A new narrow angle spectrogoniometer for the measurement of bidirectional reflectance

Presents FEBO, a new spectrogoniometer installed in the Photometric Laboratory of the University of Florence for bidirectional reflectance measurements. The system uses an industrial robot arm for positioning a detector around the target on a 2×1 m² area, at angles up to ±90° around the zenith. The spectral detector is an intensified CCD OMA, coupled with an optical fiber, allowing a narrow detection angle in the spectral range of 250-900 nm, on a target area of 95×95 mm². Other detectors can be mounted directly on the FEBO arm, for infrared measurements. Target integration is achieved by scanning the detector over the target area, under computer control by the FEBO software, which provides also data visualisation, storage and detector response calibration. Results of a first experiment on a spruce canopy is also described, showing the variation of NDVI with detection and illumination angles