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Lithium fluoride (LiF) crystals and thin films have been successfully investigated as X-ray imaging detectors based on optical reading of visible photoluminescence emitted by stable radiation-induced F2 and F3 + colour centres. In this work, the visible photoluminescence response of optically-transparent LiF film detectors of three different thicknesses, grown by thermal evaporation on Si(100) substrates and irradiated with monochromatic 7 keV X-rays at several doses in the range between 13 and 4.5× 103 Gy, was carefully investigated by fluorescence optical microscopy. For all the film thicknesses, the photoluminescence response linearly depends on the irradiation dose in the investigated dose range. The lowest detected dose, delivered to the thinnest LiF film, only 0.5 μm thick, is estimated 13 Gy. Edge-enhancement imaging experiments, conducted by irradiating LiF film detectors at the same energy placing an Au mesh in front of them at a distance of 15 mm, allowed estimating a spatial resolution of (0.38 ± 0.05) μm, which is comparable to the microscope one. This very high spatial resolution in LiF film radiation detectors based on colour centres photoluminescence is combined with the availability of a wide field of view on large areas.

We report the use of lithium fluoride fluorescent radiation imaging crystal detectors, read by an optical confocal laser microscope, to register the transmitted X-ray beams by polycapillary optics combined with a table-top Xray source. Polycapillary optics can control X-ray beams propagation and allows obtaining quasi-parallel beam (halflens) or focused beams (full-lens). Confocal laser fluorescence microscopy of X-ray irradiated LiF crystal detectors based on the photoluminescence of X-ray induced colour centres enables advanced characterization of these complex optics. Two-dimensional (2D) high spatial resolution images of X-rays transmitted through either a semi-lens or a full-lens were obtained. Moreover, the photoluminescent colour center volumes produced by X-rays in LiF crystals in a single exposure process have been used to provide threedimensional (3D) information about transmitted X-ray beams. The use of LiF crystal plates as X-ray imaging luminescent detectors represent a versatile and promising tool to characterize the operation of polycapillary optics.

Much attention is currently being paid to the materials and processes that allow one to directly write or to imprint waveguiding structures and/or diffractive elements for optical integrated circuits by exposure from a source of photons, electrons or ions. Here a brief overview of the results achieved in our laboratories is presented, concerning the fabrication and characterization of optical guiding structures based on different materials and exposure techniques. These approaches include: electron and ion beam writing of waveguides in (poly)-crystalline lithium fluoride, uv-laser printing of waveguides and gratings in photorefractive glass thin films, and fs-laser writing in tellurite glasses. Properties and perspectives of these approaches are also discussed.