Holographic lithography, in which the interference pattern of two coherent waves is used to expose a resist film, is the preferred technique for producing large‐area gratings with low distortion. The spatial period of a pattern produced by holographic lithography is directly proportional to the wavelength of the radiation and inversely proportional to the sine of one‐half the angle between the incoming beams. To expose gratings with periods ≊100 nm (50‐nm‐nominal linewidth) the source wavelength must be ≊200 nm. Since coherent deep‐ultraviolet sources are not readily available, we have investigated an achromatic holographic configuration which permits the use of incoherent sources (e.g., CdXe arc lamp) or short‐coherence‐length (≊10 μm) excimer lasers. The configuration consists of two gratings, one acting as a beamsplitter, the other as a recombiner. The beam from the source is split into plus and minus first‐order beams by the beamsplitter grating, and the zero order is subsequently blocked. The plus and minus first‐order beams are again diffracted by the recombiner grating onto the substrate. The intensity recorded at the substrate has a spatial period one‐half that of the beamsplitter grating. An analysis of this configuration shows that the intensity pattern on the substrate is independent of both the source wavelength and the angle of incidence (i.e., spatial coherence). For the configuration to be truly achromatic with high contrast the two interferometer arms must have equal path lengths within a small ‘‘window.’’ Tests of this configuration with parent gratings of 540 nm period and a Hg arc lamp produce good contrast photoresist patterns at 270 nm period, and tests with an ArF excimer laser and 250‐nm‐period parent gratings produce 125‐nm‐period patterns in polymethylmethacrylate (PMMA). This achromatic deep UV setup is similar to a proposed x‐ray interferometer and serves as a test bed for solving problems of alignment.