Patent ID: 6263291
Filing Date: 2001-07-17
Classification: G01J,G01N

Abstract:
In a method for determining the color and/or composition of a material, the method comprising the steps of:illuminating a sample of the material with at least three separate illumination bands singly or in combination, said illumination bands collectively substantially spanning at least the visible range; andmeasuring the light reflected or transmitted by the sample in each of the states of illumination with at least four light detector elements responsive to light in wavelength bands which collectively substantially span at least the visible range as an apparent emissivity or transmissivity;the improvements comprising:illuminating a reference material of known emissivity or transmissivity with at least three illumination bands singly or in combination, said illumination bands collectively substantially spanning at least the visible range;measuring the light reflected or transmitted by the reference material in each of the states of illumination with at least four light detector elements responsive to light in wavelength bands collectively substantially spanning at least the visible range; andcomparing measured light reflected or transmitted by the sample to measured light reflected or transmitted under substantially the same conditions of illumination by the reference material of known apparent emissivity or transmissivity and calculating the apparent emissivity or transmissivity of the sample therefrom.