Optical Systems Lens

Focus of the light could be done by optical system lens, Fresnel lens, mirror, etc. Converging lenses allow light concentration at the focal point. A Fresnel lens is a series of concentric rings having the shape of a prism section. It is a planoconvex lens, which allows weight saving compared to traditional lenses. Fig. 21.7 compares profiles of both a Fresnel and a conventional convex lens, with equivalent lens-focus distance. The Fresnel lens seems to have been carved from the mass of the conventional lens. 

Entropy and Information Optics, FrancisT. S. Yu Computational Methods for Electromagnetic and Optical Systems, John M. Jarem and Partha P. Banerjee Laser Beam Shaping, Fred M. Dickey and Scott C. Holswade Rare-Earth-Doped Fiber Lasers and Amplifiers Second Edition, Revised and Expanded, edited by Michel J. F. Digonnet Lens Design Third Edition, Revised and Expanded, Milton Laikin Handbook of Optical Engineering, edited by Daniel Malacara and Brian J. Thompson... 

Fig. 2. Lens system used in transmission-type electron microscope. (left I optical convex lens t, Right) electromagnetic lens...

Resolution of any optical system (necessary condition for resolution of an object with the size AB is that the lens of observation at least crosses one bright and one dark hyperboloid) identical to the results of 1.14 and 3.6... 

The quantities in the square brackets are just the ones known from equ. (4.19) with equ. (4.16). Due to the fixed value of pass it can be seen that for the evaluation of relative intensities the dispersion correction can be omitted. However, the transmission factor Tret(Ekin, pass) which describes the change of transmission caused by the retardation becomes very important in this case, see Fig. 4.16. It has to be determined experimentally, and in ideal cases it can be estimated on the basis of Liouville s theorem for optical systems (see Section 10.3.2). In the example shown in Fig. 4.16 the essential action of the retardation field is to change the brightness B in one dimension. (One has a one-dimensional problem because the lens produces focusing of the line source in one dimension only (for details see [GSa75]).) Following equ. (10.47) one gets (subscripts ( and r denote quantities before and after retardation)... 

The same fixed optical system can be used for the spectral and topographic option, to provide the required dispersion on the OMA channels. The demagnification of 1/15 mentioned in a preceding section is obtained by a 381 lens (Fig. IB, S, 1C and IE, m) at its focal distance from the slit together with a Dallmeyer Ultrac camera lens, F/0.98 of focal length 25 mm (Fig. 1C, IE, p) in the beam of light diffracted from the grating or reflected from the mirror, 1/15. 

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