A cantilevered liquid‐nitrogen‐cooled silicon mirror for the Advanced Light Source Upgrade.

This paper presents a novel cantilevered liquid‐nitrogen‐cooled silicon mirror design for the first optic in a new soft X‐ray beamline that is being developed as part of the Advanced Light Source Upgrade (ALS‐U) (Lawrence Berkeley National Laboratory, USA). The beamline is optimized for photon energies between 400 and 1400 eV with full polarization control. Calculations indicate that, without correction, this design will achieve a Strehl ratio greater than 0.85 for the entire energy and polarization ranges of the beamline. With a correction achieved by moving the focus 7.5 mm upstream, the minimum Strehl ratio is 0.99. This design is currently the baseline plan for all new ALS‐U insertion device beamlines. [ABSTRACT FROM AUTHOR]