Development of ultrathin deformable mirror for a novel sub-10nm focusing optical system

X-ray analysis enables nondestructive observation of the internal structure of samples with high spatial resolution. Focusing x-rays at the nanometer scale further enhances spatial resolution. Among various types of focusing optics, total-reflection mirrors exhibit high reflectivity and wavelength independence. However, achieving both ultra-high resolution and wavelength independence simultaneously remains challenging. To address this challenge, we propose a novel focusing optical system comprising multiple ultrathin total-reflection mirrors. Calculation results show that a four-mirror setup can focus x-rays down to 3.2nm. Furthermore, this design maintains wavelength independence because all the mirrors satisfy the total-reflection condition. However, realizing this optical system poses significant challenges: the mirrors must be thinner than 40μm, and the required shape accuracy is on the order of nanometers. Achieving the required thickness and precision is challenging with conventional fabrication and manipulation methods. To overcome these difficulties, we developed ultrathin deformable mirrors using single-crystal piezoelectric material.