Bright-held contrast

Detection of the specimen image depends on the relative intensity differences, and therefore on the amplitudes, of the particle and surround (P and S) waves. If the amplitudes of the particle and surround waves are significantly different in the intermediate image plane, then the specimen acquires a considerable amount of contrast and is easily visualized in the microscope eyepieces. Otherwise, the specimen remains transparent and appears as in an ordinary bright-held microscope. 

Fig. 52 Sheared TE-5070 particles sintered at (a) 320 °C for 5 min, and slow-cooled (b) 350 °C for 30 min, and water-quenched and (c) lamellae in bright-held diffraction contrast from a 350 °C/30min, air-quenched sample. The inset ED pattern in c is from the overexposed selected area.

Figure 7.27. Energy-filtered TEM showing silica nanoparticles embedded within an organic coating. The conventional bright-held TEM image Geft) shows little/no contrast relative to the EF-TEM image (right).[50]...

Figure 1.25 Comet tailing generated by polishing on specimen surface (a) bright-held image and (b) Nomarski contrast image. (Reproduced with permission of Struers A/S.)...

Figure 3.19 Bright-held images of aluminum alloy. The contrast difference between (a) and (b) is generated by tilting the specimen. Individual grains are marked with numbers. (Reproduced with permission from M. von Heimandahl, Electron Microscopy of Materials, Academic Press, New York. 1980 Elsevier B. V.)...

Although many studies on DNA and DNA-protein interaction have utilized metal shadowing to produce bright-held image contrast, dark-held TEM (annular or spectroscopic) of unstained or uranyl acetate-stained and metal-shadowed nucleic acid-protein complexes also provides useful resolution. In Figure 5, a short length of DNA (2356 base pairs), with attached progesterone receptor, is revealed by dark-held TEM. The RecA protein has the ability to... 

A) Bright-Held diffraction contrast mode B) Dark-field diffraction contrast mode C) High-resolution imaging mode a) Specimen b) Lens c) Aperture d) Screen... 

GUVs can be observed with bright-held microscopy, although they are difficult to see because the single bilayer is only about 6 nm thick. Visualization can be greatly enhanced by the use of either phase contrast or DIG (differential interference contrast) microscopy or fluorescence microscopy if a fluorescent molecule probe can be incorporated into the lipid bilayer. 

Fig. 17. Group of metadislocations in 28-Al-Pd-Mn. (a) At lower magnification in two-beam Bragg contrast using the (006) reflection for imaging close to the (120) axis and (b) close to the (010) zone axis, (c) Imaged under bright-held Laue conditions at the (010) zone axis, (d) Boxed area in (c) at higher magnihcation. Scale bars. 100 nm (a, b, c) and 10 nm (d).

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