Simulational and experimental investigation on the print-through high-frequency aberration of the shear-joint NIF deformable mirror.

Abstract

A shear-joint deformable mirror (DM) is important in the high-power laser systems such as the National Ignition Facility (NIF). In this paper, the print-through high-frequency aberration (PT-HIFA) that arises from adhesive curing and is corresponding to the actuator array is reported to exist in the initial surface shape of a lab-made shear-joint NIF DM. Meanwhile, experimental results show that the PT-HIFA has a great modulation on the laser intensity. This PT-HIFA could not be corrected effectively by the DM and may result in dangerous damage in the high power laser systems. In order to eliminate the PT-HIFA, we investigate the influence of the structural parameters on the PT-HIFA in a shear-joint DM through simulation and experiment. Simulational results show that the structural parameters have different influences on the PT-HIFA. In the experiment, by optimizing the structural parameters, the PT-HIFA could be eliminated in the shear-joint NIF DM and the modulation effect on the laser intensity could be removed. This investigation could help other researchers to determine appropriate structural parameters and to achieve a fine surface shape in their own shear-joint DMs.