Comparison of focusing optics for femtosecond X-ray diffraction

We characterize and compare four different types of focusing optics for hard X-rays, suitable for femtosecond X-ray diffraction experiments, usinga tabletop femtosecond laser-based plasma source. We demonstrate a 23 μmfocus with a toroidally bent Ge single crystal. A maximum flux of 7× 10⁸ photons/(s mm²) 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× 10⁵ photons/(s mrad)]. The largest number of photons3× 10⁶ 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.This revised version was published online in May 2005. The Article Category was removed.This revised version was published online in August 2005 with a corrected cover date.