In contrast to imaging methods which rely on inverse scattering, such as medical ultrasound or optical tomography, where the imaging parameters are inferred from measuring waves which are scattered at the object, coupled physics methods are using a combination of different physical phenomena to generate a signal. The idea behind this is to have one modality to interact with the medium and distort it in a certain way and to image the resulting effect with the second modality. So, ideally, you would be able to select with the first modality exactly the objects you want to see and observe them with the second modality (much like fluorescent imaging where you attach fluorescent dyes at the particles of interest and detect those afterwards by tracing the emitted light).
The precise modelling of such imaging systems can become rather involved: Not only are there two different physical effects (and therefore approximately twice the number of unknown physical parameters), also their interaction has to be properly incorporated. In an ideal case, however, the reconstruction can be split into two separate inverse problems: One to backpropagate the measured signal to recover the distortion of the medium produced by the first modality; and a second one to obtain from this generated internal data the corresponding physical parameters of the medium.
We want to discuss in this talk these inverse problems and the possibility of reconstructing the relevant physical parameters using mainly the example of photoacoustic imaging.