High Throughput Fabrication Process of a Zernike Phase Plate

Abstract

In transmission electron microscopy (TEM) for biological and polymer samples, it is difficult to image with high contrast, since they are mostly composed of light elements and have similar density. One solution to enhance the contrast is utilization of phase contrast microscopy, which is realized in optical microscopy. Accordingly, many types of phase plates for electron microscopy have been proposed. Zernike phase contrast TEM (ZPC-TEM) with a Zernike phase plate (ZPP) provides higher contrast at Af (defocus) = 0 with respect to one in conventional TEM [1]. ZPC-TEM attracts much attention in Cryo-TEM applications such as cryo-electron tomography and single-particle analysis [2], because their specimens are easy to be damaged with electrons and they need high contrast with minimum dose on the specimen.

Phase plates in the transmission electron microscope: operating principles and applications

“…The effect of contamination and means for controlling it are discussed in Section Contamination build up. The film contamination and aging studied in the context of ZPP is also applicable to HFPP [6,120,[122][123][124][125][126][127].…”

“…Since under typical conditions, the beam diameter at the HFPP does not exceed a few µm, a 100 µm diameter aperture covered with a HFPP film provides enough film area for hundreds of HFPP experiments. While the steps above are required to retrofit a HFPP in an existing TEM [95,118], instrument manufacturers offer specialized (heated) aperture support and high quality commercial HFPP films [119,120,126]. Commercial HFPP hardware is often equipped with convenient HFPP positioning software and hardware [127][128][129].…”

“…The fact that the HFPP aperture is moved with the beam blanked implies that the HFPP film needs to be flat over the distance over which the aperture moves, i.e. no more than a few nm variations of the HFPP height over a few µm [119,126].…”