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Integrating sphere reflectance and transmittance intercomparison measurements for evaluating the accuracies of the achieved results
Jochen Manara, Mariacarla Arduini-Schuster, and Leonhard Hanssen
In this work reflectance and transmittance measurements results were obtained at ambient temperature with integrating sphere setups and FTIR-spectrometers. The employed measurement setups are described in detail. The results derived at NIST and at ZAE Bayern are compared and the measurement uncertainties are stated and discussed. Additionally, the importance of a well-defined evaluation routine for the received raw data is described which includes the parameters of the measurement setup.
To cover a wide range of values, different samples are investigated. Aerogels are used to evaluate the uncertainties for samples with low reflectance and high absorptance, whereas a diffuse gold sample serves as test for samples with high reflectance. Supplementary to these, a glass fiber fleece is measured as an example for a semitransparent sample which has a non-vanishing transmittance and an intermediate reflectance.
The measurement results are in good agreement. Minor differences can be attributed to the consistency and structure of the investigated samples.
Keywords: Reflectivity; metals; porous materials; infrared spectroscopy; integrating sphere; standard uncertainty.