Paul D Duncan

US Patent:

6437885, Aug 20, 2002

Filed:

Jun 1, 2000

Appl. No.:

09/583901

Inventors:

Paul G. Duncan - Vienna VA 22182

International Classification:

G02F 109

US Classification:

359 28D, 359281, 359282, 359283, 3242441

Abstract:

Described are the design of a rare earth iron garnet sensor element, optical methods of interrogating the sensor element, methods of coupling the optical sensor element to a waveguide, and an optical and electrical processing system for monitoring the polarization rotation of a linearly polarized wavefront undergoing external modulation due to magnetic field or electrical current fluctuation. The sensor element uses the Faraday effect, an intrinsic property of certain rare-earth iron garnet materials, to rotate the polarization state of light in the presence of a magnetic field. The sensor element may be coated with a thin-film mirror to effectively double the optical path length, providing twice the sensitivity for a given field strength or temperature change. A semiconductor sensor system using a rare earth iron garnet sensor element is described.

US Patent:

6496265, Dec 17, 2002

Filed:

Feb 15, 2001

Appl. No.:

09/783390

Inventors:

Paul Grems Duncan - Vienna VA
Sean Michael Christian - Woodbridge VA
Kevin Anthony Shinpaugh - Blacksburg VA

Assignee:

Airak, Inc. - Manassas VA

International Classification:

G01B 902

US Classification:

356479, 356 355

Abstract:

A method for calculating a distance from a fiber optic tip of a sensor to a reflective surface by high pass filtering a fringe signal gathered by a spectrometer, calculating a power spectral density of the filtered signal, and using a calibrated distance vs. peak spectral density wavelength curve to determine the measured distance. This fiber optic distance measurement technique can be applied to a variety of sensor types, including, but not limited to, pressure, displacement, temperature, acoustic, pressure, load, and magnetic field sensors.

US Patent:

6534977, Mar 18, 2003

Filed:

Oct 21, 1999

Appl. No.:

09/421399

Inventors:

Paul Duncan - Vienna VA 22182
Carvel E. Holton - Blacksburg VA 24060
Richard O. Claus - Blacksburg VA 24060

International Classification:

G01R 3302

US Classification:

3242441, 324260, 359280

Abstract:

Described are the design of a rare earth iron garnet sensor element, optical methods of interrogating the sensor element, methods of coupling the optical sensor element to a waveguide, and an optical and electrical processing system for monitoring the polarization rotation of a linearly polarized wavefront undergoing external modulation due to magnetic field or electrical current fluctuation. The sensor element uses the Faraday effect, an intrinsic property of certain rare-earth iron garnet materials, to rotate the polarization state of light in the presence of a magnetic field. The sensor element may be coated with a thin-film mirror to effectively double the optical path length, providing twice the sensitivity for a given field strength or temperature change. A semiconductor sensor system using a rare earth iron garnet sensor element is described.

US Patent:

6551583, Apr 22, 2003

Filed:

Apr 25, 2001

Appl. No.:

09/841163

Inventors:

Paul G. Duncan - Vienna VA
Sean Michael Christian - Woodbridge VA
David M. Orcutt - Blacksburg VA

Assignee:

Airak, Inc, - Manassas VA

International Classification:

A61L 901

US Classification:

424 768, 424400, 424 761, 424405, 424409, 514241, 51425407, 514396

Abstract:

An antibiofouling material, a method for making said antibiofouling material, a sensor apparatus employing said antibiofouling material, and a method of making said sensor apparatus. The disclosed antibiofouling material includes one or more biocides and one or more charge transfer compounds are embedded within a copolymer host matrix. Biocides used in the present invention may include, but are not limited to, Halobenzonitriles, Azoles, diuron; and simazine. Among its uses, the antibiofouling material of the present invention can be used in a sensor apparatus. In a preferred embodiment, one or more surfaces of said sensor apparatus are coated with an antibiofouling material comprised of one or more biocides, one or more charge transfer compounds, and a copolymer host matrix.

US Patent:

6670810, Dec 30, 2003

Filed:

Apr 25, 2001

Appl. No.:

09/841164

Inventors:

Paul G. Duncan - Vienna VA
Sean Michael Christian - Woodbridge VA

Assignee:

Airak, Inc. - Manassas VA

International Classification:

G01R 3302

US Classification:

3242441, 324260, 359280

Abstract:

A system and method for gathering and analyzing data captured from one or more remote sensing units positioned in the field. Remote sensing units preferably utilize optical sensors. Power to sensing unit components is preferably selectively controlled to reduce power consumption. Remote sensing units according to the invention can be used for a variety of purposes, including water quality or electrical power monitoring, and data from such sensing units is preferably transmitted to a secure host terminal via a communications link. The host terminal preferably formats, analyzes, and stores the data for customer review and retrieval. If alarm conditions exist that require immediate customer notification, such notification can be sent to a customer via one or more telecommunications means. Through the use of the present invention, businesses can shift from a reactive to a proactive mode of monitoring and operation.

US Patent:

6718281, Apr 6, 2004

Filed:

Feb 15, 2001

Appl. No.:

09/783389

Inventors:

Paul G. Duncan - Vienna VA
Sean Michael Christian - Woodbridge VA
Kevin Anthony Shinpaugh - Blacksburg VA
Herve Marand - Blacksburg VA

Assignee:

Virginia Polytechnic Institute State University - Blacksburg VA

International Classification:

G01B 700

US Classification:

702159

Abstract:

Disclosed is a novel apparatus and method for volumetric dilatometry. A volumetric dilatometer includes an optical displacement sensor and a means for using a gap measurement obtained from the displacement sensor application in an application which requires the measurement of absolute distance and/or displacement. A novel signal-processing algorithm for volumetric dilatometry is also disclosed. The signal-processing algorithm includes a step for recovering the phase information from a spectral signal by taking the Fourier transform of a spectral signal and deriving a sensor gap measurement from the phase information. A micro-translation stage is provided for automated positioning of the optical sensor and automated re-leveling in an out-of-range condition. A heat source is consists of a vertical tube furnace, such as those found in drywell technologies. Further disclosed is a novel sealed-cell design which consists of a mercury reservoir, a sample cell capable of locking onto the bottom of the mercury reservoir and an outer reservoir sleeve for sensor-to-cell alignment during sensor positioning.

US Patent:

6756781, Jun 29, 2004

Filed:

Nov 15, 2002

Appl. No.:

10/294905

Inventors:

Paul Grems Duncan - Vienna VA
John Alan Schroeder - Leesburg VA

Assignee:

Airak, Inc. - Manassas VA

International Classification:

G01R 33032

US Classification:

3242441, 359484

Abstract:

Described are improved transmissive magneto-optical sensors that may be used to determine the magnitude and phase of a magnetic field surrounding a conductor, and when in contact with the conductor, the surface temperature of the conductor. The magneto-optical sensor may be made to be symmetric around the direction of propagation of the internal light, enabling ease of manufacturing as well as automated assembly and calibration. The magneto-optical sensor may also be made to be symmetric about the plane determined by the Faraday rotator material, thus enabling reciprocating optical paths for increased vibration and birefringence immunity. The disclosed sensors preferably include cylindrically symmetrical components, thereby making the sensor readily mass-producible.

US Patent:

6838660, Jan 4, 2005

Filed:

Jun 4, 2001

Appl. No.:

09/871692

Inventors:

Paul Grems Duncan - Vienna VA, US
Sean Michael Christian - Woodbridge VA, US
John Alan Schroeder - Leesburg VA, US

Assignee:

Airak, Inc. - Manassas VA

International Classification:

G01J 104
G02B 600

US Classification:

25022714, 25022719, 385 13, 356482

Abstract:

In a preferred embodiment, the invention provides a fiber optic pressure sensor apparatus which includes a light source, a reflective sensor diaphragm movable in accordance with pressure in a medium and an optical fiber coupled to the light source for delivering a first wavefront of light to the reflective sensor diaphragm. The optical fiber has an endface which is separated from the reflective sensor diaphragm by a gap, the endface receiving a second wavefront of light reflected from the reflective sensor diaphragm. The first and second wavefronts constructively and destructively interfere to create a modulated optical signal. A spectrometer is coupled to the optical fiber for converting the optical signal into a series of digital values, and means for analyzing the digital values is provided for obtaining a measurement of the pressure in the medium. An optical coupler is preferably provided for coupling the light source, the optical fiber, and the spectrometer. A power monitoring optical detector means may be coupled to the light source by the optical coupler.