Abstract: Low power discharge preionizers, or species, are provided by a ionizable species generator that preconditions a laser gas to eliminate arcing in lasers, such as pulsed (high repetition rate) lasers. The present invention creates the species in a low power discharge and the species prevents initial arcs from occurring between high voltage electrodes of the laser. The laser comprises a pressure vessel containing the laser gas, a fan for circulating the laser gas, a heat exchanger, a catalyst, and two high voltage discharge electrodes for exciting the laser gas to create lasing. A high voltage power source is coupled to the electrodes for providing a discharge voltage thereto. A primary auxiliary discharge source is disposed adjacent to the electrodes that is used as a preionizer that creates a low density of charged particles in the main discharge volume to act as a uniform seed for the main voltage pulse derived from the electrodes.

Abstract: A process is provided for modifying a surface of a large area, non-planar substrate to form micro structures therein that alter its optical properties. The process includes forming the micro structures by reactive ion beam etching through a chosen pattern that has been prepared on the surface.

Abstract: A pair of electrical circuits (20, 22), which may be both flexible or one flexible and one rigid, are interconnected by projections, such as bumps (24) and rings (26) . The projections are formed from substantially inelastic dielectric material, such as an epoxy defining bumps (34) and rings (36), which are plated with copper (38). Projections (24, 26) of one circuit are disposed to interconnect with mating projections on the other circuit, the interconnection being bump to bump, bump to ring, or bump to pad. The projections may be formed on a copper-clad substrate (42) or on plated-through holes (72) on a printed wiring board (70). Alternately, polygonal pads (94) on a circuit (90) may be joined to a projection. Further, a plurality of bump projections (106), electrically connected to the same or different circuits, may collectively interconnect with a single oval ring projection (108).

Abstract: An improved apparatus and method adapted for use in removing trace contaminants from the surface of a chosen substrate, such as delicate surfaces or precision parts, by application of a stream or jet spray of expanded fluid to the substrate surface. The improvement consists of controlling electrostatic charges generated on or near the substrate surface during the cleaning process.

Abstract: A process for coating a substrate with a chosen material comprising placing the substrate in a coating chamber and contacting the substrate with a mixture of the selected coating material in a chosen dense phase gas at a selected temperature and a pressure equal to or above the critical pressure of the dense phase gas for a period of time which is sufficient to allow complete penetration of the mixture into all surfaces of the substrate. Then, the phase of the dense phase gas is shifted to produce dissolution of the chosen material from the dense phase gas and to thereby form the coating of the chosen material on the substrate.

Abstract: Precise information is obtainable concerning the position of a fluid-fluid interface (28, 33), such as between a gas and a liquid or between liquids. Such information is important for the control and automation of molten metal refining processes. Specifically, in an electrolytic process for removing magnesium from molten aluminum, knowledge of the vertical position of an interface (33) between the electrolyte and the magnesium and an interface (28) between the electrolyte and the aluminum facilitates the automatic removal of the purified metals when drained or drawn from the furnace. Heat energy is conducted through a thermocouple-heater assembly 34 to a thermocouple (38) located at its tip (36). The equilibrium temperature at the thermocouple junction is dependent upon the heat loss through tip (36).

Abstract: An improved process is provided for making optical limiters having a graded axial distribution of a reverse saturable absorber compound, such as a buckminsterfullerene, in a host matrix, such as polymethyl methacrylate or polycarbonate. The process of the invention includes: (a) dissolving the reverse saturable absorber and the host matrix in a suitable solvent to form a solution having a preselected ratio of reverse saturable absorber to host matrix; (b) casting the solution onto a surface to form a film; (c) evaporating the solvent to form a free-standing film; (d) performing steps (a)-(c) for each different desired ratio of reverse saturable absorber to host matrix; (e) stacking the free-standing films in a desired order; and (f) hot-pressing the stack to form the optical limiter having a graded distribution of the reverse saturable absorber in the host matrix. If desired, the stack of films can be placed in a die for hot-pressing. The films can be pre-cut to the shape of the die.

Abstract: A plasma assembly including an RF head extending into a vacuum chamber and an associated electrode for generating a confined plasma. The assembly includes a sidewall within the chamber forming a plenum about the RF head. The plenum defines a volume substantially smaller than the volume of the chamber and hence, the gas pressure within the plenum is more easily monitored and controlled by the provision of make-up gas.

Abstract: A resin composition for investment casting contains a moderate boiling temperature liquid inert diluent, having a boiling point in the range of about 200.degree. to 300.degree. C. The presence of the liquid inert diluent allows the resin to be used as a pattern, or model, in investment casting by preventing breaking of the mold during burnout of the resin. Any of the conventional resins suitable for stereolithography may be employed in the practice of the invention. To the resin is added a moderate boiling point solvent in the amount of about 5 to 30 wt %. Use of the moderate boiling point solvent in conjunction with the resin allows the pattern to shrink and crack at moderate temperature before final burnout. The shrinkage occurs faster and at a lower temperature as compared to the prior art.

Abstract: A method of monitoring the concentration of certain plating bath major constituents such as acid is provided which is insensitive to the effects of hydrogen produced during plating. The method involves applying an ac signal superimposed on a dc potential to a sensing electrode in contact with the solution, producing an ac response current. The steady state value of the ac response current is then measured and provides an accurate indication of the acid concentration within the solution. The method can be performed using a single sensing electrode. Furthermore, the method complements and is easily integrated with known voltammetric techniques and equipment suitable for analysis of other plating bath constituents.

Abstract: Adhesives and sealants, based on polyurethane reactants, are provided. The one-component frozen premix material of the invention comprises: (a) up to about 60 vol % of at least one filler; (b) about 0.5 to 5 wt % of a thixotrope comprising hydrophobic fumed silica; and (c) the balance a urethane matrix. The urethane matrix comprises at least one polyol that includes at least one carbon-carbon double bond in its backbone and has less than 20 wt % of ether and ester moieties, at least one aliphatic polyisocyanate in stoichiometric amount relative to the polyol, and about 0.01 to 0.1 wt % of an organo-metallic catalyst. The urethanes of the invention can be stored as one-component, frozen, premix materials for a minimum of three months, and, when thawed, can be applied with a spatula or trowel to form non-sag fillets. The cured elastomers are free of voids, tears, or bubbles.

Abstract: Improved fiber reinforced composites having near zero coefficients of thermal expansion are described. The improved composites include reinforcing fibers and matrix material in which gap structures which exist within the composite are filled with a bonding agent. The reinforcing fibers can be unidirectionally, bidirectionally or multidirectionally oriented within the matrix material and articles fabricated from the improved composite have reduced coefficients of thermal expansion in directions transverse to the orientations of the fibers. This improvement makes these improved composites useful for fabricating high energy laser mirror substrates.

Abstract: A plasma is used in conjunction with a plasma assisted chemical etching material removal tool 10 to rapidly and precisely polish and smooth a substrate without mechanically contacting the surface. The pressure of a process gas, which disassociates into reactive plasma species in the presence of an applied radio frequency field, is controlled so as to allow the selection of a primarily unidirectional or a primarily omnidirectional polishing and smoothing mechanism.

Abstract: A stage 14 supporting a material removal tool 12 is instructed by a controller 16 through interface 18 to accelerate and decelerate the material removal tool 12 within at least one predetermined spatial interval while satisfying the dwell-time required to remove a predetermined amount of material to achieve a desired thickness of the spatial interval.

Abstract: Sonication is employed in the destruction of organic chemicals, using liquid carbon dioxide as the sonicating medium. The process of the invention for decomposing at least one chemical comprises: (a) providing a sonicating vessel equipped with an array of sonicators; (b) introducing the chemical to be decomposed into the sonicating vessel, together with liquid carbon dioxide; and (c) exposing the chemical in the sonicating vessel to sonication for a period of time sufficient to cause the chemical to decompose to form at least one decomposition product. The sonication process may additionally employ one or more of ultraviolet light, oxidizing modifiers such as water, sodium hypochlorite, ozone, or hydrogen peroxide, and reaction-quenching species such as hydrogen (H.sub.2).

Abstract: A system for monitoring changes in the amount of contaminants present in a flowing stream of supercritical fluid. A sample stream is removed from a flowing stream of supercritical fluid and subjected to reduced pressure. The supercritical fluid turns into gas at the reduced pressure with the contaminants remaining in a non-gaseous form. A quartz crystal microbalance system measures changes in the amount of non-gaseous contaminants present in the sample stream. The system is useful in monitoring both cleaning processes and extraction processes utilizing supercritical fluids.

Abstract: A superior thermal transfer film adhesive comprises the following composition: (a) at least one aliphatic epoxy resin; (b) a stoichiometric amount of at least one aliphatic polyamine curative; (c) an effective amount of a thixotropic agent, such as fumed silica; and (d) about 20 to 50 volume percent of at least one filler, such as alumina, based on the total of the epoxy resin and the curative. The aliphatic epoxy resin has aliphatic pendant chains of 6 to 20 carbon atoms in length. The curative comprises a long chain aliphatic or cycloaliphatic curing agent for the epoxy resin. Since aliphatic moieties, which are flexible, are used, the glass transition temperature of the resulting cured material is lower than epoxies and plasticizers employing rigid moieties. The adhesive of the invention is novel in attaining high volume resistivity (at least 10.sup.14 ohm-cm at 25.degree. C.), low temperature flexibility (-55.degree. C.), excellent adhesion for maximum thermal transfer, and ease of reworkability.

Abstract: A dual porosity electrode for use in thermoelectrochemical systems where simultaneous transport of gas and liquid into and/or out of the electrode is required. The electrode includes catalytic electrode particles having diameters ranging from about 25 to 100 angstroms. The catalytic electrode particles are anchored to a support network in clusters which have internal pores ranging in size from 25 to 100 angstroms. The pores between the clusters range in size from between about 1 to 20 microns. A method for making the dual porosity electrodes is also disclosed.

Abstract: A measurement instrument which detects the thickness of the outer layer of a wafer 24, includes a filtered white light source forming an aperture image. The white light source includes a halogen lamp 10, a condensing lens 12, a circular aperture 14, a collimator lens 16, a narrow band filter wheel 18, and a second collimator lens 20. A monochromatic beam generated by this filtered white light source illuminates the entire surface of the wafer 24 with collimated light that has passed through a third collimator lens 22. The light reflected off the wafer 24 returns through the third collimator lens 22 and forms an aperture image upon an optical device which redirects this image to a charge coupled device (CCD) camera 30. The image is converted to a map of measured reflectance data by a digitizing circuit 34 and a computer 36. This map of measured reflectance data is then self-normalized and compared to reference reflectance data to generate a map of the outer layer thickness profile of the wafer 24.

Abstract: An apparatus for shielding a plurality of wafer registration surfaces 14, 30 and a wafer retention stage 26 from depreciative effects of a chemical etching process includes a pair of etching shields 32, 32' that are positioned along an outside edge of a wafer 10. The wafer 10 is registered to the wafer retention stage 26 by the registration surfaces 14, 30. The wafer retention stage 26, and hence the wafer 10, rotates about an axis 36 through the center of the wafer 10. A chemical etching instrument probe 18 is moved, with respect to the wafer 10, along a fixed wafer diameter 34 while the wafer 10 is rotating. The probe 18 is initially positioned above a first etching shield 32' and is moved, with respect to the wafer 10, across the wafer diameter 34 until it reaches a second etching shield 32. Thus, the probe 18 scans the entire surface of the wafer 10 without extending outside the wafer edge to depreciatively effect the wafer retention materials 14, 26, 30.