| 摘要 |
Apparatus for measuring the absolute reflectance of a sample, which comprises an integrating sphere provided with four windows the centers of which lie in a plane including the center of the integrating sphere. A first one of the four windows has its center coinciding with a diametrical line of the integrating sphere included in the plane while a second and a third window are arranged symmetrically with respect to the diametrical line, with a sample set in the fourth window so as to face inwardly of the integrating sphere. A light source is so arranged as to introduce a beam of light into the integrating sphere and a light measuring device is so arranged as to receive the light emerging from the integrating sphere. The integrating sphere is rotatable for 180 DEG about an axis coinciding with the above-mentioned diametrical line so that the integrating sphere selectively takes two positions thereby to change the operative positions of the second and third windows relative to the light source or the light measuring device. The data measured at each of the two positions of the integrating sphere are processed so as to obtain the absolute reflectance of the sample. The positions of the light source and the light measuring device relative to the windows of the integrating sphere may be exchanged to obtain a different type of absolute reflectance.
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