Development of Parallel Image Detection System Using Annular Pupils for Scanning Transmission Electron Microscope

A parallel image detection system using an annular pupil for electron optics were developed to realize an increase in the depth of focus, aberration‐free imaging and separation of amplitude and phase images under scanning transmission electron microscopy (STEM). Apertures for annular pupils able to suppress high‐energy electron scattering were developed using a focused ion beam (FIB) technique. The annular apertures were designed with outer diameter of o/ 40 μm and inner diameter of o/32 μm. A taper angle varying from 20° to 1° was applied to the slits of the annular apertures to suppress the influence of high‐energy electron scattering. Each azimuth angle image on scintillator was detected by a multi‐anode photomultiplier tube assembly through 40 optical fibers bundled in a ring shape. To focus the image appearing on the scintillator on optical fibers, an optical lens relay system attached with CCD camera was developed. The system enables the taking of 40 images simultaneously from different scattered di...