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Recently, extreme ultraviolet interference lithography using a single grating interferometer and a highly coherent synchrotron insertion device source has proven to be an extremely useful technique for producing patterns with feature sizes in the range of 10 nm. The high demand for these nanoscale patterns and the small number of suitable highly coherent extreme ultraviolet sources has created new interest in the cascaded grating interferometer because of its relaxed demands for spatial and temporal coherence. This work extends that of earlier researchers on such systems by providing a compact algebraic analysis of the effects on fringe contrast of source divergence, spectral bandpass, lack of parallelism of the grating rulings, grating period mismatch, defocus, and wavefront curvature. The results are applied to illustrate the feasibility of implementing the interferometer on a small bending magnet synchrotron source, but the analysis should be applicable to typical portable plasma sources as well.