Wavelength-modulation spectroscopy method and apparatus

US7957001B2 · kind B2 · utility

Assignee

• GE Infrastructure Sensing, LLC · US

Inventors

• Xiaoyong Liu · San Jose, US
• John McKinley Poole · Maynard, US
• Yufeng Huang · Chesapeake, US
• Daniel M. Stearns · Canton, US
• Michael J. Gambuzza · Boston, US
• Gene Smith Berkowitz · Sudbury, US
• Anthony Kowal · Berlin, US
• Hejie Li · Schenectady, US
• Shawn D. Wehe · Niskayuna, US

Key dates

• Filing date: Oct 10, 2008
• Grant date: Jun 7, 2011
• Expiry date: Jul 31, 2029

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N2021/399
• WIPO field: Measurement
• WIPO sector: Instruments

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.