obtained for M = 200 (average UV radiation power 0.75 W, conversion efficiency 12%). A study was made of the characteristics of the formation of radiation pulses representing the two lines in the laser beam asmore » a whole and in its weakly diverging core. In a low-divergence beam the yellow- and green-line pulses were emitted practically simultaneously with approximately the same peak power, which facilitated the sum-frequency generation. (nonlinear optical phenomena)« less

New estimates of the CMB angular power spectra from the WMAP 5 year low-resolution data

NASA Astrophysics Data System (ADS)

Gruppuso, A.; de Rosa, A.; Cabella, P.; Paci, F.; Finelli, F.; Natoli, P.; de Gasperis, G.; Mandolesi, N.

2009-11-01

A quadratic maximum likelihood (QML) estimator is applied to the Wilkinson Microwave Anisotropy Probe (WMAP) 5 year low-resolution maps to compute the cosmic microwave background angular power spectra (APS) at large scales for both temperature and polarization. Estimates and error bars for the six APS are provided up to l = 32 and compared, when possible, to those obtained by the WMAP team, without finding any inconsistency. The conditional likelihood slices are also computed for the Cl of all the six power spectra from l = 2 to 10 through a pixel-based likelihood code. Both the codes treat the covariance for (T, Q, U) in a single matrix without employing any approximation. The inputs of both the codes (foreground-reduced maps, related covariances and masks) are provided by the WMAP team. The peaks of the likelihood slices are always consistent with the QML estimates within the error bars; however, an excellent agreement occurs when the QML estimates are used as a fiducial power spectrum instead of the best-fitting theoretical power spectrum. By the full computation of the conditional likelihood on the estimated spectra, the value of the temperature quadrupole CTTl=2 is found to be less than 2σ away from the WMAP 5 year Λ cold dark matter best-fitting value. The BB spectrum is found to be well consistent with zero, and upper limits on the B modes are provided. The parity odd signals TB and EB are found to be consistent with zero.

Third-order nonlinear optical properties of acid green 25 dye by Z-scan method

NASA Astrophysics Data System (ADS)

Jeyaram, S.; Geethakrishnan, T.

2017-03-01

Third-order nonlinear optical (NLO) properties of aqueous solutions of an anthraquinone dye (Acid green 25 dye, color index: 61570) have been studied by Z-scan method with a 5 mW continuous wave (CW) diode laser operating at 635 nm. The nonlinear refractive index (n2) and the absorption coefficient (β) have been evaluated respectively from the closed and open aperture Z-scan data and the values of these parameters are found to increase with increase in concentration of the dye solution. The negative sign of the observed nonlinear refractive index (n2) indicates that the aqueous solution of acid green 25 dye exhibits self-defocusing type optical nonlinearity. The mechanism of the observed nonlinear absorption (NLA) and nonlinear refraction (NLR) is attributed respectively to reverse saturable absorption (RSA) and thermal nonlinear effects. The magnitudes of n2 and β are found to be of the order of 10-7 cm2/W and 10-3 cm/W respectively. With these experimental results, the authors suggest that acid green 25 dye may have potential applications in nonlinear optics.

A new technique for the closure of the lens capsule by laser welding.

PubMed

Pini, Roberto; Rossi, Francesca; Menabuoni, Luca; Lenzetti, Ivo; Yoo, Sonia; Parel, Jean-Marie

2008-01-01

A new method is presented for the closure of the lens capsule based on laser welding of suitably prepared patches of anterior capsular tissue. Experiments were performed in freshly enucleated porcine eyes. The patches were previously stained with a solution of indocyanine green in sterile water and then welded on the recipient capsule by means of diode laser radiation at 810 nm. The welded tissue revealed mechanical properties comparable to those of healthy tissue. This technique is proposed to repair capsular breaks and to provide the closure of the capsulorhexis in lens refilling procedures.

Preparation and characterization of Tb3+ ions doped zincborophosphate glasses for green emission

NASA Astrophysics Data System (ADS)

Bindu, S. Hima; Raju, D. Siva; Krishna, V. Vinay; Raju, Ch. Linga

2017-06-01

The present study reports the preparation of various concentrations of Tb3+ ions doped zincborophosphate glasses and analysis by XRD, FTIR, optical, emission and decay curve spectras. The effect of borate groups on the phosphate was evidenced by FTIR spectroscopy. The JO intensity parameters was calculated using Judd-Offlet theory. The fluroscence spectra of Tb3+ doped zincborophosphate glasses revealed the efficient blue and green emissions due to 5D3 and 5D4 excited levels to 7Fj ground state respectively. The decay curves exhibits single exponential curves for all the Tb3+ ion concentrations. Various radiative and fluorescence parameters are calculated using JO intensity parameters. Based on the results obtained in the present study, the Tb3+ ions doped zincborophosphate glasses behaves as a efficient laser active materials for highintensity emissions in the green region.

Laser nanosurgery and manipulation in living cells

NASA Astrophysics Data System (ADS)

Sacconi, Leonardo; Tolic-Norrelykke, Iva M.; Antolini, Renzo; Pavone, Francesco S.

2005-03-01

We present a combination of nonlinear microscopy, laser nanosurgery and optical trapping applied to the 3D imaging and manipulation of intracellular structures in live cells. We use Titanium-sapphire laser pulses for a combined nonlinear microscopy and nanosurgery on microtubules tagged with green fluorescent protein (GFP) in fission yeast. The same laser source is also used to trap small round lipid droplets naturally present in the cell. The trapped droplets are used as handles to exert a pushing force on the nucleus, allowing for a displacement of the nucleus away from its normal position in the center of the cell. We show that nonlinear nanosurgery and optical manipulation can be performed with sub-micrometer precision and without visible collateral damage to the cell. We present this combination as an important tool in cell biology for the manipulation of specific structures in alternative to genetic methods or chemical agents. This technique can be applied to several fundamental problems in cell biology, including the study of dynamics processes in cell division.

Laser Ablated Carbon Nanodots for Light Emission.

PubMed

Reyes, Delfino; Camacho, Marco; Camacho, Miguel; Mayorga, Miguel; Weathers, Duncan; Salamo, Greg; Wang, Zhiming; Neogi, Arup

2016-12-01

The synthesis of fluorescent carbon dots-like nanostructures (CNDs) obtained through the laser ablation of a carbon solid target in liquid environment is reported. The ablation process was induced in acetone with laser pulses of 1064, 532, and 355 nm under different irradiation times. Close-spherical amorphous CNDs with sizes between 5 and 20 nm, whose abundance strongly depends on the ablation parameters were investigated using electron microscopy and was confirmed using absorption and emission spectroscopies. The π- π* electronic transition at 3.76 eV dominates the absorption for all the CNDs species synthesized under different irradiation conditions. The light emission is most efficient due to excitation at 3.54 eV with the photoluminescence intensity centered at 3.23 eV. The light emission from the CNDs is most efficient due to ablation at 355 nm. The emission wavelength of the CNDs can be tuned from the near-UV to the green wavelength region by controlling the ablation time and modifying the ablation and excitation laser wavelength.

Green Team Recognized with HHS Green Champion Award Honorable Mention | Poster

Cancer.gov

Courtesy of the NCI at Frederick Green Team The NCI at Frederick Green Team received a Department of Health and Human Services (HHS) Green Champion Award honorable mention in June for the team’s plant swap initiative, begun in October 2012.  “The Green Team has been doing a great job this past year, and it is wonderful that their efforts have been recognized by the HHS through

Laser welding of vas deferens in rodents: initial experience with fluid solders.

PubMed

Trickett, R I; Wang, D; Maitz, P; Lanzetta, M; Owen, E R

1998-01-01

This study evaluates the use of sutureless laser welding for vasovasostomy. In 14 rodents, the left vas deferens underwent vasovasostomy using an albumin-based solder applied to the adventitia of the vas deferens. The solder contained the dye, indocyanine green, to allow selective absorption and denaturation by a fiber-coupled 800-nm diode laser. The right vas deferens served as a control, receiving conventional layered microsurgical repair. We used a removable 4/0 nylon stent and microclamps to appose the vas deferens during repair, with no need for stay sutures. The mean time to perform laser solder repair (23.5 min) and conventional repair (23.3 min) were not significantly different (P=0.91). However, examination after 8 weeks showed that granuloma formation (G) and patency (P) rates for the conventional suture technique (G, 14%; P, 93%) were significantly better than observed for the laser solder technique (G, 57%; P, 50%).

Effect of laser wavelength and protein solder concentration on acute tissue repair using laser welding: initial results in a canine ureter model.

PubMed

Wright, E J; Poppas, D P

1997-01-01

Successful tissue approximation can be performed using low power laser energy combined with human albumin solder. In vitro studies were undertaken to investigate the acute repair strengths achieved using different laser wavelengths. Furthermore, we evaluated the change in repair strength with that resulted from changes in protein solder concentration. Intraluminal bursting pressure following ureterotomy repair was measured for the following laser wavelengths: 532, 808, 1,320, 2,100, and 10,600 nm. The tissue absorption characteristics of the 808-nm diode and the KTP-532-nm lasers required the addition of the exogenous chromophores indocyanine green and fluorescein, respectively. A 40% human albumin solder was incorporated in the repair of a 1.0-cm longitudinal defect in the canine ureter. Following determination of an optimal welding wavelength, human albumin solder of varying concentrations (25%, 38%, 45%, and 50%) were prepared and tested. The 1,320-nm YAG laser achieved the highest acute bursting pressure and was the most effective in this model. Of the concentrations of albumin tested, 50% human albumin yielded the greatest bursting pressures. We conclude that of the laser wavelengths evaluated, the 1,320-nm YAG achieves the strongest tissue weld in the acute ex vivo dog ureter model. In addition, when this laser system is used, the acute strength of a photothermal weld appears to be directly proportional to the concentration of human albumin solder in the range of 25 to 50%.

In vitro laser nerve repair: protein solder strip irradiation or irradiation alone?

PubMed

Trickett, I; Dawes, J M; Knowles, D S; Lanzetta, M; Owen, E R

1997-01-01

This study investigated the potential of sutureless nerve repair using two promising laser fusion methods: direct 2 microns irradiation of the epineurium, and protein solder assisted epineurial fusion using a 800 nm laser. Laser anastomosis of the rat sciatic nerve was performed in vitro without stay sutures in two groups of six animals. In the first group, direct laser fusion used a pulsed Cr, Tm: YAG laser. In the second group an albumin-based fluid solder containing the dye indocyanine green was applied to the epineurium, then irradiated with a diode laser. These two techniques were compared with regards to coaptation success and axonal damage. Direct laser welding produced weak bonds despite microscopic investigation of the irradiated nerves showing fusion of the epineurium. The unsatisfactory bonding can be attributed to poor tissue overlap and insufficient protein in the thin epineurium denaturation of underlying axons was also observed. In contrast, the laser solder method produced successful welds with greatly reduced axonal damage, and significantly improved the tensile strength. This study confirmed the technical possibilities of sutureless nerve anastomosis. Laser activated solders enable stronger bonds, by the addition of protein to the anastomosis site, and less thermal damage to underlying tissue through selective absorption of laser energy by dye in the solder. Further in vivo studies are required before drawing final conclusions.

Machining of glass and quartz using nanosecond and picosecond laser pulses

NASA Astrophysics Data System (ADS)

Ashkenasi, David; Kaszemeikat, Tristan; Mueller, Norbert; Lemke, Andreas; Eichler, Hans Joachim

2012-03-01

New laser processing strategies in micro processing of glass, quartz and other optically transparent materials are being developed with increasing effort. Utilizing diode-pumped solid-state laser generating nanosecond pulsed green (532 nm) laser light in conjunction with either scanners or special trepanning systems can provide for reliable glass machining at excellent efficiency. Micro ablation can be induced either from the front or rear side of the glass sample. Ablation rates of over 100 μm per pulse can be achieved in rear side processing. In comparison, picosecond laser processing of glass and quartz (at a wavelength of 1064 or 532 nm) yield smaller feed rates at however much better surface and bore wall quality. This is of great importance for small sized features, e.g. through-hole diameters smaller 50 μm in thin glass. Critical for applications with minimum micro cracks and maximum performance is an appropriate distribution of laser pulses over the work piece along with optimum laser parameters. Laser machining tasks are long aspect micro drilling, slanted through holes, internal contour cuts, micro pockets and more complex geometries in e.g. soda-lime glass, B33, B270, D236T, AF45 and BK7 glass, quartz, and Zerodur.

Endoscopic laser treatment for rectosigmoid villous adenoma: factors effecting the results

NASA Astrophysics Data System (ADS)

Brunetaud, Jean Marc; Maunoury, Vincent; Cochelard, Dominique; Boniface, Brigitte

1994-12-01

This present work reports the long term results after endoscopic laser treatment in 474 patients with benign rectosigmoid villous adenomas revealed by biopsy. Two types of wavelength were used: The 1.06 micrometers infrared light from the Nd:YAG laser and the green light from the argon laser or the Nd:YAG frequency doubled laser. In some patients, both wavelengths were used. Treatment was completed in 415 patients. Total tumor destruction was obtained in 92.8% of them, a carcinoma was detected in 6.5% on biopsy specimens obtained during laser treatment, and benign villous tissue persisted in 0.7%. During the average 30 mo. follow up period of the patients with total tumor destruction, 18% had a tumor recurrence. Treatment was well tolerated with a 1.8% complication rate (one perforation, one hemorrhage, and 7 stenosis requiring dilatation). Because treatment is long and difficult and cancer rate is high, endoscopic laser should be limited in patients with a circumferential villous adenoma to nonsurgical candidates. The risk of complication after surgery (some being fatal) has to be balanced against the risk of undetected carcinoma in the other patients and the indication for endoscopic laser treatment should be discussed case by case.

In vitro conjunctival incision repair by temperature-controlled laser soldering.

PubMed

Norman, Galia; Rabi, Yaron; Assia, Ehud; Katzir, Abraham

2009-01-01

The common method of closing conjunctival incisions is by suturing, which is associated with several disadvantages. It requires skill to apply and does not always provide a watertight closure, which is required in some operations (e.g., glaucoma filtration). The purpose of the present study was to evaluate laser soldering as an alternative method for closing conjunctival incisions. Conjunctival incisions of 20 ex vivo porcine eyes were laser soldered using a temperature-controlled fiberoptic laser system and an albumin mixed with indocyanine green as a solder. The control group consisted of five repaired incisions by a 10-0 nylon running suture. The leak pressure of the repaired incisions was measured. The mean leak pressure in the laser-soldered group was 132 mm Hg compared to 4 mm Hg in the sutured group. There was no statistically significant difference in both the incision's length and distance from the limbus between the groups, before and after the procedure, indicating that there was no severe thermal damage. These preliminary results clearly demonstrate that laser soldering may be a useful method for achieving an immediate watertight conjunctival wound closure. This procedure is faster and easier to apply than suturing.

Polymorph-Dependent Green, Yellow, and Red Emissions of Organic Crystals for Laser Applications.

PubMed

Xu, Zhenzhen; Zhang, Zhiwei; Jin, Xue; Liao, Qing; Fu, Hongbing

2017-12-05

Color tuning of organic solid-state luminescent materials remains difficult and time-consuming through conventional chemical synthesis. Herein, we reported highly efficient polymorph-dependent green (P1), yellow (P2), and red (P3) emissions of organic crystals made by the same molecular building blocks of 4-(2-{4-[2-(4-diphenylamino-phenyl)-vinyl]-phenyl}-vinyl)-benzonitrile (DOPVB). Single-crystal X-ray diffraction (XRD) and spectroscopic data reveal that all three polymorphs follow the herringbone packing motif in H-type aggregations. On the one hand, from P1, P2 to P3, the reduced pitch translation along π stacks increases the intermolecular interactions between adjacent molecules, therefore leading to gradually red-shifted emissions from 540, 570 to 614 nm. On the other hand, the edge-to-face arrangement and large roll translations avoid strong π-π overlap, making P1, P2 and P3 highly emissive with record-high solid-state fluorescence quantum yields of 0.60, 0.98, and 0.68, respectively. Furthermore, the optically allowed 0-1 transitions of herringbone H-aggregates of P1, P2 and P3 naturally provide a four-level scheme, enabling green and yellow amplified spontaneous emissions (ASE) with very low thresholds. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Green-Kubo relation for viscosity tested using experimental data for a two-dimensional dusty plasma

NASA Astrophysics Data System (ADS)

Feng, Yan; Goree, J.; Liu, Bin; Cohen, E. G. D.

2011-10-01

The theoretical Green-Kubo relation for viscosity is tested using experimentally obtained data. In a dusty plasma experiment, micron-sized dust particles are introduced into a partially ionized argon plasma, where they become negatively charged. They are electrically levitated to form a single-layer Wigner crystal, which is subsequently melted using laser heating. In the liquid phase, these dust particles experience interparticle electric repulsion, laser heating, and friction from the ambient neutral argon gas, and they can be considered to be in a nonequilibrium steady state. Direct measurements of the positions and velocities of individual dust particles are then used to obtain a time series for an off-diagonal element of the stress tensor and its time autocorrelation function. This calculation also requires the interparticle potential, which was not measured experimentally but was obtained using a Debye-Hückel-type model with experimentally determined parameters. Integrating the autocorrelation function over time yields the viscosity for shearing motion among dust particles. The viscosity so obtained is found to agree with results from a previous experiment using a hydrodynamical Navier-Stokes equation. This comparison serves as a test of the Green-Kubo relation for viscosity. Our result is also compared to the predictions of several simulations.

Laser Stimulated Thermoluminescence

NASA Astrophysics Data System (ADS)

Abtahi, Abdollah

Techniques for localized heating of semi-infinite single-layer and two-layer structures are investigated theoretically and experimentally, motivated by applications in thermoluminescence (TL) dosimetry of ionizing radiation. The heat-conduction equations are solved by the Green's function technique to obtain the transient temperature distribution caused by exposure to laser beams of Gaussian and uniform circular intensity profiles. It is shown that the spatio-temporal temperature response is readily monitored by the TL response that results when layer configuration contains a thermoluminescent phosphor. The experiments for the verification of the developed theory are performed with two specially constructed TL detection systems, one featuring a laser beam of Gaussian profile and the other a uniform circular laser beam. Measurements of the thermoluminescent emission from a number of different TL systems are performed and compared with computed responses on the basis of simple electron kinetics. We experiment exclusively with the commercial TL phosphor LiF:Mg,Ti(TLD-100, Harshaw), the most widely used material in thermoluminescence dosimetry. We study in detail localized Gaussian beam heating of it in the form of 0.9 mm thick slabs, self-supporting firms of fine-grain powder in a polyimide (Kapton) matrix, and on substrates of LiF single crystals or borosilicate glass. Thermoluminescent layers on glass substrates have been heated with Gaussian and uniform circular intensity profiles in two different modes: the laser beam impinges onto (a) the phosphor layer, and (b) the glass substrate. It is demonstrated that the optical and thermal behavior of the dosimeters can be determined by these methods and that, furthermore, the thermoluminescence response of a given configuration can be simulated as a function of a number of experimental parameters such as laser power, beam size, substrate and TL-layer thicknesses, and configuration of the dosimeters. In addition, we have

Selective Laser Sintering of Porous Silica Enabled by Carbon Additive

PubMed Central

Chang, Shuai; Li, Liqun; Lu, Li

2017-01-01

The aim of this study is to investigate the possibility of a freeform fabrication of porous ceramic parts through selective laser sintering (SLS). SLS was proposed to manufacture ceramic green parts because this additive manufacturing technique can be used to fabricate three-dimensional objects directly without a mold, and the technique has the capability of generating porous ceramics with controlled porosity. However, ceramic printing has not yet fully achieved its 3D fabrication capabilities without using polymer binder. Except for the limitations of high melting point, brittleness, and low thermal shock resistance from ceramic material properties, the key obstacle lies in the very poor absorptivity of oxide ceramics to fiber laser, which is widely installed in commercial SLS equipment. An alternative solution to overcome the poor laser absorptivity via improving material compositions is presented in this study. The positive effect of carbon additive on the absorptivity of silica powder to fiber laser is discussed. To investigate the capabilities of the SLS process, 3D porous silica structures were successfully prepared and characterized. PMID:29144425

Selective Laser Sintering of Porous Silica Enabled by Carbon Additive.

PubMed

Chang, Shuai; Li, Liqun; Lu, Li; Fuh, Jerry Ying Hsi

2017-11-16

The aim of this study is to investigate the possibility of a freeform fabrication of porous ceramic parts through selective laser sintering (SLS). SLS was proposed to manufacture ceramic green parts because this additive manufacturing technique can be used to fabricate three-dimensional objects directly without a mold, and the technique has the capability of generating porous ceramics with controlled porosity. However, ceramic printing has not yet fully achieved its 3D fabrication capabilities without using polymer binder. Except for the limitations of high melting point, brittleness, and low thermal shock resistance from ceramic material properties, the key obstacle lies in the very poor absorptivity of oxide ceramics to fiber laser, which is widely installed in commercial SLS equipment. An alternative solution to overcome the poor laser absorptivity via improving material compositions is presented in this study. The positive effect of carbon additive on the absorptivity of silica powder to fiber laser is discussed. To investigate the capabilities of the SLS process, 3D porous silica structures were successfully prepared and characterized.

New stable tunable solid-state dye laser in the red

NASA Astrophysics Data System (ADS)

Gvishi, Raz; Reisfeld, Renata; Burshtein, Zeev; Miron, Eli

1993-08-01

A red perylene derivative was impregnated into a composite silica-gel glass, and characterized as a dye laser material. The absorption spectrum in the range 480 - 600 nm belongs to the S0 - S1 electronic transition, with a structure reflecting the perylene skeletal vibrations, of typical energy 1100 - 1200 cm-1. An additional peak between 400 and 460 nm belongs to the S0 - S2 transition. The fluorescence exhibits a mirror image relative to the S0 - S1 absorption, with a Stokes shift of about 40 nm for the 0 - 0 transition. Laser tunability was obtained in the range 605 - 630 nm using a frequency-doubled Nd:YAG laser for pumping ((lambda) equals 532 nm). This wavelength range is important for medical applications, such as photodynamic therapy of some cancer tumors. Maximum laser efficiency of approximately 2.5% was obtained at 617 nm. Maximum output was approximately 0.36 mJ/pulse at a repetition rate of 10 Hz. Minimum laser threshold obtained was 0.45 mJ/pulse. The medium losses are attributed to an excited-state singlet-singlet absorption, with an upper limit cross-section of approximately 2.5 X 10-16 cm2. The laser output was stable over more than approximately 500,000 pulses, under excitation with the green line of a copper vapor laser (510 nm), of energy density approximately 40 mJ/cm2 per pulse. Good prospects exist for a considerable enhancement in laser output efficiency.

Green Roofs: A Part of Green Infrastructure Strategy for Urban Areas

EPA Science Inventory

This is a presentation on the basics of green roof technology. The presentation highlights some of the recent ORD research projects on green roofs and provides insight for the end user as to the benefits for green roof technology. It provides links to currently available EPA rep...

Green Builder Coalition |

Science.gov Websites

- Learn More Here - Join the Green Builder® Coalition today! - The Coalition supports the SAVE Act Assistance Advocacy Member Benefits Join Contact © 2016 Green Builder Coalition - Newsletter Signup - info @greenbuildercoalition.org - This site is green - Website by Triple Smart Follow Us

Steam cooking significantly improves in vitro bile acid binding of collard greens, kale, mustard greens, broccoli, green bell pepper, and cabbage.

PubMed

Kahlon, Talwinder Singh; Chiu, Mei-Chen M; Chapman, Mary H

2008-06-01

Bile acid binding capacity has been related to the cholesterol-lowering potential of foods and food fractions. Lowered recirculation of bile acids results in utilization of cholesterol to synthesize bile acid and reduced fat absorption. Secondary bile acids have been associated with increased risk of cancer. Bile acid binding potential has been related to lowering the risk of heart disease and that of cancer. Previously, we have reported bile acid binding by several uncooked vegetables. However, most vegetables are consumed after cooking. How cooking would influence in vitro bile acid binding of various vegetables was investigated using a mixture of bile acids secreted in human bile under physiological conditions. Eight replicate incubations were conducted for each treatment simulating gastric and intestinal digestion, which included a substrate only, a bile acid mixture only, and 6 with substrate and bile acid mixture. Cholestyramine (a cholesterol-lowering, bile acid binding drug) was the positive control treatment and cellulose was the negative control. Relative to cholestyramine, in vitro bile acid binding on dry matter basis was for the collard greens, kale, and mustard greens, 13%; broccoli, 10%; Brussels sprouts and spinach, 8%; green bell pepper, 7%; and cabbage, 5%. These results point to the significantly different (P < or = .05) health-promoting potential of collard greens = kale = mustard greens > broccoli > Brussels sprouts = spinach = green bell pepper > cabbage as indicated by their bile acid binding on dry matter basis. Steam cooking significantly improved the in vitro bile acid binding of collard greens, kale, mustard greens, broccoli, green bell pepper, and cabbage compared with previously observed bile acid binding values for these vegetables raw (uncooked). Inclusion of steam-cooked collard greens, kale, mustard greens, broccoli, green bell pepper, and cabbage in our daily diet as health-promoting vegetables should be emphasized. These green

Using LiDAR data to measure the 3D green biomass of Beijing urban forest in China.

PubMed

He, Cheng; Convertino, Matteo; Feng, Zhongke; Zhang, Siyu

2013-01-01

The purpose of the paper is to find a new approach to measure 3D green biomass of urban forest and to testify its precision. In this study, the 3D green biomass could be acquired on basis of a remote sensing inversion model in which each standing wood was first scanned by Terrestrial Laser Scanner to catch its point cloud data, then the point cloud picture was opened in a digital mapping data acquisition system to get the elevation in an independent coordinate, and at last the individual volume captured was associated with the remote sensing image in SPOT5(System Probatoired'Observation dela Tarre)by means of such tools as SPSS (Statistical Product and Service Solutions), GIS (Geographic Information System), RS (Remote Sensing) and spatial analysis software (FARO SCENE and Geomagic studio11). The results showed that the 3D green biomass of Beijing urban forest was 399.1295 million m(3), of which coniferous was 28.7871 million m(3) and broad-leaf was 370.3424 million m(3). The accuracy of 3D green biomass was over 85%, comparison with the values from 235 field sample data in a typical sampling way. This suggested that the precision done by the 3D forest green biomass based on the image in SPOT5 could meet requirements. This represents an improvement over the conventional method because it not only provides a basis to evalue indices of Beijing urban greenings, but also introduces a new technique to assess 3D green biomass in other cities.

Using LiDAR Data to Measure the 3D Green Biomass of Beijing Urban Forest in China

PubMed Central

He, Cheng; Convertino, Matteo; Feng, Zhongke; Zhang, Siyu

2013-01-01

The purpose of the paper is to find a new approach to measure 3D green biomass of urban forest and to testify its precision. In this study, the 3D green biomass could be acquired on basis of a remote sensing inversion model in which each standing wood was first scanned by Terrestrial Laser Scanner to catch its point cloud data, then the point cloud picture was opened in a digital mapping data acquisition system to get the elevation in an independent coordinate, and at last the individual volume captured was associated with the remote sensing image in SPOT5(System Probatoired'Observation dela Tarre)by means of such tools as SPSS (Statistical Product and Service Solutions), GIS (Geographic Information System), RS (Remote Sensing) and spatial analysis software (FARO SCENE and Geomagic studio11). The results showed that the 3D green biomass of Beijing urban forest was 399.1295 million m3, of which coniferous was 28.7871 million m3 and broad-leaf was 370.3424 million m3. The accuracy of 3D green biomass was over 85%, comparison with the values from 235 field sample data in a typical sampling way. This suggested that the precision done by the 3D forest green biomass based on the image in SPOT5 could meet requirements. This represents an improvement over the conventional method because it not only provides a basis to evalue indices of Beijing urban greenings, but also introduces a new technique to assess 3D green biomass in other cities. PMID:24146792

Crude Oil Remote Sensing, Characterization and Cleaning with CW and Pulsed Lasers

NASA Technical Reports Server (NTRS)

Kukhtareva, Tatiana; Chirita, Arc; Gallegos, Sonia C.

2014-01-01

For detection, identification and characterization of crude oil we combine several optical methods of remote sensing of crude oil films and emulsions (coherent fringe projection illumination (CFP), holographic in-line interferometry (HILI), and laser induced fluorescence). These methods allow the three-dimensional characterization of oil spills, important for practical applications. Combined methods of CFP and HILI are described in the frame of coherent superposition of partial interference patterns. It is shown, that in addition to detection/identification laser illumination in the green-blue region can also degrade oil slicks. Different types of surfaces contaminated by oil spills are tested: oil on the water, oil on the flat solid surfaces and oil on the curved surfaces of pipes. For the detection and monitoring of the laser-induced oil degradation in pipes, coherent fiber bundles were used. Both continuous-wave (CW) and pulsed lasers are tested using pump-probe schemes. This finding suggests that properly structured laser clean-up can be an alternative environmentally-friendly method of decontamination, as compared to the currently used chemical methods that are dangerous to environment.

Optimal parameters for laser tissue soldering

NASA Astrophysics Data System (ADS)

McNally-Heintzelman, Karen M.; Sorg, Brian S.; Chan, Eric K.; Welch, Ashley J.; Dawes, Judith M.; Owen, Earl R.

1998-07-01

Variations in laser irradiance, exposure time, solder composition, chromophore type and concentration have led to inconsistencies in published results of laser-solder repair of tissue. To determine optimal parameters for laser tissue soldering, an in vitro study was performed using an 808-nm diode laser in conjunction with an indocyanine green (ICG)- doped albumin protein solder to weld bovine aorta specimens. Liquid and solid protein solders prepared from 25% and 60% bovine serum albumin (BSA), respectively, were compared. The effects of laser irradiance and exposure time on tensile strength of the weld and temperature rise as well as the effect of hydration on bond stability were investigated. Optimum irradiance and exposure times were identified for each solder type. Increasing the BSA concentration from 25% to 60% greatly increased the tensile strength of the weld. A reduction in dye concentration from 2.5 mg/ml to 0.25 mg/ml was also found to result in an increase in tensile strength. The strongest welds were produced with an irradiance of 6.4 W/cm2 for 50 s using a solid protein solder composed of 60% BSA and 0.25 mg/ml ICG. Steady-state solder surface temperatures were observed to reach 85 plus or minus 5 degrees Celsius with a temperature gradient across the solid protein solder strips of between 15 and 20 degrees Celsius. Finally, tensile strength was observed to decrease significantly (20 to 25%) after the first hour of hydration in phosphate-buffered saline. No appreciable change was observed in the strength of the tissue bonds with further hydration.

New possibility on InZnO nano thin film for green emissive optoelectronic devices

NASA Astrophysics Data System (ADS)

Sugumaran, Sathish; Noor Bin Ahmad, Mohd; Faizal Jamlos, Mohd; Bellan, Chandar Shekar; Chandran, Sharmila; Sivaraj, Manoj

2016-04-01

Indium zinc oxide (InZnO) nano thin film was prepared from InZnO nanoparticles (NPs) by thermal evaporation technique. Fourier transform infrared spectroscopy showed the presence of metal-oxide bond. X-ray diffraction pattern revealed the mixed phase structure. The presence of elements In, Zn and O were identified from energy dispersive X-ray analysis. Size of the NPs was found to be 171 and 263 nm by transmission electron microscopy. Scanning electron microscopy image showed the spherical shape uniform morphology with uniform distribution grains. Photoluminescence spectrum exhibited a broad green emission for InZnO nano thin film. The acquired results of structure, smooth morphology and photoluminescence property suggested that the InZnO nano thin film to be a promising material for room temperature green emissive optoelectronic, laser diodes, solar cells and other optical devices.

Potassium titanyl phosphate laser tissue ablation: development and experimental validation of a new numerical model.

PubMed

Elkhalil, Hossam; Akkin, Taner; Pearce, John; Bischof, John

2012-10-01

The photoselective vaporization of prostate (PVP) green light (532 nm) laser is increasingly being used as an alternative to the transurethral resection of prostate (TURP) for treatment of benign prostatic hyperplasia (BPH) in older patients and those who are poor surgical candidates. In order to achieve the goals of increased tissue removal volume (i.e., "ablation" in the engineering sense) and reduced collateral thermal damage during the PVP green light treatment, a two dimensional computational model for laser tissue ablation based on available parameters in the literature has been developed and compared to experiments. The model is based on the control volume finite difference and the enthalpy method with a mechanistically defined energy necessary to ablate (i.e., physically remove) a volume of tissue (i.e., energy of ablation E(ab)). The model was able to capture the general trends experimentally observed in terms of ablation and coagulation areas, their ratio (therapeutic index (TI)), and the ablation rate (AR) (mm(3)/s). The model and experiment were in good agreement at a smaller working distance (WD) (distance from the tissue in mm) and a larger scanning speed (SS) (laser scan speed in mm/s). However, the model and experiment deviated somewhat with a larger WD and a smaller SS; this is most likely due to optical shielding and heat diffusion in the laser scanning direction, which are neglected in the model. This model is a useful first step in the mechanistic prediction of PVP based BPH laser tissue ablation. Future modeling efforts should focus on optical shielding, heat diffusion in the laser scanning direction (i.e., including 3D effects), convective heat losses at the tissue boundary, and the dynamic optical, thermal, and coagulation properties of BPH tissue.

Skin closure with dye-enhanced laser welding and fibrinogen.

PubMed

Wider, T M; Libutti, S K; Greenwald, D P; Oz, M C; Yager, J S; Treat, M R; Hugo, N E

1991-12-01

The topical application of wavelength-specific dye and fibrinogen has been used to enhance laser closure of vascular anastomoses. We compared the closure of skin incisions by two different dye-enhanced, fibrinogen-based laser welding systems [argon laser (power density 4.78 W/cm2) with fluorescein isothiocyanate dye (n = 32) and diode laser (power density 9.55 W/cm2) with indocyanine green dye (n = 32)] with closure by interrupted 5-0 nylon suture (n = 64) and examined tensile strength, hydroxyproline production, histology, and cosmesis. Two 3-cm full-thickness incisions were made on the shaved backs of 64 rats. One incision was closed with suture, whereas the other, after treatment with the appropriate dye, was welded with either argon- or diode-lasered fibrinogen. At postoperative days 5, 10, 15, and 28, the closure sites were harvested and sectioned for analysis. Initially, wounds closed with argon-lasered fibrinogen showed less inflammatory response, greater collagen production (34.61 +/- 0.74 mg/gm), and greater mean peak stress at rupture (64.85 lbs/in2) than those closed with suture (16.42 +/- 3.20 mg/gm, 26.68 lbs/in2) (p less than 0.05). By 15 days, both argon and diode laser closures are superior in strength and collagen production to suture closure (p less than 0.05). At 28 days, diode laser closures (1315.60 lbs/in2) are stronger than suture closures (998.09 lbs/in2), whereas both are stronger than argon laser closures (813.16 lbs/in2) (p less than 0.05). Cosmetically, argon-welded wounds consistently appeared finer and lacked cross-hatched suture scars.(ABSTRACT TRUNCATED AT 250 WORDS)

Aequorea green fluorescent protein analysis by flow cytometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ropp, J.D.; Cuthbertson, R.A.; Donahue, C.J.

The isolation and expression of the cDNA for the green fluorescent protein (GFP) from the bioluminescent jellyfish Aequorea victoria has highlighted its potential use as a marker for gene expression in a variety of cell types. The longer wavelength peak (470 nm) of GFP`s bimodal absorption spectrum better matches standard fluorescein filter sets; however, it has a considerably lower amplitude than the major absorption peak at 395. In an effort to increase the sensitivity of GFP with routinely available instrumentation, Heim et al. have generated a GFP mutant (serine-65 to threonine; S65T-GFP) which possesses a single absorption peak centered atmore » 490 nm. We have constructed this mutant in order to determine whether it or wild-type GFP (wt-GFP) afforded greater sensitivity when excited near their respective absorption maxima. Using the conventionally available 488 nm and ultraviolet (UV) laser lines from the argon ion laser as well as the 407 nm line from a krypton ion laser with enhanced violet emission, we were able to closely match the absorption maxima of both the S65T and wild-type forms of Aequorea GFP and analyze differences in fluorescence intensity of transiently transfected 293 cells with flow cytometry. The highest fluorescence signal was observed with 488 nm excitation of S65T-GFP relative to all other laser line/GFP pairs. The wt-GFP fluorescence intensity, in contrast, was significantly higher at 407 nm relative to either 488 nm or UV. These results were consistent with parallel spectrofluorometric analysis of the emission spectrum for wt-GFP and S65T- GFP. The relative contribution of cellular autofluorescence at each wavelength was also investigated and shown to be significantly reduced at 407 nm relative to either UV or 488 nm. 29 refs., 5 figs.« less

Green(ing) English: Voices Howling in the Wilderness?

ERIC Educational Resources Information Center

Bruce, Heather E.

2011-01-01

The relatively new fields of ecocriticism in literary studies and ecocomposition in rhetoric and composition studies provide a usable foundation for those interested in green(ing) English. Nevertheless, even suggesting that interest in the environment within English studies is a relatively new concern is somewhat misleading. Contemplation of…

Results from a Year of Column CO2 Measurements over Paris France using Harris GreenLITE™

NASA Astrophysics Data System (ADS)

Dobler, J. T.; Zaccheo, T. S.; Blume, N.; Broquet, G.; Ramonet, M.; Staufer, J.; Vogel, F. R.

2016-12-01

In 2013 Harris Corporation and Atmospheric and Environmental Research developed the GreenLITE™ system under a cooperative agreement with the Department of Energy, National Energy Technology Laboratory, to monitor geologic carbon storage sites on the square km scale. Since that time the system has expanded to enable coverage of areas >25 km2, and was deployed over the city of Paris, France, in November 2015. The system consists of two scanning continuous wave laser absorption spectroscopy instruments and a number of reflectors arranged to provide a number of overlapping 2-5 km chords across the 25 km2 area. The system was deployed as a demonstration for the 21st Conference of Parties (COP21), and has since been extended to a full year experiment. Operating GreenLITE for a full year will allow evaluations of seasonalvariability and enable ingestion of these measurements into inversion model frameworks to estimate the city'semissions. High resolution emissions models currently function on scales of 1-4 km2 and use in situ instrumentation located outside of the urban environment for the inversions due to challenges related to high spatio-temporal variability within the complex urban environment. GreenLITE measurements, on the other hand, provide integrated measurements on spatial and temporal scales that are more suitable for these models.This presentation will review the GreenLITE measurement approach and discuss results of the GreenLITE demonstration, including: comparisons with well calibrated Picarro and ThermoFisher in situ instruments located in or near the GreenLITE footprint, comparisons with high resolution model results, and recent steps toward using the GreenLITE data directly in the inversion models.

Lifetime behavior of laser diodes with highly strained InGaAs QWs and emission wavelength between 1120 nm and 1180 nm

NASA Astrophysics Data System (ADS)

Bugge, F.; Bege, R.; Blume, G.; Feise, D.; Sumpf, B.; Werner, N.; Zeimer, U.; Paschke, K.; Weyers, M.

2018-06-01

Highly strained InxGa1-xAs QWs are commonly used for laser diodes in the wavelength range beyond 1100 nm, but they suffer from strain induced formation of defects. The effect of different laser structures and different laser layouts on the aging behavior was investigated. If grown and processed under optimized conditions, laser diodes emitting at 1120 nm, 1156 nm and 1180 nm have lifetimes of several 1000 h up to more than 20,000 h in dependence on structure or indium content. Laser diodes with three different emission wavelength were mounted in a microoptical bench with a second harmonic generation crystal. From these benches laser emission in the green-yellow spectral range with more than 800 mW output power was obtained.

The Red Road to Green: Tribal Peoples' Worldviews Preceded "Green" Trend

ERIC Educational Resources Information Center

Pember, Mary Annette

2008-01-01

Green is definitely "in." Green refers not to fashion but the philosophy of environmental protection, stewardship, and social justice. There is nothing new about the green philosophy for tribal colleges and universities (TCUs) and the Native communities they serve. Responsible stewardship of Mother Earth is a natural outgrowth of TCU's missions…

Greening Steel Work: Varieties of Capitalism and the "Greening" of Skills

ERIC Educational Resources Information Center

Evans, Claire; Stroud, Dean

2016-01-01

An important driver of change in work, employment and skills is European Union policy aims of sustainable economic growth and the cultivation of a green economy. Part of the latter--which is supported by increasing environmental regulation--focuses on the development of a "green skills agenda," which involves the "greening" of…

In the Green

ERIC Educational Resources Information Center

Kennedy, Mike

2011-01-01

Education officials used to debate whether they could afford to pursue green design and construction. Now the green movement has gained a foothold not just in education, but in society at large, and the prevailing attitude seems to have shifted. Can schools afford "not" to go green? As budgets are slashed repeatedly, education administrators must…

Expression of red-shifted green fluorescent protein by Escherichia coli O157:H7 as a marker for the detection of cells on fresh produce.

PubMed

Takeuchi, K; Frank, J F

2001-03-01

Escherichia coli O157:H7 was transformed with a plasmid vector red-shifted green fluorescence protein (pEGFP) to express red-shifted green fluorescence protein (EGFP) from Aequorea victoria. The EGFP expression among total cells and nonviable cells was determined at the cellular level by microscopic observation of immunostained and membrane-impermeable, dye-stained cultures, respectively. E. coli O157:H7 retained pEGFP during frozen storage at -80 degrees C. The percentage of EGFP expression was improved by repeated subculturing, reaching 83.4 +/- 0.1%, although the fluorescence intensity varied among cells. A low percentage of EGFP-expressing cells was nonviable. The percentage of EGFP decreased when the culture plate was kept at 4 degrees C, suggesting that some cells lost pEGFP during refrigeration. The storage of the culture suspension in sterile deionized water at 4 degrees C for 24 h reduced the percentage of EGFP expression, indicating that some EGFP was denatured. The application of EGFP as a marker for E. coli O157:H7 on green leaf lettuce, cauliflower, and tomato was evaluated using confocal scanning laser microscopy. EGFP-transformed cells were readily visible under confocal scanning laser microscopy on all produce types. The numbers of E. coli O157:H7 cells detected with EGFP were equivalent to those detected with immunostaining for green leaf lettuce and cauliflower but less for tomato. E. coli O157:H7 attached preferentially to damaged tissues of green leaf lettuce and tomato over intact tissue surfaces and to flowerets of cauliflower than to stem surfaces. EGFP can serve as a marker to characterize E. coli O157:H7 attachment on green leaf lettuce and cauliflower but may not be suitable on tomato.

Greenhouse Gas Laser Imaging Tomography Experiment (GreenLITE): Evaluation of a new method to look at high resolution spatial/temporal distributions of carbon over key sub km sites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dobler, Jeremy; Zaccheo, T. Scott; Blume, Nathan

2015-01-01

Recently a new laser based approach for measuring area with potential for producing 2D estimates of the concentration spatial distribution has been developed through a cooperative agreement with the National Energy and Technology Laboratory of the Department of Energy, Exelis Inc. and AER Inc. The new approach is based on a pair of continuous wave intensity modulated laser absorption spectrometer transceivers, combined with a series of retro reflectors located around the perimeter of the area being monitored. The main goal of this cooperative agreement is monitoring, reporting and verification for ground carbon capture and storage projects. The system was recentlymore » tested at the Zero Emission Research and Technology site in Bozeman, MT, with underground leak rates ranging from 0.1 – 0.3 metric ton per day (T/d), as well as a 0.8 T/d surface release. Over 200 hours of data were collected over a rectangular grid 180m x 200m between August 18th and September 9th. In addition, multiple days of in situ data were acquired for the same site, using a Licor gas analyzer systems. Initial comparisons between the laser-based system and the in situ agree very well. The system is designed to operate remotely and transmit the data via a 3G/4G connection along with weather data for the site. An all web-based system ingests the data, populates a database, performs the inversion to ppm CO2 using the Line-by-Line Radiative Transfer Model (LBLRTM), and displays plots and statistics for the retrieved data. We will present an overview of the GreenLITE measurement system, outline the retrieval and reconstruction approach, and discuss results from extensive field testing.« less

Is green economy achievable through championing green growth? A local government experience from Zambia

PubMed Central

2016-01-01

The need to enhance environmental sustainability, sustainable development and growth that takes into account the well-being of the people and nature because of the increased production and consumption of goods and services is the major driver to the introduction of green economy in Zambia and countries in southern Africa. This article examines the extent to which local government in Zambia has embraced green growth and green economy and critically analyses the concept of green economy and green growth. This study is based on a review of planning and policy documents, a household questionnaire survey and interviews with various institutions, planners and rural development organisations. A number of policies implemented at the local government level were analysed and reflected upon irrespective of whether they contain the components of green growth and green economy and the extent to which they contribute to attaining green economy. The article argues that the need for economic diversification is important as far as green economy is concerned. The article recommends the need to invest in research and development in order to find more carbon-free economic activities. The conclusion is that local government is key to achieving green growth and green economy, because it is involved at all levels, from policy formulation to implementation.

What Is Green?

ERIC Educational Resources Information Center

Pokrandt, Rachel

2010-01-01

Green is a question with varying answers and sometimes no answer at all. It is a question of location, resources, people, environment, and money. As green really has no end point, a teacher's goal should be to teach students to question and consider green. In this article, the author provides several useful metrics to help technology teachers…

Coumarin-BODIPY hybrids by heteroatom linkage: versatile, tunable and photostable dye lasers for UV irradiation.

PubMed

Esnal, I; Duran-Sampedro, G; Agarrabeitia, A R; Bañuelos, J; García-Moreno, I; Macías, M A; Peña-Cabrera, E; López-Arbeloa, I; de la Moya, S; Ortiz, M J

2015-03-28

Linking amino and hydroxycoumarins to BODIPYs through the amino or hydroxyl group lets the easy construction of unprecedented photostable coumarin-BODIPY hybrids with broadened and enhanced absorption in the UV spectral region, and outstanding wavelength-tunable laser action within the green-to-red spectral region (∼520-680 nm). These laser dyes allow the generation of a valuable tunable UV (∼260-350 nm) laser source by frequency doubling, which is essential to study accurately the photochemistry of biological molecules under solar irradiation. The tunability is achieved by selecting the substitution pattern of the hybrid. Key factors are the linking heteroatom (nitrogen vs. oxygen), the number of coumarin units joined to the BODIPY framework and the involved linking positions.

Early laser operations at the Large Binocular Telescope Observatory

NASA Astrophysics Data System (ADS)

Rahmer, Gustavo; Lefebvre, Michael; Christou, Julian; Raab, Walfried; Rabien, Sebastian; Ziegleder, Julian; Borelli, José L.; Gässler, Wolfgang

2014-08-01

ARGOS is the GLAO (Ground-Layer Adaptive Optics) Rayleigh-based LGS (Laser Guide Star) facility for the Large Binocular Telescope Observatory (LBTO). It is dedicated for observations with LUCI1 and LUCI2, LBTO's pair of NIR imagers and multi-object spectrographs. The system projects three laser beams from the back of each of the two secondary mirror units, which create two constellations circumscribed on circles of 2 arcmin radius with 120 degree spacing. Each of the six Nd:YAG lasers provides a beam of green (532nm) pulses at a rate of 10kHz with a power of 14W to 18W. We achieved first on-sky propagation on the night of November 5, 2013, and commissioning of the full system will take place during 2014. We present the initial results of laser operations at the observatory, including safety procedures and the required coordination with external agencies (FAA, Space Command, and Military Airspace Manager). We also describe our operational procedures and report on our experiences with aircraft spotters. Future plans for safer and more efficient aircraft monitoring and detection are discussed.

Green Power Partnership Videos

EPA Pesticide Factsheets

The Green Power Partnership develops videos on a regular basis that explore a variety of topics including, Green Power partnership, green power purchasing, Renewable energy certificates, among others.

Single-cell optoporation and transfection using femtosecond laser and optical tweezers.

PubMed

Waleed, Muhammad; Hwang, Sun-Uk; Kim, Jung-Dae; Shabbir, Irfan; Shin, Sang-Mo; Lee, Yong-Gu

2013-01-01

In this paper, we demonstrate a new single-cell optoporation and transfection technique using a femtosecond Gaussian laser beam and optical tweezers. Tightly focused near-infrared (NIR) femtosecond laser pulse was employed to transiently perforate the cellular membrane at a single point in MCF-7 cancer cells. A distinct technique was developed by trapping the microparticle using optical tweezers to focus the femtosecond laser precisely on the cell membrane to puncture it. Subsequently, an external gene was introduced in the cell by trapping and inserting the same plasmid-coated microparticle into the optoporated cell using optical tweezers. Various experimental parameters such as femtosecond laser exposure power, exposure time, puncture hole size, exact focusing of the femtosecond laser on the cell membrane, and cell healing time were closely analyzed to create the optimal conditions for cell viability. Following the insertion of plasmid-coated microparticles in the cell, the targeted cells exhibited green fluorescent protein (GFP) under the fluorescent microscope, hence confirming successful transfection into the cell. This new optoporation and transfection technique maximizes the level of selectivity and control over the targeted cell, and this may be a breakthrough method through which to induce controllable genetic changes in the cell.

A laser induced local transfer for patterning of RGB-OLED-displays

NASA Astrophysics Data System (ADS)

Kroeger, Michael; Hueske, Marc; Dobbertin, Thomas; Meyer, Jens; Krautwald, Henning; Riedl, Thomas; Johannes, Hans-Hermann; Kowalsky, Wolfgang

2005-07-01

RGB-OLED-displays can be realized by at least three different approaches: Color from white, color from blue or patterning of red, green and blue OLEDs, which is favorable for reasons of higher efficiency and lower costs. Common patterning techniques like photolithography cannot be applied due to the degradation of the OLEDs after the exposure to solvents. Shadow masking which is currently widely applied is not applicable for bigger substrate sizes of future mass production tools. Therefore a novel approach for patterning of organic semiconductors will be demonstrated. The laser induced local transfer (LILT) of organic small molecule materials allows for mass production of high resolution RGB-OLED-displays. An infrared absorbing target is coated with the desired emitting material, which is placed in a short distance in front of an OLED substrate. A scanner deflects and focuses an infrared laser beam onto the target. By adjusting scanning speed and laser power accurately the target locally heats up to a temperature where the organic material sublimes and will be deposited on the opposite OLED substrate. By repeating this for red, green and blue emitting materials a RGB-OLED-display can be realized. For process evaluation and development a LILT-module has been built, incorporating two custom vacuum chambers, several lift and transfer stages, a high-speed high-precision scanner and an infrared continuous-wave laser (cw). This module is designed to be part of a future inline deposition system for full-color OLED displays. In the first experiments it could be observed, that the pattern resolution is strongly dependent on the scanning speed, exhibiting minimum feature sizes of 40μm. It can be deducted that this is due to the laser's beam profile (TEM00), which allows for the smallest focus possible, but may not allow for rugged process conditions suitable for production. Rectangular steep-edged beam profiles may overcome this problem.

Lasing characteristics of gas mixtures involving UFG: Application to nuclear pumping of lasers

NASA Technical Reports Server (NTRS)

Verdeyen, J. T.; Eden, J. G.

1980-01-01

Intense blue-green fluorescence from a structured band centered at lambda approximately 484 nm was observed from Ar, CF3I and NF3 gas mixtures excited by an electron beam. This emission was tentatively assigned to the E yields A transition of the iodine monofluoride (IF) molecule. The fluorescence efficiency of the IF(E yields A) band and the IF (E) state radiative lifetime were estimated to be approximately 6% and 15 ns, respectively. The emission band structure, the short IF(E) radiative lifetime and the Franck-Condon shift between the E and A states suggest that IF is an attractive candidate for a blue-green laser.

Colloidal-Quantum-Dot Ring Lasers with Active Color Control.

PubMed

le Feber, Boris; Prins, Ferry; De Leo, Eva; Rabouw, Freddy T; Norris, David J

2018-02-14

To improve the photophysical performance of colloidal quantum dots for laser applications, sophisticated core/shell geometries have been developed. Typically, a wider bandgap semiconductor is added as a shell to enhance the gain from the quantum-dot core. This shell is designed to electronically isolate the core, funnel excitons to it, and reduce nonradiative Auger recombination. However, the shell could also potentially provide a secondary source of gain, leading to further versatility in these materials. Here we develop high-quality quantum-dot ring lasers that not only exhibit lasing from both the core and the shell but also the ability to switch between them. We fabricate ring resonators (with quality factors up to ∼2500) consisting only of CdSe/CdS/ZnS core/shell/shell quantum dots using a simple template-stripping process. We then examine lasing as a function of the optical excitation power and ring radius. In resonators with quality factors >1000, excitons in the CdSe cores lead to red lasing with thresholds at ∼25 μJ/cm 2 . With increasing power, green lasing from the CdS shell emerges (>100 μJ/cm 2 ) and then the red lasing begins to disappear (>250 μJ/cm 2 ). We present a rate-equation model that can explain this color switching as a competition between exciton localization into the core and stimulated emission from excitons in the shell. Moreover, by lowering the quality factor of the cavity we can engineer the device to exhibit only green lasing. The mechanism demonstrated here provides a potential route toward color-switchable quantum-dot lasers.

Green Campus initiative and its impacts on quality of life of stakeholders in Green and Non-Green Campus universities.

PubMed

Tiyarattanachai, Ronnachai; Hollmann, Nicholas M

2016-01-01

In 2010, Universitas Indonesia (UI) developed the UI GreenMetric World University Ranking for universities to share information about their sustainability practices. This ranking system was well aligned with the basis of Sustainability for Higher Education. The scoring system can also be used as a guideline for universities to achieve sustainability in their campuses. Since its first launch, more universities around the world have increasingly participated in the ranking system including many universities in Thailand. This study compared perception of stakeholders in Green Campus and Non-Green Campus universities in Thailand regarding stakeholders' satisfaction on sustainability practices and perceived quality of life at their campuses. The results showed that stakeholders at the studied Green Campus University were more satisfied and had significantly better perceived quality of life compared to stakeholders from the studied Non-Green Campus university. The results suggested that universities should adopt the criteria set in the UI GreenMetric World University Ranking to achieve better sustainability in their campuses and improve quality of life of their stakeholders.

The Green Man

ERIC Educational Resources Information Center

Watson-Newlin, Karen

2010-01-01

The Jolly Green Giant. Robin Hood. The Bamberg Cathedral. Tales of King Arthur. Ecology. What do they have in common? What legends and ancient myths are shrouded in the tales of the Green Man? Most often perceived as an ancient Celtic symbol as the god of spring and summer, the Green Man disappears and returns year after year, century after…

Radiation data input for the design of dry or semi-dry U tailings disposal.

PubMed

Kvasnicka, J

1986-09-01

Before discussion of design criteria for the handling of dry or semi-dry tailings, it is necessary to obtain an insight into the radiation levels associated with the tailings particles and to study the basic physical properties of dry tailings. This article presents the experimental results of assessing Ra and specific alpha-activity distribution with respect to particle size of the Ranger (RUM) and Nabarlek (QML) uranium mines dry tailings samples. The variation of Rn emanation coefficient versus particle size of dry tailings has also been measured. The nuclear-track detection technique, gamma spectrometry and alpha counting were used for the above measurements. Surface Rn flux from the hypothetical Nabarlek semi-infinite dry tailings pile is 32 Bq m-2 s-1 and the Rn flux for Ranger is 10 Bq m-2 s-1. The theoretical exposure rates for 1 m above these hypothetical tailings piles are 0.95 microC kg-1 h-1 and 0.28 microC kg-1 h-1, respectively. The derived air alpha-contamination limits (DAAC) for the tailings dust were calculated to be 1.2 Bq m-3 for workers and 0.034 Bq m-3 for a member of the public. The limit for workers corresponds to the air tailings dust concentration of 0.79 mg m-3 for QML tailings and 2.2 mg m-3 for RUM tailings. The DAAC limit for the public corresponds to the air tailings dust concentration of 0.022 mg m-3 for QML tailings and 0.064 mg m-3 for RUM tailings.

High-resolution multiphoton microscopy with a low-power continuous wave laser pump.

PubMed

Chen, Xiang-Dong; Li, Shen; Du, Bo; Dong, Yang; Wang, Ze-Hao; Guo, Guang-Can; Sun, Fang-Wen

2018-02-15

Multiphoton microscopy (MPM) has been widely used for three-dimensional biological imaging. Here, based on the photon-induced charge state conversion process, we demonstrated a low-power high-resolution MPM with a nitrogen vacancy (NV) center in diamond. Continuous wave green and orange lasers were used to pump and detect the two-photon charge state conversion, respectively. The power of the laser for multiphoton excitation was 40 μW. Both the axial and lateral resolutions were improved approximately 1.5 times compared with confocal microscopy. The results can be used to improve the resolution of the NV center-based quantum sensing and biological imaging.

Green Buildings and Health.

PubMed

Allen, Joseph G; MacNaughton, Piers; Laurent, Jose Guillermo Cedeno; Flanigan, Skye S; Eitland, Erika Sita; Spengler, John D

2015-09-01

Green building design is becoming broadly adopted, with one green building standard reporting over 3.5 billion square feet certified to date. By definition, green buildings focus on minimizing impacts to the environment through reductions in energy usage, water usage, and minimizing environmental disturbances from the building site. Also by definition, but perhaps less widely recognized, green buildings aim to improve human health through design of healthy indoor environments. The benefits related to reduced energy and water consumption are well-documented, but the potential human health benefits of green buildings are only recently being investigated. The objective of our review was to examine the state of evidence on green building design as it specifically relates to indoor environmental quality and human health. Overall, the initial scientific evidence indicates better indoor environmental quality in green buildings versus non-green buildings, with direct benefits to human health for occupants of those buildings. A limitation of much of the research to date is the reliance on indirect, lagging and subjective measures of health. To address this, we propose a framework for identifying direct, objective and leading "Health Performance Indicators" for use in future studies of buildings and health.

Free-space and underwater GHz data transmission using AlGaInN laser diode technology

NASA Astrophysics Data System (ADS)

Najda, S. P.; Perlin, P.; Suski, T.; Marona, L.; Boćkowski, M.; Leszczyński, M.; Wisniewski, P.; Czernecki, R.; Kucharski, R.; Targowski, G.; Watson, S.; Kelly, A. E.

2016-05-01

Laser diodes fabricated from the AlGaInN material system is an emerging technology for defence and security applications; in particular for free space laser communication. Conventional underwater communication is done acoustically with very slow data rates, short reach, and vulnurable for interception. AlGaInN blue-green laser diode technology allows the possibility of both airbourne links and underwater telecom that operate at very fast data rates (GHz), long reach (100's of metres underwater) and can also be quantum encrypted. The latest developments in AlGaInN laser diode technology are reviewed for defence and security applications. The AlGaInN material system allows for laser diodes to be fabricated over a very wide range of wavelengths from u.v., ~380nm, to the visible ~530nm, by tuning the indium content of the laser GaInN quantum well. Ridge waveguide laser diode structures are fabricated to achieve single mode operation with optical powers of <100mW. Visible light communications at high frequency (up to 2.5 Gbit/s) using a directly modulated 422nm Galliumnitride (GaN) blue laser diode is reported in free-space and underwater.

Gross and histologic evaluation of effects of photobiomodulation, silver sulfadiazine, and a topical antimicrobial product on experimentally induced full-thickness skin wounds in green iguanas (Iguana iguana).

PubMed

Cusack, Lara M; Mayer, Joerg; Cutler, Daniel C; Rissi, Daniel R; Divers, Stephen J

2018-04-01

OBJECTIVE To assess effects of photobiomodulation, silver sulfadiazine, and a topical antimicrobial product for the treatment of experimentally induced full-thickness skin wounds in green iguanas (Iguana iguana). ANIMALS 16 healthy subadult green iguanas. PROCEDURES Iguanas were anesthetized, and three 5-mm cutaneous biopsy specimens were obtained from each iguana (day 0). Iguanas were randomly assigned to 2 treatment groups, each of which had a control treatment. Wounds in the topical treatment group received silver sulfadiazine, a topical antimicrobial product, or no treatment. Wounds in the laser treatment group received treatment with a class 4 laser at 5 or 10 J/cm 2 or no treatment. Wound measurements were obtained daily for 14 days. Iguanas were euthanized, and treatment sites were evaluated microscopically to detect ulceration, bacterial contamination, reepithelialization, necrosis, inflammation, fibrosis, and collagen maturity. RESULTS On day 14, wounds treated with a laser at 10 J/cm 2 were significantly smaller than those treated with silver sulfadiazine, but there were no other significant differences among treatments. Histologically, there were no significant differences in ulceration, bacterial infection, reepithelialization, necrosis, inflammation, fibrosis, and collagen maturity among treatments. CONCLUSIONS AND CLINICAL RELEVANCE Photobiomodulation at 10 J/cm 2 appeared to be a safe treatment that was tolerated well by green iguanas, but it did not result in substantial improvement in histologic evidence of wound healing, compared with results for other treatments or no treatment.

Laser Induced Hydrogen Generation from Coal in Water

NASA Astrophysics Data System (ADS)

Seyitliyev, Dovletgeldi; Kholikov, Khomidkhodzha; Er, Ali

We report an alternative way of obtaining hydrogen using nanosecond laser pulses and various ranks of coal and coke. SEM-EDS analysis shows the atomic concentrations of elements on each of the powders which also is in good agreement with calorimeter analysis. Coal and coke powders were irradiated with 1064nm IR and 532 nm green Nd:YAG pulsed laser beam for 45 minutes. The volume of the total gas generated after irradiation of each rank was measured using the water displacement method. The amount of gas generated increased when using 532 nm compared to 1064 nm. Post-irradiation SEM images show structural differences with samples before irradiation. The amount of gas generation with respect to laser energy density shows nonlinear correlation. Generated gas concentrations were then analyzed using gas chromatography (GC). Hydrogen and carbon monoxide were the two most highly generated gases, and the efficiency of each rank of coal was determined by analyzing the hydrogen to carbon monoxide ratio. The highest efficiency rank was anthracite, with hydrogen to carbon monoxide ratio of 1.4. GC analysis also showed that the maximum hydrogen generation occurs at 100 mJ/pulse laser energy. The efficiency of each rank of coal was observed to correlate with carbon content. American Chemical Society Petroleum Research Fund.

77 FR 24494 - Office of Federal High-Performance Green Buildings; Green Building Advisory Committee...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-24

... Federal High-Performance Green Buildings; Green Building Advisory Committee; Notification of Upcoming... agenda for the May 9, 2012, meeting of the Green Building Advisory Committee Meeting (the Committee). The... Sandler, Designated Federal Officer, Office of Federal High-Performance Green Buildings, Office of...

77 FR 66616 - Office of Federal High-Performance Green Buildings; Green Building Advisory Committee...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-11-06

... Federal High-Performance Green Buildings; Green Building Advisory Committee; Notification of Upcoming... and agenda for the November 27, 2012, meeting of the Green Building Advisory Committee Meeting (the... Green Buildings, Office of Government-wide Policy, General Services Administration, 1275 First Street NE...

78 FR 21368 - Office of Federal High-Performance Green Buildings; Green Building Advisory Committee...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-10

... Federal High-Performance Green Buildings; Green Building Advisory Committee; Notification of Upcoming... and agenda for the May 1, 2013, meeting of the Green Building Advisory Committee Meeting (the... Green Buildings, Office of Government-wide Policy, General Services Administration, 1275 First Street NE...