Seeing inside tissue. Caltech researchers develop technique to focus light inside biological tissue

Imagine if doctors could perform surgery without ever having to cut through your skin. Or if they could diagnose cancer by seeing tumors inside the body with a procedure that is as simple as an ultrasound. Thanks to a technique develoMicroscope imageped by engineers at the California Institute of Technology (Caltech), all of that may be possible in the not-so-distant future.

The new method enables researchers to focus light efficiently inside biological tissue. While the previous limit for how deep light could be focused was only about one millimeter, the Caltech team is now able to reach two and a half millimeters. And, in principle, their technique could focus light as much as a few inches into tissue. The technique is used much like a flashlight shining on the body's interior, and may eventually provide researchers and doctors with a host of possible biomedical applications, such as a less invasive way of diagnosing and treating diseases.

If you crank up the power of light, you might even be able to do away with a traditional scalpel. "It enables the possibilities of doing incision-less surgery," says Changhuei Yang, a professor of electrical engineering and bioengineering at Caltech and a senior author on the new study. "By generating a tight laser-focus spot deep in tissue, we can potentially use that as a laser scalpel that leaves the skin unharmed."

Ying Min Wang, a graduate student in electrical engineering, and Benjamin Judkewitz, a postdoctoral scholar, are the lead authors on the paper, which was published in the June 26 issue of the journal Nature Communications.