Multiple spots of illumination arc generated with an arrangement of optical elements. The multiple -spots of illumination may be used to illuminate multiple metrology marks and/or other targets at the same time, and/or for other purposes. The arrangement of optical elements is relatively low cost compared to other methods of generating multiple spots of illumination, and is compatible with existing metrology systems. Advantageously, the present systems and methods provide off axis illumination spots, which facilitate separation of ghost reflections from intensity channel measurements in such systems. Additional light paths are created in collimated space at different angles relative to each other, thus forming separate illumination spots on a target. The illumination spots can be arranged along one axis on the target, or in a two dimensional pattern, for example. According to an embodiment, a system for generating spots of illumination configured to be directed at a target is provided. The system comprises a first optical element configured to receive illumination from an illumination source along a first axis, reflect a first portion of the illumination away from the first axis, and transmit a second portion of the illumination along the first axis. The system comprises a second optical element configured to receive the first portion of the reflected illumination and at least partially reflect a third portion of the illumination along a second axis that is at a different angle from the first axis. The second portion and the third portion of the illumination are directed toward the target at an angle relative to each other in a pupil plane to create two different spots of illumination on the target. In some embodiments, the system comprises a third optical element configured to receive and fully reflect a fourth portion of the illumination along a third axis that is at a different angle from the first axis and the second axis. The fourth portion of the illumination is transmitted by the second optical element. The second portion, the third portion, and the fourth portion of the illumination are directed toward the target at different angles relative to each other in the pupil plane to create three different spots of illumination on the target, In some embodiments, a spot of illumination corresponding to the illumination from the first axis comprises an on axis spot, and a .spots of illumination corresponding to the illumination from the second and third axes comprise off axis spots. In some embodiments, an off-axis spot is configured to reduce or eliminate ghost reflections. In some embodiments, the first optical clement, the second optical element and the third optical elements arc movable relative to each other. In some embodiments, movement of the first optical element, the second optical element, and/or the third optical element is configured to adjust locations of corresponding spots of illumination on the target. In some embodiments, movement comprises tilting the first optical element, the second optical element, and/or the third optical element; and/or changing a distance between one or more of the first optical element, the second optical element, and the third optical element. In some embodiments, the first optical element, the second optical element, and the third.
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