Aspects and embodiments are generally directed to compact anamorphic refractive objective lens assemblies. In one example, a refractive objective lens assembly includes a passively athermal anamorphic lens group including at least a first cylindrical lens having a surface optically powered in a first dimension, the first anamorphic lens group positioned to receive thermal infrared radiation, a focus cell positioned to receive the radiation from the anamorphic lens group, the focus cell including a first group of lenses each having a rotationally symmetric surface optically powered in the first dimension and a second dimension orthogonal to the first dimension, a relay lens group positioned receive the radiation from the focus cell, the relay lens group including a second group of lenses each having a rotationally symmetric surface optically powered in both the first and second dimensions, and a dewar assembly including a cold stop and an optical detector.