An ophthalmic illumination system includes a collimated light beam focused onto an optical fiber for transmission of the light beam to an ophthalmic light probe. A light attenuator includes a pair of arrays positioned serially in a path for the collimated beam. The arrays are movable in parallel in the path about a rotational axis orthogonal to the path and between the arrays. Each array includes a plurality of regularly spaced-apart parallel plates, the parallel plates of one array being non-parallel to the plates of the other array.