The PRISMS system is for rapid survey of large surfaces and those at inaccessible height. It consists of a CCD camera, a filter wheel with 10 interference filters of 40nm bandwidth and central wavelength at 400nm to 850nm at 50nm interval. Either a telescope or a lens is used depending on the required spatial resolution. The highest spatial resolution is 80 micro-radians, or 80 microns at a distance of 10m. A Tungsten light with long range projection capability is used for indoor imaging or imaging at night. For outdoor imaging, daylight is sufficient. The system is placed on a computer controlled motorised pan/tilt stage that allows for automatic imaging of large areas of a monument or even an entire monument, e.g. an entire wall painting. The system has an operational range up to tens of metres. The PRISMS system is mainly for rapid survey of large areas remotely at distances up to tens of metres at submm spatial resolution and moderate spectral resolution.
The main advantage of reflectance spectral imaging with PRISMS is rapid survey of large surfaces at high spatial resolution and moderate spectral resolution in the VIS/NIR (400-850nm) from one position on the ground up to a distance of tens of metres. It can give a mosaic of RGB and any spectral band images needed and more importantly separating areas of different material composition. It can give initial material identification to be confirmed with complementary techniques such as remote Raman spectroscopy and if appropriate remote LIBS spectroscopy. It is most suited to the imaging of large paintings especially wall paintings, architectural and archaeological sites.