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.

A Plasma Ultraviolet Source for Short Wavelength Lasers.

DTIC Science & Technology

1988-04-15

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

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.

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.

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.

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.

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.

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.

Conformable large-area position-sensitive photodetectors based on luminescence-collecting silicone waveguides

NASA Astrophysics Data System (ADS)

Bartu, Petr; Koeppe, Robert; Arnold, Nikita; Neulinger, Anton; Fallon, Lisa; Bauer, Siegfried

2010-06-01

Position sensitive detection schemes based on the lateral photoeffect rely on inorganic semiconductors. Such position sensitive devices (PSDs) are reliable and robust, but preparation with large active areas is expensive and use on curved substrates is impossible. Here we present a novel route for the fabrication of conformable PSDs which allows easy preparation on large areas, and use on curved surfaces. Our device is based on stretchable silicone waveguides with embedded fluorescent dyes, used in conjunction with small silicon photodiodes. Impinging laser light (e.g., from a laser pointer) is absorbed by the dye in the PSD and re-emitted as fluorescence light at a larger wavelength. Due to the isotropic emission from the fluorescent dye molecules, most of the re-emitted light is coupled into the planar silicone waveguide and directed to the edges of the device. Here the light signals are detected via embedded small silicon photodiodes arranged in a regular pattern. Using a mathematical algorithm derived by extensive using of models from global positioning system (GPS) systems and human activity monitoring, the position of light spots is easily calculated. Additionally, the device shows high durability against mechanical stress, when clamped in an uniaxial stretcher and mechanically loaded up to 15% strain. The ease of fabrication, conformability, and durability of the device suggests its use as interface devices and as sensor skin for future robots.

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.

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

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.

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.

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.

Characteristics of a Broadband Dye Laser Using Pyrromethene and Rhodamine Dyes

NASA Technical Reports Server (NTRS)

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

2011-01-01

A broadband dye laser pumped by a frequency-doubled Nd:YAG laser with a full-width half-maximum (FWHM) from 592 to 610 nm was created for the use in a dual-pump broadband CARS system called 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 were 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, Pyrromethene dyes 597 and 650 as well as mixture of these dyes.

Dye-impregnated polymer-filled porous glass: a new composite material for solid state dye lasers and laser beam control optical elements (Abstract Only)

NASA Astrophysics Data System (ADS)

Koldunov, M. F.; Manenkov, Alexander A.; Sitnikov, N. M.; Dolotov, S. M.

1994-07-01

Polymer-filled microporous glass (PFMG) composite materials have been recently proposed as a proper host for dyes to create solid-state dye lasers and laser beam control elements (Q-switchers, etc.) [1,2]. In this paper we report investigation of some laser-related properties of Polymethilmethacrylate (PMAA) - filled porous glass doped with Rhodamine 6G perchiorate (active lasing dye) and 1055 dye (passive bleachable dye): laser induced damage threshold, lasmg efficiency, bleaching efficiency, and microhardness have been measured. All these characteristics have been found to be rather high indicating that PFMG composite materials are perspective hosts for dye impregnation and fabrication highly effective solid-state dye lasers and other laser related elements (Q-switchers, mode-lockers, modeselectors, spatial filters).

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

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.

TRASER - Total Reflection Amplification of Spontaneous Emission of Radiation

PubMed Central

Zachary, Christopher B.; Gustavsson, Morgan

2012-01-01

Background and Objective Light and lasers in medical therapy have made dramatic strides since their invention five decades ago. However, the manufacture of lasers can be complex and expensive which often makes treatments limited and costly. Further, no single laser will provide the correct parameters to treat all things. Hence, laser specialists often need multiple devices to practice their specialty. A new concept is described herein that has the potential to replace many lasers and light sources with a single ‘tunable’ device. Study Design/Material and Methods This device amplifies spontaneous emission of radiation by capturing and retaining photons through total internal reflection, hence the acronym Total Reflection Amplification of Spontaneous Emission of Radiation, or TRASER. Results Specific peaks of light can be produced in a reproducible manner with high peak powers of variable pulse durations, a large spot size, and high repetition rate. Conclusion Considering the characteristics and parameters of Traser technology, it is possible that this one device would likely be able to replace the pulsed dye laser and many other light based systems. PMID:22558261

Design and Construction of Simple, Nitrogen-Laser-Pumped, Tunable Dye Lasers

ERIC Educational Resources Information Center

Hilborn, Robert C.

1978-01-01

The basic physical principles of dye lasers are discussed and used to analyze the design and operation of tunable dye lasers pumped by pulsed nitrogen lasers. Details of the design and construction of these dye lasers are presented. Some simple demonstration experiments are described. (BB)

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.

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.

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

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.

Photophysical properties, photodegradation characteristics, and lasing action for coumarin dye C540A in polymeric media

NASA Astrophysics Data System (ADS)

Jones, Guilford, II; Huang, Zhennian; Pacheco, Dennis P., Jr.; Russell, Jeffrey A.

2004-07-01

Tunable solid-state dye lasers operating in the blue-green spectral region are attractive for a variety of applications. An important consideration in assessing the viability of this technology is the service life of the gain medium, which is presently limited by dye photodegradation. In this study, solid polymeric samples consisting of the coumarin dye C540A in modified PMMA were subjected to controlled photodegradation tests. The excitation laser was a flashlamp-pumped dye laser operating at 440 nm with a pulse duration of 1 μs. A complementary set of data was obtained for dye in solution phase for comparison purposes. Photophysical properties of C540A in water solution of polymethacrylic acid (PMAA) have been investigated with a view to assess the suitability of the sequestering polymer (PMAA) as an effective additive to facilitate use of a water medium for highly efficient blue-green dye lasers. Lasing action of C540A in aqueous PMAA has been realized using flashlamp-pumped laser system, yielding excellent laser efficiencies superior to that achieved in ethanolic solutions with the same dye. Laser characterization of dye in media included measurement of laser threshold, slope efficiency, pulse duration and output wavelength.

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.

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.

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.

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.

Multi-wavelength laser emission in dye-doped photonic liquid crystals.

PubMed

Wang, Chun-Ta; Lin, Tsung-Hsien

2008-10-27

Multi-wavelength lasing in a dye-doped cholesteric liquid crystal (CLC) cell is demonstrated. By adding oversaturated chiral dopant, the multi-photonic band CLC structure can be obtained with non-uniform chiral solubility. Under appropriate excitation, multi-wavelength lasing can be achieved with a multi-photonic band edge CLC structure. The number of lasing wavelengths can be controlled under various temperature processes. Nine wavelength CLC lasings were observed simultaneously. The wavelength range covers around 600-675nm. Furthermore, reversible tuning of multi-wavelength lasing was achieved by controlling CLC device temperature.

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.

A review of melasma treatment focusing on laser and light devices.

PubMed

Li, Janet Y; Geddes, Elizabeth Rc; Robinson, Deanne M; Friedman, Paul M

2016-12-01

Melasma is a pigmentary disorder of unclear etiology with numerous treatment options and high recurrence rates. Laser and light therapies may be utilized cautiously as second- or third-line options for recalcitrant melasma, but low-energy settings are preferred due to the risk of postinflammatory hyperpigmentation and melasma stimulation. Commonly used lasers include the low-fluence 1064-nm Q-switched neodymium-doped yttrium aluminum garnet laser, nonablative fractionated lasers, and intense pulsed light. Strict sun protection, concomitant use of bleaching agents, and maintenance treatments are necessary. A variety of other treatments that may also help to improve results are now being more widely adopted, including oral tranexamic acid, pulsed dye laser, antioxidants, and laser-assisted drug delivery. ©2016 Frontline Medical Communications.

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.

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.

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.

Laser micromachining of optical devices

NASA Astrophysics Data System (ADS)

Kopitkovas, Giedrius; Lippert, Thomas; David, Christian; Sulcas, Rokas; Hobley, Jonathan; Wokaun, Alexander J.; Gobrecht, Jens

2004-10-01

The combination of a gray tone phase mask with a laser assisted wet etching process was applied to fabricate complex microstructures in UV transparent dielectric materials. This one-step method allows the generation of arrays of plano-convex and Fresnel micro-lenses using a conventional XeCl excimer laser and an absorbing liquid, which is in contact with the UV transparent material. An array of plano-convex micro-lenses was tested as beam homogenizer for a high power XeCl excimer and ps Nd:YAG laser. The roughness of the etched features varies from several μm to 10 nm, depending on the laser fluence and concentration of the dye in the organic liquid. The etching process can be divided into several etching mechanisms which vary with laser fluence.

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.

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.

Ice matrix in reconfigurable microfluidic systems

NASA Astrophysics Data System (ADS)

Bossi, A. M.; Vareijka, M.; Piletska, E. V.; Turner, A. P. F.; Meglinski, I.; Piletsky, S. A.

2013-07-01

Microfluidic devices find many applications in biotechnologies. Here, we introduce a flexible and biocompatible microfluidic ice-based platform with tunable parameters and configuration of microfluidic patterns that can be changed multiple times during experiments. Freezing and melting of cavities, channels and complex relief structures created and maintained in the bulk of ice by continuous scanning of an infrared laser beam are used as a valve action in microfluidic systems. We demonstrate that pre-concentration of samples and transport of ions and dyes through the open channels created can be achieved in ice microfluidic patterns by IR laser-assisted zone melting. The proposed approach can be useful for performing separation and sensing processes in flexible reconfigurable microfluidic devices.

Stainless steel pinholes for fast fabrication of high-performance microchip electrophoresis devices by CO2 laser ablation.

PubMed

Yap, Yiing C; Guijt, Rosanne M; Dickson, Tracey C; King, Anna E; Breadmore, Michael C

2013-11-05

With the introduction of hobby laser engravers/cutters, the use of CO2 laser micromachining on poly(methyl methacrylate) (PMMA) has the potential for flexible, low cost, rapid prototyping of microfluidic devices. Unfortunately, the feature size created by most entry-level CO2 laser micromachining systems is too large to become a functional tool in analytical microfluidics. In this paper, we report a novel method to reduce the feature size of microchannels and the bulges formed at the rim of the channel during CO2 laser micromachining by passing the laser beam through a stainless steel pinhole. Without the pinhole, the channel width was typically 300 μm wide. However, when 50 or 35 μm diameter pinholes were used, channel widths of 60 and 25 μm, respectively, could be obtained. The height of the bulge deposited directly next to the channel was reduced to less than 0.8 μm with the pinhole during ablation. Separations of fluorescent dyes on devices ablated with and without the pinhole were compared. On devices fabricated with the pinhole, the number of theoretical plates/m was 2.2-fold higher compared to devices fabricated without the pinhole, and efficiencies comparable to embossed PMMA and laser ablated glass chips were obtained. A mass-produced commercial hobby laser (retailing at ∼$2500), when equipped with a $500 pinhole, represents a rapid and low-cost approach to the rapid fabrication of rigid plastic microchips including the narrow microchannels required for microchip electrophoresis.

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.

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.

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.

Proteus mirabilis viability after lithotripsy of struvite calculi

NASA Astrophysics Data System (ADS)

Prabakharan, Sabitha; Teichman, Joel M. H.; Spore, Scott S.; Sabanegh, Edmund; Glickman, Randolph D.; McLean, Robert J. C.

2000-05-01

Urinary calculi composed of struvite harbor urease-producing bacteria within the stone. The photothermal mechanism of holmium:YAG lithotripsy is uniquely different than other lithotripsy devices. We postulated that bacterial viability of struvite calculi would be less for calculi fragmented with holmium:YAG irradiation compared to other lithotripsy devices. Human calculi of known struvite composition (greater than 90% magnesium ammonium phosphate hexahydrate) were incubated with Proteus mirabilis. Calculi were fragmented with no lithotripsy (controls), or shock wave, intracorporeal ultrasonic, electrohydraulic, pneumatic, holmium:YAG or pulsed dye laser lithotripsy. After lithotripsy, stone fragments were sonicated and specimens were serially plated for 48 hours at 38 C. Bacterial counts and the rate of bacterial sterilization were compared. Median bacterial counts (colony forming units per ml) were 8 X 106 in controls and 3 X 106 in shock wave, 3 X 107 in ultrasonic, 4 X 105 in electrohydraulic, 8 X 106 in pneumatic, 5 X 104 in holmium:YAG and 1 X 106 in pulsed dye laser lithotripsy, p less than 0.001. The rate of bacterial sterilization was 50% for holmium:YAG lithotripsy treated stones versus 0% for each of the other cohorts, p less than 0.01. P. mirabilis viability is less after holmium:YAG irradiation compared to other lithotripsy devices.

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.

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.

Infrared-laser-based fundus angiography

NASA Astrophysics Data System (ADS)

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

1994-06-01

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

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.

A compact and portable optofluidic device for detection of liquid properties and label-free sensing

NASA Astrophysics Data System (ADS)

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

2017-06-01

Optofluidic lasers have been widely investigated over the last few years mainly because they can be easily integrated in sensor devices. However, high power pulse lasers are required as excitation sources, which, in practice, limit the portability of the system. Trying to overcome some of these limitations, in this paper we propose the combined use of a small CW laser with a Fabry-Perot optofluidic planar microcavity showing high sensitivity and versatility for detection of liquid properties and label-free sensing. Firstly, a fluorescein solution in ethanol is used to demonstrate the high performances of the FP microcavity as a temperature sensor both in the laser (high pump power above laser threshold) and in the fluorescence (low pump power) regimes. A shift in the wavelength of the resonant cavity modes is used to detect changes in the temperature and our results show that high sensitivities could be already obtained using cheap and portable CW diode lasers. In the second part of the paper, the demonstration of this portable device for label-free sensing is illustrated under low CW pumping. The wavelength positions of the optofluidic resonant modes are used to detect glucose concentrations in water solutions using a protein labelled with a fluorescent dye as the active medium.

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

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.

Treatment of burn scars in Fitzpatrick phototype III patients with a combination of pulsed dye laser and non-ablative fractional resurfacing 1550 nm erbium:glass/1927 nm thulium laser devices.

PubMed

Tao, Joy; Champlain, Amanda; Weddington, Charles; Moy, Lauren; Tung, Rebecca

2018-01-01

Burn scars cause cosmetic disfigurement and psychosocial distress. We present two Fitzpatrick phototype (FP) III patients with burn scars successfully treated with combination pulsed dye laser (PDL) and non-ablative fractional lasers (NAFL). A 30-year-old, FP III woman with a history of a second-degree burn injury to the bilateral arms and legs affecting 30% body surface area (BSA) presented for cosmetic treatment. The patient received three treatments with 595 nm PDL (7 mm, 8 J, 6 ms), six with the 1550 nm erbium:glass laser (30 mJ, 14% density, 4-8 passes) and five with the 1927 nm thulium laser (10 mJ, 30% density, 4-8 passes). Treated burn scars improved significantly in thickness, texture and colour. A 33-year-old, FP III man with a history of a second-degree burn injury of the left neck and arm affecting 7% BSA presented for cosmetic treatment. The patient received two treatments with 595 nm PDL (5 mm, 7.5 J, 6 ms), four with the 1550 nm erbium:glass laser (30 mJ, 14% density, 4-8 passes) and two with the 1927 nm thulium laser (10 mJ, 30% density, 4-8 passes). The burn scars became thinner, smoother and more normal in pigmentation and appearance. Our patients' burn scars were treated with a combination of PDL and NAFL (two wavelengths). The PDL targets scar hypervascularity, the 1550 nm erbium:glass stimulates collagen remodelling and the 1927 nm thulium targets epidermal processes, particularly hyperpigmentation. This combination addresses scar thickness, texture and colour with a low side effect profile and is particularly advantageous in patients at higher risk of post-procedure hyperpigmentation. Our cases suggest the combination of 595nm PDL plus NAFL 1550 nm erbium:glass/1927 nm thulium device is effective and well-tolerated for burn scar treatment in skin of colour.

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

PubMed

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

2014-01-01

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

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

PubMed Central

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

2014-01-01

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

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.).

Continuous-wave organic dye lasers and methods

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

Shapira, Ofer; Chua, Song-Liang; Zhen, Bo

2014-09-16

An organic dye laser produces a continuous-wave (cw) output without any moving parts (e.g., without using flowing dye streams or spinning discs of solid-state dye media to prevent photobleaching) and with a pump beam that is stationary with respect to the organic dye medium. The laser's resonant cavity, organic dye medium, and pump beam are configured to excite a lasing transition over a time scale longer than the associated decay lifetimes in the organic dye medium without photobleaching the organic dye medium. Because the organic dye medium does not photobleach when operating in this manner, it may be pumped continuouslymore » so as to emit a cw output beam. In some examples, operation in this manner lowers the lasing threshold (e.g., to only a few Watts per square centimeter), thereby facilitating electrical pumping for cw operation.« less

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.

Fluorescent intensity-based differential counting of FITC-doped silica nanoparticles: applications of CD4+ T-cell detection in microchip-type flowcytometers

NASA Astrophysics Data System (ADS)

Yun, Hoyoung; Bang, Hyunwoo; Lee, Won Gu; Lim, Hyunchang; Park, Junha; Lee, Joonmo; Riaz, Asif; Cho, Keunchang; Chung, Chanil; Han, Dong-Chul; Chang, Jun Keun

2007-12-01

Although CD4+ T-cells are an important target of HIV detection, there have been still major problems in making a diagnosis and monitoring in the third world and the region with few medical facilities. Then, it is necessary to use portable diagnosis devices at low cost when you put an enumeration of CD4+ T-cells. In general, the counting of CD4 below 200cells/uL makes it necessary to initiate antiretroviral treatment in adults (over 13 years old). However, lymphocyte subsets (including CD4 counts) of infants and young children are higher than those of adults. This fact shows the percentage of CD4+ T-cells of blood subsets, i.e., CD4/CD45%, CD4/CD8% or CD4/CD3% means a more reliable indicator of HIV infection than absolute counts in children. To know the percentage of CD4+ T-cell by using two fluorescent dyes of different emission wavelength, at least, one laser and two PMT detectors are in general needed. Then, it is so hard to develop a portable device like a 'toaster size' because this makes such a device more complex including many peripheral modules. In this study, we developed a novel technique to control the intensity of fluorescent dye-doped silica nanoparticles. I synthesized FITC-doped silica nanoparticles conjugated CD4 antibody 10 times brighter than FITC-conjugated CD45 antibody. With the difference of intensity of two fluorescent dyes, we measured two parameters by using only a single detector and laser. Most experiments were achieved with uFACS (microfabricated fluorescence-activated cell sorter) on an inverted microscope (IX71, Olympus). In conclusion, this method enables us to discriminate the difference between CD4 and CD45 in an intensity domain simultaneously. Furthermore, this technique would make it possible develop much cheaper and smaller devices which can count the number of CD4 T-cells.

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.

Laser-induced fluorescence detection platform for point-of-care testing

NASA Astrophysics Data System (ADS)

Berner, Marcel; Hilbig, Urs; Schubert, Markus B.; Gauglitz, Günter

2017-08-01

Point-of-care testing (POCT) devices for continuous low-cost monitoring of critical patient parameters require miniaturized and integrated setups for performing quick high-sensitivity analyses, away from central clinical laboratories. This work presents a novel and promising laser-induced fluorescence platform for measurements in direct optical test formats that leads towards such powerful POCT devices based on fluorescence-labeled immunoassays. Ultimate sensitivity of thin film photodetectors, integrated with microfluidics, and a comprehensive optimization of all system components aim at low-level signal detection in the targeted biosensor application. The setup acquires fluorescence signals from the volume of a microfluidic channel. An innovative sandwiching process forms a flow channel in the microfluidic chips by embedding laser-cut double-sided adhesive tapes. The custom fit of amorphous silicon based photodiode arrays to the geometry of the flow channel enables miniaturization, fully adequate for POCT devices. A free-beam laser excitation with line focus provides excellent alignment stability, allows for easy and reliable swapping of the disposable microfluidic chips, and therewith greatly improves the ease of use of the resulting integrated device. As a proof-of-concept of this novel in-volume measurement approach, the limit of detection for the dye DY636-COOH in pure water as a model fluorophore is examined and found to be 26 nmol l-1 .

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.

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.

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.

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.

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.

Dye foils with increased durability for passive Q-switching in a 1064 nm laser

NASA Astrophysics Data System (ADS)

Mierczyk, Z.; Kwasny, M.; Czeszko, J.

The results of spectral gel permeation chromatography and differential thermal analysis investigations of structures of dye foils consisting of bis-(4-dimethyl-amino-dithio-benzil)-nickel dye suspended in polymethylmethacrylate matrix, to be used for passive Q-switching in a 1064 nm laser, are reported. Results of experimental measurements and of numerical calculations of thermal and generating properties, and of the endurance of passive foil type Q-switches in the resonator of YAG:Nd(3+) laser are also presented. Optimization of polymerization conditions has enabled the production of dye foils with high thermal and photochemical resistance, which give stable operation of a giant pulsed laser.

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.

Oxazine laser dyes

DOEpatents

Hammond, Peter R.; Field, George F.

1992-01-01

New oxazine compounds useful as dye laser media in solution, are superiior to prior art materials. The oxazine dyes useful when pumped by the 578.2 nm copper line to operate in the 700-800 nm range are described by formula I ##STR1##

Laser and acoustic lens for lithotripsy

DOEpatents

Visuri, Steven R.; Makarewicz, Anthony J.; London, Richard A.; Benett, William J.; Krulevitch, Peter; Da Silva, Luiz B.

2002-01-01

An acoustic focusing device whose acoustic waves are generated by laser radiation through an optical fiber. The acoustic energy is capable of efficient destruction of renal and biliary calculi and deliverable to the site of the calculi via an endoscopic procedure. The device includes a transducer tip attached to the distal end of an optical fiber through which laser energy is directed. The transducer tip encapsulates an exogenous absorbing dye. Under proper irradiation conditions (high absorbed energy density, short pulse duration) a stress wave is produced via thermoelastic expansion of the absorber for the destruction of the calculi. The transducer tip can be configured into an acoustic lens such that the transmitted acoustic wave is shaped or focused. Also, compressive stress waves can be reflected off a high density/low density interface to invert the compressive wave into a tensile stress wave, and tensile stresses may be more effective in some instances in disrupting material as most materials are weaker in tension than compression. Estimations indicate that stress amplitudes provided by this device can be magnified more than 100 times, greatly improving the efficiency of optical energy for targeted material destruction.

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.

All-polymer photonic sensing platform based on whispering-gallery mode microgoblet lasers.

PubMed

Wienhold, T; Kraemmer, S; Wondimu, S F; Siegle, T; Bog, U; Weinzierl, U; Schmidt, S; Becker, H; Kalt, H; Mappes, T; Koeber, S; Koos, C

2015-09-21

We present an all-polymer photonic sensing platform based on whispering-gallery mode microgoblet lasers integrated into a microfluidic chip. The chip is entirely made from polymers, enabling the use of the devices as low-cost disposables. The microgoblet cavities feature quality factors exceeding 10(5) and are fabricated from poly(methyl methacrylate) (PMMA) using spin-coating, mask-based optical lithography, wet chemical etching, and thermal reflow. In contrast to silica-based microtoroid resonators, this approach replaces technically demanding vacuum-based dry etching and serial laser-based reflow techniques by solution-based processing and parallel thermal reflow. This enables scaling to large-area substrates, and hence significantly reduces device costs. Moreover, the resonators can be fabricated on arbitrary substrate materials, e.g., on transparent and flexible polymer foils. Doping the microgoblets with the organic dye pyrromethene 597 transforms the passive resonators into lasers. Devices have lasing thresholds below 0.6 nJ per pulse and can be efficiently pumped via free-space optics using a compact and low-cost green laser diode. We demonstrate that arrays of microgoblet lasers can be readily integrated into a state-of-the-art microfluidic chip replicated via injection moulding. In a proof-of-principle experiment, we show the viability of the lab-on-a-chip via refractometric sensing, demonstrating a bulk refractive index sensitivity (BRIS) of 10.56 nm per refractive index unit.

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.

Millimeter-wave generation and characterization of a GaAs FET by optical mixing

NASA Technical Reports Server (NTRS)

Ni, David C.; Fetterman, Harold R.; Chew, Wilbert

1990-01-01

Coherent mixing of optical radiation from a tunable continuous-wave dye laser and a stabilized He-Ne laser was used to generate millimeter-wave signals in GaAs FETs attached to printed-circuit millimeter-wave antennas. The generated signal was further down-converted to a 2-GHz IF by an antenna-coupled millimeter-wave local oscillator at 62 GHz. Detailed characterizations of power and S/N under different bias conditions have been performed. This technique is expected to allow signal generation and frequency-response evaluation of millimeter-wave devices at frequencies as high as 100 GHz.

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.

Label free biosensor incorporating a replica-molded, vertically emitting distributed feedback laser

NASA Astrophysics Data System (ADS)

Lu, M.; Choi, S. S.; Wagner, C. J.; Eden, J. G.; Cunningham, B. T.

2008-06-01

A label free biosensor based upon a vertically emitting distributed feedback (DFB) laser has been demonstrated. The DFB laser comprises a replica-molded, one-dimensional dielectric grating coated with laser dye-doped polymer as the gain medium. Adsorption of biomolecules onto the laser surface alters the DFB laser emission wavelength, thereby permitting the kinetic adsorption of a protein polymer monolayer or the specific binding of small molecules to be quantified. A bulk sensitivity of 16.6nm per refractive index unit and the detection of a monolayer of the protein polymer poly(Lys, Phe) have been observed with this biosensor. The sensor represents a departure from conventional passive resonant optical sensors from the standpoint that the device actively generates its own narrowband high intensity output without stringent requirements on the coupling alignments, resulting in a simple, robust illumination and detection configuration.

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.

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.

Dye Foils With Increased Durability For Passive Q-Switching In A 1064 Nm Laser.

NASA Astrophysics Data System (ADS)

Mierczyk, Z.; Kwasny, M.; Czeszko, J.

1987-10-01

The results of spectral (IR, UV-VIS, H NMR) , gel permeation chromatography and differential thermal analysis investigations of structures of dye foils consisting of bis-(4-dimethyl-amino-dithio-benzil)-nickel dye suspended in polymethylmethacrylate matrix, to be used for passive Q-switching in a 1064 nm laser, are reported. Results of experimental measurements and of numerical calculations of thermal and generating properties, and of the endurance of passive foil type Q-switches in the resona-tor of YAG:Nd3+ laser are also presented. Optimization of polymerization conditions has enabled the production of dye foils with high thermal and photochemical resistance, which give stable operation of a giant pulsed laser.

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.

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

PubMed

Cassuto, D A; Ancona, D M; Emanuelli, G

2000-09-01

Facial telangiectasias are a common cause of cosmetic concern. Current treatment modalities present various untoward effects and limits. The pulsed dye laser has been considered the gold standard in efficacy and safety; unfortunately it causes postoperative intracutaneous hematomata, discouraging many patients from undergoing this treatment. Several other vascular lasers (argon, tunable dye, copper, krypton, etc.) are disadvantaged by the risk of hypopigmented and atrophic scars. We assessed a recent powerful version of the potassium titanyl phosphate (KTP) 532 nm laser, which delivers sufficient energy in single pulse lasting 10-50 msec (DioLite 532; IRIDEX, Mountain View, CA, USA). Collateral damage is reduced while the heating of the vessel is slow enough to avoid explosive photothermolysis with its associated purpura. Sixty six patients with facial telangiectasias were treated. In 62/66 patients (93.9%) we achieved a 75-100% clearance of the lesions, while two treatments were needed to reach an acceptable clearance in the remaining 4/66 patients (6.1%). The eventual need for more sessions was well tolerated because the acceptable postoperative appearance allowed patients to continue normal business and social activities between treatments. No permanent complications or undesired effects were noted. We conclude that this diode-pumped frequency-doubled Nd:YAG laser is an effective device for the treatment of facial telangiectasias, with a low profile of undesired effects that can be well tolerated by patients.

Integrated Micro-Optics for Microfluidic Detection.

PubMed

Kazama, Yuto; Hibara, Akihide

2016-01-01

A method of embedding micro-optics into a microfluidic device was proposed and demonstrated. First, the usefulness of embedded right-angle prisms was demonstrated in microscope observation. Lateral-view microscopic observation of an aqueous dye flow in a 100-μm-sized microchannel was demonstrated. Then, the embedded right-angle prisms were utilized for multi-beam laser spectroscopy. Here, crossed-beam thermal lens detection of a liquid sample was applied to glucose detection.

Multicolored Emission and Lasing in DCM-Adamantane Plasma Nanocomposite Optical Films.

PubMed

Alcaire, María; Cerdán, Luis; Zamarro, Fernando Lahoz; Aparicio, Francisco J; González, Juan Carlos; Ferrer, Francisco J; Borras, Ana; Espinós, Juan Pedro; Barranco, Angel

2017-03-15

We present a low-temperature versatile protocol for the fabrication of plasma nanocomposite thin films to act as tunable emitters and optical gain media. The films are obtained by the remote plasma-assisted deposition of a 4-(dicyano-methylene)-2-methyl-6-(4-dimethylamino-styryl)-4H-pyran (DCM) laser dye alongside adamantane. The experimental parameters that determine the concentration of the dye in the films and their optical properties, including light absorption, the refractive index, and luminescence, are evaluated. Amplified spontaneous emission experiments in the DCM/adamantane nanocomposite waveguides show the improvement of the copolymerized nanocomposites' properties compared to films that were deposited with DCM as the sole precursor. Moreover, one-dimensional distributed feed-back laser emission is demonstrated and characterized in some of the nanocomposite films that are studied. These results open new paths for the optimization of the optical and lasing properties of plasma nanocomposite polymers, which can be straightforwardly integrated as active components in optoelectronic devices.

Lasing in silicon–organic hybrid waveguides

PubMed Central

Korn, Dietmar; Lauermann, Matthias; Koeber, Sebastian; Appel, Patrick; Alloatti, Luca; Palmer, Robert; Dumon, Pieter; Freude, Wolfgang; Leuthold, Juerg; Koos, Christian

2016-01-01

Silicon photonics enables large-scale photonic–electronic integration by leveraging highly developed fabrication processes from the microelectronics industry. However, while a rich portfolio of devices has already been demonstrated on the silicon platform, on-chip light sources still remain a key challenge since the indirect bandgap of the material inhibits efficient photon emission and thus impedes lasing. Here we demonstrate a class of infrared lasers that can be fabricated on the silicon-on-insulator (SOI) integration platform. The lasers are based on the silicon–organic hybrid (SOH) integration concept and combine nanophotonic SOI waveguides with dye-doped organic cladding materials that provide optical gain. We demonstrate pulsed room-temperature lasing with on-chip peak output powers of up to 1.1 W at a wavelength of 1,310 nm. The SOH approach enables efficient mass-production of silicon photonic light sources emitting in the near infrared and offers the possibility of tuning the emission wavelength over a wide range by proper choice of dye materials and resonator geometry. PMID:26949229

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 Shape Memory Polymer Microactuator for Thrombus Removal Following Ischemic Stroke: Preliminary In Vitro Analysis

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

Small, W; Metzger, M F; Wilson, T S

2004-09-23

Due to the narrow (3-hour) treatment window for effective use of the thrombolytic drug recombinant tissue-type plasminogen activator (rt-PA), there is a need to develop alternative treatments for ischemic stroke. We are developing an intravascular device for mechanical thrombus removal using shape memory polymer (SMP). We propose to deliver the SMP microactuator in its secondary straight rod form (length = 4 cm, diameter = 350 {micro}m) through a catheter distal to the vascular occlusion. The microactuator, which is mounted on the end of an optical fiber, is then transformed into its primary corkscrew shape by laser heating (diode laser, {lambda}more » = 800 nm) above its soft phase glass transition temperature (T{sub gs} = 55 C). Once deployed, the microactuator is retracted and the captured thrombus is removed to restore blood flow. The SMP is doped with indocyanine green (ICG) dye to increase absorption of the laser light. Successful deployment of the microactuator depends on the optical properties of the ICG-doped SMP and the optical coupling efficiency of the interface between the optical fiber and the SMP. Spectrophotometry, thermal imaging, and computer simulation aided the initial design effort and continue to be useful tools for optimization of the dye concentration and laser power. Thermomechanical testing was performed to characterize the elastic modulus of the SMP. We have demonstrated laser-activation of the SMP microactuator in air at room temperature, suggesting this concept is a promising therapeutic alternative to rt-PA.« less

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.

A Comparison of Microvascular Responses to Visible and Near-Infrared Lasers

PubMed Central

Li, D.; Farshidi, D.; Wang, G.X.; He, Y.L.; Kelly, K.M.; Wu, W.J.; Chen, B.; Ying, Z.X.

2015-01-01

Background and Objective Pulsed dye laser (PDL) is a commonly used treatment for Port Wine Stain birthmarks (PWS). However, deeper components of PWS are often resistant to PDL. Deeper penetrating lasers, including the long pulsed Neodymium:Yttrium Aluminum Garnet (Nd:YAG) laser have been used, but carry greater risk. This study evaluates the distinct blood vessel thermal responses to visible (595 nm) and near infrared (1,064 nm) lasers using animal and numerical models. Study Design/Materials and Methods Blood vessels in the rodent dorsal skin chamber (DSC) were irradiated by a 595 nm PDL and a long-pulsed 1,064 nm Nd:YAG laser. Laser-induced immediate and 1-hour post-structural and functional changes in the vessels were documented. Numerical simulations were conducted using a 1,000 μm depth SD mouse skin fold to simulate experimental conditions. Results PDL irradiation produced immediate blood vessel hemorrhage. Modeling indicated this occurs due to preferential heating of the superior parts of large blood vessels. Nd:YAG irradiation resulted in blood vessel constriction; modeling indicated more uniform heating of vessel walls. Conclusion PDL and Nd:YAG lasers result in distinct tissue responses. This supports different observable clinical treatment end points when using these devices. Vessel constriction associated with the Nd:YAG may be more difficult to observe and is one reason this device may carry greater risk. Lasers Surg. Med. 46:479–487, 2014. PMID:24974953

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.

Violet laser diodes as light sources for cytometry.

PubMed

Shapiro, H M; Perlmutter, N G

2001-06-01

Violet laser diodes have recently become commercially available. These devices emit 5-25 mW in the range of 395-415 nm, and are available in systems that incorporate the diodes with collimating optics and regulated power supplies in housing incorporating thermoelectric coolers, which are necessary to maintain stable output. Such systems now cost several thousand dollars, but are expected to drop substantially in price. Materials and Methods A 4-mW, 397-nm violet diode system was used in a laboratory-built flow cytometer to excite fluorescence of DAPI and Hoechst dyes in permeabilized and intact cells. Forward and orthogonal light scattering were also measured. DNA content histograms with good precision (G(0)/G(1) coefficient of variation 1.7%) were obtained with DAPI staining; precision was lower using Hoechst 33342. Hoechst 34580, with an excitation maximum nearer 400 nm, yielded the highest fluorescence intensity, but appeared to decompose after a short time in solution. Scatter signals exhibited relatively broad distributions. Violet laser diodes are relatively inexpensive, compact, efficient, and quiet light sources for DNA fluorescence measurement using DAPI and Hoechst dyes; they can also excite several other fluorescent probes. Copyright 2001 Wiley-Liss, Inc.

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

Feedback mechanism for smart nozzles and nebulizers

DOEpatents

Montaser, Akbar [Potomac, MD; Jorabchi, Kaveh [Arlington, VA; Kahen, Kaveh [Kleinburg, CA

2009-01-27

Nozzles and nebulizers able to produce aerosol with optimum and reproducible quality based on feedback information obtained using laser imaging techniques. Two laser-based imaging techniques based on particle image velocimetry (PTV) and optical patternation map and contrast size and velocity distributions for indirect and direct pneumatic nebulizations in plasma spectrometry. Two pulses from thin laser sheet with known time difference illuminate droplets flow field. Charge coupled device (CCL)) captures scattering of laser light from droplets, providing two instantaneous particle images. Pointwise cross-correlation of corresponding images yields two-dimensional velocity map of aerosol velocity field. For droplet size distribution studies, solution is doped with fluorescent dye and both laser induced florescence (LIF) and Mie scattering images are captured simultaneously by two CCDs with the same field of view. Ratio of LIF/Mie images provides relative droplet size information, then scaled by point calibration method via phase Doppler particle analyzer.

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.

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.

Durability of switchable QR code carriers under hydrolytic and photolytic conditions

NASA Astrophysics Data System (ADS)

Ecker, Melanie; Pretsch, Thorsten

2013-09-01

Following a guest diffusion approach, the surface of a shape memory poly(ester urethane) (PEU) was either black or blue colored. Bowtie-shaped quick response (QR) code carriers were then obtained from laser engraving and cutting, before thermo-mechanical functionalization (programming) was applied to stabilize the PEU in a thermo-responsive (switchable) state. The stability of the dye within the polymer surface and long-term functionality of the polymer were investigated against UVA and hydrolytic ageing. Spectrophotometric investigations verified UVA ageing-related color shifts from black to yellow-brownish and blue to petrol-greenish whereas hydrolytically aged samples changed from black to greenish and blue to light blue. In the case of UVA ageing, color changes were accompanied by dye decolorization, whereas hydrolytic ageing led to contrast declines due to dye diffusion. The Michelson contrast could be identified as an effective tool to follow ageing-related contrast changes between surface-dyed and laser-ablated (undyed) polymer regions. As soon as the Michelson contrast fell below a crucial value of 0.1 due to ageing, the QR code was no longer decipherable with a scanning device. Remarkably, the PEU information carrier base material could even then be adequately fixed and recovered. Hence, the surface contrast turned out to be the decisive parameter for QR code carrier applicability.

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 ...

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.

Development of high-power dye laser chain

NASA Astrophysics Data System (ADS)

Konagai, Chikara; Kimura, Hironobu; Fukasawa, Teruichiro; Seki, Eiji; Abe, Motohisa; Mori, Hideo

2000-01-01

Copper vapor laser (CVL) pumped dye laser (DL) system, both in a master oscillator power amplifier (MOPA) configuration, has been developed for Atomic Vapor Isotope Separation program in Japan. Dye laser output power of about 500 W has been proved in long-term operations over 200 hours. High power fiber optic delivery system is utilized in order to efficiently transport kilowatt level CVL beams to the DL MOPA. Single model CVL pumped DL oscillator has been developed and worked for 200 hours within +/- 0.1 pm wavelength stability. Phase modulator for spreading spectrum to the linewidth of hyperfine structure has been developed and demonstrated.

Atraumatic laser treatment for laryngeal papillomatosis

NASA Astrophysics Data System (ADS)

McMillan, Kathleen; Pankratov, Michail M.; Wang, Zhi; Bottrill, Ian; Rebeiz, Elie E.; Shapshay, Stanley M.

1994-09-01

Ten to fifteen thousand new cases of recurrent respiratory papillomatosis (RRP) are diagnosed each year in the United States. RRP is caused by the human papillomavirus (HPV) and is characterized by recurrent, non-malignant, proliferative lesions of the larynx. Patients with RRP undergo numerous microsurgical procedures to remove laryngeal papilloma threatening airway patency and interfering with phonation. The standard surgical technique involves CO2 laser vaporization of laryngeal epithelium affected by the lesions, and requires general anesthesia. The pulsed dye laser operating at 585 nm has previously been demonstrated to be effective in clearing HPV lesions of the skin (verrucae). For treatment of RRP, the fiber- compatible pulsed dye laser radiation may be delivered under local anesthesia using a flexible intranasal laryngoscope. Potential advantages of the pulsed dye laser treatment over CO2 laser surgery include (1) reduced morbidity, especially a lower risk of laryngeal scarring; (2) lower cost; (3) reduced technical difficulty; and (4) reduced risk of viral dissemination or transmission. In vivo studies are underway to determine the effect of pulsed dye laser radiation on normal canine laryngeal tissue.

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

Wide-band tunable photonic bandgap device and laser in dye-doped liquid crystal refilled cholesteric liquid crystal polymer template system

NASA Astrophysics Data System (ADS)

Lin, Jia-De; Lin, Hong-Lin; Lin, Hsin-Yu; Wei, Guan-Jhong; Lee, Chia-Rong

2017-02-01

The scientists in the field of liquid crystal (LC) have paid significant attention in the exploration of novel cholesteric LC (CLC) polymer template (simply called template) in recent years. The self-assembling nanostructural template with chirality can effectively overcome the limitation in the optical features of traditional CLCs, such as enhancement of reflectivity over 50%, multiple photonic bandgaps (PBGs), and changeable optical characteristics by flexibly replacing the refilling LC materials, and so on. This work fabricates two gradient-pitched CLC templates with two opposite handednesses, which are then merged as a spatially tunable and highly reflective CLC template sample. This sample can simultaneously reflect right- and left-circularly polarized lights and the tunable spectral range includes the entire visible region. By increasing the temperature of the template sample exceeding the clearing point of the refilling LC, the light scattering significantly decreases and the reflectance effectively increase to exceed 50% in the entire visible region. This device has a maximum reflectance over 85% and a wide-band spatial tunability in PBG between 400 nm and 800 nm which covers the entire visible region. Not only the sample can be employed as a wide-band spatially tunable filter, but also the system doping with two suitable laser dyes which emitted fluorescence can cover entire visible region can develop a low-threshold, mirror-less laser with a spatial tunability at spectral regions including blue to red region (from 484 nm to 634 nm) and simultaneous lasing emission of left- and right-circular polarizations.

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)

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.

Fusion of Renewable Ring Resonator Lasers and Ultrafast Laser Inscribed Photonic Waveguides

PubMed Central

Chandrahalim, Hengky; Rand, Stephen C.; Fan, Xudong

2016-01-01

We demonstrated the monolithic integration of reusable and wavelength reconfigurable ring resonator lasers and waveguides of arbitrary shapes to out-couple and guide laser emission on the same fused-silica chip. The ring resonator hosts were patterned by a single-mask standard lithography, whereas the waveguides were inscribed in the proximity of the ring resonator by using 3-dimensional femtosecond laser inscription technology. Reusability of the integrated ring resonator – waveguide system was examined by depositing, removing, and re-depositing dye-doped SU-8 solid polymer, SU-8 liquid polymer, and liquid solvent (toluene). The wavelength reconfigurability was validated by employing Rhodamine 6G (R6G) and 3,3′-Diethyloxacarbocyanine iodide (CY3) as exemplary gain media. In all above cases, the waveguide was able to couple out and guide the laser emission. This work opens a door to reconfigurable active and passive photonic devices for on-chip coherent light sources, optical signal processing, and the investigation of new optical phenomena. PMID:27600872

Fusion of Renewable Ring Resonator Lasers and Ultrafast Laser Inscribed Photonic Waveguides.

PubMed

Chandrahalim, Hengky; Rand, Stephen C; Fan, Xudong

2016-09-07

We demonstrated the monolithic integration of reusable and wavelength reconfigurable ring resonator lasers and waveguides of arbitrary shapes to out-couple and guide laser emission on the same fused-silica chip. The ring resonator hosts were patterned by a single-mask standard lithography, whereas the waveguides were inscribed in the proximity of the ring resonator by using 3-dimensional femtosecond laser inscription technology. Reusability of the integrated ring resonator - waveguide system was examined by depositing, removing, and re-depositing dye-doped SU-8 solid polymer, SU-8 liquid polymer, and liquid solvent (toluene). The wavelength reconfigurability was validated by employing Rhodamine 6G (R6G) and 3,3'-Diethyloxacarbocyanine iodide (CY3) as exemplary gain media. In all above cases, the waveguide was able to couple out and guide the laser emission. This work opens a door to reconfigurable active and passive photonic devices for on-chip coherent light sources, optical signal processing, and the investigation of new optical phenomena.

Review of photorejuvenation: devices, cosmeceuticals, or both?

PubMed

Rokhsar, Cameron K; Lee, Sandra; Fitzpatrick, Richard E

2005-09-01

Both the public and the medical profession have placed a lot of attention on reversal of signs of aging and photodamage, resulting in numerous cosmeceutical products and nonablative laser techniques designed to achieve these results. The purpose of this report is to briefly review both the cosmeceutical products and nonablative laser techniques that appear to be most promising based on published studies. After this review, recommendations for potential enhancement of benefits by combining cosmeceuticals and laser treatments will be explored. Pulsed dye lasers targeting microvessels, intense pulsed light targeting both melanin and microvessels, and midinfrared lasers targeting dermal water and collagen all appear to have some ability to improve skin texture, color, and wrinkling. Retinoids, vitamin C, alpha-hydroxy acids, and topical growth factors may also stimulate repair mechanisms that result in similar improvements in photodamaged skin. Although supported only by theoretic considerations and anecdotal reports, it seems logical that the concurrent use of appropriate cosmeceuticals with nonablative laser photorejuvenation should result in enhanced benefits.

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.

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.

Optics with Semiconductors: Ultrafast Physics for Devices

DTIC Science & Technology

1991-03-01

pass through a thinner (ɛÜ0 /im) saturable absorber jet of malachite green placed between the fourth and fifth passes. The saturable absorber reduces...this laser [22]. In the amplifier, the gain/absorber dye pair is SR640/ malachite green, after Knox [8]. SPli Vol 126$ Appttctiom of Ukrtshon Lssf...telescope, followed by a short tele- scope with a saturable absorber at its focus ( malachite green in a ~200 pm jet of ethylene glycol, produced by

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.

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

Blankenship, H.Lee; Thompson, Dan; United States. Bonneville Power Administration. Division of Fish and Wildlife

The first year of work with development of lasers as a mass marking technique provided both disappointing and encouraging results. A Coumarin Dye 480 laser was used to mark coho salmon in a variety of body locations and with varying energy levels. A ``bleached`` white mark was made void of any pigment. Areas marked included the nape area behind the head and in front of the dorsal fin, slightly above the anal fin, the upper lobe of the caudal fin, the dorsal fin and on the operculum. The mark appeared immediately after being lasered but started to gradually fade aftermore » one month and was fairly completely re-pigmented after three months. Complete removal and notching of the adipose fin was also attempted with a Carbon Dioxide laser. This surgical method of fin removal appears to have advantages over scissor excision (no bleeding or regeneration), and has possible application as part of a device or system which could be employed for mass marking.« less

A transmission imaging spectrograph and microfabricated channel system for DNA analysis.

PubMed

Simpson, J W; Ruiz-Martinez, M C; Mulhern, G T; Berka, J; Latimer, D R; Ball, J A; Rothberg, J M; Went, G T

2000-01-01

In this paper we present the development of a DNA analysis system using a microfabricated channel device and a novel transmission imaging spectrograph which can be efficiently incorporated into a high throughput genomics facility for both sizing and sequencing of DNA fragments. The device contains 48 channels etched on a glass substrate. The channels are sealed with a flat glass plate which also provides a series of apertures for sample loading and contact with buffer reservoirs. Samples can be easily loaded in volumes up to 640 nL without band broadening because of an efficient electrokinetic stacking at the electrophoresis channel entrance. The system uses a dual laser excitation source and a highly sensitive charge-coupled device (CCD) detector allowing for simultaneous detection of many fluorescent dyes. The sieving matrices for the separation of single-stranded DNA fragments are polymerized in situ in denaturing buffer systems. Examples of separation of single-stranded DNA fragments up to 500 bases in length are shown, including accurate sizing of GeneCalling fragments, and sequencing samples prepared with a reduced amount of dye terminators. An increase in sample throughput has been achieved by color multiplexing.

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

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

Upgrades to the MARIA Helicon Experiment at UW-Madison

NASA Astrophysics Data System (ADS)

Green, Jonathan; Hershkowitz, Noah; Schmitz, Oliver; Severn, Greg; Winters, Victoria

2016-10-01

The MARIA helicon plasma device at UW Madison is setup to investigate the neutral particle fueling of helicon discharges. Following initial results from the 668.614nm diode laser LIF system, the active spectroscopy diagnostic suite was expanded by establishing a 1.4J pulsed Nd:YAG pumped dye laser. To verify the new laser system, a comparison of measured ion velocities near a target plate was made between the diode based and dye based LIF systems. Additionally, theory and further verification of a new technique for measuring ion velocities leveraging Zeeman splitting is presented. During a campaign with <= 750W RF power, densities in the range of 1x1018 m-3 and 2 eV electron temperature were achieved with 4.1 mTorr of argon and a magnetic field of 750G. To achieve higher densities and explore the physics of neutral depletion, the available RF power was increased from 750W to 2kW, with further expansion to 4kW on a single antenna planned. For both power levels a clear helicon mode can be reliably established and its extension increases with increasing RF power. Basic plasma characterization at the higher RF power, such as electron density vs magnetic field scans, will be presented. This work was funded by the NSF CAREER Award PHY-1455210.

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.

Hyperbranched quasi-1D nanostructures for solid-state dye-sensitized solar cells.

PubMed

Passoni, Luca; Ghods, Farbod; Docampo, Pablo; Abrusci, Agnese; Martí-Rujas, Javier; Ghidelli, Matteo; Divitini, Giorgio; Ducati, Caterina; Binda, Maddalena; Guarnera, Simone; Li Bassi, Andrea; Casari, Carlo Spartaco; Snaith, Henry J; Petrozza, Annamaria; Di Fonzo, Fabio

2013-11-26

In this work we demonstrate hyperbranched nanostructures, grown by pulsed laser deposition, composed of one-dimensional anatase single crystals assembled in arrays of high aspect ratio hierarchical mesostructures. The proposed growth mechanism relies on a two-step process: self-assembly from the gas phase of amorphous TiO2 clusters in a forest of tree-shaped hierarchical mesostructures with high aspect ratio; oriented crystallization of the branches upon thermal treatment. Structural and morphological characteristics can be optimized to achieve both high specific surface area for optimal dye uptake and broadband light scattering thanks to the microscopic feature size. Solid-state dye sensitized solar cells fabricated with arrays of hyperbranched TiO2 nanostructures on FTO-glass sensitized with D102 dye showed a significant 66% increase in efficiency with respect to a reference mesoporous photoanode and reached a maximum efficiency of 3.96% (among the highest reported for this system). This result was achieved mainly thanks to an increase in photogenerated current directly resulting from improved light harvesting efficiency of the hierarchical photoanode. The proposed photoanode overcomes typical limitations of 1D TiO2 nanostructures applied to ss-DSC and emerges as a promising foundation for next-generation high-efficiency solid-state devices comprosed of dyes, polymers, or quantum dots as sensitizers.

[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

A frequency doubled pressure-tunable oscillator-amplifier dye laser system

NASA Technical Reports Server (NTRS)

Moriarty, A.; Heaps, W.; Davis, D. D.

1976-01-01

A tunable high-repetition-rate oscillator-amplifier dye-laser system is reported. The dye laser described was longitudinally pumped with the second harmonic of a Nd-YAG laser operating at 10 Hz. Using three Faraday-Perot etalons and pressure tuning, a maximum fundamental output power of the order of 6 MW with a corresponding spectral width of less than 0.003 nm at 564 nm was obtained. The fundamental at 564 nm was frequency doubled to give a maximum power level of 0.6 MW of second-harmonic output power with a spectral width less than 0.0015 nm at 282 nm. Frequency stability could be maintained to within approximately 15% of the line-width.

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.

The family of micro sensors for remote control the pollution in liquids and gases

NASA Astrophysics Data System (ADS)

Tulaikova, Tamara; Kocharyun, Gevorg; Rogerson, Graham; Burmistrova, Ludmyla; Sychugov, Vladimir; Dorojkin, Peter

2005-10-01

There are the results for the 3 groups of fiber-optical sensors. First is the fiber-optical sensor with changed sensitive heads on the base on porous polymer with clamped activated dye. Vibration method for fiber-optical sensors provides more convenient output measurements of resonant frequency changes, in comparison with the first device. The self-focusing of the living sells into optical wave-guides in laser road in water will be considered as a new touch method for environment remote sensing.

Bibliography of Soviet Laser Developments, Number 64, March - April 1983.

DTIC Science & Technology

1984-03-06

140. Mirza, S.Yu. * A.N. Soldatov, and V.B. Sukhanov (0). Efficient conversion of radiation in metal vapor to tunable lasing in dyes. Sb 8, 81-107...Device for reconstructing images. Otkr izobr, no. 16, 1983, 1015508. 521. Sander, Ye.A., V.I. Sukhanov , and S.A. Shoydin (0). Study on holographic...Deposit at VINITI, no. 6231-82, 17 Dec 1982, 27 p. (RZhF, 3/83, 3D975) 556. Sukhanov , V.I., A.Ye. Petnikov, and Yu.V. Ashcheulov (0). Hologram

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.

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.

Direct grafting of long-lived luminescent indicator dyes to GaN light-emitting diodes for chemical microsensor development.

PubMed

López-Gejo, Juan; Navarro-Tobar, Álvaro; Arranz, Antonio; Palacio, Carlos; Muñoz, Elías; Orellana, Guillermo

2011-10-01

Two new methods for covalent functionalization of GaN based on plasma activation of its surface are presented. Both of them allow attachment of sulfonated luminescent ruthenium(II) indicator dyes to the p- and n-type semiconductor as well as to the surface of nonencapsulated chips of GaN light-emitting diodes (blue LEDs). X-ray photoelectron spectroscopy analysis of the functionalized semiconductor confirms the formation of covalent bonds between the GaN surface and the dye. Confocal fluorescence microscopy with single-photon-timing (SPT) detection has been used for characterization of the functionalized surfaces and LED chips. While the ruthenium complex attached to p-GaN under an oxygen-free atmosphere gives significantly long mean emission lifetimes for the indicator dye (ca. 2000 ns), the n-GaN-functionalized surfaces display surprisingly low values (600 ns), suggesting the occurrence of a quenching process. A photoinduced electron injection from the dye to the semiconductor conduction band, followed by a fast back electron transfer, is proposed to be responsible for the excited ruthenium dye deactivation. This process invalidates the use of the n-GaN/dye system for sensing applications. However, for p-GaN/dye materials, the luminescence decay accelerates in the presence of O(2). The moderate sensitivity is attributed to the fact that only a monolayer of indicator dye is anchored to the semiconductor surface but serves as a demonstrator device. Moreover, the luminescence decays of the functionalized LED chip measured with excitation of either an external (laser) source or the underlying LED emission (from p-GaN/InGaN quantum wells) yield the same mean luminescence lifetime. These results pave the way for using advanced LEDs to develop integrateable optochemical microsensors for gas analysis. © 2011 American Chemical Society

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.

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

NASA Astrophysics Data System (ADS)

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

1990-06-01

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

21 CFR 864.1850 - Dye and chemical solution stains.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Dye and chemical solution stains. 864.1850 Section... (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Biological Stains § 864.1850 Dye and chemical solution stains. (a) Identification. Dye and chemical solution stains for medical purposes are mixtures of...

21 CFR 864.1850 - Dye and chemical solution stains.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Dye and chemical solution stains. 864.1850 Section... (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Biological Stains § 864.1850 Dye and chemical solution stains. (a) Identification. Dye and chemical solution stains for medical purposes are mixtures of...

21 CFR 864.1850 - Dye and chemical solution stains.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Dye and chemical solution stains. 864.1850 Section... (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Biological Stains § 864.1850 Dye and chemical solution stains. (a) Identification. Dye and chemical solution stains for medical purposes are mixtures of...

21 CFR 864.1850 - Dye and chemical solution stains.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Dye and chemical solution stains. 864.1850 Section... (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Biological Stains § 864.1850 Dye and chemical solution stains. (a) Identification. Dye and chemical solution stains for medical purposes are mixtures of...

21 CFR 864.1850 - Dye and chemical solution stains.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Dye and chemical solution stains. 864.1850 Section... (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Biological Stains § 864.1850 Dye and chemical solution stains. (a) Identification. Dye and chemical solution stains for medical purposes are mixtures of...

Effects of vacuum exposure on stress and spectral shift of high reflective coatings

NASA Astrophysics Data System (ADS)

Stolz, C. J.; Taylor, J. R.; Eickelberg, W. K.; Lindh, J. D.

1992-06-01

The Atomic Vapor Laser Isotope Laser Separation (AVLIS) program operates the world's largest average power dye laser; the dye laser beams are combined, formatted, and transported in vacuum. The optical system is aligned at atmosphere, while the system must meet requirements in vacuum. Therefore, coating performance must be characterized in both atmosphere and vacuum. Changes in stress and spectral shift in ambient and vacuum environments are reported for conventional and dense multilayer dielectric coatings.

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.

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.

A Student-Made Microfluidic Device for Electrophoretic Separation of Food Dyes

ERIC Educational Resources Information Center

Teerasong, Saowapak; McClain, Robert L.

2011-01-01

We have developed an undergraduate laboratory activity to introduce students to microfluidics. In the activity, each student constructs their own microfluidic device using simple photolithographic techniques and then uses the device to separate a food dye mixture by electrophoresis. Dyes are used so that students are able to visually observe the…

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

High resolution laser beam induced current images under trichromatic laser radiation: approximation to the solar irradiation.

PubMed

Navas, F J; Alcántara, R; Fernández-Lorenzo, C; Martín-Calleja, J

2010-03-01

A laser beam induced current (LBIC) map of a photoactive surface is a very useful tool when it is necessary to study the spatial variability of properties such as photoconverter efficiency or factors connected with the recombination of carriers. Obtaining high spatial resolution LBIC maps involves irradiating the photoactive surface with a photonic beam with Gaussian power distribution and with a low dispersion coefficient. Laser emission fulfils these characteristics, but against it is the fact that it is highly monochromatic and therefore has a spectral distribution different to solar emissions. This work presents an instrumental system and procedure to obtain high spatial resolution LBIC maps in conditions approximating solar irradiation. The methodology developed consists of a trichromatic irradiation system based on three sources of laser excitation with emission in the red, green, and blue zones of the electromagnetic spectrum. The relative irradiation powers are determined by either solar spectrum distribution or Planck's emission formula which provides information approximate to the behavior of the system if it were under solar irradiation. In turn, an algorithm and a procedure have been developed to be able to form images based on the scans performed by the three lasers, providing information about the photoconverter efficiency of photovoltaic devices under the irradiation conditions used. This system has been checked with three photosensitive devices based on three different technologies: a commercial silicon photodiode, a commercial photoresistor, and a dye-sensitized solar cell. These devices make it possible to check how the superficial quantum efficiency has areas dependent upon the excitation wavelength while it has been possible to measure global incident photon-to-current efficiency values approximating those that would be obtained under irradiation conditions with sunlight.

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.

Polymer based plasmonic elements with dye molecules

NASA Astrophysics Data System (ADS)

Zhang, Douguo; Wang, Xiangxian; Chen, Yikai; Han, Lu; Wang, Pei; Ming, Hai

2012-11-01

Recently, dielectric loaded surface plasmons (SPs) elements are inducing highly interesting in the field of nanooptics, which are composed of dielectric nanostructures fabricated on a metallic thin film. This configuration will provide a route to novel integrated micro-optical devices and components combining photonics and electronics on the same chip. The advantages are easy fabrication, easy integration, and also the potential to realizing active plasmonic devices. In this talk, we will present our recent work in this field. Polymer (PMMA) nano-structures are fabricated on a silver film by the electron beam lithography (EBL) and laser interference lithography. These nano-structures are used to manipulate the behaviors of the SPs, such as converging, diverging, and guiding the propagation of SPs in subwavelength scale. Except for the pure PMMA nano-structures, dye materials (Rhodamine B, RhB) doped PMMA structures are also fabricated on the silver film. The RhB molecules will work as the active medium to excite the SPs or compensation the loss of SPs wave. The dye doped PMMA nanostructure provides a choice to realize active plasmonic elements, such as SPs Bragg gratings. On the other hand, the interaction between the fluorescence molecules and SPs will give rise to some new optical phenomena, such as directional fluorescence emission, anisotropic fluorescence emission. These polymer based plasmonic structures are investigated with a home-built leakage radiation microscopy (LRM).

Experimental study of cavity configurations for dye lasers pumped by a copper vapor laser

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

Tang Chaunshun; Sun Wei

1988-04-01

Four cavity configurations are considered for dye lasers pumped transversely by a CuBr laser at high pulse repetition frequencies. Their operating characteristics are compared. Optimum performance is found for a double-prism expander cavity equipped with a Littrow mounted grating. A single longitudinal mode lasing in the 598--640 nm range was achieved with a linewidth of 0.0012 nm and a conversion of efficiency of 7.5%, respectively. The amplified spontaneous emission was 1.5%.

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.

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…

Continuous-tone applications in digital hard-copy output devices

NASA Astrophysics Data System (ADS)

Saunders, Jeffrey C.

1990-11-01

Dye diffusion technology has made a recent entry into the hardcopy printer arena making it now possible to achieve near-photographic quality images from digital raster image data. Whereas the majority of low cost printers utilizing ink-jet, thermal wax, or dotmatrix technologies advertise high resolution printheads, the restrictions which dithering algorithms apply to these inherently binary printing systems force them to sacrifice spatial resolution capability for tone scale reproduction. Dye diffusion technology allows a fully continuous range of density at each pixel location thus preserving the full spatial resolution capability of the printhead; spatial resolution is not sacrificed for tone scale. This results in images whose quality is far superior to the ink-jet or wax-transfer products; image quality so high in fact, to the unaided eye, dye diffusion images are indistinguishable from their silver-halide counterparts. Eastman Kodak Co. offers a highly refined application of dye diffusion technology in the Kodak XL 7700 Digital Continuous Tone Printer and Kodak EKTATHERM media products. The XL . 7700 Printer represents a serious alternative to expensive laser-based film recorders for applications which require high quality image output from digital data files. This paper presents an explanation of dye diffusion printing, what distinguishes it from other technologies, sensitometric control and image quality parameters, and applications within the industry, particularly that of Airborne Reconnaissance and Remote Sensing.

Intracellular microlasers

NASA Astrophysics Data System (ADS)

Humar, Matjaž; Hyun Yun, Seok

2015-09-01

Optical microresonators, which confine light within a small cavity, are widely exploited for various applications ranging from the realization of lasers and nonlinear devices to biochemical and optomechanical sensing. Here we use microresonators and suitable optical gain materials inside biological cells to demonstrate various optical functions in vitro including lasing. We explore two distinct types of microresonator—soft and hard—that support whispering-gallery modes. Soft droplets formed by injecting oil or using natural lipid droplets support intracellular laser action. The laser spectra from oil-droplet microlasers can chart cytoplasmic internal stress (˜500 pN μm-2) and its dynamic fluctuations at a sensitivity of 20 pN μm-2 (20 Pa). In a second form, whispering-gallery modes within phagocytized polystyrene beads of different sizes enable individual tagging of thousands of cells easily and, in principle, a much larger number by multiplexing with different dyes.

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.

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.

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

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.

Single-step preparation of TiO2/MWCNT Nanohybrid materials by laser pyrolysis and application to efficient photovoltaic energy conversion.

PubMed

Wang, Jin; Lin, Yaochen; Pinault, Mathieu; Filoramo, Arianna; Fabert, Marc; Ratier, Bernard; Bouclé, Johann; Herlin-Boime, Nathalie

2015-01-14

This paper presents the continuous-flowand single-step synthesis of a TiO2/MWCNT (multiwall carbon nanotubes) nanohybrid material. The synthesis method allows achieving high coverage and intimate interface between the TiO2particles and MWCNTs, together with a highly homogeneous distribution of nanotubes within the oxide. Such materials used as active layer in theporous photoelectrode of solid-state dye-sensitized solar cells leads to a substantial performance improvement (20%) as compared to reference 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.

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.

Ultrastrong light-matter coupling in electrically doped microcavity organic light emitting diodes

NASA Astrophysics Data System (ADS)

Mazzeo, M.; Genco, A.; Gambino, S.; Ballarini, D.; Mangione, F.; Di Stefano, O.; Patanè, S.; Savasta, S.; Sanvitto, D.; Gigli, G.

2014-06-01

The coupling of the electromagnetic field with an electronic transition gives rise, for strong enough light-matter interactions, to hybrid states called exciton-polaritons. When the energy exchanged between light and matter becomes a significant fraction of the material transition energy an extreme optical regime called ultrastrong coupling (USC) is achieved. We report a microcavity embedded p-i-n monolithic organic light emitting diode working in USC, employing a thin film of squaraine dye as active layer. A normalized coupling ratio of 30% has been achieved at room temperature. These USC devices exhibit a dispersion-less angle-resolved electroluminescence that can be exploited for the realization of innovative optoelectronic devices. Our results may open the way towards electrically pumped polariton lasers.

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.

All optical controlled photonic integrated circuits using azo dye functionized sol-gel material

NASA Astrophysics Data System (ADS)

Ke, Xianjun

The main focus of this dissertation is development and characterization of all-optical controllable azo dye functionized sol gel material, demonstrating a PIC fabrication technique on glass substrate using such material, and exploration and feasibility demonstration of three PIC functional devices namely optical variable attenuator, optical switches, and optical tunable filters using the material. The realization of all the devices in this dissertation are based on one material: dye functionalized sol-gel material. A photochromic sol-gel material functionalized with azo dye was synthesized and characterized. It possesses a photochromic characteristic under the control of green laser beam illumination. The material characteristics suggest the possibility of a new promising material platform candidate for the fabrication of alloptical controlled photonic integrated circuits. As the first potential application of the dye functionalized sol-gel material, an alloptical variable attenuator was designed and demonstrated. The optical variable attenuation is achieved in Mach-Zehnder interferometric configuration through all-optical modulation of sol-gel waveguide phase shifters. A 2 x 2 optical switch based on multimode interference (MMI) waveguide structure is proposed in the dissertation. The schematic configuration of the optical switch consists of a cascade of two identical MMIs with two all-optical controlled phase shifters realized by using the photochromic sol-gel material. The cross or bar switch state of the optical switch is determined by the phase difference between the two sol-gel waveguide phase shifters. An all-optical tunable filter is designed and its feasibility demonstrated by using the sol-gel photochromic material. Except for the phase change demonstrated on sol-gel waveguide phase shifters, dynamic gratings were observed on sol-gel film when exposed to two interference beams. This reveals the possibility of realizing Bragg grating-based tunable filters. The schematic configuration of proposed tunable filters consists of a single straight waveguide embedded with a sol-gel waveguide. The wavelength tuning of the tunable filters is accomplished by varying the grating period.

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.

Variability of pulsed energy outputs from three dermatology lasers during multiple simulated treatments.

PubMed

Britton, Jason

2018-01-20

Dermatology laser treatments are undertaken at regional departments using lasers of different powers and wavelengths. In order to achieve good outcomes, there needs to be good consistency of laser output across different weeks as it is custom and practice to break down the treatments into individual fractions. Departments will also collect information from test patches to help decide on the most appropriate treatment parameters for individual patients. The objective of these experiments is to assess the variability of the energy outputs from a small number of lasers across multiple weeks at realistic parameters. The energy outputs from 3 lasers were measured at realistic treatment parameters using a thermopile detector across a period of 6 weeks. All lasers fired in single-pulse mode demonstrated good repeatability of energy output. In spite of one of the lasers being scheduled for a dye canister change in the next 2 weeks, there was good energy matching between the two devices with only a 4%-5% variation in measured energies. Based on the results presented, clinical outcomes should not be influenced by variability in the energy outputs of the dermatology lasers used as part of the treatment procedure. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

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.

Fabrication of Microcapsules for Dye-Doped Polymer-Dispersed Liquid Crystal-Based Smart Windows.

PubMed

Kim, Mingyun; Park, Kyun Joo; Seok, Seunghwan; Ok, Jong Min; Jung, Hee-Tae; Choe, Jaehoon; Kim, Do Hyun

2015-08-19

A dye-doped polymer-dispersed liquid crystal (PDLC) is an attractive material for application in smart windows. Smart windows using a PDLC can be operated simply and have a high contrast ratio compared to those of other devices that employed photochromic or thermochromic material. However, in conventional dye-doped PDLC methods, dye contamination can cause problems and has a limited degree of commercialization of electric smart windows. Here, we report on an approach to resolve dye-related problems by encapsulating the dye in monodispersed capsules. By encapsulation, a fabricated dye-doped PDLC had a contrast ratio of >120 at 600 nm. This fabrication method of encapsulating the dye in a core-shell structured microcapsule in a dye-doped PDLC device provides a practical platform for dye-doped PDLC-based smart windows.

A Novel Biomedical Device Utilizing Light Emitting Nano-Structures

NASA Technical Reports Server (NTRS)

Varaljay, Vanessa A.

2004-01-01

This paper will discuss the development of a novel biomedical detection device that will be used to detect microorganisms with the use of infrared fluorochrome polymers attached to antibodies in fluids such as water. The fluorochrome polymers emit light in the near inferred region (NIR), approximately 805 nm, when excited by an NIR laser at 778 nm. The device could remarkably change the way laboratory testing is done today. The testing process is usually performed on a time scale of days while our device will be able to detect microorganisms in minutes. This type of time efficient analysis is ideal for use aboard the International Space Station and the Space Shuttle (ISS/SS) and has many useful commercial applications, for instance at a water treatment plant and food processing plants. With more research and experimentation the testing might also one day be used to detect bacteria and viruses in complex fluids such as blood, which would revolutionize blood analysis as it is performed today. My contribution to the project has been to develop a process which will allow an antibody/fluorescent dye pair to be conjugated to a specific bacteria or virus and than to to be separated from a sample body of water for detection. The antibody being used in this experiment is anti beta galactosidase and its complement enzyme is beta galactosidase, a non harmful derivative of E. Coli. The anti beta galactosidase has been conjugated to the fluorochrome polymer, IRDye800, which emits at approximately 806 nm. The dye when excited by the NIR laser emits a signal which is detected by a spectrometer and then is read by state of the art computer software. The state-of-the-art process includes incubating the anti beta galactosidase and beta galactosidase in a phosphate buffer solution in a test tube, allowing the antibody to bind to specific sites on the enzyme. After the antibody is bound to the enzyme, it is centrifuged in specific filters that will allow free antibody to wash away and leave the antibody-enzyme complexes on top in solution for testing and analysis. This solution is pipetted into a cuvette, a special plastic test tube, which will then be excited by the laser. The signal read will tell US that an antibody is present and since it is bound to the enzyme, that the bacteria is also present.

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.

Efficient 7-J flashlamp-pumped dye laser at 500-nm wavelength

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

Everett, P.N.; Aldag, H.R.; Ehrlich, J.J.

1986-07-01

An existing transverse flow flashlamp-pumped dye laser capable of operation at 500 pps for extended periods of time has been modified and optimized for operation at 502 nm using coumarin 504. Energies of over 7 J/ pulse and efficiencies of over 1% have been demonstrated in single-shot operation. This has been achieved by using a spectral transfer dye in the flashlamp coolant to increase the useful output of the flashlamps. Flashlamps were tested at up to 400-J input per lamp for extended periods to develop lamp life data.

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.

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.

Contact-lens type of micromachined hydrogenated amorphous Si fluorescence detector coupled with microfluidic electrophoresis devices

NASA Astrophysics Data System (ADS)

Kamei, Toshihiro; Wada, Takehito

2006-09-01

A 5.8-μm-thick SiO2/Ta2O5 multilayer optical interference filter was monolithically integrated and micromachined on a hydrogenated amorphous Si (a-Si :H) pin photodiode to form a fluorescence detector. A microfluidic electrophoresis device was mounted on a detection platform comprising a fluorescence-collecting half-ball lens and the micromachined fluorescence detector. The central aperture of the fluorescence detector allows semiconductor laser light to pass up through the detector and to irradiate an electrophoretic separation channel. The limit of detection is as low as 7nM of the fluorescein solution, and high-speed DNA fragment sizing can be achieved with high separation efficiency. The micromachined a-Si :H fluorescence detector exhibits high sensitivity for practical fluorescent labeling dyes as well as integration flexibility on various substances, making it ideal for application to portable microfluidic bioanalysis devices.

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

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 .

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.

Spectroscopic detection of halogen bonding resolves dye regeneration in the dye-sensitized solar cell.

PubMed

Parlane, Fraser G L; Mustoe, Chantal; Kellett, Cameron W; Simon, Sarah J; Swords, Wesley B; Meyer, Gerald J; Kennepohl, Pierre; Berlinguette, Curtis P

2017-11-24

The interactions between a surface-adsorbed dye and a soluble redox-active electrolyte species in the dye-sensitized solar cell has a significant impact on the rate of regeneration of photo-oxidized dye molecules and open-circuit voltage of the device. Dyes must therefore be designed to encourage these interfacial interactions, but experimentally resolving how such weak interactions affect electron transfer is challenging. Herein, we use X-ray absorption spectroscopy to confirm halogen bonding can exist at the dye-electrolyte interface. Using a known series of triphenylamine-based dyes bearing halogen substituents geometrically positioned for reaction with halides in solution, halogen bonding was detected only in cases where brominated and iodinated dyes were photo-oxidized. This result implies that weak intermolecular interactions between photo-oxidized dyes and the electrolyte can impact device photovoltages. This result was unexpected considering the low concentration of oxidized dyes (less than 1 in 100,000) under full solar illumination.

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.

Synthesis and characterization of organic dyes with various electron-accepting substituents for p-type dye-sensitized solar cells.

PubMed

Weidelener, Martin; Powar, Satvasheel; Kast, Hannelore; Yu, Ze; Boix, Pablo P; Li, Chen; Müllen, Klaus; Geiger, Thomas; Kuster, Simon; Nüesch, Frank; Bach, Udo; Mishra, Amaresh; Bäuerle, Peter

2014-11-01

Four new donor-π-acceptor dyes differing in their acceptor group have been synthesized and employed as model systems to study the influence of the acceptor groups on the photophysical properties and in NiO-based p-type dye-sensitized solar cells. UV/Vis absorption spectra showed a broad range of absorption coverage with maxima between 331 and 653 nm. Redox potentials as well as HOMO and LUMO energies of the dyes were determined from cyclic voltammetry measurements and evaluated concerning their potential use as sensitizers in p-type dye-sensitized solar cells (p-DSCs). Quantum-chemical density functional theory calculations gave further insight into the frontier orbital distributions, which are relevant for the electronic processes in p-DSCs. In p-DSCs using an iodide/triiodide-based electrolyte, the polycyclic 9,10-dicyano-acenaphtho[1,2-b]quinoxaline (DCANQ) acceptor-containing dye gave the highest power conversion efficiency of 0.08%, which is comparable to that obtained with the perylenemonoimide (PMI)-containing dye. Interestingly, devices containing the DCANQ-based dye achieve a higher V(OC) of 163 mV compared to 158 mV for the PMI-containing dye. The result was further confirmed by impedance spectroscopic analysis showing higher recombination resistance and thus a lower recombination rate for devices containing the DCANQ dye than for PMI dye-based devices. However, the use of the strong electron-accepting tricyanofurane (TCF) group played a negative role in the device performance, yielding an efficiency of only 0.01% due to a low-lying LUMO energy level, thus resulting in an insufficient driving force for efficient dye regeneration. The results demonstrate that a careful molecular design with a proper choice of the acceptor unit is essential for development of sensitizers for p-DSCs. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optothermally actuated capillary burst valve

NASA Astrophysics Data System (ADS)

Eriksen, Johan; Bilenberg, Brian; Kristensen, Anders; Marie, Rodolphe

2017-04-01

We demonstrate the optothermal actuation of individual capillary burst valves in an all-polymer microfluidic device. The capillary burst valves are realised in a planar design by introducing a fluidic constriction in a microfluidic channel of constant depth. We show that a capillary burst valve can be burst by raising the temperature due to the temperature dependence of the fluid surface tension. We address individual valves by using a local heating platform based on a thin film of near infrared absorber dye embedded in the lid used to seal the microfluidic device [L. H. Thamdrup et al., Nano Lett. 10, 826-832 (2010)]. An individual valve is burst by focusing the laser in its vicinity. We demonstrate the capture of single polystyrene 7 μm beads in the constriction triggered by the bursting of the valve.

Other origins for the fluorescence modulation of single dye molecules in open-circuit and short-circuit devices.

PubMed

Teguh, Jefri S; Kurniawan, Michael; Wu, Xiangyang; Sum, Tze Chien; Yeow, Edwin K L

2013-01-07

Fluorescence intensity modulation of single Atto647N dye molecules in a short-circuit device and a defective device, caused by damaging an open-circuit device, is due to a variation in the excitation light focus as a result of the formation of an alternating electric current.

Active thermal fine laser tuning in a broad spectral range and optical properties of cholesteric liquid crystal.

PubMed

Jeong, Mi-Yun; Kwak, Keumcheol

2016-11-20

In this study, we achieved active fine laser tuning in a broad spectral range with dye-doped cholesteric liquid crystal wedge-type cells through temperature control. The spatial pitch gradient of each position of the wedge cell at room temperature was almost maintained after developing a temperature gradient. To achieve the maximum tuning range, the chiral dopant concentration, thickness, thickness gradient, and temperature gradient on the wedge cell should be matched properly. In order to understand the laser tuning mechanism for temperature change, we studied the temperature dependence of optical properties of the photonic bandgap of cholesteric liquid crystals. In our cholesteric liquid crystal samples, when temperature was increased, photonic bandgaps were shifted toward blue, while the width of the photonic bandgap was decreased, regardless of whether the helicity was left-handed or right-handed. This is mainly due to the combination of decreased refractive indices, higher molecular anisotropy of chiral molecules, and increased chiral molecular solubility. We envisage that this kind of study will prove useful in the development of practical active tunable CLC laser devices.

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.

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.

Single bead near-infrared random laser based on silica-gel infiltrated with Rhodamine 640

NASA Astrophysics Data System (ADS)

Moura, André L.; Barbosa-Silva, Renato; Dominguez, Christian T.; Pecoraro, Édison; Gomes, Anderson S. L.; de Araújo, Cid B.

2018-04-01

Photoluminescence properties of single bead silica-gel (SG) embedded with a laser-dye were studied aiming at the operation of near-infrared (NIR) Random Lasers (RLs). The operation of RLs in the NIR spectral region is especially important for biological applications since the optical radiation has deep tissue penetration with negligible damage. Since laser-dyes operating in the NIR have poor stability and are poor emitters, ethanol solutions of Rhodamine 640 (Rh640) infiltrated in SG beads were used. The Rh640 concentrations in ethanol varied from 10-5 to 10-2 M and the excitation at 532 nm was made by using a 7 ns pulsed laser. The proof-of-principle RL scheme herein presented was adopted in order to protect the dye-molecules from the environment and to favor formation of aggregates. The RL emission from ≈650 nm to 720 nm, beyond the typical Rh640 monomer and dimer wavelengths emissions range, was attributed to the trade-off between reabsorption and reemission processes along the light pathways inside the SG bead and the contribution of Rh640 aggregates.

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.

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.

Distributed feedback laser biosensor incorporating a titanium dioxide nanorod surface

NASA Astrophysics Data System (ADS)

Ge, Chun; Lu, Meng; Zhang, Wei; Cunningham, Brian T.

2010-04-01

A dielectric nanorod structure is used to enhance the label-free detection sensitivity of a vertically-emitting distributed feedback laser biosensor (DFBLB). The device is comprised of a replica molded plastic grating that is subsequently coated with a dye-doped polymer layer and a TiO2 nanorod layer produced by the glancing angle deposition technique. The DFBLB emission wavelength is modulated by the adsorption of biomolecules, whose greater dielectric permittivity with respect to the surrounding liquid media will increase the laser wavelength in proportion to the density of surface-adsorbed biomaterial. The nanorod layer provides greater surface area than a solid dielectric thin film, resulting in the ability to incorporate a greater number of molecules. The detection of a monolayer of protein polymer poly (Lys, Phe) is used to demonstrate that a 90 nm TiO2 nanorod structure improves the detection sensitivity by a factor of 6.6 compared to an identical sensor with a nonporous TiO2 surface.

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

Characterization of an optimized light source and comparison to pulsed dye laser for superficial and deep vessel clearance.

PubMed

Weiss, Robert A; Ross, E Victor; Tanghetti, Emil A; Vasily, David B; Childs, James J; Smirnov, Mikhail Z; Altshuler, Gregory B

2011-02-01

An arc lamp-based device providing optimized spectrum and pulse shape was characterized and compared with two pulsed dye laser (PDL) systems using a vascular phantom. Safety and effectiveness for facial telangiectasia are presented in clinical case studies. An optimized pulsed light source's (OPL) spectral and power output were characterized and compared with two 595 nm PDL devices. Purpuric threshold fluences were determined for the OPL and PDLs on Fitzpatrick type II normal skin. A vascular phantom comprising blood-filled quartz capillaries beneath porcine skin was treated by the devices at their respective purpuric threshold fluences for 3 ms pulse widths, while vessel temperatures were monitored with an infrared (IR) camera. Patients with Fitzpatrick skin types II-III received a split-face treatment with the OPL and a 595 nm PDL. The OPL provided a dual-band output spectrum from 500 to 670 nm and 850-1,200 nm, pulse widths from 3 to 100 ms, and fluences to 80 J/cm(2). The smooth output power measured during all pulse widths provides unambiguous vessel size selectivity. Percent energy in the near infra-red increased with decreasing output power from 45% to 60% and contributed 15-26% to heating of deep vessels, respectively. At purpuric threshold fluences the ratio of OPL to PDL vessel temperature rise was 1.7-2.8. OPL treatments of facial telangiectasia were well-tolerated by patients demonstrating significant improvements comparable to PDL with no downtime. Intense pulsed light (IPL) and PDL output pulse and spectral profiles are important for selective treatment of vessels in vascular lesions. The OPL's margin between purpuric threshold fluence and treatment fluence for deeper, larger vessels was greater than the corresponding margin with PDLs. The results warrant further comparison studies with IPLs and other PDLs. Copyright © 2011 Wiley-Liss, Inc.

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.

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

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.

Multi-wavelength emission through self-induced second-order wave-mixing processes from a Nd3+ doped crystalline powder random laser

NASA Astrophysics Data System (ADS)

Moura, André L.; Jerez, Vladimir; Maia, Lauro J. Q.; Gomes, Anderson S. L.; de Araújo, Cid B.

2015-09-01

Random lasers (RLs) based on neodymium ions (Nd3+) doped crystalline powders rely on multiple light scattering to sustain laser oscillation. Although Stokes and anti-Stokes Nd3+ RLs have been demonstrated, the optical gain obtained up to now was possibly not large enough to produce self-frequency conversion. Here we demonstrate self-frequency upconversion from Nd3+ doped YAl3(BO3)4 monocrystals excited at 806 nm, in resonance with the Nd3+ transition 4I9/2 → 4F5/2. Besides the observation of the RL emission at 1062 nm, self-converted second-harmonic at 531 nm, and self-sum-frequency generated emission at 459 nm due to the RL and the excitation laser at 806 nm, are reported. Additionally, second-harmonic of the excitation laser at 403 nm was generated. These results exemplify the first multi-wavelength source of radiation owing to nonlinear optical effect in a Nd3+ doped crystalline powder RL. Contrary to the RLs based on dyes, this multi-wavelength light source can be used in photonic devices due to the large durability of the gain medium.

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.

Dichroic Liquid Crystal Displays

NASA Astrophysics Data System (ADS)

Bahadur, Birendra

The following sections are included: * INTRODUCTION * DICHROIC DYES * Chemical Structure * Chemical and Photochemical Stability * THEORETICAL MODELLING * DEFECTS CAUSED BY PROLONGED LIGHT IRRADIATION * CHEMICAL STRUCTURE AND PHOTOSTABILITY * OTHER PARAMETERS AFFECTING PHOTOSTABILITY * CELL PREPARATION * DICHROIC PARAMETERS AND THEIR MEASUREMENTS * Order Parameter and Dichroic Ratio Of Dyes * Absorbance, Order Parameter and Dichroic Ratio Measurements * IMPACT OF DYE STRUCTURE AND LIQUID CRYSTAL HOST ON PHYSICAL PROPERTIES OF A DICHROIC MIXTURE * Order Parameter and Dichroic Ratio * EFFECT OF LENGTH OF DICHROIC DYES ON THE ORDER PARAMETER * EFFECT OF THE BREADTH OF DYE ON THE ORDER PARAMETER * EFFECT OF THE HOST ON THE ORDER PARAMETER * TEMPERATURE VARIATION OF THE ORDER PARAMETER OF DYES IN A LIQUID CRYSTAL HOST * IMPACT OF DYE CONCENTRATION ON THE ORDER PARAMETER * Temperature Range * Viscosity * Dielectric Constant and Anisotropy * Refractive Indices and Birefringence * solubility43,153-156 * Absorption Wavelength and Auxochromic Groups * Molecular Engineering of Dichroic Dyes * OPTICAL, ELECTRO-OPTICAL AND LIFE PARAMETERS * Colour And CIE Colour space120,160-166 * CIE 1931 COLOUR SPACE * CIE 1976 CHROMATICITY DIAGRAM * CIE UNIFORM COLOUR SPACES & COLOUR DIFFERENCE FORMULAE120,160-166 * Electro-Optical Parameters120 * LUMINANCE * CONTRAST AND CONTRAST RATIO * SWITCHING SPEED * Life Parameters and Failure Modes * DICHROIC MIXTURE FORMULATION * Monochrome Mixture * Black Mixture * ACHROMATIC BLACK MIXTURE FOR HEILMEIER DISPLAYS * Effect of Illuminant on Display Colour * Colour of the Field-On State * Effect of Dye Linewidth * Optimum Centroid Wavelengths * Effect of Dye Concentration * Mixture Formulation Using More Than Three Dyes * ACHROMATIC MIXTURE FOR WHITE-TAYLOR TYPE DISPLAYS * HEILMEIER DISPLAYS * Theoretical Modelling * Threshold Characteristic * Effects of Dye Concentration on Electro-optical Parameters * Effect of Cholesteric Doping * Effect of Alignment * Effect of Thickness * Impact of Order Parameter * Impact of the Host * Impact of Polarizer * Colour Applications * Multiplexing * QUARTER WAVE PLATE DICHROIC DISPLAYS * Operational Principle and Display Configuration11-13 * Electro-Optical Performance * DYE-DOPED TN DISPLAYS * Threshold Characteristic, Contrast Ratio and Switching Speed * PHASE CHANGE EFFECT DICHROIC LCDs * Theoretical Background * Threshold Characteristic and Molecular Orientation * MOLECULAR ORIENTATION DURING FIELD-INDUCED PHASE TRANSITION WITH HOMOGENEOUS WALL ALIGNMENT * MOLECULAR ORIENTATION DURING FIELD-INDUCED PHASE TRANSITION WITH HOMEOTROPIC WALL ALIGNMENT * Contrast Ratio, Transmission, Brightness and Switching Speed3,7,10,198-214 * Memory or Reminiscent Contrast * Electro-optical Performance vs. Temperature * Multiplexing Phase Change Dichroic LCDs * DOUBLE CELL DICHROIC LCDs3,9,14-17,232-234 * Double Cell Nematic Dichroic LCD3,8,9,14,15,233 * Double Cell One Pitch Cholesteric LCD16,17 * Double Cell Phase Change Dichroic LCD214,232 * POSITIVE MODE DICHROIC LCDS3,8,9 * Positive Mode Heilmeier Cells3,8,9,43,77,78,235-238 * USING PLEOCHROIC DYES3,8,9,43,235-238 * USING NEGATIVE DICHROIC DYES3,8,9,63,77,78156 * DUAL FREQUENCY ADDRESSED DICHROIC DISPLAYS75,238 * Positive Mode Dichroic LCDs Using λ/4 Plate * Positive Mode Double Cell Dichroic LCD * Positive Mode Dichroic LCDs Using Special Electrode patterns7,8,239-241 * Positive Mode Phase Change Dichroic LCDs3,8,9,230,243-248 * Dichroic LCDs Using an Admixture of Pleochroic and Negative Dichroic Dyes78,118 * SUPERTWIST DICHROIC EFFECT (SDE) DISPLAYS21-23 * FERROELECTRIC DICHROIC LCDs24-27 * Devices Using A Single Polarizer * Devices Using No Polarizer24-27 * POLYMER DISPERSED DICHROIC LCDs28-30,252-259 * DICHROIC POLYMER LIQUID CRYSTAL DISPLAYS * Heilmeier Type Displays * Guest-Host Cell Using an Admixture Of L.C. Polymer and Low Molecular Weight Liquid Crysta As Host * Polymeric Ferroelectric Dichroic LCDs * SMECTIC A DICHROIC LCDs * Laser Addressed Dichroic SA Displays * Thermally and Electrically Addressed Dichroic SA Displays * FLUORESCENT DICHROIC LCDs * ACKNOWLEDGEMENTS * REFERENCES

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.

Laser use and safety.

PubMed

1992-09-01

This Guidance Article is an update of an article published in a special issue of Health Devices entitled "Lasers in Medicine--An Introduction" (13[8], June 1984). Although surgical lasers have a good overall safety record, they do expose patients, physicians, and other clinical staff to serious risks. Laser hazards can cause injury, disability, or even death: hospital staff have been burned by misdirected laser beams, technicians and maintenance personnel have received eye injuries while working on lasers and have been exposed to hazardous chemicals while changing laser dyes, and patients have died from injuries resulting from fires ignited by laser energy. Laser accidents most commonly result from misdirection of the laser beam. Direct or reflected radiation can burn skin, hair, or, more seriously, the cornea or retina, causing permanent damage. Misdirected laser energy can also cause ignition of surgical drapes, tracheal tubes, or the patient's hair. Also, a frequent by-product of laser-tissue interactions is laser plume, or smoke. Its acrid smell and particulate matter irritate the eyes, nose, and lungs and cause nausea; it is also a suspected vector for transmitting infectious materials, such as the human papilloma virus (HPV) associated with condyloma (a wartlike lesion) and cervical cancer. The risks are not limited to patients and those directly involved in using and maintaining lasers. Many laser procedures are performed in areas outside the controlled environment of the surgical suite; patients in a waiting area or even passersby could conceivably walk into an accessible laser treatment room, such as a doctor's office, and inadvertently be exposed to a direct or reflected beam.(ABSTRACT TRUNCATED AT 250 WORDS)

Step-by-Step Heating of Dye Solution for Efficient Solar Energy Harvesting in Dye-Sensitized Solar Cells

NASA Astrophysics Data System (ADS)

Shah, Syed Afaq Ali; Sayyad, Muhammad Hassan; Abdulkarim, Salem; Qiao, Qiquan

2018-05-01

A step-by-step heat treatment was applied to ruthenium-based N719 dye solution for its potential application in dye-sensitized solar cells (DSSCs). The effects were analyzed and compared with standard untreated devices. A significant increase in short circuit current density was observed by employing a step-by-step heating method for dye solution in DSSCs. This increase of J sc is attributed to the enhancement in dye adsorption by the surface of the semiconductor and the higher number of charge carriers generated. DSSCs fabricated by a heated dye solution have achieved an overall power conversion efficiency of 8.41% which is significantly higher than the efficiency of 7.31% achieved with DSSCs fabricated without heated dye. Electrochemical impedance spectroscopy and capacitance voltage studies were performed to understand the better performance of the device fabricated with heated dye. Furthermore, transient photocurrent and transient photovoltage measurements were also performed to gain an insight into interfacial charge carrier recombinations.

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.

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

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.

Nonlinear optical effects in organic microstructures

NASA Astrophysics Data System (ADS)

Novikov, Vladimir B.; Mamonov, Evgeniy A.; Kopylov, Denis A.; Mitetelo, Nikolai V.; Venkatakrishnarao, D.; Narayana, YSLV; Chandrasekar, R.; Murzina, Tatiana V.

2017-05-01

Organic microstructures attract much attention due to their unique properties originating from the design of their shape and optical parameters. In this work we discuss the linear, second- and third-order nonlinear optical effects in arrays and in individual organic microstructures composed by self-assembling technique and formed randomly on top of a solid substrate. The structures under study consist of micro-spheres, -hemispheres or -frustums made of red laser dye and reveal an intense fluorescence (FL) in the visible spectral range. Importantly, that due to a high value of the refractive index and confined geometry, such micro-structures support the excitation of whispering gallery modes (WGM), which brings about strong and spectrally-selected light localization. We show that an amplification of the nonlinear optical effects is observed for these structures as compared to a homogeneous dye film of similar composition. The obtained data are in agreement with the results of the FDTD calculations performed for the structures of different dimensions. Perspectives of application of such type of organic nonlinear microresonators in optical devices are discussed.

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.

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.

Effect of Donor Strength and Bulk on Thieno[3,4-b]-pyrazine-Based Panchromatic Dyes in Dye-Sensitized Solar Cells.

PubMed

Liyanage, Nalaka P; Cheema, Hammad; Baumann, Alexandra R; Zylstra, Alexa R; Delcamp, Jared H

2017-06-22

Near-infrared-absorbing organic dyes are critically needed in dye-sensitized solar cells (DSCs). Thieno[3,4-b]pyrazine (TPz) based dyes can access the NIR spectral region and show power conversion efficiencies (PCEs) of up to 8.1 % with sunlight being converted at wavelengths up to 800 nm for 17.6 mA cm -2 of photocurrent in a co-sensitized DSC device. Precisely controlling dye excited-state energies is critical for good performances in NIR DSCs. Strategies to control TPz dye energetics with stronger donor groups and TPz substituent choice are evaluated here. Additionally, donor size influence versus dye loading on TPz dyes is analyzed with respect to the TiO 2 surface protection designed to prevent recombination of electrons in TiO 2 with the redox shuttle. Importantly, the dyes evaluated were demonstrated to work well with low Li + concentration electrolytes, with iodine and cobalt redox shuttle systems, and efficiently as part of co-sensitized devices. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Safety approaches for high power modular laser operation

NASA Astrophysics Data System (ADS)

Handren, R. T.

1993-03-01

Approximately 20 years ago, a program was initiated at the Lawrence Livermore National Laboratory (LLNL) to study the feasibility of using lasers to separate isotopes of uranium and other materials. Of particular interest was the development of a uranium enrichment method for the production of commercial nuclear power reactor fuel to replace current more expensive methods. The Uranium Atomic Vapor Laser Isotope Separation (U-AVLIS) Program progressed to the point where a plant-scale facility to demonstrate commercial feasibility was built and is being tested. The U-AVLIS Program uses copper vapor lasers which pump frequency selective dye lasers to photoionize uranium vapor produced by an electron beam. The selectively ionized isotopes are electrostatically collected. The copper lasers are arranged in oscillator/amplifier chains. The current configuration consists of 12 chains, each with a nominal output of 800 W for a system output in excess of 9 kW. The system requirements are for continuous operation (24 h a day, 7 days a week) and high availability. To meet these requirements, the lasers are designed in a modular form allowing for rapid change-out of the lasers requiring maintenance. Since beginning operation in early 1985, the copper lasers have accumulated over 2 million unit hours at a greater than 90% availability. The dye laser system provides approximately 2.5 kW average power in the visible wavelength range. This large-scale laser system has many safety considerations, including high-power laser beams, high voltage, and large quantities (approximately 3000 gal) of ethanol dye solutions. The Laboratory's safety policy requires that safety controls be designed into any process, equipment, or apparatus in the form of engineering controls. Administrative controls further reduce the risk to an acceptable level. Selected examples of engineering and administrative controls currently being used in the U-AVLIS Program are described.

Matrix-assisted laser desorption/ionization mass spectrometric analysis of poly(3,4-ethylenedioxythiophene) in solid-state dye-sensitized solar cells: comparison of in situ photoelectrochemical polymerization in aqueous micellar and organic media.

PubMed

Zhang, Jinbao; Ellis, Hanna; Yang, Lei; Johansson, Erik M J; Boschloo, Gerrit; Vlachopoulos, Nick; Hagfeldt, Anders; Bergquist, Jonas; Shevchenko, Denys

2015-04-07

Solid-state dye-sensitized solar cells (sDSCs) are devoid of such issues as electrolyte evaporation or leakage and electrode corrosion, which are typical for traditional liquid electrolyte-based DSCs. Poly(3,4-ethylenedioxythiophene) (PEDOT) is one of the most popular and efficient p-type conducting polymers that are used in sDSCs as a solid-state hole-transporting material. The most convenient way to deposit this insoluble polymer into the dye-sensitized mesoporous working electrode is in situ photoelectrochemical polymerization. Apparently, the structure and the physicochemical properties of the generated conducting polymer, which determine the photovoltaic performance of the corresponding solar cell, can be significantly affected by the preparation conditions. Therefore, a simple and fast analytical method that can reveal information on polymer chain length, possible chemical modifications, and impurities is strongly required for the rapid development of efficient solar energy-converting devices. In this contribution, we applied matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) for the analysis of PEDOT directly on sDSCs. It was found that the PEDOT generated in aqueous micellar medium possesses relatively shorter polymeric chains than the PEDOT deposited from an organic medium. Furthermore, the micellar electrolyte promotes a transformation of one of the thiophene terminal units to thiophenone. The introduction of a carbonyl group into the PEDOT molecule impedes the growth of the polymer chain and reduces the conductivity of the final polymer film. Both the simplicity of sample preparation (only application of the organic matrix onto the solar cell is needed) and the rapidity of analysis hold the promise of making MALDI MS an essential tool for the physicochemical characterization of conducting polymer-based sDSCs.

Intraluminal tissue welding for anastomosis

DOEpatents

Glinsky, M.; London, R.; Zimmerman, G.; Jacques, S.

1998-10-27

A method and device are provided for performing intraluminal tissue welding for anastomosis of a hollow organ. A retractable catheter assembly is delivered through the hollow organ and consists of a catheter connected to an optical fiber, an inflatable balloon, and a biocompatible patch mounted on the balloon. The disconnected ends of the hollow organ are brought together on the catheter assembly, and upon inflation of the balloon, the free ends are held together on the balloon to form a continuous channel while the patch is deployed against the inner wall of the hollow organ. The ends are joined or ``welded`` using laser radiation transmitted through the optical fiber to the patch. A thin layer of a light-absorbing dye on the patch can provide a target for welding. The patch may also contain a bonding agent to strengthen the bond. The laser radiation delivered has a pulse profile to minimize tissue damage. 8 figs.

Intraluminal tissue welding for anastomosis

DOEpatents

Glinsky, Michael; London, Richard; Zimmerman, George; Jacques, Steven

1998-10-27

A method and device are provided for performing intraluminal tissue welding for anastomosis of a hollow organ. A retractable catheter assembly is delivered through the hollow organ and consists of a catheter connected to an optical fiber, an inflatable balloon, and a biocompatible patch mounted on the balloon. The disconnected ends of the hollow organ are brought together on the catheter assembly, and upon inflation of the balloon, the free ends are held together on the balloon to form a continuous channel while the patch is deployed against the inner wall of the hollow organ. The ends are joined or "welded" using laser radiation transmitted through the optical fiber to the patch. A thin layer of a light-absorbing dye on the patch can provide a target for welding. The patch may also contain a bonding agent to strengthen the bond. The laser radiation delivered has a pulse profile to minimize tissue damage.

Progress Towards Spectroscopic Diagnostics of Plasma Parameters and Neutral Dynamics in Helicon Plasmas

NASA Astrophysics Data System (ADS)

Green, Jonathan; Schmitz, Oliver; Severn, Greg; van Ruremonde, Lars; Winters, Victoria

2017-10-01

The MARIA device at the UW-Madison is used primarily to investigate the dynamics and fueling of neutral particles in helicon discharges. A new systematic method is in development to measure key plasma and neutral particle parameters by spectroscopic methods. The setup relies on spectroscopic line ratios for investigating basic plasma parameters and extrapolation to other states using a collisional radiative model. Active pumping using a Nd:YAG pumped dye laser is used to benchmark and correct the underlying atomic data for the collisional radiative model. First results show a matching linear dependence between electron density and laser induced fluorescence on the magnetic field above 500G. This linear dependence agrees with the helicon dispersion relation and implies MARIA can reliably support the helicon mode and support future measurements. This work was funded by the NSF CAREER award PHY-1455210.

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

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.

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.

Compact ultrafast semiconductor disk laser: targeting GFP based nonlinear applications in living organisms

PubMed Central

Aviles-Espinosa, Rodrigo; Filippidis, George; Hamilton, Craig; Malcolm, Graeme; Weingarten, Kurt J.; Südmeyer, Thomas; Barbarin, Yohan; Keller, Ursula; Santos, Susana I.C.O; Artigas, David; Loza-Alvarez, Pablo

2011-01-01

We present a portable ultrafast Semiconductor Disk Laser (SDL) (or vertical extended cavity surface emitting laser—VECSELs), to be used for nonlinear microscopy. The SDL is modelocked using a quantum-dot semiconductor saturable absorber mirror (SESAM), delivering an average output power of 287 mW, with 1.5 ps pulses at 500 MHz and a central wavelength of 965 nm. Specifically, despite the fact of having long pulses and high repetition rates, we demonstrate the potential of this laser for Two-Photon Excited Fluorescence (TPEF) imaging of in vivo Caenorhabditis elegans (C. elegans) expressing Green Fluorescent Protein (GFP) in a set of neuronal processes and cell bodies. Efficient TPEF imaging is achieved due to the fact that this wavelength matches the peak of the two-photon action cross section of this widely used fluorescent marker. The SDL extended versatility is shown by presenting Second Harmonic Generation images of pharynx, uterus, body wall muscles and its potential to be used to excite other different commercial dyes. Importantly this non-expensive, turn-key, compact laser system could be used as a platform to develop portable nonlinear bio-imaging devices. PMID:21483599

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.

Development of New Photovoltaic Devices Based on Multi Wall Carbon Nanotubes and Nanoparticles

DTIC Science & Technology

2013-03-01

response is registered in all the photon spectral range studied. The new kind of Graetzel-like solar cell device was built without dye and TiO2 , showing...response is registered in all the photon spectral range studied. - The new kind of Graetzel (DSSC, Dye Synthesized Solar Cell ) built without Dye and TiO2 ...an IPCE up to 20%. 15. SUBJECT TERMS EOARD, organic solar cells , photovoltaics, carbon nanotubes 16. SECURITY CLASSIFICATION

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.

Regenerable Photovoltaic Devices with a Hydrogel-Embedded Microvascular Network

PubMed Central

Koo, Hyung-Jun; Velev, Orlin D.

2013-01-01

Light-driven degradation of photoactive molecules could be one of the major obstacles to stable long term operation of organic dye-based solar light harvesting devices. One solution to this problem may be mimicking the regeneration functionality of a plant leaf. We report an organic dye photovoltaic system that has been endowed with such microfluidic regeneration functionality. A hydrogel medium with embedded channels allows rapid and uniform supply of photoactive reagents by a convection-diffusion mechanism. A washing-activation cycle enables reliable replacement of the organic component in a dye-sensitized photovoltaic system. Repetitive restoration of photovoltaic performance after intensive device degradation is demonstrated. PMID:23912814

Discovery of black dye crystal structure polymorphs: Implications for dye conformational variation in dye-sensitized solar cells

DOE PAGES

Cole, Jacqueline M.; Low, Kian Sing; Gong, Yun

2015-11-24

Here, we present the discovery of a new crystal structure polymorph (1) and pseudopolymorph (2) of the Black Dye, one of the world’s leading dyes for dye-sensitized solar cells, DSSCs (10.4% device performance efficiency). This reveals that Black Dye molecules can adopt multiple low-energy conformers. This is significant since it challenges existing models of the Black Dye···TiO 2 adsorption process that renders a DSSC working electrode; these have assumed a single molecular conformation that refers to the previously reported Black Dye crystal structure (3). The marked structural differences observed between 1, 2, and 3 make the need for modeling multiplemore » conformations more acute. Additionally, the ordered form of the Black Dye (1) provides a more appropriate depiction of its anionic structure, especially regarding its anchoring group and NCS bonding descriptions. The tendency toward NCS ligand isomerism, evidenced via the disordered form 2, has consequences for electron injection and electron recombination in Black Dye embedded DSSC devices. Dyes 2 and 3 differ primarily by the absence or presence of a solvent of crystallization, respectively; solvent environment effects on the dye are thereby elucidated. This discovery of multiple Black Dye conformers from diffraction, with atomic-level definition, complements recently reported nanoscopic evidence for multiple dye conformations existing at a dye···TiO 2 interface, for a chemically similar DSSC dye; those results emanated from imaging and spectroscopy, but were unresolved at the submolecular level. Taken together, these findings lead to the general notion that multiple dye conformations should be explicitly considered when modeling dye···TiO 2 interfaces in DSSCs, at least for ruthenium-based dye complexes.« less

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.

Design of intelligent mesoscale periodic array structures utilizing smart hydrogel

NASA Technical Reports Server (NTRS)

Sunkara, H. B.; Penn, B. G.; Frazier, D. O.; Weissman, J. M.; Asher, S. A.

1996-01-01

Mesoscale Periodic Array Structures (MPAS, also known as crystalline colloidal arrays), composed of aqueous or nonaqueous dispersions of self-assembled submicron colloidal spheres are emerging toward the development of advanced optical devices for technological applications. This is because of their unique optical diffraction properties and the ease with which these intriguing properties can be modulated experimentally. Moreover our recent advancements in this area which include 'locking' the liquid MPAS into solid or semisolid polymer matrices for greater stability with longer life span, and incorporation of CdS quantum dots and laser dyes into colloidal spheres to obtain nonlinear optical (NLO) responses further corroborate the use of MPAS in optical technology. Our long term goal is fabrication of all-optical and electro-optical devices such as spatial light modulators for optical signal processing and flat panel display devices by utilizing intelligent nonlinear periodic array structural materials. Here we show further progress in the design of novel linear MPAS which have the ability to sense and respond to an external source such as temperature. This is achieved by combining the self-assembly properties of polymer colloidal spheres and thermoshrinking properties of smart polymer gels. At selected temperatures the periodic array efficiently Bragg diffracts light and transmits most of the light at other temperatures. Hence these intelligent systems are of potential use as fixed notch filters optical switches or limiters to protect delicate optical sensors from high intensity laser radiation.

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.

Performance of dye sensitized solar cells (DSSC) using Syngonium Podophyllum Schott as natural dye and counter electrode

NASA Astrophysics Data System (ADS)

Oktariza, Lingga Ghufira; Yuliarto, Brian; Suyatman

2018-05-01

The extraction of chlorophyll pigment of Syngonium podophyllum Schott leaves which is used as natural dyes in this DSSC devices. The use of dye from nature with its simple production process is very effective to reduce DSSC production cost. Besides being used as a natural dye, chlorophyll can also be used as an alternative counter electrode. Chlorophyll that is used as a counter electrode has been through chemical activation and carbonization processes. The characterization were done using Uv-Vis, Cyclic Voltametry and DSSC device under solar simulator. Characterization of chlorophyll absorbance using UV-Vis has resulted in typical absorbance peak at visible light wavelength of 447 nm and 666 nm. The Tauc equation analysis of the Uv-Vis characterization showed 1.91 eV energy gap of chlorophyll. Chlorophyll carbonized dye is used as an alternative to Pt counter electrode. Carbonized chlorophyll dye resulted in lower conversion efficiency of 0.308% with HSE electrolyte.

Insights into the Mechanism of a Covalently Linked Organic Dye-Cobaloxime Catalyst System for Dye-Sensitized Solar Fuel Devices.

PubMed

Pati, Palas Baran; Zhang, Lei; Philippe, Bertrand; Fernández-Terán, Ricardo; Ahmadi, Sareh; Tian, Lei; Rensmo, Håkan; Hammarström, Leif; Tian, Haining

2017-06-09

A covalently linked organic dye-cobaloxime catalyst system based on mesoporous NiO is synthesized by a facile click reaction for mechanistic studies and application in a dye-sensitized solar fuel device. The system is systematically investigated by photoelectrochemical measurements, density functional theory, time-resolved fluorescence, transient absorption spectroscopy, and photoelectron spectroscopy. The results show that irradiation of the dye-catalyst on NiO leads to ultrafast hole injection into NiO from the excited dye, followed by a fast electron transfer process to reduce the catalyst. Moreover, the dye adopts different structures with different excited state energies, and excitation energy transfer occurs between neighboring molecules on the semiconductor surface. The photoelectrochemical experiments also show hydrogen production by this system. The axial chloride ligands of the catalyst are released during photocatalysis to create the active sites for proton reduction. A working mechanism of the dye-catalyst system on the photocathode is proposed on the basis of this study. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

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.

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

PubMed

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

2012-07-01

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

The fluorescence theatre: a cost-effective device using theatre gels for fluorescent protein and dye screening.

PubMed

Heil, John R; Nordeste, Ricardo F; Charles, Trevor C

2011-04-01

Here we report a simple cost-effective device for screening colonies on plates for expression of the monomeric red fluorescent protein mRFP1 and the fluorescent dye Nile red. This device can be built from any simple light source, in our case a Quebec Colony Counter, and cost-effective theatre gels. The device can be assembled in as little as 20 min, and it produces excellent results when screening a large number of colonies.

Emission characteristics in solution-processed asymmetric white alternating current field-induced polymer electroluminescent devices

NASA Astrophysics Data System (ADS)

Chen, Yonghua; Xia, Yingdong; Smith, Gregory M.; Gu, Yu; Yang, Chuluo; Carroll, David L.

2013-01-01

In this work, the emission characteristics of a blue fluorophor poly(9, 9-dioctylfluorene) (PFO) combined with a red emitting dye: Bis(2-methyl-dibenzo[f,h]quinoxaline)(acetylacetonate)iridium (III) [Ir(MDQ)2(acac)], are examined in two different asymmetric white alternating current field-induced polymer electroluminescent (FIPEL) device structures. The first is a top-contact device in which the triplet transfer is observed resulting in the concentration-dependence of the emission similar to the standard organic light-emitting diode (OLED) structure. The second is a bottom-contact device which, however, exhibits concentration-independence of emission. Specifically, both dye emission and polymer emission are found for the concentrations as high as 10% by weight of the dye in the emitter. We attribute this to the significant different carrier injection characteristics of the two FIPEL devices. Our results suggest a simple and easy way to realize high-quality white emission.

Variation in Optoelectronic Properties of Azo Dye-Sensitized TiO 2 Semiconductor Interfaces with Different Adsorption Anchors: Carboxylate, Sulfonate, Hydroxyl and Pyridyl Groups

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

Zhang, Lei; Cole, Jacqueline M.; Dai, Chencheng

2014-05-28

The optoelectronic properties of four azo dye-sensitized TiO2 interfaces are systematically studied as a function of a changing dye anchoring group: carboxylate, sulfonate, hydroxyl, and pyridyl. The variation in optoelectronic properties of the free dyes and those in dye/TiO 2 nanocomposites are studied both experimentally and computationally, in the context of prospective dye-sensitized solar cell (DSSC) applications. Experimental UV/vis absorption spectroscopy, cyclic voltammetry, and DSSC device performance testing reveal a strong dependence on the nature of the anchor of the optoelectronic properties of these dyes, both in solution and as dye/TiO2 nanocomposites. First-principles calculations on both an isolated dye/TiO2 clustermore » model (using localized basis sets) and each dye modeled onto the surface of a 2D periodic TiO2 nanostructure (using plane wave basis sets) are presented. Detailed examination of these experimental and computational results, in terms of light harvesting, electron conversion and photovoltaic device performance characteristics, indicates that carboxylate is the best anchoring group, and hydroxyl is the worst, whereas sulfonate and pyridyl groups exhibit competing potential. Different sensitization solvents are found to affect critically the extent of dye adsorption achieved in the dye-sensitization of the TiO2 semiconductor, especially where the anchor is a pyridyl group.« less

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.

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.

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.

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).

Surface plasmon-mediated energy transfer of electrically-pumped excitons

DOEpatents

An, Kwang Hyup; Shtein, Max; Pipe, Kevin P.

2015-08-25

An electrically pumped light emitting device emits a light when powered by a power source. The light emitting device includes a first electrode, a second electrode including an outer surface, and at least one active organic semiconductor disposed between the first and second electrodes. The device also includes a dye adjacent the outer surface of the second electrode such that the second electrode is disposed between the dye and the active organic semiconductor. A voltage applied by the power source across the first and second electrodes causes energy to couple from decaying dipoles into surface plasmon polariton modes, which then evanescently couple to the dye to cause the light to be emitted.

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.

Ultraviolet /UV/ sensitive phosphors for silicon imaging detectors

NASA Technical Reports Server (NTRS)

Viehmann, W.; Cowens, M. W.; Butner, C. L.

1981-01-01

The fluorescence properties of UV sensitive organic phosphors and the radiometric properties of phosphor coated silicon detectors in the VUV, UV, and visible wavelengths are described. With evaporated films of coronene and liumogen, effective quantum efficiencies of up to 20% have been achieved on silicon photodiodes in the vacuum UV. With thin films of methylmethacrylate (acrylic), which are doped with organic laser dyes and deposited from solution, detector quantum efficiencies of the order of 15% for wavelengths of 120-165 nm and of 40% for wavelengths above 190 nm have been obtained. The phosphor coatings also act as antireflection coatings and thereby enhance the response of coated devices throughout the visible and near IR.

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.

Photovoltaic studies of Dye Sensitized Solar cells Fabricated from Microwave Exposed Photo anodes

NASA Astrophysics Data System (ADS)

Ramachandran, Anju; Sreekala, C. O.; Sreelatha, K. S.; Jinchu, I.

2018-02-01

The configuration of Dye Sensitized solar cells (DSSC), consists of sintered nanoparticle titanium dioxide film, dyes, electrolyte and counter electrodes. Upon the absorption of photons by the dye molecules, excitons are generated, subsequently electrons are injected into the TiO2 photoanode. Afterward the electrons injected into the TiO2 photoanode, to produce photocurrent, scavenged by redox couple, and the hole transport to the photo cathode. The power conversion efficiency of the device depends on the amount of dye adsorbed by the photoanode. This paper explores in enhancing the efficiency of the device by controlled microwave exposure. With same exposure time, the photoanode is exposed at three different frequencies. SEM analysis is carried out to find the porosity of the photoanode on exposure. Current density is found to have an effect on microwave exposure.

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.

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

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.

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

Co-sensitization of natural dyes for improved efficiency in dye-sensitized solar cell application

NASA Astrophysics Data System (ADS)

Kumar, K. Ashok; Subalakshmi, K.; Senthilselvan, J.

2016-05-01

In this paper, a new approach of co-sensitized DSSC based on natural dyes is investigated to explore the possible way to improve the power conversion efficiency. To realize this purpose 10 DSSC devices were fabricated using mono-sensitization and co-sensitization of ethanolic extracts of natural dye sensitizers obtained from Cactus fruit, Jambolana fruit, Curcumin and Bermuda grass. The optical absorption spectrum of the mono and hybrid dye extracts were studied by UV-Visible absorption spectrum. It shows the characteristic absorption peaks in visible region corresponds to the presence of natural pigments of anthocyanin, betacyanin and chlorophylls. Absorption spectrum of hybrid dyes reveals a wide absorption band in visible region with improved extinction co-efficient and it is favorable for increased light harvesting nature. The power conversion efficiency of DSSC devices were calculated using J-V curve and the maximum efficiency achieved in the present work is noted to be ~0.61% for Cactus-Bermuda co-sensitized DSSC.

Can nitro groups really anchor onto TiO 2? Case study of dye-to-TiO 2 adsorption using azo dyes with NO 2 substituents

DOE PAGES

Zhang, Lei; Cole, Jacqueline M.

2016-06-21

The nitro group has recently been suggested as a new type of anchor for dye-sensitized solar cells (DSSCs) and has shown promising optoelectronic properties. Considering the excellent electron withdrawing ability of the nitro group and wider materials selection brought about by this substituent, it is helpful to evaluate the interfacial structures and photophysics of more organic dyes where NO 2 poses as the dye-to-TiO 2 anchor. A computational study on a family of azo dyes bearing a nitro group is presented in this paper, where the effect of certain side groups on their optical properties is examined. Both isolated dyemore » molecules and dye/TiO 2 nanocomposites are studied via density functional theory and time-dependent density functional theory, with complementary experimental UV/vis absorption spectroscopy and photovoltaic device testing. Results demonstrate that these nitro-containing dyes prefer a monodentate anchoring mode on a TiO 2 cluster. These nitro dyes reveal weak, but non-negligible, adsorption onto TiO 2; yet, very low photovoltaic performance once incorporated into a DSSC device. Finally, this poor delivery of nitro groups as DSSC anchors is ostensibly inconsistent with previous findings; but is rationalized via the “auxiliary anchor” concept.« less

Self-Assembly of Cis-Configured Squaraine Dyes at the TiO2-Dye Interface: Far-Red Active Dyes for Dye-Sensitized Solar Cells.

PubMed

Punitharasu, Vellimalai; Mele Kavungathodi, Munavvar Fairoos; Nithyanandhan, Jayaraj

2018-05-16

To synergize both steric and electronic factors in designing the dyes for dye-sensitized solar cells, a series of cis-configured unsymmetrical squaraine dyes P11-P15 with suitably functionalized alkyl groups and squaric acid units containing the electron-withdrawing groups were synthesized, respectively. These dyes capture the importance of (i) the effect and position of branched alkyl groups, (ii) mono- and di-anchoring groups containing dyes, and (iii) further appending the alkyl groups through the cyanoester vinyl unit on the central squaric acid units of D-A-D-based cis-configured squaraine dyes. All the above factors govern the controlled self-assembly of the dyes on the TiO 2 surface which helps to broaden the absorption profile of the dyes with an increased energy-harvesting process. With respect to the position of the branched alkyl groups, dye P11 with the sp 3 -C and N-alkyl groups away from the TiO 2 surface showed a better device efficiency of 5.98% ( J sc of 14.46 mA cm -2 , V oc of 0.576 V, and ff of 71.8%) than its positional isomer P12 with 3.45% ( J sc of 8.78 mA cm -2 , V oc of 0.554 V, and ff of 70.9%). However, with respect to the dyes containing mono- and di-anchoring groups, P13 with two anchoring units exhibited a superior device performance of 7.58% ( J sc of 17.12 mA cm -2 , V oc of 0.618 V, and ff of 71.7%) in the presence of optically transparent co-adsorbent CDCA (3α,7α-dihydroxy-5β-cholanic acid) than dyes P11 and P12.

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.

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.

Design of organic dyes and cobalt polypyridine redox mediators for high-efficiency dye-sensitized solar cells.

PubMed

Feldt, Sandra M; Gibson, Elizabeth A; Gabrielsson, Erik; Sun, Licheng; Boschloo, Gerrit; Hagfeldt, Anders

2010-11-24

Dye-sensitized solar cells (DSCs) with cobalt-based mediators with efficiencies surpassing the record for DSCs with iodide-free electrolytes were developed by selecting a suitable combination of a cobalt polypyridine complex and an organic sensitizer. The effect of the steric properties of two triphenylamine-based organic sensitizers and a series of cobalt polypyridine redox mediators on the overall device performance in DSCs as well as on transport and recombination processes in these devices was compared. The recombination and mass-transport limitations that, previously, have been found to limit the performance of these mediators were avoided by matching the properties of the dye and the cobalt redox mediator. Organic dyes with higher extinction coefficients than the standard ruthenium sensitizers were employed in DSCs in combination with outer-sphere redox mediators, enabling thinner TiO(2) films to be used. Recombination was reduced further by introducing insulating butoxyl chains on the dye rather than on the cobalt redox mediator, enabling redox couples with higher diffusion coefficients and more suitable redox potential to be used, simultaneously improving the photocurrent and photovoltage of the device. Optimization of DSCs sensitized with a triphenylamine-based organic dye in combination with tris(2,2'-bipyridyl)cobalt(II/III) yielded solar cells with overall conversion efficiencies of 6.7% and open-circuit potentials of more than 0.9 V under 1000 W m(-2) AM1.5 G illumination. Excellent performance was also found under low light intensity indoor conditions.

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.

Assessment of different excitation wavelengths for photodetecting neoplastic urothelial lesions by laser-induced autofluorescence spectroscopy

NASA Astrophysics Data System (ADS)

Anidjar, Maurice; Cussenot, Oliver; Avrillier, Sigrid; Ettori, Dominique; Teillac, Pierre; Le Duc, Alain

1996-04-01

We have designed a program using laser induced autofluorescence spectroscopy as a possible way to characterize urothelial tumors of the bladder. The autofluorescence spectra were compared between normal, suspicious and tumor areas of human bladder. Three different pulsed laser wavelengths were used for excitation: 308 nm (excimer), 337 nm (nitrogen) and 480 nm (dye laser). Excitation light was delivered by a specially devised multifiber catheter introduced through the working channel of a regular cystoscope under saline irrigation. The fluorescence light was focused into an optical multichannel analyzer detection system. The data was evaluated in 25 patients immediately before resection of a bladder tumor. Spectroscopic results were compared with histopathology. Upon 337 nm and 480 nm excitations, the overall intensity of the fluorescence spectra from bladder tumors was clearly reduced in comparison with normal urothelium, regardless of the stage and the grade of the tumor. upon 308 nm excitation, the shape of tumor fluorescence spectra, including carcinoma in situ, differed drastically from that of normal tissue. In this case, no absolute intensity measurements are needed and clear diagnosis can be achieved from fluorescence intensity ratio (360/440 nm). This spectroscopic study could be particularly useful for the design of a simplified autofluorescence imaging device for real-time routine detection of occult urothelial neoplastic lesions.

Dual-Pump Coherent Anti-Stokes Raman Scattering Temperature and CO2 Concentration Measurements

NASA Technical Reports Server (NTRS)

Lucht, Robert P.; Velur-Natarajan, Viswanathan; Carter, Campbell D.; Grinstead, Keith D., Jr.; Gord, James R.; Danehy, Paul M.; Fiechtner, G. J.; Farrow, Roger L.

2003-01-01

Measurements of temperature and CO2 concentration using dual-pump coherent anti-Stokes Raman scattering, (CARS) are described. The measurements were performed in laboratory flames,in a room-temperature gas cell, and on an engine test stand at the U.S. Air Force Research Laboratory, Wright-Patterson Air Force Base. A modeless dye laser, a single-mode Nd:YAG laser, and an unintensified back-illuminated charge-coupled device digital camera were used for these measurements. The CARS measurements were performed on a single-laser-shot basis. The standard deviations of the temperatures and CO2 mole fractions determined from single-shot dual-pump CARS spectra in steady laminar propane/air flames were approximately 2 and 10% of the mean values of approximately 2000 K and 0.10, respectively. The precision and accuracy of single-shot temperature measurements obtained from the nitrogen part of the dual-pump CARS system were investigated in detail in near-adiabatic hydrogen/air/CO2 flames. The precision of the CARS temperature measurements was found to be comparable to the best results reported in the literature for conventional two-laser, single-pump CARS. The application of dual-pump CARS for single-shot measurements in a swirl-stabilized combustor fueled with JP-8 was also demonstrated.

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

Zinc oxide nanocolloids prepared by picosecond pulsed laser ablation in water at different temperatures

NASA Astrophysics Data System (ADS)

D'Urso, Luisa; Spadaro, Salvatore; Bonsignore, Martina; Santangelo, Saveria; Compagnini, Giuseppe; Neri, Fortunato; Fazio, Enza

2018-01-01

Zinc oxide with wide direct band gap and high exciton binding energy is one of the most promising materials for ultraviolet (UV) light-emitting devices. It further exhibits good performance in the degradation of non-biodegradable pollutants under UV irradiation. In this work, zinc oxide (ZnO) and zinc oxide/gold (ZnO/Au) nanocolloids are prepared by picosecond pulsed laser ablation (ps-PLA), using a Zn and Au metallic targets in water media at room temperature (RT) and 80°C. ZnO and Au nanoparticles (NPs) with size in the 10-50 nm range are obtained at RT, while ZnO nanorods (NRs) are formed when water is maintained at 80°C during the ps-PLA process. Au NPs, added to ZnO colloids after the ablation process, decorate ZnO NRs. The crystalline phase of all ZnO nanocolloids is wurtzite. Methylene blue dye is used to investigate the photo-catalytic activity of all the synthesised nanocolloids, under UV light irradiation.

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.

The rotary gallstone lithotrite to aid gallbladder extraction in laparoscopic cholecystectomy.

PubMed

Sackier, J M; Hunter, J G; Paz-Partlow, M; Cuschieri, A

1992-01-01

During laparoscopic cholecystectomy, a large stone burden may cause difficulty when extracting the gallbladder through the abdominal wall. Currently, the alternatives available to the surgeon include increasing the incision, removing stones singly, or utilizing complex fragmentation techniques like the pulsed dye laser. We have employed an electromechanical rotary gallstone lithotrite (RGL) to fragment stones to an aspiratable size. Initially, cholesterol spheres were pulverized in a latex balloon to demonstrate the efficacy of the device. Then, human gallstones were placed in the balloon and reduced to fragments less than or equal to 1 mm from initial sizes of 4-24 mm. Human stones were then inserted in ex vivo porcine gallbladders in a controlled experiment and treated with the device. Ten out of 12 tests were completed within 30 s; one test required 49 s and one 105 s to achieve complete fragmentation. Blinded histological evaluation demonstrated that tissue abrasion caused by use of the device would not interfere with the diagnosis of unsuspected malignancy. Clinical trials have now commenced under the auspices of the hospital ethical committee.

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.

Bio-Inspired Photon Absorption and Energy Transfer for Next Generation Photovoltaic Devices

NASA Astrophysics Data System (ADS)

Magsi, Komal

Nature's solar energy harvesting system, photosynthesis, serves as a model for photon absorption, spectra broadening, and energy transfer. Photosynthesis harvests light far differently than photovoltaic cells. These differences offer both engineering opportunity and scientific challenges since not all of the natural photon absorption mechanisms have been understood. In return, solar cells can be a very sensitive probe for the absorption characteristics of molecules capable of transferring charge to a conductive interface. The objective of this scientific work is the advancement of next generation photovoltaics through the development and application of natural photo-energy transfer processes. Two scientific methods were used in the development and application of enhancing photon absorption and transfer. First, a detailed analysis of photovoltaic front surface fluorescent spectral modification and light scattering by hetero-structure was conducted. Phosphor based spectral down-conversion is a well-known laser technology. The theoretical calculations presented here indicate that parasitic losses and light scattering within the spectral range are large enough to offset any expected gains. The second approach for enhancing photon absorption is based on bio-inspired mechanisms. Key to the utilization of these natural processes is the development of a detailed scientific understanding and the application of these processes to cost effective systems and devices. In this work both aspects are investigated. Dye type solar cells were prepared and tested as a function of Chlorophyll (or Sodium-Copper Chlorophyllin) and accessory dyes. Forster has shown that the fluorescence ratio of Chlorophyll is modified and broadened by separate photon absorption (sensitized absorption) through interaction with nearby accessory pigments. This work used the dye type solar cell as a diagnostic tool by which to investigate photon absorption and photon energy transfer. These experiments shed some doubt on the Foster Resonant Energy Transfer mechanism since energy relay dye architecture-photosensitizer mixtures do not broaden the response of solar cells. Spectral absorption characterization of chromophore-Chlorophyll solutions in varying solvent polarity confirm the lack of cooperative absorption via a Foster-like mechanism and point the way to new concepts of cooperative absorption in natural systems and the development of a new photovoltaic paradigm.

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.

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.

Modeling recombination processes and predicting energy conversion efficiency of dye sensitized solar cells from first principles

NASA Astrophysics Data System (ADS)

Ma, Wei; Meng, Sheng

2014-03-01

We present a set of algorithms based on solo first principles calculations, to accurately calculate key properties of a DSC device including sunlight harvest, electron injection, electron-hole recombination, and open circuit voltages. Two series of D- π-A dyes are adopted as sample dyes. The short circuit current can be predicted by calculating the dyes' photo absorption, and the electron injection and recombination lifetime using real-time time-dependent density functional theory (TDDFT) simulations. Open circuit voltage can be reproduced by calculating energy difference between the quasi-Fermi level of electrons in the semiconductor and the electrolyte redox potential, considering the influence of electron recombination. Based on timescales obtained from real time TDDFT dynamics for excited states, the estimated power conversion efficiency of DSC fits nicely with the experiment, with deviation below 1-2%. Light harvesting efficiency, incident photon-to-electron conversion efficiency and the current-voltage characteristics can also be well reproduced. The predicted efficiency can serve as either an ideal limit for optimizing photovoltaic performance of a given dye, or a virtual device that closely mimicking the performance of a real device under different experimental settings.

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.

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

Efficient iodine-free dye-sensitized solar cells employing truxene-based organic dyes.

PubMed

Zong, Xueping; Liang, Mao; Chen, Tao; Jia, Jiangnan; Wang, Lina; Sun, Zhe; Xue, Song

2012-07-07

Two new truxene-based organic sensitizers (M15 and M16) featuring high extinction coefficients were synthesized for dye-sensitized solar cells employing cobalt electrolyte. The M16-sensitized device displays a 7.6% efficiency at an irradiation of AM1.5 full sunlight.

[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.

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.

Diagnostic techniques in thermal plasma processing, part 2, volume 2

NASA Astrophysics Data System (ADS)

Boulos, M.; Fauchais, P.; Pfender, E.

1986-02-01

Techniques for diagnostics for thermal plasmas are discussed. These include both optical techniques and in-flight measurements of particulate matter. In the core of the plasma, collisional excitation of the various chemical species is so strong that the population of the corresponding quantum levels becomes high enough for net emission from the plasma. In that case, the classical methods of emission spectroscopy may be applied. But in the regions where the temperatures are below 4000K (these regions are of primary importance for plasma processing), the emission from the plasma is no longer sufficient for emission spectroscopy. In this situation, the population of excited levels must be increased by the absorption of the light from an external source. Such sources, as for example pulsed tunable dye lasers, are now commercially available. The use of such new devices leads to various techniques such as laser induced fluorescence (LIF) or Coherent Anti Stockes Raman Spectroscopy (CARS) that can be used for analyzing plasmas. Particle velocity measurements can be achieved by photography and laser Doppler anemometry. Particle flux measurements are typically achieved by collecting particles on a substrate. Particle size measurements are based on intensity of scattered light.

Ultra-broad range organic solid-state laser from a dye-doped holographic grating quasi-waveguide configuration

NASA Astrophysics Data System (ADS)

Liu, Minghuan; Liu, Yonggang; Peng, Zenghui; Mu, Quanquan; Cao, Zhaoliang; Lu, Xinghai; Ma, Ji; Xuan, Li

2017-08-01

This paper reports the ultra-broad 149.1 nm lasing emission from 573.2 to 722.3 nm using a simple [4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran] (DCM)-doped holographic polymer-dispersed liquid crystal (HPDLC) grating quasi-waveguide configuration by varying the grating period. The lasing emission beams show s-polarization property. The quasi-waveguide structure, which contained the cover glass, the DCM-doped HPDLC grating, the semiconducting polymer film poly[-methoxy-5-(2‧-ethyl-hexyloxy)-1,4-phenylene-vinylene] (MEH-PPV), and the substrate were confirmed to decrease lasing threshold and broaden lasing wavelength. The operational lifetime of the device is 240 000 pulses, which corresponds to an overall laser duration of more than 6 h at a repetition rate of 10 Hz. In addition, the dual-wavelength lasing range from the 8th and 9th order is over 40 nm. The electrical tunability of the dual-wavelength lasing emission is over 1 nm. The experimental results facilitated the decreased lasing threshold and broadened lasing wavelength range of organic solid-state lasers.

[Fabrications of a poly (methyl methacrylate) (PMMA) microfluidic chip-based DNA analysis device].

PubMed

Du, Xiao-Guang

2009-12-01

A DNA analysis device based on poly(methyl methacrylate) (PMMA) microfluidic chips was developed. A PMMA chip with cross microchannels was fabricated by a simple hot embossing. Microchannels were modified with a static adsorptive coating method using 2% hydroxyethyl cellulose. A high-voltage power unit, variable in the range 0-1 800 V, was used for on-chip DNA sample injection and gel electrophoretic separation. High speed, high resolution DNA analysis was obtained with the home-built PMMA chip in a sieving matrix containing 2% hydroxyethyl cellulose with a blue intercalating dye, TO-PRO-3 (TP3), by using diode laser induced fluorescence detection based on optical fibers with a 670 nm long-pass filter. The DNA analysis device was applied for the separation of phiX-174/HaeIII DNA digest sample with 11 fragments ranging from 72 to 1 353 bp. A separation efficiency of 1.14 x 10(6) plates/m was obtained for the 603 bp fragments, while the R of 271/281 bp fragments was 1.2. The device was characterized by simple design, low cost for fabrication and operation, reusable PMMA chips, and good reproducibility. A portable microfluidic device for DNA analysis can be developed for clinical diagnosis and disease screening.

Effect of the co-sensitization sequence on the performance of dye-sensitized solar cells with porphyrin and organic dyes.

PubMed

Fan, Suhua; Lu, Xuefeng; Sun, Hong; Zhou, Gang; Chang, Yuan Jay; Wang, Zhong-Sheng

2016-01-14

To obtain a broad spectral response in the visible region, TiO2 film is co-sensitized with a porphyrin dye (FNE57 or FNE59) and an organic dye (FNE46). It is found that the stepwise co-sensitization in one single dye solution followed by in another single dye solution is better than the co-sensitization in a cocktail solution in terms of photovoltaic performance. The stepwise co-sensitization first with a porphyrin dye and then with an organic dye outperforms that in a reverse order. DSSC devices based on co-sensitizers FNE57 + FNE46 and FNE59 + FNE46 with a quasi-solid-state gel electrolyte generate power conversion efficiencies of 7.88% and 8.14%, respectively, which exhibits remarkable efficiency improvements of 61% and 35%, as compared with devices sensitized with the porphyrin dyes FNE57 and FNE59, respectively. Co-sensitization brings about a much improved short-circuit photocurrent due to the complementary absorption of the two sensitizers. The observed enhancement of incident monochromatic photon-to-electron conversion efficiency from individual dye sensitization to co-sensitization is attributed to the improved charge collection efficiency rather than to the light harvesting efficiency. Interestingly, the open-circuit photovoltage for the co-sensitization system comes between the higher voltage for the porphyrin dye (FNE57 or FNE59) and the lower voltage for the organic dye (FNE46), which is well correlated with their electron lifetimes. This finding indicates that not only the spectral complementation but also the electron lifetime should be considered to select dyes for co-sensitization.

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.

Photothermal generation of microbubbles on plasmonic nanostructures inside microfluidic channels

NASA Astrophysics Data System (ADS)

Li, Jingting; Li, Ming; Santos, Greggy M.; Zhao, Fusheng; Shih, Wei-Chuan

2016-03-01

Microbubbles have been utilized as micro-pumps, micro-mixers, micro-valves, micro-robots and surface cleaners. Various generation techniques can be found in the literature, including resistive heating, hydrodynamic methods, illuminating patterned metal films and noble metal nanoparticles of Au or Ag. We present photothermal microbubble generation by irradiating nanoporous gold disk covered microfluidic channels. The size of the microbubble can be controlled by adjusting the laser power. The dynamics of both bubble growth and shrinkage are studied. The advantages of this technique are flexible bubble generation locations, long bubble lifetimes, no need for light-adsorbing dyes, high controllability over bubble size, low power consumption, etc. This technique has the potential to provide new flow control functions in microfluidic devices.

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.

Dye Wastewater Cleanup by Graphene Composite Paper for Tailorable Supercapacitors.

PubMed

Yu, Dandan; Wang, Hua; Yang, Jie; Niu, Zhiqiang; Lu, Huiting; Yang, Yun; Cheng, Liwei; Guo, Lin

2017-06-28

Currently, the energy crisis and environmental pollution are two critical challenges confronted by humans. The development of smart strategies to address the above-mentioned issues simultaneously is significant. As the main accomplices for water pollution, several kinds of organic dyes with intrinsic redox functional groups such as phenothiazines derivatives, anthraquinone, and indigoid dyes are potential candidates for the replacement of the conventional pseudocapacitive materials. In this work, three typical organic dyes can be efficiently removed by a facile adsorption procedure using reduced graphene oxide coated cellulose fiber (rGO@CF) paper. Flexible supercapacitors based on dye/rGO@CF electrodes exhibit excellent electrochemical performances that are superior to or comparable with those of conventional pseudocapacitive materials based devices, presenting a new type of promising electrode materials. Moreover, benefiting from the high flexibility and considerable mechanical strength of the graphene composite paper, the operating potential and capacitance of the devices can be easily adjusted by tailoring the hybrid electrodes into different specific shapes followed by rational integrating. The smart design of these dye/rGO@CF paper based electrodes shows that energy storage and environmental remediation can be achieved simultaneously.

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.

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.

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.

White light photothermal lens spectrophotometer for the determination of absorption in scattering samples.

PubMed

Marcano, Aristides; Alvarado, Salvador; Meng, Junwei; Caballero, Daniel; Moares, Ernesto Marín; Edziah, Raymond

2014-01-01

We developed a pump-probe photothermal lens spectrophotometer that uses a broadband arc-lamp and a set of interference filters to provide tunable, nearly monochromatic radiation between 370 and 730 nm as the pump light source. This light is focused onto an absorbing sample, generating a photothermal lens of millimeter dimensions. A highly collimated monochromatic probe light from a low-power He-Ne laser interrogates the generated lens, yielding a photothermal signal proportional to the absorption of light. We measure the absorption spectra of scattering dye solutions using the device. We show that the spectra are not affected by the presence of scattering, confirming that the method only measures the absorption of light that results in generation of heat. By comparing the photothermal spectra with the usual absorption spectra determined using commercial transmission spectrophotometers, we estimate the quantum yield of scattering of the sample. We discuss applications of the device for spectroscopic characterization of samples such as blood and gold nanoparticles that exhibit a complex behavior upon interaction with light.

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.

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.

21 CFR 872.1745 - Laser fluorescence caries detection device.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Laser fluorescence caries detection device. 872... SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Diagnostic Devices § 872.1745 Laser fluorescence caries detection device. (a) Identification. A laser fluorescence caries detection device is a laser, a...

Fabrication and characterization of nanowalls CdS/dye sensitized solar cells

NASA Astrophysics Data System (ADS)

Abdulelah, Haider; Ali, Basil; Mahdi, M. A.; Hassan, J. J.; Al-Taay, H. F.; Jennings, P.

2017-06-01

A microwave assisted chemical bath deposition (MA-CBD) was adopted to fabricate nanowalls CdS nanocrystalline thin film. Nanomaterials (such as nanowalls structure) have attracted significant attention due to their fascinating properties and unique applications, especially in optoelectronic nanodevices. Here we describe the fabrication of dye sensitized solar cells (DSSCs) based nanowalls cadmium sulfide (CdS) nanocrystalline thin films. The surface morphology, crystalline structure, and optical properties of the prepared nanocrystalline thin films are investigated. Rhodamine B, Malachite green, Eosin methylene blue, and Cresyl violet perchlorate dyes are used to fabricate the DSSCS devices. Current-voltage (I-V) characteristics show that the nanowall CdS/Eosin methylene blue device is the highest conversion efficiency of 0.89% under 100 mW/cm2. However, heat treatment of the fabricated solar cells causes significant enhancement in the output of all devices.

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.

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.

Lessons learned: from dye-sensitized solar cells to all-solid-state hybrid devices.

PubMed

Docampo, Pablo; Guldin, Stefan; Leijtens, Tomas; Noel, Nakita K; Steiner, Ullrich; Snaith, Henry J

2014-06-25

The field of solution-processed photovoltaic cells is currently in its second spring. The dye-sensitized solar cell is a widely studied and longstanding candidate for future energy generation. Recently, inorganic absorber-based devices have reached new record efficiencies, with the benefits of all-solid-state devices. In this rapidly changing environment, this review sheds light on recent developments in all-solid-state solar cells in terms of electrode architecture, alternative sensitizers, and hole-transporting materials. These concepts are of general applicability to many next-generation device platforms. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Self bleaching photoelectrochemical-electrochromic device

DOEpatents

Bechinger, Clemens S.; Gregg, Brian A.

2002-04-09

A photoelectrochemical-electrochromic device comprising a first transparent electrode and a second transparent electrode in parallel, spaced relation to each other. The first transparent electrode is electrically connected to the second transparent electrode. An electrochromic material is applied to the first transparent electrode and a nanoporous semiconductor film having a dye adsorbed therein is applied to the second transparent electrode. An electrolyte layer contacts the electrochromic material and the nanoporous semiconductor film. The electrolyte layer has a redox couple whereby upon application of light, the nanoporous semiconductor layer dye absorbs the light and the redox couple oxidizes producing an electric field across the device modulating the effective light transmittance through the device.

Method and apparatus for passive optical dosimeter comprising caged dye molecules

DOEpatents

Sandison, David R.

2001-07-03

A new class of ultraviolet dosimeters is made possible by exposing caged dye molecules, which generate a dye molecule on exposure to ultraviolet radiation, to an exterior environment. Applications include sunburn monitors, characterizing the UV exposure history of UV-sensitive materials, especially including structural plastics, and use in disposable `one-use` optical equipment, especially medical devices.

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.

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.

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.

In vivo non-invasive optical imaging of temperature-sensitive co-polymeric nanohydrogel

NASA Astrophysics Data System (ADS)

Chen, Haiyan; Zhang, Jian; Qian, Zhiyu; Liu, Fei; Chen, Xinyang; Hu, Yuzhu; Gu, Yueqing

2008-05-01

Assessment of hyperthermia in pathological tissue is a promising strategy for earlier diagnosis of malignant tumors. In this study, temperature-sensitive co-polymeric nanohydrogel poly(N-isopropylacrylamide-co-acrylic acid) (PNIPA-co-AA) was successfully synthesized by the precipitation polymerization method. The diameters of nanohydrogels were controlled to be less than 100 nm. Also the lower critical solution temperature (LCST, 40 °C) was manipulated above physiological temperature after integration of near-infrared (NIR) organic dye (heptamethine cyanine dye, HMCD) within its interior cores. NIR laser light (765 nm), together with sensitive charge coupled device (CCD) cameras, were designed to construct an NIR imaging system. The dynamic behaviors of PNIPA-co-AA-HMCD composites in denuded mice with or without local hyperthermia treatment were real-time monitored by an NIR imager. The results showed that the PNIPA-co-AA-HMCD composites accumulated in the leg treated with local heating and diffused much slower than that in the other leg without heating. The results demonstrated that the temperature-responsive PNIPA-co-AA-HMCD composites combining with an NIR imaging system could be an effective temperature mapping technique, which provides a promising prospect for earlier tumor diagnosis and thermally related therapeutic assessment.

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.

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.

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.

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

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.

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.-

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.

Polyaniline Nanofibers as the Hole Transport Medium in an Inverse Dye-Sensitized Solar Cell

NASA Astrophysics Data System (ADS)

Hesselsweet, Ian Brock

In order to become a viable alternative to silicon photovoltaics, dye-sensitized solar cells must overcome several issues primarily resulting from their use of a liquid electrolyte. Much research has gone into correcting these shortcomings by replacing the liquid electrolyte with solid-state hole-transport media. Using these solid-state materials brings new difficulties, such as completely filling the pores in the TiO2 nanostructure, and achieving good adhesion with the dye-coated TiO2. A novel approach to addressing these difficulties is the inverse dye-sensitized solar cell design. In this method the devices are constructed in reverse order, with the solidstate hole-transport medium providing the nanostructure instead of the TiO2. This allows new materials and methods to be used which may better address these issues. In this project, inverse dye-sensitized solar cells using polyaniline nanofibers as the hole transport medium were prepared and characterized. The devices were prepared on fluorine-doped tin oxide (FTO) coated glass electrodes. The first component was a dense spin-coated polyaniline blocking layer, to help prevent short circuiting of the devices. The second layer was a thin film of drop cast polyaniline nanofibers which acted as the hole transport medium and provided high surface area for the dye attachment. The dye used was 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin (TCPP), which was covalently attached to the nanofibers using a Friedel-Crafts acylation. Titania gel was then deposited into the pores of the nanofiber film by controlled hydrolysis of a titanium complex (Tyzor LA). A back electrode of TiO2 nanoparticles sintered on FTO was pressed on top to complete the devices. A typical device generated an open circuit voltage of 0.17 V and a closed circuit current of 5.7 nA/cm2 while the highest open circuit voltage recorded for any variation on a device was 0.31 V and the highest short circuit current was 52 nA/cm2 under AM 1.5 simulated solar spectrum at 100 mW/cm2. Initially prepared devices did not generate a measureable photocurrent due to two materials flaws. The first was traced to the poorly developed conduction band of the titania gel, as deposited from Tyzor LA hydrolysis, resulting in poor electron conduction. This prevented the titania gel from efficiently functioning as the electron transport medium. A remedy was found in adding a layer of sintered anatase TiO2 nanoparticles on the back electrode to serve as the electron transport medium. However, this remedy does not address the issue of the inability of titania gel to efficiently transport electrons photogenerated deep in the nanofiber film to the back electrode. The second flaw was found to originate from fast recombination kinetics between electrons in TiO2 and holes in polyaniline. However, a positive feature was that the titania gel intended to be used as the electron transport medium was found to sufficiently insulate the interface such that the recombination rate slowed enough to allow generation of a measureable photocurrent. Electronic insulation was further enhanced by co-attaching decanoic acid onto the polyaniline nanofibers to fill in pinholes between the dye molecules. While these solutions were not ideal, they were intended to be diagnostic in nature and supplied critical information about the weak links in the device design, thus pointing the way toward improving device performance. Significant enhancements can be expected by addressing these issues in further detail.

Optical Sensors Based on Single on Arm Thin Film Waveguide Interferometer

NASA Technical Reports Server (NTRS)

Sarkisov, S. S.; Diggs, D.; Curley, M.; Adamovsky, Grigory (Technical Monitor)

2000-01-01

Single-arm dual-mode optical waveguide interferometer utilizes interference between two modes of different order. Sensing effect results from the change in propagation conditions of the modes caused by the environment. The waveguide is made as an open asymmetric structure containing a dye-doped polymer film onto a quartz substrate. It is more sensitive to the change of environment than its conventional polarimetric analog using orthogonal modes (TE and TM) of the same order. The sensor still preserves the option of operating in polarimetric regime using a variety of mode combinations such as TE(sub 0)/TM(sub 0) (conventional) TE(sub 0)/TM(sub 1), TE(sub 1)/TM(sub 0), or TE(sub 1)/TM(sub 1) but can also work in nonpolarimetric regime using combinations TE(sub 0)/TE(sub 1) or TM(sub 0)/TM(sub 1). Utilization of different mode combinations simultaneously makes the device more versatile. Application of the sensor to gas sensing is based on doping polymer film with an organic indicator dye targeting a particular gaseous reagent. Change of the optical absorption spectrum of the dye caused by the gaseous pollutant results in change of the reactive index of the dye-doped polymer film that can be detected by the sensor. As indicator dyes we utilize Bromocresol Purple doped into polymer poly(methyl) methacrylate that is sensitive to small concentrations of ammonia. The indicator dye demonstrated an irreversible increase in optical absorption near the peak at 350 nm being exposed to 5% ammonia in pure nitrogen at 600 Torr. The dye also showed reversible growth of the absorption peak near 600 nm after exposure to a vapor of standard medical ammonia spirit (65% alcohol). We have built a breadboard prototype of the sensor with He-Ne laser as a light source and with a single mode fiber input and a multimode fiber output. The prototype showed a sensitivity to temperature change of the order of 2 C per 2pi phase shift. The sensitivity of the sensor to the presence of dTy ammonia is not less than 300 ppm per 2pi phase shift. The proposed sensor can be used as a robust stand-alone instrument for continuous environment pollution monitoring.

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

Cosensitization of Structurally Simple Porphyrin and Anthracene-Based Dye for Dye-Sensitized Solar Cells.

PubMed

Reddy, Kamani Sudhir K; Chen, Yen-Chiao; Wu, Chih-Chung; Hsu, Chia-Wei; Chang, Ya-Ching; Chen, Chih-Ming; Yeh, Chen-Yu

2018-01-24

Since their introduction, dye-sensitized solar cells (DSCs) have achieved huge success at a laboratory level. Recently, research is concentrated to visualize large DSC modules at the commercial platform. In that aspect, we have tested structurally simple porphyrin-based dye SK6 and anthracene-based dye CW10 for DSCs application under simulated 1 sun (AM 1.5G) and indoor light sources. These two dyes can be easily synthesized and yet are efficient with cell performances of ca. 5.42% and ca. 5.75% (without coadsorbent/additive) for SK6 and CW10, respectively, under AM 1.5G illumination. The power conversion efficiency (PCE) of SK6 reported in this work is the highest ever reported; this is achieved by optimizing the adsorption of SK6 on TiO 2 photoanode using the most suitable solvent and immersion period. Cosensitization of SK6 with CW10 on TiO 2 surface has boosted cell performance further and achieved PCE of ca. 6.31% under AM 1.5G illumination. Charge-transfer properties of individual and cosensitized devices at TiO 2 /dye/electrolyte interface were examined via electrochemical impedance spectroscopy. To understand the cell performances under ambient light conditions, we soaked individual and cosensitized devices under T5 and light-emitting diode light sources in the range of 300-6000 lx. The PCE of ca. 22.91% under T5 light (6000 lx) with J SC = 0.883 mA cm -2 , V OC = 0.646 V, and FF = 0.749 was noted for the cosensitized device, which equals a power output of 426 μW cm -2 . These results reveal that DSCs made of structurally simple dyes performed efficiently under both 1 sun (AM 1.5G) and indoor light conditions, which is undoubtedly a significant achievement when it comes to a choice of commercial application.

Characterization of anti-theft devices directly from the surface of banknotes via easy ambient sonic spray ionization mass spectrometry.

PubMed

Schmidt, Eduardo Morgado; Franco, Marcos Fernando; Cuelbas, Claudio José; Zacca, Jorge Jardim; de Carvalho Rocha, Werickson Fortunato; Borges, Rodrigo; de Souza, Wanderley; Sawaya, Alexandra Christine Helena Frankland; Eberlin, Marcos Nogueira; Correa, Deleon Nascimento

2015-09-01

Using Brazilian banknotes as a test case, forensic examination and identification of Rhodamine B dye anti-theft device (ATD) staining on banknotes were performed. Easy ambient sonic spray ionization mass spectrometry (EASI-MS) was used since it allows fast and simple analysis with no sample preparation providing molecular screening of the surface with direct desorption and ionization of the security dye. For a more accurate molecular characterization of the ATD dye, Q Exactive Orbitrap™ Fourier transform (tandem) mass spectrometry using eletrospray ionization (ESI-HRMS/MS) was also applied. Copyright © 2015 The Chartered Society of Forensic Sciences. Published by Elsevier Ireland Ltd. All rights reserved.

Durable electrooptic devices comprising ionic liquids

DOEpatents

Agrawal, Anoop; Cronin, John P.; Tonazzi, Juan C. L.; Warner, Benjamin P.; McCleskey, T. Mark; Burrell, Anthony K.

2005-11-01

Electrolyte solutions for electrochromic devices such as rear view mirrors and displays with low leakage currents are prepared using inexpensive, low conductivity conductors. Preferred electrolytes include bifunctional redox dyes and molten salt solvents with enhanced stability toward ultraviolet radiation. The solvents include lithium or quaternary ammonium cations, and perfluorinated sulfonylimide anions selected from trifluoromethylsulfonate (CF3SO3-), bis(trifluoromethylsulfonyl)imide ((CF3SO2)2N-), bis(perfluoroethylsulfonyl)imide ((CF3CF2SO2)2N-) and tris(trifluoromethylsulfonyl)methide ((CF3SO2)3C-). Electroluminescent, electrochromic and photoelectrochromic devices with nanostructured electrodes include ionic liquids with bifunctional redox dyes.

Advances in display technology III; Proceedings of the Meeting, Los Angeles, CA, January 18, 19, 1983

NASA Astrophysics Data System (ADS)

Schlam, E.

1983-01-01

Human factors in visible displays are discussed, taking into account an introduction to color vision, a laser optometric assessment of visual display viewability, the quantification of color contrast, human performance evaluations of digital image quality, visual problems of office video display terminals, and contemporary problems in airborne displays. Other topics considered are related to electroluminescent technology, liquid crystal and related technologies, plasma technology, and display terminal and systems. Attention is given to the application of electroluminescent technology to personal computers, electroluminescent driving techniques, thin film electroluminescent devices with memory, the fabrication of very large electroluminescent displays, the operating properties of thermally addressed dye switching liquid crystal display, light field dichroic liquid crystal displays for very large area displays, and hardening military plasma displays for a nuclear environment.

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.

Synthesis and Characterization of Reduced Graphene Oxide/Rhodamine 101 (rGO-Rh101) Nanocomposites and Their Heterojunction Performance in rGO-Rh101/ p-Si Device Configuration

NASA Astrophysics Data System (ADS)

Batır, G. Güven; Arık, Mustafa; Caldıran, Zakir; Turut, Abdulmecit; Aydogan, Sakir

2018-01-01

Reduced graphene oxide (rGO)-rhodamine 101 (Rh101) nanocomposites with different ratios of rGO have been synthesized in aqueous medium by ultrasonic homogenization. The fluorescence of Rh101 as measured using a laser dye with high fluorescence quantum yield was substantially quenched with increasing amount of rGO in the nanocomposite. Formation of rGO-Rh101 nanocomposites was confirmed by x-ray diffraction analysis, scanning electron microscopy, ultraviolet-visible (UV-Vis) spectroscopy, and fluorescence microscopy. Furthermore, rGO-Rh101 nanocomposite/ p-Si heterojunctions were synthesized, all of which showed good rectifying behavior. The electrical characteristics of these devices were analyzed using current-voltage ( I- V) measurements to determine the ideality factor and barrier height. The experimental results confirmed the presence of lateral inhomogeneity in the effective barrier height of the rGO-Rh101 nanocomposite/ p-Si heterojunctions. In addition to I- V measurements, one device was analyzed in more detail using frequency-dependent capacitance-voltage measurements. All electrical measurements were carried out at room temperature and in the dark.

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

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.

AFRL Advanced Electric Lasers Branch - Construction and Upgrade of a 50-watt Facility-Class Sodium Guidestar Pump Laser

NASA Astrophysics Data System (ADS)

Bronder, T.; Miller, H.; Stohs, J.; Lu, C.; Baker, J.; Lucero, A.

The development of a reliable and effective laser source for pumping mesospheric sodium to generate an artificial guidestar has been well documented. From the early achievements with 589nm high-power dye lasers at the Keck and Lick observatories to the ground-breaking 50W CW FASOR (Frequency Addition Source of Optical Radiation) Guidestar at the Air Forces Starfire Optical Range (SOR), there has been intense interest in this technology from both the academic and military communities. Beginning in the fall of 2008, the Air Force Research Laboratorys Advanced Electric Lasers Branch began a project to build, test, verify and deliver an upgraded version of the SOR FASOR for use at the AF Maui Optical Station (AMOS) in the summer of 2010. This FASOR will be similar in design to the existing SOR device and produce 50W of diffraction limited, linearly polarized narrow linewidth 589nm light by combining the output of two injection-locked Nd:YAG ring lasers (operating at 1064nm and 1319nm) using resonant sum-frequency generation in a lithium triborate crystal (LBO). The upgraded features will include modularized sub-components, embedded control electronics, and a simplified cooling system. The first portion of this upgrade project is to reconstruct the current SOR FASOR components and include improved methods of regulating the gain modules of the two injection lasers. In parallel with this effort, the technical plans for the modularization and re-packaging of the FASOR will be finalized and coordinated with the staff at Maui. This presentation will summarize the result of these efforts to date and provide updates on the AMOS FASOR status. Additionally, plans for "next-generation" FASOR upgrades for both SOR and AMOS will also be discussed.

Characteristics of dye Rhoeo spathacea in dye sensitizer solar cell (DSSC)

NASA Astrophysics Data System (ADS)

Sumardiasih, Sri; Obina, Wilfrida M.; Cari; Supriyanto, Agus; Septiawan, Trio Y.; Khairuddin

2017-01-01

Dye-sensitized solar cell (DSSC) is a device that converts solar energy into electrical energy. The magnitude of the efficiency of DSSC is mainly based on the amount of dye absorbed by the surface of TiO2. In this work, used natural dye extracted from leaves Rhoeo spathacea. The dye partially used to immerse of TiO2 as working electrodes, and the rest are directly mixed TiO2 paste to obtain dye titanium dioxide.The paste TiO2 and dye titanium dioxide coated onto the fluorine-doped tin oxide (FTO) glass plate by spin coating method. The absorbance spectra of the dye, dye titanium dioxide and TiO2 were obtained by UV-Vis spectroscopy. The conductivity of the dye, dye titanium dioxide, and TiO2 was measured by two point probe El-Kahfi 100. The DSSC based on dye titanium dioxide that stirring for 5 hours the highest efficiency of 0,0520 % whereas those based on TiO2 immersed for 36 hours showed achieved 0,0501 % obtained from I-V characterization.

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.

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.

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

A measurement and modeling study of temperature in living and fixed tissue during and after radiofrequency exposure.

PubMed

Bermingham, Jacqueline F; Chen, Yuen Y; McIntosh, Robert L; Wood, Andrew W

2014-04-01

Fluorescent intensity of the dye Rhodamine-B (Rho-B) decreases with increasing temperature. We show that in fresh rat brain tissue samples in a custom-made radiofrequency (RF) tissue exposure device, temperature rise due to RF radiation as measured by absorbed dye correlates well with temperature measured nearby by fiber optic probes. Estimates of rate of initial temperature rise (using both probe measurement and the dye method) accord well with estimates of local specific energy absorption rate (SAR). We also modeled the temperature characteristics of the exposure device using combined electromagnetic and finite-difference thermal modeling. Although there are some differences in the rate of cooling following cessation of RF exposure, there is reasonable agreement between modeling and both probe measurement and dye estimation of temperature. The dye method also permits measurement of regional temperature rise (due to RF). There is no clear evidence of local differential RF absorption, but further refinement of the method may be needed to fully clarify this issue. © 2014 Wiley Periodicals, Inc.

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.

Molecular Design of Efficient Organic D-A-π -A Dye Featuring Triphenylamine as Donor Fragment for Application in Dye-Sensitized Solar Cells.

PubMed

Ferdowsi, Parnian; Saygili, Yasemin; Zhang, Weiwei; Edvinson, Tomas; Kavan, Ladislav; Mokhtari, Javad; Zakeeruddin, Shaik M; Grätzel, Michael; Hagfeldt, Anders

2018-01-23

A metal-free organic sensitizer, suitable for the application in dye-sensitized solar cells (DSSCs), has been designed, synthesized and characterized both experimentally and theoretically. The structure of the novel donor-acceptor-π-bridge-acceptor (D-A-π-A) dye incorporates a triphenylamine (TPA) segment and 4-(benzo[c][1,2,5]thiadiazol-4-ylethynyl)benzoic acid (BTEBA). The triphenylamine unit is widely used as an electron donor for photosensitizers, owing to its nonplanar molecular configuration and excellent electron-donating capability, whereas 4-(benzo[c][1,2,5]thiadiazol-4-ylethynyl)benzoic acid is used as an electron acceptor unit. The influences of I 3 - /I - , [Co(bpy) 3 ] 3+/2+ and [Cu(tmby) 2 ] 2+/+ (tmby=4,4',6,6'-tetramethyl-2,2'-bipyridine) as redox electrolytes on the DSSC device performance were also investigated. The maximal monochromatic incident photon-to-current conversion efficiency (IPCE) reached 81 % and the solar light to electrical energy conversion efficiency of devices with [Cu(tmby) 2 ] 2+/+ reached 7.15 %. The devices with [Co(bpy) 3 ] 3+/2+ and I 3 - /I - electrolytes gave efficiencies of 5.22 % and 6.14 %, respectively. The lowest device performance with a [Co(bpy) 3 ] 3+/2+ -based electrolyte is attributed to increased charge recombination. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Study of natural organic dyes as active material for fabrication of organic light emitting diodes

NASA Astrophysics Data System (ADS)

Sánchez Juárez, A.; Castillo, D.; Guaman, A.; Espinosa, S.; Obregón, D.

2016-09-01

The scientific community and some sectors of industry have been working with organic dyes for successful applications in OLED's, OSC's, however, most of the used dyes and pigments are synthetic. In this work is investigated the use of natural dyes for its application in organic light emitting diodes, some of the studied species are chili, blackberry, guayacan flower, cochinilla, tree tomato, capuli, etc. In this study the dyes are deposited by direct deposition and SOL-GEL process doped with the natural organic dye, both methods show good performance and lower fabrication costs for dye extraction, this represents a new alternative for the fabrication of OLED devices with low requirements in technology. Most representative results are presented for Dactylopius Coccus Costa (cochinilla) and raphanus sativus' skin.

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.

Bi-anchoring organic sensitizers of type D-(π-A)2 comprising thiophene-2-acetonitrile as π-spacer and malonic acid as electron acceptor for dye sensitized solar cell applications

NASA Astrophysics Data System (ADS)

Reddy, Gachumale Saritha; Ramkumar, Sekar; Asiri, Abdullah M.; Anandan, Sambandam

2015-06-01

Two new bi-anchoring organic sensitizers of type D-(π-A)2 comprising the identical π-spacer (thiophene-2-acetonitrile) and electron acceptor (malonic acid) but different aryl amine as electron donors (diphenylamine and carbazole) were synthesized, characterized and fabricated metal free dye-sensitized solar cell devices. The intra molecular charge transfer property and electrochemical property of these dyes were investigated by molecular absorption, emission, cyclic voltammetric experiments and in addition, quantum chemical calculation studies were performed to provide sufficient driving force for the electron injection into the conduction band of TiO2 which leads to efficient charge collection. Among the fabricated devices, carbazole based device exhibits high current conversion efficiency (η = 4.7%) with a short circuit current density (JSC) 15.3 mA/cm2, an open circuit photo voltage (VOC) of 0.59 V and a fill factor of 0.44 under AM 1.5 illumination (85 mW/cm2) compared to diphenylamine based device.

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.

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.

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.