Westinghouse Electric Corporation

Northrop Grumman Systems Corporation

Peter J Chantry

Anastasios P Goutzoulis

Tom Henningsen

Irving Liberman

Cheng-Lin Chen

Juris A Asars

David K Davies

Robert W Weinert

Bruce R McAvoy

Carlo F Petronio

Thomas J Smith, Jr

Salvador H Tallisa

The microwave field intensity of a cell type atomic clock is stabilized through time division feedback control of the power of the microwave signal implemented by a microcontroller. The depth of the microwave dip is calculated from differences in measurements of the optical signal when the microwave signal is dithered around the atomic transition frequency of the active medium, and measurements taken when the optical signal is dithered around the optical wavelength of the active medium while the microwave signal is adjusted to produce no microwave absorption, either by reducing the microwave power to zero or by detuning it from the atomic transition frequency of the active medium. RF synthesizers suitable for regulating microwave power include a synthesizer using a step recovery diode for frequency multiplication and having the power to a driver amplifier or the bias applied to the diode regulated. A digital synthesizer can also be used to generate a regulated microwave signal.

Apparatus and method for microwave field strength stabilization in cell

A miniature atomic frequency standard utilizes a tubular vapor cell extending transversely through a TE.sub.210 microwave cavity. In one embodiment of the invention, the vapor cell is heated directly by electric heaters secured to ends of the tubular vapor cell which extend outside the microwave cavity. The vapor cell is insulated by thermal insulation inside the microwave cavity and between the microwave cavity and a magnetic shield. In another embodiment of the invention, the entire microwave cavity is heated which eliminates the need for thermal insulation inside the cavity and thus it can be made smaller, but additional thermal insulation is provided between the microwave cavity and the magnetic shield. Preferably, the C-field coil is wound on the thermal insulation just inside the magnetic shield to reduce heat loss by conduction. A laser diode outside the magnetic shield transmits light to the vapor cell through optic fiber without need for a collimating lens and a photodiode with an integral lens is used as the detector.

Miniature atomic frequency standard

A gas cell for a miniature atomic frequency standard. The gas cell functions not only to contain the cesium vapor, but also as a resonator for the microwave signal used to excite the vapor. By combining the functions of gas cell and resonator into a single structure, and by taking advantage of the intensity of light available from a laser diode, the overall size of an atomic frequency standard can be reduced by two orders of magnitude when compared to prior art devices of comparable accuracy.

Gas cell for a miniaturized atomic frequency standard

An optical architecture for receiving and slowing down high-speed data for high-speed digital testing applications is provided in which an input generating means transmits high-speed input test vectors to an apparatus under testing. In response, the apparatus under testing generates output test vectors. These high speed output test vectors are converted to slow-speed data signals by optically demultiplexing the high-speed vectors into high-speed parallel data signals and then expanding the parallel data signals to for slow-speed data signals. The slow-speed data signals are then compared with slow-speed reference vectors on a personal computer to determine whether the apparatus under testing is in error for any of its output channels.

System for optically splitting high-speed digital signals using

A cell-type atomic frequency standard utilizing a miniaturized gas cell and microwave exciter along with a diode laser light source. The intensity of the diode laser light source counterbalances the penalties associated with the small gas cell. The signal produced by an oscillator is applied to a vapor within the gas cell by a miniature helix coil, or LC gap conductor, or a microstrip exciter. With the dimensions of the gas cell not exceeding one-half the wavelength of the signal, and the associated circuitry formed on a semiconductor substrate, the resulting frequency standard is reduced in size by two orders of magnitude when compared to prior art devices of comparable accuracy.

Miniaturized atomic frequency standard

An optical architecture is provided that can be used for generating high-speed input test vectors from low speed digital data and transferrring those test vectors to a device under test. The optical architecture employs gain-switched laser diodes or optical mixers to produce high-speed optical pulses from the low speed digital data. Optical multiplexing and variable delay devices process the high speed optical pulses to form a high-speed test vector. The architecture can generate test data with psec-type accuracy.

Method and apparatus for generating and transferring high speed data for

A fiberoptic-coupled free-space variable delay line is provided wherein the phase adjustment of the signal can be accurately set. A microscope-objective lens collimates a signal beam which is received by a focusing lens. The focusing lens is provided on an adjustable carrier to allow one to accurately adjust the distance travelled by the collimated signal base and thereby accurately adjust the off-set. A plurality of these variable delay lines can be arranged to form a multiplexer. If the threads on each drive rod moving a carrier are different, the carrier can be adjusted to accommodate changes in frequency of the signal.

Optical variable delay line and variable-frequency fiber-optic

A method of detecting insulation defects in a wire using an extended ion source wherein ions are generated along the entire length of the extended ion source and flow toward an insulated cable located in close proximity thereto. If there are defects in the cable insulation, a real current will flow through the insulation defects and into the cable conductor. The presence of this real current can be measured by connecting one end of the cable conductor to an ammeter and changes in this current indicate the existence of a defect in the wire insulation. In another embodiment of the extended ion source, the ions are generated only in a small portion of the extended source at any one time. By exciting the source with the proper sequence of signals, the ion generation scans or propagates along the entire length of the extended ion source.

Extended ion sources and method for using them in an insulation defect

A method for separating isotopes in which a selected isotope of a given molecule is first excited to enhance preferential dissociative electron attachment, which facilitates the separation of the desired isotope from its natural mixture. Molecules incorporating the particular isotope of interest are selectively excited to the proper vibrational and/or electronic state by narrow line radiation to enhance preferential dissociative electron attachment. The excited molecules are then exposed to low energy electrons which dissociatively attach to the excited molecules forming stable negative ion fragments. The negative ion or neutral fragments containing the desired isotopes are then separated from the remaining mixture resulting in an enrichment of the desired isotope.

Isotope dissociation selective electron attachment and separation

The detection of electronegative gases through the use of a dissociative electron attachment process is enhanced by exciting the molecules of an electronegative gas of interest to an electronic or vibrational level to increase the cross section of the molecule for dissociative attachment of electrons to produce negative ions indicative of the gas molecules of interest.

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Churchill Boro, PA, United States of America

Peter J Chantry