Ultraprecise piezoelectric deformable mirrors have been developed to construct adaptive X-ray focusing optics whose optical parameters can be varied while simultaneously performing wavefront correction. We designed and developed a deformable mirror that did not have high-spatial-frequency deformation errors. Using a Fizeau interferometer, we demonstrated that the mirror could be deformed with a peak-to-valley figure accuracy of 5 nm. In addition, wave-optical simulations based on the Fresnel–Kirchhoff integral revealed that the mirror could focus hard X-rays to 90 nm under diffraction-limited conditions.
MEMS deformable mirror for wavefront correction of large telescopes