Photoacoustics is an imaging technique that combines the advantages of optical imaging methods with established ultrasound techniques. Photoacoustics is able to combine the high optical contrast of optical imaging with the good resolving power of ultrasound imaging in highly scattering tissue. Thus, by using appropriate tumor-specific contrast agents, photoacoustics is potentially able to distinguish tumorous from healthy tissue.

The combination of light and sound is made possible by exploiting the photoacoustic effect: In the photoacoustic effect, an ultrasonic wave is generated in a medium by irradiation with light, which can be detected with an ultrasonic transducer. The detected pressure amplitude is proportional to the optical absorption of the medium.