Systems and methods for synchronous operation of debris-mitigation devices (DMDs) in an EUV radiation source that emits EUV radiation and debris particles are disclosed. The methods include establishing a select relative angular orientation between the first and second DMDs that provides a maximum amount of transmission of EUV radiation between respective first and second rotatable vanes of the first and second DMDs. The methods also include rotating the first and second sets of vanes to capture at least some of the debris particles while substantially maintaining the select relative angular orientation. The systems employ DMD drive units, and an optical-based encoder disc in one of the DMD drive units measures and controls the rotational speed of the rotatable DMD vanes. Systems and methods for optimally aligning the DMDs are also disclosed.