Double Beam Laser Interferometer to Measure Piezoelectric Displacements for Elimination of Substrate Effect in Thin Films

摘要

Using a feedback loop of anti- interference to stabilize optical path length difference the interferometer is operated in the most sensitive operation point. So the measurable minimum displacement of piezoelectric thin films induced by electric filed is 0.3 pm. The interferometer also can be used to measure butterfly curves of ferroelectric thin film, because by using lock-in amplifier, the complex piezoelectric response can be measured. The operating frequency bandwidth of the interferometer is from 1 kHz to 102 kHZ. All measurements by the interferometer are automatically completed because the whole measuring process including the date acquisition and the results displaying is controlled by personal computer communicating with the lock-in amplifier via RS232 interface.