The Sound of Light

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 computer is attached. The computer uses specially developed mathematical formulas to evaluate and interpret the specific distortions caused by scales, muscles, bones and internal organs to generate a three-dimensional image. In the future this technology may facilitate the examination of tumors or coronary vessels in humans.
www.helmholtz-muenchen.de/en

Multi-spectral opto-acoustic tomography or MSOT allows the investigation of subcellular processes in live organisms.

New Type of Imaging: Fastest Camera

Researchers at the UCLA (University of California, Los Angeles, US) Henry Samueli School of Engineering and Applied Sciences have developed the serial time-encoded amplified microscopy (STEAM) technology. It is a novel, continuously running camera that enables real-time imaging at a frame rate of more than 6 MHz and a shutter speed of less than 450ps – roughly a thousand times faster than any conventional camera. Keisuke Goda, Kevin Tsia and team leader Bahram Jalali describe a new approach that does not require a traditional CCD (charge-couples device) or CMOS (complementary metal-oxide semiconductor) video camera. The new imager operates by capturing each picture with an ultrashort laser pulse. It then converts each pulse to a serial data stream that resembles the data in a fiber optic network rather than the signal coming out of the camera. Using a technique known as amplified dispersive Fourier transform, these laser pulses, each containing an entire picture, are amplified and simultaneously stretched in time to the point that they are slow enough to be captured with an electronic digitizer. Those cameras could be used for observing high-speed events such as shockwaves, communication between cells, neural activity or laser surgery.
www.ucla.edu