Synthetic wavelength based transportable telemeter with submicrometer resolution

We describe a transportable system based on synthetic wavelength interferometry for absolute distance measurement. The synthetic wavelength is generated using two frequency-doubled Nd:YAG lasers. Main feature is the elimination of polarization cross-talk issue using a setup where spatial separation is preferred to polarization separation. A superheterodyne technique has been implemented to detect the synthetic phase, enabling a fringe interpolation of ~2 pi/5600. A resolution of 700 nm over 60 s of integration time is demonstrated for a synthetic wavelength of 7,5 mm. An accuracy better than 10 μm is demonstrated over 25 m, based on an indoor comparison with a classical fringe counting interferometer at VSL (Netherlands).
article based on oral presentation at the conference MacroScale 2011 "Recent developments in traceable dimensional measurements", Bern-Wabern (Switzerland), 04-06, October, 2011