A new approach to optical imaging makes it possible to quickly and economically monitor multiple molecular interactions in a large area of living tissue—such as an organ or a small animal; technology that could have applications in medical diagnosis, guided surgery, or pre-clinical drug testing. The method, which is detailed in Nature Photonics, is capable of simultaneously tracking 16 colors of spatially linked information over an area spanning several centimeters, and can capture interactions that occur in mere billionths of a second.