A compact spectral camera for VIS-NIR imaging

This paper describes the design of a spectro-photo/radio-metric camera, that can be used in both portable and in-situ applications, whose compactness is made possible by a suitable image spectral scanning scheme based on a Linearly Variable Filter (LVF). Such filter is able to operate continuously from 400 nm to 2500 nm, allowing the hyper-spectral imaging from visible to near infrared. In traditional scanners the whole apparatus is moved along a path as long as the scene, whereas in this instrument the camera body is still and the LVF it is the only moving part. This solution allows a compact design and an easily portable instrument

Laser cleaning of gilded wood: a comparative study of colour variations induced by irradiation at different wavelengths

There is a growing interest by art conservators for laser cleaning of wood artworks, since traditional cleaning with chemical solvents can be a source of decay, due to the prolonged action of chemicals after the restoration. In this experiment we used excimer and Nd:YAGlasers, emitting radiation in the ultraviolet (248 nm), visible (532 nm) and near infrared (1064 nm), to investigate the effect of laser interaction on gilded wood samples at different wavelengths

La falsificazione epigrafica. Questioni di metodo e casi di studio

This paper aims to reconsider the manuscript by Jacopo Valvasone (1499-1570), formerly owned by the Earl of Leicester (now British Library, Additional MS 49369), which Theodor Mommsen borrowed and inspected in 1876, just before the publication of the second part of CIL V. In the letter that he wrote to thank the Vicar and Librarian of Halkham Hall, Mommsen declared that Valvasone joined \u201cthe the long list of forgers\u201d. The analysis of forgeries in Valvasone\u2019s manuscript could show whether Mommsen was right in his opinion

Spatial filtering of visible light in a spectrophotometric camera fo art work imaging

The preservation and reproduction of a still artwork needs the knowledge of its spectral reflectance, obtainable in laboratory by spectrophotometric scanners. This work proposes the design of a miniaturized spectrophotometric camera with spatial filtering of the light for measuring the spectral reflectance factor and the spectral radiance of the objects of a scene

Influence of laser beam quality on modal selection in tapered optical fibers for multipoint optogenetic control of neural activity

Spatial-resolved light delivery in the living mammalian brain is of utmost importance in optogenetics experiments, since it allows for combining cell-type specificity with spatial selective optical control of neural activity. This can be achieved at sub-cellular resolution in first cortical layers with two-photon microscopy, while sub-cortical regions can be accessed by using waveguide-based devices. Tapered and nanostructured optical fibers have been recently proposed as viable devices to dynamically switch light stimuli between different points of deep-brain structures, by exploiting both mode division demultiplexing operated by the fiber taper and excitation of well-defined subsets of guided modes into the fiber [Pisanello et al., Neuron, vol. 82, p.1245 (2014); Pisanello et al., Biomed. Opt. Express, vol. 6, p. 4014 (2015)]. This latter is achieved byselecting the injection angle of a high-quality Gaussian beam, therefore exciting guided modes with defined transversal propagation constants. In this contribution we analyze the effectiveness of this technique as a function of the laser beam profile used to guide light into the fiber, complementing experimental results with ray tracing simulations. Two different commercial laser sources, with sensibly different beam qualities, were used to determine the extent of the injected modal subsets in a 0.22 N.A. optical fiber. This was obtained by measuring the transversal component kt of the wavevector through far-field imaging. We show that even poor quality beams might return satisfactory selection accuracy, provided that care is taken in the design of the coupling strategy. © 2016 IEEE