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Characterization of an AO-OCT system

Description: Adaptive optics (AO) and optical coherence tomography (OCT) are powerful imaging modalities that, when combined, can provide high-volumetric-resolution, images of the retina. The AO-OCT system at UC Davis has been under development for 2 years and has demonstrated the utility of this technology for microscopic, volumetric, in vivo retinal imaging [1]. The current system uses an AOptix bimorph deformable mirror (DM) for low-order, high-stroke correction [2] and a 140-actuator Boston Micromachine… more
Date: July 26, 2007
Creator: Evans, J. W.; Zawadzki, R. J.; Jones, S.; Olivier, S. & Werner, J. S.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

EUV mask reflectivity measurements with micron-scale spatial resolution

Description: The effort to produce defect-free mask blanks for EUV lithography relies on increasing the detection sensitivity of advanced mask inspection tools, operating at several wavelengths. We describe the unique measurement capabilities of a prototype actinic (EUV wavelength) microscope that is capable of detecting small defects and reflectivity changes that occur on the scale of microns to nanometers. Types of defects: (a) Buried Substrate Defects: particles & pits (causes amplitude and/or phase vari… more
Date: May 26, 2008
Creator: Goldberg, Kenneth A.; Rekawa, S. B.; Kemp, C. D.; Barty, A.; Anderson, E. H.; Kearney, Patrick et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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EUV micro-exposure tool at 0.5 NA for sub-16 nm lithography

Description: The resolution limit of present 0.3 NA 13.5 nm wavelength micro-exposure tools is compared to next generation lithography research requirements. Findings suggest that a successor design is needed for patterning starting at the 16 nm semiconductor process technology node. A two-mirror 0.5 NA optical design is presented, and performance expectations are established from detailed optical and lithographic simulation. Here, we report on the results from a SEMATECH program to fabricate a projection o… more
Date: September 26, 2008
Creator: Goldstein, Michael; Hudyma, Russ; Naulleau, Patrick & Wurm, Stefan
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Long wavelength GaN blue laser (400-490nm) development

Description: Room temperature (RT) pulsed operation of blue nitride based multi-quantum well (MQW) laser diodes grown on c-plane sapphire substrates was achieved. Atmospheric pressure MOCVD was used to grow the active region of the device which consisted of a 10 pair In{sub 0.21}Ga{sub 0.79}N (2.5nm)/In{sub 0.07}Ga{sub 0.93}N (5nm) InGaN MQW. The threshold current density was reduced by a factor of 2 from 10 kA/cm{sup 2} for laser diodes grown on sapphire substrates to 4.8 kA/cm{sub 2} for laser diodes grow… more
Date: October 26, 2000
Creator: DenBaars, S. P.; Abare, A.; Sink, K.; Kozodoy, P.; Hansen, M.; Bowers, J. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Position Stability Monitoring of THEthe LCLS Undulator Quadrupoles

Description: X-ray FELs demand that the positions of undulator components be stable to less than 1 {mu}m per day. Simultaneously, the undulator length increases significantly in order to saturate at x-ray wavelengths. To minimize the impact of the outside environment, the Linac Coherent Light Source (LCLS) undulator is placed underground, but reliable data about ground motion inside such a tunnel was not available in the required stability range during the planning phase. Therefore, a new position monitor s… more
Date: March 26, 2012
Creator: Nuhn, Heinz Dieter; Gassner, Georg & Peters, Franz
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Raman Spectroscopy of Lithium Hydride Corrosion: Selection of an Appropriate Excitation Wavelength to Minimize Fluorescence

Description: The recent interest in a hydrogen-based fuel economy has renewed research into metal hydride chemistry. Many of these compounds react readily with water to release hydrogen gas and form a caustic. Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFT) has been used to study the hydrolysis reaction. The LiOH stretch appears at 3670 cm{sup -1}. Raman spectroscopy is a complementary technique that employs monochromatic excitation (laser) allowing access to the low energy region of the… more
Date: May 26, 2011
Creator: Stowe, A. C. & Smyrl, N. R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Calibration of a High Resolution Soft X-ray Spectrometer

Description: A high resolution grating spectrometer (HRGS) with 2400 line/mm variable line spacing grating for the 10-50 {angstrom} wavelength range has been designed for laser-produced plasma experiments at the Lawrence Livermore National Laboratory (LLNL). The spectrometer has a large radius of curvature, R=44.3 m, is operated at a 2{sup o} grazing angle and can record high signal-to-noise spectra when used with a low-noise, cooled, charge-coupled device detector. The instrument can be operated with a 10-… more
Date: January 26, 2010
Creator: Dunn, J; Beiersdorfer, P; Brown, G V & Magee, E W
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Start-to-End Simulations of the LCLS Accelerator and FEL Performance at Very Low Charge

Description: The Linac Coherent Light Source (LCLS) is an x-ray Free-electron Laser (FEL) being commissioned at Stanford Linear Accelerator Center (SLAC). Recent beam measurements have shown that, using the LCLS injector-linac-compressors, the beam emittance is very small at 20 pC. In this paper we perform start-to-end simulations of the entire accelerator including the FEL undulator and study the FEL performance versus the bunch charge. At 20 pC charge, these calculations associated with the measured beam … more
Date: May 26, 2009
Creator: Ding, Y; Brachmann, A.; Decker, F. J.; Dowell, D.; Emma, P.; Frisch, J. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Coherent Soft X-Ray Generation in the Water Window with the EEHG Scheme

Description: Recently a scheme entitled echo-enabled harmonic generation (EEHG) was proposed for producing short wavelength FEL radiation that allows far higher harmonic numbers to be accessed as compared with the normal limit arising from incoherent energy spread. In this paper we study the feasibility of a single EEHG stage to generate coherent radiation in the 'water window' (2--4 nm wavelength) directly from a UV seed laser at 190-nm wavelength. We present time-dependent simulation results which demonst… more
Date: May 26, 2009
Creator: Xiang, D. & Stupakov, G.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Non-Contact Determination of Free Carrier Concentration in n-GaInAsSb

Description: GaSb-based semiconductors are of interest for mid-infrared optoelectronic and high-speed electronic devices. Accurate determination of electrical properties is essential for optimizing the performance of these devices. However, electrical characterization of these semiconductors is not straightforward since semi-insulating (SI) GaSb substrates for Hall measurements are not available. In this work, the capability of Raman spectroscopy for determination of the majority carrier concentration in n-… more
Date: November 26, 2003
Creator: Maslar, James E.; Hurst, Wildur S.; Wang, Christine A. & Shiau, Daniel A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Nonlinear Longitudinal Waves in High Energy Stored Beams

Description: We solve the Vlasov equation for the longitudinal distribution function and find stationary wave patterns when the distribution in the energy error is Maxwellian. In the long wavelength limit a stability criterion for linear waves has been obtained and a Korteweg-de Vries-Burgers equation for the relevant hydrodynamic quantities has been derived.
Date: July 26, 1999
Creator: Tzenov, Stephan I.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

21nm X-Ray Laser Thomson Scattering of Laser-Heated Exploding Foil Plasmas

Description: Recent experiments were carried out on the Prague Asterix Laser System (PALS) towards the demonstration of a soft x-ray laser Thomson scattering diagnostic for a laser-produced exploding foil. The Thomson probe utilized the Ne-like zinc x-ray laser which was double-passed to deliver {approx}1 mJ of focused energy at 21.2 nm wavelength and lasting {approx}100 ps. The plasma under study was heated single-sided using a Gaussian 300-ps pulse of 438-nm light (3{omega} of the PALS iodine laser) at la… more
Date: September 26, 2007
Creator: Dunn, J.; Rus, B.; Mocek, T.; Nelson, A. J.; Foord, M. E.; Rozmus, W. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Laboratory Studies of the Fe K-shell Emission

Description: An overview is given of measurements of the Fe K-shell spectrum from low-density laboratory sources. The measurements include wavelengths, electron-impact collision cross sections, innershell ionization phenomena, dielectronic recombination resonance strengths, charge exchange recombination, electron beam polarization effects, resonance excitation, and radiative cascade contributions. K-shell spectra have now also been obtained with microcalorimeters, including microcalorimeter arrays that are … more
Date: December 26, 2004
Creator: Beiersdorfer, P
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Near infrared spectral imaging of explosives using a tunable laser source

Description: Diffuse reflectance near infrared hyperspectral imaging is an important analytical tool for a wide variety of industries, including agriculture consumer products, chemical and pharmaceutical development and production. Using this technique as a method for the standoff detection of explosive particles is presented and discussed. The detection of the particles is based on the diffuse reflectance of light from the particle in the near infrared wavelength range where CH, NH, OH vibrational overtone… more
Date: March 26, 2010
Creator: Klunder, G. L.; Margalith, E. & Nguyen, L. K.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

High Power 938nm Cladding Pumped Fiber Laser

Description: We have developed a Nd:doped cladding pumped fiber amplifier, which operates at 938nm with greater than 2W of output power. The core co-dopants were specifically chosen to enhance emission at 938nm. The fiber was liquid nitrogen cooled in order to achieve four-level laser operation on a laser transition that is normally three level at room temperature, thus permitting efficient cladding pumping of the amplifier. Wavelength selective attenuation was induced by bending the fiber around a mandrel,… more
Date: December 26, 2002
Creator: Dawson, J; Beach, R; Brobshoff, A; Liao, Z; Payne, S; Pennington, D et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Brief history of laser AGEX

Description: A great deal of physics understanding is required for the design and construction of thermonuclear weapons. Since the days of the Manhattan Project, physicists have relied on a combination of theory and experiment for the successful creation of nuclear weapons. One of the great experimental difficulties faced by the designers of nuclear weapons is that nuclear weapons operate in a high energy density regime not found on the earth except during a nuclear weapon detonation. Replicating these cond… more
Date: January 26, 2001
Creator: Perry, T S
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Inclusion Analysis and Absorption Measurement in Nonlinear Crystals

Description: Yttrium calcium oxyborate (YCOB) is a newly developed nonlinear optical crystal used for second harmonic generation in the Mercury laser. As with any new crystal, optical characterization of the material properties needs to be fully investigated. We are developing two new techniques to detect inclusions and measure optical absorption. With the side illuminating detection examination (SIDE) method, we hope to identify and map the size, density, and the morphology of inclusions. The multi-pass ab… more
Date: August 26, 2005
Creator: Smith, L. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

MEDICAL AND ENVIRONMENTAL EFFECTS OF UV RADIATION.

Description: Organisms living on the earth are exposed to solar radiation, including its ultraviolet (UV) components (for general reviews, the reader is referred to Smith [1] and Young et al. [2]). UV wavelength regions present in sunlight are frequently designated as UVB (290-320 nm) and UVA (320-400 nm). In today's solar spectrum, UVA is the principal UV component, with UVB present at much lower levels. Ozone depletion will increase the levels of UVB reaching the biosphere, but the levels of UVA will not … more
Date: July 26, 2001
Creator: Sutherland, B. M.
Item Type: Refine your search to only Book
Partner: UNT Libraries Government Documents Department
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