Characterization of a compact multilayer mirror (MLM) polarimeter for measurements of the degree of linear polarization in the 256-A to 584-A wavelength EUV range

A molybdenum/silicon (Mo/Si) multilayer mirror (MLM) polarimeter has been constructed and used to analyze the extreme ultraviolet (EUV) emission from excited HEI and HeII states following electron impact on helium for wavelengths ranging from approximately 256 angstrom to 584 angstrom. A ratio of reflectivities for s and p polarized light, Rs/Rp approximately equals 10, and a resolving power of (lambda) /(Delta) (lambda) approximately equals 6 at 304 angstrom were obtained. These characteristics and the use of a VYNS26 spectral filter were sufficient to allow a detailed polarization study of the first two members of the Lyman series of He+ at wavelengths of 304 angstrom (HeII 2p yields 1s) and 256 angstrom (HeII 3p yields 1s) for impact electron energies ranging from threshold to 1500 eV. The MLM has also been used as a single flat surface mirror polarimeter for the analysis of longer wavelength radiation (517 angstrom to 584 angstrom) from the HeI (1snp) 1Po yields (1s2) 1S series of neutral helium with Rs/Rp approximately equals 3. While MLM polarimeters have previously been used for EUV measurements with bright photon sources such as those provided by synchrotron facilities, the results from this work clearly demonstrate the feasibility of such devices with lower intensity electron and ion impact sources. The compact design of the apparatus makes it suitable as a portable measurement and calibration device.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.