A method and system for luminescence molecular imaging or tomography of aregion of interest in a scatteringmedium is disclosed. The system comprises a non-linear luminescent markermaterial arranged in the scattering medium. Contrastand resolution of the imaging or tomography is thus improved. The non-linearmarker is for instance configured to upconvert incominglight of an illumination wavelength. The non-linear power dependence of themarker enables further improvement of theimaging by using images taken with two or more excitation beamssimultaneously.
