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Proceedings Paper

Specular baffle for improved infrared integrating sphere performance
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Paper Abstract

Baffles are often placed in integrating spheres to accommodate the non-ideal aspects of other sphere components. These include detectors, sources, sphere wall surface shape and coatings. Baffles intentionally prevent light interchange between these and other important sphere components and regions such as entrance/exit ports, sample, reference and detector field-of-view. The challenge for an integrating sphere designer is to position and construct baffles that achieve the primary goal of shadowing specific elements from each other, while at the same time minimizing all other “side” effects that the baffles may have. Perhaps the most important side effect is the additional signal loss for light arriving at or leaving the sample from or to the baffle due to its absorptance. This is especially true for coatings and spectral ranges where the wall reflectance is relatively low such as for BaSO4 above 1.5 mm and diffuse gold. A potential improvement that we have investigated in an infrared reflectometer sphere is the use of a specular coating that has significantly higher reflectance than any other available diffuse coating. In our case we have used specular gold versus the diffuse gold-coated plasma-sprayed metal coating that is on the sphere wall. Although this provides for lower loss of light reflected from the sample onto the baffle, the side effects must also be considered and reduced in the design. Specifically one needs to consider the mirroring that will take place in the sphere. In this paper we discuss the important design issues along with some integrating sphere characterization results that demonstrate improved sphere performance by use of specular baffles.

Paper Details

Date Published: 14 November 2003
PDF: 10 pages
Proc. SPIE 5192, Optical Diagnostic Methods for Inorganic Materials III, (14 November 2003); doi: 10.1117/12.508299
Show Author Affiliations
Leonard M. Hanssen, National Institute of Standards and Technology (United States)
Alexander V. Prokhorov, National Institute of Standards and Technology (United States)
Vladimir B. Khromchenko, National Institute of Standards and Technology (United States)


Published in SPIE Proceedings Vol. 5192:
Optical Diagnostic Methods for Inorganic Materials III
Leonard M. Hanssen, Editor(s)

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