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Opt Express. 2012 Feb 27;20(5):5658-82. doi: 10.1364/OE.20.005658.

Absolute distance measurement with micrometer accuracy using a Michelson interferometer and the iterative synthetic wavelength principle.

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  • 1The General Engineering Research Institute (GERI), Liverpool John Moores University, Byrom Street, Liverpool, L3 3AF, UK.


We present a novel system that can measure absolute distances of up to 300 mm with an uncertainty of the order of one micrometer, within a timeframe of 40 seconds. The proposed system uses a Michelson interferometer, a tunable laser, a wavelength meter and a computer for analysis. The principle of synthetic wave creation is used in a novel way in that the system employs an initial low precision estimate of the distance, obtained using a triangulation, or time-of-flight, laser system, or similar, and then iterates through a sequence of progressively smaller synthetic wavelengths until it reaches micrometer uncertainties in the determination of the distance. A further novel feature of the system is its use of Fourier transform phase analysis techniques to achieve sub-wavelength accuracy. This method has the major advantages of being relatively simple to realize, offering demonstrated high relative precisions better than 5 × 10(-5). Finally, the fact that this device does not require a continuous line-of-sight to the target as is the case with other configurations offers significant advantages.

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