Double drive modes unimorph deformable mirror for femtosecond laser beam wavefront correction

Abstract

Once a laser beam suffers from wavefront aberrations, the intensity of the focal spot degrades and the shape of the focus spot distorts. The same problem also exists in femtosecond laser fabrication system. The aberrations in the femtosecond laser fabrication system contain two main components: system aberrations and aberrations from the refractive index mismatch problem. Recently, adaptive optics (AO) has been used for laser beam aberrations correction to improve the light beam quality. In this paper, we introduce an adaptive optics system with double drive modes unimorph deformable mirror (DM) into the femtosecond laser fabrication system. In the experiments, the hill-climbing algorithm based on Zernike modes is used to control the DM to correct the aberrations in the close-loop manner. After correction for system aberrations and the refractive index mismatch aberrations, the shape and maximum intensity of the focal laser spot is much improved.