A micromirror array includes a substrate, a plurality of mirrors for reflecting incident radiation, and for each mirror of the plurality of mirrors, a respective post connecting the substrate to the respective mirror. The micromirror array further includes, for each mirror of the plurality of mirrors, one or more electrostatic actuators connected to the substrate for applying force to the respective post to displace the respective post relative to the substrate, thereby displacing the respective mirror. Also disclosed is a method of forming such a micromirror array. The micromirror array may be used in a programmable illuminator. The programmable illuminator may be used in a lithographic apparatus and/or in an inspection apparatus.