Experimental evaluation of Alta II spectrometer and its application in the Brazilian standards

Three series of measurements were performed by varying: the spectrometers used, the exposure to light, and the roughness of the measured surface (flat painted samples or texture painted walls). Measurements were also performed using the Lambda 1050 spectrophotometer as a reference. The analysis showed that the results may be highly inaccurate.

Therefore, the Alta II spectrometer should be used with caution. The experiments showed uncertainty of about ±0.10 in the absolute values of solar reflectance (for reflectance ranging from 0-1). Thus, the Alta II spectrometer user must consider such an error.

It was also concluded that Alta II should only be used to analyse flat surfaces and it is important to ensure that measurements are carried out preventing light leakage through contact between the equipment surface and the sample.