Spectral irradiance scale realization and uncertainty analysis based on a 14 mm diameter WC-C fixed point blackbody from 250 nm to 2500 nm

Abstract Spectral irradiance scale in the wavelength range from 250 nm to 2500 was realized at National Institute of Metrology (NIM) on basis a large area tungsten carbide–carbon (WC-C) high temperature fixed point blackbody, which is composed 14 mm diameter WC-C cell and variable blackbody BB3500MP as furnace. A series 1000 W FEL halogen lamps were used transfer standards. The new spectral compared with based variable-temperature BB3500M, divergence between these two methods varied -0.66% 0.79% 280 2100 nm. measurement uncertainty fixed-point analyzed, expanded estimated 3.9% nm, 1.4% 0.43 % 400 0.27% 800 0.25% 0.62% 1500 0.76% 2000 2.4% respectively. In 300 improved obviously: decreased by more than 25% blackbody. Below became higher because signal noise ratio poor. Above 1100 contribution decreases, therefore uncertainties are almost same level. also realize correlated colour distribution filament lamp, deviation method -0.5 K -2.9 K,