Photos: Mona Lisa still pushing science forward

The researchers also looked into the painting's state of preservation. With a depth resolution of one-hundredth of a millimeter, the scan was able to provide the most detailed analysis to date of the painting's craquelure, or surface cracks. "What our results show, and this corroborates the other studies, is that the paint layer itself, despite all its craquelure, is very well bonded to the poplar substrate," said researcher John Taylor. "We didn't see any sign of paint lifting. So for a 500-year-old painting it's very good news."

The data was collected after the museum had closed on two October nights in 2004. The painting was returned to its environment-controlled chamber by the museum's curator before doors opened to visitors in the morning. The data then took more than a year to analyze.