23 July 1993 Optical heterodyne profilometer used in industry enviroment
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Proceedings Volume 1983, 16th Congress of the International Commission for Optics: Optics as a Key to High Technology; 1983BT (1993) https://doi.org/10.1117/12.2308844
Event: 16th Congress of the International Commission for Optics: Optics as a Key to High Technology, 1993, Budapest, Hungary
Abstract
Faraday polarization modulator associated with a photovoltaic detector - Si or InGaAs for V or near IR spectrum, respectively - and a lock-in amplifier allows high accuracy measurements when used in optical devices such as ellipsometers or polarimeters. Linear or elliptical polarization azimuths can be detected with a sensitivity as high as 0.001°. Commercially available modulators always make use of a solid active material (para or diamagnetic glasses for the visible spectrum and ytrium or bismuth garnets for the IR spectrum). They always exhibit more or less stray birefringences due to residual stress in the solid state. Then, of course, the precision of the measurements is altered. To avoid this defect, we have designed, and used in high precision optical devices, modulators based on liquid active materials (e. g. a rod of water multipassed by light) (1) or on magnetic liquids (e. g. Fe2 C004 particles in CC14) (2) for the near I.R. spectrum. We present in this paper two new applications of these high precision optical devices using a liquid Faraday modulator : a method for calibrating optical retarders and a method for the measurements of linear dichroism and birefringence whether they are natural or induced.
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Xiang Li, Xiang Li, } "Optical heterodyne profilometer used in industry enviroment", Proc. SPIE 1983, 16th Congress of the International Commission for Optics: Optics as a Key to High Technology, 1983BT (23 July 1993); doi: 10.1117/12.2308844; https://doi.org/10.1117/12.2308844
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