No description available.

No description available.

No description available.

No description available.

Inaug.-diss.--Rostock.

A study of the hyperbolic electrostatic electron mirror is presented. The focal properties of the mirror are determined both theoretically and experimentally. In the theoretical study the mirror field is formed between a positive hyperbolic potential surface and the negative asymptotic cone of half angle arctan 1:2 [square root of 2]. The focal properties are obtained from the solutions of the equations for the radial and axial motions of the electron in the mirror field. The analysis includes the effect of an axial aperture (for entrance and exit of electrons) in the positive surface. The paraxial values of focal length arid focal distance and their second order spherical aberrations are calculated by expanding the expressions for the focal properties in terms of the incident radial height. The mirror field in the experimental study is formed between a similar negative electrode and a flat apertured positive electrode. The experimental values of the focal properties are determined by a ray tracing method in which the pattern of shadows cast by a grid in the incident and reflected beams is analyzed. Comparison of the experimentally measured and the theoretically calculated focal properties shows satisfactory agreement. The mirror exhibits over-corrected spherical aberration in certain ranges of its operation which suggests its use to improve the resolution limit of electron optical devices.

No description available.

No description available.

Accurate calculations of the axial chromatic aberration coefficients of geometrically symmetric three-cylinder tripotential electrostatic lenses are presented for two different center electrode lengths. This is an extension of the first-order properties and the third-order spherical aberration coefficients published by Harting and Read.

QC 351 A7 no. 71 / Generalized ray tracing is a method of calculating the principal curvatures and directions of the wavefront associated with a ray as it is traced through an optical system. The results of such a ray trace provide important information about the structure of the image and have immediate application to lens design and image analysis. The caustic surface formed by an optical system can be easily determined from the results of a generalized ray trace. An examination of several caustic surfaces formed by different optical systems provides valuable information about the relative quality of the images and indicates some of the advantages of the generalized ray tracing method.