Shawn D Wehe

US Patent:

7683357, Mar 23, 2010

Filed:

Jul 1, 2008

Appl. No.:

12/166222

Inventors:

William A. Von Drasek - Oak Forest IL, US
Shawn D. Wehe - Westford MA, US
Mark G. Allen - Boston MA, US

Assignee:

American Air Liquide, Inc. - Fremont CA
Physical Sciences, Inc. - Andover MA

International Classification:

G01N 15/06
G01N 21/00

US Classification:

250573, 356437

Abstract:

A gas species monitoring system includes a laser, a fiber amplifier configured to receive an input signal from the laser and generate an amplified signal, and a variable optical attenuation system configured to receive at least a portion of the amplified signal and generate an attenuated signal for delivery to a measurement point, where the measurement point includes a gaseous fluid. The system further includes a detector configured to receive and process a signal from the measurement point so as to obtain a measured signal that correlates with the presence of a gas species within the gaseous fluid at the measurement point, and a processor in communication with at least the variable optical attenuation system and the detector. The processor controls the variable optical attenuation system based upon the measured signal.

US Patent:

7943915, May 17, 2011

Filed:

Oct 10, 2008

Appl. No.:

12/249096

Inventors:

Xiaoyong Liu - Malden MA, US
Yufeng Huang - North Chelmsford MA, US
John McKinley Poole - Maynard MA, US
Gene Smith Berkowitz - Sudbury MA, US
Anthony Kowal - Berlin MA, US
Shawn D. Wehe - Niskayuna NY, US
Hejie Li - Schenectady NY, US

Assignee:

GE Infrastructure Sensing, Inc. - Billerica MA

International Classification:

G01V 8/00
G01J 3/28

US Classification:

2505591, 356326

Abstract:

Several methods of calibrating a wavelength-modulation spectroscopy apparatus configured to measure a concentration of an analyte in a sample gas are disclosed. Each of the methods allows for calibration and recalibration using a relatively safe gas regardless of whether the sample gas for which the concentration of the analyte can be determined is a hazardous gas. In one embodiment of the invention, calibration that is sample-gas specific is accomplished by determining a first slope coefficient and calibration function for the sample gas, after which a scaling factor can be determined based on the first slope coefficient and a second slope coefficient for the same or a different sample gas and used in a subsequent calibration (or recalibration) to scale the calibration function. In other embodiments of the invention, calibration that is not sample-gas specific is accomplished to allow for the determination of the analyte concentration in variable gas compositions and constant gas compositions.

US Patent:

7957001, Jun 7, 2011

Filed:

Oct 10, 2008

Appl. No.:

12/249156

Inventors:

Xiaoyong Liu - Malden MA, US
John McKinley Poole - Maynard MA, US
Yufeng Huang - North Chelmsford MA, US
Daniel M. Stearns - Canton MA, US
Michael J. Gambuzza - Pepperell MA, US
Gene Smith Berkowitz - Sudbury MA, US
Anthony Kowal - Berlin MA, US
Hejie Li - Schenectady NY, US
Shawn D. Wehe - Niskayuna NY, US

Assignee:

GE Infrastructure Sensing, Inc. - Billerica MA

International Classification:

G01N 21/31

US Classification:

356435, 250345

Abstract:

In one embodiment of the spectroscopy method, the method comprises the steps of modulating the wavelength of a monochromatic radiation at a modulation amplitude and a modulation frequency; determining a first variable representative of an absorbance of an analyte in a sample; and demodulating by phase-sensitive detection the first variable at a harmonic of the modulation frequency to produce a harmonic spectrum of the analyte. In one embodiment of the spectroscopy apparatus, the apparatus comprises a laser diode integrated with a first photodetector configured to detect an intensity of a backward emission from the laser diode and act as a reference detector; a second photodetector configured to detect an intensity of laser radiation exiting a sample; and electronic circuitry coupled to the laser diode and the photodetectors, configured to acquire and process spectra of the sample. In another embodiment, the spectroscopy apparatus comprises a beam splitter configured to split the laser radiation into a first radiation portion and a second radiation portion and a first photodetector configured to detect the intensity of the first radiation portion.

US Patent:

8026499, Sep 27, 2011

Filed:

Apr 11, 2011

Appl. No.:

13/083704

Inventors:

Xiaoyong Liu - Malden MA, US
Yufeng Huang - North Chelmsford MA, US
John McKinley Poole - Maynard MA, US
Gene Smith Berkowitz - Sudbury MA, US
Anthony Kowal - Berlin MA, US
Shawn D. Wehe - Niskayuna NY, US
Hejie Li - Schenectady NY, US

Assignee:

GE Infrastructure Sensing, Inc. - Billerica MA

International Classification:

G01V 8/00
G01J 3/28

US Classification:

2505591, 356326

Abstract:

Several methods of calibrating a wavelength-modulation spectroscopy apparatus configured to measure a concentration of an analyte in a sample gas are disclosed. Each of the methods allows for calibration and recalibration using a relatively safe gas regardless of whether the sample gas for which the concentration of the analyte can be determined is a hazardous gas. In one embodiment of the invention, calibration that is sample-gas specific is accomplished by determining a first slope coefficient and calibration function for the sample gas, after which a scaling factor can be determined based on the first slope coefficient and a second slope coefficient for the same or a different sample gas and used in a subsequent calibration (or recalibration) to scale the calibration function. In other embodiments of the invention, calibration that is not sample-gas specific is accomplished to allow for the determination of the analyte concentration in variable gas compositions and constant gas compositions.

US Patent:

8217376, Jul 10, 2012

Filed:

Apr 11, 2011

Appl. No.:

13/083697

Inventors:

Xiaoyong Liu - Malden MA, US
Yufeng Huang - North Chelmsford MA, US
John McKinley Poole - Maynard MA, US
Gene Smith Berkowitz - Sudbury MA, US
Anthony Kowal - Berlin MA, US
Shawn D. Wehe - Niskayuna NY, US
Hejie Li - Schenectady NY, US

Assignee:

GE Infrastructure Sensing, Inc. - Billerica MA

International Classification:

G01V 8/00
G01J 3/28

US Classification:

2505591, 356326

Abstract:

Several methods of calibrating a wavelength-modulation spectroscopy apparatus configured to measure a concentration of an analyte in a sample gas are disclosed. Each of the methods allows for calibration and recalibration using a relatively safe gas regardless of whether the sample gas for which the concentration of the analyte can be determined is a hazardous gas. In one embodiment of the invention, calibration that is sample-gas specific is accomplished by determining a first slope coefficient and calibration function for the sample gas, after which a scaling factor can be determined based on the first slope coefficient and a second slope coefficient for the same or a different sample gas and used in a subsequent calibration (or recalibration) to scale the calibration function. In other embodiments of the invention, calibration that is not sample-gas specific is accomplished to allow for the determination of the analyte concentration in variable gas compositions and constant gas compositions.

US Patent:

8625098, Jan 7, 2014

Filed:

Dec 17, 2010

Appl. No.:

12/971154

Inventors:

Hejie Li - Clifton Park NY, US
Shawn David Wehe - Niskayuna NY, US
Keith Robert McManus - Clifton Park NY, US

Assignee:

General Electric Company - Niskayuna NY

International Classification:

G01N 21/00
G01J 3/433
G01N 21/39

US Classification:

356437

Abstract:

A real-time monitoring of an equivalence ratio of a gas-fuel mixture of a gas turbine engine is provided. The system includes multiple optical probes arranged on a plurality of fuel nozzles for transmitting laser beams directly through a gas-fuel mixture or indirectly by reflecting the laser beams from a surface of a centerbody or burner tube of the fuel nozzle. The system also includes one or more detectors to measure the transmitted laser beams from the multiple optical probes. Further, the system includes a data acquisition subsystem for acquiring and processing signals from the one or more detectors to determine the equivalence ratio of the gas-fuel mixture of the nozzle.

US Patent:

20030132389, Jul 17, 2003

Filed:

Dec 9, 2002

Appl. No.:

10/314566

Inventors:

William Von Drasek - Oak Forest IL, US
Shawn Wehe - Shirley MA, US
Mark Allen - Boston MA, US

International Classification:

G01J005/02

US Classification:

250/343000, 250/339040

Abstract:

A method for monitoring the high temperature reducing combustion atmosphere in a combustion process is disclosed. First, a spectral region for monitoring CO and HO is identified. A laser wavelength is scanned so that a complete absorption transition includes a portion of the baseline. A laser is then referenced to an ITU-GRID. An output signal is generated from the laser and directed to a coupler to split the output signal in a predetermined ratio to a first component and a second component. The first component is directed to optics where it is shaped and collimated and then directed across a sample to be monitored to a detector that generates a measured output. The second component is directed to an absorption measurement device. The measured output is compared with the second component, and the temperature of the atmosphere and the concentration of the CO present in the atmosphere is calculated.

US Patent:

20040027575, Feb 12, 2004

Filed:

Jan 29, 2003

Appl. No.:

10/353807

Inventors:

William Von Drasek - Oak Forest IL, US
Shawn Wehe - Shirley MA, US
Mark Allen - Boston MA, US

International Classification:

G01N021/00

US Classification:

356/432000

Abstract:

A method to provide user selected tunability for multi-section lasers manufactured for the telecommunication industry is disclosed. Extending the tunability of the laser to be user selectable provides a means to use the technology in other applications such as gas sensing or optical component testing. The combination of the broad tuning range with rapid wavelength selection will permit a reduction in the number of DFB lasers used in multiplexed systems thereby reducing system cost and complexity.