Novel instruments for ultra-soft X-ray emission spectroscopy

Two alternative instrument designs to the traditional Rowland grating spectrometer for high resolution ultra-soft X-ray spectroscopy are presented. The first instrument is a plane grating spectrometer using off-axis parabolic mirrors for collection and refocusing, and with a spatially resolving multichannel detector with delay line read-out. The instrument offers substantially higher performance in terms of resolution and sensitivity than traditional instruments. The second instrument is a Fourier transform spectrometer based on a grazing incidence Mach–Zehnder interferometer using wavefront dividing beamsplitters. The path length difference can be scanned over 0.1 mm, which corresponds to a resolution of 12 meV.