Brewster fringe

Figure 10.13. Brewster fringes frequently seen in amethyst crystals. L and R indicate left-handed and right-handed structures, respectively.

In amethyst crystals showing Brewster fringes, a pattern such as that shown in Fig. 10.14 is observed in the growth sectors of or on the surface of r faces, and not in... 

Figure 10.14. (a), (b) Reflection photomicrographs of weakly etched surface, and (c) the structure of Brewster fringes on an r face (model by Lu and Sunagawa [17]). Zigzag (Ain (a) and (c)) and closed lamellae (B in (a) and (c)) appear alternately. L=left-handed quartz R = right-handed quartz. 

Large short-prismatic quartz crystals develop toward the center of a void. In many cases, these crystals are amethyst, in which Brazil twins and Brewster fringes are universally observed. 

Lu Taijing and 1. Sunagawa, Structure of Brazil twin boundaries in amethyst showing Brewster fringes, Phys. Chem. Min., 17,1990,207-11... 

The beam was passed through a pulse picker (4). In order to compensate pulse broadening ( chirp ) introduced by the pulse picker and to precompensate that caused by other bulky optics (lenses, polarizers etc.), the beam was passed through a group velocity dispersion compensation line (5), consisting of a pair of Brewster prisms and a mirror [20], The temporal width of the pump and probe pulses was checked with a fringe-resolved... 

To reduce spectral distortions caused by the interference fringes, the back surface of the film can be roughened, or the spectrum can be measured at the Brewster angle. Depending on the mechanical strength of the polymer, the minimum film thickness that can be achieved is usually 0.5-5 p,m. A 10-20- jim film usually produces a good transmission spectrum. 

Several ways to eliminate interference fringes have been proposed. One of the more effective ways is to mount a polarizer in the beam and to mount the sample at Brewster s angle, 9, calculated as... 

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