US 2018/0003624 A1 · Absorption Spectrometer

Abstract

An absorption spectrometer which measures a gas component concentration in a measured gas and which operates via wavelength modulation spectroscopy, wherein the light wavelength of a wavelength-tunable light source is periodically varied over a gas component absorption line of interest and simultaneously sinusoidally modulated with a high frequency and a low amplitude signal, and wherein the measurement signal of a detector is demodulated in a phase-sensitive manner at the frequency and/or a harmonic of the frequency and further analyzed, where modulation starts in each period or each n-th period with the frequency in a time interval before the beginning of the time function and is performed with a higher amplitude than during the time function to demodulate the measurement signal in a phase-synchronous manner, where a device provided for the phase-sensitive demodulation is synchronized during the time interval such that a cable for transmitting synchronization signals is no longer necessary.

Claims11

Dependent claims

-6. (canceled)

An absorption spectrometer for measuring a concentration of a gas component in a measured gas via wavelength modulation spectroscopy, the absorption spectrometer comprising:

a wavelength-tunable light source;
a modulation device which periodically varies a wavelength of light of the wavelength-tunable light source over an absorption line of interest of the gas component in accordance with a specified time function and simultaneously sinusoidally modulates the wavelength of light of the wavelength-tunable light source with a high frequency and low amplitude signal;
a detector which detects an intensity of the light after passing through the measured gas;
and
an evaluating device which contains means for phase-sensitive demodulation of a measurement signal generated by the detector at at least of (i) a frequency of the measurement signal and (ii) an harmonic of the measurement signal;
wherein the modulation device is configured to start a modulation in each period or each n-th period with the frequency in a time interval before a beginning of the specified time function and perform the modulation at a larger amplitude than during the specified time function;
and
wherein the evaluating device is configured to performed a synchronization of the means for phase-sensitive demodulation during the time interval based on the frequency (f) contained in the measurement signal.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application

15/537,052Filed 2 Dec 2015

Priority

DE 10 2014 226 323.917 Dec 2014

Published

4 Jan 2018

Term ends

Not estimatedThe source records don’t support an estimate.

Classification10 codes

G01N 21/3504
Using infrared light: for analysing gases, e.g. multi-gas analysis
G01J 3/108
Arrangements of light sources specially adapted for spectrometry or colorimetry: for measurement in the infrared range
G01J 3/433
Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry: modulation spectrometry; Derivative spectrometry
G01J 3/4338
Modulation spectrometry; Derivative spectrometry: frequency modulated spectrometry

Absorption Spectrometer

Life of this patent

Absorption Spectrometer

Life of this patent

Abstract

Claims11