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arXiv · 2405.02306

A compact and open-source microcontroller-based rapid auto-alignment system

Yanda Geng·Alan Tsidilkovski·Kevin Weber·Shouvik Mukherjee·Alessandro Restelli·Sarthak Subhankar
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Abstract

Maintaining stable and precise alignment of a laser beam is crucial in many optical setups. In this work, we present a microcontroller-based rapid auto-alignment system that detects and corrects for drifts in a laser beam trajectory using a pair of two-dimensional duo-lateral position sensing detectors (PSDs) and a pair of mirror mounts with piezoelectric actuators. We develop hardware and software for interfacing with the PSDs and for controlling the motion of the piezoelectric mirrors mounts. Our auto-alignment strategy -- implemented as a state machine on the microcontroller by a FreeRTOS kernel -- is based on a simple linearized geometrical optical model. We benchmark our system using the standard case of coupling laser light efficiently into the guided mode of a single-mode fiber optic patch cable. We can recover the maximum fiber coupling efficiency in $\sim10$ seconds, even for a laser beam that was misaligned to the point of zero fiber coupling.

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Yanda Geng, Alan Tsidilkovski, Kevin Weber, Shouvik Mukherjee, Alessandro Restelli, Sarthak Subhankar. 2024-03-22. A compact and open-source microcontroller-based rapid auto-alignment system. https://doi.org/10.1063/5.0211005

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