A calibration system and method for calibrating a detector are disclosed. In one example, the calibration system comprises a plurality of radiation sources configured to emit electromagnetic radiation, a positioning mechanism disposed opposite the plurality of radiation sources, having a single degree of freedom with respect to the plurality of radiation sources, and an optical element coupled to the positioning mechanism, and configured to rotate to a plurality of calibration positions, the optical element in each of the plurality of calibration positions being configured to receive the electromagnetic radiation from a corresponding radiation source and to reflect the electromagnetic radiation to the detector.