Improvement of 3D images by use of prism-shaped sections

A quadrangular prism specimen made of a block copolymer nanostructure (a 'prism-shaped' section) was observed in three dimensions (3D) by transmission electron microtomography (TEMT) over as wide a tilt range as possible. A cross section of the prism-shaped section was 200 nm on each side. For comparison, a conventional ultra-thin section having the same thickness as the prism-shaped section was employed. The image quality of the projections taken at a high tilt angle, e.g. 60° of the prism-shaped section was better than that of the ultra-thin section because its effective thickness was thinner than the ultra-thin section at the same tilt angle. As a result, the projections at very high tilt angles, e.g. ± 75°, can be used for the 3D reconstruction in the case of prism-shaped sections, while those at such high tilt angles obtained from the ultra-thin section become so blurred that they may not be appropriate for use in the reconstruction. By use of a prism-shaped section, the contrast of the reconstructed image was significantly enhanced. The elongation of the images along the optical axis of microscope due to the Missing Wedge was also considerably reduced in the case of the prism-shaped section.