REFLECTOGRAPHY, A NDT METHOD FOR IMAGES DIAGNOSIS

摘要

Infrared Reflectography (IR) is a non-destructive technique used for the analysis of artworks (paintings) to reveal hidden particularities under the pictorial layer. The technique is based on an infrared radiation crossing the pictorial layer and reflected at the base or preparation of the artwork. Since they are generally transparent to radiation in the near IR, the results are a function of the absorption rates to the infrared radiation from the different pigments. A CCD camera, mounted by a sweeping device and equipped with appropriate filters, in the spectral band from ultraviolet to near infrared, detects the reflected radiation and transforms it into a visible image. A luminous source consisting in an halogen lamp is used to produce radiation in the near infrared. The digitized images, denoted as REFLECTOGRAMS, are processed by an integration program to obtain a total image of the artwork called REFLECTOGRAPHY. Thus, the REFLECTOGRAPHY contains information located in the interior as well as on the surface of the artwork. This inspection technique reveals lines, underlying drawings, author signs, inscriptions, restorations, or alterations suffered by the painting in addition to the artist's regrets. Furthermore, these details hidden to the direct sight, gives precious indications both on the realization technique and on the state of conservation of the artwork to restorers and art historians and, in some cases, it can help of the artwork authenticity. This technique has been applied to the diagnostics of important paintings from the Buenos Aires National Museum (MNBA). This paper describes the operating principles of the technique and discusses the analysis of one artwork in which original outlines under the pictorial layer were found, and the artist's regrets were revealed. Key words: Infrared Reflectography, Images Diagnosis, Paintings, Inspection and Application of NDT.