The laboratory end-to-end testing of the Extreme-Ultraviolet Imaging Spectrometer (EIS) for the Solar-B satellite is reported. A short overview of the EIS, which observes in two bands in the extreme-ultraviolet wavelength range, is given. The calibration apparatus is described, including details of the light sources used. The data reduction and analysis procedure are outlined. The wavelength calibration using a Penning source to illuminate the aperture fully is presented. We discuss the aperture determination using a radiometrically calibrated hollow-cathode-based source. We then give an account of the predicted and measured efficiencies from consideration of the efficiencies of individual optical elements in first order, an account of efficiencies out of band when radiation incident in one band is detected in the other, and efficiencies in multiple orders. The efficiencies measured in first order for in band and out of band are compared with the predictions and the sensitivity, and its uncertainties are derived. Application of the radiometric calibration is discussed.
After the shutdown of the BESSY I electron storage ring, PTB's two normal-incidence monochromator beamlines for the calibration of radiation sources and detectors in the wavelength range from 40 nm to 400 nm were transferred to PTB's new radiometry laboratory at BESSY II. In this paper, the beamlines and their properties are briefly described. First results for the calibration of secondary source standards and detector standards at BESSY II are shown and demonstrate the successful re-establishment of the measurement capabilities. In the ultraviolet, calibration of deuterium lamps was reproduced within 1% and of silicon trap photodetectors within 0.2%.
The prelaunch spectral-sensitivity calibration of the solar spectrometer SUMER (Solar Ultraviolet Measurements of Emitted Radiation) is described. SUMER is part of the payload of the Solar and Heliospheric Observatory (SOHO), which begins its scientific mission in 1996. The instrument consists of a telescope and a spectrometer capable of taking spatially and spectrally highly resolved images of the Sun in a spectral range from 50 to 161 nm. The pointing capabilities, the dynamic range, and the sensitivity of the instrument allow measurements both on the solar disk and above the limb as great as two solar radii. To determine plasma temperatures and densities in the solar atmosphere, the instrument needs an absolute spectral-sensitivity calibration. Here we describe the prelaunch calibration of the full instrument, which utilizes a radiometric transfer-standard source. The transfer standard was based on a high-current hollow-cathode discharge source. It had been calibrated in the laboratory for vacuum UV radiometry of the Physikalisch-Technische Bundesanstalt by use of the calculable spectral photon flux of the Berlin electron storage ring for synchrotron radiation (BESSY)-a primary radiometric source standard.
The Physikalisch-Technische Bundesanstalt (PTB) operates at the electron storage ring BESSY a calibration facility for the normal incidence spectral region which can be used for measurement of the spectral radiance of transfer standards such as deuterium lamps and tungsten ribbon lamps. Because BESSY is not a standard of spectral radiance, radiation fluxes are compared and the area of the transfer source under investigation is determined by imaging the source on to a precisely measured aperture which acts as an entrance slit of the monochromator. Polarization effects are determined by rotating the complete calibration facility around the axis of the incoming radiation. Relative uncertainties of 2 % (1 ) for the spectral radiance are achieved, with the main contributions arising from inhomogeneity of the focusing mirror, geometry and alignment.
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