The Magnetic Electron Microscope Objective: Contour Phenomena and the Attainment of High Resolving Power

Hillier, James; Ramberg, E. G.

doi:10.1063/1.1697554

Cited by 133 publications

(11 citation statements)

References 3 publications

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“…Boersch (1947) first recognized the existence of electron optical phase contrast in the discussion of single atom imaging. Hillier & Ramberg (1947) incorporated a phase shift by the specimen film into their discussions of electron Fresnel diffraction at the edge of a transparent film. Scherzer (1949) introduced phase shifts due to objective lens spherical aberration and defocus into a theory of electron microscope resolution.…”

Section: Introductionmentioning

confidence: 99%

Enhanced contrast in electron microscopy of unstained biological material

Johnson

Parsons

1973

Journal of Microscopy

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In-focus phase contrast electron microscopy has been investigated for the enhancement of bulk contrast (i.e. the contrast of large regions) of model biological specimens. Carbon film phase plates, of measured thickness, were introduced into the back focal plane ofthe objective lens. Image contrast was determined from Faraday-cage intensity measurements. A contrast enhancement was observed but was measured to be less than that obtained using a very small objective aperture. This was attributed to the smaller proportion of elastic scattering and the limited spatial frequency region over which the phase contrast transfer function was uniform. Electron beam interferometry established the ability of the phase plates to preserve the coherence of the beam traversing them. Carbon granularity, of specific dimensions, was significantly enhanced by the phase plate in accordance with the phase contrast transfer function and this enhanced granularity dominated the images of biological specimens. I N T R O D U C T I O NThe phase contrast technique, invented for light microscopy by Zernike (1942a, b), involved phase shifting the scattered relative to the non-scattered waves from a microscope specimen. Constructive or destructive interference was achieved when the wave components interfered in the image plane and image contrast was enhanced by rendering a specific detail brighter (negative contrast) or darker (positive contrast) than its surroundings. A phase plate in the diffraction plane (back focal plane) of the objective lens accomplished the required phase shift by providing an increased optical path (a phase delay) for one wave component relative to the other.Calculations (Bennet et al., 1946; Franqon, 1950;Barer, 1952) indicated the necessity of a 7r/2 rad phase delay of scattered waves for positive phase contrast in the case of hypothetical objects comparable to typical unstained biological specimens. Experimentally, Zernike (1942a, b) and Bennet et al. (1946, 1951) found a 57/2 rad phase plate to be the best compromise for routine biological light

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Section: Introductionmentioning

confidence: 99%

Enhanced contrast in electron microscopy of unstained biological material

Johnson

Parsons

1973

Journal of Microscopy

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“…EMU 2b electron microscope. This instrument was fitted with a compensated objective pole piece (Hillier & Ramberg, 1947). Electron optical magnification was determined by the use of Dow polystyrene latex of empirical mean diameter 2590 A.…”

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confidence: 99%

Biophysical Studies of the Virus System of Vesicular Stomatitis

Cj¹,

Jb²,

Dillon³

1956

Journal of General Microbiology

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SUMMARY : Biophysical studies of the virus system of vesicular stomatitis passaged in eggs showed that the major part ofthe infectivity was associated with a component of sedimentation coefficient 625 S. A component of sedimentation coefficient 330 S was observed also, and is probably a non-infective product of the disintegration of the 6 2 5 s component. These components contribute about 35 yo of the total complement-fixing activity of the virus system. All infective materials were handled in subdued light (Skinner & Bradish, 1954). Electron micrographs of concentrates of the infective fraction revealed rods, of length 175 mp. and diameter 69 m p , and almost spherical granules of diameter 65 mp. These particles are identified with the 6 2 5 s and 330s sedimentation components. The remaining 65 Yo of the total complement-fixing activity was associated with two discrete components of sedimentation coefficients about 2 0 s and 6 s . The first of these components may contribute up to 0.1 yo of the total infectivity of the virus system. The structure of the virus system is discussed in relation to the data obtained.Ultracentrifugal studies of the virus system of foot-and-mouth disease (Bradish, Brooksby, Dillon & Norambuena, 1952) demonstrated that infectivity and complement-fixing activity were associated with discrete components of sedimentation coefficients 70 S and 8 S, respectively. These values correspond with equivalent particle diameters of about 20 and 7 mp., respectively. The extension of studies of this type to the virus system of vesicular stomatitis presents advantages because of the greater mass of the infective particle which, on the basis of earlier ultrafiltration and ultracentrifugation data (Galloway & Elford, 1933; Elford & Galloway, 1937) has an equivalent diameter of about 75 mp. This larger particle facilitates the use of certain biophysical methods which were not employed in the previous study (Bradish et al. 1952). Of particular value is the comparison which may be made between the data obtained by the biological assay of ultracentrifugal fractions and those derived by direct optical-analytical ultracentrifugation and by electron microscopy. The results obtained are presented in this paper. METHODS Handling in subdued lightIt was observed by Skinner & Bradish (1954) that the infectivity of suspensions of many viruses, including those of the virus of vesicular stomatitis, was decreased significantly by exposure to light. Special precautions were taken

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“…If we denote x = xl, the expressions X and Y, necessary for the calculations of intensity and phase distribution (cf. For the intensity distribution for several other ez-~2 at the same ratio l"z/'r 2 see [9]. (b) 7t = r2, ex -E2 = zr/4, *r/2, 31r/4, 7r.…”

Section: Two Partially Transparent Half-planes Of Opposite Orientatiomentioning

confidence: 98%

“…whicb is independent of the variables of integration ~m', ~m" Neglecting in (9) all terms of higher than second order in ~m', ~m' and substituting from (9) and (10) into (8) we get:…”

Section: J °- D Go a Rmr~mentioning

confidence: 98%

“…The intensity distribution in diffraction phenomena produced by a partially transparent half-plane was investigated by Hillier and Ramberg [9], and by Kinder and Recknagel [11], in connection with the phenomena observed in overfocused and underfocused patterns in electron and light microscopy. The interesting case ~1 = T~, ~t -E~ = ~r (see figure 7 (b)) was investigated experimentally by Kastler [10] in light optics and by Faget and Fert [4,5,6] in electron optics.…”

Section: Two Partially Transparent Half-planes Of Opposite Orientatiomentioning

confidence: 99%

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Intensity and Phase in Fresnel Diffraction by a Plane Screen Consisting of Parallel Strips

Komrska¹

1967

Optica Acta: International Journal of Optics

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Using the Huygens-Fresnel principle the expressions for the intensity and the phase in Fresnel diffraction phenomena have been derived. The cases of spherical, cylindrical and plane scalar waves incident upon the plane diffraction screen have been investigated. The diffraction screen may consist of any number of parallel strips of different transmissivities and different phase shifts, the width of the individual strips being large compared with the wavelength. As special cases of the general formulae, the intensity and phase distributions in the diffraction patterns for the following forms of the diffraction screen have been calculated: opaque and partially transparent half-plane, slit, strip and double slit. By means of the derived expressions, the validity of Babinet's principle for Fresnel diffraction phenomena of this type has been verified.

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The Magnetic Electron Microscope Objective: Contour Phenomena and the Attainment of High Resolving Power

Cited by 133 publications

References 3 publications

Enhanced contrast in electron microscopy of unstained biological material

Enhanced contrast in electron microscopy of unstained biological material

Biophysical Studies of the Virus System of Vesicular Stomatitis

Intensity and Phase in Fresnel Diffraction by a Plane Screen Consisting of Parallel Strips

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