A medical catheter (10) for treating atherosclerotic plaque (16) and other abnormalities includes optical fibers (30) for applying laser energy to the plaque (16) and an ultrasonic transducer system (32, 34) for sensing the location and configuration of the plaque (16). The optical fibers (30) and electrical wiring (40) for the transducers (32, 34) extend through a probe (28) which is rotatable inside of the catheter tube (12) to provide universal directional control of the fibers (30) and transducers (32, 34). A reflective system includes a curved reflector (38) in the probe (28) which can be axially adjusted to vary the directions of the ultrasonic signals. Alternative forms of the invention include different reflector schemes, an angled ultrasonic transducer (32, 34) having a conical signal output that varies with frequency, and various different systems for rotating the transducers (32, 34) and fibers (30).

Catheter for laser treatment of atherosclerotic plaque and other tissue abnormalities

An atomic layer deposition method includes positioning a plurality of semiconductor wafers into an atomic layer deposition chamber. Deposition precursor is emitted from individual gas inlets associated with individual of the wafers received within the chamber effective to form a respective monolayer onto said individual wafers received within the chamber. After forming the monolayer, purge gas is emitted from individual gas inlets associated with individual of the wafers received within the chamber. An atomic layer deposition tool includes a subatmospheric load chamber, a subatmospheric transfer chamber and a plurality of atomic layer deposition chambers. Other aspects and implementations are disclosed.

Atomic layer deposition methods and atomic layer deposition tools

A spacer for items includes a waveguide 28.1 for radio frequency signals and a crate 16.1 or pallet. When items 16.1 to 16.9 in an array are spaced with such waveguides, signals from an interrogator 12 of an RF electronic identification system 10 are guided via the waveguide to transponders 14.1 to 14.9 of the system mounted on the items. Response signals from the transponders are similarly guided in the reverse direction, so that the transponders may be read. The spacer, arrangement and methods according to the invention alleviate the problems presented by an RF barrier in prior art systems.

Waveguide for transmitting RF energy through an RF barrier

A high-power RF switching device employs a semiconductor wafer positioned in the third port of a three-port RF device. A controllable source of directed energy, such as a suitable laser or electron beam, is aimed at the semiconductor material. When the source is turned on, the energy incident on the wafer induces an electron-hole plasma layer on the wafer, changing the wafer's dielectric constant, turning the third port into a termination for incident RF signals, and. causing all incident RF signals to be reflected from the surface of the wafer. The propagation constant of RF signals through port 3, therefore, can be changed by controlling the beam. By making the RF coupling to the third port as small as necessary, one can reduce the peak electric field on the unexcited silicon surface for any level of input power from port 1, thereby reducing risk of damaging the wafer by RF with high peak power. The switch is useful to the construction of an improved pulse compression system to boost the peak power of microwave tubes driving linear accelerators. In this application, the high-power RF switch is placed at the coupling iris between the charging waveguide and the resonant storage line of a pulse compression system. This optically controlled high power RF pulse compression system can handle hundreds of Megawatts of power at X-band.

Active high-power RF switch and pulse compression system

A microwave switch (20) selectively directs a microwave signal (50) along first and second signal paths. The switch (20) includes a microwave transmission member (22), a microwave chamber (30) formed by the transmission member (22) for containing an ionizable gas (32), input and output ports (26, 28) formed by the transmission member (22) to communicate with the microwave chamber (30) and a triggered plasma generator (24) which is configured to generate, in response to a voltage trigger signal, a trigger electron density (Nt) in the gas (32). The microwave signal (50) increases the trigger electron density (Nt) to a reflective electron density (Nr). Consequently, the microwave signal (50) is reflected along a first path from the input port (26) when the trigger electron density (Nt) is present and is directed along a second path to the output port (28) when the trigger electron density (Nt) is absent. A plurality of these microwave switches (20A-20N) may be arranged to form a tunable microwave short (120).

Triggered-plasma microwave switch and method

A microwave rf envelope generator or pulse shaper has a main waveguide with two opposing branches connected in shunt to the main waveguide and are terminated with variable positionable shorts The characteristic impedance of the shunted combination of the two branches equal one half the characteristic impedance of the main waveguide An incident rf pulse applied to an input of the main waveguide is transmitted to a four way junction formed at the intersection of the two branches The incident pulse is divided at the junction Divided pulses are then transmitted down each of the branches and to an output of the main waveguide The pulses traveling down each branch will have their phases shifted when they are reflected by the variable positionable shorts The lengths of the branches are adjusted by the variable shorts so that the phase of the reflected and inverted pulses will cancel the trailing portion of the pulse transmitted out towards the output of the main waveguide The output pulse width is a function of the time it takes the divided pulses to travel down the branches and back

RF envelope generator

An high power microwave expander is provided which decreases the rise time of rf pulses. The expander is a transmission line in which internal conductors are separated and tapered to provide a spark gap with high isolation characteristics at low power. The arcing threshold of the spark gap can be adjusted by varying the internal pressure of the transmission line, injecting a gas such as helium into the transmission line and by providing free electrons in close proximity to the spark gap.

Robert J. Tan

Papers

RF envelope generator

High power microwave expander for producing fast rise time pulses