Abstract
ABSTRACT For high speed quality control in production we had developed a novel approach for fast ellipsometric measurements. Instead of a conventional setup that uses a standard photo-elastic modulator, we use a Single Crystal Photo-Elastic Modulator (SCPEM), for which in this case a LiTaO 3 -crystal is used. Instead of an analog Lock-In Amplifier, an automated digital processing based on a fast analog to digital converter is used. This small, simple, and cost-effective solution with its extremely compact and efficient polarization modulation allows fast ellipsometric testing where the upper limit of measurement rates is only limited by the desi red accuracy and repeatability of the measurements. Now we present an extension of this measurement from 635nm in the VIS to 1064nm in the NIR and discuss the related problems with signal measurement and re tardation control. Further the system speed was enhanced by onboard processing, such that now a sampling rate of 40 kHz is possible. Keywords: Ellipsometry, Modulators, LiTaO
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