Microscopy reflected light

The examination of specimens in transmission necessarily requires that they be thin. Thus, the techniques of transmission optical microscopy are inappropriate for the examination of bulk specimens, or materials such as metals or conducting polymers which absorb strongly at visible wavelengths. Nevertheless, examination of such samples in reflection may provide useful structural information, through the observation of topographical features. 

In general, images may be formed in reflection in similar ways to those used in transmission. Thus bright-field [8], dark-field, polarised light [20] and 

In DIC, the illumination (white light) is split into two beams that are displaced from one another at the specimen plane by a very small distance. On recombination, small optical-path differences manifest themselves as interference colours. When DIC is used in reflection the surface topography of 

The use of DIC in the study of polymers is particularly well suited to situations such as etched surfaces (see sections 10.3.2.2 and 10.4.2.3), which are macroscopically flat but which nevertheless contain fine topographic details [45]. However, the direct examination of polymer surfaces in reflection is not always entirely straightforward because of the low reflectivity exhibited by many systems. It is therefore often desirable to evaporate or sputter a reflective metallic coating on to the specimen surface prior to examination. While this improves the reflectivity of the sample it also has another less obvious benefit. In low-absorbance systems, the illumination may be reflected back into the objective lens not only from the surface of the specimen, but also from other boundaries within the sample. Particularly at low magnifications, where the depth of field may be considerable in comparison with the size of the surface features, such subsurface effects may give a false impression of the sample topography. 

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Analysts use reflected light microscopy to examine the surface of polymers. By changing the angle of illumination they can accentuate surface texture and other features of interest. Reflected light microscopy is well suited to the examination of opaque and pigmented samples. Polymer scientists make extensive use of reflected light microscopy when examining the fracture surfaces of failed samples. 

One of the key experimental results leading to the elucidation of this overall structural puzzle involved depolarized reflected light microscopy (DRLM) studies on NOBOW freely suspended films in the high-temperature SmCP phase.48 In the freely suspended films it appears that only one phase is observed, which is assumed to be the phase forming the majority domains in the EO cells. The DRLM experiment provides two key results. First, thin films of any layer number have a uniformly tilted optic axis, suggesting all of the layer interfaces are synclinic. Second, films of even-layer number are nonpolar, while films of odd-layer number are polar, with the polar axis oriented normal to the plane of the director tilt (lateral polarization). 

Reflected light Microscopy can be used for examining the texture of solid opaque polymers. Materials which can be prepared as thin films are generally examined by transmitted light. Two common techniques used are (i) polarised-light Microscopy, and (ii) phase contrast Microscopy. 

Sato M, Grasser W. Effects of bisphosphonates on isolated rat osteoclasts as examined by reflected light-microscopy. J Bone Miner Res 1990 5 31-40. 

Work concentrated on gangue quartz in main gold-bearing sulfides veins, and in late stage intrusion-related ( ) base-metal veins. Polished sections were first investigated by transmitted and reflected light microscopy to find suitable samples... 

Reflected light microscopy can be used either on thin sections or thicker polished sections. Reflected light is used primarily for identifying opaque minerals such as metals, sulfides, and some oxides. Each of these minerals has a unique appearance in reflected light. 

In addition, optical microscopy (e.g. reflected light microscopy) and scanning electron microscopy have been used extensively for direct observation of... 

Small polished sections of the reaction products were prepared for reflecting-light microscopy by using Caulk Kadon or Technovit as a mounting medium. Identification of the phases either was undertaken in air or was aided by using oil immersion. In polished sections, depending on the optical properties of the phases examined, identification is often possible when as little as 0.01% of a phase is present. 

Figure 15 is a schematic of the experimental setup for reflected-light microscopy. By use of reflected light, the sample can simply be put in a small... 

Abramowitz, M., Basics and Beyond Series Reflected Light Microscopy An Overview, Vol. 3, Olympus America, Inc., Lake Success, New York, 1990. 

FIGURE 10 Cross section of partially burned particles from the Cretaceous-Tertiary boundary layer, as seen by reflected light microscopy (Kruge et al., 1994). Particles show typical plant xylem cell structures. 

According to Insley (1936), polished section examination of Portland cement clinker was reported by Stern (1908) and by Wetzel (1913) but, largely due to poor technique, the metallographic method was abandoned until Tavasci s very detailed paper in 1934 in which reflected-light microscopy was combined with that from transmitted light. 

Cariou, B. Ranc, R. and Sorrentino, F., "Industrial Application of Quantitative Study of Portland Cement Clinker Through Reflected Light Microscopy," Proceedings of the 10th International Conference on Cement Microscopy, International Cement Microscopy Association,SanAntonio,Texas, 1988, pp. 277-284. 

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