31 May 2007 Absolute position sensor using Gaussian beam propagation properties and their spatial modulation
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Abstract
Authors propose a new approach in displacement measurements based on Gaussian beam propagation, their focusing properties and their spatial modulation. Two modulated Gaussian beams with a phase shift of 180° are focused on a slit fixed to the moveable object. The resulting laser beams at the slit output are focused into a multimode fiber. A lock-in amplifier demodulates the photodiode signal placed at the multimode fiber output. The lock in-amplifier output signal is a function of the slit displacement. The sensor is completely fibered with no electrical wires so it presents no heat dissipation near the moveable object and is compatible with vacuum use. It is a contactless sensor and provides a simple compact design and cost-effective means of achieving high resolution absolute displacement measurements. The preliminary experimental data of the sensor calibration by laser interferometry have shown a resolution of 0.1 nm.
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Darine Haddad, Darine Haddad, Patrick Juncar, Patrick Juncar, Gérard Genevès, Gérard Genevès, Patrick Pinot, Patrick Pinot, } "Absolute position sensor using Gaussian beam propagation properties and their spatial modulation", Proc. SPIE 6585, Optical Sensing Technology and Applications, 65850U (31 May 2007); doi: 10.1117/12.723033; https://doi.org/10.1117/12.723033
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