The moleular and sputtered/evaporated multilayers and the acid phthalate crystals can be applied for relatively fast, high effiiency spectral analysis of constant and pulsed low energy x‐ray sources in the 100 to 2000 eV region. Limits of resolution are about 1 eV. Reviewed here are the basic methods for the theoretical and the experimental characterization of these analyzers as required for absolute x‐ray spectometry. The design and absolute calibration of spectrographs for pulsed low energy x‐ray source diagnostics are described.