Beam Scanning and On-demand Switching
Scanning and on-demand beam-deflection use electrostatic deflection plates.
Electrostatic scanning enables high ultimate scan frequencies to be employed, or
fast rise-time drive voltages for on-demand deflection, without the time-lag and
wave-form distortion that can accompany magnetic deflection.
On-demand beam-deflection in the X-plane uses plates located just down-stream
of the object slits, driven by a high-voltage amplifier triggered by the
ADC dead-time logic [1,2].
Scanning the beam on target uses one of two modes. For small scan-areas, the beam is
raster-scanned in both X and Y over an area of up to 600 x 200 µm. For larger area
scans a hybrid approach using stage stepping in X and scanning in Y yields imaging areas
of greater than >5000 x 2000 µm.
 C.G. Ryan, D.N. Jamieson, W.L. Griffin, G. Cripps and R. Szymanski, "The New
CSIRO-GEMOC Nuclear Microprobe: First Results, Performance and Recent Applications",
Nucl. Instr. Meth. B181 (2001) 12-19.
 C.G. Ryan, D.N. Jamieson, W.L. Griffin and G. Cripps, "The CSIRO-GEMOC Nuclear Microprobe:
A high-performance system based on a new closely integrated design", Nucl. Instr. Meth. B158 (1999) 97-106.