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Full-Text Articles in Physical Sciences and Mathematics
Developing Instrumentation For Fabricating And Characterizing Thin Film Aluminum Mirrors, P. Claire Segura
Developing Instrumentation For Fabricating And Characterizing Thin Film Aluminum Mirrors, P. Claire Segura
Student Works
The best material for constructing a mirror for a broad-bandwidth telescope that is also capable of reflecting EUV light is pure aluminum. In order to test how the reflectance of aluminum in the EUV range changes as it oxidizes, a system has been constructed that allows a thin aluminum mirror to be constructed inside of a vacuum, where its reflectance can then be tested immediately. Because the experiment must take place in a vacuum, it must also be controlled remotely through a computer program, which manages the mirror fabrication process as well as the collection and analysis of reflectance data. …
Characterization Of Optical Constants For Uranium From 10 To 47 Nm, Nicole Brimhall, Nicholas Herrick, David D. Allred, R. Steven Turley, Michael Ware, Justin Peatross
Characterization Of Optical Constants For Uranium From 10 To 47 Nm, Nicole Brimhall, Nicholas Herrick, David D. Allred, R. Steven Turley, Michael Ware, Justin Peatross
Faculty Publications
We use a laser high-harmonics-based extreme-ultraviolet (EUV) polarimeter to determine the optical constants of elemental uranium in the wavelength range from 10 to 47 nm. The constants are extracted from the measure ratio of p-polarized to s-polarized reflectance from a thin uranium film deposited in situ. The film thickness is inferred from a spectroscopic ellipsometry measurement of the sample after complete oxidation in room air. Uranium has been used as a high-reflectance material in the EUV. However, difficulties with oxidation prevented its careful characterization previous to this study. We find that measured optical constants for uranium vary significantly from previous …
Extreme-Ultraviolet Polarimeter Utilizing Laser-Generated High-Order Harmonics, Nicole Brimhall, Matthew Turner, Nicholas Herrick, David D. Allred, R. Steven Turley, Michael Ware, Justin Peatross
Extreme-Ultraviolet Polarimeter Utilizing Laser-Generated High-Order Harmonics, Nicole Brimhall, Matthew Turner, Nicholas Herrick, David D. Allred, R. Steven Turley, Michael Ware, Justin Peatross
Faculty Publications
We describe an extreme-ultraviolet (EUV) polarimeter that employs laser-generated high-order harmonics as the light source. The polarimeter is designed to characterize materials and thin films for use with EUV light. Laser high harmonics are highly directional with easily rotatable linear polarization, not typically available with other EUV sources. The harmonics have good wavelength coverage, potentially spanning the entire EUV from a few to a hundred nanometers. Our instrument is configured to measure reflectances from 14 to 30 nm and has ~180 spectral resolution (lambda/delta lambda). The reflection from a sample surface can be measured over a continuous range of incident …
Nanoscale Characterization Of Thin Film Coatings Using Annular Dark Field Scanning Transmission Electron Microscopy, Guillermo Acosta, Richard Vanfleet, David D. Allred
Nanoscale Characterization Of Thin Film Coatings Using Annular Dark Field Scanning Transmission Electron Microscopy, Guillermo Acosta, Richard Vanfleet, David D. Allred
Faculty Publications
When considering the optical performance of thin films in the Extreme Ultraviolet (EUV), developing an accurate physical description of a thin film coating is necessary to be able to successfully model optical performance. With the short wavelengths of the EUV, film interfaces and sample roughness warrant special attention and care. The surfaces of thin film samples are routinely measured by Atomic Force Microscopy, from which roughness can be determined. However, characterizing the quality of interfaces below the surface is much more challenging. In a recent study of scandium oxide thin films, High Resolution Transmission Electron Microscopy and Annular Dark Field …
Scandium Oxide Thin Films And Their Optical Properties In The Extreme Ultraviolet, Guillermo Antonio Acosta
Scandium Oxide Thin Films And Their Optical Properties In The Extreme Ultraviolet, Guillermo Antonio Acosta
Theses and Dissertations
This study reports on the physical and optical characterization of scandium oxide thin films. Thin films of scandium oxide, 20-40 nm thick, were deposited on silicon wafers, quartz slides, and silicon photodiodes by reactively sputtering scandium in an oxygen environment. These samples were characterized using ellipsometry, high-resolution transmission electron microscopy, scanning transmission electron microscopy, and energy dispersive x-ray analysis. A 28.46 nm thick scandium oxide thin film was measured in the Extreme Ultraviolet (EUV) from 2.7 to 50 nm (459.3 to 24.8 eV) using synchrotron radiation at the Advanced Light Source Beamline 6.3.2 at the Lawrence Berkeley National Laboratory. In …
Phase-Matching Optimization Of Laser High-Order Harmonics Generated In A Gas Cell, Julia Robin Miller Sutherland
Phase-Matching Optimization Of Laser High-Order Harmonics Generated In A Gas Cell, Julia Robin Miller Sutherland
Theses and Dissertations
Ten-millijoule, thirty-five femtosecond, 800 nm (~40 nm bandwidth) laser pulses are used to study high-order harmonic generation in helium- and neon-filled gas cells of various lengths. Harmonic orders in the range of 50 to 100 are investigated. A semi-infinite cell geometry produces brighter harmonics than cells of sub-centimeter length. In the semi-infinite geometry, the gas occupies the region from the focusing lens to a thin exit foil near the laser focus. Counter-propagating light is used to directly probe where the high harmonics are generated within the laser focus and to investigate phase matching. The phase matching under optimized harmonic generation …
Optical Properties And Application Of Uranium-Based Thin Films For The Extreme Ultraviolet And Soft X-Ray Region, Richard L. Sandberg, David D. Allred, Shannon Lunt, Marie K. Urry, R. Steven Turley
Optical Properties And Application Of Uranium-Based Thin Films For The Extreme Ultraviolet And Soft X-Ray Region, Richard L. Sandberg, David D. Allred, Shannon Lunt, Marie K. Urry, R. Steven Turley
Faculty Publications
Uranium oxide and uranium nitride thin films reflect significantly more than all previously known/standard reflectors (e.g., nickel, gold, and iridium) for most of the 4-10 nm range at low angles of incidence. This work includes measurements of the EUV/soft x-ray (2-20 nm) reflectance of uranium-based thin films (~20 nm thick) and extraction of their optical constants (d and ?). We report the reflectances at 5, 10, and 15 degrees grazing incidence of air-oxidized sputtered uranium, reactively sputtered (O2) uranium oxide, and reactively sputtered (N2) uranium nitride thin films measured at Beamline 6.3.2 at the Advanced Light Source (ALS) at Lawrence …
Controlling Laser High-Order Harmonic Generation Using Weak Counter-Propagating Light, Sergei Leonidovich Voronov
Controlling Laser High-Order Harmonic Generation Using Weak Counter-Propagating Light, Sergei Leonidovich Voronov
Theses and Dissertations
Laser high-order harmonic generation in the presence of relatively weak interfering light is investigated. The interfering pulses intersect the primary harmonic-generating laser pulse at the laser focus. The interfering light creates a standing intensity and phase modulation on the field, which disrupts microscopic phase matching and shuts down local high harmonic production. Suppression of the 23rd harmonic (by two orders of magnitude) is observed when a counter-propagating interfering pulse of light is introduced. A sequence of counter-propagating pulses can be used to shut down harmonic production in out-of-phase zones of the generating volume to achieve quasi phase matching. Harmonic emission …