The infrared scanner consists of an X-Y precision translation stage with an optical head attached onto.

The painting surface is scanned with a spatial resolution of 4 pixel/mm.

The optical head consists of a lens, an IR photodiode and an illumination system.

The latter moves along with the optical head so that the lighting conditions are identical for each point sampled. The photodiode output signal is sampled by with 12-bit resolution, giving about 4000 shades of grey.
The high quality of the digital reflectograms is due to the high-resolution of the images, the great number of grey levels, and to the precise mechanical movement, that does not introduce geometrical distortions in the image.

IR Riflettography