Comparison of focusing optics for femtosecond X-ray diffraction

摘要

We characterize and compare four different types of focusing optics for hard X-rays, suitable for femtosecond X-ray diffraction experiments, using a tabletop femtosecond laser-based plasma source. We demonstrate a 23 μm focus with a toroidally bent Ge single crystal. A maximum flux of 7 x 10~8 photons/(s mm~2) is generated in a 32 μm focus using a multi-layer mirror. An elliptical glass capillary yields the highest number of photons per Bragg angle [2 x 10~5 photons/(s mrad)]. The largest number of photons [3 x 10~6 photons/s] per second is obtained in the 105 μm focus of a poly-capillary optical lens system. All numbers are given for characteristic Cu K_α photons.