Karch Jakub, Bartl Benjamin, Dudak Jan, Zemlicka Jan, Krejci Frantisek
Institute of Experimental and Applied Physics, Czech Technical University in Prague, Horska 3a/22, 128 00 Prague 2, Czech Republic; Faculty of Biomedical Engineering, Czech Technical University in Prague, Nam. Sitna 3105, 272 00 Kladno, Czech Republic.
National Archives, Preservation Department, Archivni 2257/4, 14900 Prague 4, Czech Republic.
Micron. 2016 Dec;91:22-28. doi: 10.1016/j.micron.2016.09.006. Epub 2016 Sep 16.
Historical beeswax seals are unique cultural heritage objects. Unfortunately, a number of historical sealing waxes show a porous structure with a strong tendency to stratification and embrittlement, which makes these objects extremely prone to mechanical damage. The understanding of beeswax degradation processes therefore plays an important role in the preservation and consequent treatment of these objects. Conventional methods applied for the investigation of beeswax materials (e.g. gas chromatography) are of a destructive nature or bring only limited information about the sample surface (microscopic techniques). Considering practical limitations of conventional methods and ethical difficulties connected with the sampling of the historical material, radiation imaging methods such as X-ray micro-tomography presents a promising non-destructive tool for the onward scientific research in this field. In this contribution, we present the application of high-contrast X-ray micro-radiography and micro-tomography for the investigation of beeswax seal fragments. The method is based on the application of the large area photon-counting detector recently developed at our institute. The detector combines the advantages of single-photon counting technology with a large field of view. The method, consequently, enables imaging of relatively large objects with high geometrical magnification. In the reconstructed micro-tomographies of investigated historical beeswax seals, we are able to reveal morphological structures such as stratification, micro-cavities and micro-fractures with spatial resolution down to 5μm non-destructively and with high imaging quality. The presented work therefore demonstrates that a combination of state-of-the-art hybrid pixel semiconductor detectors and currently available micro-focus x-ray sources makes it possible to apply X-ray micro-radiography and micro-tomography as a valuable non-destructive tool for volumetric beeswax seal morphological studies.
历史悠久的蜂蜡印章是独特的文化遗产。不幸的是，许多历史印章蜡呈现出多孔结构，具有强烈的分层和脆化倾向，这使得这些物品极易受到机械损伤。因此，了解蜂蜡降解过程在这些物品的保存及后续处理中起着重要作用。用于研究蜂蜡材料的传统方法（如气相色谱法）具有破坏性，或者只能提供关于样品表面的有限信息（微观技术）。考虑到传统方法的实际局限性以及与历史材料采样相关的伦理难题，诸如X射线显微断层扫描等辐射成像方法为该领域的进一步科学研究提供了一种有前景的无损工具。在本论文中，我们展示了高对比度X射线显微放射成像和显微断层扫描在蜂蜡印章碎片研究中的应用。该方法基于我们研究所最近开发的大面积光子计数探测器的应用。该探测器结合了单光子计数技术的优点和大视野。因此，该方法能够以高几何放大倍数对相对较大的物体进行成像。在对所研究的历史蜂蜡印章进行重建的显微断层扫描中，我们能够无损地且以高成像质量揭示诸如分层、微腔和微裂缝等形态结构，空间分辨率低至5μm。因此，所展示的工作表明，结合先进的混合像素半导体探测器和目前可用的微焦点X射线源，可以将X射线显微放射成像和显微断层扫描作为一种有价值的无损工具用于蜂蜡印章的体积形态研究。
