Together with his research team, Professor Vasilis Ntziachristos
from the Helmholtz Zentrum Munich, Germany and the Technical
University Munich, Germany developed a new technology to make
light audible. The technique, called multi-spectral opto-
acoustic tomography (MSOT), combines light and ultrasound to
visualize fluorescent proteins that are seated several
centimeters deep into living tissue. The researchers used a
genetically modified adult zebra fish which carried fluorescent
pigments in its tissue. They illuminated the fish from multiple
angles using flashes of laser light that are absorbed by the
fluorescent pigments in the fish. The pigments absorb the light,
a process that causes slight local increases of temperature,
which in turn result in tiny local volume expansions. This
happens very quickly and creates small shock waves. In effect,
the short laser pulse gives rise to an ultrasound wave that the
researchers pick up with an ultrasound microphone. To analyze
the resulting acoustic patterns, a compu