Patent ID: 6057912
Filing Date: 2000-05-02
Classification: G01J

Abstract:
A method to compensate for lamp spectrum shift, comprising:exposing a first detector to a first light from a lamp, thereby generating a first signal indicative of intensity of said first light;exposing a second detector to a wavelength (.lambda.) of a second light from said lamp, thereby generating a second signal indicative of intensity of said wavelength of said second light, after said second light has interacted with a sample;determining a new color temperature (T.sub.1) of said first light using the following equationT.sub.1 =(F.sub.1 /A).sup.1/xwhere A=F.sub.i /(T.sub.i).sup.x,x=a color temperature exponent of said lamp,F.sub.1 =said first signal,F.sub.i =an initial reference signal, andT.sub.i =an initial color temperature corresponding to said initial reference signal; and determining a first compensated signal (I.sub.1) using the following equationI.sub.1 =S.sub.1 /B.sub.1where ##EQU9## S.sub.1 =said second signal, h=Planck's constant,c=speed of light in vacuum, andk=Boltzman constant.