The development of a versatile tool to quantify magnetic anisotropies in continuous and patterned magnetic thin films is reported. The technique involves measuring the magnetooptic response to a rotating magnetic field. Similarly to mechanical torque techniques, a single measurement obtains both the anisotropy constants and their symmetry axes distribution. The technique has been applied to analyze arrays of submicrometer stripe-shaped Fe (001) elements with different interelement separations (s). For s larger than 1 μm, the anisotropy associated with the stripes is independent on separation, with a value of the effective uniaxial anisotropy constant very consistent with theoretical estimations for these systems.