An adjustable two-dimensional lamellar grating system including a lamellar grating and a movable mirror disposed substantially parallel to one another, and an interferometer using the adjustable lamellar grating system. In one example, the lamellar grating includes a dielectric wafer having a dielectric wafer having a plurality of periodically spaced recesses formed therein, wherein the dielectric wafer has higher reflectivity at its surface facing the movable mirror than at a second opposing surface. In one example, the system also includes a mechanism for moving the mirror relative to the dielectric wafer.