Compact high-resolution soft-x-ray spectrograph design using two matched grazing-incidence gratings.

A novel and simple soft-x-ray grating-spectrograph design for high-resolution plasma-spectroscopy applications is presented and analyzed. This design uses dual, matched, concave varied-groove-density gratings to provide high dispersion and slit magnification and can achieve a very high spectral resolution (λ/Δλ > 25,000) in an instrument that is less than 1 m in length while using detectors, such as microchannel plates, with relatively coarse spatial resolutions. The advantages of this design over other designs with a comparable spectral resolution include its simplicity and small size, whereas the disadvantages include a narrow useful spectral range (λ/Δλ ≈ 50). Potential applications include x-ray laser linewidth measurements.