A tunable piezoelectric Fresnel mirror for high-speed lineshaping

Abstract

We present the first tunable v-shaped mirror, also known as Fresnel mirror, that may be used to generate a quasi-nondiffracting line pattern, for example for applications in laser lithography or nanomachining with femtosecond lasers. The aperture of the device is 5 mm with a surface flatness of better than λ/10, and the range of the tilting angle is 1.3–38 mrad, resulting in a fringe spacing of 123 μm down to 4.2 μm for red light at 633 nm. In contrast to usual cantilever-comb setups, the mirrors are supported on a PDMS layer and tilted by a single piezoelectric actuator, providing a high resonance frequency of 5.1 kHz. The device is fabricated using laser rapid prototyping of silicon and a casting processes of soft polymers. We show the static and dynamic characterization of the mirror and the verification of the optical functionality.