Analyse von SMI-Sensoren zur Messung von Abstaenden und Geschwindigkeiten Abschlussbericht

Interferometric techniques which are based on determination of the optical phase difference in twobeam interferometers are widely used for high precision measurements. Unfortunately, a signal at the interferometer output usually does not carry information about direction of the phase change. For unambiguous measurements a heterodyne technique having excellent characteristics is widely used in high-end commercial laser interferometers. However, this requires some additional optics, which makes the devices large, expensive, and difficult in manufacturing and usage. In the current project a new powerful technique has been developed, which does not require additional optics and uses a simple modulation scheme. The interference of two modulated light waves generates a heterodyne-like signal, with the optical phase being transferred to an electrical carrier. This allows unambiguous phase detection by means of conventional (electronic) FM-signal processing, while the measurement signal is free from the accompanying AM-modulation. The new technique can be used with any two-beam interferometers as e.g. the Michelson or Mach-Zehnder ones. The new method has been applied to develop a new kind of 'self-mixing-interference' (SMI) sensor. It has a simple, contactless and compact setup with only one mirror at the target providing optical feddback into the laser, while the output signal is read from the monitor photodiode integrated into the laser head. With the new technique the unambiguous measurements of displacements and velocities with a linearity error below 10 nm could be achieved. (orig.)SIGLEAvailable from TIB Hannover: F98B1942+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman