New type of fiber-optic interferometer for sensing displacement from submicrons to millimeters

A compact fiber-optic interferometer has been developed to measure displacement from submicrons to millimeters. We have shown that it is suitable to measure the expansion of the piezoelectric transducers which are widely used in the modern instruments and devices. It can measure the displacement even it has small surface tilt during the measurement. The whole device can be can be install to other device owing to the compactness and stability. The precision of the measurement is increased to be much better than the wavelength by digital signal analysis. The repeated measurement showed that the sensitivity and maximum error were less than 5 nanometers.