The remote SWIR hyperspectral imaging system operating over the spectral range 1000-2500nm with a spectral resolution of 5.5nm consists of a spectrograph, a MCT camera and a telescope. It collects spectra for one spatial line at a time in a push broom fashion using an automated pan/tilt stage. 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 convenient imaging of any areas of a monument/ object from one position on the ground without moving the instrument. It is used for remote hyperspectral imaging of targeted areas at inaccessible height at high spectral and high spatial resolution. The system has an operational range of up to tens of metres.
Potential Results
Remote SWIR reflectance hyperspectral imaging extends the remote VIS/NIR (400-1000 nm) reflectance hyperspectral imaging spectral range to 2500nm covering the SWIR range of 1000-2500nm. It can complement material identification (both original and degraded materials) using VIS/NIR reflectance spectral imaging, remote Raman spectroscopy and if appropriate remote LIBS spectroscopy. The images can also reveal faded drawings, writings and preparatory sketches, as well as areas of degradation and past intervention. The SWIR range by virtue of the longer wavelength can penetrate more easily through materials that is opaque to VIS/NIR light giving better images of preparatory sketches. It can identify or distinguish different organic and synthetic materials as well as providing more definitive identification for some inorganic materials. It is particularly useful for conservation surveys, e.g. providing a hydration map or salt distribution map. The main advantage of remote reflectance hyperspectral imaging is the ability to access large monuments or objects at inaccessible height from the ground level without the need for scaffolds, making it particularly suitable to architectural and archaeological sites.