Light-optical microscope

Figure 7.1. Schematic of the components of (a) transmitted light optical microscope and (b) reflected hght optical microscope.

Typical of all human experience, seeing is believing, so the microscope has attracted much interest for many decades. All these inventions, of course, were basically initiated on the principles laid out by the telescope (as invented by Galileo) and the light-optical microscope (as invented by Hooke). Actually, no other scientific techniques have contributed so much to the scientific development in biology, medicine, and material science as the different microscopy techifiques. 

Many lay cell biologists use confocal imaging to refer to anything from a simple digital recording of a single focal plane to a full three-dimensional data By fluorescence LM, 1 mean use of a compound light (optical) microscope equipped for epifluo-... 

Figure 25. Microstructure (light-optical microscope) of a WC/Co-based hardmetal (WIDIA TTR)...

In 1873, Ernst Abbe established the resolution limit of optical microscopes The minimum distance, d, between two structural elements to be imaged as two objects instead of one is given by d = A/(2 NA), where X is the wavelength of light and NA the numerieal aperture of the objective lens. The physical root for resolution limit is related to optical diffraction and loss of evanescent waves in far-field the evaneseent waves carry high-frequency subwavelength spatial information of an object and decay exponentially with distance from the objeet. With white lights, optical microscope resolution is limited at about 200-250 nm. For about one hundred years, the Abbe criterion was considered the fundamental limit of optical microscope resolution. 

Isotropic materials have properties which are independent of the direction of examination, X-, y- or z-direction. As such, they appear with a purple color in the polarized light optical microscope and this color does not change on rotation of the stage of the microscope. Thus, reflectance and bireflectance are not relevant properties for isotropic carbons. The porous, isotropic carbons are easily identifled and distinguished from anisotropic carbons by this technique. 

Sap of lacquer trees, which appears dark under a polarized light optical microscope, showed a "Maltese cross" pattern with a number of circles of about 10 ym when it was dried into a film as shown in Fig. 9. This indicated the formation of considerable molecular orientation of the plant gum in the film, corresponding in pattern to the water droplets in the oil(urushiol) phase of sap. 

Figure 6.8 Light-optical microscopic image of chamomile inflorescence (a), FT-Raman spectrum obtained from the receptacle (b) Raman mapping showing the distribution of polyacetylenes (c) and carotenoids (d). The relative concentration of polyacetylenes...

Compare a TEM to a tremsmitted light optical microscope being used to take a photomicrograph, and the principles of design are very similar. Illumination of the object is very important, and in both microscopes the resolution and contrast of the image may be degraded if the illumination is not properly adjusted. The source of illumination may be a small, hot tungsten filament in both cases. The electrons or photons emitted from the filament are collected by a condenser lens. To increase efficiency in the TEM, an electrostatic lens electron gun) is used to steer more of the flux into this lens. In the optical microscope, a mirror behind the lamp performs this function. A second condenser lens controls the transfer of this illumination to the specimen plane. In the TEM, these are simply called condenser lens 1 (Ci) and condenser... 

Fig. 12 Polarized light optical microscope observation of VAzPy C12 at its LC phase upon UV irradiation. The right picture was obtained after irradiation with visible light ftw 80 s. Reproduced with permission from Chen et al. [61]. Copyright 2014, Royal Society of Chemistry...

After the wear test, die wear tracks developed on the coatings were detected by prolilometer. Wear of coatings and the counterface balls were examined by using Jeol 5410 Scanning Electron Microscope (SEM) equipped with Electron Diffraction Spectrometer (EDS) and a Zeiss light optical microscope. 

Indentation All indents were made with a Vickers diamond (136°). For loads below ICON a commercial hardness tester (Zwick 3212) was used, whereas for higher loads a specially constructed indenting equipment was utilized. With this equipment the diamond is loaded at a constant loading rate. All indents were made with a loading time of 5 s hold at full load. The crack length was measured with a light optical microscope at 500 X magnification. 

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