ABSTRACT
The Physikalisch-Technische Bundesanstalt (PTB) has a long tradition in the calibration of radiation sources in the ultraviolet and vacuum ultraviolet spectral range, with traceability to calculable synchrotron radiation. Within this context, new instrumentation in the PTB laboratory at the Metrology Light Source (MLS) has been put into operation that opens up extended and improved calibration possibilities. A new facility for radiation source calibrations has been set up in the spectral range from 7 nm to 400 nm based on a combined normal incidence-grazing incidence monochromator. The facility can be used for the calibration of transfer sources in terms of spectral radiant intensity or mean spectral radiance, with traceability to the MLS primary source standard. We describe the design and performance of the experimental station and give examples of some commissioning results.
ABSTRACT
In the laboratory of the Physikalisch-Technische Bundesanstalt (PTB) at the Berlin electron-storage ring BESSY II, a procedure has been developed to investigate the dependence of vacuum-ultraviolet reflection on polarization. It is based on characterizing the elliptically polarized synchrotron radiation at PTB's normal-incidence monochromator beamline for reflectometry by means of polarization-sensitive photodetectors. For this purpose, the polarization dependency in the detector responsivity was determined at a small, low, solid angle of acceptance for the synchrotron radiation, i.e., within the orbital plane of the storage ring where the degree of linear polarization is known to be almost 100%. Our method allows the polarization dependence of reflection samples to be measured with relative standard uncertainties ranging from 2.4% to 11% in the spectral range between 60 and 160 nm. The method has been applied to the optimization of polarizing mirrors at the Lyman-alpha wavelength of 121.6 nm.