Background signals in wavelength-modulation spectrometry by use of frequency-doubled diode-laser light. II. Experiment

Applied Optics

Volumn 40, Issue 6, 2001, Pages 794-805

  Kluczynski, Pawel ^a   Lindberg, Åsa M ^a   Axner, Ove ^a  

^a UMEÅ UNIVERSITY   (Sweden)

Author keywords

[No Author keywords available]

Indexed keywords

CRYSTALS; FREQUENCIES; LASER BEAMS; LIGHT MODULATION; SEMICONDUCTOR LASERS; THERMODYNAMIC STABILITY;

WAVELENGTH-MODULATION SPECTROMETRY (WMS);

LASER OPTICS;

EID: 0000986139     PISSN: 1559128X     EISSN: 21553165     Source Type: Journal    
DOI: 10.1364/AO.40.000794     Document Type: Article

References (20)

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16. The reason for these etalon background signals is that the optical system consists of a multitude of surfaces between which several weak optical etalons can inadvertently be formed. Because a slight change in the alignment of the system will alter the shape as well as the size of these etalondominated background signals, two consecutive 4f and 6f spectra will therefore not, in general, look exactly the same. The nf background signals from etalons were characterized previously (see Ref. 11) and are therefore not considered further in this paper.
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18. Although the Doppler broadening, which gives rise to a Gaussian line broadening, in many instances can rival (and even dominate) the collision-lifetime broadening, which gives rise to a Lorentzian line profile, in this study, we chose to describe the analytical signal as a pure Lorentzian profile. The main reason for our choice is that the use of a Lorentzian profile simplifies the SBR analysis in this study considerably. There are several reasons for this simplification: First, the previously developed theoretical formulation makes use of various Fourier components of the line-shape function. There exist convenient analytical expressions for a Lorentzian profile, whereas no comparable expressions have yet been found for the Gaussian or the Voigt functions. Second, there is only a small difference in the WM signal shape from the Lorentzian- and the Gaussian-shaped profiles. Third, the main aim of the SBR analysis is to investigate the behavior of the various nf harmonics of the background signal under various conditions. For the purpose of a comparison of various types of background signal to an analytical signal, we are of the opinion that a Lorentzian description of the analyte therefore serves the purpose of this study sufficiently well.
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