PERFORMANCE OF A MULTI-WAVELENGTH FILTER RADIOMETER FOR SPECTRAL IRRADIANCE MEASUREMENT IN THE NEAR IR

The performance of an automatic multi-wavelength filter radiometer (MWFR) in the near IR range is evaluated using a three-element InGaAs trap detector and nine narrow-band interference filters from NMC (Singapore) and MIKES (Finland) in a joint experiment conducted by researchers from both labs. Comparisons of detector spectral responsivity and filter spectral regular transmittance in the same wavelength range are also carried out. The maximum relative deviation of the measured photocurrent using MWFR and of the calculated photocurrent using known spectral irradiance values from a standard lamp is less than 1.8% with an expanded uncertainty of 1.9% (k = 2). From the promising results obtained from this and earlier work, it is concluded that a direct realisation of the spectral irradiance scale in the wavelength range of 300 run to 1600 nm is possible using the MWFR.