Reflectance spectral imaging is an efficient way of collecting millions of reflectance spectra over an area in one image cube (2D spatial and wavelength in the 3rd dimension). Remote VIS/NIR reflectance hyperspectral imaging can operate at large distances (tens of metres) at submm spatial resolution and high spectral resolution from one position on the ground regardless of the height of the monument/object. The main advantage of remote reflectance hyperspectral imaging compared with the remote spectral imaging system for large areas survey (PRISMS) is the high spectral resolution which allows the firm identification of a handful of pigments and dyes with sharp spectral features (e.g. cobalt pigments, anthraquinone dyes) in addition to those identifiable by the moderate spectral resolution spectral imaging system, PRISMS. It can give true colour images and images from any of the spectral channels and more importantly separating areas of different material composition. It can give material identification (both original and degraded material) to be confirmed with complementary techniques such as remote Raman/LIF spectroscopy and if appropriate remote LIBS. The images can also reveal faded drawings, writings and preparatory sketches, as well as areas of degradation and past intervention.
architecture, art, decorative arts, mosaics, painting, sculpture, textile
ceramics, stone, metal and metallurgical By-Products, pigments, dyes
wood, paper, textiles, dyes, organic pigments
The remote VIS/NIR hyperspectral imaging system operating over the spectral range 400-1000 nm with a spectral resolution of 2.8 nm consists of a spectrograph, a CMOS camera and a telescope. It collects spectra for one spatial line at a time in a pushbroom fashion using an automated pan/tilt stage. A Tungsten light with long range...