Abstract
Tools for taking advantage of phase-contrast in transmission electron microscopy are of great interest for both biological and material sciences studies as shown by the recent use of phase plates and the development of holography. Nevertheless, these tools most often require highly qualified experts and access to advanced equipment that can only be considered after preliminary investigations. Here we propose to address this issue by the development of an ImageJ plugin that allow the retrieval of a phase image by simple numerical treatment applied to two defocused images. This treatment based on Tikhonov regularization requires the adjustment of a single parameter. Moreover, it is possible to use this approach on one-image. Although in that case the retrieved image gives only qualitative information, it is able to enhance the image contrast appropriately. This can be of interest for specimens producing low contrast images under the electron microscopes, such as some frozen hydrated biological samples or those sensible to electron radiation unsuitable for holographic studies.
Highlights
Characterization of nanometric objects is becoming crucial to address environmental and technological problems in biology and material sciences
The gold nano-particles system is important for evaluating Simplified Phase Contrast Images (SPCI) from a quantitative point of view while the other examples aim at illustrating its potential for biological systems
When dealing with images as above with the SPCI plug in, the a parameter necessarily corresponds to a number of pixels, the pixel unit being defined by the reciprocal space distance 1/Np where N is the number of pixel of the image and p the pixel size in direct space
Summary
Because Transmission Electron Microscopy (TEM) has high spatial resolution, it is the method of choice to address these issues. Due to their size and low average atomic number some objects give rise to a low contrast impeding their differentiation from the background. There is a drawback tough, as on the phase-contrast image the object contour and the size change with the focusing of the objective lens. It is worth noting that the phase function Φ(r) represents the object (with the only bias of the projection effect), while the image I(r) is modified by a CTF that depends on the imaging conditions, i.e. the electron wavelength and the objective lens characteristics (aberration coefficients, Δz). If a limited resolution can be sufficient (for instance a resolution not better than 1 nm i.e. q < 1 nm−1), the high order term can be neglected in relation that writes as:
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
