Siemens Aktiengesellschaft

Daniel Depenheuer

Ralf Bitter

Frank Probst

Thomas Hankiewicz

Franz Gaiser

Simone Isabel Rupp

Pawel Kluczynski

A method for correcting a wavelength and a tuning range of a laser spectrometer in which the light from a wavelength-tunable laser diode, after being radiating through a gas, is detected and evaluated, wherein the laser diode is periodically driven with a current ramp, such that a time-resolved absorption spectrum of the gas is obtained upon the detection of the light, where in order to correct the wavelength and the tuning range of the laser spectrometer, a first step involves readjusting the central wavelength of the laser diode via the temperature thereof and based on the position of one of two different selected absorption lines in the detected absorption spectrum, and a second step involves correcting the tuning range of the laser diode via the gradient of the current ramp such that the spacing of the two absorption lines in the detected absorption spectrum remains constant.

Method for correcting a wavelength and tuning range of a laser spectrometer

A method in which the wavelength of the light of a tunable light source is varied periodically over an absorption line of interest for the gas component to measure the concentration of a gas component in a measurement gas based on one of two measurement methods of direct absorption spectroscopy and wavelength modulation spectroscopy and, where in the case of wavelength modulation spectroscopy, the wavelength of the light is additionally sinusoidally modulated at a high frequency and with a small amplitude, where the intensity of the light is detected after transradiation of the measurement gas and processed to yield a measurement result, and where in order to increase the accuracy and reliability of the measurement, the two measurement methods are applied simultaneously during each period, or alternately in consecutive periods, and their results are combined by averaging to form the measurement result.

Method for measuring concentration of a gas component in a measurement gas

A method for operating a laser spectrometer includes passing light of a semiconductor laser through a gas mixture containing a gas component and through an etalon structure onto a detector. The method also includes varying an injection current of the laser based on a predefined current-time function in order to tune the wavelength of the laser in a tuning range using a specific absorption line of the gas component. The method further includes modulating the function with a modulation signal having a frequency and alternately a first modulation amplitude and a second modulation amplitude. The method also includes evaluating a detector signal generated by the detector for determining (1) the concentration of the gas component upon the modulation with the first modulation amplitude and (2) the wavelength stabilization of the laser upon the modulation with the second modulation amplitude at the second harmonic of the frequency.

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Schwegenheim, Germany

Daniel Depenheuer