Interferometric displacement tracking based on Hilbert transform processing

John P. Harkin; Donal A. Flavin

doi:10.1117/12.417397

1 March 2001 Interferometric displacement tracking based on Hilbert transform processing

John P. Harkin, Donal A. Flavin

Proceedings Volume 4204, Fiber Optic Sensor Technology II; (2001) https://doi.org/10.1117/12.417397
Event: Environmental and Industrial Sensing, 2000, Boston, MA, United States

Abstract

We propose and demonstrate an interferometric technique for the high precision measurement of displacement, based on Hilbert transform processing of the interferometric signal. The experimental arrangement is that of a laser illuminated Michelson interferometer in which a mirror, mounted on the target under test, is a component mirror of the interferometer. The optical configuration retains the simplicity of the fringe counting arrangement. Using standard sampling electronics, we capture the high coherence interferogram for the target motion to be analysed. We process the sampled interferogram, using Hubert transform techniques to generate the complex analytic signal of the real valued interferogram. The phase of the complex signal is extracted, unwrapped, and converted to displacement information corresponding to each sampling instant. We have achieved a X/100 for the individual displacement measurements, for analysis of a 1OOOtm travel of the target. In all cases, the displacement data is readily processed to measure velocity and acceleration. We report on both bulk optic and fibre optic versions of the interferometer. We have applied the technique to the characterisation of the motion of translation stages, with the objective of assessing their potential efficacy in temporally scanned interferometers. We report on our measurements of the consistency of scan rate and on the degree of 'out-of-plane' motion of the stages.

Citation Download Citation

John P. Harkin and Donal A. Flavin "Interferometric displacement tracking based on Hilbert transform processing", Proc. SPIE 4204, Fiber Optic Sensor Technology II, (1 March 2001); https://doi.org/10.1117/12.417397

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