Here, we describe a flat-field-response, four-channel x-ray imaging instrument developed to study hotspot asymmetries in inertial-confinement fusion experiments. We discuss the details of its design and optical characterization, the diagnostic deployment of the device, and experiments with it. We achieved a spatial-response flatness better than ∼8.4% within a ±200 µm field of view (FOV), with a spatial resolution of ∼4 µm at the center of the FOV. We used the system to characterize the low-order asymmetry of the implosion hotspot, and we obtained improved results after adjustments to improve the irradiation symmetry. Due to the flat-field-response characteristic, the versatile instrument also has the potential to be applied to diagnostics for the hotspot electron temperature and the Rayleigh-Taylor instability.