抄録
The multiplicative comparator of spectral radiances built at the NRLM, was used to realize the International Practical Temperature Scale of 1968 (IPTS-68) above the gold point 1337.58K.
The comparator enables one to realize the condition corresponding to the equality Lx=Ly+Lz where Lx, Ly and Lz are the spectral radiances of radiation sources TLx, TLy and TLz, respectively. This comparator makes it possible to multiply serially the spectral radiance 2n·LAu, where LAu is the spectral radiance of the blackbody of the gold point, through repetition Lx=2n-1·LAu+2n-1·LAu, which means the condition of Ly=Lz=2n-1·LAu. With the comparator, the temperature scale above 1337.58K is realized by this process of multiplication.
The precision of the comparator is ±7mK in transferring the spectral radiance of the gold point blackbody to that of the strip lamp and ±16mK in multiplying the spectral radiance serially by the factor of two.
