The invention includes a method and apparatus for controlling curvatures of light directing devices. The apparatus includes a first substrate portion having formed therein a plurality of cavities, and a substantially flexible membrane disposed over the cavities for forming a respective plurality of light directing mechanisms, the light directing mechanisms disposed over the cavities. The respective curvatures of the light directing mechanisms are set using a pressure difference across each of the membrane portions disposed over the cavities. The respective curvatures of the light directing mechanisms may be controllably adjusted during operation of the light directing mechanisms.