In the science of cultural manuscripts, there is often a conflict between the preservation of an original manuscript and its complete study. For example, clay tablets were used in the Middle Bronze Age to communicate cuneiform messages. The clay tablets themselves were sometimes contained in a clay covering so that only the recipient could read the message, or at least know that someone else had read the message if the clay envelope was tampered with or missing. Clay tablets with these “envelopes” survive to this day and are of great historical interest, but to unlock this information requires that the researcher can read the encased message. However, reading the contents of a sealed “letter” and preserving the “envelope” can be difficult or impossible. With an X-ray system from VisiConsult, there is no need to compromise between these two goals. The replica of a clay tablet with Assyrian cuneiform writing serves as an example.
Information as the engine of all research
The letter, including the clay envelope, is only a few centimeters in size, making it easy to place on the turntable in a VisiConsult CT inspection system. Managing Director Lennart Schulenburg explains “For most of our customers, the focus is on information about deviations and defects – such as in the field of aerospace where safety is an essential factor.” But this technology is increasingly being used in other application areas, as in this case – the field of cultural manuscripts. Instead of revealing defects, here the focus is to use X-rays to non-destructively reveal information that can be used for important research.
Figure 1 Cécile Michel writing a cuneiform letter on clay in the Old Assyrian dialect. Foto: Vanessa Tubiana-Brun (CNRS).
Figure 2 After evaluation, the 3D digital version of the letter can be examined as desired
From the collection to the X-ray booth
This particular clay tablet dates back to the 19th century B.C., and comes from a private collection. The cuneiform text it contains represents one of the first references to Assyrian written language. A replica was created by Professor Cécile Michel: “We created this replica and its cover to understand how people in ancient Mesopotamia wrote on clay and made clay covers, and also to have a sample on which to perform tests. The goal was to develop a non-invasive method to read the tablet enclosed in its shell.”
Simply explained, the CT scan is performed starting with an X-ray source. This generates the X-ray beam, which in turn penetrates the clay tablet. Depending on the material density, the beam is attenuated and is captured by a detector. Between the X-ray tube and the detector, the clay tablet is automatically rotated through a total of 360° at hundreds of angles. From these numerous projection images, a digital reconstruction of the individual 2D pixels into volume pixels (the voxels) takes place. In other words, a digital 3D representation of the clay letter is created.
Examine hidden message information non-destructively
After the images are processed, the hidden message is revealed on the monitor. Particularly helpful is the clear legibility of the cuneiform writing. The text shows a message from two sisters to their brother. They chastise him for his greed for profit and neglect of his religious duties.
The CT technique convinced Professor Ralf Möller, Director of the Institute for Information Systems, at the University of Lübeck: “This non-destructive method has proven to be excellent. On the monitor, you simply set a transparency for the envelope and you can see inside. The message becomes legible.”
As a result, information is gained and the discovery continues to be preserved. In addition, many software and hardware filters can be used to visualize all sorts of additional materials. Digitizing exhibits has an added value that should not be underestimated because it also creates with it the opportunity to digitally experience exhibits by means of virtual reality for instance.
Figure 3 Transparencies can also be set, as here for the envelope. Only the letter inside is still clearly visible.
Figure 4 The HDX T.225 is a high-precision CT system that is particularly suitable for the field of research.
X-ray systems for research
Two high-precision CT systems from VisiConsult’s new HDX product line are particularly suitable for the research sector: the HDX T.225 with 225 kV, and the HDX T.450 with a corresponding 450 kV energy. Jason Robbins, Head of Sales at VisiConsult, adds: “Research facilities benefit from the many options for flexible configuration. Depending on the objects to be examined, we can put together appropriate X-ray sources, detectors and other features, that precisely match the respective examination requirements.” A third system is coming soon to the HDX line so research facilities can look forward to even more exciting technology!
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