Characterization of a filter radiometer designed for absolute optical measurements

A filter radiometer was designed to use for the realization of optical radiometric scales with high accuracy at the Ulusal Metroloji Enstitusu, Turkey. The primary aim in developing the new filter radiometer is to improve the traceability and accuracy of radiometric quantities of the Systeme International (d'unite's) (SI units). This filter radiometer basically consists of a trap detector, a set of temperature-controlled filters and a precision aperture. Complete characterization of the radiometer is described in this paper. The absolute calibration of the filter radiometer is performed by using an electrical substitution cryogenic radiometer at discrete laser lines with a relative uncertainty of the order of 0.01%.