Depth resolving power

Fig. 7.12a). In the special case where Z is fixed perpendicular to the surface of the sample the depth resolving power Rdepth = d/Ad is relevant which becomes important for depth profile and thin-film analysis. 

The classical polarizing light microscope as developed 150 years ago is still the most versatile, least expensive analytical instrument in the hands of an experienced microscopist. Its limitations in terms of resolving power, depth of field, and contrast have been reduced in the last decade, in which we have witnessed a revolution in its evolution. Video microscopy has increased contrast electronically, and thereby revealed structures never before seen. With computer enhancement, unheard of resolutions are possible. There are daily developments in the X-ray, holographic, acoustic, confocal laser scanning, and scanning tunneling micro-... 

In order to study interfacial phenomena at a liquid/liquid boundary at a microscopic level, surface-selective or depth-resolved measurements at an interface are absolutely necessary. Among several methods, TIR spectroscopy is a powerful means to obtain an inside look at an interfacial layer in several tens to several hundreds of nanometres. In this study, TIR fluorescence spectroscopy was employed to follow chemical and physical characteristics at liquid/liquid interfaces. Before discussing characteristic features of the structures at liquid/liquid interfaces, the basic theory of TIR of light is reviewed briefly in the following. 

A displacement D/Z of an object plane in the direction of the incident beam on either side of the reference plane, adds a blur oD to the diameter of the probe that thus becomes + oO (Fig. 7.4). On the image enlarged by a factor G, the blur on the image must remain lower than the resolving power of the eye , i.e. the blur on the object must not exceed e/G, hence the following expression for the depth of field ... 

Of course, the optical microscope was not so well suited for paint research because of inherent resolution and depth-of-field limitations. For example, pigment particles are often well below lum in size therefore, the most interesting features of their surfaces are below the resolving power attainable. Optical scientists have continually pushed for greater resolution through... 

The depth of focus or axial resolving power R ) is also important and depends on the characteristics of the objective. 

Two alternative methods of Raman imaging via global illumination and via point illumination in combination with confocal light collection were applied to the study of heterogeneous polymer systems. The spectral and spatial resolving power of the different techniques was estimated experimentally. The influence of the depth resolution on the Raman image of a defined sample structure was demonstrated in a mathematical simulation. Data are given for PE, PS, polyacrylate, and epoxy resins. 23 refs. 

Enhanced Microfluidic Separation by Pressure-Driven Flow, Fig. 5 (a) Effect of the depth of the shallow region in segment D of the CZE device shown in Fig. 1 on its resolving power. The electropherograms presented here were obtained using 1 mM sodium tetraborate solution as the background electrolyte and an... 

Local analysis of solids excludes the use of prior separation or enrichment steps. Hence, the specificity becomes as important as the sensitivity. The LOD essentially determines the minimal sample volume in which an analyte with a given concentration can be traced back. Specificity refers to a combination of information levels (elements, bonds, functional groups, MW, and/or structure), resolving power to overcome interferences, lateral resolution, and information depth. The last two parameters determine the scale on which compositional discontinuities can be observed. 

Numerical aperture n. The numerical aperture of a lens system (objective or condenser) is the sine of one-half the angular aperture times the refractive index of the medium (1.0 for air, 1.515 for Cargille immersion oil, etc.) between objective and specimen. The numerical aperture is a measure of the light gathering capacity of the lens system and determines its resolving power and depth of field. 

The resolving power of the film or of the lens (whichever is lower) determines the depth of focus of the camera, or... 

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