Abstract: Methods and systems for source multiplexing illumination for mask inspection are disclosed. Such illumination systems enable EUV sources of small brightness to be used for EUV mask defect inspection at nodes below the 22 nm. Utilizing the multiple plane or conic mirrors that are either attached to a continuously rotating base with different angles or individually rotating to position for each pulse, the reflected beams may be directed through a common optical path. The light may then be focused by a condenser to an EUV mask. The reflected and scattered light from the mask may then be imaged by some imaging optics onto some sensors. The mask image may be subsequently processed for defect information.