便携式高光谱感应器在有机胶料无损分析中的应用初探

Non-invasive analysis of artworks is one of the essential requirements in heritage conservation. In this study, a spectroradiometer in the field of remote sensing -a portable, full range hyperspectral sensor-was used to characterize organic compounds commonly found in cultural relics. It can obtain a continuous reflection spectrum within 0.2 s in the range of 350~2 500 nm, which covers visible, near-infrared and short-wave infrared regions. In the study, the three most widely used binders (egg yolk, rabbit skin glue, and linseed oil) were analysed. Four different pigments were used to mix with them to prepare painting mock-ups. This technique's applicability and accuracy were verified by testing a single component and a mixture of binders with pigments. The most diagnostic information of the three binders mainly lies in the range from 1 100 to 2 400 nm. Once the binders were mixed with inorganic pigments, the original position of the peaks experienced three types of modifications: (1) the shoulder peak at about 1 507 nm disappeared; (2) the broad peak between 1 943~1 922 nm shifted; (3) the absorption peak of N-H stretching and bending combination band at 2 050 nm shifted to about 2 070 nm. It is worth noting that the absorption peaks of the C-H combination and overtone bands showed the same positions in the spectra of single component and mixtures. Although in some cases, the interference between the absorption peaks of inorganic pigments and organic compounds influence on the identification, the use of their first derivative transformation can ameliorate this situation. Results showed that the hyperspectral sensor could effectively identify organic binders. This fast and non-destructive technique is feasible not only in laboratory conditions, but its portability also allows for in-situ analyses in outdoor environments.