Interferometer based methods for research of piezoelectric materials
Author(s): Miroslav Sulc
Affiliation(s): Technical University of Liberec
Topic: 1. Interferometry & Optical Testing Techniques
The laser interferometer systems were applied for the research of piezoelectric materials. Both Michelson single beam and Mach-Zender double beam arrangements were used for measurements of both piezoelectric and electro-optical Pockels coefficients. The homodyne system is working at dynamic mode. Voltage (frequency in range 1Hz-100 kHz) is applied on the samples. The amplitude of sample oscillation is determined by lock-in amplifier technique with precision of the order of 10^-12 m. The unique system is used for coefficients measurement in wide temperature range. The cryogenic cooling system, based on closed circuit of helium gas, is used for low temperature measurements, and heated evacuated chamber for the measurements above room temperature. The fundamental interferometer measurement problems as a temperature instability and mechanical vibration of cryostat were sold. All parts of interferometer (not only sample) are placed inside the temperature chamber of diameter 50 mm. The double beam interferometer, characterized by new arrangement with minimum of elements, was constructed and located inside cryostat too. So this system seems be very stable in wide temperature range. The influence of piezoelectric effect to Pockels coefficient measurement was eliminated by new compensative method. It essentially increased precision of measurement.