Abstract
A limiting factor of tunable diode laser spectroscopy (TDLS) analysis is the large unwanted residual amplitude modulation (RAM) background present on the recovered 1st harmonic signal. A novel approach to remove the background RAM will be presented. This new technique will be used alongside the phasor decomposition method (PDM) [1], a calibration free technique for recovery of the absolute gas absorption line-shape. The RAM nulling method developed, successfully removes the background by optical cancellation. This is
achieved by placing a fibre delay line, which introduces a π phase change in the modulation signal, in parallel with the gas cell line. When these lines are coupled together the background signals are at anti-phase and hence cancel each other. The main benefit being that measurement sensitivity can be increased. Results illustrating RAM nulling whilst using the PDM technique for absorption line-shape recovery will be presented. Figure 1 shows a recorded PDM measurement illustrating the difference with and without RAM Nulling.
achieved by placing a fibre delay line, which introduces a π phase change in the modulation signal, in parallel with the gas cell line. When these lines are coupled together the background signals are at anti-phase and hence cancel each other. The main benefit being that measurement sensitivity can be increased. Results illustrating RAM nulling whilst using the PDM technique for absorption line-shape recovery will be presented. Figure 1 shows a recorded PDM measurement illustrating the difference with and without RAM Nulling.
| Original language | English |
|---|---|
| Pages | 80 |
| Number of pages | 1 |
| Publication status | Published - Jul 2009 |
| Event | 7th International Conference on Tunable Diode Laser Spectroscopy - Zermatt, Switzerland Duration: 13 Jul 2009 → 17 Jul 2009 |
Conference
| Conference | 7th International Conference on Tunable Diode Laser Spectroscopy |
|---|---|
| City | Zermatt, Switzerland |
| Period | 13/07/09 → 17/07/09 |
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Keywords
- tunable diode laser spectroscopy
- residual amplitude modulation
- phasor decomposition method
- absolute gas absorption
- optical cancellation
Cite this
Ruxton, K. C., Chakraborty, A., McGettrick, A. J., Duffin, K., Johnstone, W., & Stewart, G. (2009). Diode laser spectroscopy using a calibration free phasor decomposition approach with RAM nulling. 80. Paper presented at 7th International Conference on Tunable Diode Laser Spectroscopy, Zermatt, Switzerland, .