A method for determining spectral characteristics of an object is disclosed. A probe is positioned in proximity relative to the object and provides light to a surface of the object and receives light from the object. One or more critical heights are defined below which no specularly refelcted light is received and propagated. Prior to positioning the probe in proximity relative to the object, a plurality of position-sensitive calibration/normalization reference and a plurality of calibration/normalization measurements are taken with the probe at a plurality of predetermined positions with respect to the calibration/normalization reference. The intensity of light received is determined in a plurality of spectral bands with one or more measurements. The spectral characteristics of the object are determined based on the one or more measurements and based on data taken from one or more of the calibration/normalization measurements.