Resolving power diffraction-limited

Measurements of surface disorder require a high resolving power (the ability to distinguish two close-lying points in the diffraction pattern). Quantitative measurements of surface disorder are limited in the following manner, the worse the resolving power, the smaller the maximum scale of surface disorder that can be detected. For example, if the maximum resolvable distance of the diffractometer is 100 A, then a surface that has steps spaced more than 100 A apart will look perfect to the instrument. The theoretical analysis of disorder is much simpler than that for atomic positions. 

If the sht is very narrow, comparable to the diffraction limit of the telescope, X A/Dt, the resolving power is... 

As we shall see, electron diffraction from powder samples mainly found its (up to now limited) application in the refinement step and no unknown structures has been determined from scratch relying solely on electron diffraction from powder samples. The two main reasons for that are the collapse of the three dimensional information into one dimension and the poor resolving power of electron diffraction (in terms of AQ/Q, the peak width). 

Scanning probe microscopies (SPM) such as STM and AFM are powerful tools for analyzing solid surfaces. A combination of these microscopic methods and the scattering techniques could give us a new way of determining the fine structures of microcapsule surfaces. Recently, another SPM, scanning near field microscopy, has been developed [57]. The extreme limit of the resolving power of the optical microscope based on the Abbe diffraction theorem can be raised to... 

Instead of the theoretical limit (4.9) given by the diffraction through the aperture a, a smaller practically attainable resolving power is obtained from (4.12), which takes into account a finite minimum entrance slit width b in imposed by intensity considerations and which yields ... 

The theoretical spectral resolving power is the product of the diffraction order m with the total number N of illuminated grooves. If the finite slit width b[ and the diffraction at limiting aperatures are taken into account, the practically achievable resolving power according to (4.13) is about 2—3 times lower. 

The resolution, r, of any conventional, far-field optical process in which an aperture, or lens, is used to focus light is limited by diffraction effects. When light passes through an aperture, it is diffracted. For a circular aperture, an Airy disk pattern results, in which a central bright maximum is surrounded by a series of concentric minima and maxima. The resolving power of a conventional optical system is the minimum distance at which the two central maxima may... 

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