Date of Award

Spring 1998

Document Type


Degree Name

Master of Science (MS)


Electrical & Computer Engineering

Committee Director

Amin N. Dharamsi

Committee Member

William Chu

Committee Member

Glenn Gerdin


Parasitic Fabry-Perot etaloning plagues many experiments which use wavelength modulation spectroscopy. This fringing, which is an artifact that almost always appears in such experiments, arises from multiple reflections in the optical elements in the experimental apparatus. The etaloning plays a detrimental role and limits the ultimate sensitivity of wavelength modulation spectroscopy experiments. The research described in this thesis investigates this phenomenon. Experimental results are presented which show that when the Q-factor of the parasitic etalon is smaller that that of the absorption line being measured, significant improvement in the Signal to Fringe Noise Ratio can be obtained through the use of higher harmonic detection.

A model is developed and experimental results are compared with theoretical predictions. The extremely good agreement obtained enables us to extract accurate values for the modeling parameters. Line centers, line widths, and optical absorption cross-sections of several lines in the oxygen A-band are measured with high accuracy using the etalon as a reference.


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