Patent ID: 7397562
Filing Date: 2008-07-08
Classification: G01J

Abstract:
1. A method for determining spectral characteristics of an object comprising the steps of: positioning a probe and/or the object such that the probe is in proximity relative to the object, wherein the probe provides light to a surface of the object and receives light from the object, wherein light is provided from the probe by at least first and second light sources and light is received by at least a central light receiver, wherein the first light source is positioned a first distance from the central light receiver and the second light source is positioned a second distance from the central light receiver, and wherein 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 and propagated 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 and propagated by the central light receiver, wherein the first critical height is different from the second critical height; prior to positioning the probe and/or the object such that the probe is in proximity relative to the object, taking a plurality of position-sensitive calibration/normalization measurements, wherein the probe is controllably moved relative to a calibration/normalization reference, wherein a plurality of calibration/normalization measurements are taken with the probe at a plurality of predetermined positions with respect to the calibration/normalization reference; when the probe is positioned in proximity relative to the object determining the intensity of light received by the central light receiver in a plurality of spectral bands with a first measurement when the first light source is on and with a second measurement when the second light source is on; determining the spectral characteristics of the object based on the first and second measurements and based on data taken from one or more of the calibration/normalization measurements.