It's all just Greek to us, but to the owner of the Palimpsest and the research team at the Walters, the final images of the hidden text represent years of experimentation. To avoid damaging the ancient document, the team has had to be extremely selective in what techniques they employ to see the original writing. Here are the steps they took to create the images:
Step 1: Multispectral imaging.. Numerous digital photographs are taken using different wavelengths of light -- the visible spectrum (white light) and ultraviolet. The resulting images are "stacked," and a computer algorithm filters the information to create an image of Archimedes' text. The technique worked, although the images were not of high enough quality to allow scholars and translators to decipher the characters.
Step 2: Multispectral imaging. The research team then tried combining two different wavelengths of light. The original text appears faint when exposed to visible light, but when viewed through only the red channel, it almost completely disappears. When viewing the image through the blue channel of ultraviolet light, the text appears backlit. Researchers took pictures under both wavelengths and combined them into a single image. The parchment appears white, the prayer book appears black, and the original text appears red.
Step 3: X-ray fluorescence imaging.. The initial results were excellent, but small portions of text still could not be deciphered. In this experimental X-ray imaging method, researchers use a particle accelerator to aim an X-ray pulse at a single page. The X-rays pass through the forged painting and hit atoms in Archimedes' ink. The X-rays remove the innermost electron, creating a kind of gap. A nearby electron fills the gap, and as it does, releases an X-ray. Sensitive detectors map the X-rays and create an image that shows the iron in the ink, highlighting the original Greek characters. Eureka!
The research team at the Walters has posted a detailed explanation of their research on their Web site.
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