The LISA diffractometer beam-tilting component. Schematic views of (a) the front view of the beam-tilter and `explosion drawing' with the beam-tilter opened along the centre axis. Shown are (b) the crystal translation and rotation stages and (c) the `mirror' translation and rotation stages. The Bragg crystals are shown on both sides to illustrate the geometry. The central components are: (1) tilt stage housing, (2) translation for second crystal, (3) `mirror' translations, (4) first crystal rotation, (5) first crystal `mirror' rotation, (6) ion chamber, (7) second crystal rotation, (8) second crystal `mirror' rotation, (9) diamond diode and ion chamber, (10) absorber wheel, (11) air pads for stage positioning, (12) rotating air bearing for the tilter, (13) tilter reinforcement.