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Applicability of thin film phase plates in biological electron microscopy

View Article: PubMed Central - PubMed

ABSTRACT

Presented is an evaluation of phase contrast techniques in transmission electron microscopy. The traditional defocus phase contrast is compared to two recently developed phase plate techniques. One is the Zernike phase contrast transmission electron microscope, the other is the Hilbert differential contrast thransmission electron microscope. The imaging characteristics of each technique are discussed. Phase plate techniques provide improved contrast for ice-embedded biological samples which are a challenge for the conventional defocus phase contrast. The flat spectral response of the Zernike and Hilbert modes extends towards the low frequencies which are severely suppressed in the conventional defocus mode. Target applications for each of the phase contrast techniques are discussed based on the specifics of image formation and spectral transfer.

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Fringes around strong edges in the image due to the finite size of the phase plate hole. (a) graphite flakes on holey carbon. Image taken with a 1 μm hole Zernike phase plate, Fourier transform shown in Fig. 3a, defocus 11.3 μm. (b) ice-embedded T4-phage virus (Hirokawa, H., Danev, R., Arisaka, F. and Nagayama, K., unpublished data). Image taken with a 0.3 μm hole Zernike phase plate, defocus 350 nm.
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f4-2_35: Fringes around strong edges in the image due to the finite size of the phase plate hole. (a) graphite flakes on holey carbon. Image taken with a 1 μm hole Zernike phase plate, Fourier transform shown in Fig. 3a, defocus 11.3 μm. (b) ice-embedded T4-phage virus (Hirokawa, H., Danev, R., Arisaka, F. and Nagayama, K., unpublished data). Image taken with a 0.3 μm hole Zernike phase plate, defocus 350 nm.

Mentions: Figs. 4a, b demonstrate the effect of the finite size of the phase plate hole on the appearance of the image. The Fourier transform of Fig. 4a is presented in Fig. 3a. There is a sharp jump in the Fourier space at the edge of the phase plate indicated by a green arrow in Fig. 3b. It is well known that sharp jumps in the Fourier space produce “ringing” in the real space. In Fig. 4a fringes are clearly observed around the edges of the holey carbon film and the graphite flakes. The ringing due to phase plate hole cutoff is most severe around high contrast edges in the image. Fig. 4b shows image of ice embedded T4 phage viruses. A bright fringe is noticeable around the tail and head of the virus. However due to the low contrast of ice embedded specimens such fringes are not a significant problem.


Applicability of thin film phase plates in biological electron microscopy
Fringes around strong edges in the image due to the finite size of the phase plate hole. (a) graphite flakes on holey carbon. Image taken with a 1 μm hole Zernike phase plate, Fourier transform shown in Fig. 3a, defocus 11.3 μm. (b) ice-embedded T4-phage virus (Hirokawa, H., Danev, R., Arisaka, F. and Nagayama, K., unpublished data). Image taken with a 0.3 μm hole Zernike phase plate, defocus 350 nm.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC5036645&req=5

f4-2_35: Fringes around strong edges in the image due to the finite size of the phase plate hole. (a) graphite flakes on holey carbon. Image taken with a 1 μm hole Zernike phase plate, Fourier transform shown in Fig. 3a, defocus 11.3 μm. (b) ice-embedded T4-phage virus (Hirokawa, H., Danev, R., Arisaka, F. and Nagayama, K., unpublished data). Image taken with a 0.3 μm hole Zernike phase plate, defocus 350 nm.
Mentions: Figs. 4a, b demonstrate the effect of the finite size of the phase plate hole on the appearance of the image. The Fourier transform of Fig. 4a is presented in Fig. 3a. There is a sharp jump in the Fourier space at the edge of the phase plate indicated by a green arrow in Fig. 3b. It is well known that sharp jumps in the Fourier space produce “ringing” in the real space. In Fig. 4a fringes are clearly observed around the edges of the holey carbon film and the graphite flakes. The ringing due to phase plate hole cutoff is most severe around high contrast edges in the image. Fig. 4b shows image of ice embedded T4 phage viruses. A bright fringe is noticeable around the tail and head of the virus. However due to the low contrast of ice embedded specimens such fringes are not a significant problem.

View Article: PubMed Central - PubMed

ABSTRACT

Presented is an evaluation of phase contrast techniques in transmission electron microscopy. The traditional defocus phase contrast is compared to two recently developed phase plate techniques. One is the Zernike phase contrast transmission electron microscope, the other is the Hilbert differential contrast thransmission electron microscope. The imaging characteristics of each technique are discussed. Phase plate techniques provide improved contrast for ice-embedded biological samples which are a challenge for the conventional defocus phase contrast. The flat spectral response of the Zernike and Hilbert modes extends towards the low frequencies which are severely suppressed in the conventional defocus mode. Target applications for each of the phase contrast techniques are discussed based on the specifics of image formation and spectral transfer.

No MeSH data available.


Related in: MedlinePlus