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May 2002

The Laboratory
in the News

Commentary by
Jeff Wadsworth

Building a Virtual Telescope

A New Understanding of Soft Materials

At Livermore, Audacious Physics Has Thrived for
50 years





Frederic V. Hartemann, Hector A. Baldis, Eric C. Landahl
Chirped Pulse Inverse Free-Electron Laser Vacuum Accelerator
U.S. Patent 6,345,058 B1
February 5, 2002
A chirped-pulse inverse free-electron laser (IFEL) vacuum accelerator for high-gradient laser acceleration in vacuum. By using an ultrashort (femtosecond), ultrahigh-intensity chirped laser pulse, both the IFEL interaction bandwidth and accelerating gradient are increased, thus yielding large gains in a compact system. In addition, the IFEL resonance condition can be maintained throughout the interaction region by using a chirped-drive laser wave. Also, diffraction can be alleviated by taking advantage of the laser optical bandwidth with negative dispersion focusing optics to produce a chromatic line focus. The combination of these features results in a compact, efficient laser vacuum accelerator with many applications, including high-energy physics, medical imaging and therapy, material science, and basic physics.

Bernardino M. Penetrante
NOx Reduction by Electron Beam-Produced Nitrogen Atom Injection
U.S. Patent 6,345,497 B1
February 12, 2002
Deactivated atomic nitrogen generated by an electron beam from a gas stream containing more than 99 percent nitrogen is injected at low temperatures into an engine exhaust to reduce NOx emissions. High NOx reduction efficiency is achieved with compact electron beam devices without the use of a catalyst.

Tri D. Tran, David J. Lenz
Alternating-Polarity Operation for Complete Regeneration of Electrochemical Deionization System
U.S. Patent 6,346,187 B1
February 12, 2002
An electrically regeneratable battery of electrochemical cells for capacitive deionization (including electrochemical purification) and regeneration of electrodes is operated at alternate polarities during consecutive cycles. By polarizing the cells, ions are removed from the electrolyte and are held in the electric double layers formed at the carbon aerogel surfaces of the electrodes. As the electrodes of each cell of the battery are saturated with the removed ions, the battery is regenerated electrically at a reversed polarity from that during the deionization step of the cycle, thus significantly minimizing secondary wastes.

Sol P. Dijaili, Frank G. Patterson, Jeffrey D. Walker, Robert J. Deri, Holly Petersen, William Goward
Thermally Robust Semiconductor Optical Amplifiers and Laser Diodes
U.S. Patent 6,347,106 B1
February 12, 2002
A highly heat-conductive layer is combined with or placed in the vicinity of the optical waveguide region of active semiconductor components. The thermally conductive layer enhances the conduction of heat away from the active region, which is where the heat is generated in active semiconductor components. This layer is placed so close to the optical region that it must also function as a waveguide and causes the active region to be nearly the same temperature as the ambient temperature or heat sink. However, the semiconductor material itself should be as temperature-insensitive as possible, and therefore, the invention combines a highly thermally conductive dielectric layer with improved semiconductor materials to achieve an overall package that offers improved thermal performance. The highly thermally conductive layer serves two basic functions. First, it provides a lower index material than the semiconductor device so that certain kinds of optical waveguides may be formed, for example, a ridge waveguide. Second and most important, this layer provides a significantly higher thermal conductivity than the semiconductor material, which is the principal material in the fabrication of various optoelectronic devices.

Raymond J. Beach, Eric C. Honea, Camille Bibeau, Stephen A. Payne, Howard Powell, William F. Krupke,
Steven B. Sutton
High Average Power Scaleable Thin-Disk Laser
U.S. Patent 6,347,109 B1
February 12, 2002
Using a thin-disk laser gain element with an undoped cap layer enables the scaling of lasers to extremely high-average output-power values. Ordinarily, the power scaling of such thin disk lasers is limited by the deleterious effects of amplified spontaneous emission. By using an undoped cap layer diffusion bonded to the thin disk, the onset of amplified spontaneous emission does not occur as readily as it would if no cap layer is used, and much larger transverse thin disks can be effectively used as laser gain elements. This invention can be used as a high-average-power laser for material processing applications as well as for weapon and air defense applications.

Erwin T. Rosenbury, Gerald K. Burke, Scott D. Nelson, Robert D. Stever, George K. Gorverno, Donald J. Mullenhoff
Low Cost Impulse Compatible Wideband Antenna
U.S. Patent 6,348,898 B1
February 19, 2002
An antenna apparatus and method for building the antenna. Impulse signals travel through a feed point of the antenna with respect to a ground plane. A geometric fin structure is connected to the feed point and through a termination resistance to the ground plane. A geometric ridge structure connected to the ground is positioned with respect to the fin to receive and radiate electromagnetic energy from the impulse signal at a predetermined impedance and over a predetermined set of frequencies. The fin and ridge can be either a wire or a planar surface. The fin and ridge may be disposed within a radiation cavity such as a horn. The radiation cavity is constructed of stamped and etched metal sheets bent and then soldered together. The fin and ridge are also formed from metal sheets or wires. The fin is attached to the feed point and then to the cavity through a termination resistance. The ridge is attached to the cavity and disposed with respect to the fin to achieve a particular set of antenna characteristics.

Steven L. Hunter
Self Adjusting Inclinometer
U.S. Patent 6,349,477 B1
February 26, 2002
An inclinometer using synchronous demodulation for high-resolution and electronic offset adjustment provides a wide dynamic range without any moving components. A device encompassing a tiltmeter and accompanying electronic circuitry provides quasilevel tilt sensors that detect highly resolved tilt change without signal saturation.

Long N. Dinh, Mehdi Balooch, William McLean II, Marcus A. Schildbach
Junction-Based Field Emission Structure for Field Emission Display
U.S. Patent 6,351,254 B2
February 26, 2002
A junction-based field emission display, wherein the junctions are formed by depositing a semiconducting or dielectric, low-work-function, negative electron affinity (NEA) silicon-based compound film (SBCF) onto a metal or n-type semiconductor substrate. The SBCF can be doped to become a p-type semiconductor. A small forward bias voltage is applied across the junction so that electron transport is from the substrate into the SBCF region. When the voltage enters this NEA region, many electrons are released into the vacuum level above the SBCF surface and accelerated toward a positively biased phosphor screen anode, hence lighting up the phosphor screen for display. To turn off the screen, the user can simply switch off the applied potential across the SBCF/substrate. The invention may be used for field emission flat-panel displays.

David J. Erskine
Combined Dispersive/Interference Spectroscopy for Producing a Vector Spectrum
U.S. Patent 6,351,307 B1
February 26, 2002
A method of measuring the spectral properties of broadband waves that combines interferometry with a wavelength disperser having many spectral channels to produce a fringing spectrum. Spectral mapping, Doppler shifts, metrology of angles, distances, and secondary effects such as temperature, pressure, and acceleration that change an interferometer cavity length can be measured accurately by a compact instrument using broadband illumination. Broadband illumination avoids the fringe skip ambiguities of monochromatic waves. The interferometer provides arbitrarily high spectral resolution, simple instrument response, compactness, low cost, high field of view, and high efficiency. The inclusion of a disperser increases fringe visibility and signal-to-noise ratio over an interferometer used alone for broadband waves. The fringing spectrum is represented as a wavelength-dependent two-dimensional vector, which describes the fringe amplitude and phase. Vector mathematics such as generalized dot products rapidly computes average broadband phase shifts to high accuracy. A moiré effect between the interferometer’s sinusoidal transmission and the illumination heterodyne’s high- to low-resolution spectral detail allows the use of a low-resolution disperser. Multiple parallel interferometer cavities of fixed delay allow the instantaneous mapping of a spectrum, using an instrument more compact for the same spectral resolution than a conventional dispersive spectrometer, and do not require a scanning delay.

Jeffrey S. Haas, John F. Bushman, Douglas E. Howard, James L. Wong, Joel D. Eckels
Portable Gas Chromatograph Mass Spectrometer for On-Site Chemical Analyses
U.S. Patent 6,351,983 B1
March 5, 2002
A portable, lightweight (approximately 25 kilograms) gas chromatograph–mass spectrometer (GC–MS), including the entire vacuum system, can perform qualitative and quantitative analyses of all sample types in the field. The GC–MS has a conveniently configured layout of components for ease of serviceability and maintenance. The GC–MS system can be transported under operating or near operating conditions (that is, under vacuum and at elevated temperature) to reduce the downtime before samples can be analyzed on site.

William Man-Wai Tong, John S. Taylor, Scott D. Hector, Pawitter J. S. Mangat, Alan R. Stivers, Patrick G. Kofron, Matthew A. Thompson
Coatings on Reflective Mask Substrates
U.S. Patent 6,352,803 B1
March 5, 2002
A process for creating a mask substrate involving depositing (1) a coating on one or both sides of a low-thermal expansion material, extreme-ultraviolet-light mask substrate to improve defect inspection, surface finishing, and defect levels; and (2) a high-dielectric coating on the backside to facilitate electrostatic chucking and correct for any bowing caused by the stress imbalance imparted either by other deposited coatings or the multilayer coating of the mask substrate. A film, such as tantalum silicon, may be deposited on the front or back of the low-thermal-expansion material, before the material coating, to balance the stress. The low-thermal-expansion material with a silicon overlayer and a silicon and other conductive underlayer enables improved defect inspection and stress balancing.

Peter A. Krulevitch, Robin R. Miles, Xiao-Bo Wang, Raymond P. Mariella, Peter R. C. Gascoyne, Joseph W. Balch
Microfluidic DNA Sample Preparation Method and Device
U.S. Patent 6,352,838 B1
March 5, 2002
Manipulation of DNA molecules in solution has become an essential aspect of genetic analyses used for biomedical assays, identifying hazardous bacterial agents, and decoding the human genome. Currently, most of the steps involved in preparing a DNA sample for analysis are performed manually and are time-, labor-, and equipment-intensive. These steps include extraction of the DNA from spores or cells, separation of the DNA from other particles and molecules in the solution (for example, dust, smoke, cell/spore debris, and proteins), and separation of the DNA itself into strands of specific lengths. Dielectrophoresis, a phenomenon whereby polarizable particles move in response to a gradient in electric field, can be used to manipulate and separate DNA in an automated fashion, considerably reducing the time and expense involved in DNA analyses as well as allowing for the miniaturizaiton of DNA analysis instruments. These applications include direct transport of DNA, trapping of DNA to allow for its separation from other particles or molecules in the solution, and the separation of DNA into strands of varying lengths.


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