A new technique for the nondestructive characterization of semiconductor heterostructures is presented. The technique consists of a measurement of the attenuated total reflection (ATR) spectrum of the structure. This spectrum is characterized by sharp interference patterns and deep resonance minima, corresponding to the excitation of various resonant modes. From the analysis of the ATR spectrum, detailed information can be obtained on the geometrical and compositional parameters of the structure. The technique, which is nondestructive and fast, is a natural candidate for general use in semiconductor technology (microelectronics, optoelectronics, integrated optics). To illustrate its potential, we discuss its application to the case of the thickness characterization of the wafers used to manufacture GaAlAs heterostructure lasers.