A ferromagnetic shape memory actuator designed for large 2D optical scanning

A thin film actuator of a ferromagnetic shape memory alloy (FSMA) is presented allowing two degrees of freedom (2D) control of a bulk micromirror. The actuation mechanism is based on a simultaneous ferromagnetic and martensitic transformation. The movable parts of the actuator are designed as a monolithic device with two thermally and magnetically decoupled actuation units, which is demonstrated by coupled finite element simulations. The problem of FSMA thin film integration is solved by a novel transfer bonding process. First demonstrators of the FSMA actuator show a highly nonlinear response at low actuation voltage allowing large optical scanning angles up to 65° at tuneable frequencies.