Shape memory actuation of a deformable grating for natural color displays

Abstract

We demonstrate some of the mechanical and optical properties of an elastomeric concave diffraction grating actuated by a nitinol wire, a shape memory alloy (SMA). The nitinol wire is embedded into the elastomeric grating and is activated through resistive heating. Grating radius of curvature ranges from 174 mm to 44 mm within an applied current range of 0 A to 2.5 A. We model the behavior of the changing curvature based on the austenite-martensite phase transition which follows an exponential approach to a final temperature determined by the electric current. Coated with Cr-Cu-Cr, the deformable concave grating shows the ability to diffract perceivable wavelengths of light.