MSE PhD Prospectus Defense of Kevin Man (Wenkuan)

TITLE: THERMALLY RESILIENT DEFORMABLE MIRRORS FOR HIGH ENERGY LASER BEAM COMPENSATION

PRESENTER: Kevin Man (Wenkuan)

COMMITTEE:

Thomas Bifano ME, MSE, BME, ECE; David Bishop ECE, Physics, MSE, ME, BME; Soumendra Basu ME, MSE; Jörg Werner, ME, MSE

ABSTRACT: Deformable mirrors (DMs) have been used widely in adaptive optical (AO) systems to control optical wavefront or to correct optical aberrations for astronomy, microscopy, retinal imaging, and high energy laser (HEL) optimization. For HEL optimization (aberration correction, and beam forming), DMs must have fast response to compensate for rapid changes in beam path aberrations. In addition, these DMs must be resilient to thermal and mechanical stresses induced by the high power of the incident beam. Even with high-reflectivity dielectric coatings, local heating of the DM and thermal coefficient of expansion mismatch in the DM materials can lead to unwanted distortion. A well-known problem with HEL DMs is that the residual stresses due to actuator adhesive attachments to the mirror face sheet cause the face sheet to deform in a way that cannot be compensated by the actuators. In this project, we propose a new HEL DM design and fabrication process. The core innovation in the design is to employ a single-crystal silicon face sheet that is integrated with single-crystal silicon posts to move the actuator adhesion interfaces away from the face sheet. The design aims to achieve flat face sheet surface and large actuation stroke, and a control bandwidth of up to 1kHz actuated by magnetic forces controlled by an electroplated planar copper coil array.