Design of a high-throughput grazing-incidence flat-field spectrometer

The optical design of a high-throughput grazing-incidence flat-field spectr ometer is presented. The spectral focal curve is almost a straight line bec ause of the flat-field focusing properties of spherical variable-line-space d gratings. The angular acceptance in the direction perpendicular to the pl ane of dispersion is maximized by means of a focusing spherical mirror moun ted with its tangential plane coincident with the sagittal plane of the gra ting. Analytical calculations for the determination of the optimum mirror p arameters are presented. A spectrometer for high-throughput experiments in the 800-60-eV region is designed with an extreme-ultraviolet-enhanced CCD d etector: when the available flux is compared with that of a spectrometer wi th the same kinds of grating and detector but without a focusing mirror, th e increase is as much as a factor 3. (C) 2000 Optical Society of America OC IS codes: 059.1950, 080.1010, 120.6200, 220.1000, 260.7200.