Deformable curvature and beam scanning with an elastomeric concave grating actuated by a shape memory alloy

A concave diffraction grating with a tunable radius of curvature R is fabricated by embedding a nitinol wire within an elastomeric grating replica. Curvature of the grating is controlled via the shape memory effect, where strain in the wire is recovered due to martensite-austenite phase transformations induced by resistive heating. The generated force bends the grating into a variable curvature determined by applied current. The radius of curvature for the concave grating is variable from 170 to 44 mm over a current range of 0 to 2.5 A. Actuation of R redirects the grating normal, resulting in a scanning motion of the diffracted beam.