Application of Visible and Infrared Imaging Spectroscopy To The Study of Paintings

Imaging spectroscopy, the collection of hundreds of contiguous narrow-band images, offers an improvement over site-specific fiber optic reflectance measurements by combining both spatial and spectral information. We have focused on developing portable high sensitivity hyperspectral cameras capable to operate at low light levels, which is necessary for the examination of paintings, drawings, illuminated manuscripts. The cameras operate from the visible (380 to 750 nm) and Near-infrared (750 to 2500 nm) and have both high spectral (2.4 to 4 nm) sampling and high spatial sampling (0.2 to 0.1 mm per pixel at the artwork). The cameras utilize transmission-grating spectrometers and state-of-the-art infrared detectors, such as InGaAs and InSb arrays. Use of a whiskbroom-scanning mirror allows for a portable system as it eliminates the need to translate the camera across the painted surface.