Ultrafine figuring for glue-free deformable mirror

PZT (lead zirconate titanate)-glued bimorph deformable mirrors are widely used in hard x-ray regimes[1], however, they have not yet been used in soft X-ray regimes because they are less compatible for usage under high vacuum. Therefore, we have developed a glue-free bimorph deformable mirror, in which silver nanoparticles were employed to bond PZT actuators to mirror substrates[2]. In this study, we achieved a 2 nm figure error on an elliptical shape of a glue-free deformable mirror. We evaluated the figure change characteristics due to humidity and temperature increasing at the ultrafine figure error condition.