Patent ID: 6219140
Filing Date: 2001-04-17
Classification: G01J,H04N

Abstract:
An apparatus for compensation for spectral fluctuation of a light source comprising:a lamp for generating light, the light from the lamp having spectral variations;a sensor means for determining the amount of light reaching said sensor means;a spectral monitor means for determining the spectral content of the light from said lamp, the spectral monitor means comprising at least two sensor devices with at least two different spectral responses that are a weighted combination of a 0.sup.th principal component and one additional principal component of the spectral variations in the light from the lamp;a light directing device receiving said light from said lamp and directing said light towards said spectral monitor means and said sensor means; anda signal processing means which receives the output from said spectral monitor means and said sensor means for producing a signal compensated for spectral fluctuations.