VARIED LINE-SPACING PLANE GRATING MONOCHROMATOR FOR UNDULATOR BEAMLINE

A varied line-spacing plane grating monochromator is installed at an u ndulator beamline BL-19B of the Photon Factory. Small contribution of aberrations to image sizes at a focal plane of the varied line-spacing plane grating is calculated with use of an optical path function. The largest resolving power obtained from a ray tracing is estimated to b e 4600 at a photon energy of 1239.85 eV and 10 000 at 91.2 eV. Gas abs orption spectra show the similar extent of resolution obtained by the ray tracing. A high brightness with a high resolution may be realized in this monochromator. (C) 1996 American Institute of Physics.