Title: Linearisation of counting interferometers with 0.1 nm precision

Authors: Petr Kien

Addresses: Quantum Metrology of Length Department, Czech Metrology Institute, V Botanice 4, 15072 Prague 5, Czech Republic

Abstract: The paper describes a simple method for linearising interference fringes interpolation of quadru-phase detectors (QPD) used in homodyne counting laser interferometers. The linearisation of displacement measurement is obtained without any additional equipment by means of fitting ellipse to signals from QPD and removing eccentricity by calculated correction. Residual non-linearity less than 0.1 nm can be achieved by this method. The results from the experimental data obtained in interferometrical comparator IK-1 are presented. However, these preliminary results show that a circle is not always correct as an ideal counting interferometer signal.

Keywords: interferometry; nanometrology; regression; fringe interpolation; linearity; displacement; nanotechnology; interference fringes; quadru-phase detectors; QPD; homodyne counting; laser interferometers.

DOI: 10.1504/IJNT.2007.015465

International Journal of Nanotechnology, 2007 Vol.4 No.6, pp.702 - 711

Published online: 18 Oct 2007 *

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