Development of x-ray adaptive focusing optical system based on the combination of concave mirror and convex mirror (Conference Presentation)

Abstract

In synchrotron radiation facilities and X-ray free electron laser facilities, beam size adjustment depending on the experimental condition and the sample size is necessary. Various types of X-ray focusing optical systems are used for beam conditioning. However, they are specially designed for specific purposes and optical parameters such as numerical aperture (NA) and focal length are fixed. This lack of adaptability has limited application targets. In this research, we are developing X-ray adaptive focusing optical system which can control the beam size without moving the position of the focus. The optical system consists of two deformable mirrors in one dimension. In order to control the focused beam size, the NA can be controlled by deforming the mirror shapes from concave to convex. When we want to achieve large NA, deform the upstream mirror into convex shape and spread the beam. The downstream mirror receives X-ray with full aperture and X-ray is focused at focal point. When we want to achieve small NA, deform the upstream mirror into a concave shape and narrow down the reflection area of downstream mirror. NA becomes small because reflection area of downstream mirror becomes narrow. One dimensional focusing experiment of large NA adaptive optical system was performed at SPring-8 as a demonstration. A focused beam with an intensity profile having a full width at half maximum of 134 nm was achieved at 10 keV. This is close to ideal beam size. In my presentation, I will explain details of adaptive focusing optics and deformable mirrors.