Patent ID: 7829869

Claim:
A method for checking documents of value comprising the steps: illuminating a document of value with clocked excitation light (E) of at least one light source, said light being switched on for at least one first time interval (T on ) and being switched off for at least one second time interval (T off ), detecting a first luminescence intensity (L 1 ) within the first time interval (T on ), detecting a second luminescence intensity (L 2 ) within the second time interval (T off ), linking the second luminescence intensity (L 2 ) with the first luminescence intensity (L 1 ) and determining a corrected second luminescence intensity (P 2 ) of the document of value or a partial area (A, P) of the document of value, wherein the corrected second luminescence intensity (P 2 ) substantially corresponds to a phosphorescence signal of the document of value or of the partial area (A, P) of the document of value.