Diode laser based speckle interferometry for dimensional measurements

In Electronic Speckle-Pattern Interferometry (ESPI) the utilization of tuneable diode lasers enables us to measure the 3D topography of technical freeform surfaces. The resolution of this so-called Two Wavelength ESPI (TWESPI) depends decisively on the tuneable wavelength range of the used laser source. With a Distributed-Bragg-Reflector Laser (DBR-Laser) shape measurements were carried out successfully. In this paper new methods for the extension of the measurement range, for phase-shifting and for calibration purposes will be presented. Moreover a set-up for the combined measurement of deformation and shape will be introduced and the obtained results will be shown.