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March 2002

The Laboratory
in the News

Commentary by
Wayne Shotts

Tracking Down
Virulence in Plague

L-Gel Decontaminates Better Than Bleach

Faster Inspections of Laser Coatings

From Kilobytes to Petabytes in 50 Years




Russell Hudyma
High Numerical Aperture Ring Field Projection System for Extreme Ultraviolet Lithography
U.S. Patent 6,318,869 B1
November 20, 2001
An all-reflective optical system for a projection photolithography camera has a source of extreme ultraviolet radiation, a wafer, and a mask to be imaged on the wafer. The optical system includes a first concave mirror, a second mirror, a third convex mirror, a fourth concave mirror, a fifth convex mirror, and a sixth concave mirror. The system is configured so that 5 of the 6 mirrors receive a chief ray at an incidence angle of less than substantially 12 degrees, and each of the 6 mirrors receives a chief ray at an incidence angle of less than substantially 15 degrees. Four of the six reflecting surfaces have an aspheric departure of less than substantially 7 micrometers. Five of the 6 reflecting surfaces have an aspheric departure of less than substantially 14 micrometers. Each of the 6 reflecting surfaces has an aspheric departure of less than 16 micrometers.

Layton C. Hale, Steven A. Jensen
Highly Damped Kinematic Coupling for Precision Instruments
U.S. Patent 6,325,351 B1
December 4, 2001
A highly damped kinematic coupling for precision instruments. The kinematic coupling provides support while causing essentially no influence to its natural shape. Such influences would come, for example, from manufacturing tolerances, temperature changes, or ground motion. The coupling uses three ball–cone constraints, each combined with a released flexural degree of freedom. This arrangement enables a gain of higher load capacity and stiffness, but can also significantly reduce the friction level in proportion to the ball radius divided by the distance between the ball and the hinge axis. The blade flexures reduce somewhat the stiffness of the coupling and provide an ideal location to apply constrained-layer damping, which is accomplished by attaching a viscoelastic layer and a constraining layer on opposite sides of each of the blade flexures. The three identical ball–cone flexures provide a damped coupling mechanism to kinematically support the projection optics system of an extreme ultraviolet lithography system or other load-sensitive apparatus.

Steven T. Mayer, Richard W. Pekala, James L. Kaschmitt
Method for Fabricating Composite Carbon Foam
U.S. Patent 6,332,990 B1
December 25, 2001
Carbon aerogels used as a binder for granularized materials, including other forms of carbon and metal additives, are cast onto carbon- or meta-fiber substrates to form composite carbon thin-film sheets. The thin-film sheets are used in electrochemical energy storage applications, such as electrochemical double-layer capacitors (aerocapacitors), lithium-based battery insertion electrodes, fuel cell electrodes, and electrocapacitive deionization electrodes. The composite carbon foam may be formed by prior known processes, but with the solid particles being added during the liquid phase of the process, that is, before gelation. The other forms of carbon may include carbon microspheres, carbon powder, carbon aerogel powder or particles, or graphite carbons. Metal and/or carbon fibers may be added for increased conductivity. The choice of materials and fibers will depend on the electrolyte used and the relative trade-off of system resistivity and power to system energy.

Jonathan N. Simon, Steve B. Brown
Apparatus and Method for Collection and Concentration of Respirable Particles into a Small Fluid Volume
U.S. Patent 6,337,213 B1
January 8, 2002
An apparatus and method for the collection and concentration of respirable particles into a small fluid volume. The apparatus captures and concentrates (1 to 20 micrometers) respirable particles into a submilliliter volume of fluid. The method involves a two-step operation, collection and concentration. Collection of particles is done by a wetted surface with small vertical slits that act as capillary channels. Concentration is carried out by transferring the collected particles to a small-volume (submilliliter) container by centrifugal force, which forces the particles through the vertical slits to a nonwetted wall surface of a container. The particles are deflected to the bottom of the container and analyzed with a portable flow cytometer or a portable polymerase chain reaction DNA analysis system.

Brian D. Andresen, Fred S. Miller
Method for Detection of Extremely Low Concentration
U.S. Patent 6,338,824 B1
January 15, 2002
An ultratrace detector system for handheld gas chromatography that is highly sensitive, for example, to emissions generated during production of weapons, biological compounds, or drugs. The detector system is insensitive to water, air, helium, argon, oxygen, and carbon dioxide. The system is basically composed of a handheld capillary gas chromatograph, an insulated heated redox-chamber, a detection chamber, and a vapor trap. As an example of how it works, the detector system may use gas-phase redox reactions and spectral absorption of mercury vapor. The gas chromatograph initially separates compounds that percolate through a bed of heated mercuric oxide in a silica or other metal aerogel material acting as an insulator. Compounds easily oxidized by mercuric oxide liberate atomic mercury, which subsequently passes through a detection chamber that includes a detector cell, such as quartz. The chamber is illuminated with a 254-nanometer ultraviolet mercury discharge lamp that generates the exact mercury absorption band used to detect the liberated mercury atoms. Atomic mercury strongly absorbs 254-nanometer energy and is therefore a specific signal for reducing compounds eluting from the capillary gas chromatograph. Afterward, the atomic mercury is trapped, for example, in a silicon-aerogel trap.

Timothy P. Weihs, Troy W. Barbee, Jr.
Method for Forming a Barrier Layer
U.S. Patent 6,339,020 B1
January 15, 2002
Cubic or metastable cubic refractory metal carbides act as barrier layers to isolate, adhere to, and passivate copper in semiconductor fabrication. One or more barrier layers of the metal carbide is deposited in conjunction with copper metallizations to form a multilayer characterized by a cubic crystal structure with a strong texture. Suitable barrier-layer materials include refractory transition metal carbides such as vanadium carbide, niobium carbide, tantalum carbide, chromium carbide, tungsten carbide, and molybdenum carbide.

Michael J. Wilson, David A. Goerz
Apparatus for Improving Performance of Electrical Insulating Structures
U.S. Patent 6,339,195 B1
January 15, 2002
This invention removes the electrical field from the internal volume of high-voltage structures, for example, bushings, connectors, capacitors, and cables. The electrical field is removed from inherently weak regions of the interconnect, such as between the center conductor and the solid dielectric, and placed in the primary insulation. This is accomplished by providing a conductive surface on the inside surface of the principal solid dielectric insulator surrounding the center conductor and connecting the center conductor to the conductive surface. The advantages of moving the electric fields from the weaker dielectric region to a stronger area are improved reliability, increased component life and operating levels, reduced noise and losses, and smaller, compact design. This electric field control approach is currently possible on many existing products at a modest cost. Several techniques are available to provide the level of electric field control needed. Choosing the optimum technique depends on material, size, and surface accessibility. The simplest deposition method uses a standard electroless plating technique, but other metallization techniques include vapor and energetic deposition, plasma spraying, conductive painting, and other controlled coating methods.

Earl R. Ault
Method for Beam Steering Compensation in an Ultra-High Power Liquid Laser
U.S. Patent 6,339,608 B1
January 15, 2002
Waste heat from the excitation process and absorption of laser radiation causes laser media to heat up and induces optical wavefront distortion, which in turn creates optical phase errors. This method uses a system to derive an error signal from the optical phase errors. The error signal is fed back to the power supplies for the semiconductor diodes that excite the lasing liquid. This results in the introduction of an electrically controllable wedge into the optical cavity to correct the optical phase errors.

Paul G. Carey, Jesse B. Thompson, Randy C. Aceves
Solar Cell Module Lamination Process
U.S. Patent 6,340,403 B1
January 22, 2002
Fluoropolymers are used to laminate solar cell modules and protect them from adverse environmental conditions, thus enabling more extended use of solar cells, particularly in space applications. A laminate of fluoropolymer material provides a hermetically sealed solar cell module structure that is flexible and very durable. The laminate is virtually chemically inert, highly transmissive in the visible spectrum, dimensionally stable at temperatures up to about 200°C, highly abrasion-resistant, and exhibits very little ultraviolet degradation.


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