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Verfahren und Anordnung zur Bestimmung und Normierung der Intensitaet eines Messsignals, insbesondere bei der Modulations-Laser-Absorptionsspektroskopie

Process and arrangement to determine and normalize the intensity of a measuring signal, in particular in modulation laser absorption spectroscopy
: Werle, P.

Frontpage ()

DE 1993-4333422 A: 19930930
DE 1993-4333422 A: 19930930
DE 4333422 C1: 19950302
Patent, Elektronische Publikation
Fraunhofer IFU; 2002 in Helmholtz-Gesellschaft integriert

The invention relates to a process and an arrangement which helps to perform a determination and normalization of the intensity of a measuring signal, in particular for modulation absorption spectroscopy or interferometry, whereby only a single measuring detector is required and no otherwise necessary reference channel is required. By means of on-line normalization and the use of a frequency modulation method, a diode laser is modulated in such a way that at least one discrete frequency is superimposed on the former. The frequency-modulated laser radiation at its original intensity is then subjected to an intensity attenuation in an absorption measuring cell, said attenuation being determined by means of a phase-sensitive detector. According to the invention, a residual amplitude of the modulation signal is determined at the output of a single detector, whereby said residual amplitude represents a measure of the original intensity. The residual amplitude value can then be used for know n intensity normalization methods.