Ultraviolet-induced luminescence (UVL) images record the
emission of light (luminescence) in the visible region (400-700 nm)
from a subject when this is illuminated with UV radiation.
This image is used to investigate the distribution of luminescent
materials, such as organic binders and colorants.”®? Some inorganic
materials also show luminescence properties, such as, for example,
some inorganic pigments including zinc oxide with impurities.*°*” The
absence of luminescence does not imply the absence of organic
materials.
Visible-induced infrared luminescence (VIL) images record the
emission of radiation (luminescence) in the infrared region (700-1100
nm) from a subject when this is illuminated with visible light.
This image characterizes the spatial distribution of pigments such as
Egyptian blue, Han blue, Han purple" and cadmium-containing
pigments.’? This technique is very sensitive and can reveal even
single particles of such pigments.
Visible-induced visible luminescence (VIVL) images record the
emission of light in the visible region (500-700 nm) from a subject
when this is illuminated with visible light (400-500 nm).
This image is useful in the characterisation of the spatial distribution
of red and yellow lakes.