Integrating sphere based on absolute method for measuring solar absorptance

In this paper, an integrating sphere for measuring solar absorptance is described. Its characteristics are: (1) it is an absolute method (2) it can be used to measure the directional-hemispherical reflectance for various incidence angles (3) the samples to be measured may be specular, diffuse or specular-diffuse reflecting surfaces. Theoretical analyses are carried out for this integrating sphere and the measured data of reflectance of the MgO, vacuum-vaporized aluminum mirror film and other surfaces are presented.