A spatial light modulator comprises: a first substrate (25); a second substrate (26); a layer of electrooptic material disposed between the first substrate and the second substrate. A first electrode arrangement (27) is disposed over the first substrate (25); and a second electrode arrangement (35) is disposed over the second substrate (26). The first electrode arrangement (27) comprises first and second electrode layers (28,29) disposed over the first substrate, with the spacing between the first electrode layer (28) and the first substrate (25) being different to the spacing between the second electrode (29) layer and the first substrate (25). The first electrode layer (28) and the second electrode arrangement (35) are configured so as to co-operate, in use, to define a plurality of first addressable regions in the electrooptic material. The second electrode (29) layer and the second electrode arrangement (35) are configured so as to co-operate, in use, to define a plurality of second addressable regions in the electrooptic material.