Figure 3
(a) Schematic layout of the control system with two independent drive systems for the upstream and downstream axes. (b) Typical positional errors reported by the control system when the monochromator is under real operating conditions with the crycooler liquid-nitrogen pump speed set at 30 Hz. (c) Fourier transform of (b). The peak-to-peak error reported is consistently worse for the downstream axis and it slightly exceeds 150 nrad but the majority of steps are within ±15 counts (30 counts × 4.848 nrad = 145 nrad). |