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We have studied with the sphere-in-contact model the structure of rhombohedral graphite and found that there are molecular channels 22.7 degrees with respect to the material symmetry axis. We show via theoretical simulations with the Laue equation, Kramers equation and Duane-Hunt law that X-ray radiation (λ < 1.34 Å) that is traveling along these molecular channels would have a larger mean-free-path. This suggests that stacks of rhombohedral graphite can become effective filters for X-ray sources, such as the ones used in Laue photography and other X-ray techniques that use Bremsstrahlung.

Experimental studies of X-ray diffraction from reflecting atomic planes (111) of X-cut quartz single crystal in Laue geometry influenced by the temperature gradient were carried out. It is shown that by using the temperature gradient it is possible to reflect a hard X- ray beam with photon energy near the 100 keV with high efficiency. It has been experimentally proved that the intensity of the reflected beam can be increased by more than order depending on the value of the temperature gradient.

A series of quasi-mosaic curved crystals has been fabricated for the Laue project to build up a prototype of a Laue lens. Curvature has been imparted to the samples thanks to the grooving method, which makes it possible to realize self-standing curved plates. Samples are 10 × 30 × 2 mm 3 Ge crystals characterized by two curvatures of different crystallographic planes. The primary curvature allows the focalization of the diffracted X-rays on a focal spot smaller than the crystal dimension. The secondary curvature, i.e. quasi-mosaic curvature, amplifies the diffraction efficiency by more than one order of magnitude with respect to an equivalent crystal without quasi-mosaic curvature.

Starting from the discovery of Roentgen’s X-ray (Rontgen 1895), I here reconstruct the various attempts carried out to find X-ray diffraction using very thin wedge-shaped slits. These experiments allowed A. Sommerfeld to achieve, at the beginning of 1912, a qualitative estimate of the wavelength of X-rays around 4 × 10−9 cm. This value was at the base, together with the adoption of the space-lattice model for the crystal, of Laue idea of using a crystal as a diffraction grating for X-ray. Then we will discuss the feasibility of the Laue project, as well as the realization of the experiment, and the first results of W. Friedrich and P. Knipping, with the theoretical interpretation given to them by Laue. Laue’s discovery of X-ray diffraction was immediately taken up by William Henry Bragg and re-interpreted by his son William Lawrence in terms of X-ray reflection by the planes of the crystal, thus becoming, in a few months, a formidable tool for the study of crystal structures, as well as for the precise determination of the wavelengths of X-rays (to Bragg father we owe the construction of the first X-ray ionization spectrometer). Particular attention will be given to the works of C. G. Barkla on X-ray absorption, which resulted in the discovery in 1906 of the Roentgen characteristic radiation of the elements. These works strengthened the hypothesis of the wave nature of X-rays, at the expense of the “corpuscular hypothesis” (supported notably by J. Stark and by W.H. Bragg), and represented a solid reference point for the project of Laue.

Quasi-mosaicity is an effect of secondary bending within a crystal driven by crystalline anisotropy. This effect can be used to fabricate a series of curved crystals for the realization of a Laue lens. It is highlighted that crystals bent by the quasi-mosaic effect allow very high resolution focusing with respect to mosaic crystals. Under the same conditions for energy passband, crystal size and flux of incident photons, a Laue lens based on quasi-mosaic crystals would increase the signal-to-noise ratio by about an order of magnitude compared to the same lens with mosaic crystals. Moreover, no mosaic defocusing occurs for quasi-mosaic crystals.

Quasi-mosaicity is an effect of secondary bending within a crystal driven by crystalline anisotropy. This effect can be used to fabricate a series of curved crystals for the realization of a Laue lens. We highlight that crystals bent by quasi-mosaic effect envisage very high resolution focusing with respect to mosaic crystals. Under same conditions for energy passband and flux of incident photons, a Laue lens based on quasi-mosaic crystals would increase the signal-to-noise ratio by more than one order of magnitude as for the same lens with mosaic crystals. A proposal for the realization of a self-standing quasi-mosaic crystal is given. Here permanent bending of a crystal is achieved as a result of superficial indentations.