Abstract: In a multiple-measurement system, a weighted sum of the measurements is used to provide a selective image. An additional weighted sum is used to provide an increased signal-to-noise ratio image. An improved selective image is formed by combining the low frequency portions of the selective image and the correct high frequency componenets from the increased signal-to-noise ratio image. To provide the correct high frequency components the error between the selective image and the improved selective image is minimized. The low-noise high-frequency image is weighted by the ration of the cross correlation of the selective andlow noise images divided by the autocorrelation of thelow noise image.

Abstract: There is disclosed herein an apparatus for converting control signals of an electrical or optical nature of any other type or signal which may be converted to a change of temperature of a fixed volume of material trapped in a chamber to flexure of a membrane forming one wall of the chamber. Typically the device is integrated onto a silicon wafer by anisotropically etching a trench into said wafer far enough that a thin wall of silicon remains as the bottom wall of the trench. In some embodiments, polyimide is used as the material for the membrane. The trench is then hermetically sealed in any one of a number of different ways and the material to be trapped is either encapsulated during the sealing process or later placed in the cavity by use of a fill hole. Typically, a resistor pattern is etched on the face of a pyrex wafer used as a top for the trench to form the cavity. When current is passed through this resistor, the material in the cavity is heated, its vapor pressure increases and expansion occurs.

Abstract: A bipolar transistor in which the base region includes a heterostructure and a doped layer of semiconductor material with the heterostructure functioning as a two-dimensional hole gas. The doped layer is sufficiently thin to prevent occurrence of a charge-neutral region of holes. In operation the transistor can switch quickly since minority charge storage in the base region does not present a problem. The device lends itself to downscaling in size in a VLSI circuit.

Abstract: Disclosed is a method of welding a temperature-sensing thermocouple to a silicon wafer for sensing the temperature of the wafer during rapid thermal processing using TIG welding and/or electron-beam welding. In one embodiment, a ball of silicon is formed on the bead at one end of a thermocouple by placing the thermocouple on a silicon chip and then melting the silicon chip with a TIG welder. The ball and thermocouple are then placed on the surface of a silicon wafer and the ball and surface are then melted whereby the ball of silicon flows into the silicon wafer. In placing the thermocouple on an edge portion of a silicon wafer, the wafer is supported on a tantalum plate with the edge portion of the wafer extending beyond the plate. A molybdenum sheet is positioned on the top surface of the wafer with the edge portion of the wafer exposed. A TIG arc is established with the molybdenum layer and then the arc is moved to the edge portion of the wafer for melting the silicon.

Abstract: Programmable logic gate structures employ pairs of complementary transistors. Programming of the transistors is accomplished either by voltage biasing a shared floating gate of a CMOS transistor pair or by providing a variable resistance serially or in parallel with each transistor. The variable resistance can be a fusible link or a semiconductor device having an alterable crystalline structure.

Abstract: A two-dimensional projection image of the NMR activity within a volume is obtained. The signals due to static material are not excited and do not appear in the projection image. The signals due to moving blood in vessels produce an isolated image of the vessels with the superimposed structure removed. Excitation systems are used which excite only moving material and return static material to equilibrium. A 180.degree. excitation provides immunity to inhomogeneity.

Abstract: A catheter for use in treating tumors is flexible and relatively small in diameter so that it can be inserted interstitially into the tumor mass. A conductor is provided about a length of the catheter and is electrically insulated except for a small length or small lengths thereof which are adapted to be received within the tumor volume. By connecting the conductor to a high frequency power source a heat producing current can be generated through the tumor tissue adjacent the exposed portions of the catheter to damage the tumor cells. One or more temperature sensing devices are included in the catheter and are located adjacent to the exposed conductor or conductors for monitoring the temperature of the adjacent tumor tissue. The signals from these devices, which are picked up from a connector at one end of the catheter, can then be used to control the current to the conductor or conductors so as to maintain the tumor volume at a constant and uniform desired temperature.

Abstract: An endless wire saw in which a workpiece is placed in pressure engagement with the wire and a cutting material carried by the wire slices through the workpiece. The cutting material may be a slurry such as a glycerin fluid carrying silicon carbide particles.

Abstract: Diseased tissue such as cirrhotic liver is differentiated from normal tissue by applying an ultrasound wave to the tissue, receiving backscattered ultrasound waves therefrom and bandpass filtering electrical signals generated from the backscattered wave. Assuming that the ultrasound wave has a spectrum and a center frequency, the bandpass is narrow relative to the spectrum and centered within the bounds of the spectrum of the ultrasound wave. The filtered signal will have an amplitude distribution for diseased tissue which is different from the amplitude distribution of normal tissue.

Abstract: A catheter for use in treating tumors is flexible and relatively small in diameter so that it can be inserted interstitially into the tumor mass. A conductor is provided along the length of the catheter and is electrically insulated except for a small length thereof which is adapted to be received within the tumor volume. By placing at least a pair of such catheters within the tumor mass and by connecting the conductors to a high frequency power source a heat producing current can be generated through the tumor tissue between the exposed portions of the catheter to damage the tumor cells. In addition, each catheter includes an axial passage permitting radioactive seeds or other tumor treating materials to be inserted within the tumor mass to cause further damage to and ultimately necrosis of the tumor without significantly affecting the adjacent healthy tissue of the body.

Abstract: A semiconductive diode pumped Nd:glass laser is disclosed in which standard low-loss Nd:glass is employed as the gain medium. In some embodiments, miniature optical resonators are employed for resonating the lasant radiation within the gain medium. One or more of the reflectors of the optical resonator are preferably defined by one or more faces of the glass gain medium. Travelling wave, Q-switched, modelocked, second harmonic generating, and slab laser embodiments are disclosed.

Abstract: In magnetic resonance imaging where a subject is placed in a static field and the subject is selectively excited by applying an RF magnetic field in the presence of a gradient magnetic field, the peak RF power of the RF magnetic field is reduced by decreasing the peak amplitude of the RF magnetic field while concurrently reducing the magnitude of the gradient magnetic field. The incremental time duration for the RF magnetic field portion which is reduced in amplitude is proportionately increased. In using an RF pulse having front and back sidelobes with a positive lobe therebetween, the duration of the RF pulse can be reduced by increasing the magnitudes of the sidelobes and concurrently reducing the time periods of the sidelobes. A minimum SAR embodiment can be realized.

Abstract: Disclosed is a technique for probing dynamic sheet charge density variations in integrated semiconductor devices. Using a specially designed non-invasive Nomarski phase contrast interferometer a sheet charge density sensitivity of 2.6.times.10.sup.8 e/cm.sup.2 / .sqroot.Hz is extracted from experimental data for 1 mA of detected photocurrent. The charge density sensitivity makes possible .mu.V signal level detection in an active device, and with digital signals the corresponding signal/noise level is sufficiently high that multi-mega-baud data can be captured in real time.

Abstract: A photodetector for detecting signal pulses transmitted in an optical carrier signal relies on the generation of electron-hole pairs and the diffusion of the generated electrons and holes to the electrodes on the surface of the semiconductor detector body for generating photovoltaic pulses. The detector utilizes the interference of optical waves for generating an electron-hole grating within the semiconductor body, and, by establishing an electron-hole pair maximum at one electrode and a minimum at the other electrode, a detectable voltaic pulse is generated across the electrode.

Abstract: An analog function generator useful in providing a variety of functions for analog signal processing applications includes a pulse width modulator and a switched capacitor operational amplifier. Capacitors in the input of the operational amplifier and in the feedback loop of the operational amplifier are selectively switched by the output of the modulator to create output voltages of the amplifier that are polynomial, logarithmic or exponential functions of the input voltages to the amplifier and pulse width modulator.

Abstract: The invention relates generally to the field of signal processing for signal reception and parameter estimation. The invention has many applications such as frequency estimation and filtering, and array data processing, etc. For convenience, only applications of this invention to sensor array processing are described herein. The array processing problem addressed is that of signal parameter and waveform estimation utilizing data collected by an array of sensors. Unique to this invention is that the sensor array geometry and individual sensor characteristics need not be known. Also, the invention provides substantial advantages in computations and storage over prior methods. However, the sensors must occur in pairs such that the paired elements are identical except for a displacement which is the same for all pairs. These element pairs define two subarrays which are identical except for a fixed known displacement.

Abstract: The magnetic resonance activity of a region of a volume is imaged using a time varying gradient whose integral provides a constant velocity spiral in the spatial frequency domain. To provide high fidelity for relatively low values of T.sub.2, high SNR for relatively high values, and a T.sub.2 sensitive image, the spiral is retraced back to the origin. The gradient requirements are minimized using a sequence of interleaved spirals using separate excitations. For further time reduction, only half the spatial frequency domain can be scanned, using inversion excitations to reduce the effects of inhomogeneity.

Abstract: A second harmonic, optical generator is disclosed in which a laser diode produces an output pumping beam which is focused by means of a graded, refractive index rod lens into a rod of lasant material, such as Nd:YAG, disposed within an optical resonator to pump the lasant material and to excite the optical resonator at a fundamental wavelength. A non-linear electro-optic material such as MgO:LiNbO.sub.3 is coupled to the excited, fundamental mode of the optical resonator to produce a non-linear interaction with the fundamental wavelength producing a harmonic. In one embodiment, the gain medium and the non-linear material are disposed within an optical resonator defined by a pair of reflectors, one of which is formed on a face of the gain medium and the second of which is formed on a face of the non-linear medium. In another embodiment, the non-linear, electro-optic material is doped with the lasant ion such that the gain medium and the non-linear doubling material are co-extensive in volume.

Abstract: A monolithic phasematched harmonic generator is obtained by optically pumping an optically nonlinear lasant member having reflective faces defining the monolithic optical resonator. Phasematching is achieved, in one case, by inclining a totally internally reflective face of the resonator at a proper angle relative to other faces of the resonator to angularly separate and resonate lasant waves of the proper polarization. In a second case, a clad fiber resonator of optically nonlinear lasant material has its cladding arranged to guide and thus resonate only lasant waves of the correct polarization. In a third case, the optical nonlinear coefficient of the optically nonlinear lasant material is spatially modulated with a period equal to an odd integer number of coherence lengths, of the harmonic generation process, to obtain quasi-phasematched operation. Phasematched operation improves the efficiency of the harmonic generation process.

Abstract: A fiber optic rotation sensor, employing the Sagnac effect comprising all fiber optic components positioned along a continuous, uninterrupted strand of fiber optic material. The rotation sensor includes a detection system utilizing a modulator or modulators for phase modulating at first and second frequencies light waves which counter-propagate through a loop formed in the fiber optic strand. The second modulation frequency is much lower than the first frequency. An output signal from the sensor is gated synchronously with respect to the phase modulation at the second frequency so that the detected optical output signal is provided only during selected intervals of the phase modulation at the second frequency.A phase sensitive detector generates a feedback error signal proportional to the magnitude of the optical output signal at the first phase modulation frequency.