The asymmetric magnetization reversal in exchange biased FeMn F2 involves coherent (Stoner-Wohlfarth) magnetization rotation into an intermediate, stable state perpendicular to the applied field. We provide here the experimentally tested analytical conditions for the unambiguous observation of both longitudinal and transverse magnetization components using the magneto-optical Kerr effect. This provides a fast and powerful probe of coherent magnetization reversal as well as its chirality. Surprisingly, the sign and asymmetry of the transverse magnetization component of exchange biased, low-anisotropy Mn F2 and high-anisotropy Fe F2 change with the angle between cooling and measurement fields. © 2006 American Institute of Physics.