Focused x-ray beams: Generation and Applications

Ever since the discovery of x-rays, there has been a strong desire to generate more and more intense x-ray beams focused in smaller and smaller spot size. The major breakthrough towards the increase in brightness of x-ray sources came with the availability of synchrotron storage rings in the 70’s. The physics of x-ray science and technology has grown tremendously with the availability of third generation synchrotron sources and x-ray free electron lasers. Towards the utilization of these sources, focusing of these bright beams to smaller and smaller spot size has been an equally challenging task. The refractive index of all materials is very near the refractive index of vacuum. Thus it is a technological challenge to focus x-ray beams using reflection, refraction and diffraction. The talk gives an overview of the science and technology towards the generation of intense sub micron x-ray beams and their applications. This will be followed by the capabilities of Indus-1 and Indus-2 synchrotron sources operating at RRCAT, Indore as national facilities. Some of the efforts done at RRCAT, towards development of x-ray focusing optics, will be presented. The developments include x-ray multilayer optics, x-ray wave guides, x-ray lithography for fabrication of refractive/diffractive x-ray optics and evaluation of ASTROSAT soft x-ray telescope optics.