Deformable optical elements may be physically altered through fluid displacement. We imprint a grating surface onto an elastomeric membrane by soft lithography. The membrane is installed as a flexible wall of a sealed fluidic chamber. Injection of excess fluid into the chamber induces expansion of the membrane, effectively varying the groove spacing of the imprinted grating. In transmission experiments using a broadband light source, we are able to achieve a 127.2-nm shift in peak wavelength with an injected fluid volume of 0.56 ml. A paraboloid model of the change in curvature of the grating during expansion accurately describes our experimental results.