  This paper discusses several optical elements now in use at BL43LXU, the
RIKEN Quantum NanoDynamics Beamline, of the RIKEN SPring-8 Center. BL43LXU is
dedicated to meV-resolved inelastic x-rays scattering using spherical analyzers
operating between 15.8 and 25.7 keV. The work described here is relevant for
setups on the high-resolution spectrometer (10m two-theta arm) with resolution
between 2.8 and 0.8 meV. Specific optics discussed include a multilayer
Kirkpatrick-Baez (KB) mirror pair that focuses the full (~1x3mm2) beam at 17.79
keV to a 4.4 X 4.1 {\mu}m2 spot with ~60% throughput, two different types of
Soller slits that help reduce backgrounds, masks for the analyzers that allow
increased solid angle to be collected while preserving momentum resolution, and
a diamond quadrant beam position monitor (BPM). These elements have been used
and facilitate experiments in extreme conditions with diamond anvil cells, and
liquid measurements at low momentum transfers, among other work.
