Citation:
Jane Hodgkinson, Dackson Masiyano, and Ralph P. Tatam. Using integrating spheres as absorption cells: path-length distribution and application of Beer's law. Applied Optics, Vol. 48, 2009, Issue 30, pp. 5748-5758
Abstract:
We have modeled the path-length distribution in an integrating sphere used as a
multipass optical cell for absorption measurements. The measured radiant flux as
a function of analyte concentration is nonlinear as a result, deviating from
that expected for a single path length. We have developed a full numerical model
and introduce a new analytical relationship that describes this behavior for
high reflectivity spheres. We have tested both models by measuring the optical
absorption of methane at 1651nm in a 50mm diameter sphere, with good agreement
with experimental data in the absorption range 0-0.01cm -1 . Our results compare
well with previous work on the temporal response of integrating spheres.
