a1 Laboratorium für Elektronenmikroskopie, Karlsruher Institut für Technologie (KIT), 76128 Karlsruhe, Germany
a2 CellNetworks, BioQuant, Universität Heidelberg, 69120 Heidelberg, Germany
Zach phase plates (PPs) are promising devices to enhance phase contrast in transmission electron microscopy. The Zach PP shifts the phase of the zero-order beam by a strongly localized inhomogeneous electrostatic potential in the back focal plane of the objective lens. We present substantial improvements of the Zach PP, which overcome previous limitations. The implementation of a microstructured heating device significantly reduces contamination and charging of the PP structure and extends its lifetime. An improved production process allows fabricating PPs with reduced dimensions resulting in lower cut-on frequencies as revealed by simulations of the electrostatic potential. Phase contrast with inversion of PbSe nanoparticles is demonstrated in a standard transmission electron microscope with LaB6 cathode by applying different voltages.
(Received March 07 2012)
(Accepted May 30 2012)