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Experimental demonstration of velocimetry by actively stabilised coherent optical transfer
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  • Benjamin Dix-Matthews ,
  • David Gozzard ,
  • Skevos Karpathakis ,
  • Shane Walsh ,
  • Ayden McCann ,
  • Alex Frost ,
  • Sascha Schediwy
Benjamin Dix-Matthews
The University of Western Australia

Corresponding Author:[email protected]

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David Gozzard
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Skevos Karpathakis
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Shane Walsh
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Ayden McCann
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Alex Frost
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Sascha Schediwy
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We report on the development of a system called velocimetry by actively stabilised coherent optical transfer (VASCOT) that is capable of overcoming these challenges. VASCOT optically tracks the phase of the returned signal to allow for narrow-band photo-detection, thus transferring the requirements on the photodetector bandwidth to the phase-tracking bandwidth. The pointing challenges are handled by an active tracking terminal capable of suppressing angular pointing errors to the moving target. VASCOT is  experimentally demonstrated over a 584 m atmospheric link to a corner-cube retro-reflector (CCR) on an airborne drone, with cycleslip-free phase tracking achieved for the three minute experiment. It was shown that the in-line target velocity measurement could achieve residual uncertainties below 2 nm/s within 5 s of averaging. VASCOT was also able to provide an absolute range measurement with a statistical error of ±13.7 mm, that agreed with an independent GPS-derived range measurement to within the uncertainty of the GPS module.