A diffraction grating light valve modulates an incident beam of light. A plurality of elongated elements each have a reflective surface. The elongated elements are suspended with their respective ends substantially coplanar. Alternate ones of the elongated elements are electrically coupled for receiving a first bias voltage. The interdigitated elongated elements are electrically coupled for receiving a second bias voltage. By applying a appropriate first and second biasing voltages, all the reflective surfaces can be maintained in a first plane. When all the elongated elements are in the first plane, the diffraction grating light valve reflects the beam of light. A predetermined group of the elongated elements, preferably alternate ones, are deformable to be substantially coplanar in a second plane which is parallel to the first plane. When the predetermined group of elements is in the second plane, the diffraction grating light valve diffracts the beam of light.