Panoramic lens an historical perspective: from sky lens to consumer wide angle freeform optics

CBED Shadow Images and Cs:Aberration Measurement

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100055813 ◽

1982 ◽

Vol 40 ◽

pp. 696-697

Author(s):

R. W. Carpenter ◽

I.Y.T. Chan ◽

J. M. Cowley

Keyword(s):

Focal Point ◽

Spherical Aberration ◽

Optic Axis ◽

Wide Angle ◽

Caustic Surface ◽

Convergent Beam

Wide-angle convergent beam shadow images(CBSI) exhibit several characteristic distortions resulting from spherical aberration. The most prominent is a circle of infinite magnification resulting from rays having equal values of a forming a cross-over on the optic axis at some distance before reaching the paraxial focal point. This distortion is called the tangential circle of infinite magnification; it can be used to align and stigmate a STEM and to determine Cs for the probe forming lens. A second distortion, the radial circle of infinite magnification, results from a cross-over on the lens caustic surface of rays with differing values of ∝a, also before the paraxial focal point of the lens.

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Reconstruction of Chitin-Protein Complexes Using Correlation Averaging Methods: Ovipositor of the Ichneumon Fly Megarhyssa

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s1431927600000143 ◽

1980 ◽

Vol 38 ◽

pp. 38-39

Author(s):

L. T. Germinario ◽

J. Blackwell ◽

J. Frank

Keyword(s):

Protein Complexes ◽

Hexagonal Lattice ◽

Uranyl Acetate ◽

Optical Diffraction ◽

Insect Cuticle ◽

High Dose ◽

Wide Angle ◽

X Ray ◽

Averaging Methods ◽

Digital Correlation

This report describes the use of digital correlation and averaging methods 1,2 for the reconstruction of high dose electron micrographs of the chitin-protein complex from Megarhyssa ovipositor. Electron microscopy of uranyl acetate stained insect cuticle has demonstrated a hexagonal array of unstained chitin monofibrils, 2.4−3.0 nm in diameter, in a stained protein matrix3,4. Optical diffraction Indicated a hexagonal lattice with a = 5.1-8.3 nm3 A particularly well ordered complex is found in the ovipositor of the ichneumon fly Megarhyssa: the small angle x-ray data gives a = 7.25 nm, and the wide angle pattern shows that the protein consists of subunits arranged in a 61 helix, with an axial repeat of 3.06 nm5.

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