Abstract: A method of isolating individual heterojunction bipolar transistors (HBTs) on a wafer increases the current gain which can be obtained when using proton implantation to isolate the transistor. The photoresist pattern which is used to cover the transistor location during isolation implantation is undercut when etching the cap layer. A dielectric is then deposited on the etched surface, including the undercut portion. The photoresist is lifted off and an HBT is fabricated on the wafer in the area which is not covered by the dielectric. The dielectric on the undercut portion confines the emitter current to a region slightly removed from the isolation implant and provides improved current gain.

Abstract: A monitor is provided for measuring and controlling the strain rate of a blank during forming. A light source directs light against the blank and a video camera is positioned and focused to view the light reflected from the blank while it is being formed. A video monitor and an image processor receive the signal from the camera. This signal is used to determine the strain rate based upon the dimensional change in reference marks on the blank. The image processor provides an output signal which can be used to control the strain rate in accordance with a predetermined strain rate profile for the particular part being formed.

Abstract: A gold(III) acetate is formed by dissolving gold(III) hydroxide in glacial acetic acid. This solution containing gold(III) acetate can be used to form a gold-containing film by heating it above about 60.degree. C. and then casting it to form a film. Gold can be deposited from the film by heating it to about 175.degree. C. to decompose the film. In this manner, a line or pattern of conductive gold can be formed by heating selected portions of the film with a laser.

Abstract: Nickel base alloy sheets are diffusion bonded together at a temperature which is low enough to retain the superplastic properties of the nickel base alloy. A foil and a screen of type 300 series stainless steel are placed between the sheets in the area to be bonded. This assembly is sealed in an envelope and maintained in a vacuum to protect the surfaces from oxidation, and placed within the heated platens of a press. The assembly is heated to a temperature below which rapid grain growth occurs, and sufficient pressure is applied by the press to deform the screen to create continuous contact between the surfaces to be bonded. Diffusion causes bonding of the sheets in less than six hours at temperature, without destroying the superplasticity of the nickel base alloy. In an embodiment of the invention, gas pressure is applied between the sheets in a location away from the bond to superplastically form the sheets during the bonding process.

Abstract: The invention provides an etchant and a method of using the etchant for revealing dislocations on low index planes in group II-VI compounds such as (Hg.sub.x Cd.sub.(1-x))Te. The etchant has a composition proportional to 80 ml water, 10 ml of hydrochloric acid, 20 ml of nitric acid, and 8 gm of potassium dichromate. In another embodiment, the concentration of nitric acid is reduced to 0%. The surface of the compound being examined is exposed to the etchant for about 20 second to 6 minutes depending upon the crystallographic plane being examined. The surface is then rinsed in water. For the {111}B plane, additional rinses in a 0.05% solution of bromine in methanol and methanol are used.

Abstract: A meter measures the flow rate of a mixture by measuring a frequency characteristic of microwave propagation within a waveguide which forms a part of the conduit through which the mixture flows. Spaced apart slots in the waveguide form transmitting and detecting antennas which are connected to the output ports of a microwave bridge. An oscillator generates microwaves which are fed to the input of the microwave bridge. The output of the bridge is the difference in power transmitted through the two antennas. This signal is fed to a phase sensitive detection system and the output can be correlated to the flow rate of the mixture. In one embodiment, a computer control unit and computer controlled switches are provided to switch the microwave bridge in and out of the circuit so that both the flow rate and the concentration of an ingredient can be measured.

Abstract: A device is provided for suspending an external load by means of a magnetic field and a superconductor. The superconductor is supported in a magnetic field which penetrates the superconductor. A magnet is suspended below the superconductor and oriented so that its magnetic moment is aligned parallel to the magnetic field. The magnet is provided with a coupling means so that it can be coupled to an external load. Either a vertical or a horizontal magnetic field can be used. In one embodiment, the load-carrying member is a composite material suspended from a supported magnet. The composite consists of a superconducting phase and an attractive phase comprising either a magnet, a ferromagnetic material, or a paramagnetic material. In another embodiment, a device for concentrating flux is provided by placing a superconductor between the source of the magnetic field and the position in which the concentrated flux is desired.

Abstract: A velocimeter and a method for measuring the velocity of a printing press web are provided. The velocity is measured without contacting the web by measuring a speckle pattern which is reflected off the moving web by a laser. The reflected light is filtered and detected by a linear photodetector array which is differentially connected. The photodetector array output is fed into a differential amplifier to obtain a differenced output which has a frequency that is related to the velocity of the web. The difference output is filtered through a variable filter set at a predetermined bandpass center frequency and bandwidth, and its frequency is counted to obtain the approximate velocity of the web. Using the approximate velocity, a bandpass center frequency and bandwidth is selected which provides a substantially linear response of velocity at the counted frequency. The variable filter is reset to the selected bandpass center frequency and bandpass, and the frequency of its output is obtained.

Abstract: A method and an apparatus are provided for measuring the pressure of a gas within a sealed vessel. A sonic transducer is used to apply an oscillating force to the surface of the vessel. The frequency of the ultrasonic wave is swept through a range which causes resonant vibration of the gas in the vessel. A receiving transducer measures the amplitude of the resultant vibration at the vessel surface and reveals the resonant frequency of the gas as peaks in the amplitude of the sweep. The resonant frequency obtained depends upon the composition of the gas, its pressure and temperature, and the shape of the confining vessel. These relationships can be predetermined empirically so that the pressure inside the vessel can be calculated when the composition of the gas, its temperature, and shape of the confining vessel are known. The output of the receiver is fed into a computer which is programmed to calculate the pressure based upon these predetermined relationships which are stored in the computer.

Abstract: The dynamic viscosity of a viscous medium is measured by positioning an acoustic transducer in the temperature and pressure environment of the medium and spaced from the medium, then measuring a first resonant frequency and bandwidth for acoustic shear wave propagation within the transducer. The transducer is then positioned in surface contact with the medium, and a second resonant frequency and bandwidth are measured. The viscosity of the medium is calculated from the difference between the first and second resonant frequencies and bandwidths. The step of measuring a first resonant frequency and bandwidth involves applying a first input signal to the transducer to generate acoustic shear waves within the transducer, measuring the frequency and amplitude of the output signal produced by the transducer in response to the acoustic shear waves, and repeating the steps of applying and measuring for a range of first input signal frequencies to determine a first resonant frequency and bandwidth for the transducer.

Abstract: A softer metal such as aluminum, or a metal forming a metal aluminide, or an alloy containing these metals is added to a metal aluminide composite during fabrication to promote easy consolidation of the metal aluminide matrix with the reinforcing phase. The metal aluminide may be titanium aluminide, nickel aluminide, or iron aluminide. The softer metal, the metal aluminide matrix, and the reinforcing phase are pressed together at a temperature above the softening temperature of the softer metal. The softened metal promotes flow and consolidation of the matrix and the reinforcement at relatively low temperatures. The composite is held at an elevated temperature to diffuse and convert the soft metal phase into the metal aluminide matrix. By consolidating at a lower temperature, cracking tendencies due to thermal expansion differences between the matrix and reinforcement is reduced. By consolidating at a lower pressure, mechanical damage to the fibers is avoided.

Abstract: The invention is a layered nonalloyed ohmic contact structure for use on n type gallium arsenide including a layer of germanium or silicon of the order of 10 .ANG. thick evaporated onto the gallium arsenide; a diffusion barrier layer of material 100-200 .ANG. thick over the germanium or silicon selected from non-metallic conducting compounds, including metal compounds ofarsenidephosphidecarbideboridenitridesilicideand non-metallic conducting elements; with the diffusion barrier layer material characterized by resistivity of the order of 1 ohm cm or less; and a conducting metal overlayer on the diffusion barrier layer. The invention includes the method for manufacturing the contact structure.

Abstract: A gradient index filter can be fabricated with integral antireflection properties without degrading the inband performance of the filter. The filter is for placement between an incident medium and a substrate to reflect incident electromagnetic energy having wavelengths within a predetermined band of wavelengths and to transmit incident electromagnetic energy having wavelengths outside of the reflection band. The filter includes an antireflecting portion having a nominal refractive index profile selected to reflect a minimum amount of electromagnetic energy from a theoretical interface between a first medium having a first predetermined refractive index and a second medium having a second predetermined refractive index. A band rejecting portion has a periodic refractive index profile whose periodicity and amplitude are selected to reflect a maximum amount of electromagnetic energy within the relfection band.

Abstract: A conductive or semiconductive pattern of a metal sulfide or selenide such as copper, cadmium, cobalt or nickel sulfide, is provided on a substrate. The pattern may have a resistivity in the range of 1 to 10.sup.6 ohms per square. It is formed by coating the surface with a solution containing a salt of one of the metals which is capable of being converted to a divalent metal compound, a sulfur group donor such as thiourea, and a solvent such as methanol or water. The solution is dried, and then selected portions of the coated surface are irradiated with a laser beam. This thermally converts the irradiated metal salt into a metal sulfide. The unreacted solution is then washed from the substrate to leave a conductive pattern. The desired conductivity of the pattern can be obtained by selecting the proper metal salt, concentration of salt in the solution, and the energy of the radiation.

Abstract: A heterostructure complementary transistor switch (HCTS) is fabricated using epitaxial layers on a substrate to form the desired P-N-P-N (or N-P-N-P) complementary structure in III-V compound semiconductor materials. Two HCTS are formed on a single substrate to form a memory cell. A collector and a base on one of the HCTs are connected to a base and a collector, respectively, on the other HCTS to form the memory cell.

Abstract: An aluminum alloy is provided which has a surface with a fine grain structure. It is produced by overaging an aluminum alloy and then cold working only the surface by shot peening or other surface working technique. The alloy is then heated so that the overaged, cold-worked surface recrystallizes into a fine grain structure.

Abstract: The crystallographic plane-dependent, amphoteric nature of Si-doped AlGaAs is used to provide a low threshold semiconductor laser. An active layer of AlGaAs is sandwiched between an injection layer and a current confining layer of AlGaAs. The injection layer is doped to be n-type conductivity. The confining layer is amphoterically doped with Si to be n-type in a (100) plane and p-type in a (111)A plane. The resulting p-n junctions, heterostructure, and geometry provide the current and the optical confinement for the semiconductor laser.

Abstract: An ultrasonic viscometer is described which is particularly designed for monitoring the viscosity of a thermally curing resin or composite, such as a fiber-reinforced epoxy composite, in an autoclave at high temperature. According to a preferred embodiment, the viscometer comprises a piezoelectric element of lithium niobate crystals bonded to a first buffer of copper, which is bonded on the other side to a second buffer of aluminum. The resin or composite is in contact with the second buffer. When the transducer emits a short ultrasonic pulse, two echoes are reflected back, the first echo being generated by the copper-aluminum interface, the second by the aluminum-resin interface. The signals from the two echoes are processed to obtain the complex reflection coefficient at the interface of the second buffer and the resin, from which the viscosity of the resin can be calculated and the cure state of the resin determined.

Abstract: A method of fabricating an optical coating includes a layer pair, with a layer of a first optical material having a first refractive index and a first nominal thickness and a layer of a second optical material having a second refractive index and a second nominal thickness. The first layer is deposited, then its actual thickness is measured. A target thickness for the second layer is determined so that the optical properties of the combined actual first layer and target second layer are substantially the same as the optical properties of the combined nominal first layer and nominal second layer. The second layer is then deposited. Where the optical coating further includes a plurality of layer pairs, the steps of depositing, measuring, determining, and depositing are repeated for each of the layer pairs in the pairwise approach.

Abstract: Silicon doping of GaAs provides n conductivity in {100} planes and p conductivity in {111} A planes. A split level of Si-doped GaAs utilizes this phenomena to provide a bipolar transistor. In one embodiment, the emitter is one level of the layer in the {100} planes, and the collector is another level of the layer in the {100} planes. These n conductivity levels are joined by {111} A planes to form a p conductivity base. The junctions in the layer between the {100} planes and the {111} A planes form an npn transistor.