A radiometric method to measure high temperatures of black bodies using broadband-filter detectors is presented. Results of temperature measurements using a linear pyrometer and filter detectors, respectively, are compared. The performance of the black-body source and the realization of an interim detector-based spectralirradiance scale are described and discussed. The new scale is compared with the results of the 1990 Comité Consultatif de Photométrie et Radiométrie intercomparison of spectral-irradiance measurements.

Based on extensive investigations of almost 100 high-power quartz-halogen lamps covering thirteen different types, seven different manufacturers and different batches with a total operating time of about 27000 h, a new type of lamp (1000 W T6 modified FEL-type lamp, Osram Sylvania Inc.) has been selected and its operating conditions have been optimized. This lamp, which after seasoning is about ten times more stable than the best lamps used before, is recommended as a reference and transfer standard of spectral irradiance in the whole range between 250 nm and 3 µm. While excellent short-term and long-term stability over operating times of several hundreds of hours can be achieved, the disadvantages of the new standard lamp lie in a long seasoning time (80 h to 100 h) and a noticeable sensitivity of the seasoned lamps to shock and vibrations. Typical results of the characterization, calibration and reproducibility of the new standard lamp are presented and discussed in order to illustrate its performance and to demonstrate how to use it under optimal operation conditions.

Subcomparison CCPR-K1.b of the CCPR key comparison of spectral irradiance covering 200 nm to 400 nm will be carried out in 2002/03 piloted by the Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig, Germany. Deuterium arc lamps will be used as transfer standards of spectral irradiance, although they are known to have, in general, poor stability and reproducibility. PTB investigated a variety of deuterium lamps to test their capability (stability and reproducibility) for use as transfer standards. A measurement facility capable of characterizing up to three lamps at a time has been set up. Investigations of the spectral ageing pattern will help to interpolate between different reference measurements to markedly reduce the influence of ageing effects. The application of an external SiC photodiode as a monitor detector was tested. Spatial characterization of the irradiance of each lamp was also carried out. All this all helped us to find suitable types of lamp, producing reasonable irradiance homogeneously enough to be non-sensitive to small misalignments.

The spectral irradiance of lamp standards can be stabilized within a limited spectral range using a suitable selective detector to control the irradiance of the lamps. The capability of one commercial lamp facility incorporating a computer-controlled power supply was tested in an international comparison. A set of three lamps and the detector-stabilized power supply were circulated between the Physikalisch-Technische Bundesanstalt (PTB, Germany),