2 NEW OPTICAL DESIGNS FOR SOFT-X-RAY SPECTROMETERS USING VARIABLE-LINE-SPACE GRATINGS

Two new optical designs for soft x-ray spectrometers using variable-line-space (VLS) gratings are described, characterized, and compared. One design, using VLS rulings on a spherical substrate, is characterized both analytically and with ray tracing. The second, using a concave focusing mirror and a plane VLS grating, is ray traced. Performance is optimized using line spacing described by a third-order polynomial. For the single element design, resolving powers of approximately 1300 and above are achieved over the energy range from 300 to 1000 eV in a compact (1-m-long) instrument, with performance limited by the resolution of the electronic area detector to be used with the design. © 1995 American Institute of Physics.