Southwest Sciences Inc

Optical Absorbance Sensitivity and Reliability Improvement via Rotation of Sample Container

U. S. Patent No. 7,126,685, issued October 24, 2006

One of the remarkable capabilities of a laser-based gas sensor is that it can be used to measure the contents of a bottle without needing to open the bottle or pierce it in any way. This capability can be exploited to determine whether a bottle is not properly sealed, for instance if carbonation has leaked out or if oxygen has leaked in. Because the test is non-destructive, this can be done on every single bottle.

Practical problems arise when applying spectroscopy to samples in bottles. Powders in the bottle can block the laser beam, while the bottle itself is a source of etalon fringes from reflections from the glass surfaces. This patent describes a simple way to improve the reliability of measurements of bottles, by spinning them so that data are collected from a variety of points on the bottle. When wavelength modulation techniques are used, the dc signal can be used to determine that the laser has a clear path through the bottle to the detector, while the ac signal can be used to infer the concentration of the target gas. Averaging only the signals with a good path rejects interferences from powders or foams blocking the laser. Spining also averages away etalon fringes because the bottle is not perfectly uniform. The result is much higher sensitivity to the gaseous contents of the bottle.

Contact Information

Southwest Sciences, Inc.
1570 Pacheco St., Suite E-11, Santa Fe, NM 87505
tel. (505) 984-1322/ fax (505) 988-9230



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