Jean-Angelo Beraldin, optical engineer

The award-winning optical engineer explains how lasers reveal secrets about famous art, why they're useful in aeronautics and entertainment, and what it's like to spend two nights with Mona Lisa. Interview by Hayley Rutger

May 25, 2008

Photo courtesy of National Research Council of Canada

Donatello's Maddalena. A Byzantine Crypt. Aboriginal Rock Art. The Mona Lisa. These names appear in the titles of research papers by Jean-Angelo Beraldin, an engineer at the National Research Council (NRC) in Canada.

Beraldin works in optics and in metrology, the science of measurement. He and his colleagues have developed laser scanners that help companies like Boeing design planes and that allow NASA crews to inspect their shuttles for defects in space. But these days, Beraldin focuses his beams on cultural artifacts. His scanners can take pictures of every crack and brushstroke in an old painting. After he scans a painting, computers assemble the pictures into 3D models that researchers can manipulate and study.

That's why Beraldin spent two nights with the Mona Lisa in 2004. His wife wasn't pleased, he jokes in his French-Canadian accent. His scanner, called the XYZ-RGB, scanned the painting in three dimensions, termed X, Y, and Z, using three colored lasers merged together: red, green, and blue. A camera-like sensor gathered and translated that light into Mona Lisa's digital twin. The resulting computer models show everything from its color to its surface texture and the shape of the wooden plank Leonardo Da Vinci painted on.

Beraldin, 48, is as precise as his scanner. During more than 20 years of research at the NRC, he helped develop new imaging systems that make measurements smaller than a hair's diameter. He also scrutinized everything that could distort laser beams or affect the objects he measures.

Today, Beraldin travels the world to scan tombs, caves, paintings, sculptures, and more. He chats fluently in English, French, and Italian with curators and art connoisseurs, whose trust he must earn before he scans their treasures. His Mona Lisa work appeared in The New York Times, Reuters, The Globe and Mail, and other media outlets since its debut at a September 2006 press conference. He described the project in Boston at the February 2008 meeting of the American Association for the Advancement of Science. Mona Lisa came out of her bulletproof glass case for two nights so Beraldin and his colleagues could reveal her every secret — except, perhaps, why she smiles so mysteriously.

You scanned and modeled the Mona Lisa in 2004. Why keep it under wraps for two years?

We had to because the Louvre wanted to make sure we had all the information, and the book would come out, and then we were allowed to do the press conference. The book is called Mona Lisa: Inside the Painting, because that's more or less what we're doing: We're peeling off layers of the Mona Lisa as we go in. [The book, by Jean-Pierre Mohen, is available from Harry N. Abrams, Inc.]

"In Canada we're not known outside of our area of expertise. I'm not a hockey player, so I'm not that important in society. [But] I think the Mona Lisa gave people an idea of what we're doing."

When we look at paintings under museum lights, what are we missing?

When you look at an object, the position of the light, the spectrum — the colors — in the light, and the orientation and surface texture, all will influence how you're going to perceive it. The painting, how should it be viewed, I don't know. But with digital technologies, if you can imagine a display that tells you, "this is it under this lighting; this is it under that lighting," you're bringing more knowledge about the work of art and the person behind it.

You scanned the painting with a blend of red, green, and blue lasers. Why?

Blue only measures surfaces; it's short wavelength. Green goes a bit deeper, and red, much deeper. Because we have three lasers, we have three depth measurements. And we can use those to an advantage. We can show one layer, and another layer, and another layer, not only shape but also color. We correlate that with data from people who use infrared.

Infrared light, which is invisible to us, is commonly used on paintings. How does it compare with your scanner?

Infrared light is an imaging technique. Its goal is not really to measure the shape. What you want to do with infrared is look under the paint layer, to go on the drawing side. A lot of these artists would draw something first and then paint, and sometimes they make changes — people call them pentimento. Pentimento is when you regret something. On the Mona Lisa there is only one pentimento. She's sitting on a chair, and the way she's putting her finger, if you put it in a certain position, she looks tense, and if you put it in another, she looks relaxed. The goal of the painter is that she's very relaxed.

What does your computer model tell you about Leonardo's techniques? I see what look like brushstrokes, where you removed the color.

There are no [visible] brushstrokes. It's the drawing underneath. He drew, then painted the skin — the flesh tone, then he put in the shadows to give that effect of depth. So the shadows are above the skin itself. Even the clothing has layers you don't see in the painting.

You confirmed that Mona Lisa was wearing a garment pregnant women wore.

The garment is called a guarnelo. That's how you can confirm that she probably had a child. She had a bonnet too, but you don't really see it.

Do art conservationists get nervous when you're around a painting?

Always. Everyone gets nervous. You cannot touch it.

How do you get conservationists and museum curators to trust you?

You start small. You start with scanning objects from markets around the world or your local pawn shops. Also, you talk with people. You meet with people in a lot of museums.

Over the two nights you spent scanning the Mona Lisa, it was kept in a very controlled environment. Why was that important?

People are worried about the conservation of a work of art. Going from cold to warm, high humidity to low humidity, these are the worst things. Usually we were in an environment that was controlled. Safety was one thing. The other one was temperature and humidity. If they exceeded a certain level, everybody had to go out of the room. If you're trying to measure something, and if the temperature changes while you're measuring, these [paintings] are not rigid. They move with temperature. If you don't take care of that, you can draw the wrong conclusions. Wood will change shape. It's the same with any material. Say you're trying to assemble a plane like the Airbus 380. You have to understand what's happening with the temperature and humidity during the setup.

Can lasers damage a painting? I've heard camera flashes can cause damage over time.

Our lasers are very low power. You have to look at the amount of energy — it's power times the time spent on a location. You can imagine when you have flash photography, and you need a lot of light to take your picture because your sensor is not sensitive. That could be damaging, because it's intense light. Imagine the Louvre, getting eight million people a year, and everybody taking ten pictures of the Mona Lisa. That could be a lot of energy. If you go to museums around the world, you'll notice there is not much light.

Your laser isn't just gentle, it's tiny, right?

The spot size is like the diameter of a hair.

What did you first scan with the XYZ-RGB lasers?

A little object that somebody brought back from Peru, from a shop. That was the first experiment we did, in 1990. You can imagine the kind of emotion you get. It happened with other systems too. We had this video camera that can take 3D pictures. Even as scientists you get excited when you see these things.

Imaging technology you helped develop was used in movies like the "The Matrix" and "The Lord of the Rings". How was it used?

One example is a technology we developed for draping images on 3D models of art or cultural sites. This software was sold to a company that does special effects for movies. We look at some of these movies and think, ah, that was draped with our software. We can say, "I have a little part in that."

Your laser scanners ended up on the space shuttle Discovery. What did they do?

There was a robotic arm [designed and built in Canada] that would grab things. On the end is a laser camera that does inspections of tiles.

The tiles that protect the spacecraft against heat?


Would it surprise people to know how many jobs your lasers scanners do?

In Canada we're not known outside our area of expertise. Probably it's the way Canada operates. I'm not a hockey player, so I'm not that important in society. When people do [television] programs about us, people say, "It's too technical. Nobody wants to see your lab." How can you be known in your community if TV is not interested, newspapers are not interested? It's not a problem because people in the technology field are aware of us. NASA is aware, Boeing is aware, Airbus is aware. The major research projects are aware of us. I think the Mona Lisa gave people an idea of what we're doing.

You've been working on another cool project, scanning ancient cave paintings in southern Italy.

We went in 2005 and did the major rooms. We did five chambers. It's about 300 meters long. We have a scanner that can do bigger things, so you can imagine the laser spot size is bigger. To give it color, we take a high-quality photograph, and we drape the photograph around the [modeled] walls. Once you bring it to the digital world, it brings up so many applications. It could be for art connoisseurs, it could be for curators, it could be for the public. We'll have to do some computer graphics to show it using some torches, or the first light [flashlights] of people who discovered the cave.

What will you model in the future?

The Acropolis. The building is called the Erechteion. That's where the maidens are [the Caryatids, which form six columns]. We're documenting the whole building in 3D.

Do you feel privileged to see all these artworks and artifacts?

Yes, even things we never modeled. In Florence, they showed me the room where Michelangelo hid during the war. I spent my early career in a lab. All of a sudden, I go out, and it's like a renaissance of myself.

Hayley Rutger, a graduate student in the Science Communication Program at UC Santa Cruz, earned a B.S. in biology from Stetson University. She has worked as a reporting intern at the Monterey County Herald, the Stanford University News Office, and the Stanford University Medical School. Hayley will spend the summer in Washington, D.C. as an intern at National Geographic.

© 2008 Hayley Rutger