Laser crystallization microstructure

In another approach, two cascaded microstructure-collapses on a photonic crystal fiber are intentionally introduced by C02 laser or electric arc heating31. In this way, the mismatch of core size along the fiber causes light coupling between the core and cladding modes. 

The structure (e.g., number, size, distribution) of fat crystals is difficult to analyze by common microscopy techniques (i.e., electron, polarized light), due to their dense and interconnected microstructure. Images of the internal structures of lipid-based foods can only be obtained by special manipulation of the sample. However, formation of thin sections (polarized light microscopy) or fractured planes (electron microscopy) still typically does not provide adequate resolution of the crystalline phase. Confocal laserscanning microscopy (CLSM), which is based on the detection of fluorescence produced by a dye system when a sample is illuminated with a krypton/argon mixed-gas laser, overcomes these problems. Bulk specimens can be used with CLSM to obtain high-resolution images of lipid crystalline structure in intricate detail. 

To obtain the fractal dimension of a network of particles, acquiring images of the microstructure is necessary. Many forms of microscopy can be used, including brightfield microscopy, confocal laser scanning microscopy, scanning electron microscopy, and in the case of fat crystal networks, polarized light microscopy. 

Figure 1.11. TEM images of the calcite single crystal shocked in a laser irradiation experiment with an initial pressure of 225 GPa. (a) Dark-field TEM image of a 60-pm-deep zone in the specimen, containing numerous dislocation loops. This microstructure indicates incipient decomposition, (b) Dark-field TEM image of tangled, curved dislocations occurring in a depth of 90 pm below the initial specimen surface, (c) Bright-field TEM image of a multiply twinned zone in a depth of-280 pm.

For characterizing the microstructure we use a confocal laser scanning microscope (CLSM). By CLSM we can specify a 3-D configuration under atmospheric condition. Smectite minerals are extremely fine and poorly crystallized, so it is difficult to determine the properties by experiment. We inquire into the physicochemical properties by a molecular dynamics (MD) simulation method. Then, we develop a multiscale homogenization analysis (HA) method to extend the microscopic characteristics to the macroscopic behavior. We show numerical examples of a coupled water-flow and diffusion problem. 

Choudhury D, Rodenas A, Paterson L, Diaz F, Jaque D, Kar AK (2013) Three-dimensional microstructuring of yttrium aluminum garnet crystals for laser active optofluidic applications. Appl Phys Lett 103 041101... 

Fini JM (2004) Microstructure fibres for optical sensing in gases and liquids. Meas Sd Technol 15 1120-1128 Frazao O, Santos JL, Araujo EM, Ferreira LA (2008) Optical sensing with photonic crystal fibers. Laser Photon Rev 2(6) 449- 59... 

Gaumann, M. Bezengon, C. Canalis, P. et al. (2001) Single-Crystal Laser Deposition of Superalloys Processing-Microstructure Maps. Acta Mater., Vol. 49, pp.1051-1062, ISSN 1359-6454... 

Changes in the film microstructure (e.g. texture and grain-size distribution) of the laser-treated Pt thin films were analyzed using Electron Backscatter Diffraction (EBSD). The determination of the orientation of the crystal ensemble and the grain-size distribution has been performed on the cross-like pattern showed in Fig. 9(c). 

Niino, H., Kawabata, Y, and Yabe, A. (1989) Application of excimer laser polymer ablation to alignment of liquid crystals periodic microstructure on polyefhersulfone. Jpn. J. Appl. Phys.,... 

A focused laser may be used for drawing or for drilling microstructures into semiconductor surfaces, in these cases, the laser beam is focused into a spot onto the crystal surface. Specific patterns may be generated by computer-controlled scanning techniques. 

---