Comparison between scanning acoustic microscopy and submillimeter spectroscopy. A new opportunity to investigate dielectric behavior and structure of materials

In acoustic microscopy, ultrasound and hypersound range waves (10 MHz-2 GHz) are used as the analysis factor. The following trends in the development of this method for polymers seem promising: morphology of smooth surfaces with nonuniform distribution of physical and mechanical properties, measurements of local anisotropy, study of dynamic phenomena connected with the change in materials due to physical factors (temperature, UV, IR, SHF-radiation), mechanical and chemical factors. In the field of submillimeter spectroscopy we have developed a spectrometer capable of performing dielectric measurements in solids in the previously inaccessible region of millimeter-submillimeter wavelengths (3-0.3 mm). The spectrometer employs intensive frequency tunable radiation from a Backward-Wave Oscillator (BWO) in combination with optical contactless measuring schemes, which realizes the most efficient advantages of infrared spectroscopy and conventional microwave technique: precise, independent measurements of the real ε´ and imaginary ε´´ parts of the spectra in a wide frequency range