Method for imaging or spectorscopy with a non-linear interferometer

It is claimed a method for imaging and/or spectroscopy comprising the stepsi) generation of a first signal field and a first idler field, by pumping a first non-linear medium, such that the two fields are correlated,ii) illumination of the object with the first idler field,iii) generation of second signal field and a second idler field, by pumping a first non-linear medium, such that the two fields are correlated,iv) combination of the first and second idler fields, such that the two fields are indistinguishable, and a combination of the first and second signal fields, such that the two fields interfere,v) first measurement of the interfered signal field by a detection means,vi) one or more additional measurements of the interfered signal field, wherein for each additional measurement in step vi) a different phase shift a is generated in the setup, and wherein all measurements are carried out within the stability time of the setup,vii) calculation of the phase function F.