Distance measurement using frequency sweeping interferometry is an absolute distance measurement technique that allows for high accuracy over long distances. Notwithstanding, the measurement accuracy is affected by laser sweeping nonlinearity and limited sweeping range. In this work, an optimized post-processing linearization method is demonstrated to realize high-accuracy arbitrary distance measurement using a laser with small modulation range. The interference signal is sparsely resampled to eliminate the influence of the sweeping nonlinearity, and the absolute distance is obtained by analyzing the phase of the resampled signal. In the measurement system, a high-finesse Fabry-Pérot cavity placed in vacuum is used as the measurement reference, so the effect of dispersion mismatch is negligible. Moreover, the distance measurement result is determined by the linear fit of the phase of each resampled point. Therefore, the influence of target vibration and other external random noise can be partially eliminated, and the reliability of the result is high. In the experiment, the sweeping range of the laser source is only 88 GHz. Comparing with a fringe-counting interferometer, the standard deviation of the residual errors is 34 µm within a distance of 6.7 m.

The measurement of distance plays an integral part in many aspects of modern societies. In this paper an integrated mode-locked laser on a chip is used for distance measurement based on mode-resolved interferometry. The emission from the on-chip source with a repetition rate of 2.5 GHz and a spectral bandwidth of 3 nm is coupled into a Michelson interferometer. The interferometer output is recorded as a spectral interferogram, which is captured in a single camera image. The images are analyzed using Hilbert transform to extract the distance. The distance derived shows a deviation of 6 \mum from the reference, for a distance up to 25 mm. We also demonstrate interferometry with repetition frequency sweep which can also be used with the source. Performance is expected to be better in the near future with the rapid developments in the field of on-chip laser sources which are demonstrating larger spectral widths and coherence lengths.

A highly miniaturized, single-chip, large scanning range MOEMS scanner is demonstrated. This intrinsically-aligned, monolithically integrated device uses small angular displacement to provide a linear scanning range of 2000 μm in the lateral and 1000 μm in the vertical direction, at a working distance of 2 cm, with an average operating power lower than 170 mW. Within a footprint of only 7×10 mm², the presented system fully integrates a photonic interferometer comprising a mirror, a silicon microlens and the MEMS actuator into a single chip, thus offering an unprecedentedly miniaturized scanning solution. The monolithic integration of all photonic components provides intrinsic alignment and excludes coupling losses often encountered in systems composed of discrete parts. No additional attenuation of the optical signal is observed during device operation. This small and high-performance device is suitable as complete system-on-chip for commercial, portable imaging applications.