INTERFEROMETER BASED METHODS FOR RESEARCH OF PIEZOELECTRIC MATERIALS

摘要

The various laser interferometer systems are used for the measurement of piezoelectric and electro-optics coefficients of piezoelectric materials. Both Michelson single beam and Mach-Zehnder double beam homodyne systems are working at dynamic modes. The alternating voltage (frequency in range 1Hz-100kHz) is applied on the samples. The amplitude of samples displacement is determined by lock-in amplifier technique. It enables to measure very small amplitudes of the order of 10~(-12)m. The new unique system is used for measurement of coefficients in wide temperature range. The cryogenic cooling system, based on closed circuit of helium gas, is used for low temperature measurements and evacuated temperature chamber for the measurements above room temperature. The fundamental interferometer measurement problems as a temperature instability and mechanical vibration of cryostat are sold. The all parts of interferometer are placed inside the cryostat. The relative motion of interferometer's parts is almost suppressed by this way. To locate a double beam Mach-Zehnder interferometer to small temperature chamber was problematic because it consists of many optical elements. The new type of double beam interferometer with minimum of elements was constructed and located inside cryostat. The similar interferometric methods are used for electro-optical coefficients measurements too.