Nearly stigmatic toroidal grazing-incidence spectrometer in the 100-300-A range: design.

We have performed an initial design study on a single-element aberration-corrected holographic toroidal spectrometer for use in diagnosing extreme ultraviolet laser amplifiers that we plan to study as part of ourtabletop extreme ultraviolet laser project at MIT. The spectrometer is designed to be 7 m long from source to image with an incidence angle of 80 degrees and a 450-line/mm holographic grating. The instrument isdesigned to be nearly stigmatic between 100 and 300 A to sufficient precision to allow two-dimensional imaging with a 10-microm resolution. As a spectrometer the ideal resolution (with a zero slit width and a 25-microm spatial resolution at the image) is designed to be lambda/Deltalambda asymptotically equal to 5000.