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Sample records for 532-nm laser light

  1. Transparency of the strong shock-compressed diamond for 532 nm laser light

    NASA Astrophysics Data System (ADS)

    Zhang, Zhiyu; Zhao, Yang; Yang, Jiamin

    2016-04-01

    An optical reflectivity and transmissivity model for the shock-compressed diamond is established and used to calculate the optical reflectivity and transmissivity of the diamond under different shock compressions. The simulated results indicate that the reflection occurs at the shock front and does not depend on the thickness of the compressed diamond, but the transmissivity decreases with the thickness. The simulated reflectivity is consistent with the experimental results in the literature, which validates the model. It is shown that the diamond keeps transparent when the shock pressure is lower than 2.00 Mbar, and becomes opaque but does not reflect the probe laser as the shock pressure increases from 2.00 Mbar to 4.60 Mbar and reflects the probe laser markedly when the shock pressure is higher than 4.60 Mbar.

  2. Miniaturized diode laser module emitting green light at 532 nm with a power of more than 900 mW for next-generation holographic displays

    NASA Astrophysics Data System (ADS)

    Hofmann, Julian; Blume, Gunnar; Jedrzejczyk, Daniel; Eppich, Bernd; Feise, David; Kreutzmann, Sabrina; Sahm, Alexander; Paschke, Katrin

    2016-02-01

    We present a micro-integrated laser module based on an amplified diode laser and second harmonic generation which is a promising candidate for a green light source in next-generation 3D holographic displays. The light emitted by the amplified laser has a wavelength of 1064 nm, reaches a power up to 8.2 W and has a long coherence length of >400 m. For second harmonic generation, we tested two geometries of periodically poled lithium niobate crystals in single pass: a bulk crystal and a planar waveguide crystal. With the planar waveguide crystal, we achieve an output power >900 mW and a coherence length >20 m at a wavelength of 532 nm.

  3. The Double-ended 750 nm and 532 nm Laser Output from PPLN-FWM

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Li, Yu-Xiang; Yao, Jian-Quan; Guo, Ling; Wang, Zhuo; Han, Sha-Sha; Zhang, Cui-Ying; Zhong, Kai

    2013-06-01

    We investigate 750 nm and 532 nm dual-wavelength laser for applications in the internet of things. A kind of optical maser is developed, in which the semiconductor module outputs the 808 nm pump light and then it goes into a double-clad Nd3+ :YAG monocrystal optical fiber through the intermediate coupler and forms a 1064 nm laser. The laser outputs come from both left and right terminals. In the right branch, the laser goes into the right cycle polarization LinNbO3 (PPLN) crystal through the right coupler, produces the optical parametric oscillation and forms the signal light λ1 (1500 nm), the idle frequency light λ2 (3660.55 nm), and the second-harmonic of the signal light λ3 (750 nm). These three kinds of light and the pump light λ4 together form the frequency matching and the quasi-phase matching, then the four-wave mixing occurs to create the high-gain light at wavelength 750 nm. Meanwhile, in the left branch, the laser goes into the left PPLN crystal through the left coupler, engenders frequency doubling and forms the light at wavelength 532 nm. That is to say, the optical maser provides 750 nm and 532 nm dual-wavelength laser outputting from two terminals, which is workable.

  4. Ageing of optical components under laser irradiation at 532nm

    NASA Astrophysics Data System (ADS)

    Becker, S.; Delrive, L.; Bouchut, P.; Andre, B.; Geffraye, F.

    2005-09-01

    The pulsed Laser Induced Damage Threshold (LIDT) of optical components usually reaches several hundreds of MW/cm2. When exposed to laser power several order of magnitude below their LIDT, the optical component lifetime is, by default, considered infinite. Under specific conditions, the accumulation of laser pulses may lead to a contamination of the surface and a degradation of its optical properties and LIDT. In the first order, these phenomena depend on the experimental conditions such as the irradiation time, the laser power, and the environment. In order to better understand the physics emphasizing this degradation, we developed an experimental cell with an in-situ spectroscopic ellipsometry diagnostic. The dry-pumped cell sheltering the sample is associated with a mass spectrometer that enables us to follow the environmental conditions in which we experiment the ageing. Anti-reflection coatings on fused silica were tested under 10 kHz-532 nm laser ageing. We present first results of degradation obtained in these conditions.

  5. Experience in the 532-nm green laser treatment of cutaneous angiodysplasias using an automatic delivery system

    NASA Astrophysics Data System (ADS)

    Mordon, Serge R.; Suchet-Lopez, Marie A.; Rotteleur, Guy; Brunetaud, Jean Marc

    1992-06-01

    Cutaneous angiodysplasias are currently treated by Argon, CW-Dye or Pulsed Dye Lasers. Green light at 532 nm is highly specific for hemoglobin-laden vessels. Therefore, this wavelength was evaluated on different cutaneous angiodysplasias. One hundred thirty-five (135) patients with either port wine stains (94) or facial telangiectasia (41) were treated with a 532 nm laser coupled to an automatic delivery system. Treatments were performed using the minimal blanching technique. The average fluence was 17 J/cm-2 for port wine stains and 15 J/cm-2 for facial telangiectasia. Pathologic scars were not reported for any patient. Sixty percent (60%) of the patients with port wine stains achieved good or excellent results after a 12-month period of observations. Ninety percent (90%) of the patients with facial telangiectasia achieved good or excellent results after a 12-month period of observation.

  6. Nanosecond-laser-induced damage in potassium titanyl phosphate: pure 532 nm pumping and frequency conversion situations

    SciTech Connect

    Wagner, Frank R.; Hildenbrand, Anne; Natoli, Jean-Yves; Commandre, Mireille

    2011-08-01

    Nanosecond-laser-induced damage measurements in the bulk of KTiOPO{sub 4} (KTP) crystals are reported using incident 532 nm light or using incident 1064 nm light, which pumps more or less efficient second harmonic generation. No damage threshold fatigue effect is observed with pure 532 nm irradiation. The damage threshold of Z-polarized light is higher than the one for X- or Y-polarized light. During frequency doubling, the damage threshold was found to be lower than for pure 1064 or 532 nm irradiation. More data to quantify the cooperative damage mechanism were generated by performing fluence ramp experiments with varying conditions and monitoring the conversion efficiency. All damage thresholds plotted against the conversion efficiency align close to a characteristic curve.

  7. Laser enhancements for Lunar Laser Ranging at 532 nm

    NASA Astrophysics Data System (ADS)

    Martinot-Lagarde, G.; Aimar, M.; Albanèse, D.; Courde, C.; Exertier, P.; Fienga, A.; Mariey, H.; Métris, G.; Rigard-Cerison, R.; Samain, E.; Torre, J.-M.; Viot, H.

    This article exposes how we improved (by more than a factor of four) the green Lunar Laser Ranging instrumental sensitivity of the French telemetric station of the "Observatoire de la Côte d'Azur" in 2012. The primary reason for this success is the doubling of the pulse energy of our green Nd:YAG laser, reaching now 200 mJ at 10 Hz. This first gain is due to the replacement (inside our oscillator cavity) of the dye cell with a CR4+:YAG crystal saturable absorber. Complementary spatial beam profile improvements are also described, regarding polarisation, flashlamp geometry and specific lens arrangements (to exclude ghosts from focusing on the 8 m long amplification chain). Those combined laser enhancements pave the way to future science breakthrough linked to quasi-millimetric determination of the Earth-Moon dynamics (Murphy, 2013). Jointly, we propose an empirical thermal lensing model, varying with the cycle ratio of the flashlamps. Our model connects Koechner's (1970) continuous pumping to our intermittent pumping case, with a "normalised heating coefficient" equalling 0.05 only if the electrical lamp input power is equal to 6 kW and scaling as this [electrical input power into the lamps] to the power of [half the pumping cycle ratio].

  8. Performance of multilayer optical coatings under long-term 532nm laser exposure

    NASA Astrophysics Data System (ADS)

    Poulios, D.; Konoplev, O.; Chiragh, F.; Vasilyev, A.; Stephen, M.; Strickler, K.

    2013-11-01

    The effects of long-term exposure to high intensity 532 nm radiation on various dielectric-coated optics are studied. To investigate potential photodarkening effects on optical surfaces, an accelerated life test platform was constructed where optics were exposed to 532 nm radiation from a short-pulse, high repetition rate fiber amplifier at total doses up to 1 trillion shots. The first run of trillion-shot tests were conducted on e-beam deposited and ion beam sputtering (IBS) coated high reflecting mirrors with onsurface intensities ranging from 1.0-1.4 GW/cm2. It was found that the e-beam coated mirrors failed catastrophically at less than 150 billion shots, while the IBS coated mirror was able to complete the trillionshot test with no measurable loss of reflectivity. Profiling the IBS mirror surface with a high-resolution white light interferometer post-irradiation revealed a ~10 nm high photocontamination deposit at the irradiation site that closely matched the intensity profile of the laser spot. Trillion-shot surface exposure tests were also conducted at multiple surface sites of an LBO frequency doubling crystal at ~1.5 GW/cm2 at multiple surface sites. The transmitted power and on-surface beam size were monitored throughout the tests, and periodic measurements of the beam quality and waist location of the transmitted light were also made using an M2 meter. No changes in transmitted power or M2 were observed in any of the tests, but 3D surface profiling revealed laser-induced contamination deposits at each site tested.

  9. Aesthetic earlobe remodeling: my personal experience with an LBO laser at 532 nm.

    PubMed

    Scrimali, Luca; Tamburino, Serena

    2014-06-01

    Since 1960, when Maiman built the first laser equipment, this technology has gone through a continuous development and an increasing utilization in several fields. Nowadays many pathologies find a less traumatic solution in laser technology. Laser can be either used to treat lesions with a high bleeding risk such as hemangioma and lymphangioma or in patients with coagulation diseases or hypertension, taking advantage of its capability to coagulate. Moreover healing and scarring are improved by the laser's effect of biostimulation and inhibition of bacterial growth, this leading to a greater comfort for the patient. The tissue vaporization and the dimension of the damaged area depend on several factors, those related to the laser used, such as wavelength, power, emission mode (continued or pulsed mode) and the power density, and those concerning to the treated tissue, like color and consistency. In this Study, we used an Lithium Borate, (LBO), laser, instead of scalpel for earlobe reduction in a 35-year-old male patient with pending lobule. LBO laser works through a solid active medium emitting a visible green light. A diode laser, with a wavelength of 810 nm, stimulates a crystal of Nd:YAG, which has a wavelength of 1064 nm. Then a crystal of LBO doubles the vibration frequency of the photons, leading to a final wavelength of 532 nm. PMID:24802299

  10. Continuous-wave single-frequency laser with dual wavelength at 1064 and 532 nm.

    PubMed

    Zhang, Chenwei; Lu, Huadong; Yin, Qiwei; Su, Jing

    2014-10-01

    A continuous-wave high-power single-frequency laser with dual-wavelength output at 1064 and 532 nm is presented. The dependencies of the output power on the transmission of the output coupler and the phase-matching temperature of the LiB(3)O(5) (LBO) crystal are studied. An output coupler with transmission of 19% is used, and the temperature of LBO is controlled to the optimal phase-matching temperature of 422 K; measured maximal output powers of 33.7 W at 1064 nm and of 1.13 W at 532 nm are obtained with optical-optical conversion efficiency of 45.6%. The laser can be single-frequency operated stably and mode-hop-free, and the measured frequency drift is less than 15 MHz in 1 min. The measured Mx2 and My2 for the 1064 nm laser are 1.06 and 1.09, respectively. The measured Mx2 and My2 for the 532 nm laser are 1.12 and 1.11, respectively. PMID:25322220

  11. Superconducting nanowire single photon detector at 532 nm and demonstration in satellite laser ranging.

    PubMed

    Li, Hao; Chen, Sijing; You, Lixing; Meng, Wengdong; Wu, Zhibo; Zhang, Zhongping; Tang, Kai; Zhang, Lu; Zhang, Weijun; Yang, Xiaoyan; Liu, Xiaoyu; Wang, Zhen; Xie, Xiaoming

    2016-02-22

    Superconducting nanowire single-photon detectors (SNSPDs) at a wavelength of 532 nm were designed and fabricated aiming to satellite laser ranging (SLR) applications. The NbN SNSPDs were fabricated on one-dimensional photonic crystals with a sensitive-area diameter of 42 μm. The devices were coupled with multimode fiber (ϕ = 50 μm) and exhibited a maximum system detection efficiency of 75% at an extremely low dark count rate of <0.1 Hz. An SLR experiment using an SNSPD at a wavelength of 532 nm was successfully demonstrated. The results showed a depth ranging with a precision of ~8.0 mm for the target satellite LARES, which is ~3,000 km away from the ground ranging station at the Sheshan Observatory. PMID:26907010

  12. Interaction between high power 532nm laser and prostatic tissue: in vivo evaluation for laser prostatectomy

    NASA Astrophysics Data System (ADS)

    Malek, Reza; Kang, Hyun Wook; Peng, Steven Yihlih; Stinson, Douglas; Beck, Michael; Koullick, Ed

    2011-03-01

    A previous in vitro study demonstrated that 180W was the optimal power to reduce photoselective vaporization of the prostate (PVP) time for larger prostate glands. In this study, we investigated anatomic and histologic outcomes and ablation parameters of 180W laser performed with a new 750-μm side-firing fiber in a survival study of living canines. Eight male canines underwent anterograde PVP with the 180W 532-nm laser. Four each animals were euthanized 3 hours or 8 weeks postoperatively. Prostates were measured and histologically analyzed after hematoxylin and eosin (H&E), triphenyltetrazolium chloride (TTC), or Gomori trichrome (GT) staining. Compared to the previous 120W laser, PVP with the 180W laser bloodlessly created a 76% larger cavity (mean 11.8 vs. 6.7 cm3; p=0.014) and ablated tissue at a 77% higher rate (mean 2.3 vs. 1.3 cm3/min; p=0.03) while H&E- and TTC-staining demonstrated its 33% thicker mean coagulation zone (2.0+/-0.4 vs. 1.5+/-0.3 mm). H&E-stained cross-sectional prostatic tissue specimens from the 3-hour (acute) group showed histologic evolution of concentric non-viable coagulation zone, partially viable hyperemic transition zone of repair, and viable non-treated zone. H&E- and GT-stained specimens from the 8-week (chronic) group revealed healed circumferentially epithelialized, non-edematous, prostatic urethral channels with no increase in collagen in the subjacent prostatic tissue vis-á-vis the normal control. Our canine study demonstrates that 180W 532-nm laser PVP with its new fiber has a significantly higher ablation rate with a more hemostatic coagulation zone, but equally favorable tissue interaction and healing, compared with our previous 120W canine study.

  13. Interaction between high power 532nm laser and prostatic tissue: in vitro evaluation for laser prostatectomy

    NASA Astrophysics Data System (ADS)

    Kang, Hyun Wook; Peng, Yihlih Steven; Stinson, Douglas

    2011-03-01

    Photoselective vaporization of the prostate (PVP) has been developed for effective treatment of obstructive benign prostatic hyperplasia. To maximize tissue ablation for large prostate gland, identifying the optimal power level for PVP is still necessary. We investigated the effect of various power levels on in vitro bovine prostate ablation with a 532-nm laser system. A custom-made 532-nm laser was employed to provide various power levels, delivered through a newly designed 750-μm side-firing fiber. Tissue ablation efficiency was evaluated in terms of power (P; 120~200W), treatment speed of fiber (TS; 2~8 mm/s), and working distance between fiber and tissue surface (WD; 1~5 mm). Coagulation depth was also estimated macroscopically and histologically (H&E) at various Ps. Both 180 and 200W yielded comparable ablated volume (104.3+/-24.7 vs. 104.1+/-23.9 mm3 at TS=4 mm/s and WD=2 mm; p=0.99); thus, 180W was identified as the optimal power to maximize tissue ablation, by removing tissue up to 80% faster than 120W (41.7+/-9.9 vs. 23.2+/-3.4 mm3/s at TS=4 mm/s and WD=2 mm; p<0.005). Tissue ablation was maximized at TS=4 mm/s and ablated equally efficiently at up to 3 mm WD (104.5+/-16.7 mm3 for WD=1 mm vs. 93.4+/-7.4 mm3 for WD=3 mm at 180W; p=0.33). The mean thickness of coagulation zone for 180W was 20% thicker than that for 120W (1.31+/-0.17 vs. 1.09+/-0.16 mm; p<0.005). The current in vitro study demonstrated that 180W was the optimal power to maximize tissue ablation efficiency with enhanced coagulation characteristics.

  14. Treatment of facial telangiectasias with a diode-pumped Nd:YAG laser at 532 nm

    NASA Astrophysics Data System (ADS)

    Cassuto, Daniel A.; Ancona, Deborah M.; Emanuelli, Guglielmo

    2000-06-01

    Facial telangiectasias are a common cause of cosmetic concern. Current treatment modalities present various effects and limits. The pulsed dye laser has been considered the golden standard in efficacy and safety. Unfortunately it causes postoperative intracutaneous hematomata that discourage many patients form undergoing this treatment. Several other vascular lasers are disadvantaged by the risk of hypopigmented and atrophic scars. We assessed a recent powerful version of the potassium titanyl phosphate 532 nm laser, that can deliver sufficient energy in single pulses lasting 10-50 msec. Collateral damage is reduced while the heating of the vessel is slow enough to avoid explosive photothermolysis with its associated purpura. Sixty-six patients with facial telangiectasias were treated. In 62/66 patients, we achieved a 75 percent-100 percent clearance of the lesions, while two treatments were needed to reach an acceptable clearance in the remaining 4/66 patients. The overall need for more sessions was well tolerated, because the acceptable postoperative appearance allowed patients to continue normal business and social activities between treatments. No permanent complications or undesired effects were noted. The KTP/532nm laser is also being tested in combined laser-sclerotherapy of fine leg capillary telangiectasias with encouraging results.

  15. Influence of consecutive picosecond pulses at 532 nm wavelength on laser ablation of human teeth

    NASA Astrophysics Data System (ADS)

    Mirdan, Balsam M.; Antonelli, Luca; Batani, Dimitri; Jafer, Rashida; Jakubowska, Katarzyna; Tarazi, Saad al; Villa, Anna Maria; Vodopivec, Bruno; Volpe, Luca

    2014-07-01

    The interaction of 40 ps pulse duration laser emitting at 532 nm wavelength with human dental tissue (enamel, dentin, and dentin-enamel junction) has been investigated. The crater profile and the surface morphology have been studied by using a confocal auto-fluorescence microscope (working in reflection mode) and a scanning electron microscope. Crater profile and crater morphology were studied after applying consecutive laser pulses and it was found that the ablation depth increases with the number of consecutive pulses, leaving the crater diameter unchanged. We found that the thermal damage is reduced by using short duration laser pulses, which implies an increased retention of restorative material. We observe carbonization of the irradiated samples, which does not imply changes in the chemical composition. Finally, the use of 40 ps pulse duration laser may become a state of art in conservative dentistry.

  16. Treatment of superficial cutaneous vascular lesions: experience with the KTP 532 nm laser.

    PubMed

    Clark, C; Cameron, H; Moseley, H; Ferguson, J; Ibbotson, S H

    2004-01-01

    Whilst most facial telangiectasias respond well to short-pulse-duration pulsed dye laser therapy, studies have shown that for the treatment of larger vessels these short-duration pulses are sub-optimal. Long-pulse frequency-doubled neodymium:YAG lasers have been introduced with pulse durations ranging from 1-50 ms and treatment beam diameters of up to 4 mm. We report the results of KTP/532 nm laser treatment for superficial vascular skin lesions. The aim was to determine the efficacy of the KTP/532 nm laser in the treatment of superficial cutaneous vascular lesions at a regional dermatology centre in a 2 year retrospective analysis. Patients were referred from general dermatology clinics to a purpose-built laser facility. A test dose was performed at the initial consultation and thereafter patients were reviewed and treated at 6 week intervals. Outcome was graded into five classifications by the patient and operator independently based on photographic records: clear, marked improvement, partial response, poor response, and no change or worsening. Over the 2 year period, 204 patients with 246 diagnoses were treated [156 female; median age 41 (range 1-74) years; Fitzpatrick skin types I-III]. Equal numbers of spider angioma (102) and facial telangiectasia (102) were treated. Of those patients who completed treatment and follow up, 57/58 (98%) of spider angiomas and 44/49 (90%) of facial telangiectasia markedly improved or cleared. Satisfactory treatment outcomes, with one clearance and two partial responses, occurred in three of five patients with port-wine stain. Few patients experienced adverse effects: two declined further treatment due to pain, and a small area of minimal superficial scarring developed in one case. Two patients developed mild persistent post-inflammatory hyperpigmentation, and one subject experienced an episode of acute facial erythema, swelling and blistering after one treatment. The KTP/532 nm frequency-doubled neodymium:YAG laser is a safe and

  17. MoXy fiber with active cooling cap for bovine prostate vaporization with high power 200W 532 nm laser

    NASA Astrophysics Data System (ADS)

    Peng, Steven Y.; Kang, Hyun Wook; Pirzadeh, Homa; Stinson, Douglas

    2011-03-01

    A novel MoXyTM fiber delivery device with Active Cooling Cap (ACCTM) is designed to transmit up to 180W of 532 nm laser light to treat benign prostatic hyperplasia (BPH). Under such high power tissue ablation, effective cooling is key to maintaining fiber power transmission and ensuring the reliability of the fiber delivery device To handle high power and reduce fiber degradation, the MoXy fiber features a larger core size (750 micrometer) and an internal fluid channel to ensure better cooling of the fiber tip to prevent the cap from burning, detaching, or shattering during the BPH treatment. The internal cooling channel was created with a metal cap and tubing that surrounds the optical fiber. In this study MoXy fibers were used to investigate the effect of power levels of 120 and 200 W on in-vitro bovine prostate ablation using a 532 nm XPSTM laser system. For procedures requiring more than 100 kJ, the MoXy fiber at 200W removed tissue at twice the rate of the current HPS fiber at 120W. The fiber maintained a constant tissue vaporization rate during the entire tissue ablation process. The coagulation at 200W was about 20% thicker than at 120W. In conclusion, the new fibers at 200W doubled the tissue removal rate, maintained vaporization efficiency throughout delivery of 400kJ energy, and induced similar coagulation to the existing HPS fiber at 120W.

  18. Optimal irradiance for sintering of inkjet-printed Ag electrodes with a 532nm CW laser

    NASA Astrophysics Data System (ADS)

    Moon, Yoon Jae; Kang, Heuiseok; Kang, Kyungtae; Hwang, Jun Young; Moon, Seung Jae

    2013-09-01

    Industrial solar cell fabrication generally adopts printing process to deposit the front electrodes, which needs additional heat treatment after printing to enhance electrical conductivity. As a heating method, laser irradiation draws attention not only because of its special selectivity, but also because of its intense heating to achieve high electric conductivity which is essential to reduce ohmic loss of solar cells. In this study, variation of electric conductivity was examined with laser irradiation having various beam intensity. 532 nm continuous wave (CW) laser was irradiated on inkjet-printed silver lines on glass substrate and electrical resistance was measured in situ during the irradiation. The results demonstrate that electric conductivity varies nonlinearly with laser intensity, having minimum specific resistance of 4.1 x 10-8 Ωm at 529 W/cm2 irradiation. The results is interesting because the specific resistance achieved by the present laser irradiation was about 1.8 times lower than the best value obtainable by oven heating, even though it was still higher by 2.5 times than that of bulk silver. It is also demonstrated that the irradiation time, needed to finish sintering process, decreases with laser intensity. The numerical simulation of laser heating showed that the optimal heating temperature could be as high as 300 oC for laser sintering, while it was limited to 250 oC for oven sintering. The nonlinear response of sintering with heating intensity was discussed, based on the results of FESEM images and XRD analysis.

  19. Photodissociation of 2, 4, 6-trinitrotoluene with a Nd:YAG laser at 532nm

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Shen, Ruiqi; Ye, Yinghua; Wu, Lizhi; Hu, Yan; Zhu, Peng

    2015-05-01

    2, 4, 6-Trinitrotoluene (TNT) belongs to the group of aromatic nitro compounds which have extended use in industrial applications, in particular as explosives or additives to explosives. Understanding the initial step of laser induced decomposition of common explosives is important to the reliability and safety of laser initiators and firing systems. Lasers coupled with mass spectrometer find wide application in photochemical studies for identification of different ions formed due to photoexcitation/ionization of molecules by laser. In this paper, a pulsed Nd: YAG (15ns, 532nm) laser was used for ionizating the condensed TNT sample, and the ions produced in the ionization process were detected by a time of flight mass spectrometer (TOFMS). The influence of laser fluence and the delay time to the decomposition was also studied. According to the assignment of both positive and negative ions, possible laser induced dissociation pathways were proposed. The results may tell much about the initiation process and the chemical reaction that may occur in TNT when exposed to laser pulse.

  20. Effect on isoflavone of soybean seedlings by 532nm laser irradiation

    NASA Astrophysics Data System (ADS)

    Tian, J.; Jin, L. H.; Li, J. M.; Shen, B. J.; Wang, C. Y.; Lu, X.; Zhao, X. L.

    2010-02-01

    We took soybeans as experimental substance to study how the 532nm laser with different power density and irradiation time affected the pullulation ratio of the soybeans, average height of seedlings and the isoflavone content of seedlings' cotyledon and laminae. The mechanism that laser pretreatment of soybean seeds could increase the isoflavone content of the seedlings was discussed in such both aspects as the efficiency of the photosynthesis and the activity of a phenylalanine ammonia-lyase (PAL) as an initial enzyme for synthesizing the isoflavone. The results showed that after the soybean seeds were pretreated by laser, the activity of the PAL and the resultants of the photosynthesis such as the sugar of dissolubility, the sucrose, and the amylum all increased with the soybean seeds irradiated by laser in which the effect on the soybean seeds pretreated by 15mW/mm2 laser for 5 min was the most obvious. As a result, the photosynthesis efficiency of the soybean seedlings increased after being pretreated by laser, which might offer the foundation for accumulating a large amount of isoflavone.

  1. Effect on isoflavone of soybean seedlings by 532nm laser irradiation

    NASA Astrophysics Data System (ADS)

    Tian, J.; Jin, L. H.; Li, J. M.; Shen, B. J.; Wang, C. Y.; Lu, X.; Zhao, X. L.

    2009-10-01

    We took soybeans as experimental substance to study how the 532nm laser with different power density and irradiation time affected the pullulation ratio of the soybeans, average height of seedlings and the isoflavone content of seedlings' cotyledon and laminae. The mechanism that laser pretreatment of soybean seeds could increase the isoflavone content of the seedlings was discussed in such both aspects as the efficiency of the photosynthesis and the activity of a phenylalanine ammonia-lyase (PAL) as an initial enzyme for synthesizing the isoflavone. The results showed that after the soybean seeds were pretreated by laser, the activity of the PAL and the resultants of the photosynthesis such as the sugar of dissolubility, the sucrose, and the amylum all increased with the soybean seeds irradiated by laser in which the effect on the soybean seeds pretreated by 15mW/mm2 laser for 5 min was the most obvious. As a result, the photosynthesis efficiency of the soybean seedlings increased after being pretreated by laser, which might offer the foundation for accumulating a large amount of isoflavone.

  2. 532 nm Low-Power Laser Irradiation Facilitates the Migration of GABAergic Neural Stem/Progenitor Cells in Mouse Neocortex

    PubMed Central

    Fukuzaki, Yumi; Shin, Hyeryun; Kawai, Hideki D.; Yamanoha, Banri; Kogure, Shinichi

    2015-01-01

    Background and Objective Accumulating evidence has shown that low-power laser irradiation (LLI) affects cell proliferation and survival, but little is known about LLI effects on neural stem/progenitor cells (NSPCs). Here we investigate whether transcranial 532 nm LLI affects NSPCs in adult murine neocortex and in neurospheres from embryonic mice. Study Design/Materials and Methods We applied 532 nm LLI (Nd:YVO4, CW, 60 mW) on neocortical surface via cranium in adult mice and on cultured cells from embryonic mouse brains in vitro to investigate the proliferation and migration of NSPCs and Akt expression using immunohistochemical assays and Western blotting techniques. Results In vivo experiments demonstrated that 532 nm LLI significantly facilitated the migration of GABAergic NSPCs that were induced to proliferate in layer 1 by mild ischemia. In vitro experiments using GABAergic NSPCs derived from embryonic day 14 ganglionic eminence demonstrated that 532 nm LLI for 60 min promoted the migration of GAD67-immunopositive NSPCs with a significant increase of Akt expression. Meanwhile, the LLI induced proliferation, but not migration, of NSPCs that give rise to excitatory neurons. Conclusion It is concluded that 532 nm LLI promoted the migration of GABAergic NSPCs into deeper layers of the neocortex in vivo by elevating Akt expression. PMID:25919297

  3. LD pumped high-repetition-rate high-power 532nm Nd:YAG/LBO solid state laser

    NASA Astrophysics Data System (ADS)

    Li, Pingxue; Liu, Dongyu; Chi, Junjie; Yang, Chun; Zhao, Ziqiang; Hu, Haowei; Zhang, Guangju; Yao, Yifei

    2013-09-01

    Diode pumped solid state 532 nm green laser is widely required for many industrial, medical and scientific applications. Among most of these applications, high power quasi-continuous-wave (QCW) green laser output is demanded. This can be efficiently achieved through a diode-side-pumped acoustic-optic Q-switched Nd:YAG laser with an intracavity second harmonic generation (SHG). In our experiment, LBO crystal is used for the second harmonic generation of high-average-power lasers of near infrared (NIR) range, though its effective NLO coefficient deff is relatively small. It is because of its high damage threshold (greater than 2.5 GW/cm2), large acceptance angle, small walk-off angle, and the nonhygroscopic characteristic. In this paper, we reported a high-repetition-rate high-power diode-side-pumped AO Q-switched Nd:YAG 532 nm laser. A plane-plane cavity with two rods, two AO Q-switches and the type II critical phase-matched LBO at room temperature were employed. Under the LD pump power of 480 W, 95.86 W at 1064 nm wavelength was achieved when the repetition rate was 15 kHz, and the 532 nm average output power of 44.77 W was obtained, with a pulse width of 111.7 ns, corresponding to an optical to optical conversion efficiency of 46.7% from 1064 nm to 532 nm. The 532 nm average output power was 40.10 W at a repetition rate of 10 kHz with a pulse width of 78.65 ns. The output characteristics of the SHG varying with the pumping current and the pulse repetition frequency (PRF) of the laser were also investigated. Further improvement of the SHG is under study.

  4. Our perspective of the treatment of naevus of Ota with 1,064-, 755- and 532-nm wavelength lasers.

    PubMed

    Felton, S J; Al-Niaimi, F; Ferguson, J E; Madan, V

    2014-09-01

    Naevus of Ota (NO) is a disfiguring pigmentary disorder affecting the face. Q-switched neodymium-doped yttrium aluminium garnet (QS Nd:YAG)-1,064 nm is a standard laser treatment because it causes highly selective destruction of melanin within the aberrant dermal melanocytes. However, not all lesions respond. This study aims to evaluate the efficacy/safety of QS Nd:YAG-1,064 nm and the shorter wavelength QS Alexandrite-755 nm and QS Nd:YAG-532 nm lasers in treating NO. Data were evaluated from 21 patients treated in our laser centre from 2004 to 2012. Lesional skin was irradiated with QS-532 nm/QS-755 nm/QS-1,064 nm, with settings titrated according to responses. All received initial test patches to direct initial wavelength choice, with subsequent treatments at 3-monthly intervals until clearance/lack of further response. Laser modality was switched following repeated test patches if there was no or no sustained improvement. Two thirds of patients had ≥ 90% improvement compared to baseline photographs. In 20% of patients, QS-1,064 nm was most efficacious with 97% mean improvement. The mean improvement was 80% for those in whom QS-755 nm was superior, and 90% for QS-532 nm. Median number of overall laser treatments was 8 (range 4-13). Number of treatments required varied significantly according to lesional colour and site: grey lesions and those on the forehead/temple were most resistant. We confirm successful treatment of NO with QS Nd:YAG-1,064 nm and the shorter wavelength QS-755 nm/QS-532 nm lasers without serious or irreversible side effects. We recommend judicious test patch analysis before treatment and a modality switch if complete clearance is not obtained. PMID:23640036

  5. Comparison of short-pulsed and long-pulsed 532 nm lasers in the removal of freckles.

    PubMed

    Vejjabhinanta, Voraphol; Elsaie, Mohamed L; Patel, Shalu S; Patel, Asha; Caperton, Caroline; Nouri, Keyvan

    2010-11-01

    The purpose of this study was to compare the efficacy and safety of the 532 nm long-pulsed laser (10 ms) with that of the 532 nm short-pulsed laser (10 ns) for freckle removal. Currently, the gold standard for treatment is the short-pulsed laser. Recently, several long-pulsed lasers have been introduced for both hair removal and the treatment of freckles. To our investigative team's knowledge, no controlled experiments have been performed to compare the safety and efficacy of long-pulsed versus short-pulsed lasers for the treatment of freckles. This was a 4-week trial, and all patients had three freckles that were randomly allocated to be treated with short-pulse laser, long-pulse laser, or to receive no treatment (control). All patients had three freckles that were randomly selected to be treated with short-pulse 532 nm Medlite IV laser (10 n, 1 J/cm(2)), or long-pulse 532 nm Aura laser (10 ms, 1 J/cm(2)) or to remain as a control (no treatment). The laser treatment was only performed once, followed by a 1-day and a 1-month follow-up visit. Freckle size was determined by a novel surface area measurement technique that was created by our research staff. The study included 17 sets of freckles (three in each set). All of the lesions which received the short-pulsed laser treatment had immediate whitening of the lesions, which turned into dry scabs the next day. None of the freckles treated in the long-pulsed group or control group developed immediate whitening or scabs. No blisters or ulcers developed. The average pain score in the short-pulsed laser group was 2-3 out of 10, while it was 0 out of 10 in the long-pulsed laser group. All scabs that developed in the short-pulsed laser group fell off between days 6 and 12 (average 8 days). The outcome of this study verified the appropriate treatment of freckles. The study confirmed that when the same energy settings, short-pulsed laser is the more effective laser treatment regimen (when compared with the long-pulsed laser

  6. Anti-Fungal Laser Treatment of Paper: A Model Study with a Laser Wavelength of 532 nm

    NASA Astrophysics Data System (ADS)

    Pilch, E.; Pentzien, S.; Mädebach, H.; Kautek, W.

    Biodeterioration of organic cultural heritage materials is a common problem. Particularly the removal of discoloration caused by fungal pigments is yet an unsolved problem in paper conservation. In the present study, cellulose (cotton and linters) and 16th century paper (rag), were incubated with several fungi types, such as Cladosporium, Epicoccum, Alternaria, Chaetomium, Aspergillus, Trichophyton, and Penicillium on agar for three weeks. Then they were immersed in 70% Ethanol for removal of hyphae and mycelia and deactivation of the remaining conidia. These specimens were laser-treated in a computer-controlled laser cleaning system with a high pulse energy diode pumped Q-switched Nd:YAG laser operating at 532 nm and a pulse duration of 8 ns. Colour differences were determined spectrophotometrically. Best cleaning results were observed with fungi such as Penicillium and Alternaria. Dry laser cleaning generally turned out to be superb over wet bleaching approaches.

  7. Laser cutting of bone tissue under bulk water with a pulsed ps-laser at 532 nm

    NASA Astrophysics Data System (ADS)

    Tulea, Cristian-Alexander; Caron, Jan; Gehlich, Nils; Lenenbach, Achim; Noll, Reinhard; Loosen, Peter

    2015-10-01

    Hard-tissue ablation was already investigated for a broad variety of pulsed laser systems, which cover almost the entire range of available wavelengths and pulse parameters. Most effective in hard-tissue ablation are Er:YAG and CO2 lasers, both utilizing the effect of absorption of infrared wavelengths by water and so-called explosive vaporization, when a thin water film or water-air spray is supplied. The typical flow rates and the water layer thicknesses are too low for surgical applications where bleeding occurs and wound flushing is necessary. We studied a 20 W ps-laser with 532 nm wavelength and a pulse energy of 1 mJ to effectively ablate bones that are submerged 14 mm under water. For these laser parameters, the plasma-mediated ablation mechanism is dominant. Simulations based on the blow-off model predict the cut depth and cross-sectional shape of the incision. The model is modified considering the cross section of the Gaussian beam, the incident angle, and reflections. The ablation rate amounts to 0.2 mm3/s, corresponding to an increase by at least 50% of the highest values published so far for ultrashort laser ablation of hard tissue.

  8. Influence of water content on the ablation of skin with a 532 nm nanosecond Nd:YAG laser.

    PubMed

    Kim, Soogeun; Eom, Tae Joong; Jeong, Sungho

    2015-01-01

    This work reports that the ablation volume and rate of porcine skin changed significantly with the change of skin water content. Under the same laser irradiation conditions (532 nm Nd:YAG laser, pulse width = 11.5 ns, pulse energy = 1.54 J, beam radius = 0.54 mm), the ablation volume dropped by a factor of 4 as the skin water content decreased from 40 wt. % (native) to 19 wt. % with a change in the ablation rate below and above around 25 wt. %. Based on the ablation characteristics observed by in situ shadowgraph images and the calculated tissue temperatures, it is considered that an explosive rupture by rapid volumetric vaporization of water is responsible for the ablation of the high water content of skin, whereas thermal disintegration of directly irradiated surface layer is responsible for the low water content of skin. PMID:25581397

  9. 32.5 mJ and 4.6 ns 532 nm Q-switched Nd:YAG laser at 500 Hz.

    PubMed

    Zhang, Zilong; Liu, Qiang; Gong, Mali

    2013-04-20

    A laser diode side-pumped electro-optical Q-switched Nd:YAG green light laser with high repetition rates, short pulse width, and high peak power was demonstrated. We studied the performance of the oscillator at the repetition rates from 100 to 500 Hz. At 500 Hz, 61 mJ, 5 ns of 1064 nm infrared light pulses were obtained with an oscillator-amplifier system. The peak power of the pulse was 12 MW. By frequency doubling with a LiB(3)O(5)(LBO) crystal, 32.5 mJ, 4.6 ns of 532 nm green light was achieved, corresponding to a peak power of 7 MW. The frequency conversion efficiency was 53.3%. PMID:23669684

  10. Changing the optical and electrical properties of a crown dielectric surface using a 532 nm diode laser

    NASA Astrophysics Data System (ADS)

    Khairuzzaman, Md

    The optical response of a dielectric surface to a given laser radiation can be modified when this surface receives a supplemental uniform energy from an external source such as from the uniform electric field set up by a capacitor voltage. A low capacitor voltage across the dielectric can shift the wavelength of the probe laser as perceived by the dielectric surface toward smaller values. This shift is due to an increase of the vibrational frequency of the electric dipoles located on the dielectric surface. The change in the polarization properties of the dielectric surface suggests the usage of this configuration as an optoelectronic switch driven by a relatively small capacitor voltage. Another goal of this work is to observe the coupling between two lasers through a simultaneous interaction on the surface of a crown dielectric material. We analyze the destructive interference pattern between a weak probe laser and a stronger coupling laser in an electromagnetic induced transparency (EIT)-type configuration. We compare our destructive interference pattern obtained with crown glass illuminated with a diode laser of 532 nm, with previous results where a flint dielectric material was illuminated with the same radiation in similar experimental conditions.

  11. Fractional 532-nm Q-switched Nd:YAG laser: One of the safest novel treatment modality to treat café-au-lait macules.

    PubMed

    Won, Kwang Hee; Lee, Ye Jin; Rhee, Do Young; Chang, Sung Eun

    2016-10-01

    Café-au-lait macules (CALMs) are benign epidermal basilar hyperpigmentations that can be found in an isolated form or in association with neurocutaneous syndromes. Frequency-doubled Q-switched neodymium-doped yttrium aluminum garnet laser (532-nm QSNYL) does not penetrate deeply into the skin and is therefore suitable for epidermal pigmented lesion. Fractional photothermolysis (FP) targets only very small areas of the skin, without injuring adjacent areas of healthy, normal skin. Herein, we report a case of CALMs successfully treated with fractional 532-nm QSNYL. By applying FP to 532-nm QSNYL, we could treat CALMs safely with less downtime as compared to conventional laser treatments and expect more energy delivery for each microscopic hole, thereby allowing higher response rate. PMID:26962881

  12. 40W high beam quality 532nm green laser with LBO intracavity-frequecy-doubling

    NASA Astrophysics Data System (ADS)

    Liu, Xuesheng; Li, Jing; Liu, Youqiang; Wang, Zhiyong

    2014-12-01

    A high-power high-beam-quality 1064nm Nd:YAG rod laser and SHG by intracavity-frequency-doubling are reported. With two common side-pumped Nd:YAG rod modules in the short cavity, we achieved an 78.5W near diffraction-limited pulsed wave 1064nm laser(M2=1.5) with pulse frequency 30kHz, pulse width 94ns and a good power stability of +/-1% for over two hours. Finally, a 40W pulsed green laser with pulse width of 92ns in a near diffraction-limited beam (M2=1.45) is generated using an LBO crystal as the frequency doubler in the cavity.

  13. Randomised clinical trial evaluating best-corrected visual acuity and central macular thickness after 532-nm subthreshold laser grid photocoagulation treatment in diabetic macular oedema

    PubMed Central

    Pei-pei, W; Shi-zhou, H; Zhen, T; Lin, L; Ying, L; Jiexiong, O; Wen-bo, Z; Chen-jin, J

    2015-01-01

    Purpose To compare best-corrected visual acuity (BCVA) and central macular thickness (CMT) after 532-nm subthreshold laser grid photocoagulation and threshold laser grid photocoagulation for the treatment of diabetic macular oedema (DME). Patients and methods Twenty-three patients (46 eyes) with binocular DME were enroled in this study. The two eyes of each patient were divided into a subthreshold photocoagulation group and a threshold photocoagulation group. The eyes of the subthreshold group underwent 532-nm patter scan laser system (PASCAL) 50% end point subthreshold laser grid photocoagulation therapy, whereas the threshold photocoagulation group underwent short-pulse grid photocoagulation with a 532-nm PASCAL system. BCVA and CMT were assessed in all patients before treatment, 7 days after treatment, and 1, 3, and 6 months after treatment. Results After grid photocoagulation, the mean BCVA improved in both the subthreshold group, and the threshold group, and the two groups did not differ statistically significantly from each other. Similarly, the macular oedema diminished in both groups after treatment, and the two groups did not differ statistically significantly from each other with regard to CMT. Conclusion Both 532-nm subthreshold laser grid photocoagulation and threshold laser grid photocoagulation can improve the visual acuity and reduce CMT in DME patients. PMID:25697457

  14. 180W at 1kHz, 532nm SHG from LBO crystals using high average power Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Tamaoki, Yoshinori; Kato, Yoshinori; Iyama, Koichi; Kawashima, Toshiyuki; Miyanaga, Noriaki

    2014-02-01

    We have developed high average power MOPA laser system with SHG unit on the table top size (3 × 1.5m). At the wavelength 1064nm has been obtained the max average output power of 715W. We have achieved the average power 180W at the wavelength 532nm, the pulse width of about 100ns, the frequency of 1kHz. And the power efficiency of the SHG from the wavelength of 1064nm to 532nm was obtained about 25.6%.

  15. Stimulated scattering effects in gold-nanorod-water samples pumped by 532 nm laser pulses

    PubMed Central

    Shi, Jiulin; Wu, Haopeng; Liu, Juan; Li, Shujing; He, Xingdao

    2015-01-01

    Stimulated scattering in gold-nanorod-water samples has been investigated experimentally. The scattering centers are impurity particles rather than the atoms or molecules of conventional homogeneous scattering media. The pump source for exciting stimulated scattering is a pulsed and narrow linewidth second-harmonic Nd: YAG laser, with 532 nm wavelength, ~8 ns pulse duration, and 10 Hz repetition rate. Experimental results indicate that SMBS, SBS and STRS can be generated in gold-nanorod-water samples under appropriate pump and absorption conditions. The incident pump energy has to be larger than a certain threshold value before stimulated scattering can be detected. The absorption coefficient of samples at 532 nm wavelength depends on the one of characteristic absorption bands of gold nanorods located around 530 nm. A critical absorption coefficient can be determined for the transition from SBS to STRS. Also, the spectral-line-broadening effects of STRS have been observed, the line-shape presents a pseudo-Voigt profile due to the random thermal motion of molecules and strong particle collision. PMID:26173804

  16. Cluster-assisted generation of multi-charged ions in nanosecond laser ionization of pulsed hydrogen sulfide beam at 1064 and 532 nm

    NASA Astrophysics Data System (ADS)

    Niu, Dong-Mei; Li, Hai-Yang; Luo, Xiao-Lin; Liang, Feng; Cheng, Shuang; Li, An-Lin

    2006-07-01

    The multi-charged sulfur ions of Sq+ (q<= 6) have been generated when hydrogen sulfide cluster beams are irradiated by a nanosecond laser of 1064 and 532 nm with an intensity of 1010~ 1012W.cm-2. S6+ is the dominant multi-charged species at 1064 nm, while S4+, S3+ and S2+ ions are the main multi-charged species at 532 nm. A three-step model (i.e., multiphoton ionization triggering, inverse bremsstrahlung heating, electron collision ionizing) is proposed to explain the generation of these multi-charged ions at the laser intensity stated above. The high ionization level of the clusters and the increasing charge state of the ion products with increasing laser wavelength are supposed mainly due to the rate-limiting step, i.e., electron heating by absorption energy from the laser field via inverse bremsstrahlung, which is proportional to λ2, λ being the laser wavelength.

  17. Stable, high-power, single-frequency generation at 532 nm from a diode-bar-pumped Nd:YAG ring laser with an intracavity LBO frequency doubler.

    PubMed

    Martin, K I; Clarkson, W A; Hanna, D C

    1997-06-20

    We obtained 2.5 W of single-frequency TEM(00) output at 532 nm using a Brewster-angled LBO crystal for intracavity second-harmonic generation in a diode-bar-pumped Nd:YAG laser. By inserting a thin uncoated étalon, the 1061.4-nm laser transition can be selected, generating 1.6 W of output at 530.7 nm. PMID:18253441

  18. Comparative study on the intracavity frequency-doubling 532 nm laser based on gray-tracking-resistant KTP and conventional KTP.

    PubMed

    Huang, H-T; Qiu, G; Zhang, B-T; He, J-L; Yang, J-F; Xu, J-L

    2009-11-10

    A comparative study of a frequency-doubling 532 nm laser based on gray-tracking-resistant KTP (GTR-KTP) and conventional KTP is presented. The intracavity GTR-KTP was proved to have better temperature characteristics than that of conventional KTP. Within the normalized output power variation range of 0.8-1.0, GTR-KTP has a temperature tolerance of 35 degrees C, broader than the 21 degrees C obtained with conventional KTP. Under the laser diode (LD) pump power of 180 W, the maximum average output power at 532 nm was 40.6 W for GTR-KTP at a repetition frequency of 10 kHz. In the case of conventional KTP, the maximum available LD pump power was limited to 150 W, with the corresponding maximum green average output power of 27.2 W. PMID:19904338

  19. Generation of high-peak power 532-nm green pulses from composite, all-ceramics, passively Q-switched Nd:YAG/Cr4+:YAG laser

    NASA Astrophysics Data System (ADS)

    Salamu, Gabriela; Ionescu, Alina; Brandus, Catalina; Grigore, Oana; Pavel, Nicolaie; Dascalu, Traian

    2013-06-01

    Laser pulses at 1.06 μm with 2.5-mJ energy and 3.1-MW peak power have been obtained from a composite, all polycrystalline ceramics, passively Q-switched 1.1-at.% Nd:YAG/Cr4+:YAG laser that was quasi-continuous-wave pumped with diode lasers. Single-pass frequency doubling with LiB3O5 nonlinear crystal at room temperature yielded green laser pulses at 532 nm with energy of 0.36-mJ and 0.45-MW peak power; the infrared-to-green conversion efficiency was 0.27.

  20. Observation and Measurement of Temperature Rise and Distribution on GaAs Photo-cathode Wafer with a 532nm Drive Laser and a Thermal Imaging Camera

    SciTech Connect

    Shukui Zhang, Stephen Benson, Carlos Hernandez-Garcia

    2011-03-01

    Significant temperature rise and gradient are observed from a GaAs photo-cathode wafer irradiated at various power levels with over 20W laser power at 532nm wavelength. The laser power absorption and dissipated thermal distribution are measured. The result shows a clear indication that proper removal of laser induced heat from the cathode needs to be considered seriously when designing a high average current or low quantum efficiency photo-cathode electron gun. The measurement method presented here provides a useful way to obtain information about both temperature and thermal profiles, it also applies to cathode heating study with other heating devices such as electrical heaters.

  1. Picosecond laser texturization of mc-silicon for photovoltaics: A comparison between 1064 nm, 532 nm and 355 nm radiation wavelengths

    NASA Astrophysics Data System (ADS)

    Binetti, Simona; Le Donne, Alessia; Rolfi, Andrea; Jäggi, Beat; Neuenschwander, Beat; Busto, Chiara; Frigeri, Cesare; Scorticati, Davide; Longoni, Luca; Pellegrino, Sergio

    2016-05-01

    Self-organized surface structures were produced by picosecond laser pulses on multi-crystalline silicon for photovoltaic applications. Three different laser wavelengths were employed (i.e. 1064 nm, 532 nm and 355 nm) and the resulting morphologies were observed to effectively reduce the reflectivity of the samples after laser irradiation. Besides, a comparative study of the laser induced subsurface damage generated by the three different wavelengths was performed by confocal micro-Raman, photoluminescence and transmission electron microscopy. The results of both the structural and optical characterization showed that the mc-Si texturing performed with the laser at 355 nm provides surface reflectivity between 11% and 8% over the spectral range from 400 nm to 1 μm, while inducing the lowest subsurface damage, located above the depletion region of the p-n junction.

  2. Spectroscopic study of carbon plasma produced by the first (1064 nm) and second (532 nm) harmonics of Nd:YAG laser

    SciTech Connect

    Hanif, M.; Salik, M.; Arif, F.

    2015-03-15

    In this research work, spectroscopic studies of carbon (C) plasma by using laser-induced breakdown spectroscopy (LIBS) are presented. The plasma was produced by the first (1064 nm) and second (532 nm) harmonics of a Q-switched Nd:YAG (Quantel Brilliant) pulsed laser having a pulse duration of 5 ns and 10-Hz repetition rate, which is capable of delivering 400 mJ at 1064 nm and 200 mJ at 532 nm. The laser beam was focused on the target material (100% carbon) by placing it in air at atmospheric pressure. The experimentally observed line profiles of five neutral carbon (C I) lines at 247.85, 394.22, 396.14, 588.95, and 591.25 nm were used to extract the electron temperature T{sub e} by using the Boltzmann plot method and determine its value, 9880 and 9400 K, respectively, for the fundamental and second harmonics of the laser, whereas the electron density N{sub e} was determined from the Stark broadening profile of neutral carbon line at 247.85 nm. The values of N{sub e} at a distance of 0.05 mm from the target surface for the fundamental-harmonic laser with a pulse energy of 130 mJ and the second-harmonic laser with a pulse energy of 72 mJ are 4.68 × 10{sup 17} and 5.98 × 10{sup 17} cm{sup −3}, respectively. This extracted information on T{sub e} and N{sub e} is useful for the deposition of carbon thin films by using the pulsed laser deposition technique. Moreover, both plasma parameters (T{sub e} and N{sub e}) were also calculated by varying the distance from the target surface along the line of propagation of the plasma plume and also by varying the laser irradiance.

  3. Optic detectors calibration for measuring ultra-high energy extensive air showers Cherenkov radiation by 532 nm laser

    NASA Astrophysics Data System (ADS)

    Knurenko, Stanislav; Petrov, Igor; Egorov, Yuri

    2015-08-01

    Calibration of a PMT matrix is crucial for the treatment of the data obtained with Cherenkov tracking detector. Furthermore, due to high variability of the aerosol abundance in the atmosphere depending on season, weather etc. A constant monitoring of the atmospheric transparency is required during the measurements. For this purpose, besides traditional methods, a station for laser atmospheric probing is used.

  4. Quadrupole mass spectrometry and time-of-flight analysis of ions resulting from 532 nm pulsed laser ablation of Ni, Al, and ZnO targets

    SciTech Connect

    Sage, Rebecca S.; Cappel, Ute B.; Ashfold, Michael N. R.; Walker, Nicholas R.

    2008-05-01

    This work describes the design and validation of an instrument to measure the kinetic energies of ions ejected by the pulsed laser ablation (PLA) of a solid target. Mass spectra show that the PLA of Ni, Al, and ZnO targets, in vacuum, using the second harmonic of a Nd:YAG laser (532 nm, pulse duration {approx}10 ns) generates abundant X{sup n+} ions (n{<=}3 for Ni, {<=}2 for Al, {<=}3 and {<=}2 for Zn and O respectively from ZnO). Ions are selected by their mass/charge (m/z) ratio prior to the determination of their times of flight. PLA of Ni has been studied in most detail. The mean velocities of ablated Ni{sup n+} ions are shown to follow the trend v(Ni{sup 3+})>v(Ni{sup 2+})>v(Ni{sup +}). Data from Ni{sup 2+} and Ni{sup 3+} are fitted to shifted Maxwellian functions and agree well with a model which assumes both thermal and Coulombic contributions to ion velocities. The dependence of ion velocities on laser pulse energy (and fluence) is investigated, and the high energy data are shown to be consistent with an effective accelerating voltage of {approx}90 V within the plume. The distribution of velocities associated with Ni{sup 3+} indicates a population at cooler temperature than Ni{sup 2+}.

  5. Investigation of N2O Production from 266 and 532 nm Laser Flash Photolysis of O3/N2/O2 Mixtures

    NASA Technical Reports Server (NTRS)

    Estupinan, E. G.; Nicovich, J. M.; Li, J.; Cunnold, D. M.; Wine, P. H.

    2002-01-01

    Tunable diode laser absorption spectroscopy has been employed to measure the amount of N2O produced from laser flash photolysis of O3/N2/O2 mixtures at 266 and 532 nm. In the 532 nm photolysis experiments very little N2O is observed, thus allowing an upper limit yield of 7 x 10(exp -8) to be established for the process O3 + N2 yield N2O + O2, where O3 is nascent O3 that is newly formed via O(3P(sub J)) + O2 recombination (with vibrational excitation near the dissociation energy of O3). The measured upper limit yield is a factor of approx. 600 smaller than a previous literature value and is approximately a factor of 10 below the threshold for atmospheric importance. In the 266 nm photolysis experiments, significant N2O production is observed and the N2O quantum yield is found to increase linearly with pressure over the range 100 - 900 Torr in air bath gas. The source of N2O in the 266 nm photolysis experiments is believed to be the addition reaction O(1D(sub 2)) + N2 + M yields (k(sub sigma)) N2O + M, although reaction of (very short-lived) electronically excited O3 with N2 cannot be ruled out by the available data. Assuming that all observed N2O comes from the O(1D(sub 2)) + N2 + M reaction, the following expression describes the temperature dependence of k(sub sigma) (in its third-order low-pressure limit) that is consistent with the N2O yield data: k(sub sigma) = (2.8 +/- 0.1) x 10(exp -36)(T/300)(sup -(0-88+0.36)) cm(sup 6) molecule(sup -2)/s, where the uncertainties are 2(sigma) and represent precision only. The accuracy of the reported rate coefficients at the 95% confidence level is estimated to be 30 - 40% depending on the temperature. Model calculations suggest that gas phase processes initiated by ozone absorption of a UV photon represent about 1.4% of the currently estimated global source strength of atmospheric N2O. However, these processes could account for a significant fraction of the oxygen mass-independent enrichment observed in atmospheric N2O, and

  6. Magnetorheological finishing (MRF) of potassium dihydrogen phosphate (KDP) crystals: nonaqueous fluids development, optical finish, and laser damage performance at 1064 nm and 532 nm

    NASA Astrophysics Data System (ADS)

    Menapace, J. A.; Ehrmann, P. R.; Bickel, R. C.

    2009-10-01

    Over the past year we have been working on specialized MR fluids for polishing KDP crystals. KDP is an extremely difficult material to conventionally polish due to its water solubility, low hardness, and temperature sensitivity. Today, KDP crystals are finished using single-point diamond turning (SPDT) tools and nonaqueous lubricants/coolants. KDP optics fabricated using SPDT, however, are limited to surface corrections due to tool/method characteristics with surface quality driven by microroughness from machine pitch, speed, force, and diamond tool character. MRF polishing offers a means to circumvent many of these issues since it is deterministic which makes the technique practical for surface and transmitted wavefront correction, is low force, and is temperature independent. What is lacking is a usable nonaqueous MR fluid that is chemically and physically compatible with KDP which can be used for polishing and subsequently cleaned from the optical surface. In this study, we will present the fluid parameters important in the design and development of nonaqueous MR fluid formulations capable of polishing KDP and how these parameters affect MRF polishing. We will also discuss requirements peculiar to successful KDP polishing and how they affect optical figure/finish and laser damage performance at 1064 nm and 532 nm.

  7. Magnetorheological finishing (MRF) of potassium dihydrogen phosphate (KDP) crystals: nonaqueous fluids development, optical finish, and laser damage performance at 1064 nm and 532 nm

    SciTech Connect

    Menapace, J A; Ehrmann, P R; Bickel, R C

    2009-11-05

    Over the past year we have been working on specialized MR fluids for polishing KDP crystals. KDP is an extremely difficult material to conventionally polish due to its water solubility, low hardness, and temperature sensitivity. Today, KDP crystals are finished using single-point diamond turning (SPDT) tools and nonaqueous lubricants/coolants. KDP optics fabricated using SPDT, however, are limited to surface corrections due to tool/method characteristics with surface quality driven by microroughness from machine pitch, speed, force, and diamond tool character. MRF polishing offers a means to circumvent many of these issues since it is deterministic which makes the technique practical for surface and transmitted wavefront correction, is low force, and is temperature independent. What is lacking is a usable nonaqueous MR fluid that is chemically and physically compatible with KDP which can be used for polishing and subsequently cleaned from the optical surface. In this study, we will present the fluid parameters important in the design and development of nonaqueous MR fluid formulations capable of polishing KDP and how these parameters affect MRF polishing. We will also discuss requirements peculiar to successful KDP polishing and how they affect optical figure/finish and laser damage performance at 1064 nm and 532 nm.

  8. Hadamard transform microchip electrophoresis combined with laser-induced fluorescence detection using a compact neodymium-doped yttrium aluminum garnet laser emitting at 532 nm

    NASA Astrophysics Data System (ADS)

    Hata, Kazuki; Kaneta, Takashi; Imasaka, Totaro

    2009-05-01

    Hadamard transform electrophoresis combined with laser-induced fluorescence (LIF) detection on a microchip was demonstrated. A compact, diode-pumped neodymium-doped yttrium aluminum garnet laser was employed as the light source for LIF detection. The analytical conditions were optimized using rhodamine B as the analyte. Under optimal conditions, the signal-to-noise ratio (S/N) of the analyte was improved by a factor of 7.5 by means of Hadamard transformation based on a 255-order cyclic S matrix. Additionally, the relationship between fluorescence intensity and analyte concentration was linear with a correlation coefficient of 0.993 in the inverse Hadamard transformed data at the concentration range from 25 to 100 pM. The results indicate that the present method is applicable to quantitative analysis at the concentration lower than the concentration limit of detection in a conventional method. The concentration limit of detection was ˜25 pM (the relative standard deviation of the peak height was 5.2%). The present technique was successfully applied to the separation of a mixture containing 1.9 nM phenylalanine and 1.9 nM glutamic acid labeled with rhodamine B isothiocyanate. The S/Ns of the analyte peaks were improved up to ˜10 in the inverse Hadamard transformed data derived from a 127-order cyclic S matrix, while neither peak was lower than the limit of detection (S/N<3) in conventional microchip electrophoresis by a single injection.

  9. Suppression of optical damage at 532 nm in Holmium doped congruent lithium niobate.

    PubMed

    Barnes, Eftihia; O'Connell, Nathan H; Balli, Nicolas R; Pokhrel, Madhab; Movsesyan, Anush; Kokanyan, Edvard; Sardar, Dhiraj K

    2014-10-20

    Optical damage experiments were carried out in a series of Holmium doped congruent lithium niobate (Ho:cLN) crystals as a function of dopant concentration and laser intensity. The light induced beam distortion was recorded with a camera and a detector under the pseudo-Z-scan configuration. At 532 nm, strong suppression of the optical damage was observed for the 0.94 mol. % doped crystal. Increased resistance to optical damage was also observed at 488 nm. The suppression of the optical damage is predominantly attributed to the reduction of the Nb antisites due to the holmium doping. PMID:25401654

  10. Assessment of the CALIPSO Lidar 532 nm Attenuated Backscatter Calibration Using the NASA LaRC Airborne High Spectral Resolution Lidar

    NASA Technical Reports Server (NTRS)

    Rogers, Raymond R.; Hostetler, Chris A.; Hair, Johnathan W.; Ferrare, Richard A.; Liu, Zhaoyan; Obland, Michael D.; Harper, David B.; Cook, Anthony L.; Powell, Kathleen A.; Vaughan, Mark A.; Winker, David M.

    2011-01-01

    The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) spacecraft has provided global, high-resolution vertical profiles of aerosols and clouds since it became operational on 13 June 2006. On 14 June 2006, the NASA Langley Research Center (LaRC) High Spectral Resolution Lidar (HSRL) was deployed aboard the NASA Langley B-200 aircraft for the first of a series of 86 underflights of the CALIPSO satellite to provide validation measurements for the CALIOP data products. To better assess the range of conditions under which CALIOP data products are produced, these validation flights were conducted under both daytime and nighttime lighting conditions, in multiple seasons, and over a large range of latitudes and aerosol and cloud conditions. This paper presents a quantitative assessment of the CALIOP 532 nm calibration (through the 532 nm total attenuated backscatter) using an internally calibrated airborne HSRL underflight data and is the most extensive study of CALIOP 532 nm calibration. Results show that average HSRL and CALIOP 532 nm total attenuated backscatter agree on average within 2.7% +/- 2.1% (CALIOP lower) at night and within 2.9 % +/- 3.9% (CALIOP lower) during the day., demonstrating the accuracy of the CALIOP 532 nm calibration algorithms. Additionally, comparisons with HSRL show consistency of the CALIOP calibration before and after the laser switch in 2009 as well as improvements in the daytime version 3 calibration scheme compared with the version 2 calibration scheme. Potential systematic uncertainties in the methodology relevant to validating satellite lidar measurements with an airborne lidar system are discussed and found to be less than 3.7% for this validation effort with HSRL. Results from this study are also compared to those from prior assessments of CALIOP calibration and attenuated backscatter.

  11. High Conversion Efficiency and Power Stability of 532 nm Generation from an External Frequency Doubling Cavity

    NASA Astrophysics Data System (ADS)

    Zhao, Yang; Lin, Bai-Ke; Li, Ye; Zhang, Hong-Xi; Cao, Jian-Ping; Fang, Zhan-Jun; Li, Tian-Chu; Zang, Er-Jun

    2012-09-01

    We present a high-efficiency 532 nm green light conversion from an external cavity-enhanced second harmonic generation (SHG) with a periodically poled KTP crystal (PPKTP). The cavity is a bow-tie ring configuration with a unitized structure. When the impedance matching is optimized, the coupling efficiency of the fundamental is as high as 95%. Taking into account both the high power output of the second harmonic and the stability of the system, we obtain over 500 mW green passing through the output cavity mirror, corresponding to a net conversion efficiency higher than 75.2%. Under these operating conditions, the power stability is better than ±0.25% during 5 h. It is the highest conversion efficiency and power stability ever produced in the bow-tie ring cavity with PPKTP for 532 nm generation.

  12. Nonlinear optical properties of Bi2O3-GeO2 glass at 800 and 532 nm

    NASA Astrophysics Data System (ADS)

    Oliveira, Tâmara R.; Falcão-Filho, Edilson L.; de Araújo, Cid B.; da Silva, Diego S.; Kassab, Luciana R. P.; da Silva, Davinson M.

    2013-08-01

    The nonlinear (NL) optical properties of glassy xBi2O3-(1-x) GeO2 with x = 0.72 and 0.82 were investigated. The experiments were performed with lasers at 800 nm (pulses of 150 fs) and 532 nm (pulses of 80 ps and 250 ns). Using the Kerr gate technique, we observed that the NL response of the samples at 800 nm is faster than 150 fs. NL refraction indices, |n2|≈ 5 × 10-16 cm2/W, and two-photon absorption coefficients, α2, smaller than 0.03 cm/GW, were measured at 800 nm. At 532 nm, we measured the NL transmittance of the samples. From the results obtained, we determined α2 ≈1 cm/GW and excited-state absorption cross-sections of ≈10-22 cm2 due to free-carriers.

  13. Steady-state Raman gain coefficients of potassium-gadolinium tungstate at the wavelength of 532 nm

    NASA Astrophysics Data System (ADS)

    Chulkov, R.; Markevich, V.; Orlovich, V.; El-Desouki, M.

    2015-12-01

    Stokes generation has been considered under the Fourier-limited nanosecond pulse excitation to find Raman gain coefficients in potassium-gadolinium tungstate. Data of numerical simulation under spontaneous Stokes initiation, light diffraction, and optical feedback have been compared with experimental results to reveal coefficient values of 14 ± 3 and 11 ± 3 cm/GW for the p[mm]p and p[gg]p sample orientations, respectively, at 532 nm wavelength.

  14. Characterization of post mortem arterial tissue using time-resolved photoacoustic spectroscopy at 436, 461 and 532 nm.

    PubMed

    Beard, P C; Mills, T N

    1997-01-01

    Time-resolved photoacoustic spectroscopy has been used to characterize post mortem arterial tissue for the purpose of discriminating between normal and atheromatous areas of tissue. Ultrasonic thermoelastic waves were generated in post mortem human aorta by the absorption of nanosecond laser pulses at 436, 461 and 532 nm produced by a frequency doubled Q-switched Nd:YAG laser in conjunction with a gas filled Raman cell. A PVDF membrane hydrophone was used to detect the thermoelastic waves. At 436 nm, differences in the photoacoustic signatures of normal tissue and atherorma were found to be highly variable. At 461 nm, there was a clear and reproducible difference between the photacoustic response of atheroma and normal tissue as a result of increased optical attenuation in atheroma. At 532 nm, the generation of subsurface thermoelastic waves provided a means of determining the structure and thickness of the tissue sample. It is suggested that pulsed photoacoustic spectroscopy at 461 and 532 nm may find application in characterizing arterial tissue in situ by providing information about both the composition and thickness of the vessel wall. PMID:9015817

  15. Improvements in filtered Rayleigh scattering measurements using Fabry-Perot etalons for spectral filtering of pulsed, 532-nm Nd:YAG output

    NASA Astrophysics Data System (ADS)

    Sutton, Jeffrey A.; Patton, Randy A.

    2014-09-01

    In this manuscript, we investigate a new methodology for increasing the spectral purity of the second-harmonic output of an injection-seeded, frequency-doubled, Q-switched Nd:YAG laser operating near 532 nm. Specifically, tunable Fabry-Perot etalons (FPEs) are used as ultra-narrowband spectral filters, transmitting the desired single-mode output, while filtering out a significant portion of the broadband pedestal characteristic of injection-seeded lasers. A specific emphasis is placed on the design and optimization of the FPEs in the context of filtered Rayleigh scattering (FRS) measurements and how their utilization results in substantial increases in spectral purity, realizable attenuation of unwanted scattering, and applications in environments with high particulate levels. Experimental results show an increase in laser spectral purity of more than one order-of-magnitude (from 0.99997 to 0.999998) when using FPE filters, which led to a two-order-of-magnitude increase in achievable attenuation of laser light passing through a molecular iodine filter. The utility of the FPE-based spectral filtering of the pulsed Nd:YAG output for 2D FRS imaging was demonstrated in turbulent, isothermal gas-phase jets, seeded with varying levels of non-evaporating droplets with particle volume fractions ( F Vp) ranging from ~5 to >60 parts-per-million (ppm). After implementation of an optimized air-spaced FPE in the 532-nm output, no particle scattering was observed (based on visual and statistical analysis), even for the highest seed case ( F Vp ~ 60 ppm), and the gas-phase Rayleigh-Brillouin signals were collected without interference from the flowfield particulate. The current results suggest that the implementation of properly specified FPEs allows FRS to be applied in environments with high flowfield particulate levels; levels are well beyond what have been suitable for previous FRS measurements.

  16. Seagrass Identification Using High-Resolution 532nm Bathymetric LiDAR and Hyperspectral Imagery

    NASA Astrophysics Data System (ADS)

    Pan, Z.; Prasad, S.; Starek, M. J.; Fernandez Diaz, J. C.; Glennie, C. L.; Carter, W. E.; Shrestha, R. L.; Singhania, A.; Gibeaut, J. C.

    2013-12-01

    Seagrass provides vital habitat for marine fisheries and is a key indicator species of coastal ecosystem vitality. Monitoring seagrass is therefore an important environmental initiative, but measuring details of seagrass distribution over large areas via remote sensing has proved challenging. Developments in airborne bathymetric light detection and ranging (LiDAR) provide great potential in this regard. Traditional bathymetric LiDAR systems have been limited in their ability to map within the shallow water zone (< 1 m) where seagrass is typically present due to limitations in receiver response and laser pulse length. Emergent short-pulse width bathymetric LiDAR sensors and waveform processing algorithms enable depth measurements in shallow water environments previously inaccessible. This 3D information of the benthic layer can be applied to detect seagrass and characterize its distribution. Researchers with the National Center for Airborne Laser Mapping (NCALM) at the University of Houston (UH) and the Coastal and Marine Geospatial Sciences Lab (CMGL) of the Harte Research Institute at Texas A&M University-Corpus Christi conducted a coordinated airborne and boat-based survey of the Redfish Bay State Scientific Area as part of a collaborative study to investigate the capabilities of bathymetric LiDAR and hyperspectral imaging for seagrass mapping. Redfish Bay, located along the middle Texas coast of the Gulf of Mexico, is a state scientific area designated for the purpose of protecting and studying native seagrasses. Redfish Bay is part of the broader Coastal Bend Bays estuary system recognized by the US Environmental Protection Agency (EPA) as a national estuary of significance. For this survey, UH acquired high-resolution discrete-return and full-waveform bathymetric data using their Optech Aquarius 532 nm green LiDAR. In a separate flight, UH collected 2 sets of hyperspectral imaging data (1.2-m pixel resolution and 72 bands, and 0.6m pixel resolution and 36

  17. Nonlinear bleaching, absorption, and scattering of 532-nm-irradiated plasmonic nanoparticles

    SciTech Connect

    Liberman, V.; Sworin, M.; Kingsborough, R. P.; Geurtsen, G. P.; Rothschild, M.

    2013-02-07

    Single-pulse irradiation of Au and Ag suspensions of nanospheres and nanodisks with 532-nm 4-ns pulses has identified complex optical nonlinearities while minimizing material damage. For all materials tested, we observe competition between saturable absorption (SA) and reverse SA (RSA), with RSA behavior dominating for intensities above {approx}50 MW/cm{sup 2}. Due to reduced laser damage in single-pulse experiments, the observed intrinsic nonlinear absorption coefficients are the highest reported to date for Au nanoparticles. We find size dependence to the nonlinear absorption enhancement for Au nanoparticles, peaking in magnitude for 80-nm nanospheres and falling off at larger sizes. The nonlinear absorption coefficients for Au and Ag spheres are comparable in magnitude. On the other hand, the nonlinear absorption for Ag disks, when corrected for volume fraction, is several times higher. These trends in nonlinear absorption are correlated to local electric field enhancement through quasi-static mean-field theory. Through variable size aperture measurements, we also separate nonlinear scattering from nonlinear absorption. For all materials tested, we find that nonlinear scattering is highly directional and that its magnitude is comparable to that of nonlinear absorption. These results indicate methods to improve the efficacy of plasmonic nanoparticles as optical limiters in pulsed laser systems.

  18. Nonlinear bleaching, absorption, and scattering of 532-nm-irradiated plasmonic nanoparticles

    NASA Astrophysics Data System (ADS)

    Liberman, V.; Sworin, M.; Kingsborough, R. P.; Geurtsen, G. P.; Rothschild, M.

    2013-02-01

    Single-pulse irradiation of Au and Ag suspensions of nanospheres and nanodisks with 532-nm 4-ns pulses has identified complex optical nonlinearities while minimizing material damage. For all materials tested, we observe competition between saturable absorption (SA) and reverse SA (RSA), with RSA behavior dominating for intensities above ˜50 MW/cm2. Due to reduced laser damage in single-pulse experiments, the observed intrinsic nonlinear absorption coefficients are the highest reported to date for Au nanoparticles. We find size dependence to the nonlinear absorption enhancement for Au nanoparticles, peaking in magnitude for 80-nm nanospheres and falling off at larger sizes. The nonlinear absorption coefficients for Au and Ag spheres are comparable in magnitude. On the other hand, the nonlinear absorption for Ag disks, when corrected for volume fraction, is several times higher. These trends in nonlinear absorption are correlated to local electric field enhancement through quasi-static mean-field theory. Through variable size aperture measurements, we also separate nonlinear scattering from nonlinear absorption. For all materials tested, we find that nonlinear scattering is highly directional and that its magnitude is comparable to that of nonlinear absorption. These results indicate methods to improve the efficacy of plasmonic nanoparticles as optical limiters in pulsed laser systems.

  19. Revised Calibration Strategy for the CALIOP 532 nm Channel. Part II; Daytime

    NASA Technical Reports Server (NTRS)

    Powell, Kathleen A.; Vaughan, Mark A.; Kuehn, Ralph; Hunt, William H.; Pee, Kam-Pui

    2008-01-01

    The CALIPSO lidar (CALIOP) makes backscatter measurements at 532 nm and 1064 nm and linear depolarization ratios at 532 nm. Accurate calibration of the backscatter measurements is essential in the retrieval of optical properties. An assessment of the nighttime 532 nm parallel channel calibration showed that the calibration strategy used for the initial release (Release 1) of the CALIOP lidar level 1B data was acceptable. In general, the nighttime calibration coefficients are relatively constant over the darkest segment of the orbit, but then change rapidly over a short period as the satellite enters sunlight. The daytime 532 nm parallel channel calibration scheme implemented in Release 1 derived the daytime calibration coefficients from the previous nighttime coefficients. A subsequent review of the daytime 532 nm parallel channel calibration revealed that the daytime calibration coefficients do not remain constant, but vary considerably over the course of the orbit, due to thermally-induced misalignment of the transmitter and receiver. A correction to the daytime calibration scheme is applied in Release 2 of the data. Results of both nighttime and daytime calibration performance are presented in this paper.

  20. CARS imaging with a new 532-nm synchronously pumped picosecond OPO

    NASA Astrophysics Data System (ADS)

    Büttner, Edlef; Carrasco, Silvia; Evans, Conor L.; Ganikhanov, Feruz S.; Herbst, Johannes G.; Kopf, Daniel; Rimke, Ingo; Xie, Sunney

    2007-02-01

    A new, synchronously pumped picosecond OPO for CARS microscopy is presented. It is based on non-critically phasematched interaction in LBO pumped by a frequency-doubled modelocked Nd:Vanadat laser at 532 nm. Within the parametric process a tuneable pair of two different wavelengths in the NIR range is generated (Signal <680 ...990 nm, Idler 1150...>2450 nm). In this system they are extracted from the cavity at the same mirror and therefore propagating collinear at the same beam path. Due to the mechanism of their generation there is no jitter between Signal and Idler. Though the wavelengths are different the GVD is negligible for this picosecond pulse duration. As a result the two pulse trains are spatially and temporally perfectly matched. The pulses generated are close to transform limit with about 5-6 ps pulse duration, excellent beam quality (M2 < 1,1) and high pointing stability. The output power for Signal and Idler is about 1 W each @ 4 W pump power. The tuning mechanism is split into two parts - temperature tuning for rough variations and fast angular BRF tuning for the fine adjustment of the output wavelength. The perfect spatial and temporal overlap make the described OPO an ideal and nearly hands-free laser source for CARS microscopy with a tuneable energy difference 1,400 ... >10,000 cm -1. The absolute wavelength range is resulting in high penetration depth and low photo damage of the analyzed samples. Finally some CARS-images are presented and the latest results and methods for further sensitivity enhancements are shown.

  1. Large-scale characterization of silicon nitride-based evanescent couplers at 532nm wavelength

    NASA Astrophysics Data System (ADS)

    Claes, Tom; Jansen, Roelof; Neutens, Pieter; Du Bois, Bert; Helin, Philippe; Severi, Simone; Van Dorpe, Pol; Deshpande, Paru; Rottenberg, Xavier

    2014-05-01

    Recently, the photonics community has a renewed attention for silicon nitride.1-3 When deposited at temperatures below 650K with plasma-enhanced chemical vapor deposition (PECVD),4 it enables photonic circuits fabricated on-top of standard complementary metaloxidesemiconductor (CMOS) electronics. Silicon nitride is moreover transparent to wavelengths that are visible to the human eye and detectable with available silicon detectors, thus offering a photonics platform for a range of applications that is not accessible with the popular silicon-on-insulator platform. However, first-time-right design of large-scale circuits for demanding specifications requires reliable models of the basic photonic building blocks, like evanescent couplers (Figure 1), components that couple power between multiple waveguides. While these models typically exist for the silicon-on-insulator platform, they still lack maturity for the emerging silicon nitride platform. Therefore, we meticulously studied silicon nitride-based evanescent couplers fabricated in our 200mm-wafer facility. We produced the structures in a silicon nitride film deposited with low-temperature PECVD, and patterned it using optical lithography at a wavelength of 193nm and reactive ion etching. We measured the performance of as much as 250 different designs at 532nm wavelength, a central wavelength in the visible range for which laser sources are widespread. For each design, we measured the progressive transmission of up-to 10 cascaded identical couplers (Figure 2(a)), yielding very accurate figures for the coupling factor (Figure 2(b)). This paper presents the trends extracted from this vast data set (Figure 3), and elaborates on the impact of the couplers bend radius and gap on its coupling factors (Figure 4 and Figure 5). We think that the large- scale characterization of evanescent couplers presented in this paper, in excellent agreement with the simulated performance of the devices, forms the basis for a component

  2. Accuracy of Linear Depolarisation Ratios in Clean Air Ranges Measured with POLIS-6 at 355 and 532 NM

    NASA Astrophysics Data System (ADS)

    Freudenthaler, Volker; Seefeldner, Meinhard; Groß, Silke; Wandinger, Ulla

    2016-06-01

    Linear depolarization ratios in clean air ranges were measured with POLIS-6 at 355 and 532 nm. The mean deviation from the theoretical values, including the rotational Raman lines within the filter bandwidths, amounts to 0.0005 at 355 nm and to 0.0012 at 532 nm. The mean uncertainty of the measured linear depolarization ratio of clean air is about 0.0005 at 355 nm and about 0.0006 at 532 nm.

  3. Enhanced light scattering in Si nanostructures produced by pulsed laser irradiation

    SciTech Connect

    Sberna, P. M.; Scapellato, G. G.; Boninelli, S.; Miritello, M.; Crupi, I.; Bruno, E.; Privitera, V.; Simone, F.; Mirabella, S.; Piluso, N.

    2013-11-25

    An innovative method for Si nanostructures (NS) fabrication is proposed, through nanosecond laser irradiation (λ = 532 nm) of thin Si film (120 nm) on quartz. Varying the laser energy fluences (425–1130 mJ/cm{sup 2}) distinct morphologies of Si NS appear, going from interconnected structures to isolated clusters. Film breaking occurs through a laser-induced dewetting process. Raman scattering is enhanced in all the obtained Si NS, with the largest enhancement in interconnected Si structures, pointing out an increased trapping of light due to multiple scattering. The reported method is fast, scalable and cheap, and can be applied for light management in photovoltaics.

  4. Thermal and damage data from multiple microsecond pulse trains at 532nm in an in vitro retinal model

    NASA Astrophysics Data System (ADS)

    Denton, Michael L.; Tijerina, Amanda J.; Hoffman, Aaron; Clark, Clifton D.; Noojin, Gary D.; Rickman, John M.; Castellanos, Cherry C.; Shingledecker, Aurora D.; Boukhris, Sarah J.; Thomas, Robert J.; Rockwell, Benjamin A.

    2014-03-01

    An artificially pigmented retinal pigment epithelial (RPE) cell model was used to study the damage rates for exposure to 1, 10, 100, and 1,000 230-μs laser pulses at 532 nm, at two different concentrations of melanosome particles (MPs) per cell. Multiple pulses were delivered at pulse repetition rates of 50 and 99 pulses per second. Standard fluorescence viability indicator dyes and the method of microthermography were used to assess damage and thermal responses, respectively. Although frame rate during microthermography was more than five times slower than the duration of laser pulses, thermal information was useful in refining the BTEC computational model for simulating high-resolution thermal responses by the pigmented cells. When we temporally sampled the thermal model output at a rate similar to our microthermography, the resulting thermal profiles for multiple pulses resembled the thermal experimental profiles. Complementary to the thermal simulations, our computer-generated thresholds were in good agreement with the in vitro data. Findings are examined within the context of common exposure limit definitions in the national and international laser safety standards.

  5. Preparation and characterization of Irgacure 784 doped photopolymers for holographic data storage at 532 nm

    NASA Astrophysics Data System (ADS)

    Lin, S. H.; Hsiao, Y.-N.; Hsu, K. Y.

    2009-02-01

    This paper presents the development of a thick photopolymer for holographic data storage at a wavelength of 532 nm. Irgacure 784, one kind of the titanocene photoinitiators, has been selected and doped to synthesize the photopolymers in this research. Using a two-step thermo-polymerization procedure two photopolymer samples have been fabricated, Irgacure 784 doped poly(methyl methacrylate) (PMMA) and Irgacure 784 doped epoxy resin. Samples of 2 mm thick have been fabricated. Holographic measurements show that Irgacure 784 doped epoxy resin is very sensitive at 532 nm and that it is capable of supporting holographic data storage at a ultra-fast recording rate of 760 Mb s-1. Mass spectrum measurement, solid state 1H-NMR spectrum measurement, and thermogravity analyses (TGA) have been performed. The results reveal the physical mechanism of holographic recording in these samples, providing a guideline for a design strategy and fabrication technique to produce a low-shrinkage recording material for holographic data storage in the tera-byte information age.

  6. 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

  7. Resolved Sideband Spectroscopy and Cooling of Strontium in a 532-nm Optical Lattice

    NASA Astrophysics Data System (ADS)

    Aman, James; Hill, Joshua; Killian, T. C.

    2016-05-01

    Resolved sideband cooling is a powerful and well established technique for driving ultracold atoms in optical lattices to the motional ground state of individual lattice sites. Here we present spectroscopy of the narrow 5s21S0 --> 5 s 5 p3P1 transition for neutral strontium-84 in a 532nm optical lattice. Resolved red- and blue-detuned sidebands are observed corresponding to changes in the motional state in the lattice sites. Driving the red sideband, we demonstrate cooling into the ground state, which increases the initial phase-space density before forced evaporative cooling. This is a promising technique for improving the production of strontium quantum degenerate gases. Research supported by the Robert A, Welch Foundation under Grant No. C-1844.

  8. Effect of visible laser light on ATP level of anaemic red blood cell.

    PubMed

    Suardi, Nursakinah; Sodipo, Bashiru Kayode; Mustafa, Mohd Zulkifli; Ali, Zalila

    2016-09-01

    In this work we present influence of visible laser light on ATP level and viability of anaemic red blood cell (RBC). The visible laser lights used in this work are 460nm and 532nm. The responses of ATP level in anaemic and normal RBC before and after laser irradiation at different exposure time (30, 40, 50 and 60s) were observed. Three aliquots were prepared from the ethylenediaminetetraacetic acid (EDTA) blood sample. One served as a control (untreated) and another two were irradiated with 460nm and 560nm lasers. Packed RBC was prepared to study ATP level in the RBC using CellTiter-GloLuminescent cell Viability Assay kit. The assay generates a glow type signal produced by luciferase reaction, which is proportional to the amount of ATP present in RBCs. Paired t-test were done to analyse ATP level before and after laser irradiation. The results revealed laser irradiation improve level of ATP in anaemic RBC. Effect of laser light on anaemic RBCs were significant over different exposure time for both 460nm (p=0.000) and 532nm (p=0.003). The result of ATP level is further used as marker for RBC viability. The influence of ATP level and viability were studied. Optical densities obtained from the data were used to determine cell viability of the samples. Results showed that laser irradiation increased viability of anaemic RBC compared to normal RBC. PMID:27508880

  9. Removal of copper oxide from copper surfaces using Q-switched Nd:YAG radiation at 1064 nm, 532 nm, and 266 nm

    NASA Astrophysics Data System (ADS)

    Kearns, Aileen; Fischer, C.; Watkins, Kenneth G.; Glasmacher, Mathias; Steen, William M.; Kheyrandish, H.; Brown, A.

    1997-08-01

    During electronic device fabrication it is necessary to remove the oxides from copper surfaces prior to soldering in order to improve the surface wetability and achieve a good quality solder joint. The usual method of achieving this is by using acids in a flux. The work reported here explores the possibility of removing these oxides by laser cleaning using the harmonics of a Q-switched Nd:YAG laser, a technique which could be incorporated into a industrial laser soldering process. The effect of Q-switched Nd:YAG radiation (5 - 10 ns pulses), at 1064 nm, 532 nm and 266 nm, on the oxidized surface of a copper alloy foil is studied with increasing fluence. In order to successfully compare the effect of increasing fluence at the three wavelengths each area treated was only subjected to one laser pulse. The laser treated surfaces were characterized using optical microscopy, SEM, and surface analysis performed by static secondary ion mass spectrometry (SSIMS). SSIMS and SNMS (secondary neutral mass spectrometry) with mechanical depth profilometry were used to characterize the oxide layer. The reflectivity of the oxidized plates for the three wavelengths was ascertained using a reflectivity spectrometer. Successful cleaning was achieved at all wavelengths, above certain threshold values which defined the lower end of the process operating window for single pulse operation. The threshold for the cleaning process decreased with laser wavelength. Surface melting was evident at the lowest fluences examined for all the wavelengths (< .5 J/cm2). This value is well below the lower end of the process windows of all wavelengths. Microscopic `explosive' features were found at the onset of copper oxide removal possibly resulting from ionization or a plasma induced shock waves. There was some possible evidence of mechanical effects at 1064 nm and 532 nm. Large amounts of sputtered debris was found around the 266 nm craters. A SSIMS analysis was performed on the 532 nm spots. The

  10. The effect of the laser wavelength on collinear double pulse laser induced breakdown spectroscopy (DP-LIBS)

    NASA Astrophysics Data System (ADS)

    Wang, Qi; Lin, Yanqing; Liu, Jing; Fan, Shuang; Xu, Zhuopin; Huang, Qing; Wu, Yuejin

    2016-05-01

    The pulsed lasers at wavelengths of 532 nm and 1064 nm were used as two beams of light for collinear double pulse laser induced breakdown spectroscopy (DP-LIBS). By changing the time sequence of two beams of different lasers, we studied the effect of the interval of two pulses of DP-LIBS on spectral signals compared with single pulsed (SP) LIBS.

  11. 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.

  12. Effect of In3+ concentration on the photorefraction and scattering properties in In:Fe:CU:LiNbO3 crystals at 532 nm wavelength

    NASA Astrophysics Data System (ADS)

    Luo, Suhua; Meng, Qingxin; Wang, Jian; Sun, Xiudong

    2016-01-01

    The LiNbO3 crystals doped with Fe2O3, CuO and various In2O3, respectively, have been grown by the Czochralski method in air atmosphere. The photorefractive properties at 532 nm wavelength were measured by using the typical two-wave coupling experiments. Meanwhile, the incident exposure energy flux threshold for the light-induced scattering was characterized to investigate the scattering properties of the crystals. The results show that the response time shortens, the recording sensitivity improves, and the light-induced scattering decreases with the increasing In3+ ions concentration. However, the doping of In3+ ions leads to the decrease of the diffraction efficiency and the gain coefficient. So, the appropriate In3+ ions concentration should be doping in In:Fe:Cu:LiNbO3 crystals to adapt our practical application in the green light region photorefractive holographic recording.

  13. Biomodulation of light on cells in laser surgery

    NASA Astrophysics Data System (ADS)

    Liu, Timon C.; Li, Yan; Duan, Rui; Cai, Xiongwei

    2002-04-01

    In laser surgery, it has been observed pulsed 532-nm laser can avoid postoperative purpura, but pulsed 585-nm, 595-nm or 600-nm lasers nonetheless cause purpura when they were used to treat port-wine stains; the XeCl excimer laser (308 nm) can safely and effectively clear psoriasis; both XeCl excimer laser and Ho:YAG laser were used in coronary interventions, but only former was approved by the FDA; open channels after ultraviolet (UV) laser treatment and closed channels with infrared (IR) lasers for transmyocardial laser revascularization; and so on. In this paper, the biological information model of low intensity laser (BIML) is extended to include UVA biomodulation and is used to understand these phenomena. Although the central intensity of the laser beam is so intense that it destroys the tissue, the edge intensity is so low that it can induce biomodulation. Our investigation showed that biomodulation of light on cells might play an important role in the long-term effects of laser surgery.

  14. Evaluation of CALIOP 532-nm Aerosol Optical Depth Over Opaque Water Clouds

    NASA Technical Reports Server (NTRS)

    Liu, Z.; Winker, D.; Omar, A.; Vaughan, M.; Kar, J.; Trepte, C.; Hu, Y.; Schuster, G.

    2015-01-01

    With its height-resolved measurements and near global coverage, the CALIOP lidar onboard the CALIPSO satellite offers a new capability for aerosol retrievals in cloudy skies. Validation of these retrievals is difficult, however, as independent, collocated and co-temporal data sets are generally not available. In this paper, we evaluate CALIOP aerosol products above opaque water clouds by applying multiple retrieval techniques to CALIOP Level 1 profile data and comparing the results. This approach allows us to both characterize the accuracy of the CALIOP above-cloud aerosol optical depth (AOD) and develop an error budget that quantifies the relative contributions of different error sources. We focus on two spatial domains: the African dust transport pathway over the tropical North Atlantic and the African smoke transport pathway over the southeastern Atlantic. Six years of CALIOP observations (2007-2012) from the northern hemisphere summer and early fall are analyzed. The analysis is limited to cases where aerosol layers are located above opaque water clouds so that a constrained retrieval technique can be used to directly retrieve 532 nm aerosol optical depth and lidar ratio. For the moderately dense Sahara dust layers detected in the CALIOP data used in this study, the mean/median values of the lidar ratios derived from a constrained opaque water cloud (OWC) technique are 45.1/44.4 +/- 8.8 sr, which are somewhat larger than the value of 40 +/- 20 sr used in the CALIOP Level 2 (L2) data products. Comparisons of CALIOP L2 AOD with the OWC-retrieved AOD reveal that for nighttime conditions the L2 AOD in the dust region is underestimated on average by approx. 26% (0.183 vs. 0.247). Examination of the error sources indicates that errors in the L2 dust AOD are primarily due to using a lidar ratio that is somewhat too small. The mean/median lidar ratio retrieved for smoke is 70.8/70.4 +/- 16.2 sr, which is consistent with the modeled value of 70 +/- 28 sr used in the

  15. Direct laser light enhancement of susceptibility of bacteria to gentamicin antibiotic

    NASA Astrophysics Data System (ADS)

    Reznick, Yana; Banin, Ehud; Lipovsky, Anat; Lubart, Rachel; Zalevsky, Zeev

    2011-11-01

    ObjectivesTo test the effect of pulsed (Q-switched) and continuous wave (CW) laser light at wavelength of 532 nm on the viability of free-living stationary phase bacteria with and without gentamicin (an antibiotic) treatment. MethodsFree living stationary phase gram negative bacteria ( Pseudomonas aeruginosa strain PAO1) was immersed in Luria Broth (LB) solution and exposed to Q-switched and CW lasers with and without the addition of the antibiotic gentamicin. Cell viability was determined at different time points. ResultsLaser treatment alone did not reduce cell viability compared to untreated control and the gentamicin treatment alone only resulted in a 0.5 log reduction in the viable count for P. aeruginosa. The combined laser and gentamicin treatment, however, resulted in a synergistic effect and viability was reduced by 8 logs for P. aeruginosa PAO1. ConclusionsCombination of laser light with gentamicin shows an improved efficacy against P. aeruginosa.

  16. Differential Absorption Measurements of Atmospheric Water Vapor with a Coherent Lidar at 2050.532 nm

    NASA Technical Reports Server (NTRS)

    Koch, Grady J.; Dharamsi, Amin; Davis, Richard E.; Petros, Mulugeta; McCarthy, John C.

    1999-01-01

    Wind and water vapor are two major factors driving the Earth's atmospheric circulation, and direct measurement of these factors is needed for better understanding of basic atmospheric science, weather forecasting, and climate studies. Coherent lidar has proved to be a valuable tool for Doppler profiling of wind fields, and differential absorption lidar (DIAL) has shown its effectiveness in profiling water vapor. These two lidar techniques are generally considered distinctly different, but this paper explores an experimental combination of the Doppler and DIAL techniques for measuring both wind and water vapor with an eye-safe wavelength based on a solid-state laser material. Researchers have analyzed and demonstrated coherent DIAL water vapor measurements at 10 micrometers wavelength based on CO2 lasers. The hope of the research presented here is that the 2 gm wavelength in a holmium or thulium-based laser may offer smaller packaging and more rugged operation that the CO2-based approach. Researchers have extensively modeled 2 um coherent lasers for water vapor profiling, but no published demonstration is known. Studies have also been made, and results published on the Doppler portion, of a Nd:YAG-based coherent DIAL operating at 1.12 micrometers. Eye-safety of the 1.12 micrometer wavelength may be a concern, whereas the longer 2 micrometer and 10 micrometer systems allow a high level of eyesafety.

  17. Characterization and FDTD simulation analysis on light trapping structures of amorphous silicon thin films by laser irradiation

    NASA Astrophysics Data System (ADS)

    Huang, Lu; Jin, Jing; Yuan, Zhijun; Yang, Weiguang; Wang, Linjun; Shi, Weimin; Zhou, Jun; Lou, Qihong

    2016-05-01

    The effect of laser energy density on the light-trapping structures of amorphous silicon (α-Si) thin films is studied both theoretically and experimentally. The thin films are irradiated by a frequency-doubled (λ = 532 nm) Nd:YAG pulsed nanosecond laser. An effective finite difference time domain (FDTD) model is built to find the optimized laser energy density (EL) for the light trapping structures of α-Si. Based on the simulation analysis, it shows the variation of reflection spectra with laser energy density. The optimized reflection spectra at EL = 1000 mJ/cm2 measured by UV-visible spectroscopy confirms to agree well with that corresponding to the depth to diameter ratio (h/D) in the FDTD simulation. The surface morphology characterization by optical microscope (OM) and scanning electron microscope (SEM) accords fairly well to of light-trapping modeling in the simulation.

  18. Implementation of Rotational Raman Channel in Multiwavelength Aerosol Lidar to Improve Measurements of Particle Extinction and Backscattering at 532 NM

    NASA Astrophysics Data System (ADS)

    Veselovskii, Igor; Whiteman, David N.; Korenskiy, Michael; Suvorina, A.; Perez-Ramirez, Daniel

    2016-06-01

    We describe a practical implementation of rotational Raman (RR) measurements in an existing Mie-Raman lidar to obtain measurements of aerosol extinction and backscattering at 532 nm. A 2.3 nm width interference filter was used to select a spectral range characterized by low temperature sensitivity within the anti-Stokes branch of the RR spectrum. Simulations demonstrate that the temperature dependence of the scattering cross section does not exceed 1.0% in the 230-300K range making accurate correction for this dependence quite easy. With this upgrade, the NASA/GSFC multiwavelength Raman lidar has demonstrated useful α532 measurements and was used for regular observations. Examples of lidar measurements and inversion of optical data to the particle microphysics will be given in presentation.

  19. Continuous wave laser irradiation of explosives

    SciTech Connect

    McGrane, Shawn D.; Moore, David S.

    2010-12-01

    Quantitative measurements of the levels of continuous wave (CW) laser light that can be safely applied to bare explosives during contact operations were obtained at 532 nm, 785 nm, and 1550 nm wavelengths. A thermal camera was used to record the temperature of explosive pressed pellets and single crystals while they were irradiated using a measured laser power and laser spot size. A visible light image of the sample surface was obtained before and after the laser irradiation. Laser irradiation thresholds were obtained for the onset of any visible change to the explosive sample and for the onset of any visible chemical reaction. Deflagration to detonation transitions were not observed using any of these CW laser wavelengths on single crystals or pressed pellets in the unconfined geometry tested. Except for the photochemistry of DAAF, TATB and PBX 9502, all reactions appeared to be thermal using a 532 nm wavelength laser. For a 1550 nm wavelength laser, no photochemistry was evident, but the laser power thresholds for thermal damage in some of the materials were significantly lower than for the 532 nm laser wavelength. No reactions were observed in any of the studied explosives using the available 300 mW laser at 785 nm wavelength. Tables of laser irradiance damage and reaction thresholds are presented for pressed pellets of PBX9501, PBX9502, Composition B, HMX, TATB, RDX, DAAF, PETN, and TNT and single crystals of RDX, HMX, and PETN for each of the laser wavelengths.

  20. Formation of temperature fields in doped anisotropic crystals under spatially inhomogeneous light beams passing through them

    SciTech Connect

    Zaitseva, E. V.; Markelov, A. S.; Trushin, V. N. Chuprunov, E. V.

    2013-12-15

    The features of formation of thermal fields in potassium dihydrophosphate crystal doped with potassium permanganate under a 532-nm laser beam passing through it have been investigated. Data on the influence of birefringence on the temperature distribution in an anisotropic crystal whose surface is illuminated by a spatially modulated light beam are presented.

  1. Formation of temperature fields in doped anisotropic crystals under spatially inhomogeneous light beams passing through them

    NASA Astrophysics Data System (ADS)

    Zaitseva, E. V.; Markelov, A. S.; Trushin, V. N.; Chuprunov, E. V.

    2013-12-01

    The features of formation of thermal fields in potassium dihydrophosphate crystal doped with potassium permanganate under a 532-nm laser beam passing through it have been investigated. Data on the influence of birefringence on the temperature distribution in an anisotropic crystal whose surface is illuminated by a spatially modulated light beam are presented.

  2. Growth and optical photorefraction of Zr:Fe:LiNbO3 crystals with various [Li]/[Nb] ratios at 532 nm wavelength

    NASA Astrophysics Data System (ADS)

    Luo, Suhua; Wang, Jian; Meng, Qingxin; Sun, Xiudong

    2013-11-01

    Zr:Fe:LiNbO3 crystals were grown in air by the Czochralski technique with various [Li]/[Nb] ratios of 0.85, 1.05, and 1.38 in melt. Based on the ICP-AES (inductively coupled plasma atomic emission spectrometry) analyzed results, the chemical formulas of Zr:Fe:LiNbO3 crystals were obtained. The sign of the dominate charge carriers as well as the two-wave coupling gain coefficient as a function of the [Li]/[Nb] ratios in crystal were investigated by using the typical two-wave coupling experimental setup. The results show that electrons are the dominate charge carriers and the gain coefficient is the largest when the recording angle 2θ=21° in the sample with [Li]/[Nb]=0.7111 in crystal. In addition, the dependence of the light-induced birefringence on the [Li]/[Nb] ratios was measured in Zr:Fe:LiNbO3 crystals, which shows that the optical damage resistance of Zr:Fe:LiNbO3 crystals increases with the increasing of [Li]/[Nb] ratios at 532 nm wavelength. The dependences of the green photorefraction on the defect structure of Zr:Fe:LiNbO3 crystals are discussed in detail based on the obtained chemical formulas.

  3. Dynamics of Light-Absorption Variations Induced in a Bismuth Silicate Crystal by Visible Laser Illumination

    NASA Astrophysics Data System (ADS)

    Khudyakova, E. S.; Kisteneva, M. G.; Shandarov, S. M.; Kornienko, T. A.; Tolstik, A. L.; Kargin, Yu. F.

    2015-01-01

    We present the results of experimental studies of the dynamics of the photoinduced optical absorption in a bismuth silicate crystal subject to continuous laser irradiation with wavelengths of 532 and 655 nm. The semiconductor-laser light beam with the wavelength λ = 655 nm causes the crystal bleaching at this wavelength, whereas its exposure to a shorter-wavelength irradiation from the optical-spectrum green region with a wavelength of 532 nm increases the optical absorption at both wavelengths, of 532 and 655 nm. The experimental results are interpreted using the theoretical model which assumes that the crystal has deep defect centers of two types so that an electron at each of these centers can be in one of the states characterized by different photoionization cross sections.

  4. Solid-state laser source of narrowband ultraviolet B light for skin disease care

    NASA Astrophysics Data System (ADS)

    Tarasov, Aleksandr A.; Chu, Hong

    2013-03-01

    We report about the development of all-solid-state laser source of narrowband UV-B light for medical applications. The device is based on a gain-switched Ti: Sapphire laser with volume Bragg grating, pumped at 532 nm and operating at 931.8 nm, followed by a third harmonic generator and a fiber optic beam homogenizer. The maximum available pulse energy exceeded 5 mJ at 310.6 nm, with a pulse repetition rates of 50 Hz. The output characteristics satisfy the medical requirements for psoriasis and vitiligo treatment. A new optical scheme for third harmonic generation enhancement at moderate levels of input intensities is proposed and investigated. As a result, 40% harmonic efficiency was obtained, when input pulse power was only 300 kW.

  5. Thermo-optical effect and saturation of nonlinear absorption induced by gray tracking in a 532-nm-pumped KTP optical parametric oscillator.

    PubMed

    Boulanger, B; Fève, J P; Guillien, Y

    2000-04-01

    We present experiments that show that gray tracking modifies the parametric gain and the generated wavelengths of a KTP optical parametric oscillator pumped at 532 nm near degeneracy. These perturbations occur over a limited range of pump intensity. We propose a satisfactory model that takes into account photochromic damage, the thermo-optical effect, and the combined processes of creation and saturation of a two-photon absorber at 532 nm. The temperature dependence of Sellmeier equations of KTP is also established at 20-200 degrees C. PMID:18064087

  6. Explosively pumped laser light

    DOEpatents

    Piltch, Martin S.; Michelotti, Roy A.

    1991-01-01

    A single shot laser pumped by detonation of an explosive in a shell casing. The shock wave from detonation of the explosive causes a rare gas to luminesce. The high intensity light from the gas enters a lasing medium, which thereafter outputs a pulse of laser light to disable optical sensors and personnel.

  7. Explosively pumped laser light

    SciTech Connect

    Piltch, M.S.; Michelott, R.A.

    1991-09-24

    This patent describes a single shot laser pumped by detonation of an explosive in a shell casing. The shock wave from detonation of the explosive causes a rare gas to luminesce. The high intensity light from the gas enters a lasing medium, which thereafter outputs a pulse of laser light to disable optical sensors and personnel.

  8. Simultaneous Filtered and Unfiltered Light Scattering Measurements in Laser Generated Air Sparks

    NASA Astrophysics Data System (ADS)

    Limbach, Christopher; Miles, Richard

    2013-09-01

    Elastic laser light scattering may be used to measure the thermofluidic properties of gases and plasmas, including but not limited to density, temperature and velocity. Most of this information is contained within the spectra of the scattered radiation. This may be measured directly through dispersion or indirectly, by passing the light through an atomic or molecular vapor filter with known absorption features. In this work, filtered and unfiltered laser light scattering is used to diagnose air sparks generated by a 1064 nm Q-switched laser. The probe laser consists of a second Q-switched Nd:YAG laser frequency doubled to 532 nm. Simultaneous unfiltered and filtered images of the scattering are captured by a Princeton Instruments ICCD camera by using a 50 mm diameter concave re-imaging mirror. The filter consists of a well-characterized molecular Iodine cell. In the shock wave formed by the laser spark, spatially resolved measurements of density, temperature and radial velocity are extracted and compared with theory and models. Measurements in the spark core probe the ion feature of the electron Thomson scattering, from which ne and T can be extracted with the assumption Te =Ti . Partial funding was provided by General Electric Global Research Center: Niskayuna, New York. The first author is also supported by a National Defense Science and Engineering Graduate Fellowship.

  9. Visible luminescence from laser-induced stain- and dry etched silicon

    SciTech Connect

    Dimova-Malinovska, D.; Tzolov, M.; Malinowski, N.

    1996-12-31

    Light emitting silicon has been prepared by Ar laser (514.5 nm) induced stain etching and Nd:YAG impulse (532 nm) laser irradiation in air. Photoluminescence (PL), IR and XPS spectra have been studied. The intensity and position of the PL depend on the power or the energy and the duration of laser beam treatment during the etching. Correlation between the PL and chemical bonding is discussed.

  10. ERL R&D: Laser and Laser Light Transport

    SciTech Connect

    Sheehy, B.

    2010-01-01

    Operation of the photocathode gun in the ERL requires that a tightly controlled optical pulse train, consisting of temporally and spatially shaped pulses, be delivered at the photocathode in synchrony with the RF field in the gun cavity. The pulse train must also be dynamically variable, in order to tune or ramp up the current in the ERL. A laser was developed especially for this task by Lumera Laser GmbH, of Kaiserslautern Germany, under design supervision and review of the ERL project. Following the final design review, the laser was delivered in August 2009. Preliminary tests certifying its compliance with design specifications have been performed, with further tests planned following the final certification of the ERL laser room in January 2010. The development of the necessary spatial and temporal shaping techniques is an ongoing project: proof of principle experiments have been successfully carried out with a laser of similar pulse width, operating at 532 nm and 81.5 MHz. The next stage is to evaluate the application of these techniques and alternatives, using the operations laser. A transport line has been designed and the propagation of a shaped pulse through it to the photocathode simulated and tested experimentally. As the performance of the complete photocathode drive system is critical for ERL operation, an extensive set of diagnostics will be in place to monitor and maintain its performance. The block diagram in Fig. 1 breaks the optical system down into its basic components, which are discussed.

  11. Demonstration of long-term reliability of a 266-nm, continuous-wave, frequency-quadrupled solid-state laser using beta-BaB(2)O(4).

    PubMed

    Kondo, K; Oka, M; Wada, H; Fukui, T; Umezu, N; Tatsuki, K; Kubota, S

    1998-02-01

    We report what we believe to be the first operation of more than 1000 h of a 266-nm (cw) frequency-quadrupled solid-state laser with a 100-mW output. We used beta-BaB(2)O(4)(BBO) crystal grown by the Czochralski method to double the green-light (532-nm) wavelength, using an external resonant cavity. The green light was generated with an intracavity frequency-doubled Nd:YVO(4)laser pumped by a 4-W laser diode. When the incident 532-nm power on the external resonant doubler was 500 mW, we generated 100 mW of cw 266-nm radiation with the BBO crystal. The degradation rate seems to be proportional to the strength of the UV optical electric field. We also obtained a relative intensity noise of -130dB/Hz at frequencies of 2 to 10 MHz for 266-nm laser light. PMID:18084457

  12. Analysis of Laser Breakdown Data

    NASA Astrophysics Data System (ADS)

    Becker, Roger

    2009-03-01

    Experiments on laser breakdown for ns pulses of 532 nm or 1064 nm light in water and dozens of simple hydrocarbon liquids are analyzed and compared to widely-used models and other laser breakdown experiments reported in the literature. Particular attention is given to the curve for the probability of breakdown as a function of the laser fluence at the beam focus. Criticism is made of the na"ive forms of both ``avalanche'' breakdown and multi-photon breakdown. It appears that the process is complex and is intimately tied to the chemical group of the material. Difficulties with developing an accurate model of laser breakdown in liquids are outlined.

  13. Functional assessment of high-level laser irradiation. Annual progress report, 1 August 1983-31 December 1984

    SciTech Connect

    Robbins, D.O.

    1985-01-01

    High-energy, Q-switched pulses from a laser are known to produce punctate lesions on the retina. The structural alterations often extend well beyond the primary area of exposure. This report examines the changes in visual sensitivity following single pulses of 532 nm light several orders of magnitude above the ED 50 level. Both temporary and long-term changes in spectral acuity and contrast sensitivity indicate the functional consequences of intense laser irradiation of minute areas of the central fovea.

  14. Polarization behavior of paints doped with silicone light diffusion agent

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Xie, Wei; Guo, Honggui; Wu, Jianye

    2016-02-01

    We report on the polarization behavior of painted samples doped with a silicone light diffusion agent and illuminated by linearly polarized laser light centered at 532 and 650 nm. Reflection spectra of the painted samples with dopant concentration of 0 and 12.2 wt.% were examined. The degree of depolarization increases from 0.35 to 0.8 under laser illumination at 650 nm and from 0.5 to 0.94 under laser illumination at 532 nm with an increasing concentration of light diffusion agent. The polarization behavior of painted samples was described, taking into account contribution of both surface scattering and volume scattering.

  15. 100-watt fiber-based green laser with near diffraction-limited beam quality

    NASA Astrophysics Data System (ADS)

    Hu, Dan; Eisenberg, Eric; Brar, Khush; Yilmaz, Tolga; Honea, Eric

    2010-02-01

    An air-cooled, light-weight, fiber-based, high power green laser has been prototyped. The system consists of an all-fibercoupled IR pump laser at 1064 nm and a frequency-conversion module in a compact and flexible configuration. The IR laser operates in QCW mode, with 10 MHz pulse repetition frequency and 3-5 ns pulse width, to generate sufficient peak power for frequency doubling in the converter module. The IR laser can produce more than 200 W in a linearlypolarized diffraction-limited output beam with high spectral brightness for frequency conversion. The converter module has an input telescope and an oven with a nonlinear crystal to efficiently convert the 1064-nm IR fiber laser output to 532-nm green output. The IR laser and conversion module are connected via a stainless-steel protected delivery fiber for optical beam delivery and an electrical cable harness for electrical power delivery and system control. The beam quality of the 532 nm output remains near diffraction-limited, with M2<1.4. Up to 101 W of 532 nm output was demonstrated and multi-hour runs were characterized at 75 W output. The weights of the IR laser package and doubler are 69 lbs and 14 lbs respectively. An overview of the system and full characterization results will be presented. Such compact, highbrightness green laser sources are expected to enable various scientific, defense and industrial applications.

  16. 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.

  17. Laser light scattering review

    NASA Technical Reports Server (NTRS)

    Schaetzel, Klaus

    1989-01-01

    Since the development of laser light sources and fast digital electronics for signal processing, the classical discipline of light scattering on liquid systems experienced a strong revival plus an enormous expansion, mainly due to new dynamic light scattering techniques. While a large number of liquid systems can be investigated, ranging from pure liquids to multicomponent microemulsions, this review is largely restricted to applications on Brownian particles, typically in the submicron range. Static light scattering, the careful recording of the angular dependence of scattered light, is a valuable tool for the analysis of particle size and shape, or of their spatial ordering due to mutual interactions. Dynamic techniques, most notably photon correlation spectroscopy, give direct access to particle motion. This may be Brownian motion, which allows the determination of particle size, or some collective motion, e.g., electrophoresis, which yields particle mobility data. Suitable optical systems as well as the necessary data processing schemes are presented in some detail. Special attention is devoted to topics of current interest, like correlation over very large lag time ranges or multiple scattering.

  18. Laser light scattering review

    NASA Astrophysics Data System (ADS)

    Schaetzel, Klaus

    1989-08-01

    Since the development of laser light sources and fast digital electronics for signal processing, the classical discipline of light scattering on liquid systems experienced a strong revival plus an enormous expansion, mainly due to new dynamic light scattering techniques. While a large number of liquid systems can be investigated, ranging from pure liquids to multicomponent microemulsions, this review is largely restricted to applications on Brownian particles, typically in the submicron range. Static light scattering, the careful recording of the angular dependence of scattered light, is a valuable tool for the analysis of particle size and shape, or of their spatial ordering due to mutual interactions. Dynamic techniques, most notably photon correlation spectroscopy, give direct access to particle motion. This may be Brownian motion, which allows the determination of particle size, or some collective motion, e.g., electrophoresis, which yields particle mobility data. Suitable optical systems as well as the necessary data processing schemes are presented in some detail. Special attention is devoted to topics of current interest, like correlation over very large lag time ranges or multiple scattering.

  19. Fiber-Coupled Planar Light-Wave Circuit for Seed Laser Control in High Spectral Resolution Lidar Systems

    NASA Technical Reports Server (NTRS)

    Cook, Anthony; McNeil, Shirley; Switzer, Gregg; Battle, Philip

    2010-01-01

    Precise laser remote sensing of aerosol extinction and backscatter in the atmosphere requires a high-power, pulsed, frequency doubled Nd:YAG laser that is wavelength- stabilized to a narrow absorption line such as found in iodine vapor. One method for precise wavelength control is to injection seed the Nd:YAG laser with a low-power CW laser that is stabilized by frequency converting a fraction of the beam to 532 nm, and to actively frequency-lock it to an iodine vapor absorption line. While the feasibility of this approach has been demonstrated using bulk optics in NASA Langley s Airborne High Spectral Resolution Lidar (HSRL) program, an ideal, lower cost solution is to develop an all-waveguide, frequency-locked seed laser in a compact, robust package that will withstand the temperature, shock, and vibration levels associated with airborne and space-based remote sensing platforms. A key technology leading to this miniaturization is the integration of an efficient waveguide frequency doubling element, and a low-voltage phase modulation element into a single, monolithic, planar light-wave circuit (PLC). The PLC concept advances NASA's future lidar systems due to its compact, efficient and reliable design, thus enabling use on small aircraft and satellites. The immediate application for this technology is targeted for NASA Langley's HSRL system for aerosol and cloud characterization. This Phase I effort proposes the development of a potassium titanyl phosphate (KTP) waveguide phase modulator for future integration into a PLC. For this innovation, the proposed device is the integration of a waveguide-based frequency doubler and phase modulator in a single, fiber pigtail device that will be capable of efficient second harmonic generation of 1,064-nm light and subsequent phase modulation of the 532 nm light at 250 MHz, providing a properly spectrally formatted beam for HSRL s seed laser locking system. Fabrication of the integrated PLC chip for NASA Langley, planned for

  20. 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.

  1. Dual wavelength laser damage testing for high energy lasers.

    SciTech Connect

    Atherton, Briggs W.; Rambo, Patrick K.; Schwarz, Jens; Kimmel, Mark W.

    2010-05-01

    As high energy laser systems evolve towards higher energies, fundamental material properties such as the laser-induced damage threshold (LIDT) of the optics limit the overall system performance. The Z-Backlighter Laser Facility at Sandia National Laboratories uses a pair of such kiljoule-class Nd:Phosphate Glass lasers for x-ray radiography of high energy density physics events on the Z-Accelerator. These two systems, the Z-Beamlet system operating at 527nm/ 1ns and the Z-Petawatt system operating at 1054nm/ 0.5ps, can be combined for some experimental applications. In these scenarios, dichroic beam combining optics and subsequent dual wavelength high reflectors will see a high fluence from combined simultaneous laser exposure and may even see lingering effects when used for pump-probe configurations. Only recently have researchers begun to explore such concerns, looking at individual and simultaneous exposures of optics to 1064 and third harmonic 355nm light from Nd:YAG [1]. However, to our knowledge, measurements of simultaneous and delayed dual wavelength damage thresholds on such optics have not been performed for exposure to 1054nm and its second harmonic light, especially when the pulses are of disparate pulse duration. The Z-Backlighter Facility has an instrumented damage tester setup to examine the issues of laser-induced damage thresholds in a variety of such situations [2] . Using this damage tester, we have measured the LIDT of dual wavelength high reflectors at 1054nm/0.5ps and 532nm/7ns, separately and spatially combined, both co-temporal and delayed, with single and multiple exposures. We found that the LIDT of the sample at 1054nm/0.5ps can be significantly lowered, from 1.32J/cm{sup 2} damage fluence with 1054/0.5ps only to 1.05 J/cm{sup 2} with the simultaneous presence of 532nm/7ns laser light at a fluence of 8.1 J/cm{sup 2}. This reduction of LIDT of the sample at 1054nm/0.5ps continues as the fluence of 532nm/7ns laser light simultaneously

  2. CW laser light condensation.

    PubMed

    Zhurahov, Michael; Bekker, Alexander; Levit, Boris; Weill, Rafi; Fischer, Baruch

    2016-03-21

    We present a first experimental demonstration of classical CW laser light condensation (LC) in the frequency (mode) domain that verifies its prediction (Fischer and Weill, Opt. Express20, 26704 (2012)). LC is based on weighting the modes in a noisy environment in a loss-gain measure compared to an energy (frequency) scale in Bose-Einstein condensation (BEC). It is characterized by a sharp transition from multi- to single-mode oscillation, occurring when the spectral-filtering (loss-trap) has near the lowest-loss mode ("ground-state") a power-law dependence with an exponent smaller than 1. An important meaning of the many-mode LC system stems from its relation to lasing and photon-BEC. PMID:27136845

  3. Lasers for ultrashort light pulses

    SciTech Connect

    Herrmann, J.; Wilhelmi, B.

    1987-01-01

    The present rapid expansion of research work on picosecond lasers and their application makes it difficult to survey and comprehend the large number of publications in this field. This book aims to provide an introduction to the field starting with the very basic and moving on to an advanced level. Contents: Fundamentals of the interaction between light pulses and matter; Fundamentals of lasers for ultrashort light pulses; Methods of measurement; Active modelocking; Synchronously pumped lasers; Passive modelocking of dye lasers; Passive modelocking of solid state lasers; Nonstationary nonlinear optical processes; Ultrafast spectroscopy.

  4. Tri-wave laser therapy for spinal cord injury, neuropathic pain management, and restoration of motor function

    NASA Astrophysics Data System (ADS)

    Chariff, Mark D.; Olszak, Peter

    2015-03-01

    A laser therapy device using three combined wavelengths 532nm, 808nm, and 1064nm has been demonstrated in clinical studies. Primarily, therapeutic lasers have used wavelengths in the ranges of 632nm through 1064nm, where the optical density (OD) < 5, to achieve pain relief and tissue regeneration. Conventional wisdom would argue against using wavelengths in the region of 532nm, due to poor penetration (OD ~ 8); however, the author's observations are to the contrary. The 532nm light is efficiently absorbed by chromophores such as oxyhemoglobin, deoxyhemoglobin, and cytochrome c oxidase thereby providing energy to accelerate the healing process. The 808nm light is known to result in Nitric Oxide production thereby reducing inflammation and oxidative stress. All three laser wavelengths likely contribute to pain relief by inhibiting nerve conduction; however, the 1064nm has the deepest penetration. Through the use of this device on over 1000 patients with a variety of acute and chronic neuro-musculoskeletal disorders, the author observed that a majority of these individuals experienced rapid relief from their presenting conditions and most patients reported a tingling sensation upon irradiation. Patient testimonials and thermal images have been collected to document the results of the laser therapy. These studies demonstrate the ability of laser therapy to rapidly alleviate pain from both acute and chronic conditions.

  5. Laser technology in automotive lighting

    NASA Astrophysics Data System (ADS)

    Altingöz, Ceren

    2014-03-01

    The last few years have seen something of a revolution in automotive lighting facilitated by a range of new photonics advances. The lighting industry as a whole is moving rapidly from the incandescent and gas discharge based technologies that dominated the 20th century to solid state technology in the form of Light Emitting Diodes (LED) which are a point source light, Organic Light Emitting Diodes (OLED) which are an area source light and at the edge the increasing use of lasers with different functional applications. In this paper I will focus on this edge technology of lasers as they are still trying to find their right place in automotive lighting. To better analyze their potential, the working principle of a laser will be explained, laser types used in automotive lighting, their application methods, advantages and disadvantages of their usage will be declared, application examples from the current trials of some leading automotive industry research groups will be given and finalization will be with an overall view of the possible future laser applications in the field of automotive lighting.

  6. Pulse laser machining and particulate separation from high impact polystyrene

    NASA Astrophysics Data System (ADS)

    Arif, Saira; Kautek, Wolfgang

    2014-01-01

    Opaque high impact polystyrene (HIPS) contaminated with graphite particles and poly(styrene-co-divinyl benzene) spheres can only be removed efficiently with nanosecond-pulsed laser radiation of 532 nm while the substrate is preserved. The destruction thresholds are 1-2 orders of magnitude lower than that of other common technical polymers. The inhomogeneously distributed polybutadiene composite component led to enhanced light scattering in the polystyrene matrix so that increased light absorption and energy density causes a comparatively low ablation threshold. Due to this fact there is advantageous potential for pulse laser machining at comparatively low fluences.

  7. Visible and near infrared resonance plasmonic enhanced nanosecond laser optoporation of cancer cells

    PubMed Central

    St-Louis Lalonde, Bastien; Boulais, Étienne; Lebrun, Jean-Jacques; Meunier, Michel

    2013-01-01

    In this paper, we report a light driven, non-invasive cell membrane perforation technique based on the localized field amplification by a nanosecond pulsed laser near gold nanoparticles (AuNPs). The optoporation phenomena is investigated with pulses generated by a Nd:YAG laser for two wavelengths that are either in the visible (532 nm) or near infrared (NIR) (1064 nm). Here, the main objective is to compare on and off localized surface plasmonic resonance (LSPR) to introduce foreign material through the cell membrane using nanosecond laser pulses. The membrane permeability of human melanoma cells (MW278) has been successfully increased as shown by the intake of a fluorescent dye upon irradiation. The viability of this laser driven perforation method is evaluated by propidium iodide exclusion as well as MTT assay. Our results show that up to 25% of the cells are perforated with 532 nm pulses at 50 mJ/cm2 and around 30% of the cells are perforated with 1064 nm pulses at 1 J/cm2. With 532 nm pulses, the viability 2 h after treatment is 64% but it increases to 88% 72 h later. On the other hand, the irradiation with 1064 nm pulses leads to an improved 2 h viability of 81% and reaches 98% after 72 h. Scanning electron microscopy images show that the 5 pulses delivered during treatment induce changes in the AuNPs size distribution when irradiated by a 532 nm beam, while this distribution is barely affected when 1064 nm is used. PMID:23577284

  8. Resonance running hologram velocity nonlinearity dependence upon light intensity in photorefractive crystals

    NASA Astrophysics Data System (ADS)

    de Oliveira, Ivan; Carvalho, Jesiel F.; Frejlich, Jaime

    2013-06-01

    We report on the nonlinear relation between the resonance hologram velocity and the recording light irradiance in fringe-locked running hologram experiments carried out on a nominally undoped photorefractive Bi12TiO20 crystal using 532 nm wavelength laser light. Such nonlinearity is due to the dependence of the material diffusion length on the light irradiance. Experimental data show a good agreement with the theoretical equations thus supporting the mathematical model here reported and allowing to compute the quantum efficiency for photoelectron generation, the dependence of the diffusion length upon the recorded light irradiance, and the far from saturation diffusion length.

  9. Characterization of extreme ultraviolet light-emitting plasmas from a laser-excited fluorine containing liquid polymer jet target

    NASA Astrophysics Data System (ADS)

    Abel, B.; Assmann, J.; Faubel, M.; Gäbel, K.; Kranzusch, S.; Lugovoj, E.; Mann, K.; Missalla, T.; Peth, Ch.

    2004-06-01

    The operation of a liquid polymer jet laser-plasma target and the characterization of the absolute x-ray emission in the extreme ultraviolet wavelength window from 9-19 nm is reported. The target is a liquid polymer (perfluoro-polyether) that is exposed to pulsed and focused laser light at 532 nm in the form of a thin, liquid microjet (d=40 to 160 μm) in vacuum. The spectral brightness of the source in the 13 nm range is relatively high because a large fraction of radiative energy is emitted in one single line only, which is assigned to be the 2p-3d FVII doublet at 12.8 nm, with a laser energy conversion efficiency of 0.45% (2π sr, 2% bandwidth) in our initial experiment. A further increase of the relative emission has been found in the wavelength range between 7 and 17 nm when the jet diameter was increased from 40 to 160 μm. The two-dimensional spatial profile of the source plasma (d=40 to 50 μm) has been analyzed with a pinhole camera.

  10. UV Laser Diagnostics of the 1-MA Z-pinch Plasmas

    SciTech Connect

    Altemara, S. D.; Ivanov, V. V.; Astanovitskiy, A. L.; Haboub, A.

    2009-01-21

    The 532 nm laser diagnostic set at the Zebra generator shows the details of the ablation and stagnation phases in cylindrical, planar, and star-like wire arrays but it cannot show the structure of the stagnated z-pinch and the implosion in small diameter loads, 1-3 mm in diameter. The absorption increment and the refraction angle of the 532 nm laser, when passing through the plasma, are too great to obtain quality images. An ultraviolet probing beam at the wavelength of 266 nm was developed to study small-diameter loads and to investigate the structure of the 1-MA z-pinch. The UV radiation has a much smaller absorption increment and refraction angles in plasmas than the 532 nm light and allows for better imaging of the z-pinch plasmas. Estimates showed that UV probing would be able to probe the high-density z-pinch plasma in experiments on the Zebra generator, and the early results of UV probing on the Zebra generator have shown promise.

  11. 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.

  12. SIMPL Laser Altimeter Measurements of Lake Erie Ice Cover: a Pathfinder for ICESat-2

    NASA Astrophysics Data System (ADS)

    Harding, D. J.; Dabney, P.; Valett, S. R.; Kelly, A.

    2010-12-01

    NASA’s ICESat-2 missions, scheduled for launch in 2015, will make measurements of ice sheet elevation change, sea ice thickness change and vegetation height using a micro-pulse, multi-beam laser altimeter employing single photon ranging at 532 nm (green). Lake Erie ice and snow cover data acquired in February 2009 by the Slope Imaging Multi-polarization Photon-counting Lidar (SIMPL) provides pathfinder information enabling improved understanding of this next-generation altimeter measurement approach. SIMPL is an airborne, multi-beam laser altimeter developed through the NASA Earth Science Technology Office Instrument Incubator Program with a focus on cryopshere remote sensing. SIMPL operates at 532 nm and 1064 nm using a micropulse laser, achieving a ranging precision of 8 cm per single photon, and acquires reflected energy parallel and perpendicular to the transmit pulse polarization plane. Approximately 30,000 single photon returns per second are acquired from snow and ice at the nominal flight altitude of 8,000 ft. The resulting two-color information on surface and volume scattering properties enables differentiation of open water and ice types with varying optical properties. For open water, SIMPL data documents laser pulse penetration at 532 nm in the water column, relative to the surface defined by the 1064 nm data. And increasing amount of perpendicularly polarized light with depth relative to the parallel polarization, indicating an increasing fraction of multiply scattered photons, provides a measure of water column optical depth. The observed ice cover types (skim, nias, new grey ice, new grey-white ice) represent the early stages of sea ice formation. Differences in surface roughness and transparency of the ice types are indicated by the 532 nm and 1064 nm perpendicular/parallel depolarization ratio measures of the degree of multiple scattering. The understanding of laser pulse interactions with water, ice and snow using this first-of-its-kind data set

  13. Physics Holographic Recording Device Based on LCoS Spatial Light Modulator

    NASA Astrophysics Data System (ADS)

    Bulanovs, A.; Tamanis, E.; Mihailova, I.

    2011-01-01

    A PC-controlled holographic recording device has been developed in which a LC-R-2500 Spatial Light Modulator (SLM) based on reflective Liquid Crystal on Silicone (LCoS) display was used. The device allows the amplitude and phase modu-lation of coherent light wave fronts. In the optical scheme, a DPSS (Diode Pumped Solid State) laser with nanosecond pulse duration and wavelength 532 nm was applied. The holographic recording was made and tested in the amplitude and phase wave front modulation modes on a chalcogenide semiconductor photoresist As40S15S45. The experimental results are presented.

  14. High energy picosecond laser for applications in microstructuring of crystalline silicon

    NASA Astrophysics Data System (ADS)

    Lin, Xuechun; Yu, Haijuan; Huang, Yongguang; Zhang, Ling; Zhu, Hongliang

    2012-10-01

    Black silicon is very promising for the third generation Solar Cells, because of its fascinating light absorption of above 98% in visible spectrum and more than 90% in 800-2500 nm, and its surface micro-nano structures enlarge light trapping intermediate impurities levels caused by supersaturated doping expand absorptive limitation of crystalline Si. In recent years femtosecond laser pulses were widely used in the process of improving the absorptance by irradiating silicon surfaces with in the presence of different gases. Nevertheless, picosecond laser used to fabricate large-area black silicon is seldom reported. A diode-pumped picosecond Nd:YAG regenerative amplifier laser system designed for microstructuring the crystalline silicon was reported in this paper. At the repetition of 1 kHz, the system generated 1 W average-power, 26-ps-long pulses with a pulse energy of 1 mJ at 1064 nm, which corresponds the peak power of 38.5 MW. A 0.5 W second-harmonic 532 nm laser is achieved with a 20 mm long noncritically phase-matched lithium triborate (LBO) crystal from the 1W 1064 nm laser. igh optical absorption black Si irradiated with 1064 nm and 532 nm picosecond pulses in SF6 at different laser fluence. And the relationship between the surface morphology and the wavelength or the laser fluence was researched.

  15. Characterization of laser-treated paper

    NASA Astrophysics Data System (ADS)

    Rudolph, P.; Ligterink, F. J.; Pedersoli, J. L., Jr.; van Bommel, M.; Bos, J.; Aziz, H. A.; Havermans, J. B. G. A.; Scholten, H.; Schipper, D.; Kautek, W.

    Paper is one of the most important materials in cultural heritage given its extensive use as the data carrier for religious, artistic and scientific records. For both aesthetic and conservation reasons, cleaning of these materials is often needed. Current paper cleaning methods using conventional means are not always sufficient, e.g. for the local cleaning of paper in the vicinity of sensitive media. In this respect a ns-pulse laser provides a valuable tool for solving difficult cleaning problems. The influence of various laser wavelengths (355 nm, 532 nm, and 1064 nm) and the ageing status of modern paper test systems were studied. Colorimetric measurements, the determination of the average molecular mass of cellulose, and chemiluminescence analysis proved to be useful for the characterization of the laser-treated paper. Treatment with green laser light at λ=532 nm below the paper ablation threshold fluence gave the most promising results on pure papers, with no discolouration and no other visible alteration, nor detectable chemical changes.

  16. Highly Flexible Home-built ND:YVO4 Modelocked Laser System for Trapped Ion Qubit Raman Transitions

    NASA Astrophysics Data System (ADS)

    Sakrejda, Tomasz; Wright, John; Graham, Richard; Zhou, Zichao; Blinov, Boris

    2014-05-01

    A passively mode-locked ND:YVO4 laser system for driving Raman transitions in Ba+ and Yb+ is constructed and evaluated. Based on on a commercial CW laser platform, we make straightforward modifications to the cavity to effect passive mode locking. With 20 W of 808 nm diode pump light, we achieve over 4 W 1064 nm output power, 150 MHz repetition rate, and 17 ps pulse duration. Laser cavity parameters can be easily modified to facilitate changes in pulse duration or repetition rate. Stable mode locking is achieved at start-up with no perturbations to the cavity resonator. The output 1064 nm light can frequency-doubled in an external LBO crystal to generate up to 130 mW of 532 nm light in a single pass. The 532 nm light is close enough to the 493 nm line in Ba+ to drive ground state qubit flips with a single laser pulse. We plan to use this laser to drive qubit gates in both Ba 138+ and, with a third harmonic (355 nm) generation system, in 171Yb+. Supported by MUSIQC/IARPA.

  17. Efficient high-power frequency doubling of distributed Bragg reflector tapered laser radiation in a periodically poled MgO-doped lithium niobate planar waveguide.

    PubMed

    Jedrzejczyk, Daniel; Güther, Reiner; Paschke, Katrin; Jeong, Woo-Jin; Lee, Han-Young; Erbert, Götz

    2011-02-01

    We report on efficient single-pass, high-power second-harmonic generation in a periodically poled MgO-doped LiNbO3 planar waveguide using a distributed Bragg reflector tapered diode laser as a pump source. A coupling efficiency into the planar waveguide of 73% was realized, and 1.07 W of visible laser light at 532 nm was generated. Corresponding optical and electro-optical conversion efficiencies of 26% and 8.4%, respectively, were achieved. Good agreement between the experimental data and the theoretical predictions was observed. PMID:21283192

  18. Explosive laser light initiation of propellants

    DOEpatents

    Piltch, M.S.

    1993-05-18

    A improved initiator for artillery shell using an explosively generated laser light to uniformly initiate the propellent. A small quantity of a high explosive, when detonated, creates a high pressure and temperature, causing the surrounding noble gas to fluoresce. This fluorescence is directed into a lasing material, which lases, and directs laser light into a cavity in the propellant, uniformly initiating the propellant.

  19. Explosive laser light initiation of propellants

    DOEpatents

    Piltch, Martin S.

    1993-01-01

    A improved initiator for artillery shell using an explosively generated laser light to uniformly initiate the propellent. A small quantity of a high explosive, when detonated, creates a high pressure and temperature, causing the surrounding noble gas to fluoresce. This fluorescence is directed into a lasing material, which lases, and directs laser light into a cavity in the propellant, uniformly initiating the propellant.

  20. Single mode optofluidic distributed feedback dye laser

    NASA Astrophysics Data System (ADS)

    Li, Zhenyu; Zhang, Zhaoyu; Emery, Teresa; Scherer, Axel; Psaltis, Demetri

    2006-01-01

    Single frequency lasing from organic dye solutions on a monolithic poly(dimethylsiloxane) (PDMS) elastomer chip is demonstrated. The laser cavity consists of a single mode liquid core/PDMS cladding channel waveguide and a phase shifted 15th order distributed feedback (DFB) structure. A 1mM solution of Rhodamine 6G in a methanol and ethylene glycol mixture was used as the gain medium. Using 6 nanosecond 532nm Nd:YAG laser pulses as the pump light, we achieved threshold pump fluence of ~0.8mJ/cm2 and single-mode operation at pump levels up to ten times the threshold. This microfabricated dye laser provides a compact and inexpensive coherent light source for microfluidics and integrated optics covering from near UV to near IR spectral region.

  1. Lasers in light skin interaction

    NASA Astrophysics Data System (ADS)

    Chan, Benny L.; Jutamulia, Suganda

    2010-11-01

    Lasers used in dermatological treatments are presented. Commercially available semiconductor lasers (laser diodes) are also presented for comparison. Potential applications of semiconductor lasers to noninvasive information processing or diagnosis as well as medical treatment are discussed. In addition, the current application of LEDs to dermatology is also included in the paper.

  2. Laser-induced alteration of contaminated papers

    NASA Astrophysics Data System (ADS)

    Rudolph, P.; Ligterink, F. J.; Pedersoli, J. L., Jr.; Scholten, H.; Schipper, D.; Havermans, J. B. G. A.; Aziz, H. A.; Quillet, V.; Kraan, M.; van Beek, B.; Corr, S.; Hua-Ströfer, H.-Y.; Stokmans, J.; Dalen, P. van; Kautek, W.

    Cleaning of paper objects represents one of the most complex cases of laser ablation, since low volumes of dispersed material phases are evaporated while a sensitive and fragile fibrous organic matrix has to be preserved. Conventional chemical and mechanical cleaning methods suffer from the common phenomenon that the foreign matter is diluted into the substrate rather than removed. The application of a laser beam allows highly localized and optically specific interaction. However, the occurrence of extreme temperatures and light intensities may cause irreversible alteration of the paper matrix. Further, incomplete removal and/or chemical conversion of contaminations may result in insufficient cleaning or affect the ageing behaviour. Laser treatments were performed by Q-switched Nd:YAG lasers at three wavelengths (355 nm, 532 nm, and 1064 nm). Papers contaminated with inks and adhesive-tape remnants served as model samples. Multispectral imaging and colorimetric results served to quantify and systematize the results.

  3. Sum-frequency generation of continuous-wave tunable ultraviolet coherent light in BBO-installed external cavity

    NASA Astrophysics Data System (ADS)

    Mukoyama, Kenta; Tokuyama, Kazuhiro; Kumagai, Hiroshi; Inoue, Norihiro; Fukuda, Naoaki; Takiya, Toshio

    2012-02-01

    Recently, we have tried to develop a continuous wave (CW), tunable, and ultraviolet (UV) coherent light source through sum-frequency generation (SFG) using a BBO nonlinear crystal with a two-stage frequency-conversion system using two different external cavities for the enhancement of CW lights. In the first stage, we obtained the 532-nm light with the second harmonic generation (SHG) of the 1064-nm light. A bow-tie external cavity incorporating four mirrors, whose cavity length was controlled by the frequency stabilization method proposed by Hänsch and Couillaud, was employed there. In the second stage, to generate the 312-nm light, we demonstrated doubly resonant sum frequency generation of the 532-nm light from the first-stage and the 754-nm light from a single-frequency CW Ti:Sapphire laser. Considering a nonlinear coefficient, it should be preferable to use a BiBO crystal for high-efficient SFG, but the 312-nm light might be absorbed by the BiBO crystal. Therefore, we chose a BBO as a nonlinear crystal to avoid the absorption of the 312-nm light.

  4. Enhanced efficiency of AlGaInP disk laser by in-well pumping.

    PubMed

    Mateo, C M N; Brauch, U; Schwarzbäck, T; Kahle, H; Jetter, M; Abdou Ahmed, M; Michler, P; Graf, T

    2015-02-01

    The performance of a 665-nm GaInP disk laser operated continuous-wave at 15°C both in-well-pumped at 640 nm and barrier pumped at 532 nm is reported. The efficiency with respect to the absorbed power was enhanced by 3.5 times when using a 640-nm pump instead of a 532-nm pump. In-well pumping which is based on the absorption of the pump photons within the quantum-well heterostructures of the gain region instead of short-wavelength absorption in the barrier and spacer regions reduces the quantum defect between pump and laser photon and hence the heat generation. A slope efficiency of 60% with respect to the absorbed pump power was obtained by in-well pumping at 15°C. Continuous-wave laser operation was further demonstrated at heat sink temperatures of up to 55°C. Both the measurement of photoluminescence and COMSOL simulation show that the overall heat load in the in-well pumped laser is smaller than in the barrier-pumped laser. These results demonstrate the potential of optical in-well pumping for the operation of red AlGaInP disk lasers if combined with means for efficient pump-light absorption. PMID:25836115

  5. Green pumped Alexandrite lasers

    NASA Astrophysics Data System (ADS)

    Kuper, Jerry W.; Brown, David C.

    2005-04-01

    Initial experiments with pulsed and CW pumping an alexandrite laser rod at 532 nm are presented. This pumping architecture holds promise for the production of scalable diode-pumped, tunable alexandrite laser systems operating in the near infrared (750 nm), and the ultraviolet (375 and 250 nm) spectral regions.

  6. New methods in order to determine the extent of temporary blinding from laser and LED light and proposal how to allocate into blinding groups

    NASA Astrophysics Data System (ADS)

    Reidenbach, Hans-Dieter; Ott, Günter; Brose, Martin; Dollinger, Klaus

    2010-02-01

    Indirect effects arising from bright artificial optical sources like temporary blinding might result in serious incidents or even accidents due to accompanying alteration of visual functions like visual acuity, contrast sensitivity and color discrimination. In order to determine the degree and duration of impairment resulting from glare, dazzle, flash-blindness and afterimages, caused by a beam from a laser or lamp product, particularly under low ambient light conditions, an investigation has been performed with the goal to improve the current knowledge as far as especially recovery duration of visual acuity is concerned. For this two different test set-ups were designed and engineered in order to be able to determine the time duration after which visual acuity returns to its previous value after temporary blinding with a laser or an LED and in addition to search for functional relations as far as wavelength, optical power and exposure duration are concerned. Instead of normal visual acuity measurement, which is the standard test done by eye care professionals, and which has been applied in order to determine the recovery time after irradiation with a high brightness LED (HB-LED) with the aid of a modified commercially available binoptometer with Landolt-C rings as optotypes, a special reading test on a computer monitor was developed for the case of laser irradiation. Two different laser were applied, one with a wavelength of 632.8 nm and the other with 532 nm. Red, green, royal blue and white HB-LEDs were used as stimulating light sources. The maximum applied optical power in a 7-mm aperture, which is equivalent to the pupil diameter of a dark adapted eye, was 0.783 mW (laser) and 3 mW (LED). The exposure durations were chosen as 0.25 s, 0.5 s, 1 s, 5 s, and 20 s in the case of laser irradiation and 0.25 s, 1 s, 5 s, and 10 s for LEDs, respecting maximum permissible exposure (MPE) and/or limit exposure levels (ELVs) in all exposure situations. The visual acuity

  7. χ{sup (3)} measurements of axial ligand modified high valent tin(IV) porphyrins using degenarete four wave mixing at 532nm

    SciTech Connect

    Narendran, N. K. Siji Chandrasekharan, K.; Soman, Rahul; Arunkumar, Chellaiah; Sudheesh, P.

    2014-10-15

    Porphyrins and metalloporphyrins are unique class of molecules for Nonlinear Optical applications because of their unique structure of altering the central metal atom, large extended π-system, high thermal stability, tunable shape, symmetry and synthetic versatility Here, we report χ{sup (3)} Measurements of a simple phenyl porphyrins and its highvalent tin(IV) porphyrins with Bromination characterized by UV-Visible spectroscopic method. In this study, we employed the Degenerate Four Wave Mixing technique using forward Boxcar geometry with an Nd:YAG nano second pulsed laser as source and it was found that the tin(IV) porphyrin with Bromination exhibits good χ{sup (3)} value and figure of merit.

  8. Visible light plasmonic heating of Au-ZnO for the catalytic reduction of CO2

    DOE PAGESBeta

    Wang, Congjun; Ranasingha, Oshadha; Natesakhawat, Sittichai; Ohodnicki, Paul R.; Andio, Mark; Lewis, James P.; Matranga, Christopher

    2013-01-01

    Plasmonic excitation of Au nanoparticles attached to the surface of ZnO catalysts using low power 532 nm laser illumination leads to significant heating of the catalyst and the conversion of CO2 and H2 reactants to CH4 and CO products. Temperature-calibrated Raman spectra of ZnO phonons show that intensity-dependent plasmonic excitation can controllably heat Au–ZnO from 30 to ~600 °C and simultaneously tune the CH4 : CO product ratio. The laser induced heating and resulting CH4 : CO product distribution agrees well with predictions from thermodynamic models and temperature-programmed reaction experiments indicating that the reaction is a thermally driven process resultingmore » from the plasmonic heating of the Au-ZnO. The apparent quantum yield for CO2 conversion under continuous wave (cw) 532 nm laser illumination is 0.030%. The Au-ZnO catalysts are robust and remain active after repeated laser exposure and cycling. The light intensity required to initiate CO2 reduction is low ( ~2.5 x 105 W m-2) and achievable with solar concentrators. Our results illustrate the viability of plasmonic heating approaches for CO2 utilization and other practical thermal catalytic applications.« less

  9. Electronic Rotator For Sheet Of Laser Light

    NASA Technical Reports Server (NTRS)

    Franke, John M.; Rhodes, David B.; Leighty, Bradley D.; Jones, Stephen B.

    1989-01-01

    Primary flow-visualization system in Basic Aerodynamic Research Tunnel (BART) at NASA Langley Research Center is sheet of laser light generated by 5-W argon-ion laser and two-axis mirror galvanometer scanner. Generates single and multiple sheets of light, which remain stationary or driven to sweep out volume. Sine/cosine potentiometer used to orient two galvanometer/mirror devices simultaneously and yields desired result at reasonable cost and incorporated into prototype in 1 day.

  10. Explosive laser light initiation of propellants

    SciTech Connect

    Piltch, M.S.

    1992-12-31

    This invention is comprised of an improved initiator for artillery shell using an explosively generated laser light to uniformly initiate the propellent. A small quantity of a high explosive, when detonated, creates a high pressure and temperature, causing the surrounding noble gas to fluoresce. This fluorescence is directed into a lasing material, which lases, and directs laser light into a cavity in the propellant, uniformly initiating the propellant.

  11. Laser-driven polyplanar optic display

    SciTech Connect

    Veligdan, J.T.; Biscardi, C.; Brewster, C.; DeSanto, L.; Beiser, L.

    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 variable 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.

  12. Engineering Light: Quantum Cascade Lasers

    ScienceCinema

    Claire Gmachl

    2010-09-01

    Quantum cascade lasers are ideal for environmental sensing and medical diagnostic applications. Gmachl discusses how these lasers work, and their applications, including their use as chemical trace gas sensors. As examples of these applications, she briefly presents results from her field campaign at the Beijing Olympics, and ongoing campaigns in Texas, Maryland, and Ghana.

  13. Femtosecond laser processing and spatial light modulator

    NASA Astrophysics Data System (ADS)

    Paivasaari, Kimmo; Silvennoinen, Martti; Kaakkunen, Jarno; Vahimaa, Pasi

    2014-03-01

    The use of the femtosecond laser enables generation of small spot sizes and ablation features. Ablation of the small features usually requires only a small amount of laser power to be delivered to the ablation spot. When using only a one beam for the ablation of the small features this process is bound to be time consuming. The spatial light modulator (SLM) together with the computer generated holograms (CGH) can be used for manipulating and shaping of the laser beam in various applications. In laser micromachining, when using laser with relatively high power, the original beam can be divided up to hundreds beams and still have the energy of the individual beam above the ablation threshold of the material. This parallel laser processing enables more efficient use of the laser power regardless of the machining task.

  14. Reinjection of transmitted laser light into laser-produced plasma for efficient laser ignition.

    PubMed

    Endo, Takuma; Takenaka, Yuhei; Sako, Yoshiyuki; Honda, Tomohisa; Johzaki, Tomoyuki; Namba, Shinichi

    2016-02-10

    For improving the laser absorption efficiency in laser ignition, the transmitted laser light was returned to the laser-produced plasma by using a corner cube. In the experiments, the transmitted light was reinjected into the plasma at different times. The laser absorption efficiency was found to be substantially improved when the transmitted light was reinjected into the plasma after adequate plasma expansion. Furthermore, through visualization experiments on gas-dynamics phenomena, it was found that the reinjection of the transmitted light affected not only the laser absorption efficiency but also the gas dynamics after breakdown, and thereby the initial flame kernel development. PMID:26906388

  15. Laser light scattering instrument advanced technology development

    NASA Technical Reports Server (NTRS)

    Wallace, J. F.

    1993-01-01

    The objective of this advanced technology development (ATD) project has been to provide sturdy, miniaturized laser light scattering (LLS) instrumentation for use in microgravity experiments. To do this, we assessed user requirements, explored the capabilities of existing and prospective laser light scattering hardware, and both coordinated and participated in the hardware and software advances needed for a flight hardware instrument. We have successfully breadboarded and evaluated an engineering version of a single-angle glove-box instrument which uses solid state detectors and lasers, along with fiber optics, for beam delivery and detection. Additionally, we have provided the specifications and written verification procedures necessary for procuring a miniature multi-angle LLS instrument which will be used by the flight hardware project which resulted from this work and from this project's interaction with the laser light scattering community.

  16. Stimulated light forces using picosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Bloch, Immanuel; Goepfert, A.; Haubrich, D.; Lison, F.; Schuetze, R.; Wynands, Robert; Meschede, Dieter

    1997-05-01

    Using the stimulated force exerted by counterpropagating picosecond laser pulses from a mode-locked Ti:Sapphire laser we were able to focus a beam of laser-cooled cesium atoms along one dimension to about 57% of its original width in the detection zone. The force profile was measured outside and inside the overlap region of the pulses and found to be in agreement with an earlier theoretical prediction. A brief theoretical account of the interaction of atoms with pulsed laser light based on the optical Bloch equations is given.

  17. [Dermatological laser- and light treatments of scars].

    PubMed

    Karmisholt, Katrine; Borch, Jakob E; Omland, Silje Haukali; Hædersdal, Merete

    2016-08-01

    Many patients struggle with tender, rigid and erythematous scars. Various modalities are used to treat cutaneous scars and in recent years, laser treatments are emerging as promising procedures. This article describes laser systems used for scar treatment according to scar type, evaluates the highest available level of evidence from randomized controlled trials (RCTs) and introduces a guideline for laser treatment of scars. Twelve RCTs documented effect on acne, burn and surgical scars. It is recommended that laser- and light-based treatments are considered according to the scar type. PMID:27507028

  18. Laser-photophoretic migration and fractionation of human blood cells.

    PubMed

    Monjushiro, Hideaki; Tanahashi, Yuko; Watarai, Hitoshi

    2013-05-13

    Laser photophoretic migration behavior of human blood cells in saline solution was investigated under the irradiation of Nd:YAG laser beam (532 nm) in the absence and the presence of the flow in a fused silica capillary. Red blood cells (RBC) were migrated faster than white blood cells (WBC) and blood pellets to the direction of propagation of laser light. The observed photophoretic velocity of RBC was about 11 times faster than those of others. This was understood from the larger photophoretic efficiency of RBC than that of WBC, which was simulated based on the Mie scattering theory. Furthermore, it was found that, during the photophoretic migration, RBCs spontaneously orientated parallel to the migration direction so as to reduce the drag force. Finally, it was demonstrated that RBC and WBC were separated in a micro-channel flow system by the laser photophoresis. PMID:23622969

  19. Laser based enhancement of susceptibility of bacteria to antibiotic

    NASA Astrophysics Data System (ADS)

    Reznick, Yana; Banin, Ehud; Lipovsky, Anat; Lubart, Rachel; Zalevsky, Zeev

    2012-03-01

    Our objective is to test the effect of pulsed (Q-switched) and continuous wave (CW) laser light at wavelength of 532nm on the viability of free-living stationary phase bacteria with and without gentamicin (an antibiotic) treatment. Free living stationary phase gram negative bacteria (Pseudomonas aeruginosa strain PAO1) was immersed in Luria Broth (LB) solution and exposed to Q-switched and CW lasers with and without the addition of the antibiotic gentamicin. Cell viability was determined at different time points. Laser treatment alone did not reduce cell viability compared to untreated control and the gentamicin treatment alone only resulted in a 0.5 log reduction in the viable count for P. aeruginosa. The combined laser and gentamicin treatment, however, resulted in a synergistic effect and viability was reduced by 8 log's for P. aeruginosa PAO1.

  20. Improved tumour response by laser light treatment

    NASA Astrophysics Data System (ADS)

    Graschew, Georgi; Smith, Janice; Rakowsky, Stefan; Roelofs, Theo A.; Schlag, Peter M.; Stein, Ulrike

    2008-04-01

    Multidrug resistance (MDR) poses a serious barrier to the efficacy of clinical treatment of human cancers with chemotherapeutic drugs. This barrier might be reduced and eventually overcome by the simultaneous application of two or more treatment modalities. This study reports on the synergetic effect of combined application of laser light and cytostatic drugs to induce an improved tumour response in MDR cancer cells. The MDR breast cancer cell line MaTu/ADR, resistant to the drug adriamycin (ADR), was treated with a combination of ADR (125-1000 ng/ml) and laser light (488 nm with a total light dose between 6-18 J/cm2). This combined treatment leads to an additional reduction of the cell vitality by a factor of 2-3 as compared to treatment with ADR alone, suggesting that combined application of laser light and other treatment modalities might constitute a promising strategy for improvements in the tumour response.

  1. Visible light plasmonic heating of Au-ZnO for the catalytic reduction of CO2

    SciTech Connect

    Wang, Congjun; Ranasingha, Oshadha; Natesakhawat, Sittichai; Ohodnicki, Paul R.; Andio, Mark; Lewis, James P.; Matranga, Christopher

    2013-01-01

    Plasmonic excitation of Au nanoparticles attached to the surface of ZnO catalysts using low power 532 nm laser illumination leads to significant heating of the catalyst and the conversion of CO2 and H2 reactants to CH4 and CO products. Temperature-calibrated Raman spectra of ZnO phonons show that intensity-dependent plasmonic excitation can controllably heat Au–ZnO from 30 to ~600 °C and simultaneously tune the CH4 : CO product ratio. The laser induced heating and resulting CH4 : CO product distribution agrees well with predictions from thermodynamic models and temperature-programmed reaction experiments indicating that the reaction is a thermally driven process resulting from the plasmonic heating of the Au-ZnO. The apparent quantum yield for CO2 conversion under continuous wave (cw) 532 nm laser illumination is 0.030%. The Au-ZnO catalysts are robust and remain active after repeated laser exposure and cycling. The light intensity required to initiate CO2 reduction is low ( ~2.5 x 105 W m-2) and achievable with solar concentrators. Our results illustrate the viability of plasmonic heating approaches for CO2 utilization and other practical thermal catalytic applications.

  2. How Monochromatic Is Laser Light?

    ERIC Educational Resources Information Center

    Jacobs, Stephen F.

    1979-01-01

    Presents two derivations of the fundamental laser linewidth that have been used successfully in introductory physics courses. The cause of the finite linewidth is identified with phase fluctuations in the electric field due to spontaneous emissions. A factor of 2 discrepancy between the energy and field analysis is explained. (Author/GA)

  3. Zeeman effect induced by intense laser light.

    PubMed

    Stambulchik, E; Maron, Y

    2014-08-22

    We analyze spectral line shapes of hydrogenlike species subjected to fields of electromagnetic waves. It is shown that the magnetic component of an electromagnetic wave may significantly influence the spectra. In particular, the Zeeman effect induced by a visible or infrared light can be experimentally observed using present-day powerful lasers. In addition, the effect may be used for diagnostics of focused beam intensities achieved at existing and newly built laser facilities. PMID:25192094

  4. Growth and ultraviolet application of Li2B4O7 crystals: Generation of the fourth and fifth harmonics of Nd:Y3Al5O12 lasers

    NASA Astrophysics Data System (ADS)

    Komatsu, R.; Sugawara, T.; Sassa, K.; Sarukura, N.; Liu, Z.; Izumida, S.; Segawa, Y.; Uda, S.; Fukuda, T.; Yamanouchi, K.

    1997-06-01

    A 2 in. diam single crystal of lithium tetraborate (Li2B4O7) was successfully grown by the Czochralski method. The crystal was free from macrodefects and had a dislocation density as low as 100/cm2. It had an excellent homogeneity of the refractive index and a wide transparency down to 170 nm. The optical damage threshold was 40 GW/cm2. Second-harmonic generation and sum frequency generation were investigated in association with the generation of the fourth and fifth harmonics of a Q-switched Nd:YAG laser. The conversion efficiency of the second-harmonic generation from the green (532 nm) light was 20%.

  5. Lasers and Intense Pulsed Light Hidradenitis Suppurativa.

    PubMed

    Saunte, Ditte M; Lapins, Jan

    2016-01-01

    Lasers and intense pulsed light (IPL) treatment are useful for the treatment of hidradenitis suppurativa (HS). Carbon dioxide lasers are used for cutting or vaporization of the affected area. It is a effective therapy for the management of severe and recalcitrant HS with persistent sinus tract and scarring, and can be performed under local anesthesia. HS has a follicular pathogenesis. Lasers and IPL targeting the hair have been found useful in treating HS by reducing the numbers of hairs in areas with HS. The methods have few side effects, but the studies are preliminary and need to be repeated. PMID:26617364

  6. Solution-processed PCDTBT capped low-voltage InGaZnOx thin film phototransistors for visible-light detection

    NASA Astrophysics Data System (ADS)

    Wang, Han; Xiao, Yubin; Chen, Zefeng; Xu, Wangying; Long, Mingzhu; Xu, Jian-Bin

    2015-06-01

    The effects of visible-light detection based on solution processed poly[N-9''-hepta-decanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'benzothiadiazole) (PCDTBT) capped InGaZnOx (IGZO) phototransistors with Al2Ox serving as gate dielectric are investigated in this paper. The high-k dielectric is used to lower the device operating voltage down to 2 V. Photons emitted from laser sources with the wavelengths (λ) of 532 nm and 635 nm are absorbed through the layer of PCDTBT to generate electron-hole-pairs (EHPs). After the separation of EHPs, electrons are injected into IGZO layer through the p-n junction formed between the IGZO (n-type semiconductor) and the PCDTBT (p-type semiconductor). The photo-generated carriers boost the drain current of the transistors as well as bring about the negative threshold voltage shift. Significant enhanced detection performance is achieved under the laser wavelength of 532 nm. The highest photoresponsivity reaches up to 20 A/W, while the photoresponse rise time comes to 10 ms and the fall time comes to approximate 76 ms, which is much faster than trap assisted IGZO visible light detection. The fabricated phototransistors favor the application of visible-light detectors and/or optical switches.

  7. The global light system laser station prototype

    NASA Astrophysics Data System (ADS)

    Hunt, Patrick R.

    We describe the design and fabrication of a prototype Global Light System (GLS) laser station for the JEM-EUSO project. The GLS will consist of a network of ground-based Ultraviolet (UV) light-emitting diodes (LEDs) and steered lasers to monitor and calibrate the cosmic ray detector planned for install on the International Space Station (ISS). The GLS units will generate optical signatures in the atmosphere that are comparable to tracks from cosmic ray extensive air showers (EASs). Unlike an EAS, the number, time, energy, location and direction (for lasers) of GLS events can be specified as JEM-EUSO passes 400 km overhead. Laser tracks from the GLS prototype will be recorded by prototype detectors in ground-to-ground tests. Distant tracks with low angular speed are of particular interest because these are the types of EAS tracks that will be measured by JEM-EUSO. To do these ground-to-ground tests, the prototype detectors will need to measure the laser through the atmosphere at low elevation viewing angles. The beam energy can be adjusted from 1 to 90 mJ to compensate for this additional atmospheric attenuation. The frequency-tripled Nd:YAG laser produces 355 nm (7 ns pulse) light. This wavelength is near the center of the UV EAS fluorescence spectrum. The system is housed in a utility trailer that can be transported by a small truck for domestic campaigns or shipped in an industry standard 20 foot container for global deployment. In operation mode, the laser platform inside the trailer is isolated mechanically to maintain beam pointing accuracy. A retractable two stage steering head can point in any direction above the horizon. A slip ring eliminates cable wrap problems. The GLS prototype will be used to test the EUSO-TA detector and will also be used in preflight tests of the EUSO-balloon payload planned for a super pressure balloon mission.

  8. Direct writing the selective emitter of solar cell with lateral ultrasonic spray laser doping technique

    NASA Astrophysics Data System (ADS)

    Song, Jingwei; Wang, Xuemeng; Gong, Li; Lin, Yanghuan; Gao, Xiaodong; Huang, Jiapei; Shen, Hui

    2015-10-01

    In recent years, laser doping of selective emitters has offered an attractive method to improve the performance of silicon solar cell. A simple laser process is presented for the local doping of crystalline silicon solar cells. Here, the doped line has been direct-written by a 532 nm wavelength laser combined with lateral ultrasonic spray using phosphoric acid. The laser doping selective emitter was quantitatively and spatially measured using Kelvin probe force microscopy under external light illumination. By using the exploited system, we could pattern the dielectric layer while simultaneously doping the underlying silicon to easily achieve the selective emitter (n++) in one processing step. With argon as the conveyance gas, the local melted Si was surrounded by the air-argon gas mixture in the entire process, which caused a decrease in oxygen incorporation.

  9. A Review of Laser Treatment for Symptomatic BPH (Benign Prostatic Hyperplasia).

    PubMed

    Nair, Shiva Madhwan; Pimentel, Marie Adrianne; Gilling, Peter John

    2016-06-01

    Benign prostatic hyperplasia (BPH) is the predominant cause of bladder outflow obstruction and is associated with significant morbidity. Surgical removal of adenoma has been a key treatment principle for alleviation of obstruction. Lasers have been used as an alternative to transurethral resection of the prostate (TURP), due to the higher complications of the latter procedure, since the early 1990s. Early generations of lasers utilized coagulative and ablative techniques to dis-obstruct the bladder. Ablative techniques have remained popular with the resurgence of 532-nm vaporization (commonly known as GreenLight). Enucleation techniques especially with the holmium laser have shown durable efficacy in randomized controlled trials whilst new modalities such as thulium still require long-term data. This review examines the most common types of laser technology used in BPH surgery, with a focus on efficacy and side effect profile. PMID:27053186

  10. OH measurement by laser light absorption

    NASA Technical Reports Server (NTRS)

    Perner, D.

    1986-01-01

    Since the first attempt to measure atmospheric hydroxyl radicals by optical absorption in 1975 (Perner et al., 1976) this method has been continuously developed further and its major obstacles and limitations are known today. The laser beam needs to be expanded in order to reduce the beam divergence. At the same time the energy density of the laser beam which produces OH via ozone photolysis is reduced to such an extent that the self-produced OH concentration ranges well below the atmospheric value. Atmospheric absorptions should be observed over a wide spectral range so that not only the OH radicals are properly identified by several rotational lines but their absorption can be corrected for interfering absorptions from other air constituents as SO2, CH2O, CS2, etc., which can be identified in a wide spectral range with more confidence. Air turbulence demands fast spectral scanning or probing on and off the absorption line. Energy requirements should be kept small in field operations. In the experiment frequency doubled dye laser pulses at 308 nm are produced. The picosecond light pulses are expected to show a smooth profile (light intensity against wavelength) which will be broadened to the required spectral width according to the uncertainty principle. The pump laser will be an optoacoustically modulated Nd:YAG laser.

  11. Power analysis of light source in laser projector

    NASA Astrophysics Data System (ADS)

    Duan, Jingyuan; Shi, Ancun; Zhang, Yunfang; Fang, Qing; Liu, Yuliang

    2012-01-01

    In this paper, we design a high power and small volume laser projector using the red laser diode, green laser diode, blue laser diode and green fluorescence as light source, which could improve the performance of the projector significantly with longer lifetime than lamps, higher reliability, and larger color gamut. According to the requirement of CIE Standard Illuminant D65 and light output, the power of red laser diode, green laser diode, blue laser diode and green fluorescence were calculated. The energy efficiency of four base-color optical path was also analyzed. It could be concluded that the blue laser and red laser have higher power requirements.

  12. New laser serves red light, straight up

    SciTech Connect

    Amato, I.

    1993-05-28

    Researchers have been trying to develop lasers that direct their light up through the top of a chip instead of out the side. But they've had little success in turning such lasers into efficient, practical emitters of the visible light prized for many applications. Now, researchers at Sandia National Laboratories have fashioned tiny surface-emitters that just may pass technological muster. In the 13 May issue of Electronics Letters, Sandia materials scientists Richard Schneider and James A. Lott report a new wrinkle on a technology familiar in the optoelectronics world-that of the so-called vertical cavity surface emitting lasers (VSCELs). To make their VSCEL, the Sandia scientists relied on a fabrication technique known as metalorganic vapor phase epitaxy, which enables them to build up complex multilayered constructions, molecular layer by molecular layer. The light-emitting heart of these constructions is the optical cavity, composed of several 10-nanometer-thick layers of the semiconductor indium-aluminum-gallium-phosphide. The cavity's quantum mechanical properties, which depend partly on the precise thicknesses of its layers, the specific semiconductors used, and the mechanical strain between adjacent layers, turn it into so-called quantum well in which electric charges approaching from the layers above and below it get trapped and recombine to emit red light. Bounding the cavity are complex mirrors made up of alternating sublayers of aluminum arsenide and aluminum gallium arsenide. The mirrors reflect and amplify the emitted light and pave a low resistance pathway into the cavity for electrons and holes - mobile positive charges. The electrical current that drives the laser enters through metal electrodes that are deposited onto the very top and bottom of the multilayered structure.

  13. Threshold measurement of two-photon laser induced photo-polymerization via Z-scan

    NASA Astrophysics Data System (ADS)

    Boiko, Yuri

    2010-02-01

    A technique is suggested to measure a threshold of two-photon initiated photopolymerisation involving Z-scan of a thin film of sensitive material along the focusing axis of the laser beam. The condition of reaching the threshold when gradually increasing the light intensity by moving the film towards the focal spot of the beam is defined as that with minimal intensity at which polymerization occurs. The occurrence of the polymerization is detected by interferometric effect inside the transmitted beam itself, which is due to interference of the wave going through the polymerization area and the wave going around it. The technique is demonstrated for measurements employing Nd:YAG laser in nanosecond regime with fundamental frequency 1064 nm and its harmonic of 532 nm, as well as with pumped by its third harmonic optical parametric oscillator. Threshold data are presented for particular systems, indicating threshold of 5 GW/cm2 for a system based on Rose Bengal exposed by 1064 nm nanosecond-pulsed radiation and 0.05 GW/cm2 for Darocur initiators exposed to 532 nm.

  14. Determination Of The Elements In The Olive Oil Responsible For The Luminescence Spectra Using A Green Laser

    NASA Astrophysics Data System (ADS)

    Fawaz, Saiof; Mahmod, Al-gafary; Lamia, Al-mamouly

    2009-09-01

    In this paper, we were able to record luminescence spectra of olive, sunflower, corn, gourd and laurel oils, chlorophyll and carotene by using an argon laser (488-514 nm) and second harmonic Nd-YAG laser (532 nm) along with a monochromator whose spectral range is 400-900 nm. Only when the luminescence light is vertical to laser light, two new peaks 540 nm and 673 nm have been detected with the latter one is more intense. In discussing our results, we succeeded in determining which materials in olive oil are responsible for producing the luminescence spectral peak; 673 nm. The experimental data has shown that the chlorophyll is the main part of the olive components which gives the olive oil luminescence spectral peak; 673 nm. The other luminescence spectral peak; 540 nm was common to all different kinds of oil in general.

  15. Laser Light Scattering by Shock Waves

    NASA Technical Reports Server (NTRS)

    Panda, J.; Adamovsky, G.

    1995-01-01

    Scattering of coherent light as it propagates parallel to a shock wave, formed in front of a bluff cylindrical body placed in a supersonic stream, is studied experimentally and numerically. Two incident optical fields are considered. First, a large diameter collimated beam is allowed to pass through the shock containing flow. The light intensity distribution in the resultant shadowgraph image, measured by a low light CCD camera, shows well-defined fringes upstream and downstream of the shadow cast by the shock. In the second situation, a narrow laser beam is brought to a grazing incidence on the shock and the scattered light, which appears as a diverging sheet from the point of interaction, is visualized and measured on a screen placed normal to the laser path. Experiments are conducted on shocks formed at various free-stream Mach numbers, M, and total pressures, P(sub 0). It is found that the widths of the shock shadows in a shadowgraph image become independent of M and P(sub 0) when plotted against the jump in the refractive index, (Delta)n, created across the shock. The total scattered light measured from the narrow laser beam and shock interaction also follows the same trend. In the numerical part of the study, the shock is assumed to be a 'phase object', which introduces phase difference between the upstream and downstream propagating parts of the light disturbances. For a given shape and (Delta)n of the bow shock the phase and amplitude modulations are first calculated by ray tracing. The wave front is then propagated to the screen using the Fresnet diffraction equation. The calculated intensity distribution, for both of the incident optical fields, shows good agreement with the experimental data.

  16. High power, picosecond green laser based on a frequency-doubled, all-fiber, narrow-bandwidth, linearly polarized, Yb-doped fiber laser

    NASA Astrophysics Data System (ADS)

    Tian, Wenyan; Isyanova, Yelena; Stegeman, Robert; Huang, Ye; Chieffo, Logan R.; Moulton, Peter F.

    2016-03-01

    We report on the development of an all-fiber, 68-kW-peak-power, 16-ps-pulse-width, narrow-bandwidth, linearly polarized, 1064-nm fiber laser suitable for high-power, picosecond-pulse-width, green-light generation. Our 1064-nm fiber laser delivered an average power of up to 110 W at a repetition of 100- MHz in a narrow bandwidth, with minimal nonlinear distortion. We developed a high-power, picosecond green source at 532 nm through use of single-pass frequency-doubling of our 1064-nm fiber laser in lithium triborate (LBO). Using a 15-mm long LBO crystal, we have generated 30 W of average power in the second harmonic with 73-W of fundamental average power, for a conversion efficiency of 41%.

  17. Laser triggering of water switches in terrawatt-class pulse power accelerators.

    SciTech Connect

    Woodworth, Joseph Ray; Johnson, David Lee (Titan Pulse Sciences, San Leandro, CA); Wilkins, Frank (Bechtel Nevada, Las Vegas, NV); Van De Valde, David (EG&G Technical Services, Albuquerque, NM); Sarkisov, Gennady Sergeevich; Zameroski, Nathan D.; Starbird, Robert L.

    2005-12-01

    Focused Beams from high-power lasers have been used to command trigger gas switches in pulse power accelerators for more than two decades. This Laboratory-Directed Research and Development project was aimed at determining whether high power lasers could also command trigger water switches on high-power accelerators. In initial work, we determined that focused light from three harmonics of a small pulsed Nd:YAG laser at 1064 nm, 532 nm, and 355 nm could be used to form breakdown arcs in water, with the lowest breakdown thresholds of 110 J/cm{sup 2} or 14 GW/cm{sup 2} at 532 nm in the green. In laboratory-scale laser triggering experiments with a 170-kV pulse-charged water switch with a 3-mm anode-cathode gap, we demonstrated that {approx}90 mJ of green laser energy could trigger the gap with a 1-{sigma} jitter of less than 2ns, a factor of 10 improvement over the jitter of the switch in its self breaking mode. In the laboratory-scale experiments we developed optical techniques utilizing polarization rotation of a probe laser beam to measure current in switch channels and electric field enhancements near streamer heads. In the final year of the project, we constructed a pulse-power facility to allow us to test laser triggering of water switches from 0.6- MV to 2.0 MV. Triggering experiments on this facility using an axicon lens for focusing the laser and a switch with a 740 kV self-break voltage produced consistent laser triggering with a {+-} 16-ns 1-{sigma} jitter, a significant improvement over the {+-} 24-ns jitter in the self-breaking mode.

  18. Trimodal detection of early childhood caries using laser light scanning and fluorescence spectroscopy: clinical prototype

    PubMed Central

    Kim, Amy S.; Ridge, Jeremy S.; Nelson, Leonard Y.; Berg, Joel H.; Seibel, Eric J.

    2013-01-01

    Abstract. There is currently a need for a safe and effective way to detect and diagnose early stages of childhood caries. A multimodal optical clinical prototype for diagnosing caries demineralization in vivo has been developed. The device can be used to quickly image and screen for any signs of demineralized enamel by obtaining high-resolution and high-contrast surface images using a 405-nm laser as the illumination source, as well as obtaining autofluorescence and bacterial fluorescence images. When a suspicious region of demineralization is located, the device also performs dual laser fluorescence spectroscopy using 405- and 532-nm laser excitation. An autofluorescence ratio of the two excitation lasers is computed and used to quantitatively diagnose enamel health. The device was tested on five patients in vivo as well as on 28 extracted teeth with clinically diagnosed carious lesions. The device was able to provide detailed images that highlighted the lesions identified by the clinicians. The autofluorescence spectroscopic ratios obtained from the extracted teeth successfully quantitatively discriminated between sound and demineralized enamel. PMID:23986369

  19. 5W intracavity frequency-doubled green laser for laser projection

    NASA Astrophysics Data System (ADS)

    Yan, Boxia; Bi, Yong; Li, Shu; Wang, Dongdong; Wang, Dongzhou; Qi, Yan; Fang, Tao

    2014-11-01

    High power green laser has many applications such as high brightness laser projection and large screen laser theater. A compact and high power green-light source has been developed in diode-pumped solid-state laser based on MgO doped periodically poled LiNbO3 (MgO:PPLN). 5W fiber coupled green laser is achieved by dual path Nd:YVO4/MgO:PPLN intra-cacity frequency-doubled. Single green laser maximum power 2.8W at 532nm is obtained by a 5.5W LD pumped, MgO:PPLN dimensions is 5mm(width)×1mm(thickness)×2mm(length), and the optical to optical conversion efficiency is 51%. The second LD series connected with the one LD, the second path green laser is obtained using the same method. Then the second path light overlap with the first path by the reflection mirrors, then couple into the fiber with a focus mirror. Dual of LD, Nd:YVO4, MgO:PPLN are placed on the same heat sink using a TEC cooling, the operating temperature bandwidth is about 12°C and the stablity is 5% in 96h. A 50×50×17mm3 laser module which generated continuous-wave 5 W green light with high efficiency and width temperature range is demonstrated.

  20. Laser ablation of a turbid medium: Modeling and experimental results

    SciTech Connect

    Brygo, F.; Semerok, A.; Weulersse, J.-M.; Thro, P.-Y.; Oltra, R.

    2006-08-01

    Q-switched Nd:YAG laser ablation of a turbid medium (paint) is studied. The optical properties (absorption coefficient, scattering coefficient, and its anisotropy) of a paint are determined with a multiple scattering model (three-flux model), and from measurements of reflection-transmission of light through thin layers. The energy deposition profiles are calculated at wavelengths of 532 nm and 1.064 {mu}m. They are different from those described by a Lambert-Beer law. In particular, the energy deposition of the laser beam is not maximum on the surface but at some depth inside the medium. The ablated rate was measured for the two wavelengths and compared with the energy deposition profile predicted by the model. This allows us to understand the evolution of the ablated depth with the wavelength: the more the scattering coefficient is higher, the more the ablated depth and the threshold fluence of ablation decrease.

  1. Kinetic Effects of Laser Light on Rubidium

    NASA Astrophysics Data System (ADS)

    Xie, Chuan

    1995-01-01

    In part one of this dissertation, a derivation of the semi-classical kinetic theory of laser-atom interaction for a general multilevel atom is presented, followed by a complete algorithm for the calculation of the force and diffusion as functions of atomic velocity. In contrast to previous numerical methods, the excited states of the atom are not eliminated in this algorithm. Velocity dependent Raman resonances (Ramanons) in a three level Lambda-system are calculated using the general algorithm and physical origin of these resonances is discussed. In part two of the thesis, two novel experiments on the kinetic effects of laser light on rubidium atoms are reported. Transient effects in laser cooling are reported and studied in detail. A semiclassical simulation based on the physical interpretation of these effects agrees well with both the experimental data and results from the quantum calculations, indicating a good understanding of the phenomena. Results of systematic study of a new cooling scheme using a standing wave laser field of two frequencies are presented. In this scheme, sub-Doppler cooling is achieved without either a polarization gradient or a B-field. In addition to cooling and heating, deflection of atoms by a rectified dipole force is observed for certain laser parameters.

  2. Pulsed laser induced birefringence switching in a biopolymer matrix containing azo-dye molecules

    NASA Astrophysics Data System (ADS)

    Mysliwiec, Jaroslaw; Ziemienczuk, Marta; Miniewicz, Andrzej

    2011-07-01

    All optical switching has been studied using the Optical Kerr Effect (OKE) configuration in a biopolymer matrix containing an azo-dye: the Disperse Orange 3 (DO3). The biopolymer system consisted of a deoxyribonucleic acid blended with cationic surfactant molecule cetyltrimethyl-ammonium chloride is suitable for optical quality thin film fabrication. The excitation beams inducing birefringence were delivered from a continuous wave laser at 532 nm and another nanosecond pulsed Nd: YAG laser. The birefringence was instantaneously monitored under crossed polarizer system by a weak non-absorbed light from a cw He-Ne laser working at 632.8 nm. Fast all optical switching process (in the range of microseconds) and excellent reversibility have been observed.

  3. Green laser interferometric metrology system with sub-nanometer periodic nonlinearity.

    PubMed

    Zhao, Shijie; Wei, Haoyun; Zhu, Minhao; Li, Yan

    2016-04-10

    This paper describes the design and realization of a heterodyne laser interferometer system that is applicable to metrology comparison. In this research, an iodine-stabilized Nd:YAG laser at 532 nm served as the light source. Two spatially separated beams with different offset frequencies are generated by two acousto-optic modulators to prevent any source mixing and polarization leakage. The interferometry components are integrated to a monolithic prism to reduce the difficulty of the light path adjustment and to guarantee the measuring accuracy. The experimental results show there is a sub-nanometer periodic nonlinearity, which mainly results from the ghost reflection. Placed in a vacuum chamber, the interferometer is applicable for measuring comparison using a piezo nanopositioner and a precision translation stage. Finally, a commercial interferometer is calibrated with the interferometer system. PMID:27139867

  4. Effect of frequency-doubling pulse Nd:YAG laser on microbial mutation

    NASA Astrophysics Data System (ADS)

    Zhao, Yansheng; Wang, Luyan; Zheng, Heng; Yin, Hongping; Chen, Xiangdong; Tan, Zheng; Wu, Wutong

    1999-09-01

    We are going to report the mutagenic effect of frequency-doubling pulse Nd:YAG laser (532 nm) on microbe. After irradiation with pulse laser, mutants of abscisic acid producing strains and erythromycin producing strains were obtained, one of which could produce 62.1% and 57% more products than control, respectively. In the study of mutagenization of Spirulina platensis caused by pulse laser, we selected a high photosynthetic strains, with improved productivity of protein and exocellular ploysaccharides of 12% and 246%, respectively. The experimental results indicate that frequency-doubling pulse laser (532 nm) is a potential new type of physical mutagenic factor.

  5. Light emission: A temperature-tunable random laser

    NASA Astrophysics Data System (ADS)

    Wiersma, Diederik S.; Cavalieri, Stefano

    2001-12-01

    Random lasers have fascinating emission properties that lie somewhere between those of a conventional laser and a common light-bulb. We have created a random laser that can be brought above and below its threshold for laser emission by small changes in its temperature, thereby creating a light source with a temperature-tunable colour spectrum. As a single random laser can be made as small as a grain of tens of micrometres in diameter, we expect our device to find application in photonics, temperature-sensitive displays and screens, and in remote temperature sensing.Lasers are now commonplace - for example, they are used in industry and in hospitals, in bar-code scanners and compact-disc players. Conventional lasers are based on an optically active material and some sort of laser cavity that traps light for long enough for laser action to occur. A new type of laser source, known as a random laser, has been discovered that does not require a regular cavity but instead depends on a diffusive material such as a fine powder. In a random laser, light waves are trapped by multiple light scattering (that is, light diffusion), which takes over the role of the cavity in a regular laser (Fig. 1). The emission of a random-laser source has a well defined colour spectrum and can be pulsed, just like a regular laser, although its emission is in several directions because of the intrinsic randomness of the system.

  6. Near Infrared (NIR) Imaging Techniques Using Lasers and Nonlinear Crystal Optical Parametric Oscillator/Amplifier (OPO/OPA) Imaging and Transferred Electron (TE) Photocathode Image Intensifiers

    SciTech Connect

    YATES,GEORGE J.; MCDONALD,THOMAS E. JR.; BLISS,DAVID E.; CAMERON,STEWART M.; GREIVES,KENNETH H.; ZUTAVERN,FRED J.

    2000-12-20

    Laboratory experiments utilizing different near-infrared (NIR) sensitive imaging techniques for LADAR range gated imaging at eye-safe wavelengths are presented. An OPO/OPA configuration incorporating a nonlinear crystal for wavelength conversion of 1.56 micron probe or broadcast laser light to 807 nm light by utilizing a second pump laser at 532 nm for gating and gain, was evaluated for sensitivity, resolution, and general image quality. These data are presented with similar test results obtained from an image intensifier based upon a transferred electron (TE) photocathode with high quantum efficiency (QE) in the 1-2 micron range, with a P-20 phosphor output screen. Data presented include range-gated imaging performance in a cloud chamber with varying optical attenuation of laser reflectance images.

  7. Threshold Characteristics of Slow-Light Photonic Crystal Lasers

    NASA Astrophysics Data System (ADS)

    Xue, Weiqi; Yu, Yi; Ottaviano, Luisa; Chen, Yaohui; Semenova, Elizaveta; Yvind, Kresten; Mork, Jesper

    2016-02-01

    The threshold properties of photonic crystal quantum dot lasers operating in the slow-light regime are investigated experimentally and theoretically. Measurements show that, in contrast to conventional lasers, the threshold gain attains a minimum value for a specific cavity length. The experimental results are explained by an analytical theory for the laser threshold that takes into account the effects of slow light and random disorder due to unavoidable fabrication imperfections. Longer lasers are found to operate deeper into the slow-light region, leading to a trade-off between slow-light induced reduction of the mirror loss and slow-light enhancement of disorder-induced losses.

  8. Threshold Characteristics of Slow-Light Photonic Crystal Lasers.

    PubMed

    Xue, Weiqi; Yu, Yi; Ottaviano, Luisa; Chen, Yaohui; Semenova, Elizaveta; Yvind, Kresten; Mork, Jesper

    2016-02-12

    The threshold properties of photonic crystal quantum dot lasers operating in the slow-light regime are investigated experimentally and theoretically. Measurements show that, in contrast to conventional lasers, the threshold gain attains a minimum value for a specific cavity length. The experimental results are explained by an analytical theory for the laser threshold that takes into account the effects of slow light and random disorder due to unavoidable fabrication imperfections. Longer lasers are found to operate deeper into the slow-light region, leading to a trade-off between slow-light induced reduction of the mirror loss and slow-light enhancement of disorder-induced losses. PMID:26918991

  9. Generating A Strobed Laser Light Sheet

    NASA Technical Reports Server (NTRS)

    Leighty, Bradley D.; Franke, John M.; Rhodes, David B.; Jones, Stephen B.

    1994-01-01

    An optoelectronic system generating synchronous, strobed sheet of laser light developed for use in making visible flow of air about model helicopter rotor. Used in wind-tunnel tests to determine actual locations of vortices for comparison with locations predicted by mathematical models to validate models. Each blade tip produces vortex. By establishing successive vortex locations, researcher determines trajectory of vortex pattern. Light-sheet strobe circuits provide selection of blade positions, strobe-pulse durations, and multiple pulses per revolution for rotors having two to nine blades. To make flow visible, vaporizing propylene glycol injected upstream of model. System also provides calibrated trigger delay of strobe pulses, adjustable strobe-pulse durations, selectable number of blades, and slip-sync mode to make flow visible as though in slow motion.

  10. Surface nano-texturing of silicon by picosecond laser irradiation through TiO2 nanotube arrays

    NASA Astrophysics Data System (ADS)

    Babu, K. E. Sarath Raghavendra; Duraiselvam, Muthukannan

    2015-10-01

    This article presents, nano-texturing of crystalline silicon by irradiating picosecond laser with variable spatial intensity, caused by optically non-linear TiO2 nanotube arrays (TNTA). Along with micro-scale surface structure, highly ordered laser-induced periodic surface structures (LIPSS) was observed at nano-scale. The periodicity (Λ) of the LIPSS generated was near to the laser wavelength (532 nm). Surface morphology at micro-level was characterized by optical microscopy (OM) and white light interferometer (WLI) and at the nano-scale by scanning electron microscope (SEM) and atomic force microscope (AFM). The results highlight the potential use of TNTA as a single step process to produce micro/nanostructures without any gas/liquid medium under ambient condition.

  11. Temperature dependence of nanosecond laser pulse thresholds of melanosome and microsphere microcavitation

    NASA Astrophysics Data System (ADS)

    Schmidt, Morgan S.; Kennedy, Paul K.; Noojin, Gary D.; Thomas, Robert J.; Rockwell, Benjamin A.

    2016-01-01

    Melanosome microcavitation is the threshold-level retinal pigment epithelium (RPE) damage mechanism for nanosecond (ns) pulse exposures in the visible and near-infrared (NIR). Thresholds for microcavitation of isolated bovine RPE melanosomes were determined as a function of temperature (20 to 85°C) using single ns laser pulses at 532 and 1064 nm. Melanosomes were irradiated using a 1064-nm Q-switched Nd:YAG (doubled for 532-nm irradiation). For comparison to melanosome data, a similar temperature (20 to 65°C) dependence study was also performed for 532 nm, ns pulse exposures of black polystyrene microbeads. Results indicated a decrease in the microcavitation average radiant exposure threshold with increasing sample temperature for both 532- and 1064-nm single pulse exposures of melanosomes and microbeads. Threshold data and extrapolated nucleation temperatures were used to estimate melanosome absorption coefficients in the visible and NIR, and microbead absorption coefficients in the visible, indicating that melanin is a better absorber of visible light than black polystyrene. The NIR melanosome absorption coefficients ranged from 3713 cm-1 at 800 nm to 222 cm-1 at 1319 nm. These data represent the first temperature-dependent melanosome microcavitation study in the NIR and provide additional information for understanding melanosome microcavitation threshold dependence on wavelength and ambient temperature.

  12. Lasers.

    ERIC Educational Resources Information Center

    Schewe, Phillip F.

    1981-01-01

    Examines the nature of laser light. Topics include: (1) production and characteristics of laser light; (2) nine types of lasers; (3) five laser techniques including holography; (4) laser spectroscopy; and (5) laser fusion and other applications. (SK)

  13. Small bore ceramic laser tube inspection light table

    DOEpatents

    Updike, Earl O.

    1990-01-01

    Apparatus for inspecting small bore ceramic laser tubes, which includes a support base with one or more support rollers. A fluorescent light tube is inserted within the laser tube and the laser tube is supported by the support rollers so that a gap is maintained between the laser tube and the fluorescent tube to enable rotation of the laser tube. In operation, the ceramic tube is illuminated from the inside by the fluorescent tube to facilitate visual inspection. Centering the tube around the axial light of the fluorescent tube provides information about straightness and wall thickness of the laser tube itself.

  14. Two-mirrored galvanometer laser light sheet generator

    NASA Technical Reports Server (NTRS)

    Leighty, B. D.; Franke, J. M.; Jones, S. B.; Rhodes, D. B.

    1988-01-01

    Light sheets generated with either laser or noncoherent sources have found widespread application to flow visualization. Previous light sheet generating systems were usually dedicated to a specific viewing geometry. The technique with the most flexibility is the galvanometer mirror based laser light sheet system. A two-mirrored system was designed and developed to provide flexibility and adaptability to a wide range of applications. The design includes the capability to control the size and location of the laser light sheet in real time, to generate horizontal or vertical sheets, to sweep the sheet repeatedly through a volume, to generate multiple sheets with controllable separation and to rotate single or multiple laser light sheets. The system is capable of producing up to 12 sheets of laser light at an angular divergence of + or - 20 degrees. Maximum scan rate of any one line is 500 Hertz. This system has proven to be uniquely versatile and a patent has been applied for.

  15. Laser light scattering in eye lens model

    NASA Astrophysics Data System (ADS)

    Larionova, Nadezhda L.; Maksimova, Irina L.; Kochubey, Vyacheslav I.

    2000-11-01

    Theoretical investigations of laser light radiation scattered by eye lens model as a system of spheres with various parameters were performed on the base of Mie theory of electromagnetic scattering by a single sphere. The calculations were performed for systems of particles whose coordinates were specifically realized in random fashion according to the specified probabilities defined by the approximation of hard spheres. The modeling of lens biotissue was carried out by using of medical data about internal structure of lens of human and some animals. In general the researchable model presents the system of homogeneous spherical particles those are randomly distributed in the layer of thickness. We study the optical properties such as scattering effective cross-section and function of correlation in different models.

  16. Improved optics for laser light scattering

    NASA Technical Reports Server (NTRS)

    Cheung, H. Michael

    1989-01-01

    Laser light scattering experiments contemplated for use in a microgravity environment must conform to a number of operational constraints which do not apply on Earth. In particular, the use of index matching fluid to control flare is unacceptable. Work to eliminate index matching fluids by the use of high spatial resolution receiving optics is described. By increasing on-axis spatial resolution flare from the sample cell walls (both the cell sample and cell air interfaces) can be effectively prevented from reaching the photodetector. In general, improving the on-axis discrimination degrades the angular resolution of a receiving optical train. Several different possible configurations of receiving optics are compared for their spatial resolution and angular resolution. For cylinder symmetric optics, the dual lens, fourier transform pair, receiving train with a center mask located between the lenses gives the best on-axis spatial resolution.

  17. Airborne Polarimetric, Two-Color Laser Altimeter Measurements of Lake Ice Cover: A Pathfinder for NASA's ICESat-2 Spaceflight Mission

    NASA Technical Reports Server (NTRS)

    Harding, David; Dabney, Philip; Valett, Susan; Yu, Anthony; Vasilyev, Aleksey; Kelly, April

    2011-01-01

    The ICESat-2 mission will continue NASA's spaceflight laser altimeter measurements of ice sheets, sea ice and vegetation using a new measurement approach: micropulse, single photon ranging at 532 nm. Differential penetration of green laser energy into snow, ice and water could introduce errors in sea ice freeboard determination used for estimation of ice thickness. Laser pulse scattering from these surface types, and resulting range biasing due to pulse broadening, is assessed using SIMPL airborne data acquired over icecovered Lake Erie. SIMPL acquires polarimetric lidar measurements at 1064 and 532 nm using the micropulse, single photon ranging measurement approach.

  18. Diffuse Reflection of Laser Light From Clouds

    NASA Technical Reports Server (NTRS)

    Cahalan, R. F.; Davis, A.; McGill, M.

    1999-01-01

    Laser light reflected from an aqueous suspension of particles or "cloud" with known thickness and particle size distribution defines the "cloud radiative Green's function", G. G is sensitive to cloud thickness, allowing retrieval of that important quantity. We describe a laboratory simulation of G, useful in design of an offbeam Lidar instrument for remote sensing of cloud thickness. Clouds of polystyrene microspheres suspended in water are analogous to real clouds of water droplets suspended in air. The size distribution extends from 0.5 microns to 25 microns, roughly lognormal, similar to real clouds. Density of suspended spheres is adjusted so photon mean-free-path is about 10 cm, 1000 times smaller than in real clouds. The light source is a Nd:YAG laser at 530 nm. Detectors are flux and photon-counting PMTs, with a glass probe for precise positioning. A Labview 5 VI controls position and data acquisition, via an NI Motion Control board connected to a stepper motor driving an Edmund linear slider,and a 16-channel 16-bit NI-DAQ board. The stepper motor is accurate to 10 microns. Step size is selectable. Far from the beam, the rate of exponential increase in the beam direction scales as expected from diffusion theory, linearly with cloud thickness, and inversely as the square root of the reduced optical thickness, independent of particle size. Nearer the beam the signal increases faster than exponential and depends on particle size. Results verify 3D Monte Carlo simulations that demonstrate detectability of remotely sensed offbeam returns, without filters at night, with narrow bandpass filter in day.

  19. NASA Laser Light Scattering Advanced Technology Development Workshop, 1988

    NASA Technical Reports Server (NTRS)

    Meyer, William V. (Editor)

    1989-01-01

    The major objective of the workshop was to explore the capabilities of existing and prospective laser light scattering hardware and to assess user requirements and needs for a laser light scattering instrument in a reduced gravity environment. The workshop addressed experimental needs and stressed hardware development.

  20. Twin-Mirrored-Galvanometer Laser-Light-Sheet Generator

    NASA Technical Reports Server (NTRS)

    Rhodes, David B.; Franke, John M.; Jones, Stephen B.; Leighty, Bradley D.

    1991-01-01

    Multiple, rotating laser-light sheets generated to illuminate flows in wind tunnels. Designed and developed to provide flexibility and adaptability to wide range of applications. Design includes capability to control size and location of laser-light sheet in real time, to generate horizontal or vertical sheets, to sweep sheet repeatedly through volume, to generate multiple sheets with controllable separation, and to rotate single or multiple laser-light sheets. Includes electronic equipment and laser mounted on adjustable-height platform. Twin-mirrored galvanometer unit supported by tripod to reduce vibration. Other possible applications include use in construction industry to align beams of building. Artistic or display applications also possible.

  1. Light pollution generated by laser guide star at Canarian Observatories

    NASA Astrophysics Data System (ADS)

    Chueca, Sergio; Fuensalida, Jesus J.

    2004-11-01

    A new generation of instrument using a launching laser is been developed to correct the atmospheric image blurring and to establish optical communication with space. Then, light pollution generated by laser will be a serious operational problem in next years. This laser could affect astronomical works of adjacent telescopes when the laser lay across the field of view of the observing telescope, this is a kind of light pollution. This could be avoided with an adequate operational politic to detect possible interference between the laser and the astronomical telescopes. In this paper is analysed the mathematical probability of a cross-event happen.

  2. Hybrid proton acceleration scheme using relativistic intense laser light

    SciTech Connect

    Andreev, A. A.; Platonov, K. Yu.; Schnuerer, M.; Prasad, R.; Ter-Avetisyan, S.

    2013-03-15

    Ion acceleration phenomena at relativistic intense laser interaction with thin foil targets are studied to find an efficient laser-target interaction concept at the conditions, where neither the ponderomotive pressure of the laser light nor the hot electron pressure is negligible. Particle in cell simulations and the analytical model are allowing to predict optimum laser-target parameters and suggesting a significant increase of proton energy if a hybrid proton acceleration scheme is used. In the proposed scenario, the laser polarisation is changed during the acceleration process: First with circularly polarised laser light the target is accelerated as a whole by the ponderamotive pressure, and then with linearly polarised laser light the electrons are heated which additionally increases the accelerating field. The calculations are in good agreement with experimental findings.

  3. Laser microfluidics: fluid actuation by light

    NASA Astrophysics Data System (ADS)

    Delville, Jean-Pierre; de Saint Vincent, Matthieu Robert; Schroll, Robert D.; Chraïbi, Hamza; Issenmann, Bruno; Wunenburger, Régis; Lasseux, Didier; Zhang, Wendy W.; Brasselet, Etienne

    2009-03-01

    The development of microfluidic devices is still hindered by the lack of robust fundamental building blocks that constitute any fluidic system. An attractive approach is optical actuation because light field interaction is contactless and dynamically reconfigurable, and solutions have been anticipated through the use of optical forces to manipulate microparticles in flows. Following the concept of an 'optical chip' advanced from the optical actuation of suspensions, we propose in this survey new routes to extend this concept to microfluidic two-phase flows. First, we investigate the destabilization of fluid interfaces by the optical radiation pressure and the formation of liquid jets. We analyze the droplet shedding from the jet tip and the continuous transport in laser-sustained liquid channels. In the second part, we investigate a dissipative light-flow interaction mechanism consisting in heating locally two immiscible fluids to produce thermocapillary stresses along their interface. This opto-capillary coupling is implemented in adequate microchannel geometries to manipulate two-phase flows and propose a contactless optical toolbox including valves, droplet sorters and switches, droplet dividers or droplet mergers. Finally, we discuss radiation pressure and opto-capillary effects in the context of the 'optical chip' where flows, channels and operating functions would all be performed optically on the same device.

  4. 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.

  5. Single Frequency Monolithic Solid State Green Laser as a Potential Source for Vibrometry Systems

    SciTech Connect

    Sotor, Jaroslaw Z.; Antonczak, Arkadiusz J.; Abramski, Krzysztof M.

    2010-05-28

    In this paper miniature, monolithic single frequency solid state laser operating at 532 nm is presented. Developed Nd:GdVO{sub 4}/YVO{sub 4}/KTP consist of three crystal bonded together with a UV adhesive. The single frequency operation was obtained in wide temperature range from 17 deg. C to 27 deg. C. The laser operated with output power up to 90 mW at 532 nm. The total optical efficiency (808 nm to 532 nm) was 9.5%. Power stability was at the level of +-0.8% and the long term frequency stability was approximately 3centre dot10{sup -8}. The beam has a Gaussian profile and the M2 parameter was below 1.1.

  6. Improved beam profile of a 266 nm deep ultraviolet laser employing a multi-mirror-reflected cavity

    NASA Astrophysics Data System (ADS)

    Yang, Houwen; Cheng, Wenyong; Wang, Junhua; Zhang, Yaguang; Wang, Xiaoqian; Zhang, Lijie

    2016-04-01

    A 266 nm deep ultraviolet (DUV) laser with a good Gaussian profile is reported employing a multi-mirror-reflected cavity. A type-I LiB3O5 (LBO) crystal is used to double the fundamental-light (1064 nm) wavelength generated by an actively Q-switched Nd:YVO4 laser with an intra-cavity configuration. A fourth harmonic generation (FHG) wavelength is obtained by a type-I β-BaB2O4 (BBO) crystal. The output power as high as 440 mW at 266 nm is generated under an incident power of 2.26 W at 532 nm, corresponding to the conversion efficiency of 532 nm-266 nm up to 19.5% with a repetition rate of 15 kHz and the pulse duration of 266 nm is 10.7 ns.

  7. Light pressure acceleration with frequency-tripled laser pulse

    SciTech Connect

    Wang, Xiaofeng; Shen, Baifei E-mail: zhxm@siom.ac.cn; Zhang, Xiaomei E-mail: zhxm@siom.ac.cn; Ji, Liangliang; Wang, Wenpeng; Zhao, Xueyan; Xu, Jiancai; Yu, Yahong; Yi, Longqing; Shi, Yin; Xu, Tongjun; Zhang, Lingang

    2014-08-15

    Light pressure acceleration of ions in the interaction of the frequency-tripled (3ω) laser pulse and foil target is studied, and a promising method to increase accelerated ion energy is shown. Results show that at a constant laser energy, much higher ion energy peak value is obtained for 3ω laser compared with that using the fundamental frequency laser. The effect of energy loss during frequency conversion on ion acceleration is considered, which may slightly decrease the acceleration effect.

  8. ARGOS laser system mechanical design

    NASA Astrophysics Data System (ADS)

    Deysenroth, M.; Honsberg, M.; Gemperlein, H.; Ziegleder, J.; Raab, W.; Rabien, S.; Barl, L.; Gässler, W.; Borelli, J. L.

    2014-07-01

    ARGOS, a multi-star adaptive optics system is designed for the wide-field imager and multi-object spectrograph LUCI on the LBT (Large Binocular Telescope). Based on Rayleigh scattering the laser constellation images 3 artificial stars (at 532 nm) per each of the 2 eyes of the LBT, focused at a height of 12 km (Ground Layer Adaptive Optics). The stars are nominally positioned on a circle 2' in radius, but each star can be moved by up to 0.5' in any direction. For all of these needs are following main subsystems necessary: 1. A laser system with its 3 Lasers (Nd:YAG ~18W each) for delivering strong collimated light as for LGS indispensable. 2. The Launch system to project 3 beams per main mirror as a 40 cm telescope to the sky. 3. The Wave Front Sensor with a dichroic mirror. 4. The dichroic mirror unit to grab and interpret the data. 5. A Calibration Unit to adjust the system independently also during day time. 6. Racks + platforms for the WFS units. 7. Platforms and ladders for a secure access. This paper should mainly demonstrate how the ARGOS Laser System is configured and designed to support all other systems.

  9. GreenLight 180W XPS photovaporization of the prostate: how I do it.

    PubMed

    Zorn, Kevin C; Liberman, Daniel

    2011-10-01

    Transurethral resection of the prostate (TURP) is the most common surgical intervention for benign prostatic hyperplasia (BPH), largely due to lower urinary tract symptoms refractory to medical therapy. TURP remains the gold standard for men with prostates sized 30g-80g, while open prostatectomy has been the preferred option for men with glands larger than 80g-100 g and those with other lower urinary tract anomalies such as large bladder stones or bladder diverticula. Unfortunately, these procedures have complications including bleeding (often requiring transfusion in 7%-13% of cases), electrolyte abnormalities (2% TURP syndrome), erectile dysfunction (6%-10%), and retrograde ejaculation (50%-75%). The overall incidence of a second intervention (repeat TURP, urethrotomy and bladder neck incision) has been reported in 12% and 15% of men at 5 and 10 years following TURP. Alternative therapies have been developed with the aim of reducing the level of complications while maintaining efficacy. These include microwave therapy, transurethral needle ablation, and a range of laser procedures (Holmium, Diode, Thulium and 532nm-Greenlight). Photoselective vaporization of the prostate (PVP), initially launched as a 60W prototype, was ultimately introduced to the urology community as a 80W system (American Medical Systems, Minnetonka, Minnesota, USA), has been the predominant device used in clinical trials. This 1st generation used an Nd:YAG laser beam passed through a potassium-titanyl-phosphate (KTP) crystal, halving the wavelength (to 532nm), doubling the laser's frequency, and resulting in a green light. Outcomes have demonstrated a reduced frequency and severity of clinical complications, however it was limited to smaller prostate sizes. In 2006, the 120W lithium triborate laser (LBO), also known as the GreenLight HPS (High Performance System) laser was introduced. This laser utilizes a diode pumped Nd:YAG laser light that is emitted through an LBO instead of a KTP crystal

  10. Reflection of femtosecond laser light in multipulse ablation of metals

    SciTech Connect

    Vorobyev, A. Y.; Guo Chunlei

    2011-08-15

    The shot-to-shot reflectance of high-intensity laser light is studied as a function of both the number of laser shots and laser fluence in multipulse ablation of a metal when the irradiated surface undergoes structural changes from an initially smooth surface to a deep crater. Our study shows that the reflectance of the irradiated surface significantly decreases due to the high intensity of laser pulses and the laser-induced surface structures in ablation regimes typically used for femtosecond laser processing of materials. The high-intensity effect dominates in the reflection reduction at low numbers of laser shots when laser-induced surface structures do not cause the reflectance to decrease noticeably. With increasing the number of laser shots, the structural effect comes into play, and both high-intensity and structural effects quickly reduce the reflectance of the sample to a low value.

  11. Structure light with laser speckle for object contour reconstruction

    NASA Astrophysics Data System (ADS)

    Hua, Ting-Xuan; Chen, Cheng-Huan; Tsai, Augustine; Liu, Wen-Kai

    2012-02-01

    Invisible grid-pattern structure light has often been used for being shined on objects for contour reconstruction based on the distortion of grid pattern, for vehicle collision prevention etc. However, the structure light can be easily disturbed by surrounding nature light even if infra-red (IR) light source is used because natural light contains quite an amount of IR spectrum. In this paper, it is proposed that the structure light is provided from a highly coherent laser source, so that the structure light pattern reflected from the target object will contain not only the distorted irradiance distribution of grid pattern, but also laser speckle associated with it. The laser speckle pattern depends on the surface roughness of the target object, which provides extra information for extracting the distorted grid pattern from the background irradiance of surrounding natural light. The laser speckle pattern therefore helps to improve the immunity for surrounding light disturbance, and hence the robustness and reliability of contour reconstruction system. A binary surface relief phase-type diffractive optical element(DOE) has been proposed for generating desired pattern directly at far field when working together with laser light source. The design process is based on iterative Fourier transform algorithm(IFTA) in scalar diffraction theory.

  12. Practice and Educational Gaps in Light, Laser, and Energy Treatments.

    PubMed

    Alam, Murad; Waldman, Abigail; Nouri, Keyvan; Council, M Laurin; Cartee, Todd V

    2016-07-01

    This article discusses current practice in laser dermatology, the gaps in practice, and recommendations for improvement. As is the case with other areas of cosmetic dermatology, there is a rapid development of new laser and light devices with limited epidemiologic data available to inform best practice. The high fixed cost associated with new laser devices, limited space available in some practices, and inconsistent training may limit the adoption of needed therapies. Improving research in this area; training opportunities for physicians, residents, and staff; and cost-effective laser/light device rentals programs could improve quality of current practice. PMID:27363892

  13. Laser wakefield accelerator based light sources: potential applications and requirements

    SciTech Connect

    Albert, F.; Thomas, A. G.; Mangles, S. P.D.; Banerjee, S.; Corde, S.; Flacco, A.; Litos, M.; Neely, D.; Viera, J.; Najmudin, Z.; Bingham, R.; Joshi, C.; Katsouleas, T.

    2015-01-15

    In this article we review the prospects of laser wakefield accelerators as next generation light sources for applications. This work arose as a result of discussions held at the 2013 Laser Plasma Accelerators Workshop. X-ray phase contrast imaging, X-ray absorption spectroscopy, and nuclear resonance fluorescence are highlighted as potential applications for laser-plasma based light sources. We discuss ongoing and future efforts to improve the properties of radiation from plasma betatron emission and Compton scattering using laser wakefield accelerators for these specific applications.

  14. LIGHT SOURCE: TW Laser system for Thomson scattering X-ray light source at Tsinghua University

    NASA Astrophysics Data System (ADS)

    Yan, Li-Xm; Du, Ying-Chao; Du, Qiang; Li, Ren-Kai; Hua, Jian-Fei; Huang, Wen-Hui; Tang, Chuan-Xiang

    2009-06-01

    A TW (Tera Watt) laser system based on Ti:sapphire mainly for the Tsinghua Thomson scattering X-ray light source (TTX) is being built. Both UV (ultraviolet) laser pulse for driving the photocathode radio-frequency (RF) gun and the IR (infrared) laser pulse as the electron-beam-scattered-light are provided by the system. Efforts have also been made in laser pulse shaping and laser beam transport to optimize the high-brightness electron beam production by the photocathode RF gun.

  15. Remote sensing of foliar biochemistry with a terrestrial laser scanner

    NASA Astrophysics Data System (ADS)

    Eitel, J.; Vierling, L. A.; Long, D. S.

    2011-12-01

    Foliar biochemistry provides important information about the physiological status of plants. Several different tools and techniques have been developed to infer plant biochemistry (such as state and change of foliar nitrogen (N) and chlorophyll) using remote sensing. However, few techniques allow accurate mapping of foliar biochemistry in 3-dimensions at a sub-cm level. Scanning laser technology is available that measures the x,y,z location of each reflected laser pulse in addition to the intensity of the reflected laser light within a mm-scale ground instantaneous field of view at a very high sampling rate (up to 50,000 points sec-1 in this study). We examined the ability to quantify foliar N of spring wheat (Triticum aestivum L.) and chlorophyll content of two broadleaf tree species saplings (Quercus macrocarpa and Acer saccharum) using a green (532 nm) terrestrial laser scanner. The return intensity of the reflected green laser light was significantly correlated with foliar N concentration of wheat (r2 = 0.68) and the foliar chlorophyll content (r2 = 0.77) of the broadleaf saplings. The results indicate that laser scanners are useful to obtain spatially explicit estimates of foliar biochemistry.

  16. Polymer-based lab-on-a-chip lasers

    NASA Astrophysics Data System (ADS)

    Kristensen, A.; Balslev, S.; Bilenberg, B.; Gersborg-Hansen, M.; Nilsson, D.

    2004-12-01

    The integration of optical transducers is generally considered a key issue in the further development of lab-on-a-chip Microsystems. We present a technology for miniaturized, polymer based lasers, suitable for integration with planar waveguides and microfluidic networks. The lasers rely on the commercial laser dye Rhodamine 6G as active medium, and the laser resonator is defined in a thin film of polymer on a low refractive index substrate. Two types of devices are demonstrated: solid and microfluidic polymer based dye lasers. In the microfluidic dye lasers, the laser dye is dissolved in a suitable solvent and flushed though a microfluidic channel, which has the laser resonator embedded. For solid state dye lasers, the laser dye is dissolved in the polymer forming the laser resonator. The miniaturized dye lasers are optically pumped by a frequency doubled, pulsed Nd:YAG laser (at 532 nm), and emit at wavelengths between 560 nm and 590 nm. The lasers emit in the plane of the chip, and the emitted light is coupled into planar polymer waveguides on the chip. The feasibility of three types of polymers is demonstrated: SU-8, PMMA and a cyclo-olefin co-polymer (COC) - Topas. SU-8 is a negative tone photoresist, allowing patterning with conventional UV lithography. PMMA and Topas are thermoplasts, which are patterned by nanoimprint lithography (NIL). The lasing wavelength of the microfluidic dye lasers can be coarse tuned over 30 nm by varying the concentration of laser dye, and fine tuned by varying the refractive index of the solvent. This is utilized to realize a tunable laser, by on-chip mixing of dye, and two solvents of different index of refraction. The lasers were also integrated with waveguides and microfluidic networks.

  17. Picoseconds-Laser Modification of Thin Films

    SciTech Connect

    Gakovic, Biljana; Trtica, Milan; Batani, Dimitri; Desai, Tara; Redaelli, Renato

    2006-04-07

    The interaction of a Nd:YAG laser, pulse duration of 40 ps, with a titanium nitride (TiN) and tungsten-titanium (W-Ti) thin films deposited at silicon was studied. The peak intensity on targets was up to 1012 W/cm2. Results have shown that the TiN surface was modified, by the laser beam, with energy density of {>=}0.18 J/cm2 ({lambda}laser= 532 nm) as well as of 30.0 J/cm2 ({lambda}laser= 1064 nm). The W-Ti was surface modified with energy density of 5.0 J/cm2 ({lambda}laser= 532 nm). The energy absorbed from the Nd:YAG laser beam is partially converted to thermal energy, which generates a series of effects such as melting, vaporization of molten materials, dissociation and ionization of the vaporized material, appearance of plasma, etc. The following morphological changes of both targets were observed: (i) The appearance of periodic microstructures, in the central zone of the irradiated area, for laser irradiation at 532 nm. Accumulation of great number of laser pulses caused film ablation and silicon modification. (ii) Hole formation on the titanium nitride/silicon target was registered at 1064 nm. The process of the Nd:YAG laser interaction with both targets was accompanied by plasma formation above the target.

  18. Photo-dissociation quantum yields of mammalian oxyhemoglobin investigated by a nanosecond laser technique

    SciTech Connect

    Yang Ningli; Zhang Shuyi . E-mail: zhangsy@nju.edu.cn; Kuo Paokuang; Qu Min; Fang Jianwen; Li Jiahuang; Hua Zichun

    2007-02-23

    The photo-dissociations of oxyhemoglobin of several mammals, such as human, bovine, pig, horse, and rabbit, have been studied. By means of optical pump-probe technique, the quantum yields for photo-dissociation of these oxyhemoglobin have been determined at pH 7 and 20 {sup o}C. A nanosecond laser at 532 nm is used as the pumping source, and a xenon lamp through a monochrometer provides a probe light at 432 nm. The experimental results show that the quantum yields of these mammalian oxyhemoglobin are different from each other, especially for that of rabbit. By analyzing the amino acid sequences and tetramer structures as well as the flexibility and hydrophobicity of the different hemoglobin, possible explanations for the differences are proposed.

  19. Interferometer combines laser light source and digital counting system

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Measurement of small linear displacements in digital readouts with extreme accuracy and sensitivity is achieved by an interferometer. The instrument combines a digital electro-optical fringe-counting system and a laser light source.

  20. Proton displacement damage in light-emitting and laser diodes

    NASA Technical Reports Server (NTRS)

    Johnston, A. H.

    2000-01-01

    The effects of proton displacement damage on light-emitting diodes and laser diodes are discussed, comparing the radiation sensitivity of current technology devices with older devices for which data exists in the literature.

  1. Diffusion filter eliminates fringe effects of coherent laser light source

    NASA Technical Reports Server (NTRS)

    Olsasky, M. J.

    1970-01-01

    Diffusion filter comprised of small particles in colloidal suspension reduces the coherence of a laser beam used as a photographic light source. Interference patterns which obscure details in photographic film are eliminated, the intensity and collimation are moderately affected.

  2. 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.

  3. Research of time fiducial and imaging VISAR laser for Shenguang-III laser facility

    NASA Astrophysics Data System (ADS)

    Zhang, Rui; Wang, Zhenguo; Tian, Xiaocheng; Zhou, Dandan; Zhu, Na; Wang, Jianjun; Li, Mingzhong; Xu, Dangpeng; Dang, Zhao; Hu, Dongxia; Zhu, Qihua; Zheng, Wanguo; Wang, Feng

    2015-10-01

    Time fiducial laser is an important tool for the precise measurement in high energy density physics experiments. The VISAR probe laser is also vital for shock wave diagnostics in ICF experiments. Here, time fiducial laser and VISAR light were generated from one source on SG-III laser facility. After generated from a 1064-nm DFB laser, the laser is modulated by an amplitude modulator driven by 10 GS/s arbitrary waveform generator. Using time division multiplexing technology, the ten-pulse time fiducial laser and the 20-ns VISAR pulse were split by a 1×2 multiplexer and then chosen by two acoustic optic modulators. Using the technique, cost of the system was reduced. The technologies adopted in the system also include pulse polarization stabilization, high precision fiber coupling and energy transmission. The time fiducial laser generated synchronized 12-beam 2ω and 4-beam 3ω laser, providing important reference marks for different detectors and making it convenient for the analysis of diagnostic data. After being amplified by fiber amplifiers and Nd:YAG rod amplifiers, the VISAR laser pulse was frequency-converted to 532-nm pulse by a thermally controlled LBO crystal with final output energy larger than 20 mJ. Finally, the green light was coupled into a 1-mm core diameter, multimode fused silica optical fiber and propagated to the imaging VISAR. The VISAR laser has been used in the VISAR diagnostic physics experiments. Shock wave loading and slowdown processes were measured. Function to measure velocity history of shock wave front movement in different kinds of materials was added to the SG-III laser facility.

  4. An improved light source for laser ranging

    NASA Technical Reports Server (NTRS)

    Hamal, Karel; Richardson, Martin

    1993-01-01

    The development of a new laser material, Cr-doped LiSAF, makes possible the development of a laser source for satellite ranging systems that is more superior in performance capabilities than current Nd:YAG-based laser sources. This new material offers the potential of shorter pulses and more preferable wavelengths (850 and 425 nm) than multiwavelength Nd:YAG systems, leading to superior ranging resolution and greater detection sensitivity. We are embarking on a feasibility study of a two-wavelength, mode-locked laser system based on Cr:LiSAF, providing shorter pulses for improved ranging resolution.

  5. Laser entertainment and light shows in education

    NASA Astrophysics Data System (ADS)

    Sabaratnam, Andrew T.; Symons, Charles

    2002-05-01

    Laser shows and beam effects have been a source of entertainment since its first public performance May 9, 1969, at Mills College in Oakland, California. Since 1997, the Photonics Center, NgeeAnn Polytechnic, Singapore, has been using laser shows as a teaching tool. Students are able to exhibit their creative skills and learn at the same time how lasers are used in the entertainment industry. Students will acquire a number of skills including handling three- phase power supply, operation of cooling system, and laser alignment. Students also acquire an appreciation of the arts, learning about shapes and contours as they develop graphics for the shows. After holography, laser show animation provides a combination of the arts and technology. This paper aims to briefly describe how a krypton-argon laser, galvanometer scanners, a polychromatic acousto-optic modulator and related electronics are put together to develop a laser projector. The paper also describes how students are trained to make their own laser animation and beam effects with music, and at the same time have an appreciation of the operation of a Class IV laser and the handling of optical components.

  6. Fluorescent photography of spray droplets using a laser light source

    NASA Technical Reports Server (NTRS)

    Groeneweg, J.; Hiroyasu, H.; Sowls, R.

    1969-01-01

    Monochromatic laser emission transformed by a fluorescent process into droplet emission over a wavelength band provides high light intensities for obtaining adequate time resolution to stop droplet motion in photographic spray studies. Experiments showed that the Q-switched laser-optical harmonic generator combination produced sharp, well-exposed droplet images.

  7. First light : from the ruby laser to nonlinear optics

    NASA Astrophysics Data System (ADS)

    Giordmaine, J. A.

    2010-02-01

    Laser action was first demonstrated by Maiman in a flashlamp-pumped ruby crystal in May of 1960. This talk, based in part on personal recollections, recounts some of the research highlights during the two years that followed - a period of exponential growth in the field of quantum electronics, driven by the newly available, unprecedented coherence, power, and monochomaticity of laser light. Active areas from the beginning were new lasers in HeNe and other gas systems, in host crystals with increasingly effective dopants, and in glass. Modes in open resonators became understood, as did the surprising granularity of laser light An important step was the Q-switch, enabling megawatt lasers and providing a new tool for the study of dielectrics at high optical fields. The field of nonlinear optics opened up with experimental discoveries including optical second harmonic generation, two-photon absorption, phase matching and stimulated Raman scattering. A key to subsequent progress was a comprehensive quantum mechanical theory that provided a general description of nonlinear optical processes. The end of the two-year period covered here coincided with two advances which were to shape the future role of lasers in technology and science: the first semiconductor lasers; and a theoretical description of states of light having truly quantum properties, properties not evident in laser light up to that time. )

  8. Active beam shaping in multiple laser guide stars

    NASA Astrophysics Data System (ADS)

    Jones, Katharine J.

    2012-10-01

    Adaptive beam shaping is a critical part of multiple Laser Guide Stars (LGS) for Multiple Conjugate Adaptive Optics (MCAO) for ground-based astronomical telescopes. There are two kinds of Laser Guide Stars: Na Laser Guide Stars (at 589 nm and 92 km altitude) and Rayleigh Laser Guide Stars (at 532 nm and 20 km altitude). Multiple Conjugate Adaptive Optics (MCAO) corrects for each "layer" of atmosphere independently. Multiple Laser Guide Stars are being developed to achieve a measure of tilt and increase the isoplanatic patch. Multiple Laser Guide Stars are being combined with Multiple Conjugate Optics in the Large Binocular Telescope (LBT): more than one Laser Guide Star (4-5) and two different wavelengths: 589 nm and 532 nm. Other observatories have multiple Laser Guide Stars but only one wavelength: 589 nm or 532 nm. Because Laser Guide Stars are launched into the atmosphere, adaptive beam shaping will be carried out before the laser is launched and will be different depending on which laser is being used, presumably to effect the tightest beam which can be achieved at the power level which is required to provide the requisite return to gound-based wavefront sensors. A complete range of devices are used. Beam attenuation and divergnece will take place. Multiple Laser Guide Stars of major observatories (SOR, LBT, MMT, ESO VLT and Gemini South) will be evaluated for effective adaptive beam shaping and impact on performance

  9. Control of light backscattering in blood during intravenous laser irradiation

    NASA Astrophysics Data System (ADS)

    Melnik, Ivan S.; Popov, V. D.; Rusina, Tatyana V.; Dets, Sergiy M.

    1997-02-01

    One of the most important problems in modern laser medicine is the determination of system response on laser treatment. Reaction of living system is significant during many kinds of laser procedures like surgery, therapy and biostimulation. Our study was aimed to optimize laser exposure using feed-back fiber system for intravenous laser irradiation of blood (ILIB). This system consisted of helium-neon laser (633 nm, 5 mW) with coupled fiber unit, photodetector and PC interface. Photodetector signals produced due to light backscattering were storaged and processed during all blood irradiation procedure. Significant time-dependent variations were observed within 9-15 min after beginning of treatment procedure and were correlated with number of trials, stage and character of disease. The designed feed-back system allows us to register a human blood response on laser irradiation to achieve better cure effect.

  10. Gratings for Increasing Solid-State Laser Gain and Efficiency

    SciTech Connect

    Erlandson, A C; Britten, J A; Bonlie, J D

    2010-04-16

    We introduce new concepts for increasing the efficiency of solid state lasers by using gratings deposited on laser slabs or disks. The gratings improve efficiency in two ways: (1) by coupling out of the slab deleterious amplified spontaneous emission (ASE) and (2) by increasing the absorption efficiency of pump light. The gratings also serve as antireflective coatings for the extracting laser beam. To evaluate the potential for such coatings to improve laser performance, we calculated optical properties of a 2500 groove/mm, tantala-silica grating on a 1cm x 4cm x 8cm titanium-doped sapphire slab and performed ray-trace calculations for ASE and pump light. Our calculations show substantial improvements in efficiency due to grating ASE-coupling properties. For example, the gratings reduce pump energy required to produce a 0.6/cm gain coefficient by 9%, 20% and 35% for pump pulse durations of 0.5 {micro}s, 1{micro}s and 3{micro}s, respectively. Gratings also increase 532-nm pump-light absorption efficiency, particularly when the product slab overall absorption is small. For example, when the single-pass absorption is 1 neper, absorption efficiency increases from 66%, without gratings, to 86%, when gratings are used.

  11. Laser Light: Using Laser Refractometry to Determine Concentration.

    ERIC Educational Resources Information Center

    Gauger, Robert

    1995-01-01

    Laser refractometry is a science-technology-based activity that requires students to manipulate a variety of equipment, tools, materials, and critical-thinking skills. Students use a laser to measure the percent of glucose in a solution by calibrating the system, taking measurements, and computing the concentration. (MKR)

  12. Experimental and theoretical studies of H2O oxidation by neutral Ti2O4,5 clusters under visible light irradiation.

    PubMed

    Yin, Shi; Bernstein, Elliot R

    2014-07-21

    A new photo excitation fast flow reactor system is constructed and used to investigate reactions of neutral TimOn clusters with H2O under visible (532 nm) light irradiation. Single photon ionization at 118 nm (10.5 eV) is used to detect neutral cluster distributions through time of flight mass spectrometry. TimOn clusters are generated through laser ablation of a titanium target in the presence of 4% O2/He carrier gas. Association products Ti2O4(H2O) and Ti2O5(H2O) are observed for reactions of H2O and TimOn clusters without irradiation. Under 532 nm visible light irradiation of the fast flow reactor, only the Ti2O5(H2O) feature disappears. This light activated reaction suggests that visible radiation can induce chemistry for Ti2O5(H2O), but not for Ti2O4(H2O). Density functional theory (DFT) and time-dependent (TD) DFT calculations are performed to explore the ground and first excited state potential energy surfaces (PES) for the reaction Ti2O5 + H2O → Ti2O4 + H2O2. A high barrier (1.33 eV) and a thermodynamically unfavorable (1.14 eV) pathway are obtained on the ground state PES for the Ti2O5 + H2O reaction; the reaction is also thermodynamically unfavorable (1.54 eV) on the first singlet excited state PES. The reaction is proposed to occur on the ground state PES through a conical intersection ((S1/S0)CI), and to generate products Ti2O4 and H2O2 on the ground state PES. This mechanism is substantiated by a multi-reference ab initio calculation at the complete active space self-consistent field (CASSCF) level. The S0-S1 vertical excitation energy of Ti2O4 (3.66 eV) is much higher than the 532 nm photon energy (2.33 eV), suggesting this visible light driven reaction is unfavorable for the Ti2O4 cluster. The TDDFT calculated optical absorption spectra of Ti2O4 and Ti2O5 further indicate that Ti2O5 like structures on a titanium oxide surface are the active catalytic sites for visible light photo-catalytic oxidation of water. PMID:24898817

  13. Shaping laser accelerated ions for future applications - The LIGHT collaboration

    NASA Astrophysics Data System (ADS)

    Busold, S.; Almomani, A.; Bagnoud, V.; Barth, W.; Bedacht, S.; Blažević, A.; Boine-Frankenheim, O.; Brabetz, C.; Burris-Mog, T.; Cowan, T. E.; Deppert, O.; Droba, M.; Eickhoff, H.; Eisenbarth, U.; Harres, K.; Hoffmeister, G.; Hofmann, I.; Jaeckel, O.; Jaeger, R.; Joost, M.; Kraft, S.; Kroll, F.; Kaluza, M.; Kester, O.; Lecz, Z.; Merz, T.; Nürnberg, F.; Al-Omari, H.; Orzhekhovskaya, A.; Paulus, G.; Polz, J.; Ratzinger, U.; Roth, M.; Schaumann, G.; Schmidt, P.; Schramm, U.; Schreiber, G.; Schumacher, D.; Stoehlker, T.; Tauschwitz, A.; Vinzenz, W.; Wagner, F.; Yaramyshev, S.; Zielbauer, B.

    2014-03-01

    The generation of intense ion beams from high-intensity laser-generated plasmas has been the focus of research for the last decade. In the LIGHT collaboration the expertise of heavy ion accelerator scientists and laser and plasma physicists has been combined to investigate the prospect of merging these ion beams with conventional accelerator technology and exploring the possibilities of future applications. We report about the goals and first results of the LIGHT collaboration to generate, handle and transport laser driven ion beams. This effort constitutes an important step in research for next generation accelerator technologies.

  14. Light polarization experiments with a diode laser pointer

    NASA Astrophysics Data System (ADS)

    Benenson, Raymond E.

    2000-01-01

    Polarized light has many uses: glare reduction, stress analysis, microscope image enhancement, thin-film characterization, astronomy, saccharimetry, and atomic spectroscopy. Here we discuss introductory polarized light measurements in which a diode laser pointer replaces the more frequently used polarized He-Ne laser. A diode laser has been used in introductory optics experiments, and in a more advanced polarization-reflection experiment. Its strong collimated beam is completely polarized and, being free of infrared radiation, it permits Polaroid sheets to be used successfully with semiconductor detectors.

  15. Optical laser systems at the Linac Coherent Light Source

    DOE PAGESBeta

    Minitti, Michael P.; Robinson, Joseph S.; Coffee, Ryan N.; Edstrom, Steve; Gilevich, Sasha; Glownia, James M.; Granados, Eduardo; Hering, Philippe; Hoffmann, Matthias C.; Miahnahri, Alan; et al

    2015-04-22

    Ultrafast optical lasers play an essential role in exploiting the unique capabilities of recently commissioned X-ray free-electron laser facilities such as the Linac Coherent Light Source (LCLS). Pump–probe experimental techniques reveal ultrafast dynamics in atomic and molecular processes and reveal new insights in chemistry, biology, material science and high-energy-density physics. This manuscript describes the laser systems and experimental methods that enable cutting-edge optical laser/X-ray pump–probe experiments to be performed at LCLS.

  16. Optical laser systems at the Linac Coherent Light Source

    PubMed Central

    Minitti, Michael P.; Robinson, Joseph S.; Coffee, Ryan N.; Edstrom, Steve; Gilevich, Sasha; Glownia, James M.; Granados, Eduardo; Hering, Philippe; Hoffmann, Matthias C.; Miahnahri, Alan; Milathianaki, Despina; Polzin, Wayne; Ratner, Daniel; Tavella, Franz; Vetter, Sharon; Welch, Marc; White, William E.; Fry, Alan R.

    2015-01-01

    Ultrafast optical lasers play an essential role in exploiting the unique capabilities of recently commissioned X-ray free-electron laser facilities such as the Linac Coherent Light Source (LCLS). Pump–probe experimental techniques reveal ultrafast dynamics in atomic and molecular processes and reveal new insights in chemistry, biology, material science and high-energy-density physics. This manuscript describes the laser systems and experimental methods that enable cutting-edge optical laser/X-ray pump–probe experiments to be performed at LCLS. PMID:25931064

  17. Laser versus intense pulsed light: Competing technologies in dermatology.

    PubMed

    Ross, E Victor

    2006-04-01

    Lasers have been competing with non-laser intense pulsed light (IPL) sources in the cosmetic arena over the past 10 years. Initially IPLs were somewhat cumbersome and accepted by a minority of "serious" practitioners. Recently, however, the popularity of full-face visible light skin rejuvenation, enhanced engineering of IPLs, and favorable cost versus many lasers, have lead to a proliferation of IPL devices. No longer a stepchild in the rejuvenation market, IPLs may overtake lasers as the devices of choice among most physicians. We review the pros and cons of lasers and IPLs within the context of design, cost, and other practical concerns for a typical office-based practice. PMID:16596659

  18. Preparation and optimization of the laser thin film filter

    NASA Astrophysics Data System (ADS)

    Su, Jun-hong; Wang, Wei; Xu, Jun-qi; Cheng, Yao-jin; Wang, Tao

    2014-08-01

    A co-colored thin film device for laser-induced damage threshold test system is presented in this paper, to make the laser-induced damage threshold tester operating at 532nm and 1064nm band. Through TFC simulation software, a film system of high-reflection, high -transmittance, resistance to laser damage membrane is designed and optimized. Using thermal evaporation technique to plate film, the optical properties of the coating and performance of the laser-induced damage are tested, and the reflectance and transmittance and damage threshold are measured. The results show that, the measured parameters, the reflectance R >= 98%@532nm, the transmittance T >= 98%@1064nm, the laser-induced damage threshold LIDT >= 4.5J/cm2 , meet the design requirements, which lays the foundation of achieving laser-induced damage threshold multifunction tester.

  19. NASA Now: Lasers and Light: STORRM

    NASA Video Gallery

    Byron Meadows, a laser systems engineer at NASA, describes his work on sensor testing for the Orion Relative Navigation Risk Mitigation, or STORRM, project. Learn why NASA wants to develop technolo...

  20. Final Report: Cooling Molecules with Laser Light

    SciTech Connect

    Di Rosa, Michael D.

    2012-05-08

    Certain diatomic molecules are disposed to laser cooling in the way successfully applied to certain atoms and that ushered in a revolution in ultracold atomic physics, an identification first made at Los Alamos and which took root during this program. Despite their manipulation into numerous achievements, atoms are nonetheless mundane denizens of the quantum world. Molecules, on the other hand, with their internal degrees of freedom and rich dynamical interplay, provide considerably more complexity. Two main goals of this program were to demonstrate the feasibility of laser-cooling molecules to the same temperatures as laser-cooled atoms and introduce a means for collecting laser-cooled molecules into dense ensembles, a foundational start of studies and applications of ultracold matter without equivalence in atomic systems.

  1. Design and Calibration of a Raman Spectrometer for use in a Laser Spectroscopy Instrument Intended to Analyze Martian Surface and Atmospheric Characteristics for NASA

    NASA Technical Reports Server (NTRS)

    Lucas, John F.; Hornef, James

    2016-01-01

    This project's goal is the design of a Raman spectroscopy instrument to be utilized by NASA in an integrated spectroscopy strategy that will include Laser-Induced Breakdown Spectroscopy (LIBS) and Laser-Induced Florescence Spectroscopy (LIFS) for molecule and element identification on Mars Europa, and various asteroids. The instrument is to be down scaled from a dedicated rover mounted instrument into a compact unit with the same capabilities and accuracy as the larger instrument. The focus for this design is a spectrometer that utilizes Raman spectroscopy. The spectrometer has a calculated range of 218 nm wavelength spectrum with a resolution of 1.23 nm. To filter out the laser source wavelength of 532 nm the spectrometer design utilizes a 532 nm wavelength dichroic mirror and a 532 nm wavelength notch filter. The remaining scatter signal is concentrated by a 20 x microscopic objective through a 25-micron vertical slit into a 5mm diameter, 1cm focal length double concave focusing lens. The light is then diffracted by a 1600 Lines per Millimeter (L/mm) dual holographic transmission grating. This spectrum signal is captured by a 1-inch diameter double convex 3 cm focal length capture lens. An Intensified Charge Couple Device (ICCD) is placed within the initial focal cone of the capture lens and the Raman signal captured is to be analyzed through spectroscopy imaging software. This combination allows for accurate Raman spectroscopy to be achieved. The components for the spectrometer have been bench tested in a series of prototype developments based on theoretical calculations, alignment, and scaling strategies. The mounting platform is 2.5 cm wide by 8.8 cm long by 7 cm height. This platform has been tested and calibrated with various sources such as a neon light source and ruby crystal. This platform is intended to be enclosed in a ruggedized enclosure for mounting on a rover platform. The size and functionality of the Raman spectrometer allows for the rover to

  2. A twin-mirrored galvanometer laser light sheet generator

    NASA Technical Reports Server (NTRS)

    Rhodes, David B.; Franke, John M.; Jones, Stephen B.; Leighty, Bradley D.

    1988-01-01

    A galvanometer mirror-based laser light sheet system has been developed for use in the Basic Aerodynamics Research Tunnel at NASA Langley. This system generates and positions single or multiple light sheets over aeronautical research models being tested in the low speed tunnel. This report describes a twin mirrored galvanometer laser light sheet generator and shows typical light sheet arrangements in use. With this system, illumination of smoke entrained in the flow over a delta wing model reveals the vortical flow produced by the separation of the flow at the leading edge of the model. The light sheet system has proven to be very adaptable and easy to use in sizing and positioning light sheets in wind tunnel applications.

  3. Laser light stripe measurements assure correct piston assembly

    NASA Astrophysics Data System (ADS)

    Stein, Norbert; Frohn, Heiko

    1993-12-01

    Two VIKON-3D optical inspection systems assure the correct assembly of piston rings and guard rings in a new Volkswagen piston/rod assembly line. Both systems use laser light stripe measurements to locate and identify the relevant parts with high accuracy. The piston ring assembly is checked dynamically in video real time using laser light stripe and parallel projection techniques. In addition structured light is used to verify the correct piston/rod assembly. Both inspection systems are fully integrated into the manufacturing line. All types of pistons assembled can be checked without any mechanical changes to the measurement setup.

  4. Laser warning receiver to identify the wavelength and angle of arrival of incident laser light

    DOEpatents

    Sinclair; Michael B.; Sweatt, William C.

    2010-03-23

    A laser warning receiver is disclosed which has up to hundreds of individual optical channels each optically oriented to receive laser light from a different angle of arrival. Each optical channel has an optical wedge to define the angle of arrival, and a lens to focus the laser light onto a multi-wavelength photodetector for that channel. Each multi-wavelength photodetector has a number of semiconductor layers which are located in a multi-dielectric stack that concentrates the laser light into one of the semiconductor layers according to wavelength. An electrical signal from the multi-wavelength photodetector can be processed to determine both the angle of arrival and the wavelength of the laser light.

  5. Laterally injected light-emitting diode and laser diode

    DOEpatents

    Miller, Mary A.; Crawford, Mary H.; Allerman, Andrew A.

    2015-06-16

    A p-type superlattice is used to laterally inject holes into an III-nitride multiple quantum well active layer, enabling efficient light extraction from the active area. Laterally-injected light-emitting diodes and laser diodes can enable brighter, more efficient devices that impact a wide range of wavelengths and applications. For UV wavelengths, applications include fluorescence-based biological sensing, epoxy curing, and water purification. For visible devices, applications include solid state lighting and projection systems.

  6. Stray-light suppression with high-collection efficiency in laser light-scattering experiments

    NASA Technical Reports Server (NTRS)

    Deilamian, K.; Gillaspy, J. D.; Kelleher, D. E.

    1992-01-01

    An optical system is described for collecting a large fraction of fluorescent light emitted isotropically from a cylindrical interaction region. While maintaining an overall detection efficiency of 9 percent, the system rejects, by more than 12 orders of magnitude, incident laser light along a single axis that intersects the interaction region. Such a system is useful for a wide variety of light-scattering experiments in which high-collection efficiency is desirable, but in which light from an incident laser beam must be rejected without resorting to spectral filters.

  7. Femtosecond Kerr-lens mode-locked Alexandrite laser.

    PubMed

    Ghanbari, Shirin; Akbari, Reza; Major, Arkady

    2016-06-27

    The generation of 170 fs pulses at 755 nm from a Kerr-lens mode-locked Alexandrite laser was demonstrated. The laser was pumped at 532 nm and produced 780 mW of average output power with 9.8% of optical-to-optical efficiency. To the best of our knowledge, these are the shortest pulses that have been produced from a mode-locked Alexandrite laser to date. PMID:27410635

  8. The Laser Synthesis of Linear Polyynes: The Particle in a Box Revisited

    ERIC Educational Resources Information Center

    Anderson, Bruce D.; Gordon, Christopher M.

    2008-01-01

    In this experiment, linear polyynes are synthesized and then the predictions of a one-dimensional, particle in a box are used to calculate the quantum mechanical box length for the polyynes. A solution of graphite in ethanol is irradiated with a Nd:YAG laser (532 nm) and the resulting solution is filtered and analyzed. Data from gas…

  9. The light-matter interaction of a single semiconducting AlGaN nanowire and noble metal Au nanoparticles in the sub-diffraction limit.

    PubMed

    Sivadasan, A K; Madapu, Kishore K; Dhara, Sandip

    2016-08-24

    Near field scanning optical microscopy (NSOM) is not only a tool for imaging of sub-diffraction limited objects but also a prominent characteristic tool for understanding the intrinsic properties of nanostructures. In order to understand light-matter interactions in the near field regime using a NSOM technique with an excitation of 532 nm (2.33 eV), we selected an isolated single semiconducting AlGaN nanowire (NW) of diameter ∼120 nm grown via a vapor liquid solid (VLS) mechanism along with a metallic Au nanoparticle (NP) catalyst. The role of electronic transitions from different native defect related energy states of AlGaN is discussed in understanding the NSOM images for the semiconducting NW. The effect of strong surface plasmon resonance absorption of an excitation laser on the NSOM images for Au NPs, involved in the VLS growth mechanism of NWs, is also observed. PMID:27511614

  10. Luminescent light source for laser pumping and laser system containing same

    DOEpatents

    Hamil, Roy A.; Ashley, Carol S.; Brinker, C. Jeffrey; Reed, Scott; Walko, Robert J.

    1994-01-01

    The invention relates to a pumping lamp for use with lasers comprising a porous substrate loaded with a component capable of emitting light upon interaction of the component with exciting radiation and a source of exciting radiation. Preferably, the pumping lamp comprises a source of exciting radiation, such as an electron beam, and an aerogel or xerogel substrate loaded with a component capable of interacting with the exciting radiation, e.g., a phosphor, to produce light, e.g., visible light, of a suitable band width and of a sufficient intensity to generate a laser beam from a laser material.

  11. The 'Magic Light': A Discussion on Laser Ethics.

    PubMed

    Stylianou, Andreas; Talias, Michael A

    2015-08-01

    Innovations in technology and science form novel fields that, although beneficial, introduce new bio-ethical issues. In their short history, lasers have greatly influenced our everyday lives, especially in medicine. This paper focuses particularly on medical and para-medical laser ethics and their origins, and presents the complex relationships within laser ethics through a three-dimensional matrix model. The term 'laser' and the myth of the 'magic light' can be identified as landmarks for laser related ethical issues. These ethical issues are divided into five major groups: (1) media, marketing, and advertising; (2) economic outcomes; (3) user training; (4) the user-patient/client relationship; and (5) other issues. In addition, issues arising from two of the most common applications of lasers, laser eye surgery and laser tattoo removal, are discussed. The aim of this paper is to demonstrate that the use of medical and para-medical lasers has so greatly influenced our lives that the scientific community must initiate an earnest discussion of medical laser ethics. PMID:25027860

  12. Laser remote sensing of backscattered light from a target sample

    DOEpatents

    Sweatt, William C.; Williams, John D.

    2008-02-26

    A laser remote sensing apparatus comprises a laser to provide collimated excitation light at a wavelength; a sensing optic, comprising at least one optical element having a front receiving surface to focus the received excitation light onto a back surface comprising a target sample and wherein the target sample emits a return light signal that is recollimated by the front receiving surface; a telescope for collecting the recollimated return light signal from the sensing optic; and a detector for detecting and spectrally resolving the return light signal. The back surface further can comprise a substrate that absorbs the target sample from an environment. For example the substrate can be a SERS substrate comprising a roughened metal surface. The return light signal can be a surface-enhanced Raman signal or laser-induced fluorescence signal. For fluorescence applications, the return signal can be enhanced by about 10.sup.5, solely due to recollimation of the fluorescence return signal. For SERS applications, the return signal can be enhanced by 10.sup.9 or more, due both to recollimation and to structuring of the SERS substrate so that the incident laser and Raman scattered fields are in resonance with the surface plasmons of the SERS substrate.

  13. An amplified femtosecond laser system for material micro-/nanostructuring with an integrated Raman microscope

    NASA Astrophysics Data System (ADS)

    Zalloum, Othman H. Y.; Parrish, Matthew; Terekhov, Alexander; Hofmeister, William

    2010-05-01

    In order to obtain new insights into laser-induced chemical material modifications, we introduce a novel combined approach of femtosecond pulsed laser-direct writing and in situ Raman microscopy within a single experimental apparatus. A newly developed scanning microscope, the first of its kind, provides a powerful tool for micro-/nanomachining and characterization of material properties and allows us to relate materials' functionality with composition. We address the issues of light delivery to the photomodification site and show the versatility of the system using tight focusing. Amplified femtosecond pulses are generated by a Ti:sapphire laser oscillator and a chirped-pulse regenerative amplifier, both pumped by a diode-pumped frequency doubled neodymium-doped yttrium orthovanadate (Nd:YVO4) laser operating at 532 nm. Results of Raman spectroscopy and scanning electron microscopy images of femtosecond laser micro-/nanomachining on the surface and in the bulk of single-crystal diamond obtained from first trials of this instrument are also presented. This effective combination could help to shed light on the influence of the local structure fluctuations on controllability of the laser processing and the role of the irradiation in the ablation processes ruling out possible imprecisions coming from the use of the two independent techniques.

  14. A multiple work mode YAG laser in derma surgery

    NASA Astrophysics Data System (ADS)

    Sa, Yu; Zhang, Guizhong; Ye, Zhisheng; Yu, Lin

    2006-06-01

    It has been very common that a pulse laser is used in derma surgery based on the theory of "Selective Photothermolysis". This method has also been accepted as the best way to treat the pigments by the medical textbook. A kind of double-pulsed laser which gets the name by two pulse output at one pumping process is developed for derma surgery lately, and this kind of laser has been proved more effective and safe than single-pulse laser. We also develop a multiple work mode YAG laser including two double-pulsed modes at 1064nm and 532nm, two single-pulsed modes at 1064nm and 532nm, and one free-running mode at 1064nm. Considering availability, security and reliability of the laser as a surgery machine, some important subsystems of the laser are optimized carefully, such as Q-switch driver, wavelength-switching system, power supply, and control system etc. At last we get a prototype laser which can run for longer than 30 minutes continuously, and output Max10 pulse per second (pps) with Max800mJ energy at 1064nm double Q-Switch mode, or Max400mJ at 532nm. Using double pulse mode of the laser we do some removal experiments of tattoos and other pigments, and obtain good effect.

  15. Laser and Light-Based Aesthetics in Men.

    PubMed

    Green, Jeremy B; Metelitsa, Andrei I; Kaufman, Joely; Keaney, Terrence

    2015-09-01

    Men represent an important evolving segment of the cosmetic market. With the growing acceptability of cosmetic procedures along with societal and workplace pressure to maintain youthfulness, men increasingly seek the advice of aesthetic practitioners. Despite this so-called "Menaissance," there is a paucity of published literature regarding laser and light treatments of male skin. Herein the differences in male cutaneous physiology are addressed, followed by a review of light-based treatment of conditions largely unique to male skin, pseudofolliculitis barbae, and rhinophyma. Next, the publications related to laser treatment of male skin specifically are examined. We conclude with a discussion of personal observations derived from clinical experience with laser and light-based treatments in men. PMID:26355628

  16. Light fan driven by a relativistic laser pulse.

    PubMed

    Shi, Yin; Shen, Baifei; Zhang, Lingang; Zhang, Xiaomei; Wang, Wenpeng; Xu, Zhizhan

    2014-06-13

    When a relativistic laser pulse with a high photon density interacts with a specially tailored thin foil target, a strong torque is exerted on the resulting spiral-shaped foil plasma, or "light fan." Because of its structure, the latter can gain significant orbital angular momentum (OAM), and the opposite OAM is imparted to the reflected light, creating a twisted relativistic light pulse. Such an interaction scenario is demonstrated by particle-in-cell simulation as well as analytical modeling, and should be easily verifiable in the laboratory. As an important characteristic, the twisted relativistic light pulse has a strong torque and ultrahigh OAM density. PMID:24972214

  17. Laser light: its nature and its action on the eye.

    PubMed Central

    Bessette, F M; Nguyen, L C

    1989-01-01

    Lasers produce a coherent, focused, monochromatic, high-energy form of light. Because laser surgery is more versatile and precise and is freer of complications than conventional surgery it has become widely accepted in ophthalmology over the past 10 years. Applications range from routine procedures in the fundus to recent, more delicate interventions in the cornea. The argon laser is the most widely used to treat extrafoveal chorioretinal diseases such as age-related macular degeneration and diabetic retinopathy; it has also been used successfully to treat glaucoma by iridectomy or trabeculoplasty. The krypton red laser is the argon laser's counterpart in the treatment of subfoveal and pigment-epithelium-related diseases. Posterior capsulotomy is the most widespread and successful intervention with the neodymium:yttrium-aluminum-garnet crystal laser; this laser is also used to cut vitreous traction bands and is increasingly used in iridectomy. Although the use of the excimer laser in corneal surgery is still largely investigational it has been shown to produce precise cuts in corneal layers for the correction of myopia or astigmatism. The variable-wavelength dye laser, capable of reaching a specific level in the retina or choroid, has offered exciting new developments, and it promises to soon be part of the ophthalmologist's armamentarium in the treatment of eye disease. PMID:2684379

  18. Candle soot nanoparticles-polydimethylsiloxane composites for laser ultrasound transducers

    NASA Astrophysics Data System (ADS)

    Chang, Wei-Yi; Huang, Wenbin; Kim, Jinwook; Li, Sibo; Jiang, Xiaoning

    2015-10-01

    Generation of high power laser ultrasound strongly demands the advanced materials with efficient laser energy absorption, fast thermal diffusion, and large thermoelastic expansion capabilities. In this study, candle soot nanoparticles-polydimethylsiloxane (CSNPs-PDMS) composite was investigated as the functional layer for an optoacoustic transducer with high-energy conversion efficiency. The mean diameter of the collected candle soot carbon nanoparticles is about 45 nm, and the light absorption ratio at 532 nm wavelength is up to 96.24%. The prototyped CSNPs-PDMS nano-composite laser ultrasound transducer was characterized and compared with transducers using Cr-PDMS, carbon black (CB)-PDMS, and carbon nano-fiber (CNFs)-PDMS composites, respectively. Energy conversion coefficient and -6 dB frequency bandwidth of the CSNPs-PDMS composite laser ultrasound transducer were measured to be 4.41 × 10-3 and 21 MHz, respectively. The unprecedented laser ultrasound transduction performance using CSNPs-PDMS nano-composites is promising for a broad range of ultrasound therapy applications.

  19. Laser-induced light emission from carbon nanoparticles

    SciTech Connect

    Osswald, S.; Behler, K.; Gogotsi, Y.

    2008-10-01

    Strong absorption of light in a broad wavelength range and poor thermal conductance between particles of carbon nanomaterials, such as nanotubes, onions, nanodiamond, and carbon black, lead to strong thermal emission (blackbody radiation) upon laser excitation, even at a very low (milliwatts) power. The lasers commonly used during Raman spectroscopy characterization of carbon can cause sample heating to very high temperatures. While conventional thermometry is difficult in the case of nanomaterials, Raman spectral features, such as the G band of graphitic carbon and thermal emission spectra were used to estimate the temperature during light emission that led to extensive graphitization and evaporation of carbon nanomaterials, indicating local temperatures exceeding 3500 deg. C.

  20. Control of Laser High-Harmonic Generation with Counterpropagating Light

    NASA Astrophysics Data System (ADS)

    Voronov, S. L.; Kohl, I.; Madsen, J. B.; Simmons, J.; Terry, N.; Titensor, J.; Wang, Q.; Peatross, J.

    2001-09-01

    Relatively weak counterpropagating light is shown to disrupt the emission of laser high-harmonic generation. Harmonic orders ranging from the teens to the low thirties produced by a 30-femtosecond pulse in a narrow argon jet are ``shut down'' with a contrast as high as 2 orders of magnitude by a chirped 1-picosecond counterpropagating laser pulse (60 times less intense). Alternatively, under poor phase-matching conditions, the counterpropagating light boosts harmonic production by similar contrast through quasiphase matching where out-of-phase emission is suppressed.

  1. Absorption of a laser light pulse in a dense plasma.

    NASA Technical Reports Server (NTRS)

    Mehlman-Balloffet, G.

    1973-01-01

    An experimental study of the absorption of a laser light pulse in a transient, high-density, high-temperature plasma is presented. The plasma is generated around a metallic anode tip by a fast capacitive discharge occurring in vacuum. The amount of transmitted light is measured for plasmas made of different metallic ions in the regions of the discharge of high electronic density. Variation of the transmission during the laser pulse is also recorded. Plasma electrons are considered responsible for the very high absorption observed.

  2. Laser light propagation in adipose tissue and laser effects on adipose cell membranes

    NASA Astrophysics Data System (ADS)

    Solarte, Efraín; Rebolledo, Aldo; Gutierrez, Oscar; Criollo, William; Neira, Rodrigo; Arroyave, José; Ramírez, Hugo

    2006-01-01

    Recently Neira et al. have presented a new liposuction technique that demonstrated the movement of fat from inside to outside of the cell, using a low-level laser device during a liposuction procedure with Ultrawet solution. The clinical observations, allowed this new surgical development, started a set of physical, histological and pharmacological studies aimed to determine the mechanisms involved in the observed fat mobilization concomitant to external laser application in liposuction procedures. Scanning and Transmission Electron Microscopy, studies show that the cellular arrangement of normal adipose tissue changes when laser light from a diode laser: 10 mW, 635 nm is applied. Laser exposures longer than 6 minutes cause the total destruction of the adipocyte panicles. Detailed observation of the adipose cells show that by short irradiation times (less than four minutes) the cell membrane exhibits dark zones, that collapse by longer laser exposures. Optical measurements show that effective penetration length depends on the laser intensity. Moreover, the light scattering is enhanced by diffraction and subsequent interference effects, and the tumescent solution produces a clearing of the tissue optical medium. Finally, isolate adipose cell observation show that fat release from adipocytes is a concomitant effect between the tumescent solution (adrenaline) and laser light, revealing a synergism which conduces to the aperture, and maybe the disruption, of the cell membrane. All these studies were consistent with a laser induced cellular process, which causes fat release from inside the adipocytes into the intercellular space, besides a strong modification of the cellular membranes.

  3. Evaluating the use of laser radiation in cleaning of copper embroidery threads on archaeological Egyptian textiles

    NASA Astrophysics Data System (ADS)

    Abdel-Kareem, Omar; Harith, M. A.

    2008-07-01

    Cleaning of copper embroidery threads on archaeological textiles is still a complicated conservation process, as most textile conservators believe that the advantages of using traditional cleaning techniques are less than their disadvantages. In this study, the uses of laser cleaning method and two modified recipes of wet cleaning methods were evaluated for cleaning of the corroded archaeological Egyptian copper embroidery threads on an archaeological Egyptian textile fabric. Some corroded copper thread samples were cleaned using modified recipes of wet cleaning method; other corroded copper thread samples were cleaned with Q-switched Nd:YAG laser radiation of wavelength 532 nm. All tested metal thread samples before and after cleaning were investigated using a light microscope and a scanning electron microscope with an energy dispersive X-ray analysis unit. Also the laser-induced breakdown spectroscopy (LIBS) technique was used for the elemental analysis of laser-cleaned samples to follow up the laser cleaning procedure. The results show that laser cleaning is the most effective method among all tested methods in the cleaning of corroded copper threads. It can be used safely in removing the corrosion products without any damage to both metal strips and fibrous core. The tested laser cleaning technique has solved the problems caused by other traditional cleaning techniques that are commonly used in the cleaning of metal threads on museum textiles.

  4. High purity efficient first Stokes Raman laser

    NASA Astrophysics Data System (ADS)

    Liu, Xiaomeng; Liu, Qinyong; Li, Daijun; Du, Keming

    2015-02-01

    The subject of the solid-state Raman frequency conversion to the yellow frequency spectra has been an active topic since the mid 1990's, because of its application in bio-medical and astronomy fields. However, the yellow laser performance is often limited because of the cascade conversion to second or higher Stokes. This cascade conversion not only limits the conversion efficiency and the output power of the first Stokes, but also degrades the pulse and the beam profile of the first Stokes. We present a type of polarization coupled Raman resonator, in which the higher order ( the second Stokes and higher ) laser output can be dramatically suppressed. Our Raman resonator is pumped by a Q-switched and frequency doubled slab laser, and we can get an almost pure (P559/(P559 +P532)>99%) 559 nm yellow light output with an efficiency over 39% from 532 nm to 559 nm. The resonator includes a high reflection rear mirror, a KGW crystal, a polarization coupled input/output element, and a high reflection output coupler of 559 nm (R559 nm = 0.6). Furthermore, we have proposed an improvement of this polarization coupled Raman resonator. The theoretical calculations of the temporal and spatial dependent Raman conversion equations show that the conversion efficiency of the first order Stokes is greatly enhanced with an additionalλ/2 waveplate for 589 nm and the BBO crystal.

  5. Effects of laser energy and wavelength on the analysis of LiFePO₄ using laser assisted atom probe tomography

    DOE PAGESBeta

    Santhanagopalan, Dhamodaran; Schreiber, Daniel K.; Perea, Daniel E.; Martens, Richard L.; Janssen, Yuri; Khalifah, Peter; Meng, Ying Shirley

    2014-09-21

    The effects of laser wavelength (355 nm and 532 nm) and laser pulse energy on the quantitative analysis of LiFePO₄ by atom probe tomography are considered. A systematic investigation of ultraviolet (UV, 355 nm) and green (532 nm) laser assisted field evaporation has revealed distinctly different behaviors. With the use of a UV laser, the major issue was identified as the preferential loss of oxygen (up to 10 at%) while other elements (Li, Fe and P) were observed to be close to nominal ratios. Lowering the laser energy per pulse to 1 pJ/pulse from 50 pJ/pulse increased the observed oxygenmore » concentration to nearer its correct stoichiometry, which was also well correlated with systematically higher concentrations of ¹⁶O₂⁺ ions. Green laser assisted field evaporation led to the selective loss of Li (33% deficiency) and a relatively minor O deficiency. The loss of Li is likely a result of selective dc evaporation of Li between or after laser pulses. Comparison of the UV and green laser data suggests that the green wavelength energy was absorbed less efficiently than the UV wavelength because of differences in absorption at 355 and 532 nm for LiFePO₄. Plotting of multihit events on Saxey plots also revealed a strong neutral O₂ loss from molecular dissociation, but quantification of this loss was insufficient to account for the observed oxygen deficiency.« less

  6. Effects of laser energy and wavelength on the analysis of LiFePO₄ using laser assisted atom probe tomography

    SciTech Connect

    Santhanagopalan, Dhamodaran; Schreiber, Daniel K.; Perea, Daniel E.; Martens, Richard L.; Janssen, Yuri; Khalifah, Peter; Meng, Ying Shirley

    2014-09-21

    The effects of laser wavelength (355 nm and 532 nm) and laser pulse energy on the quantitative analysis of LiFePO₄ by atom probe tomography are considered. A systematic investigation of ultraviolet (UV, 355 nm) and green (532 nm) laser assisted field evaporation has revealed distinctly different behaviors. With the use of a UV laser, the major issue was identified as the preferential loss of oxygen (up to 10 at%) while other elements (Li, Fe and P) were observed to be close to nominal ratios. Lowering the laser energy per pulse to 1 pJ/pulse from 50 pJ/pulse increased the observed oxygen concentration to nearer its correct stoichiometry, which was also well correlated with systematically higher concentrations of ¹⁶O₂⁺ ions. Green laser assisted field evaporation led to the selective loss of Li (33% deficiency) and a relatively minor O deficiency. The loss of Li is likely a result of selective dc evaporation of Li between or after laser pulses. Comparison of the UV and green laser data suggests that the green wavelength energy was absorbed less efficiently than the UV wavelength because of differences in absorption at 355 and 532 nm for LiFePO₄. Plotting of multihit events on Saxey plots also revealed a strong neutral O₂ loss from molecular dissociation, but quantification of this loss was insufficient to account for the observed oxygen deficiency.

  7. Laser produced plasma light source for EUVL

    NASA Astrophysics Data System (ADS)

    Fomenkov, Igor V.; Ershov, Alex I.; Partlo, William N.; Myers, David W.; Brown, Daniel; Sandstrom, Richard L.; La Fontaine, Bruno; Bykanov, Alexander N.; Vaschenko, Georgiy O.; Khodykin, Oleh V.; Böwering, Norbert R.; Das, Palash; Fleurov, Vladimir B.; Zhang, Kevin; Srivastava, Shailendra N.; Ahmad, Imtiaz; Rajyaguru, Chirag; De Dea, Silvia; Hou, Richard R.; Dunstan, Wayne J.; Baumgart, Peter; Ishihara, Toshihiko; Simmons, Rod D.; Jacques, Robert N.; Bergstedt, Robert A.; Brandt, David C.

    2011-04-01

    This paper describes the development of laser-produced-plasma (LPP) extreme-ultraviolet (EUV) source architecture for advanced lithography applications in high volume manufacturing. EUV lithography is expected to succeed 193 nm immersion technology for sub-22 nm critical layer patterning. In this paper we discuss the most recent results from high qualification testing of sources in production. Subsystem performance will be shown including collector protection, out-of-band (OOB) radiation measurements, and intermediate-focus (IF) protection as well as experience in system use. This presentation reviews the experimental results obtained on systems with a focus on the topics most critical for an HVM source.

  8. The efficiency of photovoltaic cells exposed to pulsed laser light

    NASA Technical Reports Server (NTRS)

    Lowe, R. A.; Landis, G. A.; Jenkins, P.

    1993-01-01

    Future space missions may use laser power beaming systems with a free electron laser (FEL) to transmit light to a photovoltaic array receiver. To investigate the efficiency of solar cells with pulsed laser light, several types of GaAs, Si, CuInSe2, and GaSb cells were tested with the simulated pulse format of the induction and radio frequency (RF) FEL. The induction pulse format was simulated with an 800-watt average power copper vapor laser and the RF format with a frequency-doubled mode-locked Nd:YAG laser. Averaged current vs bias voltage measurements for each cell were taken at various optical power levels and the efficiency measured at the maximum power point. Experimental results show that the conversion efficiency for the cells tested is highly dependent on cell minority carrier lifetime, the width and frequency of the pulses, load impedance, and the average incident power. Three main effects were found to decrease the efficiency of solar cells exposed to simulated FEL illumination: cell series resistance, LC 'ringing', and output inductance. Improvements in efficiency were achieved by modifying the frequency response of the cell to match the spectral energy content of the laser pulse with external passive components.

  9. LASERS: Iodine laser pumped by light from a shock front created by detonating an explosive

    NASA Astrophysics Data System (ADS)

    Arzhanov, V. P.; Borovich, Boris L.; Zuev, V. S.; Kazanskiĭ, V. M.; Katulin, V. A.; Kirillov, G. A.; Kormer, S. B.; Kuratov, Yu V.; Kuryapin, A. I.; Nosach, O. Yu; Sinitsyn, M. V.; Stoĭlov, Yu Yu

    1992-02-01

    The results are presented of investigations, performed in 1965-1966, of a pulsed photodissociation iodine laser utilizing CF3I and C3F7I molecules and pumped by light from a shock front created by detonating an explosive charge. Such lasers were found to possess a unique combination of high output energy and high pulse power. Two types of laser were studied. In one of them the active medium was pumped by light from a shock wave in xenon, and in the other a shock wave propagated through a mixture of the active medium and a rare gas. The energy characteristics of the second type of laser were found to be considerably higher than those of the first type. The laser pulse radiation enegy reached ~100 J with an average power of ~15 MW.

  10. Spectroscopic characterization of laser ablated silicon plasma

    NASA Astrophysics Data System (ADS)

    Shakeel, Hira; Mumtaz, M.; Shahzada, S.; Nadeem, A.; Haq, S. U.

    2014-06-01

    We report plasma parameters of laser ablated silicon plasma using the fundamental (1064 nm) and second harmonics (532 nm) of a Nd : YAG laser. The electron temperature and electron number density are evaluated using the Boltzmann plot method and Stark broadened line profile, respectively. The electron temperature and electron number density are deduced using the same laser irradiance 2-16 GW cm-2 for 1064 nm and 532 nm as 6350-7000 K and (3.42-4.44) × 1016 cm-3 and 6000-6400 K and (4.20-5.72) × 1016 cm-3, respectively. The spatial distribution of plasma parameters shows a decreasing trend of 8200-6300 K and (4.00-3.60) × 1016 cm-3 for 1064 nm and 6400-5500 K and (5.10-4.50) × 1016 cm-3 for 532 nm laser ablation. Furthermore, plasma parameters are also investigated at low pressure from 45 to 550 mbar, yielding the electron temperature as 4580-5535 K and electron number density as (1.51-2.12) × 1016 cm-3. The trend of the above-mentioned results is in good agreement with previous investigations. However, wavelength-dependent studies and the spatial evolution of plasma parameters have been reported for the first time.

  11. Towards Laser Cooling Trapped Ions with Telecom Light

    NASA Astrophysics Data System (ADS)

    Dungan, Kristina; Becker, Patrick; Donoghue, Liz; Liu, Jackie; Olmschenk, Steven

    2015-05-01

    Quantum information has many potential applications in communication, atomic clocks, and the precision measurement of fundamental constants. Trapped ions are excellent candidates for applications in quantum information because of their isolation from external perturbations, and the precise control afforded by laser cooling and manipulation of the quantum state. For many applications in quantum communication, it would be advantageous to interface ions with telecom light. We present progress towards laser cooling and trapping of doubly-ionized lanthanum, which should require only infrared, telecom-compatible light. Additionally, we present progress on optimization of a second-harmonic generation cavity for laser cooling and trapping barium ions, for future sympathetic cooling experiments. This research is supported by the Army Research Office, Research Corporation for Science Advancement, and Denison University.

  12. Rate-equation approach to atomic-laser light statistics

    SciTech Connect

    Chusseau, Laurent; Arnaud, Jacques; Philippe, Fabrice

    2002-11-01

    We consider three- and four-level atomic lasers that are either incoherently (unidirectionally) or coherently (bidirectionally) pumped, the single-mode cavity being resonant with the laser transition. The intracavity Fano factor and the photocurrent spectral density are evaluated on the basis of rate equations. According to that approach, fluctuations are caused by jumps in active and detecting atoms. The algebra is simple. Whenever a comparison is made, the expressions obtained coincide with the previous results. The conditions under which the output light exhibits sub-Poissonian statistics are considered in detail. Analytical results, based on linearization, are verified by comparison with Monte Carlo simulations. An essentially exhaustive investigation of sub-Poissonian light generation by three- and four-level lasers has been performed. Only special forms were reported earlier.

  13. Light source employing laser-produced plasma

    SciTech Connect

    Tao, Yezheng; Tillack, Mark S

    2013-09-17

    A system and a method of generating radiation and/or particle emissions are disclosed. In at least some embodiments, the system includes at least one laser source that generates a first pulse and a second pulse in temporal succession, and a target, where the target (or at least a portion the target) becomes a plasma upon being exposed to the first pulse. The plasma expand after the exposure to the first pulse, the expanded plasma is then exposed to the second pulse, and at least one of a radiation emission and a particle emission occurs after the exposure to the second pulse. In at least some embodiments, the target is a solid piece of material, and/or a time period between the first and second pulses is less than 1 microsecond (e.g., 840 ns).

  14. Laser action in chromium-activated forsterite for near infrared excitation

    NASA Technical Reports Server (NTRS)

    Petricevic, V.; Gayen, S. K.; Alfano, R. R.

    1988-01-01

    This paper reports on laser action in chromium-doped forsterite (Cr:Mg2SiO4) for 1064-nm excitation of the crystal's double-hump absorption band spanning the 850-1200-nm wavelength range. The cavity arrangement used for obtaining laser action in Cr:Mg2SiO2 was similar to that described by Petricevic et al. (1988). The fundamental and second harmonic emissions from a Q-switched Nd:YAG laser operating at a 10-Hz repetition rate were used for excitation of the NIR and visible bands, respectively. Pulsed laser action was readily observed for both the 1064-nm and 532-nm pumping at or above the respective thresholds. The laser parameters of the 532-nm and 1064-nm excitations were similar, indicating that the IR band is responsible for laser action for both excitations.

  15. Blue laser diode (LD) and light emitting diode (LED) applications

    NASA Astrophysics Data System (ADS)

    Bergh, Arpad A.

    2004-09-01

    The family of blue LEDs, edge emitting and surface emitting lasers, enable a number of applications. Blue lasers are used in digital applications such as optical storage in high density DVDs. The resolution of the spot size and hence the storage density is diffraction limited and is inversely proportional to the square of the wavelength of the laser. Other applications include printing, optical scanners, and high-resolution photo-lithography.As light emitters, blue LEDs are used for signaling and in direct view large area emissive displays. They are also making inroads into signage and LCD back-lighting, mobile platforms, and decorative accent lighting in curtains, furniture, etc.Blue LEDs produce white light either with phosphor wavelength converters or in combination with red and green LEDs. The full potential of LED light sources will require three devices to enable complete control over color and intensity.Sensing and medical/bio applications have a major impact on home security, on monitoring the environment, and on health care. New emerging diagnostic and therapeutic applications will improve the quality and reduce the cost of health care.

  16. Modelling laser light propagation in thermoplastics using Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Parkinson, Alexander

    Laser welding has great potential as a fast, non-contact joining method for thermoplastic parts. In the laser transmission welding of thermoplastics, light passes through a semi-transparent part to reach the weld interface. There, it is absorbed as heat, which causes melting and subsequent welding. The distribution and quantity of light reaching the interface are important for predicting the quality of a weld, but are experimentally difficult to estimate. A model for simulating the path of this laser light through these light-scattering plastic parts has been developed. The technique uses a Monte-Carlo approach to generate photon paths through the material, accounting for absorption, scattering and reflection between boundaries in the transparent polymer. It was assumed that any light escaping the bottom surface contributed to welding. The photon paths are then scaled according to the input beam profile in order to simulate non-Gaussian beam profiles. A method for determining the 3 independent optical parameters to accurately predict transmission and beam power distribution at the interface was established using experimental data for polycarbonate at 4 different glass fibre concentrations and polyamide-6 reinforced with 20% long glass fibres. Exit beam profiles and transmissions predicted by the simulation were found to be in generally good agreement (R2>0.90) with experimental measurements. The simulations allowed the prediction of transmission and power distributions at other thicknesses as well as information on reflection, energy absorption and power distributions at other thicknesses for these materials.

  17. Photoactive dye enhanced tissue ablation for endoscopic laser prostatectomy

    NASA Astrophysics Data System (ADS)

    Ahn, Minwoo; Nguyen, Trung Hau; Nguyen, Van Phuc; Oh, Junghwan; Kang, Hyun Wook

    2015-02-01

    Laser light has been widely used as a surgical tool to treat benign prostate hyperplasia with high laser power. The purpose of this study was to validate the feasibility of photoactive dye injection to enhance light absorption and eventually to facilitate tissue ablation with low laser power. The experiment was implemented on chicken breast due to minimal optical absorption Amaranth (AR), black dye (BD), hemoglobin powder (HP), and endoscopic marker (EM), were selected and tested in vitro with a customized 532-nm laser system with radiant exposure ranging from 0.9 to 3.9 J/cm2. Light absorbance and ablation threshold were measured with UV-VIS spectrometer and Probit analysis, respectively, and compared to feature the function of the injected dyes. Ablation performance with dye-injection was evaluated in light of radiant exposure, dye concentration, and number of injection. Higher light absorption by injected dyes led to lower ablation threshold as well as more efficient tissue removal in the order of AR, BD, HP, and EM. Regardless of the injected dyes, ablation efficiency principally increased with input parameter. Among the dyes, AR created the highest ablation rate of 44.2+/-0.2 μm/pulse due to higher absorbance and lower ablation threshold. Preliminary tests on canine prostate with a hydraulic injection system demonstrated that 80 W with dye injection yielded comparable ablation efficiency to 120 W with no injection, indicating 33 % reduced laser power with almost equivalent performance. In-depth comprehension on photoactive dye-enhanced tissue ablation can help accomplish efficient and safe laser treatment for BPH with low power application.

  18. Perovskite Materials for Light-Emitting Diodes and Lasers.

    PubMed

    Veldhuis, Sjoerd A; Boix, Pablo P; Yantara, Natalia; Li, Mingjie; Sum, Tze Chien; Mathews, Nripan; Mhaisalkar, Subodh G

    2016-08-01

    Organic-inorganic hybrid perovskites have cemented their position as an exceptional class of optoelectronic materials thanks to record photovoltaic efficiencies of 22.1%, as well as promising demonstrations of light-emitting diodes, lasers, and light-emitting transistors. Perovskite materials with photoluminescence quantum yields close to 100% and perovskite light-emitting diodes with external quantum efficiencies of 8% and current efficiencies of 43 cd A(-1) have been achieved. Although perovskite light-emitting devices are yet to become industrially relevant, in merely two years these devices have achieved the brightness and efficiencies that organic light-emitting diodes accomplished in two decades. Further advances will rely decisively on the multitude of compositional, structural variants that enable the formation of lower-dimensionality layered and three-dimensional perovskites, nanostructures, charge-transport materials, and device processing with architectural innovations. Here, the rapid advancements in perovskite light-emitting devices and lasers are reviewed. The key challenges in materials development, device fabrication, operational stability are addressed, and an outlook is presented that will address market viability of perovskite light-emitting devices. PMID:27214091

  19. Fifth-Generation Free-Electron Laser Light Sources

    SciTech Connect

    Pellegrini, Claudio

    2011-03-02

    During the past few years, the Linac Coherent Light Source (LCLS) and the Free-Electron Laser in Hamburg (FLASH) have demonstrated the outstanding capability of free-electron lasers (FELs) as sources of coherent radiation in the soft and hard x-ray region. The high intensity, tens of GW, short pulses (few to less than 100 femtoseconds, and the unique transverse coherence properties are opening a new window to study the structure and dynamics of atomic and molecular systems. The LCLS, FLASH, and the other FELs now under construction are only the beginning of the development of these light sources. The next generations will reach new levels of performance: terawatt, atto-second, ultra-small line-width, high repetition rate, full longitudinal and transverse coherence. These future developments and the R&D needed to successfully build and operate the next generation of FEL light sources will be discussed.

  20. Multimode laser beam analyzer instrument using electrically programmable optics

    NASA Astrophysics Data System (ADS)

    Marraccini, Philip J.; Riza, Nabeel A.

    2011-12-01

    Presented is a novel design of a multimode laser beam analyzer using a digital micromirror device (DMD) and an electronically controlled variable focus lens (ECVFL) that serve as the digital and analog agile optics, respectively. The proposed analyzer is a broadband laser characterization instrument that uses the agile optics to smartly direct light to the required point photodetectors to enable beam measurements of minimum beam waist size, minimum waist location, divergence, and the beam propagation parameter M2. Experimental results successfully demonstrate these measurements for a 500 mW multimode test laser beam with a wavelength of 532 nm. The minimum beam waist, divergence, and M2 experimental results for the test laser are found to be 257.61 μm, 2.103 mrad, 1.600 and 326.67 μm, 2.682 mrad, 2.587 for the vertical and horizontal directions, respectively. These measurements are compared to a traditional scan method and the results of the beam waist are found to be within error tolerance of the demonstrated instrument.

  1. Interstitial laser and chemotherapy combined for treatment of human squamous cell carcinoma

    NASA Astrophysics Data System (ADS)

    Saxton, Romaine E.; Graeber, Ines P.; Suh, Michael J.; Paek, Woo H.; Paiva, Marcos B.; Castro, Dan J.

    1997-05-01

    We have tested a combined treatment for squamous cell carcinoma based on laser activation of anti-cancer drugs in human solid tumors. Cisplatinum and the new anthrapyrazole CI- 941 are reported to interact with photothermal energy. Combined intratumor drug and interstitial laser therapy were tested in nude mice bearing human squamous cell carcinomas grown as subcutaneous tumors. Cisplatinum injection (1.2 mg/500 mg tumor) 4 hours before KTP laser fiberoptic treatment (532 nm, 0.8 W, 10 sec/site, 300 J) resulted in complete tumor regression in 6/8 animals, while intratumor drug alone led to partial regression and tumor regrowth in 10/10 mice during 12 weeks followup. Laser treatment alone resulted in ablation followed by recurrence in 7/8 cases. Similar laser treatment 4 hours after injection of the light sensitive anthrapyrazole CI-941 led to complete tumor regression in 15/22 cases. CI-941 alone at drug levels up to 1.2 mg/gm tumor in 30 mice induced stasis followed by progression in all cases. Finally, tumor retention of 14C-CI-941 in mice 4 hrs after intralesional injection was 200-fold higher than via the systemic route and by 24 hrs remained 40-fold higher, but drug levels in normal tissues were reduced 10 - 100 fold. The data suggest laser chemotherapy may be a useful new treatment for human cancer.

  2. Status of ARGOS - The Laser Guide Star System for the LBT

    NASA Astrophysics Data System (ADS)

    Raab, Walfried; Rabien, Sebastian; Gaessler, Wolfgang; Esposito, Simone; Antichi, Jacopo; Lloyd-Hart, Michael; Barl, Lothar; Beckmann, Udo; Bonaglia, Marco; Borelli, Jose; Brynnel, Joar; Buschkamp, Peter; Busoni, Lorenzo; Carbonaro, Luca; Christou, Julian; Connot, Claus; Davies, Richard; Deysenroth, Matthias; Durney, Olivier; Green, Richard; Gemperlein, Hans; Gasho, Victor; Haug, Marcus; Hubbard, Pete; Ihle, Sebastian; Kulas, Martin; Loose, Christina; Lehmitz, Michael; Noenickx, Jamison; Nussbaum, Edmund; Orban De Xivry, Gilles; Quirrenbach, Andreas; Peter, Diethard; Rahmer, Gustavo; Rademacher, Matt; Storm, Jesper; Schwab, Christian; Vaitheeswaran, Vidhya; Ziegleder, Julian

    2013-12-01

    ARGOS is an innovative multiple laser guide star adaptive optics system for the Large Binocular Telescope (LBT), designed to perform effective GLAO correction over a very wide field of view. The system is using high powered pulsed green (532 nm) lasers to generate a set of three guide stars above each of the LBT mirrors. The laser beams are launched through a 40 cm telescope and focused at an altitude of 12 km, creating laser beacons by means of Rayleigh scattering. The returning scattered light, primarily sensitive to the turbulences close to the ground, is detected by a gated wavefront sensor system. The derived ground layer correction signals are directly driving the adaptive secondary mirror of the LBT. ARGOS is especially designed for operation with the multiple object spectrograph Luci, which will benefit from both, the improved spatial resolution, as well as the strongly enhanced flux. In addition to the GLAO Rayleigh beacon system, ARGOS was also designed for a possible future upgrade with a hybrid sodium laser - Rayleigh beacon combination, enabling diffraction limited operation. The ARGOS laser system has undergone extensive tests during Summer 2012 and is scheduled for installation at the LBT in Spring 2013. The remaining sub-systems will be installed during the course of 2013. We report on the overall status of the ARGOS system and the results of the sub-system characterizations carried out so far.

  3. 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. PMID:26998858

  4. Robotic visible-light laser adaptive optics

    NASA Astrophysics Data System (ADS)

    Baranec, Christoph; Riddle, Reed; Law, Nicholas; Ramaprakash, A. N.; Tendulkar, Shriharsh; Bui, Khanh; Burse, Mahesh; Chordia, Pravin; Das, Hillol; Dekany, Richard; Kulkarni, Shrinivas; Punnadi, Sujit

    2013-12-01

    Robo-AO is the first autonomous laser adaptive optics system and science instrument operating on sky. With minimal human oversight, the system robotically executes large scale surveys, monitors long-term astrophysical dynamics and characterizes newly discovered transients, all at the visible diffraction limit. The adaptive optics setup time, from the end of the telescope slew to the beginning of an observation, is a mere ~50-60 s, enabling over 200 observations per night. The first of many envisioned systems has finished 58 nights of science observing at the Palomar Observatory 60-inch (1.5 m) telescope, with over 6,400 robotic observations executed thus far. The system will be augmented in late 2013 with a low-noise wide field infrared camera, which doubles as a tip-tilt sensor, to widen the spectral bandwidth of observations and increase available sky coverage while also enabling deeper visible imaging using adaptive-optics sharpened infrared tip-tilt guide sources. Techniques applicable to larger telescope systems will also be tested: the infrared camera will be used to demonstrate advanced multiple region-of-interest tip-tilt guiding methods, and a visitor instrument port will be used for evaluation of other instrumentation, e.g. single-mode and photonic fibers to feed compact spectrographs.

  5. Laser flash effects on laser speckle shift visual evoked potential.

    PubMed

    Schmeisser, E T

    1985-10-01

    Steady-state visual evoked potentials (VEP's) were recorded from four cynomolgus monkeys in response to a sinusoidally oscillating 10 degrees helium-neon laser speckle field (632.8 nm), moving vertically 2.5 degrees at 8 shifts per second. A 5-pulse flash train at the maximum permissible exposure (MPE) dose from a collimated Q-switched frequency-doubled neodymium laser (532 nm) was superimposed on the foveal stimulus and the subsequent disruption and recovery of the VEP measured. Minimal disruption of the response signal magnitude was demonstrated (0.1 greater than p greater than 0.05) which recovered within 300 ms of the termination of the pulse train. A small but significant (p less than 0.01) disruption of phase entrainment was also noted that recovered within the same period. This is contrasted with a second experiment with three monkeys in which an argon (514 nm) laser served both as the speckle stimulus source and as the shuttered flash. Exposure to collimated MPE argon radiation for 250 ms immediately depressed the VEP (97%, p less than 0.01) and showed recovery to 70% of the pre-flash baseline only after 3 s. Phase lock was also severely degraded for several seconds. These results imply that visual processing of nonacuity-limited medium contrast stimuli with broad spatial frequency content will probably not be materially affected by ultra-short pulsed laser exposure at these energy levels and frequencies. However, even safe levels of collimated continuous laser light may have severe effects on vision that could parallel flash effects seen with Xenon discharge flash lamps. PMID:4073205

  6. Modes in light wave propagating in semiconductor laser

    NASA Technical Reports Server (NTRS)

    Manko, Margarita A.

    1994-01-01

    The study of semiconductor laser based on an analogy of the Schrodinger equation and an equation describing light wave propagation in nonhomogeneous medium is developed. The active region of semiconductor laser is considered as optical waveguide confining the electromagnetic field in the cross-section (x,y) and allowing waveguide propagation along the laser resonator (z). The mode structure is investigated taking into account the transversal and what is the important part of the suggested consideration longitudinal nonhomogeneity of the optical waveguide. It is shown that the Gaussian modes in the case correspond to spatial squeezing and correlation. Spatially squeezed two-mode structure of nonhomogeneous optical waveguide is given explicitly. Distribution of light among the laser discrete modes is presented. Properties of the spatially squeezed two-mode field are described. The analog of Franck-Condon principle for finding the maxima of the distribution function and the analog of Ramsauer effect for control of spatial distribution of laser emission are discussed.

  7. Singlet molecular oxygen generation by light-activated DHN-melanin of the fungal pathogen Mycosphaerella fijiensis in black Sigatoka disease of bananas.

    PubMed

    Beltrán-García, Miguel J; Prado, Fernanda M; Oliveira, Marilene S; Ortiz-Mendoza, David; Scalfo, Alexsandra C; Pessoa, Adalberto; Medeiros, Marisa H G; White, James F; Di Mascio, Paolo

    2014-01-01

    In pathogenic fungi, melanin contributes to virulence, allowing tissue invasion and inactivation of the plant defence system, but has never been implicated as a factor for host cell death, or as a light-activated phytotoxin. Our research shows that melanin synthesized by the fungal banana pathogen Mycosphaerella fijiensis acts as a virulence factor through the photogeneration of singlet molecular oxygen O2 (1Δg). Using analytical tools, including elemental analysis, ultraviolet/infrared absorption spectrophometry and MALDI-TOF mass spectrometry analysis, we characterized both pigment content in mycelia and secreted to the culture media as 1,8-dihydroxynaphthalene (DHN)-melanin type compound. This is sole melanin-type in M. fijiensis. Isolated melanins irradiated with a Nd:YAG laser at 532 nm produced monomol light emission at 1270 nm, confirming generation of O2 (1Δg), a highly reactive oxygen specie (ROS) that causes cellular death by reacting with all cellular macromolecules. Intermediary polyketides accumulated in culture media by using tricyclazole and pyroquilon (two inhibitors of DHN-melanin synthesis) were identified by ESI-HPLC-MS/MS. Additionally, irradiation at 532 nm of that mixture of compounds and whole melanized mycelium also generated O2 (1Δg). A pigmented-strain generated more O2 (1Δg) than a strain with low melanin content. Banana leaves of cultivar Cavendish, naturally infected with different stages of black Sigatoka disease, were collected from field. Direct staining of the naturally infected leaf tissues showed the presence of melanin that was positively correlated to the disease stage. We also found hydrogen peroxide (H2O2) but we cannot distinguish the source. Our results suggest that O2 (1Δg) photogenerated by DHN-melanin may be involved in the destructive effects of Mycosphaerella fijiensis on banana leaf tissues. Further studies are needed to fully evaluate contributions of melanin-mediated ROS to microbial pathogenesis. PMID:24646830

  8. Singlet Molecular Oxygen Generation by Light-Activated DHN-Melanin of the Fungal Pathogen Mycosphaerella fijiensis in Black Sigatoka Disease of Bananas

    PubMed Central

    Beltrán-García, Miguel J.; Prado, Fernanda M.; Oliveira, Marilene S.; Ortiz-Mendoza, David; Scalfo, Alexsandra C.; Pessoa, Adalberto; Medeiros, Marisa H. G.; White, James F.; Di Mascio, Paolo

    2014-01-01

    In pathogenic fungi, melanin contributes to virulence, allowing tissue invasion and inactivation of the plant defence system, but has never been implicated as a factor for host cell death, or as a light-activated phytotoxin. Our research shows that melanin synthesized by the fungal banana pathogen Mycosphaerella fijiensis acts as a virulence factor through the photogeneration of singlet molecular oxygen O2 (1Δg). Using analytical tools, including elemental analysis, ultraviolet/infrared absorption spectrophometry and MALDI-TOF mass spectrometry analysis, we characterized both pigment content in mycelia and secreted to the culture media as 1,8-dihydroxynaphthalene (DHN)-melanin type compound. This is sole melanin-type in M. fijiensis. Isolated melanins irradiated with a Nd:YAG laser at 532 nm produced monomol light emission at 1270 nm, confirming generation of O2 (1Δg), a highly reactive oxygen specie (ROS) that causes cellular death by reacting with all cellular macromolecules. Intermediary polyketides accumulated in culture media by using tricyclazole and pyroquilon (two inhibitors of DHN-melanin synthesis) were identified by ESI-HPLC-MS/MS. Additionally, irradiation at 532 nm of that mixture of compounds and whole melanized mycelium also generated O2 (1Δg). A pigmented-strain generated more O2 (1Δg) than a strain with low melanin content. Banana leaves of cultivar Cavendish, naturally infected with different stages of black Sigatoka disease, were collected from field. Direct staining of the naturally infected leaf tissues showed the presence of melanin that was positively correlated to the disease stage. We also found hydrogen peroxide (H2O2) but we cannot distinguish the source. Our results suggest that O2 (1Δg) photogenerated by DHN-melanin may be involved in the destructive effects of Mycosphaerella fijiensis on banana leaf tissues. Further studies are needed to fully evaluate contributions of melanin-mediated ROS to microbial pathogenesis. PMID:24646830

  9. Let there be light--the laser in dentistry.

    PubMed

    Mercer, C

    1992-06-20

    A damp and dull London day in March somewhat contradicted the title of the meeting of the Odontology Section of the RSM, Let there be light--the laser in dentistry, but there was no doubt, once inside, that the organisers had, with perfect timing, caught the interest of the profession as a Barnes Room packed to capacity was greeted by the president of the section, Margaret Seward. Rather apologetically, she confessed that the film Goldfinger was unavailable, but promised us equal fascination with a galaxy of international experts to guide us through a maze of new developments in laser dentistry. PMID:1616774

  10. The high frequency characteristics of laser reflection and visible light during solid state disk laser welding

    NASA Astrophysics Data System (ADS)

    Gao, Xiangdong; You, Deyong; Katayama, Seiji

    2015-07-01

    Optical properties are related to weld quality during laser welding. Visible light radiation generated from optical-induced plasma and laser reflection is considered a key element reflecting weld quality. An in-depth analysis of the high-frequency component of optical signals is conducted. A combination of a photoelectric sensor and an optical filter helped to obtain visible light reflection and laser reflection in the welding process. Two groups of optical signals were sampled at a high sampling rate (250 kHz) using an oscilloscope. Frequencies in the ranges 1-10 kHz and 10-125 kHz were investigated respectively. Experimental results showed that there was an obvious correlation between the high-frequency signal and the laser power, while the high-frequency signal was not sensitive to changes in welding speed. In particular, when the defocus position was changed, only a high frequency of the visible light signal was observed, while the high frequency of the laser reflection signal remained unchanged. The basic correlation between optical features and welding status during the laser welding process is specified, which helps to provide a new research focus for investigating the stability of welding status.

  11. EFFECT OF LASER LIGHT ON MATTER. LASER PLASMAS: Threshold for gas breakdown initiated by an interaction of laser light with aerosol particles

    NASA Astrophysics Data System (ADS)

    Borets-Pervak, I. Yu; Vorob'ev, V. S.

    1993-03-01

    A model constructed previously for plasma production through the laser heating, evaporation, and ionization of a microscopic surface defect is refined in an effort to determine the breakdown conditions in an aerosol. Simple analytic expressions are derived for the threshold laser intensity as a function of the wavelength of the laser light, the dimensions and material of the aerosol particles, the shape of the laser pulse, and the evaporated volume of the particle. The results are compared with experiments on the laser breakdown of air caused by beams from CO2 and Nd lasers in the presence of an aerosol consisting of carbon particles 0.1-25 μm in radius. The results are also compared with the predictions of the explosion model.

  12. Design of fiber optic probes for laser light scattering

    NASA Technical Reports Server (NTRS)

    Dhadwal, Harbans S.; Chu, Benjamin

    1989-01-01

    A quantitative analysis is presented of the role of optical fibers in laser light scattering. Design of a general fiber optic/microlens probe by means of ray tracing is described. Several different geometries employing an optical fiber of the type used in lightwave communications and a graded index microlens are considered. Experimental results using a nonimaging fiber optic detector probe show that due to geometrical limitations of single mode fibers, a probe using a multimode optical fiber has better performance, for both static and dynamic measurements of the scattered light intensity, compared with a probe using a single mode fiber. Fiber optic detector probes are shown to be more efficient at data collection when compared with conventional approaches to measurements of the scattered laser light. Integration of fiber optic detector probes into a fiber optic spectrometer offers considerable miniaturization of conventional light scattering spectrometers, which can be made arbitrarily small. In addition static and dynamic measurements of scattered light can be made within the scattering cell and consequently very close to the scattering center.

  13. Light assisted collisions in ultra cold Tm atom

    NASA Astrophysics Data System (ADS)

    Akimov, Alexey; Cojocaru, Ivan; Pyatchenkov, Sergey; Snigirev, Stepan; Luchnokov, Ilia; Sukachev, Denis; Kalganova, Elena; Sorokin, Vadim

    2016-05-01

    Recently laser cooled rare earth elements attracted considerable attention due to the high orbital and magnetic moments. Such a systems allow low-field Feshabach resonances enabling tunable in wide range interactions. In particular, thulium atom has one hole in 4f shell therefore having orbital moment of 3 in the ground state, magnetic moment of 4 Bohr magnetons in ground state. While magnetic moment of the thulium atom is less than that of Erbium or Dysprosium simpler level structure, possibility to capture thulium atoms and the dipole trap at 532 nm make thulium atom an extremely attractive subject for quantum simulations. Nevertheless collisional properties of thulium atom are not yet explored in details, in particular light assisted collision of thulium atom were not yet investigated. In this contribution, we performed studies of light assisted collisions near in Magneto optical trap operating on narrow 530.7 nm transition. We found, that light assisted inelastic binary collisions losses rate is around β ~10-9cm3cm3s s . Possible mechanism of losses from the trap are discussed

  14. Evaluation of a green laser pointer for flow cytometry.

    PubMed

    Habbersett, Robert C; Naivar, Mark A; Woods, Travis A; Goddard, Gregory R; Graves, Steven W

    2007-10-01

    Flow cytometers typically incorporate expensive lasers with high-quality (TEM00) output beam structure and very stable output power, significantly increasing system cost and power requirements. Red diode lasers minimize power consumption and cost, but limit fluorophore selection. Low-cost DPSS laser pointer modules could possibly offer increased wavelength selection but presumed emission instability has limited their use. A $160 DPSS 532 nm laser pointer module was first evaluated for noise characteristics and then used as the excitation light source in a custom-built flow cytometer for the analysis of fluorescent calibration and alignment microspheres. Eight of ten modules tested were very quiet (RMS noise < or = 0.6% between 0 and 5 MHz). With a quiet laser pointer module as the light source in a slow-flow system, fluorescence measurements from alignment microspheres produced CVs of about 3.3%. Furthermore, the use of extended transit times and < or =1 mW of laser power produced both baseline resolution of all 8 peaks in a set of Rainbow microspheres, and a detection limit of <20 phycoerythrin molecules per particle. Data collected with the transit time reduced to 25 micros (in the same instrument but at 2.4 mW laser output) demonstrated a detection limit of approximately 75 phycoerythrin molecules and CVs of about 2.7%. The performance, cost, size, and power consumption of the tested laser pointer module suggests that it may be suitable for use in conventional flow cytometry, particularly if it were coupled with cytometers that support extended transit times. PMID:17712796

  15. Development of a versatile laser light scattering instrument

    NASA Technical Reports Server (NTRS)

    Meyer, William V.; Ansari, Rafat R.

    1992-01-01

    NASA Lewis Research Center is providing and coordinating the technology for placing a compact Laser Light Scattering (LLS) instrument in a microgravity environment. This will be accomplished by defining and assessing user requirements for microgravity experiments, coordinating needed technological developments, and filling technical gaps. This effort is striving to brassboard and evaluate a miniature multi-angle LLS instrument. The progress of the program is reported.

  16. Laser-activated remote phosphor light engine for projection applications

    NASA Astrophysics Data System (ADS)

    Daniels, Martin; Mehl, Oliver; Hartwig, Ulrich

    2015-09-01

    Recent developments in blue emitting laser diodes enable attractive solutions in projection applications using phosphors for efficient light conversion with very high luminance levels. Various commercially available projectors incorporating this technology have entered the market in the past years. While luminous flux levels are still comparable to lamp-based systems, lifetime expectations of classical lamp systems are exceeded by far. OSRAM GmbH has been exploring this technology for several years and has introduced the PHASER® brand name (Phosphor + laser). State-of-the-art is a rotating phosphor wheel excited by blue laser diodes to deliver the necessary primary colors, either sequentially for single-imager projection engines, or simultaneously for 3-panel systems. The PHASER® technology enables flux and luminance scaling, which allows for smaller imagers and therefore cost-efficient projection solutions. The resulting overall efficiency and ANSI lumen specification at the projection screen of these systems is significantly determined by the target color gamut and the light transmission efficiency of the projection system. With increasing power and flux level demand, thermal issues, especially phosphor conversion related, dominate the opto-mechanical system design requirements. These flux levels are a great challenge for all components of an SSL-projection system (SSL:solid-state lighting). OSRAḾs PHASER® light engine platform is constantly expanded towards higher luminous flux levels as well as higher luminance levels for various applications. Recent experiments employ blue laser pump powers of multiple 100 Watts to excite various phosphors resulting in luminous flux levels of more than 40 klm.

  17. Fiber optic detector probes for laser light scattering

    NASA Technical Reports Server (NTRS)

    Dhadwal, Harbans S.; Wu, Chi; Chu, Benjamin

    1989-01-01

    An experimental investigation of the role of fiber optic detector probes in laser light scattering is presented. A quantitative comparison between different detector configurations is accomplished by measuring the time taken for one million photocounts to be accumulated in the extrapolated zeroth delay channel of the net unnormalized intensity time correlation function. A considerable reduction in the accumulation time is achieved by relaxing a rather stringent requirement for the spatial coherence of the optical field.

  18. LIGHT - from laser ion acceleration to future applications

    NASA Astrophysics Data System (ADS)

    Roth, Markus; Light Collaboration

    2013-10-01

    Creation of high intensity multi-MeV ion bunches by high power lasers became a reliable tool during the last 15 years. The laser plasma source provides for TV/m accelerating field gradients and initially sub-ps bunch lengths. However, the large envelope divergence and the continuous exponential energy spectrum are substential drawbacks for many possible applications. To face this problem, the LIGHT collaboration was founded (Laser Ion Generation, Handling and Transport). The collaboration consists of several university groups and research centers, namely TU Darmstadt, JWGU Frankfurt, HI Jena, HZDR Dresden and GSI Darmstadt. The central goal is building a test beamline for merging laser ion acceleration with conventional accelerator infrastructure at the GSI facility. In the latest experiments, low divergent proton bunches with a central energy of up to 10 MeV and containing >109 particles could be provided at up to 2.2 m behind the plasma source, using a pulsed solenoid. In a next step, a radiofrequency cavity will be added to the beamline for phase rotation of these bunches, giving access to sub-ns bunch lengths and reaching highest intensities. An overview of the LIGHT objectives and the recent experimental results will be given. This work was supported by HIC4FAIR.

  19. Cooperative phenomena in two-pulse, two-color laser photocoagulation of cutaneous blood vessels.

    PubMed

    Barton, J K; Frangineas, G; Pummer, H; Black, J F

    2001-06-01

    A novel laser system has been developed to study the effects of multiple laser pulses of differing wavelengths on cutaneous blood vessels in vivo, using the hamster dorsal skin flap preparation and in vitro, using cuvettes of whole or diluted blood. The system permits sequenced irradiation with well-defined intrapulse spacing at 532 nm, using a long-pulse frequency-doubled Nd:YAG laser, and at 1064 nm, using a long-pulse Nd:YAG laser. Using this system, we have identified a parameter space where two pulses of different wavelengths act in a synergistic manner to effect permanent vessel damage at radiant exposures where the two pulses individually have little or no effect. Using a two-color pump-probe technique in vitro, we have identified a phenomenon we call greenlight-induced infrared absorption, where a pulse of green light causes photochemical and photothermal modifications to the chemical constituents of blood and results in enhanced infrared absorption. We identify a new chemical species, met-hemoglobin, not normally present in healthy human blood but formed during laser photocoagulation which we believe is implicated in the enhanced near-infrared absorption. PMID:11421070

  20. Targeted gene transfer into rat facial muscles by nanosecond pulsed laser-induced stress waves.

    PubMed

    Kurita, Akihiro; Matsunobu, Takeshi; Satoh, Yasushi; Ando, Takahiro; Sato, Shunichi; Obara, Minoru; Shiotani, Akihiro

    2011-09-01

    We investigate the feasibility of using nanosecond pulsed laser-induced stress waves (LISWs) for gene transfer into rat facial muscles. LISWs are generated by irradiating a black natural rubber disk placed on the target tissue with nanosecond pulsed laser light from the second harmonics (532 nm) of a Q-switched Nd:YAG laser, which is widely used in head and neck surgery and proven to be safe. After injection of plasmid deoxyribose nucleic acid (DNA) coding for Lac Z into rat facial muscles, pulsed laser is used to irradiate the laser target on the skin surface without incision or exposure of muscles. Lac Z expression is detected by X-gal staining of excised rat facial skin and muscles. Strong Lac Z expression is observed seven days after gene transfer, and sustained for up to 14 days. Gene transfer is achieved in facial muscles several millimeters deep from the surface. Gene expression is localized to the tissue exposed to LISWs. No tissue damage from LISWs is observed. LISW is a promising nonviral target gene transfer method because of its high spatial controllability, easy applicability, and minimal invasiveness. Gene transfer using LISW to produce therapeutic proteins such as growth factors could be used to treat nerve injury and paralysis. PMID:21950944

  1. Targeted gene transfer into rat facial muscles by nanosecond pulsed laser-induced stress waves

    NASA Astrophysics Data System (ADS)

    Kurita, Akihiro; Matsunobu, Takeshi; Satoh, Yasushi; Ando, Takahiro; Sato, Shunichi; Obara, Minoru; Shiotani, Akihiro

    2011-09-01

    We investigate the feasibility of using nanosecond pulsed laser-induced stress waves (LISWs) for gene transfer into rat facial muscles. LISWs are generated by irradiating a black natural rubber disk placed on the target tissue with nanosecond pulsed laser light from the second harmonics (532 nm) of a Q-switched Nd:YAG laser, which is widely used in head and neck surgery and proven to be safe. After injection of plasmid deoxyribose nucleic acid (DNA) coding for Lac Z into rat facial muscles, pulsed laser is used to irradiate the laser target on the skin surface without incision or exposure of muscles. Lac Z expression is detected by X-gal staining of excised rat facial skin and muscles. Strong Lac Z expression is observed seven days after gene transfer, and sustained for up to 14 days. Gene transfer is achieved in facial muscles several millimeters deep from the surface. Gene expression is localized to the tissue exposed to LISWs. No tissue damage from LISWs is observed. LISW is a promising nonviral target gene transfer method because of its high spatial controllability, easy applicability, and minimal invasiveness. Gene transfer using LISW to produce therapeutic proteins such as growth factors could be used to treat nerve injury and paralysis.

  2. Laser ablation of CFRP using picosecond laser pulses at different wavelengths from UV to IR

    NASA Astrophysics Data System (ADS)

    Wolynski, Alexander; Herrmann, Thomas; Mucha, Patrick; Haloui, Hatim; L'huillier, Johannes

    Laser processing of carbon fibre reinforced plastics (CFRP) has a great industrial relevance for high performance structural parts in airplanes, machine tools and cars. Through-holes drilled by nanosecond laser pulses show thermal induced molten layers and voids. Recently, picosecond lasers have demonstrated the ability to drill high-efficient and high-quality rivet through-holes. In this paper a high-power picosecond laser system operating at different wavelengths (355 nm, 532 nm and 1064 nm) has been used for CFRP ablation experiments to study the influence of different laser parameters in terms of machining quality and processing time.

  3. Single- and dual-wavelength laser pulses induced modification in 10×(Al/Ti)/Si multilayer system

    NASA Astrophysics Data System (ADS)

    Salatić, B.; Petrović, S.; Peruško, D.; Čekada, M.; Panjan, P.; Pantelić, D.; Jelenković, B.

    2016-01-01

    The surface morphology of the ablation craters created in the multilayer 10×(Al/Ti)/Si system by nanosecond laser pulses at single- and dual wavelength has been studied experimentally and numerically. A complex multilayer thin film including ten (Al/Ti) bilayers deposited by ion sputtering on Si(1 0 0) substrate to a total thickness of 260 nm were illuminated at different laser irradiance in the range 0.25-3.5 × 109 W cm-2. Single pulse laser irradiation was done at normal incidence in air, with the single wavelength, either at 532 nm or 1064 nm or with both laser light simultaneously in the ratio of 1:10 for energy per pulse between second harmonic and 1064 nm. Most of the absorbed laser energy was rapidly transformed into heat, producing intensive modifications of composition and morphology on the sample surface. The results show an increase in surface roughness, formation of specific nanostructures, appearance of hydrodynamic features and ablation of surface material with crater formation. Applying a small fraction (10%) of the second harmonic in dual-wavelength pulses, a modification of the 10×(Al/Ti)/Si system by a single laser pulse was reflected in the formation of wider and/or deeper craters. Numerical calculations show that the main physical mechanism in ablation process is normal evaporation without phase explosion. The calculated and experimental results agree relatively well for the whole irradiance range, what makes the model applicable to complex Al/Ti multilayer systems.

  4. Soft x ray optics by pulsed laser deposition

    NASA Technical Reports Server (NTRS)

    Fernandez, Felix E.

    1994-01-01

    A series of molybdenum thin film depositions by PLD (Pulsed Laser Deposition) have been carried out, seeking appropriate conditions for multilayer fabrication. Green (532 nm) and UV (355 nm) light pulses, in a wide range of fluences, were used. Relatively large fluences (in comparison with Si) are required to cause evaporation of molybdenum. The optical penetration depths and reflectivities for Mo at these two wavelengths are comparable, which means that results should be, and do appear to be similar for equal fluences. For all fluences above threshold used, a large number of incandescent particles is ejected by the target (either a standard Mo sputtering target or a Mo sheet were tried), together with the plasma plume. Most of these particles are clearly seen to bounce off the substrate. The films were observed with light microscopy using Nomarski and darkfield techniques. There is no evidence of large debris. Smooth films plus micron-sized droplets are usually seen. The concentration of these droplets embedded in the film appears not to vary strongly with the laser fluence employed. Additional characterization with SEM and XRD is under way.

  5. Influence of pulsed Nd3+ : YAG laser beam profile and wavelength on microscribing of copper and aluminum thin films

    NASA Astrophysics Data System (ADS)

    Nammi, Srinagalakshmi; Vasa, Nilesh J.; Balaganesan, G.; Gupta, Sanjay; Mathur, Anil C.

    2015-10-01

    Evenly spaced conductive grids of copper and aluminum thin films on polyimide substrate are used for parabolic reflector antennas aboard telecommunications satellites. Laser microscribing of thin films using a flat-top and Gaussian laser beam profile is analyzed with 95% overlapping of the diameter of the laser spot. Laser scribing is performed using the Q-switched Nd3+: YAG (355, 532 nm) laser. The influence of laser irradiation and beam shape on the scribed microchannel width, depth, and surface characteristics is experimentally analyzed using a noncontact optical profilometer and scanning electron microscope (SEM). Laser scribing using a flat-top profile produced near rectangular microchannels in copper thin films. Using the Gaussian profile, the probability of melting is greater than vaporization as observed using SEM images; this melt pool plays a prominent role in resolidification at the edges. The depth of the scribe channel is observed to be 20% higher for the 532-nm wavelength compared to the 355-nm wavelength. The effect of different environments such as air, water, and vacuum on the channel depth and quality is reported. The response of aluminum and copper thin films for high fluences is also studied. Thermal modeling of the laser-material interaction has been attempted by assuming the plasma electron temperature as the laser ablation temperature for modeling the recession rate and depth for a single laser pulse. Model results agree with experimental data showing greater depth for 532 nm compared to 355 nm.

  6. High luminance low etendue white light source using blue laser over static phosphor

    NASA Astrophysics Data System (ADS)

    Farooq, Tayyab; Qian, KeYuan

    2015-10-01

    A High Luminance White Light source for Etendue limited application has been demonstrated in this research paper by using blue InGaN laser diode beam over static source of phosphor Ce: YAG layer. Phosphor target has kept static because moving phosphor target light output is not constant and uniform. Different color temperatures had been obtained by varying phosphor concentration and thickness of the layer. When laser beam has focused on phosphor target spot, it induced very high temperature at that spot area. Temperature induced in the layer by laser beam depends on the layer thickness. All the layer thickness, surface temperature, output light flux, efficiency, and light color temperature are interrelate with each other. Uniform laser beam distribution, surface temperature, laser spot size, phosphor layer thickness are successfully calculated. Luminous efficiency, light color temperature, flux, wavelength spectrum, and light output power of laser driven white light source had been successfully observed at different laser beam powers.

  7. Micromachining of polydimethylsiloxane induced by laser plasma EUV light

    NASA Astrophysics Data System (ADS)

    Torii, S.; Makimura, T.; Okazaki, K.; Nakamura, D.; Takahashi, A.; Okada, T.; Niino, H.; Murakami, K.

    2011-06-01

    Polydimethylsiloxane (PDMS) is fundamental materials in the field of biotechnology. Because of its biocompatibility, microfabricated PDMS sheets are applied to micro-reactors and microchips for cell culture. Conventionally, the microstructures were fabricated by means of cast or imprint using molds, however it is difficult to fabricate the structures at high aspect ratios such as through-holes/vertical channels. The fabrication of the high-aspect structures would enable us to stack sheets to realize 3D fluidic circuits. In order to achieve the micromachining, direct photo-ablation by short wavelength light is promising. In the previous works, we investigated ablation of transparent materials such as silica glass and poly(methyl methacrylate) induced by irradiation with laser plasma EUV light. We achieved smooth and fine nanomachining. In this work, we applied our technique to PDMS micromachining. We condensed the EUV light onto PDMS surfaces at high power density up to 108 W/cm2 using a Au coated ellipsoidal mirror. We found that PDMS sheet was ablated at a rate up to 440 nm/shot. It should be emphasized that through hole with a diameter of 1 μm was fabricated in a PDMS sheet with a thickness of 4 μm. Thus we demonstrated the micromachining of PDMS sheets using laser plasma EUV light.

  8. Frequency determination of visible laser light by interferometric comparison with upconverted CO(2) laser radiation.

    PubMed

    Woods, P T; Shotton, K C; Rowley, W R

    1978-04-01

    A servocontrolled 1-m plane-parallel Fabry-Perot interferometer has been developed at NPL for the precise intercomparison of laser wavelengths. This instrument has been used to measure the wavelength ratio of a 679-nm radiation and that from a 633-nm iodine-stabilized He-Ne laser, achieving an accuracy of 2.9 parts in 10(11). The 679-nm light was derived from a stabilized CO(2) laser radiation by upconversion, and the wavelength of this 9.3-microm laser radiation can be calculated from the visible wavelength result. Frequency measurements on the same CO(2) laser radiation have already been made in this laboratory, so that the experiment reported here leads to a precise value for the speed of light in vacuum and to the value of 473, 612, 380.5 +/- 0.3 MHz for the absolute frequency of the visible radiation from a He-Ne laser stabilized to component d of (127)I(2). PMID:20197930

  9. Laser light scattering as a probe of fractal colloid aggregates

    NASA Technical Reports Server (NTRS)

    Weitz, David A.; Lin, M. Y.

    1989-01-01

    The extensive use of laser light scattering is reviewed, both static and dynamic, in the study of colloid aggregation. Static light scattering enables the study of the fractal structure of the aggregates, while dynamic light scattering enables the study of aggregation kinetics. In addition, both techniques can be combined to demonstrate the universality of the aggregation process. Colloidal aggregates are now well understood and therefore represent an excellent experimental system to use in the study of the physical properties of fractal objects. However, the ultimate size of fractal aggregates is fundamentally limited by gravitational acceleration which will destroy the fractal structure as the size of the aggregates increases. This represents a great opportunity for spaceborne experimentation, where the reduced g will enable the growth of fractal structures of sufficient size for many interesting studies of their physical properties.

  10. Processing condition influence on the characteristics of gold nanoparticles produced by pulsed laser ablation in liquids

    NASA Astrophysics Data System (ADS)

    Nikov, R. G.; Nikolov, A. S.; Nedyalkov, N. N.; Atanasov, P. A.; Alexandrov, M. T.; Karashanova, D. B.

    2013-06-01

    A study is presented of Au nanoparticles (NPs) created by nanosecond pulsed laser ablation of a solid target in double distilled water. The influence was examined of the laser wavelength on the size, shape and optical properties of the resulting NPs. Three different wavelengths: the fundamental (λ = 1064 nm), second (λSHG = 532) and third (λTHG = 355) harmonic of a Nd:YAG laser at the same fluence were utilized to produce various colloids. Ablation at the wavelength of 532 nm was investigated in more detail to reveal the influence of self-absorption by the already created NPs on their characteristics. The colloid produced was irradiated by λirrad = 532 nm (laser energy 40 mJ) at different times up to 25 min after the end of ablation. The initial structure of welded NPs forming wires was modified. Transmission electron microscopy and optical transmission measurements were used to evaluate the shape and size distribution of the NPs.

  11. Transcutaneous laser treatment of leg veins.

    PubMed

    Meesters, Arne A; Pitassi, Luiza H U; Campos, Valeria; Wolkerstorfer, Albert; Dierickx, Christine C

    2014-03-01

    Leg telangiectasias and reticular veins are a common complaint affecting more than 80% of the population to some extent. To date, the gold standard remains sclerotherapy for most patients. However, there may be some specific situations, where sclerotherapy is contraindicated such as needle phobia, allergy to certain sclerosing agents, and the presence of vessels smaller than the diameter of a 30-gauge needle (including telangiectatic matting). In these cases, transcutaneous laser therapy is a valuable alternative. Currently, different laser modalities have been proposed for the management of leg veins. The aim of this article is to present an overview of the basic principles of transcutaneous laser therapy of leg veins and to review the existing literature on this subject, including the most recent developments. The 532-nm potassium titanyl phosphate (KTP) laser, the 585-600-nm pulsed dye laser, the 755-nm alexandrite laser, various 800-983-nm diode lasers, and the 1,064-nm neodymium yttrium-aluminum-garnet (Nd:YAG) laser and various intense pulsed light sources have been investigated for this indication. The KTP and pulsed dye laser are an effective treatment option for small vessels (<1 mm). The side effect profile is usually favorable to that of longer wavelength modalities. For larger veins, the use of a longer wavelength is required. According to the scarce evidence available, the Nd:YAG laser produces better clinical results than the alexandrite and diode laser. Penetration depth is high, whereas absorption by melanin is low, making the Nd:YAG laser suitable for the treatment of larger and deeply located veins and for the treatment of patients with dark skin types. Clinical outcome of Nd:YAG laser therapy approximates that of sclerotherapy, although the latter is associated with less pain. New developments include (1) the use of a nonuniform pulse sequence or a dual-wavelength modality, inducing methemoglobin formation and enhancing the optical absorption

  12. Possibility of methane conversion into heavier hydrocarbons using nanosecond lasers

    NASA Astrophysics Data System (ADS)

    Navid, H. A.; Irani, E.; Sadighi-Bonabi, R.

    2016-03-01

    Effect of nanosecond lasers on the methane dissociation is experimentally studied by using three different laser wavelengths at 248 nm, 355 nm and 532 nm. C2H2 generation is measured as a major reaction product in experiments and the energy consumptions in production of this component are measured as 5.8 MJ/mol, 3.1 MJ/mol and 69.0 MJ/mol, for 355 nm, 532 nm and 248 nm wavelengths, respectively. The mechanism of conversion and production of new stable hydrocarbons is also theoretically investigated. It is found that in theoretical calculations, the ion-molecule reactions should be included and this leads to a unique approach in proper explanation of the experimental measurements.

  13. Possibility of methane conversion into heavier hydrocarbons using nanosecond lasers.

    PubMed

    Navid, H A; Irani, E; Sadighi-Bonabi, R

    2016-03-01

    Effect of nanosecond lasers on the methane dissociation is experimentally studied by using three different laser wavelengths at 248 nm, 355 nm and 532 nm. C2H2 generation is measured as a major reaction product in experiments and the energy consumptions in production of this component are measured as 5.8 MJ/mol, 3.1 MJ/mol and 69.0 MJ/mol, for 355 nm, 532 nm and 248 nm wavelengths, respectively. The mechanism of conversion and production of new stable hydrocarbons is also theoretically investigated. It is found that in theoretical calculations, the ion-molecule reactions should be included and this leads to a unique approach in proper explanation of the experimental measurements. PMID:26655072

  14. Spectroscopic studies of magnesium plasma produced by fundamental and second harmonics of Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Haq, S. U.; Ahmat, L.; Mumtaz, M.; Shakeel, Hira; Mahmood, S.; Nadeem, A.

    2015-08-01

    In the present experimental work, laser induced magnesium plasma has been characterized using plasma parameters. The plasma has been generated by the fundamental (1064 nm) and second harmonics (532 nm) of Nd:YAG laser. The plasma parameters such as electron temperature and electron number density have been extracted using Boltzmann plot method and Stark broadened line profile, respectively. The laser irradiance dependence and spatial behavior of electron temperature and number density in laser induced magnesium plasma have been studied. The electron temperature as a function of laser irradiance (0.5 to 6.5 GW/cm2) ranges from (9.16-10.37) × 103 K and (8.5-10.1)× 103 K, and electron number density from (0.99-1.08) × 1016 cm-3 and (1.04-1.22) × 1016cm-3 for 1064 and 532 nm, respectively. These parameters exhibit fast increase at low laser irradiance and slow increase at high irradiance. The spatial distribution of electron temperature and electron number density shows same decreasing trend up to 2.25 mm from the target surface. The electron temperature and number density decrease from (9.5-8.6) × 103 K, (1.27-1.15) × 1016cm-3 and (10.56-8.85)× 103 K, (1.08-0.99) × 1016 cm-3 for 532 nm and 1064 nm laser ablation wavelengths, respectively.

  15. Analysis of natural and artificial ultramarine blue pigments using laser induced breakdown and pulsed Raman spectroscopy, statistical analysis and light microscopy.

    PubMed

    Osticioli, I; Mendes, N F C; Nevin, A; Gil, Francisco P S C; Becucci, M; Castellucci, E

    2009-08-01

    Pulsed laser induced breakdown spectroscopy (LIBS) and Raman spectroscopy were performed using a novel laboratory setup employing the same Nd:YAG laser emission at 532 nm for the analysis of five commercially available pigments collectively known as "ultramarine blue", a sodium silicate material of either mineral origin or an artificially produced glass. LIBS and Raman spectroscopy have provided information regarding the elemental and molecular composition of the samples; additionally, an analytical protocol for the differentiation between natural (lapis lazuli) and artificial ultramarine blue pigments is proposed. In particular LIBS analysis has allowed the discrimination between pigments on the basis of peaks ascribed to calcium. The presence of calcite in the natural blue pigments has been confirmed following Raman spectroscopy in specific areas of the samples, and micro-Raman and optical microscopy have further corroborated the presence of calcite inclusions in the samples of natural origin. Finally multivariate analysis of Laser induced breakdown spectra using principal component analysis (PCA) further enhanced the differentiation between natural and artificial ultramarine blue pigments. PMID:19129003

  16. Analysis of natural and artificial ultramarine blue pigments using laser induced breakdown and pulsed Raman spectroscopy, statistical analysis and light microscopy

    NASA Astrophysics Data System (ADS)

    Osticioli, I.; Mendes, N. F. C.; Nevin, A.; Gil, Francisco P. S. C.; Becucci, M.; Castellucci, E.

    2009-08-01

    Pulsed laser induced breakdown spectroscopy (LIBS) and Raman spectroscopy were performed using a novel laboratory setup employing the same Nd:YAG laser emission at 532 nm for the analysis of five commercially available pigments collectively known as "ultramarine blue", a sodium silicate material of either mineral origin or an artificially produced glass. LIBS and Raman spectroscopy have provided information regarding the elemental and molecular composition of the samples; additionally, an analytical protocol for the differentiation between natural (lapis lazuli) and artificial ultramarine blue pigments is proposed. In particular LIBS analysis has allowed the discrimination between pigments on the basis of peaks ascribed to calcium. The presence of calcite in the natural blue pigments has been confirmed following Raman spectroscopy in specific areas of the samples, and micro-Raman and optical microscopy have further corroborated the presence of calcite inclusions in the samples of natural origin. Finally multivariate analysis of Laser induced breakdown spectra using principal component analysis (PCA) further enhanced the differentiation between natural and artificial ultramarine blue pigments.

  17. The influence of femtosecond laser pulse wavelength on embryonic stem cell differentiation

    NASA Astrophysics Data System (ADS)

    Mthunzi, Patience

    2012-10-01

    Stem cells are rich in proteins, carbohydrates, deoxyribonucleic acid (DNA), ribonucleic acid (RNA) and various other cellular components which are responsible for a diversity of functions. Mostly the building blocks of these intracellular entities play an active role in absorbing ultra-violet (UV) and visible light sources. Light-matter interactions in biomaterials are a complex situation and subsequent damage may not always amount only from wavelength dependent effects but may also be driven by a wealth of other optical parameters which may lead to a variety photochemical reactions. Previously, literature has reported efficient photo-transfection and differentiation of pluripotent stem cells via near infrared (NIR) femtosecond (fs) laser pulses with minimum compromise to their viability. Therefore, in this study the influence of using different fs laser wavelengths on optical stem cell transfection and differentiation is investigated. A potassium titanyl phosphate (KTP) crystal was employed in frequency doubling a 1064 nm fs laser beam. The newly generated 532 nm fs pulsed beam was then utilized for the first time in transient photo-transfection of ES-E14TG2a mouse embryonic stem (mES) cells. Compared to using 1064 nm fs pulses which non-invasively introduce plasmid DNA and other macromolecules into mES cells, our results showed a significant decline in the photo-transfection efficiency following transfecting with a pulsed fs visible green beam.

  18. Influence of laser wavelength on the laser induced breakdown spectroscopy measurement of thin CuIn 1- xGaxSe2 solar cell films

    NASA Astrophysics Data System (ADS)

    Kim, Chan Kyu; In, Jung Hwan; Lee, Seok Hee; Jeong, Sungho

    2013-10-01

    Laser induced breakdown spectroscopy (LIBS) measurement of thin CuInxGa 1- xSe2 (CIGS) films (1.2-1.9 μm) with varying Ga to In ratios was carried out using the fundamental (1064 nm) and second harmonic (532 nm) wavelength Nd:YAG lasers (τ = 5 ns, spot diameter = 150 μm, top-hat profile) in air. The concentration ratios of Ga to In, xGa ≡ Ga/(Ga + In), of the CIGS samples ranged from 0.027 to 0.74 for which the band gap varied nearly proportionally to xGa from 0.96 to 1.42. It was found that the LIBS signal of 1064 nm (1.17 eV) wavelength laser was significantly influenced by xGa, whereas that of the 532 nm (2.34 eV) laser was consistent for all values of xGa. The observed dependency of the LIBS signal intensity on the laser wavelength was attributed to the large difference of photon energy of the two wavelengths that changed the absorption of incident laser energy by the film. The 532 nm wavelength was found to be advantageous for multi-shot analysis that enabled depth profile analysis of the thin CIGS films and for improving measurement precision by averaging the multi-shot LIBS spectra.

  19. Laser light triggered-activated carbon nanosystem for cancer therapy.

    PubMed

    Chu, Maoquan; Peng, Jinliang; Zhao, Jiajia; Liang, Shanlu; Shao, Yuxiang; Wu, Qiang

    2013-02-01

    Among carbon-based nanomaterials, activated carbon (AC) may be an ideal candidate as a carrier for tumor therapeutic agents. Here we found a new property of nanoscale activated carbon (NAC) with narrow size distribution, namely the rapid conversion of light to thermal energy both in vitro and in vivo. An aqueous suspension of 200 μL of NAC (1 mg/mL) exhibited a rapid temperature increase of more than 35 °C after irradiation for 20 min with a 655-nm laser; this was within the temperature range for effective tumor treatment. We demonstrated that lung cancer cells (H-1299) incubated with bamboo nano-AC (BNAC) were killed with high efficiency after laser irradiation. In addition, mouse tumors with sizes smaller than the laser spot that had been injected with BNAC disappeared after irradiation. For tumors larger than the laser spot area, the incorporation of the photosensitizer ZnPc obviously increased the tumor growth inhibition efficiency of BNAC. BNAC-ZnPc was found to exhibit a synergistic effect when photothermal and photodynamic therapies were administered in combination. These results indicated that NAC can be used for high efficiency cancer phototherapy. PMID:23228422

  20. Energy Dependent Processing of Fiber Reinforced Plastics with Ultra Short Laser Pulses

    NASA Astrophysics Data System (ADS)

    Schilling, N.; Lasagni, A.; Klotzbach, U.

    In this paper the processing of a fiber reinforced plastic consisting of glass fibers embedded in polypropylene with ultra short laser systems is shown. Focus of the study is on the dependence of working wavelength (1064 nm, 532 nm and 355 nm) and pulse duration (500 fs to 10 ps) on the laser ablation characteristic of the treated material. Depending on the energy density and the material properties, two different process regions could be identified.

  1. Single-frequency, fully integrated, miniature DPSS laser based on monolithic resonator

    NASA Astrophysics Data System (ADS)

    Dudzik, G.; Sotor, J.; Krzempek, K.; Soboń, G.; Abramski, K. M.

    2014-02-01

    We present a single frequency, stable, narrow linewidth, miniature laser sources operating at 532 nm (or 1064 nm) based on a monolithic resonators. Such resonators utilize birefringent filters formed by YVO4 beam displacer and KTP or YVO4 crystals to force single frequency operation at 532 nm or 1064 nm, respectively. In both configurations Nd:YVO4 gain crystal is used. The resonators dimensions are 1x1x10.5 mm3 and 1x1x8.5 mm3 for green and infrared configurations, respectively. Presented laser devices, with total dimensions of 40x52x120 mm3, are fully equipped with driving electronics, pump diode, optical and mechanical components. The highly integrated (36x15x65 mm3) low noise driving electronics with implemented digital PID controller was designed. It provides pump current and resonator temperature stability of ±30 μA@650 mA and ±0,003ºC, respectively. The laser parameters can be set and monitored via the USB interface by external application. The developed laser construction is universal. Hence, the other wavelengths can be obtained only by replacing the monolithic resonator. The optical output powers in single frequency regime was at the level of 42 mW@532 nm and 0.5 W@1064 nm with the long-term fluctuations of ±0.85 %. The linewidth and the passive frequency stability under the free running conditions were Δν < 100 kHz and 3ṡ10-9@1 s integration time, respectively. The total electrical power supply consumption of laser module was only 4 W. Presented compact, single frequency laser operating at 532 nm and 1064 nm may be used as an excellent source for laser vibrometry, interferometry or seed laser for fiber amplifiers.

  2. Spectrum of reflected light by self-focusing of light in a laser plasma

    SciTech Connect

    Gorbunov, L.M.

    1983-05-01

    The spectrum of the radiation reflected by a laser-produced plasma is considered. In this situation, self-focusing occurs and a region of low density (caviton) is formed. It is shown that the process leads to a considerable broadening of the spectrum on the ''red'' side, and to the appearance of a line structure in the spectrum. The results can explain data for the reflected light spectrum (L. M. Gorbunov et al., FIAN Preprint No. 126 (1979)) as being due to the nonstationary self-focusing of light in a laser-produced plasma that has recently been observed (V. L. Artsimovich et al., FIAN Preprint No. 252 (1981); Sov. Phys. Doklady 27, 618 (1982)).

  3. Light-curing polymers for laser plasma generation

    NASA Astrophysics Data System (ADS)

    Loktionov, E. Y.; Protasov, Y. S.; Protasov, Y. Y.; Telekh, V. D.

    2015-07-01

    Solid rather than liquid media are used in pulsed laser plasma generators despite sophisticated transportation and dosing system need for a long-term operation. Liquid media could be more preferable due to transfer and dosing (down to 10-14 L) being well developed, but plasma generation of those results in intense droplet formation and kinetic energy losses. Combination of liquids transportation advantages and solids plasma generation efficiency might resolve this trade-off. Liquid-to-solid transition can be induced by cooling down to sublimation temperature, thermo-, photo- or electron induced polymerization (curing). Light cured polymers seem to be very useful as active media for plasma generators, since they can be solidified very fast (ca. 30 ms) just before impact. We considered experimentally several UV- curing polymer and mixtures ablation regimes and supply schemes for laser plasma generation. The best results were obtained for liquid polymer at high-power pulsed irradiation matching curing optimum wavelength.

  4. Development of a broadband reflectivity diagnostic for laser driven shock compression experiments

    DOE PAGESBeta

    Ali, S. J.; Bolme, C. A.; Collins, G. W.; Jeanloz, R.

    2015-04-01

    A normal - incidence visible and near - infrared Shock Wave Optical Reflectivity Diagnostic (SWORD) was constructed to investigate changes in the optical properties of materials under dynamic laser compression . Documenting wavelength - and time - dependent changes in the optical properties of laser - shock compressed samples has been difficult, primarily due to the small sample sizes and short time scales involved , but we succeeded in doing so by broadening a series of time delayed 800 - nm pulses from an ultra fast Ti: sapphire laser to generate high - intensity broadband light at nanosecond time scalesmore » . This diagnostic was demonstrated over the wavelength range 450 to 1150 nm with up to 16 time displaced spectra during a single shock experiment. Simultaneous off - normal incidence velocity interferometry (VISAR) characterize d the sample under laser - compression , and also provide d a n independent reflectivity measurement at 532 nm wavelength . Lastly, the shock - driven semiconductor - to - metallic transition in germanium was documented by way of reflectivity measurements with 0.5 ns time resolution and a wavelength resolution of 10 nm .« less

  5. Elimination of leukemic cells from human transplants by laser nano-thermolysis

    NASA Astrophysics Data System (ADS)

    Lapotko, Dmitri; Lukianova, Ekaterina; Potapnev, Michail; Aleinikova, Olga; Oraevsky, Alexander

    2006-02-01

    We describe novel ex vivo method for elimination of tumor cells from bone marrow and blood, Laser Activated Nano-Thermolysis for Cell Elimination Technology (LANTCET) and propose this method for purging of transplants during treatment of leukemia. Human leukemic cells derived from real patients with different diagnoses (acute lymphoblastic leukemias) were selectively damaged by LANTCET in the experiments by laser-induced micro-bubbles that emerge inside individual specifically-targeted cells around the clusters of light-absorbing gold nanoparticles. Pretreatment of the transplants with diagnosis-specific primary monoclonal antibodies and gold nano-particles allowed the formation of nanoparticle clusters inside leukemic cells only. Electron microscopy found the nanoparticulate clusters inside the cells. Total (99.9%) elimination of leukemic cells targeted with specific antibodies and nanoparticles was achieved with single 10-ns laser pulses with optical fluence of 0.2 - 1.0 J/cm2 at the wavelength of 532 nm without significant damage to normal bone marrow cells in the same transplant. All cells were studied for the damage/viability with several control methods after their irradiation by laser pulses. Presented results have proved potential applicability of developed LANTCET technology for efficient and safe purging (cleaning of residual tumor cells) of human bone marrow and blood transplants. Design of extra-corporeal system was proposed that can process the transplant for one patient for less than an hour with parallel detection and counting residual leukemic cells.

  6. Development of a broadband reflectivity diagnostic for laser driven shock compression experiments

    SciTech Connect

    Ali, S. J.; Bolme, C. A.; Collins, G. W.; Jeanloz, R.

    2015-04-01

    A normal - incidence visible and near - infrared Shock Wave Optical Reflectivity Diagnostic (SWORD) was constructed to investigate changes in the optical properties of materials under dynamic laser compression . Documenting wavelength - and time - dependent changes in the optical properties of laser - shock compressed samples has been difficult, primarily due to the small sample sizes and short time scales involved , but we succeeded in doing so by broadening a series of time delayed 800 - nm pulses from an ultra fast Ti: sapphire laser to generate high - intensity broadband light at nanosecond time scales . This diagnostic was demonstrated over the wavelength range 450 to 1150 nm with up to 16 time displaced spectra during a single shock experiment. Simultaneous off - normal incidence velocity interferometry (VISAR) characterize d the sample under laser - compression , and also provide d a n independent reflectivity measurement at 532 nm wavelength . Lastly, the shock - driven semiconductor - to - metallic transition in germanium was documented by way of reflectivity measurements with 0.5 ns time resolution and a wavelength resolution of 10 nm .

  7. Development of a broadband reflectivity diagnostic for laser driven shock compression experiments

    NASA Astrophysics Data System (ADS)

    Ali, S. J.; Bolme, C. A.; Collins, G. W.; Jeanloz, R.

    2015-04-01

    A normal-incidence visible and near-infrared shock wave optical reflectivity diagnostic was constructed to investigate changes in the optical properties of materials under dynamic laser compression. Documenting wavelength- and time-dependent changes in the optical properties of laser-shock compressed samples has been difficult, primarily due to the small sample sizes and short time scales involved, but we succeeded in doing so by broadening a series of time delayed 800-nm pulses from an ultrafast Ti:sapphire laser to generate high-intensity broadband light at nanosecond time scales. This diagnostic was demonstrated over the wavelength range 450-1150 nm with up to 16 time displaced spectra during a single shock experiment. Simultaneous off-normal incidence velocity interferometry (velocity interferometer system for any reflector) characterized the sample under laser-compression and also provided an independent reflectivity measurement at 532 nm wavelength. The shock-driven semiconductor-to-metallic transition in germanium was documented by the way of reflectivity measurements with 0.5 ns time resolution and a wavelength resolution of 10 nm.

  8. Investigation of Laser Ignition Behavior of Iso-octane and Ethanol Blends

    NASA Astrophysics Data System (ADS)

    Peters, Nathan; Bailey, Patrina; Coombs, Deshawn; Akih-Kumgeh, Benjamin

    2015-11-01

    Laser-induced ignition is a promising technology for combustion initiation in gas turbines and internal combustion engines. There is renewed interest in this technology in recent years due to its ability to ignite lean mixtures which are desirable for cleaner combustion. Research in this area has mainly focused on methane combustion. Effects of pressure, temperature, and ignition energy have been studied. Another fuel of practical interest which has not been studied as extensively is iso-octane. Due to the complexities of the laser ignition process, there is still a lot that to be understood, especially during the early stages of ignition. In this work we study the ignition of iso-octane and blends including ethanol, induced by focused light pulse from an Nd:YAG laser emitting at 532 nm. Experiments are carried out in a cylindrical stainless steel vessel, equipped with 6 optical accesses. Schlieren imaging and laser interferometry are used to image the ignition process. We seek to understand the multiphysics of the early stages of ignition including shock wave velocity, plasma to flame kernel transition, and flame kernel quenching under lean conditions.

  9. The synergistic effect of visible light and gentamycin on Pseudomona aeruginosa microorganisms.

    PubMed

    Reznick, Yana; Banin, Ehud; Lipovsky, Anat; Lubart, Rachel; Polak, Pazit; Zalevsky, Zeev

    2013-01-01

    Recently there were several publications on the bactericidal effect of visible light, most of them claiming that blue part of the spectrum (400 nm-500 nm) is responsible for killing various pathogens(1-5). The phototoxic effect of blue light was suggested to be a result of light-induced reactive oxygen species (ROS) formation by endogenous bacterial photosensitizers which mostly absorb light in the blue region(4,6,7). There are also reports of biocidal effect of red and near infra red(8) as well as green light(9). In the present study, we developed a method that allowed us to characterize the effect of high power green (wavelength of 532 nm) continuous (CW) and pulsed Q-switched (Q-S) light on Pseudomonas aeruginosa. Using this method we also studied the effect of green light combined with antibiotic treatment (gentamycin) on the bacteria viability. P. aeruginosa is a common noscomial opportunistic pathogen causing various diseases. The strain is fairly resistant to various antibiotics and contains many predicted AcrB/Mex-type RND multidrug efflux systems(10). The method utilized free-living stationary phase Gram-negative bacteria (P. aeruginosa strain PAO1), grown in Luria Broth (LB) medium exposed to Q-switched and/or CW lasers with and without the addition of the antibiotic gentamycin. Cell viability was determined at different time points. The obtained results showed that laser treatment alone did not reduce cell viability compared to untreated control and that gentamycin treatment alone only resulted in a 0.5 log reduction in the viable count for P. aeruginosa. The combined laser and gentamycin treatment, however, resulted in a synergistic effect and the viability of P. aeruginosa was reduced by 8 log's. The proposed method can further be implemented via the development of catheter like device capable of injecting an antibiotic solution into the infected organ while simultaneously illuminating the area with light. PMID:23852319

  10. The Synergistic Effect of Visible Light and Gentamycin on Pseudomona aeruginosa Microorganisms

    PubMed Central

    Reznick, Yana; Banin, Ehud; Lipovsky, Anat; Lubart, Rachel; Polak, Pazit; Zalevsky, Zeev

    2013-01-01

    Recently there were several publications on the bactericidal effect of visible light, most of them claiming that blue part of the spectrum (400 nm-500 nm) is responsible for killing various pathogens1-5. The phototoxic effect of blue light was suggested to be a result of light-induced reactive oxygen species (ROS) formation by endogenous bacterial photosensitizers which mostly absorb light in the blue region4,6,7. There are also reports of biocidal effect of red and near infra red8 as well as green light9. In the present study, we developed a method that allowed us to characterize the effect of high power green (wavelength of 532 nm) continuous (CW) and pulsed Q-switched (Q-S) light on Pseudomonas aeruginosa. Using this method we also studied the effect of green light combined with antibiotic treatment (gentamycin) on the bacteria viability. P. aeruginosa is a common noscomial opportunistic pathogen causing various diseases. The strain is fairly resistant to various antibiotics and contains many predicted AcrB/Mex-type RND multidrug efflux systems10. The method utilized free-living stationary phase Gram-negative bacteria (P. aeruginosa strain PAO1), grown in Luria Broth (LB) medium exposed to Q-switched and/or CW lasers with and without the addition of the antibiotic gentamycin. Cell viability was determined at different time points. The obtained results showed that laser treatment alone did not reduce cell viability compared to untreated control and that gentamycin treatment alone only resulted in a 0.5 log reduction in the viable count for P. aeruginosa. The combined laser and gentamycin treatment, however, resulted in a synergistic effect and the viability of P. aeruginosa was reduced by 8 log's. The proposed method can further be implemented via the development of catheter like device capable of injecting an antibiotic solution into the infected organ while simultaneously illuminating the area with light. PMID:23852319

  11. Safety Guidelines for Laser Illumination on Exposed High Explosives and Metals in Contact with High Explosives with Calculational Results

    SciTech Connect

    Benterou, J; Roeske, F; Wilkins, P; Carpenter, K H

    2002-04-17

    Experimental tests have been undertaken to determine safe levels of laser exposure on bare high explosive (HE) samples and on common metals used in intimate contact with HE. Laser light is often focused on bare HE and upon metals in contact with HE during alignment procedures and experimental metrology experiments. This paper looks at effects caused by focusing laser beams at high energy densities directly onto the surface of various bare HE samples. Laser energy densities (fluence) exceeding 19 kilowatts/cm{sup 2} using a 5-milliwatt, 670 nm, cw laser diode were generated by focusing the laser down to a spot size diameter of 4 microns. Upon careful inspection, no laser damage was observed in any of the HE samples illuminated at this fluence level. Direct laser exposure of metals directly contacting HE surfaces was also tested. Laser energy densities (fluence) varying from 188 Watts/cm{sup 2} to 12.7 KW/cm{sup 2} were generated using an 11-Watt, 532 nm frequency-doubled Nd:YAG cw laser with focal spot size diameters as small as 100 microns. These measurements look at the temperature rise of the surface of the metal in contact with HE when laser energy is incident on the opposite side of the metal. The temperature rise was experimentally measured as a function of incident laser power, spot size, metal composition and metal thickness. Numerical simulations were also performed to solve the two-dimensional heat flow problem for this experimental geometry. In order to simplify the numerical simulation to allow representation of a large number of physical cases, the equations used in the simulation are expressed in terms of dimensionless variables. The normalized numerical solutions are then compared to the various experimental configurations utilized. Calculations and experiment agree well over the range measured. Safety guidelines for alignment laser illumination upon bare HE are outlined.

  12. Laser light scan analysis of the “anticonvulsant face”

    PubMed Central

    Orup, H. Ivan; Deutsch, Curtis K.; Holmes, Lewis B.

    2014-01-01

    BACKGROUND The “anticonvulsant face”, comprised of a short nose, low nasal bridge, epicanthal folds, and wide mouth, was suggested in the 1970s to indicate teratogenesis caused by the anticonvulsant drugs phenytoin and phenobarbital. However, these were based on subjective clinical observations. In the present study we have applied objective and reliable quantitative measures to the operational definitions of craniofacial features in anticonvulant-exposed cases. We have adopted anthropometric analysis based on image analysis of laser light scans. Using morphometric methods, we established the positions of physical features and objectively determined the changes in the size and shape of affected soft tissues of the faces of children exposed to those anticonvulsant drugs during pregnancy. METHODS Thirteen individuals, exposed throughout pregnancy to phenytoin as either monotherapy or polytherapy, were identified in a previous analysis as having significant changes in their craniofacial features based on measurements of cephalometric radiographs, changes associated with “the anticonvulsant face”.. The soft tissues of their faces were imaged by 3D laser (structured light) scanning. RESULTS The notable changes in soft tissues identified by laser light scans were a wide philtrum (between the left and right cristae philtri), narrow mouth (between the left and right cheilions), short nasal bridge (between nasale and pronasale), short nose height (between the nasale and subnasale), and flat orbits (based on the orbital protrusion index). CONCLUSIONS This analysis of phenytoin-exposed individuals is the first anthropometric analysis of the craniofacial surface, designed to render the identification of abnormal features both objective and realiable. These analyses demonstrated that there were several significant changes in the soft tissue of the face, corroborating earlier studies of alterations of the craniofacial skeleton in the anticonvulsant face. Two of the

  13. Reflectives: Phosphors and lasers - shedding light on rare earths

    SciTech Connect

    Tonneson, L.C.; Fox, G.J.

    1996-04-01

    The first powder electroluminescent phosphor was introduced in 1936. Today, phosphors, particularly those made of high-purity rare earths, have found their way into a variety of products: industrial, commercial, and consumer, alike. The fluorescent lamp industry which remains the leading market for the use of high-purity rare earths, lit the way for the future of rare earths in the optical, x-ray, and display screen applications. Light combined with rare earth materials is also a successful recipe for reflectivity needed in filtering applications such as optics, lasers, and conductors. This article discusses the applications and markets for phosphors and rare earths.

  14. Laser biostimulation of patients suffering from multiple sclerosis in respect to the biological influence of laser light

    NASA Astrophysics Data System (ADS)

    Peszynski-Drews, Cezary; Klimek, Andrzej; Sopinski, Marek; Obrzejta, Dominik

    2003-10-01

    The authors discuss the results, obtained so far during three years' clinical examination, of laser therapy in the treatment of patients suffering from multiple sclerosis. They regard both the results of former laboratory experiments and so far discovered mechanisms of biological influence of laser light as an objective explanation of high effectiveness of laser therapy in the csae of this so far incurable disease. They discuss wide range of biological mechanisms of laser therapy, examined so far on different levels (cell, tissue, organ), allowing the explanation of beneficial influence of laser light in pathogenetically different morbidities.

  15. ["Power bleaching" with the KTP laser].

    PubMed

    Vanderstricht, K; Nammour, S; De Moor, R

    2009-01-01

    The most important constituent of the bleaching process is the hydrogen peroxyde. The bleaching effect is the result of a change in the chemical structure of organic molecules in the teeth. Different bleaching techniques are described on the basis of the concentration of the hydrogen peroxyde used and on the basis of the different methods of application. It has been demonstrated that a faster change in colour can be obtained when bleaching is performed in combination with a light source i.e. power bleaching aiming for a more in depth change of colour. Different investigations have demonstrated that negative effects associated with bleaching agents are seen earlier when light sources have been used as accelerators. So, light activation may not lead to 'heating of the pulp'. Different types of laser bleaching have been described, though, not all of them will lead to the desired result. There is only one exception at present and this is the KTP-laser bleaching with the Smart Bleach gel. The specific laser-tissue interaction is the result of different activation processes of the hydrogen peroxyde in the gel: as a result of the interaction with the laser a photocatalytic effect is induced (i.e. the activation of the gel by means of light--this is also referred to as a photochemical reaction), a limited photothermal effect (light absorption may result in a certain heating of the gel). The light activated gel also has an alkaline pH, which favours the ionisation of the hydrogen peroxyde into perhydroxyl ions (these are the most reactive free radicals). It is also possible to directly cut the tetracycline molecules (a good absorption of light by the tetracycline molecules at 532 nm). This will result in better decolouration of tetracycline stained teeth. This last process is described as direct photobleaching. It also needs to be emphasized that bleaching with a laser can only be performed by a dentist who has acquired a substantial knowledge on laser-tissue interaction

  16. Laser and light-based treatment options for hidradenitis suppurativa.

    PubMed

    Hamzavi, Iltefat H; Griffith, James L; Riyaz, Farhaad; Hessam, Schapoor; Bechara, Falk G

    2015-11-01

    Hidradenitis suppurativa (HS) is a chronic inflammatory disease that commonly develops painful, deep dermal abscesses and chronic, draining sinus tracts. Classically, pharmacologic and surgical therapies have been effective for reducing lesion activity and inflammation, but provide only modest success in the prevention of future recurrences and disease progression. Adjunctive therapies, such as laser and light-based therapies, have become more commonly used in the management of HS. These therapies work to reduce the occurrence of painful HS flare-ups by decreasing the number of hair follicles, sebaceous glands, and bacteria in affected areas, and by ablatively debulking chronic lesions. The best results are seen when treatment is individualized, taking disease severity into consideration when selecting specific energy-based approaches. This article will discuss various light-based therapies and the evidence supporting their use in the management of HS. PMID:26470622

  17. Indigenous development of static laser light scattering (SLS) spectrometer

    NASA Astrophysics Data System (ADS)

    Joseph, David; Kumar, Amit

    2013-02-01

    An indigenous laser light scattering spectrometer is being developed for the studies of biological cells, macromolecules and their interactions. A laboratory spectrometer is used and modified as scattering arm, Turn Table and Collimating arm. Both the arms have polarizers, one acting as polarizer and the other as analyzer. The scattered light from the scattering cell is analyzed by an analyzer and is fed to a PMT and a photon counting module. Except for the PMT all the accessories are being fabricated indigenously. The studies are based initially on the studies of red blood cells. Studies are focused on for their single particle and their aggregation behavior. Using the ORT program developed by Otto Glatter the morphology of red blood cells will be analyzed.

  18. Transient light absorption induced in glassby femtosecond laser pulses

    SciTech Connect

    Blonskii, I V; Kadan, V N; Pavlov, I A; Kryuchkov, N N; Shpotyuk, O I

    2009-10-31

    The dynamics of the transient light absorption induced in K8 optical glass by filamented femtosecond laser pulses have been studied using time-resolved transmitted-light microscopy at wavelengths from 450 to 700 nm. The transient absorption measured as a function of probe beam wavelength is compared to that predicted by the Drude plasma model. We conclude that, just 450 fs after a pump pulse, the transient absorption is dominated by transient electronic states, presumably, self-trapped excitons, with an excitation energy of 2.6 - 2.7 eV. These states are filled with free-carriers from a long-lived plasma, which acts as a 'carrier reservoir'. The relaxation of transient absorption has two components. The slow component, with {tau}{sub 1} {approx} 17-17.5 ps, is governed by the plasma thermalisation time, whereas the second, with {tau}{sub 1} >> 300 ps, is determined by the plasma lifetime. (nonlinear optical phenomena)

  19. Synchronization of video recording and laser pulses including background light suppression

    NASA Technical Reports Server (NTRS)

    Kalshoven, Jr., James E. (Inventor); Tierney, Jr., Michael (Inventor); Dabney, Philip W. (Inventor)

    2004-01-01

    An apparatus for and a method of triggering a pulsed light source, in particular a laser light source, for predictable capture of the source by video equipment. A frame synchronization signal is derived from the video signal of a camera to trigger the laser and position the resulting laser light pulse in the appropriate field of the video frame and during the opening of the electronic shutter, if such shutter is included in the camera. Positioning of the laser pulse in the proper video field allows, after recording, for the viewing of the laser light image with a video monitor using the pause mode on a standard cassette-type VCR. This invention also allows for fine positioning of the laser pulse to fall within the electronic shutter opening. For cameras with externally controllable electronic shutters, the invention provides for background light suppression by increasing shutter speed during the frame in which the laser light image is captured. This results in the laser light appearing in one frame in which the background scene is suppressed with the laser light being uneffected, while in all other frames, the shutter speed is slower, allowing for the normal recording of the background scene. This invention also allows for arbitrary (manual or external) triggering of the laser with full video synchronization and background light suppression.

  20. Polarized Imaging Nephelometer for in situ airborne measurements of aerosol light scattering.

    PubMed

    Dolgos, Gergely; Martins, J Vanderlei

    2014-09-01

    Global satellite remote sensing of aerosols requires in situ measurements to enable the calibration and validation of algorithms. In order to improve our understanding of light scattering by aerosol particles, and to enable routine in situ airborne measurements of aerosol light scattering, we have developed an instrument, called the Polarized Imaging Nephelometer (PI-Neph). We designed and built the PI-Neph at the Laboratory for Aerosols, Clouds and Optics (LACO) of the University of Maryland, Baltimore County (UMBC). This portable instrument directly measures the ambient scattering coefficient and phase matrix elements of aerosols, in the field or onboard an aircraft. The measured phase matrix elements are the P(11), phase function, and P(12). Lasers illuminate the sampled ambient air and aerosol, and a wide field of view camera detects scattered light in a scattering angle range of 3° to 176°. The PI-Neph measures an ensemble of particles, supplying the relevant quantity for satellite remote sensing, as opposed to particle-by-particle measurements that have other applications. Comparisons with remote sensing measurements will have to consider aircraft inlet effects. The PI-Neph first measured at a laser wavelength of 532nm, and was first deployed successfully in 2011 aboard the B200 aircraft of NASA Langley during the Development and Evaluation of satellite ValidatiOn Tools by Experimenters (DEVOTE) project. In 2013, we upgraded the PI-Neph to measure at 473nm, 532nm, and 671nm nearly simultaneously. LACO has deployed the PI-Neph on a number of airborne field campaigns aboard three different NASA aircraft. This paper describes the PI-Neph measurement approach and validation by comparing measurements of artificial spherical aerosols with Mie theory. We provide estimates of calibration uncertainties, which show agreement with the small residuals between measurements of P(11) and -P(12)/P(11) and Mie theory. We demonstrate the capability of the PI-Neph to measure

  1. LIGHT SCATTERING: Observation of multiple scattering of laser radiation from a light-induced jet of microparticles in suspension

    NASA Astrophysics Data System (ADS)

    Kondrat'ev, Andrei V.

    2004-06-01

    Variation in the correlation function of light multiply scattered by a random medium was observed with increasing the incident beam power. The light-induced motion of microparticles in suspension, caused by a high-power laser radiation, serves as an additional factor in the decorrelation of the scattered light. The experimental data are in good agreement with the results of theoretical analysis.

  2. Laser-assisted biosynthesis for noble nanoparticles production

    NASA Astrophysics Data System (ADS)

    Kukhtarev, Tatiana; Edwards, Vernessa; Kukhtareva, Nickolai; Moses, Sherita

    2014-08-01

    Extracellular Biosynthesis technique (EBS) for nanoparticles production has attracted a lot of attention as an environmentally friendly and an inexpensive methodology. Our recent research was focused on the rapid approach of the green synthesis method and the reduction of the homogeneous size distribution of nanoparticles using pulse laser application. Noble nanoparticles (NNPs) were produced using various ethanol and water plant extracts. The plants were chosen based on their biomedical applications. The plants we used were Magnolia grandiflora, Geranium, Aloe `tingtinkie', Aloe barbadensis (Aloe Vera), Eucalyptus angophoroides, Sansevieria trifasciata, Impatiens scapiflora. Water and ethanol extract, were used as reducing agents to produce the nanoparticles. The reaction process was monitored using a UV-Visible spectroscopy. NNPs were characterized by Fourier Transfer Infrared Spectroscopy (FTIR), Transmission Electron Microscopy (TEM), and the Dynamic Light Scattering technique (DLS). During the pulse laser Nd-YAG illumination (λ=1064nm, 532nm, PE= 450mJ, 200mJ, 10 min) the blue shift of the surface plasmon resonance absorption peak was observed from ~424nm to 403nm for silver NP; and from ~530nm to 520 nm for gold NPs. In addition, NNPs solution after Nd-YAG illumination was characterized by the narrowing of the surface plasmon absorption resonance band, which corresponds to monodispersed NNPS distribution. FTIR, TEM, DLS, Zeta potential results demonstrated that NNPs were surrounded by biological molecules, which naturally stabilized nanosolutions for months. Cytotoxicity investigation of biosynthesized NNPs is in progress.

  3. Metal-clad waveguide characterization for contact-based light transmission into tissue

    NASA Astrophysics Data System (ADS)

    Chininis, Jeffrey; Whiteside, Paul; Hunt, Heather K.

    2016-02-01

    As contemporary laser dermatology procedures, like tattoo removal and skin resurfacing, become more popular, the complications of their operation are also becoming more prevalent. Frequent incidences of over-exposure, ocular injury, and excessive thermal damage represent mounting concerns for those seeking such procedures; moreover, each of these problems is a direct consequence of the standard, free-space method of laser transmission predominantly used in clinical settings. Therefore, an alternative method of light transmission is needed to minimize these problems. Here, we demonstrate and characterize an alternative method that uses planar waveguides to deliver light into sample tissue via direct contact. To do this, slab substrates made from glass were clad in layers of titanium and silver, constraining the light within the waveguide along the waveguide's length. By creating active areas on the waveguide surface, the propagating light could then optically tunnel into the tissue sample, when the waveguide was brought into contact with the tissue. SEM and EDS were used to characterize the metal film thickness and deposition rates onto the glass substrates. Laser light from a Q-switched Nd:YAG source operating at 532nm was coupled into the waveguide and transmitted into samples of pig skin. The amount of light transmitted was measured using photoacoustics techniques, in conjunction with a photodiode and integrating sphere. Transmitting light into tissue in this manner effectively resolves or circumvents the complications caused by free-space propagation methods as it reduces the operating distance to 0, which prevents hazardous back-reflections and allows for the ready incorporation of contact cooling technologies.

  4. Laser-light delivery microtools based on laser technology: design, fabrication, and applications

    NASA Astrophysics Data System (ADS)

    Veiko, Vadim P.; Voznesensky, Nikolay B.

    2001-06-01

    A set of new laser-light delivery microtools (LDM) based on laser technology is investigated and discussed. Wide application of LDM in different fields of science, medicine, biology, industry and information processing is considered. Fiber optical networks in medical diagnostics and technical, civil engineering and other technological areas are discussed. The general approach based on electromagnetic field equations-transformation for all range of dimensions (mini-, micro and nanodomain) is given. Laser-assisted technology for drawing-out and for microstructuring optical tools is investigated, high-speed movie has been applied to study the process and compared with theoretical description. Finally a number of fibers and micropipettes-based medical tools and SNOM-tips has been fabricated and tested. Applications of some tools for medical operations (thermocoagulation), protein rasters preparing, SNOM-microscopy investigation have been demonstrated.

  5. Influence of laser light on AMPK as a factor in the laser therapy of diabetes

    NASA Astrophysics Data System (ADS)

    Makela, A. M.

    2006-02-01

    The use of light and laser in the treatment of diabetes has been under research and some controversy. The following paper explores some of the mechanisms involved in glucose level regulation in connection to light. Several researchers have found that laser irradiation can activate ATP production, influence redox values within cells, and have other effects which can (in)directly activate AMP-activated protein kinase (AMPK). The activation of AMPK plays an important, albeit not an exclusive, role in the induction of GLUT4 recruitment to the plasma membrane. In addition, there is some demonstration that AMPK may regulate glucose transport through GLUT1. Increased glucose uptake will result in an increase in glycolysis and ATP production.

  6. Increased epidermal laser fluence through simultaneous ultrasonic microporation

    NASA Astrophysics Data System (ADS)

    Whiteside, Paul J. D.; Chininis, Jeff A.; Schellenberg, Mason W.; Qian, Chenxi; Hunt, Heather K.

    2016-03-01

    Lasers have demonstrated widespread applicability in clinical dermatology as minimally invasive instruments that achieve photogenerated responses within tissue. However, before reaching its target, the incident light must first transmit through the surface layer of tissue, which is interspersed with chromophores (e.g. melanin) that preferentially absorb the light and may also generate negative tissue responses. These optical absorbers decrease the efficacy of the procedures. In order to ensure that the target receives a clinically relevant dose, most procedures simply increase the incident energy; however, this tends to exacerbate the negative complications of melanin absorption. Here, we present an alternative solution aimed at increasing epidermal energy uence while mitigating excess absorption by unintended targets. Our technique involves the combination of a waveguide-based contact transmission modality with simultaneous high-frequency ultrasonic pulsation, which alters the optical properties of the tissue through the agglomeration of dissolved gasses into micro-bubbles within the tissue. Doing so effectively creates optically transparent pathways for the light to transmit unobstructed through the tissue, resulting in an increase in forward scattering and a decrease in absorption. To demonstrate this, Q-switched nanosecond-pulsed laser light at 532nm was delivered into pig skin samples using custom glass waveguides clad in titanium and silver. Light transmission through the tissue was measured with a photodiode and integrating sphere for tissue with and without continuous ultrasonic pulsation at 510 kHz. The combination of these techniques has the potential to improve the efficiency of laser procedures while mitigating negative tissue effects caused by undesirable absorption.

  7. Super-luminescent jet light generated by femtosecond laser pulses

    PubMed Central

    Xu, Zhijun; Zhu, Xiaonong; Yu, Yang; Zhang, Nan; Zhao, Jiefeng

    2014-01-01

    Phenomena of nonlinear light-matter interaction that occur during the propagation of intense ultrashort laser pulses in continuous media have been extensively studied in ultrafast optical science. In this vibrant research field, conversion of the input laser beam into optical filament(s) is commonly encountered. Here, we demonstrate generation of distinctive single or double super-luminescent optical jet beams as a result of strong spatial-temporal nonlinear interaction between focused 50 fs millijoule laser pulses and their induced micro air plasma. Such jet-like optical beams, being slightly divergent and coexisting with severely distorted conical emission of colored speckles, are largely different from optical filaments, and obtainable when the focal lens of proper f-number is slightly tilted or shifted. Once being collimated, the jet beams can propagate over a long distance in air. These beams not only reveal a potentially useful approach to coherent optical wave generation, but also may find applications in remote sensing. PMID:24463611

  8. Bowls made of Laser Light to Corral Ultracold Atoms

    NASA Astrophysics Data System (ADS)

    Thomas, John

    2010-10-01

    Using stable lasers, it is now possible to create nearly perfect bowls made of pure light, which are smaller than a piece of lint and store atoms for several minutes in an ultrahigh vacuum environment. These almost frictionless bowls are ideal for cooling atoms by evaporation, the same way that alcohol cools the skin. In just a few seconds, atoms trapped in the bowl are cooled to temperatures of ten of billionths of a degree above absolute zero, where the de Broglie wavelength is several microns. These ultracold atoms occupy the quantum energy levels of the bowl, producing a giant quantum system that can be directly observed using laser flash photography. I will describe our laser trapping methods and show how they can be use to study a unique quantum gas of spin-up and spin-down ^6Li atoms, which are fermions that obey the Pauli exclusion principle. I will describe how this ultracold atomic gas now tests predictions in nearly all fields of physics, from high temperature superconductors to neutron stars, the quark-gluon plasma of the Big Bang, and even string theory.

  9. Low-level laser/light therapy for androgenetic alopecia.

    PubMed

    Gupta, Aditya K; Lyons, Danika C A; Abramovits, William

    2014-01-01

    Androgenetic alopecia (AGA) is a persistent and pervasive condition that affects men worldwide. Some common treatment options for AGA include hair prosthetics, oral and topical medications, and surgical hair restoration (SHR). Pharmaceutical and SHR treatments are associated with limitations including adverse side effects and significant financial burden. Low-level laser or light (LLL) devices offer alternative treatment options that are not typically associated with adverse side effects or significant costs. There are clinic- and home-based LLL devices. One home-based laser comb device has set a standard for others; however, this device requires time devoted to carefully moving the comb through the hair to allow laser penetration to the scalp. A novel helmet-like LLL device for hair growth has proven effective in preliminary trials and allows for hands-free use. Regardless, there are few clinical trials that have been conducted regarding LLL devices for AGA and results are mixed. Further research is required to establish the true efficacy of these devices for hair growth in comparison to existing alternative therapies. PMID:25134310

  10. a Light-Weight Laser Scanner for Uav Applications

    NASA Astrophysics Data System (ADS)

    Tommaselli, A. M. G.; Torres, F. M.

    2016-06-01

    Unmanned Aerial Vehicles (UAV) have been recognized as a tool for geospatial data acquisition due to their flexibility and favourable cost benefit ratio. The practical use of laser scanning devices on-board UAVs is also developing with new experimental and commercial systems. This paper describes a light-weight laser scanning system composed of an IbeoLux scanner, an Inertial Navigation System Span-IGM-S1, from Novatel, a Raspberry PI portable computer, which records data from both systems and an octopter UAV. The performance of this light-weight system was assessed both for accuracy and with respect to point density, using Ground Control Points (GCP) as reference. Two flights were performed with the UAV octopter carrying the equipment. In the first trial, the flight height was 100 m with six strips over a parking area. The second trial was carried out over an urban park with some buildings and artificial targets serving as reference Ground Control Points. In this experiment a flight height of 70 m was chosen to improve target response. Accuracy was assessed based on control points the coordinates of which were measured in the field. Results showed that vertical accuracy with this prototype is around 30 cm, which is acceptable for forest applications but this accuracy can be improved using further refinements in direct georeferencing and in the system calibration.

  11. A compact high brightness laser synchrotron light source for medical applications

    NASA Astrophysics Data System (ADS)

    Nakajima, Kazuhisa

    1999-07-01

    The present high-brightness hard X-ray sources have been developed as third generation synchrotron light sources based on large high energy electron storage rings and magnetic undulators. Recently availability of compact terawatt lasers arouses a great interest in the use of lasers as undulators. The laser undulator concept makes it possible to construct an attractive compact synchrotron radiation source which has been proposed as a laser synchrotron light source. This paper proposes a compact laser synchrotron light source for mediacal applications, such as an intravenous coronary angiography and microbeam therapy.

  12. Near infrared laser ocular bioeffects

    SciTech Connect

    Lund, D.J.; Beatrice, E.S.

    1989-05-01

    Thresholds for laser chorioretinal injury in the red end of the visible spectrum and the near-infrared (IR-A) spectral regions are presented. An unpredicted wavelength dependence of the injury threshold for single Q-switched pulses is demonstrated. Four lasers were used to determine thresholds at 40 wavelengths between 532 nm and 1064 nm: a ruby laser, a neodymium:YAG-pumped dye laser, an erbium:YLF laser and an alexandrite laser. Despite many careful and repeated efforts to determine a cause for the variation due to possible variations in the lasers or other aspects of the experimental technique and due to biological absorption properties of the eye, there is no complete or obvious explanation for the significant variations of threshold with small changes in wavelength. The implications of these findings for laser safety standards are presented.

  13. EFFECT OF LASER LIGHT ON MATTER. LASER PLASMAS: Boundary instability of an erosion laser plasma expanding into a background gas

    NASA Astrophysics Data System (ADS)

    Anisimov, V. N.; Grishina, V. G.; Derkach, O. N.; Kanevskiĭ, M. F.; Sebrant, A. Yu

    1993-12-01

    The stability of the contact region in the system consisting of an erosion plasma and a gas has been determined experimentally under conditions such that the length of the applied laser pulse is longer than the rise time of the instability, and the expansion of the erosion plume is accompanied by breakdown of the background gas. The evolution of perturbations of the plasma front following the introduction of initial perturbations with a fixed spatial period has been studied. It is possible to model the injection of plasma bunches into a low-pressure gas by studying the dynamics of the vaporization at moderate laser-light intensities, characteristic of technological applications.

  14. EFFECT OF LASER LIGHT ON LASER PLASMAS: Laser plasma at low air pressure

    NASA Astrophysics Data System (ADS)

    Vas'kovskiĭ, Yu M.; Moiseev, V. N.; Rovinskiĭ, R. E.; Tsenina, I. S.

    1993-01-01

    The dynamic and optical characteristics of the laser plasma produced during the application of a CO2 laser pulse to a target have been studied as a function of the ambient air pressure. The changes in the surface roughness of the sample after bombardment were studied as a function of the air pressure. It is concluded from the results that a transition from an air plasma to an erosion plasma occurs at a residual air pressure on the order of 1 torr. The experiment data support the existing picture of the process by which a plasma is produced near the surface of a target in air by laser pulses.

  15. Estimating the pressure of laser-induced plasma shockwave by stimulated Raman shift of lattice translational modes

    SciTech Connect

    Li Zhanlong; Shan Xiaoning; Li Zuowei; Zhou Mi; Men Zhiwei; Cao Junsheng; Wang Yiding; Sun Chenglin

    2012-07-09

    The current paper investigates stimulated Raman scattering (SRS) when laser-induced plasma is formed in heavy water by focusing an intense pulsed 532 nm Nd:YAG laser beam at room temperature. An unexpected low-frequency SRS line attributed to the lattice translational modes of ice-VII (D{sub 2}O) is observed. The pressure of the plasma shockwave is estimated using low-frequency SRS line shift.

  16. 21.2% wall-plug efficiency green laser based on an electrically pumped VECSEL through intracavity second harmonic generation

    NASA Astrophysics Data System (ADS)

    Zhao, Pu; Xu, Bing; van Leeuwen, Robert; Chen, Tong; Watkins, Laurence; Zhou, Delai; Seurin, Jean-Francois; Gao, Peng; Xu, Guoyang; Wang, Qing; Ghosh, Chuni

    2015-03-01

    We have achieved a 21.2% wall-plug efficiency green laser at 532 nm based on an electrically pumped vertical externalcavity surface emitting laser (VECSEL) through intracavity second harmonic generation. The continuous-wave green output power was 3.34 W. The VECSEL gain device is cooled by using a thermoelectric cooler, which can greatly benefit packaging. Both power and efficiency can be further scaled up by optimizing external-cavity design and improving the performance of VECSEL gain device.

  17. Influence of the Sampling Rate and Noise Characteristics on Prediction of the Maximal Safe Laser Exposure in Human Skin Using Pulsed Photothermal Radiometry

    NASA Astrophysics Data System (ADS)

    Vidovič, L.; Milanič, M.; Majaron, B.

    2013-09-01

    Pulsed photothermal radiometry (PPTR) allows for noninvasive determination of the laser-induced temperature depth profile in strongly scattering samples, including human skin. In a recent experimental study, we have demonstrated that such information can be used to derive rather accurate predictions of the maximal safe radiant exposure on an individual patient basis. This has important implications for efficacy and safety of several laser applications in dermatology and aesthetic surgery, which are often compromised by risk of adverse side effects (e.g., scarring, and dyspigmentation) resulting from nonselective absorption of strong laser light in epidermal melanin. In this study, the differences between the individual maximal safe radiant exposure values as predicted from PPTR temperature depth profiling performed using a commercial mid-IR thermal camera (as used to acquire the original patient data) and our customized PPTR setup are analyzed. To this end, the latter has been used to acquire 17 PPTR records from three healthy volunteers, using 1 ms laser irradiation at 532 nm and a signal sampling rate of 20 000 . The laser-induced temperature profiles are reconstructed first from the intact PPTR signals, and then by binning the data to imitate the lower sampling rate of the IR camera (1000 fps). Using either the initial temperature profile in a dedicated numerical model of heat transfer or protein denaturation dynamics, the predicted levels of epidermal thermal damage and the corresponding are compared. A similar analysis is performed also with regard to the differences between noise characteristics of the two PPTR setups.

  18. Laser Plasma Instability (LPI) Driven Light Scattering Measurements with Nike KrF Laser

    NASA Astrophysics Data System (ADS)

    Oh, J.; Weaver, J. L.; Kehne, D. M.; Obenschain, S. P.; McLean, E. A.; Lehmberg, R. H.

    2008-11-01

    With the short wavelength (248 nm), large bandwidth (1˜2 THz), and ISI beam smoothing, Nike KrF laser is expected to have higher LPI thresholds than observed at other laser facilities. Previous measurements using the Nike laser [J. L. Weaver et al, Phys. Plasmas 14, 056316 (2007)] showed no LPI evidence from CH targets up to I˜2x10^15 W/cm^2. For further experiments to detect LPI excitation, Nike capabilities have been extended to achieve higher laser intensities by tighter beam focusing and higher power pulses. This talk will present results of a recent LPI experiment with the extended Nike capabilities focusing on light emission data in spectral ranges relevant to the Raman (SRS) and Two-Plasmon Decay (TPD) instabilities. The primary diagnostics were time-resolved spectrometers with an absolute-intensity-calibrated photodiode array in (0.4˜0.8)φ0 and a streak camera near 0.5φ0. The measurements were conducted at laser intensities of 10^15˜10^16 W/cm^2 on planar targets of CH solids and RF foams.

  19. Paper un-printing: using lasers to remove toner-print in order to reuse office paper

    NASA Astrophysics Data System (ADS)

    Leal-Ayala, D. R.; Allwood, J. M.; Counsell, T. A. M.

    2011-12-01

    In this article, lasers in the ultraviolet, visible and infrared light spectra working with pulse widths in the nanosecond range are applied to a range of toner-paper combinations to determine their ability to remove toner. If the laser energy fluence can be chosen to stay below the ablation threshold of paper at the same time that it surpasses that of toner, paper could be cleaned and re-used instead of being recycled or disposed into a landfill. This could significantly reduce the environmental impact of paper production and use. Although there are a variety of paper conservation studies which have investigated the effects of laser radiation on blank and soiled paper, none has previously explored toner-print removal from paper by laser ablation. Colour analysis under the L ∗ a ∗ b ∗ colour space and SEM examination of the outcome indicate that it is possible to remove toner from paper without damaging and discolouring the substrate. Best results are obtained when employing visible radiation at a wavelength of 532 nm working with a pulse width of 4 ns and energy fluences under 1.6 J/cm2. This means that it is technically feasible to remove toner-print for paper re-use.

  20. High-power picosecond 355 nm laser based on La₂CaB₁₀O₁₉ crystal.

    PubMed

    Li, Kai; Zhang, Ling; Xu, Degang; Zhang, Guochun; Yu, Haijuan; Wang, Yuye; Shan, Faxian; Wang, Lirong; Yan, Chao; Wu, Yicheng; Lin, Xuechun; Yao, Jianquan

    2014-06-01

    Third harmonic generation experiments were performed on a type-I phase-matching La2CaB10O19 crystal cut at θ=49.4° and φ=0.0° with dimensions of 4.0  mm×4.0  mm×17.6  mm. A 1064 nm laser with a maximum average power of 35.2 W was employed as the fundamental light source, which has a pulse width of 10 picoseconds and a pulse repetition rate of 80 MHz. A type-I noncritical phase-matching LBO crystal was used to generate 532 nm lasers. By investigating a series of focusing lens combinations, a picosecond 355 nm laser of 5.3 W was obtained, which is the highest power of picosecond 355 nm laser based on a La2CaB10O19 crystal so far. The total conversion efficiency from 1064 to 355 nm was up to 15.1%. PMID:24876039

  1. Flow Visualization by Elastic Light Scattering in the Boundary Layer of a Supersonic Flow

    NASA Technical Reports Server (NTRS)

    Herring, G. C.; Hillard, Mervin E., Jr.

    2000-01-01

    We demonstrate instantaneous flow visualization of the boundary layer region of a Mach 2.5 supersonic flow over a flat plate that is interacting with an impinging shock wave. Tests were performed in the Unitary Plan Wind Tunnel (UPWT) at NASA Langley Research Center. The technique is elastic light scattering using 10-nsec laser pulses at 532 nm. We emphasize that no seed material of any kind, including water (H2O), is purposely added to the flow. The scattered light comes from a residual impurity that normally exists in the flow medium after the air drying process. Thus, the technique described here differs from the traditional vapor-screen method, which is typically accomplished by the addition of extra H2O vapor to the airflow. The flow is visualized with a series of thin two-dimensional light sheets (oriented perpendicular to the streamwise direction) that are located at several positions downstream of the leading edge of the model. This geometry allows the direct observation of the unsteady flow structure in the spanwise dimension of the model and also allows the indirect observation of the boundary layer growth in the streamwise dimension.

  2. Spectrum of laser light scattered by nanoparticles in an ablation-induced cavitation bubble

    NASA Astrophysics Data System (ADS)

    Takeuchi, Masato; Sasaki, Koichi

    2016-04-01

    The spectrum of the laser light scattered by nanoparticles in a cavitation bubble, which was induced by laser ablation of a titanium target in water, was measured using a triple-grating spectrograph. The scattered laser light observed at 100 \\upmu s after laser ablation had no wavelength-shifted component, suggesting that nanoparticles at this delay time were metallic. The wavelength-shifted component was observed in the spectrum at a delay time of 200 \\upmu s, suggesting the formation of oxidized nanoparticles. However, we observed no peaks in the spectrum of the scattered laser light in the present in situ laser-light scattering experiment. On the other hand, we observed clear peaks in the Raman spectrum of synthesized nanoparticles. The experimental results suggest slow crystallization of nanoparticles in liquid in liquid-phase laser ablation.

  3. The Measurement of the Speed of Light Using a Laser Pointer.

    ERIC Educational Resources Information Center

    Mak, Se-yuen; Yip, Din-yan

    2000-01-01

    Presents a method for measuring the speed of light using a laser pointer with adjustable focus as the signal carrier, a signal generator to modulate the light beam, and a student oscilloscope to detect the phase shift. (Author/CCM)

  4. Light pipe design method and stepper experimentation for interference effects reduction in laser illumination

    NASA Astrophysics Data System (ADS)

    Poyet, Jean-Michel; Lutz, Yves

    2016-07-01

    The use of light pipes is an efficient and low-cost technique to get a homogeneous illumination for laser-gated viewing systems. However, this technique suffers from drawbacks when used with coherent sources like solid-state lasers. Compacting light pipe-based laser illuminators involves working with small light pipe sections, and experiments show that interference fringes appear on the laser illumination profiles. The principle of light pipe homogenization has been reviewed using geometrical optics to understand the phenomenon better, and a pragmatic light pipe design method, based on laser-gated viewing system parameters, is proposed. Another original solution based on optical stepper is studied to reduce both interference fringes and speckle noise to increase the homogeneity of laser illumination profiles.

  5. Semiconductor-to-metallic phase transition of VO2 by laser excitation

    NASA Astrophysics Data System (ADS)

    Liu, H.; Vasquez, O.; Santiago, V. R.; Diaz, L.; Fernandez, F. E.

    2004-10-01

    VO2 thin films deposited on MgO and fused silica glass substrates were prepared by the pulsed laser deposition (PLD) technique, which shows phase transition (PT) from the monoclinic semiconductor phase to a metallic tetragonal rutile structure at temperatures over 68°C. The observed PT is reversible, showing a typical hysteresis. The PT can also be induced through optical pumping by laser excitation. In this case, it was found that the optically induced PT is ultrafast and passive, but not thermally initiated. In order to understand the PT mechanism, a study of transient holography using degenerate-four-wavemixing (DFWM) measurement was conducted. A Nd:YAG pulsed laser with pulse duration of 30 psec operating at 532 nm was employed as the coherent light source. This showed that the observed transient holography in VO2 thin film is associated with the excited state dynamical process, which essentially causes the structural change, or so-called optically induced PT. The observed extremely large polarizability is believed to relate to the large offset in the potential well minimum between the ground state and excited state. Through an unidentified intermediate state, the transient lattice distortion triggered the structural change.

  6. Carbon ion beam focusing using laser irradiated heated diamond hemispherical shells

    SciTech Connect

    Offermann, Dustin T; Flippo, Kirk A; Gaillard, Sandrine A

    2009-01-01

    Experiments preformed at the Los Alamos National Laboratory's Trident Laser Facility were conducted to observe the acceleration and focusing of carbon ions via the TNSA mechanism using hemispherical diamond targets. Trident is a 200TW class laser system with 80J of 1 {micro}m, short-pulse light delivered in 0.5ps, with a peak intensity of 5 x 10{sup 20} W/cm{sup 2}. Targets where Chemical Vapor Deposition (CVD) diamonds formed into hemispheres with a radius of curvature of 400{micro}m and a thickness of 5{micro}m. The accelerated ions from the hemisphere were diagnosed by imaging the shadow of a witness copper mesh grid located 2mm behind the target onto a film pack located 5cm behind the target. Ray tracing was used to determine the location of the ion focal spot. The TNSA mechanism favorably accelerates hydrogen found in and on the targets. To make the carbon beam detectable, targets were first heated to several hundred degrees Celsius using a CW, 532nm, 8W laser. Imaging of the carbon beam was accomplished via an auto-radiograph of a nuclear activated lithium fluoride window in the first layer of the film pack. The focus of the carbon ion beam was determined to be located 630 {+-} 110 {micro}m from the vertex of the hemisphere.

  7. Laser mimicking mosquito bites for skin delivery of malaria sporozoite vaccines.

    PubMed

    Zhou, Chang; Chen, Xinyuan; Zhang, Qi; Wang, Ji; Wu, Mei X

    2015-04-28

    Immunization with radiation-attenuated sporozoites (RAS) via mosquito bites has been shown to induce sterile immunity against malaria in humans, but this route of vaccination is neither practical nor ethical. The importance of delivering RAS to the liver through circulation in eliciting immunity against this parasite has been recently verified by human studies showing that high-level protection was achieved only by intravenous (IV) administration of RAS, not by intradermal (ID) or subcutaneous (SC) vaccination. Here, we report in a murine model that ID inoculation of RAS into laser-illuminated skin confers immune protection against malarial infection almost as effectively as IV immunization. Brief illumination of the inoculation site with a low power 532 nm Nd:YAG laser enhanced the permeability of the capillary beneath the skin, owing to hemoglobin-specific absorbance of the light. The increased blood vessel permeability appeared to facilitate an association of RAS with blood vessel walls by an as-yet-unknown mechanism, ultimately promoting a 7-fold increase in RAS entering circulation and reaching the liver over ID administration. Accordingly, ID immunization of RAS at a laser-treated site stimulated much stronger sporozoite-specific antibody and CD8(+)IFN-γ(+) T cell responses than ID vaccination and provided nearly full protection against malarial infection, whereas ID immunization alone was ineffective. This novel, safe, and convenient strategy to augment efficacy of ID sporozoite-based vaccines warrants further investigation in large animals and in humans. PMID:25725360

  8. NASA`s airborne oceanographic lidar: A two excitation frequency laser fluorosensor

    SciTech Connect

    Wright, C.W.

    1996-10-01

    NASA has recently designed its AOL to acquire individual laser-induced fluorescence (LIF) spectra from two excitation frequencies emitted from a single laser transmitter. The backscattered laser-induced fluorescence (LEF) signal from each of the separate two footprints pass through the same optical train to form separate spectral images upon the focal plane of the AOL spectrometer. Other major modifications include a redesign of the AOL spectrometer to provide substantial reduction of scattered light and the inclusion of a narrow band (notch) holographic filter to reject 532nm radiation from the spectrometer. Results from initial mission show good signal-to-noise characteristics and has demonstrated high precision resolution for the measurement of chromophobic dissolved organic matter, chlorophyll, and phycoerythrin (an axillary pigment found in marine phytoplankton). The most significant result of these recent engineering modifications has been the development of the capability of the AOL to capture clean LEF signals from the two phycoerythrin pigments, phycourobilin and phycoerythrobilin. 12 refs., 4 figs.

  9. Comparative Study of Light Scattering from Hepatoma Cells and Hepatocytes

    NASA Astrophysics Data System (ADS)

    Lin, Xiaogang; Wang, Rongrong; Guo, Yongcai; Gao, Chao; Guo, Xiaoen

    2012-11-01

    Primary liver cancer is one of the highest mortality malignant tumors in the world. China is a high occurrence area of primary liver cancer. Diagnosis of liver cancer, especially early diagnosis, is essential for improving patients' survival. Light scattering and measuring method is an emerging technology developed in recent decades, which has attracted a large number of biomedical researchers due to its advantages, such as fast, simple, high accuracy, good repeatability, and non-destructive. The hypothesis of this project is that there may be some different light scattering information between hepatoma cells and hepatocyte. Combined with the advantages of the dynamic light scattering method and the biological cytology, an experimental scheme to measure the light scattering information of cells was formulated. Hepatoma cells and hepatic cells were irradiated by a semiconductor laser (532 nm). And the Brookhaven BI-200SM wide-angle light scattering device and temperature control apparatus were adopted. The light scattering information of hepatoma cells and hepatic cells in vitro within the 15°C to 30°C temperature range was processed by a BI-9000AT digital autocorrelator. The following points were found: (a) the scattering intensities of human hepatic cells and hepatoma cells are nearly not affected by the temperature factor, and the former is always greater than the latter and (b) the relaxation time of hepatoma cells is longer than that of hepatic cells, and both the relaxation time are shortened with increasing temperature from 15°C to 25°C. It can be concluded that hepatoma cells could absorb more incident light than hepatic cells. The reason may be that there exists more protein and nucleic acid in cancerous cells than normal cells. Furthermore, based on the length relaxation time, a conclusion can be inferred that the Brownian movement of cancer cells is greater.

  10. Nonvolatile holographic storage in iron-doped lithium tantalate with continuous-wave laser light.

    PubMed

    Imbrock, J; Kip, D; Krätzig, E

    1999-09-15

    Holograms have been recorded in congruent LiTaO(3):Fe with continuous-wave laser light by use of a two-step process. Blue gating light (lambda=488 nm) sensitizes the crystals for holographic recording with red light (lambda=660 nm) of a diode laser. Refractive-index changes of as much as 1.0x10(-5) are achieved for intensities of the red light of 1 W/cm(2) . The saturation values are proportional to the intensity of the writing light. Nondestructive readout with red light is possible, and the holograms remain erasable for blue light. PMID:18079787

  11. EFFECT OF LASER LIGHT ON MATTER. LASER PLASMAS: Recoil momentum at a solid surface during developed laser ablation

    NASA Astrophysics Data System (ADS)

    Kuznetsov, L. I.

    1993-12-01

    The recoil momentum from a laser light pulse in the intensity range 105-107 W/cm2 is experimentally investigated for dielectric and metallic targets as a function of the pressure of the surrounding medium and angle of illumination. An equation with empirical coefficients is obtained for the recoil momentum of illuminated targets. Effects of the screening properties of the erosion jet and the back pressure on the recoil momentum are analyzed as the external pressure is varied.

  12. Laser-initiated iodine radical chemistry in single microdroplets

    NASA Astrophysics Data System (ADS)

    Vaughn, Bartholomew S.; Tracey, Phillip J.; Trevitt, Adam J.

    2012-11-01

    Iodine radical reactions in single free-falling microdroplets of iodododecane, initiated using UV laser photolysis, are probed using Raman spectroscopy. Stimulated Raman spectra, with 532 nm laser excitation, are recorded at varying time delays from the UV pulse. I atom recombination reactions lead to I2 that changes the optical properties of the microdroplet ultimately quenching the Raman signal. This quenching is observed over ˜10 ns, which is about the time resolution of the two-laser experiment. Although the kinetics are too rapid to be measured in current laser configuration, it demonstrates that radical kinetics can be followed in single microdroplets.

  13. High efficiency CW green-pumped alexandrite lasers

    NASA Astrophysics Data System (ADS)

    Kuper, J. W.; Brown, D. C.

    2006-02-01

    High power, CW and pulsed alexandrite lasers were produced by pumping the laser rod with a high quality diode pumped 532 nm laser sources. This pumping architecture provides stable performance with output power > 1.4 W at 767nm in the free running mode and 0.78W at 1000 Hz. An output of 80 mW at 375.5 nm was achieved at 500 Hz. This approach holds promise for the production of a scalable diode-pumped, tunable alexandrite laser systems operating in the near infrared (750 nm), and the ultraviolet (375 and 250 nm) spectral regions.

  14. Invitation to the World of the Plasma for Light Source 3.Light Source Measurement 3.1 Laser Diagnostics of Plasmas for Light Sources

    NASA Astrophysics Data System (ADS)

    Motomura, Hideki; Jinno, Masafumi

    Examples and basic theories of various methods of laser diagnostics of plasmas for light sources are introduced. Most introduced papers were presented at International Symposium on the Science and Technology of Light Sources (LS), which is the only international symposium on the science and technology of light sources.

  15. Development of a versatile laser light scattering instrument

    NASA Technical Reports Server (NTRS)

    Meyer, William V.; Ansari, Rafat R.

    1990-01-01

    A versatile laser light scattering (LLS) instrument is developed for use in microgravity to measure microscopic particles of 30 A to above 3 microns. Since it is an optical technique, LLS does not affect the sample being studied. A LLS instrument built from modules allows several configurations, each optimized for a particular experiment. The multiangle LLS instrument can be mounted in the rack in the Space Shuttle and on Space Station Freedom. It is possible that a Space Shuttle glove-box and a lap-top computer containing a correlator card can be used to perform a number of experiments and to demonstrate the technology needed for more elaborate investigations. This offers simple means of flying a great number of experiments without the additional requirements of full-scale flight hardware experiments.

  16. Laser speckle tracking for monitoring and analysis of retinal photocoagulation

    NASA Astrophysics Data System (ADS)

    Seifert, Eric; Bliedtner, Katharina; Brinkmann, Ralf

    2014-02-01

    Laser coagulation of the retina is an established treatment for several retinal diseases. The absorbed laser energy and thus the induced thermal damage varies with the transmittance and scattering properties of the anterior eye media and with the pigmentation of the fundus. The temperature plays the most important role in the coagulation process. An established approach to measure a mean retinal temperature rise is optoacoustics, however it provides limited information on the coagulation. Phase sensitive OCT potentially offers a three dimensional temporally resolved temperature distribution but is very sensitive to slightest movements which are clinically hard to avoid. We develop an optical technique able to monitor and quantify thermally and coagulation induced tissue movements (expansions and contractions) and changes in the tissue structure by dynamic laser speckle analysis (LSA) offering a 2D map of the affected area. A frequency doubled Nd:YAG laser (532nm) is used for photocoagulation. Enucleated porcine eyes are used as targets. The spot is 100μm. A Helium Neon laser (HeNe) is used for illumination. The backscattered light of a HeNe is captured with a camera and the speckle pattern is analyzed. A Q-switched Nd:YLF laser is used for simultaneous temperature measurements with the optoacoustic approach. Radial tissue movements in the micrometer regime have been observed. The signals evaluation by optical flow algorithms and generalized differences tuned out to be able to distinguish between regions with and without immediate cell damage. Both approaches have shown a sensitivity of 93% and a specificity above 99% at their optimal threshold.

  17. Design and implementation of control system for range-gated underwater laser imaging

    NASA Astrophysics Data System (ADS)

    Ge, Wei-long; Zhang, Xiao-hui; Han, Hong-wei; Hua, Liang-hong

    2012-01-01

    There is currently considerable in developing underwater target detection, the underwater imaging system can be divided into active imaging system and passive system. The main feature of the active imaging system is that they use light sources to illuminate the targets and collect the reflection from targets. The advantages of active imaging system over passive imaging systems are high contrast and without the affection of environment sources. In this article, a range-gated underwater laser imaging system is built, which consists of laser illumination system, photoelectric imaging system and control system. The laser illumination system includes a light-pumped solid state doubled ND-YAG laser(532nm) which laser power and frequency can be adjusted and an optics expanding system of variable ratio. The photoelectric imaging system includes a gated Intensified CCD(ICCD) cameras which ICCD scheduling, gate width, delay time and gain can be adjusted and a optics received system of variable ratio. In order to acquire effectual target image using range-gated underwater laser imaging system, appropriate control parameters that include laser power and frequency, ICCD scheduling, gate width, delay time and gain, optics expanding system ratio and optics received system ratio must be given accurately. A control system which used C8051F320 and C8051F040 (MCU) as the core is designed, the control system can effectively control seven parameters that given above. The construction of software and hardware of the control system is introduced. And target image of underwater distance 25 m and 40m is given, Experimental results showed that the control system has high control precision, safe and stable operation and good speed adjusting performance can be achieved. It can be satisfied to apply to underwater target detection.

  18. Design and implementation of control system for range-gated underwater laser imaging

    NASA Astrophysics Data System (ADS)

    Ge, Wei-Long; Zhang, Xiao-Hui; Han, Hong-Wei; Hua, Liang-Hong

    2011-11-01

    There is currently considerable in developing underwater target detection, the underwater imaging system can be divided into active imaging system and passive system. The main feature of the active imaging system is that they use light sources to illuminate the targets and collect the reflection from targets. The advantages of active imaging system over passive imaging systems are high contrast and without the affection of environment sources. In this article, a range-gated underwater laser imaging system is built, which consists of laser illumination system, photoelectric imaging system and control system. The laser illumination system includes a light-pumped solid state doubled ND-YAG laser(532nm) which laser power and frequency can be adjusted and an optics expanding system of variable ratio. The photoelectric imaging system includes a gated Intensified CCD(ICCD) cameras which ICCD scheduling, gate width, delay time and gain can be adjusted and a optics received system of variable ratio. In order to acquire effectual target image using range-gated underwater laser imaging system, appropriate control parameters that include laser power and frequency, ICCD scheduling, gate width, delay time and gain, optics expanding system ratio and optics received system ratio must be given accurately. A control system which used C8051F320 and C8051F040 (MCU) as the core is designed, the control system can effectively control seven parameters that given above. The construction of software and hardware of the control system is introduced. And target image of underwater distance 25 m and 40m is given, Experimental results showed that the control system has high control precision, safe and stable operation and good speed adjusting performance can be achieved. It can be satisfied to apply to underwater target detection.

  19. Comparative effectiveness of light emitting diodes (LEDs) and Lasers in near infrared photoimmunotherapy.

    PubMed

    Sato, Kazuhide; Watanabe, Rira; Hanaoka, Hirofumi; Nakajima, Takahito; Choyke, Peter L; Kobayashi, Hisataka

    2016-03-22

    Near infrared photoimmunotherapy (NIR-PIT) is a new cancer treatment that combines the specificity of antibodies for targeting tumors with the toxicity induced by photosensitizers after exposure to near infrared (NIR) light. Herein we compare two NIR-light sources; light emitting diodes (LEDs) and Lasers, for their effectiveness in NIR-PIT. A photosensitizer, IRDye-700DX, conjugated to panitumumab (pan-IR700), was incubated with EGFR-expressing A431 and MDA-MB-468-luc cells. NIR-light was provided by LEDs or Lasers at the same light dose. Laser-light produced more cytotoxicity and greater reductions in IR700-fluorescence intensity than LED-light. Laser-light also produced more cytotoxicity in vivo in both cell lines. Assessment of super-enhanced permeability and retention (SUPR) effects were stronger with Laser than LED. These results suggest that Laser-light produced significantly more cytotoxic effects compared to LEDs. Although LED is less expensive, Laser-light produces superior results in NIR-PIT. PMID:26885688

  20. Comparative effectiveness of light emitting diodes (LEDs) and Lasers in near infrared photoimmunotherapy

    PubMed Central

    Sato, Kazuhide; Watanabe, Rira; Hanaoka, Hirofumi; Nakajima, Takahito; Choyke, Peter L.; Kobayashi, Hisataka

    2016-01-01

    Near infrared photoimmunotherapy (NIR-PIT) is a new cancer treatment that combines the specificity of antibodies for targeting tumors with the toxicity induced by photosensitizers after exposure to near infrared (NIR) light. Herein we compare two NIR-light sources; light emitting diodes (LEDs) and Lasers, for their effectiveness in NIR-PIT. A photosensitizer, IRDye-700DX, conjugated to panitumumab (pan-IR700), was incubated with EGFR-expressing A431 and MDA-MB-468-luc cells. NIR-light was provided by LEDs or Lasers at the same light dose. Laser-light produced more cytotoxicity and greater reductions in IR700-fluorescence intensity than LED-light. Laser-light also produced more cytotoxicity in vivo in both cell lines. Assessment of super-enhanced permeability and retention (SUPR) effects were stronger with Laser than LED. These results suggest that Laser-light produced significantly more cytotoxic effects compared to LEDs. Although LED is less expensive, Laser-light produces superior results in NIR-PIT. PMID:26885688

  1. Time-resolved spectral investigations of laser light induced microplasma

    NASA Astrophysics Data System (ADS)

    Nánai, L.; Hevesi, I.

    1992-01-01

    The dynamical and spectral properties of an optical breakdown microplasma created by pulses of different lasers on surfaces of insulators (KCI), metals (Cu) and semiconductors (V 2O 5), have been investigated. Experiments were carried out in air and vacuum using different wavelengths (λ = 0.694μm, type OGM-20,λ = 1.06μm with a home-made laser based on neodymium glass crystal, and λ = 10.6μm, similarly home-made) and pulse durations (Q-switched and free-running regimes). To follow the integral, dynamical and spectral characteristics of the luminous spot of microplasma we have used fast cameras (SFR-2M, IMACON-HADLAND), a high speed spectral camera (AGAT-2) and a spectrograph (STE-1). It has been shown that the microplasma consists of two parts: fast front (peak) with τ≈100 ns and slow front (tail) with τ≈1μs durations. The detonation front speed is of the order of ≈10 5 cm s -1 and follows the temporal dependence of to t0.4. It depends on the composition of the surrounding gas and its pressure and could be connected with quick evaporation of the material investigated (peak) and optical breakdown of the ambient gaseous atmosphere (tail). From the delay in appearance of different characteristic spectral lines of the target material and its gaseous surrounding we have shown that the evolution of the microplasma involves evaporation and ionization of the atoms of the parent material followed by optical breakdown due to the incident and absorbed laser light, together with microplasma expansion.

  2. Parametric investigation of laser-induced fluorescence of solid-state uranyl compounds.

    PubMed

    Wang, Guangjun; Su, Yi; Monts, David L

    2008-10-23

    The combination of remote/standoff sensing and laser-induced fluorescence (LIF) spectroscopy shows potential for detection of uranyl (UO2(2+)) compounds. Uranyl compounds exhibit characteristic emission in the 450-600 nm (22,200 to 16,700 cm(-1)) spectral region when excited by wavelengths in the ultraviolet or in the short-wavelength portion of the visible spectrum. We report a parametric study of the effects of excitation wavelength [including 532 nm (18,797 cm(-1)), 355 nm (28,169 cm(-1)), and 266 nm (37,594 cm(-1))] and excitation laser power on solid-state uranium compounds. The uranium compounds investigated include uranyl nitrate, uranyl sulfate, uranyl oxalate, uranium dioxide, triuranium octaoxide, uranyl acetate, uranyl formate, zinc uranyl acetate, and uranyl phosphate. We observed the characteristic uranyl fluorescence spectrum from the uranium compounds except for uranium oxide compounds (which do not contain the uranyl moiety) and for uranyl formate, which has a low fluorescence quantum yield. Relative uranyl fluorescence intensity is greatest for 355 nm excitation, and the order of decreasing fluorescence intensity with excitation wavelength (relative intensity/laser output) is 355 nm > 266 nm > 532 nm. For 532 nm excitation, the emission spectrum is produced by two-photon excitation. Uranyl fluorescence intensity increases linearly with increasing laser power, but the rate of fluorescence intensity increase is different for different emission bands. PMID:18823105

  3. Thermal Performance of III-Nitride Light Emitting Diodes and Developments in Laser Based White Lighting

    NASA Astrophysics Data System (ADS)

    Pfaff, Nathan Andrew

    Light emitting diodes, LEDs, have two distinct reductions in their efficiency. Efficiency droop which is a decrease in efficiency with increasing current density, and thermal droop, a reduction in efficiency with increasing temperature. Although there has been extensive work on efficiency droop and research into both the mitigation and causes of efficiency droop, comparably little research has been done on thermal droop. Since the early years of III-Nitride LEDs, have shown better performance than other materials systems used in visible light emitters when operated at increased temperatures. Due to the push for increased electrical efficiency thermal droop has been largely ignored or dealt with at a packaging level. Now LEDs are increasingly used in general illumination applications requiring high-current and high-flux operation resulting in elevated operating temperatures. In such high power applications LEDs can reach temperatures of over 100 °C where the performance can be significantly degraded. By altering the internal structure both below and within the active region the thermal droop of LEDs was reduced while preserving or enhancing electrical efficiency. Increased high temperature performance was observed on both blue c-plane and m-plane LEDs. Electrical droop which adversely affects LEDs in general illumination applications is difficult to mitigate. As an alternative to high-current, high-luminous flux LEDs for general illumination, phosphor converted laser, pc-LD, based white lighting is demonstrated. pc-LD shows virtually droop free performance over a wide range of high current densities with high luminous flux levels. The ability to achieve efficiencies on par with pc-LEDs, with significantly reduced substrate use and extremely high current operation, suggests that pc-LD white lighting has potential for entry into select white lighting applications in the near future. First demonstrations of pc-LD white lighting with general illumination level fluxes

  4. Shedding light: laser physics and mechanism of action.

    PubMed

    De Felice, E

    2010-02-01

    Lasers have affected health care in many ways. Clinical applications have been found in a number of medical and surgical specialities. In particular, applications of laser technology in phlebology has made it essential for vein physicians to obtain a fundamental knowledge of laser physics, laser operation and also to be well versed in laser safety procedures. This article reviews recommended text books and current literature to detail the basics of laser physics and its application to venous disease. Laser safety and laser side effects are also discussed. PMID:20118342

  5. Light-emitting diode versus laser irradiation phototherapy with lutetium texaphyrin (PCI-0123)

    NASA Astrophysics Data System (ADS)

    Woodburn, Kathryn W.; Young, Stuart W.; Qing, Fan; Miles, Dale R.; Thiemann, Patricia A.

    1997-05-01

    Lutetium texaphyrin (PCI-0123) is presently in clinical trials for the treatment of neoplasms. An argon-pumped dye laser has mostly been used to generate light for PCI-0123 photoactivation. However, lasers are expensive and produce a limited area of illumination, so the efficacy of light emitting diodes (LEDs) was investigated. An LED array was developed so that the spectral emission matched the far red absorption spectrum of PCI-0123. A preclinical PDT efficacy study comparing the laser and the LED was undertaken using EMT6-bearing animals. The LED and laser light sources were statistically comparable in eradicating the murine mammary sarcomas using PCI-0123 as the photosensitizer.

  6. Optical parameteric oscillation in MgO:LiNbO sub 3 driven by a diode pumped single frequencey q-switched laser

    SciTech Connect

    Gerstenberger, D.C.; Tye, G.E.; Wallace, R.W. )

    1990-01-01

    The authors report how they have obtained optical parametric oscillation tunable over the 940--1220 nm spectral region from a monolithic magnesium oxide doped lithium niobate ring resonator. The monolithic OPO was pumped by the 532 nm second harmonic of a diode laser pumped single frequency {ital Q}-switched Nd:YAG laser. The exceptional frequency and amplitude stability of the single frequency pump source provided stable OPO output pulses.

  7. Nanosecond pulsed laser blackening of copper

    NASA Astrophysics Data System (ADS)

    Tang, Guang; Hourd, Andrew C.; Abdolvand, Amin

    2012-12-01

    Nanosecond (12 ns) pulsed laser processing of copper at 532 nm resulted in the formation of homogenously distributed, highly organized microstructures. This led to the fabrication of large area black copper substrates with absorbance of over 97% in the spectral range from 250 nm to 750 nm, and a broadband absorbance of over 80% between 750 nm and 2500 nm. Optical and chemical analyses of the fabricated black metal are presented and discussed. The employed laser is an industrially adaptable source and the presented technique for fabrication of black copper could find applications in broadband thermal radiation sources, solar energy absorbers, irradiative heat transfer devices, and thermophotovoltaics.

  8. Laser radiation effects on Mycoplasma agalactiae

    NASA Astrophysics Data System (ADS)

    Dinu, Cerasela Z.; Grigoriu, Constantin; Dinescu, Maria; Pascale, Florentina; Popovici, Adrian; Gheorghescu, Lavinia; Cismileanu, Ana; Avram, Eugenia

    2002-08-01

    The biological effects of the laser radiation emitted by the Nd:YAG laser (second harmonic, wavelength 532 nm /fluence 32 mJ/cm2/pulse duration 6 ns) on the Mycoplasma agalactiae bacterium were studied. The radiation was found to intensify the multiplication of the bacteria irradiated in TRIS buffer (0.125 M), without however affecting the proteinic composition of the cell membrane. When the bacteria were irradiated in their growth medium (PPLO broth) being later cultivated on a solid medium (PPLO agar), the exclusive presence of the atypical colonies (granular and T-like ones) was noticed.

  9. Controlled laser delivery into biological tissue via thin-film optical tunneling and refraction

    NASA Astrophysics Data System (ADS)

    Whiteside, Paul J. D.; Goldschmidt, Benjamin S.; Curry, Randy; Viator, John A.

    2015-02-01

    Due to the often extreme energies employed, contemporary methods of laser delivery utilized in clinical dermatology allow for a dangerous amount of high-intensity laser light to reflect off a multitude of surfaces, including the patient's own skin. Such techniques consistently represent a clear and present threat to both patients and practitioners alike. The intention of this work was therefore to develop a technique that mitigates this problem by coupling the light directly into the tissue via physical contact with an optical waveguide. In this manner, planar waveguides cladded in silver with thin-film active areas were used to illuminate agar tissue phantoms with nanosecond-pulsed laser light at 532nm. The light then either refracted or optically tunneled through the active area, photoacoustically generating ultrasonic waves within the phantom, whose peak-to-peak intensity directly correlated to the internal reflection angle of the beam. Consequently, angular spectra for energy delivery were recorded for sub-wavelength silver and titanium films of variable thickness. Optimal energy delivery was achieved for internal reflection angles ranging from 43 to 50 degrees, depending on the active area and thin film geometries, with titanium films consistently delivering more energy across the entire angular spectrum due to their relatively high refractive index. The technique demonstrated herein therefore not only represents a viable method of energy delivery for biological tissue while minimizing the possibility for stray light, but also demonstrates the possibility for utilizing thin films of high refractive index metals to redirect light out of an optical waveguide.

  10. Laser system refinements to reduce variability in infarct size in the rat photothrombotic stroke model

    PubMed Central

    Alaverdashvili, Mariam; Paterson, Phyllis G.; Bradley, Michael P.

    2015-01-01

    Background The rat photothrombotic stroke model can induce brain infarcts with reasonable biological variability. Nevertheless, we observed unexplained high inter-individual variability despite using a rigorous protocol. Of the three major determinants of infarct volume, photosensitive dye concentration and illumination period were strictly controlled, whereas undetected fluctuation in laser power output was suspected to account for the variability. New method The frequently utilized Diode Pumped Solid State (DPSS) lasers emitting 532 nm (green) light can exhibit fluctuations in output power due to temperature and input power alterations. The polarization properties of the Nd:YAG and Nd:YVO4 crystals commonly used in these lasers are another potential source of fluctuation, since one means of controlling output power uses a polarizer with a variable transmission axis. Thus, the properties of DPSS lasers and the relationship between power output and infarct size were explored. Results DPSS laser beam intensity showed considerable variation. Either a polarizer or a variable neutral density filter allowed adjustment of a polarized laser beam to the desired intensity. When the beam was unpolarized, the experimenter was restricted to using a variable neutral density filter. Comparison with existing method(s) Our refined approach includes continuous monitoring of DPSS laser intensity via beam sampling using a pellicle beamsplitter and photodiode sensor. This guarantees the desired beam intensity at the targeted brain area during stroke induction, with the intensity controlled either through a polarizer or variable neutral density filter. Conclusions Continuous monitoring and control of laser beam intensity is critical for ensuring consistent infarct size. PMID:25840363

  11. Graphene Calisthenics: Straintronics of Graphene with Light-Reactive Azobenzene Polymer

    NASA Astrophysics Data System (ADS)

    Meaker, Kacey; Cao, Peigen; Huo, Mandy; Crommie, Michael

    2014-03-01

    Although a promising target for next-generation electronics, graphene's lack of a band gap is a severe hindrance. There are many ways of opening a gap, and one controllable way is through application of specific non-uniform strains which can produce extremely large pseudomagnetic fields. This effect was predicted and verified experimentally, but so far there have been few methods developed that reliably control the size, location, separation and amount of strain in graphene. We have used a layer of light-reactive azobenzene polymer beneath the graphene to produce strained monolayer graphene with light exposure. Using Raman spectroscopy, we have measured a shift of up to 20 cm-1 in the 2D peak when the graphene and polymer sample was exposed to 532 nm laser illumination indicating that the graphene is undergoing a strain from deformation of the azobenzene layer below. AFM topographic measurements and COMSOL simulations were used to verify this assertion. Use of polymeric materials to reliably strain graphene in non-uniform ways could result in controllable production of large pseudomagnetic fields in graphene and more control over graphene's low-energy charge carriers.

  12. Fluorescent all-fiber light source based on micro-capillaries and on microstructured optical fibers terminated with a microbulb

    NASA Astrophysics Data System (ADS)

    Vladev, Veselin; Eftimov, Tinko; Bock, Wojtek

    2015-12-01

    An integrated fiber-optic fluorescent light source compatible with photonic-crystal and hollow-core fibers is presented in this paper. We have studied the dependence of the fluorescence spectra on the length of a micro-capillary filled with Rhodamine 6G dissolved in glycerin. As the capillary, we used a standard fiber-optic glass ferrule with two parallel holes having an inner diameter of 125 μm. One of the holes was filled with fluorescing solution, while an SMF-28 fiber polished at 45° with aluminum coating was placed in the second hole to serve as a pumping fiber. As the solution was pumped by continuous-wave laser light at 532 nm, the fluorescence was captured by a microstructured optical fiber immersed in the filled hole. To prevent the solution from penetrating into this receiving fiber, its end was capped by molten borosilicate glass forming a ball lens. Combining the spectra of several fluorescent organic dyes can create a broadband light source compatible with optical fibers that could be used for the development of compact photonic-crystal and hollow-core fiber sensors.

  13. Scanning tunneling microscopic studies of laser-induced modifications of Si(001)-(2 x 1) surface

    SciTech Connect

    Yasui, Kosuke; Kanasaki, Jun'ichi

    2011-11-15

    Scanning tunneling microscopic studies of Si(001)-2 x 1 surfaces excited with 532-nm laser pulses of intensities below melting and ablation thresholds have revealed two different modes of structural modifications, strongly depending on the intensity of laser lights. The excitation below 100 mJ/cm{sup 2} causes bond rupture at individual dimer-sites leading to the formation of vacancies selectively on the outermost layer. The bond rupture, which shows a strongly site-sensitive rate, forms efficiently vacancy-strings elongated along the surface dimer-rows. Selective removal of surface dimers results in the exposure of flat and defect-less underlying layer as reported previously, which is resistive to the excitation at this range of intensity. At intensities above 100 mJ/cm{sup 2}, on the other hand, the excitation forms not only vacancies but also ad-dimers on terraces. The number density of ad-dimers is in proportion to the square of that for vacancies, indicating strongly that silicon atoms released by laser-induced bond rupture are associated with each other to form ad-dimers. The repeated irradiations at this range of intensities induce anisotropic growth of ad-dimer islands and of vacancy clusters on terrace regions, leading to multiply terraced structure. The primary processes of the structural modifications are discussed based on the quantitative analyses of the growth of vacancy and ad-dimer under excitation.

  14. 100-kHz-rate gas-phase thermometry using 100-ps pulses from a burst-mode laser.

    PubMed

    Roy, Sukesh; Hsu, Paul S; Jiang, Naibo; Slipchenko, Mikhail N; Gord, James R

    2015-11-01

    Temperature measurements based on gas-phase coherent anti-Stokes Raman scattering (CARS) spectroscopy are demonstrated in reacting flows at a rate of 100 kHz employing a burst-mode laser with a pulse duration of ∼100  ps. The recently developed picosecond-duration, high-energy burst-mode laser is used to pump an optical parametric generator/optical parametric amplifier that produces broadband light centered at ∼680  nm to provide the Stokes beams for excitation of the rovibrational Raman transitions of H(2). The 532-nm output of the picosecond burst-mode laser is then utilized as a pump beam for the CARS process that generates 100 single-shot spectra at a rate of 100 kHz during the 1-ms duration burst. Coherent spectroscopy-based temperature measurements at 100 kHz will significantly aid the understanding of transient and unsteady flow phenomena related to turbulent combustion, transonic and hypersonic flows, high-enthalpy flows, and the dynamics of energetic materials. PMID:26512535

  15. 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. PMID:23083193

  16. Near-infrared distributed feedback solgel lasers by intensity modulation and polarization modulation.

    PubMed

    Wang, Jun; Dong, Hongxing; Fan, Jintai; Li, Rihong; Zhang, Long; Wong, King Y

    2011-11-20

    Near-infrared distributed feedback (DFB) laser actions of Oxazine 725 dye in zirconia thin films and in silica bulks were investigated. Intensity modulation and polarization modulation were used to generate the DFB lasing. Wideband tuning of the output wavelength was achieved by varying the period of the modulation generated by a nanosecond Nd:YAG laser at 532 nm. Tuning ranges were 716-778 nm and 724-813 nm for the thin film lasers and the bulk lasers, respectively. The laser output showed different polarization characteristics and threshold energy variation when the feedback mechanism was changed from intensity modulation to polarization modulation. PMID:22108883

  17. Toxicity of laser irradiated photoactive fluoride PrF3 nanoparticles toward bacteria

    NASA Astrophysics Data System (ADS)

    Pudovkin, M. S.; Korableva, S. L.; Krasheninnicova, A. O.; Nizamutdinov, A. S.; Semashko, V. V.; Zelenihin, P. V.; Alakshin, E. M.; Nevzorova, T. A.

    2014-11-01

    The article is devoted to exploration of biological effects of crystalline PrF3 nanoparticles toward Salmonella typhimurium TA 98 bacteria under the laser irradiation. Obtained results show bactericidal activity of PrF3 nanoparticles and optimal parameters of laser irradiation (power of laser irradiation, wavelength, diameter of the laser spoil, and exposure time) have been found under which the effects of bactericidal activity become the most significant. Survival of bacterial cells under laser irradiation with wavelength 532 nm in colloidal solution of PrF3 nanoparticles was 39%, 34%, 20% for exposure times 5 minutes, 15 minutes and 30 minutes, correspondingly.

  18. Single shot thermometry using laser induced thermal grating

    NASA Astrophysics Data System (ADS)

    Qu, Pubo; Guan, Xiaowei; Zhang, Zhenrong; Wang, Sheng; Li, Guohua; Ye, Jingfeng; Hu, Zhiyun

    2015-05-01

    With the concern of environmental protection and reducing the fossil fuel consumption, combustion processes need to be more efficient and less contaminable. Therefore, the ability to obtain important thermophysical parameters is crucial to combustion research and combustor design. Traditional surveying techniques were difficult to apply in a confined space, especially the physically intrusions of detectors can alter the combustion processes. Laser-based diagnostic techniques, like CARS, SVRS, PLIF and TDLAS, allow the in situ, non-intrusive, spatially and temporally resolved measurements of combustion parameters in hostile environments. We report here a new non-intrusive optical diagnostic technique, based on laser-induced thermal grating. Thermal gratings generated in NO2/N2 binary mixtures, arise from the nonlinear interaction between the medium and the light radiation from the interference of two pulsed, frequency-doubled Nd:YAG lasers (532 nm). This leads to the formation of a dynamic grating through the resonant absorption and the subsequent collisional relaxation. By the temporally resolved detection of a continuous wave, frequency-doubled Nd:YVO4 probe laser beam (671 nm) diffracted by LITG. The temporal behavior of the signal is a function of the local temperature and other properties of gas, various parameters of the target gas can be extracted by analyzing the signal. The accurate singleshot temperature measurements were carried out at different test conditions using a stainless steel pressurized cell, data averaged on 100 laser shots were compared with simultaneously recorded thermocouple data, and the results were consistent with each other. The LITG signal is shown to grow with increasing the gas pressure and is spatially coherent, which makes the LITG thermometry technique a promising candidate in high pressure environments.

  19. Secondary laser cooling and capturing of thulium atoms in traps

    SciTech Connect

    Sukachev, D D; Kalganova, E S; Sokolov, A V; Fedorov, S A; Vishnyakova, G A; Akimov, A V; Kolachevsky, N N; Sorokin, V N

    2014-06-30

    Secondary laser cooling has been realised on the weak dipole transition 4f{sup 13}({sup 2}F{sup o})6s{sup 2}, J = 7/2, F=4 → 4f{sup 12}({sup 3}H{sub 6}) 5d{sub 5/2}6s{sup 2}, J' = 9/2, F' = 5 with the wavelength of 530.7 nm and natural width of 350 kHz. The temperature of the atomic cloud in a magnetooptical trap (MOT) was 30 μK at the lifetime of 2 s and the number of atoms 10{sup 5}. Approximately 1% of atoms from the MOT have been reloaded to an optical dipole trap and to one-dimensional optical lattice at the wavelength of 532 nm. The atom lifetime in the optical lattice was 320 ms. We propose to employ thulium atoms captured in an optical lattice as an optical frequency reference. (extreme light fields and their applications)

  20. Reusable, robust, and accurate laser-generated photonic nanosensor.

    PubMed

    Yetisen, Ali K; Montelongo, Yunuen; da Cruz Vasconcellos, Fernando; Martinez-Hurtado, J L; Neupane, Sankalpa; Butt, Haider; Qasim, Malik M; Blyth, Jeffrey; Burling, Keith; Carmody, J Bryan; Evans, Mark; Wilkinson, Timothy D; Kubota, Lauro T; Monteiro, Michael J; Lowe, Christopher R

    2014-06-11

    Developing noninvasive and accurate diagnostics that are easily manufactured, robust, and reusable will provide monitoring of high-risk individuals in any clinical or point-of-care environment. We have developed a clinically relevant optical glucose nanosensor that can be reused at least 400 times without a compromise in accuracy. The use of a single 6 ns laser (λ = 532 nm, 200 mJ) pulse rapidly produced off-axis Bragg diffraction gratings consisting of ordered silver nanoparticles embedded within a phenylboronic acid-functionalized hydrogel. This sensor exhibited reversible large wavelength shifts and diffracted the spectrum of narrow-band light over the wavelength range λpeak ≈ 510-1100 nm. The experimental sensitivity of the sensor permits diagnosis of glucosuria in the urine samples of diabetic patients with an improved performance compared to commercial high-throughput urinalysis devices. The sensor response was achieved within 5 min, reset to baseline in ∼10 s. It is anticipated that this sensing platform will have implications for the development of reusable, equipment-free colorimetric point-of-care diagnostic devices for diabetes screening. PMID:24844116

  1. Laser-driven phosphor-converted white light source for solid-state illumination.

    PubMed

    George, Anthony F; Al-waisawy, Sara; Wright, Jason T; Jadwisienczak, Wojciech M; Rahman, Faiz

    2016-03-10

    Energy efficiency and lighting quality considerations are driving research into laser-pumped white light sources. Laser diodes as pump sources for downconversion phosphors promise freedom from "droop" that adversely affects the efficiency of light-emitting diodes (LEDs). High-intensity laser diode-pumped light sources for applications such as search lights and automobile headlights have been demonstrated recently. Our paper describes the design and construction of a domestic/office-type solid-state luminaire driven by light from an integrated violet laser-diode module. A trichromatic phosphor made from a blend of separate europium-containing rare-earth phosphors was used as the downconversion medium. Mechanical and optical design of the reflector and the phosphor plate are described. Characteristics of both the pump light and the downconverted light are also described. Our studies also looked at the variation of chromaticity coordinates with variation in pump power and the effect of laser speckle on the lamp's light output. Finally, there is a brief discussion of energy conversion efficiency and longevity considerations, comparing pumping with LEDs versus pumping with laser diodes. PMID:26974780

  2. Laser-induced breakdown spectroscopic study of ammonium nitrate plasma

    SciTech Connect

    Hanif, M.; Salik, M.; Baig, M. A.

    2013-12-15

    We present the optical emission studies of the ammonium nitrate plasma produced by the fundamental (1064 nm) and second (532 nm) harmonics of a Q-switched Nd: YAG laser. The target material was placed in front of the laser beam in an open atmospheric air. The spectrum reveals numerous transitions of neutral nitrogen. We have studied the spatial behavior of the plasma temperature (T{sub e}) and electron number density (N{sub e}) determined using the Boltzmann plot method and Stark broadened line profiles, respectively. Besides, we have studied the variation of the plasma parameters as a function of the laser irradiance.

  3. Analysis of selective laser cleaning of patina on bronze coins

    NASA Astrophysics Data System (ADS)

    Buccolieri, G.; Nassisi, V.; Torrisi, L.; Buccolieri, A.; Castellano, A.; Di Giulio, M.; Giuffreda, E.; Delle Side, D.; Velardi, L.

    2014-04-01

    The patina, is the result of a large number of chemical, electrochemical and physical processes which occur spontaneously during interaction of metal surfaces with the environment. In this work we want to analyze and remove the patina in artefacts, exposed to atmosphere for various decades. Here, experimental results about the laser cleaning of bronze coins by KrF (248 nm) and Nd:YAG (532 nm) lasers are reported. Both laser wavelengths were efficient to reduce the chlorine concentration on the surface of the coins more than 80 %, as demonstrated by Energy Dispersive X-Ray Fluorescence analyses.

  4. MABEL photon-counting laser altimetry data in Alaska for ICESat-2 simulations and development

    NASA Astrophysics Data System (ADS)

    Brunt, Kelly M.; Neumann, Thomas A.; Amundson, Jason M.; Kavanaugh, Jeffrey L.; Moussavi, Mahsa S.; Walsh, Kaitlin M.; Cook, William B.; Markus, Thorsten

    2016-08-01

    Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) is scheduled to launch in late 2017 and will carry the Advanced Topographic Laser Altimeter System (ATLAS), which is a photon-counting laser altimeter and represents a new approach to satellite determination of surface elevation. Given the new technology of ATLAS, an airborne instrument, the Multiple Altimeter Beam Experimental Lidar (MABEL), was developed to provide data needed for satellite-algorithm development and ICESat-2 error analysis. MABEL was deployed out of Fairbanks, Alaska, in July 2014 to provide a test dataset for algorithm development in summer conditions with water-saturated snow and ice surfaces. Here we compare MABEL lidar data to in situ observations in Southeast Alaska to assess instrument performance in summer conditions and in the presence of glacier surface melt ponds and a wet snowpack. Results indicate the following: (1) based on MABEL and in situ data comparisons, the ATLAS 90 m beam-spacing strategy will provide a valid assessment of across-track slope that is consistent with shallow slopes (< 1°) of an ice-sheet interior over 50 to 150 m length scales; (2) the dense along-track sampling strategy of photon counting systems can provide crevasse detail; and (3) MABEL 532 nm wavelength light may sample both the surface and subsurface of shallow (approximately 2 m deep) supraglacial melt ponds. The data associated with crevasses and melt ponds indicate the potential ICESat-2 will have for the study of mountain and other small glaciers.

  5. Laser dosimetry for disabling anopheles stephensi mosquitoes in-flight (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Keller, Matthew D.; Norton, Bryan J.; Rutschman, Phil; Farrar, David J.; Marvit, Maclen; Makagon, Artyom

    2016-03-01

    The Photonic Fence is a system designed to detect mosquitoes and other pestilent flying insects in an active region and to apply lethal doses of laser light to them. Previously, we determined lethal fluence levels for a variety of lasers and pulse conditions on anesthetized Anopheles stephensi mosquitoes. In this work, similar studies were performed while the bugs were freely flying within transparent cages. Dose-response curves were created for various beam diameter, pulse width, and power conditions at 455 nm, 532 nm, 1064nm, and 1540 nm wavelengths. Besides mortality outcomes, the flight behavior of the bugs and the performance of the tracking system were monitored for consistency and to ensure that they had no impact on the mortality outcomes. As in anesthetized experiments, the visible wavelengths required significantly less fluence than near infrared wavelengths to reliably disable bugs. For the visible wavelengths, lethal fluence values were generally equivalent to those found in anesthetized dosing, while near infrared wavelengths required approximately twice the fluence compared with anesthetized experiments. The performance of the optical tracking system remained highly stable throughout the experiments, and it was found not to influence mortality results for pulse widths up to 25 ms. In general, keeping energy constant while decreasing power and increasing pulse width reduced mortality levels. The results of this study further affirm the practicality of using optical approaches to protect people and crops from flying insects.

  6. Determination of glucose concentration based on pulsed laser induced photoacoustic technique and least square fitting algorithm

    NASA Astrophysics Data System (ADS)

    Ren, Zhong; Liu, Guodong; Huang, Zhen

    2015-08-01

    In this paper, a noninvasive glucose concentration monitoring setup based on the photoacoustic technique was established. In this setup, a 532nm pumped Q switched Nd: YAG tunable pulsed laser with repetition rate of 20Hz was used as the photoacoustic excitation light source, and a ultrasonic transducer with central response frequency of 9.55MHz was used as the detector of the photoacoustic signal of glucose. As the preliminary exploration of the blood glucose concentration, a series of in vitro photoacoustic monitoring of glucose aqueous solutions by using the established photoacoustic setup were performed. The photoacoustic peak-to-peak values of different concentrations of glucose aqueous solutions induced by the pulsed laser with output wavelength of 1300nm to 2300nm in interval of 10nm were obtained with the average times of 512. The differential spectral and the first order derivative spectral method were used to get the characteristic wavelengths. For the characteristic wavelengths of glucose, the least square fitting algorithm was used to establish the relationship between the glucose concentrations and photoacoustic peak-to-peak values. The characteristic wavelengths and the predicted concentrations of glucose solution were obtained. Experimental results demonstrated that the prediction effect of characteristic wavelengths of 1410nm and 1510nm were better than others, and this photoacoustic setup and analysis method had a certain potential value in the monitoring of the blood glucose concentration.

  7. Development of an underwater laser imaging system for micro-bubbles

    NASA Astrophysics Data System (ADS)

    Wang, Yunying; Lv, Shuai; Wang, Hailu; Li, Guijuan; Guo, Yuanyuan

    2015-10-01

    Bubbles in the sea are important to the research of geography, chemical engineering, biology etc. This paper presented an underwater laser imaging system for micro-bubbles, including the design, construction and performance. The system using a series 532-nm laser for lighting, and transform a piece-source. The piece-source illumination and image an area of bubbles by a high resolution CCD. It is impossible to achievement imaging the bubbles with diameters from 10µm to 500µm at the same time, we use three different focus apertures to adapt the requirements of resolution and receiver field of view. We can change the adaptive aperture for bubbles with different diameters. The imaging capability of the system is tested in the laboratory. The solid targets of specified size have been imaged in the sink, and obtained the clear images of the target with 500µm and 10µm for three magnifications. In order to verify the reliability of the system, experiments were carried out in the marine to obtain the bubble distribution in the offshore area. The results of bubbles distribution characteristics showed that the distribution is basically according with index law.

  8. Laser induced optical bleaching in Ge12Sb25S63 chalcogenide thin film

    NASA Astrophysics Data System (ADS)

    Naik, Ramakanta; Jena, S.; Sahoo, N. K.

    2015-06-01

    Photo induced effects of Ge12Sb25S63 films illuminated with 532 nm laser light is investigated from transmission spectra measured by FTIR spectroscopy. The material exhibit photo bleaching (PB) when exposed to band gap laser for a prolonged time in vacuum. The PB is ascribed to structural changes inside the film as well as surface photo oxidation. The amorphous nature of thin films was detected by X-ray diffraction. The chemical composition of the deposited thin films was examined by Energy Dispersive X-ray Analysis (EDAX). The refractive indices of the films were obtained from the transmission spectra based on inverse synthesis method, and the optical band gaps were derived from optical absorption spectra using the Tauc plot. The dispersion of the refractive index is discussed in terms of the single-oscillator Wemple-DiDomenico model. It was found that, the mechanism of the optical absorption follows the rule of the allowed non-direct transition. Raman spectra analysis also supports the optical changes.

  9. Processing of Diamond for Integrated Optic Devices Using Q-Switched Nd:YAG Laser at Different Wavelengths

    NASA Astrophysics Data System (ADS)

    Sudheer, S. K.; Pillai, V. P. Mahadevan; Nayar, V. U.

    In the present investigation, a Q-switched Nd:YAG laser is used to study the various aspects of diamond processing for fabricating integrated optic and UV optoelectronic devices. Diamond is a better choice of substrate compared to silicon and gallium arsenide for the fabrication of waveguides to perform operations such as modulation, switching, multiplexing, and filtering, particularly in the ultraviolet spectrum. The experimental setup of the present investigation consists of two Q-Switched Nd:YAG lasers capable of operating at wavelengths of 1064 nm and 532 nm. The diamond cutting is performed using these two wavelengths by making the "V"-shaped groove with various opening angle. The variation of material loss of diamond during cutting is noted for the two wavelengths. The cut surface morphology and elemental and structural analysis of graphite formed during processing in both cases are compared using scanning electron microscopy (SEM) and laser Raman spectroscopy. Both the Q-Switched Nd:YAG laser systems (at 1064 nm and 532 nm) show very good performance in terms of peak-to-peak output stability, minimal spot diameter, smaller divergence angle, higher peak power in Q-switched mode, and good fundamental TEM00 mode quality for processing natural diamond stones. Less material loss and minimal micro cracks are achieved with wavelength 532 nm whereas a better diamond cut surface is achieved with processing at 1064 nm with minimum roughness.

  10. Reporting guide for laser-light shows and displays (21 CFR 1002)

    SciTech Connect

    Not Available

    1988-05-01

    The guide is to be used for reporting laser-light shows or displays incorporating Class IIIb or Class IV lasers only. Separate reports are not required for shows or displays that incorporate Class I, IIa, II, or IIIa laser-projection systems. Such show descriptions must be included in the user instructions and the report for the laser projector. Laser projectors used in any light shows or displays regardless of the class of the projector must be certified by the manufacturer and reported using the guide titled, Guide for Preparing Initial Reports and Model Change Reports on Lasers and Products Containing Lasers, HHS Publication FDA 86-8259. These guides assist manufacturers in providing the information that the Center for Devices and Radiological Health (CDRH) needs to determine how laser-light-shown projections and laser-light shows comply with the Federal standard for laser products (21 CDR 1040.10 and 1040.11) and with the conditions of an approved variance.

  11. Reduction of power fluctuation of laser light for collinear laser spectroscopy experiments at BECOLA facility at NSCL

    NASA Astrophysics Data System (ADS)

    Strum, Ryan; Barquest, Brad; Bollen, Georg; Miniamisono, Kei; Tarazona, David; Klose, Andrew; Mantica, Paul; Morrissey, Dave; Hughes, Max; Ringle, Ryan; Rodriguez, Alberto; Rossi, Dominic; Ryder, Caleb; Shwarz, Stefan; Sumithrarachchi, Chandana; Geppert, Cristopher

    2013-10-01

    The BEam COoler and LAser spectroscopy (BECOLA) facility at NSCL/MSU is designed to determine fundamental properties of the atomic nucleus such as the charge radii, nuclear spins and electromagnetic moments. Commissioning tests of BECOLA have been completed using a stable 39K beam produced from an offline ion source. The 39K beam was then cooled and bunched using a radiofrequency cooler and buncher, propagated collinearly with laser light and resulting fluorescence was detected. The laser light that was co-propagated with the beam was transported to the experimental area from a remote laser room via a single-mode optical fiber. Random rotation of the polarization of the laser light led to a large fluctuation in laser power, and hence a poor signal-to-noise ratio for the fluorescence measurement. A laser power controller was introduced to mitigate the power fluctuations. The performance characteristics of the power-stabilization system as well as the collinear laser spectroscopy of the bunched 39K beam will be discussed. This work was supported in part by the National Science Foundation, Grant PHY-11-02511.

  12. Comparison between blue lasers and light-emitting diodes for future solid-state lighting: Comparison between blue lasers and light-emitting diodes

    SciTech Connect

    Wierer, Jonathan J.; Tsao, Jeffrey Y.; Sizov, Dmitry S.

    2013-08-01

    Solid-state lighting (SSL) is now the most efficient source of high color quality white light ever created. Nevertheless, the blue InGaN light-emitting diodes (LEDs) that are the light engine of SSL still have significant performance limitations. Foremost among these is the decrease in efficiency at high input current densities widely known as “efficiency droop.” Efficiency droop limits input power densities, contrary to the desire to produce more photons per unit LED chip area and to make SSL more affordable. Pending a solution to efficiency droop, an alternative device could be a blue laser diode (LD). LDs, operated in stimulated emission, can have high efficiencies at much higher input power densities than LEDs can. In this article, LEDs and LDs for future SSL are explored by comparing: their current state-of-the-art input-power-density-dependent power-conversion efficiencies; potential improvements both in their peak power-conversion efficiencies and in the input power densities at which those efficiencies peak; and their economics for practical SSL.

  13. Rapid prototyping of reflectors for vehicle lighting using laser activated remote phosphor

    NASA Astrophysics Data System (ADS)

    Lachmayer, Roland; Kloppenburg, Gerolf; Wolf, Alexander

    2015-03-01

    Bright white light sources are of significant importance for automotive front lighting systems. Today's upper class vehicles mainly use HID or LED as light source. As a further step in this development laser diode based systems offer high luminance, efficiency and allow the realization of new styling concepts and new dynamic lighting functions. These white laser diode systems can either be realized by mixing different spectral sources or by combining diodes with specific phosphors. Based on the approach of generating light using a laser and remote phosphor, lighting modules are manufactured. Four blue laser diodes (450 nm) are used to activate a phosphor coating and thus to achieve white light. A segmented paraboloid reflector generates the desired light distribution for an additional car headlamp. We use high speed milling and selective laser melting to build the reflector system for this lighting module. We compare the spectral reflection grade of these materials. Furthermore the generated modules are analyzed regarding their efficiency and light distribution. The use of Rapid Prototyping technologies allows an early validation of the chosen concept and is supposed to reduce cost and time in the product development process significantly. Therefor we discuss costs and times of the applied manufacturing technologies.

  14. High average power quasi-CW single-mode green and UV fiber lasers

    NASA Astrophysics Data System (ADS)

    Avdokhin, Alexey; Gapontsev, Valentin; Kadwani, Pankaj; Vaupel, Andreas; Samartsev, Igor; Platonov, Nicholai; Yusim, Alex; Myasnikov, Daniil

    2015-02-01

    Kilowatt-level narrow-linewidth SM ytterbium fiber laser operating in high-repetition-rate QCW regime was used to obtain 700 W average power at 532 nm with single-mode beam quality and wall-plug efficiency of over 23 %. To the best of our knowledge, this is ~60 % higher power than previously reported for single-mode green lasers based on other platforms, and also is ~30 % increase comparing to the previous result obtained by our group on the base of similar fiber laser platform. We have also experimentally proved that the same type of fiber laser can be used for generating of world-record levels of power at other wavelengths of visible and UV spectral ranges by employing cascaded non-linear frequency conversion. Thus, utilizing frequency tripling in 2 LBO crystals, we achieved over 160 W average power of nearly single-mode UV light at 355 nm with THG efficiency of more than 25 %. As far as we know, this is the highest output power ever reported for UV laser with nearly diffraction limited beam quality. We also conducted some preliminary experiments to demonstrate suitability of our approach for generating longer wavelengths of the visible spectrum. By pre-shifting fundamental emission wavelength in fiber Raman converter, followed by frequency doubling in NCPM LBO, we obtained average powers of 36 W at 589 nm and 27 W at 615 nm. These proof-of-concept experiments were performed with low-power pump laser and were not fully optimized with respect to frequency conversion. Our analysis indicates that employing kW-level QCW ytterbium laser with optimized SRS and SHG converters we can achieve hundreds of Watts of average power in red and orange color with single-mode beam quality.

  15. Squeezed light from conventionally pumped multi-level lasers

    NASA Technical Reports Server (NTRS)

    Ralph, T. C.; Savage, C. M.

    1992-01-01

    We have calculated the amplitude squeezing in the output of several conventionally pumped multi-level lasers. We present results which show that standard laser models can produce significantly squeezed outputs in certain parameter ranges.

  16. Beamed neutron emission driven by laser accelerated light ions

    NASA Astrophysics Data System (ADS)

    Kar, S.; Green, A.; Ahmed, H.; Alejo, A.; Robinson, A. P. L.; Cerchez, M.; Clarke, R.; Doria, D.; Dorkings, S.; Fernandez, J.; Mirfayzi, S. R.; McKenna, P.; Naughton, K.; Neely, D.; Norreys, P.; Peth, C.; Powell, H.; Ruiz, J. A.; Swain, J.; Willi, O.; Borghesi, M.

    2016-05-01

    Highly anisotropic, beam-like neutron emission with peak flux of the order of 109 n/sr was obtained from light nuclei reactions in a pitcher–catcher scenario, by employing MeV ions driven by a sub-petawatt laser. The spatial profile of the neutron beam, fully captured for the first time by employing a CR39 nuclear track detector, shows a FWHM divergence angle of ∼ 70^\\circ , with a peak flux nearly an order of magnitude higher than the isotropic component elsewhere. The observed beamed flux of neutrons is highly favourable for a wide range of applications, and indeed for further transport and moderation to thermal energies. A systematic study employing various combinations of pitcher–catcher materials indicates the dominant reactions being d(p, n+p)1H and d(d,n)3He. Albeit insufficient cross-section data are available for modelling, the observed anisotropy in the neutrons’ spatial and spectral profiles is most likely related to the directionality and high energy of the projectile ions.

  17. Safe Helium--Neon Lasers Advance Understanding of Light

    ERIC Educational Resources Information Center

    Knowles, C. Harry

    1972-01-01

    Experimental data, Federal and State regulations, and user data are presented to assess the safety factors of low-power lasers. General safety precautions, basic laser theory, the place of the laser in the classroom, and some introductory exercises are also presented. (Author/TS)

  18. The potential of ill-nitride laser diodes for solid-state lighting [Advantages of III-Nitride Laser Diodes in Solid-State Lighting

    SciTech Connect

    Wierer, Jonathan; Tsao, Jeffrey Y.

    2014-09-01

    III-nitride laser diodes (LDs) are an interesting light source for solid-state lighting (SSL). Modelling of LDs is performed to reveal the potential advantages over traditionally used light-emitting diodes (LEDs). The first, and most notable, advantage is LDs have higher efficiency at higher currents when compared to LEDs. This is because Auger recombination that causes efficiency droop can no longer grow after laser threshold. Second, the same phosphor-converted methods used with LEDs can also be used with LDs to produce white light with similar color rendering and color temperature. Third, producing white light from direct emitters is equally challenging for both LEDs and LDs, with neither source having a direct advantage. Lastly, the LD emission is directional and can be more readily captured and focused, leading to the possibility of novel and more compact luminaires. These advantages make LDs a compelling source for future SSL.

  19. The potential of ill-nitride laser diodes for solid-state lighting [Advantages of III-Nitride Laser Diodes in Solid-State Lighting

    DOE PAGESBeta

    Wierer, Jonathan; Tsao, Jeffrey Y.

    2014-09-01

    III-nitride laser diodes (LDs) are an interesting light source for solid-state lighting (SSL). Modelling of LDs is performed to reveal the potential advantages over traditionally used light-emitting diodes (LEDs). The first, and most notable, advantage is LDs have higher efficiency at higher currents when compared to LEDs. This is because Auger recombination that causes efficiency droop can no longer grow after laser threshold. Second, the same phosphor-converted methods used with LEDs can also be used with LDs to produce white light with similar color rendering and color temperature. Third, producing white light from direct emitters is equally challenging for bothmore » LEDs and LDs, with neither source having a direct advantage. Lastly, the LD emission is directional and can be more readily captured and focused, leading to the possibility of novel and more compact luminaires. These advantages make LDs a compelling source for future SSL.« less

  20. The role of lasers and intense pulsed light technology in dermatology.

    PubMed

    Husain, Zain; Alster, Tina S

    2016-01-01

    The role of light-based technologies in dermatology has expanded dramatically in recent years. Lasers and intense pulsed light have been used to safely and effectively treat a diverse array of cutaneous conditions, including vascular and pigmented lesions, tattoos, scars, and undesired hair, while also providing extensive therapeutic options for cosmetic rejuvenation and other dermatologic conditions. Dermatologic laser procedures are becoming increasingly popular worldwide, and demand for them has fueled new innovations and clinical applications. These systems continue to evolve and provide enhanced therapeutic outcomes with improved safety profiles. This review highlights the important roles and varied clinical applications that lasers and intense pulsed light play in the dermatologic practice. PMID:26893574

  1. The role of lasers and intense pulsed light technology in dermatology

    PubMed Central

    Husain, Zain; Alster, Tina S

    2016-01-01

    The role of light-based technologies in dermatology has expanded dramatically in recent years. Lasers and intense pulsed light have been used to safely and effectively treat a diverse array of cutaneous conditions, including vascular and pigmented lesions, tattoos, scars, and undesired hair, while also providing extensive therapeutic options for cosmetic rejuvenation and other dermatologic conditions. Dermatologic laser procedures are becoming increasingly popular worldwide, and demand for them has fueled new innovations and clinical applications. These systems continue to evolve and provide enhanced therapeutic outcomes with improved safety profiles. This review highlights the important roles and varied clinical applications that lasers and intense pulsed light play in the dermatologic practice. PMID:26893574

  2. System for obtaining smooth laser beams where intensity variations are reduced by spectral dispersion of the laser light (SSD)

    DOEpatents

    Skupsky, Stanley; Kessler, Terrance J.; Short, Robert W.; Craxton, Stephen; Letzring, Samuel A.; Soures, John

    1991-01-01

    In an SSD (smoothing by spectral dispersion) system which reduces the time-averaged spatial variations in intensity of the laser light to provide uniform illumination of a laser fusion target, an electro-optic phase modulator through which a laser beam passes produces a broadband output beam by imposing a frequency modulated bandwidth on the laser beam. A grating provides spatial and angular spectral dispersion of the beam. Due to the phase modulation, the frequencies ("colors") cycle across the beam. The dispersed beam may be amplified and frequency converted (e.g., tripled) in a plurality of beam lines. A distributed phase plate (DPP) in each line is irradiated by the spectrally dispersed beam and the beam is focused on the target where a smooth (uniform intensity) pattern is produced. The color cycling enhances smoothing and the use of a frequency modulated laser pulse prevents the formation of high intensity spikes which could damage the laser medium in the power amplifiers.

  3. Organic semiconductor lasers as integrated light sources for optical sensor systems

    NASA Astrophysics Data System (ADS)

    Punke, Martin; Woggon, Thomas; Stroisch, Marc; Ebenhoch, Bernd; Geyer, Ulf; Karnutsch, Christian; Gerken, Martina; Lemmer, Uli; Bruendel, Mathias; Wang, Jing; Weimann, Thomas

    2007-09-01

    We demonstrate the feasibility of organic semiconductor lasers as light sources for lab-on-a-chip systems. These lasers are based on a 1D- or 2D-photonic crystal resonator structure providing optical feedback in the active laser material that is deposited on top, e.g. aluminum tris(8-hydroxyquinoline) (Alq 3) doped with the laser dye 4-dicyanomethylene-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM). We investigated different fabrication methods for the resonator structures, like thermal nanoimprint, UV nanoimprint, and laser interference lithography. Different substrate materials commonly used in lab-on-a-chip systems, e.g. PMMA, Topas, and Ormocer were deployed. By changing the distributed feedback grating periodicity, we demonstrate a tuning range for a single material system of more than 120 nm. The investigated organic semiconductor lasers are optically pumped. External optical pumping provides a feasible way for one-time-use chips. Our recent success of pumping organic lasers with a low-cost laser diode also renders hand-held systems possible. As a further step towards the integration of organic lasers in sensor systems, we demonstrate the coupling of an organic laser into polymeric waveguides which can be combined with microfluidic channels. The integrated organic lasers and the waveguides are both fabricated on the same polished PMMA substrate using thermal nanoimprint lithography and deep-UV modification, respectively. We could demonstrate the guiding of the laser light in single-mode waveguides.

  4. How many principles does it take to change a light bulb…into a laser?

    NASA Astrophysics Data System (ADS)

    Wiseman, Howard M.

    2016-03-01

    Quantum optics did not, and could not, flourish without the laser. The present paper is not about the principles of laser construction, still less a history of how the laser was invented. Rather, it addresses the question: what are the fundamental features that distinguish laser light from thermal light? The obvious answer, ‘laser light is coherent’, is, I argue, so vague that it must be put aside at the start, albeit to revisit later. A more specific, quantum theoretic, version, ‘laser light is in a coherent state’, is simply wrong in this context: both laser light and thermal light can equally well be described by coherent states, with amplitudes that vary stochastically in space. Instead, my answer to the titular question is that four principles are needed: high directionality, monochromaticity, high brightness, and stable intensity. Combining the first three of these principles suffices to show, in a quantitative way—involving, indeed, very large dimensionless quantities (up to ∼ {10}51)—that a laser must be constructed very differently from a light bulb. This quantitative analysis is quite simple, and is easily relatable to ‘coherence’, yet is not to be found in any textbooks on quantum optics to my knowledge. The fourth principle is the most subtle and, perhaps surprisingly, is the only one related to coherent states in the quantum optics sense: it implies that the description in terms of coherent states is the only simple description of a laser beam. Interestingly, this leads to the (not, as it turns out, entirely new) prediction that narrowly filtered laser beams are indistinguishable from similarly filtered thermal beams. I hope that other educators find this material useful; it may contain surprises even for researchers who have been in the field longer than I have.

  5. EFFECT OF LASER LIGHT ON MATTER. LASER PLASMAS: Optical visualization of the topography of a crater formed on a solid sample by a laser pulse

    NASA Astrophysics Data System (ADS)

    Vasil'ev, Sergei V.; Ivanov, A. Yu; Lyalikov, A. M.

    1993-06-01

    A fringe projection method has been used to determine the shape of a crater formed by applying laser light to a metal plate. The crater topography should be taken into account in thermal, acoustic, and plasma-dynamics calculations.

  6. Evaluation of the Nd/YAG laser for treatment of amateur and professional tattoos.

    PubMed

    Ferguson, J E; August, P J

    1996-10-01

    Two hundred and twenty-one amateur tattoos and 27 professional tattoos were treated with a Nd/YAG laser (lambda 1064 nm and 532 nm). The response was expressed as the percentage area cleared of tattoo. Seventy-nine per cent of amateur black tattoos were > or = 75% clear after one to five treatments (mean 2) at 1064 nm. The response of professional tattoos was slower and less complete. Seventy-four per cent of black professional tattoos were > or = 75% clear after one to 11 treatments (mean 6.3) at 1064 nm. Red tattoos responded well to 532 nm and were > or = 75% clear after one to five treatments. Yellow, orange, blue and green tattoos were resistant to treatment. Side-effects included minor scarring in 1.2% of tattoos and transient pigmentary changes in 77% of patients. PMID:8915151

  7. Dynamic Properties of Langmuir Films by Laser Light Scattering

    NASA Astrophysics Data System (ADS)

    Sanders, John Newell

    A technique and instrumentation for measuring visco-elastic properties of Langmuir film organic monolayers has been developed. This technique is used to characterize certain films used in the manufacture of Langmuir-Blodgett solid films. Furthermore a comparison of the dynamic viscous and elastic moduli determined by this technique is made with static values determined from the Pressure versus Area Isotherm. Briefly, a Langmuir film consists of amphiphilic organic molecules spread in a trough filled with pure water. The hydrophobic ends of the molecules trap them on the water surface. When spread at a dilute concentration the molecules exhibit two dimensional ideal gas behavior. By increasing the surface concentration one obtains two dimensional liquid and finally two dimensional solid behavior. The measurement is performed by electrodynamically driving the liquid surface with the electric field from a razor blade brought to within less than 1 mm of the surface. A sinusoidally varying electric field induces dipoles in the water subphase and generates waves at twice the driving frequency (Attractive dipoles are generated whether the field is positive or negative). The space propagation and damping of these waves is measured by laser light scattering. A focused laser beam incident on the surface is reflected at an angle due to the slope of the waves on the surface. By observing the movement of the beam the amplitude and phase of the oscillation with respect to the driving function may be determined (via a Lock-In amplifier) at various distances from the razor blade. One may directly profile the waves by translating the profiler, or one may observe the variation in amplitude and phase while scanning the frequency or surface pressure. In the latter cases one uses a known reference state to determine the wavelength and damping from the amplitude and phase change. This data is fit by a non-linear least squares curve fitting program to determine the wavelength and space

  8. The power of light: Self-organized formation of macroscopic amounts of silica melts controlled by laser light

    NASA Astrophysics Data System (ADS)

    Günster, J.; Oelgardt, C.; Heinrich, J. G.; Melcher, J.

    2009-01-01

    CO2 laser systems with a power output of up to 12kW continuous wave have been employed for melting high purity amorphous silica (SiO2) powders. Under the intense light irradiation, the migration of matter on the silica sample has been observed. A net mass transport results in the formation of macroscopic structures in the liquid phase. Protrusions of up to 7mm height are formed against gravitational force and surface tension. For the first time, this work reports on the self-organized formation of macroscopic structures by viscous flow of a dielectric melt driven by laser light.

  9. The power of light: Self-organized formation of macroscopic amounts of silica melts controlled by laser light

    SciTech Connect

    Guenster, J.; Oelgardt, C.; Heinrich, J. G.; Melcher, J.

    2009-01-12

    CO{sub 2} laser systems with a power output of up to 12 kW continuous wave have been employed for melting high purity amorphous silica (SiO{sub 2}) powders. Under the intense light irradiation, the migration of matter on the silica sample has been observed. A net mass transport results in the formation of macroscopic structures in the liquid phase. Protrusions of up to 7 mm height are formed against gravitational force and surface tension. For the first time, this work reports on the self-organized formation of macroscopic structures by viscous flow of a dielectric melt driven by laser light.

  10. Numerical Optimization of Sequential Cryogen Spray Cooling and Laser Irradiation for Improved Therapy of Port Wine Stain

    PubMed Central

    Milanič, Matija; Jia, Wangcun; Nelson, J Stuart; Majaron, Boris

    2011-01-01

    Background and Objective Despite application of cryogen spray (CS) precooling, customary treatment of port wine stain (PWS) birthmarks with a single laser pulse does not result in complete lesion blanching for a majority of patients. One obvious reason is nonselective absorption by epidermal melanin, which limits the maximal safe radiant exposure. Another possible reason for treatment failure is screening of laser light within large PWS vessels, which prevents uniform heating of the entire vessel lumen. Our aim is to identify the parameters of sequential CS cooling and laser irradiation that will allow optimal photocoagulation of various PWS blood vessels with minimal risk of epidermal thermal damage. Study Design and Methods Light and heat transport in laser treatment of PWS are simulated using a custom 3D Monte Carlo model and 2D finite element method, respectively. Protein denaturation in blood and skin are calculated using the Arrhenius kinetic model with tissue-specific coefficients. Simulated PWS vessels with diameters of 30–150 μm are located at depths of 200–600 μm, and shading by nearby vessels is accounted for according to PWS histology data from the literature. For moderately pigmented and dark skin phototypes, PWS blood vessel coagulation and epidermal thermal damage are assessed for various parameters of sequential CS cooling and 532-nm laser irradiation, i.e. the number of pulses in a sequence (1–5), repetition rate (7–30 Hz), and radiant exposure. Results Simulations of PWS treatment in darker skin phototypes indicate specific cooling/irradiation sequences that provide significantly higher efficacy and safety as compared to the customary single-pulse approach across a wide range of PWS blood vessel diameters and depths. The optimal sequences involve three to five laser pulses at repetition rates of 10–15 Hz. Conclusions Application of the identified cooling/irradiation sequences may offer improved therapeutic outcome for patients with

  11. Tunable optofluidic microring laser based on a tapered hollow core microstructured optical fiber.

    PubMed

    Li, Zhi-Li; Zhou, Wen-Yuan; Luo, Ming-Ming; Liu, Yan-Ge; Tian, Jian-Guo

    2015-04-20

    A tunable optofluidic microring dye laser within a tapered hollow core microstructured optical fiber was demonstrated. The fiber core was filled with a microfluidic gain medium plug and axially pumped by a nanosecond pulse laser at 532 nm. Strong radial emission and low-threshold lasing (16 nJ/pulse) were achieved. Lasing was achieved around the surface of the microfluidic plug. Laser emission was tuned by changing the liquid surface location along the tapered fiber. The possibility of developing a tunable laser within the tapered simplified hollow core microstructured optical fiber presents opportunities for developing liquid surface position sensors and biomedical analysis. PMID:25969082

  12. Dependence of multiply charged ions on the polarization state in nanosecond laser-benzene cluster interaction

    NASA Astrophysics Data System (ADS)

    Wang, Weiguo; Zhao, Wuduo; Hua, Lei; Hou, Keyong; Li, Haiyang

    2016-05-01

    This paper investigated the dependence of multiply charged ions on the laser polarization state when benzene cluster was irradiated with 532 and 1064 nm nanosecond laser. A circle, square and flower distribution for C2+, C3+ and C4+ were observed with 532 nm laser respectively, while flower petals for C2+, C3+ and C4+ were observed at 1064 nm as the laser polarization varied. A theoretical calculation was performed to interpret the polarization state and wavelength dependence of the multiply charged ions. The simulated results agreed well with the experimental observation with considering the contribution from the cluster disintegration.

  13. Use of a white light supercontinuum laser for confocal interference-reflection microscopy

    PubMed Central

    Chiu, L-D; Su, L; Reichelt, S; Amos, WB

    2012-01-01

    Shortly after its development, the white light supercontinuum laser was applied to confocal scanning microscopy as a more versatile substitute for the multiple monochromatic lasers normally used for the excitation of fluorescence. This light source is now available coupled to commercial confocal fluorescence microscopes. We have evaluated a supercontinuum laser as a source for a different purpose: confocal interferometric imaging of living cells and artificial models by interference reflection. We used light in the range 460–700 nm where this source provides a reasonably flat spectrum, and obtained images free from fringe artefacts caused by the longer coherence length of conventional lasers. We have also obtained images of cytoskeletal detail that is difficult to see with a monochromatic laser. PMID:22432542

  14. Laser equipment for investigation of light distribution in dental tissues and restorative materials

    NASA Astrophysics Data System (ADS)

    Grisimov, Vladimir N.; Smirmov, Alexander V.; Stafeev, Sergey C.

    1997-04-01

    The description of experimental set-up for investigation of light scattering in dental tissue and dental restorative material is presented. The set-up includes the light source (He-Ne laser), beam shaping light polarization control unit and registration device. The latter represents the computer interfaced CCD-camera. The experimental results of side light scattering in enamel/dentin and in double-layer porcelain are represented. The results of this research may be useful for aesthetic dental restorations.

  15. Elementary experiments in green laser vibrometry

    NASA Astrophysics Data System (ADS)

    Antończak, Arkadiusz J.; Kozioł, Paweł; Sotor, Jarosław Z.; Kaczmarek, Paweł R.; WąŻ, Adam T.; Abramski, Krzysztof M.

    2010-05-01

    The main disadvantage of He-Ne based Doppler vibrometer is low efficiency and high power consumption of the laser. Many application require compact, high efficiency, single frequency and narrow linewidth laser sources with the output power at the level of tens of mW. These requirements are fulfilled quite well by microchip lasers. Narrow linewidth at the level of a few kHz, single frequency operation, precise frequency tuning, very good beam quality and high efficiency (˜10%) of solid state single frequency green laser motivate us to use it as a laser source in LDV. In this paper, conception and practical realization of heterodyne laser vibrometry based on single frequency solid state microchip SHG laser operated at 532 nm is presented.

  16. Over 0.5 MW green laser from sub-nanosecond giant pulsed microchip laser

    NASA Astrophysics Data System (ADS)

    Zheng, Lihe; Taira, Takunori

    2016-03-01

    A sub-nanosecond green laser with laser head sized 35 × 35 × 35 mm3 was developed from a giant pulsed microchip laser for laser processing on organic superconducting transistor with a flexible substrate. A composite monolithic Y3Al5O12 (YAG) /Nd:YAG/Cr4+:YAG/YAG crystal was designed for generating giant pulsed 1064 nm laser. A fibercoupled 30 W laser diode centered at 808 nm was used with pump pulse duration of 245 μs. The 532 nm green laser was obtained from a LiB3O5 (LBO) crystal with output energy of 150 μJ and pulse duration of 268 ps. The sub-nanosecond green laser is interesting for 2-D ablation patterns.

  17. Design and implementation of omni-directional light source and receiving system used in underwater wireless optical communication

    NASA Astrophysics Data System (ADS)

    Rao, Jionghui; Yao, Wenming; Chen, Nannan

    2013-08-01

    Underwater wireless optical communication is a communication mode which uses light as an information carrier and water as transmission medium. As a result of the inherent characteristics of the light waves, underwater wireless optical communication has the advantages of high transmission rate, good security, and strong anti-interference ability. It is suitable for high-speed, short-range communication between underwater mobile vehicles. Underwater optical wireless communication system designed in this paper is composed of the omni-directional communication light source and the receiving system. In the omni-directional communication light source, the laser beams with small divergence angle of 532nm wavelength produced by modulated laser are expanded through a combination refraction-reflection solid and then obtain more than 2π space divergence angle. The paper use TRACEPRO simulation tool to help design a combination solid composed of the lens, conical reflector and parabolic reflector, and test in the air and underwater, the result shows that the effect is fine. Unlike in the air, light attenuation is heavy in the water and a large range of variations in light intensity at different distances appear during underwater optical communication. In order to overcome this problem, the paper use a small photomultiplier as the detection device, design the receiving system using the automatic gain control technique. Underwater wireless optical communication system designed in this paper has the characteristics of small size, low power dissipation and the omni-directional communication function, it is suitable for application in the UUV, AUV, Swimmer Delivery Vehicle (SDV) and other underwater mobile platform, it realizes point-to-point communications and point-to-multipoint communications.

  18. 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.

  19. Laser machined macro and micro structures on glass for enhanced light trapping in solar cells

    NASA Astrophysics Data System (ADS)

    Moore, David; Rahman, Mahfujur; Dowling, Denis P.; McNally, Patrick J.; Brabazon, Dermot

    2013-03-01

    In order to increase the efficiency of solar cell modules it is necessary to make the optimum use of light incident upon them. Much research has been done on improving light absorption through front surface texturisation and light trapping schemes. Laser light is commonly used in industry for various applications including marking and texturisation. By controlling laser parameters, it is possible to tailor macro and micro structures in most materials. The CO2 laser used in this investigation emits radiation at 10.6 μm with the ability to pulse in the micro-second range. The laser was used to ablate grooved textures in the fused quartz material, used in this study as the light trapping medium, following which an analysis of the effects of the laser parameters on the texture geometry and surface morphology was performed through a combination of cross sectioning and scanning electron microscopy. Transmission through the textured glass was improved for most samples after acid etching. The light trapping effects of the best performing textures were analysed by investigating the effects on a silicon solar cell's performance at varying angles of incidence. Results indicated a significant increase in light trapping when light was incident at acute angles. For an angle of incidence of 10∘ a relative increase in efficiency of up to 51 % was observed.

  20. Controlling the pulsed-laser-induced size reduction of Au and Ag nanoparticles via changes in the external pressure, laser intensity, and excitation wavelength.

    PubMed

    Werner, Daniel; Hashimoto, Shuichi

    2013-01-29

    The laser-induced size reduction of aqueous noble metal nanoparticles has been the subject of intensive research, because of the mechanistic interest in the light-nanoparticle interactions and its potential application to size control. The photothermal evaporation hypothesis has gained solid support. However, the polydispersity of the final products is considered as an inherent drawback of the method. It is likely that the polydispersity arises from the uncontrolled heat dissipation caused by vapor bubble formation in the ambient atmosphere. To overcome this problem, we applied high pressures of 30-100 MPa. The particle size was regulated by adjusting three parameters: the pressure, laser intensity, and excitation wavelength. For example, starting from a colloidal solution of 100 nm diameter gold nanoparticles, highly monodisperse (±3-5%) spheres with various diameters ranging from 90 to 30 nm were fabricated by tuning the laser intensity at 100 MPa, using an excitation wavelength of 532 nm. Further size reduction of the diameter to 20 nm was achieved by reducing the pressure and switching the excitation wavelength to 355 nm. It was found that the application of high pressures led to the heat loss-controlled size-reduction of the gold nanoparticles. More complicated results were obtained for 100 nm silver nanoparticles, possibly because of the different size-dependent light-absorbing nature of these particles. Based on our extensive experimental studies, a detailed picture was developed for the nanosecond laser-induced fabrication of gold and silver nanoparticles, leading to unprecedented size control. PMID:23259708

  1. Growth of GaAs “nano ice cream cones” by dual wavelength pulsed laser ablation

    NASA Astrophysics Data System (ADS)

    Schamp, C. T.; Jesser, W. A.; Shivaram, B. S.

    2007-05-01

    Harmonic generation crystals inherently offer the possibility of using multiple wavelengths of light in a single laser pulse. In the present experiment, the fundamental (1064 nm) and second harmonic (532 nm) wavelengths from an Nd:YAG laser are focused together on GaAs and GaSb targets for ablation. Incident energy densities up to about 45 J/cm 2 at 10 Hz with substrate temperatures between 25 and 600 °C for durations of about 60 s have been used in an ambient gas pressure of about 10 -6 Torr. The ablated material was collected on electron-transparent amorphous carbon films for TEM analysis. Apart from a high density of isolated nanocrystals, the most common morphology observed consists of a crystalline GaAs cone-like structure in contact with a sphere of liquid Ga, resembling an "ice cream cone", typically 50-100 nm in length. For all of the heterostuctures of this type, the liquid/solid/vacuum triple junction is found to correspond to the widest point on the cone. These heterostructures likely form by preferential evaporation of As from molten GaAs drops ablated from the target. The resulting morphology minimizes the interfacial and surface energies of the liquid Ga and solid GaAs.

  2. Iodine photodissociation laser with an intracavity space - time light modulator

    SciTech Connect

    Kachalin, G N; Pevny, S N; Pivkin, A N; Safronov, A S

    2012-08-31

    A scheme of an iodine laser with two different intracavity space - time modulators based on electrooptic PLZT ceramics is experimentally studied. It is shown that lasing can occur in different angular directions with the use of both modulators. The output laser energy is 10 mJ with a pulse duration of 200 {mu}s and a beam divergence of 6.3 Multiplication-Sign 10{sup -4} rad. The laser field of view (5.1 Multiplication-Sign 10{sup -3} rad) consists of a discrete set of 8 Multiplication-Sign 8 directions. (control of laser radiation parameters)

  3. Proceedings of the 5th International Symposium on Blue Laser and Light Emitting Diodes (ISBLLED-2004)

    NASA Astrophysics Data System (ADS)

    Suh, Eun-Kyung; Yoon, Euijoon; Lee, Hyung Jae

    2004-09-01

    The 5th International Symposium on Blue Laser and Light Emitting Diodes (ISBLLED-2004) was held in Gyeongju, Korea, 15-19 March 2004. The purpose of the symposium was to provide a forum for scientists and engineers to discuss recent progress and future trends in the rapidly advancing wide band gap semiconductor science and technologies and their applications in blue laser and light emitting diodes.

  4. Rapid Adiabatic Passage in a Rb gas with intense Frequency Chirped Laser Light

    NASA Astrophysics Data System (ADS)

    Kaufman, Brian; Grogan, Tanner; Paltoo, Tracy; Wright, Matthew

    We will discuss our progress toward using intense frequency chirped laser light to control the excitation of atoms in a room-temperature gas cell. We illuminate 87Rb atoms with a 1 GHz in 8 ns frequency chirped pulse of laser light covering the 5S1/2 F =1 --> 5P3/2 and explore the saturation behavior as intensity increases. We estimate that we are exciting over 90% of the atoms over 1 mm2.

  5. Diode-end-pumped, electro-optically Q-switched Nd:YVO4 slab laser and its second-harmonic generation.

    PubMed

    Zhang, Hengli; Shi, Peng; Li, Daijun; Du, Keming

    2003-03-20

    We describe the operation of a near-diffraction-limited, 1,064-nm electro-optically Q-switched Nd:YVO4 slab laser that is end pumped by laser-diode stacks and its efficient second-harmonic generation by using a lithium triborate (LBO) crystal. The energy per pulse of 3.6 and 0.8 mJ and pulse widths of 5 and 13.5 ns were obtained at repetition of 5 and 40 kHz, respectively. With a LBO crystal, a maximum output power of 15.6 W at 532 nm was obtained at the repetition rate of 40 kHz, the corresponding conversion efficiency was 60%, and the pulse width was 11.3 ns. At 10 kHz, the pulse energy of 532 nm was 1.2 mJ, and the pulse width was 5 ns. PMID:12665098

  6. Laser Light Scattering, from an Advanced Technology Development Program to Experiments in a Reduced Gravity Environment

    NASA Technical Reports Server (NTRS)

    Meyer, William V.; Tscharnuter, Walther W.; Macgregor, Andrew D.; Dautet, Henri; Deschamps, Pierre; Boucher, Francois; Zuh, Jixiang; Tin, Padetha; Rogers, Richard B.; Ansari, Rafat R.

    1994-01-01

    Recent advancements in laser light scattering hardware are described. These include intelligent single card correlators; active quench/active reset avalanche photodiodes; laser diodes; and fiber optics which were used by or developed for a NASA advanced technology development program. A space shuttle experiment which will employ aspects of these hardware developments is previewed.

  7. Effects of Laser Energy and Wavelength on the Analysis of LiFePO4 Using Laser Assisted Atom Probe Tomography

    SciTech Connect

    Santhanagopalan, Dhamodaran; Schreiber, Daniel K.; Perea, Daniel E.; Martens, Rich; Janssen, Yuri; Kalifah, Peter; Meng, Ying S.

    2015-01-21

    The effects of laser wavelength (355 nm and 532 nm) and laser pulse energy on the quantitative accuracy of atom probe tomography (APT) examinations of LiFePO4 (LFP) are considered. A systematic investigation of ultraviolet (UV, 355 nm) and green (532 nm) laser assisted APT of LFP has revealed distinctly different behaviors. With the use of UV laser the major issue was identified as the preferential loss of oxygen (up to 10 at. %) while other elements (Li, Fe and P) were observed to be close to nominal ratios. Lowering the laser energy per pulse to 1 pJ increased the observed oxygen concentration to near its correct stoichiometry and was well correlated with systematically higher concentrations of 16O2+ ions. This observation supports the premise that lower laser energies lead to a higher probability of oxygen molecule ionization. Conversely, at higher laser energies the resultant lower effective electric field reduces the probability of oxygen molecule ionization. Green laser assisted field evaporation led to the selective loss of Li (~50% deficiency) and correct ratios of the remaining elements, including the oxygen concentration. The loss of Li is explained by selective dc evaporation of lithium between laser pulses and relatively negligible oxygen loss as neutrals during green-laser pulsing. Lastly, plotting of multihit events on a Saxey plot for the straight-flight path data (green laser only) revealed a surprising dynamic recombination process for some molecular ions mid-flight.

  8. Laser Drilling - Drilling with the Power of Light

    SciTech Connect

    Brian C. Gahan; Samih Batarseh

    2005-09-28

    Gas Technology Institute (GTI) has been the leading investigator in the field of high power laser applications research for well construction and completion applications. Since 1997, GTI (then as Gas Research Institute) has investigated several military and industrial laser systems and their ability to cut and drill into reservoir type rocks. In this report, GTI continues its investigation with a recently acquired 5.34 kW ytterbium-doped multi-clad high power fiber laser (HPFL). The HPFL represents a potentially disruptive technology that, when compared to its competitors, is more cost effective to operate, capable of remote operations, and requires considerably less maintenance and repair. To determine how this promising laser would perform under high pressure in-situ conditions, GTI performed a number of experiments with results directly comparable to previous data. Experiments were designed to investigate the effect of laser input parameters on representative reservoir rock types of sandstone and limestone. The focus of the experiments was on completion and perforation applications, although the results and techniques apply to well construction and other rock cutting applications. All previous laser/rock interaction tests were performed on samples in the lab at atmospheric pressure. To determine the effect of downhole pressure conditions, a sophisticated tri-axial cell was designed and tested. For the first time, Berea sandstone, limestone and clad core samples were lased under various combinations of confining, axial and pore pressures. Composite core samples consisted of steel cemented to rock in an effort to represent material penetrated in a cased hole. The results of this experiment will assist in the development of a downhole laser perforation prototype tool. In the past, several combinations of laser and rock variables were investigated at standard conditions and reported in the literature. More recent experiments determined the technical feasibility of

  9. Tooth bleaching using three laser systems, halogen-light unit, and chemical action agents

    NASA Astrophysics Data System (ADS)

    Dostalova, Tatjana; Jelinkova, Helena; Housova, Devana; Sulc, Jan; Nemec, Michal; Koranda, Petr; Miyagi, Mitsunobu; Shi, Yi-Wei; Matsuura, Yuji

    2004-09-01

    μThe study describes the preclinical experience with laser-activated bleaching agent for discolored teeth. Extracted human upper central incisors were selected, and in the bleaching experiment 35% hydrogen peroxide was used. Three various laser systems and halogen-light unit for activation of the bleaching agent were applied. They were Alexandrite laser (wavelength 750 nm and 375 nm - SHG), Nd:YAG laser (wavelength 1.064 m), and Er:YAG laser (wavelength 2.94 μm). The halogen-light unit was used in a standard regime. The enamel surface was analyzed in the scanning electron microscope. The method of chemical oxidation results in a 2-3 shade change in one treatment. The halogen-light units produced the same effect with shorter time of bleaching process (from 630 s to 300 s). The Alexandrite laser (750 nm) and bleaching agent helped to reach the desired color shade after a shorter time (400 s). Alexandrite laser (375 nm) and Nd:YAG laser had no effect on the longevity of the process of bleaching. Overheating of the chemical bleaching agent was visible after Er:YAG laser activation (195 s). Slight surface modification after bleaching process was detected in SEM.

  10. Fractional CO2 Laser Versus Intense Pulsed Light in Treating Striae Distensae

    PubMed Central

    El Taieb, Moustafa Adam; Ibrahim, Ahmed Khair

    2016-01-01

    Context: Striae distensae are linear atrophic dermal scars covered with flat atrophic epidermis. They may cause disfigurement, especially in females. Many factors may cause striae distensae such as steroids, obesity, and pregnancy. Although there is no standard treatment for striae; many topical applications, peeling, and light and laser systems have been tried. Aims: To evaluate and compare the efficacy of fractional CO2 laser with intense pulse light in treating striae distensae. Subjects and Methods: Forty patients with striae distensae were recruited. Twenty of them were treated by fractional CO2 laser and 20 were treated with intense pulse light. Length and width of the largest striae were measured pre- and post-treatment. Patient satisfaction was also evaluated and graded. Patients were photographed after each treatment session and photos were examined by a blinded physician who had no knowledge about the cases. Results: Both groups showed significant improvement after treatments (P < 0.05). Patients treated with fractional CO2 laser showed significant improvement after the fifth session compared with those treated with ten sessions of intense pulsed light (P < 0.05) in all parameters except in the length of striae (P > 0.05). Conclusions: The current study has provided supportive evidence to the effectiveness of both fractional CO2 laser and intense pulse light as treatments for striae distensae. Fractional CO2 laser was found to be more effective in the treatment of striae distensae compared with intense pulse light. PMID:27057017

  11. Highly reliable 198-nm light source for semiconductor inspection based on dual fiber lasers

    NASA Astrophysics Data System (ADS)

    Imai, Shinichi; Matsuki, Kazuto; Kikuiri, Nobutaka; Takayama, Katsuhiko; Iwase, Osamu; Urata, Yoshiharu; Shinozaki, Tatsuya; Wada, Yoshio; Wada, Satoshi

    2010-02-01

    Highly reliable DUV light sources are required for semiconductor applications such as a photomask inspection. The mask inspection for the advanced devices requires the UV lightning wavelength beyond 200 nm. By use of dual fiber lasers as fundamental light sources and the multi-wavelength conversion we have constructed a light source of 198nm with more than 100 mW. The first laser is Yb doped fiber laser with the wavelength of 1064 nm; the second is Er doped fiber laser with 1560 nm. To obtain the robustness and to simplify the configuration, the fundamental lights are run in the pulsed operation and all wavelength conversions are made in single-pass scheme. The PRFs of more than 2 MHz are chosen as an alternative of a CW light source; such a high PRF light is equivalent to CW light for inspection cameras. The light source is operated described as follows. Automatic weekly maintenance within an hour is done if it is required; automatic monthly maintenance within 4 hours is done on fixed date per month; manufacturer's maintenance is done every 6 month. Now this 198 nm light sources are equipped in the leading edge photomask inspection machines.

  12. Surface and pulpal temperature comparison of tooth whitening using lasers and curing lights

    NASA Astrophysics Data System (ADS)

    White, Joel M.; Pelino, Jose; Rodrigues, Rively; Zwhalen, Brian J.; Nguyen, Max H.; Wu, Emily

    2000-03-01

    Chemical action of bleaching agents applied to tooth surface is accelerated by increase in temperature. This in vitro study measured the temperature rises on the surface and in the pulp of teeth during whitening using a diode laser, a plasma arc curing (PAC) light and conventional curing lights. Extracted, non-carious single-rooted teeth were exposed to PAC light and laser at times ranging from 10 to 60 seconds and energy ranges of 2 W, 4 W, and 6 W, and to low-intensity curing lights from 1 to 4 minutes. Maximum temperature rises were analyzed for both pulpal and surface temperature. Diode laser exposures at 2 W for all times and at 4 watts for 10 seconds and PAC light exposures at 10 seconds all produced acceptably safe pulpal rises equivalent to conventional light-curing exposures. Exposures at these settings also attained surface temperature rises that were significantly higher than those using conventional light-curing. The diode laser demonstrated bleaching results equivalent to the PAC light, and both were achieved in significantly less times than conventional light- curing.

  13. Theoretical study of diode-pumped Nd:YAG triple-frequency UV laser by LBO crystal

    NASA Astrophysics Data System (ADS)

    Dai, Qin; Liu, Yan-juan; Li, Ye-qui; Yao, Jun

    2011-06-01

    Based on the nonlinear three optical waves of coupling theory, the walk-off angle, effective nonlinear coefficients and the interaction length of wavelength of 1064nm and 532nm were calculated numerically under the condition of second class phase matching of the LBO crystals. In the phase matching range, the bigger the effective nonlinear coefficient and the smaller walk-off angle between 1064nm and 532nm beams, the higher frequency conversion efficiency. When the fundamental frequency light was an ideal Gaussian beam, the conversion efficiency improved with the crystal length increasing in the case of a particular power. And then, the conversion efficiency is limited by the fundamental frequency light was absorbed and the walk-off angle was increased with the crystal length increasing.

  14. Particle acceleration studies with intense lasers and advanced light sources

    NASA Astrophysics Data System (ADS)

    Murphy, C. D.; Gray, R. J.; MacLellan, D. A.; Rusby, D.; McKenna, P.; Ridgers, C. P.; Booth, N.; Robinson, A. P. L.; Wilson, L.; Green, J. S.

    2013-10-01

    The interaction of lasers with matter is a subject which has progressed rapidly over the last two decades as higher intensity lasers are found to have possible applications in inertial fusion, laboratory astrophysics and ion acceleration for oncology or ultrafast proton probing. All of these applications require a good understanding of laser-electron coupling and fast electron transport in solid targets which has proven difficult to diagnose. Here we present data from an experiment carried out on the Astra Gemini laser system at STFC-Rutherford Appleton Laboratory, where novel targets and diagnostics illuminate the complex processes at play. An outline of how x-ray free electron lasers may further expand our understanding of such processes will also be described.

  15. Pre-Conditioning with Low-Level Laser (Light) Therapy: Light Before the Storm

    PubMed Central

    Agrawal, Tanupriya; Gupta, Gaurav K.; Rai, Vikrant; Carroll, James D.; Hamblin, Michael R.

    2014-01-01

    Pre-conditioning by ischemia, hyperthermia, hypothermia, hyperbaric oxygen (and numerous other modalities) is a rapidly growing area of investigation that is used in pathological conditions where tissue damage may be expected. The damage caused by surgery, heart attack, or stroke can be mitigated by pre-treating the local or distant tissue with low levels of a stress-inducing stimulus, that can induce a protective response against subsequent major damage. Low-level laser (light) therapy (LLLT) has been used for nearly 50 years to enhance tissue healing and to relieve pain, inflammation and swelling. The photons are absorbed in cytochrome(c) oxidase (unit four in the mitochondrial respiratory chain), and this enzyme activation increases electron transport, respiration, oxygen consumption and ATP production. A complex signaling cascade is initiated leading to activation of transcription factors and up- and down-regulation of numerous genes. Recently it has become apparent that LLLT can also be effective if delivered to normal cells or tissue before the actual insult or trauma, in a pre-conditioning mode. Muscles are protected, nerves feel less pain, and LLLT can protect against a subsequent heart attack. These examples point the way to wider use of LLLT as a pre-conditioning modality to prevent pain and increase healing after surgical/medical procedures and possibly to increase athletic performance. PMID:25552961

  16. Applications of Light Amplification by Stimulated Emission of Radiation (Lasers) for Restorative Dentistry.

    PubMed

    Najeeb, Shariq; Khurshid, Zohaib; Zafar, Muhammad Sohail; Ajlal, Syed

    2016-01-01

    Light amplification by stimulated emission of radiation (laser) has been used widely in a range of biomedical and dental applications in recent years. In the field of restorative dentistry, various kinds of lasers have been developed for diagnostic (e.g. caries detection) and operative applications (e.g. tooth ablation, cavity preparation, restorations, bleaching). The main benefits for laser applications are patient comfort, pain relief and better results for specific applications. Major concerns for using dental lasers frequently are high cost, need for specialized training and sensitivity of the technique, thereby compromising its usefulness particularly in developing countries. The main aim of this paper is to evaluate and summarize the applications of lasers in restorative dentistry, including a comparison of the applications of lasers for major restorative dental procedures and conventional clinical approaches. A remarkable increase in the use of lasers for dental application is expected in the near future. PMID:26642047

  17. High-efficiency pyrromethene doped solid-state dye lasers

    SciTech Connect

    Hermes, R.E. ); Allik, T.H.; Chandra, S. ); Hutchinson, J.A. )

    1993-08-16

    Successful laser oscillation of various pyrromethene dyes doped in a modified acrylic plastic has been achieved. Pumped with a frequency doubled Nd:YAG laser at 532 nm, a slope efficiency of 85% has been obtained from one of the dyes in plastic, with an output beam energy of 128 mJ. A useful lifetime of greater than 20 000 shots at 3.33 Hz with output energies above 30 mJ has been demonstrated, with only a 34% loss in the available output energy.

  18. Polymer laser fabricated by a simple micromolding process

    NASA Astrophysics Data System (ADS)

    Lawrence, Justin R.; Turnbull, Graham A.; Samuel, Ifor D. W.

    2003-06-01

    We report polymer distributed feedback lasers fabricated using solvent-assisted microcontact molding. The poly[2-methoxy-5-(3,7-dimethyloctyloxy) paraphenylenevinylene] film is patterned by placing it in conformal contact with an elastomeric mould inked with a suitable solvent. When the resulting microstructured film is pumped with the 532 nm pulsed output of a microchip laser, we observe lasing above a threshold pump energy of 225 nJ. Above threshold the emission narrows to a linewidth of less than 0.6 nm at a wavelength of 638 nm. This micromolding technique may find application to a wide range of wavelength-scale microstructured organic photonic devices.

  19. Plasma and Cavitation Dynamics during Pulsed Laser Microsurgery in vivo

    SciTech Connect

    Hutson, M. Shane; Ma Xiaoyan

    2007-10-12

    We compare the plasma and cavitation dynamics underlying pulsed laser microsurgery in water and in fruit fly embryos (in vivo)--specifically for nanosecond pulses at 355 and 532 nm. We find two key differences. First, the plasma-formation thresholds are lower in vivo --especially at 355 nm--due to the presence of endogenous chromophores that serve as additional sources for plasma seed electrons. Second, the biological matrix constrains the growth of laser-induced cavitation bubbles. Both effects reduce the disrupted region in vivo when compared to extrapolations from measurements in water.

  20. Colloid formation and laser-induced bleaching in fluorite

    SciTech Connect

    LeBret, Joel B.; Cramer, Loren P.; Norton, M. Grant; Dickinson, J. T.

    2004-11-08

    Colloid formation and subsequent laser-induced bleaching in fluorite has been studied by transmission electron microscopy and electron diffraction. At high incident electron-beam (e-beam) energies, Ca colloids with diameter {approx}10 nm form a simple cubic superlattice with lattice parameter a{approx}18 nm. The colloids themselves are topotactic with the fluorite matrix forming low-energy interfaces close to a {sigma}=21 special grain boundary in cubic materials. Laser irradiation using {lambda}=532 nm has been shown to effectively bleach the e-beam-irradiated samples returning the fluorite to its monocrystalline state. The bleached samples appear more resistant to further colloid formation.

  1. Research on range-gated laser active imaging seeker

    NASA Astrophysics Data System (ADS)

    You, Mu; Wang, PengHui; Tan, DongJie

    2013-09-01

    Compared with other imaging methods such as millimeter wave imaging, infrared imaging and visible light imaging, laser imaging provides both a 2-D array of reflected intensity data as well as 2-D array of range data, which is the most important data for use in autonomous target acquisition .In terms of application, it can be widely used in military fields such as radar, guidance and fuse. In this paper, we present a laser active imaging seeker system based on range-gated laser transmitter and sensor technology .The seeker system presented here consist of two important part, one is laser image system, which uses a negative lens to diverge the light from a pulse laser to flood illuminate a target, return light is collected by a camera lens, each laser pulse triggers the camera delay and shutter. The other is stabilization gimbals, which is designed to be a rotatable structure both in azimuth and elevation angles. The laser image system consists of transmitter and receiver. The transmitter is based on diode pumped solid-state lasers that are passively Q-switched at 532nm wavelength. A visible wavelength was chosen because the receiver uses a Gen III image intensifier tube with a spectral sensitivity limited to wavelengths less than 900nm.The receiver is image intensifier tube's micro channel plate coupled into high sensitivity charge coupled device camera. The image has been taken at range over one kilometer and can be taken at much longer range in better weather. Image frame frequency can be changed according to requirement of guidance with modifiable range gate, The instantaneous field of views of the system was found to be 2×2 deg. Since completion of system integration, the seeker system has gone through a series of tests both in the lab and in the outdoor field. Two different kinds of buildings have been chosen as target, which is located at range from 200m up to 1000m.To simulate dynamic process of range change between missile and target, the seeker system has

  2. Geoscience Laser Altimeter System (GLAS) on the ICESat Mission: Initial Science Measurement Performance

    NASA Technical Reports Server (NTRS)

    Abshire, James B.; Sun, Xiaoli; Riris, Haris; Sirota, Marcos; McGarry, J.; Palm, Steve

    2003-01-01

    The Geoscience Laser Altimeter System is the space lidar on the NASA ICESat mission. Its design combines an altimeter with 5 cm precision with a laser pointing angle determination system and a dual wavelength cloud and aerosol lidar. GLAS measures the range to the Earth s surface with 1064 nm laser pulses. Each laser pulse produces a precision pointing measurement from the stellar reference system (SRS) and an echo pulse waveform, which permits range determination and waveform spreading analysis. The single shot ranging accuracy is < 10 cm for ice surfaces with slopes < 2 degrees. GLAS also measures atmospheric backscatter profiles at both 1064 and 532 nm. The 1064 nm measurements use an analog Si APD detector and measure the height and profile the backscatter signal from thicker clouds. The measurements at 532 nm use photon counting detectors, and will measure the vertical height distributions of optically thin clouds and aerosol layers Before launch, the measurement performance of GLAS was evaluated using a lidar test instrument called the Bench Check Equipment (BCE). The BCE was developed in parallel with GLAS and served as an inverse altimeter, inverse lidar and a stellar source simulator. It was used to simulate the range of expected optical inputs to the GLAS receiver by illuminating its telescope with simulated background light as well as laser echoes with known powers, energy levels, widths and delay times. The BCE also allowed monitoring of the transmitted laser energy, the angle measurements of the SRS, the co-alignment of the transmitted laser beam to the receiver line of sight, and performance of the flight science algorithms. Performance was evaluated during the GLAS development, before and after environmental tests, and after delivery to the spacecraft. The ICESat observatory was launched into a 94 degree inclination, 590 km altitude circular polar orbit on January 12,2003. Beginning in early February, GLAS was powered on tested in stages. Its 1064 nm

  3. Laser Drilling - Drilling with the Power of Light

    SciTech Connect

    Iraj A. Salehi; Brian C. Gahan; Samih Batarseh

    2007-02-28

    Gas Technology Institute (GTI) has been the leading investigator in the field of high power laser applications research for well construction and completion applications. Since 1997, GTI (then as Gas Research Institute- GRI) has investigated several military and industrial laser systems and their ability to cut and drill into reservoir type rocks. In this report, GTI continues its investigation with a 5.34 kW ytterbium-doped multi-clad high power fiber laser (HPFL). When compared to its competitors; the HPFL represents a technology that is more cost effective to operate, capable of remote operations, and requires considerably less maintenance and repair. Work performed under this contract included design and implementation of laboratory experiments to investigate the effects of high power laser energy on a variety of rock types. All previous laser/rock interaction tests were performed on samples in the lab at atmospheric pressure. To determine the effect of downhole pressure conditions, a sophisticated tri-axial cell was designed and tested. For the first time, Berea sandstone, limestone and clad core samples were lased under various combinations of confining, axial and pore pressures. Composite core samples consisted of steel cemented to rock in an effort to represent material penetrated in a cased hole. The results of this experiment will assist in the development of a downhole laser perforation or side tracking prototype tool. To determine how this promising laser would perform under high pressure in-situ conditions, GTI performed a number of experiments with results directly comparable to previous data. Experiments were designed to investigate the effect of laser input parameters on representative reservoir rock types of sandstone and limestone. The focus of the experiments was on laser/rock interaction under confining pressure as would be the case for all drilling and completion operations. As such, the results would be applicable to drilling, perforation, and

  4. Present Status and Future of EUV (Extreme Ultra Violet) Light Source Research 4.Laser Produced Plasma Light Sources 4.2High Average Power Laser Produced Plasma EUV Light Sources

    NASA Astrophysics Data System (ADS)

    Endo, Akira

    This paper reviews the research and development of the high average power, extreme ultraviolet light source based on laser produced plasma by EUVA. The technology is based on a liquid Xe micro jet, high repetition rate short pulse Nd:YAG laser, and various diagnostics for plasma optimization are described.

  5. Comparative efficiency analysis of GaN-based light-emitting diodes and laser diodes

    NASA Astrophysics Data System (ADS)

    Piprek, Joachim

    2016-07-01

    Nobel laureate Shuji Nakamura predicted in 2014 that GaN-based laser diodes are the future of solid state lighting. However, blue GaN-lasers still exhibit less than 40% wall-plug efficiency, while some GaN-based blue light-emitting diodes exceed 80%. This paper investigates non-thermal reasons behind this difference. The inherently poor hole conductivity of the Mg-doped waveguide cladding layer of laser diodes is identified as main reason for their low electrical-to-optical energy conversion efficiency.

  6. Once the Light Touch to the Brain: Cytotoxic Effects of Low-Dose Gamma-Ray, Laser Light, and Visible Light on Rat Neuronal Cell Culture

    PubMed Central

    Cakir, Murteza; Colak, Abdullah; Calikoglu, Cagatay; Taspinar, Numan; Sagsoz, Mustafa Erdem; Kadioglu, Hakan Hadi; Hacimuftuoglu, Ahmet; Seven, Sabriye

    2016-01-01

    Objective: We aimed to evaluate the effects of gamma-ray, laser light, and visible light, which neurons are commonly exposed to during treatment of various cranial diseases, on the viability of neurons. Materials and Methods: Neuronal cell culture was prepared from the frontal cortex of 9 newborn rats. Cultured cells were irradiated with gamma-ray for 1–10 min by 152Eu, 241Am, and 132Ba isotopes, visible light for 1–160 min, and laser light for 0.2–2 seconds. The MTT tetrazolium reduction assay was used to assess the number of viable cells in the neuronal cell cultures. Wavelength dispersive X-ray fluorescence spectrometer was used to determine Na, K, and Ca levels in cellular fluid obtained from neuronal cell culture plaques. Results: Under low-dose radiation with 152Eu, 241Am, and 132Ba isotopes, cell viability insignificantly decreased with time (p>0.05). On the other hand, exposure to visible light produced statistically significant decrease in cell viability at both short- (1–10 min) and long-term (20–160 min). Cell viability did not change with 2 seconds of laser exposure. Na, K, and Ca levels significantly decreased with gamma-ray and visible light. The level of oxidative stress markers significantly changed with gamma-ray. Conclusion: In conclusion, while low dose gamma-ray has slight to moderate apoptotic effect in neuronal cell cultures by oxidative stress, long-term visible light induces remarkable apoptosis and cell death. Laser light has no significant effect on neurons. Further genetic studies are needed to clarify the chronic effect of visible light on neuronal development and functions. PMID:27551168

  7. Laser Drilling - Drilling with the Power of Light

    SciTech Connect

    Brian C. Gahan; Samih Batarseh

    2004-09-28

    Gas Technology Institute (GTI) has been the leading investigator in the field of high power laser applications research for well construction and completion applications. Since 1997, GTI (then as Gas Research Institute) has investigated several military and industrial laser systems and their ability to cut and drill into reservoir type rocks. In this report, GTI continues its investigation with a recently acquired 5.34 kW ytterbium-doped multi-clad high power fiber laser (HPFL). The HPFL represents a potentially disruptive technology that, when compared to its competitors, is more cost effective to operate, capable of remote operations, and requires considerably less maintenance and repair. To determine how this promising laser compares with other lasers used in past experimental work, GTI performed a number of experiments with results directly comparable to previous data. Experiments were designed to investigate the effect of laser input parameters on representative reservoir rock types of sandstone and limestone. The focus of the experiments was on completion and perforation applications, although the results and techniques apply to well construction and other rock cutting applications. Variables investigated include laser power, beam intensity, external purging of cut materials, sample orientation, beam duration, beam shape, and beam frequency. The investigation also studied the thermal effects on the two sample rock types and their methods of destruction: spallation for sandstone, and thermal dissociation for limestone. Optimal operating conditions were identified for each rock type and condition. As a result of this experimental work, the HPFL has demonstrated a better capability of cutting and drilling limestone and sandstone when compared with other military and industrial lasers previously tested. Consideration should be given to the HPFL as the leading candidate for near term remote high power laser applications for well construction and completion.

  8. Fungicidal response of a novel natural photosensitizer (Beta vulgaris) on Candida albicans with low-power laser radiation

    NASA Astrophysics Data System (ADS)

    Mittal, Subhangi; Roy, Sukhdev; Srivastava, J. N.

    2013-05-01

    We report the efficacy of an aqueous extract of Beta vulgaris as a novel, natural photosensitizer for use in photodynamic therapy against Candidiasis disease. This study evaluates the effect of different laser wavelengths (He-Ne: 633 nm, Nd-YAG: 532 nm), power (17, 27 mW) and duration of exposure (5, 10, 15 min) in combination with the Beta vulgaris natural photosensitizer on the viability of Candida albicans causing Candidiasis disease. Although inhibition was observed in all cases, a maximum of 51.91% inhibition takes place with the combination of Beta vulgaris exposed to 532 nm at 27 mW for 15 min by the Agar well diffusion method. The study is important in optimizing different parameters and designing a low-power, compact, non-invasive and portable device for treatment.

  9. Micro-scanning mirrors for high-power laser applications in laser surgery

    NASA Astrophysics Data System (ADS)

    Sandner, Thilo; Kimme, Simon; Grasshoff, Thomas; Todt, Ulrich; Graf, Alexander; Tulea, Cristian; Lenenbach, Achim; Schenk, Harald

    2014-03-01

    We present two novel micro scanning mirrors with large aperture and HR dielectric coatings suitable for high power laser applications in a miniaturized laser-surgical instrument for neurosurgery to cut skull tissue. An electrostatic driven 2D-raster scanning mirror with 5x7.1mm aperture is used for dynamic steering of a ps-laser beam of the laser cutting process. A second magnetic 2D-beam steering mirror enables a static beam correction of a hand guided laser instrument. Optimizations of a magnetic gimbal micro mirror with 6 mm x 8 mm mirror plate are presented; here static deflections of 3° were reached. Both MEMS devices were successfully tested with a high power ps-laser at 532nm up to 20W average laser power.

  10. Generation of high-power laser light with Gigahertz splitting.

    PubMed

    Unks, B E; Proite, N A; Yavuz, D D

    2007-08-01

    We demonstrate the generation of two high-power laser beams whose frequencies are separated by the ground state hyperfine transition frequency in (87)Rb. The system uses a single master diode laser appropriately shifted by high frequency acousto-optic modulators and amplified by semiconductor tapered amplifiers. This produces two 1 W laser beams with a frequency spacing of 6.834 GHz and a relative frequency stability of 1 Hz. We discuss possible applications of this apparatus, including electromagnetically induced transparency-like effects and ultrafast qubit rotations. PMID:17764314

  11. Laser driven light sails: An examination of the possibilities for interstellar probes and other missions

    NASA Technical Reports Server (NTRS)

    Rather, J. D. G.; Zeiders, G. W.; Vogelsang, K. R.

    1976-01-01

    A theoretical discussion of high energy laser propelled light sails is presented. Selection of sail materials, interstellar drag forces, beam pointing, flight velocity, probe mass, and radiation shielding are among the factors discussed. Interstellar probe missions and colonization of the solar system via the light sail are considered.

  12. Electrically switchable organo–inorganic hybrid for a white-light laser source

    NASA Astrophysics Data System (ADS)

    Huang, Jui-Chieh; Hsiao, Yu-Cheng; Lin, Yu-Ting; Lee, Chia-Rong; Lee, Wei

    2016-06-01

    We demonstrate a spectrally discrete white-light laser device based on a photonic bandgap hybrid, which is composed of a soft photonic crystal; i.e., a layer of dye-doped cholesteric liquid crystal (CLC), sandwiched between two imperfect but identical, inorganic multilayer photonic crystals. With a sole optical pump, a mono-, bi-, or tri-chromatic laser can be obtained and, through the soft photonic crystal regulated by an applied voltage, the hybrid possesses electrical tunability in laser wavelength. The three emitted spectral peaks originate from two bandedges of the CLC reflection band as well as one of the photonic defect modes in dual-mode lasing. Thanks to the optically bistable nature of CLC, such a white-light laser device can operate in quite an energy-saving fashion. This technique has potential to fulfill the present mainstream in the coherent white-light source.

  13. Electrically switchable organo–inorganic hybrid for a white-light laser source

    PubMed Central

    Huang, Jui-Chieh; Hsiao, Yu-Cheng; Lin, Yu-Ting; Lee, Chia-Rong; Lee, Wei

    2016-01-01

    We demonstrate a spectrally discrete white-light laser device based on a photonic bandgap hybrid, which is composed of a soft photonic crystal; i.e., a layer of dye-doped cholesteric liquid crystal (CLC), sandwiched between two imperfect but identical, inorganic multilayer photonic crystals. With a sole optical pump, a mono-, bi-, or tri-chromatic laser can be obtained and, through the soft photonic crystal regulated by an applied voltage, the hybrid possesses electrical tunability in laser wavelength. The three emitted spectral peaks originate from two bandedges of the CLC reflection band as well as one of the photonic defect modes in dual-mode lasing. Thanks to the optically bistable nature of CLC, such a white-light laser device can operate in quite an energy-saving fashion. This technique has potential to fulfill the present mainstream in the coherent white-light source. PMID:27324219

  14. Laser-Modified Black Titanium Oxide Nanospheres and Their Photocatalytic Activities under Visible Light.

    PubMed

    Chen, Xing; Zhao, Dongxu; Liu, Kewei; Wang, Chunrui; Liu, Lei; Li, Binghui; Zhang, Zhenzhong; Shen, Dezhen

    2015-07-29

    A facile pulse laser ablation approach for preparing black titanium oxide nanospheres, which could be used as photocatalysts under visible light, is proposed. The black titanium oxide nanospheres are prepared by pulsed-laser irradiation of pure titanium oxide in suspended aqueous solution. The crystalline phases, morphology, and optical properties of the obtained nanospheres are characterized by means of X-ray diffraction (XRD), field-emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS), and UV-vis-NIR diffuse reflectance spectroscopy. It is shown that high-energy laser ablation of titanium oxide suspended solution benefited the formation of Ti(3+) species and surface disorder on the surface of the titanium oxide nanospheres. The laser-modified black titanium oxide nanospheres could absorb the full spectrum of visible light, thus exhibiting good photocatalytic performance under visible light. PMID:26132217

  15. Analysis of lasers as a solution to efficiency droop in solid-state lighting

    DOE PAGESBeta

    Chow, Weng W.; Crawford, Mary H.

    2015-10-06

    This letter analyzes the proposal to mitigate the efficiency droop in solid-state light emitters by replacing InGaN light-emitting diodes (LEDs) with lasers. The argument in favor of this approach is that carrier-population clamping after the onset of lasing limits carrier loss to that at threshold, while stimulated emission continues to grow with injection current. A fully quantized (carriers and light) theory that is applicable to LEDs and lasers (above and below threshold) is used to obtain a quantitative evaluation. The results confirm the potential advantage of higher laser output power and efficiency above lasing threshold, while also indicating disadvantages includingmore » low efficiency prior to lasing onset, sensitivity of lasing threshold to temperature, and the effects of catastrophic laser failure. As a result, a solution to some of these concerns is suggested that takes advantage of recent developments in nanolasers.« less

  16. Electrically switchable organo-inorganic hybrid for a white-light laser source.

    PubMed

    Huang, Jui-Chieh; Hsiao, Yu-Cheng; Lin, Yu-Ting; Lee, Chia-Rong; Lee, Wei

    2016-01-01

    We demonstrate a spectrally discrete white-light laser device based on a photonic bandgap hybrid, which is composed of a soft photonic crystal; i.e., a layer of dye-doped cholesteric liquid crystal (CLC), sandwiched between two imperfect but identical, inorganic multilayer photonic crystals. With a sole optical pump, a mono-, bi-, or tri-chromatic laser can be obtained and, through the soft photonic crystal regulated by an applied voltage, the hybrid possesses electrical tunability in laser wavelength. The three emitted spectral peaks originate from two bandedges of the CLC reflection band as well as one of the photonic defect modes in dual-mode lasing. Thanks to the optically bistable nature of CLC, such a white-light laser device can operate in quite an energy-saving fashion. This technique has potential to fulfill the present mainstream in the coherent white-light source. PMID:27324219

  17. Analysis of lasers as a solution to efficiency droop in solid-state lighting

    SciTech Connect

    Chow, Weng W.; Crawford, Mary H.

    2015-10-06

    This letter analyzes the proposal to mitigate the efficiency droop in solid-state light emitters by replacing InGaN light-emitting diodes (LEDs) with lasers. The argument in favor of this approach is that carrier-population clamping after the onset of lasing limits carrier loss to that at threshold, while stimulated emission continues to grow with injection current. A fully quantized (carriers and light) theory that is applicable to LEDs and lasers (above and below threshold) is used to obtain a quantitative evaluation. The results confirm the potential advantage of higher laser output power and efficiency above lasing threshold, while also indicating disadvantages including low efficiency prior to lasing onset, sensitivity of lasing threshold to temperature, and the effects of catastrophic laser failure. As a result, a solution to some of these concerns is suggested that takes advantage of recent developments in nanolasers.

  18. High flux, narrow bandwidth compton light sources via extended laser-electron interactions

    SciTech Connect

    Barty, V P

    2015-01-13

    New configurations of lasers and electron beams efficiently and robustly produce high flux beams of bright, tunable, polarized quasi-monoenergetic x-rays and gamma-rays via laser-Compton scattering. Specifically, the use of long-duration, pulsed lasers and closely-spaced, low-charge and low emittance bunches of electron beams increase the spectral flux of the Compton-scattered x-rays and gamma rays, increase efficiency of the laser-electron interaction and significantly reduce the overall complexity of Compton based light sources.

  19. Spectroscopic measurements of ablation plasma generated with laser-driven intense extreme ultraviolet (EUV) light

    NASA Astrophysics Data System (ADS)

    Tanaka, N.; Hane, K.; Shikata, H.; Masuda, M.; Nagatomi, K.; Sunahara, A.; Yoshida, M.; Fujioka, S.; Nishimura, H.

    2016-03-01

    Material ablation by a focused Extreme ultraviolet (EUV) light is studied by comparing expanding ion properties and plasma parameters with laser ablation. The kinetic energy distributions of expanding ions from EUV and laser ablation showed different spectra implying different geometries of plasma expansion. The calculation results of plasma parameters showed that EUV energy is mostly deposited in high electron density region close to the solid density, while laser energy is deposited in low energy density region. Plasma parameters experimentally obtained from visible spectra did not show noticeable difference between EUV and laser ablation due to the corresponding low cut off density.

  20. Linearly polarized photons from Compton backscattering of laser light for nuclear resonance fluorescence experiments

    NASA Astrophysics Data System (ADS)

    Ohgaki, H.; Noguchi, T.; Sugiyama, S.; Yamazaki, T.; Mikado, T.; Chiwaki, M.; Yamada, K.; Suzuki, R.; Sei, N.

    1994-12-01

    Elastically scattered photons from 208Pb(γ pol, γ) have been measured with completely polarized photons. The polarized photons (laser Compton photons) can be generated by Compton backscattering of laser light. The energy of the polarized LCPs ranges from 1 to 10 MeV by using a Q-switched Nd:YAG laser and the storage ring TERAS at Electrotechnical Laboratory. We can rotate the polarization axis of the LCPs by using the laser polarization controller to diminish the systematic error in the measurement system. Parities of J = 1 levels in 208Pb, Ex = 5.514 and 4.841 MeV, were clearly determined to be negative.

  1. Pretty Lights and Glowing Rocks: Using Lasers Pointers to Demonstrate Optical Phenomena

    NASA Astrophysics Data System (ADS)

    Huang, A.; Bodner, G.; Zheng, C.

    2011-12-01

    Green and violet lasers have recently become both inexpensive and portable, more than 70 years after the first laser was built. Despite the technology's age, the general public is still fascinated by the exotic nature of laser light. This activity uses green and violet laser pointers to produce a veritable rainbow of colors from household items and common minerals. Our objective is to create an educational experience which uses vivid colors and appealing effects to engage the audience, while teaching basic optical concepts such as scattering, fluorescence, Snell's law, and the quantum nature of light. The activity can be adapted to a lecture demonstration or to a laboratory exercise in which students handle the lasers and test samples. Learning outcomes have not been formally measured, but this demonstration will still captivate audiences in museum settings, community outreach programs, and introductory science courses.

  2. Investigation of the light field of a semiconductor diode laser.

    PubMed

    Ankudinov, A V; Yanul, M L; Slipchenko, S O; Shelaev, A V; Dorozhkin, P S; Podoskin, A A; Tarasov, I S

    2014-10-20

    Scanning near-field optical microscopy was applied to study, with sub-wavelength spatial resolution, the near- and the far-field distributions of propagating modes from a high-power laser diode. Simple modeling was also performed and compared with experimental results. The simulated distributions were consistent with the experiment and permitted clarification of the configuration of the transverse modes of the laser. PMID:25401675

  3. Laser action in chromium-activated forsterite for near-infrared excitation: Is Cr/sup 4 +/ the lasing ion

    SciTech Connect

    Petricevic, V.; Gayen, S.K.; Alfano, R.R.

    1988-12-26

    Room-temperature pulsed laser action has been obtained in chromium-activated forsterite (Cr:Mg/sub 2/SiO/sub 4/) for excitation of the near-infrared absorption band of the system by the 1064 nm radiation from a Nd:YAG laser. The characteristics of laser emission are similar to those observed for 532 nm pumping. It is suggested that the laser action is due to a ''center'' other than the trivalent chromium (Cr/sup 3 +/), presumably the tetravalent chromium (Cr/sup 4 +/).

  4. Demonstration of miniaturized 20mW CW 280nm and 266nm solid-state UV laser sources

    NASA Astrophysics Data System (ADS)

    Landru, Nicolas; Georges, Thierry; Beaurepaire, Julien; Le Guen, Bruno; Le Bail, Guy

    2015-02-01

    Visible 561 nm and 532 nm laser emissions from 14-mm long DPSS monolithic cavities are frequency converted to deep UV 280 nm and 266 nm in 16-mm long monolithic external cavities. Wavelength conversion is fully insensitive to mechanical vibrations and the whole UV laser sources fit in a miniaturized housing. More than 20 mW deep UV laser emission is demonstrated with high power stability, low noise and good beam quality. Aging tests are in progress but long lifetimes are expected thanks to the cavity design. Protein detection and deep UV resonant Raman spectroscopy are applications that could benefit from these laser sources.

  5. Pulsed-laser micropatterned quantum-dot array for white light source

    NASA Astrophysics Data System (ADS)

    Wang, Sheng-Wen; Lin, Huang-Yu; Lin, Chien-Chung; Kao, Tsung Sheng; Chen, Kuo-Ju; Han, Hau-Vei; Li, Jie-Ru; Lee, Po-Tsung; Chen, Huang-Ming; Hong, Ming-Hui; Kuo, Hao-Chung

    2016-03-01

    In this study, a novel photoluminescent quantum dots device with laser-processed microscale patterns has been demonstrated to be used as a white light emitting source. The pulsed laser ablation technique was employed to directly fabricate microscale square holes with nano-ripple structures onto the sapphire substrate of a flip-chip blue light-emitting diode, confining sprayed quantum dots into well-defined areas and eliminating the coffee ring effect. The electroluminescence characterizations showed that the white light emission from the developed photoluminescent quantum-dot light-emitting diode exhibits stable emission at different driving currents. With a flexibility of controlling the quantum dots proportions in the patterned square holes, our developed white-light emitting source not only can be employed in the display applications with color triangle enlarged by 47% compared with the NTSC standard, but also provide the great potential in future lighting industry with the correlated color temperature continuously changed in a wide range.

  6. High-coherence light extraction through a compact Brillouin/erbium fiber laser

    NASA Astrophysics Data System (ADS)

    Chen, Mo; Wang, Jianfei; Chen, Wei; Sun, Shilin; Meng, Zhou

    2016-05-01

    High-coherence light is stringently demanded in high-accuracy interferometric optical fiber sensors, where the phase noise of the light source greatly affects the sensitivity of the whole system. Distributed-feedback laser diodes with a phase noise of -80 ~ -90 dB/Hz1/2 at 1 kHz (with 1 m optical path difference) is now easily obtained, but the interferometric fiber sensors requires the laser source with the phase noise lower than -100 dB/Hz1/2. Lasers with ultra-low-noise usually require complicated and sophisticated techniques. We propose a novel structure to realize high-coherence light extraction through a compact Brillouin/erbium fiber laser (BEFL) which uses a length of 4 m erbium-doped fiber as both the Brillouin and linear gain media. The phase noise of the Brillouin pump light is greatly smoothed and suppressed after being transferred to the Brillouin Stokes light. High-coherence light with the phase noise of about -104 dB/Hz1/2 at 1 kHz is extracted through the compact BEFL from a commercialized laser diode with the phase noise of about -89 dB/Hz1/2. The capability of phase noise suppression in the compact BEFL presents much importance especially in large-array interferometric fiber sensor systems.

  7. REVIEWS OF TOPICAL PROBLEMS: Let there be white light: supercontinuum generation by ultrashort laser pulses

    NASA Astrophysics Data System (ADS)

    Zheltikov, Aleksei M.

    2006-06-01

    Three centuries after Newton's experiments on the decomposition of white light into its spectral components and the synthesis of white light from various colors, nonlinear-optical transformations of ultrashort laser pulses have made it possible to produce an artificial white light with unique spectral properties, controlled time duration, and a high spectral brightness. Owing to its broad and continuous spectrum, such radiation is called supercontinuum. The laser generation of white light is an interesting physical phenomenon and the relevant technology is gaining in practical implications — it offers novel solutions for optical communications and control of ultrashort laser pulses, helps to achieve an unprecedented precision in optical metrology, serves to probe the atmosphere of the Earth, and suggests new strategies for the creation of compact multiplex light sources for nonlinear spectroscopy, microscopy, and laser biomedicine. Here, we provide a review of physical mechanisms behind the laser generation of white light, examine its applications, and discuss the methods of generation of broadband radiation with controlled spectral, temporal, and phase parameters.

  8. Modeling of reflection-type laser-driven white lighting considering phosphor particles and surface topography.

    PubMed

    Lee, Dong-Ho; Joo, Jae-Young; Lee, Sun-Kyu

    2015-07-27

    This paper presents a model of blue laser diode (LD)-based white lighting coupled with a yellow YAG phosphor, for use in the proper design and fabrication of phosphor in automotive headlamps. First, the sample consisted of an LD, collecting lens, and phosphor was prepared that matches the model. The light distribution of the LD and the phosphor were modeled to investigate an effect of the surface topography and phosphor particle properties on the laser-driven white lighting systems by using the commercially available optical design software. Based on the proposed model, the integral spectrum distribution and the color coordinates were discussed. PMID:26367551

  9. Sub-100 nm gold nanoparticle vesicles as a drug delivery carrier enabling rapid drug release upon light irradiation.

    PubMed

    Niikura, Kenichi; Iyo, Naoki; Matsuo, Yasutaka; Mitomo, Hideyuki; Ijiro, Kuniharu

    2013-05-01

    Previously, we reported gold nanoparticles coated with semifluorinated ligands self-assembled into gold nanoparticle vesicles (AuNVs) with a sub-100 nm diameter in tetrahydrofuran (THF). (1) Although this size is potentially useful for in vivo use, the biomedical applications of AuNVs were limited, as the vesicular structure collapsed in water. In this paper, we demonstrate that the AuNVs can be dispersed in water by cross-linking each gold nanoparticle with thiol-terminated PEG so that the cross-linked vesicles can work as a drug delivery carrier enabling light-triggered release. Rhodamine dyes or anticancer drugs were encapsulated within the cross-linked vesicles by heating to 62.5 °C. At this temperature, the gaps between nanoparticles open, as confirmed by a blue shift in the plasmon peak and the more efficient encapsulation than that observed at room temperature. The cross-linked AuNVs released encapsulated drugs upon short-term laser irradiation (5 min, 532 nm) by again opening the nanogaps between each nanoparticle in the vesicle. On the contrary, when heating the solution to 70 °C, the release speed of encapsulated dyes was much lower (more than 2 h) than that triggered by laser irradiation, indicating that cross-linked AuNVs are highly responsive to light. The vesicles were efficiently internalized into cells compared to discrete gold nanoparticles and released anticancer drugs upon laser irradiation in cells. These results indicate that cross-linked AuNVs, sub-100 nm in size, could be a new type of light-responsive drug delivery carrier applicable to the biomedical field. PMID:23566248

  10. Coherence transfer of subhertz-linewidth laser light via an 82-km fiber link

    NASA Astrophysics Data System (ADS)

    Ma, Chaoqun; Wu, Lifei; Jiang, Yanyi; Yu, Hongfu; Bi, Zhiyi; Ma, Longsheng

    2015-12-01

    We demonstrate optical coherence transfer of subhertz-linewidth laser light through fiber links by actively compensating random fiber phase noise induced by environmental perturbations. The relative linewidth of laser light after transferring through a 32-km urban fiber link is suppressed within 1 mHz (resolution bandwidth limited), and the absolute linewidth of the transferred laser light is less than 0.36 Hz. For an 82-km fiber link, a repeater station is constructed between a 32-km urban fiber and a 50-km spooled fiber to recover the spectral purity. A relative linewidth of 1 mHz is also demonstrated for light transferring through the 82-km cascaded fiber. Such an optical signal distribution network based on repeater stations allows optical coherence and synchronization available over spatially separated places.

  11. Apparatus for injecting high power laser light into a fiber optic cable

    DOEpatents

    Sweatt, W.C.

    1997-11-11

    High intensity laser light is evenly injected into an optical fiber by the combination of a converging lens and a multisegment kinoform (binary optical element). The segments preferably have multi-order gratings on each which are aligned parallel to a radial line emanating from the center of the kinoform and pass through the center of the element. The grating in each segment causes circumferential (lateral) dispersion of the light, thereby avoiding detrimental concentration of light energy within the optical fiber. 6 figs.

  12. 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.

  13. Non-digitized diffractive beam splitters for high-throughput laser materials processing

    NASA Astrophysics Data System (ADS)

    Amako, J.; Fujii, E.

    2014-03-01

    We report a non-digitized diffractive beam splitter with a split count of 45, a 95% splitting efficiency, and a 0.90 splitting uniformity. The splitter was iteratively designed and was created on fused silica by laser writing lithography. Antireflection coatings were added to the splitter to ensure high efficiency. This splitter was applied to the manufacture of inkjet printer heads, in which silicon wafers were drilled with a 532-nm, nanosecond pulse laser with an average output of 10 W and were wet-etched to produce microfluidic channels. We also discuss large beam arrays for process throughput and subwavelength structures formed on the splitter for efficient laser power use.

  14. Radially and azimuthally polarized laser induced shape transformation of embedded metallic nanoparticles in glass.

    PubMed

    Tyrk, Mateusz A; Zolotovskaya, Svetlana A; Gillespie, W Allan; Abdolvand, Amin

    2015-09-01

    Radially and azimuthally polarized picosecond (~10 ps) pulsed laser irradiation at 532 nm wavelength led to the permanent reshaping of spherical silver nanoparticles (~30 - 40 nm in diameter) embedded in a thin layer of soda-lime glass. The observed peculiar shape modifications consist of a number of different orientations of nano-ellipsoids in the cross-section of each written line by laser. A Second Harmonic Generation cross-sectional scan method from silver nanoparticles in transmission geometry was adopted for characterization of the samples after laser modification. The presented approach may lead to sophisticated marking of information in metal-glass nanocomposites. PMID:26368440

  15. High precision laser induced etching of multilayered MoS{sub 2}

    SciTech Connect

    Ko, P. J.; Thu, T. V.; Takahashi, H.; Abderrahmane, A.; Takamura, T.; Sandhu, A.

    2014-02-20

    We demonstrate a method for reducing the thickness of multilayered MoS{sub 2} to few and single layers by irradiation with a 532 nm wavelength laser spot. The morphology and optical properites of the etched MoS{sub 2} were were measured by atomic force microscopy (AFM) and Raman spectroscopy before and after laser etching. Our laser etching method is a simple and highly effective tool for the fabrication of single, and few layered MoS{sub 2} for atomic scale optical and electronic device applications.

  16. Design, assembly, and testing of a high-resolution relay lens used for holography with operation at both doubled and tripled Nd:YAG laser wavelengths

    SciTech Connect

    Sorenson, Danny S; Pazuchanics, Peter D; Malone, Robert M; Cox, Brian C; Frogget, Brent C; Kaufman, Morris I; Capelle, Gene A

    2009-01-01

    The design and assembly of a nine-element lens that achieves >2000 1p/mm resolution at a 355-nm wavelength (ultraviolet) has been completed. By adding a doublet to this lens system, operation at a 532-nm wavelength (green) with > 1100 1p/mm resolution is achieved. This lens is used with high-power laser light to record holograms of fast-moving ejecta particles from a shocked metal surface located inside a test package. Part of the lens and the entire test package are under vacuum with a 1-cm air gap separation. Holograms have been recorded with both doubled and tripled Nd:YAG laser light. The UV operation is very sensitive to the package window's tilt. If this window is tilted by more than 0.1 degrees, the green operation performs with better resolution than that of the UV operation. The setup and alignment are performed with green light, but the dynamic recording can be done with either UV light or green light. A resolution plate can be temporarily placed inside the test package so that a television microscope located beyond the hologram position can archive images of resolution patterns that prove that the calibration wires., interference filter, holographic plate, and relay lenses are in their correct positions. Part of this lens is under vacuum, at the point where the laser illumination passes through a focus. Alignment and tolerancing of this high-resolution lens are presented. Resolution variation across the 12-mm field of view and throughout the 5-mm depth of field is discussed for both wavelengths.

  17. Design, Assembly, and Testing of a High-Resolution Relay Lens Used for Holography with Operation at Both Doubled and Tripled Nd:YAG Laser Wavelengths

    SciTech Connect

    Malone, Robert M; Cox, Brian C; Frogget, Brent C; Grover, Mike; Kaufman, Morris I; Pazuchanics, Peter; Sorenson, Danny S; Stevens, Gerald D; Tibbits, Aric; Turley, William D

    2009-08-21

    The design and assembly of a nine-element lens that achieves >2000 lp/mm resolution at a 355-nm wavelength (ultraviolet) has been completed. By adding a doublet to this lens system, operation at a 532-nm wavelength (green) with >1100 lp/mm resolution is achieved. This lens is used with high-power laser light to record holograms of fast-moving ejecta particles from a shocked metal surface located inside a test package. Part of the lens and the entire test package are under vacuum with a 1-cm air gap separation. Holograms have been recorded with both doubled and tripled Nd:YAG laser light. The UV operation is very sensitive to the package window’s tilt. If this window is tilted by more than 0.1 degrees, the green operation performs with better resolution than that of the UV operation. The setup and alignment are performed with green light, but the dynamic recording can be done with either UV light or green light. A resolution plate can be temporarily placed inside the test package so that a television microscope located beyond the hologram position can archive images of resolution patterns that prove that the calibration wires, interference filter, holographic plate, and relay lenses are in their correct positions. Part of this lens is under vacuum, at the point where the laser illumination passes through a focus. Alignment and tolerancing of this high-resolution lens are presented. Resolution variation across the 12-mm field of view and throughout the 5-mm depth of field is discussed for both wavelengths.

  18. Laser and Light Treatments for Striae Distensae: A Comprehensive Review of the Literature.

    PubMed

    Aldahan, Adam S; Shah, Vidhi V; Mlacker, Stephanie; Samarkandy, Sahal; Alsaidan, Mohammed; Nouri, Keyvan

    2016-06-01

    Striae distensae (SD) are common dermatologic lesions that often arise as a result of rapid weight change, certain endocrine conditions, or prolonged exposure to steroids. SD initially present as raised edematous plaques (striae rubra), after which they become white and atrophic (striae alba) owing to local breakdown and reorganization of collagen and elastin. There currently exists no reliable treatment option, though numerous topical applications have been attempted. Lasers and light represent emerging noninvasive therapies that have demonstrated some success targeting vascular chromophores in striae rubra and stimulating collagen and elastin production in striae alba. An extensive literature review was performed to gather all available articles studying laser and light treatments for SD. Lasers and light can significantly improve the appearance of both striae rubra and striae alba. Generally, striae rubra are more responsive to therapy and can be treated successfully with a variety of lasers without major adverse effects. Fractional lasers exhibit the strongest results for striae alba repigmentation and collagen induction, and several other lasers produce temporary repigmentation. Lasers in combination with other modalities such as topical agents and additional energy devices have also demonstrated promising preliminary results; however, large comparative studies are necessary to validate these outcomes. PMID:26923916

  19. Single-mode and tunable microfluidic dye lasers

    NASA Astrophysics Data System (ADS)

    Kristensen, A.; Balslev, S.; Gersborg-Hansen, M.; Bilenberg, B.; Rasmussen, T.; Nilsson, D.

    2006-08-01

    We present a technology for miniaturized, chip-based liquid dye lasers, which may be integrated with microfluidic networks and planar waveguides without addition of further process steps. The microfluidic dye lasers consist of a microfluidic channel with an embedded optical resonator. The lasers are operated with Rhodamine 6G laser dye dissolved in a suitable solvent, such as ethanol or ethylene glycol, and optically pumped at 532 nm with a pulsed, frequency doubled Nd:YAG laser. Both vertically and laterally emitting devices are realized. A vertically emitting Fabry-Perot microcavity laser is integrated with a microfluidic mixer, to demonstrate realtime wavelength tunability. Two major challenges of this technology are addressed: lasing threshold and fluidic handling. Low threshold, in-plane emission and integration with polymer waveguides and microfluidic networks is demonstrated with distributed feed-back lasers. The challenge of fluidic handling is addressed by hybridization with mini-dispensers, and by applying capillary filling of the laser devices.

  20. Influence of wavelength on laser doping and laser-fired contact processes for c-Si solar cells

    NASA Astrophysics Data System (ADS)

    Molpeceres, Carlos; Sánchez-Aniorte, María. Isabel; Morales, Miguel; Muñoz, David; Martín, Isidro; Ortega, Pablo; Colina, Mónica; Voz, Cristóbal; Alcubilla, Ramón

    2012-10-01

    This work investigates the influence of the laser wavelength on laser doping (LD) and laser-fired contact (LFC) formation in solar cell structures. We compare the results obtained using the three first harmonics (corresponding to wavelengths of 1064 nm, 532 nm and 355 nm) of fully commercial solid state laser sources with pulse width in the ns range. The discussion is based on the impact on the morphology and electrical characteristics of test structures. In the case of LFC the study includes the influence of different passivation layers and the assessment of the process quality through electrical resistance measurements of an aluminium single LFC point for the different wavelengths. Values for the normalized LFC resistance far below 1.0 mΩcm2 have been obtained, with better results at shorter wavelengths. To assess the influence of the laser wavelength on LD we have created n+ regions into p-type c-Si wafers, using a dry LD approach to define punctual emitters. J-V characteristics show exponential trends at mid-injection for a broad parametric window in all wavelengths, with local ideality factors well below 1.5. In both processes the best results have been obtained using green (532 nm) and, specially, UV (355 nm). This indicates that to minimize the thermal damage in the material is a clear requisite to obtain the best electrical performance, thus indicating that UV laser shows better potential to be used in high efficiency solar cells.

  1. CO2 laser-fabricated cladding light strippers for high-power fiber lasers and amplifiers.

    PubMed

    Boyd, Keiron; Simakov, Nikita; Hemming, Alexander; Daniel, Jae; Swain, Robert; Mies, Eric; Rees, Simon; Andrew Clarkson, W; Haub, John

    2016-04-10

    We present and characterize a simple CO2 laser processing technique for the fabrication of compact all-glass optical fiber cladding light strippers. We investigate the cladding light loss as a function of radiation angle of incidence and demonstrate devices in a 400 μm diameter fiber with cladding losses of greater than 20 dB for a 7 cm device length. The core losses are also measured giving a loss of <0.008±0.006  dB/cm. Finally we demonstrate the successful cladding light stripping of a 300 W laser diode with minimal heating of the fiber coating and packaging adhesives. PMID:27139854

  2. Magnetooptical Faraday and Light-Scattering Diagnostics of Laser Plasma in Leopard Laser Facility at UNR/NTF

    NASA Astrophysics Data System (ADS)

    Sarkisov, G. S.; Yates, K.; Ivanov, V. V.; Sotnikov, V. I.; Yasin, E.; Wiewior, P.; Astanovitsky, A.; Chaly, O.; Kindel, J.

    2009-11-01

    Laser plasma of the solid target on Leopard Laser Facility at University of Nevada Reno was investigated using polarimetry, interferometry and laser-scattering diagnostics. 50 TW Nd:glass Leopard laser operates on 1056 nm wavelength, 10 J energy and 1ns/400 fs pulse width. Power flux on a target surface varied from 10^14 to 10^19W/cm^2 with 20 μm focus spot from off-axis parabola. The diagnostic of spontaneous magnetic fields in laser plasma was carried out using three-channel polarinterferometer with Faraday, shadow and interferogram channels. Ultrafast two-frame shadowgrams/interferograms with two probing beams with orthogonal polarizations were used for investigation of fast moving plasma phenomena (jets, ionization front propagation). Continuous 1W green DPSS-laser with external modulation was used for light scattering experiments for investigation of the late-time micro-particles generation in laser plasma with expected large charge number of the grain Z ˜ 100-1000.

  3. Light intensity independence during dynamic laser speckle analysis

    NASA Astrophysics Data System (ADS)

    Reis, Renan Oliveira; Rabal, Hector J.; Braga, Roberto A.

    2016-05-01

    We explore some different normalizations of current dynamic laser speckle activity measures searching for their performance with respect to the illumination inhomogeneity of the samples. Inertia Moment and Average Value of Differences of the co-occurrence matrix are compared using a paint-drying case study on a uniform sample where attenuation in a portion of the illuminated area is introduced using a neutral density filter. In this way, all environmental conditions being equal but non-uniform illumination permits the comparison on a better approximation to objectivity. The results presented show that it is possible to mitigate the effects of the illumination in the activities measured by the dynamic laser speckle.

  4. Indication of Local Laser Pump Depletion via Transmitted Self-Guided Laser Light

    SciTech Connect

    Pak, A. E.; Marsh, K. A.; Ralph, J. E.; Lu, W.; Clayton, C. E.; Joshi, C.

    2009-01-22

    In recent experiments it has been shown that an ultra-intense, ultra-short laser pulse can be self-guided over tens of Rayleigh lengths in an underdense plasma where {tau}(FWHM of the laser pulse) is on the order of the plasma wavelength ({lambda}{sub p}). Using an imaging spectrograph, the frequency of the transmitted laser pulse was spatially and spectrally resolved at the exit of 3, 5, and 8 mm long plasmas. The mechanism of laser pump depletion was studied by observing the amount that the transmitted laser pulse's spectrum was red shifted in wavelength through the interaction with the self-guiding plasma wave.

  5. Texturing of polypropylene (PP) with nanosecond lasers

    NASA Astrophysics Data System (ADS)

    Riveiro, A.; Soto, R.; del Val, J.; Comesaña, R.; Boutinguiza, M.; Quintero, F.; Lusquiños, F.; Pou, J.

    2016-06-01

    Polypropylene (PP) is a biocompatible and biostable polymer, showing good mechanical properties that has been recently introduced in the biomedical field for bone repairing applications; however, its poor surface properties due to its low surface energy limit their use in biomedical applications. In this work, we have studied the topographical modification of polypropylene (PP) laser textured with Nd:YVO4 nanosecond lasers emitting at λ = 1064 nm, 532 nm, and 355 nm. First, optical response of this material under these laser wavelengths was determined. The application of an absorbing coating was also studied. The influence of the laser processing parameters on the surface modification of PP was investigated by means of statistically designed experiments. Processing maps to tailor the roughness, and wettability, the main parameters affecting cell adhesion characteristics of implants, were also determined. Microhardness measurements were performed to discern the impact of laser treatment on the final mechanical properties of PP.

  6. Vacuum-Compatible Wideband White Light and Laser Combiner Source System

    NASA Technical Reports Server (NTRS)

    Azizi, Alineza; Ryan, Daniel J.; Tang, Hong; Demers, Richard T.; Kadogawa, Hiroshi; An, Xin; Sun, George Y.

    2010-01-01

    For the Space Interferometry Mission (SIM) Spectrum Calibration Development Unit (SCDU) testbed, wideband white light is used to simulate starlight. The white light source mount requires extremely stable pointing accuracy (<3.2 microradians). To meet this and other needs, the laser light from a single-mode fiber was combined, through a beam splitter window with special coating from broadband wavelengths, with light from multimode fiber. Both lights were coupled to a photonic crystal fiber (PCF). In many optical systems, simulating a point star with broadband spectrum with stability of microradians for white light interferometry is a challenge. In this case, the cameras use the white light interference to balance two optical paths, and to maintain close tracking. In order to coarse align the optical paths, a laser light is sent into the system to allow tracking of fringes because a narrow band laser has a great range of interference. The design requirements forced the innovators to use a new type of optical fiber, and to take a large amount of care in aligning the input sources. The testbed required better than 1% throughput, or enough output power on the lowest spectrum to be detectable by the CCD camera (6 nW at camera). The system needed to be vacuum-compatible and to have the capability for combining a visible laser light at any time for calibration purposes. The red laser is a commercially produced 635-nm laser 5-mW diode, and the white light source is a commercially produced tungsten halogen lamp that gives a broad spectrum of about 525 to 800 nm full width at half maximum (FWHM), with about 1.4 mW of power at 630 nm. A custom-made beam splitter window with special coating for broadband wavelengths is used with the white light input via a 50-mm multi-mode fiber. The large mode area PCF is an LMA-8 made by Crystal Fibre (core diameter of 8.5 mm, mode field diameter of 6 mm, and numerical aperture at 625 nm of 0.083). Any science interferometer that needs a

  7. Laser produced plasma for efficient extreme ultraviolet light sources

    SciTech Connect

    Donnelly, Tony; Cummins, Thomas; O' Gorman, Colm; Li Bowen; Harte, Colm S.; O'Reilly, Fergal; Sokell, Emma; Dunne, Padraig; O'Sullivan, Gerry

    2012-05-25

    Extreme ultraviolet emission from laser produced plasma and their relevance to EUV source development is discussed. The current state of the field for Sn LPP sources operating at 13.5 nm is described and initial results are given for EUV emission from CO{sub 2} laser irradiation of a bulk Sn target. A maximum conversion efficiency of 1.7% has been measured and the influence of the CO{sub 2} laser temporal profile on the CE is discussed. A double pulse irradiation scheme is shown to increase CE up to a maximum value of 2.1% for an optimum prepulse - pulse delay of 150 ns. The emergence of a new EUVL source wavelength at 6.7 nm based on Gd and Tb LPPs has been outlined. An initial experiment investigating picosecond laser irradiation as a means to produce strong 6.7 nm emission from a Gd{sub 2}O{sub 3} target has been performed and verified.

  8. Laser photothermal spectroscopy of light-induced absorption

    SciTech Connect

    Skvortsov, L A

    2013-01-31

    Basic methods of laser photothermal spectroscopy, which are used to study photoinduced absorption in various media, are briefly considered. Comparative analysis of these methods is performed and the latest results obtained in this field are discussed. Different schemes and examples of their practical implementation are considered. (review)

  9. 20,000 Photons Under the Snow: Subsurface Scattering of Visible Laser Light and the Implications for Laser Altimeters

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Existing visible light laser altimeters such as ATM (Airborne Topographical Mapper) with NASA's Operation IceBridge and NASA's MABEL (Multiple Altimeter Beam Experimental Lidar; a simulator for NASA's ICESat-2 mission) are providing scientists with a view of Earth's ice sheets, glaciers, and sea ice with unprecedented detail. Measuring how these surfaces evolve in the face of a rapidly changing climate requires the utmost attention to detail in the design and calibration of these instruments, as well as understanding the changing optical properties of these surfaces. As single photon counting lidars, MABEL and NASA's ATLAS (Advanced Topographic Laser Altimeter System) on the upcoming ICESat-2 mission provide fundamentally different information compared with waveform lidars such as ATM, or GLAS (Geoscience Laser Altimeter System) on NASA's previous ICESat-1 mission. By recording the travel times of individual photons, more detailed information about the surface, and potentially the subsurface, are available and must be considered in elevation retrievals from the observed photon cloud. Here, we investigate possible sources of uncertainty associated with monochromatic visible light scattering in subsurface snow, which may affect the precision and accuracy of elevation estimates. We also explore the capacity to estimate snow grain size in near surface snow using experimental visible light laser data obtained in laboratory experiments.

  10. Note: Laser beam scanning using a ferroelectric liquid crystal spatial light modulator

    SciTech Connect

    Das, Abhijit; Boruah, Bosanta R.

    2014-04-15

    In this work we describe laser beam scanning using a ferroelectric liquid crystal spatial light modulator. Commercially available ferroelectric liquid crystal spatial light modulators are capable of displaying 85 colored images in 1 s using a time dithering technique. Each colored image, in fact, comprises 24 single bit (black and white) images displayed sequentially. We have used each single bit image to write a binary phase hologram. For a collimated laser beam incident on the hologram, one of the diffracted beams can be made to travel along a user defined direction. We have constructed a beam scanner employing the above arrangement and demonstrated its use to scan a single laser beam in a laser scanning optical sectioning microscope setup.

  11. Efficient plant growth using automatic position-feedback laser light irradiation

    NASA Astrophysics Data System (ADS)

    Kakinoki, Yoshiaki; Kato, Yuya; Ogawa, Kosuke; Nakao, Akira; Okai, Zenshiro; Katsuyama, Toshio

    2013-05-01

    The plant growth based on the scanning laser beam is newly developed. Three semiconductor lasers with three primary colors, i.e., blue, green and red are used. Here, the laser scanned position is restricted only to the plant leaves, where the light illumination is needed. The feedback system based on the perspective projection is developed. The system consists of the automatic position correction from the camera image. The automatic image extraction of the leaf parts is also introduced. The electric power needed for this system is as small as 6.25% compared with the traditional white fluorescent lamp. Furthermore, experimental results show that the red-color laser light is particularly efficient for the growth of the radish sprouts.

  12. Frequency chirped light at large detuning with an injection-locked diode laser

    SciTech Connect

    Teng, K.; Disla, M.; Dellatto, J.; Limani, A.; Kaufman, B.; Wright, M. J.

    2015-04-15

    We have developed a laser system to generate frequency-chirped light at rapid modulation speeds (∼100 MHz) with a large frequency offset. Light from an external cavity diode laser with its frequency locked to an atomic resonance is passed through a lithium niobate electro-optical phase modulator. The phase modulator is driven by a ∼6 GHz signal whose frequency is itself modulated with a RF MHz signal (<200 MHz). A second injection locked diode laser is used to filter out all of the light except the frequency-chirped ±1 order by more than 30 dB. Using this system, it is possible to generate a 1 GHz frequency chirp in 5 ns.

  13. Mid IR pulsed light source for laser ultrasonic testing of carbon-fiber-reinforced plastic

    NASA Astrophysics Data System (ADS)

    Hatano, H.; Watanabe, M.; Kitamura, K.; Naito, M.; Yamawaki, H.; Slater, R.

    2015-09-01

    A quasi-phase-matched (QPM) optical parametric oscillator (OPO) was developed using a periodically poled Mg-doped stoichiometric LiTaO3 crystal to generate mid-IR light for excitation of laser ultrasound in carbon fiber reinforced plastic (CFRP). The ultrasound generation efficiency was measured at the three different wavelengths that emanate from the OPO: 1.064 μm, 1.59/1.57 μm, and 3.23/3.30 μm. The measurements indicate that mid-IR 3.2-3.3 μm light generates the most efficient ultrasonic waves in CFRP with the least laser damage. We used mid-IR light in conjunction with a laser interferometer to demonstrate the detection of flaws/defects in CFRP such as the existence of air gaps that mimic delamination and voids in CFRP, and the inhomogeneous adhesion of CFRP material to a metal plate was also clearly detected.

  14. Optical measurement of temperature in biological cells under infrared laser light exposure (λ=800 nm)

    NASA Astrophysics Data System (ADS)

    Moreau, David; Lefort, Claire; Leveque, Philippe; O'Connor, Rod P.

    2015-07-01

    Interest in the interaction between laser light and biological samples has gained momentum in recent years, particularly in neurobiology, where there is significant potential to stimulate neurons with infrared laser light. Despite recent reports showing the application of infrared light for neurostimulation, the underlying mechanism is still unknown. The two main hypotheses are based on thermal or electrostatic mechanisms. Here, a novel optical method is presented to make temperature measurements in human neural cells under infrared laser excitation (λ=800nm) using the dye Rhodamine B (RhB). The measurement of temperature is based on the property of RhB, a fluorescent dye whose fluorescence intensity decreases linearly with increases in temperature. We present and detail the setup and measurement procedure that has temporal resolution of few milliseconds, based around a fluorescent live-cell imaging microscope used for cellular microfluorimetry experiments.

  15. Comparison of laser and intense pulsed light sintering (IPL) for inkjet-printed copper nanoparticle layers

    NASA Astrophysics Data System (ADS)

    Niittynen, Juha; Sowade, Enrico; Kang, Hyunkyoo; Baumann, Reinhard R.; Mäntysalo, Matti

    2015-03-01

    In this contribution we discuss the sintering of an inkjet-printed copper nanoparticle ink based on electrical performance and microstructure analysis. Laser and intense pulsed light (IPL) sintering are employed in order to compare the different techniques and their feasibility for electronics manufacturing. A conductivity of more than 20% of that of bulk copper material has been obtained with both sintering methods. Laser and IPL sintering techniques are considered to be complementary techniques and are highly suitable in different application fields.

  16. Laser-ablation-induced refractive index fields studied using pulsed digital holographic interferometry

    NASA Astrophysics Data System (ADS)

    Amer, Eynas; Gren, Per; Sjödahl, Mikael

    2009-07-01

    Pulsed digital holographic interferometry has been used to investigate the plume and the shock wave generated in the ablation process of a Q-switched Nd-YAG ( λ=1064 nm and pulse duration=12 ns) laser pulse on a polycrystalline boron nitride (PCBN) target under atmospheric air pressure. A special setup based on two synchronised wavelengths from the same laser for simultaneous processing and measurement has been used. Digital holograms were recorded for different time delays using collimated laser light ( λ=532 nm) passed through the volume along the target. Numerical data of the integrated refractive index field were calculated and presented as phase maps showing the propagation of the shock wave and the plume generated by the process. Radon inversion has been used to estimate the 3D refractive index fields measured from the projections assuming rotational symmetry. The shock wave density has been calculated using the point explosion model and the shock wave condition equation and its behaviour with time at different power densities ranging from 1.4 to 9.1 GW/cm 2 is presented. Shock front densities have been calculated from the reconstructed refractive index fields using the Gladstone-Dale equation. A comparison of the shock front density calculated from the reconstructed data and that calculated using the point explosion model at different time delays has been done. The comparison shows quite good agreement between the model and the experimental data. Finally the reconstructed refractive index field has been used to estimate the electron number density distribution within the laser-induced plasma. The electron number density behaviour with distance from the target at different power densities and its behaviour with time are shown. The electron number densities are found to be in the order of 10 18 cm -3 and decay at a rate of 3×10 15 electrons/cm 3 ns.

  17. Light Trapping for Thin Silicon Solar Cells by Femtosecond Laser Texturing: Preprint

    SciTech Connect

    Lee, B. G.; Lin, Y. T.; Sher, M. J.; Mazur, E.; Branz, H. M.

    2012-06-01

    Femtosecond laser texturing is used to create nano- to micron-scale surface roughness that strongly enhances light-trapping in thin crystalline silicon solar cells. Light trapping is crucial for thin solar cells where a single light-pass through the absorber is insufficient to capture the weakly absorbed red and near-infrared photons, especially with an indirect-gap semiconductor absorber layer such as crystalline Si which is less than 20 um thick. We achieve enhancement of the optical absorption from light-trapping that approaches the Yablonovitch limit.

  18. Diode laser for endodontic treatment: investigations of light distribution and disinfection efficiency

    NASA Astrophysics Data System (ADS)

    Stock, Karl; Graser, Rainer; Udart, Martin; Kienle, Alwin; Hibst, Raimund

    2011-03-01

    Diode lasers are used in dentistry mainly for oral surgery and disinfection of root canals in endodontic treatment. The purpose of this study was to investigate and to improve the laser induced bacteria inactivation in endodontic treatment. An essential prerequisite of the optimization of the irradiation process and device is the knowledge about the determinative factors of bacteria killing: light intensity? light dosis? temperature? In order to find out whether high power NIR laser bacterial killing is caused by a photochemical or a photothermal process we heated bacteria suspensions of E. coli K12 by a water bath and by a diode laser (940 nm) with the same temporal temperature course. Furthermore, bacteria suspensions were irradiated while the temperature was fixed by ice water. Killing of bacteria was measured via fluorescence labeling. In order to optimize the irradiation of the root canal, we designed special fiber tips with radial light emission characteristic by optical ray tracing simulations. Also, we calculated the resulting light distribution in dentin by voxelbased Monte Carlo simulations. Furthermore, we irradiated root canals of extracted human teeth using different fiber tip geometries and measured the resulting light and heat distribution by CCD-camera and thermography. Comparison of killing rates between laser and water based heating shows no significant differences, and irradiation of ice cooled suspensions has no substantial killing effect. Thus, the most important parameter for bacterial killing is the maximum temperature. Irradiation of root canals using fiber tips with radial light emission results in a more defined irradiated area with minor irradiation of the apex and higher intensity and therefore higher temperature increase on root canal surface. In conclusion, our experiments show that at least for E. coli bacteria inactivation by NIR laser irradiation is solely based on a thermal process and that heat distribution in root canal can be

  19. In vivo studies of low level laser (light) therapy for traumatic brain injury

    NASA Astrophysics Data System (ADS)

    Xuan, Weijun; Wu, Qiuhe; Huang, Ying-Ying; Ando, Takahiro; Huang, Liyi; Hamblin, Michael R.

    2012-03-01

    Low-level laser (or light) therapy (LLLT) is attracting growing interest to treat both stroke and traumatic brain injury (TBI). The fact that near-infrared light can penetrate into the brain allows non-invasive treatment to be carried out with a low likelihood of treatment-related adverse events. It is proposed that red and NIR light is absorbed by chromophores in the mitochondria of cells leading to changes in gene transcription and upregulation of proteins involved in cell survival, antioxidant production, collagen synthesis, reduction of chronic inflammation and cell migration and proliferation. We developed a mouse model of controlled cortical impact (CCI) TBI and examined the effect of 0, 1, 3, and 14 daily 810-nm CW laser treatments in the CCI model as measured by neurological severity score and wire grip and motion test. 1 laser Tx gave a significant improvement while 3 laser Tx was even better. Surprisingly 14 laser Tx was no better than no treatment. Histological studies at necropsy suggested that the neurodegeneration was reduced at 14 days and that the cortical lesion was repaired by BrdU+ve neural progenitor (stem) cells at 28 days. Transcranial laser therapy is a promising treatment for acute (and chronic TBI) and the lack of side-effects and paucity of alternative treatments encourages early clinical trials.

  20. Remote Continuous Wave and Pulsed Laser Raman Detection of Chemical Warfare Agents Simulants and Toxic Industrial Compounds

    NASA Astrophysics Data System (ADS)

    Ortiz-Rivera, William; Pacheco-Londoño, Leonardo C.; Hernández-Rivera, Samuel P.

    2010-09-01

    This study describes the design, assembly, testing and comparison of two Remote Raman Spectroscopy (RRS) systems intended for standoff detection of hazardous chemical liquids. Raman spectra of Chemical Warfare Agents Simulants (CWAS) and Toxic Industrial Compounds (TIC) were measured in the laboratory at a 6.6 m source-target distance using continuous wave (CW) laser detection. Standoff distances for pulsed measurements were 35 m for dimethyl methylphosphonate (DMMP) detection and 60, 90 and 140 m for cyclohexane detection. The prototype systems consisted of a Raman spectrometer equipped with a CCD detector (for CW measurements) and an I-CCD camera with time-gated electronics (for pulsed laser measurements), a reflecting telescope, a fiber optic assembly, a single-line CW laser source (514.5, 488.0, 351.1 and 363.8 nm) and a frequency-doubled single frequency Nd:YAG 532 nm laser (5 ns pulses at 10 Hz). The telescope was coupled to the spectrograph using an optical fiber, and filters were used to reject laser radiation and Rayleigh scattering. Two quartz convex lenses were used to collimate the light from the telescope from which the telescope-focusing eyepiece was removed, and direct it to the fiber optic assembly. To test the standoff sensing system, the Raman Telescope was used in the detection of liquid TIC: benzene, chlorobenzene, toluene, carbon tetrachloride, cyclohexane and carbon disulfide. Other compounds studied were CWAS: dimethylmethyl phosphonate, 2-chloroethyl ethyl sulfide and 2-(butylamino)-ethanethiol. Relative Raman scattering cross sections of liquid CWAS were measured using single-line sources at 532.0, 488.0, 363.8 and 351.1 nm. Samples were placed in glass and quartz vials at the standoff distances from the telescope for the Remote Raman measurements. The mass of DMMP present in water solutions was also quantified as part of the system performance tests.