An integrating sphere system has been designed and constructed for multiple optical property measurement in the infrared spectral range. In particular, for specular samples, the absolute transmittance and reflectance can be measured directly with high accuracy and the absorptance obtained from these by simple calculation. These properties are measured with a Fourier transform spectrophotometer for several samples of both opaque and transmitting materials. The expanded uncertainties of the measurements are shown to be less than 0.003 (absolute) over most of the detector-limited working spectral range of 2 m to 18 m. The sphere is manipulated via two rotation stages which enable the ports on the sphere to be rearranged in any orientation relative to the input beam. Although the sphere system is used for infrared spectral measurements, the measurement method, design principles and features are generally applicable to other wavelengths as well.
Citation: Applied Optics
Issue: No. 19
Pub Type: Journals
absolute, infrared, integrating sphere, method, reflectance, regular, specular, transmittance