In a method for monitoring of polymer in a liquid state, such as a polymer melt or resin, to detect inhomogeneities therein, such as the presence of other phase objects, especially gels in a matrix formed of the liquid state, the polymer in a liquid state flowing past an inspection point is monitored. At the inspection point, electromagnetic radiation in the form of UV light or polarised electromagnetic radiation is passed through the flow chamber (1) and received by a detector (8), and the absorption of the UV light or the changes in the state of polarisation of the electromagnetic radiation caused by the inhomogeneities are used to observe them.