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5 October 2009 Recent advance in tunable diode laser spectroscopy with background RAM nulling for industrial applications
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Proceedings Volume 7503, 20th International Conference on Optical Fibre Sensors; 750313 (2009) https://doi.org/10.1117/12.833000
Event: 20th International Conference on Optical Fibre Sensors, 2009, Edinburgh, United Kingdom
Abstract
A limiting factor of tuneable diode laser spectroscopy (TDLS) with wavelength modulation spectroscopy (WMS) is the presence of background residual amplitude modulation (RAM) on the recovered 1st harmonic signal. The presence of this background term is due to direct modulation of the source laser power. This work presents a novel method to optically remove the unwanted background, with the major benefit being that measurement sensitivity can be increased. The recently developed phasor decomposition method1 (PDM), is a near IR (NIR) TDLS analysis technique that is used with the addition of the new RAM nulling method to recover gas absorption line-shapes. The PDM is a calibration free approach, which recovers the gas absorption line-shape and the isolated 1st derivative of the line-shape from the 1st harmonic signal. The work presented illustrates and validates the new RAM nulling procedure with measurements examining the 1650.96nm absorption line of methane (CH4) with comparisons to theory.
© (2009) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Keith Ruxton, Arup Lal Chakraborty, Andrew J. McGettrick, Kevin Duffin, Walter Johnstone, and George Stewart "Recent advance in tunable diode laser spectroscopy with background RAM nulling for industrial applications", Proc. SPIE 7503, 20th International Conference on Optical Fibre Sensors, 750313 (5 October 2009); https://doi.org/10.1117/12.833000
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