In a method for measuring a composition of a sample, an illumination surface area of the sample is illuminated using a light source, and light from a plurality of emitting surface areas of the sample is received, each emitting surface area at a different location, the received light scattered by the sample. A cumulative area of the illumination surface area is greater than a cumulative area of two emitting surface areas of the plurality of emitting surface areas. For each emitting surface area, spectral content information associated with received light corresponding to that emitting surface area is determined, and composition information corresponding to a sub-surface region of the sample is determined based on the determined spectral content information. Different shapes of illumination surface areas as well as the plurality of emitting surface areas may advantageously be utilized for various specimen or sample geometries or illumination sources.