Speckle reduction

A speckle reduction mask 7 comprising a first linear array comprising first parallel lines, and a second linear array comprising second parallel lines, where the parallel lines are arranged to change the phase of incident radiation and such that cells 8 are formed at the intersections of the first parallel and second parallel lines. The phase change of each line is preferably independently and electrically controllable and the arrays may be at right angles to each other. The overall phase change of radiation passing through each subcell 8 of the mask can be 0 or pi rad and the pixels 8 may also be able to form a phase pattern generated from an orthogonal array. The second linear array may be in contact with and overlaid on the first linear array to form a grid or matrix and there may also be an electrical connection to each parallel line.