How the Technique Works (IMAGE) California Institute of Technology Caption Left: Light enters the tissue sample and is scattered (blue arrows). From above, ultrasound is focused into a small area inside the tissue. The ultrasound shifts the frequency of any light that passed through that area ever so slightly, changing its color. The color-shifted light (green) is then recorded. Right: The recorded light is sent back to retrace its steps to the small region where the ultrasound was focused -- which means the light itself is focused on that area. Credit Caltech/Ying Min Wang and Benjamin Judkewitz Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.