Gregory M Nau

US Patent:

6650418, Nov 18, 2003

Filed:

Jul 27, 2001

Appl. No.:

09/916615

Inventors:

Michael J. Tweedy - Simi Valley CA
Eric L. Goldner - Valencia CA
Patrick J. Welton - Thousand Oaks CA
Gregory M. Nau - Alexandria VA
Bruce A Danver - Alexandria VA

Assignee:

Litton Systems, Inc. - Woodland Hills CA

International Classification:

G01B 902

US Classification:

356477

Abstract:

A pair of fiber optic coils are mounted on opposite sides of a flexural disk and are arranged to form an interferometer that produces an output signal in response to acceleration of the flexural disk. The flexural disk is mounted in a housing having first and second end plates with a sidewall extending between them. A support member extends between the end plates and through a central passage in the flexural disk. A pair of compressive dampers is mounted in the housing between the flexural disk and the housing end plates. A shear damper mounted on the central support member exerts a radial force on an inner edge of the central passage in flexural disk to dampen vibrations of the flexural member and control the output signal amplitude over a selected frequency range.

US Patent:

60787066, Jun 20, 2000

Filed:

Sep 24, 1998

Appl. No.:

9/159566

Inventors:

Gregory Nau - Alexandria VA
Dominique M. Dagenais - Chevy Chase MD
Frank Bucholtz - Crofton MD

Assignee:

The United States of America as represented by the Secretary of the Navy - Washington DC

International Classification:

G01B 902

US Classification:

385 12

Abstract:

This invention is a quasi-static fiber pressure sensor using self-referenced interferometry based on a broadband semiconductor source which probes the pressure plate deflection within a Fabry-Perot cavity where phase is demodulated with a dual grating spectrometer providing real-time, high resolution remote measurement of pressure using optical interrogation of a deflecting pressure plate. This technique yields absolute gap measurement in real time over a wide range of gap lengths with nanometer resolution. By tailoring the pressure plate design to cover the range of gaps and deflection that can be resolved, pressure sensing with psi resolution can be obtained in a kpsig pressure range.

US Patent:

56215223, Apr 15, 1997

Filed:

Apr 5, 1995

Appl. No.:

8/417164

Inventors:

Kenneth J. Ewing - Bowie MD
Thomas Bilodeau - Alexandria VA
Gregory Nau - Alexandria VA
Ishwar Aggarwal - Fairfax Station VA

Assignee:

The United States of America as represented by the Secretary of the Navy - Washington DC

International Classification:

G01J 344
G01N 2165

US Classification:

356301

Abstract:

The present invention is a chemical sensor including a polymer substrate capable of reversible adsorption of an analyte organic compound, a source of Raman excitation radiation, positioned for directing this Raman excitation radiation onto the substrate, thus generating a Raman signal, and a Raman signal detector, positioned for detecting this Raman signal. Another aspect of this invention is the sensing tip of such a sensor, including a polymer substrate capable of reversible adsorption of an analyte organic compound, focusing means for directing excitation radiation onto the polymer substrate to generate a Raman signal from the organic compound, and collection means, for transmitting this Raman signal to a detector. Another aspect of this invention is an array of sensing tips, each using a different polymer substrate selected for selective adsorption of an analyte species, coupled to an excitation radiation source and a detector.

US Patent:

55258000, Jun 11, 1996

Filed:

Oct 31, 1994

Appl. No.:

8/332294

Inventors:

Jasbinder S. Sanghera - Greenbelt MD
Pablo C. Pureza - Burke VA
Ishwar D. Aggarwal - Fairfax Station VA
Gregory Nau - Alexandria VA

Assignee:

The United States of America as represented by the Secretary of the Navy - Washington DC

International Classification:

G01N 2117

US Classification:

25033908

Abstract:

A fiber optic sensor for detecting at least one chemical by evanescent wave spectroscopy comprises a generator of a light signal, a mirror for introducing the light signal into a fiber, a clad optical chalcogenide glass fiber, a mirror for directing the light signal from the fiber into a detector, and a detector for detecting chemicals by the fiber. The fiber comprises a core and a clad having lower refractive index than the core enveloping and being in continuous contact with the core, at least one region on the fiber completely or partially devoid of the clad, and a polymer disposed in the region having affinity for the chemical(s). There being a different polymer in each region if there is more than one region.

US Patent:

57395365, Apr 14, 1998

Filed:

Dec 14, 1995

Appl. No.:

8/572389

Inventors:

Frank Bucholtz - Crofton MD
Gregory Nau - Alexandria VA
Ishwar D. Aggarwal - Fairfax Station VA
Jasbinder S. Sanghera - Greenbelt MD
Kenneth J. Ewing - Bowie MD

Assignee:

The United States of America as represented by the Secretary of the Navy - Washington DC

International Classification:

G01J 502

US Classification:

2503412

Abstract:

A system for the in-situ detection of chemicals, including water, in soil comprises: a penetrometer for penetrating the soil, the penetrometer including interior and exterior surfaces, and a window for allowing infrared radiation to be transmitted between the interior and exterier surfaces of the penetrometer; a driver for driving the penetrometer into the soil to a plurality of different depths; a source for providing infrared radiation which passes through the window to irradiate the soil adjacent to the window; an infrared transmitting chalcogenide optical fiber; an optical system disposed within the penetrometer adjacent to the window for transmitting infrared radiation from the source through the window into the soil and for collecting infrared radiation reflected from the soil back through the window into a first end of the chalcogenide fiber; and a spectrometer coupled to a second end of the infrared transmitting chalcogenide optical fiber for receiving and analyzing the reflected infrared radiation passing through the chalcogenide optical fiber to obtain information on chemicals present at various depths of the soil through which the penetrometer passes.

US Patent:

H14702, Aug 1, 1995

Filed:

Mar 28, 1994

Appl. No.:

8/219188

Inventors:

Kenneth J. Ewing - Bowie MD
Gregory Nau - Alexandria VA
Thomas Bilodeau - Alexandria VA
Irwin Schneider - Alexandria VA
Ishwar Aggarwal - Fairfax Station VA

International Classification:

G01N 2141

US Classification:

356128

Abstract:

A refractive index-based sensor uses a light source and an optical fiber to direct an optical beam towards a sensor/environment face at a specific angle. The sensor has a predetermined shape selected such that the light directed into the sensor will have a specific angle of incidence designed to detect a plurality of liquids. A second optical fiber carries the light reflected off the sensor/environment face to a photodetector. The optical beam will either be transmitted through or reflected off the sensor/environment face based upon the refractive indices of the sensor and the environment and upon the angle of incidence of the optical beam. The amount of light reflected is indicative of the refractive index of the material in a given area of the sensor/environment face and, thus, the type of material. By adjusting the angle at which the light is directed to the sensor/environment face, the photodetector response can be calibrated to identify the type of liquid present at the sensor/environment face.