A method for determining spectral characteristics of an object is
disclosed. A probe is positioned in proximity relative to the object. The
probe provides light from at least first and second light sources
positioned first and second distances from a central light receiver. The
first light source and the central light receiver define a first critical
height from the surface below which no specularly reflected light from
the first light source is received by the central light receiver, and the
second light source and the central light receiver define a second
critical height from the surface below which no specularly reflected
light from the second light source is received by the central light
receiver. The first critical height is different from the second critical
height.