Compound-cavity micro-interferometer using VCSEL and piezoelectric actuator

A novel compound-cavity interferometer which measures displacement without ambiguity is studied. A vertical-cavity surface-emitting laser (VCSEL) has several advantages in comparison with a conventional edge-emitting laser for sensing use. The authors have proposed an optical sensor using a VCSEL and it has realized very small size without optical parts such as a collimator lens. The new sensor we proposed in this paper is based on a combination of a micro optical interferometer using a VCSEL and a piezoelectric actuator. In this study, two signal waves which have /spl pi//2 radian phase difference are obtained in order to enable detection of the displacement direction.