Abstract: A dissolved wafer process is modified by providing an etch control seal around the perimeter of an etch resistant microstructure, such as a micromechanical or microelectromechanical device, formed on a first substrate. The microstructure is defined and shaped by a surrounding trench in the first substrate. Selected areas of the microstructure and the first substrate are bonded to an etch resistant second substrate. The selected bonding areas may comprise raised areas of the first substrate, or raised areas of the second substrate corresponding to the selected bonding areas of the first substrate. A bonded area forming a ring extending around the perimeter of the microstructure and its defining trench forms an etch control seal. The first substrate of the bonded assembly is dissolved in a selective etch so that the etch resistant microstructure remains attached to the second substrate only at the bonded areas.

Abstract: A method and apparatus are provided for filtering incident radiation to protect imaging sensors from the damaging effects of high intensity radiation. The apparatus comprises a filter and a plurality of mirrors disposed within a cube. The filter is positioned diagonally within the cube so that portions of the incident radiation reflected by the filter are directed to a beam-stop on a surface of the cube. Portions of the radiation passed by the filter are directed by the mirrors to pass through the filter a plurality of times. Passing the radiation through a single filter a plurality of times provides a high density imaging system in a physically compact geometric shape. A focused beam passes through the filter in regions of successively greater optical gain. High intensity radiation thermally activates the filter to reject the radiation and protect the sensors.

Abstract: An electronic circuit extracts a ratio of currents from two sources and provides an output that is a function of the current ratio. An embodiment of the circuit includes a source current that may be provided by a blue-green photodetector and a sinking current that may be provided by a red photodetector. The source current feeds the input of a current splitter formed by a pair of PFETs. A portion of the source current is fed from the current splitter to a current ratio extractor implemented in CMOS. The remaining portion of the current from the current splitter is fed to a node shared with the sinking current and a second input to the current ratio extractor. The current ratio extractor produces an output voltage that is a function of the ratio of the photodiode currents and is substantially independent of the total current.

Abstract: A continuous wave Doppler radar system having a transmitter module and a receiver module is provided for automotive vehicles. Each module includes an antenna system, including a horn, a lens, and a waveguide system, which is attached to a monolithic microwave integrated circuit (MMIC) chip that provides all necessary electronic functions. Each MMIC chip may be attached to a metal base heat sink, which may be conveniently connected to a base plate heat sink that holds the entire radar assembly. The transmitter module includes a voltage controlled oscillator (VCO) that generates a VCO frequency signal which is amplified and switched sequentially to three multiplier chains for transmission in three different directions. Each transmit signal is taken off the MMIC chip by a dielectric waveguide and directed to the antenna system. The receiver module includes three receivers that are selected sequentially to provide a beam azimuth scanning function.

Abstract: A fast, nondestructive, and easy to perform method of Potentiometric Evaluation of Substrate Oxidation ("PESO") is provided. A coated part to be analyzed is placed in contact with an electrolytic solution having a pH adjusted to provide an optimum oxide dissolution rate. The open circuit potential of the part is monitored as the substrate oxide dissolves in the electrolytic solution. The voltage typically changes as a function of time during oxide dissolution. When oxide dissolution is complete, the voltage reaches a steady value associated with active dissolution of the substrate metal and reduction processes on the coating. The electrolytic solution can be flowed or agitated to reduce concentration polarization, provide more meaningful voltage measurements, and minimize the time required for analysis. The time required to reach a steady-state voltage provides a measure of the amount of substrate oxide within pores in the coating.

Abstract: An analog VLSI circuit having a network of resistive elements and switches is provided for discriminating between an object and the background in a sensor image of a scene. A sensor system captures two-dimensional visual images and identifies edges of objects. The output of the imaging system is mapped onto the switched resistive grid. The presence of object edges causes switches to open at corresponding grid points in the resistive network. The periphery of the grid is connected to a first voltage, while a central point of the grid is connected to a second voltage. An edge map contour of open switches surrounding the central point causes the voltage at every point within the contour to rise to the second voltage, while every grid point outside the contour settles to the first voltage. Thus, the object enclosed by the edge map contour is labeled or tagged with the second voltage and the surrounding background is characterized by the first voltage.

Abstract: A dissolved wafer micromachining process is modified by providing an etch control seal around the perimeter of a heavily doped micromechanical structure formed on a substrate. The micromechanical structure is fabricated on a wafer using conventional methods including the formation of a trench that surrounds and defines the shape of the micromechanical structure in the substrate. The etch control seal comprises a portion of the substrate in the form of a raised ring extending around the perimeter of the micromechanical structure and its defining trench. Selected raised areas of the heavily doped micromechanical structure and the top of the raised etch control seal are bonded to a second substrate. A selective etch is then used to dissolve the first substrate so that the heavily doped micromechanical structure remains attached to the second substrate only at the bonded areas.

Abstract: A method is provided for monitoring and controlling the deposition of multiple layer thin films using a broadband spectral monitor and a generalized model of the film. A design specification, including the number of layers and the material, refractive index, and thickness of each layer, is provided for the desired thin film. A target optical thickness is computed for the end point of each layer using correction factors based on the generalized model, preferably a single layer model, of the multilayer thin film. A monitor chip, such as a silicon substrate, is used for monitoring the multiple layers of film deposition. During deposition of the film, a broadband spectral monitor (BBSM) comprising a source of broadband light is directed onto the monitoring chip. Light reflected by the monitoring chip is received by a photosensor that provides a broadband reflectance spectrum to a computer.

Abstract: A sequential electrochemical reduction method and apparatus are provided for assessing and restoring solderability of electronic component leads. The method detects and quantifies the presence of metallic oxides that are detrimental to solderability by sequential electrochemical reduction in contact with an electrolyte in an inert atmosphere. A cathode having a high hydrogen overvoltage is placed in contact with the electrolyte. A solderable portion of the component to be tested is placed in contact with the cathode and the electrolyte. An inert counter electrode and a reference electrode are also placed in contact with the electrolyte. A current is passed between the cathode and inert electrode, and the voltage and current are measured as a function of time during reduction of metallic oxides on the solderable portions of the component.

Abstract: An electrical capacitor includes an organic electrolyte to provide high power, high energy density, and broad operating temperature range. The capacitor includes electrodes and an electrolyte system comprising a salt combined with a solvent containing a nitrile. The electrolyte system is selected to be relatively nonreactive and difficult to oxidize or reduce so as to produce a high electric potential range. As examples, the electrolyte may include a solvent selected from the group consisting of acetonitrile, succinonitrile, glutaronitrile, propylene carbonate, and ethylene carbonate; a salt cation selected from the group consisting of tetraalkylamonium (R.sub.4 N.sup.+) and alkali metals; and an anion selected from the group consisting of trifluoromethylsulfonate (CF.sub.3 SO.sub.3.sup.-), bistrifluoromethylsulfurylimide (N(CF.sub.3 SO.sub.2).sub.2.sup.-), tristrifluoromethylsulfurylcarbanion (C(CF.sub.3 SO.sub.2).sub.3.sup.-), tetrafluoroborate (BF.sub.4.sup.-), hexafluorophosphate (PF.sub.6.sup.

Abstract: A system is provided for regenerating reducing agents used in ancillary chemical or electrochemical processes such as restoring solderability of electronic components to be soldered in a fluxless soldering process. The system includes a cathode, an anode, and an electrolyte system that is separated by a semipermeable ionic barrier into a catholyte and an anolyte. The catholyte includes the reduced member of a redox couple, which can be regenerated electrochemically. The redox couple of the electrolyte system is charged like a battery and discharged during the ancillary process. Regeneration of the reduced member of the redox couple is accomplished at the cathode, which may evolve hydrogen gas. Chemical balance is maintained by the semipermeable ionic barrier, which permits proton migration from the anolyte to the catholyte but acts as a barrier against diffusion and migration of cations from the catholyte to the anolyte.

Abstract: A method is provided for depositing a uniform thin film on a substrate using laser ablation of a target material in a deposition chamber. The laser beam may be pulsed and focused to strike the target along a line to produce a broad plume of ablated material expanding in a propagation direction outward from the target. The plane of the substrate deposition surface is oriented generally parallel to the propagation direction of the plume of ablated material. The deposition chamber includes a low background pressure of inert or reactive gas to facilitate lateral diffusion of ablated atoms, ions, and molecules to be deposited on the substrate surface. Particles ejected from the target material, which have trajectories generally parallel to the propagation direction of the plume, are too heavy to have significant lateral diffusion and have little chance of lodging on the deposition surface.

Abstract: A vehicular traffic monitoring system incorporates an array of photosensors and a nonlinear resistive network for identifying, locating, and processing outliers in sensor images of a highway or intersection. The camera system can be mounted on a pole or overpass to provide an image of the roadway or intersection. Areas of the outlier network ("video loops") are designated to correspond to selected areas of the roadway. Images are received by the outlier detection network with all data path switches closed between sensor elements and their corresponding network nodes. The system detects the presence of objects in the image by comparing the brightness or intensity of each pixel with that of the background. If the intensity of a pixel is significantly different from the background level, the data path switch corresponding to that pixel is opened. A readout of the state of all the switches in the network yields a map of outlier points for each video frame.

Abstract: Apparatus for assessing solderability of electronic component leads and printed wiring boards by sequential electrochemical reduction. The apparatus detects and quantifies the oxides present on copper, solder, andintermetallics that are detrimental to solderability. A solderable portion of the component to be tested is immersed in an electrolyte to form an electrode. An inert counter electrode and a reference electrode are also placed in the electrolyte. A current is passed from the inert counter electrode to the tested component, and the potential between the component and the reference electrode is recorded as a function of time. In a plot of the electrode potential versus the total charge passed, a series of inflection points identify and quantify particular metallic oxides present on the solder. The plot is compared with previous analyses of aged specimens having known oxide compositions that correlate with degradation of solderability.

Abstract: A voltage amplifying source follower circuit provides an output gain characteristic greater than unity with low overall noise. The circuit typically comprises a source follower FET with additional FETs to sense the output voltage and change the load current in a direction opposite to a change in the input voltage. In response to an input voltage change, the load current is varied by the source follower circuit so that the corresponding output voltage change is amplified beyond that of the input voltage change. By varying the load current in a direction opposite to the effect of a load resistance, the source follower gain is increased to greater than unity. When the input voltage increases, the output voltage increases even more because the load current is decreased correspondingly. The compact amplifying circuit can be fabricated on an integrated circuit chip outside critical unit cell areas of a focal plane array.

Abstract: A method is described for transferring a thin film of arbitrarily large area from an original substrate to an alternate substrate. An etch stop layer is provided below an epitaxial layer, for example, grown on a semiconductor substrate. In a single transfer process, the epitaxial layer is bonded to a rigid host substrate having desirable thermal, electromagnetic, and/or mechanical properties. The original growth substrate is then removed from the transferred epitaxial layer using the etch stop layer. In a double transfer process, the epitaxial layer is first bonded to a rigid and porous temporary substrate using a thermally or chemically releasable resin, for example. The original growth substrate is removed using the etch stop layer so that the original substrate side of the epitaxial layer can be bonded to a rigid host substrate, as described above. The temporary substrate is then removed using the releasable resin to leave the transferred thin film attached to the host substrate.

Abstract: A monolithic quasi-optic amplifier is provided for co-linear beam propagation in the millimeter wave frequency range (30-300 GHz). The amplifier comprises a multiplicity of unit cells that act as nearly independent amplifiers. Each unit cell includes a GaAs transistor, a slot antenna, a patch antenna, a microstrip line, and a DC bias provided by a ground plane that routes non-radiating transmission lines without interference. The slot antennas on GaAs provide preferential directionality in receiving the input waves. A vertically polarized input wave couples energy into each unit cell through the slots in the ground plane, through the microstrip lines, and to the base of each transistor. After amplification by the transistors, the signal is fed to the patch antennas, which generate a horizontally polarized output wave. The size of each patch antenna, which is determined by the operating frequency, is approximately 1 mm by 1 mm in GaAs at 44 GHz.

Abstract: A multiplexed optical fiber readout system is coupled to an array of scintillators, such as BGO crystals, for determining position and energy of radiation events in gamma ray imaging systems. Each scintillator in an N.times.M array is coupled to a pair of step-index-of-refraction, wavelength shifting, fluorescent fibers. The fluorescent fibers are arranged in N rows and M columns (or other indexed scheme) such that each scintillator is coupled to one row fiber and one column fiber, for example. The fluorescent fibers are coupled to clear optical fibers terminating at high quantum efficiency photon counters. Readout of the array of scintillators is accomplished by detecting coincident fluorescent photons in orthogonal pairs of the N+M fibers. By multiplexing the readout on row and column fibers, the number of signal channels is reduced by a factor of (N+M) / (N.times.M), which can greatly reduce cost or increase resolution compared with existing gamma ray imaging systems.

Abstract: An electronically scanned buffered direct injection (ESBDI) readout circuit is provided for a long wavelength infrared focal plane array (IR FPA). The ESBDI circuit comprises a cascoded CMOS inverter amplifier that allows high detector cell density and provides high voltage amplification, low input impedance, high charge capacity, and high sensitivity in a low power staring focal plane array. The amplifier employs a cascode FET to stabilize the amplifier operating point and to provide low noise access for each unit cell. Distributed capacitance along each bus line provides large overall charge capacity in a minimum of chip real estate. When not accessed, idle IR detector cells are clamped to an externally adjustable voltage to prevent excess detector noise and crosstalk. The circuit may be fabricated on a neutron transmutation doped silicon wafer to provide threshold uniformity and low power dissipation.

Abstract: A method for real time processing of information received from a plurality of permanent magnets embedded in the pavement of an Intelligent Vehicle Highway System. A sequence of magnet orientations provides coded information to sensors mounted on automotive vehicles. The method uses a combination of extended Kalman filtering and Schweppe likelihood estimation to determine the relative location and orientation of the magnets. A separate location estimator (extended Kalman filter) is provided for each of the possible magnet orientations. A decision process identifies the most likely orientation of the magnet, and the Kalman filter selected by the process contains the best estimate of the location of the magnet. Schweppe likelihood estimation is extended to use the detector as a decoder of the information provided by the orientation sequence of the magnets.