Southwest Sciences Inc

Dense pattern optical multipass cell,

U. S. Patent 7,477,377 issued January 13, 2009

Schematic drawing of patented methane sensor

Spectroscopic measurements of gas concentration are more senstitive when the light makes a longer path through the gas. Multiple pass optics have been developed to allow a long path to be folded into a small volume. This invention is a multiple pass optical cell comprising a pair of opposed cylindrical mirrors. A hole in one mirror lets light into and out of the cell. By adjusting both the twist angle and the mirror spacing, various pathlengths can be produced. At a twist angle of 90 degrees (far right column) the system acts somewhat like a Herriott cell. The picture at right summarizes the many possible solutions. Larger, bluer spots correspond to solutions with a small number of passes, while small, red spots correspond to large number of passes. The ideal path length depends on a number of factors, including mirror reflectivity and desired measurement range.

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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