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April 2003

The Laboratory
in the News

Commentary by
C. K. Chou

Finding the Missing Piece in the Climate Change Puzzle

An Elusive Transformation—The Mystery of Oscillating Neutrinos

Toward a Common Data Model for Supercomputing

Into the Vortex—New Insights into the Behavior of Dynamic Fluids





Steven R. Visuri, Anthony J. Makarewicz, Richard A. London, William J. Benett, Peter Krulevitch, Luiz B. Da Silva
Laser and Acoustic Lens for Lithotripsy
U.S. Patent 6,491,685 B2
December 10, 2002
An acoustic focusing device whose acoustic waves are generated by laser radiation through an optical fiber. The acoustic energy can efficiently destroy renal and biliary calculi and is delivered 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. Tensile stresses may be more effective in some instances in disrupting material because 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.

Robert J. Deri, Oliver T. Strand, Henry E. Garrett
Optical Add/Drop Filter for Wavelength Division Multiplexed Systems
U.S. Patent 6,493,484 B1
December 10, 2002
An optical add/drop filter for wavelength division multiplex systems and construction methods. The add/drop filter includes a first ferrule having a first preformed opening for receiving a first optical fiber; an interference filter oriented to pass a first set of wavelengths along the first optical fiber and reflect a second set of wavelengths; and a second ferrule having a second preformed opening for receiving the second optical fiber and the reflected second set of wavelengths. The method for constructing the optical add/drop filter consists of forming a first set of openings in a first ferrule; inserting a first set of optical fibers into the first set of openings; forming a first set of guide pin openings in the first ferrule; dividing the first ferrule into a first ferrule portion and a second ferrule portion; forming an interference filter on the first ferrule portion; inserting guide pins through the first set of guide pin openings in the first ferrule portion and second ferrule portion to passively align the first set of optical fibers; removing material such that light reflected from the interference filter from the first set of optical fibers is accessible; forming a second set of openings in a second ferrule; inserting a second set of optical fibers into the second set of openings; and positioning the second ferrule with respect to the first ferrule such that the second set of optical fibers receive the light reflected from the interference filter.

Babak Sadigh, Thomas J. Lenosky, Tomas Diaz de la Rubia, Martin Giles, Maria-Jose Caturla, Vidvuds Ozolins, Mark Asta, Silva Theiss, Majeed Foad, Andrew Quong
Method for Enhancing the Solubility of Boron and Indium in Silicon
U.S. Patent 6,498,078 B2
December 24, 2002
A method for enhancing the equilibrium solubility of boron and indium in silicon. The method involves first-principles quantum mechanical calculations to determine the temperature dependence of the equilibrium solubility of two important p-type dopants in silicon, namely boron and indium, under various strain conditions. The equilibrium thermodynamic solubility of size-mismatched impurities, such as boron and indium in silicon, can be raised significantly if the silicon substrate is strained appropriately. For example, for boron, a 1-percent compressive strain raises the equilibrium solubility by 100 percent at 1,100ÍC; and for indium, a 1-percent tensile strain at 1,100ÍC corresponds to an enhancement of the solubility by 200 percent.

Conrad Yu
Micro-Machined Thermo-Conductivity Detector
U.S. Patent 6,502,983 B2
January 7, 2003
A micromachined thermal conductivity detector for a portable gas chromatograph. The detector is highly sensitive and has fast response time to enable detection of small gas samples, on the order of nanoliters, in a portable gas chromatograph. The high sensitivity and fast response time are achieved through micromachined devices composed of a nickel wire, for example, on a silicon nitride window, about a millimeter square, formed in a silicon member. In addition to operating as a thermal conductivity detector, the silicon nitride window with a micromachined wire therein can be used as a fast response heater for polymerase chain reaction applications.

William J. Benett, James B. Richards
PCR Thermocycler
U.S. Patent 6,503,750 B1
January 7, 2003
A sleeve-type silicon polymerase chain reaction (PCR) chamber or thermocycler having improved thermal performance. The improved thermal performance comes from etched features in the chamber that reduce thermal mass and increase the surface area of the sleeve for cooling. The improved thermal performance increases the speed and efficiency of the reaction chamber. The improvement is accomplished by providing grooves in the faces of the sleeve and a series of grooves on the interior surfaces that connect with the grooves on the faces of the sleeve. The grooves can be anisotropically etched in the silicon sleeve simultaneously with formation of the chamber.

D. Kent Lewis
Compensated Individually Addressable Array Technology for Human Breast Imaging
U.S. Patent 6,504,288 B2
January 7, 2003
A method of forming broad bandwidth acoustic or microwave beams that encompass array design, array excitation, source signal preprocessing, and received signal postprocessing. This technique uses several different methods to achieve improvement over conventional array systems. These methods are (1) individually addressable array elements without any moving parts, which allow scanning around and over an object such as a human breast; (2) digital-to-analog converters for the source signals, which allow virtually any radiated field to be created in the half-space in front of the array; (3) inverse filtering from source precompensation, which allows for corrections in the system, most notably in the response of the individual elements and in the ability to increase contrast and resolution of signal propagating through the medium under investigation; and (4) spectral extrapolation to expand the bandwidth of the received signals. Used together, the system allows for compensation to create beams of any desired shape, control the wave fields generated to correct for medium differences, and improve contrast and resolution in and through the medium.

Ronald G. Musket, Robert G. Patterson
Versatile, High-Sensitivity Faraday Cup Array for Ion Implanters
U.S. Patent 6,507,033 B1
January 14, 2003
An improved Faraday cup array for determining the dose of ions delivered to a substrate during ion implantation and for monitoring the uniformity of the dose delivered to the substrate. The improved Faraday cup array incorporates a variable size ion beam aperture by changing only an insertable plate that defines the aperture without changing the position of the Faraday cup, which is positioned for the operation of the largest ion beam aperture. The design enables the dose sensitivity range, typically from 1011 to 1018 ions per square centimeter, to be extended to below a million (106) ions per square centimeter. The insertable plate-aperture arrangement is structurally simple and enables scaling to aperture areas between lesser than 1 square centimeter and greater than 750 square centimeters, and enables ultrahigh vacuum (UHV) applications by incorporation of UHV-compatible materials.

Conrad Yu
Chemical Method for Producing Smooth Surfaces on Silicon
U.S. Patent 6,514,875 B1
February 4, 2003
An improved method for producing optically smooth surfaces in silicon wafers during wet chemical etching involves a pretreatment rinse of the wafer before etching and a postetching rinse. The pretreatment with an organic solvent provides a well-wetted surface that ensures uniform mass transfer during etching, which results in optically smooth surfaces. The postetching treatment with an acetic acid solution stops the etching instantly, preventing any uneven etching that leads to surface roughness. This method can be used to etch silicon surfaces to a depth of 200 micrometers or more, while the finished surfaces have a surface roughness of only 1.5 to 5.0 nanometers.

Michael D. Perry
High-Resolution Imaging and Target Designation through Clouds or Smoke
U.S. Patent 6,515,737 B2
February 4, 2003
A method and system of combining gated intensifiers and advances in solid-state, short-pulse laser technology to create compact systems capable of producing high-resolution (that is, approximately less than 20 centimeters) optical images through a scattering medium such as dense clouds, fog, or smoke from air- or ground-based platforms. Laser target designation through a scattering medium is also enabled by using a short-pulse illumination laser and a relatively minor change to the detectors on laser-guided munitions.

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