These stacks of carefully polished, coated and cut silicon wafers – normally used to manufacture integrated circuits – will focus X-rays inside ESA’s Athena space observatory, due for launch in 2028. See http://www.esa.int/spaceinimages/Images/2016/12/Silicon_pore_optics_stacks
More on Athena: http://sci.esa.int/cosmic-vision/54517-athena/
