The performance of X-ray free-electron laser beamlines may be limited by the angular aperture. Compound refractive lenses (CRLs) can be employed to prefocus the X-ray beam, thereby increasing the beamline transmission. A prefocusing CRL was implemented in the X-ray transport of the Matter under Extreme Conditions Instrument at the Linac Coherent Light Source. A significant improvement in the beamline transmission was calculated over the 3–10 keV photon energy range. At 5 keV, the relative X-ray intensity was measured and a factor of four increase was seen in the beamline transmission. The X-ray focus was also determined by the ablation imprint method.
Heimann, P., MacDonald, M., Nagler, B., Lee, H. J., Galtier, E., Arnold, B., & Xing, Z. (2016). Compound refractive lenses as prefocusing optics for X-ray FEL radiation. Journal of Synchrotron Radiation, 23(2), 425–429. https://doi.org/10.1107/s1600577516001636