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UV Laser (uv + laser)
Selected AbstractsSingle-layered microscale linear-gradient PDLC material for electro-opticsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 8 2009Y. G. Marinov Abstract We report on single-layered optical material of linear-gradient microscale polymer-dispersed liquid crystal (PDLC). E7/NOA65 composite films formed by pulsed UV laser photopolymerization-induced phase separation exhibit two morphology types, namely a bipolar and a hybrid alignment of liquid crystal droplets. The specific structural properties of the produced PDLC layers, such as the droplet shape uniformity and alignment, as well as the droplet size control through the film thickness, facilitate the efficient control on the electro-optical (EO) response, thus being of practical interest for EO device applications. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Use of stereolithography to manufacture critical-sized 3D biodegradable scaffolds for bone ingrowth,JOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2003Malcolm N. Cooke Abstract A novel approach to the manufacture of biodegradable polymeric scaffolds for tissue-engineering utilizing stereolithography (SLA) is presented. SLA is a three-dimensional (3D) printing method that uses an ultraviolet laser to photo-crosslink a liquid polymer substrate. The current generation of SLA devices provide a 3D printing resolution of 0.1 mm. The experiments utilized a biodegradable resin mixture of diethyl fumarate (DEF), poly(propylene fumarate) (PPF), and a photoinitiator, bisacylphosphine oxide (BAPO). The PPF is crosslinked with the use of the SLA's UV laser (325-nm wavelength). An SLA device was retrofitted with a custom fixture build tank enclosing an elevator-driven build table. A 3D prototype model testing the manufacturing control this device provides was created in a computer-aided-design package. The resulting geometric data were used to drive the SLA process, and a DEF/PPF prototype part was successfully manufactured. These scaffolds have application in the tissue engineering of bony substrates. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 64B: 65,69, 2002 [source] Optimum acquisition of Raman spectra in pigment analysis with IR laser diode and pulsed UV irradiationJOURNAL OF RAMAN SPECTROSCOPY, Issue 10 2006Alejandro López-Gil Abstract Fluorescence, due to the binding media, is the main problem that one encounters in the molecular analysis of artistic pigments using Raman spectroscopy. With the object of minimizing this problem, we propose the use of a semiconductor IR laser in Raman spectral acquisition and the application of local irradiation with a pulsed UV laser on the analysis zone. The Raman analysis with an IR source shows advantages compared to that with visible lasers, such as the reduction of fluorescence and its shot noise, although a price has to be paid in the form of the small intensity of the obtained spectra with the same acquisition time. Also, in this paper we demonstrate that controlled levels of pulsed UV radiation over the analyzed painting (pigment + binding media) can improve even more the Raman spectral quality obtained with the IR laser, which leads us to conclude that the local use of a pulsed UV laser, prior to Raman analysis with the IR source, can bring optimum quality results in pigment identification. The spectral quality of these experimental results for different pigments has been measured by calculating in each case the signal-to-noise ratio (SNR) of the corresponding spectra. From a quantitative point of view, in some practical cases (chromium yellow and ultramarine blue) an SNR improvement of 16 dB is achieved when pulsed UV irradiation and IR laser Raman analysis are used instead of a simple Raman analysis with a visible laser. Copyright © 2006 John Wiley & Sons, Ltd. [source] Surface-enhanced Raman spectroscopy with ultraviolet excitationJOURNAL OF RAMAN SPECTROSCOPY, Issue 6-7 2005Xu-Feng Lin Abstract Surface-enhanced Raman scattering (SERS) spectroscopy excited with a UV laser was successfully developed and the UV,SER spectra of various adsorbates, including pyridine and SCN,, on different transition metal electrodes were obtained. The experimental requirements for obtaining UV,SERS in an electrochemical system are given. The surface enhancement factor of a roughened Rh electrode covered with thiocyanate as a model molecule was estimated to be about two orders of magnitude in the UV region, consistent with our preliminary theoretical calculation based on the electromagnetic model. The investigation of SERS in the UV region will improve the understanding of the SERS enhancement mechanism and broaden the research field of SERS in areas such as surface science and the life sciences. Copyright © 2005 John Wiley & Sons, Ltd. [source] Over 8 W high peak power UV laser with a high power Q-switched Nd:YVO4 oscillator and the compact extra-cavity sum-frequency mixingLASER PHYSICS LETTERS, Issue 2 2009X.P. Yan Abstract A 8.2 W UV laser was reported with the compact extra-cavity sum-frequency mixing. The IR fundamental frequency source was a high power and high beam quality Q-switched Nd:YVO4 oscillator. 38Wfundamental frequency laser at 1064 nm was obtained at the pulse repetition rate of 450 kHz with the beam quality factors of M2x = 1.27, M2y = 1.21. The type I and type II phase-matched LBO crystals were used as the extra-cavity frequency doubling and mixing crystals respectively. At 38 kHz, 8.2 W UV laser at 355 nm was achieved with the pulse duration of 8 ns corresponding to the pulse peak power as high as 27 kW, and the optical-optical conversion efficiency from IR to UV was 25.6%. The output characteristics of the IR and the harmonic generations varying with the pulse repetition rate were also investigated detailedly. (© 2009 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Direct detection of particles formed by laser ablation of matrices during matrix-assisted laser desorption/ionization,RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 18 2003Sandra Alves We report the detection of nanoparticles formed by irradiating matrix-assisted laser desorption/ionization (MALDI) matrix samples. This is direct evidence for the ejection of large size aggregates in the MALDI process. Nanometer-size particles were generated via a tunable solid-state UV laser, irradiating a sample placed in a nitrogen atmosphere. Size distribution measurements were performed using a differential mobility analyzer and a condensation particle counter. Particles in the 10,1000,nm size range were detected. The dependence of the particle size distribution on the laser fluence, wavelength and matrix was investigated. The observed effects are discussed and related to the MALDI ablation dynamics and gas-phase processes. Copyright © 2003 John Wiley & Sons, Ltd. 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