Abstract

The grating/crystal monochromator (GCM) consists of an initial 2° grazing angle paraboloidal mirror which collimates the synchrotron radiation from the electron beam source; a final identical paraboloidal mirror which focuses collimated monochromatic radiation to the fixed exit slit in a 1:1 image of the source; and a pair of plane diffracting elements or a mirror/diffracting element pair which monochromatize the radiation in the region of collimated light between the paraboloidal mirrors. The diffracting elements can be either crystals or gratings giving an unprecedented spectral range in one instrument from the UV to 2 keV. The two-crystallike scanning motion is ideal for an always on-blaze condition with diffraction gratings. We will report on performance tests with a plane mirror/grating pair (600 g/mm) installed in the scanning system. We present measurements of the exit slit image, the quality of which is fundamental to the resolving power of the instrument. The image quality is influenced by the source size and stability, mirror alignment, and possible mirror figuring errors. Preliminary results on spectral flux, higher-order flux, and absorption edge resolution to 100 eV are presented. Calibration and stability of the mechanical system of the GCM and the critical laser angle interferometer that encodes the orientation of the mirror/grating pair are discussed. Wavelength calibration via absorption edge spectral location is outlined.

© 1985 Optical Society of America