def GetWaveSet(self):
        """Obtain the wavelength set for the composite spectrum.
        This is done by using :func:`MergeWaveSets` to form a union of
        wavelength sets from its components.

        Returns
        -------
        waveset : array_like
            Composite wavelength set.

        """
        waveset1 = self.component1.GetWaveSet()
        waveset2 = self.component2.GetWaveSet()
        return MergeWaveSets(waveset1, waveset2)