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Proceedings Paper

Improving a commercially available heterodyne laser interferometer to sub-nm uncertainty
Author(s): Han Haitjema; Suzanne J. A. G. Cosijns; N. J. J. Roset; Maarten J. Jansen
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Paper Abstract

Laser interferometer systems are known for their high resolution, and especially for their high range/resolution ratio. In dimensional metrology laboratories, laser interferometers are popular workhorses for the calibration of displacements. The uncertainty is usually limited to about 10 nm due to polarization- and frequency mixing. For demanding applications however nanometer uncertainty is desired. We adapted a commercially available heterodyne laser interferometer by feeding the measurement signal into a fast lock-in amplifier and use the laser interferometer reference signal as a reference. By measuring both the in-phase and quadrature component an uncorrected phase can be directly measured. By recording both components while the phase changes between 0 and 2π a typical ellipse is recorded from which the first and second harmonics of periodic deviations can be derived. These can be corrected independent of their origin. Measurements show that this method can reduce severe non-linearities (40 nm top-bottom) to a standard deviation of about 0.02 nm. Also, optical set-ups can be analysed to predict the non-linearities when a non-compensated standard interferometer is used.

Paper Details

Date Published: 20 November 2003
PDF: 8 pages
Proc. SPIE 5190, Recent Developments in Traceable Dimensional Measurements II, (20 November 2003); doi: 10.1117/12.508542
Show Author Affiliations
Han Haitjema, Technische Univ. Eindhoven (Netherlands)
Suzanne J. A. G. Cosijns, Technische Univ. Eindhoven (Netherlands)
N. J. J. Roset, Technische Univ. Eindhoven (Netherlands)
Maarten J. Jansen, Technische Univ. Eindhoven (Netherlands)

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

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