Dynamically deformable micromirror array for defined laser beam shaping and homogenizing
We present a dynamic laser beam shaper than can generate smooth flat top and gaussian intensity profiles. It consists of a 100% fill factor membrane, supported by beams or posts, that deforms in a shape similar to a concave linear or 2D microlens array. The dynamic and tunable focal lengths allow to change the diffusion angle or to switch between flat top or gaussian output optical profiles. The whole array is fabricated over a rotating stage that enables the averaging of the interference effects caused by the array. Experiments showed that an angle of only 0.18° smooth the interferences to a contrast of 0.04. Optical simulations were performed to design the device. A first prototype using a magnetic scanner was tested to validate the simulations. Fabrication of the rotating stage and the membrane was accomplished using surface and bulk micromachining using parylene trench refilling.