Recent developments in Laue lens manufacturing and their impact on imaging performance

Abstract

We report on recent progress in the development of Laue lenses for applications in hard X/soft gamma-ray astronomy. Here, we focus on the realization of a sector of such a lens made of 11 bent germanium crystals and describe the technological challenges involved in their positioning and alignment with adhesive-based bonding techniques. The accurate alignment and the uniformity of the curvature of the crystals are critical for achieving optimal X-ray focusing capabilities. We assessed how the errors of misalignment with respect to the main orientation angles of the crystals affect the point spread function (PSF) of the image diffracted by a single sector. We corroborated these results with simulations carried out with our physical model of the lens, based on a Monte Carlo ray-tracing technique, adopting the geometrical configuration of the Laue sector, the observed assembly accuracy, and the measured curvatures of the crystals. An extrapolation of the performances achieved on a single sector to an entire Laue lens based on this model shows that a PSF with a halfpower-diameter of 4.8 arcmin can be achieved with current technology. This has the potential to lead to a significant improvement in the sensitivity of spectroscopic and polarimetric observations in the 50 to 600 keV band.