Featured Research

from universities, journals, and other organizations

Hidden Art Could Be Revealed By New Terahertz Device

Date:
February 5, 2008
Source:
University of Michigan
Summary:
Like X-rays let doctors see the bones beneath our skin, "T-rays" could let art historians see murals hidden beneath coats of plaster or paint in centuries-old buildings, engineering researchers say.

Like X-rays let doctors see the bones beneath our skin, "T-rays" could let art historians see murals hidden beneath coats of plaster or paint in centuries-old buildings.
Credit: Image courtesy of University of Michigan

Like X-rays let doctors see the bones beneath our skin, "T-rays" could let art historians see murals hidden beneath coats of plaster or paint in centuries-old buildings, University of Michigan engineering researchers say.

T-rays, pulses of terahertz radiation, could also illuminate penciled sketches under paintings on canvas without harming the artwork, the researchers say. Current methods of imaging underdrawings can't detect certain art materials such as graphite or sanguine, a red chalk that some of the masters are believed to have used.

The team of researchers, which includes scientists at the Louvre Museum, Picometrix, LLC and U-M, used terahertz imaging to detect colored paints and a graphite drawing of a butterfly through 4 mm of plaster. They believe their technique is capable of seeing even deeper.

In March, the scientists will take their equipment to France to help archaeologists examine a mural they discovered recently behind five layers of plaster in a 12th century church.

"It's ideal that the method of evaluation for historical artifacts such as frescoes and mural paintings, which are typically an inherent part of a building's infrastructure, be non-destructive, non-invasive, precise and applicable on site. Current technologies may satisfy one or more of these requirements, but we believe our new technique can satisfy all of them," said John Whitaker, an author of the paper who is a research scientist and adjunct professor in the Department of Electrical Engineering and Computer Science at U-M.

Terahertz imaging can reveal depth and detail that other techniques cannot, Whitaker said. And it's not potentially harmful like X-ray imaging because terahertz radiation is non-ionizing. Its rays don't have enough energy to knock electrons off atoms, forming charged particles and causing damage, like X-rays do.

While terahertz radiation is all around us in nature, it has been difficult to produce in a lab because it falls between the capabilities of electronic devices and lasers.

"Terahertz is a strange range in the electromagnetic spectrum because it's quasi-optical. It is light, but it isn't," said Bianca Jackson, first author of the paper who is a doctoral student in applied physics.

The device used for this research is a hybrid between electronics and lasers. It was developed by the Ann-Arbor based company Picometrix. It's called the T-Ray™ system, and it uses pulses from an ultra-fast laser to excite a semiconductor antenna, which in turn emits pulses of terahertz radiation.

The rays permeate the plaster, and some reflect back when there is a change in the material. When they bounce back and how much energy they retain depends on the material they hit. Different colors of paint, or the presence of graphite, for example, cause tell-tale differences in the amount of energy in the returning waves. A receiver measures this energy, and the scientists can use the data to produce an image of what lies beneath, Jackson explained.

A similar device made by Picometrix is used routinely to examine the foam on the space shuttle's fuel tanks for underlying damage, said Irl Duling, director of terahertz business development at Picometrix and an author of the paper. This paper discusses a new application, rather than a new device.

G่rard Mourou, a U-M electrical engineering professor emeritus, said he believes this technique will be especially useful in Europe, where historic regime changes often resulted in artworks being plastered or painted over. This was common in places of worship, some of which switched from churches to mosques and vice versa over the centuries.

"In France alone, you have 100,000 churches," Mourou said. "In many of these places, we know there is something hidden. It has already been written about. This is a quick way to find it."

And Leonardo DaVinci's "The Battle of Anghiari," for example, is believed to lurk beneath other frescos at the Palazzo Vecchio in Florence, Italy, Mourou said.

The paper  "Terahertz imaging for non-destructive evaluation of mural paintings," is published in the February edition of Optics Communications.

Mourou is the A. D. Moore Distinguished University Professor Emeritus of Electrical Engineering and Computer Science. He currently holds a position at the Laboratoire d'Optique Appliqu่e. Other authors are: Steven Williamson of Picometrix; Marie Mourou, a U-M undergraduate student; and Michel Menu, of the Center for Research and Restoration at The Louvre Museum.


Story Source:

The above story is based on materials provided by University of Michigan. Note: Materials may be edited for content and length.


Cite This Page:

University of Michigan. "Hidden Art Could Be Revealed By New Terahertz Device." ScienceDaily. ScienceDaily, 5 February 2008. <www.sciencedaily.com/releases/2008/02/080204111732.htm>.
University of Michigan. (2008, February 5). Hidden Art Could Be Revealed By New Terahertz Device. ScienceDaily. Retrieved July 29, 2014 from www.sciencedaily.com/releases/2008/02/080204111732.htm
University of Michigan. "Hidden Art Could Be Revealed By New Terahertz Device." ScienceDaily. www.sciencedaily.com/releases/2008/02/080204111732.htm (accessed July 29, 2014).

Share This




More Fossils & Ruins News

Tuesday, July 29, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Asteroid's Timing Was 'Colossal Bad Luck' For The Dinosaurs

Asteroid's Timing Was 'Colossal Bad Luck' For The Dinosaurs

Newsy (July 28, 2014) — The asteroid that killed the dinosaurs struck at the worst time for them. A new study says that if it hit earlier or later, they might've survived. Video provided by Newsy
Powered by NewsLook.com
Did ISIS Destroy Jonah's Tomb?

Did ISIS Destroy Jonah's Tomb?

Newsy (July 25, 2014) — Unverified footage posted to YouTube purportedly shows ISIS militants destroying a shrine widely believed to be the tomb of the prophet Jonah. Video provided by Newsy
Powered by NewsLook.com
Europe's Highest Train Turns 80 in French Pyrenees

Europe's Highest Train Turns 80 in French Pyrenees

AFP (July 25, 2014) — Europe's highest train, the little train of Artouste in the French Pyrenees, celebrates its 80th birthday. Duration: 01:05 Video provided by AFP
Powered by NewsLook.com
Richard III's Car Park Burial Site Opens to Public

Richard III's Car Park Burial Site Opens to Public

AFP (July 25, 2014) — Visitors will be able to look down from a glass walkway on the grave of King Richard III when a new centre opens in the English cathedral city of Leicester, where the infamous hunchback was found under a car park in 2012. Duration: 00:35 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins