Airy diskand resolution

The diffraction effect of the objective aperture is important for HRTEM imaging. The radius of the Airy disk produced by the objective aperture is given by,          rAiry ~ 1.2λf/D ---------------- [3743b] where,          f -- The focal length of the lens;          D -- The aperture diameter.

The magnifying glass consists of a piece of convex[1]-shaped glass or plastic. It has to be held at the right distance between the eye and the object for the object to be in focus. The magnifying glass usually comes with a handle. A telescope is a more advanced kind of magnifying glass and consists of at least two glass lenses.

Airy Disktelescope

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Radius ofAiry diskformula

A magnifying glass is a lens through which can be used to make things appear bigger, so you can see them better. It is used in many applications and manual operations, e.g., for examining postage stamps in philately.

This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.

Airy diskcalculator

where,           Î± -- The convergence semi-angle (also called maximum diffraction angle);           Î» -- The wavelength of the incident electron beam.

In conventional TEM system, the existence of spherical aberration requires the utility of very small apertures to maximize the spatial resolution, while the resolution will also be limited by diffraction if the apertures are too small.

[1] Methods in Cell Biology, Vol. 81, DOI: 10.1016/S0091-679X(06)81002-2, David E. Wolf, The Optics of Microscope Image Formation, (2007).

Airy diskformula

For an ideal objective lens, the incident electron probe simply forms an Airy disk in the back focal plane of the lens. This disk is the Fourier transform of the uniformly illuminated condenser aperture.

Based on the Rayleigh criteria, the ability (spatial resolution) of the microscope to resolve two spots as two essentially relates to how sharply the Airy disks are defined. As the disks get closer, the intensity dip between the two spots becomes smaller. For instance, the two spots can be resolved in Figure 3743 (a) and (b), while they cannot be resolved in Figure 3743 (c).

A pair of binoculars is like a telescope for each eye. Spectacles or eyeglasses also use lenses to correct a person's vision.