Multispectral imaging - Ultraviolet reflected photography (UVr)
Analytical technique description:
The technique belonging to the multispectral photographic techniques, called imaging. It is a non-invasive and portable method of analysis for objects of art. It could be used for characterization of pictorial material. As visible photography, ultraviolet radiation is sent on the surface of the object which can absorb or reflect the radiation, according to material and substances on it.
The images are acquired by means of a digital camera. The object should be irradiate homogenously and for this purpose a set of two flashes are used. To provide only UV radiation filters are insert ahead of the two flashes.
The images obtained are elaborated by means of computer graphic program in a black and white photo.
Applications:
Pigments on every surface such as fresco, canvas, marble and wood.
Basics:
The ultraviolet radiation can be reflected or absorbed by a surface. The different behaviour is acquired by the camera sensor with a filter ahead of the lens, the filter is used to allow only the ultraviolet radiation reflected from the surface arrive on the detector.
Lights should be homogeneous on surface to avoid overexposure and reflection.
Instrumental details:
Canon EOS 400D, Flash Quantum mod. T5D, filtri Schneider Optics B+W 403 UV passband (Florence Unit).
ICVBC - AREA DI RICERCA CNR DI FIRENZE
Via Madonna del Piano, 10 - 50019 Sesto Fiorentino (FI)
Tel. 055 5225484 - Fax 055 5225483
Institute for the Conservation and Valorization of Cultural Heritage