Hard X-ray astronomy is a crucial field for understanding physical processes occurring in several celestial objects, characterized by extreme physical conditions and strong gravity regime, but still poorly explored. Current hard-X ray instrumentation suffers from a poor angular resolution, compared with other wavelengths, and insufficient continuum sensitivity to resolve hard X-ray spectra, especially above few hundreds keV. Laue lenses made with bent crystals represent a viable solution to overcome both limitations, providing good angular resolution ( better than 30 arcsec) combined with excellent sensitivity (orders of magnitude better than that achievable with the current non focusing instrumentation). Supported by the Italian Space Agency, we test a modular method for building Laue lenses. This consists in the realization of portions of Laue lenses that are successively tuned and aligned under the control of a gamma-ray source for focusing the radiation on the common Laue lens focal point. Each module, composed with few tens of crystals, can be realized with an accuracy better than 20 arcsecs with the goal of achieving an overall alignment better than 30 arcsec. In addition, we present a significant improvement in the realization of a large number of bent crystals with the required curvature.
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