The integrating cavity absorption meter (ICAM) has been used successfully to measure
the low absorption coefficient of pure water. The ICAM produces an effective total path
length of several meters or even longer, although the physical size of the instrument is
only several centimeters. The long effective total path length ensures a high sensitivity
that enables the ICAM to measure liquid mediums with low absorption. Compared to the
conventional transmission type of instruments that were used to measure the same
medium with the same path length, the ICAM eliminates the effect of scattering by
introducing isotropic illumination in the medium, and consequently measures the true
absorption coefficient of the medium in stead of the attenuation coefficient. The original
ICAM was constructed with Spectralon and used in the wavelength range from 380 nm
to 700 nm. Later studies showed that Spectralon is not suitable for measurements in the
UV region because of its relatively lower reflectivity in this region and, even worse, the
continuously decaying reflectivity under the exposure to UV radiation. Thus, we have
developed a new way to construct the ICAM utilizing the material fumed silica. The resulting ICAM has a high sensitivity even in the UV region and doesn't have the
deterioration problem. The measurement results from the new ICAM are in good
agreement with the existing results. The absorption coefficients of pure water at
wavelengths between 250 nm and 400 nm are presented here.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/85959 |
| Date | 10 October 2008 |
| Creators | Wang, Ling |
| Contributors | Fry, Edward S. |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Dissertation, text |
| Format | electronic, born digital |
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