Application of a pulsed laser for measurements of bathymetry and algal fluorescence.

NASA Technical Reports Server (NTRS)

Hickman, G. D.; Hogg, J. E.; Friedman, E. J.; Ghovanlou, A. H.

1973-01-01

The technique of measuring water depths with an airborne pulsed dye laser is studied, with emphasis on the degrading effect of some environmental and operational parameters on the transmitted and reflected laser signals. Extrapolation of measurements of laser stimulated fluorescence, performed as a function of both the algal cell concentration and the distance between the algae and the laser/receiver, indicate that a laser system operating from a height of 500 m should be capable of detecting chlorophyll concentrations as low as 1.0 mg/cu m.-

Characteristics of a broadband dye laser using Pyrromethene and Rhodamine dyes.

PubMed

Tedder, Sarah A; Wheeler, Jeffrey L; Danehy, Paul M

2011-02-20

A broadband dye laser pumped by a frequency-doubled Nd:YAG laser with a full width at half-maximum from 592 to 610 nm was created for the use in a dual-pump broadband coherent anti-Stokes Raman spectroscopy (CARS) system called width increased dual-pump enhanced CARS (WIDECARS). The desired broadband dye laser was generated with a mixture of Pyrromethene dyes as an oscillator gain medium and a spectral selective optic in the oscillator cavity. A mixture of Rhodamine dyes was used in the amplifier dye cell. To create this laser, a study was performed to characterize the spectral behavior of broadband dye lasers created with Rhodamine dyes 590, 610, and 640 and Pyrromethene dyes 597 and 650, as well as mixtures of these dyes.

Dye lasing arrangement including an optical assembly for altering the cross-section of its pumping beam and method

DOEpatents

O'Neil, Richard W.; Sweatt, William C.

1992-01-01

An optical assembly is disclosed herein along with a method of operation for use in a dye lasing arrangement, for example a dye laser oscillator or a dye amplifier, in which a continuous stream of dye is caused to flow through a given zone in a cooperating dye chamber while the zone is being illuminated by light from a pumping beam which is directed into the given zone. This in turn causes the dye therein to lase and thereby produce a new dye beam in the case of a dye laser oscillator or amplify a dye beam in the case of a dye amplifier. The optical assembly so disclosed is designed to alter the pump beam such that the beam enters the dye chamber with a different cross-sectional configuration, preferably one having a more uniform intensity profile, than its initially produced cross-sectional configuration. To this end, the assembly includes a network of optical components which first act on the beam while the latter retains its initially produced cross-sectional configuration for separating it into a plurality of predetermined segments and then recombines the separated components in a predetermined way which causes the recombined beam to have the different cross-sectional configuration.

Continuous-wave operation of a room-temperature, diode-laser-pumped, 946-nm Nd:YAG laser

NASA Technical Reports Server (NTRS)

Fan, T. Y.; Byer, Robert L.

1987-01-01

Single-stripe diode-laser-pumped operation of a continuous-wave 946-nm Nd:YAG laser with less than 10-mW threshold has been demonstrated. A slope efficiency of 16 percent near threshold was shown with a projected slope efficiency well above a threshold of 34 percent based on results under Rhodamine 6G dye-laser pumping. Nonlinear crystals for second-harmonic generation of this source were evaluated. KNbO3 and periodically poled LiNbO3 appear to be the most promising.

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

PubMed

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

2015-08-10

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

Development of New Laser Protective Dyes. Phase 2.

DTIC Science & Technology

DYE LASERS, PROTECTION, LASERS, DYES , HAZARDS, SYNTHESIS, EYE SAFETY, OPTICAL MATERIALS, PLASTICS, LENSES, THERMAL STABILITY, CYANINE DYES , POLYCARBONATES, INJECTION MOLDING, NEAR INFRARED RADIATION, FLUORENES.

Random lasing action in a polydimethylsiloxane wrinkle induced disordered structure

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

Shen, Zhenhua; Wu, Leilei; Zhu, Shu

This paper presents a chip-scale random lasing action utilizing polydimethylsiloxane (PDMS) wrinkles with random periods as disordered medium. Nanoscale wrinkles with long range disorder structures are formed on the oxidized surface of a PDMS slab and confirmed by atomic force microscopy. Light multiply scattered at each PDMS wrinkle-dye interfaces is optically amplified in the presence of pump gain. The shift of laser emission wavelength when pumping at different regions indicates the randomness of the winkle period. In addition, a relatively low threshold of about 27 μJ/mm{sup 2} is realized, which is comparable with traditional optofluidic dye laser. This is due tomore » the unique sinusoidal Bragg-grating-like random structure. Contrast to conventional microfluidic dye laser that inevitably requires the accurate design and implementation of microcavity to provide optical feedback, the convenience in both fabrication and operation makes PDMS wrinkle based random laser a promising underlying element in lab-on-a-chip systems and integrated microfluidic networks.« less

Spectroscopy and laser action of the "red perylimide dye" in various solvents

NASA Astrophysics Data System (ADS)

Gvishi, R.; Reisfeld, R.; Burshtein, Z.

1993-10-01

Optical properties of the red perylimide laser dye in various solvents are studied. The absorption spectrum exhibits two main bands, in the ranges 480-600 and 400-460 nm, due to the S 0-S 1 and S 0-S 2 transition. The fluorescence spectrum is a mirror image of the S 0-S 1 absorption (shift of ˜ 30-50 nm). The Stokes shift increases with solvent polarity. Such dye-solvent interactions are compared to theoretical predictions. The fluorescence quantum yields approaches unity in all the solvents studied. Laser tunability around 30 nm was obtained each time, covering the spectral range 580-640 nm. This interval is important for medical applications in photodynamic therapy and fluorescence diagnostics. The laser threshold energy varied from 0.35 mJ/pulse in cyclohexane to 1.87 mJ/pulse in methanol, and the slope efficiency from about 6.6% in methanol to 14% in xylenes. The laser output was stable for several hours of operation under an average pump energy of about 20 mJ/pulse at 1 Hz repetition rate, without flow.

Estimation of ground and excited state dipole moment of laser dyes C504T and C521T using solvatochromic shifts of absorption and fluorescence spectra.

PubMed

Basavaraja, Jana; Suresh Kumar, H M; Inamdar, S R; Wari, M N

2016-02-05

The absorption and fluorescence spectra of laser dyes: coumarin 504T (C504T) and coumarin 521T (C521T) have been recorded at room temperature in a series of non-polar and polar solvents. The spectra of these dyes showed bathochromic shift with increasing in solvent polarity indicating the involvement of π→π⁎ transition. Kamlet-Taft and Catalan solvent parameters were used to analyze the effect of solvents on C504T and C521T molecules. The study reveals that both general solute-solvent interactions and specific interactions are operative in these two systems. The ground state dipole moment was estimated using Guggenheim's method and also by quantum mechanical calculations. The solvatochromic data were used to determine the excited state dipole moment (μ(e)). It is observed that dipole moment value of excited state (μ(e)) is higher than that of the ground state in both the laser dyes indicating that these dyes are more polar in nature in the excited state than in the ground state. Copyright © 2015. Published by Elsevier B.V.

On the possibility of measuring atmospheric OH using intracavity laser spectroscopy

NASA Technical Reports Server (NTRS)

Mcmanus, J. Barry; Kolb, C. E.

1994-01-01

Intracavity laser spectroscopy (ILS) has been demonstrated to be useful for measuring extremely weak absorption produced by gases in air. ILS is based on the observation that when there are spectrally narrow losses within the cavity of a broadband laser, the laser output has corresponding spectral holes where the laser oscillation is partially quenched. The depth of the laser output dips can be enhanced by a factor of 10(exp 5) over the depth of the initial cavity loss, and absorptivities of 10(exp -8) cm(exp -1) have been measured in lasers only one meter long. With ILS, one can achieve in a compact space a spectral contrast that would otherwise require kilometers of pathlength. ILS systems typically use quasi-continuous wave dye lasers operating close to threshold. The pump laser is modulated from just below to just above the threshold level for the dye laser, and the dye laser output is spectroscopically observed during a well defined time interval after the onset of lasing (the generation time). The spectral contrast of an intracavity absorber is equivalent to that produced by absorption through a path length equal to the generation time multiplied by the speed of light (assuming the cavity is completely filed with the absorber) up to some limiting time. Thus, if one measures the spectrum after 33 microseconds, the effective path length is 10,000 meters.

Single mode pulsed dye laser oscillator

DOEpatents

Hackel, Richard P.

1992-01-01

A single mode pulsed dye laser oscillator is disclosed. The dye laser oscillator provides for improved power efficiency by reducing the physical dimensions of the overall laser cavity, which improves frequency selection capability.

Two Wavelength Ti:sapphire Laser for Ozone DIAL Measurements from Aircraft

NASA Technical Reports Server (NTRS)

Situ, Wen; DeYoung, Russel J.

1998-01-01

Laser remote sensing of ozone from aircraft has proven to be a valuable technique for understanding the distribution and dynamics of ozone in the atmosphere. Presently the differential absorption lidar (DIAL) technique, using dual ND:YAG lasers that are doubled to pump dye lasers which in turn are doubled into the UV for the "on" and "off' line lasers, is used on either the NASA DC-8 or P-3 aircraft. Typically, the laser output for each line is 40-mJ and this is split into two beams, one looking up and the other downward, each beam having about 20-mJ. The residual ND:YAG (1.06 micron) and dye laser energies are also transmitted to obtain information on the atmospheric aerosols. While this system has operated well, there are several system characteristics that make the system less than ideal for aircraft operations. The system, which uses separate "on" and "off" line lasers, is quite large and massive requiring valuable aircraft volume and weight. The dye slowly degrades with time requiring replacement. The laser complexity requires a number of technical people to maintain the system performance. There is also the future interest in deploying an ozone DIAL system in an Unpiloted Atmospheric Vehicle (UAV) which would require a total payload mass of less than 150 kg and power requirement of less than 1500 W. A laser technology has emerged that could potentially provide significant enhancements over the present ozone DIAL system. The flashlamp pumped Ti:sapphire laser system is an emerging technology that could reduce the mass and volume over the present system and also provide a system with fewer conversion steps, reducing system complexity. This paper will discuss preliminary results from a flashlamp-pumped Ti:sapphire laser constructed as a radiation source for a UV DIAL system to measure ozone.

Argon dye photocoagulator for microsurgery of the interior structure of the eye

NASA Astrophysics Data System (ADS)

Wolinski, Wieslaw L.; Kazmirowski, Antoni; Kesik, Jerzy; Korobowicz, Witold; Spytkowski, Wojciech

1991-08-01

Argon-dye laser photocoagulator for the microsurgery of the interior structure of the eye is described. Some technical specifications like power stability shape of the spots and the dependence of the power on the tissue vs. wavelenght for dye laser are given. Argon-dye photocoagulator was designed and constructed including argon laser tube and dye laser in Institute of Microelectronics and Optoelectronics Technical University of Warsaw.

Single mode pulsed dye laser oscillator

DOEpatents

Hackel, R.P.

1992-11-24

A single mode pulsed dye laser oscillator is disclosed. The dye laser oscillator provides for improved power efficiency by reducing the physical dimensions of the overall laser cavity, which improves frequency selection capability. 6 figs.

Solvent-free fluidic organic dye lasers.

PubMed

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

2013-05-06

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

Applications of lasers and electro-optics

NASA Astrophysics Data System (ADS)

Tan, B. C.; Low, K. S.; Chen, Y. H.; Ahmad, Harith; Tou, T. Y.

Supported by the IRPA Programme on Laser Technology and Applications, many types of lasers have been designed, constructed and applied in various areas of science, medicine and industries. Amongst these lasers constructed were high power carbon dioxide lasers, rare gas halide excimer lasers, solid state Neodymium-YAG lasers, nitrogen lasers, flashlamp pumped dye lasers and nitrogen and excimer laser pumped dye lasers. These lasers and the associated electro-optics system, some with computer controlled, are designed and developed for the following areas of applications: (1) industrial applications of high power carbon dioxide lasers for making of i.c. components and other materials processing purposes -- prototype operational systems have been developed; (2) Medical applications of lasers for cancer treatment using the technique of photodynamic therapy -- a new and more effective treatment protocol has been proposed; (3) agricultural applications of lasers in palm oil and palm fruit-fluorescence diagnostic studies -- fruit ripeness signature has been developed and palm oil oxidation level were investigated; (4) development of atmospheric pollution monitoring systems using laser lidar techniques -- laboratory scale systems were developed; and (5) other applications of lasers including laser holographic and interferometric methods for the non destructive testing of materials.

Simultaneous RGB lasing from a single-chip polymer device.

PubMed

Yamashita, Kenichi; Takeuchi, Nobutaka; Oe, Kunishige; Yanagi, Hisao

2010-07-15

This Letter describes the fabrication and operation of a single-chip white-laser device. The laser device has a multilayered structure consisting of three laser layers. Each laser layer comprises polymer claddings and a waveguide core doped with organic dye. In each laser layer, grating corrugations were fabricated by UV-nanoimprint lithography that act as distributed-feedback cavity structures. Under optical pumping, lasing output with red, green, and blue colors was simultaneously obtained from the sample edge.

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

Koch, T.H.

Coumarin laser dyes upon excitation degrade to produce products that absorb at the lasing wavelength. This results in attenuation of dye laser output through interference of stimulated emission. The roles of singlet oxygen and excitation intensity on dye degradation were explored. Singlet oxygen is formed but its reactions with the dye do not appear to be a major cause of dye laser output deterioration. High light intensity results in dye-sensitized, solvent oligomerization to yield materials that interfere with dye-stimulated emission. 1, 4-Diazabicyclo2,2,2octane (DABCO)inhibits this oligomerization.

Dye laser amplifier including a dye cell contained within a support vessel

DOEpatents

Davin, James

1992-01-01

A large (high flow rate) dye laser amplifier in which a continous replenished supply of dye is excited by a first light beam, specifically a copper vapor laser beam, in order to amplify the intensity of a second different light beam, specifically a dye beam, passing through the dye is disclosed herein. This amplifier includes a dye cell defining a dye chamber through which a continuous stream of dye is caused to pass at a flow rate of greater than 30 gallons/minute at a static pressure greater than 150 pounds/square inch and a specifically designed support vessel for containing the dye cell.

Turnable Blue-Green LIDAR Transmitter Demonstration: Injection Laser Technology

DTIC Science & Technology

1990-08-30

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

Laser dye DCM: CW, synchronously pumped, cavity pumped and single-frequency performance

NASA Astrophysics Data System (ADS)

Marason, E. G.

1981-04-01

Laser dye DCM exhibits a tuning range of 605 to 725 nm with a lasing efficiency as high as 34% when pumped by the 488 nm line of the argon ion laser, placing it among the most efficient and broadly tunable dyes known. Performance of the dye is characterized for four laser systems: 1) continuous wave, 2) synchronously pumped (SP), 3) cavity dumped synchrompously pumped (SPCD) and 4) single-frequency ring dye laser. Pulse peak powers were as high as 520 W and 2.8 kW for SP and SPCD systems respectively.

Three color laser fluorometer for studies of phytoplankton fluorescence

NASA Technical Reports Server (NTRS)

Phinney, David A.; Yentsch, C. S.; Rohrer, J.

1988-01-01

A three-color laser fluorometer has been developed for field work operations. Using two tunable dye lasers (excitation wavelengths at 440 nm and 530 nm), broadband wavelength optical filters were selected to obtain maximum fluorescence sensitivity at wavelengths greater than 675 nm (chlorophyll) and 575 + or - 15 nm (phycoerythrin). The laser fluorometer permits the measurement of phytoplankton pigments under static or flowing conditions and more closely resembles the time scales (ns) and energy levels (mW) of other laser-induced fluorescence instruments.

Dye laser amplifier including a low turbulence, stagnation-free dye flow configuration

DOEpatents

Davin, J.

1992-12-01

A large (high flow rate) dye laser amplifier in which a continuous replenished supply of dye is excited by a first light beam, specifically a copper vapor laser beam, in order to amplify the intensity of a second different light beam, specifically a dye beam, passing through the dye is disclosed herein. This amplifier includes a dye cell defining a dye chamber through which a continuous stream of dye is caused to pass at a flow rate of for example 30 gallons/minute, a specifically designed support vessel for containing the dye cell and a screen device for insuring that the dye stream passes into the dye cell in a substantially turbulent free, stagnation-free manner. 9 figs.

Fundamental characteristics of degradation-recoverable solid-state DFB polymer laser.

PubMed

Yoshioka, Hiroaki; Yang, Yu; Watanabe, Hirofumi; Oki, Yuji

2012-02-13

A novel solid-state dye laser with degradation recovery was proposed and demonstrated. Polydimethylsiloxane was used as a nanoporous solid matrix to enable the internal circulation of dye molecules in the solid state. An internal circulation model for the dye molecules was also proposed and verified numerically by assuming molecular mobility and using a proposed diffusion equation. The durability of the laser was increased 20.5-fold compared with that of a conventional polymethylmethacrylate laser. This novel laser solves the low-durability problem of dye-doped polymer lasers.

Feasibility of solar-pumped dye lasers

NASA Technical Reports Server (NTRS)

Lee, Ja H.; Kim, Kyung C.; Kim, Kyong H.

1987-01-01

Dye laser gains were measured at various pump-beam irradiances on a dye cell in order to evaluate the feasibility of solar pumping. Rhodamine 6G dye was considered as a candidate for the solar-pumped laser because of its high utilization of the solar spectrum and high quantum efficiency. Measurements show that a solar concentration of 20,000 is required to reach the threshold of the dye.

Hair ignition by dye laser for port-wine stain: risk factors evaluated.

PubMed

Molin, L; Hallgren, S

1999-04-01

Flashlamp-pumped pulsed dye laser is the preferred treatment for port-wine stain. Vascular hemoglobin and epidermal melanin are competing sites for dye laser absorption and damage. The case presented illustrates the potential hazard of ignition induced by dye laser treatment on the face of a patient receiving inhalation anesthesia. A 6-year-old girl with almost black hair was treated for a port-wine stain covering most of the right half of her face. She was treated with dye laser under general anesthesia administered by mask. A laser pulse close to the upper part of the eyebrow induced a blaze and the eyebrow was instantly destroyed by the fire. Regrowth of the eyebrow was complete after a few months. Hair specimens of various colors were exposed experimentally to dye laser irradiation in room and oxygen-saturated atmospheres. Risk factors of ignition are high laser dosage, a high oxygen level, repeated pulses and dark colored hair.

Preparation of 6-hydroxyindolines and their use for preparation of novel laser dyes

DOEpatents

Field, George F.; Hammond, Peter R.

1993-01-01

A novel method for the synthesis of 6-hydroxyindolines and new fluorescent dyes produced therefrom, which dyes are ring-constrained indoline-based rhodamine class dyes. These dyes have absorption and emission spectra which make them particularly useful in certain dye laser applications.

Laser head for simultaneous optical pumping of several dye lasers. [with single flash lamp

NASA Technical Reports Server (NTRS)

Mumola, P. B.; Mcalexander, B. T. (Inventor)

1975-01-01

The invention is a laser head for simultaneous pumping several dye lasers with a single flash lamp. The laser head includes primarily a multi-elliptical cylinder cavity with a single flash lamp placed along the common focal axis of the cavity and with capillary tube dye cells placed along each of the other focal axes of the cavity. The inside surface of the cavity is polished. Hence, the single flash lamp supplies the energy to the several dye cells.

Preparation of 6-hydroxyindolines and their use for preparation of novel laser dyes

DOEpatents

Field, G.F.; Hammond, P.R.

1993-10-26

A novel method is described for the synthesis of 6-hydroxyindolines and new fluorescent dyes produced therefrom, which dyes are ring-constrained indoline-based rhodamine class dyes. These dyes have absorption and emission spectra which make them particularly useful in certain dye laser applications.

Absolute tracer dye concentration using airborne laser-induced water Raman backscatter

NASA Technical Reports Server (NTRS)

Hoge, F. E.; Swift, R. N.

1981-01-01

The use of simultaneous airborne-laser-induced dye fluorescence and water Raman backscatter to measure the absolute concentration of an ocean-dispersed tracer dye is discussed. Theoretical considerations of the calculation of dye concentration by the numerical comparison of airborne laser-induced fluorescence spectra with laboratory spectra for known dye concentrations using the 3400/cm OH-stretch water Raman scatter as a calibration signal are presented which show that minimum errors are obtained and no data concerning water mass transmission properties are required when the laser wavelength is chosen to yield a Raman signal near the dye emission band. Results of field experiments conducted with an airborne conical scan lidar over a site in New York Bight into which rhodamine dye had been injected in a study of oil spill dispersion are then indicated which resulted in a contour map of dye concentrations, with a minimum detectable dye concentration of approximately 2 ppb by weight.

Theoretical studies of solar-pumped lasers

NASA Technical Reports Server (NTRS)

Harries, W. L.

1983-01-01

Possible types of lasers were surveyed for solar power conversion. The types considered were (1) liquid dye lasers, (2) vapor dye lasers, and (3) nondissociative molecular lasers. These are discussed.

Pulsed Nd-YAG laser in endodontics

NASA Astrophysics Data System (ADS)

Ragot-Roy, Brigitte; Severin, Claude; Maquin, Michel

1994-12-01

The purpose of this study was to establish an operative method in endodontics. The effect of a pulsed Nd:YAG laser on root canal dentin has been examined with a scanning electron microscope. Our first experimentation was to observe the impacts carried out perpendicularly to root canal surface with a 200 micrometers fiber optic in the presence of dye. Secondarily, the optical fiber was used as an endodontic instrument with black dye. The irradiation was performed after root canal preparation (15/100 file or 40/100 file) or directly into the canal. Adverse effects are observed. The results show that laser irradiation on root canal dentin surfaces induces a nonhomogeneous modified dentin layer, melted and resolidified dentin closed partially dentinal tubules. The removal of debris is not efficient enough. The laser treatment seems to be indicated only for endodontic and periapical spaces sterilization after conventional root canal preparation.

A switchable digital microfluidic droplet dye-laser.

PubMed

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

2011-11-07

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

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.

Intense excitation source of blue-green laser

NASA Astrophysics Data System (ADS)

Han, Kwang S.

1986-10-01

An intense and efficient source for blue green laser useful for the space-based satellite laser applications, underwater strategic communication, and measurement of ocean bottom profile is being developed. The source in use, the hypocycloidal pinch plasma (HCP), and the dense plasma focus (DPF) can produce intense uv photons (200 to 400nm) which match the absorption spectra of both near UV and blue green dye lasers (300 to 400nm). As a result of optimization of the DPF light at 355nm, the blue green dye (LD490) laser output exceeding 4mJ was obtained at the best cavity tunning of the laser system. With the HCP pumped system a significant enhancement of the blue green laser outputs with dye LD490 and coumarin 503 has been achieved through the spectrum conversion of the pumping light by mixing a converter dye BBQ. The maximum increase of laser output with the dye mixture of LD490+BBQ and coumarin 503+BBQ was greater than 80%. In addition, the untunned near UV lasers were also obtained. The near UV laser output energy of P-terphenyl dye was 0.5mJ at lambda sub C=337nm with the bandwidth of 3n m for the pulse duration of 0.2us. Another near UV laser output energy obtained with BBQ dye was 25 mJ at lambda sub C=383nm with the bandwidth of 3nm for the pulse duration of 0.2us. Another near UV laser output energy obtained with BBQ dye was 25 mJ at lambda sub C=383nm with the bandwidth of 3nm for the pulse duration of 0.2microsec.

Excimer Pumped Pulsed Tunable Dye Laser

NASA Astrophysics Data System (ADS)

Littman, Michael G.

1988-06-01

It has been recently shown and reported for the first time at this meeting, that Excimer pumping of a single-mode, short-cavity, grazing-incidence, longitudinally-pumped pulsed dye laser is feasible. In this paper the key concepts upon which this latest development is based are presented and are in a somewhat unusual form. This manuscript describes five specific dye laser examples. The five examples represent a progression from the simplest type of dye laser to the single-mode version mentioned above. The examples thus serve as a tutorial introduction to potential users of dye lasers. The article is organized into five sections or STEPS, each of which describes a different pulsed dye laser. Since the subtle points about dye lasers are best appreciated only after one actually attempts to build a working model, a PROCEDURES category is included in which details about the construction of the particular form of laser are given. As one reads through this category, think of it as looking over the shoulder of the laser builder. The NOTES category which follows is a brief but essential discussion explaining why various components and procedures are used, as well as how laser performance specifications are obtained. This subsection can he viewed as a discussion with the laser builder concerning the reasons for specific actions and choices made in the assembly of the example laser. The last category contains COMMENTS which provide additional related information pertaining to the example laser that goes beyond the earlier annotated discussion. If you like, these are the narrator's comments. At the end of the article, after the five sequential forms of the laser have been presented, there is a brief summation.

Identification Of Natural Dyes On Archaeological Textile Objects Using Laser Induced Fluorescent Technique

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

Abdel-Kareem, O.; Eltokhy, A.; Harith, M. A.

2011-09-22

This study aims to evaluate the use of Laser Fluorescent as a non-destructive technique for identification of natural dyes on archaeological textile objects. In this study wool textile samples were dyed with 10 natural dyes such as cochineal, cutch, henna, indigo, Lac, madder, safflower, saffron, sumac and turmeric. These dyes common present on archaeological textile objects to be used as standard dyed textile samples. These selected natural dyes will be used as known references that can be used a guide to identify unknown archaeological dyes. The dyed textile samples were investigated with laser radiation in different wavelengths to detect themore » best wavelengths for identification each dye. This study confirms that Laser Florescent is very useful and a rapid technique can be used as a non-destructive technique for identification of natural dyes on archaeological textile objects. The results obtained with this study can be a guide for all conservators in identification of natural organic dyes on archaeological textile objects.« less

Identification Of Natural Dyes On Archaeological Textile Objects Using Laser Induced Fluorescent Technique

NASA Astrophysics Data System (ADS)

Abdel-Kareem, O.; Eltokhy, A.; Harith, M. A.

2011-09-01

This study aims to evaluate the use of Laser Fluorescent as a non-destructive technique for identification of natural dyes on archaeological textile objects. In this study wool textile samples were dyed with 10 natural dyes such as cochineal, cutch, henna, indigo, Lac, madder, safflower, saffron, sumac and turmeric. These dyes common present on archaeological textile objects to be used as standard dyed textile samples. These selected natural dyes will be used as known references that can be used a guide to identify unknown archaeological dyes. The dyed textile samples were investigated with laser radiation in different wavelengths to detect the best wavelengths for identification each dye. This study confirms that Laser Florescent is very useful and a rapid technique can be used as a non-destructive technique for identification of natural dyes on archaeological textile objects. The results obtained with this study can be a guide for all conservators in identification of natural organic dyes on archaeological textile objects.

Photoactive dye-enhanced tissue ablation for endoscopic laser prostatectomy.

PubMed

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

2014-11-01

Laser light has been widely used as a surgical tool to treat benign prostate hyperplasia (BPH) over 20 years. Recently, application of high laser power up to 200 W was often reported to swiftly remove a large amount of prostatic tissue. The purpose of this study was to validate the feasibility of photoactive dye injection to enhance light absorption and eventually to facilitate tissue vaporization with low laser power. Chicken breast tissue was selected as a target tissue due to minimal optical absorption at the visible wavelength. Four biocompatible photoactive dyes, including 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/cm(2) . 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 radiant exposure, dye concentration, and number of injection. Among the dyes, AR created the highest ablation rate of 44.2 ± 0.2 µm/pulse due to higher absorbance and lower ablation threshold. High aspect ratios up to 7.1 ± 0.4 entailed saturation behavior in the tissue ablation injected with AR and BD, possibly resulting from plume shielding and increased scattering due to coagulation. 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. Due to efficient coupling of optical energy, pre-injection of photoactive dyes promoted the degree of tissue removal during laser irradiation. Further studies will investigate spatial distribution of dyes and optimal injecting pressure to govern the extent of dye-assisted ablation in a predictable manner. In-depth comprehension on photoactive dye-enhanced tissue ablation can help accomplish efficient and safe laser vaporization for BPH with low power application. © 2014 Wiley Periodicals, Inc.

Threshold pump power of a solar-pumped dye laser

NASA Technical Reports Server (NTRS)

Lee, Ja H.; Kim, Kyung C.; Kim, Kyong H.

1988-01-01

Threshold solar power for dye laser pumping has been determined by measuring the gain of a rhodamine 6G dye laser amplifier at various solar-simulated irradiances on an amplifier cell. The measured threshold was 20,000 solar constants (2.7 kW/sq cm) for the dye volume of 2 x 5 x 40 cu mm and the optimum dye concentration of 0.001 M. The threshold is about one-third of that achievable with a high-intensity solar concentrator.

Photodegradation and Photophysics of Laser Dyes

DTIC Science & Technology

1994-06-30

research. "The Photophysics and Photochem istry of’ Orgainic Laser Dyecs uander Conditions oit Binding to Polymethacrylic Acid in Water** thcsis...c 13. ABSTRACT (Maximum 200 wotrds) 6 The solubilization of laser dyes in water with the aid of the polyelectrolyte, poly(methacr,-- lic acid ) (PMAA...moderately acidic pH. Polymer-bound dyes in water display markedly enhanced emission yield, lifetime, and polarization. Dye materials are also less

Compact Ozone Differential Absorption Lidar (DIAL) Transmitter Using Solid-State Dye Polymers

NASA Technical Reports Server (NTRS)

Jones, Alton L., Jr.; DeYoung, Russell J.; Elsayid-Ele, Hani

2001-01-01

A new potential DIAL laser transmitter is described that uses solid-state dye laser materials to make a simpler, more compact, lower mass laser system. Two solid-state dye laser materials were tested to evaluate their performance in a laser oscillator cavity end pumped by a pulsed Nd:YAG laser at 532 nm. The polymer host polymethyl-methacrylate was injected with a pyrromethene laser dye, PM 580, or PM 597. A narrowband laser oscillator cavity was constructed to produce visible wavelengths of 578 and 600 nm which were frequency doubled into the UV region (299 or 300 nm) by using a BBO crystal, resulting in a maximum energy of 11 mJ at a wavelength of 578 nm when pumped by the Nd:YAG laser at an energy of 100 mJ (532 nm). A maximum output energy of 378 microJ was achieved in the UV region at a wavelength of 289 nm but lasted only 2000 laser shots at a repetition rate of 10 Hz. The results are promising and show that a solid-state dye laser based ozone DIAL system is possible with improvements in the design of the laser transmitter.

Transforming Benzophenoxazine Laser Dyes into Chromophores for Dye-Sensitized Solar Cells: A Molecular Engineering Approach

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

Schröder, Florian A. Y. N.; Cole, Jacqueline M.; Waddell, Paul G.

2015-02-03

The re-functionalization of a series of four well-known industrial laser dyes, based on benzophenoxazine, is explored with the prospect of molecularly engineering new chromophores for dye-sensitized solar cell (DSC) applications. Such engineering is important since a lack of suitable dyes is stifling the progress of DSC technology. The conceptual idea involves making laser dyes DSC-active by chemical modification, while maintaining their key property attributes that are attractive to DSC applications. This molecular engineering follows a step-wise approach. Firstly, molecular structures and optical absorption properties are determined for the parent laser dyes: Cresyl Violet (1); Oxazine 170 (2); Nile Blue Amore » (3), Oxazine 750 (4). These reveal structure-property relationships which define the prerequisites for computational molecular design of DSC dyes; the nature of their molecular architecture (D-π-A) and intramolecular charge transfer. Secondly, new DSC dyes are computationally designed by the in silico addition of a carboxylic acid anchor at various chemical substitution points in the parent laser dyes. A comparison of the resulting frontier molecular orbital energy levels with the conduction band edge of a TiO2 DSC photoanode and the redox potential of two electrolyte options I-/I3- and Co(II/III)tris(bipyridyl) suggests promise for these computationally designed dyes as co-sensitizers for DSC applications.« less

Aerosol-fluorescence spectrum analyzer: real-time measurement of emission spectra of airborne biological particles

NASA Astrophysics Data System (ADS)

Hill, Steven C.; Pinnick, Ronald G.; Nachman, Paul; Chen, Gang; Chang, Richard K.; Mayo, Michael W.; Fernandez, Gilbert L.

1995-10-01

We have assembled an aerosol-fluorescence spectrum analyzer (AFS), which can measure the fluorescence spectra and elastic scattering of airborne particles as they flow through a laser beam. The aerosols traverse a scattering cell where they are illuminated with intense (50 kW/cm 2) light inside the cavity of an argon-ion laser operating at 488 nm. This AFS can obtain fluorescence spectra of individual dye-doped polystyrene microspheres as small as 0.5 mu m in diameter. The spectra obtained from microspheres doped with pink and green-yellow dyes are clearly different. We have also detected the fluorescence spectra of airborne particles (although not single particles) made from various

Enhancement of KTP/532 laser disc decompression and arthroscopic microdiscectomy with a vital dye

NASA Astrophysics Data System (ADS)

Yeung, Anthony T.

1993-07-01

Currently, the clinical indications and results of arthroscopic microdiscectomy and laser disc decompression come close to, but do not exceed, the results of classic discectomy or microdiscectomy for the whole spectrum of surgical disc herniations. However, as minimally invasive techniques continue to evolve, results can be expected to equal or be potentially superior to conventional surgery. This exhibit demonstrates how the use of a vital dye can enhance standard arthroscopic microdiscectomy techniques and, when used in conjunction with KTP/532 laser disc decompression, allows for better arthroscopic visualization, documentation, and extraction of nucleus pulposus, ultimately expanding the current limiting criteria for minimally invasive techniques. When proper patient selection is combined with good clinical indications, the surgical results are rather dramatic, often achieving immediate relief of sciatica in the operating room.

Composition and method of preparation of solid state dye laser rods

DOEpatents

Hermes, Robert E.

1992-01-01

The present invention includes solid polymeric-host laser rods prepared using bulk polymerization of acrylic acid ester comonomers which, when admixed with dye(s) capable of supporting laser oscillation and polymerized with a free radical initiator under mild thermal conditions, produce a solid product having the preferred properties for efficient lasing. Unsaturated polymerizable laser dyes can also be employed as one of the comonomers. Additionally, a method is disclosed which alleviates induced optical stress without having to anneal the polymers at elevated temperatures (>85.degree. C.).

Multi-wavelength laser from dye-doped cholesteric polymer films.

PubMed

Huang, Yuhua; Wu, Shin-Tson

2010-12-20

A multi-wavelength laser is demonstrated using a dye-doped cholesteric polymer film whose reflection bandwidth is broadened with several oscillations. Due to the abrupt change of the density of state between oscillation peak and valley, each oscillation functions as a photonic band gap for generating a laser wavelength under the excitation of a pumping laser. As a result, a multiple wavelength laser is generated. Results indicate that the dye-doped cholesteric liquid crystal polymer film is a good candidate for fabricating broadband lasers such as white light lasers. Potential applications include experimental testing of laser materials, identification markers, information displays, and inertial confinement laser fusion.

Spectroscopic properties and amplified spontaneous emission of fluorescein laser dye in ionic liquids as green media

NASA Astrophysics Data System (ADS)

AL-Aqmar, Dalal M.; Abdelkader, H. I.; Abou Kana, Maram T. H.

2015-09-01

The use of ionic liquids (ILs) as milieu materials for laser dyes is a promising field and quite competitive with volatile organic solvents and solid state-dye laser systems. This paper investigates some photo-physical parameters of fluorescein dye incorporated into ionic liquids; 1-Butyl-3-methylimidazolium chloride (BMIM Cl), 1-Butyl-3-methylimidazolium tetrachloroaluminate (BMIM AlCl4) and 1-Butyl-3-methylimidazolium tetrafluoroborate (BMIM BF4) as promising host matrix in addition to ethanol as reference. These parameters are: absorption and emission cross-sections, fluorescence lifetime and quantum yield, in addition to the transition dipole moment, the attenuation length and oscillator strength were also investigated. Lasing characteristics such as amplified spontaneous emission (ASE), the gain, and the photostability of fluorescein laser dye dissolved in different host materials were assessed. The composition and properties of the matrix of ILs were found that it has great interest in optimizing the laser performance and photostability of the investigated laser dye. Under transverse pumping of fluorescein dye by blue laser diode (450 nm) of (400 mW), the initial ASE for dye dissolved in BMIM AlCl4 and ethanol were decreased to 39% and 36% respectively as time progressed 132 min. Relatively high efficiency and high fluorescence quantum yield (11.8% and 0.82% respectively) were obtained with good photostability in case of fluorescein in BMIM BF4 that was decreased to ∼56% of the initial ASE after continuously pumping with 400 mW for 132 min.

Apparatus and method for measurement of weak optical absorptions by thermally induced laser pulsing

DOEpatents

Cremers, D.A.; Keller, R.A.

1982-06-08

The thermal lensing phenomenon is used as the basis for measurement of weak optical absorptions when a cell containing the sample to be investigated is inserted into a normally continuous-wave operation laser-pumped dye laser cavity for which the output coupler is deliberately tilted relative to intracavity circulating laser light, and pulsed laser output ensues, the pulsewidth of which can be rlated to the sample absorptivity by a simple algorithm or calibration curve. A minimum detection limit of less than 10/sup -5/ cm/sup -1/ has been demonstrated using this technique.

Apparatus and method for measurement of weak optical absorptions by thermally induced laser pulsing

DOEpatents

Cremers, D.A.; Keller, R.A.

1985-10-01

The thermal lensing phenomenon is used as the basis for measurement of weak optical absorptions when a cell containing the sample to be investigated is inserted into a normally continuous-wave operation laser-pumped dye laser cavity for which the output coupler is deliberately tilted relative to intracavity circulating laser light, and pulsed laser output ensues, the pulsewidth of which can be related to the sample absorptivity by a simple algorithm or calibration curve. A minimum detection limit of less than 10[sup [minus]5] cm[sup [minus]1] has been demonstrated using this technique. 6 figs.

Apparatus and method for measurement of weak optical absorptions by thermally induced laser pulsing

DOEpatents

Cremers, David A.; Keller, Richard A.

1985-01-01

The thermal lensing phenomenon is used as the basis for measurement of weak optical absorptions when a cell containing the sample to be investigated is inserted into a normally continuous-wave operation laser-pumped dye laser cavity for which the output coupler is deliberately tilted relative to intracavity circulating laser light, and pulsed laser output ensues, the pulsewidth of which can be related to the sample absorptivity by a simple algorithm or calibration curve. A minimum detection limit of less than 10.sup.-5 cm.sup.-1 has been demonstrated using this technique.

From Dye Laser Factory to Portable Semiconductor Laser: Four Generations of Sodium Guide Star Lasers for Adaptive Optics in Astronomy and Space Situational Awareness

NASA Astrophysics Data System (ADS)

d'Orgeville, C.; Fetzer, G.

This presentation recalls the history of sodium guide star laser systems used in astronomy and space situational awareness adaptive optics, analysing the impact that sodium laser technology evolution has had on routine telescope operations. While it would not be practical to describe every single sodium guide star laser system developed to date, it is possible to characterize their evolution in broad technology terms. The first generation of sodium lasers used dye laser technology to create the first sodium laser guide stars in Hawaii, California, and Spain in the late 1980's and 1990's. These experimental systems were turned into the first laser guide star facilities to equip medium-to-large diameter adaptive optics telescopes, opening a new era of LGS AO-enabled diffraction-limited imaging from the ground. Although they produced exciting scientific results, these laser guide star facilities were large, power-hungry and messy. In the USA, a second-generation of sodium lasers was developed in the 2000's that used cleaner, yet still large and complex, solid-state laser technology. These are the systems in routine operation at the 8-10m class astronomical telescopes and 4m-class satellite imaging facilities today. Meanwhile in Europe, a third generation of sodium lasers was being developed using inherently compact and efficient fiber laser technology, and resulting in the only commercially available sodium guide star laser system to date. Fiber-based sodium lasers will be deployed at two astronomical telescopes and at least one space debris tracking station this year. Although highly promising, these systems remain significantly expensive and they have yet to demonstrate high performance in the field. We are proposing to develop a fourth generation of sodium lasers: based on semiconductor technology, these lasers could provide the final solution to the problem of sodium laser guide star adaptive optics for all astronomy and space situational awareness applications.

Preparation of certain m-aminophenols and the use thereof for preparation of laser dyes

DOEpatents

Hammond, P.R.

1983-12-29

Methods are provided for making certain m-aminophenols using a sulfonation/alkali fusion procedure. The aminophenols are key intermediates in the synthesis of dyes, particularly efficient, stable dyes for laser application. Preparations of some rhodamine and phenoxazone dyes from the m-aminophenols are described.

Preparation of certain m-aminophenols and the use thereof for preparation of laser dyes

DOEpatents

Hammond, Peter R.

1986-01-01

Methods are provided for making certain m-aminophenols using a sulfonation/alkali fusion procedure. The aminophenols are key intermediates in the synthesis of dyes, particularly efficient, stable dyes for laser application. Preparations of some rhodamine and phenoxazone dyes from the m-aminophenols are described.

Invasive leg vein treatment with 1064/1319 Nd:YAG laser: combination with dye laser treatment

NASA Astrophysics Data System (ADS)

Smucler, Roman; Horak, Ladislav; Mazanek, Jiri

1999-06-01

More than 2 500 leg veins patients were treated with dye laser / ScleroPlus, Candela, USA / successfully in our clinic and we use this therapy as the basic cosmetics treatment. But especially diameter of leg vein is limiting factor. Very often we have to treat some cases that are not ideal for classical surgical or for dye laser method. We decided to make invasive perivenous laser coagulation. We adapted original Czech 1064/1319 nm Nd:YAG laser / US patent pending /, which is new combine tool, for invasive application. Principe: After we have penetrated the cutis with laser fiber we coagulate leg veins during slowly perivenous motion. Perfect preoperative examination is a condition of success. After 15 months we have very interesting results. Some patients / 15%/ were perfect treated only with this possibility but excellent results are acquired from combination with dye laser.

Direct solar-pumped iodine laser amplifier

NASA Technical Reports Server (NTRS)

Han, Kwang S.; Kim, K. H.; Stock, L. V.

1986-01-01

In order to evaluate the feasibility of the solar pumped dye laser, the parametric study of a dye laser amplifier pumped by a solar simulator and flashlamp was carried out, and the amplifier gains were measured at various pump beam irradiances on the dye cell. Rhodamine 6G was considered as a candidate for the solar pumped laser because of its good utilization of the solar spectrum and high quantum efficiency. The measurement shows that a solar concentration of 20,000 is required to reach the threshold of the dye. The work to construct a kinetic model algorithm which predicts the output parameter of laser was progressed. The kinetic model was improved such that there is good agreement between the theoretical model and experimental data for the systems defined previously as flashlamp pumped laser oscillator, and the long path length solar pumped laser.

Photodynamic therapy: a synergy between light and colors

NASA Astrophysics Data System (ADS)

Merigo, Elisabetta; Sozzi, Michele; Ciociola, Tecla; Conti, Stefania; Fornaini, Carlo; Vescovi, Paolo; Selleri, Stefano; Cucinotta, Annamaria

2015-02-01

In this work the application of different laser wavelengths, in combination with different photosensitizing dyes, to bacterial cultures, in liquid or solid mean, has been investigated. Two types of Streptococcus mutans cultures have been used for the experiments, inside agar and saline solution. Three different laser wavelengths have been applied to the bacterial cultures together with a photosensitizing dye: red diode (650 nm) on cultures stained with Toluidine Blue, blueviolet diode (450 nm) on cultures stained with Curcumin and KTP laser (532 nm) on cultures stained with Erythrosine. The choice of the dye has been made considering the color affinity with the used wavelength. Tests without dyes have also been performed. Experimental results show that the maximum inhibition of bacterial growth with the blue laser has been obtained in a saline solution with a growth of 40.77%. While the combination with Curcumin lead to an inhibition growth of about 99.1%, for a laser fluence of 30J/cm2. No inhibition has been observed using the red laser in saline solution without dye, while the combination with Toluidine Blue resulted in a 100% inhibition growth for 20 and 30 J/cm2 fluences. An inhibition growth of just 16.26% has been obtained with the use of KTP laser in saline solution without dye. The use of Erythrosine had the effect of a complete inhibition growth. From the obtained results it is possible to observe that the combination of laser wavelength with a particular photosensitizing dye can dramatically increase the bacterial growth.

KrF laser-induced OH fluorescence imaging in a supersonic combustion tunnel

NASA Technical Reports Server (NTRS)

Quagliaroli, T. M.; Laufer, G.; Hollo, S. D.; Krauss, R. H.; Whitehurst, R. B., III; Mcdaniel, J. C., Jr.

1992-01-01

Planar fluorescence images of OH in a continuous-flow, electrical-resistively heated, high enthalpy, hydrogen-air combustion tunnel, induced by a tunable KrF laser, were recorded. These images were compared to previously recorded fluorescence images induced by a doubled-dye laser under similar conditions. Images induced by the doubled-dye laser system demonstrated a severe distortion caused by absorption and fluorescence trapping. By contrast, images of the fluorescence induced by the tunable KrF laser retained the symmetry properties of the flow. Based on signal-to-noise ratio measurements the yield of the fluorescence induced by the doubled-dye laser is larger than the fluorescence yield induced by the KrF laser. The measurements in the present facility of OH fluorescence induced by the KrF laser were limited by the photon-statistical noise. Based 2 on this result, doubled-dye laser systems are recommended for OH imaging in small and OH lean (less than 10 exp 15/cu cm) facilities. KrF lasers should be selected otherwise.

Physically transient photonics: random versus distributed feedback lasing based on nanoimprinted DNA.

PubMed

Camposeo, Andrea; Del Carro, Pompilio; Persano, Luana; Cyprych, Konrad; Szukalski, Adam; Sznitko, Lech; Mysliwiec, Jaroslaw; Pisignano, Dario

2014-10-28

Room-temperature nanoimprinted, DNA-based distributed feedback (DFB) laser operation at 605 nm is reported. The laser is made of a pure DNA host matrix doped with gain dyes. At high excitation densities, the emission of the untextured dye-doped DNA films is characterized by a broad emission peak with an overall line width of 12 nm and superimposed narrow peaks, characteristic of random lasing. Moreover, direct patterning of the DNA films is demonstrated with a resolution down to 100 nm, enabling the realization of both surface-emitting and edge-emitting DFB lasers with a typical line width of <0.3 nm. The resulting emission is polarized, with a ratio between the TE- and TM-polarized intensities exceeding 30. In addition, the nanopatterned devices dissolve in water within less than 2 min. These results demonstrate the possibility of realizing various physically transient nanophotonics and laser architectures, including random lasing and nanoimprinted devices, based on natural biopolymers.

Optical Properties of Nano-Spherical Gold Doped Dye Solution Hybrid

NASA Astrophysics Data System (ADS)

Hoa, D. Q.; Lien, N. T. H.; Ha, C. V.; Nhung, T. H.; Long, P.

2011-03-01

Gold nanoparticles with average diameter of 16 nm which are coated with Cetrimonium Bromide (CTAB) by chemical method are dissolved in dye solution at different concentrations. The absorption spectra of the dye mixture appeared almost unchanged at low concentrations of gold nanoparticles (around 1×1014 cm-3) despite its fluorescence intensity increased many-fold. Energy transfer from gold nanoparticles to dye molecules occurs through surface plasmon resonance(SPR). The fluorescence of rhodamine 610 (Rh610) dye molecules co-adsorbed within 16 nm gold nanoparticles assemblies can be useful for enhancing gain in lasing emission. An increase in laser efficiency by a factor of one and half times stronger compared to the single Rh610 dye suggest the potential of using the mixture of rhodamine dye with gold nanoparticles as laser medium in the configuration of quenching distributed feedback dye laser.

Laser-induced fluorescence spectroscopy in tissue local necrosis detection

NASA Astrophysics Data System (ADS)

Cip, Ondrej; Buchta, Zdenek; Lesundak, Adam; Randula, Antonin; Mikel, Bretislav; Lazar, Josef; Veverkova, Lenka

2014-03-01

The recent effort leads to reliable imaging techniques which can help to a surgeon during operations. The fluorescence spectroscopy was selected as very useful online in vivo imaging method to organics and biological materials analysis. The presented work scopes to a laser induced fluorescence spectroscopy technique to detect tissue local necrosis in small intestine surgery. In first experiments, we tested tissue auto-fluorescence technique but a signal-to-noise ratio didn't express significant results. Then we applied a contrast dye - IndoCyanine Green (ICG) which absorbs and emits wavelengths in the near IR. We arranged the pilot experimental setup based on highly coherent extended cavity diode laser (ECDL) used for stimulating of some critical areas of the small intestine tissue with injected ICG dye. We demonstrated the distribution of the ICG exciter with the first file of shots of small intestine tissue of a rabbit that was captured by high sensitivity fluorescent cam.

Clean Photothermal Heating and Controlled Release from Near-Infrared Dye Doped Nanoparticles without Oxygen Photosensitization.

PubMed

Guha, Samit; Shaw, Scott K; Spence, Graeme T; Roland, Felicia M; Smith, Bradley D

2015-07-21

The photothermal heating and release properties of biocompatible organic nanoparticles, doped with a near-infrared croconaine (Croc) dye, were compared with analogous nanoparticles doped with the common near-infrared dyes ICG and IR780. Separate formulations of lipid-polymer hybrid nanoparticles and liposomes, each containing Croc dye, absorbed strongly at 808 nm and generated clean laser-induced heating (no production of (1)O2 and no photobleaching of the dye). In contrast, laser-induced heating of nanoparticles containing ICG or IR780 produced reactive (1)O2, leading to bleaching of the dye and also decomposition of coencapsulated payload such as the drug doxorubicin. Croc dye was especially useful as a photothermal agent for laser-controlled release of chemically sensitive payload from nanoparticles. Solution state experiments demonstrated repetitive fractional release of water-soluble fluorescent dye from the interior of thermosensitive liposomes. Additional experiments used a focused laser beam to control leakage from immobilized liposomes with very high spatial and temporal precision. The results indicate that fractional photothermal leakage from nanoparticles doped with Croc dye is a promising method for a range of controlled release applications.

Clean Photothermal Heating and Controlled Release From Near Infrared Dye Doped Nanoparticles Without Oxygen Photosensitization

PubMed Central

Guha, Samit; Shaw, Scott K.; Spence, Graeme T.; Roland, Felicia M.; Smith, Bradley D.

2015-01-01

The photothermal heating and release properties of biocompatible organic nanoparticles, doped with a near-infrared croconaine (Croc) dye, were compared with analogous nanoparticles doped with the common near-infrared dyes ICG and IR780. Separate formulations of lipid-polymer-hybrid nanoparticles and liposomes, each containing Croc dye, absorbed strongly at 808 nm and generated clean laser-induced heating (no production of 1O2 and no photobleaching of the dye). In contrast, laser-induced heating of nanoparticles containing ICG or IR780 produced reactive 1O2 leading to bleaching of the dye and also decomposition of co-encapsulated payload such as the drug Doxorubicin. Croc dye was especially useful as a photothermal agent for laser controlled release of chemically sensitive payload from nanoparticles. Solution state experiments demonstrated repetitive fractional release of water soluble fluorescent dye from the interior of thermosensitive liposomes. Additional experiments used a focused laser beam to control leakage from immobilized liposomes with very high spatial and temporal precision. The results indicate that fractional photothermal leakage from nanoparticles doped with Croc dye is a promising method for a range of controlled release applications. PMID:26149326

Laser lithotripsy of gallstones: alexandrite and rhodamine-6G versus coumarin dye laser: fragmentation and fiber burn-off in vitro

NASA Astrophysics Data System (ADS)

Hochberger, Juergen; Bredt, Marion; Mueller, Gudrun; Hahn, Eckhart G.; Ell, Christian

1993-05-01

In the following study three different pulsed laser lithotripsy systems were compared for the fine fragmentation of identical sets of natural and synthetic gallstones `in vitro.' Using a pulsed coumarin dye laser (504 nm), a pulsed rhodamine 6G dye laser (595 nm), and a pulsed Alexandrite laser (755 nm) a total of 184 concrements of known chemical composition, size, and weight were disintegrated to a fragment size of

Optimal parameters for laser tissue soldering: II. Premixed versus separate dye-solder techniques.

PubMed

McNally, K M; Sorg, B S; Chan, E K; Welch, A J; Dawes, J M; Owen, E R

2000-01-01

Laser tissue soldering by using an indocyanine green (ICG)-doped protein solder applied topically to the tissue surface and denatured with a diode laser was investigated in Part I of this study. The depth of light absorption was predominantly determined by the concentration of the ICG dye added to the solder. This study builds on that work with an in vitro investigation of the effects of limiting the zone of heat generation to the solder-tissue interface to determine whether more stable solder-tissue fusion can be achieved. An alternative laser tissue soldering technique was investigated, which increased light absorption at the vital solder-tissue interface. A thin layer of ICG dye was smeared over the surface to be treated, the protein solder was then placed directly on top of the dye, and the solder was denatured with an 808-nm diode laser. Because laser light at approximately 800 nm is absorbed primarily by the ICG dye, this thin layer of ICG solution restricted the heat source to the space between the solder and the tissue surfaces. A tensile strength analysis was conducted to compare the separate dye-solder technique with conventional techniques of laser tissue soldering for which a premixed dye-solder is applied directly to the tissue surface. The effect of hydration on bond stability of repairs formed by using both techniques was also investigated using tensile strength and scanning electron microscopy analysis. Equivalent results in terms of tensile strength were obtained for the premixed dye-solder technique using protein solders containing 0.25 mg/ml ICG (liquid solder, 220 +/- 35 N/cm(2); solid solder, 602 +/- 32 N/cm(2)) and for the separate dye-solder technique (liquid solder, 228 +/- 41 N/cm(2); solid solder, 578 +/- 29 N/cm(2)). The tensile strength of native bovine thoracic aorta was 596 +/- 31 N/cm(2). Repairs created by using the separate dye-solder technique were more stable during hydration than their premixed dye-solder counterparts. The conventional premixed dye-solder was simpler and approximately twice as fast to apply. The separate dye-solder technique, however, increased the shelf-life of the solder, because the dye was mixed at the time of the experiment, thus conserving its spectral absorbency properties. Two laser-assisted tissue soldering techniques have been evaluated for repairing aorta incisions in vitro. The advantages and disadvantages of each of these techniques are discussed. Copyright 2000 Wiley-Liss, Inc.

Determination of Spatial Distribution of Air Pollution by Dye Laser Measurement of Differential Absorption of Elastic Backscatter

NASA Technical Reports Server (NTRS)

Ahmed, S. A.; Gergely, J. S.

1973-01-01

This paper presents the results of an analytical study of a lidar system which uses tunable organic dye lasers to accurately determine spatial distribution of molecular air pollutants. Also described will be experimental work to date on simultaneous multiwavelength output dye laser sources for this system. Basically the scheme determines the concentration of air pollutants by measuring the differential absorption of an (at least) two wavelength lidar signal elastically backscattered by the atmosphere. Only relative measurements of the backscattered intensity at each of the two wavelengths, one on and one off the resonance absorption of the pollutant in question, are required. The various parameters of the scheme are examined and the component elements required for a system of this type discussed, with emphasis on the dye laser source. Potential advantages of simultaneous multiwavelength outputs are described. The use of correlation spectroscopy in this context is examined. Comparisons are also made for the use of infrared probing wavelengths and sources instead of dye lasers. Estimates of the sensitivity and accuracy of a practical dye laser system of this type, made for specific pollutants, snow it to have inherent advantages over other schemes for determining pollutant spatial distribution.

On-chip tunable optofluidic dye laser

NASA Astrophysics Data System (ADS)

Cai, Zengyan; Shen, Zhenhua; Liu, Haigang; Yue, Huan; Zou, Yun; Chen, Xianfeng

2016-11-01

We demonstrate a chip-scale tunable optofluidic dye laser with Au-coated fibers as microcavity. The chip is fabricated by soft lithography. When the active region is pumped, a relatively low threshold of 6.7 μJ/mm2 is realized with multimode emission due to good confinement of the cavity mirrors, long active region, as well as total reflectivity. It is easy to tune the lasing emission wavelength by changing the solvent of laser dye. In addition, the various intensity ratios of multicolor lasing can be achieved by controlling flow rates of two fluid streams carried with different dye molecules. Furthermore, the convenience in fabrication and directional lasing emission outcoupled by the fiber make the tunable optofluidic dye laser a promising underlying coherent light source in the integrated optofluidic systems.

PicoGreen dye as an active medium for plastic lasers

NASA Astrophysics Data System (ADS)

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

2015-08-01

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

Intense excitation source of blue-green laser

NASA Astrophysics Data System (ADS)

Han, K. S.

1985-10-01

An intense and efficient excitation source for blue-green lasers useful for the space-based satellite laser applications, underwater strategic communication, and measurement of ocean bottom profile is being developed. The source in use, hypocycloidal pinch plasma (HCP), and a newly designed dense-plasma focus (DPF) can produce intense UV photons (200 to 300 nm) which match the absorption spectra of both near UV and blue green dye lasers (300 to 400 nm). During the current project period, the successful enhancement of blue-green laser output of both Coumarin 503 and LD490 dye through the spectral conversion of the HCP pumping light has been achieved with a converter dye BBQ. The factor of enhancement in the blue-green laser output energy of both Coumarin 503 and LD490 is almost 73%. This enhancement will definitely be helpful in achieving the direct high power blue-green laser (> 1 MW) with the existing blue green dye laser. On the other hand the dense-plasma focus (DPF) with new optical coupling has been designed and constructed. For the optimization of the DPF device as the UV pumping light source, the velocity of current sheath and the formation of plasma focus have been measured as function of argon or argon-deuterium fill gas pressure. Finally, the blue-green dye laser (LD490) has been pumped with the DPF device for preliminary tests. Experimental results with the DPF device show that the velocity of the current sheath follows the inverse relation of sq st. of pressure as expected. The blue-green dye (LD490) laser output exceeded 3.1 m at the best cavity tuning of laser system. This corresponds to 3J/1 cu cm laser energy extraction.

Plasma shield lasertripsy: in vitro studies.

PubMed

Bhatta, K M; Rosen, D I; Dretler, S P

1989-10-01

A technique for safer and more effective pulsed laser lithotripsy of urinary and biliary calculi was investigated in vitro. The technique involves enclosing the distal end of the laser delivery fiber in a "plasma shield." The plasma shield is a specially designed metal cap that serves to transfer the laser-induced mechanical impulse to the calculus while shielding surrounding tissue from direct laser exposure and thermal radiation. The metal cap also offers the advantage of effectively blunting the sharp fiber tip and improving its visualization under fluoroscopy. Plasma shield lithotripsy using a 200 micron quartz fiber inserted into a section of a modified 0.034 in. diameter stainless steel guide wire was tested in vitro on a variety of calculi and compared with results obtained using a 200 micron laser fiber applied directly. Calculi tested included cystine, struvite and calcium oxalate dihydrate urinary stones and pigmented cholesterol gallstones. The laser source was a flashlamp-pumped dye laser producing pulses of 1.2 microsecond duration and operated at a wavelength of 504 nm and pulse repetition frequency of 5 Hz. The results show that plasma shield lasertripsy is as effective as direct lasertripsy for fragmenting gallstones, struvite and calcium oxalate dihydrate calculi, is potentially safer, and can fragment cystine calculi which the pulsed dye laser applied directly cannot.

New ultra-high resolution dye laser spectrometer utilizing a non-tunable reference resonator

NASA Astrophysics Data System (ADS)

Helmcke, J.; Snyder, J. J.; Morinaga, A.; Mensing, F.; Gläser, M.

1987-06-01

A new dye laser spectrometer utilizing a non-tunable reference resonator is described. The resonator consists of two Zerodur mirrors optically contacted to a Zerodur spacer. Frequency scanning of the laser is provided by acoustooptic modulation. Residual drifts of the resonator frequency — measured on line — are compensated automatically by corresponding corrections of the modulation frequency. The stability during several hours and the resettability of the dye laser frequency are±2.5 kHz and±10 kHz, respectively.

Picosecond pulse measurements using the active laser medium

NASA Technical Reports Server (NTRS)

Bernardin, James P.; Lawandy, N. M.

1990-01-01

A simple method for measuring the pulse lengths of synchronously pumped dye lasers which does not require the use of an external nonlinear medium, such as a doubling crystal or two-photon fluorescence cell, to autocorrelate the pulses is discussed. The technique involves feeding the laser pulses back into the dye jet, thus correlating the output pulses with the intracavity pulses to obtain pulse length signatures in the resulting time-averaged laser power. Experimental measurements were performed using a rhodamine 6G dye laser pumped by a mode-locked frequency-doubled Nd:YAG laser. The results agree well with numerical computations, and the method proves effective in determining lengths of picosecond laser pulses.

Dye system for dye laser applications

DOEpatents

Hammond, Peter R.

1991-01-01

A dye of the DCM family, [2-methyl-6-[2-(1,2,3,4-tetrahydro-1-methyl-6-quinolinyl)ethenyl]-4H-pyran -4-ylidene]-propanedinitrile, dissolved in 2-phenoxyethanol, is non-mutagenic, stable and efficient, particularly in a pumped continuous wave laser system.

Co-extruded mechanically tunable multilayer elastomer laser

NASA Astrophysics Data System (ADS)

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

2011-04-01

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

An All-Solid-State High Repetiton Rate Titanium:Sapphire Laser System For Resonance Ionization Laser Ion Sources

NASA Astrophysics Data System (ADS)

Mattolat, C.; Rothe, S.; Schwellnus, F.; Gottwald, T.; Raeder, S.; Wendt, K.

2009-03-01

On-line production facilities for radioactive isotopes nowadays heavily rely on resonance ionization laser ion sources due to their demonstrated unsurpassed efficiency and elemental selectivity. Powerful high repetition rate tunable pulsed dye or Ti:sapphire lasers can be used for this purpose. To counteract limitations of short pulse pump lasers, as needed for dye laser pumping, i.e. copper vapor lasers, which include high maintenance and nevertheless often only imperfect reliability, an all-solid-state Nd:YAG pumped Ti:sapphire laser system has been constructed. This could complement or even replace dye laser systems, eliminating their disadvantages but on the other hand introduce shortcomings on the side of the available wavelength range. Pros and cons of these developments will be discussed.

Performance of a nonlaser light source for photodynamic therapy

NASA Astrophysics Data System (ADS)

Whitehurst, Colin; Byrne, Karen T.; Morton, Colin; Moore, James V.

1995-03-01

Advances in short arc technology and optical filter coatings led to the design and construction of a table-top light source in 1989; the first viable and cost-effective alternative to a laser. The device can deliver over 3 W within a 30 nm band centered at any wavelength from 200 nm to 1200 nm at fluence rates of over 1 W cm-2. Its relative biological effectiveness (RBE) in vitro has been proven alongside an argon pumped dye laser and a copper vapor pumped dye laser. These in vitro tests showed an efficiency of hematoporphyrin derivative (HPD) induced cellular photoinactivation close to that of the argon/dye laser (RBE 100%), with a mean RBE for the lamp of 87 +/- 3% (p < 0.05). The lamp proved to be superior to that of the copper/dye laser system with an RBE of up to 150% at fluence rates above 50 mWcm-2. In vivo tests show that the extent and depth of tumor necrosis are comparable to that of an argon/dye laser. An in situ bioassay using tumor regrowth delay is currently underway. Early clinical trials show clearance of Bowen's disease and actinic keratosis using the same light fluences as costly PDT lasers.

Skin closure with dye-enhanced laser welding and fibrinogen.

PubMed

Wider, T M; Libutti, S K; Greenwald, D P; Oz, M C; Yager, J S; Treat, M R; Hugo, N E

1991-12-01

The topical application of wavelength-specific dye and fibrinogen has been used to enhance laser closure of vascular anastomoses. We compared the closure of skin incisions by two different dye-enhanced, fibrinogen-based laser welding systems [argon laser (power density 4.78 W/cm2) with fluorescein isothiocyanate dye (n = 32) and diode laser (power density 9.55 W/cm2) with indocyanine green dye (n = 32)] with closure by interrupted 5-0 nylon suture (n = 64) and examined tensile strength, hydroxyproline production, histology, and cosmesis. Two 3-cm full-thickness incisions were made on the shaved backs of 64 rats. One incision was closed with suture, whereas the other, after treatment with the appropriate dye, was welded with either argon- or diode-lasered fibrinogen. At postoperative days 5, 10, 15, and 28, the closure sites were harvested and sectioned for analysis. Initially, wounds closed with argon-lasered fibrinogen showed less inflammatory response, greater collagen production (34.61 +/- 0.74 mg/gm), and greater mean peak stress at rupture (64.85 lbs/in2) than those closed with suture (16.42 +/- 3.20 mg/gm, 26.68 lbs/in2) (p less than 0.05). By 15 days, both argon and diode laser closures are superior in strength and collagen production to suture closure (p less than 0.05). At 28 days, diode laser closures (1315.60 lbs/in2) are stronger than suture closures (998.09 lbs/in2), whereas both are stronger than argon laser closures (813.16 lbs/in2) (p less than 0.05). Cosmetically, argon-welded wounds consistently appeared finer and lacked cross-hatched suture scars.(ABSTRACT TRUNCATED AT 250 WORDS)

Laser-activated protein solder for peripheral nerve repair

NASA Astrophysics Data System (ADS)

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

1995-05-01

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

In vitro photoacoustic measurement of hemoglobin oxygen saturation using a single pulsed broadband supercontinuum laser source.

PubMed

Lee, Changho; Jeon, Mansik; Jeon, Min Yong; Kim, Jeehyun; Kim, Chulhong

2014-06-20

We have utilized a single pulsed broadband supercontinuum laser source to photoacoustically sense total hemoglobin concentration (HbT) and oxygen saturation of hemoglobin (SO2) in bloods in vitro. Unlike existing expensive and bulky laser systems typically used for functional photoacoustic imaging (PAI), our laser system is relatively cost-effective and compact. Instead of using two single wavelengths, two wavelength bands were applied to distinguish the concentrations of two different chromophores in the mixture. In addition, we have successfully extracted the total dye concentration and the ratio of the red dye concentration to the total dye concentration in mixed red and blue dye solutions in phantoms. The results indicate that PAI with a cheap and compact fiber based laser source can potentially provide HbT and SO2 in live animals in vivo.

Numerical investigation of vessel heating using a copper vapor laser and a pulsed dye laser in treating vascular skin lesions

NASA Astrophysics Data System (ADS)

Pushkareva, A. E.; Ponomarev, I. V.; Isaev, A. A.; Klyuchareva, S. V.

2018-02-01

A computer simulation technique was employed to study the selective heating of a tissue vessel using emission from a pulsed copper vapor laser and a pulsed dye laser. The depth and size of vessels that could be selectively and safely removed were determined for the lasers under examination.

Fiber optics interface for a dye laser oscillator and method

DOEpatents

Johnson, Steve A.; Seppala, Lynn G.

1986-01-01

A dye laser oscillator in which one light beam is used to pump a continuous tream of dye within a cooperating dye chamber for producing a second, different beam is generally disclosed herein along with a specific arrangement including an optical fiber and a fiber optics interface for directing the pumping beam into the dye chamber. The specific fiber optics interface illustrated includes three cooperating lenses which together image one particular dimension of the pumping beam into the dye chamber from the output end of the optical fiber in order to insure that the dye chamber is properly illuminated by the pumping beam.

Fiber optics interface for a dye laser oscillator and method

DOEpatents

Johnson, S.A.; Seppala, L.G.

1984-06-13

A dye laser oscillator in which one light beam is used to pump a continuous stream of dye within a cooperating dye chamber for producing a second, different beam is generally disclosed herein along with a specific arrangement including an optical fiber and a fiber optics interface for directing the pumping beam into the dye chamber. The specific fiber optics interface illustrated includes three cooperating lenses which together image one particular dimension of the pumping beam into the dye chamber from the output end of the optical fiber in order to insure that the dye chamber is properly illuminated by the pumping beam.

Time-Delayed Two-Step Selective Laser Photodamage of Dye-Biomolecule Complexes

NASA Astrophysics Data System (ADS)

Andreoni, A.; Cubeddu, R.; de Silvestri, S.; Laporta, P.; Svelto, O.

1980-08-01

A scheme is proposed for laser-selective photodamage of biological molecules, based on time-delayed two-step photoionization of a dye molecule bound to the biomolecule. The validity of the scheme is experimentally demonstrated in the case of the dye Proflavine, bound to synthetic polynucleotides.

Intensity calibration of a laser scanning confocal microscope based on concentrated dyes.

PubMed

Model, Michael A; Blank, James L

2006-10-01

To find water-soluble fluorescent dyes with absorption in various regions of the spectrum and investigate their utility as standards for laser scanning confocal microscopy. Several dyes were found to have characteristics required for fluorescence microscopy standards. The intensity of biological fluorescent specimens was measured against the emission of concentrated dyes. Results using different optics and different microscopes were compared. Slides based on concentrated dyes can be prepared in a highly reproducible manner and are stable under laser scanning. Normalized fluorescence of biological specimens remains consistent with different objective lenses and is tolerant to some mismatch in optical filters or imperfect pinhole alignment. Careful choice of scanning parameters is necessary to ensure linearity of intensity measurements. Concentrated dyes provide a robust and inexpensive intensity standard that can be used in basic research or clinical studies.

Comparison of pulsed dye laser versus combined pulsed dye laser and Nd:YAG laser in the treatment of inflammatory acne vulgaris.

PubMed

Salah El Din, Manal Mohamed; Samy, Nevien Ahmed; Salem, Amira Eid

2017-06-01

Both pulsed dye laser and combined 585/1064-nm (sequential dual-wavelength PDL and Nd:YAG) laser improves inflammatory skin disorders including acne vulgaris. To compare the efficacy of 585-nm pulsed dye laser versus sequential dual-wavelength PDL and Nd:YAG in treatment of acne vulgaris. Thirty patients with acne vulgaris were treated by PDL alone on half of the face while contra lateral half was treated by combined 585/1064 nm laser. The study showed that inflammatory acne lesions count was significantly reduced by 82.5% (p 0.0001) on PDL sides and by 83.5% (p 0.00001) on combined 585/1064-nm side after 8 weeks, while reduction of non-inflammatory acne lesions was observed at 8 weeks by 58.4% and 71.5% respectively. However, difference between the two modalities was not statistically significant. PDL and combined PDL/Nd:YAG laser treatment were found to be an effective, safe and well-tolerated treatment option for inflammatory and non-inflammatory acne vulgaris.

Gold nanoparticle-based plasmonic random fiber laser

NASA Astrophysics Data System (ADS)

Hu, Zhijia; Liang, Yunyun; Xie, Kang; Gao, Pengfei; Zhang, Douguo; Jiang, Haiming; Shi, Fan; Yin, Leicheng; Gao, Jiangang; Ming, Hai; Zhang, Qijin

2015-03-01

We have reported the realization of a plasmonic random fiber laser based on the localized surface plasmonic resonance of gold nanoparticles (NPs) in the liquid core optical fiber. The liquid core material contains a dispersive solution of gold NPs and laser dye pyrromethene 597 in toluene. It was experimentally proved that the fluorescence quenching of the dye is restrained in the optical fiber, which is considered one of the main sources of loss in the traditional laser system. Meanwhile, the random lasing can be more easily obtained in the random laser system with more overlap between the plasmonic resonance of the gold NPs and the photoluminescence spectrum of the dye molecules.

Direct Analysis of Textile Fabrics and Dyes Using IR Matrix-Assisted Laser Desorption Electrospray Ionization (MALDESI) Mass Spectrometry

PubMed Central

Cochran, Kristin H.; Barry, Jeremy A.; Muddiman, David C.; Hinks, David

2012-01-01

The forensic analysis of textile fibers uses a variety of techniques from microscopy to spectroscopy. One such technique that is often used to identify the dye(s) within the fiber is mass spectrometry (MS). In the traditional MS method, the dye must be extracted from the fabric and the dye components are separated by chromatography prior to mass spectrometric analysis. Direct analysis of the dye from the fabric allows the omission of the lengthy sample preparation involved in extraction, thereby significantly reducing the overall analysis time. Herein, a direct analysis of dyed textile fabric was performed using the infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) source for MS. In MALDESI, an IR laser with wavelength tuned to 2.94 μm is used to desorb the dye from the fabric sample with the aid of water as the matrix. The desorbed dye molecules are then post-ionized by electrospray ionization (ESI). A variety of dye classes were analyzed from various fabrics with little to no sample preparation allowing for the identification of the dye mass and in some cases the fiber polymer. Those dyes that were not detected using MALDESI were also not observed by direct infusion ESI of the dye standard. PMID:23237031

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Study of relaxation times of polymethine dyes used for passive mode locking of solid-state lasers emitting between 750 and 850 nm

NASA Astrophysics Data System (ADS)

Grigonis, R.; Derevyanko, Nadezhda A.; Ishchenko, Aleksandr A.; Sirutkaitis, V. A.

2001-11-01

The relaxation times τ of the bleached states of polymethine dyes absorbing light in the 750 — 850-nm are determined by the direct pump — probe method. The effect of the dye structure and the solvent type on the relaxation time is discussed. The role of different intra- and intermolecular interactions in the relaxation of excited electronic states of the dyes is analysed. Polymethine dyes are found (with τ=11 — 75 ps) that are promising for passive mode locking in Cr3+:LiCaAlF6, Cr3+:KZnF3, and Cr3+:LiSrAlF6 crystal lasers.

Mather-type dense plasma focus as a new optical pump for short-wavelength high-power lasers

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

Fanning, J.J.; Kim, K.

For the first time, a Mather-type dense plasma focus (MDPF) is successfully operated as an optical pump for lasers. Rhodamine-6G dye is optically pumped using the MDPF fluorescence, producing a laser pulse 1 ..mu..s in duration and more than 50 kW in output power. No optimization is attempted either of the laser cavity or of the lasing medium concentration and volume. A brief description of the experimental setup is presented, along with a summary and discussion of the results. The advantages of the present optical pump source and, in particular, their implications for the pumping of short-wavelength lasers are discussed.

Improving the Performance of Gold-Nanoparticle-Doped Solid-State Dye Laser Using Thermal Conversion Effect

NASA Astrophysics Data System (ADS)

An, N. T. M.; Lien, N. T. H.; Hoang, N. D.; Hoa, D. Q.

2018-04-01

Energy transfer between spherical gold nanoparticles with size of more than 15 nm and molecules of organic dye 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4 H-pyran (DCM) has been studied. Such radiative energy transfer led to high local temperature, giving rise to a bleaching effect that resulted in rapid degradation of the laser medium. Gold nanoparticles were dispersed at concentrations from 5 × 109 particles/mL to 5 × 1010 particles/mL in DCM polymethylmethacrylate polymer using a radical polymerization process with 2,2'-azobis(isobutyronitrile) (AIBN) as initiator. Using the fast thermoelectric cooling method, the laser medium stability was significantly improved. The output stability of a distributed feedback dye laser pumped by second-harmonic generation from a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser was investigated. Moreover, bidirectional energy transfer between gold nanoparticles and dye molecules was observed.

Sentinel lymph nodes detection with an imaging system using Patent Blue V dye as fluorescent tracer

NASA Astrophysics Data System (ADS)

Tellier, F.; Steibel, J.; Chabrier, R.; Rodier, J. F.; Pourroy, G.; Poulet, P.

2013-03-01

Sentinel lymph node biopsy is the gold standard to detect metastatic invasion from primary breast cancer. This method can help patients avoid full axillary chain dissection, thereby decreasing the risk of morbidity. We propose an alternative to the traditional isotopic method, to detect and map the sentinel lymph nodes. Indeed, Patent Blue V is the most widely used dye in clinical routine for the visual detection of sentinel lymph nodes. A Recent study has shown the possibility of increasing the fluorescence quantum yield of Patent Blue V, when it is bound to human serum albumin. In this study we present a preclinical fluorescence imaging system to detect sentinel lymph nodes labeled with this fluorescent tracer. The setup is composed of a black and white CCD camera and two laser sources. One excitation source with a laser emitting at 635 nm and a second laser at 785 nm to illuminate the region of interest. The prototype is operated via a laptop. Preliminary experiments permitted to determine the device sensitivity in the μmol.L-1 range as regards the detection of PBV fluorescence signals. We also present a preclinical evaluation performed on Lewis rats, during which the fluorescence imaging setup detected the accumulation and fixation of the fluorescent dye on different nodes through the skin.

Hemangiomas

MedlinePlus

... grow. The flash-lamp pulse dye, pump dye, diode, and sclero-laser are the primary lasers used ... go through several trials of dosing-tapering. The current protocol is to put them on the initial ...

Interface module for transverse energy input to dye laser modules

DOEpatents

English, R.E. Jr.; Johnson, S.A.

1994-10-11

An interface module for transverse energy input to dye laser modules is provided particularly for the purpose of delivering enhancing transverse energy beams in the form of illumination bar to the lasing zone of a dye laser device, in particular to a dye laser amplifier. The preferred interface module includes an optical fiber array having a plurality of optical fibers arrayed in a co-planar fashion with their distal ends receiving coherent laser energy from an enhancing laser source, and their proximal ends delivered into a relay structure. The proximal ends of the optical fibers are arrayed so as to be coplanar and to be aimed generally at a common point. The transverse energy beam array delivered from the optical fiber array is acted upon by an optical element array to produce an illumination bar which has a cross section in the form of a elongated rectangle at the position of the lasing window. The illumination bar is selected to have substantially uniform intensity throughout. 5 figs.

Laser desorption/ionization mass spectrometry of dye-sensitized solar cells: identification of the dye-electrolyte interaction.

PubMed

Ellis, Hanna; Leandri, Valentina; Hagfeldt, Anders; Boschloo, Gerrit; Bergquist, Jonas; Shevchenko, Denys

2015-05-01

Dye-sensitized solar cells (DSCs) have great potential to provide sustainable electricity from sunlight. The photoanode in DSCs consists of a dye-sensitized metal oxide film deposited on a conductive substrate. This configuration makes the photoanode a perfect sample for laser desorption/ionization mass spectrometry (LDI-MS). We applied LDI-MS for the study of molecular interactions between a dye and electrolyte on the surface of a TiO2 photoanode. We found that a dye containing polyoxyethylene groups forms complexes with alkali metal cations from the electrolyte, while a dye substituted with alkoxy groups does not. Guanidinium ion forms adducts with neither of the two dyes. Copyright © 2015 John Wiley & Sons, Ltd.

Organic Lasers: Recent Developments on Materials, Device Geometries, and Fabrication Techniques.

PubMed

Kuehne, Alexander J C; Gather, Malte C

2016-11-09

Organic dyes have been used as gain medium for lasers since the 1960s, long before the advent of today's organic electronic devices. Organic gain materials are highly attractive for lasing due to their chemical tunability and large stimulated emission cross section. While the traditional dye laser has been largely replaced by solid-state lasers, a number of new and miniaturized organic lasers have emerged that hold great potential for lab-on-chip applications, biointegration, low-cost sensing and related areas, which benefit from the unique properties of organic gain materials. On the fundamental level, these include high exciton binding energy, low refractive index (compared to inorganic semiconductors), and ease of spectral and chemical tuning. On a technological level, mechanical flexibility and compatibility with simple processing techniques such as printing, roll-to-roll, self-assembly, and soft-lithography are most relevant. Here, the authors provide a comprehensive review of the developments in the field over the past decade, discussing recent advances in organic gain materials, which are today often based on solid-state organic semiconductors, as well as optical feedback structures, and device fabrication. Recent efforts toward continuous wave operation and electrical pumping of solid-state organic lasers are reviewed, and new device concepts and emerging applications are summarized.

Scanning fluorescence detector for high-throughput DNA genotyping

NASA Astrophysics Data System (ADS)

Rusch, Terry L.; Petsinger, Jeremy; Christensen, Carl; Vaske, David A.; Brumley, Robert L., Jr.; Luckey, John A.; Weber, James L.

1996-04-01

A new scanning fluorescence detector (SCAFUD) was developed for high-throughput genotyping of short tandem repeat polymorphisms (STRPs). Fluorescent dyes are incorporated into relatively short DNA fragments via polymerase chain reaction (PCR) and are separated by electrophoresis in short, wide polyacrylamide gels (144 lanes with well to read distances of 14 cm). Excitation light from an argon laser with primary lines at 488 and 514 nm is introduced into the gel through a fiber optic cable, dichroic mirror, and 40X microscope objective. Emitted fluorescent light is collected confocally through a second fiber. The confocal head is translated across the bottom of the gel at 0.5 Hz. The detection unit utilizes dichroic mirrors and band pass filters to direct light with 10 - 20 nm bandwidths to four photomultiplier tubes (PMTs). PMT signals are independently amplified with variable gain and then sampled at a rate of 2500 points per scan using a computer based A/D board. LabView software (National Instruments) is used for instrument operation. Currently, three fluorescent dyes (Fam, Hex and Rox) are simultaneously detected with peak detection wavelengths of 543, 567, and 613 nm, respectively. The detection limit for fluorescein-labeled primers is about 100 attomoles. Planned SCAFUD upgrades include rearrangement of laser head geometry, use of additional excitation lasers for simultaneous detection of more dyes, and the use of detector arrays instead of individual PMTs. Extensive software has been written for automatic analysis of SCAFUD images. The software enables background subtraction, band identification, multiple- dye signal resolution, lane finding, band sizing and allele calling. Whole genome screens are currently underway to search for loci influencing such complex diseases as diabetes, asthma, and hypertension. Seven production SCAFUDs are currently in operation. Genotyping output for the coming year is projected to be about one million total genotypes (DNA samples X polymorphic markers) at a total cost of

Organic Solid-State Tri-Wavelength Lasing from Holographic Polymer-Dispersed Liquid Crystal and a Distributed Feedback Laser with a Doped Laser Dye and a Semiconducting Polymer Film.

PubMed

Liu, Minghuan; Liu, Yonggang; Peng, Zenghui; Wang, Shaoxin; Wang, Qidong; Mu, Quanquan; Cao, Zhaoliang; Xuan, Li

2017-05-07

Organic solid-state tri-wavelength lasing was demonstrated from dye-doped holographic polymer-dispersed liquid crystal (HPDLC) distributed feedback (DFB) laser with semiconducting polymer poly[-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene-vinylene] (MEH-PPV) and laser dye [4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran] (DCM) by a one-step holography technique, which centered at 605.5 nm, 611.9 nm, and 671.1 nm. The temperature-dependence tuning range for the tri-wavelength dye-doped HPDLC DFB laser was as high as 8 nm. The lasing emission from the 9th order HPDLC DFB laser with MEH-PPV as active medium was also investigated, which showed excellent s-polarization characterization. The diffraction order is 9th and 8th for the dual-wavelength lasing with DCM as the active medium. The results of this work provide a method for constructing the compact and cost-effective all solid-state smart laser systems, which may find application in scientific and applied research where multi-wavelength radiation is required.

QUANTITATIVE DETECTION OF ENVIRONMENTALLY IMPORTANT DYES USING DIODE LASER/FIBER-OPTIC RAMAN

EPA Science Inventory

A compact diode laser/fiber-optic Raman spectrometer is used for quantitative detection of environmentally important dyes. This system is based on diode laser excitation at 782 mm, fiber optic probe technology, an imaging spectrometer, and state-of-the-art scientific CCD camera. ...

Fractional Resurfacing Aiding Photodynamic Therapy of a Recalcitrant Plantar Verruca

PubMed Central

Pope, Amy

2008-01-01

Fractional resurfacing has become a very popular laser modality in recent years, and photodynamic therapy (PDT) has become a mainstay of many practices treating a wide array of clinical entities. In this case report, we describe a recalcitrant verrucous lesion on the foot that is unresponsive to cryotherapy, pulsed dye laser, and pulsed dye laser with PDT. The lesion did, however, respond very well to the use of a fractional laser to enhance the penetration of the PDT photosensitizer and then responded to pulsed dye laser with PDT. Fractional resurfacing prior to PDT may be a novel dermatologic treatment approach, making PDT an even better treatment option in the future. PMID:21103307

High Power Dye Lasers

DTIC Science & Technology

1975-09-30

sphere is greatly reduced when compared to the axial flow dye cell. This is because the focusing optics can only direct light from a limited angle into...Distribution in Flashlamp . . . „ [ [ TTIH Flashlamp Cooling and Thermal Limits [ [ [ ii~ik Optical Characteristics ’,,: •*••••••••••• il-ib...Tracing Program e Dye Pumping System Laser Tests ! 1 i * * TTT’I Laser Output Fall Off !!!.’!!!" ’ TTT’H Single Shot Optical Distortion TTT’I

Multipurpose Fiber Injected-micro-spherical LIDAR System

NASA Technical Reports Server (NTRS)

Abdelayem, Hossin; Jamison, Tracee

2005-01-01

A technological revolution is occurring in the field of fiber lasers. Over the past two years, the level of power has increased from approx. 100 watts to nearly 1 kilowatt. We are developing a novel fiber laser system, which is a satellite-based LIDAR transmitter of multi-lines. The system is made of a hollow fiber filled with micro-spheres doped with lasing materials. Each sphere has its inherent optical cavity, which makes the system a cavity free and in the same time, emits multi-laser lines for simultaneous multi-task operations. The system is also rugged, compact, lightweight, and durable. Our earlier studies on micro-spheres doped with different laser dyes demonstrated the emission of extremely fine laser lines of less than 3 A line-width, which are of interest for spectroscopic applications, sensing, imaging, and optical communications. Individual dye-doped micro-spheres demonstrated a lasing resonance peaks phenomenon in their fluorescence spectra of linear and nonlinear features that do not exist in the bulk dye solutions. Each individual micro-sphere acts as a laser system with inherent cavity, where the fluorescence line suffers multiple internal reflections within the micro-sphere and gains enough energy to become a laser line. Such resonance peaks are dependent on the sphere's morphology, size, shape, and its refractive index. These resonance peaks are named structural resonance, whispering modes or whispering gallery modes, creeping waves, circumferential waves, surfaces modes, and virtual modes. All of these names refer to the same phenomenon of morphology dependent resonance (MDR), which has already been described and predicted precisely by electromagnetic theory and Lorentz-Mie theory since 1908. The resonance peaks become more obvious when the particle size approaches and exceeds the wavelength of the laser used and the relative index of the particle is greater than that of the surrounding medium. Additional information is included in the original extended abstract.

Measuring the Dispersion Curve of a PMMA-Fibre Optic Cable Using a Dye Laser

ERIC Educational Resources Information Center

Zorba, Serkan; Farah, Constantine; Pant, Ravi

2010-01-01

An advanced undergraduate laboratory experiment is outlined which uses a dye laser to map out the chromatic dispersion curve of a polymethyl methacrylate (PMMA) optical fibre. Seven different wavelengths across the visible spectrum are employed using five different dyes. The light pulse is split into two pulses, one to a nearby photodetector and…

Ultrafast Laser Techniques

DTIC Science & Technology

1991-06-05

2 Prism Dye Amplifiers .................................................................................. 2 Axicon...carried out under this project. PRISM DYE AMPLIFIERS A first effort was devoted to setting up an amplifier system for the output of a short pulse dye laser...For amplification up to pulse energies of approximately 500 p.J/pulse we chose three stages of prism amplifier cells, with diameters of 1 m, 3 mm

In vitro study of bactericidal effect of low-level laser therapy in the presence of photosensitizer on cariogenic bacteria

NASA Astrophysics Data System (ADS)

Zanin, Iriana C. J.; Brugnera, Aldo, Jr.; Goncalves, Reginaldo B.

2002-06-01

The aim of this in vitro study was to determine whether low-level laser light in the presence of a photosensitizer could kill Streptococcus mutans and Streptococcus sobrinus. Suspensions of these microorganisms were exposed to a gallium-aluminium-arsenide laser light (660 nm) in the presence of photosensitizer toluidine blue O. Viable microorganisms were counted on brain heart agar plates after incubation at 37 degree(s)C in partial atmosphere of 10% CO2 for 48 hours. Their exposure to the laser light in the absence of the dye or the dye in the absence of the laser light presented no significant effect on the viability of the microorganisms. However, a decrease in the number of viable microorganisms was only verified when they were exposed to both the laser light and the dye at the same time. Their total growth inhibition was achieved with a dye concentration of 100 mg/mL and a light energy density of 28.8 J/cm2, after being exposed to laser light for 900 seconds. In conclusion, these results imply that these bacteria can be killed by low-power laser light in the presence of the photosensitizer.

Passive mode locking of a Nd:YAG laser with a thin gelatine-film saturable absorber containing organic-dye J-aggregates

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

Avdeeva, V I; Shapiro, Boris I; Kuch'yanov, Aleksandr S

2003-06-30

Ultrashort pulses of duration {approx}13 ps are first obtained in a passively mode-locked Nd:YAG laser with a negative feedback using a thin gelatine-film saturable absorber containing organic-dye J-aggregates. (control of laser radiation parameters)

Third-order nonlinear optical properties of acid green 25 dye by Z-scan method

NASA Astrophysics Data System (ADS)

Jeyaram, S.; Geethakrishnan, T.

2017-03-01

Third-order nonlinear optical (NLO) properties of aqueous solutions of an anthraquinone dye (Acid green 25 dye, color index: 61570) have been studied by Z-scan method with a 5 mW continuous wave (CW) diode laser operating at 635 nm. The nonlinear refractive index (n2) and the absorption coefficient (β) have been evaluated respectively from the closed and open aperture Z-scan data and the values of these parameters are found to increase with increase in concentration of the dye solution. The negative sign of the observed nonlinear refractive index (n2) indicates that the aqueous solution of acid green 25 dye exhibits self-defocusing type optical nonlinearity. The mechanism of the observed nonlinear absorption (NLA) and nonlinear refraction (NLR) is attributed respectively to reverse saturable absorption (RSA) and thermal nonlinear effects. The magnitudes of n2 and β are found to be of the order of 10-7 cm2/W and 10-3 cm/W respectively. With these experimental results, the authors suggest that acid green 25 dye may have potential applications in nonlinear optics.

Pulsed dye laser application in ablation of vascular ectasias of the larynx: a preliminary animal study

NASA Astrophysics Data System (ADS)

Woo, Peak; Wang, Zhi; Perrault, Donald F., Jr.; McMillan, Kathleen; Pankratov, Michail M.

1995-05-01

Vascular ectasias (dilatation) and vascular lesions of the larynx are difficult to treat with exciting modalities. Varix (enlarged vessel) of the vocal folds, vocal fold hemorrhage, vascular polyp, hemangioma, intubation or contact granuloma are common problems which disturb voice. Current applications of CO2 laser and cautery often damage the delicate vocal fold cover. The 585 nm dermatologic pulsed dye laser may be an ideal substitute. Two adult canines were examined under anesthesia via microlaryngoscopy technique. Pulsed dye laser (SPTL-1a, Candela Laser Corp., Wayland, MA) energy was delivered via the micromanipulator with the 3.1-mm spot size in single pulses of 6, 8, and 10 Joules/cm2 and applied to the vessels of the vocal folds, epiglottis, and arytenoid cartilage. Endoscopic examination was carried out immediately after the treatment and at 4 weeks postoperatively. The animals were sacrificed at 3 weeks, larynges excised, and whole organ laryngeal section were prepared for histology. Pulsed dye laser thrombosed vessels of the vocal fold using 6 or 8 Joules/cm2. Vascular break and leakage occurred at 10 Joules/cm2. Follow up examination showed excellent vessel obliteration or thrombosis without scarring or injury to the overlying tissues. Histologic examination shows vascular thrombosis without inflammation and fibrosis in the vocal fold cover. Pulsed dye laser may have promise in treatment of vascular lesions of the larynx and upper airway.

Sub-wavelength plasmon laser

DOEpatents

Bora, Mihail; Bond, Tiziana C.

2016-04-19

A plasmonic laser device has resonant nanocavities filled with a gain medium containing an organic dye. The resonant plasmon frequencies of the nanocavities are tuned to align with both the absorption and emission spectra of the dye. Variables in the system include the nature of the dye and the wavelength of its absorption and emission, the wavelength of the pumping radiation, and the resonance frequencies of the nanocavities. In addition the pumping frequency of the dye is selected to be close to the absorption maximum.

Light-driven phase shifter

DOEpatents

Early, James W.

1990-01-01

A light-driven phase shifter is provided for modulating a transmission light beam. A gaseous medium such as argon is provided with electron energy states excited to populate a metastable state. A tunable dye laser is selected with a wavelength effective to deplete the metastable electron state and may be intensity modulated. The dye laser is directed through the gaseous medium to define a first optical path having an index of refraction determined by the gaseous medium having a depleted metastable electron state. A transmission laser beam is also directed through the gaseous medium to define a second optical path at least partially coincident with the first optical path. The intensity of the dye laser beam may then be varied to phase modulate the transmission laser beam.

Simplifications of the RELIEF flow tagging system for laboratory use. [Raman Excitation plus Laser Induced Electronic Fluorescence

NASA Technical Reports Server (NTRS)

Lempert, Walter R.; Zhang, Boying; Miles, Richard B.; Diskin, Glenn

1991-01-01

The use of an O2:He stimulated Raman cell to generate the Stokes beam for the Raman vibrational pumping step of the RELIEF (Raman Excitation plus Laser-Induced Electronic Fluorescence) flow tagging method is reported. Use of the Raman cell rather than a dye laser provides pump and Stokes beams which are automatically frequency matched and temporally and spatially overlapped. The Nd:YAG pump laser is operated multilongitudinal mode, which eliminates the need for injection seeding, resulting in decreased operation complexity and improved stability with respect to acoustic noise. Results are presented for 1st Stokes conversion efficiency and stimulated Brillouin backscattering loss and are compared to the case of pure O2. Scanning CARS measurements of the Q-branch lineshape for both pure O2 and the O2:He mixture are also presented.

Dye laser traveling wave amplifier

NASA Technical Reports Server (NTRS)

Davidson, F.; Hohman, J.

1985-01-01

Injection locking was applied to a cavity-dumped coaxial flashlamp pumped dye laser in an effort to obtain nanosecond duration pulses which have both high energy and narrow-linewidth. In the absence of an injected laser pulse, the cavity-dumped dye laser was capable of generating high energy (approx. 60mJ) nanosecond duration output pulses. These pulses, however, had a fixed center wavelength and were extremely broadband (approx. 6nm FWHM). Experimental investigations were performed to determine if the spectral properties of these outputs could be improved through the use of injection-locking techniques. A parametric study to determine the specific conditions under which the laser could be injection-locked was also carried out. Significant linewidth reduction to 0.0015nm) of the outputs was obtained through injection-locking but only at wavelengths near the peak lasing wavelength of the dye. It was found, however; that by inserting weakly dispersive tuning elements in the laser cavity, these narrow-linewidth outputs could be obtained over a wide (24nm) tuning range. Since the tuning elements had low insertion losses, the tunability of the output was obtained without sacrificing output pulse energy.

Interface module for transverse energy input to dye laser modules

DOEpatents

English, Jr., Ronald E.; Johnson, Steve A.

1994-01-01

An interface module (10) for transverse energy input to dye laser modules is provided particularly for the purpose of delivering enhancing transverse energy beams (36) in the form of illumination bar (54) to the lasing zone (18) of a dye laser device, in particular to a dye laser amplifier (12). The preferred interface module (10) includes an optical fiber array (30) having a plurality of optical fibers (38) arrayed in a co-planar fashion with their distal ends (44) receiving coherent laser energy from an enhancing laser source (46), and their proximal ends (4) delivered into a relay structure (3). The proximal ends (42) of the optical fibers (38) are arrayed so as to be coplanar and to be aimed generally at a common point. The transverse energy beam array (36) delivered from the optical fiber array (30) is acted upon by an optical element array (34) to produce an illumination bar (54) which has a cross section in the form of a elongated rectangle at the position of the lasing window (18). The illumination bar (54) is selected to have substantially uniform intensity throughout.

Thin film DNA-complex-based dye lasers fabricated by immersion and conventional processes

NASA Astrophysics Data System (ADS)

Kawabe, Yutaka; Suzuki, Yuki

2017-08-01

DNA based thin film dye laser is one of promising optical devices for future technology. Laser oscillation and amplified spontaneous emission (ASE) were demonstrated by hemicyanine-doped DNA complex films prepared with `immersion method' as well as those made by a conventional way. In the immersion process, DNA-surfactant complex films were stained by immersion into an acetone solution including the dyes. In this study, three types of hemicyanines were incorporated with both methods, and laser oscillation was achieved with optically induced population grating formed in all of the complex films. The laser threshold values for six cases ranged in 0.07 - 0.18 mJ/cm2 , which was close to the best values made in DNA complex matrices. Continual pumping showed that laser oscillation persisted for 4 - 10 minutes. Immersion process gave superior laser capability especially for output efficiency over the conventional counterparts.

Application of LIF technique for the space- and time-resolved monitoring of pollutant gas decomposition in nonthermal plasma reactors

NASA Astrophysics Data System (ADS)

Mizeraczyk, Jerzy; Ohkubo, Toshikazu; Kanazawa, Seiji; Kocik, Marek

2003-10-01

Laser-induced fluorescence (LIF) technique aided by intensified CCD light signal detection and fast digital image processing is demonstrated to be a useful diagnostic method for in-situ observation of the discharge-induced plasma-chemistry processes responsible for NOx(NO + NO2) decomposition occurring in non-thermal plasma reactors. In this paper a method and results of the LIF measurement of two-dimensional distribution of the ground-state NO molecule density inside a DC positive streamer corona reactor during NO removal from a flue gas simulator [air/NO(up to 300 ppm)] are presented. Either a needle-to-plate or nozzle-to-plate electrode system, having an electrode gap of 30-50 mm was used for generating the corona discharge in the reactor. The LIF monitoring of NO molecules was carried out under the steady-state DC corona discharge condition. The laser-induced fluorescence on the transition NO X2Π(v"=0)<--A2Σ+(v'=0) at λ=226nm was chosen for monitoring ground-state NO molecules in the reactor. This transition was induced by irradiation of the NO molecules with UV laser pulses generated by a laser system consisted of a XeF excimer laser, dye laser and BBO crystal. The laser pulses from the XeF excimer laser (Lambda Physik, Complex 150, λ=351 nm) pumped the dye laser (Lambda Physik, Scanmate) with Coumarin 47 as a dye, which generated the laser beam of a wavelength turned around λ=450 nm. Then, the tuned dye laser beam pumped the BBO crystal in which the second harmonic radiation of a wavelength correspondingly tuned around λ=226 nm was generated. The 226-nm UV laser pulses of energy of 0.8-2 mJ and duration of about 20 ns were transformed into the form of the so-called laser sheet (width of 1 mm, height of 30-50 mm) which passed between the electrodes through the operating gas. The obtained results, presented in the form of images, which illustrated the two-dimensional distributions of NO molecule concentration in the non-thermal reactor, showed that the corona discharge-induced removal of NO molecules occurred not only in the vicinity of the plasma region formed by the corona discharge-induced removal of NO molecules occurred not only in the vicinity of the plasma region formed by the corona streamers and in the downstream region of the reactor but also in the upstream region of the reactor, i.e. before the flue gas simulator has entered the plasma region. This information obtained owing to the LIF technique, is important for the understanding of the plasma-chemistry processes responsible for NOx decomposition in non-thermal plasma reactors and for optimising their performance.

Development of New Laser Protective Dyes

DTIC Science & Technology

1993-07-31

Science’s Phase I research, the feasibility of thermally stabilizing cyanine and squarylium dyes for simulated polycarbonate injection-molding... SQUARYLIUM & CROCONIUM FIUORENE DYE SYNTHESIS SYNTHESIS OF NEW DYES DYE SYNTHESES IENGFICA TION ASYNTHESIS OF SUSSTITUTED DYES EVELOP OH TECHNOLOGIES...region, three dyes were successfully extruded into PETG and/or PC: (a.) the croconium dye SS-1044 (,%max = 834 um in PETG). (b.) the squarylium dye

Laser-activated protein bands for peripheral nerve repair

NASA Astrophysics Data System (ADS)

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

1996-01-01

A 100 micrometer core optical fiber-coupled 75 mW diode laser operating at a wavelength of 800 nm has been used in conjunction with a protein solder to stripe weld severed rat tibial nerves, reducing the long operating time required for microsurgical nerve repair. Welding is produced by selective laser denaturation of the protein based solder which contains the dye indocyanine green. Operating time for laser soldering was 10 plus or minus 5 min. (n equals 24) compared to 23 plus or minus 9 min (n equals 13) for microsuturing. The laser solder technique resulted in patent welds with a tensile strength of 15 plus or minus 5 g, while microsutured nerves had a tensile strength of 40 plus or minus 10 g. Histopathology of the laser soldered nerves, conducted immediately after surgery, displayed solder adhesion to the outer membrane with minimal damage to the inner axons of the nerves. An in vivo study, with a total of fifty-seven adult male wistar rats, compared laser solder repaired tibial nerves to conventional microsuture repair. Twenty-four laser soldered nerves and thirteen sutured nerves were characterized at three months and showed successful regeneration with average compound muscle action potentials (CMAP) of 2.4 plus or minus 0.7 mV and 2.7 plus or minus 0.8 mV respectively. Histopathology of the in vivo study, confirmed the comparable regeneration of axons in laser and suture operated nerves. A faster, less damaging and long lasting laser based anastomotic technique is presented.

Bibliography of Soviet Laser Developments Number 57, January-February 1982.

DTIC Science & Technology

1983-03-02

1 3. Crystal: Miscellaneous ............. 2 4. Semiconductor a. InP..............................................3 b . Pbl...Nd...........................................6 6. Glass: Miscellaneous................................7 B . Liquid Lasers I. Organic Dyes a. Rhodamine...8 b . Miscellaneous Dyes...............................8 2. Incrganic Liquids

Thermally and optically tunable lasing properties from dye-doped holographic polymer dispersed liquid crystal in capillaries

NASA Astrophysics Data System (ADS)

Chen, Maozhou; Dai, Haitao; Wang, Dongshuo; Yang, Yue; Luo, Dan; Zhang, Xiaodong; Liu, Changlong

2018-03-01

In this paper, we investigated tunable lasing properties from the dye-doped holographic polymer dispersed liquid crystal (HPDLC) gratings in capillaries with thermal and optical manners. The thermally tunable range of the lasing from the dye-doped HPDLC reached 8.60 nm with the temperature ranging from 23 °C to 50 °C. The optically tunable laser emission was achieved by doping azo-dye in HPDLC. The transition of azo-dye from trans- to cis-state could induce the reorientation of LC molecules after UV light irradiation, which resulted in the variation of refractive index contrast of LC-rich/polymer-rich layer in HPDLC. Experimentally, the emission wavelength of lasing showed a blueshift (about 2 nm) coupled with decreasing output intensities. The tunable laser based on HPDLC may enable more applications in laser displays, optical communication, biosensors, etc.

Data acquisition, remote control and equipment monitoring for ISOLDE RILIS

NASA Astrophysics Data System (ADS)

Rossel, R. E.; Fedosseev, V. N.; Marsh, B. A.; Richter, D.; Rothe, S.; Wendt, K. D. A.

2013-12-01

With a steadily increasing on-line operation time up to a record 3000 h in the year 2012, the Resonance Ionization Laser Ion Source (RILIS) is one of the key components of the ISOLDE on-line isotope user facility at CERN. Ion beam production using the RILIS is essential for many experiments due to the unmatched combination of ionization efficiency and selectivity. To meet the reliability requirements the RILIS is currently operated in shift duty for continuous maintenance of crucial laser parameters such as wavelength, power, beam position and timing, as well as ensuring swift intervention in case of an equipment malfunction. A recent overhaul of the RILIS included the installation of new pump lasers, commercial dye lasers and a complementary, fully solid-state titanium:sapphire laser system. The framework of the upgrade also required the setup of a network-extended, LabVIEW-based system for data acquisition, remote control and equipment monitoring, to support RILIS operators as well as ISOLDE users. The system contributes to four key aspects of RILIS operation: equipment monitoring, machine protection, automated self-reliance, and collaborative data acquisition. The overall concept, technologies used, implementation status and recent applications during the 2012 on-line operation period will be presented along with a summary of future developments.

[Therapeutic indications for percutaneous laser in patients with vascular malformations and tumors].

PubMed

Labau, D; Cadic, P; Ouroussoff, G; Ligeron, C; Laroche, J-P; Guillot, B; Dereure, O; Quéré, I; Galanaud, J-P

2014-12-01

Lasers are increasingly used to treat vascular abnormalities. Indeed, this technique is non-invasive and allows a specific treatment. The aim of this review is to present some biophysical principles of the lasers, to describe the different sorts of lasers available for treatment in vascular medicine indications. Three principal lasers exist in vascular medicine: the pulsed-dye laser, for the treatment of superficial pink lesions, the NdYAG-KTP laser for purple and bigger lesions, and the NdYAG long pulse laser for even deeper and bigger vascular lesions. In vascular malformations, port wine stains can also be treated by pulsed-dye laser, KTP or NdYAG when they are old and thick. Telangiectasias are good indications for the three sorts of lasers, depending on their depth, color and size. Microcystic lymphatic malformations can be improved by laser treatment. Arterio-venous malformations constitute a contraindication of laser treatment. In vascular tumors, involuted infantile hemangiomas constitute an excellent indication of pulsed-dye laser treatment. Controlled studies are necessary to evaluate and to compare the efficacy of each laser, in order to determine their optimal indications and optimal parameters for each machine. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Conversion of the luminescence of laser dyes in opal matrices to stimulated emission

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

Alimov, O K; Basiev, T T; Orlovskii, Yu V

The luminescence and laser characteristics of a synthetic opal matrix filled with organic dyes are studied upon excitation by nanosecond laser pulses. The appearance of stimulated emission in a partially ordered scattering medium is investigated. It is shown that if the luminescence spectrum of a dye (oxazine-17) is located far outside the photonic bandgap of the opal matrix, stimulated emission along a preferential direction in the (111) plane is observed when pumping exceeds a threshold even without an external optical cavity. The stimulated emission spectrum is considerably narrower than the luminescence spectrum and consists of several narrow lines located withinmore » the dye luminescence band. If the luminescence spectrum of a dye (rhodamine 6G) overlaps with the photonic bandgap of the opal matrix, a different picture is observed. The loss of radiation in the matrix leads to the red shift of the luminescence spectrum, while the stimulated emission as in the case of oxazine-17 lies is observed within the luminescence band. (active media, lasers, and amplifiers)« less

Pulsed dye laser treatment of rosacea using a novel 15 mm diameter treatment beam.

PubMed

Bernstein, Eric F; Schomacker, Kevin; Paranjape, Amit; Jones, Christopher J

2018-04-10

The pulsed-dye laser has been used to treat facial redness and rosacea for decades. Recent advances in dye laser technology enable 50% higher output energies supporting 50% larger treatment areas, and beam-diameters up to 15 mm with clinically-relevant fluences. In this study, we investigate this novel pulsed-dye laser using a 15 mm diameter beam for treatment of rosacea. Twenty subjects with erythemato-telangiectatic rosacea were enrolled in the study. A total of 4 monthly treatments were administered, first treating linear vessels with a 3 × 10 mm elliptical beam, then diffuse redness with a 15-mm diameter circular beam. Blinded assessment of digital, cross-polarized photographs taken 2 months following the last treatment was performed using an 11-point clearance scale. Nineteen subjects completed the study. Blinded reviewers correctly identified baseline photos in 55 out of the total of 57 images (96.5%). The blinded reviewers scored 17 of the 19 subjects with an improvement greater than 40%, and 11 of the 19 subjects greater than 50%. The average improvement was 53.9%. Side effects were limited to mild edema, mild to moderate erythema, and mild to moderate bruising. This study demonstrates that a newly designed pulsed-dye laser having a novel 15-mm diameter treatment beam improves the appearance of rosacea with a favorable safety profile. Lasers Surg. Med. 9999:1-5, 2018. © 2018 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc. © 2018 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc.

High conversion efficiency distributed feedback laser from a dye-doped holographic transmission grating

NASA Astrophysics Data System (ADS)

Liu, Lijuan; Zhang, Guiyang; Kong, Xiaobo; Liu, Yonggang; Xuan, Li

2018-01-01

A high conversion efficiency distributed feedback (DFB) laser from a dye-doped holographic polymer dispersed liquid crystal (HPDLC) transmission grating structure was reported. The alignment polyimide (PI) films were used to control the orientation of the phase separated liquid crystals (LCs) to increase the refractive index difference between the LC and the polymer, so it can provide better light feedback. The lasing wavelength located at 645.8 nm near the maximum of the amplified spontaneous emission (ASE) spectrum with the lowest threshold 0.97 μ J/pulse and the highest conversion efficiency 1.6% was obtained. The laser performance under electric field were also investigated and illustrated. The simple configuration, one-step fabrication organic dye laser shows the potential to realize ultra-low cost plastic lasers.

Near-ultraviolet laser diodes for brilliant ultraviolet fluorophore excitation.

PubMed

Telford, William G

2015-12-01

Although multiple lasers are now standard equipment on most modern flow cytometers, ultraviolet (UV) lasers (325-365 nm) remain an uncommon excitation source for cytometry. Nd:YVO4 frequency-tripled diode pumped solid-state lasers emitting at 355 nm are now the primary means of providing UV excitation on multilaser flow cytometers. Although a number of UV excited fluorochromes are available for flow cytometry, the cost of solid-state UV lasers remains prohibitively high, limiting their use to all but the most sophisticated multilaser instruments. The recent introduction of the brilliant ultraviolet (BUV) series of fluorochromes for cell surface marker detection and their importance in increasing the number of simultaneous parameters for high-dimensional analysis has increased the urgency of including UV sources in cytometer designs; however, these lasers remain expensive. Near-UV laser diodes (NUVLDs), a direct diode laser source emitting in the 370-380 nm range, have been previously validated for flow cytometric analysis of most UV-excited probes, including quantum nanocrystals, the Hoechst dyes, and 4',6-diamidino-2-phenylindole. However, they remain a little-used laser source for cytometry, despite their significantly lower cost. In this study, the ability of NUVLDs to excite the BUV dyes was assessed, along with their compatibility with simultaneous brilliant violet (BV) labeling. A NUVLD emitting at 375 nm was found to excite most of the available BUV dyes at least as well as a UV 355 nm source. This slightly longer wavelength did produce some unwanted excitation of BV dyes, but at sufficiently low levels to require minimal additional compensation. NUVLDs are compact, relatively inexpensive lasers that have higher power levels than the newest generation of small 355 nm lasers. They can, therefore, make a useful, cost-effective substitute for traditional UV lasers in multicolor analysis involving the BUV and BV dyes. Published 2015 Wiley Periodicals Inc. on behalf of ISAC.

The optical biomedical sensors for DNA detection and imaging based on two-photon excited luminescent styryl dyes: phototoxic influence on the DNA

NASA Astrophysics Data System (ADS)

Yashchuk, Valeriy M.; Kudrya, Vladislav Yu.; Losytskyy, Mykhaylo Yu.; Tokar, Valentyna P.; Yarmoluk, Sergiy M.; Dmytruk, Igor M.; Prokopets, Vadym M.; Kovalska, Vladyslava B.; Balanda, Anatoliy O.; Kryvorotenko, Dmytro V.; Ogul'chansky, Tymish Yu.

2007-06-01

The optical absorption, fluorescence and phosphorescence of the novel styryl dyes developed for the fluorescent detection of DNA were investigated. The energy structures of dye molecules as well as spectral manifestations of the dyes aggregate formation and interaction with DNA were studied. The dramatic increase (up to 1000 times) of the fluorescence intensity of dyes in the presence of DNA was observed. The photostability and phototoxic influence on the DNA of several styryl dyes were studied by analyzing absorption, fluorescence and phosphorescence spectra of these dyes and dye-DNA systems. Changes of the optical density value of dye-DNA solutions caused by the visible light irradiation were fixed in the wavelength regions of the DNA absorption and of the dye absorption. Fluorescence emission of dye-DNA complexes upon two-photon excitation (TPE) at wavelength 1064 nm with the 20 ns pulsed YAG: Nd3+ laser and at 840 nm with the 90 fs pulsed Ti:sapphire laser was registered. The values of two-photon absorption cross-sections of dye-DNA complexes were evaluated.

Intensity and absorbed-power distribution in a cylindrical solar-pumped dye laser

NASA Technical Reports Server (NTRS)

Williams, M. D.

1984-01-01

The internal intensity and absorbed-power distribution of a simplified hypothetical dye laser of cylindrical geometry is calculated. Total absorbed power is also calculated and compared with laboratory measurements of lasing-threshold energy deposition in a dye cell to determine the suitability of solar radiation as a pump source or, alternatively, what modifications, if any, are necessary to the hypothetical system for solar pumping.

Fabrication of Ocular Protective Devices against Laser Radiation and Ballistic Fragments for Evaluation in Military Scenarios

DTIC Science & Technology

1992-09-30

19 3.4.5 High Energy Laser ..... .............. .. 20 3.4.6 Solar ..................................... 21 3.4.7 Humidity...57 4.5.6 Solar ...................................... 57 4.5.7 Humidity... . .................. ...o.. ....57 4.5.8 Temperature...coated AO-ET dye 12. Effect of solar exposure on AO-ET dyeD 13. Spectral transmittance molded B-401 dye 14. Visible transmittance of typical two

Low-threshold ablation of enamel and dentin using Nd:YAG laser assisted with chromophore with different pulse shapes

NASA Astrophysics Data System (ADS)

Bonora, Stefano; Benazzato, Paolo; Stefani, Alessandro; Villoresi, Paolo

2004-05-01

Neodimium laser treatment has several drawbacks when used in the hard tissue cutting, because of the low absorption of the dental tissues at its wavelength. This investigation proved that the Nd:YAG radiation is a powerful ablation tool if it is used with the dye assisted method. Several in vitro tests on enamel and dentin were accomplished changing some laser parameters to have different pulse shapes and durations from 125μs up to 1.4ms. The importance of short time high power peaks, typical of crystal lasers, in the ablation process was investigated. The pulse shapes were analyzed by their intensity in space and time profiles. A first set of results found the optimum dye concentration be used in all the following tests. Furthermore the ablation threshold for this technique was found for each different pulse shapes and durations. A low energy ablation method was found to avoid temperature increase and surface cracks formation. In vitro temperature analysis was reported comparing the differences between no dye application laser treatment and with a dye spray applied. A strong reduction of the temperature increase was found in the dye assisted method. A discussion on the general findings and their possible clinical applications is presented.

Investigation of potential of differential absorption Lidar techniques for remote sensing of atmospheric pollutants

NASA Technical Reports Server (NTRS)

Butler, C. F.; Shipley, S. T.; Allen, R. J.

1981-01-01

The NASA multipurpose differential absorption lidar (DIAL) system uses two high conversion efficiency dye lasers which are optically pumped by two frequency-doubled Nd:YAG lasers mounted rigidly on a supporting structure that also contains the transmitter, receiver, and data system. The DIAL system hardware design and data acquisition system are described. Timing diagrams, logic diagrams, and schematics, and the theory of operation of the control electronics are presented. Success in obtaining remote measurements of ozone profiles with an airborne systems is reported and results are analyzed.

Dye-sensitized solar cells using laser processing techniques

NASA Astrophysics Data System (ADS)

Kim, Heungsoo; Pique, Alberto; Kushto, Gary P.; Auyeung, Raymond C. Y.; Lee, S. H.; Arnold, Craig B.; Kafafi, Zakia H.

2004-07-01

Laser processing techniques, such as laser direct-write (LDW) and laser sintering, have been used to deposit mesoporous nanocrystalline TiO2 (nc-TiO2) films for use in dye-sensitized solar cells. LDW enables the fabrication of conformal structures containing metals, ceramics, polymers and composites on rigid and flexible substrates without the use of masks or additional patterning techniques. The transferred material maintains a porous, high surface area structure that is ideally suited for dye-sensitized solar cells. In this experiment, a pulsed UV laser (355nm) is used to forward transfer a paste of commercial TiO2 nanopowder (P25) onto transparent conducting electrodes on flexible polyethyleneterephthalate (PET) and rigid glass substrates. For the cells based on flexible PET substrates, the transferred TiO2 layers were sintered using an in-situ laser to improve electron paths without damaging PET substrates. In this paper, we demonstrate the use of laser processing techniques to produce nc-TiO2 films (~10 μm thickness) on glass for use in dye-sensitized solar cells (Voc = 690 mV, Jsc = 8.7 mA/cm2, ff = 0.67, η = 4.0 % at 100 mW/cm2). This work was supported by the Office of Naval Research.

Direct and comprehensive analysis of dyes based on integrated molecular and structural information via laser desorption laser postionization mass spectrometry.

PubMed

Liu, Rong; Yin, Zhibin; Leng, Yixin; Hang, Wei; Huang, Benli

2018-01-01

Laser desorption laser postionization time-of-flight mass spectrometry (LDPI-TOFMS) was employed for direct analysis and determination of typical basic dyes. It was also used for the analysis and comprehensive understanding of complex materials such as blue ballpoint pen inks. Simultaneous emergences of fragmental and molecular information largely simplify and facilitate unambiguous identification of dyes via variable energy of 266nm postionization laser. More specifically, by optimizing postionization laser energy with the same energy of desorption laser, the structurally significant results show definite differences in the fragmentation patterns, which offer opportunities for discrimination of isomeric species with identical molecular weight. Moreover, relatively high spectra resolution can be acquired without the expense of sensitivity. In contrast to laser desorption/ionization mass spectrometry (LDI-MS), LDPI-MS simultaneously offers valuable molecular information about dyes in traces, solvents and additives about inks, thereby offering direct determination and comprehensive understanding of blue ballpoint inks and giving a high level of confidence to discriminate the complicated evidentiary samples. In addition, direct analysis of the inks not only allows the avoidance of the tedious sample preparation processes, significantly shortening the overall analysis time and improving throughput, but allows minimized sample consumption which is important for rare and precious samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Inversion of the resonance line of Sr/+/ produced by optically pumping Sr atoms

NASA Technical Reports Server (NTRS)

Green, W. R.; Falcone, R. W.

1978-01-01

A description is presented of an experiment which demonstrates the selective production of excited-state ions by an optical absorption from neutrals. An inversion on the resonance line of Sr(+) was produced by laser excitation of a two-electron transition, followed by ionization of one of the excited electrons by the same laser. A pulsed, mode-locked laser operating at 2680 A was used to excite atoms from the Sr ground level. The same laser then ionized the excited atoms. The 2680-A pump beam was generated by frequency doubling the output of a synchronously pumped mode-locked dye laser in a KDP crystal. It is pointed out that the reported results are significant for the construction of vacuum-ultraviolet and X-ray lasers. Many of the proposed methods for making such lasers depend on the selective production of excited-state ions.

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

PubMed

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

1997-01-01

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

LASERS, ACTIVE MEDIA: The aqueous-polyelectrolyte dye solution as an active laser medium

NASA Astrophysics Data System (ADS)

Akimov, A. I.; Saletskii, A. M.

2000-11-01

The spectral, luminescent, and lasing properties of aqueous solutions of a cationic dye rhodamine 6G with additions of anion polyelectrolytes — polyacrylic and polymethacrylic acids — are studied. It is found that the energy and spectral properties of lasing of these solutions depend on the ratio of concentrations of polyelectrolyte and molecules. It is also found that the lasing parameters of aqueous-polyelectrolyte dye solutions can be controlled by changing the structure of the molecular system. The variation in the structure of aqueous-polyelectrolyte dye solutions of rhodamine 6G resulted in an almost five-fold increase in the lasing efficiency compared to that in aqueous dye solutions.

Theoretical studies on a new pattern of laser-driven systems: towards elucidation of direct photo-injection in dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Mishima, Kenji; Yamashita, Koichi

2011-03-01

We theoretically and numerically investigated a new type of analytically solvable laser-driven systems inspired by electron-injection dynamics in dye-sensitized solar cells. The simple analytical expressions were found to be useful for understanding the difference between dye excitation and direct photo-injection occurring between dye molecule and semiconductor nanoparticles. More importantly, we propose a method for discriminating experimentally dye excitation and direct photo-injection by using time-dependent fluorescence. We found that dye excitation shows no significant quantum beat whereas the direct photo-injection shows a significant quantum beat. This work was supported by Funding Program for World-Leading Innovative R&D on Science and Technology (FIRST) ``Development of Organic Photovoltaics toward a Low-Carbon Society,'' Cabinet Office, Japan.

Fluorescence lifetime imaging with near-infrared dyes

NASA Astrophysics Data System (ADS)

Becker, Wolfgang; Shcheslavskiy, Vladislav

2013-02-01

Near-infrared (NIR) dyes are used as fluorescence markers in small-animal imaging and in diffuse optical tomography of the human brain. In these applications it is important to know whether the dyes bind to proteins or other tissue constituents, and whether their fluorescence lifetimes depend on the targets they are bound to. Unfortunately, neither the lasers nor the detectors of commonly used confocal and multiphoton laser scanning microscopes allow for excitation and detection of NIR fluorescence. We therefore upgraded existing confocal TCSPC FLIM systems with NIR lasers and NIR sensitive detectors. In multiphoton systems we used the Ti:Sa laser as a one-photon excitation source in combination with an NIR-sensitive detector in the confocal beam path. We tested a number of NIR dyes in biological tissue. Some of them showed clear lifetime changes depending on the tissue structures they are bound to. We therefore believe that NIR FLIM can deliver supplementary information on the tissue constitution and on local biochemical parameters.

Laser performance of Coumarin 540A dye molecules in polymeric host media with different viscosities: From liquid solution to solid polymer matrix

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

Costela, A.; Garcia-Moreno, I.; Barroso, J.

1998-01-01

Photophysical parameters and lasing properties of Coumarin 540A dye molecules are studied in solutions of increasing viscosity, from liquid solutions in 1,4-dioxane to solid solutions in poly(methyl methacrylate). The fluorescence quantum yield and lasing efficiencies decrease as the viscosity of the solution increases, reflecting the strong influence of the rigidity of the medium on the radiative processes. The photodegradation mechanisms acting on the fluorophores are analyzed by following the dependence of laser induced fluorescence and laser output on the number of pump laser pulses. The fluorescence redistribution after pattern photobleaching technique is used, and Fick{close_quote}s second law is applied tomore » study the diffusion of dye molecules in the highly viscous polymer solutions. The diffusion coefficients of the dye molecules as a function of the increased viscosity of the medium are determined. {copyright} {ital 1998 American Institute of Physics.}« less

An Ambipolar BODIPY Derivative for a White Exciplex OLED and Cholesteric Liquid Crystal Laser toward Multifunctional Devices.

PubMed

Chapran, Marian; Angioni, Enrico; Findlay, Neil J; Breig, Benjamin; Cherpak, Vladyslav; Stakhira, Pavlo; Tuttle, Tell; Volyniuk, Dmytro; Grazulevicius, Juozas V; Nastishin, Yuriy A; Lavrentovich, Oleg D; Skabara, Peter J

2017-02-08

A new interface engineering method is demonstrated for the preparation of an efficient white organic light-emitting diode (WOLED) by embedding an ultrathin layer of the novel ambipolar red emissive compound 4,4-difluoro-2,6-di(4-hexylthiopen-2-yl)-1,3,5,7,8-pentamethyl-4-bora-3a,4a-diaza-s-indacene (bThBODIPY) in the exciplex formation region. The compound shows a hole and electron mobility of 3.3 × 10 -4 and 2 × 10 -4 cm 2 V -1 s -1 , respectively, at electric fields higher than 5.3 × 10 5 V cm -1 . The resulting WOLED exhibited a maximum luminance of 6579 cd m -2 with CIE 1931 color coordinates (0.39; 0.35). The bThBODIPY dye is also demonstrated to be an effective laser dye for a cholesteric liquid crystal (ChLC) laser. New construction of the ChLC laser, by which a flat capillary with an optically isotropic dye solution is sandwiched between two dye-free ChLC cells, provides photonic lasing at a wavelength well matched with that of a dye-doped planar ChLC cell.

Comparison of different laser systems in the treatment of hypertrophic and atrophic scars and keloids

NASA Astrophysics Data System (ADS)

Scharschmidt, D.; Algermissen, Bernd; Willms-Jones, J.-C.; Philipp, Carsten M.; Berlien, Hans-Peter

1997-12-01

Different laser systems and techniques are used for the treatment of hypertrophic scars, keloids and acne scars. Significant criteria in selecting a suitable laser system are the scar's vascularization, age and diameter. Flashlamp- pumped dye-lasers, CO2-lasers with scanner, Argon and Nd:YAG-lasers are used. Telangiectatic scars respond well to argon lasers, erythematous scars and keloids to dye-laser treatment. Using interstitial Nd:YAG-laser vaporization, scars with a cross-section over 1 cm can generally be reduced. For the treatment of atrophic and acne scars good cosmetic results are achieved with a CO2-laser/scanner system, which allows a precise ablation of the upper dermis with low risk of side-effects.

Flow and thermal characteristics of high Reynolds number (2800-17,000) dye cell: simulation and experiment.

PubMed

Mishra, G K; Kumar, Abhay; Prakash, O; Biswal, R; Dixit, S K; Nakhe, S V

2015-04-10

This paper presents computational and experimental studies on wavelength/frequency fluctuation characteristics of a high pulse repetition rate (18 kHz) dye laser pumped by a frequency-doubled Nd:YAG laser (532 nm). The temperature gradient in the dye solution is found to be responsible for wavelength fluctuations of the dye laser at low flow rates (2800

Variations in thermo-optical properties of neutral red dye with laser ablated gold nanoparticles

NASA Astrophysics Data System (ADS)

Prakash, Anitha; Pathrose, Bini P.; Mathew, S.; Nampoori, V. P. N.; Radhakrishnan, P.; Mujeeb, A.

2018-05-01

We have investigated the thermal and optical properties of neutral red dye incorporated with different weight percentage of gold nanoparticles prepared by laser ablation method. Optical absorption studies confirmed the production of spherical nanoparticles and also the interactions of the dye molecules with gold nanoparticles. The quenching of fluorescence and the reduction in the lifetime of gold incorporated samples were observed and was due to the non-radiative energy transfer between the dye molecules and gold nanoparticles. Dual beam thermal lens technique has been employed to measure the heat diffusion in neutral red with various weight percentage of gold nano sol dispersed in ethanol. The significant outcome of the experiment is that, the overall heat diffusion is slower in the presence of gold nano sol compared to that of dye alone sample. Brownian motion is suggested to be the main mechanism of heat transfer under the present conditions. The thermal diffusivity variations of samples with respect to different excitation power of laser were also studied.

Intracavity absorption with a continuous wave dye laser - Quantification for a narrowband absorber

NASA Technical Reports Server (NTRS)

Brobst, William D.; Allen, John E., Jr.

1987-01-01

An experimental investigation of the dependence of intracavity absorption on factors including transition strength, concentration, absorber path length, and pump power is presented for a CW dye laser with a narrow-band absorber (NO2). A Beer-Lambert type relationship is found over a small but useful range of these parameters. Quantitative measurement of intracavity absorption from the dye laser spectral profiles showed enhancements up to 12,000 (for pump powers near lasing threshold) when compared to extracavity measurements. The definition of an intracavity absorption coefficient allowed the determination of accurate transition strength ratios, demonstrating the reliability of the method.

Fiber optic laser rod

DOEpatents

Erickson, G.F.

1988-04-13

A laser rod is formed from a plurality of optical fibers, each forming an individual laser. Synchronization of the individual fiber lasers is obtained by evanescent wave coupling between adjacent optical fiber cores. The fiber cores are dye-doped and spaced at a distance appropriate for evanescent wave coupling at the wavelength of the selected dye. An interstitial material having an index of refraction lower than that of the fiber core provides the optical isolation for effective lasing action while maintaining the cores at the appropriate coupling distance. 2 figs.

Diode pumped solid-state laser oscillators for spectroscopic applications

NASA Technical Reports Server (NTRS)

Byer, R. L.; Basu, S.; Fan, T. Y.; Kozlovsky, W. J.; Nabors, C. D.; Nilsson, A.; Huber, G.

1987-01-01

The rapid improvement in diode laser pump sources has led to the recent progress in diode laser pumped solid state lasers. To date, electrical efficiencies of greater than 10 percent were demonstrated. As diode laser costs decrease with increased production volume, diode laser and diode laser array pumped solid state lasers will replace the traditional flashlamp pumped Nd:YAG laser sources. The use of laser diode array pumping of slab geometry lasers will allow efficient, high peak and average power solid state laser sources to be developed. Perhaps the greatest impact of diode laser pumped solid state lasers will be in spectroscopic applications of miniature, monolithic devices. Single-stripe diode-pumped operation of a continuous-wave 946 nm Nd:YAG laser with less than 10 m/w threshold was demonstrated. A slope efficiency of 16 percent near threshold was shown with a projected slope efficiency well above a threshold of 34 percent based on results under Rhodamine 6G dye-laser pumping. Nonlinear crystals for second-harmonic generation of this source were evaluated. The KNbO3 and periodically poled LiNbO3 appear to be the most promising.

Self-assembled dye-doped polymer microspheres as whispering gallery mode lasers

NASA Astrophysics Data System (ADS)

Chen, Xiaogang; Sun, Hongyi; Yang, Hongqin; Wu, Xiang; Xie, Shusen

2016-10-01

Microlasers based on high-Q whispering-gallery-mode (WGM) resonances are promising low-threshold laser sources for bio-sensing and imaging applications. In this talk, we demonstrate a cost effective approach to obtain size-controllable polymer microspheres, which can be served as good WGM microcavities. By injecting SU-8 solution into low-refractiveindex UV polymer, self-assembled spherical droplet with smooth surface can be created inside the elastic medium and then solidified by UV exposure. The size of the microspheres can be tuned from several to hundreds of microns. WGM Lasing has been achieved by optically pumping the dye-doped microspheres with ns lasers. Experimental results show that the microsphere lasers have high quality factors and low lasing thresholds. The self-assembled dye-doped polymer microspheres would provide an excellent platform for the micro-laser sources in on-chip biosensing and imaging systems.

Random lasing from dye-doped negative liquid crystals using ZnO nanoparticles as tunable scatters

NASA Astrophysics Data System (ADS)

Li, Long-Wu; Shang, Zhen-Zhen; Deng, Luogen

2016-09-01

This work demonstrates the realization of a lasing in scattering media, which contains dispersive solution of ZnO nanoparticles (NPs) and laser dye 4-dicyanomethylene-2-methyle-6-(p-dimethylaminostyryl)-4H-pyran(DCM) in negative liquid crystals (LCs) that was injected into a cell. The lasing intensity of the dye-doped negative LC laser can be tuned from low to high if the NPs concentration is increased. The tunability of the laser is attributable to the clusters-sensitive feature in effective refractive index of the negative LCs. Such a tunable negative liquid crystal laser can be used in the fabrication of new optical sources, optical communication, and liquid crystal laser displays. Project supported by the Doctoral Science Research Start-up Funding of Guizhou Normal University, China (Grant No. 11904-0514162) and the National Natural Science Foundation of China (Grant No. 11474021).

Photophysics of Laser Dye-Doped Polymer Membranes for Laser-Induced Fluorescence Photogrammetry

NASA Technical Reports Server (NTRS)

Dorrington, Adrian A.; Jones, Thomas W.; Danehy, Paul M.

2004-01-01

Laser-induced fluorescence target generation in dye-doped polymer films has recently been introduced as a promising alternative to more traditional photogrammetric targeting techniques for surface profiling of highly transparent or reflective membrane structures. We investigate the photophysics of these dye-doped polymers to help determine their long-term durability and suitability for laser-induced fluorescence photogrammetric targeting. These investigations included experimental analysis of the fluorescence emission pattern, spectral content, temporal lifetime, linearity, and half-life. Results are presented that reveal an emission pattern wider than normal Lambertian diffuse surface scatter, a fluorescence time constant of 6.6 ns, a pump saturation level of approximately 20 micro J/mm(exp 2), and a useful lifetime of more than 300,000 measurements. Furthermore, two demonstrations of photogrammetric measurements by laser-induced fluorescence targeting are presented, showing agreement between photogrammetric and physically measured dimensions within the measurement scatter of 100 micron.

Characterization of Fluorescent Polystyrene Microspheres for Advanced Flow Diagnostics

NASA Technical Reports Server (NTRS)

Maisto, Pietro M. F.; Lowe, K. Todd; Byun, Guibo; Simpson, Roger; Vercamp, Max; Danley, Jason E.; Koh, Brian; Tiemsin, Pacita; Danehy, Paul M.; Wohl, Christopher J.

2013-01-01

Fluorescent dye-doped polystyrene latex microspheres (PSLs) are being developed for velocimetry and scalar measurements in variable property flows. Two organic dyes, Rhodamine B (RhB) and dichlorofluorescence (DCF), are examined to assess laser-induced fluorescence (LIF) properties for flow imaging applications and single-shot temperature measurements. A major interest in the current research is the application of safe dyes, thus DCF is of particular interest, while RhB is used as a benchmark. Success is demonstrated for single-point laser Doppler velocimetry (LDV) and also imaging fluorescence, excited via a continuous wave 2 W laser beam, for exposures down to 10 ms. In contrast, when exciting with a pulsed Nd:YAG laser at 200 mJ/pulse, no fluorescence was detected, even when integrating tens of pulses. We show that this is due to saturation of the LIF signal at relatively low excitation intensities, 4-5 orders of magnitude lower than the pulsed laser intensity. A two-band LIF technique is applied in a heated jet, indicating that the technique effectively removes interfering inputs such as particle diameter variation. Temperature measurement uncertainties are estimated based upon the variance measured for the two-band LIF intensity ratio and the achievable dye temperature sensitivity, indicating that particles developed to date may provide about +/-12.5 C precision, while future improvements in dye temperature sensitivity and signal quality may enable single-shot temperature measurements with sub-degree precision.

The pulsed dye laser versus the Q-switched Nd:YAG laser in laser-induced shock-wave lithotripsy.

PubMed

Thomas, S; Pensel, J; Engelhardt, R; Meyer, W; Hofstetter, A G

1988-01-01

To date, there are two fairly well-established alternatives for laser-induced shock-wave lithotripsy in clinical practice. The Q-switched Nd:YAG laser is distinguished by the high-stone selectivity of its coupler systems. The necessity of a coupler system and its fairly small conversion rate of light energy into mechanical energy present serious drawbacks. Furthermore, the minimal outer diameter of the transmission system is 1.8 mm. The pulsed-dye laser can be used with a highly flexible and uncomplicated 200-micron fiber. However, the laser system itself is more complicated than the Q-switched Nd:YAG laser and requires a great deal of maintenance. Biological evaluation of damage caused by direct irradiation shows that both laser systems produce minor damage of different degrees. YAG laser lithotripsy with the optomechanical coupler was assessed in 31 patients with ureteral calculi. The instability and limited effectiveness of the fiber application system necessitated auxiliary lithotripsy methods in 14 cases. Dye-laser lithotripsy is currently being tested in clinical application. Further development, such as systems for blind application or electronic feedback mechanisms to limit adverse tissue effects, have yet to be optimized. Nevertheless, laser-induced shock-wave lithotripsy has the potential to become a standard procedure in the endourologic management of stone disease.

Monolithic dye laser amplifier

DOEpatents

Kuklo, T.C.

1993-03-30

A fluid dye laser amplifier for amplifying a dye beam by pump beams has a channel structure defining a channel through which a laseable fluid flows and the dye and pump beams pass transversely to one another through a lasing region. The channel structure is formed with two pairs of mutually spaced-apart and mutually confronting glass windows, which are interlocked and make surface-contacts with one another and surround the lasing region. One of the glass window pairs passes the dye beam and the other passes the pump beams therethrough and through the lasing region. Where these glass window pieces make surface-contacts, glue is used to join the pieces together to form a monolithic structure so as to prevent the dye in the fluid passing through the channel from entering the space between the mutually contacting glass window pieces.

Monolithic dye laser amplifier

DOEpatents

Kuklo, Thomas C.

1993-01-01

A fluid dye laser amplifier for amplifying a dye beam by pump beams has a channel structure defining a channel through which a laseable fluid flows and the dye and pump beams pass transversely to one another through a lasing region. The channel structure is formed with two pairs of mutually spaced-apart and mutually confronting glass windows, which are interlocked and make surface-contacts with one another and surround the lasing region. One of the glass window pairs passes the dye beam and the other passes the pump beams therethrough and through the lasing region. Where these glass window pieces make surface-contacts, glue is used to join the pieces together to form a monolithic structure so as to prevent the dye in the fluid passing through the channel from entering the space between the mutually contacting glass window pieces.

Master dye laser oscillator including a specific grating assembly for use therein

DOEpatents

Davin, James M.

1992-01-01

A dye laser oscillator for producing a tuned dye beam is disclosed herein and includes, among other components, a beam output coupling assembly, a dye cell assembly, a beam expander assembly, an etalon assembly, and a grating assembly. Each of three assemblies is vertically supported from a horizontal base so as to be readily removable from the base without interference from or interfering with the other assemblies. The particular grating assembly disclosed is specifically designed for proper optical alignment with the intended path of the dye beam to be produced and for accurate pivotal movement relative to the beam path in order to function as a coarse tuning mechanism in the production of the ultimately tuned beam.

Master dye laser oscillator including a specific grating assembly for use therein

DOEpatents

Davin, J.M.

1992-09-01

A dye laser oscillator for producing a tuned dye beam is disclosed herein and includes, among other components, a beam output coupling assembly, a dye cell assembly, a beam expander assembly, an etalon assembly, and a grating assembly. Each of three assemblies is vertically supported from a horizontal base so as to be readily removable from the base without interference from or interfering with the other assemblies. The particular grating assembly disclosed is specifically designed for proper optical alignment with the intended path of the dye beam to be produced and for accurate pivotal movement relative to the beam path in order to function as a coarse tuning mechanism in the production of the ultimately tuned beam. 5 figs.

Studies of third-order optical nonlinearities and optical limiting properties of azo dyes.

PubMed

Gayathri, C; Ramalingam, A

2008-03-01

In order to protect optical sensors and human eyes from debilitating laser effects, the intensity of the incoming laser light has to be opportunely reduced. Here, we report our results on the third-order optical nonlinearity and optical limiting properties of three azo dyes exposed to a 532nm continuous wave laser. We have observed low power optical limiting based on nonlinear refraction in our samples.

Photophysical parameters and laser performance of 3-(4‧-dimethylaminophenyl)-1-(2-furanyl)prop-2-en-1-one (DMAFP): A new laser dye

NASA Astrophysics Data System (ADS)

El-Daly, S. A.; Gaber, M.; El-Sayed, Y. S.

2009-09-01

The spectral properties such as singlet absorption, molar absorptivity, emission spectra, fluorescence quantum yield and excited state lifetime of 3-(4'-dimethylaminophenyl)-1-(2-furanyl)prop-2-en-1-one (DMAFP) have been determined in different solvents. DMAFP dye exhibits a large red shift in both electronic absorption and emission spectra as the solvent polarity increases, indicating a large change in the dipole moment of molecules upon excitation. A crystalline solid of DMAFP gives an excimer like emission at 566 nm due to the excitation of molecular aggregates. This is expected from the idealized crystal structure of the dye that belongs to the B-type class of Steven's classification. The ground and excited state protonation constants of DMAFP are calculated and amounted to 1.71 and 8.3, respectively. DMAFP acts as a good laser dye upon pumping with nitrogen laser ( λex=337.1 nm) in chloroform, methylene chloride and dioxane and gives laser emission in the range 460-590 nm. The laser parameters such as the tuning range, gain coefficient ( α), emission cross section ( σ e) and half-life energy ( E1/2) are calculated. The photoreactivity and net photochemical quantum yield of DMAFP in chloromethane solvents are also studied.

Combined pulsed dye and CO2 lasers in the treatment of angiolymphoid hyperplasia with eosinophilia.

PubMed

Sagi, Lior; Halachmi, Shlomit; Levi, Assi; Amitai, Dan Ben; Enk, Claes D; Lapidoth, Moshe

2016-08-01

Angiolymphoid hyperplasia with eosinophilia (ALHE) is an uncommon dermatosis of unknown etiology that manifests as characteristic red nodules and papules with a predilection for the scalp and periauricular region. Treatment is required for both esthetic and functional reasons, as lesions may ulcerate and bleed. Many treatment approaches have been reported, including excision, systemic medical approaches, topical or intralesional therapies, and non-invasive modalities including cryotherapy, electrosurgery, and laser. Treatments have exhibited variable efficacy, and the recurrence rate is 100 %. We report the combination of pulsed dye laser and CO2 laser in the treatment of ALHE in 14 patients. All patients exhibited clinical response after a mean of 2.4 ± 0.4 treatment sessions. The clinical efficacy of the combined treatment, together with its well-tolerated nature, render the use of pulsed dye laser in combination with CO2 laser, a viable treatment for debulking ALHE lesions. Ongoing maintenance treatments are needed to due to the high degree of relapse.

Superradiant laser emission from rhodamine 6G and rhodamine B using a coaxial flashpump.

NASA Technical Reports Server (NTRS)

Mumola, P. B.

1972-01-01

Superradiant laser emission has been observed from ethanol solutions of rhodamine 6G and rhodamine B using a coaxial flashlamp pump. The dependence of input threshold energy on dye concentration is examined. The possibility of exciting other dyes to superradiance is discussed.

Convenient Microscale Synthesis of a Coumarin Laser Dye Analog

ERIC Educational Resources Information Center

Aktoudianakis, Evangelos; Dicks, Andrew P.

2006-01-01

Coumarin (2H-1-benzopyran-2-one) and its derivatives constitute a fascinating class of organic substances that are utilized industrially in areas such as cosmetics, food preservatives, insecticides and fluorescent laser dyes. The product can be synthesized, purified, and characterized within two hours with benefits of microscale reactivity being…

Efficient sintering of nanocrystalline titanium dioxide films for dye solar cells via raster scanning laser

NASA Astrophysics Data System (ADS)

Mincuzzi, Girolamo; Vesce, Luigi; Reale, Andrea; Di Carlo, Aldo; Brown, Thomas M.

2009-09-01

By identifying the right combination of laser parameters, in particular the integrated laser fluence Φ, we fabricated dye solar cells (DSCs) with UV laser-sintered TiO2 films exhibiting a power conversion efficiency η =5.2%, the highest reported for laser-sintered devices. η is dramatically affected by Φ and a clear trend is reported. Significantly, DSCs fabricated by raster scanning the laser beam to sinter the TiO2 films are made as efficient as those with oven-sintered ones. These results, confirmed on three batches of cells, demonstrate the remarkable potential (noncontact, local, low cost, rapid, selective, and scalable) of scanning laser processing applied to DSC technology.

Direct solar-pumped iodine laser amplifier

NASA Technical Reports Server (NTRS)

Han, K. S.

1986-01-01

During this period the parametric studies of the iodine laser oscillator pumped by a Vortek simulator were carried out before amplifier studies. The amplifier studies are postponed to the extended period after completing the parametric studies. In addition, the kinetic modeling of a solar-pumped iodine laser amplifier, and the experimental work for a solar pumped dye laser amplifier are in progress. This report contains three parts: (1) a 10 W CW iodine laser pumped by a Vortek solar simulator; (2) kinetic modeling to predict the time to lasing threshold, lasing time, and energy output of solar-pumped iodine laser; and (3) the study of the dye laser amplifier pumped by a Tamarack solar simulator.

High-repetition-rate, narrow-band dye lasers with water as a solvent for dyes

NASA Astrophysics Data System (ADS)

Ray, Alok K.; Sinha, Sucharita; Kundu, Soumitra; Kumar, Sasi; Nair, Sivagiriyal Karunakaran Sreenivasan; Pal, Tamal; Dasgupta, Kamalesh

2002-03-01

The performance of a copper vapor laser-pumped narrow-band dye laser in oscillator-amplifier configuration with water-based binary mixture solvents is described. Although oscillator efficiency in water-surfactant (sodium lauryl sulfate) solvent was comparable with that that employed pure ethanolic solvent, amplifier efficiency was found to be lower. Experiments that were carried out with vertically polarized pump beams and either horizontally or vertically polarized signal beams show that, in case of both the pump and signal having orthogonal polarization (horizontal) and same polarization (vertical), the extraction efficiency for both ethanolic and water-micelle media increased substantially from 15.7% to 18.5% and from 10% to 12.5%, respectively. However, the relative difference remained nearly the same, indicating that a slower orientational diffusion of excited dye molecules in a micellar medium is not responsible for a decrease in amplifier efficiency. Amplifier efficiency comparable with that containing ethanolic dye solutions could be obtained with a binary solvent that comprises a mixture of water and about 30% n-propanol. The performances of two efficient dyes, Rhodamine-6G and Kiton Red S, using water-based solvents were studied.

Picosecond transient backward stimulated Raman scattering and pumping of femtosecond dye lasers

NASA Astrophysics Data System (ADS)

Arrivo, Steven M.; Spears, Kenneth G.; Sipior, Jeffrey

1995-02-01

We report studies of transient, backward stimulated, Raman scattering (TBSRS) in solvents with a 10 Hz, 27 ps, 532 nm pump laser. The TBSRS effect was used to create pulses at 545 nm and 630 nm with durations of 2-3 ps and 5-10 μJ of energy. The duration, energy and fluctuations of the Raman pulse were studied as a function of pump energy and focal parameters. A 5 μJ Raman pulse was amplified in either a Raman amplifier or two stage dye amplifier to 1 mJ levels. A 545 nm pulse of 3 ps duration was generated in CCl 4 and was then used to pump a short cavity dye laser (SCDL). The SCDL oscillator and a 5 stage dye amplifier provided a pulse of 700 fs and 400 μJ that was tunable near 590 nm.

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

D'yachkov, Aleksei B; Labozin, Valerii P

The results of experiments on the 510 {yields} 578-nm conversion of high-power radiation from a copper vapour laser (CVL) in a dye cell are presented. The use of the efficient laser dye Pyrromethane 597 (PM-597) made it possible to convert the 120-W CVL radiation (72 W at 510 nm + 48 W at 578 nm) into 102-W radiation at 578 nm, which is equivalent to a conversion efficiency of 85%. Photostability of the dye in various solvents is studied. The photostability (more than 45 GJ mole{sup -1}) of PM-597 in n-heptane is found to be higher than that of Rhmore » 6G in ethanol. (control of laser radiation parameters)« less

Optically sectioned wide-field fluorescence lifetime imaging endoscopy enabled by structured illumination (Conference Presentation)

NASA Astrophysics Data System (ADS)

Hinsdale, Taylor; Malik, Bilal H.; Rico-Jimenez, Jose J.; Jo, Javier A.; Maitland, Kristen C.

2016-03-01

We present a wide-field fluorescence lifetime imaging (FLIM) system with optical sectioning by structured illumination microscopy (SIM). FLIM measurements were made using a time gated ICCD camera in conjunction with a pulsed nitrogen dye laser operating at 450 nm. Intensity images were acquired at multiple time delays from a trigger initiated by a laser pulse to create a wide-field FLIM image, which was then combined with three phase SIM to provide optical sectioning. Such a mechanism has the potential to increase the reliability and accuracy of the FLIM measurements by rejecting background intensity. SIM also provides the opportunity to create volumetric FLIM images with the incorporation of scanning mechanisms for the sample plane. We present multiple embodiments of such a system: one as a free space endoscope and the other as a fiber microendoscope enabled by the introduction of a fiber bundle. Finally, we demonstrate the efficacy of such an imaging system by imaging dyes embedded in a tissue phantom.

Lidar Probing of the Mesosphere: Simultaneous Observations of Sporadic Sodium and Iron Formations, Calcium Ion Layers, Neutral Temperature and Winds

NASA Technical Reports Server (NTRS)

Kane, Timothy J.; Qian, Jun; Scherrer, Daniel R.; Senft, Daniel C.; Pfenninger, W. Matthew; Papen, George C.; Gardner, Chester S.

1992-01-01

Meteoritic ablation in the upper atmosphere is the commonly accepted source of the mesospheric metals between 80 and 105 km. The vertical and temporal behavior of some of these metals can be probed with high accuracy and resolution using resonance fluorescence lidar techniques. Of considerable interest in recent years has been the sporadic and rapid formation of thin, dense enhancements in these metallic layers. Since late Mar. 1991, the UIUC CEDAR lidar system, located at the Urbana Atmospheric Observatory, has been routinely operating at the Fe resonance line of 372 nm in order to probe the mesospheric Fe layer. In Nov. 1991, the capability to investigate mesospheric Ca(+) at the resonance line of 393.4 nm was added. The lidar's eximer-pumped dye laser uses Exciton QUI laser dye dissolved in p-dioxane, which can lase at both the Fe and Ca(+) frequencies. Various aspects of this investigation are discussed.

Laser optogalvanic wavelength calibration with a commercial hollow cathode iron - neon discharge lamp

NASA Technical Reports Server (NTRS)

Zhu, Xinming; Nur, Abdullahi H.; Misra, Prabhakar

1994-01-01

351 optogalvanic transitions have been observed in the 337 - 598 nm wavelength region using an iron - neon hollow cathode discharge lamp and a pulsed tunable dye laser. 223 of these have been identified as transitions associated with neon energy levels. These optogalvanic transitions have allowed, in conjunction with interference fringes recorded concomitantly with an etalon, the calibration of the dye laser wavelength with 0.3/cm accuracy.

Temperature tuning of lasing emission from dye-doped liquid crystal at intermediate twisted phase

NASA Astrophysics Data System (ADS)

Liao, Kuan-Cheng; Lin, Ja-Hon; Jian, Li-Hao; Chen, Yao-Hui; Wu, Jin-Jei

2015-07-01

Temperature tuning of lasing emission from dye-doped cholesteric liquid crystal (CLC) at intermediate twisted phase has been demonstrated in this work. With heavily doping of 42.5% chiral molecules into the nematic liquid crystals, the shifts of photonic bandgap versus temperature is obviously as thermal controlling of the sample below the certain value. By the differential scanning calorimetr measuremet, we demonstrate the phase transition from the CLC to the smectic phase when the temperature is lowered to be about 15°C. Between CLC and smectic phase, the liquid crystal mixtures are operated at intermediate twisted phase that can be used the temperature related refractive mirror. After pump by the Q-switched Nd:YAG laser, the lasing emission from this dye doped LC mixtures has been demonstrated whose emission wavelength can be tuned from 566 to 637 nm with 1.4°C variation.

Third-order nonlinear optical properties of organic azo dyes by using strength of nonlinearity parameter and Z-scan technique

NASA Astrophysics Data System (ADS)

Motiei, H.; Jafari, A.; Naderali, R.

2017-02-01

In this paper, two chemically synthesized organic azo dyes, 2-(2,5-Dichloro-phenyazo)-5,5-dimethyl-cyclohexane-1,3-dione (azo dye (i)) and 5,5-Dimethyl-2-tolylazo-cyclohexane-1,3-dione (azo dye (ii)), have been studied from optical Kerr nonlinearity point of view. These materials were characterized by Ultraviolet-visible spectroscopy. Experiments were performed using a continous wave diode-pumped laser at 532 nm wavelength in three intensities of the laser beam. Nonlinear absorption (β), refractive index (n2) and third-order susceptibility (χ (3)) of dyes, were calculated. Nonlinear absorption coefficient of dyes have been calculated from two methods; 1) using theoretical fits and experimental data in the Z-scan technique, 2) using the strength of nonlinearity curves. The values of β obtained from both of the methods were approximately the same. The results demonstrated that azo dye (ii) displays better nonlinearity and has a lower two-photon absorption threshold than azo dye (i). Calculated parameter related to strength of nonlinearity for azo dye (ii) was higher than azo dye (i), It may be due to presence of methyl in azo dye (ii) instead of chlorine in azo dye (i). Furthermore, The measured values of third order susceptibility of azo dyes were from the order of 10-9 esu . These azo dyes can be suitable candidate for optical switching devices.

[First clinical results using a pulsed dye laser Rhodamine 590 lithotripter in treatment of ureteral calculi].

PubMed

Jichlinski, P; Bonard, M; von Niederhäusern, W; Delacrétaz, G; Rink, K; Lambelet, P; Klohn, M; Bolle, J F; Graber, P

1991-09-01

A collaborative study about a pulsed dye laser Rhodamin 590 was undergone, 2 years ago, between the laser application center of EPFL and both urological departments of the university of Geneva and the university of Lausanne. First clinical results are presented. Ten patients have been treated for various ureteral stones, mainly calcium oxalate stones. Laser fragmentation was successful in seven cases. No serious complication was noted. Fragmentation efficiency seems better with a 320 microns fiber than with a 200 microns fiber.

Spectral evolution of distributed feedback laser of gold nanoparticles doped solid-state dye laser medium

NASA Astrophysics Data System (ADS)

An, N. T. M.; Lien, N. T. H.; Hoang, N. D.; Nghia, N. T.; Hoa, D. Q.

2017-10-01

Characteristics of suppressed relaxation oscillation of a distributed feedback dye laser (DFDL) based on the energy transfer process in a mixture of spherical gold nanoparticles-doped solid-state polymethylmetacrylate dissolved 4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran dye was theoretically and experimentally studied. Single pulse generation regime of the DFDL can be obtained with a suitable gold nanoparticle concentration and ratio of pump power over lasing threshold. Numerical analysis and experimental approach showed that in this regime, the first-pulse laser pulsewidth is rather unchanged while varying the gold nanoparticles concentration in the range of 2.0 × 109-2.0 × 1010 par cm-3. The enhancement of first pulse and the suppression of the secondary pulses by bi-direction energy transfer of spherical gold nanoparticles were experimentally observed.

Logistics of building a laser practice for the treatment of hypertrophic burn scars.

PubMed

Hultman, Charles Scott; Edkins, Renee E; Cairns, Bruce A; Meyer, Anthony A

2013-05-01

Although lasers can improve burn scars, such treatment has not been adopted universally, due to operational challenges starting a practice and the perception that such a program is not financially viable. We report the logistics of building a laser practice for the treatment of hypertrophic burn scars. We analyzed the clinical, operational, and financial components of our laser practice, focusing on treatment of hypertrophic burn scars, using pulsed dye laser, fractional CO2 laser, and intense pulsed light. Cases were performed in an operating room, with anesthesia, after preauthorization. We examined professional charges and collections, case time, variable and indirect expenses, and breakeven volumes. Our practice grew as follows: 2008, 1 case; 2009, 44 cases; 2010, 169 cases; and 2011, 415 cases. Overall collection rate was 32.1%. Expenses incurred by the provider, per 8-hour session, included laser rental/lease ($2375), personnel salaries ($1900), and physician overhead ($808), for a total cost of $5083. Mean charge was $1642 per case; mean collection was $527 per case. Median case time (procedure plus turnover) was 40 minutes. In this model, breakeven volume is 9.7 cases per day; breakeven time is 49.7 minutes. Provider profit margin for 10 cases per day, or 83% capacity utilization, is $187 per day (income - expenses = $5270 - $5083). Despite high costs associated with starting and operating a laser practice for the treatment of hypertrophic burn scars, a sustainable enterprise can be achieved when the provider has accrued enough volume to batch cases over an entire day. Critical to achieving breakeven is preauthorization, controlling overhead, and efficient throughput.

Bonding of human meniscal and articular cartilage with photoactive 1,8-naphthalimide dyes

NASA Astrophysics Data System (ADS)

Judy, Millard M.; Nosir, Hany R.; Jackson, Robert W.; Matthews, James Lester; Lewis, David E.; Utecht, Ronald E.; Yuan, Dongwu

1996-05-01

This study focused on meniscal cartilage repair by using the laser-activated photoactive 1,8- naphthalimide dye N,N'-bis-{6-[2-(2-(2- aminoethoxy)ethoxy)ethoxyethyl]amino-1H-benz (de)isoquinolin-1,3(2H)-dion-2- yl}-1,11-diamino-3,6,9-trioxaundecane. Harvested cadaveric human menisci were debrided and carved into strips 1 mm thick, 10 mm long, and 3 mm wide. Each strip was divided into two flaps, the surface painted with photoactive dye, the painted surfaces overlapped, the sample wrapped in Saran film, and the composite sandwiched between two glass slides at a pressure of approximately 3 kg/cm2. The sample then was transilluminated by argon ion laser light of 457.9-nm wavelength at a power density of 200 mW/cm2 with exposure times up to 5 h (3902 J/cm2 energy density). Essentially, the same procedures were performed for human femoral articular cartilage samples. Control experiments were conducted with laser irradiation alone and with dye alone. All the specimens were stored in isotonic saline solution for 2 h after irradiation to ensure hydration. The bond shear-strength was then tested and samples prepared for optical and electron transmission microscopy. Shear strength values of up to 1.8 kg/cm2 for meniscal tissues and 1.2 kg/cm2 for articular cartilaginous tissues were obtained for exposures of 3902 J/cm2. Shear strength values of approximately 0.9 kg/cm2 and 0.4 kg/cm2, respectively, for meniscus and cartilage were obtained with 459 J/cm2 exposure. Dye- and light-only controls exhibited 0 kg/cm2 shear strength values. Microscopy revealed close contact at the bonded surface in the laser-activated, dye-treated-specimens. This study shows that the laser-activated photoactive dyes have the capability of athermally bonding the meniscal and articular cartilage surfaces.

Multicolor fluorescence enhancement from a photonics crystal surface

NASA Astrophysics Data System (ADS)

Pokhriyal, A.; Lu, M.; Huang, C. S.; Schulz, S.; Cunningham, B. T.

2010-09-01

A photonic crystal substrate exhibiting resonant enhancement of multiple fluorophores has been demonstrated. The device, fabricated uniformly from plastic materials over a ˜3×5 in.2 surface area by nanoreplica molding, utilizes two distinct resonant modes to enhance electric field stimulation of a dye excited by a λ =632.8 nm laser (cyanine-5) and a dye excited by a λ =532 nm laser (cyanine-3). Resonant coupling of the laser excitation to the photonic crystal surface is obtained for each wavelength at a distinct incident angle. Compared to detection of a dye-labeled protein on an ordinary glass surface, the photonic crystal surface exhibited a 32× increase in fluorescent signal intensity for cyanine-5 conjugated streptavidin labeling, while a 25× increase was obtained for cyanine-3 conjugated streptavidin labeling. The photonic crystal is capable of amplifying the output of any fluorescent dye with an excitation wavelength in the 532 nm<λ<633 nm range by selection of an appropriate incident angle. The device is designed for biological assays that utilize multiple fluorescent dyes within a single imaged area, such as gene expression microarrays.

Multicolor fluorescence enhancement from a photonics crystal surface

PubMed Central

Pokhriyal, A.; Lu, M.; Huang, C. S.; Schulz, S.; Cunningham, B. T.

2010-01-01

A photonic crystal substrate exhibiting resonant enhancement of multiple fluorophores has been demonstrated. The device, fabricated uniformly from plastic materials over a ∼3×5 in.2 surface area by nanoreplica molding, utilizes two distinct resonant modes to enhance electric field stimulation of a dye excited by a λ=632.8 nm laser (cyanine-5) and a dye excited by a λ=532 nm laser (cyanine-3). Resonant coupling of the laser excitation to the photonic crystal surface is obtained for each wavelength at a distinct incident angle. Compared to detection of a dye-labeled protein on an ordinary glass surface, the photonic crystal surface exhibited a 32× increase in fluorescent signal intensity for cyanine-5 conjugated streptavidin labeling, while a 25× increase was obtained for cyanine-3 conjugated streptavidin labeling. The photonic crystal is capable of amplifying the output of any fluorescent dye with an excitation wavelength in the 532 nm<λ<633 nm range by selection of an appropriate incident angle. The device is designed for biological assays that utilize multiple fluorescent dyes within a single imaged area, such as gene expression microarrays. PMID:20957067

Pulsed laser-induced damage of metals at 492 nm.

PubMed

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

1982-11-15

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

High-speed off-axis holographic cinematography with a copper-vapor-pumped dye laser.

PubMed

Lauterborn, W; Judt, A; Schmitz, E

1993-01-01

A series of coherent light pulses is generated by pumping a dye laser with the pulsed output of a copper-vapor laser at rates of as much as 20 kHz. Holograms are recorded at this pulse rate on a rotating holographic plate. This technique of high-speed holographic cinematography is demonstrated by viewing the bubble filaments that appear in water under the action of a sound field of high intensity.

DNA-based dye lasers: progress in this half a decade

NASA Astrophysics Data System (ADS)

Kawabe, Yutaka

2016-09-01

After the invention of DNA-surfactant films and the proposal of dye doping into them by Ogata, many applications were demonstrated. Among them tunable thin film laser is one of the most attractive functional devices. Development and progress in DNA based lasers after the first observation of amplified spontaneous emission (ASE) by us has been reviewed in a former paper published in 2011.1 In this proceeding, progresses in the subsequent half a decade are described.

Intense Excitation Source of Blue-Green Laser.

DTIC Science & Technology

1985-10-15

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

Dye-enhanced laser welding for skin closure.

PubMed

DeCoste, S D; Farinelli, W; Flotte, T; Anderson, R R

1992-01-01

The use of a laser to weld tissue in combination with a topical photosensitizing dye permits selective delivery of energy to the target tissue. A combination of indocyanine green (IG), absorption peak 780 nm, and the near-infrared (IR) alexandrite laser was studied with albino guinea pig skin. IG was shown to bind to the outer 25 microns of guinea pig dermis and appeared to be bound to collagen. The optical transmittance of full-thickness guinea pig skin in the near IR was 40% indicating that the alexandrite laser should provide adequate tissue penetration. Laser "welding" of skin in vivo was achieved at various concentrations of IG from 0.03 to 3 mg/cc using the alexandrite at 780 nm, 250-microseconds pulse duration, 8 Hz, and a 4-mm spot size. A spectrum of welds was obtained from 1- to 20-W/cm2 average irradiance. Weak welds occurred with no thermal damage obtained at lower irradiances: stronger welds with thermal damage confined to the weld site occurred at higher irradiances. At still higher irradiances, local vaporization occurred with failure to "weld." Thus, there was an optimal range of irradiances for "welding," which varied inversely with dye concentration. Histology confirmed the thermal damage results that were evident clinically. IG dye-enhanced laser welding is possible in skin and with further optimization may have practical application.

Evaluation of OH laser-induced fluorescence techniques for supersonic combustion diagnostics

NASA Technical Reports Server (NTRS)

Quagliaroli, T. M.; Laufer, G.; Krauss, R. H.; Mcdaniel, J. C., Jr.

1992-01-01

The limitations on application of dye laser and narrowband tunable KrF excimer laser systems to planar OH fluorescence measurements in supersonic combustion test facilities are examined. Included in the analysis are effects of collisional quenching, beam absorption, fluorescence trapping, and signal strengths on achievable measurement accuracy using several excitation and detection options for either of the two laser systems. Dye-based laser systems are found to be the method of choice for imaging OH concentrations less than 10 exp 15 per cu cm, while the KrF based systems provide significant reduction in measurement ambiguity for concentrations in excess of 10 exp 15 per cu cm.

ICIASF '85 - International Congress on Instrumentation in Aerospace Simulation Facilities, 11th, Stanford University, CA, August 26-28, 1985, Record

NASA Technical Reports Server (NTRS)

1985-01-01

Developments related to laser Doppler velocimetry are discussed, taking into account a three-component dual beam laser-Doppler-anemometer to be operated in large wind tunnels, a new optical system for three-dimensional laser-Doppler-anemometry using an argon-ion and a dye laser, and a two-component laser Doppler velocimeter by switching fringe orientation. Other topics studied are concerned with facilities, instrumentation, control, hot wire/thin film measurements, optical diagnostic techniques, signal and data processing, facilities and adaptive wall test sections, data acquisition and processing, ballistic instrument systems, dynamic testing and material deformation measurements, optical flow measurements, test techniques, force measurement systems, and holography. Attention is given to nonlinear calibration of integral wind tunnel balances, a microcomputer system for real time digitized image compression, and two phase flow diagnostics in propulsion systems.

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

Digital DNA detection based on a compact optofluidic laser with ultra-low sample consumption.

PubMed

Lee, Wonsuk; Chen, Qiushu; Fan, Xudong; Yoon, Dong Ki

2016-11-29

DNA lasers self-amplify optical signals from a DNA analyte as well as thermodynamic differences between sequences, allowing quasi-digital DNA detection. However, these systems have drawbacks, such as relatively large sample consumption and complicated dye labelling. Moreover, although the lasing signal can detect the target DNA, it is superimposed on an unintended fluorescence background, which persists for non-target DNA samples as well. From an optical point of view, it is thus not truly digital detection and requires spectral analysis to identify the target. In this work, we propose and demonstrate an optofluidic laser that has a single layer of DNA molecules as the gain material. A target DNA produces intensive laser emission comparable to existing DNA lasers, while any unnecessary fluorescence background is successfully suppressed. As a result, the target DNA can be detected with a single laser pulse, in a truly digital manner. Since the DNA molecules cover only a single layer on the surface of the laser microcavity, the DNA sample consumption is a few orders of magnitude lower than that of existing DNA lasers. Furthermore, the DNA molecules are stained by simply immersing the microcavity in the intercalating dye solution, and thus the proposed DNA laser is free of any complex dye-labelling process prior to analysis.

Electrically controllable liquid crystal random lasers below the Fréedericksz transition threshold.

PubMed

Lee, Chia-Rong; Lin, Jia-De; Huang, Bo-Yuang; Lin, Shih-Hung; Mo, Ting-Shan; Huang, Shuan-Yu; Kuo, Chie-Tong; Yeh, Hui-Chen

2011-01-31

This investigation elucidates for the first time electrically controllable random lasers below the threshold voltage in dye-doped liquid crystal (DDLC) cells with and without adding an azo-dye. Experimental results show that the lasing intensities and the energy thresholds of the random lasers can be decreased and increased, respectively, by increasing the applied voltage below the Fréedericksz transition threshold. The below-threshold-electric-controllability of the random lasers is attributable to the effective decrease of the spatial fluctuation of the orientational order and thus of the dielectric tensor of LCs by increasing the electric-field-aligned order of LCs below the threshold, thereby increasing the diffusion constant and decreasing the scattering strength of the fluorescence photons in their recurrent multiple scattering. This can result in the decrease in the lasing intensity of the random lasers and the increase in their energy thresholds. Furthermore, the addition of an azo-dye in DDLC cell can induce the range of the working voltage below the threshold for the control of the random laser to reduce.

Techniques for reducing and/or eliminating secondary modes in a dye laser oscillator

DOEpatents

Hackel, Richard P.

1988-01-01

A dye laser master oscillator is disclosed herein. This oscillator is intended to provide a single mode output, that is, a primary beam of light of a specific wavelength, but also has the tendency to provide secondary modes, that is, secondary beams of light at different wavelengths and slightly off-axis with respect to the primary beam as a result of grazing incident reflections within the dye cell forming part of the master oscillator. Also disclosed herein are a number of different techniques for reducing or eliminating these secondary modes.

Three-dimensional dynamics of temperature fields in phantoms and biotissue under IR laser photothermal therapy using gold nanoparticles and ICG dye

NASA Astrophysics Data System (ADS)

Akchurin, Georgy G.; Garif, Akchurin G.; Maksimova, Irina L.; Skaptsov, Alexander A.; Terentyuk, Georgy S.; Khlebtsov, Boris N.; Khlebtsov, Nikolai G.; Tuchin, Valery V.

2010-02-01

We describe applications of silica (core)/gold (shell) nanoparticles and ICG dye to photothermal treatment of phantoms, biotissue and spontaneous tumor of cats and dogs. The laser irradiation parameters were optimized by preliminary experiments with laboratory rats. Three dimensional dynamics of temperature fields in tissue and solution samples was measured with a thermal imaging system. It is shown that the temperature in the volume region of nanoparticles localization can substantially exceed the surface temperature recorded by the thermal imaging system. We have demonstrated effective optical destruction of cancer cells by local injection of plasmon-resonant gold nanoshells and ICG dye followed by continuous wave (CW) diode laser irradiation at wavelength 808 nm.

Cellular dye lasers: lasing thresholds and sensing in a planar resonator

PubMed Central

Humar, Matjaž; Gather, Malte C.; Yun, Seok-Hyun

2015-01-01

Biological cell lasers are promising novel building blocks of future biocompatible optical systems and offer new approaches to cellular sensing and cytometry in a microfluidic setting. Here, we demonstrate a simple method for providing optical gain by using a variety of standard fluorescent dyes. The dye gain medium can be located inside or outside a cell, or in both, which gives flexibility in experimental design and makes the method applicable to all cell types. Due to the higher refractive index of the cytoplasm compared to the surrounding medium, a cell acts as a convex lens in a planar Fabry-Perot cavity. Its effect on the stability of the laser cavity is analyzed and utilized to suppress lasing outside cells. The resonance modes depend on the shape and internal structure of the cell. As proof of concept, we show how the laser output modes are affected by the osmotic pressure. PMID:26480446

Application of Raman spectroscopy and surface-enhanced Raman scattering to the analysis of synthetic dyes found in ballpoint pen inks.

PubMed

Geiman, Irina; Leona, Marco; Lombardi, John R

2009-07-01

The applicability of Raman spectroscopy and surface-enhanced Raman scattering (SERS) to the analysis of synthetic dyes commonly found in ballpoint inks was investigated in a comparative study. Spectra of 10 dyes were obtained using a dispersive system (633 nm, 785 nm lasers) and a Fourier transform system (1064 nm laser) under different analytical conditions (e.g., powdered pigments, solutions, thin layer chromatography [TLC] spots). While high fluorescence background and poor spectral quality often characterized the normal Raman spectra of the dyes studied, SERS was found to be generally helpful. Additionally, dye standards and a single ballpoint ink were developed on a TLC plate following a typical ink analysis procedure. SERS spectra were successfully collected directly from the TLC plate, thus demonstrating a possible forensic application for the technique.

1983 Annual Report on Laser Dyes.

DTIC Science & Technology

1984-04-01

Dye II). lThe laser portitm f 1327 11982) 311 the work was sLpp orted b , the National Aerollautics 10 (; II. \\s , .K. Jack-1 amnd AMI . ialpern. (hem...to be the longest-lived. ni)lciatc iu,pui , laser dive solution ol ami that hawe been reported. 1. Introduction We itade a tnore lhiirough evaluation...J. E. Colbert 01) E. White (1) I Riverside Research Institute. Arlington, VA (Suite 714. R. Pamst) 2 Riverside Research Institute. New York, NY Dr. M

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

NASA Astrophysics Data System (ADS)

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

2001-05-01

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

Advances in solid state laser technology for space and medical applications

NASA Technical Reports Server (NTRS)

Byvik, C. E.; Buoncristiani, A. M.

1988-01-01

Recent developments in laser technology and their potential for medical applications are discussed. Gas discharge lasers, dye lasers, excimer lasers, Nd:YAG lasers, HF and DF lasers, and other commonly used lasers are briefly addressed. Emerging laser technology is examined, including diode-pumped lasers and other solid state lasers.

Using the ultra-long pulse width pulsed dye laser and elliptical spot to treat resistant nasal telangiectasia.

PubMed

Madan, Vishal; Ferguson, Janice

2010-01-01

Thick linear telangiectasia on the ala nasi and nasolabial crease can be resistant to treatment with the potassium-titanyl-phosphate (KTP) laser and the traditional round spot on a pulsed dye laser (PDL). We evaluated the efficacy of a 3 mm x 10 mm elliptical spot using the ultra-long pulse width on a Candela Vbeam(R) PDL for treatment of PDL- and KTP laser-resistant nasal telangiectasia. Nasal telangiectasia resistant to PDL (12 patients) and KTP laser (12 patients) in 18 patients were treated with a 3 mm x 10 mm elliptical spot on the ultra-long pulse pulsed dye laser (ULPDL) utilising long pulse width [595 nm, 40 ms, double pulse, 30:20 dynamic cooling device (DCD)]. Six patients had previously received treatment with both PDL and KTP laser prior to ULPDL (40 treatments, range1-4, mean 2.2). Complete clearance was seen in ten patients, and eight patients displayed more than 80% improvement after ULPDL treatment. Self-limiting purpura occurred with round spot PDL and erythema with KTP laser and ULPDL. Subtle linear furrows along the treatment sites were seen in three patients treated with the KTP laser. ULPDL treatment delivered using a 3 mm x 10 mm elliptical spot was non-purpuric and highly effective in the treatment of nasal telangiectasia resistant to KTP laser and PDL.

Direct solar-pumped iodine laser amplifier

NASA Technical Reports Server (NTRS)

Han, K. S.

1985-01-01

This semiannual progress report covers the period from April 1, 1985 to Sept. 30, 1985 under NASA grant NAS1-441 entitled direct solar pumped iodine laser amplifier. During this period the parametric studies of the iodine laser oscillator pumped by a Vortek simulator was carried out before the amplifier studies. The amplifier studies are postponed to the extended period following completion of the parametric studies. In addition, the kinetic modeling of a solar pumped iodine laser amplifier, and the experimental work for a solar pumped dye laser amplifier are in progress. This report contains three parts: (1) the radiation characteristics of solar simulator and the parametric characteristics of photodissociation iodine laser continuously pumped by a Vortek solar simulator; (2) kinetic modeling of a solar pumped iodine laser amplifier; and (3) the study of the dye laser amplifier pumped by a Tamarack solar simulator.

Bibliography of Soviet Laser Developments, Number 28, March - April 1977.

DTIC Science & Technology

1978-02-24

Dyes " a. Rhodamine 25. Makogon, M.M. and V.B. Sukhanov (0). Dye laser with a partially se- lective resonator. ZhPS, v.26, no.4, 1977, 622-625. b...medium. KE, no.4, 1977, 751-757. 105. Bel’tyugov, V.N., I.I. Sukhanov , and Yu.V. Troitskiy (0). Thermal dis- tortions in intraresonator optical

Reconfigurable Solid-state Dye-doped Polymer Ring Resonator Lasers

NASA Astrophysics Data System (ADS)

Chandrahalim, Hengky; Fan, Xudong

2015-12-01

This paper presents wavelength configurable on-chip solid-state ring lasers fabricated by a single-mask standard lithography. The single- and coupled-ring resonator hosts were fabricated on a fused-silica wafer and filled with 3,3‧-Diethyloxacarbocyanine iodide (CY3), Rhodamine 6G (R6G), and 3,3‧-Diethylthiadicarbocyanine iodide (CY5)-doped polymer as the reconfigurable gain media. The recorded lasing threshold was ~220 nJ/mm2 per pulse for the single-ring resonator laser with R6G, marking the lowest threshold shown by solid-state dye-doped polymer lasers fabricated with a standard lithography process on a chip. A single-mode lasing from a coupled-ring resonator system with the lasing threshold of ~360 nJ/mm2 per pulse was also demonstrated through the Vernier effect. The renewability of the dye-doped polymer was examined by removing and redepositing the dye-doped polymer on the same resonator hosts for multiple cycles. We recorded consistent emissions from the devices for all trials, suggesting the feasibility of employing this technology for numerous photonic and biochemical sensing applications that entail for sustainable, reconfigurable, and low lasing threshold coherent light sources on a chip.

Reconfigurable Solid-state Dye-doped Polymer Ring Resonator Lasers

PubMed Central

Chandrahalim, Hengky; Fan, Xudong

2015-01-01

This paper presents wavelength configurable on-chip solid-state ring lasers fabricated by a single-mask standard lithography. The single- and coupled-ring resonator hosts were fabricated on a fused-silica wafer and filled with 3,3′-Diethyloxacarbocyanine iodide (CY3), Rhodamine 6G (R6G), and 3,3′-Diethylthiadicarbocyanine iodide (CY5)-doped polymer as the reconfigurable gain media. The recorded lasing threshold was ~220 nJ/mm2 per pulse for the single-ring resonator laser with R6G, marking the lowest threshold shown by solid-state dye-doped polymer lasers fabricated with a standard lithography process on a chip. A single-mode lasing from a coupled-ring resonator system with the lasing threshold of ~360 nJ/mm2 per pulse was also demonstrated through the Vernier effect. The renewability of the dye-doped polymer was examined by removing and redepositing the dye-doped polymer on the same resonator hosts for multiple cycles. We recorded consistent emissions from the devices for all trials, suggesting the feasibility of employing this technology for numerous photonic and biochemical sensing applications that entail for sustainable, reconfigurable, and low lasing threshold coherent light sources on a chip. PMID:26674508

Reconfigurable Solid-state Dye-doped Polymer Ring Resonator Lasers.

PubMed

Chandrahalim, Hengky; Fan, Xudong

2015-12-17

This paper presents wavelength configurable on-chip solid-state ring lasers fabricated by a single-mask standard lithography. The single- and coupled-ring resonator hosts were fabricated on a fused-silica wafer and filled with 3,3'-Diethyloxacarbocyanine iodide (CY3), Rhodamine 6G (R6G), and 3,3'-Diethylthiadicarbocyanine iodide (CY5)-doped polymer as the reconfigurable gain media. The recorded lasing threshold was ~220 nJ/mm(2) per pulse for the single-ring resonator laser with R6G, marking the lowest threshold shown by solid-state dye-doped polymer lasers fabricated with a standard lithography process on a chip. A single-mode lasing from a coupled-ring resonator system with the lasing threshold of ~360 nJ/mm(2) per pulse was also demonstrated through the Vernier effect. The renewability of the dye-doped polymer was examined by removing and redepositing the dye-doped polymer on the same resonator hosts for multiple cycles. We recorded consistent emissions from the devices for all trials, suggesting the feasibility of employing this technology for numerous photonic and biochemical sensing applications that entail for sustainable, reconfigurable, and low lasing threshold coherent light sources on a chip.

Analysis of in vivo penetration of textile dyes causing allergic reactions

NASA Astrophysics Data System (ADS)

Lademann, J.; Patzelt, A.; Worm, M.; Richter, H.; Sterry, W.; Meinke, M.

2009-10-01

Contact allergies to textile dyes are common and can cause severe eczema. In the present study, we investigated the penetration of a fluorescent textile dye, dissolved from a black pullover, into the skin of one volunteer during perspiration and nonperspiration. Previously, wearing this pullover had induced a severe contact dermatitis in an 82-year old woman, who was not aware of her sensitization to textile dyes. The investigations were carried out by in vivo laser scanning microscopy. It could be demonstrated that the dye was eluted from the textile material by sweat. Afterwards, the dye penetrated into the stratum corneum and into the hair follicles. Inside the hair follicles, the fluorescent signal was still detectable after 24 h, whereas it was not verifiable anymore in the stratum corneum, Laser scanning microscopy represents an efficient tool for in vivo investigation of the penetration and storage of topically applied substances and allergens into the human skin and reveals useful hints for the development and optimization of protection strategies.

Solar generation and storage of O2 (a 1 delta g)

NASA Technical Reports Server (NTRS)

Twarowski, Allen J.; Dao, Phan; Good, Lisa A.

1988-01-01

An investigation was performed of the technical steps required to design a solar powered oxygen-iodine laser. Singlet delta oxygen is formed upon transfer of energy from selected photoexcited dye molecules to ground state molecular oxygen and then is concentrated and stored as an endoperoxide by reaction with an aromatic hydrocarbon. The endoperoxide, when heated, releases singlet oxygen in high yield thus providing a regenerable source of laser fuel. Energy transfer from dye molecules to molecular oxygen was investigated. When dye molecules were adsorbed to polymer substrates it was observed that the dye became embedded in the polymer matrix. Porphin dyes were incorporated into films of 1,4-dimethyl-2-poly(vinylnaphthalene), 2PVN. An endoperoxide was formed when porphin-doped 2PVN was exposed to visible radiation. This demonstrates the possibility of generating singlet oxygen using solar energy and concentrating and storing it in one simple step. Transport of energy by exciton migration in polycrystalline dye films was also investigated.

Water soluble laser dyes

DOEpatents

Hammond, Peter R.; Feeman, James F.; Field, George F.

1998-01-01

Novel water soluble dyes of the formula I are provided ##STR1## wherein R.sup.1 and R.sup.4 are alkyl of 1 to 4 carbon atoms or hydrogen; or R.sup.1 -R.sup.2 or R.sup.2 -R.sup.4 form part of aliphatic heterocyclic rings; R.sup.2 is hydrogen or joined with R.sup.1 or R.sup.4 as described above; R.sup.3 is --(CH.sub.2).sub.m --SO.sub.3.sup.-, where m is 1 to 6; X is N, CH or ##STR2## where Y is 2 --SO.sub.3.sup.- ; Z is 3, 4, 5 or 6 --SO.sub.3.sup.-. The novel dyes are particularly useful as the active media in water solution dye lasers.

Co2/Erbium:YAG/Dye laser combination: an effective and successful treatment for angiofibromas in tuberous sclerosis.

PubMed

Fioramonti, Paolo; De Santo, Liliana; Ruggieri, Martina; Carella, Sara; Federico, Lo Torto; Onesti, Maria Giuseppina; Scuderi, Nicolò

2014-02-01

Tuberous sclerosis, an autosomal dominant neurocutaneous syndrome seen in approximately 1 in 6,000 people worldwide, is characterized by the appearance of hamartomas in multiple organs. The classic clinical triad consists of angiofibromas, epilepsy, and developmental delay. Dermatologic disorder is one of the main characteristics. Angiofibromas, a common form of presentation, causes significant cosmetic and medical problems. The current treatment for skin lesions is laser therapy. The carbon dioxide (CO2) laser has been used satisfactorily in treating these lesions, but several studies have demonstrated a high percentage of recurrences. Erbium:yttrium-aluminum-garnet (YAG) laser treatment has been used to resurface skin abnormalities in patients with dermatologic conditions. The dye laser as an alternative uses the principles of selective photothermolysis and is very effective in treating the vascular component of tuberous sclerosis. The use of all these lasers to treat skin lesions in patients affected by tuberous sclerosis has never been described in the literature. A retrospective study, conducted from 2007 to May 2013, investigated 13 patients who had tuberous sclerosis treated with an erbium:YAG/CO2/dye laser combination. All the patients showed great improvement of their skin lesions. The results were evident immediately after the first treatment. No patient experienced complications or recurrence. The combined use of the erbium:YAG/Dye/CO2 laser is a safe and effective treatment for skin lesions in patients affected by tuberous sclerosis. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Influence of an Interfacial Effect on the Laser Performance of a Rhodamine 6G/Cellulose Acetate Waveguide on a Vinylidene Fluoride Copolymer Layer.

PubMed

Tsutsumi, Naoto; Hirano, Yoshinori; Kinashi, Kenji; Sakai, Wataru

2018-06-12

The fluorescent properties of dyes and fluorophores in condensed matter significantly affect the laser performance of organic dye lasers and fluorescent polymer lasers. Concentration quenching of fluorescence is commonly observed in condensed matter. Several approaches have been presented to suppress such quenching, such as the use of a dendrimer and the use of effective energy transfer in a guest-host system. The enhanced fluorescence of rhodamine 6G (R6G) dye on a vinylidene fluoride polymer is an alternative method for enhancing laser performance because of the roughness of the P(VDF-TrFE) surface and the interaction between polar β-crystals of P(VDF-TrFE) and R6G dye. In this paper, a significant improvement in slope efficiency (SE) is demonstrated without a significant depression in the lasing threshold for distributed feedback (DFB) and distributed Bragg reflector (DBR) lasers fabricated using an R6G-dispersed cellulose acetate (CA) matrix spin-coated onto a copolymer of vinylidene fluoride and trifluoroethylene P(VDF-TrFE) thin film. SEs of 3.4 and 1.3% were measured for DBR and DFB laser devices with CA/R6G on a P(VDF-TrFE) thin film, respectively, whereas an SE of less than 1.0% was measured for both corresponding laser devices without a P(VDF-TrFE) thin film. From the aspect of simple fabrication procedures, repeatability in device fabrication and performance, stability of the device, time for device fabrication, the present approach is the most preferable way for industrial applications, requiring only the additional step of spin-coating of a P(VDF-TrFE) thin film.

Parallel and Multivalued Logic by the Two-Dimensional Photon-Echo Response of a Rhodamine–DNA Complex

PubMed Central

2015-01-01

Implementing parallel and multivalued logic operations at the molecular scale has the potential to improve the miniaturization and efficiency of a new generation of nanoscale computing devices. Two-dimensional photon-echo spectroscopy is capable of resolving dynamical pathways on electronic and vibrational molecular states. We experimentally demonstrate the implementation of molecular decision trees, logic operations where all possible values of inputs are processed in parallel and the outputs are read simultaneously, by probing the laser-induced dynamics of populations and coherences in a rhodamine dye mounted on a short DNA duplex. The inputs are provided by the bilinear interactions between the molecule and the laser pulses, and the output values are read from the two-dimensional molecular response at specific frequencies. Our results highlights how ultrafast dynamics between multiple molecular states induced by light–matter interactions can be used as an advantage for performing complex logic operations in parallel, operations that are faster than electrical switching. PMID:25984269

Strong coupling between surface plasmon polariton and laser dye rhodamine 800

NASA Astrophysics Data System (ADS)

Valmorra, Federico; Bröll, Markus; Schwaiger, Stephan; Welzel, Nadine; Heitmann, Detlef; Mendach, Stefan

2011-08-01

We report on strong coupling between surface plasmon polaritons on a thin silver film and laser dye Rhodamine 800. Attenuated total reflection measurements reveal that the pure surface plasmon polaritons interact with the Rhodamine 800 absorption lines exhibiting pronounced anticrossings in the dispersion relation. We show that the corresponding energy gap can be tailored by the concentration of dye molecules in the dielectric matrix between 50 meV and 70 meV. We can well model our data by a classical transfer matrix approach as well as by a quantum mechanical coupled oscillator ansatz.

IV INTERNATIONAL CONFERENCE ON ATOM AND MOLECULAR PULSED LASERS (AMPL'99): Radiative and photochemical properties of organic compounds excited by high-power XeCl laser radiation

NASA Astrophysics Data System (ADS)

Kopylova, T. N.; Kuznetsova, Rimma T.; Svetlichnyi, Valerii A.; Sergeev, A. K.; Tel'minov, E. N.; Filinov, D. N.

2000-06-01

Radiative and photochemical properties of a number of laser dyes excited by focused radiation of a XeCl laser with intensity up to 200 MW cm-2 were studied. A method for measuring the gain of organic molecules under high-power excitation is proposed. The dependence of the dye transmittance for the pump radiation on its intensity was studied. It is shown that changes in energy, spectral, and time characteristics of radiation and the photostability of compounds under high-power excitation are associated with the formation of superluminescence.

Comparison of the effect of the carbon dioxide laser and the bipolar coagulator on the cat brain

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

Cozzens, J.W.; Cerullo, L.J.

The carbon dioxide laser has recently received clinical acceptance in neurosurgical practice. There are, however, few studies reported in the neurosurgical literature, either clinical or experimental, concerning its safety or efficacy on a physiological level by comparison to a more conventional tool. This study is not a description of a surgical technique, but is rather a basic physiological comparison of two surgical instruments. In this study, 11 cats were pretreated with the protein-bound dye, Evans blue. A corticotomy was performed in one hemisphere with the carbon dioxide laser and in the other with a microbipolar coagulator and a sharp blade.more » The subsequent extravasation of dye was presumed to be proportional to the amount of blood-brain barrier disruption associated with each lesion. When effective power settings for the two devices were compared, the laser lesions had significantly less extravasation of blue dye. This indicated that there was less damage to the blood-brain barrier surrounding laser corticotomy than surrounding conventional bipolar coagulation and sharp dissection at comparable power settings for each modality.« less

Laser velocimetry with fluorescent dye-doped polystyrene microspheres.

PubMed

Lowe, K Todd; Maisto, Pietro; Byun, Gwibo; Simpson, Roger L; Verkamp, Max; Danehy, Paul M; Tiemsin, Pacita I; Wohl, Christopher J

2013-04-15

Simultaneous Mie scattering and laser-induced fluorescence (LIF) signals are obtained from individual polystyrene latex microspheres dispersed in an air flow. Microspheres less than 1 μm mean diameter were doped with two organic fluorescent dyes, Rhodamine B (RhB) and dichlorofluorescein (DCF), intended either to provide improved particle-based flow velocimetry in the vicinity of surfaces or to provide scalar flow information (e.g., marking one of two fluid streams). Both dyes exhibit measureable fluorescence signals that are on the order of 10(-3) to 10(-4) times weaker than the simultaneously measured Mie signals. It is determined that at the conditions measured, 95.5% of RhB LIF signals and 32.2% of DCF signals provide valid laser-Doppler velocimetry measurements compared with the Mie scattering validation rate with 6.5 W of 532 nm excitation, while RhB excited with 1.0 W incident laser power still exhibits 95.4% valid velocimetry signals from the LIF channel. The results suggest that the method is applicable to wind tunnel measurements near walls where laser flare can be a limiting factor and monodisperse particles are essential.

Diagnosis of NMOS DRAM functional performance as affected by a picosecond dye laser

NASA Technical Reports Server (NTRS)

Kim, Q.; Schwartz, H. R.; Edmonds, L. D.; Zoutendyk, J. A.

1992-01-01

A picosec pulsed dye laser beam was at selected wavelengths successfully used to simulate heavy-ion single-event effects (SEEs) in negative channel NMOS DRAMs. A DRAM was used to develop the test technique because bit-mapping capability and previous heavy-ion upset data were available. The present analysis is the first to establish such a correlation between laser and heavy-ion data for devices, such as the NMOS DRAM, where charge collection is dominated by long-range diffusion, which is controlled by carrier density at remote distances from a depletion region. In the latter case, penetration depth is an important parameter and is included in the present analysis. A single-pulse picosecond dye laser beam (1.5 microns diameter) focused onto a single cell component can upset a single memory cell; clusters of memory cell upsets (multiple errors) were observed when the laser energy was increased above the threshold energy. The multiple errors were analyzed as a function of the bias voltage and total energy of a single pulse. A diffusion model to distinguish the multiple upsets from the laser-induced charge agreed well with previously reported heavy ion data.

Comparison of microleakages of photo-cured composites using three different light sources: halogen lamp, LED and argon laser: an in vitro study.

PubMed

Tielemans, M; Compere, Ph; Geerts, S O; Lamy, M; Limme, M; De Moor, R J G; Delmé, K I M; Bertrand, M F; Rompen, E; Nammour, S

2009-01-01

In this study, we compared the microleakage of composite fillings cured with halogen bulb, LED and argon ion laser (488 nm). Twenty-four extracted human molars were divided randomly in three groups. Six cavities were prepared on the coronal part of each tooth. Standard cavities (1.7 x 2 mm) were prepared. Cavities were acid etched, sealed with Scotch Bond 1 and filled by a hybrid composite. Cavities were exposed to one light source, thermocycled and immersed in a 2% methylene blue dye solution. Dye penetration in the leakage of cavities was recorded using a digital optical microscope. Mean values of percentage of dye penetrations in microleakages of cavities were 49.303 +/- 5.178% for cavities cured with LED, 44.486 +/- 6.075% with halogen bulb and 36.647 +/- 5.936% for those cured by argon laser. Statistically significant difference exists between cavities cured by halogen vs LED (P < 0.01), halogen vs laser (P < 0.001) and LED vs laser (P < 0.001). The lowest microleakage was observed in the cavities and composites cured with argon ion laser.

Dye laser traveling wave amplifier

NASA Technical Reports Server (NTRS)

Davidson, F.; Hohman, J.

1984-01-01

A flashlamp pumped dye laser suitable for use as a single stage amplifier is described. Particular emphasis is placed on the efforts to increase output pulse energy and improve the temporal profile of the injected pulse. By using high power thin film polarizers, output energies reach from 4 to 45 mJ. Various dispersive elements are used to develop an amplified pulse with an extremely clean temporal profile.

Simultaneous sampling technique for two spectral sources

NASA Technical Reports Server (NTRS)

Jarrett, Olin, Jr.

1987-01-01

A technique is described that uses a bundle of fiber optics to simultaneously sample a dye laser and a spectral lamp. By the use of a real-time display with this technique, the two signals can be superimposed, and the effect of any spectral adjustments can be immediately accessed. In the NASA's CARS system used for combustion diagnostics, the dye laser mixes with a simultaneously pulsed Nd:YAG laser at 532 nm to probe the vibrational levels of nitrogen. An illustration of the oscilloscopic display of the system is presented.

Computer simulation of gene detection without PCR by single molecule detection

NASA Astrophysics Data System (ADS)

Davis, Lloyd M.; Williams, John G.; Lamb, Don T.

1999-01-01

Pioneer Hi-Bred is developing a low-cost method for rapid screening of DNA, for use in research on elite crop seed genetics. Unamplified genomic DNA with the requisite base sequence is simultaneously labeled by two different colored fluorescent probes, which hybridize near the selected gene. Dual-channel single molecule detection (SMD) within a flow cell, then provides a sensitive and specific assay for the gene. The technique has been demonstrated using frequency- doubled Nd:YAG laser excitation of two visible-wavelength dyes. A prototype instrument employing infrared fluorophores and laser diodes for excitation has been developed. Here, we report results from a Monte Carlo simulation of the new instrument, in which experimentally determined photophysical parameters for candidate infrared dyes are used for parametric studies of experimental operating conditions. Fluorophore photostability is found to be a key factor in determining the instrument sensitivity. Most infrared dyes have poor photostability, resulting in inefficient SMD. However, the normalized cross-correlation function of the photon signals from each of the two channels can still yield a discernable peak, provided that the concentration of dual- labeled molecules is sufficiently high. Further, for low concentrations, processing of the two photon streams with Gaussian -weighted sliding sum digital filters and selection of simultaneously occurring peaks can also provide a sensitive indicator of the presence of dual-labeled molecules, although accidental coincidences must be considered in the interpretation of results.

Development of New Laser-Protective Dyes. Phase 1.

DTIC Science & Technology

1990-10-30

technology to stabilize cyanine and squarylium dyes . This accomplishment will justify continued research on the synthesis and process development of...beyond. This is the subject of a proposed Phase II program. RESULTS AND DISCUSSION THERMAL STABILITY: In Phase I, dyes of the cyanine and squarylium ...Test in Appendix 1). Table 1 shows that the squarylium dyes are inherently more thermally stable than the cyanines. This observation supports

Intraoperative Fluorescence Cerebral Angiography by Laser Surgical Microscopy: Comparison With Xenon Microscopy and Simultaneous Observation of Cerebral Blood Flow and Surrounding Structures.

PubMed

Ito, Yuhei; Suzuki, Kyouichi; Ichikawa, Tsuyoshi; Watanabe, Yoichi; Sato, Taku; Sakuma, Jun; Saito, Kiyoshi

2018-06-12

Laser surgical microscopes should enable uniform illumination of the operative field, and require less luminous energy compared with existing xenon surgical microscopes. To examine the utility of laser illumination in fluorescence cerebral angiography. Fluorescein sodium (fluorescein) was used as a fluorescent dye. We first compared the clarity of cerebral blood flow images collected by fluorescence angiography between the laser illumination and xenon illumination methods. We then assessed use of the laser illuminator for simultaneous observation of blood flow and surrounding structures during fluorescence angiography. Furthermore, the study was designed to evaluate usefulness of the thus determined excitation light in clinical cases. Fluorescence angiography using blue light laser for excitation provided higher clarity and contrast blood flow images compared with using blue light generated from a xenon lamp. Further, illumination with excitation light consisting of a combination of 3 types of laser (higher level of blue light, no green light, and lower level of red light) enabled both blood flow and surrounding structures to be observed through the microscope directly by the surgeon. Laser-illuminated fluorescence angiography provides high clarity and contrast images of cerebral blood flow. Further, a laser providing strong blue light and weak red light for excitation light enables simultaneous visual observation of fluorescent blood flow and surrounding structures by the surgeon using a surgical microscope. Overall, these data suggest that laser surgical microscopes are useful for both ordinary operative manipulations and fluorescence angiography.

Hybrid organic semiconductor lasers for bio-molecular sensing.

PubMed

Haughey, Anne-Marie; Foucher, Caroline; Guilhabert, Benoit; Kanibolotsky, Alexander L; Skabara, Peter J; Burley, Glenn; Dawson, Martin D; Laurand, Nicolas

2014-01-01

Bio-functionalised luminescent organic semiconductors are attractive for biophotonics because they can act as efficient laser materials while simultaneously interacting with molecules. In this paper, we present and discuss a laser biosensor platform that utilises a gain layer made of such an organic semiconductor material. The simple structure of the sensor and its operation principle are described. Nanolayer detection is shown experimentally and analysed theoretically in order to assess the potential and the limits of the biosensor. The advantage conferred by the organic semiconductor is explained, and comparisons to laser sensors using alternative dye-doped materials are made. Specific biomolecular sensing is demonstrated, and routes to functionalisation with nucleic acid probes, and future developments opened up by this achievement, are highlighted. Finally, attractive formats for sensing applications are mentioned, as well as colloidal quantum dots, which in the future could be used in conjunction with organic semiconductors.

Long pulsed dye laser treatment of facial wrinkles.

PubMed

Tay, Yong-Kwang; Khoo, Boo-Peng; Tan, Eileen; Kwok, Colin

2004-11-01

The flashlamp pulsed dye laser has been used in the treatment of rhytids. To evaluate the efficacy of the long pulsed dye laser in the treatment of mild to moderate wrinkles in Asian patients. Wrinkles on one half of the face in 10 subjects were treated with the long pulsed dye laser (595 nm, 10 mm spot size, 10 ms, 7 J/cm2, 40 ms spray, 40 ms delay, single-pass, 30% overlap) with the other side serving as a control. A total of three treatments were given at 2 monthly intervals. The following sites were treated: periorbital area, six patients; forehead, two patients; cheek, two patients. No preoperative anesthesia or postoperative treatment were used. Clinical photographs were taken before and after each treatment, and analysis was undertaken through photographic evaluation by non-treating physicians. At 2 months after the last treatment, the clinical improvement of rhytids was noted in all patients compared with baseline. Four subjects had mild improvement (< or = 25%), five had moderate improvement (26-50%) and one had marked improvement (51-75%). The periorbital area was more responsive to treatment compared with the other sites. No clinical changes were noted in the control areas. No adverse effects were reported except for transient mild erythema in two patients which lasted for up to an hour. Nine patients were somewhat satisfied with the treatment and one was highly satisfied. All wanted the other half of the face to be treated. Treatment with a non-ablative 595 nm flashlamp pulsed dye laser can lead to mild to moderate clinical improvement in class I-II rhytids with minimal to no side effects in patients with darker skin types.

Water soluble laser dyes

DOEpatents

Hammond, P.R.; Feeman, J.F.; Field, G.F.

1998-08-11

Novel water soluble dyes of the formula 1 are provided by the formula described in the paper wherein R{sup 1} and R{sup 4} are alkyl of 1 to 4 carbon atoms or hydrogen; or R{sup 1}--R{sup 2} or R{sup 2}--R{sup 4} form part of aliphatic heterocyclic rings; R{sup 2} is hydrogen or joined with R{sup 1} or R{sup 4} as described above; R{sup 3} is --(CH{sub 2}){sub m}--SO{sub 3}{sup {minus}}, where m is 1 to 6; X is N, CH or formula 2 given in paper where Y is 2 --SO{sub 3}{sup {minus}} ; Z is 3, 4, 5 or 6 --SO{sub 3}{sup {minus}}. The novel dyes are particularly useful as the active media in water solution dye lasers.

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Influence of the layer thickness and concentration of dye molecules on the emission amplification in cholesteric liquid crystals

NASA Astrophysics Data System (ADS)

Alaverdyan, R. B.; Gevorgyan, A. A.; Chilingaryan, A. D.; Chilingaryan, Yu S.

2008-05-01

The propagation of light through a planar layer of a cholesteric liquid crystal doped with dye molecules is considered. The features of the emission spectra of the crystal are studied both in the absence and presence of dielectric boundaries. The increase in the emission intensity is investigated for different layer thicknesses and different concentrations of dye molecules. It is shown that an anomalously strong increase in the emission intensity with the diffraction intrinsic polarisation takes place in the case of a comparatively small crystal thickness and a relatively low concentration of dye molecules. The obtained results can be used for the development of miniature lasers with the circular polarisation of the fundamental radiation mode.

Tunable organic distributed feedback dye laser device excited through Förster mechanism

NASA Astrophysics Data System (ADS)

Tsutsumi, Naoto; Hinode, Taiki

2017-03-01

Tunable organic distributed feedback (DFB) dye laser performances are re-investigated and characterized. The slab-type waveguide DFB device consists of air/active layer/glass substrate. Active layer consisted of tris(8-quinolinolato)aluminum (Alq3), 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM) dye, and polystyrene (PS) matrix. Effective energy transfer from Alq3 to DCM through Förster mechanism enhances the laser emission. Slope efficiency in the range of 4.9 and 10% is observed at pump energy region higher than 0.10-0.15 mJ cm-2 (lower threshold), which is due to the amplified spontaneous emission (ASE) and lasing. Typical slope efficiency for lasing in the range of 2.0 and 3.0% is observed at pump energy region higher than 0.25-0.30 mJ cm-2 (higher threshold). The tuning wavelength for the laser emission is ranged from 620 to 645 nm depending on the ASE region.

Peculiarities of the statistics of spectrally selected fluorescence radiation in laser-pumped dye-doped random media

NASA Astrophysics Data System (ADS)

Yuvchenko, S. A.; Ushakova, E. V.; Pavlova, M. V.; Alonova, M. V.; Zimnyakov, D. A.

2018-04-01

We consider the practical realization of a new optical probe method of the random media which is defined as the reference-free path length interferometry with the intensity moments analysis. A peculiarity in the statistics of the spectrally selected fluorescence radiation in laser-pumped dye-doped random medium is discussed. Previously established correlations between the second- and the third-order moments of the intensity fluctuations in the random interference patterns, the coherence function of the probe radiation, and the path difference probability density for the interfering partial waves in the medium are confirmed. The correlations were verified using the statistical analysis of the spectrally selected fluorescence radiation emitted by a laser-pumped dye-doped random medium. Water solution of Rhodamine 6G was applied as the doping fluorescent agent for the ensembles of the densely packed silica grains, which were pumped by the 532 nm radiation of a solid state laser. The spectrum of the mean path length for a random medium was reconstructed.

Optimization of Nanocomposite Solar Cell/Liquid Crystal Matrix to Diminish High Intensity Laser Light Relevant to Aviation Safety Applications

NASA Astrophysics Data System (ADS)

Hofmann, James A.

An increasing threat to the aviation industry is laser light illumination on airplanes during critical phases of flight. If a laser hits the cockpit, it not only distracts the pilots, but it can cause flash blindness or permanently damage the vision of the pilots. This research attempts to mitigate these lasers illuminations through the application of both liquid crystal (LC's) technologies and dye sensitized solar cell (DSSC) technologies. The LC of choice is N-(4-Methoxybenzylidene)-4-butylaniline, or MBBA, because it has special optical properties including the ability to undergo phase transitions when exposed to an electric field. By applying an external electric field, MBBA switches from its transparent nematic phase, to its non-transparent crystalline phase, blocking the laser light. This research optimized the application of MBBA by reducing the triggering voltage and relaxation time of the LC using spacer thicknesses and scratching techniques. The liquid to solid phase transition was reduced to a 3V differential, and the time required for the crystals to relax into its transparent liquid phase was reduced to less than ten seconds. The phase transition was studied using an external electric field generated by DSSCs constructed from a titanium dioxide (TiO2) nanocomposite layer coated with dye. To maximize the voltage output by the DSSCs, layer thickness and dye sensitizer were studied to investigate their impact on the performance of the DSSC when illuminated by solar lamps and green light (532nm). Three different layer thicknesses and five different dyes were tested: Eosin Y, Eriochrome Black, Congo Red, Fast Green, and Alizarine Yellow. The experimental results showed a thin layer of nanocomposite sensitized with Eosin Y dye produced the most efficient DSSCs for the scope of this research. Experimental testing showed the DSSCs can generate 381 +/- 10mV under solar lamp exposure, 356 +/- 10mV under laser light exposure, and a voltage increase of 60 +/- 16mV when exposed to both light sources. Additionally, the performance of the DSSCs were correlated to molecular modeling predictions using Spartan software. The stability of TiO2-dye interactions indicated that dye adsorption to the surface of the nanocomposite directly impacted the performance of the DSSCs. Implementation of a LC and DSSC system forces the LCs to transition between its nematic and crystalline phases depending on the wavelength of light that is illuminating the DSSC. This research explores the practicality of using LCs and DSSCs as a preliminary approach to mitigating green laser light illumination on aircraft. Experimental results have shown that DSSCs alone are not capable of forcing a phase transitions in LCs which can entirely mitigate incoming laser light. The intense laser light required to generate substantial voltage (3V) from the DSSCs penetrates the crystalline phase of the LC with minimal attenuation of 5%.

Effects of diode laser welding with dye-enhanced glue on tensile strength of sutures commonly used in urology.

PubMed

Kirsch, A J; Chang, D T; Kayton, M L; Libutti, S K; Connor, J P; Hensle, T W

1996-01-01

Tissue welding using laser-activated protein solders may soon become an alternative to sutured tissue approximation. In most cases, approximating sutures are used both to align tissue edges and provide added tensile strength. Collateral thermal injury, however, may cause disruption of tissue alignment and weaken the tensile strength of sutures. The objective of this study was to evaluate the effect of laser welding on the tensile strength of suture materials used in urologic surgery. Eleven types of sutures were exposed to diode laser energy (power density = 15.9 W/cm2) for 10, 30, and 60 seconds. Each suture was compared with and without the addition of dye-enhanced albumin-based solder. After exposure, each suture material was strained (2"/min) until ultimate breakage on a tensometer and compared to untreated sutures using ANOVA. The strength of undyed sutures were not significantly affected; however, violet and green-dyed sutures were in general weakened by laser exposure in the presence of dye-enhanced glue. Laser activation of the smallest caliber, dyed sutures (7-0) in the presence of glue caused the most significant loss of tensile strength of all sutures tested. These results indicate that the thermal effects of laser welding using our technique decrease the tensile strength of dyed sutures. A thermally resistant suture material (undyed or clear) may prevent disruption of wounds closed by laser welding techniques.

A comparative study of pulsed dye laser versus long pulsed Nd:YAG laser treatment in recalcitrant viral warts.

PubMed

Shin, Yo Sup; Cho, Eun Byul; Park, Eun Joo; Kim, Kwang Ho; Kim, Kwang Joong

2017-08-01

Viral warts are common infectious skin disease induced by human papillomavirus (HPV). But the treatment of recalcitrant warts is still challenging. In this study, we compared the effectiveness of pulsed dye laser (PDL) and long pulsed Nd:YAG (LPNY) laser in the treatment of recalcitrant viral warts. We retrospectively analyzed the medical records of patients with recalcitrant warts treated with laser therapy between January 2013 and February 2016. Seventy-two patients with recalcitrant warts were evaluated. Thirty-nine patients were treated with pulsed dye laser and thirty-three patients were treated with LPNY laser. The following parameters were used: PDL (spot size, 7 mm; pulse duration, 1.5 ms; and fluence, 10-14 J/cm 2 ) and LPNY (spot size, 5 mm; pulse duration, 20 ms; and fluence, 240-300 J/cm 2 ). Complete clearance of two patients (5.1%) in PDL group, and three patients (9.1%) in LPNY group were observed without significant side effects. The patients who achieved at least 50% improvement from baseline were 20 (51.3%) in PDL and 22 (66.7%) in LPNY, respectively. This research is meaningful because we compared the effectiveness of the PDL and LPNY in the recalcitrant warts. Both PDL and LPNY laser could be used as a safe and alternative treatment for recalcitrant warts.

Reinforcement of high-risk anastomoses using laser-activated protein solders: a clinical study

NASA Astrophysics Data System (ADS)

Libutti, Steven K.; Bessler, Marc; Chabot, J.; Bass, Lawrence S.; Oz, Mehmet C.; Auteri, Joseph S.; Kirsch, Andrew J.; Nowygrod, Roman; Treat, Michael R.

1993-07-01

Anastomotic leakage or breakdown can result in catastrophic complications and significantly increased post-operative morbidity and mortality. Certain anastomoses are subject to a higher incidence of disruption and are therefore termed high risk. In an attempt to decrease the risk of anastomotic leaks, we reinforced sutured anastomoses with a laser activated protein solder in patients undergoing esophagojejunostomies (n equals 2), lung transplantation (n equals 2), and pancreaticojejunostomies (Whipple procedure, n equals 5). The protein solder was composed of 1.0 ml of a 25% human albumin solution, 1.0 ml of sodium hyaluronate, and 0.1 ml of Cardiogreen dye. This composition was applied to the sutured anastomosis and activated with an 860 nm pulsed diode laser. Drains were placed when appropriate and patients were followed for up to 10 months post-operatively and assessed for clinical signs of anastomotic leaks. Results to data demonstrated that there were no immediate complications as a result of the procedure. Operative time was not significantly lengthened. There were no cases of clinically significant leakage from any of the reinforced anastomoses. Laser activated protein solders may help to reduce the incidence of leakage in high risk anastomoses. Large numbers of patients and longer follow-up is needed however, to draw significant conclusions.

Passive mode lockers for lasers generating at a wavelength of 1.06 micron

NASA Astrophysics Data System (ADS)

Mikhailov, V. P.; Demchuk, M. I.; Lugovskii, A. P.; Sosnovskii, G. M.; Iumashev, K. V.

1983-04-01

New polymethine dyes that can be used for the passive mode locking of lasers generating at 1.06 micron are investigated using YAG:Nd as the active element. The effect of introducing various substituents into the heterocyclic nuclei of the end groups of polymethine dyes is discussed. It is shown that substituents generally increase the energy of the ultrashort pulse while also increasing its length.

Laser inhibited diffusion in rhodamine-ethanol solutions

NASA Technical Reports Server (NTRS)

Lawandy, N. M.; Fuhr, P. L.; Robinson, D. W.

1981-01-01

The diffusion of rhodamine-6G dye in ethanol is observed to be inhibited by optical pumping by a cadmium laser. The diffusion process is observed as a function of the solution temperature. The relative difference in diffusion coefficients with and without optical pumping is calculated. The effect is interpreted as being due to a stronger solvent-dye interaction in the first excited singlet state of rhodamine-6G.

Topical timolol maleate 0.5% for infantile hemangioma; it's effectiveness and/or adjunctive pulsed dye laser - single center experience of 102 cases in Korea.

PubMed

Park, Kyung Hea; Jang, Yong Hyun; Chung, Ho Yun; Lee, Weon Ju; Kim, Do Won; Lee, Seok-Jong

2015-01-01

Although oral beta-blocker, propranolol, was shown excellent outcome for infantile hemangioma (IH) up to date, concern of side effects and reluctance of treatment-related cumbersome evaluations are major obstacles to employ. Instead, topical beta-blockers were recently introduced as an effective alternative, but few studies are reported. So we performed a retrospective study of IH treated with topical beta-blockers, timolol maleate 0.5%, and adjunctive role of pulsed dye laser from 2011 to 2014. Among 102 IH enrolled, 61 patients (59.8%) treated with only timolol maleate and 41 (40.2%) patients treated with combination of pulsed dye laser. A clinical review of medical records and evaluation at 4-8 weeks intervals using the physicians' Global Assessment Scores (GAS) and patients' parents' GAS at the latest visit. Physicians' GAS was used to grade the lesions compared with the baseline photo by two physicians' evaluation. And parents' GAS was assessed by direct or telephone interview. In the only timolol treatment group, mean change was within 47.0% improvement from baseline by physicians. In addition, adjunctive treatment of pulsed dye laser group showed 66.5% improvement. No side effects were found on both groups, and mean change was 54.5% improvement by overall parent assessments.

Pulsed Dye Laser Therapy in the Treatment of Warts: A Review of the Literature.

PubMed

Veitch, David; Kravvas, Georgios; Al-Niaimi, Firas

2017-04-01

Warts or verrucae vulgaris are common cutaneous infections with currently no definitive curative treatments available. To determine the efficacy of pulsed dye laser (PDL) in the treatment of warts. A literature search was performed using the PubMed and MEDLINE databases. A search using {(Wart[s], verruca or condylomata)} AND [(Pulsed dye laser)] was used. Forty-four articles were identified as relevant to this review. Simple warts were very responsive to PDL, being treated successfully in over 95% of patients. Facial and anogenital warts also demonstrated excellent outcomes. Recalcitrant warts, displayed significant variability in their response, ranging between 50% and 100% across all articles. The response rates seen in peripheral warts (involving the hands and feet) were also very variable, ranging between 48% and 95%. Recurrence rates at 4 months of follow-up were documented as 0% to 15%. Complications have been described as very few and rare, the main ones being topical discomfort and erythema. Pulsed dye laser is a safe and effective modality in the treatment of warts that can be applied to most body parts. Cost and availability remain a limitation to the use of PDL; however, this modality can be used when other more traditional and accessible treatments have failed.

Studies on the optogalvanic effect and isotope-selective excitation of ytterbium in a hollow cathode discharge lamp using a pulsed dye laser.

PubMed

Kumar, Pankaj; Kumar, Jitendra; Prakash, Om; Saini, Vinod K; Dixit, Sudhir K; Nakhe, Shankar V

2013-09-01

This paper presents studies on the pulsed optogalvanic effect and isotope-selective excitation of Yb 555.648 nm (0 cm(-1) → 17 992.007 cm(-1)) and 581.067 nm (17 992.007 cm(-1) → 35 196.98 cm(-1)) transitions, in a Yb/Ne hollow cathode lamp. The Yb atoms were excited by narrow linewidth (500-1000 MHz) Rh110 and Rh6G dye based pulsed lasers. Optogalvanic signal inversion for ground state transition at 555.648 nm was observed beyond a hollow cathode discharge current of 8.5 mA, in contrast to normal optogalvanic signal at 581.067 nm up to maximum current of 14 mA. The isotope-selective excitation studies of Yb were carried out by recording Doppler limited optogalvanic signals as a function of dye laser wavelength. For the 581.067 nm transition, three even isotopes, (172)Yb, (174)Yb, and (176)Yb, and one odd isotope, (171)Yb, were clearly resolved. These data were compared with selective isotope excitation by 10 MHz linewidth continuous-wave dye laser. For 555.648 nm transition, isotopes were not clearly resolved, although isotope peaks of low modulation were observed.

Comparison of light absorption levels with different skin phantoms and the Monte Carlo simulation using Fourier-domain optical coherence tomography

NASA Astrophysics Data System (ADS)

Jo, Hang Chan; Kim, Jae Hun; Kim, Dae Yu

2018-02-01

Dermatologic patients have various skin characteristics such as skin tone and pigmentation color. However most studies on laser ablation and treatment only considered laser operating conditions like wavelength, output power and pulse duration. The laser ablation arises from photothermal effect by photon energy absorption. Chromophores like melanin exist as the absorber in the skin. In this study, we painted color to mimic chromophores on in-vivo and in-vitro skin models to demonstrate influence on the laser ablation by skin color. Water-based pens were used to paint color. Cross sectional images of the laser ablation were acquired by Fourier-domain optical coherence tomography (Fd-OCT). Light source to make ablation was a Q-switch diode-pumped Nd:YVO4 nanosecond laser (532nm central wavelength). Irradiated light energy dose of the laser could not make ablation craters in the control group. However experimental groups showed craters with same irradiation light energy dose. These results show painting on skin increased tissue damage by absorption in painted color without dyeing cells or tissues.

Laser treatments of deep-seated brain lesions

NASA Astrophysics Data System (ADS)

Ward, Helen A.

1997-06-01

The five year survival rate of deep-seated malignant brain tumors after surgery/radiotherapy is virtually 100 percent mortality. Special problems include: (1) Lesions often present late. (2) Position: lesion overlies vital structures, so complete surgical/radiotherapy lesion destruction can damage vital brain-stem functions. (3) Difficulty in differentiating normal brain form malignant lesions. This study aimed to use the unique properties of the laser: (a) to minimize damage during surgical removal of deep-seated brain lesions by operating via fine optic fibers; and (b) to employ the propensity of certain lasers for absorption of dyes and absorption and induction of fluorescence in some brain substances, to differentiate borders of malignant and normal brain, for more complete tumor removal. In the method a fine laser endoscopic technique was devised for removal of brain lesions. The results of this technique, were found to minimize and accurately predict the extent of thermal damage and shock waves to within 1-2mm of the surgical laser beam. Thereby it eliminated the 'popcorn' effect.

Portable IR dye laser optofluidic microresonator as a temperature and chemical sensor.

PubMed

Lahoz, F; Martín, I R; Gil-Rostra, J; Oliva-Ramirez, M; Yubero, F; Gonzalez-Elipe, A R

2016-06-27

A compact and portable optofluidic microresonator has been fabricated and characterized. It is based on a Fabry-Perot microcavity consisting essentially of two tailored dichroic Bragg mirrors prepared by reactive magnetron sputtering deposition. The microresonator has been filled with an ethanol solution of Nile-Blue dye. Infrared laser emission has been measured with a pump threshold as low as 0.12 MW/cm² and an external energy conversion efficiency of 41%. The application of the device as a temperature and a chemical sensor is demonstrated. Small temperature variations as well as small amount of water concentrations in the liquid laser medium are detected as a shift of the resonant laser modes.

Recent advance to 3 × 10(-5) rad near diffraction-limited beam divergence of dye laser with transverse-discharge flash-lamp pumping.

PubMed

Trusov, K K

1994-02-20

A new experimental setup of a Rhodamine 6G dye laser with a transverse-discharge flash-lamp-pumping system is presented. It differs from a previous setup [Sov. J. Quantum Electron. 16, 468-471 (1989)] in that it has a larger laser beam aperture (32 mm) and higher pumping energy (1 kJ), which made it possible to test the scalability and reach near diffraction-limited laser beam divergence of 3 × 10(-5) rad FWHM at beam energy 1.4 J. The effect of spectral dispersion in the active medium and of other optical elements on the beam divergence is also discussed.

Update on flashlamp pumped pulsed dye laser treatment for port wine stains (capillary malformation) patients

PubMed Central

Hsiao, Yen-Chang; Chang, Cheng-Jen

2011-01-01

Background and Aims: Currently, the method of choice for the treatment of port-wine stains is laser photocoagulation. Because of evolving treatment options, it is no longer enough for port-wine stains merely to be lightened through laser treatment. The best course of management consists of the most appropriate laser that will produce the most complete clearing of a lesion in the fewest treatment sessions with the least morbidity. The goal is generally accomplished with the use of yellow-light lasers. Materials (Subjects) and Methods: Absorption of laser energy by melanin causes localized heating in the epidermis, which may, if not controlled, produce permanent complications such as hypertrophic scarring or dyspigmentation. Refinements of the results can be achieved by using the flashlamp-pumped pulsed dye laser (FLPDL) in conjunction with the cryogen spray cooling (CSC) system. In our related studies, the infrared thermal image instrument is used for doctors in determining the optimum laser light dosage and preventing the side effects caused by FLPDL. Topic application of angiogenesis inhibitor (Imiquimod) in conjunction with pulsed dye laser treatment for the PWS patients has been assessed for improvement of FLPDL treatment. Results: We present the clinical effect of FLPDL, and the efficacy and safety of cooled laser treatment of PWS birthmarks. Our clinical outcome in the laser treatment of patients with PWS has been achieved to maximize thermal impact on targeted vessels, while minimizing adverse complications. Conclusions: CSC in conjunction with FLPDL can improve the treatment of PWS. The infrared image instrument is helpful for doctors in determining the optimum laser light dosage. Topic application of angiogenesis inhibitor (Imiquimod) in conjunction with laser treatment for the PWS patients is promising in the near future. PMID:24155536

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

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

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

2013-02-05

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

Laser synthesized super-hydrophobic conducting carbon with broccoli-type morphology as a counter-electrode for dye sensitized solar cells.

PubMed

Gokhale, Rohan; Agarkar, Shruti; Debgupta, Joyashish; Shinde, Deodatta; Lefez, Benoit; Banerjee, Abhik; Jog, Jyoti; More, Mahendra; Hannoyer, Beatrice; Ogale, Satishchandra

2012-11-07

A laser photochemical process is introduced to realize superhydrophobic conducting carbon coatings with broccoli-type hierarchical morphology for use as a metal-free counter electrode in a dye sensitized solar cell. The process involves pulsed excimer laser irradiation of a thin layer of liquid haloaromatic organic solvent o-dichlorobenzene (DCB). The coating reflects a carbon nanoparticle-self assembled and process-controlled morphology that yields solar to electric power conversion efficiency of 5.1% as opposed to 6.2% obtained with the conventional Pt-based electrode.

Fluorimetric studies and noncovalent labeling of protein with the near-infrared dye HITCI for analysis by CE-LIF.

PubMed

Yan, Weiying; Colyer, Christa L

2005-08-01

1,1',3,3,3',3'-Hexamethylindotricarbocyanine iodide (HITCI) is a commercially available, positively charged, indocarbocyanine dye used typically as a laser dye in the near infrared (NIR). The absorbance and fluorescence properties of HITCI in a variety of solvent systems were determined. Results indicate that the fluorescence of HITCI is not significantly affected by the pH. Titration of HITCI with human serum albumin (HSA) and trypsinogen was carried out to investigate the interactions between this dye and proteins. These studies revealed that the absorbance and fluorescence properties of the dye change upon binding to protein in a wide range of solution pH's. The potential use of HITCI as a noncovalent protein labeling probe, therefore, was explored. Determination and separation of HITCI and HITCI-protein complexes was performed by capillary electrophoresis with diode-laser induced fluorescence detection (CE-LIF). Both pre-column and on-column noncovalent labeling methods are demonstrated.

Fiber-Type Random Laser Based on a Cylindrical Waveguide with a Disordered Cladding Layer.

PubMed

Zhang, Wei Li; Zheng, Meng Ya; Ma, Rui; Gong, Chao Yang; Yang, Zhao Ji; Peng, Gang Ding; Rao, Yun Jiang

2016-05-25

This letter reports a fiber-type random laser (RL) which is made from a capillary coated with a disordered layer at its internal surface and filled with a gain (laser dye) solution in the core region. This fiber-type optical structure, with the disordered layer providing randomly scattered light into the gain region and the cylindrical waveguide providing confinement of light, assists the formation of random lasing modes and enables a flexible and efficient way of making random lasers. We found that the RL is sensitive to laser dye concentration in the core region and there exists a fine exponential relationship between the lasing intensity and particle concentration in the gain solution. The proposed structure could be a fine platform of realizing random lasing and random lasing based sensing.

Development of compact excimer lasers for remote sensing

NASA Technical Reports Server (NTRS)

Laudenslager, J. B.; Mcdermid, I. S.; Pacala, T. J.

1983-01-01

The capabilities of excimer lasers for remote sensing applications are illustrated in a discussion of the development of a compact tunable XeCl excimer laser for the detection of atmospheric OH radicals. Following a brief review of the operating principles and advantages of excimer lasers, measurements of the wavelength dependence of the net small signal gain coefficient of a discharge excited XeCl laser are presented which demonstrate the overlap of several absorption lines of the A-X(0,0) transition of OH near 308 nm with the wavelengths of the XeCl laser. A range of continuous narrow bandwidth tunability of from 307.6 to 308.4 nm with only a 30 percent variation in output is reported for an XeCl laser used as a double-pass amplifier for a frequency-doubled dye laser, and measurements demonstrating the detection of laser-induced fluorescence from OH in a methane-oxygen flame are also noted. The design of an oscillator-amplifier excimer system comprising a corona-preionized, transverse-discharge oscillator and amplifier is then presented. Output energies of 12-15 mJ have been achieved in the regions where injection locking was established, with energies of 8-10 mJ elsewhere.

Comparison study of a long-pulse pulsed dye laser and a long-pulse pulsed alexandrite laser in the treatment of port wine stains.

PubMed

Li, Li; Kono, Taro; Groff, William Frederick; Chan, Henry H; Kitazawa, Yoshihiko; Nozaki, Motohiro

2008-03-01

Port wine stains (PWSs) are commonly treated by the pulsed dye laser. Recently, a long-pulse pulsed alexandrite laser was used to treat bulky vascular malformations. In the present study, we compare the efficacy and complications of the long-pulse pulsed dye laser (LPPDL) and the long-pulse pulsed alexandrite laser (LPPAL) in the treatment of PWSs. Eleven patients with Fitzpatrick skin types III-IV were enrolled in this study. One section of each patient's PWS was treated with LPPDL and another section was treated with LPPAL. The patients' PWSs were evaluated for efficacy of elimination of erythema and for treatment-related side effects. Both LPPDL and LPPAL treatment are effective in the treatment of PWSs. Hyperpigmentation was seen in two areas treated with LPPDL and in three areas treated with LPPAL. Hypopigmentation was seen in one area treated with LPPAL, but not in any of the areas treated with LPPDL. There was no scarring. LPPAL works best with hypertrophic, purple PWSs, while LPPDL yields better clinical improvements with the flat, pink PWSs. Targeting of deoxyhemoglobin, deeper penetration, and higher fluence may explain the effectiveness of LPPAL in purple, hypertrophic PWSs. However, there is a risk of dyspigmentation when using the LPPAL.

Study of excitation transfer in laser dye mixtures by direct measurement of fluorescence lifetime

NASA Technical Reports Server (NTRS)

Lin, C.; Dienes, A.

1973-01-01

By directly measuring the donor fluorescence lifetime as a function of acceptor concentration in the laser dye mixture Rhodamine 6G-Cresyl violet, we found that the Stern-Volmer relation is obeyed, from which the rate of excitation transfer is determined. The experimental results indicate that the dominant mechanism responsible for the efficient excitation transfer is that of resonance transfer due to long range dipole-dipole interaction.

Spectral plasmonic effect in the nano-cavity of dye-doped nanosphere-based photonic crystals.

PubMed

Yadav, Ashish; Danesh, Mohammad; Zhong, Liubiao; Cheng, Gary J; Jiang, Lin; Chi, Lifeng

2016-04-22

We demonstrated three-dimensional PMMA-based photonic crystal (3D-PC) nanostructures attached to Au nanoparticles (AuNPs), which undergo self-organization into super lattice planes and enhance the fluorescence properties. This new structure exhibited interesting tunable spectral, peak broadening plasmonic behavior because of strong plasmonic interaction at high laser powers. The presented work provides an important tool to improve the efficiency of dye laser applications.

Azaquinolone dye lasers

DOEpatents

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

1978-01-01

A dye laser comprising a laser dye solution of a compound having the general structure: ##STR1## wherein at least one of the 5, 6 and 8 ring positions is occupied by a nitrogen atom in lieu of the corresponding CR group and X is OH, alkoxy, or amino including amino substituted by at least one of the following: alkyl, aryl, acyl, aracyl, a group which taken together with the nitrogen atom of the amino group forms a heterocyclic ring, or part of one or two 5 or 6 membered aliphatic heterocyclic rings attached to ring A at positions 6 or 8 or both depending on where the N in ring A is located. R.sub.1, R.sub.3, R.sub.4, R.sub.5, R.sub.6 and R.sub.8 are hydrogen or other groups as defined below. The compounds lase in the blue to near ultraviolet region.

Azacoumarin dye lasers

DOEpatents

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

1978-01-01

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

Stabilized Lasers and Precision Measurements.

ERIC Educational Resources Information Center

Hall, J. L.

1978-01-01

Traces the development of stabilized lasers from the Massachusetts Institute of Technology passive-stabilization experiments of the early 1960s up through the current epoch of highly stabilized helium-neon and carbon dioxide and continuous wave dye lasers. (Author/HM)

Pulsed dye laser double-pass treatment of patients with resistant capillary malformations.

PubMed

Rajaratnam, Ratna; Laughlin, Sharyn A; Dudley, Denis

2011-07-01

The pulsed dye laser is an effective and established treatment for port-wine stains and has become the generally accepted standard of care. However, in many cases, complete clearance cannot be achieved as a significant proportion of lesions become resistant to treatment. Multiple passes or pulse-stacking techniques have been used to improve the extent and rate of fading, but concerns over increased adverse effects have limited this clinical approach. In this work, a double-pass technique with the pulsed dye laser has been described, which may allow for increased depth of vascular injury, greater efficacy, and an acceptable risk profile. Our aim was to determine the efficacy and the rate of side-effects for a double-pass protocol with a pulsed dye laser (PDL) to treat patients previously treated with PDL and/or other laser modalities. A retrospective chart review was conducted of 26 patients treated with a minimum of three double-pass treatments alone, or in combination, with single pass conventional PDL. Almost half of the patients (n = 12) showed either a moderate or significant improvement in fading compared to pre-treatment photographs with the double-pass technique. In a further 12 patients, there was a mild improvement. In two patients, there was no change. Sixteen patients developed mild side-effects: blisters (n = 5), dry scabs (n = 11) and transient hyperpigmentation (n = 4). This preliminary experience suggests that a double-pass technique at defined intervals between the first and second treatment with PDL can further lighten some port-wine stains, which are resistant to conventional single-pass treatments. This technique may be a useful addition to the laser treatment of PWS and deserves further scrutiny with randomized prospective studies and histological analysis to confirm the increased depth of vascular injury.

Measuring evaporation rates of laser-trapped droplets by use of fluorescent morphology-dependent resonances.

PubMed

Pastel, R; Struthers, A

2001-05-20

Morphology-dependent resonances (MDRs) are used to measure accurately the evaporation rates of laser-trapped 1- to 2-mum droplets of ethylene glycol. Droplets containing 3 x 10(-5) M Rhodamine-590 laser dye are optically trapped in a 20-mum hollow fiber by two counterpropagating 150-mW, 800-nm laser beams. A weaker 532-nm laser excites the dye, and fluorescence emission is observed near 560 nm as the droplet evaporates. A complete series of first-order TE and TM MDRs dominates the fluorescent output. MDR mode identification sizes the droplets and provides accurate evaporation rates. We verify the automated MDR mode identification by counting fringes in a videotape of the experiment. The longitudinal spring constant of the trap, measured by analysis of the videotaped motion of droplets perturbed from the trap center, provides independent verification of the laser's intensity within the trap.

Measuring Evaporation Rates of Laser-Trapped Droplets by Use of Fluorescent Morphology-Dependent Resonances

NASA Astrophysics Data System (ADS)

Pastel, Robert; Struthers, Allan

2001-05-01

Morphology-dependent resonances (MDRs) are used to measure accurately the evaporation rates of laser-trapped 1- to 2- m droplets of ethylene glycol. Droplets containing 3 x10-5 M Rhodamine-590 laser dye are optically trapped in a 20- m hollow fiber by two counterpropagating 150-mW, 800-nm laser beams. A weaker 532-nm laser excites the dye, and fluorescence emission is observed near 560 nm as the droplet evaporates. A complete series of first-order TE and TM MDRs dominates the fluorescent output. MDR mode identification sizes the droplets and provides accurate evaporation rates. We verify the automated MDR mode identification by counting fringes in a videotape of the experiment. The longitudinal spring constant of the trap, measured by analysis of the videotaped motion of droplets perturbed from the trap center, provides independent verification of the laser s intensity within the trap.

An overview of clinical and experimental treatment modalities for port wine stains

PubMed Central

Chen, Jennifer K.; Ghasri, Pedram; Aguilar, Guillermo; van Drooge, Anne Margreet; Wolkerstorfer, Albert; Kelly, Kristen M.; Heger, Michal

2014-01-01

Port wine stains (PWS) are the most common vascular malformation of the skin, occurring in 0.3% to 0.5% of the population. Noninvasive laser irradiation with flashlamp-pumped pulsed dye lasers (selective photothermolysis) currently comprises the gold standard treatment of PWS; however, the majority of PWS fail to clear completely after selective photothermolysis. In this review, the clinically used PWS treatment modalities (pulsed dye lasers, alexandrite lasers, neodymium:yttrium-aluminum-garnet lasers, and intense pulsed light) and techniques (combination approaches, multiple passes, and epidermal cooling) are discussed. Retrospective analysis of clinical studies published between 1990 and 2011 was performed to determine therapeutic efficacies for each clinically used modality/technique. In addition, factors that have resulted in the high degree of therapeutic recalcitrance are identified, and emerging experimental treatment strategies are addressed, including the use of photodynamic therapy, immunomodulators, angiogenesis inhibitors, hypobaric pressure, and site-specific pharmaco-laser therapy. PMID:22305042

PHYSICAL EFFECTS OCCURRING DURING GENERATION AND AMPLIFICATION OF LASER RADIATION: Dynamics of population of the A3∑u+ nitrogen metastable state in a self-sustained volume discharge of a pulsed CO2 laser

NASA Astrophysics Data System (ADS)

Apollonov, V. V.; Baĭtsur, G. G.; Ermachenko, A. V.; Raspopov, N. A.; Sviridenkov, É. A.; Semenov, S. K.; Firsov, K. N.

1989-02-01

Intracavity laser spectroscopy was used to study the dynamics of population of the ν = 2-8 vibrational levels of the A3∑u+ state in order to establish the possible influence of multistage ionization on the evolution of instability in a self-sustained volume discharge in CO2 laser active mixtures. The populations of the nitrogen vibrational levels Nν were calculated taking into account the real output pulse profile of a dye laser. It was found that multistage ionization can only influence the duration of stable operation of a self-sustained volume discharge by increasing the rate of growth of the spark channel in the discharge gap. This is why the addition of readily ionized substances to the gas that reduce the electron energy and therefore lower Nν can substantially improve the stability of the volume discharge and increase the active volume and output energy of a CO2 laser.

UV laser interaction with a fluorescent dye solution studied using pulsed digital holography.

PubMed

Amer, Eynas; Gren, Per; Sjödahl, Mikael

2013-10-21

A frequency tripled Q-switched Nd-YAG laser (wavelength 355 nm, pulse duration 12 ns) has been used to pump Coumarin 153 dye solved in ethanol. Simultaneously, a frequency doubled pulse (532 nm) from the same laser is used to probe the solvent perpendicularly resulting in a gain through stimulated laser induced fluorescence (LIF) emission. The resulting gain of the probe beam is recorded using digital holography by blending it with a reference beam on the detector. Two digital holograms without and with the pump beam were recorded. Intensity maps were calculated from the recorded digital holograms and used to calculate the gain of the probe beam due to the stimulated LIF. In addition numerical data of the local temperature rise was calculated from the corresponding phase maps using Radon inversion. It was concluded that about 15% of the pump beam energy is transferred to the dye solution as heat while the rest is consumed in the radiative process. The results show that pulsed digital holography is a promising technique for quantitative study of fluorescent species.

Enhanced optical confinement of dye-doped dielectric nanoparticles using a picosecond-pulsed near-infrared laser

NASA Astrophysics Data System (ADS)

Kittiravechote, A.; Chiang, W.-Y.; Usman, A.; Liau, I.; Masuhara, H.

2014-07-01

We demonstrate a novel strategy to increase the capability of confining numerous dye-doped polymeric nanobeads (diameter 100 nm) with laser trapping. Unlike most classical works of optical trapping that address mainly the stiffness of the optical trap, our work concerns an increase in the number of particles confined near the laser focus. We developed an imaging system of light scattering in which a condenser lamp was employed to illuminate the focal plane of the objective lens, and the scattering of the incoherent light was specifically measured to determine the number of confined nanobeads. In contrast to preceding work that used mainly continuous-wave or femtosecond-pulsed lasers, we employed a picosecond-pulsed laser with the half-wavelength of the laser particularly falling within the absorption band of the dopant. Our results show that the number of doped nanobeads held by the laser is significantly greater than that of the bare nanobeads of the same dimension. In striking contrast, the confinement of the nanobeads of the two types was comparable when a continuous-wave laser of the same wavelength and power was employed. The number of confined dye-doped nanobeads increased nonlinearly with the power of the pulsed laser; this dependence was fitted satisfactorily with a second-order polynomial. Supported by theoretical analysis, we attribute the enhanced confinement of doped nanobeads in part to an increased effective refractive index resulting from two-photon resonance between the optical field of the laser and the dopant of the nanobead. We envisage that our findings would evoke applications that benefit from controlled confinement or aggregation of nanomaterials with the employment of near-infrared pulsed lasers.

Pulsed-Dye Laser Treatment of Port-Wine Stains in Children: Useful Tips to Avoid General Anesthesia.

PubMed

Alegre-Sánchez, Adrián; Pérez-García, Bibiana; Boixeda, Pablo

2017-09-01

Pulsed dye laser (PDL) treatment of port-wine stains (PWSs) in children is a common procedure performed in most laser units. Pain assessment in our younger patients is a major concern, especially in those with extensive PWSs. The use of general anesthesia (GA) results in pain-free treatment, but its effects on the developing brain are far from totally understood. Thus we propose some tips that avoid the use of GA in most of our young patients, including the use of topical anesthetics and cooling systems, large laser spot size and high frequencies, early and frequent treatment with parents present, and the "introduction" and "pressure" techniques, among others. © 2017 Wiley Periodicals, Inc.

Coumarin-BODIPY hybrids by heteroatom linkage: versatile, tunable and photostable dye lasers for UV irradiation.

PubMed

Esnal, I; Duran-Sampedro, G; Agarrabeitia, A R; Bañuelos, J; García-Moreno, I; Macías, M A; Peña-Cabrera, E; López-Arbeloa, I; de la Moya, S; Ortiz, M J

2015-03-28

Linking amino and hydroxycoumarins to BODIPYs through the amino or hydroxyl group lets the easy construction of unprecedented photostable coumarin-BODIPY hybrids with broadened and enhanced absorption in the UV spectral region, and outstanding wavelength-tunable laser action within the green-to-red spectral region (∼520-680 nm). These laser dyes allow the generation of a valuable tunable UV (∼260-350 nm) laser source by frequency doubling, which is essential to study accurately the photochemistry of biological molecules under solar irradiation. The tunability is achieved by selecting the substitution pattern of the hybrid. Key factors are the linking heteroatom (nitrogen vs. oxygen), the number of coumarin units joined to the BODIPY framework and the involved linking positions.

Laser tissue welding mediated with a protein solder

NASA Astrophysics Data System (ADS)

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

1996-05-01

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

Pulse Width Dependence Of Pigment Cell Damage At 694 nm In Guinea Pig Skin

NASA Astrophysics Data System (ADS)

Dover, Jeffrey S.; Polla, Luigi L.; Margolis, Randall J.; Whitaker, Diana; Watanabe, Schinichi; Murphy, George F.; Parrish, John A.; Anderson, R. R.

1987-03-01

351 nm, 20-nsec XeF excimer laser irradiation has previously been shown to selectively target and damage melanosomes in human skin. In the following studies selective targeting with melanosomal photodisruption has been demonstrated in pigmented guinea pig skin with a Q-switched 40-nsec ruby laser, and a 750-nsec pulsed dye laser but not with a 400-usec pulsed dye laser. The pulse width dependence of melanosomal disruption, occurring only at pulsewidths shorter than the thermal relaxation time of the melanosome (0.5 - 1.0 usec), is in accordance with the theory of selective photothermolysis. Possible mechanisms of melanosomal photodisruption include development of sudden thermal gradients leading to cavitation or shock wave production.

Development of a see-through hollow cathode discharge lamp for (Li/Ne) optogalvanic studies

NASA Astrophysics Data System (ADS)

Saini, V. K.; Kumar, P.; Sarangpani, K. K.; Dixit, S. K.; Nakhe, S. V.

2017-09-01

Development of a demountable and see-through hollow cathode (HC) discharge lamp suitable for optogalvanic (OG) spectroscopy is described. The design of the HC lamp is simple, compact, and inexpensive. Lithium, investigated rarely by the OG method, is selected for cathode material as its isotopes are important for nuclear industry. The HC lamp is characterized electrically and optically for discharge oscillations free OG effect. Strong OG signals of lithium as well as neon (as buffer gas) are produced precisely upon copper vapor laser pumped tunable dye laser irradiation. The HC lamp is capable of generating a clean OG resonance spectrum in the available dye laser wavelength scanning range (627.5-676 nm) obtained with 4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran dye. About 28 resonant OG lines are explicitly observed. Majority of them have been identified using j-l coupling scheme and assigned to the well-known neon transitions. One line that corresponds to wavelength near about 670.80 nm is assigned to lithium and resolved for its fine (2S1/2 → 2P1/2, 3/2) transitions. These OG transitions allow 0.33 cm-1 accuracy and can be used to supplement the OG transition data available from other sources to calibrate the wavelength of a scanning dye laser with precision at atomic levels.

Development of a see-through hollow cathode discharge lamp for (Li/Ne) optogalvanic studies.

PubMed

Saini, V K; Kumar, P; Sarangpani, K K; Dixit, S K; Nakhe, S V

2017-09-01

Development of a demountable and see-through hollow cathode (HC) discharge lamp suitable for optogalvanic (OG) spectroscopy is described. The design of the HC lamp is simple, compact, and inexpensive. Lithium, investigated rarely by the OG method, is selected for cathode material as its isotopes are important for nuclear industry. The HC lamp is characterized electrically and optically for discharge oscillations free OG effect. Strong OG signals of lithium as well as neon (as buffer gas) are produced precisely upon copper vapor laser pumped tunable dye laser irradiation. The HC lamp is capable of generating a clean OG resonance spectrum in the available dye laser wavelength scanning range (627.5-676 nm) obtained with 4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran dye. About 28 resonant OG lines are explicitly observed. Majority of them have been identified using j-l coupling scheme and assigned to the well-known neon transitions. One line that corresponds to wavelength near about 670.80 nm is assigned to lithium and resolved for its fine ( 2 S 1/2 → 2 P 1/2, 3/2 ) transitions. These OG transitions allow 0.33 cm -1 accuracy and can be used to supplement the OG transition data available from other sources to calibrate the wavelength of a scanning dye laser with precision at atomic levels.

Elucidation of Free Radical and Optogalvanic Spectroscopy Associated with Microgravity Combustion via Conventional and Novel Laser Platforms

NASA Technical Reports Server (NTRS)

Misra, Prabhakar; She, Yong-Bo; Zhu, Xin-Ming; King, Michael

1997-01-01

Combustion studies under both normal gravity and microgravity conditions depend a great deal on the availability and quality of the diagnostic systems used for such investigations. Microgravity phenomena are specially susceptible to even small perturbations and therefore non-intrusive diagnostic techniques are of paramount importance for successful understanding of reduced-gravity combustion phenomena. Several non-intrusive diagnostic techniques are available for probing and delineating normal as well as reduced gravity combustion processes, such as Rayleigh scattering, Raman scattering, Mie scattering, velocimetry, interferometric and Schlieren techniques, emission and laser-induced fluorescence (LIF) spectroscopy. Our approach is to use the LIF technique as a non-intrusive diagnostic tool for the study of combustion-associated free radicals and use the concomitant optogalvanic transitions to accomplish precise calibration of the laser wavelengths used for recording the excitation spectra of transient molecular species. In attempting to perform spectroscopic measurements on chemical intermediates, we have used conventional laser sources as well as new and novel platforms employing rare-earth doped solid-state lasers. Conventional (commercially available) sources of tunable UV laser radiation are extremely cumbersome and energy-consuming devices that are not very suitable for either in-space or in-flight (or microgravity drop tower) experiments. Traditional LIF sources of tunable UV laser radiation involve in addition to a pump laser (usually a Nd:YAG laser with an attached frequency-doubling stage), a tunable dye laser. In turn, the dye laser has to be provided with a dye circulation system and a subsequent stage for frequency-doubling of the dye laser radiation, together with a servo-tuning system (termed the 'Autotracker') to follow the wavelength changes and also an optical system (called the 'Frequency Separator') for separation of the emanating visible and UV beams. In contrast to this approach, we have devised an alternate arrangement for recording LIF excitation spectra of free radicals (following appropriate precursor fragmentation) that utilizes a tunable rare-earth doped solid state laser system with direct UV pumping. We have designed a compact and portable tunable UV laser system incorporating features necessary for both in-space and in-flight spectroscopy experiments. For the purpose of LIF excitation, we have developed an all-solid-state tunable UV laser that employs direct pumping of the solid-state UV-active medium employing UV harmonics from a Nd:YAG laser. An optical scheme with counterpropagating photolysis and excitation beams focused by suitable lenses into a reaction vacuum chamber was employed.

Fast photocatalytic degradation of methylene blue dye using a low-power diode laser.

PubMed

Liu, Xianhua; Yang, Yulou; Shi, Xiaoxuan; Li, Kexun

2015-01-01

This study focused on the application of diode lasers as alternative light sources for the fast photocatalytic degradation of methylene blue. The photocatalytic decomposition of methylene blue in aqueous solution under 443 nm laser light irradiation was found to be technically feasible using Ag/AgCl nanoparticles as photocatalysts. The effects of various experimental parameters, such as irradiation time, light source, catalyst loading, initial dye concentration, pH, and laser energy on decolorization and degradation were investigated. The mineralization of methylene blue was confirmed by chemical oxygen demand analysis. The results demonstrate that the laser-induced photocatalytic process can effectively degrade methylene blue under the optimum conditions (pH 9.63, 4 mg/L MB concentration, and 1.4 g/L Ag/AgCl nanoparticles). Copyright © 2014 Elsevier B.V. All rights reserved.

Physical and chemical investigations on natural dyes

NASA Astrophysics Data System (ADS)

Acquaviva, S.; D'Anna, E.; de Giorgi, M. L.; Della Patria, A.; Baraldi, P.

2010-09-01

Natural dyes have been used extensively in the past for many purposes, such us to colour fibers and to produce inks, watercolours and paints, but their use declined rapidly after the discovery of synthetic colours. Nowadays we witness a renewed interest, as natural dyes are neither toxic nor polluting. In this work, physical and chemical properties of four selected dyes, namely red (Madder), yellow (Weld and Turmeric) and blue (Woad) colours, produced by means of traditional techniques at the Museo dei Colori Naturali (Lamoli, Italy), have been investigated. The chromatic properties have been studied through the reflectance spectroscopy, a non-invasive technique for the characterisation of chromaticity. Reflection spectra both from powders and egg-yolk tempera models have been acquired to provide the typical features of the dyes in the UV-vis spectral range. Moreover, to assess the feasibility of laser cleaning procedures, tempera layers were investigated after irradiation with an excimer laser. Micro Raman spectroscopy, Scanning Electron Microscopy and Energy Dispersive X-Ray analyses have complemented the survey, returning compositional and morphological information as well. Efforts have been made to give scientific feedback to the production processes and to support the research activity in the restoration of the artworks where these dyes were employed.

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

NASA Technical Reports Server (NTRS)

Wang, Charles P. (Editor)

1993-01-01

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

The Diatom Staurosirella pinnata for Photoactive Material Production

PubMed Central

Prosposito, Paolo; Casalboni, Mauro; Lamastra, Francesca Romana; Nanni, Francesca; Congestri, Roberta

2016-01-01

A native isolate of the colonial benthic diatom Staurosirella pinnata was cultivated for biosilica production. The silicified cell walls (frustules) were used as a source of homogeneous and structurally predictable porous biosilica for dye trapping and random laser applications. This was coupled with the extraction of lipids from biomass showing potential to fabricate photoactive composite materials sustainably. The strain was selected for its ease of growth in culture and harvesting. Biosilica and lipids were obtained at the end of growth in indoor photobioreactors. Frustules were structurally characterized microscopically and their chemistry analyzed with Fourier Transform Infrared Spectroscopy. Frustule capacity of binding laser dyes was evaluated on a set of frustules/Rhodamine B (Rho B) solutions and with respect to silicon dioxide and diatomite by Fluorescence Spectroscopy demonstrating a high affinity for the organic dye. The effect of dye trapping property in conveying Rho B emission to frustules, with enhancement of scattering events, was analyzed on Rho B doped polyacrylamide gels filled or not with frustules. Amplified spontaneous emission was recorded at increasing pump power indicating the onset of a random laser effect in frustule filled gels at lower power threshold compared to unfilled matrices. PMID:27828985

Method for changing the cross section of a laser beam

DOEpatents

Sweatt, W.C.; Seppala, L.

1995-12-05

A technique is disclosed herein in which a circular optical beam, for example a copper vapor laser (CVL) beam, is converted to a beam having a profile other than circular, e.g. square or triangular. This is accomplished by utilizing a single optical mirror having a reflecting surface designed in accordance with a specifically derived formula in order to make the necessary transformation, without any substantial light loss and without changing substantially the intensity profile of the circular beam which has a substantially uniform intensity profile. In this way, the output beam can be readily directed into the dye cell of a dye laser. 4 figs.

Optical bending sensor using distributed feedback solid state dye lasers on optical fiber.

PubMed

Kubota, Hiroyuki; Oomi, Soichiro; Yoshioka, Hiroaki; Watanabe, Hirofumi; Oki, Yuji

2012-07-02

Novel type of optical fiber sensor was proposed and demonstrated. The print-like fabrication technique fabricates multiple distributed feedback solid state dye lasers on a polymeric optical fiber (POF) with tapered coupling. This multi-active-sidecore structure was easily fabricated and provides multiple functions. Mounting the lasers on the same point of a multimode POF demonstrated a bending radius sensitivity of 20 m without any supports. Two axis directional sensing without cross talk was also confirmed. A more complicated mounting formation can demonstrate a twisted POF. The temperature property of the sensor was also studied, and elimination of the temperature influence was experimentally attained.

Method for changing the cross section of a laser beam

DOEpatents

Sweatt, William C.; Seppala, Lynn

1995-01-01

A technique is disclosed herein in which a circular optical beam, for example a copper vapor laser (CVL) beam, is converted to a beam having a profile other than circular, e.g. square or triangular. This is accomplished by utilizing a single optical mirror having a reflecting surface designed in accordance with a specifically derived formula in order to make the necessary transformation, without any substantial light loss and without changing substantially the intensity profile of the circular beam which has a substantially uniform intensity profile. In this way, the output beam can be readily directed into the dye cell of a dye laser.

The discrimination of colored acrylic, cotton, and wool textile fibers using micro-Raman spectroscopy. Part 1: in situ detection and characterization of dyes.

PubMed

Buzzini, Patrick; Massonnet, Genevieve

2013-11-01

Raman spectroscopy has been applied to characterize fiber dyes and determine the discriminating ability of the method. Black, blue, and red acrylic, cotton, and wool samples were analyzed. Four excitation sources were used to obtain complementary responses in the case of fluorescent samples. Fibers that did not provide informative spectra using a given laser were usually detected using another wavelength. For any colored acrylic, the 633-nm laser did not provide Raman information. The 514-nm laser provided the highest discrimination for blue and black cotton, but half of the blue cottons produced noninformative spectra. The 830-nm laser exhibited the highest discrimination for red cotton. Both visible lasers provided the highest discrimination for black and blue wool, and NIR lasers produced remarkable separation for red and black wool. This study shows that the discriminating ability of Raman spectroscopy depends on the fiber type, color, and the laser wavelength. © 2013 American Academy of Forensic Sciences.

Electrically tunable laser based on heliconical cholesteric (Conference Presentation)

NASA Astrophysics Data System (ADS)

Xiang, Jie; Varanytsia, Andrii; Minkowski, Fred; Paterson, Daniel A.; Imrie, Corrie T.; Lavrentovich, Oleg D.; Palffy-Muhoray, Peter

2016-09-01

STUDENT CONTRIBUTION: Cholesteric liquid crystals (CLC) self-assemble into a periodic supramolecular helical structure with properties of a one-dimensional photonic crystal. The CLCs doped with a fluorescent dye and optical pump enable a distributed feedback cavity and lasing [1]. Although lasing was observed in range of wavelength from near UV to near IR, a practical method of tuning of emission wavelength from a dye-doped CLC without structural destruction of a helix is not demonstrated yet. In this work, we demonstrate an electrically tunable dye-doped CLC laser based on the so-called oblique helicoidal, or heliconical, CLC state [2,3]. In this state, the molecules twist around the helicoidal axis, making an angle smaller than 90 degrees with the axis. Molecular tilt makes the heliconical structure different from the regular CLC (in which the molecules are perpendicular to the axis) and enable electric tunability [2,3]. An electric field applied parallel to the heliconical axis changes the pitch but does not realign the axis. When the field increases, the pitch decreases. As a result, the selective reflection band and a lasing wavelength move towards shorter wavelength. Using heliconical CLC and two laser dyes DCM and LD688, we demonstrate effective tuning of the laser emission wavelength from 574 nm to 722 nm. With appropriate laser dyes, the spectrum can be extended from near UV to near IR. Efficient electric tuning in the broad spectral range and small size of the heliconical cholesteric lasers makes them potentially useful for optical and biomedical applications. [1] P. Palffy-Muhoay, W.Y. Cao, M. Moreira, B. Taheri, A. Munoz, Photonics and lasing in liquid crystal [2] J. Xiang, S.V. Shiyanovskii, C.T. Imrie, O.D. Lavrentovich, Electrooptic Response of Chiral Nematic Liquid Crystals with Oblique Helicoidal Director, Phys Rev Lett, 112 (2014) 217801. [3] J. Xiang, Y.N. Li, Q. Li, D.A. Paterson, J.M.D. Storey, C.T. Imrie, O.D. Lavrentovich, Electrically Tunable Selective Reflection of Light from Ultraviolet to Visible and Infrared by Heliconical Cholesterics, Adv Mater, 27 (2015) 3014-3018.

Laser therapy in plastic surgery: decolorization in port wine stains

NASA Astrophysics Data System (ADS)

Peszynski-Drews, Cezary; Wolf, Leszek

1996-03-01

For the first time laserotherapy is described as a method of port wine stain decolorization in plastic surgery. The authors present their 20-year experience in the treatment of port wine stains with the argon laser and dye laser.

Four generations of sodium guide star lasers for adaptive optics in astronomy and space situational awareness

NASA Astrophysics Data System (ADS)

d'Orgeville, Céline; Fetzer, Gregory J.

2016-07-01

This paper recalls the history of sodium guide star laser systems used in astronomy and space situational awareness adaptive optics, analyzing the impact that sodium laser technology evolution has had on routine telescope operations. While it would not be practical to describe every single sodium guide star laser system developed to date, it is possible to characterize their evolution in broad technology terms. The first generation of sodium lasers used dye laser technology to create the first sodium laser guide stars in Hawaii, California, and Spain in the late 1980s and 1990s. These experimental systems were turned into the first laser guide star facilities to equip mediumto- large diameter adaptive optics telescopes, opening a new era of Laser Guide Star Adaptive Optics (LGS AO)-enabled diffraction-limited imaging from the ground. Although they produced exciting scientific results, these laser guide star facilities were large, power-hungry and messy. In the USA, a second-generation of sodium lasers was developed in the 2000s that used cleaner, yet still large and complex, solid-state laser technology. These are the systems in routine operation at the 8 to 10m-class astronomical telescopes and 4m-class satellite imaging facilities today. Meanwhile in Europe, a third generation of sodium lasers was being developed using inherently compact and efficient fiber laser technology, and resulting in the only commercially available sodium guide star laser system to date. Fiber-based sodium lasers are being or will soon be deployed at three astronomical telescopes and two space surveillance stations. These highly promising systems are still relatively large to install on telescopes and they remain significantly expensive to procure and maintain. We are thus proposing to develop a fourth generation of sodium lasers: based on semiconductor technology, these lasers could provide a definitive solution to the problem of sodium LGS AO laser sources for all astronomy and space situational awareness applications.

Luminescence enhancement in nanocomposite consisting of polyvinyl alcohol incorporated gold nanoparticles and Nile blue 690 perchlorate.

PubMed

Chubinidze, Ketevan; Partsvania, Besarion; Sulaberidze, Tamaz; Khuskivadze, Aleksandre; Davitashvili, Elene; Koshoridze, Nana

2014-11-01

We have experimentally demonstrated that the emission of visible light from the polymer matrix doped with luminescent dye and gold nanoparticles (GNPs) can be enhanced with the use of surface plasmon coupling. GNPs can enhance the luminescence intensity of nearby luminescent dye because of the interactions between the dipole moments of the dye and the surface plasmon field of the GNPs. The electric charge on the GNPs and the distance between GNPs and luminescent dye molecules have a significant effect on the luminescence intensity, and this enhancement depends strongly upon the excitation wavelength of the pumping laser source. In particular, by matching the plasmon frequency of GNPs to the frequency of the laser light source we have observed a strong luminescence enhancement of the nanocomposite consisting of GNPs coupled with luminescent dye Nile blue 690 perchlorate. This ability of controlling luminescence can be beneficially used in developing contrast agents for highly sensitive and specific optical sensing and imaging. This opens new possibilities for plasmonic applications in the solar energy field.

New laser media based on microporous glasses

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

Altshuler, G.B.; Bakanov, V.A.; Dulneva, E.G.

The results of the investigation of new class of the laser media based on dye solutions impregnated microporous glasses are presented. Based on such media highly effective active elements of tunable dye lasers and passive modulators for solid-state lasers are created. This article is devoted to laser media of the new type - the heterogenous solid-liquid media on the basis of the impregnated by the solutions of the dyes of the microporous glasses. The microporous glasses represent themselves the products of the leaching of heat - treated sodium borosilicate glasses of a certain composition range. As a result of heatmore » treatment is realized the phase separated glass. It consists of two interconnected phases: the silica rich phase and the chemical unstable sodium - borate - rich phase. If we place this glass in the acid then the ions of sodium and borate will be transfered to the solution. As a result we obtain the porous glass and this process produces the continuous claster. Therefore it could be easily impregnated by liquids and gases. We now have the technology that permits us to obtain the samples with the volume porosity from ten to fifty percent and the size of this poroses could be varied from twenty angstroms up to one thousand angstroms.« less

Laser synthesized super-hydrophobic conducting carbon with broccoli-type morphology as a counter-electrode for dye sensitized solar cells

NASA Astrophysics Data System (ADS)

Gokhale, Rohan; Agarkar, Shruti; Debgupta, Joyashish; Shinde, Deodatta; Lefez, Benoit; Banerjee, Abhik; Jog, Jyoti; More, Mahendra; Hannoyer, Beatrice; Ogale, Satishchandra

2012-10-01

A laser photochemical process is introduced to realize superhydrophobic conducting carbon coatings with broccoli-type hierarchical morphology for use as a metal-free counter electrode in a dye sensitized solar cell. The process involves pulsed excimer laser irradiation of a thin layer of liquid haloaromatic organic solvent o-dichlorobenzene (DCB). The coating reflects a carbon nanoparticle-self assembled and process-controlled morphology that yields solar to electric power conversion efficiency of 5.1% as opposed to 6.2% obtained with the conventional Pt-based electrode.A laser photochemical process is introduced to realize superhydrophobic conducting carbon coatings with broccoli-type hierarchical morphology for use as a metal-free counter electrode in a dye sensitized solar cell. The process involves pulsed excimer laser irradiation of a thin layer of liquid haloaromatic organic solvent o-dichlorobenzene (DCB). The coating reflects a carbon nanoparticle-self assembled and process-controlled morphology that yields solar to electric power conversion efficiency of 5.1% as opposed to 6.2% obtained with the conventional Pt-based electrode. Electronic supplementary information (ESI) available: Materials and equipment details, solar cell fabrication protocol, electrolyte spreading time measurement details, XPS spectra, electronic study, film adhesion test detailed analysis and field emission results. See DOI: 10.1039/c2nr32082g

Optoelectronic and photoacoustic studies of an organic dye synthesized through green route

NASA Astrophysics Data System (ADS)

Vijayakumar, S.; Sreelatha, S.; Hatamimoslehabadi, M.; Yelleswarappu, C. S.

2017-10-01

An azo dye was prepared through an environmentally benign and economically feasible synthesis route with cardanol as a starting material. Cardanol is a cost-effective and renewable natural source obtained from Cashew Nut Shell Liquid, a by-product of the cashew industry. The dye was spectrally characterized by IR, UV-Vis, NMR and fluorescence studies. UV-Vis absorption showed a bathochromic shift between solvents of lower and higher polarities. Nonlinear optical and photoacoustic properties were studied using a frequency doubled Nd:YAG laser producing 532 nm laser pulses of 3 ns pulse width. Results show that the nonlinear absorption coefficient decreases with the increase of on-axis intensity, suggesting excited state absorption as the principal mechanism. The observed nonlinearity has applications in optoelectronics.

Blue diode-pumped solid-state-laser based on ytterbium doped laser crystals operating on the resonance zero-phonon transition

DOEpatents

Krupke, William F.; Payne, Stephen A.; Marshall, Christopher D.

2001-01-01

The invention provides an efficient, compact means of generating blue laser light at a wavelength near .about.493+/-3 nm, based on the use of a laser diode-pumped Yb-doped laser crystal emitting on its zero phonon line (ZPL) resonance transition at a wavelength near .about.986+/-6 nm, whose fundamental infrared output radiation is harmonically doubled into the blue spectral region. The invention is applied to the excitation of biofluorescent dyes (in the .about.490-496 nm spectral region) utilized in flow cytometry, immunoassay, DNA sequencing, and other biofluorescence instruments. The preferred host crystals have strong ZPL fluorecence (laser) transitions lying in the spectral range from .about.980 to .about.992 nm (so that when frequency-doubled, they produce output radiation in the spectral range from 490 to 496 nm). Alternate preferred Yb doped tungstate crystals, such as Yb:KY(WO.sub.4).sub.2, may be configured to lase on the resonant ZPL transition near 981 nm (in lieu of the normal 1025 nm transition). The laser light is then doubled in the blue at 490.5 nm.

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

NASA Astrophysics Data System (ADS)

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

2016-03-01

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

Light amplification and lasing from dyes doped in DNA-complex thin films prepared by soaking method

NASA Astrophysics Data System (ADS)

Kawabe, Yutaka; Suzuki, Takemasa; Iisaka, You

2014-08-01

An alternative fabrication method for dye-doped DNA-surfactant complex films was developed and amplified spontaneous emission (ASE) and lasing under low energy optical pumping were demonstrated. In this new preparation technique, thin DNA-cethyltrimethylammonium (CTMA) complex films made by a spin coating method were stained with a hemicyanine dye by soaking them in acetone solution of the dye for one day. Molar ratio of the dye to DNA base pair for the final products was estimated to be 0.2, the value was much higher than those achieved via usual mixing method. ASE threshold value under pumping of a pulsed frequency-doubled YAG laser was about 0.3 mJ/cm2. Laser emission was also attained under the excitation with two interfering beams forming a dynamic grating of gain coefficient. Durability test indicated that 70% of their initial performance was maintained after 1 hour of continuous pumping. The technique was applied to water soluble dyes because the DNA complex was insoluble to water as well as acetone. We employed anionic Eosin Y dye, succeeding in sample formation and ASE emission. Different types of surfactants were also complexed with DNA, showing variation of emission peak wavelength. These results give a clue about the structure of the complex or interaction modes between DNA and surfactants, strongly suggesting that dye molecules are not intercalated into nor bound to DNA double strand directly, but are incorporated in the complex system via ion-exchange process or aggregating with cationic surfactants.

Automated Lab-on-a-Chip Electrophoresis System

NASA Technical Reports Server (NTRS)

Willis, Peter A.; Mora, Maria; Greer, Harold F.; Fisher, Anita M.; Bryant, Sherrisse

2012-01-01

Capillary electrophoresis is an analytical technique that can be used to detect and quantify extremely small amounts of various biological molecules. In the search for biochemical traces of life on other planets, part of this search involves an examination of amino acids, which are the building blocks of life on Earth. The most sensitive method for detecting amino acids is the use of laser induced fluorescence. However, since amino acids do not, in general, fluoresce, they first must be reacted with a fluorescent dye label prior to analysis. After this process is completed, the liquid sample then must be transported into the electrophoresis system. If the system is to be reused multiple times, samples must be added and removed each time. In typical laboratories, this process is performed manually by skilled human operators using standard laboratory equipment. This level of human intervention is not possible if this technology is to be implemented on extraterrestrial targets. Microchip capillary electrophoresis (CE) combined with laser induced fluorescence detection (LIF) was selected as an extremely sensitive method to detect amino acids and other compounds that can be tagged with a fluorescent dye. It is highly desirable to package this technology into an integrated, autonomous, in situ instrument capable of performing CE-LIF on the surface of an extraterrestrial body. However, to be fully autonomous, the CE device must be able to perform a large number of sample preparation and analysis operations without the direct intervention of a human.

Determination of dye/protein ratios in a labeling reaction between a cyanine dye and bovine serum albumin by micellar electrokinetic chromatography using a diode laser-induced fluorescence detection.

PubMed

Jing, Peng; Kaneta, Takashi; Imasaka, Totaro

2002-08-01

The degree of labeling, i.e., dye/protein ratio (D/P) is important for characterizing properties of dye labeling with proteins. A method for the determination of this ratio between a fluorescent cyanine dye and bovine serum albumin (BSA), based on the separation of the labeling mixture using micellar electrokinetic chromatography with diode laser-induced fluorescence detection, is described. Two methods for the determination of D/P were examined in this study. In these methods, a hydrolysis product and impurities, which are usually unfavorable compounds that are best excluded for protein analysis, were utilized to determine the amounts of dye bound to BSA. One is a direct method in which a ratio of the peak area of BSA to the total peak area of all the products produced in the labeling reaction was used for determining the average number of dye molecules bound to a single BSA molecule. The other is an indirect determination, which is based on diminution of all peak areas related to the products except for the labeled BSA. These methods were directly compared by means of a spectrophotometric method. The experimental results show that the indirect method is both reliable and sensitive. Therefore, D/P values can be determined at trace levels using the indirect method.

Unconventional High-Performance Laser Protection System Based on Dichroic Dye-Doped Cholesteric Liquid Crystals

NASA Astrophysics Data System (ADS)

Zhang, Wanshu; Zhang, Lanying; Liang, Xiao; Le Zhou; Xiao, Jiumei; Yu, Li; Li, Fasheng; Cao, Hui; Li, Kexuan; Yang, Zhou; Yang, Huai

2017-02-01

High-performance and cost-effective laser protection system is of crucial importance for the rapid advance of lasers in military and civilian fields leading to severe damages of human eyes and sensitive optical devices. However, it is crucially hindered by the angle-dependent protective effect and the complex preparation process. Here we demonstrate that angle-independence, good processibility, wavelength tunability, high optical density and good visibility can be effectuated simultaneously, by embedding dichroic anthraquinone dyes in a cholesteric liquid crystal matrix. More significantly, unconventional two-dimensional parabolic protection behavior is reported for the first time that in stark contrast to the existing protection systems, the overall parabolic protection behavior enables protective effect to increase with incident angles, hence providing omnibearing high-performance protection. The protective effect is controllable by dye concentration, LC cell thickness and CLC reflection efficiency, and the system can be made flexible enabling applications in flexible and even wearable protection devices. This research creates a promising avenue for the high-performance and cost-effective laser protection, and may foster the development of optical applications such as solar concentrators, car explosion-proof membrane, smart windows and polarizers.

Synthesis and characterization of gold graphene composite with dyes as model substrates for decolorization: A surfactant free laser ablation approach

NASA Astrophysics Data System (ADS)

Sai Siddhardha, R. S.; Lakshman Kumar, V.; Kaniyoor, Adarsh; Sai Muthukumar, V.; Ramaprabhu, S.; Podila, Ramakrishna; Rao, A. M.; Ramamurthy, Sai Sathish

2014-12-01

A facile surfactant free laser ablation mediated synthesis (LAMS) of gold-graphene composite is reported here. The material was characterized using transmission electron microscopy, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, powdered X-ray diffraction, Raman spectroscopy, Zeta potential measurements and UV-Visible spectroscopic techniques. The as-synthesized gold-graphene composite was effectively utilized as catalyst for decolorization of 4 important textile and laser dyes. The integration of gold nanoparticles (AuNPs) with high surface area graphene has enhanced the catalytic activity of AuNPs. This enhanced activity is attributed to the synergistic interplay of pristine gold's electronic relay and π-π stacking of graphene with the dyes. This is evident when the Rhodamine B (RB) reduction rate of the composite is nearly twice faster than that of commercial citrate capped AuNPs of similar size. In case of Methylene blue (MB) the rate of reduction is 17,000 times faster than uncatalyzed reaction. This synthetic method opens door to laser ablation based fabrication of metal catalysts on graphene for improved performance without the aid of linkers and surfactants.

Synthetic thrombus model for in vitro studies of laser thrombolysis

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

Hermes, R.E.; Trajkovska, K.

1998-07-01

Laser thrombolysis is the controlled ablation of a thrombus (blood clot) blockage in a living arterial system. Theoretical modeling of the interaction of laser light with thrombi relies on the ability to perform in vitro experiments with well characterized surrogate materials. A synthetic thrombus formulation may offer more accurate results when compared to in vivo clinical experiments. The authors describe the development of new surrogate materials based on formulations incorporating chick egg, guar gum, modified food starch, and a laser light absorbing dye. The sound speed and physical consistency of the materials were very close to porcine (arterial) and humanmore » (venous) thrombi. Photographic and videotape recordings of pulsed dye laser ablation experiments under various experimental conditions were used to evaluate the new material as compared to in vitro tests with human (venous) thrombus. The characteristics of ablation and mass removal were similar to that of real thrombi, and therefore provide a more realistic model for in vitro laser thrombolysis when compared to gelatin.« less

Vitamin C for stabilising biological lasers (Conference Presentation)

NASA Astrophysics Data System (ADS)

Kar, Ajoy K.; Mackenzie, Mark D.; Cialowicz, Katarzyna I.; Saleeb, Rebecca S.; Duncan, Rory R.

2016-04-01

We report on efforts to improve the lifetime of biological lasers through the use of ascorbic acid (also commonly known as vitamin C). Fluorescent proteins and dyes, used in biological lasers, suffer from photobleaching due to the build-up of reactive oxygen species (ROS) which causes damage leading to a decrease in emission over time. This is an issue both for laser lifetime and cell health. It has previously been shown that ascorbic acid can be effective in reducing ROS levels in a variety of applications. For our experiments human embryonic kidney cells (HEK293), containing the fluorescent dye Calcein AM, were placed between two dielectric plane mirrors to form a laser cavity. The cells were pumped using the output of a Ti:Sapphire femtosecond OPO system, frequency doubled twice in BBO crystals, giving an output of 474 nm. Initial results have shown an increase in laser lifetime when ascorbic acid is added to cells indicating a reduction in the build-up of ROS.

An overview of clinical and experimental treatment modalities for port wine stains.

PubMed

Chen, Jennifer K; Ghasri, Pedram; Aguilar, Guillermo; van Drooge, Anne Margreet; Wolkerstorfer, Albert; Kelly, Kristen M; Heger, Michal

2012-08-01

Port wine stains (PWS) are the most common vascular malformation of the skin, occurring in 0.3% to 0.5% of the population. Noninvasive laser irradiation with flashlamp-pumped pulsed dye lasers (selective photothermolysis) currently comprises the gold standard treatment of PWS; however, the majority of PWS fail to clear completely after selective photothermolysis. In this review, the clinically used PWS treatment modalities (pulsed dye lasers, alexandrite lasers, neodymium:yttrium-aluminum-garnet lasers, and intense pulsed light) and techniques (combination approaches, multiple passes, and epidermal cooling) are discussed. Retrospective analysis of clinical studies published between 1990 and 2011 was performed to determine therapeutic efficacies for each clinically used modality/technique. In addition, factors that have resulted in the high degree of therapeutic recalcitrance are identified, and emerging experimental treatment strategies are addressed, including the use of photodynamic therapy, immunomodulators, angiogenesis inhibitors, hypobaric pressure, and site-specific pharmaco-laser therapy. Copyright © 2011 American Academy of Dermatology, Inc. Published by Mosby, Inc. All rights reserved.

Theory of lasing in a multiple-scattering medium

NASA Astrophysics Data System (ADS)

John, Sajeev; Pang, Gendi

1996-10-01

In several recent experiments, isotropic lasing action was observed in paints that contain rhodamine 640 dye molecules in methanol solution as gain media and titania particles as optical scatterers. These so-called paint-on laser systems are extraordinary because they are highly disordered systems. The microscopic mechanism for laser activity and the coherence properties of light emission in this multiple-light-scattering medium have not yet been elucidated. In this paper we derive the emission intensity properties of a model dye system with excited singlet and triplet electronic energy levels, which is immersed in a multiple-scattering medium with transport mean free path l*. Using physically reasonable estimates for the absorption and emission cross section for the singlet and triplet manifolds, and the singlet-triplet intersystem crossing rate, we solve the nonlinear laser rate equations for the dye molecules. This leads to a diffusion equation for the light intensity in the medium with a nonlinear intensity-dependent gain coefficient. Using this model we are able to account for nearly all of the experimentally observed properties of laser paint reported so far when l*>>λ0, the emission wavelength. This includes the dependence of the peak intensity of amplified emission on the mean free path l*, the dye concentration ρ, and the pump intensity characteristics. Our model recaptures the collapse of the emission linewidth at a specific threshold pump intensity and describes how this threshold intensity varies with l*. In addition, our model predicts a dramatic increase in the peak intensity and a further lowering of the lasing threshold for the strong scattering limit l*-->λ0. This suggests a striking enhancement of the characteristics of laser paint near the photon localization threshold in a disordered medium.

Resonance Raman and UV-visible spectroscopy of black dyes on textiles.

PubMed

Abbott, Laurence C; Batchelor, Stephen N; Smith, John R Lindsay; Moore, John N

2010-10-10

Resonance Raman and UV-visible diffuse reflectance spectra were recorded from samples of cotton, viscose, polyester, nylon, and acrylic textile swatches dyed black with one of seven single dyes, a mixture of two dyes, or one of seven mixtures of three dyes. The samples generally gave characteristic Raman spectra of the dyes, demonstrating that the technique is applicable for the forensic analysis of dyed black textiles. Survey studies of the widely used dye Reactive Black 5 show that essentially the same Raman spectrum is obtained on bulk sampling from the dye in solution, on viscose, on cotton at different uptakes, and on microscope sampling from the dye in cotton threads and single fibres. The effects of laser irradiation on the Raman bands and emission backgrounds from textile samples with and without dye are also reported. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Dye-sensitized solar cells consisting of dye-bilayer structure stained with two dyes for harvesting light of wide range of wavelength

NASA Astrophysics Data System (ADS)

Inakazu, Fumi; Noma, Yusuke; Ogomi, Yuhei; Hayase, Shuzi

2008-09-01

Dye-sensitized solar cells (DSCs) containing dye-bilayer structure of black dye and NK3705 (3-carboxymethyl-5-[3-(4-sulfobutyl)-2(3H)-bezothiazolylidene]-2-thioxo-4-thiazolidinone, sodium salt) in one TiO2 layer (2-TiO-BD-NK) are reported. The 2-TiO-BD-NK structure was fabricated by staining one TiO2 layer with these two dyes, step by step, under a pressurized CO2 condition. The dye-bilayer structure was observed by using a confocal laser scanning microscope. The short circuit current (Jsc) and the incident photon to current efficiency of the cell (DSC-2-TiO-BD-NK) was almost the sum of those of DSC stained with black dye only (DSC-1-TiO-BD) and DSC stained with NK3705 only (DSC-1-TiO-NK).

Multispectral photoacoustic decomposition with localized regularization for detecting targeted contrast agent

NASA Astrophysics Data System (ADS)

Tavakoli, Behnoosh; Chen, Ying; Guo, Xiaoyu; Kang, Hyun Jae; Pomper, Martin; Boctor, Emad M.

2015-03-01

Targeted contrast agents can improve the sensitivity of imaging systems for cancer detection and monitoring the treatment. In order to accurately detect contrast agent concentration from photoacoustic images, we developed a decomposition algorithm to separate photoacoustic absorption spectrum into components from individual absorbers. In this study, we evaluated novel prostate-specific membrane antigen (PSMA) targeted agents for imaging prostate cancer. Three agents were synthesized through conjugating PSMA-targeting urea with optical dyes ICG, IRDye800CW and ATTO740 respectively. In our preliminary PA study, dyes were injected in a thin wall plastic tube embedded in water tank. The tube was illuminated with pulsed laser light using a tunable Q-switch ND-YAG laser. PA signal along with the B-mode ultrasound images were detected with a diagnostic ultrasound probe in orthogonal mode. PA spectrums of each dye at 0.5 to 20 μM concentrations were estimated using the maximum PA signal extracted from images which are obtained at illumination wavelengths of 700nm-850nm. Subsequently, we developed nonnegative linear least square optimization method along with localized regularization to solve the spectral unmixing. The algorithm was tested by imaging mixture of those dyes. The concentration of each dye was estimated with about 20% error on average from almost all mixtures albeit the small separation between dyes spectrums.

Dye laser amplifier including an improved window configuration for its dye beam

DOEpatents

O'Neil, R.W.; Davin, J.M.

1992-12-01

A dye laser amplifier in which a continuously replenished supply of dye is excited with a first light beam in order to amplify the intensity of a second different light beam passing therethrough is disclosed herein. This amplifier includes a cell though which a continuous stream of the dye is caused to pass, and means for directing the first beam into the cell while the second beam is directed into and through the same cell. There is also disclosed herein a specific improvement to this amplifier which resides in the use of a pair of particularly configured windows through which the second beam passes along fixed paths as the second beam enters and exits the dye cell. Each of these windows has a relatively thick main section which is substantially larger in dimensions transverse to its beam path than the cross section of the second beam itself, whereby to add structural integrity to the overall window. At the same time, the latter includes a second section which is disposed entirely within the confines of the main section and through which the second beam is intended to pass in its entirety. This second section is made substantially thinner than the main section in order to reduce optical distortion as the second beam passes therethrough. 4 figs.

Dye laser amplifier including an improved window configuration for its dye beam

DOEpatents

O'Neil, Richard W.; Davin, James M.

1992-01-01

A dye laser amplifier in which a continuously replenished supply of dye is excited with a first light beam in order to amplify the intensity of a second different light beam passing therethrough is disclosed herein. This amplifier includes a cell though which a continuous stream of the dye is caused to pass, and means for directing the first beam into the cell while the second beam is directed into and through the same cell. There is also disclosed herein a specific improvement to this amplifier which resides in the use of a pair of particularly configured windows through which the second beam passes along fixed paths as the second beam enters and exits the dye cell. Each of these windows has a relatively thick main section which is substantially larger in dimensions transverse to its beam path than the cross section of the second beam itself, whereby to add structural integrity to the overall window. At the same time, the latter includes a second section which is disposed entirely within the confines of the main section and through which the second beam is intended to pass in its entirety. This second section is made substantially thinner than the main section in order to reduce optical distortion as the second beam passes therethrough.

Preparation and flow cytometry of uniform silica-fluorescent dye microspheres.

PubMed

Bele, Marjan; Siiman, Olavi; Matijević, Egon

2002-10-15

Uniform fluorescent silica-dye microspheres have been prepared by coating preformed monodispersed silica particles with silica layers containing rhodamine 6G or acridine orange. The resulting dispersions exhibit intense fluorescent emission between 500 and 600 nm, over a broad excitation wavelength range of 460 to 550 nm, even with exceedingly small amounts of dyes incorporated into the silica particles (10-30 ppm, expressed as weight of dye relative to weight of dry particles). The fluorescent particles can be prepared in micrometer diameters suitable for analyses using flow cytometry with 488-nm laser excitation.

Z-scan and optical limiting properties of Hibiscus Sabdariffa dye

NASA Astrophysics Data System (ADS)

Diallo, A.; Zongo, S.; Mthunzi, P.; Rehman, S.; Alqaradawi, S. Y.; Soboyejo, W.; Maaza, M.

2014-12-01

The intensity-dependent refractive index n 2 and the nonlinear susceptibility χ (3) of Hibiscus Sabdariffa dye solutions in the nanosecond regime at 532 nm are reported. More presicely, the variation of n 2, β, and real and imaginary parts of χ (3) versus the natural dye extract concentration has been carried out by z-scan and optical limiting techniques. The third-order nonlinearity of the Hibiscus Sabdariffa dye solutions was found to be dominated by nonlinear refraction, which leads to strong optical limiting of laser.

The photokilling of bladder carcinoma cells in vitro by phenothiazine dyes.

PubMed

Fowler, G J; Rees, R C; Devonshire, R

1990-09-01

The potential photodynamic therapy photosensitizers Methylene Blue, Azure C, Methylene Violet, Thionine, Methylene Green, Haematoporphyrin, Nile Blue A, chloroaluminium phthalocyanine and bis-aluminium phthalocyanine were examined for their photoeffects and dark toxicity against a human superficial bladder carcinoma cell-line. By examination of [3H]thymidine uptake into dye-treated cells after irradiation with a copper-vapour pumped dye laser, it was found that Methylene Blue was the most phototoxic and dark toxic of all the dyes tested, suggesting that the dye might be of some use as a topically applied photodrug for use in photodynamic therapy of superficial or early-recurring carcinomas.

Rationalizing the photophysical properties of BODIPY laser dyes via aromaticity and electron-donor-based structural perturbations

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

Waddell, Paul G.; Liu, Xiaogang; Zhao, Teng

2015-05-01

The absorption and fluorescence properties of six boron dipyrromethene (BODIPY) laser dyes with simple non-aromatic substituents are rationalized by relating them to observable structural perturbations within the molecules of the dyes. An empirical relationship involving the structure and the optical properties is derived using a combination of single-crystal X-ray diffraction data, quantum chemical calculations and electronic constants: i.e. the tendency of the pyrrole bond lengths towards aromaticity and the UV-vis absorption and fluorescence wavelengths correlating with the electron-donor properties of the substituents. The effect of molecular conformation on the solid-state optical properties of the dyes is also discussed. The findingsmore » in this study also demonstrate the usefulness and limitations of using crystal structure data to develop structure-property relationships in this class of optical materials, contributing to the growing effort to design optoelectronic materials with tunable properties via molecular engineering.« less

Detection of gain enhancement in laser-induced fluorescence of rhodamine B lasing dye by silicon dioxide nanostructures-coated cavity

NASA Astrophysics Data System (ADS)

Al-Tameemi, Mohammed N. A.

2018-03-01

In this work, nanostructured silicon dioxide films are deposited by closed-field unbalanced direct-current (DC) reactive magnetron sputtering technique on two sides of quartz cells containing rhodamine B dye dissolved in ethanol with 10‒5 M concentration as a random gain medium. The preparation conditions are optimized to prepare highly pure SiO2 nanostructures with a minimum particle size of about 20 nm. The effect of SiO2 films as external cavity for the random gain medium is determined by the laser-induced fluorescence of this medium, and an increase of about 200% in intensity is observed after the deposition of nanostructured SiO2 thin films on two sides of the dye cell.

Thermally switchable photonic band-edge to random laser emission in dye-doped cholesteric liquid crystals

NASA Astrophysics Data System (ADS)

Ye, Lihua; Wang, Yan; Feng, Yangyang; Liu, Bo; Gu, Bing; Cui, Yiping; Lu, Yanqing

2018-03-01

By changing the doping concentration of the chiral agent to adjust the relative position of the reflection band of cholesteric liquid crystals and the fluorescence emission spectrum of the dye, photonic band-edge and random lasing were observed, respectively. The reflection band of the cholesteric phase liquid crystal can also be controlled by adjusting the temperature: the reflection band is blue-shifted with increasing temperature, and a reversible switch from photonic band-edge to random lasing is obtained. Furthermore, the laser line width can be thermally adjusted from 1.1 nm (at 27 °C) to 4.6 nm (at 32.1 °C). A thermally tunable polarization state of a random laser from dual cells was observed, broadening the field of application liquid crystal random lasers.

Collisional Quenching of No A2sigma+(nu’= 0) Between 125 and 294 (Postprint)

DTIC Science & Technology

2009-05-28

using an oil-free pumping system consisting of a turbomolecular pump backed by a dry scroll pump . The measured leak rate of the cell was less than 10...mode-locked laser producing pulses of approximately 100 ps duration, was used to pump a DFDL, a side- pumped dye amplifier, and an end- pumped dye...conditions, the calibrated pressure Vacuum C N2 Laser PMTMono L2 L3 Cryostat W1 W2 L1 L1 Ap ND FIG. 1. Experimental arrangement with section detail of cryostat

Planar waveguide nanolaser configured by dye-doped hybrid nanofilm on substrate

NASA Astrophysics Data System (ADS)

Tikhonov, E. A.; Yashchuk, V. P.; Telbiz, G. M.

2018-04-01

Dye-doped hybrid silicate/titanium nanofilms on the glass substrate structures of asymmetrical waveguides were studied by way of laser systems. The threshold, spatial and spectral features of the laser oscillation of genuine and hollow waveguides were determined. The pattern of stimulated radiation included two concurrent processes: single-mode waveguide lasing and lateral small divergence emission. Comparison of the open angle of the lateral beams and grazing angles of the waveguide lasing mode provides an insight into the effect of leaky mode emission followed by Lummer-Gehrcke interference.

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

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

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

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

Laser inactivation of periodontal bacteria using photosensitizing dyes

NASA Astrophysics Data System (ADS)

Golding, Paul S.; Maddocks, L.; King, Terence A.; Drucker, D. B.

1996-12-01

We demonstrate the killing of the oral bacteria Prevotella nigrescens using a photosensitizer and light from a 10 Hz, frequency doubled, Q-switched Nd:YAG pumped dye laser, with modified oscillator to increase output power. This system produced light at wavelengths close to 620 nm, the absorption maximum of the photosensitizing agent, malachite green isothiocyanate, a wavelength that is not significantly absorbed by tissue. A bacterial reduction of 97.5 percent was achieved at an energy density of 0.67 J/cm2 and exposure times of 300 seconds.

Performance of laser guide star adaptive optics at Lick Observatory

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

Olivier, S.S.; An, J.; Avicola, K.

1995-07-19

A sodium-layer laser guide star adaptive optics system has been developed at Lawrence Livermore National Laboratory (LLNL) for use on the 3-meter Shane telescope at Lick Observatory. The system is based on a 127-actuator continuous-surface deformable mirror, a Hartmann wavefront sensor equipped with a fast-framing low-noise CCD camera, and a pulsed solid-state-pumped dye laser tuned to the atomic sodium resonance line at 589 nm. The adaptive optics system has been tested on the Shane telescope using natural reference stars yielding up to a factor of 12 increase in image peak intensity and a factor of 6.5 reduction in image fullmore » width at half maximum (FWHM). The results are consistent with theoretical expectations. The laser guide star system has been installed and operated on the Shane telescope yielding a beam with 22 W average power at 589 nm. Based on experimental data, this laser should generate an 8th magnitude guide star at this site, and the integrated laser guide star adaptive optics system should produce images with Strehl ratios of 0.4 at 2.2 {mu}m in median seeing and 0.7 at 2.2 {mu}m in good seeing.« less

Effects of shielded or unshielded laser and electrohydraulic lithotripsy on rabbit bladder.

PubMed

Bhatta, K M; Rosen, D I; Flotte, T J; Dretler, S P; Nishioka, N S

1990-04-01

The pulsed dye laser and electrohydraulic lithotriptor (EHL) are both effective devices for fragmenting urinary and biliary calculi. Both fragment stones by producing a plasma-mediated shockwave. Recently, a plasma shield consisting of a hollow spring and a metal end cap has been described for use with the laser and EHL devices in an attempt to minimize tissue damage without adversely affecting stone fragmentation rates. The tissue effects produced by a pulsed dye laser and an EHL device with and without plasma shields were examined and compared using rabbit urinary bladders. If blood was present, the unshielded laser perforated the bladder wall in two pulses. However, in the absence of blood, over 100 pulses were needed for the laser to perforate the bladder. A mean of six pulses were required to perforate the bladder wall with a shielded laser. The unshielded EHL perforated the bladder wall in two pulses, whereas, the shielded EHL required a mean of 35 pulses. Microscopically, areas of exposure revealed hemorrhage and tissue ablation. We conclude that all devices examined can produce significant tissue damage when discharged directly onto bladder epithelium.

Sealing ability of three root-end filling materials prepared using an erbium: Yttrium aluminium garnet laser and endosonic tip evaluated by confocal laser scanning microscopy

PubMed Central

Nanjappa, A Salin; Ponnappa, KC; Nanjamma, KK; Ponappa, MC; Girish, Sabari; Nitin, Anita

2015-01-01

Aims: (1) To compare the sealing ability of mineral trioxide aggregate (MTA), Biodentine, and Chitra-calcium phosphate cement (CPC) when used as root-end filling, evaluated under confocal laser scanning microscope using Rhodamine B dye. (2) To evaluate effect of ultrasonic retroprep tip and an erbium:yttrium aluminium garnet (Er:YAG) laser on the integrity of three different root-end filling materials. Materials and Methods: The root canals of 80 extracted teeth were instrumented and obturated with gutta-percha. The apical 3 mm of each tooth was resected and 3 mm root-end preparation was made using ultrasonic tip (n = 30) and Er:YAG laser (n = 30). MTA, Biodentine, and Chitra-CPC were used to restore 10 teeth each. The samples were coated with varnish and after drying, they were immersed in Rhodamine B dye for 24 h. The teeth were then rinsed, sectioned longitudinally, and observed under confocal laser scanning microscope. Statistical Analysis Used: Data were analyzed using one-way analysis of variance (ANOVA) and a post-hoc Tukey's test at P < 0.05 (R software version 3.1.0). Results: Comparison of microleakage showed maximum peak value of 0.45 mm for Biodentine, 0.85 mm for MTA, and 1.05 mm for Chitra-CPC. The amount of dye penetration was found to be lesser in root ends prepared using Er:YAG laser when compared with ultrasonics, the difference was found to be statistically significant (P < 0.05). Conclusions: Root-end cavities prepared with Er:YAG laser and restored with Biodentine showed superior sealing ability compared to those prepared with ultrasonics. PMID:26180420

Fluidic optics

NASA Astrophysics Data System (ADS)

Whitesides, George M.; Tang, Sindy K. Y.

2006-09-01

Fluidic optics is a new class of optical system with real-time tunability and reconfigurability enabled by the introduction of fluidic components into the optical path. We describe the design, fabrication, operation of a number of fluidic optical systems, and focus on three devices, liquid-core/liquid-cladding (L2) waveguides, microfluidic dye lasers, and diffraction gratings based on flowing, crystalline lattices of bubbles, to demonstrate the integration of microfluidics and optics. We fabricate these devices in poly(dimethylsiloxane) (PDMS) with soft-lithographic techniques. They are simple to construct, and readily integrable with microanalytical or lab-on-a-chip systems.

Evaluation of Energy Dose and Output Power Optimum of Diode’s Laser of 450 nm and 650 nm in Photoantimicrobial Mechanisms Against Inhibition of C. Albicans Biofilm Cells

NASA Astrophysics Data System (ADS)

Dewi-Astuty, S.; Suhariningsih; Dyah-Astuti, S.; Baktir, A.

2018-03-01

Photoantimicrobial as a pathogenic microbial inhibitory therapy system such as C. albicans in biofilms forms has been studied in vitro. Mechanisms of inhibiting called inactivating used the absorb principles of a dye agents such as chlorophyll against the photon energy of diode laser which any number of ROS product depend on energy doses of a laser, time of irradiation, concentration and time of incubation the dyes agent. The inactivation profile of C. albicans biofilm cells was observed based on cell viability reduction after photoantimicrobial treatment with or without oxygenation by XTT assay test. Results show that the inhibiting significantly with the time incubation of the dye agents and the oxygen degree inside the sample. The inhibition for oxygenation biofilm’s group 10% lower than without oxygenation biofilm’s group at the maximum of reduction of cell viability occurred in the 3hour incubation group. Optimum of inactivation are 89.6% (without oxygenation) and 94.8% (with oxygenation) after irradiation with 450 nm laser (power output 128.73 at energy dose 86.09 J/cm2), While, by 650 nm laser (power output 164.53 mW at energy dose 92.52 J/cm2) irradiation treatment obtained optimum of inactivation are 89.5% (without oxygenation) and 92.3% (with oxygenation).

Limits to Sensitivity in Laser Enhanced Ionization.

ERIC Educational Resources Information Center

Travis, J. C.

1982-01-01

Laser enhanced ionization (LEI) occurs when a tunable dye laser is used to excite a specific atomic population in a flame. Explores the origin of LEI's high sensitivity and identifies possible avenues to higher sensitivity by describing instrument used and experimental procedures and discussing ion formation/detection. (Author/JN)

Bibliography of Soviet Laser Developments, Number 50, November-December 1980.

DTIC Science & Technology

1981-11-30

ADA B 37 DEFENSE INTELLIGENCE AGENCY WASHINGTON Dc OIRECTORAT-ETC F/6 201", BIBLIOGRAPHY OF SOVIET LASER DEVELOPMENTS, NOVEMBER-DECEMBER I 9-ETCIU...Semiconductor: Simple Junction a. GaAs.............................................3 b . CUS..............................................3 5...Glass: Nd...........................................6 B . Liquid Lasers 1. Organic Dyes a. Rhodamine........................................6 b

New 445 nm blue laser for laryngeal surgery combines photoangiolytic and cutting properties.

PubMed

Hess, Markus M; Fleischer, Susanne; Ernstberger, Marcel

2018-06-01

Photoangiolytic lasers have broadened the surgical armamentarium for many phonosurgical interventions. However, the pulse dye laser and potassium titanyl phosphate (KTP) laser have technical drawbacks and a smaller spectrum of indications. The new 445 nm wavelength laser, the so-called 'blue laser', proves to show tissue effects comparable to the KTP laser and is also capable of treating subepithelial vessels due to its photoangiolytic properties, it can coagulate and carbonize at higher energy levels, and can be used via glass fibers in non-contact and contact mode for in-office procedures. In contrast to the KTP, the new 445 nm laser can also be used as a cutting laser, thus combining very much wanted properties of diode or CO2 lasers with photoangiolytic lasers. Further advantages of the new laser are the; (1) portability of the shoe box sized, shock-proof laser machine for in-office and operating room usage, (2) the selection of pulse rates from continuous wave (cw) to less than a millisecond, (3) stronger tissue effects compared to KTP with similar energy and pulse settings, (4) far better cutting properties than the KTP, and thus (5) more possibilities for usage in laryngology as well as in other fields or surgery. We demonstrate the feasibility of the 445 nm laser in several laboratory experiments and show clinical cases where photoangiolysis and cutting was possible. However, this is a preliminary report and further systematic studies in greater numbers are warranted.

Particle Image Velocimetry Applications Using Fluorescent Dye-Doped Particles

NASA Technical Reports Server (NTRS)

Petrosky, Brian J.; Maisto, Pietro; Lowe, K. Todd; Andre, Matthieu A.; Bardet, Philippe M.; Tiemsin, Patsy I.; Wohl, Christopher J.; Danehy, Paul M.

2015-01-01

Polystyrene latex sphere particles are widely used to seed flows for velocimetry techniques such as Particle Image Velocimetry (PIV) and Laser Doppler Velocimetry (LDV). These particles may be doped with fluorescent dyes such that signals spectrally shifted from the incident laser wavelength may be detected via Laser Induced Fluorescence (LIF). An attractive application of the LIF signal is achieving velocimetry in the presence of strong interference from laser scatter, opening up new research possibilities very near solid surfaces or at liquid/gas interfaces. Additionally, LIF signals can be used to tag different fluid streams to study mixing. While fluorescence-based PIV has been performed by many researchers for particles dispersed in water flows, the current work is among the first in applying the technique to micron-scale particles dispersed in a gas. A key requirement for such an application is addressing potential health hazards from fluorescent dyes; successful doping of Kiton Red 620 (KR620) has enabled the use of this relatively safe dye for fluorescence PIV for the first time. In this paper, basic applications proving the concept of PIV using the LIF signal from KR620-doped particles are exhibited for a free jet and a twophase flow apparatus. Results indicate that while the fluorescence PIV techniques are roughly 2 orders of magnitude weaker than Mie scattering, they provide a viable method for obtaining data in flow regions previously inaccessible via standard PIV. These techniques have the potential to also complement Mie scattering signals, for example in multi-stream and/or multi-phase experiments.

[INVITED] On the mechanisms of single-pulse laser-induced backside wet etching

NASA Astrophysics Data System (ADS)

Tsvetkov, M. Yu.; Yusupov, V. I.; Minaev, N. V.; Akovantseva, A. A.; Timashev, P. S.; Golant, K. M.; Chichkov, B. N.; Bagratashvili, V. N.

2017-02-01

Laser-induced backside wet etching (LIBWE) of a silicate glass surface at interface with a strongly absorbing aqueous dye solution is studied. The process of crater formation and the generated optoacoustic signals under the action of single 5 ns laser pulses at the wavelength of 527 nm are investigated. The single-pulse mode is used to avoid effects of incubation and saturation of the etched depth. Significant differences in the mechanisms of crater formation in the ;soft; mode of laser action (at laser fluencies smaller than 150-170 J/cm2) and in the ;hard; mode (at higher laser fluencies) are observed. In the ;soft; single-pulse mode, LIBWE produces accurate craters with the depth of several hundred nanometers, good shape reproducibility and smooth walls. Estimates of temperature and pressure of the dye solution heated by a single laser pulse indicate that these parameters can significantly exceed the corresponding critical values for water. We consider that chemical etching of glass surface (or molten glass) by supercritical water, produced by laser heating of the aqueous dye solution, is the dominant mechanism responsible for the formation of crater in the ;soft; mode. In the ;hard; mode, the produced craters have ragged shape and poor pulse-to-pulse reproducibility. Outside the laser exposed area, cracks and splits are formed, which provide evidence for the shock induced glass fracture. By measuring the amplitude and spectrum of the generated optoacoustic signals it is possible to conclude that in the ;hard; mode of laser action, intense hydrodynamic processes induced by the formation and cavitation collapse of vapor-gas bubbles at solid-liquid interface are leading to the mechanical fracture of glass. The LIBWE material processing in the ;soft; mode, based on chemical etching in supercritical fluids (in particular, supercritical water) is very promising for structuring of optical materials.

A new type of two-wave interaction in saturable dye

NASA Astrophysics Data System (ADS)

Hu, Q.; Lin, F.

1986-03-01

A new interaction of two noncollinear laser beams with the same frequency have been observed in a saturable dye solution of bis-(4-dimethyl aminodithio benzil) (DN) and pentamethine cyanine. It differs from the four-wave mixing effect and the transient self-diffraction and coherent coupling effects.

Excimer-laser-induced shock wave and its dependence on atmospheric environment

NASA Astrophysics Data System (ADS)

Krueger, Ronald R.; Krasinski, Jerzy S.; Radzewicz, Czeslaw

1993-06-01

High speed shadow photography is performed on excimer laser ablated porcine corneas and rubber stoppers to capture the excimer laser induced shock waves at various time delays between 40 and 320 nanoseconds. The shock waves in air, nitrogen, and helium are recorded by tangentially illuminating the ablated surface with a tunable dye laser, the XeCl excimer laser pulse. The excimer laser ablates the specimen and excites the dye laser, which is then passed through an optical delay line before illuminating the specimen. The shadow of the shock wave produced during ablation is then cast on a screen and photographed with a CCD video camera. The system is pulsed at 30 times per second to allow a video recording of the shock wave at a fixed time delay. We conclude that high energy acoustic waves and gaseous particles are liberated during excimer laser corneal ablation, and dissipate on a submicrosecond time scale. The velocity of their dissipation is dependent on the atmospheric environment and can be increased two-fold when the ablation is performed in a helium atmosphere. Therefore, local temperature increases due to the liberation of high energy gases may be reduced by using helium during corneal photoablation.

Investigation of laser induced parametric interactions in optical waveguides and fibers

NASA Technical Reports Server (NTRS)

Yu, C.

1978-01-01

Experimental and theoretical aspects of the laser pump depletion characteristics in an optical fiber due to stimulated Raman scattering, and stimulated Brillouin scattering were studied. A review is presented of research in fiber transmission accompanied by stimulated scattering. Results of experimental work with tunable dye lasers and argon lasers are presented. The spectral profiles of the laser pump and its transmitted light through the fiber are given.

Topical Adjuncts to Pulsed Dye Laser for Treatment of Port Wine Stains: Review of the Literature.

PubMed

Lipner, Shari R

2018-06-01

Port wine stains (PWS) pose a therapeutic challenge. Pulsed dye laser (PDL) is the treatment of choice; however, treatment is often ineffective and recurrences are common. This article provides a review of topical therapies that have been investigated to improve efficacy of PDL for the treatment of PWS. A literature search was performed through PubMed, EMBASE, Web of Science, and CINAHL, using the search terms "port wine stain," "pulsed dye laser," and "topical." Clinical trials have investigated the topical agents, timolol, imiquimod, and rapamycin (RPM) in combination with PDL for the treatment of PWS. Topical timolol with PDL failed to show improved efficacy compared with PDL alone. Two clinical trials using imiquimod and PDL showed enhanced blanching of PWS compared with controls. Rapamycin and PDL were more effective than controls for facial PWS, but not for nonfacial PWS. Topical imiquimod and RPM have shown some efficacy in treating PWS with PDL, but to date there is no topical adjuvant to PDL that reliably improves results for PWS.

Demonstration of versatile whispering-gallery micro-lasers for remote refractive index sensing.

PubMed

Wan, Lei; Chandrahalim, Hengky; Zhou, Jian; Li, Zhaohui; Chen, Cong; Cho, Sangha; Zhang, Hui; Mei, Ting; Tian, Huiping; Oki, Yuji; Nishimura, Naoya; Fan, Xudong; Guo, L Jay

2018-03-05

We developed chip-scale remote refractive index sensors based on Rhodamine 6G (R6G)-doped polymer micro-ring lasers. The chemical, temperature, and mechanical sturdiness of the fused-silica host guaranteed a flexible deployment of dye-doped polymers for refractive index sensing. The introduction of the dye as gain medium demonstrated the feasibility of remote sensing based on the free-space optics measurement setup. Compared to the R6G-doped TZ-001, the lasing behavior of R6G-doped SU-8 polymer micro-ring laser under an aqueous environment had a narrower spectrum linewidth, producing the minimum detectable refractive index change of 4 × 10 -4 RIU. The maximum bulk refractive index sensitivity (BRIS) of 75 nm/RIU was obtained for SU-8 laser-based refractive index sensors. The economical, rapid, and simple realization of polymeric micro-scale whispering-gallery-mode (WGM) laser-based refractive index sensors will further expand pathways of static and dynamic remote environmental, chemical, biological, and bio-chemical sensing.

Luminescent characteristics study of Mather-type dense plasma focus and applications to short-wavelength optical pumping. Final technical report, 1 May 1984-30 September 1985

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

Kim, K.K.

A Mather-type dense plasma focus (MDPF) system was designed, built, and tested specifically to study its luminescent characteristics and to assess its potential as a new light source of high-energy, short-wavelength lasers. The luminescence study of MDPF showed that the conversion efficiency from the electrical input to the optical output energies is at least 50%, up to the time the plasma compression is complete. Using the system, for the first time as an optical pump, laser activities were successfully obtained from a variety of liquid organic dyes. Diagnostic capabilities included an optical multichannel analyzer system complete with a computer control,more » a nitrogen-pumped tunable dye-laser system, a high-speed streak/framing camera, a digital laser energy meter, voltage and current probes, and a computer-based data-acquisition system.« less

PVA with nopal dye as holographic recording material

NASA Astrophysics Data System (ADS)

Toxqui-López, S.; Olivares-Pérez, A.; Fuentes-Tapia, I.; Pinto-Iguanero, B.

2011-09-01

Cactus nopal dye is introduced into a polyvinyl alcohol matrix achieving a like brown appearance thick film, such that they can be used as a recording medium. This dye material provides excellent property as photosensitizer, i.e., easy handling, low cost and can be used in real time holographic recording applications. The experimental results show the diffraction efficiencies obtained by recording grating patterns induced by a He-Cd laser (442nm). For the samples, a thick film of polyvinyl alcohol and dye from cactus nopal was deposited by the gravity technique on a glass substrate. This mixture dries to form a photosensitive emulsion.

Fluorescence-Doped Particles for Simultaneous Temperature and Velocity Imaging

NASA Technical Reports Server (NTRS)

Danehy, Paul M.; Tiemsin, Pacita I.; Wohl, Chrostopher J.; Verkamp, Max; Lowe, T.; Maisto, P.; Byun, G.; Simpson, R.

2012-01-01

Polystyrene latex microspheres (PSLs) have been used for particle image velocimetry (PIV) and laser Doppler velocimetry (LDV) measurements for several decades. With advances in laser technologies, instrumentation, and data processing, the capability to collect more information about fluid flow beyond velocity is possible using new seed materials. To provide additional measurement capability, PSLs were synthesized with temperature-sensitive fluorescent dyes incorporated within the particle. These multifunctional PSLs would have the greatest impact if they could be used in large scale facilities with minimal modification to the facilities or the existing instrumentation. Consequently, several potential dyes were identified that were amenable to existing laser systems currently utilized in wind tunnels at NASA Langley Research Center as well as other wind and fluid (water) tunnels. PSLs incorporated with Rhodamine B, dichlorofluorescein (DCF, also known as fluorescein 548 or fluorescein 27) and other dyes were synthesized and characterized for morphology and spectral properties. The resulting particles were demonstrated to exhibit fluorescent emission, which would enable determination of both fluid velocity and temperature. They also would allow near-wall velocity measurements whereas laser scatter from surfaces currently prevents near-wall measurements using undoped seed materials. Preliminary results in a wind tunnel facility located at Virginia Polytechnic Institute and State University (Virginia Tech) have verified fluorescent signal detection and temperature sensitivity of fluorophore-doped PSLs.

Use of reflectance spectrophotometry to predict the response of port wine stains to pulsed dye laser.

PubMed

Halachmi, Shlomit; Azaria, Ron; Inbar, Roy; Ad-El, Dean; Lapidoth, Moshe

2014-01-01

Reflectance spectroscopy can be used to quantitate subtle differences in color. We applied a portable reflectance spectrometer to determine its utility in the evaluation of pulsed dye laser treatment of port wine stains (PWS) and in prediction of clinical outcome, in a prospective study. Forty-eight patients with PWS underwent one to nine pulsed dye laser treatments. Patient age and skin color as well as PWS surface area, anatomic location, and color were recorded. Pretreatment spectrophotometric measurements were performed. The subjective clinical results of treatment and the quantitative spectrophotometry results were evaluated by two independent teams, and the findings were correlated. The impact of the clinical characteristics on the response to treatment was assessed as well. Patients with excellent to good clinical results of laser treatments had pretreatment spectrophotometric measurements which differed by more than 10%, whereas patients with fair to poor results had spectrophotometric measurements with a difference of of less than 10%. The correlation between the spectrophotometric results and the clinical outcome was 73% (p < 0.01). The impact of the other clinical variables on outcome agreed with the findings in the literature. Spectrophotometry has a higher correlation with clinical outcome and a better predictive value than other nonmeasurable, nonquantitative, dependent variables.

Blue-green upconversion laser

DOEpatents

Nguyen, D.C.; Faulkner, G.E.

1990-08-14

A blue-green laser (450--550 nm) uses a host crystal doped with Tm[sup 3+]. The Tm[sup 3+] is excited through upconversion by a red pumping laser and an IR pumping laser to a state which transitions to a relatively lower energy level through emissions in the blue-green band, e.g., 450.20 nm at 75 K. The exciting laser may be tunable dye lasers or may be solid-state semiconductor laser, e.g., GaAlAs and InGaAlP. 3 figs.

Blue-green upconversion laser

DOEpatents

Nguyen, Dinh C.; Faulkner, George E.

1990-01-01

A blue-green laser (450-550 nm) uses a host crystal doped with Tm.sup.3+. The Tm.sup.+ is excited through upconversion by a red pumping laser and an IR pumping laser to a state which transitions to a relatively lower energy level through emissions in the blue-green band, e.g., 450.20 nm at 75 K. The exciting laser may be tunable dye lasers or may be solid-state semiconductor laser, e.g., GaAlAs and InGaAlP.

New energy transfer dyes for DNA sequencing.

PubMed Central

Lee, L G; Spurgeon, S L; Heiner, C R; Benson, S C; Rosenblum, B B; Menchen, S M; Graham, R J; Constantinescu, A; Upadhya, K G; Cassel, J M

1997-01-01

We have synthesized a set of four energy transfer dyes and demonstrated their use in automated DNA sequencing. The donor dyes are the 5- or 6-carboxy isomers of 4'-aminomethylfluorescein and the acceptor dyes are a novel set of four 4,7-dichloro-substituted rhodamine dyes which have narrower emission spectra than the standard, unsubstituted rhodamines. A rigid amino acid linker, 4-aminomethylbenzoic acid, was used to separate the dyes. The brightness of each dye in an automated sequencing instrument equipped with a dual line argon ion laser (488 and 514 nm excitation) was 2-2.5 times greater than the standard dye-primers with a 2 times reduction in multicomponent noise. The overall improvement in signal-to-noise was 4- to 5-fold. The utility of the new dye set was demonstrated by sequencing of a BAC DNA with an 80 kb insert. Measurement of the extinction coefficients and the relative quantum yields of the dichlororhodamine components of the energy transfer dyes showed their values were reduced by 20-25% compared with the dichlororhodamine dyes alone. PMID:9207029

Thermal cycling and the optical and electrical characterization of self-assembled multilayer nile blue A-gold thin films.

PubMed

Geist, Brian; Spillman, William B; Claus, Richard O

2005-10-20

Some laser applications produce high power densities that can be dangerous to equipment and operators. We have fabricated thin-film coatings by using molecular electrostatic self-assembly to create a spectrally selective absorbing coating that is able to withstand thermal fluctuations from -20 degrees C to 120 degrees C. We made the thin-film coatings by alternating deposition of an organic dye and gold colloidal nanoparticles onto glass substrates. Nile Blue A perchlorate, with a maximum absorbance slightly above 632 nm, was chosen as the organic dye. Strong coupling between the dye molecules and the gold nanoparticles provides a redshift that increases as the film's thickness is increased. The incorporation of the gold colloidal nanoparticles also decreases the resistivity of the film. The resistivity of the film was measured with a four-point probe and found to be approximately 10 omega/cm for the two samples measured. Atomic-force microscopy was used to show that film thickness increased 2.4 nm per bilayer. The optical properties of the film were measured at the end of every 5 thermal cycles from -20 degrees C to 120 degrees C, and negligible degradation was observed after 30 cycles.

[Photodynamic therapy of dysplasias and early carcinomas in Barrett esophagus with a diode laser system--a pilot study].

PubMed

Zöpf, T; Rosenbaum, A; Apel, D; Jakobs, R; Arnold, J C; Riemann, J F

2001-04-15

Photodynamic therapy (PDT) of dysplasia and early cancer of the esophagus could show good results in the potential of ablation. Unfortunately, the existing expensive and temperamental dye laser systems foiled a broad clinical use. In this pilot study, we investigated the feasibility of an inexpensive and maintenance-free diode laser system for PDT of dysplasia and early cancer in Barrett's esophagus. Eight patients with Barrett's esophagus and/or early cancer were treated. As light source we used a diode laser system with a maximum power output of 2 W and a wavelength of 633 +/- 3 nm. One patient was treated initially with Photosan-3, seven patients received 5-aminolevulinic acid. In all patients we could achieve reduction in length and/or histologically proven downgrading. In three quarters of the patients, complete eradication of adenocarcinoma could be attained. Columnar-lined metaplastic epithelium could also be completely eradicated. PDT using a diode laser system is comparably effective in Barrett's esophagus/early cancer as PDT with dye laser systems. PDT is a gentle and effective technique with little side effects.

Comparison of TiO₂ and ZnO solar cells sensitized with an indoline dye: time-resolved laser spectroscopy studies of partial charge separation processes.

PubMed

Sobuś, Jan; Burdziński, Gotard; Karolczak, Jerzy; Idígoras, Jesús; Anta, Juan A; Ziółek, Marcin

2014-03-11

Time-resolved laser spectroscopy techniques in the time range from femtoseconds to seconds were applied to investigate the charge separation processes in complete dye-sensitized solar cells (DSC) made with iodide/iodine liquid electrolyte and indoline dye D149 interacting with TiO2 or ZnO nanoparticles. The aim of the studies was to explain the differences in the photocurrents of the cells (3-4 times higher for TiO2 than for ZnO ones). Electrochemical impedance spectroscopy and nanosecond flash photolysis studies revealed that the better performance of TiO2 samples is not due to the charge collection and dye regeneration processes. Femtosecond transient absorption results indicated that after first 100 ps the number of photoinduced electrons in the semiconductor is 3 times higher for TiO2 than for ZnO solar cells. Picosecond emission studies showed that the lifetime of the D149 excited state is about 3 times longer for ZnO than for TiO2 samples. Therefore, the results indicate that lower performance of ZnO solar cells is likely due to slower electron injection. The studies show how to correlate the laser spectroscopy methodology with global parameters of the solar cells and should help in better understanding of the behavior of alternative materials for porous electrodes for DSC and related devices.

Tunable lasers for water vapor measurements and other lidar applications

NASA Technical Reports Server (NTRS)

Gammon, R. W.; Mcilrath, T. J.; Wilkerson, T. D.

1977-01-01

A tunable dye laser suitable for differential absorption (DIAL) measurements of water vapor in the troposphere was constructed. A multi-pass absorption cell for calibration was also constructed for use in atmospheric DIAL measurements of water vapor.

Protein labeling with red squarylium dyes for analysis by capillary electrophoresis with laser-induced fluorescence detection.

PubMed

Yan, Weiying; Sloat, Amy L; Yagi, Shigeyuki; Nakazumi, Hiroyuki; Colyer, Christa L

2006-04-01

Two new red luminescent asymmetric squarylium dyes (designated "Red-1c and Red-3") have been shown to exhibit absorbance shifts to longer wavelengths upon the addition of protein, along with a concomitant increase in fluorescence emission. Specifically, the absorbance maxima for Red-1c and Red-3 dyes are 607 and 622 nm, respectively, in the absence of HSA, and 642 and 640 nm in the presence of HSA, making the excitation of their protein complexes feasible with inexpensive and robust diode lasers. Fluorescence emission maxima, in the presence of HSA, are 656 and 644 nm for Red-1c and Red-3, respectively. Because of the inherently low fluorescence of the dyes in their free state, Red-1c and Red-3 were used as on-column labels (that is, with the dye incorporated into the separation buffer), thus eliminating the need for sample derivatization prior to injection and separation. A comparison of precolumn and on-column labeling of proteins with these squarylium dyes revealed higher efficiencies and greater sensitivities for on-column labeling, which, when conducted with a basic, high-salt content buffer, permitted baseline resolution of a mixture of five model proteins. LOD for model proteins, such as transferrin, alpha-lactalbumin, BSA, and beta-lactoglobulin A and B, labeled with these dyes and analyzed by CE with LIF detection (CE-LIF) were found to be dependent upon dye concentration and solution pH, and are as low as 5 nM for BSA. Satisfactory linear relationships between peak height (or peak area) and protein concentration were obtained by CE-LIF for this on-column labeling method with Red-3 and Red-1c.

Bench-Top Antigen Detection Technique that Utilizes Nanofiltration and Fluorescent Dyes which Emit and Absorb Light in the Near Infrared

NASA Technical Reports Server (NTRS)

Varaljay-Spence, Vanessa A.; Scardelletti, Maximilian C.

2007-01-01

This article discusses the development of a bench-top technique to detect antigens in fluids. The technique involves the use of near infrared NIR fluorescent dyes conjugated to antibodies, centrifugation, nanofilters, and spectrometry. The system used to detect the antigens utilizes a spectrometer, fiber optic cables, NIR laser, and laptop computer thus making it portable and ideally suited for desk top analysis. Using IgM as an antigen and the secondary antibody, anti-IgM conjugated to the near infrared dye, IRDye (trademark) 800, for detection, we show that nanofiltration can efficiently and specifically separate antibody-antigen complexes in solution and that the complexes can be detected by a spectrometer and software using NIR laser excitation at 778 nm and NIR dye offset emission at 804 nm. The peak power detected at 778 nm for the excitation emission and at 804 nm for the offset emission is 879 pW (-60.06 dBm) and 35.7 pW (-74.5 dBm), respectively.

In vitro laser nerve repair: protein solder strip irradiation or irradiation alone?

PubMed

Trickett, I; Dawes, J M; Knowles, D S; Lanzetta, M; Owen, E R

1997-01-01

This study investigated the potential of sutureless nerve repair using two promising laser fusion methods: direct 2 microns irradiation of the epineurium, and protein solder assisted epineurial fusion using a 800 nm laser. Laser anastomosis of the rat sciatic nerve was performed in vitro without stay sutures in two groups of six animals. In the first group, direct laser fusion used a pulsed Cr, Tm: YAG laser. In the second group an albumin-based fluid solder containing the dye indocyanine green was applied to the epineurium, then irradiated with a diode laser. These two techniques were compared with regards to coaptation success and axonal damage. Direct laser welding produced weak bonds despite microscopic investigation of the irradiated nerves showing fusion of the epineurium. The unsatisfactory bonding can be attributed to poor tissue overlap and insufficient protein in the thin epineurium denaturation of underlying axons was also observed. In contrast, the laser solder method produced successful welds with greatly reduced axonal damage, and significantly improved the tensile strength. This study confirmed the technical possibilities of sutureless nerve anastomosis. Laser activated solders enable stronger bonds, by the addition of protein to the anastomosis site, and less thermal damage to underlying tissue through selective absorption of laser energy by dye in the solder. Further in vivo studies are required before drawing final conclusions.

Optofluidic lasers with a single molecular layer of gain

PubMed Central

Chen, Qiushu; Ritt, Michael; Sivaramakrishnan, Sivaraj; Sun, Yuze; Fan, Xudong

2014-01-01

We achieve optofluidic lasers with a single molecular layer of gain, in which green fluorescent protein, dye-labeled bovine serum albumin, and dye-labeled DNA are respectively used as the gain medium and attached to the surface of a ring resonator via surface immobilization biochemical methods. It is estimated that the surface density of the gain molecules is on the order of 1012/cm2, sufficient for lasing under pulsed optical excitation. It is further shown that the optofluidic laser can be tuned by energy transfer mechanisms through biomolecular interactions. This work not only opens a door to novel photonic devices that can be controlled at the level of a single molecular layer, but also provides a promising sensing platform to analyze biochemical processes at the solid-liquid interface. PMID:25312306

Sustained multi-kHz flamefront and 3-component velocity-field measurements for the study of turbulent flames

NASA Astrophysics Data System (ADS)

Boxx, I.; Stöhr, M.; Carter, C.; Meier, W.

2009-04-01

We describe an approach of imaging the dynamic interaction of the flamefront and flowfield. Here, a diode-pumped Nd:YLF laser operating at 5 kHz is used to pump a dye laser, which is then frequency doubled to 283 nm to probe flamefront OH, while a dual cavity diode-pumped Nd:YAG system produces pulse-pairs for particle image velocimetry (PIV). CMOS digital cameras are used to detect both planar laser-induced fluorescence (PLIF) and particle scattering (in a stereo arrangement) such that a 5 kHz measurement frequency is attained. This diagnostic is demonstrated in lifted-jet and swirl-stabilized flames, wherein the dynamics of the flame stabilization processes are seen. Nonperiodic effects such as local ignition and/or extinction, lift-off and flashback events, and their histories can be captured by this technique. As such, this system has the potential to significantly extend our understanding of nonstationary combustion processes relevant to industrial and technical applications.

A Search for Some Wide-Range Tunable Dye Laser Systems Working on the ’Exciplex’ Principle.

DTIC Science & Technology

The ’ exciplex ’ mechanism of radiation emission from a dye affords one means of producing a broad fluorescent spectrum without adding to the...emissions from both the dye and the exciplex may appear, thereby permitting an even greater tuning range. Two mechanisms apply: the ’proton exciplex ...8217, which relates to changes in conventional acidity and basicity in the excited state; and the ’molecular exciplex ’, which relates to changes in

Infrared Dyes For Optical Storage

NASA Astrophysics Data System (ADS)

Jipson, V. B.; Jones, C. R.

1981-06-01

There is current interest in developing optical storage materials that can be written with GaAlAs lasers. Dyes which absorb strongly at those wavelengths are potential candidates for this application due to their attractive thermal properties. Through optical and thermal modelling, the properties that are necessary if they are to be writeable at energies of <=1 nJ are examined. A specific class of infrared absorbing dyes, squarylium, is discussed and preliminary data on optical characteristics, writing energy, and stability are presented.

A unique charge-coupled device/xenon arc lamp based imaging system for the accurate detection and quantitation of multicolour fluorescence.

PubMed

Spibey, C A; Jackson, P; Herick, K

2001-03-01

In recent years the use of fluorescent dyes in biological applications has dramatically increased. The continual improvement in the capabilities of these fluorescent dyes demands increasingly sensitive detection systems that provide accurate quantitation over a wide linear dynamic range. In the field of proteomics, the detection, quantitation and identification of very low abundance proteins are of extreme importance in understanding cellular processes. Therefore, the instrumentation used to acquire an image of such samples, for spot picking and identification by mass spectrometry, must be sensitive enough to be able, not only, to maximise the sensitivity and dynamic range of the staining dyes but, as importantly, adapt to the ever changing portfolio of fluorescent dyes as they become available. Just as the available fluorescent probes are improving and evolving so are the users application requirements. Therefore, the instrumentation chosen must be flexible to address and adapt to those changing needs. As a result, a highly competitive market for the supply and production of such dyes and the instrumentation for their detection and quantitation have emerged. The instrumentation currently available is based on either laser/photomultiplier tube (PMT) scanning or lamp/charge-coupled device (CCD) based mechanisms. This review briefly discusses the advantages and disadvantages of both System types for fluorescence imaging, gives a technical overview of CCD technology and describes in detail a unique xenon/are lamp CCD based instrument, from PerkinElmer Life Sciences. The Wallac-1442 ARTHUR is unique in its ability to scan both large areas at high resolution and give accurate selectable excitation over the whole of the UV/visible range. It operates by filtering both the excitation and emission wavelengths, providing optimal and accurate measurement and quantitation of virtually any available dye and allows excellent spectral resolution between different fluorophores. This flexibility and excitation accuracy is key to multicolour applications and future adaptation of the instrument to address the application requirements and newly emerging dyes.

A modified commercial ultrasound scanner used for in vivo photoacoustic imaging of nude mice injected with non-targeted contrast agents

NASA Astrophysics Data System (ADS)

Jankovic, Ladislav; Shahzad, Khalid; Wang, Yao; Burcher, Michael; Scholle, Frank-Detlef; Hauff, Peter; Mofina, Sabine; Skobe, Mihaela

2008-02-01

Photoacoustic (PA) experiments were performed using a modified commercial ultrasound scanner equipped with an array transducer and a Nd:YAG pumped OPO laser. The contrast agent SIDAG (Bayer Schering Pharma AG, Germany), used to enhance the optical absorption, demonstrated an expected pharmacokinetic behavior of the dye in the tumor and in the bladder of the nude mice. A typical behavior in the tumor consisted of an initial linear increase in PA signal followed by an exponential decay. PA signal approached the pre-injection level after about one hour following the dye injection, which was consistent with the behavior for such contrast agents when used in other imaging modalities, such as fluorescence imaging. The in-vivo spectral PA data from the mouse bladder, conducted 1.5 hours after the dye injection, clearly demonstrated presence of the dye. The multi-spectral PA data was obtained at 760nm, 784nm and 850nm laser excitations. The PA intensities obtained at these three wavelengths accurately matched the dye absorption spectrum. In addition, in the kidney, a clearance organ for this contrast agent, both in-vivo and ex-vivo results demonstrated a significant increase (~ 40%) in the ratio of PA signal at 760nm (the peak of the dye absorption) relative to the signal at 850nm (<1% absorption), indicating significant amounts of the dye in this organ. Our initial results confirm the desired photoacoustic properties of the contrast agent, indicating its great potential to be used for imaging with a commercial array-based ultrasound scanner.

Optimization strategies for a fluorescent dye with bimodal excitation spectra: application to semiautomated proteomics

NASA Astrophysics Data System (ADS)

Patton, Wayne F.; Berggren, Kiera N.; Lopez, Mary F.

2001-04-01

Facilities engaged in proteome analysis differ significantly in the degree that they implement automated systems for high-throughput protein characterization. Though automated workstation environments are becoming more routine in the biotechnology and pharmaceutical sectors of industry, university-based laboratories often perform these tasks manually, submitting protein spots excised from polyacrylamide gels to institutional core facilities for identification. For broad compatibility with imaging platforms, an optimized fluorescent dye developed for proteomics applications should be designed taking into account that laser scanners use visible light excitation and that charge-coupled device camera systems and gas discharge transilluminators rely upon UV excitation. The luminescent ruthenium metal complex, SYPRO Ruby protein gel stain, is compatible with a variety of excitation sources since it displays intense UV (280 nm) and visible (470 nm) absorption maxima. Localization is achieved by noncovalent, electrostatic and hydrophobic binding of dye to proteins, with signal being detected at 610 nm. Since proteins are not covalently modified by the dye, compatibility with downstream microchemical characterization techniques such as matrix-assisted laser desorption/ionization-mass spectrometry is assured. Protocols have been devised for optimizing fluorophore intensity. SYPRO Ruby dye outperforms alternatives such as silver staining in terms of quantitative capabilities, compatibility with mass spectrometry and ease of integration into automated work environments.

Effect of wavelength and dye selection on biosensor response

NASA Astrophysics Data System (ADS)

Ligler, Frances S.; Breslin, Kristen A.; Cao, Lynn K.; Anderson, George P.

1995-05-01

The availability of low cost laser diodes and new fluorescent dyes has made portable biosensors a reality. Previously, we have examined the variation in the fluorescent signal generated in an antigen-antibody reaction when the antigen is labeled with dyes exciting at different wavelengths. In this study, we looked at the effect of changing dyes and wavelengths on a sandwich immunoassay for the F1 antigen from Yersinia pestis, the etiologic agent of plaque. The F1 immunoassay has previously been demonstrated to work in serum, plasma, and even whole blood, when performed using a fiber optic biosensor. In this study, we demonstrated that changing to cyanine dyes enhanced the sensitivity of the detection without altering the immunochemistry of the assay.

Stimulated emission and optical properties of pyranyliden fragment containing compounds in PVK matrix

NASA Astrophysics Data System (ADS)

Vembris, Aivars; Zarins, Elmars; Kokars, Valdis

2017-10-01

Organic solid state lasers are thoughtfully investigated due to their potential applications in communication, sensors, biomedicine, etc. Low amplified spontaneous emission (ASE) excitation threshold value is essential for further use of the material in devices. Intramolecular interaction limits high molecule density load in the matrix. It is the case of the well-known red light emitting laser dye - 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM). The lowest ASE threshold value of the mentioned laser dye could be obtained within the concentration range between 2 and 4 wt%. At higher concentration threshold energy drastically increases. In this work optical and ASE properties of three original DCM derivatives in poly(N-vinylcarbazole) (PVK) at various concentrations will be discussed. One of the derivatives is modified DCM dye in which the methyl substituents in the electron donor part have been replaced with bulky trityloxyethyl groups (DWK-1). These sterically significant functional groups do not influence electron transitions in the dye but prevent aggregation of the molecules. The chemical structure of the second investigated compound is similar to DWK-1 where the methyl group is replaced with the tert-butyl substituent (DWK-1TB). The third derivative (DWK-2) consists of two N,N-di(trityloxyethyl)amino electron donor groups. All results were compared with DCM:PVK system. Photoluminescence quantum yield (PLQY) is up to ten times larger for DWK-1TB with respect to DCM systems. Bulky trityloxyethyl groups prevent aggregation of the molecules thus decreasing interaction between dyes and amount of non-radiative decays. The red shift of the photoluminescence and amplified spontaneous emission at higher concentrations were observed due to the solid state solvation effect. The increase of the investigated dye density in the matrix with a smaller reduction in PLQY resulted in low ASE threshold energy. The lowest threshold value was obtained around 21 μJ/cm2 (2.1 kW/cm2) in DWK-1TB:PVK films.

CAPILLARY ELECTROPHORESIS/LASER-INDUCED FLUORESCENCE DETECTION OF FLUORESCEIN AS A GROUNDWATER MIGRATION TRACER

EPA Science Inventory

Capillary electrophoresis (CE) has been applied to the determination of the groundwater migration tracer dye fluorescein based on laser-induced fluorescence (LIF) detection and compared to determinations obtained with traditional spectrofluorimetry. Detection limits of injected d...

Photodynamic Inactivation of Actinomyces naeslundii in Comparison With Chlorhexidine and Polyhexanide--A New Approach for Antiseptic Treatment of Medication-Related Osteonecrosis of the Jaw?

PubMed

Hafner, Sigurd; Ehrenfeld, Michael; Storz, Enno; Wieser, Andreas

2016-03-01

Local antimicrobial therapy is a fundamental principle in the treatment of lesions of medication-related osteonecrosis of the jaw. Antimicrobial photodynamic therapy (aPDT) as a local application for the treatment of microbial infections has become more widely used in recent years. In the mouth, the bone surface is in constant contact with saliva and thus cannot be kept sterile, making the development of strategies for disinfection even more important. Different methods currently in use include local rinses with chlorhexidine (CHX), polyhexanide (PHX), or aPDT. This study compared the efficiency of these 3 methods. The in vitro activity of 3 different agents against slowly growing Actinomyces naeslundii isolated from a patient with osteonecrosis was evaluated. PHX 0.04% solution, CHX 0.12% solution, and methylene blue (MB) based dye with a laser light of 660-nm wavelength (aPDT) were compared. The decrease in colony-forming units by each method was measured using an in vitro killing assay based on a water-exposed surface in a well plate. MB dye with laser (10 seconds) decreased the bacterial load by more than 4 orders of magnitude and was superior to PHX and CHX exposure for 60 seconds. Laser exposure alone and MB dye exposure alone decreased bacterial loads slightly, but less efficiently than 60-second exposure to PHX or CHX. The most effective means of decreasing colony-forming units was achieved by a combination of laser light and dye, which also can be used clinically. Copyright © 2016 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Random lasing in dye-doped polymer dispersed liquid crystal film

NASA Astrophysics Data System (ADS)

Wu, Rina; Shi, Rui-xin; Wu, Xiaojiao; Wu, Jie; Dai, Qin

2016-09-01

A dye-doped polymer-dispersed liquid crystal film was designed and fabricated, and random lasing action was studied. A mixture of laser dye, nematic liquid crystal, chiral dopant, and PVA was used to prepare the dye-doped polymer-dispersed liquid crystal film by means of microcapsules. Scanning electron microscopy analysis showed that most liquid crystal droplets in the polymer matrix ranged from 30 μm to 40 μm, the size of the liquid crystal droplets was small. Under frequency doubled 532 nm Nd:YAG laser-pumped optical excitation, a plurality of discrete and sharp random laser radiation peaks could be measured in the range of 575-590 nm. The line-width of the lasing peak was 0.2 nm and the threshold of the random lasing was 9 mJ. Under heating, the emission peaks of random lasing disappeared. By detecting the emission light spot energy distribution, the mechanism of radiation was found to be random lasing. The random lasing radiation mechanism was then analyzed and discussed. Experimental results indicated that the size of the liquid crystal droplets is the decisive factor that influences the lasing mechanism. The surface anchor role can be ignored when the size of the liquid crystal droplets in the polymer matrix is small, which is beneficial to form multiple scattering. The transmission path of photons is similar to that in a ring cavity, providing feedback to obtain random lasing output. Project supported by the National Natural Science Foundation of China (Grant No. 61378042), the Colleges and Universities in Liaoning Province Outstanding Young Scholars Growth Plans, China (Grant No. LJQ2015093), and Shenyang Ligong University Laser and Optical Information of Liaoning Province Key Laboratory Open Funds, China.

Electrically assisted bandedge mode selection of photonic crystal lasing in chiral nematic liquid crystals

NASA Astrophysics Data System (ADS)

Wang, Chun-Ta; Chen, Chun-Wei; Yang, Tzu-Hsuan; Nys, Inge; Li, Cheng-Chang; Lin, Tsung-Hsien; Neyts, Kristiaan; Beeckman, Jeroen

2018-01-01

Selection of the bandedge lasing mode of a photonic crystal laser has been realized in a fluorescent dye doped chiral nematic liquid crystal by exerting electrical control over the mode competition. The bandedge lasing can be reversibly switched from the short-wavelength edge mode to the long-wavelength edge mode by applying a voltage of only 20 V, without tuning the bandgap. The underlying mechanism is the field-induced change in the order parameter of the fluorescent dye in the liquid crystal. The orientation of the transition dipole moment determines the polarization state of the dye emission, thereby promoting lasing in the bandedge mode that favors the emission polarization. Moreover, the dynamic mode-selection capability is retained upon polymer-stabilizing the chiral nematic liquid crystal laser. In the polymer-stabilized system, greatly improved stability and lasing performance are observed.

Laser Assisted Cancer Immunotherapy: An Experimental Theraputic Approach in Balb/c Mice

NASA Astrophysics Data System (ADS)

Gray, John

2005-03-01

Among the different therapeutic approaches to treat superficial malignant tumors, Laser Assisted Cancer Immunotherapy (LACI) shows promise. Experiments are in progress in our laboratory based on the concept of LACI which utilizes a light absorbing dye (Indocyanine Green, ICG), an immunoadjuvant (Glycated Chitosan, GC), and an infrared diode laser (1-15w) operating at 804 nm. Superficial tumors (5 to 7 mm in diameter) of the T4 cell line are grown in an animal model (Balb/C mice). The tumors are injected with ICG and GC prior to interstitial/surface irradiation of the tumor. The tumors' internal temperatures are monitored during the irradiation by invasive (microthermocouples) as well as noninvasive (infrared detector) modes. Along with the various experimental parameters, only the laser delivery (interstitial/surface) and laser intensity are varied in this initial stage so that the tumor temperature is in the range of 55 degrees C to 65 degrees C to ensure hyperthermic cell killing. The goal of the project is to determine the precise temperature range through which primary tumor necrosis and a vigorous immune response will end in tumor elimination. Experimental results coupled with a theoretical framework of laser-tissue interactions will be presented in the context of this therapeutic approach.

Control of intracellular ionic concentrations by mid-infrared laser irradiation

NASA Astrophysics Data System (ADS)

Takebe, G.; Yamauchi, T.; Shimizu, Y.; Dougakiuchi, T.

2018-02-01

We successfully induced intracellular ion concentration changes in live culture cells using mid-infrared laser irradiation. The laser used for irradiation was a quantum cascade laser with a wavelength of 6.1 micrometers. We tuned the power of the laser to be between 30 to 60 mW at the sample. Cell lines, namely HeLa and Chinese hamster ovary cell lines, were used. They were cultured on specially fabricated silicon-bottom dishes. Live cells were stained using ion-sensitive dyes such as Calcium Green-1. The mid-infrared light was incident on the cell samples from the bottom of the dish through the silicon plate, and fluorescence imaging of the ion concentrations was performed using an upright fluorescence microscope placed on top of the sample stage. The mid-infrared lasers were operated in the continuous wave mode and light irradiations onto the cells were temporally controlled using a mechanical shutter in a periodical on-and-off pattern in the second timescale. The cells showed oscillations in their ionic concentration, which was synchronized with the periodical mid-infrared irradiation, and the threshold power needed for evoking the ion concentration change was dependent on the cell types and ion species. These results demonstrated that mid-infrared light directly changed the ionic response within cells and had the ability to change cell functions.

All-Union Conference on Laser Optics, 4th, Leningrad, USSR, January 13-18, 1984, Proceedings

NASA Astrophysics Data System (ADS)

Bukhenskii, M. F.

1984-08-01

The papers presented in this volume provide an overview of current theoretical and experimental research in laser optics. Topics discussed include electronically controlled tunable lasers, nonlinear phenomena in fiber-optic waveguides, holographic distributed-feedback dye lasers, and new developments in solid-state lasers. Papers are also presented on the generation of picosecond pulses through self-Q-switching in a distributed-feedback laser, temporal compression of light pulses during stimulated backscattering, and optimization of second harmonic generation in a multimode Nd:glass laser.

[The use of lasers in dermatology].

PubMed

Lecocq, C; Pirard, D; del Marmol, V; Berlingin, E

2013-01-01

Albert Einstein is undoubtedly the father of lasers. But it is not until 1964 that the first dermatological lasers were introduced. The Nd-YAG laser, the CO2 laser were developed by Kumar Patel. In a 40 year period lasers not only were diversified but have also become safer and miniaturized. This article hopes to strengthen general practionners' and specialist's knowledge of the different categories of available lasers. The most frequently used ones are ablative lasers (CO2-Erbium), vascular lasers (Nd-YAG, KTP, pulsed dye laser) and the pigment lasers (Q-Switched Nd-YAG, Alexandrite). A description of these lasers and their indications in dermatology will be discussed.

High Affinity Macrocycle Threading by a Near-Infrared Croconaine Dye with Flanking Polymer Chains

PubMed Central

Liu, Wenqi; Peck, Evan M.; Smith, Bradley D.

2016-01-01

Croconaine dyes have narrow and intense absorption bands at ~800 nm, very weak fluorescence, and high photostabilities, which combine to make them very attractive chromophores for absorption-based imaging or laser heating technologies. The physical supramolecular properties of croconaine dyes have rarely been investigated, especially in water. This study focuses on a molecular threading process that encapsulates a croconaine dye inside a tetralactam macrocycle in organic or aqueous solvent. Macrocycle association and rate constant data are reported for a series of croconaine structures with different substituents attached to the ends of the dye. The association constants were highest in water (Ka ~109 M−1), and the threading rate constants (kon) increased in the solvent order H2O > MeOH > CHCl3. Systematic variation of croconaine substituents located just outside the croconaine/macrocycle complexation interface hardly changed Ka but had a strong influence on kon. A croconaine dye with N-propyl groups at each end of the structure exhibited a desirable mixture of macrocycle threading properties; that is, there was rapid and quantitative croconaine/macrocycle complexation at relatively high concentrations in water, and no dissociation of the pre-assembled complex when it was diluted into a solution of fetal bovine serum, even after laser induced photothermal heating of the solution. The combination of favorable near-infrared absorption properties and tunable mechanical stability makes threaded croconaine/macrocycle complexes very attractive as molecular probes or as supramolecular composites for various applications in absorption-based imaging or photothermal therapy. PMID:26807599

Neodymium-yttrium aluminum garnet laser versus pulsed dye laser in erythemato-telangiectatic rosacea: comparison of clinical efficacy and effect on cutaneous substance (P) expression.

PubMed

Salem, Samar Abdallah M; Abdel Fattah, Nermeen S A; Tantawy, Samah M A; El-Badawy, Nafissa M A; Abd El-Aziz, Yasser A

2013-09-01

Different laser systems are reported to be effective in treatment of telangiectasia and erythema, but comparative studies on 1064-nm neodymium-yttrium aluminum garnet (Nd-YAG) laser and pulsed dye laser (PDL) in treatment of erythemato-telangiectatic rosacea are lacking. Substance (P) is implicated in rosacea pathogenesis. To compare the effect of Nd-YAG laser and PDL on erythemato-telangiectatic rosacea, both clinically and immunohistochemically on cutaneous substance (P) expression. This split-face comparative study included 15 patients with erythemato-telangiectatic rosacea treated on the right side with Nd-YAG laser and on the left side with PDL: three sessions, 4 weeks apart. Evaluation of the patients was done using erythema and telangiectasia grading scores, patient's self-assessment, physicians' clinical assessment of the patient, and immunohistochemical assessment of substance (P). One month after the three laser sessions, excellent response was achieved in 73.3% of patients after Nd-YAG and in 53.3% of patients after PDL with significantly lower substance (P) concentration after Nd-YAG laser than after PDL. Positive correlations were found between the decrease in erythema and telangiectasia grading scores and the decrease in substance (P) concentration. The use of Nd-YAG laser and PDL appears to be safe and effective measures in treatment of erythemato-telangiectatic rosacea. Both types of laser decrease the concentration of substance (P) in the skin. This effect is more pronounced with Nd-YAG laser. © 2013 Wiley Periodicals, Inc.

Investigation of the spectral properties of a squarylium near-infrared dye and its complexation with Fe(III) and Co(II) ions

NASA Astrophysics Data System (ADS)

Tarazi, Leila; Narayanan, Nara; Sowell, John; Patonay, Gabor; Strekowski, Lucjan

2002-01-01

The spectral features of the squarylium dye NN525 in different solutions and its complexation with several metal ions were investigated. The absorbance maximum of the dye is at 669 nm in tetrahydrofuran. This value matches the output of a commercially available laser diode (650 nm), thus making use of such a source practical for excitation. The emission maximum of the dye in tetrahydrofuran is at 676 nm. The addition of either Fe(III) ion or Co(II) ion resulted in fluorescence quenching of the dye. The detection limit is 6.24×10 -8 M for Fe(III) ion and 1.55×10 -8 M for Co(II) ion. The molar ratio of the metal to the dye was established to be 1:1 for both metal ions. The stability constant KS of the metal-dye complex was calculated to be 3.14×10 6 M -1 for the Fe-dye complex and 2.64×10 5 M -1 for the Co-dye complex.

Investigation of the spectral properties of a squarylium near-infrared dye and its complexation with Fe(III) and Co(II) ions.

PubMed

Tarazi, Leila; Narayanan, Nara; Sowell, John; Patonay, Gabor; Strekowski, Lucjan

2002-01-15

The spectral features of the squarylium dye NN525 in different solutions and its complexation with several metal ions were investigated. The absorbance maximum of the dye is at 669 nm in tetrahydrofuran. This value matches the output of a commercially available laser diode (650 nm), thus making use of such a source practical for excitation. The emission maximum of the dye in tetrahydrofuran is at 676 nm. The addition of either Fe(III) ion or Co(II) ion resulted in fluorescence quenching of the dye. The detection limit is 6.24 x 10(-8) M for Fe(III) ion and 1.55 x 10(-8) M for Co(II) ion. The molar ratio of the metal to the dye was established to be 1:1 for both metal ions. The stability constant Ks of the metal-dye complex was calculated to be 3.14 x 10(6) M(-1) for the Fe-dye complex and 2.64 x 10(5) M(-1) for the Co-dye complex.

Tailoring of optical properties of fluorescein using green synthesized gold nanoparticles.

PubMed

John, Jisha; Thomas, Lincy; George, Nibu A; Kurian, Achamma; George, Sajan D

2015-06-28

Dye-nanoparticle mixtures hold great promise in biological as well as photonics applications due to their capability to tailor the emission behavior of dye by tuning the nanoparticles parameters. However, as compared to the well-defined dye-nanoparticle distance, studies lack the understanding of homogenous mixtures of dye and nanoparticles. In this work, we investigate the influence of shape and concentration of gold nanoparticles prepared via green synthesis on the optical properties of fluorescein dye in a dye-nanoparticle mixture. We have investigated the radiative path of deexcitation using steady state fluorescence and the non-radiative path is probed using a laser based dual-beam thermal lens technique. The energy transfer efficiency as well as dye-nanoparticle distance is studied using both techniques. Furthermore, we have explored the influence of nanoparticles parameters on the fluorescence quantum yield of fluorescein using the thermal lens technique. The studies indicate that spherical nanoparticles are efficient quenchers while star shaped nanoparticles can probe larger dye-NP distances. The tailoring of dye properties by tuning nanoparticle parameters can be utilized in diverse areas including bioimaging, solar cells, and sensors.

Effectiveness of antimicrobial photodynamic therapy using a 660 nm laser and methyline blue dye for inactivating Staphylococcus aureus biofilms in compact and cancellous bones: An in vitro study.

PubMed

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

2015-06-01

New therapeutic modalities such as antimicrobial photodynamic therapy (APDT) has been investigated in order to be a valid alternative to the treatment of infections caused by different microorganisms. This work evaluated the in vitro effectiveness of Antimicrobial Photodynamic Therapy (APDT) using 660 nm laser combined with methylene blue dye to inactivate Staphylococcus aureus (ATCC 25923) biofilms in compact and cancellous bones specimens. Eighty specimens of compact bone and 80 specimens of cancellous bone were contaminated with a standard suspension of S. aureus and incubated for 14 days at 37°C to induce the formation of biofilms. The specimens were then divided into groups (n = 10) according to the established treatment: PS-L- (control--no treatment), PS+L- (only AM for 5 min in the dark), PS-L+90 (only laser irradiation for 90 s), PS-L+180 (only laser irradiation for 180 s), PS-L+300 (only laser irradiation for 300 s), APDT90 (APDT for 90 s), APDT180 (APDT for 180 s), and APDT300 (APDT for 300 s). The findings were statistically analyzed by ANOVA 5%. All of the experimental treatments showed a significant reduction (log 10 CFU/mL) of S. aureus biofilms in compact and cancellous bones specimens compared with the control group, and the APDT group was the most effective. Compact specimens treated with APDT showed the greatest reduction in biofilms compared with cancellous specimens, regardless of length of treatment. APDT with methylene blue dye and a 660 nm laser proved to be effective in inactivating S. aureus biofilms formed in compact and cancellous bone. Copyright © 2015 Elsevier B.V. All rights reserved.

Photodetection of early cancer by laser-induced fluorescence of a tumor-selective dye: apparatus design and realization

NASA Astrophysics Data System (ADS)

Wagnieres, Georges A.; Depeursinge, Christian D.; Monnier, Philippe; Savary, Jean-Francois; Cornaz, Piet F.; Chatelain, Andre; van den Bergh, Hubert

1990-07-01

An apparatus is designed and realized to detect "early" cancer at the surface of the hollow organs in the human body by endoscopic means. The tumor is localized by the laser induced fluorescence of a dye (HPD) which concentrates selectively in the neoplastic tissue after intravenous injection. Fluorescence contrast between the tumor and its normal surroundings is enhanced by subtracting the background autofluorescence which occurs in both types of tissue. This is done by means of 2-color digital images manipulation in real-time. Preliminary clinical tests of the apparatus demonstrated the detection of carcinoma in situ in the esophagus.

Optical property measurements of a novel type of upconverting reporter

NASA Astrophysics Data System (ADS)

Xiao, Xudong; Herring, Michael E.; Haushalter, Jeanne; Lee, Seonkyung; Kalogerakis, Kostas S.; Faris, Gregory W.

2003-07-01

We have recently developed a new type of reporter (upconverting chelate) for biomedical diagnostics. For this reporter, the light is absorbed and emitted by a lanthanide ion, rather than an organic molecule, as is the case for a typical fluorescent dye. These materials do not photobleach and have no autofluorescent background. We focus in this paper on neodymium ions complexed with the familiar chelating agents, EDTA, DPA, DTPA and DOTA. We have performed experimental measurements with one- and two-color laser light excitation for different chelate compounds. The samples are excited using two Nd:YAG-pumped dye laser systems that provide laser light near 587 nm and 800 nm. For one-color excitation, the emitted light depends quadratically on the incident laser power, as expected. Three strongly emitting lines are observed, located near 360 nm, 387 nm, and 417 nm. We observed more efficient upconversion in EDTA although the DPA chelates show comparable ground state absorbance. We have studied the influence of temporal delay between the two laser pulses and obtained the decay lifetime of the first intermediate state in the various chelated compounds.

Single event effects and laser simulation studies

NASA Technical Reports Server (NTRS)

Kim, Q.; Schwartz, H.; Mccarty, K.; Coss, J.; Barnes, C.

1993-01-01

The single event upset (SEU) linear energy transfer threshold (LETTH) of radiation hardened 64K Static Random Access Memories (SRAM's) was measured with a picosecond pulsed dye laser system. These results were compared with standard heavy ion accelerator (Brookhaven National Laboratory (BNL)) measurements of the same SRAM's. With heavy ions, the LETTH of the Honeywell HC6364 was 27 MeV-sq cm/mg at 125 C compared with a value of 24 MeV-sq cm/mg obtained with the laser. In the case of the second type of 64K SRAM, the IBM640lCRH no upsets were observed at 125 C with the highest LET ions used at BNL. In contrast, the pulsed dye laser tests indicated a value of 90 MeV-sq cm/mg at room temperature for the SEU-hardened IBM SRAM. No latchups or multiple SEU's were observed on any of the SRAM's even under worst case conditions. The results of this study suggest that the laser can be used as an inexpensive laboratory SEU prescreen tool in certain cases.

Random laser action in bovine semen

NASA Astrophysics Data System (ADS)

Smuk, Andrei; Lazaro, Edgar; Olson, Leif P.; Lawandy, N. M.

2011-03-01

Experiments using bovine semen reveal that the addition of a high-gain water soluble dye results in random laser action when excited by a Q-switched, frequency doubled, Nd:Yag laser. The data shows that the linewidth collapse of the emission is correlated to the sperm count of the individual samples, potentially making this a rapid, low sample volume approach to count determination.

Application of PDT for Uterine Cervical Cancer.

PubMed

Muroya, T; Kawasaki, K; Suehiro, Y; Kunugi, T; Umayahara, K; Akiya, T; Iwabuchi, H; Sakunaga, H; Sakamoto, M; Sugishita, T; Tenjin, Y

1999-01-01

We have been performing PDT using Excimer Dye Laser (EDL) or YAG-OPO laser, a type of low power laser, both of which have a considerably higher degree of tissue penetration even when compared to PDT using Argon Dye Laser (ADL).PDT is a relatively simple procedure without any bleeding and does not require anesthesia since it causes no pain. PDT is performed 48 h after intravenous injection of 1.5-2.0 mg/kg of PHE (Photofrin((R))). Precise spot irradiation is possible using a colposcope with an optical laser path. We also use a cervical probe which enables photoirradiation of the entire cervical canal.We have performed PDT on 131 cases (95 CIS, 31 dysplasia, 1 vulval dysplasia (VIN), 3 squamous cell carcinoma, microinvasion, and 1 CIS + endocervical adenocarcinoma, microinvasion). Of these cases, 127 became CR (96.9%). The first CR case was 10 years ago and no recurrence has been observed yet.PDT is extremely effective to preserve fertility. Except for sensitive reactions to sunlight, there are no noticeable side effects or difficulties related to pregnancy or delivery. We expect that in the near future PDT will be performed using diode lasers and without hospitalization due to new photosensitizers which have shorter retention times.

Membrane Vibration Analysis Above the Nyquist Limit with Fluorescence Videogrammetry

NASA Technical Reports Server (NTRS)

Dorrington, Adrian A.; Jones, Thomas W.; Danehy, Paul M.; Pappa, Richard S.

2004-01-01

A new method for generating photogrammetric targets by projecting an array of laser beams onto a membrane doped with fluorescent laser dye has recently been developed. In this paper we review this new fluorescence based technique, then proceed to show how it can be used for dynamic measurements, and how a short pulsed (10 ns) laser allows the measurement of vibration modes at frequencies several times the sampling frequency. In addition, we present experimental results showing the determination of fundamental and harmonic vibration modes of a drum style dye-doped polymer membrane tautly mounted on a 12-inch circular hoop and excited with 30 Hz and 62 Hz sinusoidal acoustic waves. The projected laser dot pattern was generated by passing the beam from a pulsed Nd:YAG laser though a diffractive optical element, and the resulting fluorescence was imaged with three digital video cameras, all of which were synchronized with a pulse and delay generator. Although the video cameras are capable of 240 Hz frame rates, the laser s output was limited to 30 Hz and below. Consequently, aliasing techniques were used to allow the measurement of vibration modes up to 186 Hz with a Nyquist limit of less than 15 Hz.

Agricultural pest monitoring using fluorescence lidar techniques. Feasibility study

NASA Astrophysics Data System (ADS)

Mei, L.; Guan, Z. G.; Zhou, H. J.; Lv, J.; Zhu, Z. R.; Cheng, J. A.; Chen, F. J.; Löfstedt, C.; Svanberg, S.; Somesfalean, G.

2012-03-01

The fluorescence of different types of planthopper ( Hemiptera) and moth ( Lepidoptera), which constitute important Chinese agricultural pests, was investigated both in situ in a laboratory setting and remotely using a fluorescence light detection and ranging (lidar) system operating at a range of about 50 m. The natural autofluorescence of different species, as well as the fluorescence from insects that had been dusted with fluorescent dye powder for identification were studied. Autofluorescence spectra of both moths and planthoppers show a maximum intensity peak around 450 nm. Bleaching upon long-time laser illumination was modest and did not affect the shape of the spectrum. A single dyed rice planthopper, a few mm in size, could be detected at 50 m distance by using the fluorescence lidar system. By employing various marking dyes, different types of agricultural pest could be determined. We suggest that lidar may be used in studies of migration and movement of pest insects, including studies of their behavior in the vicinity of pheromone traps and in pheromone-treated fields.

Fundamental Study of Nuclear Pumped Laser Plasmas.

DTIC Science & Technology

1980-12-23

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

Bibliography of Soviet Laser Developments, No. 16, April - June 1974

DTIC Science & Technology

1974-11-01

Radiofiz Acta physica polonica Bulletin de I’Academic Polonaise del Sciences. Serie des Sciences Terhniqurs Akademiya nauk Armyanskoy SSR. DokUdy...V. Kryukov (0). Spectral kinetics of radiation from complex organic dye solution lasers. Acta phys. et ehem. Szeged, v. 19, no

Investigations of coherent anti-Stokes Raman spectroscopy /CARS/ for combustion diagnostics

NASA Technical Reports Server (NTRS)

Eckbreth, A. C.; Hall, R. J.; Shirley, J. A.

1979-01-01

Investigations of coherent anti-Stokes Raman spectroscopy (CARS) in a variety of flames are presented. Thermometry has received the primary emphasis in these studies, but species spectral and sensitivity studies will also be described. CARS is generated by mixing a 10 pps, frequency-doubled neodymium 'pump' laser with a spectrally broadband, laser-pumped, Stokes-shifted dye laser. This approach obviates the requirement to frequency scan the dye laser and generates the entire CARS spectrum with each pulse permitting, in principle, instantaneous measurements of medium properties. CARS spectra of N2, CO, O2, H2O, CO2 and CH4 in flames will be presented. In general these spectra exhibit very good agreement with computer synthesized spectra and permit measurements of temperature and species concentration. To illustrate the applicability of CARS to practical combustion diagnostics, CARS signatures from N2 have been employed to map the temperature field throughout a small, luminous, highly sooting propane diffusion flame

Temporal measurement on and using pulses from laser-like emission obtained from styrylpyridinium cyanine dye

NASA Astrophysics Data System (ADS)

Dharmadhikari, Aditya; Bhowmik, Achintya; Ahyi, Ayayi; Thakur, Mrinal

2000-03-01

We have recently reported observation of spectral narrowing and high-conversion laser-like emission in a solution of styrylpyridinium cynanine dye (SPCD) at a low threshold energy, pumped with the second-harmonic of a picosecond Nd:YAG laser. Fundamental and second-harmonic pulses from a Nd:YAG laser of 80 ps duration at 10 Hz repetition rate were used to pump 0.1 mol/l concentration of SPCD in methanol in two separate pumping arrangements. A highly directional emission was observed in both the pumping arrangements without incorporating any mirrors. The pulse duration of spectrally narrowed emission in both cases was measured by background-free SHG intensity autocorrelation technique. A BBO crystal was used for the autocorrelation measurement. The measured duration of the pulses was 40 ps. These pulses having a spectral linewidth of 10 nm (FWHM) were used as a probe to measure the gain in SPCD solution in a pump-probe set up. The results will be discussed.

[Electronic spectra of triphenodioxazines dyes by modified PPP-MO method].

PubMed

Wang, Xue-jie

2002-02-01

The triphenodioxazines dyes have good colour and luster, excellent colour fastness to light, and strong painted. They are used as the dyes and pigment extensively, and also be used as the photoelectronic transformation, laser dyes and far-infrared anti-radiation material. The colour and constitution of triphenodioxazines dyes were evaluated by means of the modified PPP-SCF-MO method with variable R, beta approximation. The calculated wavelengths of maximum absorption are in good agreement with experimental results. It was found that there exists a good correlated relationship between the wavenumber of fluorescence maximum nu fl and the calculated fluorescence emission energy delta Efl, as nu fl = 11.6837 delta Efl + 3.3485(k.cm-1), r = 0.9547. The relationship between structure of molecular and properties of electronic spectra has been discussed.

Long-term effects of laser-imiquimod combination in the treatment of late-stage melanoma patients

NASA Astrophysics Data System (ADS)

Naylor, Mark F.; Le, Henry; Li, Xiaosong; Nordquist, Robert E.; Hode, Tomas; Liu, Hong; Chen, Wei R.

2012-03-01

Topical application of a potent immunological modulator, imiquimod, followed by laser irradiation has been used for the treatment of late-stage melanoma patients. This novel approach, laser-assisted laser immunotherapy (LIT), targets the root course of melanoma, a highly metastatic cancer. We started a phase I clinical trial in 2006 with promising initial outcomes. The laser-imiquimod combination showed significant palliative effects for these patients with multiple treatment cycles. For the returning patients, we found that the recurrent tumors were less aggressive than usually seen in untreated patients. The current protocol uses a light-absorbing dye for selective laser photothermal interaction with a non-invasive treatment mode. It has limitations for patient treatment, particularly for large, deeper tumors, and for patients with dark pigmented skins. This study provides some information on the treated patients (both stage IV and stage IV) during the past several years. We also discuss the future directions of LIT, particularly in the area of photothermal treatment mode with a new approach of interstitial irradiation. The current results in melanoma treatment using LIT indicate that the combination of photothermal therapy and immunological stimulation may hold the key for the treatment of late-stage, metastatic cancers, not only for cutaneous cancers such as melanoma and breast cancer, but also for deep and internal tumors using different operations modes such as interstitial laser irradiation.

Physicochemical and Nonlinear Optical Properties of Novel Environmentally Benign Heterocyclic Azomethine Dyes: Experimental and Theoretical Studies

PubMed Central

Afzal, S. M.; Razvi, M. A. N.; Khan, Salman A.; Osman, Osman I.; Bakry, Ahmed H.; Asiri, Abdullah M.

2016-01-01

Novel heterocyclic azomethine dyes were prepared by the reaction of anthracene-9-carbaldehyde with different heterocyclic amines under microwave irradiation. Structures of the azomethine dyes were confirmed by the elemental analysis, mass spectrometry and several spectroscopic techniques. We studied absorbance and fluorescence spectra of the azomethine dyes in various solvents. They are found to be good absorbers and emitters. We also report photophysical properties like, extinction coefficient, oscillator strength, stokes shift and transition dipole moment. This reflects physicochemical behaviors of synthesized dyes. In addition, their intramolecular charge transfer and nonlinear optical properties, supported by natural bond orbital technique, were also studied computationally by density functional theory. The negative nonlinear refractive index and nonlinear absorption coefficient were measured for these dyes using the closed and open aperture Z-scan technique with a continuous wave helium-neon laser. These are found to vary linearly with solution concentration. PMID:27631371

Measurements of population densities of metastable and resonant levels of argon using laser induced fluorescence

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

Nikolić, M.; Newton, J.; Sukenik, C. I.

2015-01-14

We present a new approach to measure population densities of Ar I metastable and resonant excited states in low temperature Ar plasmas at pressures higher than 1 Torr. This approach combines the time resolved laser induced fluorescence technique with the kinetic model of Ar. The kinetic model of Ar is based on calculating the population rates of metastable and resonant levels by including contributions from the processes that affect population densities of Ar I excited states. In particular, we included collisional quenching processes between atoms in the ground state and excited states, since we are investigating plasma at higher pressures. Wemore » also determined time resolved population densities of Ar I 2 p excited states by employing optical emission spectroscopy technique. Time resolved Ar I excited state populations are presented for the case of the post-discharge of the supersonic flowing microwave discharge at pressures of 1.7 and 2.3 Torr. The experimental set-up consists of a pulsed tunable dye laser operating in the near infrared region and a cylindrical resonance cavity operating in TE{sub 111} mode at 2.45 GHz. Results show that time resolved population densities of Ar I metastable and resonant states oscillate with twice the frequency of the discharge.« less

Dye-enhanced protein solders and patches in laser-assisted tissue welding.

PubMed

Small, W; Heredia, N J; Maitland, D J; Da Silva, L B; Matthews, D L

1997-01-01

This study examines the use of dye-enhanced protein bonding agents in 805 nm diode laser-assisted tissue welding. A comparison of an albumin liquid solder and collagen solid-matrix patches used to repair arteriotomies in an in vitro porcine model is presented. Extrinsic bonding media in the form of solders and patches have been used to enhance the practice of laser tissue welding. Preferential absorption of the laser wavelength has been achieved by the incorporation of chromophores. Both the solder and the patch included indocyanine green dye (ICG) to absorb the 805 nm continuous-wave diode laser light used to perform the welds. Solder-mediated welds were divided into two groups (high power/short exposure and low power/long exposure), and the patches were divided into three thickness groups ranging from 0.1 to 1.3 mm. The power used to activate the patches was constant, but the exposure time was increased with patch thickness. Burst pressure results indicated that solder-mediated and patched welds yielded similar average burst strengths in most cases, but the patches provided a higher success rate (i.e., more often exceeded 150 mmHg) and were more consistent (i.e., smaller standard deviation) than the solder. The strongest welds were obtained using 1.0-1.3 mm thick patches, while the high power/short exposure solder group was the weakest. Though the solder and patches yielded similar acute weld strengths, the solid-matrix patches facilitated the welding process and provided consistently strong welds. The material properties of the extrinsic agents influenced their performance.

Plume Image Profiling of UV Laser Desorbed Biomolecules

NASA Astrophysics Data System (ADS)

Merrigan, T. L.; Hunniford, C. A.; Timson, D. J.; Catney, M.; McCullough, R. W.

2008-12-01

An experimental system, based upon the techniques of UV and IR laser desorption with time of flight mass spectrometry, has been constructed to enable the production and characterization of neutral biomolecular targets. The feasibility of the laser desorption technique for the purpose of radiation interaction experiments is investigated here. Fluorescent dye tagging and laser induced fluorescence imaging has been used to help characterize the laser produced plumes of biomolecules revealing their spatial density profiles and temporal evolution. Peak target thicknesses of 2×1012 molecules cm-2 were obtained 30 μs after laser desorption.

Polylactic acid promotes healing of photodegraded disperse orange 11 molecules

NASA Astrophysics Data System (ADS)

Stubbs, Najee; Bridgewater, Mauricio; Stubbs, Micheala; Kabir, Amin; Crescimanno, Michael; Kuzyk, Mark G.; Dawson, Nathan J.

2018-02-01

We report on the recovery of a photodegraded organic molecule mediated by a biopolymer. Amplified spontaneous emission (ASE) from disperse orange 11 (DO11) dye-doped polylactic acid (PLA) was used to monitor photodegradation while the material was being damaged by a strong pump laser. The ASE signal fully recovers over two hours time when the pump beam is blocked. The fluorescence spectra was also observed to recover after partial photobleaching the dye-doped polymer. PLA is the first biopolymer known to mediate the recovery of a photodegraded organic dye molecule.

Optical study of xanthene-type dyes in nano-confined liquid

NASA Astrophysics Data System (ADS)

Mahdi Shavakandi, Seyyed; Alizadeh, Khalil; Sharifi, Soheil; Marti, Othmar; Amirkhani, Masoud

2017-04-01

The optical activity of dye molecules in different environments is of great interest for many applications such as laser system or biological imaging. We investigate the fluorescence and absorption spectrum of nano-confined xanthene dyes (RhB and fluorescein sodium salt) in a two-phase liquid. Each show very distinct optical behavior in the water phase of a reverse microemulsion. Their optical properties such as absorption and fluorescence for different concentrations of dye and nanodroplets are investigated. We show that for the same concentration of dye in the microemulsion the peak of fluorescence intensity is varied by altering the concentration of nanodroplets. However, the trend of the change is widely different depending on the hydrophobicity of dyes. Quantum-mechanical second order perturbation theory is used to calculate the ratio of dipole moments in the ground and excited states, which accounts for the Stokes shift in fluorescence peak. Photon correlation spectroscopy is employed to check the trace of the dye in the oil phase of the microemulsion.

Nonlinearities of polymethine and squarylium molecules for optical limiting

NASA Astrophysics Data System (ADS)

Lim, Jin Hong

Optical limiting, a process that reduces transmittance at high laser input energies (irradiance, fluence), is of interest in applications where sensitive optical components, e.g. detectors, are vulnerable to damage by the laser beam. Polymethine and squarylium dyes show strong reverse saturable absorption (RSA) at 532 nm. RSA is a process by which weak linear absorption populates excited states which subsequently absorb strongly. Thus, low inputs are transmitted while high inputs are absorbed. This nonlinear absorption is determined by the ground and excited-state absorption cross sections as well as excited state lifetimes of the molecular system. We characterized a series of polymethine and squarine molecules in ethanol and polyurethane acrylate polymeric host (PUA) using Z-scan and pump-probe techniques at the second harmonic of the Nd:YAG laser system. A comparison of the properties in these two hosts is made. Some of these dyes show a large ratio of excited to ground state absorption cross section, ~200, which is larger than any previously reported values. In order to determine the wavelength dependence of the nonlinearities of these molecules, we also performed Z-scan and pump-probe experiments at wavelengths from 440 to 650 nm using a picosecond optical parametric oscillator (OPO) which is synchronously pumped by the third-harmonic of a modelocked train of Nd:YAG laser pulses. The OPO is continuously tunable from 400 to 700 nm using two critically phase-matched BBO crystals mounted for walkoff compensation. A polymethine dye in PUA (PD #3), which is one of the best polymethine dyes at 532 nm, shows strong RSA over a broad spectral range from 480 to 620 nm. while a squarylium dye shows RSA over a relatively narrow spectral range from 500 to 560 nm. However, the excited state lifetimes (~2.5 ns in PUA) are shorter than desirable for good nanosecond optical limiting (10 ns) and at high inputs (>=0.36 J/cm2) the limiting properties are reduced. Extensive measurements of these molecules along with computer modeling indicate that the reduced limiting at high inputs is due to molecular degradation induced after a trans-cis conformational change. Evidence for this and possible methods to eliminate this problem are presented.

Development of a passively Q-switched Nd:YAG microchip laser for use in the Satellite Laser Ranging 2000 project

NASA Astrophysics Data System (ADS)

Gompers, Samuel Leo

Presently, NASA is designing a replacement for its existing satellite laser ranging systems. These systems are used to measure Earth-satellite distances, tectonic plate movement, variations in rotational motion and other geodetic phenomena. Satellite Laser Ranging 2000 (SLR2000) is envisioned as a fully automated, sub- centimeter accuracy, eye-safe, low-cost replacement to the current SLR systems. It is expected to overcome present limitations by operating autonomously; being free of optical, chemical or electrical hazards; and having a greater average time between failures. Expected shot range precision is about one centimeter with normal point precision of better than three centimeters. This system will have twenty-four hour tracking coverage. SLR2000 specifications dictate operation at visible wavelengths with eye-safe energies on the order of one hundred microjoules and repetition rates on the order of two kilohertz. The optical subsystem of SLR2000 includes a passively Q- switched Nd:YAG microlaser. Passive Q-switching will be achieved using a saturable absorber and offers a number of advantages over the mode-locked lasers currently used in ranging stations: no need for long resonators with tight thermal control; no electro-optic switch required for single pulse selection; saturable absorbers precluding the use of carcinogenic dyes and solvents; and RF drive frequency electronics not tied to the resonator length of the laser cavity. The presented work describes the research and development of a prototype laser used to produce the energies, repetition rates and pulsewidths required for SLR2000. Optimization theories and models were applied to the laser design in order to accurately predict and assess performance characteristics of both gain medium and saturable absorber. Data were obtained which illustrated the affect of pump laser saturation and thermal lensing of the gain medium. Important laboratory skills and techniques were acquired in the design and construction of passively Q-switched microlasers.

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

NASA Astrophysics Data System (ADS)

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

1997-05-01

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

Comparative proteomic analysis using samples obtained with laser microdissection and saturation dye labelling.

PubMed

Wilson, Kate E; Marouga, Rita; Prime, John E; Pashby, D Paul; Orange, Paul R; Crosier, Steven; Keith, Alexander B; Lathe, Richard; Mullins, John; Estibeiro, Peter; Bergling, Helene; Hawkins, Edward; Morris, Christopher M

2005-10-01

Comparative proteomic methods are rapidly being applied to many different biological systems including complex tissues. One pitfall of these methods is that in some cases, such as oncology and neuroscience, tissue complexity requires isolation of specific cell types and sample is limited. Laser microdissection (LMD) is commonly used for obtaining such samples for proteomic studies. We have combined LMD with sensitive thiol-reactive saturation dye labelling of protein samples and 2-D DIGE to identify protein changes in a test system, the isolated CA1 pyramidal neurone layer of a transgenic (Tg) rat carrying a human amyloid precursor protein transgene. Saturation dye labelling proved to be extremely sensitive with a spot map of over 5,000 proteins being readily produced from 5 mug total protein, with over 100 proteins being significantly altered at p < 0.0005. Of the proteins identified, all showed coherent changes associated with transgene expression. It was, however, difficult to identify significantly different proteins using PMF and MALDI-TOF on gels containing less than 500 mug total protein. The use of saturation dye labelling of limiting samples will therefore require the use of highly sensitive MS techniques to identify the significantly altered proteins isolated using methods such as LMD.

High resolution imaging of intracellular oxygen concentration by phosphorescence lifetime

PubMed Central

Kurokawa, Hiromi; Ito, Hidehiro; Inoue, Mai; Tabata, Kenji; Sato, Yoshifumi; Yamagata, Kazuya; Kizaka-Kondoh, Shinae; Kadonosono, Tetsuya; Yano, Shigenobu; Inoue, Masahiro; Kamachi, Toshiaki

2015-01-01

Optical methods using phosphorescence quenching by oxygen are suitable for sequential monitoring and non-invasive measurements for oxygen concentration (OC) imaging within cells. Phosphorescence intensity measurement is widely used with phosphorescent dyes. These dyes are ubiquitously but heterogeneously distributed inside the whole cell. The distribution of phosphorescent dye is a major disadvantage in phosphorescence intensity measurement. We established OC imaging system for a single cell using phosphorescence lifetime and a laser scanning confocal microscope. This system had improved spatial resolution and reduced the measurement time with the high repetition rate of the laser. By the combination of ubiquitously distributed phosphorescent dye with this lifetime imaging microscope, we can visualize the OC inside the whole cell and spheroid. This system uses reversible phosphorescence quenching by oxygen, so it can measure successive OC changes from normoxia to anoxia. Lower regions of OC inside the cell colocalized with mitochondria. The time-dependent OC change in an insulin-producing cell line MIN6 by the glucose stimulation was successfully visualized. Assessing the detailed distribution and dynamics of OC inside cells achieved by the presented system will be useful to understanding a physiological and pathological oxygen metabolism. PMID:26065366

Experience with esthetic reconstruction of complex facial soft tissue trauma: application of the pulsed dye laser.

PubMed

Ebrahimi, Ali; Kazemi, Hossein Mohammad; Nejadsarvari, Nasrin

2014-08-01

Facial soft tissue injury can be one of the most challenging cases presenting to the plastic surgeon. The life quality and self-esteem of the patients with facial injury may be compromised temporarily or permanently. Immediate reconstruction of most defects leads to better restoration of form and function as well as early rehabilitation. The aim of this study was to present our experience in management of facial soft tissue injuries from different causes. We prospectively studied patients treated by plastic surgeons from 2010 to 2012 suffering from different types of blunt or sharp (penetrating) facial soft tissue injuries to the different areas of the face. All soft tissue injuries were treated primarily. Photography from all patients before, during, and after surgical reconstruction was performed and the results were collected. We used early pulsed dye laser (PDL) post-operatively. In our study, 63 patients including 18 (28.5%) women and 45 (71.5%) men aged 8-70 years (mean 47 years) underwent facial reconstruction due to soft tissue trauma in different parts of the face. Sharp wounds were seen in 15 (23%) patients and blunt trauma lacerations were seen in 52 (77%) patients. Overall, 65% of facial injuries were repaired primary and the remainder were reconstructed with local flaps or skin graft from adjacent tissues. Postoperative PDL therapy done two weeks following surgery for all scars yielded good results in our cases. Analysis of the injury including location, size, and depth of penetration as well as presence of associated injuries can aid in the formulation of a proper surgical plan. We recommend PDL in the early post operation period (two weeks) after suture removal for better aesthetic results.

Experience With Esthetic Reconstruction of Complex Facial Soft Tissue Trauma: Application of the Pulsed Dye Laser

PubMed Central

Ebrahimi, Ali; Kazemi, Hossein Mohammad; Nejadsarvari, Nasrin

2014-01-01

Background: Facial soft tissue injury can be one of the most challenging cases presenting to the plastic surgeon. The life quality and self-esteem of the patients with facial injury may be compromised temporarily or permanently. Immediate reconstruction of most defects leads to better restoration of form and function as well as early rehabilitation. Objectives: The aim of this study was to present our experience in management of facial soft tissue injuries from different causes. Patients and Methods: We prospectively studied patients treated by plastic surgeons from 2010 to 2012 suffering from different types of blunt or sharp (penetrating) facial soft tissue injuries to the different areas of the face. All soft tissue injuries were treated primarily. Photography from all patients before, during, and after surgical reconstruction was performed and the results were collected. We used early pulsed dye laser (PDL) post-operatively. Results: In our study, 63 patients including 18 (28.5%) women and 45 (71.5%) men aged 8-70 years (mean 47 years) underwent facial reconstruction due to soft tissue trauma in different parts of the face. Sharp wounds were seen in 15 (23%) patients and blunt trauma lacerations were seen in 52 (77%) patients. Overall, 65% of facial injuries were repaired primary and the remainder were reconstructed with local flaps or skin graft from adjacent tissues. Postoperative PDL therapy done two weeks following surgery for all scars yielded good results in our cases. Conclusions: Analysis of the injury including location, size, and depth of penetration as well as presence of associated injuries can aid in the formulation of a proper surgical plan. We recommend PDL in the early post operation period (two weeks) after suture removal for better aesthetic results. PMID:25337516

40 CFR 63.4292 - What operating limits must I meet?

Code of Federal Regulations, 2010 CFR

2010-07-01

... systems on the web coating/printing operation(s) and dyeing/finishing operations for which you use this... Limitations § 63.4292 What operating limits must I meet? (a) For any web coating/printing operation, slashing operation, or dyeing/finishing operation on which you use the compliant material option; web coating...

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

NASA Astrophysics Data System (ADS)

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

1995-05-01

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

Photodynamic detection and treatment of squamous cell carcinoma

NASA Astrophysics Data System (ADS)

Vari, Sandor G.; Pergadia, Vani R.; Papaioannou, Thanassis; Snyder, Wendy J.; Marcus, J.; Glassberg, Edward; Dimino-Emme, L.; Fishbein, Michael C.; Thomas, Reem; Dhondt, M. D.; Lask, Gary P.; Grundfest, Warren S.

1994-02-01

In this study the fluorescence intensity of photosensitizer in squamous cell tumors were quantified in terms of the tumor resolution rate. A He-Cd laser (442 nm - 17 mW) with a 600 micrometers core silica fiber was used for excitation. The same fiber was used for fluorescence acquisition and an optical multichannel analyzer (EG&G, OMA III) was used to analyze the fluorescence. Twelve days after carcinoma inoculation fluorescence signal from the tumor and skin (1 cm radius from the tumor) at the 12, 3, 6, and 9 o'clock positions were recorded. Benzoporphyrin Derivative (QLT, Canada -- 2 mg/kg of body weight) was then injected into the tail vein. The drug was photoactivated with a 690 nm modified argon pump cw-dye laser (Medtech) operating at 140 mW/cm2 for 15 mins. LIFS is capable of localizing in situ malignancy and evaluating photosensitizers for photodynamic fluorescence detection and therapy of tumors.

Robust remote-pumping sodium laser for advanced LIDAR and guide star applications

NASA Astrophysics Data System (ADS)

Ernstberger, Bernhard; Enderlein, Martin; Friedenauer, Axel; Schwerdt, Robin; Wei, Daoping; Karpov, Vladimir; Leisching, Patrick; Clements, Wallace R. L.; Kaenders, Wilhelm G.

2015-10-01

The performance of large ground-based optical telescopes is limited due to wavefront distortions induced by atmospheric turbulence. Adaptive optics systems using natural guide stars with sufficient brightness provide a practical way for correcting the wavefront errors by means of deformable mirrors. Unfortunately, the sky coverage of bright stars is poor and therefore the concept of laser guide stars was invented, creating an artificial star by exciting resonance fluorescence from the mesospheric sodium layer about 90 km above the earth's surface. Until now, mainly dye lasers or sumfrequency mixing of solid state lasers were used to generate laser guide stars. However, these kinds of lasers require a stationary laser clean room for operation and are extremely demanding in maintenance. Under a development contract with the European Southern Observatory (ESO) and W. M. Keck Observatory (WMKO), TOPTICA Photonics AG and its partner MPB Communications have finalized the development of a next-generation sodium guide star laser system which is available now as a commercial off-the-shelf product. The laser is based on a narrow-band diode laser, Raman fiber amplifier (RFA) technology and resonant second-harmonic generation (SHG), thus highly reliable and simple to operate and maintain. It emits > 22 W of narrow-linewidth (≈ 5 MHz) continuous-wave radiation at sodium resonance and includes a re-pumping scheme for boosting sodium return flux. Due to the SHG resonator acting as spatial mode filter and polarizer, the output is diffraction-limited with RMS wavefront error < λ/25. Apart from this unique optical design, a major effort has been dedicated to integrating all optical components into a ruggedized system, providing a maximum of convenience and reliability for telescope operators. The new remote-pumping architecture allows for a large spatial separation between the main part of the laser and the compact laser head. Together with a cooling-water flow of less than 5 l/min and an overall power consumption of < 700 W, the system offers a maximum of flexibility with minimal infrastructure demands on site. Each system is built in a modular way, based on the concept of line-replaceable units (LRU). A comprehensive system software, as well as an intuitive service GUI, allow for remote control and error tracking down to at least the LRU level. In case of a failure, any LRU can be easily replaced. With these fiber-based guide star lasers, TOPTICA for the first time offers a fully engineered, off-the-shelf guide star laser system for groundbased optical telescopes providing convenient, turn-key operation in remote and harsh locations. Reliability and flexibility will be beneficial in particular for advanced satellite and space debris tracking as well as LIDAR applications.

Apparatus for eliminating background interference in fluorescence measurements

DOEpatents

Martin, J.C.; Jett, J.H.

1984-01-06

The disclosure is directed to an apparatus for eliminating background interference during fluorescence measurements in a multiple laser flow cytometer. A biological particle stained with fluorescent dyes is excited by a laser. A fluorescence detector detects the fluorescence. The particle scatters light and a gate signal is generated and delayed until the biological particle reaches the next laser. The delayed signal turns on this next laser which excites a different stained component of the same biological particle.

Apparatus for eliminating background interference in fluorescence measurements

DOEpatents

Martin, John C.; Jett, James H.

1986-01-01

The disclosure is directed to an apparatus for eliminating background interference during fluorescence measurements in a multiple laser flow cytometer. A biological particle stained with fluorescent dyes is excited by a laser. A fluorescence detector detects the fluorescence. The particle scatters light and a gate signal is generated and delayed until the biological particle reaches the next laser. The delayed signal turns on this next laser, which excites a different stained component of the same biological particle.

Apparatus for eliminating background interference in fluorescence measurements

DOEpatents

Martin, J.C.; Jett, J.H.

1986-03-04

The disclosure is directed to an apparatus for eliminating background interference during fluorescence measurements in a multiple laser flow cytometer. A biological particle stained with fluorescent dyes is excited by a laser. A fluorescence detector detects the fluorescence. The particle scatters light and a gate signal is generated and delayed until the biological particle reaches the next laser. The delayed signal turns on this next laser, which excites a different stained component of the same biological particle. 8 figs.

Femtosecond laser-induced cell-cell surgical attachment.

PubMed

Katchinskiy, Nir; Godbout, Roseline; Goez, Helly R; Elezzabi, Abdulhakem Y

2014-04-01

Laser-induced cell-cell surgical attachment using femtosecond laser pulses is reported. We have demonstrated the ability to attach single cells using sub-10 femtosecond laser pulses, with 800 nm central wavelength delivered from a Ti:Sapphire laser. To check that the cells did not go through a cell-fusion process, a fluorescent dye Calcein AM was used to verify that the fluorescent dye did not migrate from a dyed cell to a non-dyed cell. The mechanical integrity of the attached joint was assessed using an optical tweezer. Attachment of cells was performed without the induction of cell-cell fusion, with attachment efficiency of 95%, and while preserving the cells' viability. Cell-cell attachment was achieved by delivery of one to two trains of femtosecond laser pulses lasting 15 ms each. Laser-induced ionization process led to an ultrafast reversible destabilization of the phospholipid layer of the cellular membrane. The inner cell membrane remained intact during the attachment procedure, and isolation of the cells' cytoplasm from the surrounding medium was obtained. A strong physical attachment between the cells was obtained due to the bonding of the membranes' ionized phospholipid molecules and the formation of a joint cellular membrane at the connection point. The cellular attachment technique, femtosecond laser-induced cell-cell surgical attachment, can potentially provide a platform for the creation of engineered tissue and cell cultures. © 2014 Wiley Periodicals, Inc.

Office flexible cystoscopy.

PubMed

Kavoussi, L R; Clayman, R V

1988-11-01

Since the development of the first purpose-built flexible cystoscope in 1984, flexible cystoscopy has become an accepted diagnostic and therapeutic modality. Indeed, it is estimated that more than 10 per cent of practicing urologists are already familiar with this technology. The flexible cystoscope has markedly extended the urologist's ability to examine the bladder, and it has become a valuable adjunct to the rigid cystoscope. Although the operation of this instrument is vastly different from that of its rigid counterpart, with practice, the technique can be learned. After experience is obtained with diagnostic flexible cystoscopy, the urologist will likely prefer this new instrument for bladder inspection, as it provides for a more thorough yet less morbid and less expensive examination. In the future, the development of improved and smaller instrumentation will further extend the therapeutic indications for flexible cystoscopy. Indeed, advances in laser technology are already providing the urologist with 300- to 600-micron (0.9 to 1.8F) flexible probes capable of incision (KTP laser), fulguration (Nd:YAG laser), and stone disintegration (tunable dye laser). Lastly, the skills obtained in using the flexible cystoscope are all readily applicable to the development of dexterity with the already available flexible nephroscope and the more recently developed flexible ureteroscope.

Pulsed multiwavelength laser ranging system. Ph.D. Thesis - Maryland Univ.

NASA Technical Reports Server (NTRS)

Abshire, J. B.

1982-01-01

A pulsed multiwavelength laser ranging system for measuring atmospheric delay was built and tested, and its theoretical performance limits were calculated. The system uses a dye modelocked ND:YAG laser, which transmits 70 psec wide pulses simultaneously at 1064, 532, and 355 nm. The differential delay of the 1064 and 355 nm pulses is measured by a specially calibrated waveform digitizer to estimate the dry atmospheric delay. The delay time of the 532 nm pulse is used to measure the target distance. Static crossed field photomultipliers are used as detectors for all wavelengths. Theoretical analysis shows that path curvature and atmospheric turbulence are fundamental limits to the ranging accuracy of both single and multicolor systems operating over horizontal paths. For two color systems, an additional error is caused by the uncertainty in the path averaged water vapor. The standard deviation of the multicolor instrument's timing measurements is directly proportional to the laser pulse width plus photomultiplier jitter divided by the square root of the received photoelectron number. The prototype system's maximum range is km, which is limited by atmospheric and system transmission losses at 355 nm. System signal detection and false alarm calculations are also presented.

Proton-Controlled Organic Microlaser Switch.

PubMed

Gao, Zhenhua; Zhang, Wei; Yan, Yongli; Yi, Jun; Dong, Haiyun; Wang, Kang; Yao, Jiannian; Zhao, Yong Sheng

2018-05-25

Microscale laser switches have been playing irreplaceable roles in the development of photonic devices with high integration levels. However, it remains a challenge to switch the lasing wavelengths across a wide range due to relatively fixed energy bands in traditional semiconductors. Here, we report a strategy to switch the lasing wavelengths among multiple states based on a proton-controlled intramolecular charge-transfer (ICT) process in organic dye-doped flexible microsphere resonant cavities. The protonic acids can effectively bind onto the ICT molecules, which thus enhance the ICT strength of the dyes and lead to a red-shifted gain behavior. On this basis, the gain region was effectively modulated by using acids with different proton-donating ability, and as a result, laser switching among multiple wavelengths was achieved. The results will provide guidance for the rational design of miniaturized lasers with performances based on the characteristic of organic optoelectronic materials.

Carbachol-induced fluid movement through methazolamide-sensitive bicarbonate production in rat parotid intralobular ducts: quantitative analysis of fluorescence images using fluorescent dye sulforhodamine under a confocal laser scanning microscope.

PubMed

Nakamoto, Tetsuji; Shiba, Yoshiki; Hirono, Chikara; Sugita, Makoto; Takemoto, Kazuhisa; Iwasa, Yoshiko; Akagawa, Yasumasa

2002-09-01

Fluid secretion is observed at the openings of ducts in the exocrine gland. It remains unclear whether the ducts are involved in fluid secretion in the salivary glands. In the present study, we investigated the exclusion of fluorescent dye from the duct lumen by carbachol (CCh) in isolated parotid intralobular duct segments to clarify the ability of the ducts for the fluid secretion. When the membrane-impermeable fluorescent dye, sulforhodamine, was added to the superfused extracellular solution, quantitative fluorescence images of the duct lumen were obtained under the optical sectioning at the level of the duct lumen using a confocal laser scanning microscope. CCh decreased the fluorescent intensity in the duct lumen during the superfusion of the fluorescent dye, and CCh flushed out small viscous substances stained with the fluorescent dye from isolated duct lumen, suggesting that CCh might induce fluid secretion in the duct, leading to the clearance of the dye and small stained clumps from the duct lumen. CCh-induced clearance of the fluorescent dye was divided into two phases by the sensitivity to external Ca2+ and methazolamide, an inhibitor for carbonic anhydrase. The initial phase was insensitive to these, and the subsequent late phase was sensitive to these. A major portion in the late phase was inhibited by removal of bicarbonate in the superfusion solution and DPC, but not low concentration of external Cl-, bumetanide or DIDS, suggesting that methazolamide-sensitive production of HCO3-, but not the Cl- uptake mechanism, might contribute to the CCh-induced clearance of the dye from the duct lumen. These results represent the first measurements of fluid movement in isolated duct segments, and suggest that carbachol might evoke fluid secretion possibly through Ca2+-activated, DPC-sensitive anion channels with HCO3- secretion in the rat parotid intralobular ducts.

A new fluorescent imaging procedure in vivo for evaluation of the retinal microcirculation in rats.

PubMed

Kimura, H; Kiryu, J; Nishiwaki, H; Ogura, Y

1995-03-01

We investigated a new method for in vivo evaluation of the retinal microcirculation in rats using a cell-permeant fluorescent dye, acridine orange (AO), which stains cell nuclei and cytoplasm, and a scanning laser ophthalmoscope (SLO). AO, which binds and interacts with DNA and RNA, and thus stains cell nuclei and cytoplasm, was administered intravenously to rats. Fluorescein angiography was performed after administration of the AO, and fundus images were recorded on S-VHS videotape by means of an SLO. Argon laser was used as an exciter of the dye. The retinal vessels were stained with the dye, rendering the retinal microvasculature clearly visible. Cell nuclei and vessel walls were observed as greater fluorescence and lesser fluorescence, respectively. Leukocytes were also observed as highly fluorescent dots moving through the vessels. The results suggest that SLO visualization of AO uptake by cells may be a useful procedure for the evaluation of retinal microcirculation in vivo in rats.

Micromanipulation and physiological monitoring of cells using two-photon excited fluorescence in cw laser tweezers

NASA Astrophysics Data System (ADS)

Sonek, Gregory J.; Liu, Yagang; Berns, Michael W.; Tromberg, Bruce J.

1996-05-01

We report the observation of two-photon fluorescence excitation and cell confinement, simultaneously, in a continuous-wave (cw) single-beam gradient force optical trap, and demonstrate its use as an in-situ probe to study the physiological state of an optically confined cell sample. At the wavelength of 1064 nm, a single focused gaussian laser beam is used to simultaneously confine, and excite visible fluorescence from, a human sperm cell that has been tagged with propidium iodide, a exogenous fluorescent dye that functions as a viability assay of cellular physiological state. The intensity at the dye peak emission wavelength of 620 nm exhibits a near-square-law dependence on incident trapping beam photon laser power, a behavior consistent with a two-photon absorption process. In addition, for a sperm cell held stationary in the optical tweezers for a period of several minutes at a constant trapping power, red fluorescence emission was observed to increase the time, indicating that the cell has gradually transitioned between a live and dead state. Two-photon excited fluorescence was also observed in chinese hamster ovary cells that were confined by cw laser tweezers and stained with either propidium iodide or Snarf, a pH-sensitive dye probe. These results suggest that, for samples suitably tagged with fluorescent probes and vital stains, optical tweezers can be used to generate their own in-situ diagnostic optical probes of cellular viability or induced photodamage, via two-photon processes.

Treatment of resistant port wine stains (PWS) with pulsed dye laser and non-contact vacuum: a pilot study.

PubMed

Kautz, Gerd; Kautz, Ingrid; Segal, Jenny; Zehren, Sabrina

2010-07-01

The blanching of resistant port wine stains (PWS) with a pulsed dye laser (PDL) requires a large number of treatments, resulting in substantial discomfort to patients, many of them children. Pneumatic skin flattening (PSF - Serenity Pro) is a new technology that generates a vacuum over the skin and reduces pain in laser-based treatments of the skin, while creating contact between the skin and an upper window. The same technology can be utilized to increase skin blood fraction while operated in a non-contact mode. The objective of this study was to test the enhancement in the efficacy of PWS treatment with PDL and Serenity Pro while vacuum is being utilized in the non-contact, blood-enrichment mode. Fifteen patients with resistant PWS underwent 1-4 treatments (interval of 5-20 weeks) under general anesthesia with a 595-nm PDL at 10-14 J/cm(2), 1.5-3 ms pulse duration, and 7-mm spot size. Lesion blanching with DCD chilling and with vacuum were photographed and compared. Better blanching of various degrees was observed on resistant PWS with the blood-enrichment technique in seven out of 11 patients who returned for follow-up. There were no cases of decrease in efficacy. Blood enrichment with the Serenity Pro non-contact vacuum technology has the potential of enhancing the capability of treating resistant port wine stains in over 50% of cases. Further studies will better quantify the number of treatments necessary for better lesion clearance. The vacuum-assisted technique may be of particular importance in view of the fact that achieving complete lesion clearance remains a challenge in PWS treatments.

Measurement of photoluminescence from a twisted-nematic liquid crystal/dye cell for an application in an energy-harvesting display

NASA Astrophysics Data System (ADS)

Ohta, Masamichi; Itaya, Shunsuke; Ozawa, Shintaro; Binti, M. Azmi; Dianah, Nada; Fujieda, Ichiro

2016-09-01

One can convert a Luminescent Solar Concentrator (LSC) to an energy-harvesting display by scanning a laser beam on it. By incorporating a guest-host system of liquid crystal (LC) and dye materials in an LSC, the power of photoluminescence (PL) utilized for either display or energy-harvesting can be adjusted to the changes in ambient lighting conditions. We have measured basic characteristics of an LC/dye cell with twisted-nematic (TN) alignment. These are absorption of the laser light, PL radiation pattern, contrast of luminance, spreading of the PL generated by a narrow laser beam, and their dependencies on the bias. The results are similar to those of the LC/dye cell with antiparallel (AP) alignment with the following exceptions. First, absorption by the TN cell depends on the bias for both polarization components of the excitation light, while the AP cell exhibits a bias dependency only for the component polarized along the alignment direction. Second, the PL from the TN cell is mostly polarized along the alignment direction on the exit side of the cell while the PL from the AP cell is mostly polarized along its alignment direction. These observations can be attributed to the fact that the polarization plane of a linearly polarized light rotates as it propagated the TN-LC layer. For both AP and TN cells, low-intensity PL is observed from the whole cell surfaces. This can degrade the contrast of a displayed image. Bias application to the cell suppresses this effect.

Effect of parameters on picosecond laser ablation of Cr12MoV cold work mold steel

NASA Astrophysics Data System (ADS)

Wu, Baoye; Liu, Peng; Zhang, Fei; Duan, Jun; Wang, Xizhao; Zeng, Xiaoyan

2018-01-01

Cr12MoV cold work mold steel, which is a difficult-to-machining material, is widely used in the mold and dye industry. A picosecond pulse Nd:YVO4 laser at 1064 nm was used to conduct the study. Effects of operation parameters (i.e., laser fluence, scanning speed, hatched space and number of scans) were studied on ablation depth and quality of Cr12MoV at the repetition rate of 20 MHz. The experimental results reveal that all the four parameters affect the ablation depth significantly. While the surface roughness depends mainly on laser fluence or scanning speed and secondarily on hatched space or number of scans. For laser fluence and scanning speed, three distinct surface morphologies were observed experiencing transition from flat (Ra < 1.40 μm) to bumpy (Ra = 1.40 - 2.40 μm) eventually to rough (Ra > 2.40 μm). However, for hatched space and number of scan, there is a small bumpy and rough zone or even no rough zone. Mechanisms including heat accumulation, plasma shielding and combustion reaction effects are proposed based on the ablation depth and processing morphology. By appropriate management of the laser fluence and scanning speed, high ablation depth with low surface roughness can be obtained at small hatched space and high number of scans.

40 CFR 63.4292 - What operating limits must I meet?

Code of Federal Regulations, 2012 CFR

2012-07-01

... Other Textiles Emission Limitations § 63.4292 What operating limits must I meet? (a) For any web coating... material option; web coating/printing operation or dyeing/finishing operation on which you use the emission... controlled web coating/printing operation or dyeing/finishing operation on which you use the emission rate...

40 CFR 63.4292 - What operating limits must I meet?

Code of Federal Regulations, 2014 CFR

2014-07-01

... Other Textiles Emission Limitations § 63.4292 What operating limits must I meet? (a) For any web coating... material option; web coating/printing operation or dyeing/finishing operation on which you use the emission... controlled web coating/printing operation or dyeing/finishing operation on which you use the emission rate...

40 CFR 63.4292 - What operating limits must I meet?

Code of Federal Regulations, 2013 CFR

2013-07-01

... Other Textiles Emission Limitations § 63.4292 What operating limits must I meet? (a) For any web coating... material option; web coating/printing operation or dyeing/finishing operation on which you use the emission... controlled web coating/printing operation or dyeing/finishing operation on which you use the emission rate...

Opto-injection into single living cells by femtosecond near-infrared laser

NASA Astrophysics Data System (ADS)

Peng, Cheng

This dissertation presents a novel technique to deliver membrane impermeable molecules into single living cells with the assistance of femtosecond (fs) near-infrared (NIR) laser pulses. This approach merges ultrafast laser technology with key biological, biomedical, and medical applications, such as gene transfection, gene therapy and drug delivery. This technique promises several major advantages, namely, very high transfection efficiency, high cell survival rate (≈100%) and fully preserved cell viabilities. It is also a promising method to deliver molecules into cells that are difficult or even completely resistant to established physical methods, such as microinjection by glass pipettes, electroporation, and biolistics. In this work, the system for fs NIR opto-injection was designed and built. Successful fs NIR opto-injection has been performed on several cell systems including single mammalian cells (bovine aortic endothelial cells), marine animal eggs (Spisula solidissima oocytes), and human cancer cells (fibrosarcoma HT1080) cultured in a tissue-like environment. The connections between laser parameters and cell responses were explored through further experiments and in-depth analyses, especially the relationship between dye uptake rate and incident laser intensity, and the relationship between pore size created on cell membranes and incident laser intensity. Dye uptake rate of the target cells was observed to depend on incident laser intensity. Pore size was found dependent on incident laser intensity. The conclusion was made that laser-induced breakdown and plasma-induced ablation in cell membrane are the physical principles that govern the process of fs NIR opto-injection.

Laser Radar Study Using Resonance Absorption for Remote Detection Of Air Pollutants

NASA Technical Reports Server (NTRS)

Igarashi, Takashi

1973-01-01

A laser radar using resonance absorption has an advantage of increased detection range and sensitivity compared with that achieved by Raman or resonance back scattering. In this paper, new laser radar system using resonance absorption is proposed and results obtained from this laser radar system are discussed. NO2, SO2 gas has an absorption spectrum at 4500 A and 3000 A respectively as shown in Fig. 1. A laser light including at least a set of an absorption peak (lambda)1 and a valley (lambda)2 is emitted into a pollutant atmosphere. The light reflected with a topographical reflector or an atmospheric Mie scattering as distributed reflectors is received and divided into two wavelength components (lambda)1 and (lambda)2. The laser radar system used in the investigation is shown in Fig', 2 and consists of a dye laser transmitter, an optical receiver with a special monochrometer and a digital processer. Table 1 shows the molecular constants of NO2, and SO2 and the dye laser used in this experiment. In this system, the absolute concentration of the pollutant gas can be measured in comparison with a standard gas cell. The concentration of NO2, SO2 as low as 0.1 ppm have been measured at 100 m depth resolution. For a 1 mJ laser output, the observable range of this system achieved up to 300 m using the distributed Mie reflector. The capability and technical limitation of the system will be discussed in detail.

Interstitial laser photochemotherapy with new anthrapyrazole drugs for the treatment of xenograft tumors.

PubMed

Paiva, M B; Saxton, R E; Letts, G A; Chung, P S; Soudant, J; Vanderwerf, Q; Castro, D J

1995-10-01

Photodynamic therapy (PDT) with lasers and new dyes has gained popularity in recent years as a minimally invasive technique with high tumoricidal effects in vitro and in some cancer patients. However, because new laser dyes are not FDA approved at present, the clinical evaluation of PDT may be years away. During the past 6 years we have used laser alone for photothermal ablation in both preclinical studies and in a large number of patients with an observed 60% tumor response rate. The 40% treatment failure led us to explore the possibility of combined therapy with lasers and standard chemotherapeutic drugs. We have recently tested a promising preclinical alternative using implantation of a bare 600-microns KTP 532 laser fiberoptic in multiple tumor sites 30 min after intratumor injection of the anthrapyrazole DUP-941. As a control, this drug was injected in 3 sites of P3 human squamous cell tumor transplants in nude mice, which led to tumor stasis without regression. Similar 400-600 mm3 tumors exposed to laser illumination alone (0.8 W for 5 sec) at multiple sites resulted in tumor regrowth after 10 weeks in 80% of the animals. However, combining interstitial laser illumination with intratumor DUP-941 injections led to complete tumor regression in 85% of the mice. We propose that intratumor drug injection followed by interstitial laser fiberoptic treatment represents a potentially useful new method for tumor ablation in advanced cancer patients.

Combined pulsed dye laser and fiberoptic Nd-YAG laser for the treatment of hypertrophic port wine stain.

PubMed

Radmanesh, Mohammed; Radmanesh, Ramin

2017-10-01

The hypertrophic Port Wine Stain (PWS) is only partially and superficially treated with the Pulsed dye laser (PDL) because of its limited depth of penetration. We used combined PDL and fiberoptic 1444-nm Nd-YAG laser to treat a case with hypertrophic PWS. After tumescent anesthesia, few holes were made by a 16-gauge needle on different sides of the lesion. The fiberoptic tip of 1444-nm Nd-YAG laser was inserted within the holes and was pushed forward while triggering. In a fan pattern and by a back and forth movement, the subcutaneous and deep dermal areas were coagulated. The skin and outer mucosal surfaces were then treated by PDL. The fiberoptic system used was Accusculpt 1444-nm Nd-YAG laser (Lutronic lasers, South Korea), and the PDL used was 585 nm Nlite system (Chromogenex UK). The parameters used for PDL were fluence = 9 Joules/cm 2 and the spot size was 5 mm. The parameters used for fiberoptic 1444-nm Nd-YAG laser were: Pulse rate = 30 Hz, pulse energy = 300 mJ, power = 6 W, and the total energy = 4000 J for the whole face and mucosa. Little sign of regression and moderate purpura were detected immediately after combined fiberoptic Nd-YAG and PDL therapy. The lesion gradually regressed within 4 months with satisfactory color and volume change. Combined fiberoptic Nd-YAG laser and PDL can be used for the treatment of deeper and superficial layers of hypertrophic PWS.

New stable tunable solid-state dye laser in the red

NASA Astrophysics Data System (ADS)

Gvishi, Raz; Reisfeld, Renata; Burshtein, Zeev; Miron, Eli

1993-08-01

A red perylene derivative was impregnated into a composite silica-gel glass, and characterized as a dye laser material. The absorption spectrum in the range 480 - 600 nm belongs to the S0 - S1 electronic transition, with a structure reflecting the perylene skeletal vibrations, of typical energy 1100 - 1200 cm-1. An additional peak between 400 and 460 nm belongs to the S0 - S2 transition. The fluorescence exhibits a mirror image relative to the S0 - S1 absorption, with a Stokes shift of about 40 nm for the 0 - 0 transition. Laser tunability was obtained in the range 605 - 630 nm using a frequency-doubled Nd:YAG laser for pumping ((lambda) equals 532 nm). This wavelength range is important for medical applications, such as photodynamic therapy of some cancer tumors. Maximum laser efficiency of approximately 2.5% was obtained at 617 nm. Maximum output was approximately 0.36 mJ/pulse at a repetition rate of 10 Hz. Minimum laser threshold obtained was 0.45 mJ/pulse. The medium losses are attributed to an excited-state singlet-singlet absorption, with an upper limit cross-section of approximately 2.5 X 10-16 cm2. The laser output was stable over more than approximately 500,000 pulses, under excitation with the green line of a copper vapor laser (510 nm), of energy density approximately 40 mJ/cm2 per pulse. Good prospects exist for a considerable enhancement in laser output efficiency.

Monitoring sperm mitochondrial respiration response in a laser trap using ratiometric fluorescence

NASA Astrophysics Data System (ADS)

Mei, Adrian; Botvinick, Elliot; Berns, Michael

2005-08-01

Sperm motility is an important area in understanding male infertility. Various techniques, such as the Computer Assisted Sperm Analysis (CASA), have been used to understand sperm motility. Sperm motility is related to the energy (ATP) production of sperm. ATP is produced by the depolarization of the membrane potential of the inner membrane of the mitochondria. In this study, a mitochondrial dye, JC-1, has been used to monitor the energetics of the mitochondria. This fluorescent dye can emit at two different wavelengths, depending on the membrane potential of the mitochondria. It can fluoresce green at low membrane potential and red at high membrane potential. The ratio of the two colors (red/green) allows for an accurate measurement of the change of membrane potential. Various experiments were conducted to quantify the behavior of the dye within the sperm and the reaction of the sperm to trap. Sperm were trapped using laser tweezers. Results have shown that the ratio drops dramatically when sperm are trapped, indicating a depolarization of the membrane. The physiological response to this depolarization is yet to be determined, but the studies indicate that the sperm could have been slightly damaged by the laser. However, knowing that sperm depolarizes their membrane when trapped can help understand how sperm react to their environment and consequently help treat male infertility.

Airborne lidar experiments at the Savannah River Plant

NASA Technical Reports Server (NTRS)

Krabill, William B.; Swift, Robert N.

1985-01-01

The results of remote sensing experiments at the Department of Energy (DOE) Savannah River Nuclear Facility utilizing the NASA Airborne Oceanographic Lidar (AOL) are presented. The flights were conducted in support of the numerous environmental monitoring requirements associated with the operation of the facility and for the purpose of furthering research and development of airborne lidar technology. Areas of application include airborne laser topographic mapping, hydrologic studies using fluorescent tracer dye, timber volume estimation, baseline characterization of wetlands, and aquatic chlorophyll and photopigment measurements. Conclusions relative to the usability of airborne lidar technology for the DOE for each of these remote sensing applications are discussed.

EFFECTS OF LASER RADIATION ON MATTER: Spectrum of the barium atom in a laser radiation field

NASA Astrophysics Data System (ADS)

Bondar', I. I.; Suran, V. V.

1990-08-01

An experimental investigation was made of the influence of a laser radiation field on the spectrum of barium atoms. The investigation was carried out by the method of three-photon ionization spectroscopy using dye laser radiation (ω = 14 800-18 700 cm - 1). The electric field intensity of the laser radiation was 103-106 V/cm. This laser radiation field had a strong influence on a number of bound and autoionizing states. The nature of this influence depended on the ratio of the excitation frequencies of bound and autoionizing states.

Flow Property Measurement Using Laser-Induced Fluorescence in the NASA Ames Interaction Heating Facility

NASA Technical Reports Server (NTRS)

Grinstead, Jay Henderson; Porter, Barry J.; Carballo, Julio Enrique

2011-01-01

The spectroscopic diagnostic technique of two photon absorption laser-induced fluorescence (TALIF) of atomic species has been applied to single-point measurements of velocity and static temperature in the NASA Ames Interaction Heating Facility (IHF) arc jet. Excitation spectra of atomic oxygen and nitrogen were recorded while scanning a tunable dye laser over the absorption feature. Thirty excitation spectra were acquired during 8 arc jet runs at two facility operating conditions; the number of scans per run varied between 2 and 6. Curve fits to the spectra were analyzed to recover their Doppler shifts and widths, from which the flow velocities and static temperatures, respectively, were determined. An increase in the number of independent flow property pairs from each as-measured scan was obtained by extracting multiple lower-resolution scans. The larger population sample size enabled the mean property values and their uncertainties for each run to be characterized with greater confidence. The average plus or minus 2 sigma uncertainties in the mean velocities and temperatures for all 8 runs were plus or minus 1.4% and plus or minus 11%, respectively.

Electronic spectroscopy of UO(2)Cl(2) isolated in solid Ar.

PubMed

Jin, Jin; Gondalia, Raj; Heaven, Michael C

2009-11-12

Laser-induced fluorescence spectra have been recorded for uranyl chloride isolated in a solid Ar matrix. Pulsed excitation was examined using a XeCl excimer laser (308 nm) and a dye laser operating in the 19500-27500 cm-1 range. Several absorption and emission band systems were observed. The emission spectra were characterized by a nearly harmonic vibrational progression with a frequency of 840 cm-1 starting at 20323 cm-1. The electronic absorption spectra were dominated by five harmonic vibrational progressions with frequencies of approximately 710 cm-1. Comparisons with theoretical calculations indicate that all of the transitions observed were associated with the UO2+2 subunit. They involved the promotion of an electron from a bonding orbital to the metal-centered 5f(delta) and 5f(phi) orbitals. Band origins and vibrational constants for five excited states were obtained. Fluorescence was observed from the lowest-energy excited state alone, regardless of the excitation wavelength. The decay curve was found to be biexponential, with characteristic decay lifetimes of 50 and 260 micros.

Pressure Studies of Protein Dynamics

DTIC Science & Technology

1989-02-26

infrared flash photolysis system with the monitoring light produced by a Spectra-Physics/ Laser Analytics tunable- diode laser and detected by a liquid...refrigerator. Time range extends from about 100 ms to 100 s. The diode laser current is modulated at 10 kHz and the signal is amplified with a PAR 5101...Photolysis is obtained with a Phase-R D 121OOC dye laser using rhodamine 6G (pulse 4 width 500 ns, 0.3 J). Kinetic spectra are obtained from about 10

Association of Er:YAG and Nd:YAG irradiation for apicoectomy and retrofilling cavity preparation compared to conventional technique: a permeability study

NASA Astrophysics Data System (ADS)

Camargo, Selma C. C.; Gavini, Giulio; Eduardo, Carlos d. P.; Aun, Carlos E.; Ribeiro, Luciano W.; Coil, Jeffrey M.

1999-05-01

The aim of this research was to evaluate dentin permeability effects at the apical cut surface prepared with Er:YAG laser and irradiated with Nd:YAG laser compared to conventional techniques. 62 extracted human teeth were divided into four groups of 7 teeth each. For Group 1 apicoectomy was performed using high speed handpiece and diamond burs. Group 2 was prepared as group 1 and lased with Nd:YAG (1W,15Hz of energy before retrograde cavity filling). For group 3 Er:YAG* laser irradiation (wavelength of 2.94μm, pulse width of 250-500μs)was used in 400mJ of energy, frequency of 6Hz, on focus mode under distilled water refrigeration and group 4 was performed as group 3 and lased with Nd:YAG (1W, 15Hz of energy before retrograde cavity filling). Permeability was evaluated by the extent of methylene blue dye penetration into the tubules. There were statistically significant differences in permeability between groups. Nd:YAG laser irradiation significantly reduced apical dentin permeability when compared to unlased groups. Er:YAG laser by itself showed higher percentage of dye penetration.

Excitation/Detection Strategies for OH Planar Laser-Induced Fluorescence Measurements in the Presence of Interfering Fuel Signal and Absorption Effects

NASA Technical Reports Server (NTRS)

Heath, Christopher M.; Anderson, Robert C.; Hicks, Yolanda R.

2011-01-01

Planar laser-induced fluorescence (PLIF) excitation/detection methods have been applied to obtain spatial distributions of the hydroxyl [OH] reacting intermediary and hydrocarbon [HC] primary species in laminar and turbulent combustion reactions. In this report, broadband and narrowband excitation/filtering techniques are explored to identify an optimal experimental configuration yielding significant fluorescent signal with low absorption losses. The combustion environments analyzed include 1) a laminar non-premixed methane/air flame and 2) a turbulent, non-premixed Jet-A/air fueled flame within a lean flame tube combustor. Hydrocarbon-based fuel and OH were excited via the R1 (1), R1(10) and R2(7) transitions of the A(sup 2)Epsilon(+) X(sup 2)pi(1,0) band using a broadband Nd:YAG pumped optical parametric oscillator (OPO) and narrowband Nd:YAG/dye laser with ultraviolet frequency extension (UVX) package. Variables tested for influence on fluorescent signal and absorption characteristics were excitation line, laser energy, exciting linewidth, combustion reactants, and test flow conditions. Results are intended to guide the transition from a dye/UVX laser to an OPO system for performing advanced diagnostics of low-emission combustion concepts.

Photophysical parameters and fluorescence quenching of 7-diethylaminocoumarin (DEAC) laser dye

NASA Astrophysics Data System (ADS)

El-Mossalamy, E. H.; Obaid, A. Y.; El-Daly, S. A.

2011-10-01

The optical properties including electronic absorption spectrum, emission spectrum, fluorescence quantum yield, and dipole moment of electronic transition of 7-diethylaminocoumarin (DEAC) laser dye have been measured in different solvents. Both electronic absorption and fluorescence spectra are red shifted as the polarity of the medium increases, indicating that the dipole moment of molecule increases on excitation. The fluorescence quantum yield of DEAC decreases as the polarity of solvent increases, a result of the role of solvent polarity in stabilization of the twisting of the intramolecular charge transfer (TICT) in excited state, which is a non-emissive state, as well as hydrogen bonding with the hetero-atom of dye. The emission spectrum of DEAC has also been measured in cationic (CTAC) and anionic (SDS) micelles, the intensity increases as the concentration of surfactant increases, and an abrupt change in emission intensity is observed at critical micelle concentration (CMC) of surfactant. 2×10 -3 mol dm -3 of DEAC gives laser emission in the blue region on pumping with nitrogen laser ( λex=337.1 nm). The laser parameters such as tuning range, gain coefficient ( α), emission cross section ( σe), and half-life energy have been calculated in different solvents, namely acetone, dioxane , ethanol, and dimethyforamide (DMF). The photoreactivity of DEAC has been studied in CCl 4 at a wavelength of 366 nm. The values of photochemical yield ( ϕc) and rate constant ( k) are determined. The interaction of organic acceptors such as picric acid (PA), tetracyanoethylene (TCNE), and 7,7,8,8-tetracynoquinonedimethane (TCNQ) with DEAC is also studied using fluorescence measurements in acetonitrile (CH 3CN); from fluorescence quenching study we assume the possible electron transfer from excited donor DEAC to organic acceptor forming non-emissive exciplex.

Rapid fabrication of mesoporous TiO2 thin films by pulsed fibre laser for dye sensitized solar cells

NASA Astrophysics Data System (ADS)

Hadi, Aseel; Alhabradi, Mansour; Chen, Qian; Liu, Hong; Guo, Wei; Curioni, Michele; Cernik, Robert; Liu, Zhu

2018-01-01

In this paper we demonstrate for the first time that a fibre laser with a wavelength of 1070 nm and a pulse width of milliseconds can be applied to generate mesoporous nanocrystalline (nc) TiO2 thin films on ITO coated glass in ambient atmosphere, by complete vaporisation of organic binder and inter-connection of TiO2 nanoparticles, without thermally damaging the ITO layer and the glass substrate. The fabrication of the mesoporous TiO2 thin films was achieved by stationary laser beam irradiation of 1 min. The dye sensitized solar cell (DSSC) with the laser-sintered TiO2 photoanode reached higher power conversion efficiency (PCE) of 3.20% for the TiO2 film thickness of 6 μm compared with 2.99% for the furnace-sintered. Electrochemical impedance spectroscopy studies revealed that the laser sintering under the optimised condition effectively decreased charge transfer resistance and increased electron lifetime of the TiO2 thin films. The use of the fibre laser with over 40% wall-plug efficiency offers an economically-feasible, industrial viable solution to the major challenge of rapid fabrication of large scale, mass production of mesoporous metal oxide thin film based solar energy systems, potentially for perovskite and monolithic tandem solar cells, in the future.

Combination of 595-nm pulsed dye laser, long-pulsed 755-nm alexandrite laser, and microdermabrasion treatment for keratosis pilaris: retrospective analysis of 26 Korean patients.

PubMed

Lee, Sang Ju; Choi, Min Ju; Zheng, Zhenlong; Chung, Won Soon; Kim, Young Koo; Cho, Sung Bin

2013-06-01

Keratosis pilaris (KP) has beenpresented as small keratotic follicular papules with or without surrounding erythema. Various treatments with laser or light therapy have been used for the management of KP with various clinical outcomes. In the present study, we investigated the efficacy and safety of a combination therapy for KP. A total of 29 anatomical sites with KP in 26 patients were treated using a 595-nm pulsed dye laser (PDL) with nonpurpuragenic fluences, a long-pulsed 755-nm alexandrite laser, and microdermabrasion. Clinical improvement was assessed by comparing preand posttreatment clinical photographs and patient satisfaction rates. Evaluation of the clinical results three months after the treatments showed that 12 of the 29 anatomical sites (41.4%) demonstrated Grade 3 clinical improvement, ten (34.5%) had Grade 2 clinical improvement, four (13.8%) showed Grade 1 improvement, and three (10.3%) showed Grade 4 improvement. We observed that KP lesions improved not only in erythema and skin texture, but also in brownish dyschromias. Potential adverse events were not observed, except prolonged posttherapy scaling. Our observations demonstrate that combination therapy using a 595-nm PDL, a long-pulsed 755-nm alexandrite laser, and microdermabrasion can have a positive therapeutic effect on KP.

Application of PDT for Uterine Cervical Cancer

PubMed Central

Kawasaki, K.; Suehiro, Y.; Kunugi, T.; Umayahara, K.; Akiya, T.; Iwabuchi, H.; Sakunaga, H.; Sakamoto, M.; Sugishita, T.; Tenjin, Y.

1999-01-01

We have been performing PDT using Excimer Dye Laser (EDL) or YAG-OPO laser, a type of low power laser, both of which have a considerably higher degree of tissue penetration even when compared to PDT using Argon Dye Laser (ADL). PDT is a relatively simple procedure without any bleeding and does not require anesthesia since it causes no pain. PDT is performed 48 h after intravenous injection of 1.5–2.0 mg/kg of PHE (Photofrin®). Precise spot irradiation is possible using a colposcope with an optical laser path. We also use a cervical probe which enables photoirradiation of the entire cervical canal. We have performed PDT on 131 cases (95 CIS, 31 dysplasia, 1 vulval dysplasia (VIN), 3 squamous cell carcinoma, microinvasion, and 1 CIS + endocervical adenocarcinoma, microinvasion). Of these cases, 127 became CR (96.9%). The first CR case was 10 years ago and no recurrence has been observed yet. PDT is extremely effective to preserve fertility. Except for sensitive reactions to sunlight, there are no noticeable side effects or difficulties related to pregnancy or delivery. We expect that in the near future PDT will be performed using diode lasers and without hospitalization due to new photosensitizers which have shorter retention times. PMID:18493501

Modern retinal laser therapy

PubMed Central

Kozak, Igor; Luttrull, Jeffrey K.

2014-01-01

Medicinal lasers are a standard source of light to produce retinal tissue photocoagulation to treat retinovascular disease. The Diabetic Retinopathy Study and the Early Treatment Diabetic Retinopathy Study were large randomized clinical trials that have shown beneficial effect of retinal laser photocoagulation in diabetic retinopathy and have dictated the standard of care for decades. However, current treatment protocols undergo modifications. Types of lasers used in treatment of retinal diseases include argon, diode, dye and multicolor lasers, micropulse lasers and lasers for photodynamic therapy. Delivery systems include contact lens slit-lamp laser delivery, indirect ophthalmocope based laser photocoagulation and camera based navigated retinal photocoagulation with retinal eye-tracking. Selective targeted photocoagulation could be a future alternative to panretinal photocoagulation. PMID:25892934

Acid azo dye remediation in anoxic-aerobic-anoxic microenvironment under periodic discontinuous batch operation: bio-electro kinetics and microbial inventory.

PubMed

Venkata Mohan, S; Suresh Babu, P; Naresh, K; Velvizhi, G; Madamwar, Datta

2012-09-01

Functional behavior of anoxic-aerobic-anoxic microenvironment on azo dye (C.I. Acid black 10B) degradation was evaluated in a periodic discontinuous batch mode operation for 26 cycles. Dye removal efficiency and azo-reductase activity (30.50 ± 1 U) increased with each feeding event until 13th cycle and further stabilized. Dehydrogenase activity also increased gradually and stabilized (2.0 ± 0.2 μg/ml) indicating the stable proton shuttling between metabolic intermediates providing higher number of reducing equivalents towards dye degradation. Voltammetric profiles showed drop in redox catalytic currents during stabilized phase also supports the consumption of reducing equivalents towards dye removal. Change in Tafel slopes, polarization resistance and other bioprocess parameters correlated well with the observed dye removal and biocatalyst behavior. Microbial community analysis documented the involvement of specific organism pertaining to aerobic and facultative functions with heterotrophic and autotrophic metabolism. Integrating anoxic microenvironment with aerobic operation might have facilitated effective dye mineralization due to the possibility of combining redox functions. Copyright © 2012 Elsevier Ltd. All rights reserved.

Counterion dye staining of proteins in one- and two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis and tryptic gel digestion of stained protein for mass spectrometry.

PubMed

Cong, Wei-Tao; Wang, Xu; Hwang, Sun-Young; Jin, Li-Tai; Choi, Jung-Kap

2012-01-01

A fast and matrix-assisted laser desorption/ionization mass spectrometry compatible protein staining method in one- and two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis is described. It is based on the counterion dye staining method that employs oppositely charged two dyes, zincon and ethyl violet, to form an ion-pair complex. The protocol, including fixing, staining, and quick washing steps, can be completed in 1-1.5 h, depending upon gel thickness. It has the sensitivity comparable to the colloidal Coomassie Brilliant Blue G stain using phosphoric acid as a component of staining solution (4-8 ng). The counterion dye stain does not induce protein modifications that complicate interpretation of peptide mapping data from mass spectrometry. Considering the speed, sensitivity, and compatibility with mass spectrometry, the counterion dye stain may be more practical than any other dye-based protein stains for routine proteomic researches.

Enhanced optical, thermal and piezoelectric behavior in dye doped potassium acid phthalate (KAP) single crystal

NASA Astrophysics Data System (ADS)

Rao, G. Babu; Rajesh, P.; Ramasamy, P.

2017-06-01

Dye inclusion crystals have attracted researchers in the context of crystal growth for applications in solid state lasers. Pure and 0.1 mol% amaranth doped KAP single crystals, were grown from aqueous solutions by slow evaporation technique at room temperature. The grown crystals are up to the dimension of 12×10×3 mm3. Attempt is made to improve the growth rate, optical, piezoelectric and photoconductive properties of pure KAP single crystal with addition of amaranth dye as a dopant. Various characterization studies were made for both pure and dye doped KAP. Thermal stability of the crystals is tested from thermogravimetric and differential thermal analysis (TG/DTA). There is only one endothermic peak indicating decomposition point. Higher optical transparency for dye doped KAP crystal was identified from the UV-vis spectrum. Etching studies showed an improvement in the optical quality of the KAP crystal after doping with amaranth dye. The positive photoconductive nature is observed from both pure and amaranth doped KAP.

A Comparative Study on the Photophysics and Photochemistry of Xanthene Dyes in the Presence of Polyamidoamine (PAMAM) Dendrimers.

PubMed

Arbeloa, Ernesto Maximiliano; Previtali, Carlos Mario; Bertolotti, Sonia Graciela

2018-04-17

The photophysical and photochemical properties of the xanthene dyes Eosin Y, Erythrosin B, and Rose Bengal are evaluated in the presence of amino-terminated polyamidoamine (PAMAM) dendrimers of relatively high generation (G3-G5) in alkaline aqueous solution. UV/Vis absorption and fluorescence spectra of the dyes show bathochromic shifts, which correlate with the size of the dendrimer. Binding constants (K bind ) are calculated from absorption data. The resulting high K bind values indicate strong interactions between both molecules. Triplet-triplet absorption spectra of the dyes are recorded by laser flash photolysis, and a decrease in the triplet lifetimes is observed in the presence of dendrimers. At the same time, an increase in the absorption of the semireduced form of the dyes is observed. Rate constants for triplet quenching ( 3 k q ) and radical quantum yields (Φ R ) are obtained. The results are explained by a very efficient electron-transfer process from PAMAM to xanthene dyes for all of the dye/dendrimer couples that are evaluated. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bibliography of Soviet Laser Developments, Number 40, March - April 1979.

DTIC Science & Technology

1979-11-27

6. Semiconductor: Heterojunction 7. Semiconductor: Theory ......................... 3 8. Glass : Nd ..................................... 4...9. Glass : Miscellaneous...........................4 B. Liquid Lasers 1. Organic Dyes a. Rhodamine .................................. 5 b...1979, 603-604. 8. Glass : Nd 22. Gvatua, Sh.Sh., E.V. Katselashvili, V.A. Khanevichev, D.K. Khotelashvili, and V.S. Chagulov (39). Substructure of high

Surface-enhanced Raman spectroscopy on laser-engineered ruthenium dye-functionalized nanoporous gold

NASA Astrophysics Data System (ADS)

Schade, Lina; Franzka, Steffen; Biener, Monika; Biener, Jürgen; Hartmann, Nils

2016-06-01

Photothermal processing of nanoporous gold with a microfocused continuous-wave laser at λ = 532 nm provides a facile means in order engineer the pore and ligament size of nanoporous gold. In this report we take advantage of this approach in order to investigate the size-dependence of enhancement effects in surface-enhanced Raman spectroscopy (SERS). Surface structures with laterally varying pore sizes from 25 nm to ≥200 nm are characterized using scanning electron microscopy and then functionalized with N719, a commercial ruthenium complex, which is widely used in dye-sensitized solar cells. Raman spectroscopy reveals the characteristic spectral features of N719. Peak intensities strongly depend on the pore size. Highest intensities are observed on the native support, i.e. on nanoporous gold with pore sizes around 25 nm. These results demonstrate the particular perspectives of laser-fabricated nanoporous gold structures in fundamental SERS studies. In particular, it is emphasized that laser-engineered porous gold substrates represent a very well defined platform in order to study size-dependent effects with high reproducibility and precision and resolve conflicting results in previous studies.

Emission lifetimes of a fluorescent dye under shock compression

DOE PAGES

Liu, Wei-long; Bassett, Will P.; Christensen, James M.; ...

2015-10-15

The emission lifetimes of rhodamine 6G (R6G), were measured under shock compression to 9.1 GPa, with the dual intent of better understanding molecular photophysics in extreme environments and assessing the usefulness of fluorescence lifetime microscopy to measure spatially-dependent pressure distributions in shocked microstructured media. R6G was studied as free dye dissolved in poly-methyl methacrylate (PMMA), or dye encapsulated in silica microparticles suspended in PMMA. Thin layers of these materials in impedance-matched geometries were subjected to planar single-stage shocks created by laser-driven flyer plates. A synchronized femtosecond laser excited the dye at selected times relative to flyer plate arrival and themore » emission lifetimes were measured with a streak camera. Lifetimes decreased when shocks arrived. The lifetime decrease was attributed to a shock-induced enhancement of R6G nonradiative relaxation. At least part of the relaxation involved shock-enhanced intersystem crossing. For free dye in PMMA, the lifetime decrease during the shock was shown to be a linear function of shock pressure from 0-9 GPa, with a slope of -0.22 ns·GPa -1. Furthermore, the linear relationship makes it simple to convert lifetimes into pressures. Lifetime measurements in shocked microenvironments may be better than emission intensity measurements, since lifetimes are sensitive to the surrounding environment, but insensitive to intensity variations associated with the motion and optical properties of a dynamically changing structure.« less

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

Yen, Chih-Ping; Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan; Yu, Pin-Feng

The deposition of various distinct organic dyes, including ruthenium complex N3, melanin nanoparticle (MNP), and porphyrin-based donor-π-acceptor dye YD2-o-C8, by using matrix-assisted pulsed laser evaporation (MAPLE) for application to dye-sensitized solar cell (DSSC) is investigated systematically. It is found that the two covalently-bonded organic molecules, i.e., MNP and YD2-o-C8, can be transferred from the frozen target to the substrate with maintained molecular integrity. In contrast, N3 disintegrates in the process, presumably due to the lower bonding strength of metal complex compared to covalent bond. With the method, DSSC using YD2-o-C8 is fabricated, and an energy conversion efficiency of 1.47% ismore » attained. The issue of the low penetration depth of dyes deposited by MAPLE and the possible resolution to it are studied. This work demonstrates that MAPLE could be an alternative way for deposition of organic dyes for DSSC.« less

Feasibility of surveying pesticide coverage with airborne fluorometer

NASA Technical Reports Server (NTRS)

Stoertz, G. E.; Hemphill, W. R.

1970-01-01

Response of a Fraunhofer line discriminator (FLD) to varying distributions of granulated corncobs stained with varying concentrations of Rhodamine WT dye was tested on the ground and from an H-19 helicopter. The granules are used as a vehicle for airborne emplacement of poison to control fire ants in the eastern and southeastern United States. Test results showed that the granules are detectable by FLD but that the concentration must be too great to be practical with the present apparatus. Possible methods for enhancement of response may include: (1) increasing dye concentration; (2) incorporating with the poisoned granules a second material to carry the dye alone; (3) use of a more strongly fluorescent substance (at 5890 A); (4) modifying the time interval after dyeing, or modifying the method of dyeing; (5) modifying the FLD for greater efficiency, increased field of view or larger optics; or (6) experimenting with laser-stimulated fluorescence.

Compact fixed wavelength femtosecond oscillators as an add-on for tunable Ti:sapphire lasers extend the range of applications towards multimodal imaging and optogenetics

NASA Astrophysics Data System (ADS)

Hakulinen, T.; Klein, J.

2016-03-01

Two-photon (2P) microscopy based on tunable Ti:sapphire lasers has become a widespread tool for 3D imaging with sub-cellular resolution in living tissues. In recent years multi-photon microscopy with simpler fixed-wavelength femtosecond oscillators using Yb-doped tungstenates as gain material has raised increasing interest in life-sciences, because these lasers offer one order of magnitude more average power than Ti:sapphire lasers in the wavelength range around 1040 nm: Two-photon (2P) excitation of mainly red or yellow fluorescent dyes and proteins (e.g. YFP, mFruit series) simultaneously has been proven with a single IR laser wavelength. A new approach is to extend the usability of existing tunable Titanium sapphire lasers by adding a fixed IR wavelength with an Yb femtosecond oscillator. By that means a multitude of applications for multimodal imaging and optogenetics can be supported. Furthermore fs Yb-lasers are available with a repetition rate of typically 10 MHz and an average power of typically 5 W resulting in pulse energy of typically 500 nJ, which is comparably high for fs-oscillators. This makes them an ideal tool for two-photon spinning disk laser scanning microscopy and holographic patterning for simultaneous photoactivation of large cell populations. With this work we demonstrate that economical, small-footprint Yb fixed-wavelength lasers can present an interesting add-on to tunable lasers that are commonly used in multiphoton microscopy. The Yb fs-lasers hereby offer higher power for imaging of red fluorescent dyes and proteins, are ideally enhancing existing Ti:sapphire lasers with more power in the IR, and are supporting pulse energy and power hungry applications such as spinning disk microscopy and holographic patterning.

Confocal Microscopy Imaging with an Optical Transition Edge Sensor

NASA Astrophysics Data System (ADS)

Fukuda, D.; Niwa, K.; Hattori, K.; Inoue, S.; Kobayashi, R.; Numata, T.

2018-05-01

Fluorescence color imaging at an extremely low excitation intensity was performed using an optical transition edge sensor (TES) embedded in a confocal microscope for the first time. Optical TES has the ability to resolve incident single photon energy; therefore, the wavelength of each photon can be measured without spectroscopic elements such as diffraction gratings. As target objects, animal cells labeled with two fluorescent dyes were irradiated with an excitation laser at an intensity below 1 μW. In our confocal system, an optical fiber-coupled TES device is used to detect photons instead of the pinhole and photomultiplier tube used in typical confocal microscopes. Photons emitted from the dyes were collected by the objective lens, and sent to the optical TES via the fiber. The TES measures the wavelength of each photon arriving in an exposure time of 70 ms, and a fluorescent photon spectrum is constructed. This measurement is repeated by scanning the target sample, and finally a two-dimensional RGB-color image is obtained. The obtained image showed that the photons emitted from the dyes of mitochondria and cytoskeletons were clearly resolved at a detection intensity level of tens of photons. TES exhibits ideal performance as a photon detector with a low dark count rate (< 1 Hz) and wavelength resolving power. In the single-mode fiber-coupled system, the confocal microscope can be operated in the super-resolution mode. These features are very promising to realize high-sensitivity and high-resolution photon spectral imaging, and would help avoid cell damage and photobleaching of fluorescence dyes.

Clinical approved fluorescent dyes coupled to endomicroscopy for in vivo diagnostic of peritoneal carcinomatosis

NASA Astrophysics Data System (ADS)

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

2015-03-01

Peritoneal carcinomatosis is metastatic stage aggravating digestive, gynecological or bladder cancer dissemination and the preoperative evaluation of lesions remains difficult. There is therefore a need for minimal invasive innovative techniques to establish a precise preoperative assessment of cancer peritoneal cavity. Probe-based confocal laser endomicroscopy (pCLE) provides dynamic images of the microarchitecture of tissues during an endoscopy. The PERSEE project proposes new developments in robotics and pCLE for the exploration of the peritoneal cavity during laparoscopy. Two fluorescent dyes, Patent blue V and Indocyanine green have been evaluated on human ex vivo samples to improve the contrast of pCLE images. For a future implementation in clinical study, two topically staining protocols operable in vivo have been validated on 70 specimens from 25 patients with a peritoneal carcinomatosis. The specimens were then imaged by pCLE with an optical probe designed for the application. A histo-morphological correlative study was performed on 350 pCLE images and 70 standard histological preparations. All images were interpreted in a random way by two pathologists. Differential histological diagnostics such as normal peritoneum or pseudomyxoma could be recognized on fluorescence images. The statistical analysis of the correlative study is underway. These dyes already approved for human use are interesting for pCLE imaging because some micromorphological criteria look like to conventional histology and are readable by pathologist. Thus pCLE images using both dyes do not require a specific semiology unlike to what is described in the literature, for pCLE associated with fluorescein for the in vivo imaging of pancreatic cysts.

Can H-aggregates serve as light-harvesting antennae? Triplet-triplet energy transfer between excited aggregates and monomer thionine in aerosol-OT solutions

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

Das, S.; Kamat, P.V.

1999-01-07

The cationic dye thionine undergoes slow dissolution in aerosol-OT (AOT) containing solutions of heptane and toluene. By controlling the ratio of [dye]/[AOT], it is possible to obtain varying amounts of monomer, dimer, and higher order aggregates (trimer) in dilute dye solutions. The thionine aggregates exhibit characteristic absorption maxima at 565 and 530 nm for the dimer and trimer forms, respectively. The singlet excited states of these dye aggregates are short-lived ({tau} = 40--63 ps) as they undergo efficient intersystem crossing to generate the triplet excited states. Triplet energy transfer from the excited dye aggregates to monomeric thionine molecules was observedmore » upon excitation with a 532 nm laser pulse. Pulse radiolysis experiments, in which the excited triplet states were generated indirectly, also confirm the finding that the triplet energy cascades down from excited trimer to dimer to monomeric dye. These studies demonstrate the possibility of using H-type dye aggregates as antenna molecules to harvest light energy whereby the aggregate molecules absorb light in different spectral regions and subsequently transfer energy to the monomeric dye.« less

Theoretical and experimental analysis of injection seeding a Q-switched alexandrite laser

NASA Technical Reports Server (NTRS)

Prasad, C. R.; Lee, H. S.; Glesne, T. R.; Monosmith, B.; Schwemmer, G. K.

1991-01-01

Injection seeding is a method for achieving linewidths of less than 500 MHz in the output of broadband, tunable, solid state lasers. Dye lasers, CW and pulsed diode lasers, and other solid state lasers have been used as injection seeders. By optimizing the fundamental laser parameters of pump energy, Q-switched pulse build-up time, injection seed power and mode matching, one can achieve significant improvements in the spectral purity of the Q-switched output. These parameters are incorporated into a simple model for analyzing spectral purity and pulse build-up processes in a Q-switched, injection-seeded laser. Experiments to optimize the relevant parameters of an alexandrite laser show good agreement.

Synthesis, spectroscopic and TD-DFT quantum mechanical study of azo-azomethine dyes. A laser induced trans-cis-trans photoisomerization cycle

NASA Astrophysics Data System (ADS)

Georgiev, Anton; Kostadinov, Anton; Ivanov, Deyan; Dimov, Deyan; Stoyanov, Simeon; Nedelchev, Lian; Nazarova, Dimana; Yancheva, Denitsa

2018-03-01

This paper describes the synthesis, spectroscopic characterization and quantum mechanical calculations of three azo-azomethine dyes. The dyes were synthesized via condensation reaction between 4-(dimethylamino)benzaldehyde and three different 4-aminobenzene azo dyes. Quantum chemical calculations on the optimized molecular geometry and electron densities of the trans (E) and cis (Z) isomers and their vibrational frequencies have been computed by using DFT/B3LYP density-functional theory with 6-311 ++G(d,p) basis set in vacuo. The thermodynamic parameters such as total electronic energy E (RB3LYP), enthalpy H298 (sum of electronic and thermal enthalpies), free Gibbs energy G298 (sum of electronic and thermal free Gibbs energies) and dipole moment μ were computed for trans (E) and cis (Z) isomers in order to estimate the ΔEtrans → cis, Δμtrans → cis,ΔHtrans → cis, ΔGtrans → cis and ΔStrans → cis values. After molecular geometry optimization the electronic spectra have been obtained by TD-DFT calculations at same basis set and correlated with the spectra of vapour deposited nanosized films of the dyes. The NBO analysis was performed in order to understand the intramolecular charge transfer and energy of resonance stabilization. Solvatochromism was investigated by UV-VIS spectroscopy in five different organic solvents with increasing polarity. The dynamic photoisomerization experiments have been performed in DMF by pump lasers λ = 355 nm (mostly E → Z) and λ = 491 nm (mostly Z → E) in spectral region 300 nm - 800 nm at equal concentrations and times of illumination in order to investigate the photodynamical trans-cis-trans properties of the sbnd CHdbnd Nsbnd and sbnd Ndbnd Nsbnd chromophore groups of the dyes.

Near-infrared dyes and upconverting phosphors as biomolecule labels and probes

NASA Astrophysics Data System (ADS)

Patonay, Gabor; Strekowski, Lucjan; Nguyen, Diem-Ngoc; Seok, Kim Jun

2007-02-01

Near-Infrared (NIR) absorbing chromophores have been used in analytical and bioanalytical chemistry extensively, including for determination of properties of biomolecules, DNA sequencing, immunoassays, capillary electrophoresis (CE) separations, etc. The major analytical advantages of these dyes are low background interference and high molar absorptivities. NIR dyes have additional advantages due to their sensitivity to microenvironmental changes. Spectral changes induced by the microenvironment are not desirable if the labels are used as a simple reporting group, e.g., during a biorecognition reaction. For these applications upconverting phosphors seem to be a better choice. There are several difficulties in utilizing upconverting phosphors as reporting labels. These are: large physical size, no reactive groups and insolubility in aqueous systems. This presentation will discuss how these difficulties can be overcome for bioanalytical and forensic applications. During these studies we also have investigated how to reduce physical size of the phosphor by simple grinding without losing activity and how to attach reactive moiety to the phosphor to covalently bind to the biomolecule of interest. It has to be emphasized that the described approach is not suitable for medical applications and the results of this research are not applicable in medical applications. For bioanalytical and forensic applications upconverting phosphors used as reporting labels have several advantages. They are excited with lasers that are red shifted respective to phosphorescence, resulting in no light scatter issues during detection. Also some phosphors are excited using eye safe lasers. In addition energy transfer to NIR dyes is possible, allowing detection schemes using donor-acceptor pairs. Data is presented to illustrate the feasibility of this phenomenon. If microenvironmental sensitivity is required, then specially designed NIR dyes can be used as acceptor labels. Several novel dyes have been synthesized in our laboratories for that purpose.

Resonance Energy Transfer Studies from Derivatives of Thiophene Substituted 1,3,4-Oxadiazoles to Coumarin-334 Dye in Liquid and Dye-Doped Polymer Media

NASA Astrophysics Data System (ADS)

Naik, Lohit; Deshapande, Narahari; Khazi, Imtiyaz Ahamed M.; Malimath, G. H.

2018-02-01

In the present work, we have carried out energy transfer studies using newly synthesised derivatives of thiophene substituted 1,3,4-oxadiazoles namely, 2-(-4-(thiophene-3-yl)phenyl)-5-(5-(thiophene-3-yl)thiophene-2-yl)-1,3,4-oxadiazole [TTO], 2-(-4-(benzo[b]thiophene-2-yl)phenyl)-5-(5-(benzo[b]thiophene-2-yl)-1,3,4-oxadiozole [TBO] and 2-(4-(4-(trifluoromethyl)phenyl)phenyl)-5-(5-(4-(trifluoromethyl)phenyl)thiophen-2-yl)-1,3,4-oxadiazole [TMO] as donors and laser dye coumarin-334 as acceptor in ethanol and dye-doped polymer (poly(methyl methacrylate) (PMMA)) media following steady-state and time-resolved fluorescence methods. Bimolecular quenching constant ( k q), translation diffusion rate parameter ( k d), diffusion length ( D l), critical transfer distance ( R 0), donor- acceptor distance ( r) and energy transfer efficiency ( E T) are calculated. It is observed that, critical transfer distance is more than the diffusion length for all the pairs. Further, bimolecular quenching constant is also more than the translation diffusion rate parameter. Hence, our experimental findings suggest that overall energy transfer is due to Förster resonance energy transfer (FRET) between donor and acceptor in both the media and for all the pairs. In addition, considerable increase in fluorescence intensity and energy transfer efficiency is observed in dye-doped polymer matrix systems as compared to liquid media. This suggests that, these donor-acceptor pairs doped in PMMA matrix may be used for applications such as energy transfer dye lasers (ETDL) to improve the efficiency and photostability, to enhance tunability and for plastic scintillation detectors.

Ablation of intervertebral discs in dogs using a MicroJet-assisted dye-enhanced injection device coupled with the diode laser

NASA Astrophysics Data System (ADS)

Bartels, Kenneth E.; Henry, George A.; Dickey, D. Thomas; Stair, Ernest L.; Powell, Ronald; Schafer, Steven A.; Nordquist, Robert E.; Frederickson, Christopher J.; Hayes, Donald J.; Wallace, David B.

1998-07-01

Use of holmium laser energy for vaporization/coagulation of the nucleus pulposus in canine intervertebral discs has been previously reported and is currently being applied clinically in veterinary medicine. The procedure was originally developed in the canine model and intended for potential human use. Since the pulsed (15 Hz) holmium laser energy exerts photomechanical and photothermal effects, the potential for extrusion of additional disc material to the detriment of the patient is possible using the procedure developed for the dog. To reduce this potential complication, use of diode laser (805 nm - CW mode) energy, coupled with indocyanine green (ICG) as a selective laser energy absorber, was formulated as a possible alternative. Delivery of the ICG and diode laser energy was through a MicroJet device that could dispense dye interactively between individual laser 'shots.' Results have shown that it is possible to selectively ablate nucleus pulposus in the canine model using the device described. Acute observations (gross and histopathologic) illustrate that accurate placement of the spinal needle before introduction of the MicroJet device is critically dependent on the expertise of the interventional radiologist. In addition, the success of the overall technique depends on consistent delivery of both ICG and diode laser energy. Minimizing tissue carbonization on the tip of the MicroJet device is also of crucial importance for effective application of the technique in clinical veterinary medicine.

Acoustic fingerprints of dye-labeled protein submicrosphere photoacoustic contrast agents

NASA Astrophysics Data System (ADS)

McDonald, Michael A.; Jankovic, Ladislav; Shahzad, Khalid; Burcher, Michael; Li, King C. P.

2009-05-01

Dye-labeled protein microspheres, submicron in size and capable of producing thermoelastically generated ultrasound in response to laser stimulation, are presented as contrast agents for photoacoustic imaging. Incident laser energy absorbed by fluorescein isothiocyanate (FITC)-labeled elastin submicrospheres results in thermoelastically generated sound production. Plotted A-line graphs reveal a distinctive morphology and a greater than two orders of magnitude increase in signal amplitude subsequent to converting FITC elastin into submicrospheres (despite a four orders of magnitude decrease in concentration). Evidence of nonlinearity and enhancement of ultrasound backscatter indicate a potential use in contrast-enhanced harmonic imaging. Photoacoustic and ultrasound imaging of FITC-elastin submicrospheres in a water-filled phantom vessel shows enhanced contrast at low concentration and clear delineation of the phantom vessel wall.

Laser separation of lithium isotopes by double resonance enhanced multiphoton ionization of Li/sub 2/

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

Balz, J.G.; Bernheim, R.A.; Gold, L.P.

1987-01-01

Multiphoton ionization spectra of /sup 7/Li/sub 2/, /sup 6/Li/sub 2/, and /sup 7/Li/sup 6/Li vapors have been measured in the 570--650 nm region using a single, low resolution, multimode cw dye laser. A number of wavelengths provide selective multiphoton ionization of one isotopic species demonstrating the possibility of efficient laser-driven isotopic separation in lithium in this wavelength region.

Mobile lidar system for environmental monitoring

NASA Astrophysics Data System (ADS)

Zhao, Guangyu; Lian, Ming; Li, Yiyun; Duan, Zheng; Zhu, Shiming; Svanberg, Sune

2018-04-01

A versatile mobile remote sensing system for multidisciplinary environmental monitoring tasks on the Chinese scene is described. The system includes a 20 Hz Nd:YAG laser-pumped dye laser, optical transmitting/receiving systems with a 30 cm and a 40 cm Newtonian telescope, and electronics, all integrated in a laboratory, installed on a Jiefang truck. Results from field experiments on atomic mercury DIAL mapping and remote laser-induced fluorescence and break-down spectroscopy are given.

Enzyme-mediated bacterial biodegradation of an azo dye (C.I. Acid blue 113): reuse of treated dye wastewater in post-tanning operations.

PubMed

Senthilvelan, T; Kanagaraj, J; Panda, R C

2014-11-01

"Dyeing" is a common practice used to color the hides during the post-tanning operations in leather processing generating plenty of wastewater. The waste stream containing dye as pollutant is severely harmful to living beings. An azo dye (C.I. Acid Blue 113) has been biodegraded effectively by bacterial culture mediated with azoreductase enzyme to reduce the pollution load in the present investigation. The maximum rate of dye degradation was found to be 96 ± 4 and 92 ± 4 % for the initial concentrations of 100 and 200 mg/l, respectively. The enzyme activity was measured using NADH as a substrate. Fourier transform infrared spectroscopy (FT-IR) analysis was confirmed that the transformation of azo linkage could be transformed into N2 or NH3 or incorporated into complete biomass. Breaking down of dye molecules to various metabolites (such as aniline, naphthalene-1,4-diamine, 3-aminobenzenesulfonic acid, naphthalene-1-sulfonic acid, 8-aminonaphthalene-1-sulfonic acid, 5,8-diaminonaphthalene-1-sulfonic acid) was confirmed by gas chromatography and mass spectra (GC-MS) and mass (electrospray ionization (ESI)) spectra analysis. The treated wastewater could be reused for dyeing operation in the leather processing, and the properties of produced leather were evaluated by conventional methods that revealed to have improved dye penetration into the grain layer of experimental leather sample and resulted in high levelness of dyeing, which helps to obtain the desired smoothness and soft leather properties.

Effects of early combinatorial treatment of autologous split-thickness skin grafts in red duroc pig model using pulsed dye laser and fractional CO2 laser.

PubMed

Bailey, J Kevin; Blackstone, Britani N; DeBruler, Danielle M; Kim, Jayne Y; Baumann, Molly E; McFarland, Kevin L; Imeokparia, Folasade O; Supp, Dorothy M; Powell, Heather M

2018-01-01

The use of pulsed dye laser (PDL) and fractional CO 2 (FX CO 2 ) laser therapy to treat and/or prevent scarring following burn injury is becoming more widespread with a number of studies reporting reduction in scar erythema and pruritus following treatment with lasers. While the majority of studies report positive outcomes following PDL or FX CO 2 therapy, a number of studies have reported no benefit or worsening of the scar following treatment. The objective of this study was to directly compare the efficacy of PDL, FX CO 2 , and PDL + FX CO 2 laser therapy in reducing scarring post burn injury and autografting in a standardized animal model. Eight female red Duroc pigs (FRDP) received 4 standardized, 1 in. x 1 in. third degree burns that were excised and autografted. Wound sites were treated with PDL, FX CO 2 , or both at 4, 8, and 12 weeks post grafting. Grafts receiving no laser therapy served as controls. Scar appearance, morphology, size, and erythema were assessed and punch biopsies collected at weeks 4, 8, 12, and 16. At week 16, additional tissue was collected for biomechanical analyses and markers for inflammatory cytokines, extracellular matrix (ECM) proteins, re-epithelialization, pigmentation, and angiogenesis were quantified at all time points using qRT-PCR. Treatment with PDL, FX CO 2 , or PDL + FX CO 2 resulted in significantly less contraction versus skin graft only controls with no statistically significant difference among laser therapy groups. Scars treated with both PDL and FX CO 2 were visually more erythematous than other groups with a significant increase in redness between two and three standard deviations above normal skin redness. Scars treated with FX CO 2 were visually smoother and contained significantly fewer wrinkles. In addition, hyperpigmentation was significantly reduced in scars treated with FX CO 2 . The use of fractional carbon dioxide or pulsed dye laser therapy within 1 month of autografting significantly reduced scar contraction versus control, though no statistically significant difference was detected between laser modalities or use of both modalities. Overall, FX CO 2 therapy appears to be modestly more effective at reducing erythema, and improving scar texture and biomechanics. The current data adds to prior studies supporting the role of laser therapy in the treatment of burn scars and indicates more study is needed to optimize delivery protocols for maximum efficacy. Lasers Surg. Med. 50:78-87, 2018. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Laser tissue soldering for hypospadias repair: results of a controlled prospective clinical trial.

PubMed

Kirsch, A J; Cooper, C S; Gatti, J; Scherz, H C; Canning, D A; Zderic, S A; Snyder, H M

2001-02-01

Laser tissue soldering has been shown to provide safe and effective tissue closure by creating an immediate leak-free anastomosis with minimal scar formation. We compared the results of laser tissue soldering and conventional suturing for hypospadias repair. A consecutive group of 138 boys 4 months to 8 years old (mean age 15 months) was divided into a standard suturing (84) and a sutureless laser (54) hypospadias repair group. Urethral repair was defined as simple (Thiersch-Duplay or Snodgrass) and complex (onlay island flap or tube) in 101 and 37 cases, respectively. Laser tissue soldering was performed with 50% human albumin solder doped with 2.5 mg./ml. indocyanine green dye using an 808 nm. diode laser at 0.5 W. In the laser group sutures were used for tissue alignment only. At surgery neourethral and penile length, operative time for neourethral construction and the number of sutures or throws were measured. Postoperatively patients were examined for complications of wound healing, stricture or fistula. Mean patient age, urethral defect severity, type of repair, neourethral length and stenting time plus or minus standard error of mean were not significantly different in the 2 groups. Mean operative time was a fifth as long for laser tissue soldering in simple and complex hypospadias repair compared to controls (1.5 +/- 0.1 and 5.1 +/- 0.3 versus 8.5 +/- 0.8 and 26.7 +/- 1.7 minutes, respectively, p <0.001). The mean number of sutures used for tissue alignment in the laser group for simple and complex repair was significantly less than in controls (3.0 +/- 0.2 and 8.2 +/- 0.6 versus 8.5 +/- 0.8 and 23.2 +/- 1.5, respectively, p <0.001). All patients were followed a mean of 12 months (minimum 6, maximum 22). The complication rate was 4.7% in the laser group and 10.7% in controls with fistula in 2 of 54 cases, and fistula and meatal stenosis in 7 and 2 of 84, respectively. These preliminary results indicate that laser tissue soldering for hypospadias repair may be performed in almost sutureless fashion and more rapidly than conventional suturing. The ease of the laser technique and the lower complication rate in the laser group indicate that laser tissue soldering is an acceptable means of tissue closure in hypospadias repair.

FY 1980 Report on Dye Laser Materials

DTIC Science & Technology

1981-02-01

C02H H Rh 19 H C2H 5 CH3 CO9H H i Rh6G H C2H 5 CH3 Co2 C2H5 H RhB C2H5 C2H!5 H CO,H H Rh3B C2A5 C2H5 H CO2CH 5 H Rh 101 RING- RING RING...Dye designations Ring SRh 101 Rh 101 - Diethyl SRh B Rh B Rhb 3B Mono ethyl (methyl) -- Rh 19 (116) Rh 6G Unsubstituted -- Rh 110 Rh 123 Nominal Single...Broadband Lasing Wave-lengths of the Rhodamine Dyes. Lasing Wavelength, n Approximate Dye Conc. x 104 Range Midpoint Rh 110 1.0 567-577 572 2.0 Rh 123

Highly efficient volume hologram multiplexing in thick dye-doped jelly-like gelatin.

PubMed

Katarkevich, Vasili M; Rubinov, Anatoli N; Efendiev, Terlan Sh

2014-08-01

Dye-doped jelly-like gelatin is a thick-layer self-developing photosensitive medium that allows single and multiplexed volume phase holograms to be successfully recorded using pulsed laser radiation. In this Letter, we present a method for multiplexed recording of volume holograms in a dye-doped jelly-like gelatin, which provides significant increase in their diffraction efficiency. The method is based on the recovery of the photobleached dye molecule concentration in the hologram recording zone of gel, thanks to molecule diffusion from other unexposed gel areas. As an example, an optical recording of a multiplexed hologram consisting of three superimposed Bragg gratings with mean values of the diffraction efficiency and angular selectivity of ∼75% and ∼21^', respectively, is demonstrated by using the proposed method.

Low-frequency wide-field fluorescence lifetime imaging using a high-power near-infrared light-emitting diode light source

PubMed Central

Gioux, Sylvain; Lomnes, Stephen J.; Choi, Hak Soo; Frangioni, John V.

2010-01-01

Fluorescence lifetime imaging (FLi) could potentially improve exogenous near-infrared (NIR) fluorescence imaging, because it offers the capability of discriminating a signal of interest from background, provides real-time monitoring of a chemical environment, and permits the use of several different fluorescent dyes having the same emission wavelength. We present a high-power, LED-based, NIR light source for the clinical translation of wide-field (larger than 5 cm in diameter) FLi at frequencies up to 35 MHz. Lifetime imaging of indocyanine green (ICG), IRDye 800-CW, and 3,3′-diethylthiatricarbocyanine iodide (DTTCI) was performed over a large field of view (10 cm by 7.5 cm) using the LED light source. For comparison, a laser diode light source was employed as a gold standard. Experiments were performed both on the bench by diluting the fluorescent dyes in various chemical environments in Eppendorf tubes, and in vivo by injecting the fluorescent dyes mixed in Matrigel subcutaneously into CD-1 mice. Last, measured fluorescence lifetimes obtained using the LED and the laser diode sources were compared with those obtained using a state-of-the-art time-domain imaging system and with those previously described in the literature. On average, lifetime values obtained using the LED and the laser diode light sources were consistent, exhibiting a mean difference of 3% from the expected values and a coefficient of variation of 12%. Taken together, our study offers an alternative to laser diodes for clinical translation of FLi and explores the use of relatively low frequency modulation for in vivo imaging. PMID:20459250

Stimulated emission from aluminium anode oxide films doped with rhodamine 6G

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

Ibrayev, N Kh; Zeinidenov, A K; Aimukhanov, A K

The spectral and luminescent properties of the rhodamine 6G dye in a porous matrix of aluminium anode oxide are studied. The films with a highly-ordered porous structure are produced using the method of two-stage anodic oxidation. By means of raster electron microscopy it is found that the diameter of the pores amounts to nearly 50 nm and the separation between the adjacent channels is almost 105 nm. The thickness of the films is equal to 55 μm, and the specific surface area measured using the method of nitrogen capillary condensation is 15.3 m{sup 2} g{sup -1}. Fluorescence and absorption spectramore » of rhodamine 6G molecules injected into the pores of the aluminium anode oxide are measured. It is found that under the excitation of samples with the surface dye concentration 0.3 × 10{sup 14} molecules m{sup -2} by the second harmonic of the Nd : YAG laser in the longitudinal scheme with the pumping intensity 0.4 MW cm{sup -2}, a narrow band of stimulated emission with the intensity maximum at the wavelength 572 nm appears against the background of the laser-induced fluorescence spectrum. A further increase in the pumping radiation intensity leads to the narrowing of the stimulated emission band and an increase in its intensity. The obtained results demonstrate the potential possibility of using the porous films of aluminium anode oxide, doped with laser dyes, in developing active elements for quantum electronics. (laser applications and other topics in quantum electronics)« less

Gonioscopic ab interno laser sclerostomy. A pilot study in glaucoma patients.

PubMed

Latina, M A; Melamed, S; March, W F; Kass, M A; Kolker, A E

1992-11-01

The purpose of this study is to evaluate the safety and efficacy of gonioscopic ab interno laser sclerostomy (GLS) in patients with glaucoma. The technique of GLS involves iontophoresis of methylene blue dye (1%) at the limbus to focally dye the sclera and to provide subsequent delivery of 10-microsecond pulsed laser energy to the dyed area through a goniolens. The laser emits at 660 nm, a wavelength that is maximally absorbed by the methylene blue dye. Patients were evaluated for fistula formation, intraocular pressure (IOP) reduction, and adverse sequelae. Thirty-eight treatments were performed in 35 eyes. Successful complete sclerostomies were achieved in 21 eyes (55%), which was associated with an acute mean reduction in IOP of 23 mmHg. Mean preoperative IOP for all patients was 35 mmHg, and 1 hour after treatment it was reduced to 18.5 mmHg. In 4 of the 38 treatments, there was no acute IOP reduction, and these eyes were judged as failures. The mean follow-up time was 8.2 months with a maximum follow-up of 15 months. By 9 months, 50% of patients had an IOP of 22 mmHg or lower. The number of antiglaucoma medications decreased from 3.1 to 1.7 for all eyes over the 15-month follow-up period. Hyphemas (13%) were the only major complication, and these resolved spontaneously. In only one case did the IOP increase after the procedure. The results of this trial indicate that GLS is technically feasible, and preliminary results of IOP control are promising.

Solar pumped lasers: Work in progress at the University of Chicago

NASA Astrophysics Data System (ADS)

Winston, Roland

Of the variety of solar energy conversion schemes that have been explored, the conversion of solar flux to coherent laser radiation is relatively new. Solar flux at sufficiently high concentrations to overcome threshold for the really important laser materials has not been available. This technological inhibition has recently been overcome through the application of nonimaging optics through the demonstration of concentration levels of 84,000 suns at the University of Chicago in a refractive medium (sapphire) and of over 20,000 suns in air at the Solar Energy Research Institute High Flux Facility. A thermodynamic overview is presented of solar lasers including solid state lasers and dye lasers.

High-speed photography during laser-based gall bladder stone lithotripsy

NASA Astrophysics Data System (ADS)

Kokaj, Jahja O.

2001-04-01

Shadowgraphy of gall bladder stone, which is held by a basket and immersed in a civete is performed. The exposure time is determined by the time of a N-Dye laser pulse used as a lightening source for photography. The shadowgram is projected in the objective of a camera which is connected to a microscope. The light coming from the laser, illuminates the civete collecting optical information of the stone and physical phenomena appearing above the stone. On top of the stone a tip of optical fiber is fixed, which is used for transmitting Ho:Yag laser power to the stone. Using a computer and time delay the laser pulses used for destruction and illumination are synchronized. Since the N-Dye laser pulse is pico-second range and the Ho:Yag laser pulse is in the range of micro-second, many image frames are obtained within the time of one pulse applied during the destruction. It is known that in the process of stone destruction several phenomena like plume, plasma, shock wave and bubble formation take place. However, the physical mechanism of the stone destruction is not yet completely understood. From the obtained results the above phenomena are studied which gives new information and clue for understanding some of the mentioned phenomena. The laser power which is guided by an optical fiber into the gall bladder or kidney of the human body can damage the living tissue and cause some serious health problems. For this reason the fiber needs to be oriented properly during the action of the laser power.

Bibliography of Soviet Laser Developments, Number 90, July-August 1987

DTIC Science & Technology

1988-06-27

8, 1987, 1250-1255. 51. Cernai, K.; Novakov , M. 0. Concentration dependence of stimulated emission in 4-methylumbelliferone-fluorescein laser dye...118 PANCHENKO I P 129 NADENENKO A V 29 NOVAK A 9 PANCHENKO V YA 18 NADEZHDINSKIY A 1 115 NOVAKOV 14 7 PANKOV F N 88 NAGORNYKH S N 121 NOVICHENKOV V YE

Apodizer aperture for lasers

DOEpatents

Jorna, Siebe; Siebert, Larry D.; Brueckner, Keith A.

1976-11-09

An aperture attenuator for use with high power lasers which includes glass windows shaped and assembled to form an annulus chamber which is filled with a dye solution. The annulus chamber is shaped such that the section in alignment with the axis of the incident beam follows a curve which is represented by the equation y = (r - r.sub.o).sup.n.

Ion beam production and study of radioactive isotopes with the laser ion source at ISOLDE

NASA Astrophysics Data System (ADS)

Fedosseev, Valentin; Chrysalidis, Katerina; Day Goodacre, Thomas; Marsh, Bruce; Rothe, Sebastian; Seiffert, Christoph; Wendt, Klaus

2017-08-01

At ISOLDE the majority of radioactive ion beams are produced using the resonance ionization laser ion source (RILIS). This ion source is based on resonant excitation of atomic transitions by wavelength tunable laser radiation. Since its installation at the ISOLDE facility in 1994, the RILIS laser setup has been developed into a versatile remotely operated laser system comprising state-of-the-art solid state and dye lasers capable of generating multiple high quality laser beams at any wavelength in the range of 210-950 nm. A continuous programme of atomic ionization scheme development at CERN and at other laboratories has gradually increased the number of RILIS-ionized elements. At present, isotopes of 40 different elements have been selectively laser-ionized by the ISOLDE RILIS. Studies related to the optimization of the laser-atom interaction environment have yielded new laser ion source types: the laser ion source and trap and the versatile arc discharge and laser ion source. Depending on the specific experimental requirements for beam purity or versatility to switch between different ionization mechanisms, these may offer a favourable alternative to the standard hot metal cavity configuration. In addition to its main purpose of ion beam production, the RILIS is used for laser spectroscopy of radioisotopes. In an ongoing experimental campaign the isotope shifts and hyperfine structure of long isotopic chains have been measured by the extremely sensitive in-source laser spectroscopy method. The studies performed in the lead region were focused on nuclear deformation and shape coexistence effects around the closed proton shell Z = 82. The paper describes the functional principles of the RILIS, the current status of the laser system and demonstrated capabilities for the production of different ion beams including the high-resolution studies of short-lived isotopes and other applications of RILIS lasers for ISOLDE experiments. This article belongs to the Focus on Exotic Beams at ISOLDE: A Laboratory Portrait special issue.

Water tunnel flow visualization using a laser

NASA Technical Reports Server (NTRS)

Beckner, C.; Curry, R. E.

1985-01-01

Laser systems for flow visualization in water tunnels (similar to the vapor screen technique used in wind tunnels) can provide two-dimensional cross-sectional views of complex flow fields. This parametric study documents the practical application of the laser-enhanced visualization (LEV) technique to water tunnel testing. Aspects of the study include laser power levels, flow seeding (using flourescent dyes and embedded particulates), model preparation, and photographic techniques. The results of this study are discussed to provide potential users with basic information to aid in the design and setup of an LEV system.

Mie resonances to tailor random lasers

NASA Astrophysics Data System (ADS)

García, P. D.; Ibisate, M.; Sapienza, R.; Wiersma, D. S.; López, C.

2009-07-01

In this paper, we present an optical characterization of photonic glass-based random lasers. We show how the resonant behavior of diffuse light transport through such systems can tailor the lasing emission when a gain medium is added to the glass. A DNA-based organic dye is used as gain medium. The resonances in the transport mean-free path influence the lasing wavelength of the random laser. The laser wavelength is therefore controlled by the sphere diameter. Furthermore, the existence of Mie resonances reduces the necessary pump energy to reach the lasing threshold.

Singlet-Oxygen Generation From Individual Semiconducting and Metallic Nanostructures During Near-Infrared Laser Trapping

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

Smith, Bennett E.; Roder, Paden B.; Hanson, Jennifer L.

2015-03-13

Photodynamic therapy has been used for several decades in the treatment of solid tumors through the generation of reactive singlet-oxygen species (1O2). Recently, nanoscale metallic and semiconducting materials have been reported to act as photosensitizing agents with additional diagnostic and therapeutic functionality. To date there have been no reports of observing the generation of singlet-oxygen at the level of single nanostructures, particularly at near infrared (NIR) wavelengths. Here we demonstrate that NIR laser-tweezers can be used to observe the formation of singlet-oxygen produced from individual silicon and gold nanowires via use of a commercially available reporting dye. The laser trapmore » also induces 2-photon photoexcitation of the dye following a chemical reaction with singlet oxygen. Corresponding 2-photon emission spectra confirms the generation of singlet oxygen from individual silicon nanowires at room temperature (30°C), suggesting a range of applications in understanding the impact of 1O2 on individual cancer cells.« less

Multiphoton-generated localized electron plasma for membrane permeability modification in single cells

NASA Astrophysics Data System (ADS)

Merritt, T.; Leblanc, M.; McMillan, J.; Westwood, J.; Khodaparast, G. A.

2014-03-01

Successful incorporation of a specific macromolecule into a single cell would be ideal for characterizing trafficking dynamics through plasmodesmata or for studying intracellular localizations. Here, we demonstrate NIR femtosecond laser-mediated infiltration of a membrane impermeable dextran-conjugated dye into living cells of Arabidopsis thaliana seedling stems. Based on the reactions of fluorescing vacuoles of transgenic cells and artificial cell walls comprised of nanocellulose, laser intensity and exposure time were adjusted to avoid deleterious effects. Using these plant-tailored laser parameters, cells were injected with the fluorophores and long-term dye retention was observed, all while preserving vital cell functions. This method is ideal for studies concerning cell-to-cell interactions and potentially paves the way for introducing transgenes to specific cells. This work was supported by NSF award IOS-0843372 to JHW, with additional support from and U.S. Department of Agriculture Hatch Project no. 135997, and by the Institute of Critical Technology and Applied Sciences (ICTAS) at Virginia Tech.

Absorption and emission spectra of Li atoms trapped in rare gas matrices

NASA Astrophysics Data System (ADS)

Wright, J. J.; Balling, L. C.

1980-10-01

Pulsed-dye-laser excitation has been used to investigate the optical absorption and emission spectra of Li atoms trapped in Ar, Kr, and Xe matrices at 10 °K. Attempts to stabilize Li atoms in a Ne matrix at 2 °K were unsuccessful. Results for all three rare gases were qualitatively the same. White light absorption scans showed a single absorption with three peaks centered near the free-atom 2s→2p transition wavelength. The intensity of fluorescence produced by dye-laser excitation within this absorption band was measured as a function of emission wavelength. Excitation of the longest- and shortest-wavelength absorption peaks produced identical emission profiles, but no distinct fluorescence signal was detected when the laser was tuned to the central absorption peaks, indicating that the apparent absorption triplet is actually the superposition of a singlet and a doublet absorption originating from two different trapping sites. No additional absorption bands were detected.

Study of resonance light scattering for remote optical probing

NASA Technical Reports Server (NTRS)

Penney, C. M.; Morey, W. W.; St. Peters, R. L.; Silverstein, S. D.; Lapp, M.; White, D. R.

1973-01-01

Enhanced scattering and fluorescence processes in the visible and UV were investigated which will enable improved remote measurements of gas properties. The theoretical relationship between scattering and fluorescence from an isolated molecule in the approach to resonance is examined through analysis of the time dependence of re-emitted light following excitation of pulsed incident light. Quantitative estimates are developed for the relative and absolute intensities of fluorescence and resonance scattering. New results are obtained for depolarization of scattering excited by light at wavelengths within a dissociative continuum. The experimental work was performed in two separate facilities. One of these utilizes argon and krypton lasers, single moded by a tilted etalon, and a 3/4 meter double monochromator. This facility was used to determine properties of the re-emission from NO2, I2 and O3 excited by visible light. The second facility involves a narrow-line dye laser, and a 3/4 meter single monochromator. The dye laser produces pulsed light with 5 nsec pulse duration and 0.005 nm spectral width.

Measurement of Zeta-Potential at Microchannel Wall by a Nanoscale Laser Induced Fluorescence Imaging

NASA Astrophysics Data System (ADS)

Kazoe, Yutaka; Sato, Yohei

A nanoscale laser induced fluorescence imaging was proposed by using fluorescent dye and the evanescent wave with total internal reflection of a laser beam. The present study focused on the two-dimensional measurement of zeta-potential at the microchannel wall, which is an electrostatic potential at the wall surface and a dominant parameter of electroosmotic flow. The evanescent wave, which decays exponentially from the wall, was used as an excitation light of the fluorescent dye. The fluorescent intensity detected by a CCD camera is closely related to the zeta-potential. Two kinds of fluorescent dye solution at different ionic concentrations were injected into a T-shaped microchannel, and formed a mixing flow field in the junction area. The two-dimensional distribution of zeta-potential at the microchannel wall in the pressure-driven flow field was measured. The obtained zeta-potential distribution has a transverse gradient toward the mixing flow field and was changed by the difference in the averaged velocity of pressure-driven flow. To understand the ion motion in the mixing flow field, the three-dimensional flow structure was analyzed by the velocity measurement using micron-resolution particle image velocimetry and the numerical simulation. It is concluded that the two-dimensional distribution of zeta-potential at the microchannel wall was dependent on the ion motion in the flow field, which was governed by the convection and molecular diffusion.

Laser-Induced Population Inversion in Rhodamine 6G for Lysozyme Oligomer Detection.

PubMed

Hanczyc, Piotr; Sznitko, Lech

2017-06-06

Fluorescence spectroscopy is a common method for detecting amyloid fibrils in which organic fluorophores are used as markers that exhibit an increase in quantum yield upon binding. However, most of the dyes exhibit enhanced emission only when bound to mature fibrils, and significantly weaker signals are obtained in the presence of amyloid oligomers. In the concept of population inversion, a laser is used as an excitation source to keep the major fraction of molecules in the excited state to create the pathways for the occurrence of stimulated emission. In the case of the proteins, the conformational changes lead to the self-ordering and thus different light scattering conditions that can influence the optical signatures of the generated light. Using this methodology, we show it is possible to optically detect amyloid oligomers using commonly available staining dyes in which population inversion can be induced. The results indicate that rhodamine 6G molecules are complexed with oligomers, and using a laser-assisted methodology, weakly emissive states can be detected. Significant spectral red-shifting of rhodamine 6G dispersed with amyloid oligomers and a notable difference determined by comparison of spectra of the fibrils suggest the existence of specific dye aggregates around the oligomer binding sites. This approach can provide new insights into intermediate oligomer states that are believed to be responsible for toxic seeding in neurodegeneration diseases.

Characterization of a liquid crystal/dye cell for a future application in display-integrated photovoltaics

NASA Astrophysics Data System (ADS)

Fujieda, Ichiro; Itaya, Shunsuke; Ohta, Masamichi; Ozawa, Shintaro; Azmi, Nada Dianah Binti M.

2016-04-01

One can convert a luminescent solar concentrator to a display by scanning a laser beam on it. When a guest-host system of liquid crystal (LC) and dye materials are incorporated, absorption of excitation light and the radiation pattern of photoluminescence (PL) can be adjusted to changes in lighting condition. The resolution of a displayed image can be degraded by PL spreading in the LC/dye layer. Its contrast can be limited by the PL induced by ambient light. In the experiment, we fabricated a 22×25 mm2 cell that contained 0.5 wt. % coumarin 6 in a nematic LC host. The alignment was antiparallel and the gap was 6 μm. Using a blue laser beam of 0.04 mm FWHM, the PL intensity distribution was measured to be 0.20 mm FWHM at zero bias. It became slightly wider at 10 V. For contrast evaluation, we measured PL spectra under two conditions. First, the center of the cell was irradiated by a 1.7-mW blue laser beam. Second, the whole cell was uniformly exposed to light from a fluorescent lamp at illuminance of 800lx. The contrast of luminance was calculated to be 1.4×105. The optical power reaching its edge surfaces was measured and roughly agreed with the prediction by a simple model.

Assessment of Efficacy of the 595-nm Pulsed Dye Laser in the Treatment of Facial Port-Wine Stains in Indian Patients.

PubMed

Khandpur, Sujay; Sharma, Vinod K

2016-06-01

Pulsed dye lasers have revolutionized treatment of port-wine stains (PWS). The authors' previous study with a 585-nm/0.45-millisecond pulsed dye laser (PDL) showed 25% to 75% improvement in 60% of facial PWS. The authors analyzed data on facial PWS treated with a 595-nm tunable PDL in Indian patients. Response was assessed subjectively on a scale of -1 to 5 (Investigator Global Assessment) by comparing pretreatment and posttreatment photographs. Patients' perception of change in PWS was also noted on a visual analog scale from 0 to 10 (Patient Global Assessment). Side effects were recorded. A total of 74 flat and 24 hypertrophic PWS in skin Types IV and V with a median lesion size of 56 cm and 102 cm, respectively, and color ranging from pink to purple were treated. They underwent a mean of 7.3 and 8.5 sessions (range: 4-10 session), respectively. A mean lightening of 54% in flat and 40% in hypertrophic PWS was observed. After 10 treatments, 46.6% of flat PWS cases showed >75% lightening and an equal number had 25% to 75% improvement. A >75% improvement was observed in 12.5% of hypertrophic PWS with 75% of cases showing between 25% to 75% improvement. No significant side effects were noted. The 595-nm tunable PDL produced moderate response with no significant side effects.

Noncontact microsurgery of cell membranes using femtosecond laser pulses for optoinjection of specified substances into cells

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

Il'ina, I V; Ovchinnikov, A V; Chefonov, O V

IR femtosecond laser pulses were used for microsurgery of a cell membrane aimed at local and short-duration change in its permeability and injection of specified extracellular substances into the cells. The possibility of noncontact laser delivery of the propidium iodide fluorescent dye and the pEGFP plasmid, encoding the green fluorescent protein, into the cells with preservation of the cell viability was demonstrated. (extreme light fields and their applications)

Airborne water vapor DIAL system and measurements of water and aerosol profiles

NASA Technical Reports Server (NTRS)

Higdon, Noah S.; Browell, Edward V.

1991-01-01

The Lidar Applications Group at NASA Langley Research Center has developed a differential absorption lidar (DIAL) system for the remote measurement of atmospheric water vapor (H2O) and aerosols from an aircraft. The airborne H2O DIAL system is designed for extended flights to perform mesoscale investigations of H2O and aerosol distributions. This DIAL system utilizes a Nd:YAG-laser-pumped dye laser as the off-line transmitter and a narrowband, tunable Alexandrite laser as the on-line transmitter. The dye laser has an oscillator/amplifier configuration which incorporates a grating and prism in the oscillator cavity to narrow the output linewidth to approximately 15 pm. This linewidth can be maintained over the wavelength range of 725 to 730 nm, and it is sufficiently narrow to satisfy the off-line spectral requirements. In the Alexandrite laser, three intracavity tuning elements combine to produce an output linewidth of 1.1 pm. These spectral devices include a five-plate birefringent tuner, a 1-mm thick solid etalon and a 1-cm air-spaced etalon. A wavelength stability of +/- 0.35 pm is achieved by active feedback control of the two Fabry-Perot etalons using a frequency stabilized He-Ne laser as a wavelength reference. The three tuning elements can be synchronously scanned over a 150 pm range with microprocessor-based scanning electronics. Other aspects of the DIAL system are discussed.

MRF, ELSM and STED: tools to study defects in fused silica optics

NASA Astrophysics Data System (ADS)

Catrin, R.; Taroux, D.; Cormont, P.; Maunier, C.; Neauport, J.

2013-11-01

The MegaJoule laser being constructed at the CEA near Bordeaux (France) is designed to focus more than 1 MJ of energy at 351 nm, on a millimetre scale target in the centre of an experiment chamber. The final optic assembly of this system operating at a wavelength of 351 nm is made up of large fused silica optics, working in transmission, that are used to convey and focus the laser beam. Under high fluences (i.e. more than 5 J/cm2 for 3 ns pulses), the limited lifetime of final optical assembly is a major concern for fusion scale laser facilities. Previous works have shown that surface finishing processes applied to manufacture these optical components can leave subsurface cracks (SSD), pollution or similar defects that act as initiators of the laser damage. In this work, we used epi-fluorescent light scanning microscopy (ELSM) and Stimulated Emission Depletion (STED) in confocal mode with fluorescent dye tagging to get a better knowledge of size and depth of these subsurface cracks. Magnetorheological fluid finishing technique (MRF) was also used as a tool to remove these cracks and thus assess depths measured by confocal microscopy. Subsurface cracks with a width of about 120 nm are observed up to ten micrometers below the surface.

Preliminary clinical results of pulsed-dye laser therapy for recurrent respiratory papillomatosis

NASA Astrophysics Data System (ADS)

McMillan, Kathleen; Shapshay, Stanley M.; McGilligan, J. A.; Wang, Zhi; Rebeiz, Elie E.

1998-07-01

Recurrent respiratory papillomatosis (RRP) is a viral disease characterized by the growth of benign tumors on the vocal cords. Standard management of RRP currently consists of CO2 laser microsurgical ablation of the papillomas. Because of the recurrent nature of this disease, patients are often faced with significant cumulative risk of soft tissue complications such as vocal cord scarring. As a minimally traumatic alternative to management of RRP, we have investigated the use of the 585 nm pulsed dye laser (PDL) to cause regression of the papillomas by selective eradication of the tumor microvasculature. Three patients have been treated with the PDL at fluences of 6 J/cm2 (double pulses per irradiated site), 8 J/cm2 (single pulses), and 10 J/cm2 (single pulses), at noncritical areas within the larynx, using a specially designed micromanipulator. Lesions on the true cords were treated with the CO2 laser. Clinical examination showed that PDL treatment appeared to produce complete regression of papillomas. Unlike the sites of lesions treated by the CO2 laser, the epithelial surface at the PDL treatment sites was preserved intact. The presumed mechanism for papilloma regression following PDL treatment involves acute or chronic localized hypoxia caused by loss of tumor microvasculature.

Nine color eleven parameter immunophenotyping using three laser flow cytometry.

PubMed

Bigos, M; Baumgarth, N; Jager, G C; Herman, O C; Nozaki, T; Stovel, R T; Parks, D R; Herzenberg, L A

1999-05-01

This study describes a three laser flow cytometer, reagents, and software used to simultaneously evaluate nine distinct fluorescent parameters on one cell sample. We compare the quality of data obtained with (1) full software compensation and (2) the use of partial spectral compensation of selected pairs of parameters in analog hardware, in combination with final software compensation. An application characterizing low frequency murine B cell subpopulations is given. The fluorochromes used are: fluorescein (FITC), phycoerythrin (PE), Cy5PE and Cy7PE, excited at 488 nm by an argon laser; Texas Red (TR), allophycocyanin (APC), and Cy7APC excited at 595 nm by a pumped dye laser; and cascade blue (CB) and cascade yellow (CY) excited at 407 nm by a violet-enhanced krypton laser. Custom additions to commercial electronics and an extended optical bench allow the measurement of these nine parameters plus forward and side scatter light signals. We find the use of partial analog compensation reduces the variation in the background staining levels introduced by the compensation process. Novel B cell populations with frequencies below 1% are characterized. Nine color flow cytometry is capable of providing measurements with high information content. The choice of reagent-dye combinations and the ability to compensate in multi-parameter measurement space are crucial to obtaining satisfactory results.

Management of a Recurrent Pyogenic Granuloma of the Hard Palate with Diode Laser: A Case Report.

PubMed

Hasanoglu Erbasar, Güzin Neda; Senguven, Burcu; Gultekin, Sibel Elif; Cetiner, Sedat

2016-01-01

Pyogenic granuloma (PG) is a prevalent inflammatory hyperplasia of skin and oral mucosa which is often caused by constant low-grade local irritation, traumatic injury or hormonal factors. In many cases, gingival irritation and inflammation due to poor oral hygiene are precipitating factors. Oral PG occurs predominantly on the gingiva, but it is also encountered on the lips, tongue, buccal mucosa and rarely on the hard palate. Although surgical excision is the first choice of treatment, many other treatment modalities could be counted such as cryosurgery, sodium tetradecyl sulfate sclerotherapy, intralesional steroids, flash lamp pulsed dye laser, neodymium-doped yttrium aluminium garnet (Nd:YAG) laser, carbon dioxide (CO2) laser, erbium-doped yttrium aluminum garnet (Er:YAG) lasers and diode laser have been suggested. After surgical excision recurrence occurs up to 16% of these lesions. It is believed that recurrence ensues as a result of incomplete excision, failure to eliminate etiologic factors or repeated trauma. A 50-year-old female was referred to the Department of Oral Surgery, Gazi University, School of Dentistry, complaining of a swelling and growth on the right side of the hard palate for four months. Patient reported a similar growth in the same area about two years earlier, which had turned out to be a PG by histopathology. The treatment plan included surgical excision of the lesion using diode laser. The patient reported no pain after the surgery. She was discharged with a prescription of chlorhexidine mouthwash and necessary post-operative instructions. At 7 days follow up visit, immediate recurrence of the lesion was observed, and it was excised by diode laser with 2 mm margins at its clinical periphery, to a depth up to the periosteum, by the same operator. No recurrence or scarring was observed in 14 months follow-up. Although diode laser is a secure and efficient technique for the treatment of intraoral PG, in order to minimize its recurrence, the lesion should be excised with a wider margin down to the periosteum or to the causing agent. Also due to its high recurrence rate, long-term follow-up is recommended.

Laser welding versus suturing in tunica vaginalis and venous patch graft corporoplasty.

PubMed

Kirsch, A J; Chang, D T; Miller, M I; Connor, J P; Hensle, T W; Shabsigh, R

1995-08-01

Congenital penile curvature may result from corporeal disproportion in nearly 40% of cases, while in adults scarring of the corporeal bodies or periurethral fibrosis accounts for the majority of cases. Some surgeons advocate lengthening the fibrosed corporeal bodies by excising tunica albuginea and grafting such defects to straighten the penis. Tunica vaginalis, dermis, dorsal vein and lyophilized dura have been used for this purpose. Traditionally, these graft biomaterials have been sutured to the tunica albuginea. We assessed the feasibility, short-term safety and efficacy of diode laser tissue welding using albumin based solder and indocyanine green dye to perform patch graft corporoplasty in the dog. Ten animals were subjected to bilateral transverse excision of 1 x 2 cm. sections of tunica albuginea. Corporoplasty was performed using grafts composed of saphenous vein (5) or tunica vaginalis (5). Microsurgical repair with 7-zero polydioxanone suture (10) was compared to contralateral laser welded repair (10) by recording operative time, initial and short-term bursting pressures (mean plus or minus standard deviation) and histological analysis. Operative time on the laser side (9.8 +/- 2.3 minutes) was significantly shorter (p < 0.05) than on the suture side (17.1 +/- 5.1 minutes). Leak pressures, initially (laser 105.7 +/- 23.8 mm. Hg versus suture 35.3 +/- 8.0 mm. Hg), at 3 to 5 days (greater than 333.3 +/- 62.4 mm. Hg versus 136.6 +/- 39.4 mm. Hg) and at 7 to 10 days (greater than 397.8 +/- 39.8 mm. Hg versus 191.5 +/- 46.4 mm. Hg) were higher (p < 0.05) in the laser side compared to controls. Graft failure (necrosis) occurred in 3 repairs (2 laser on day 4 and 1 suture on day 10). Viable tissue with minimal differences in foreign body reaction between groups was observed in the remaining grafts. We conclude that laser welded patch graft corporoplasty using tunica vaginalis or vein is easy to perform, and provides excellent initial and short-term leak pressures. The use of laser welding in conjunction with suturing may be beneficial in corporoplasty for congenital or acquired penile curvature.

The use of fluorescent indoline dyes for side population analysis.

PubMed

Kohara, Hiroshi; Watanabe, Kohei; Shintou, Taichi; Nomoto, Tsuyoshi; Okano, Mie; Shirai, Tomoaki; Miyazaki, Takeshi; Tabata, Yasuhiko

2013-01-01

Dye efflux assay evaluated by flow cytometry is useful for stem cell studies. The side population (SP) cells, characterized by the capacity to efflux Hoechst 33342 dye, have been shown to be enriched for hematopoietic stem cells (HSCs) in bone marrow. In addition, SP cells are isolated from various tissues and cell lines, and are also potential candidates for cancer stem cells. However, ultra violet (UV) light, which is not common for every flow cytometer, is required to excite Hoechst 33342. Here we showed that a fluorescent indoline dye ZMB793 can be excited by 488-nm laser, equipped in almost all the modern flow cytometers, and ZMB793-excluding cells showed SP phenotype. HSCs were exclusively enriched in the ZMB793-excluding cells, while ZMB793 was localized in cytosol of bone marrow lineage cells. The efflux of ZMB793 dye was mediated by ATP binding cassette (ABC) transporter Abcg2. Moreover, staining properties were affected by the side-chain structure of the dyes. These data indicate that the fluorescent dye ZMB793 could be used for the SP cell analysis. Copyright © 2012 Elsevier Ltd. All rights reserved.

Vacuum decay container/closure integrity testing technology. Part 2. Comparison to dye ingress tests.

PubMed

Wolf, Heinz; Stauffer, Tony; Chen, Shu-Chen Y; Lee, Yoojin; Forster, Ronald; Ludzinski, Miron; Kamat, Madhav; Mulhall, Brian; Guazzo, Dana Morton

2009-01-01

Part 1 of this series demonstrated that a container closure integrity test performed according to ASTM F2338-09 Standard Test Method for Nondestructive Detection of Leaks in Packages by Vacuum Decay Method using a VeriPac 325/LV vacuum decay leak tester by Packaging Technologies & Inspection, LLC (PTI) is capable of detecting leaks > or = 5.0 microm (nominal diameter) in rigid, nonporous package systems, such as prefilled glass syringes. The current study compared USP, Ph.Eur. and ISO dye ingress integrity test methods to PTI's vacuum decay technology for the detection of these same 5-, 10-, and 15-microm laser-drilled hole defects in 1-mL glass prefilled syringes. The study was performed at three test sites using several inspectors and a variety of inspection conditions. No standard dye ingress method was found to reliably identify all holed syringes. Modifications to these standard dye tests' challenge conditions increased the potential for dye ingress, and adjustments to the visual inspection environment improved dye ingress detection. However, the risk of false positive test results with dye ingress tests remained. In contrast, the nondestructive vacuum decay leak test method reliably identified syringes with holes > or = 5.0 microm.

Ultrafast Pulse Generation in an Organic Nanoparticle-Array Laser.

PubMed

Daskalakis, Konstantinos S; Väkeväinen, Aaro I; Martikainen, Jani-Petri; Hakala, Tommi K; Törmä, Päivi

2018-04-11

Nanoscale coherent light sources offer potentially ultrafast modulation speeds, which could be utilized for novel sensors and optical switches. Plasmonic periodic structures combined with organic gain materials have emerged as promising candidates for such nanolasers. Their plasmonic component provides high intensity and ultrafast nanoscale-confined electric fields, while organic gain materials offer fabrication flexibility and a low acquisition cost. Despite reports on lasing in plasmonic arrays, lasing dynamics in these structures have not been experimentally studied yet. Here we demonstrate, for the first time, an organic dye nanoparticle-array laser with more than a 100 GHz modulation bandwidth. We show that the lasing modulation speed can be tuned by the array parameters. Accelerated dynamics is observed for plasmonic lasing modes at the blue side of the dye emission.

Excitation laser energy dependence of surface-enhanced fluorescence showing plasmon-induced ultrafast electronic dynamics in dye molecules

NASA Astrophysics Data System (ADS)

Itoh, Tamitake; Yamamoto, Yuko S.; Tamaru, Hiroharu; Biju, Vasudevanpillai; Murase, Norio; Ozaki, Yukihiro

2013-06-01

We find unique properties accompanying surface-enhanced fluorescence (SEF) from dye molecules adsorbed on Ag nanoparticle aggregates, which generate surface-enhanced Raman scattering. The properties are observed in excitation laser energy dependence of SEF after excluding plasmonic spectral modulation in SEF. The unique properties are large blue shifts of fluorescence spectra, deviation of ratios between anti-Stokes SEF intensity and Stokes from those of normal fluorescence, super-broadening of Stokes spectra, and returning to original fluorescence by lower energy excitation. We elucidate that these properties are induced by electromagnetic enhancement of radiative decay rates exceeding the vibrational relaxation rates within an electronic excited state, which suggests that molecular electronic dynamics in strong plasmonic fields can be largely deviated from that in free space.

Second generation photodynamic agents: a review.

PubMed

Sternberg, E D; Dolphin, D

1993-10-01

Over the last decade, laser treatment of neoplastic diseases has become routine. The ability of these light-induced therapies to effect positive results is increased with the utilization of photosensitizing dyes. The approval of Photofrin in Canada as a first generation photodynamic therapeutic agent for the treatment of some forms of bladder cancer is being followed by the development of other agents with improved properties. At this time a number of second generation photosensitizing dyes are under study in phase I/II clinical trials. A review of the status of these trials along with mechanistic aspects is reviewed in this article. In addition, a review of the status of lasers to be utilized for photodynamic therapy gives some indication of which instruments could be considered for this therapy in the future.

Measurement of the photoionization cross section from the laser-populated 3D metastable levels in barium

NASA Technical Reports Server (NTRS)

Carlsten, J. L.; Mcilrath, T. J.; Parkinson, W. H.

1974-01-01

Measurements of the absolute photoionization cross section from the 6s5d 3D metastable level of barium are presented. The 3D levels were selectively populated with a high-power tuneable dye laser. The number density was determined by observing the resulting depopulation of the ground state when pumping occurred.

Remote sensing of tropospheric gases and aerosols with airborne DIAL system

NASA Technical Reports Server (NTRS)

Browell, E. V.

1983-01-01

The multipurpose airborne DIAL system developed at NASA Langley Research Center is characterized, and the published results of tropospheric O3, H2O, and aerosol-backscatter remote-sensing experiments performed in 1980 and 1981 are summarized. The system comprises two tunable dye lasers pumped by frequency-doubled Nd:YAG lasers, dielectric-coated steering optics, a 36-cm-diameter Cassegrain receiver telescope, gateable photomultiplier tubes, and a minicomputer data-processing unit for real-time calculation of gas concentrations and backscattering profiles. The transmitted energy of the 100-microsec-separated dye-laser pulses is 40, 80, or 50 mJ/pulse at around 300, 600, or 720-nm wavelength, respectively. Good agreement was found between DIAL-remote-sensed and in-situ H2O and O3 profiles of the lower troposphere and O3 profiles of the tropopause region, and the usefulness of DIAL backscattering measurements in the study of boundary-layer and tropospheric dynamics is demonstrated. The feasibility of DIAL sensing of power-plant or urban plume SO2, of urban-area (or rural-area column-content) NO2, and of temperature and H2O (simultaneously using a third laser) has been suggested by simulation studies.

Imaging monitoring techniques applications in the transient gratings detection

NASA Astrophysics Data System (ADS)

Zhao, Qing-ming

2009-07-01

Experimental studies of Degenerate four-wave mixing (DFWM) in iodine vapor at atmospheric pressure and 0℃ and 25℃ are reported. The Laser-induced grating (LIG) studies are carried out by generating the thermal grating using a pulsed, narrow bandwidth, dye laser .A new image processing system for detecting forward DFWM spectroscopy on iodine vapor is reported. This system is composed of CCD camera, imaging processing card and the related software. With the help of the detecting system, phase matching can be easily achieved in the optical arrangement by crossing the two pumps and the probe as diagonals linking opposite corners of a rectangular box ,and providing a way to position the PhotoMultiplier Tube (PMT) . Also it is practical to know the effect of the pointing stability on the optical path by monitoring facula changing with the laser beam pointing and disturbs of the environment. Finally the effects of Photostability of dye laser on the ration of signal to noise in DFWM using forward geometries have been investigated in iodine vapor. This system makes it feasible that the potential application of FG-DFWM is used as a diagnostic tool in combustion research and environment monitoring.

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

Liu, Wei-long; Bassett, Will P.; Christensen, James M.

The emission lifetimes of rhodamine 6G (R6G), were measured under shock compression to 9.1 GPa, with the dual intent of better understanding molecular photophysics in extreme environments and assessing the usefulness of fluorescence lifetime microscopy to measure spatially-dependent pressure distributions in shocked microstructured media. R6G was studied as free dye dissolved in poly-methyl methacrylate (PMMA), or dye encapsulated in silica microparticles suspended in PMMA. Thin layers of these materials in impedance-matched geometries were subjected to planar single-stage shocks created by laser-driven flyer plates. A synchronized femtosecond laser excited the dye at selected times relative to flyer plate arrival and themore » emission lifetimes were measured with a streak camera. Lifetimes decreased when shocks arrived. The lifetime decrease was attributed to a shock-induced enhancement of R6G nonradiative relaxation. At least part of the relaxation involved shock-enhanced intersystem crossing. For free dye in PMMA, the lifetime decrease during the shock was shown to be a linear function of shock pressure from 0-9 GPa, with a slope of -0.22 ns·GPa -1. Furthermore, the linear relationship makes it simple to convert lifetimes into pressures. Lifetime measurements in shocked microenvironments may be better than emission intensity measurements, since lifetimes are sensitive to the surrounding environment, but insensitive to intensity variations associated with the motion and optical properties of a dynamically changing structure.« less

Laser-mediated perforation of plant cells

NASA Astrophysics Data System (ADS)

Wehner, Martin; Jacobs, Philipp; Esser, Dominik; Schinkel, Helga; Schillberg, Stefan

2007-07-01

The functional analysis of plant cells at the cellular and subcellular levels requires novel technologies for the directed manipulation of individual cells. Lasers are increasingly exploited for the manipulation of plant cells, enabling the study of biological processes on a subcellular scale including transformation to generate genetically modified plants. In our setup either a picosecond laser operating at 1064 nm wavelength or a continuous wave laser diode emitting at 405 nm are coupled into an inverse microscope. The beams are focused to a spot size of about 1.5 μm and the tobacco cell protoplasts are irradiated. Optoporation is achieved when targeting the laser focal spot at the outermost edge of the plasma membrane. In case of the picosecond laser a single pulse with energy of about 0.4 μJ was sufficient to perforate the plasma membrane enabling the uptake of dye or DNA from the surrounding medium into the cytosol. When the ultraviolet laser diode at a power level of 17 mW is employed an irradiation time of 200 - 500 milliseconds is necessary to enable the uptake of macromolecules. In the presence of an EYFP encoding plasmid with a C-terminal peroxisomal signal sequence in the surrounding medium transient transformation of tobacco protoplasts could be achieved in up to 2% of the optoporated cells. Single cell perforation using this novel optoporation method shows that isolated plant cells can be permeabilized without direct manipulation. This is a valuable procedure for cell-specific applications, particularly where the import of specific molecules into plant cells is required for functional analysis.

Transition from nonresonant to resonant random lasers by the geometrical confinement of disorder.

PubMed

Ghofraniha, N; Viola, I; Zacheo, A; Arima, V; Gigli, G; Conti, C

2013-12-01

We report on a transition in random lasers that is induced by the geometrical confinement of the emitting material. Different dye doped paper devices with controlled geometry are fabricated by soft lithography and show two distinguished behaviors in the stimulated emission: in the absence of boundary constraints, the energy threshold decreases for larger laser volumes showing the typical trend of diffusive nonresonant random lasers, while when the same material is lithographed into channels, the walls act as cavity and the resonant behavior typical of standard lasers is observed. The experimental results are consistent with the general theories of random and standard lasers and a clear phase diagram of the transition is reported.

Immunoassays for pesticide monitoring

NASA Astrophysics Data System (ADS)

Wengatz, Ingrid; Szurdoki, Ferenc; Swamy, Anand R.; Evans, Lawrence, III; Patonay, Gabor; Stimmann, Eric; Delwiche, Michael; Stoutamire, Donald; Gee, Shirley J.; Hammock, Bruce D.

1995-05-01

This study compares two formats of rapid assays for the detection of pesticides (bromacil and pyrethroid based metabolites): enzyme linked immunosorbent assay (ELISA) and immunoassay with near-infrared (NIR) fluorescence detection. NIR dye immunoassay (NIRDIA) measurements were carried out by using two different instruments, both having a silicon photodiode as the detector and a laser diode for excitation. ELISA and NIRDIA were performed in a tracer format, where the specific antibody is bound to the surface of a microtiter plate well and the tracer with enzyme or fluorescent dye label competes with the analyte for the antibody binding site. It was demonstrated that the NIRDIA is at least as sensitive as the ELISA. Both assays detect pesticides in the (mu) g/L (ppb) range. Hapten- macromolecule-NIR dye-conjugates have been synthesized with various biopolymers (e.g., proteins) as carriers. The use of carrier macromolecules enables convenient purification of the cyanine dye derivatives. The mild conjugation method of the dye is based on isothiocyanate chemistry.

Laser treatment of port-wine stains

PubMed Central

Brightman, Lori A; Geronemus, Roy G; Reddy, Kavitha K

2015-01-01

Port-wine stains are a type of capillary malformation affecting 0.3% to 0.5% of the population. Port-wine stains present at birth as pink to erythematous patches on the skin and/or mucosa. Without treatment, the patches typically darken with age and may eventually develop nodular thickening or associated pyogenic granuloma. Laser and light treatments provide improvement through selective destruction of vasculature. A variety of vascular-selective lasers may be employed, with the pulsed dye laser being the most common and well studied. Early treatment produces more optimal results. Advances in imaging and laser treatment technologies demonstrate potential to further improve clinical outcomes. PMID:25624768