Rotor wind power plant and method for detecting a rotation angle

The invention relates to a rotor (4) with a rotor hub (5) and a plurality of on the rotor hub (5) arranged rotor blades (6) which are mounted about their longitudinal axis (A imaging sensor (13) to the rotor hub (5), or vice versa, are arranged such that upon rotation of the rotor blade (6) about its longitudinal axis (A