Improved specimen reconstruction by Hilbert phase contrast tomography

Barton, Bastian; Joos, Friederike; Schröder, Rasmus R.

doi:10.1016/j.jsb.2008.07.009

Cited by 27 publications

(10 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In a recent study, Zernike phase contrast TEM (ZPC-TEM) demonstrated improved performance for 3D structural investigations of proteins based on the ''single particle" reconstruction method (Danev and Nagayama, 2008). Another recent study (Barton et al, 2008) demonstrated improved visibility of details in reconstructed tomograms of thin sections of resin embedded biological specimens by utilizing a Hilbert type carbon film phase plate.…”

Section: Introductionmentioning

confidence: 99%

Zernike phase contrast cryo-electron tomography

Danev

Kanamaru

Marko

et al. 2010

Journal of Structural Biology

View full text Add to dashboard Cite

Section: Introductionmentioning

confidence: 99%

Zernike phase contrast cryo-electron tomography

Danev

Kanamaru

Marko

et al. 2010

Journal of Structural Biology

View full text Add to dashboard Cite

“…To test whether the phase shift is correctly calculated in our simulations we compared to Barton et al . () according to which 40.4 nm of amorphous carbon (with a potential of 10.7 V) will shift a 200 keV electron wave by 180 degrees. In our own simulation a 40‐nm stack of constant potential of 10.7 V surrounded by vacuum leads to a phase shift of 179 degrees for 200 keV electrons.…”

Section: Simulation Results and Discussionmentioning

confidence: 99%

Limitations of the linear and the projection approximations in three‐dimensional transmission electron microscopy of fully hydrated proteins

Koeck

Karshikoff

2015

Journal of Microscopy

View full text Add to dashboard Cite

We establish expressions for the linear and quadratic terms in the series expansion of the phase and the phase and amplitude object description of imaging thin specimens by transmission electron microscopy. Based on these expressions we simulate the corresponding contributions to images of unstained protein complexes of varying thickness and arrive at an estimate for how much each term contributes to the contrast of the image. From this we can estimate a maximum specimen thickness for which the weak phase and the weak amplitude and phase object approximation (and therefore linear imaging) is still reasonably accurate. When discussing thick specimens it is also necessary to consider limitations due to describing the image as a filtered projection of the specimen, since the different layers of the specimen are not imaged with the same defocus value. We therefore compared simulations based on the projection approximation with the more accurate multislice model of image formation. However, we find that the errors due to nonlinear image contributions are greater than those due to the defocus gradient for the defocus values chosen for the simulations. Finally, we study how the discussed nonlinear image contributions and the defocus gradient affect the quality of three-dimensional reconstructions. We find that three-dimensional reconstructions reach high resolution when at the same time exhibiting localized systematic structural errors.

show abstract

“…Another advantage lies in the reduced amplitude loss and electron scattering in a thin film phase plate that is only half the thickness (Nagayama & Danev, 2008). Since the phase-plate only applies a phase shift of π/4, it can be kept very thin (about 11 nm for a carbon film phase plate and 300 keV electrons (Barton et al, 2008). Clearly, the presented ideas can also be applied in the case of the Volta potential phase plate (Danev et al, 2014) provided a material can be found that produces the correct phase shift for a microscope with a given acceleration potential.…”

Section: Discussionmentioning

confidence: 99%

Improved Zernike‐type phase contrast for transmission electron microscopy

Koeck

2015

Journal of Microscopy

View full text Add to dashboard Cite

Zernike phase contrast has been recognized as a means of recording high-resolution images with high contrast using a transmission electron microscope. This imaging mode can be used to image typical phase objects such as unstained biological molecules or cryosections of biological tissue. According to the original proposal discussed in Danev and Nagayama (2001) and references therein, the Zernike phase plate applies a phase shift of π/2 to all scattered electron beams outside a given scattering angle and an image is recorded at Gaussian focus or slight underfocus (below Scherzer defocus). Alternatively, a phase shift of -π/2 is applied to the central beam using the Boersch phase plate. The resulting image will have an almost perfect contrast transfer function (close to 1) from a given lowest spatial frequency up to a maximum resolution determined by the wave length, the amount of defocus and the spherical aberration of the microscope. In this paper, I present theory and simulations showing that this maximum spatial frequency can be increased considerably without loss of contrast by using a Zernike or Boersch phase plate that leads to a phase shift between scattered and unscattered electrons of only π /4, and recording images at Scherzer defocus. The maximum resolution can be improved even more by imaging at extended Scherzer defocus, though at the cost of contrast loss at lower spatial frequencies.

show abstract

Improved specimen reconstruction by Hilbert phase contrast tomography

Cited by 27 publications

References 28 publications

Zernike phase contrast cryo-electron tomography

Zernike phase contrast cryo-electron tomography

Limitations of the linear and the projection approximations in three‐dimensional transmission electron microscopy of fully hydrated proteins

Improved Zernike‐type phase contrast for transmission electron microscopy

Contact Info

Product

Resources

About