Abstract: A method for interferometric measurement comprises emitting waves onto a reference surface (1) and onto a measured object (2), which each reflects a part of the emitted waves, and receiving both the reflected parts of the waves by the same receiver (4). In the receiver the parts of the waves generate a representation of the measured object (2) in the form of an interferogram, from which the form of the measured object (2) is determined. The emitted waves comprise waves of three well-defined wavelengths &ngr;1, &ngr;2 and &ngr;3, where &ngr;1≠&ngr;2≠&ngr;3, which wavelengths are chosen to substantially satisfy the mutual relation &ngr;1=(&ngr;2.&ngr;3)/(2.&ngr;3−&ngr;2) and generate an interferogram each in the receiver (4).