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Proceedings Paper

Interferometric calibration of microdisplacement actuators
Author(s): Gian Bartolo Picotto
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Paper Abstract

The interferometer set-up in use at IMGC for the calibration of microdisplacement actuators is driven by a computer-based loop control of the out-of-phase between the reference and the measuring signal of the interferometer. In such a way, the displacements are changed in steps of λ of the optical path difference (OPD) and the periodic non-linearity error of the heterodyne interferometer is minimised. Nevertheless, with a double-pass optical configuration a few sampling points are available for the calibration of small displacements in the sub-wavelength range. The non-linearity has a period of λ in terms of optical path change and is due to optical mixing of the two beam frequency components in the two arms of the interferometer. Some methods have been proposed to compensate the optical non-linearity. An approach based on fast phase-shifting to zero-fill the phase difference of the heterodyne beat signals at each sub-wavelength displacement to be measured, is discussed in this contribution. Use is made of a transverse electro-optic modulator for phase shifting the path of the measuring beam of the heterodyne interferometer. The preliminary results shows a significant reduction of the non-linearity in the full sub-wavelength range.

Paper Details

Date Published: 20 November 2003
PDF: 6 pages
Proc. SPIE 5190, Recent Developments in Traceable Dimensional Measurements II, (20 November 2003); doi: 10.1117/12.505909
Show Author Affiliations
Gian Bartolo Picotto, Istituto di Metrologia Gustavo Colonnetti, CNR (Italy)

Published in SPIE Proceedings Vol. 5190:
Recent Developments in Traceable Dimensional Measurements II
Jennifer E. Decker; Nicholas Brown, Editor(s)

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