High-accuracy longitudinal position measurement using self-accelerating light

TL;DR

This paper introduces a novel method using radially self-accelerating light beams for high-accuracy, stable longitudinal position measurements over millimeter ranges, combining simulation and experimental validation.

Contribution

It demonstrates a new approach employing spiraling intensity patterns of self-accelerating beams for precise distance measurement using simple detectors.

Findings

Achieved ~2 μm accuracy over 2 mm range

Utilized single-beam interference with static generation

Enabled high-speed, stable longitudinal measurements

Abstract

Radially self-accelerating light exhibits an intensity pattern that describes a spiraling trajectory around the optical axis as the beam propagates. In this article, we show in simulation and experiment how such beams can be used to perform a high-accuracy distance measurement with respect to a reference using simple off-axis intensity detection. We demonstrate that generating beams whose intensity pattern simultaneously spirals with fast and slow rotation components enables a distance measurement with high accuracy over a broad range, using the high and low rotation frequency, respectively. In our experiment, we achieve an accuracy of around 2~$\mu$m over a longitudinal range of more than 2~mm using a single beam and only two quadrant detectors. As our method relies on single-beam interference and only requires a static generation and simple intensity measurements, it is intrinsically stable and might find applications in high-speed measurements of longitudinal position.