Optical Bragg microscopy

An X-ray beam, of a finite width, samples a small volume of the polymer structure. The diffraction pattern gives no information about the location of crystals within that volume, but it gives information about the range of crystal orientations in the volume this can be used with optical microscopy to build up a picture of the microstructure. The crystal lattice model, used to interpret diffraction patterns, contains many sets of parallel planes. Polymer crystals often have lower lattice symmetry than metals, so the relationship between the interplanar spacing d and the Miller indices hkl) of the plane are complex (Kelly and Groves, 1970). The Bragg condition... 

X- radiation is very energetic and has been very difficult to manipulate. It can be focused either coherently by Fresnel zone plates and Bragg Fresnel lenses, or incoherently by bent crystal optics and coated fiber optics (generally speaking by highly reflective materials, e.g. super mirrors etc.). However, for many applications, such as X-ray microscopy and spectroscopy, the spot size at the exit of the aperture is too large and the beam stmcture is difficult to control. Moreover, in order to use X-ray in non-invasive medical treatments there is a need for an X-ray waveguide. 

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