SelfMixing Techniques for Sensing Applications（SelfMixing传感技术的应用）.pdfVIP

from: Proceedings ODIMAP IV, Oulu, June 16-18, 2004, pages 213-234 Self-Mixing Techniques for Sensing Applications Silvano Donati, Guido Giuliani, Michele Norgia Dipartimento di Elettronica, Università di Pavia, Via Ferrata 1, I-27100 Pavia, Italy e-mail: silvano.donati@unipv.it Abstract - We present a review of laser diode self-mixing interferometry applied to the measurement of a number of measurands, that we can classify as mechanical (displacement, vibration, distance, angle) as well as physical (remote optical echoes, optical attenuation, coherence length and enhancement factor). After a brief summary of the operating principle, we discuss the applications and report the experimental results about the performance of the sensors. 1 INTRODUCTION Laser interferometry is one of the most powerful and pervasive techniques in science and engineering, and provides an unparalleled sensitivity to measure- ment of optical path lengths and derived quantities [1]. Most commonly, laser interferometers are developed from the external configuration [1], in which the laser is the source and splitting/recombination of the beams is made external to the source, in an optical interferometer. This is not the only possibility, however, as we can also have an internal configuration [1], like in the ring-laser gyroscope, where the laser cavity is also used to develop the optical path length of interest. In recent years, a third configuration has attracted considerable interest, one in which a fraction of the light back-reflected or back-scattered by a remote target is allowed to re-enter into the laser cavity. This interaction generates a modu- lation of both the amplitude and the fr